@article{liu_xian_zhang_gao_shi_zhou_deng_hou_geng_ye_2022, title={A Mixed-Ligand Strategy to Modulate P3HT Regioregularity for High-Efficiency Solar Cells}, volume={55}, url={https://doi.org/10.1021/acs.macromol.1c02404}, DOI={10.1021/acs.macromol.1c02404}, abstractNote={Sustainable synthesis of polythiophenes (e.g., P3HT) is highly desired for the development of low-cost organic solar cells. Regulating the regioregularity of P3HT is a promising way to boost its performance. Yet, few eco-friendly methods can prepare P3HT with tunable regioregularity. Herein, we put forward a facile strategy to finely modulate the regioregularity of P3HT from 90% to 98% by tuning the molar ratio of two ligands in direct arylation polycondensation. Moreover, the ligand effect on regioregularity is well elucidated with DFT calculations, and the regioregularity effect of P3HT in non-fullerene solar cells is clarified for the first time. Our calorimetric, microscopic, and scattering results show that regioregularity strongly impacts the polymer crystallinity and phase separation, and device performance of the blend films. The P3HT batch with a regioregularity of 95% yields an unprecedented power conversion efficiency of 10.82%. Importantly, this realization firmly provides optimism for cheap materials such as polythiophenes, which are made via eco-friendly polycondensation for the application of solar cells and beyond.}, number={8}, journal={Macromolecules}, publisher={American Chemical Society (ACS)}, author={Liu, Yang and Xian, Kaihu and Zhang, Xuwen and Gao, Mengyuan and Shi, Yibo and Zhou, Kangkang and Deng, Yunfeng and Hou, Jianhui and Geng, Yanhou and Ye, Long}, year={2022}, month={Apr}, pages={3078–3086} }
@article{li_liu_wu_qi_zhang_meng_hu_ye_chen_2022, title={A general enlarging shear impulse approach to green printing large-area and efficient organic photovoltaics}, url={https://doi.org/10.1039/D2EE00639A}, DOI={10.1039/D2EE00639A}, abstractNote={The shear impulse strategy is an effective strategy that optimizes the morphology of the active layer by varying the MGC speed, resulting in a remarkable PCE of 17.15%.}, journal={Energy & Environmental Science}, author={Li, Haojie and Liu, Siqi and Wu, Xueting and Qi, Qingchun and Zhang, Haiyang and Meng, Xiangchuan and Hu, Xiaotian and Ye, Long and Chen, Yiwang}, year={2022} }
@article{gao_zhang_he_jiang_li_qi_zhou_chen_zhao_ye_2022, title={A generic approach yields organic solar cells with enhanced efficiency and thermal stability}, url={https://doi.org/10.1002/agt2.289}, DOI={10.1002/agt2.289}, abstractNote={Abstract The use of deuterium are critical for promoting the fundamental understanding of aggregate materials and their new functions. Particularly, the solution structure of conjugated polymers can be hardly resolved without deuteration. However, studies about the isotopic effects of casting solvents on the aggregated structures of photovoltaic polymers and their bulk‐heterojunction blends are deficient. Here, the impact of deuterated solvents on the thermal behavior, aggregated structures, and device performance of photovoltaic polymers is clearly delineated for the first time by multiple techniques. The enhanced π‐π stacking order of photovoltaic polymers is highly relevant to their relatively poor miscibility with deuterated solvents. Benefiting from higher crystallinity and optimized morphology of deuterated solvents processed films, the devices are able to achieve better efficiency and notable improvement in thermal stability. Our results highlight the isotopic effects of solvents on the aggregated structure of conjugated polymer systems and reveal the potential of innovative approaches to fabricate thermally stable high‐efficiency solar cells.}, journal={Aggregate}, author={Gao, Mengyuan and Zhang, Kai and He, Chunyong and Jiang, Hanqiu and Li, Xiong and Qi, Qingchun and Zhou, Kangkang and Chen, Yu and Zhao, Wenchao and Ye, Long}, year={2022}, month={Nov} }
@article{ma_zhou_sun_liu_kan_xiao_peña_li_zou_xing_et al._2022, title={Achieving high efficiency and well-kept ductility in ternary all-polymer organic photovoltaic blends thanks to two well miscible donors}, volume={5}, url={http://dx.doi.org/10.1016/j.matt.2021.12.002}, DOI={10.1016/j.matt.2021.12.002}, abstractNote={All-polymer solar cells (APSCs) are one of the most promising types of application-oriented photovoltaic technologies because they are operationally and mechanically stable; however, their low power conversion efficiency (PCE) restricts the core competitiveness against other types of solar cells. Besides, poor insight of mechanical performance, such as ductility, has been revealed for cutting-edge APSCs. Herein, we chose two well miscible polymer donors, PM6 and J71, and achieved a PCE of 16.52% for APSCs in a ternary blend with PY-IT and 15.74% for air-processed devices. The improvement is enabled by effective energy transfer, tuned crystallinity, and improved phase separation, which resulted in faster charge transfer and more balanced charge transport, suppressed exciton recombination, and more efficient charge extraction. Furthermore, the good miscibility between two donors enabled the target to have well-maintained film morphology without damaging the initial nanoscale network, bringing comparable film ductility. Last, the inner structure-property relationship of photovoltaic and morphological parameters, and film ductility was illustrated by a correlation study.}, number={2}, journal={Matter}, publisher={Elsevier BV}, author={Ma, Ruijie and Zhou, Kangkang and Sun, Yanna and Liu, Tao and Kan, Yuanyuan and Xiao, Yiqun and Peña, Top Archie Dela and Li, Yixin and Zou, Xinhui and Xing, Zengshan and et al.}, year={2022}, month={Feb}, pages={725–734} }
@article{liu_qiao_zhou_wang_gui_xian_gao_yin_hao_zhou_et al._2022, title={An Aggregation‐Suppressed Polymer Blending Strategy Enables High‐Performance Organic and Quantum Dot Hybrid Solar Cells}, volume={4}, url={http://dx.doi.org/10.1002/smll.202201387}, DOI={10.1002/smll.202201387}, abstractNote={Solution-processing hybrid solar cells with organics and colloidal quantum dots (CQDs) have drawn substantial attention in the past decade. Nevertheless, hybrid solar cells based on the recently developed directly synthesized CQD inks are still unexplored. Herein, a facile polymer blending strategy is put forward to enable directly synthesized CQD/polymer hybrid solar cells with a champion efficiency of 13%, taking advantage of the conjugated polymer blends with finely optimized aggregation behaviors. The spectroscopic and electrical investigations on carrier transport and recombination indicate that polymer blends can endow fast carrier transport and less recombination over the single counterparts. Moreover, the blending strategy offers a "dilution effect" for top-notch photovoltaic polymers with excessively strong aggregation tendency, resulting in moderate feature domain size and surface roughness, which afford fast hole transport and therefore high photovoltaic performance. The effectiveness of this strategy is successfully validated using two pairs of photovoltaic polymers. Accordingly, the relationships between polymer morphology, carrier transport, and photovoltaic performance are established to advance the progress of CQD/polymer hybrid solar cells. Such progress stresses that the utilization of aggregation-suppressed polymer blends is a facile approach toward the fabrication of high-efficiency organic-inorganic hybrid solar cells.}, journal={Small}, publisher={Wiley}, author={Liu, Junwei and Qiao, Jiawei and Zhou, Kangkang and Wang, Jingjing and Gui, Ruohua and Xian, Kaihu and Gao, Mengyuan and Yin, Hang and Hao, Xiaotao and Zhou, Zhihua and et al.}, year={2022}, month={Apr}, pages={2201387} }
@article{an in situ film to film transformation approach toward highly crystalline covalent organic framework films_2022, url={https://publons.com/wos-op/publon/52987656/}, DOI={10.31635/CCSCHEM.021.202101025}, abstractNote={Open AccessCCS ChemistryCOMMUNICATION1 May 2022An In Situ Film-to-Film Transformation Approach toward Highly Crystalline Covalent Organic Framework Films Yongkang Lv, Yusen Li, Guang Zhang, Zhongxiang Peng, Long Ye, Yu Chen, Ting Zhang, Guolong Xing and Long Chen Yongkang Lv Department of Chemistry, Institute of Molecular Plus, Tianjin Key Laboratory of Molecular Optoelectronic Science, Tianjin University, Tianjin 300072 Google Scholar More articles by this author , Yusen Li Department of Chemistry, Institute of Molecular Plus, Tianjin Key Laboratory of Molecular Optoelectronic Science, Tianjin University, Tianjin 300072 Google Scholar More articles by this author , Guang Zhang Department of Chemistry, Institute of Molecular Plus, Tianjin Key Laboratory of Molecular Optoelectronic Science, Tianjin University, Tianjin 300072 Google Scholar More articles by this author , Zhongxiang Peng School of Materials Science and Engineering, Tianjin University, Tianjin 300072 Google Scholar More articles by this author , Long Ye School of Materials Science and Engineering, Tianjin University, Tianjin 300072 Google Scholar More articles by this author , Yu Chen Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 Google Scholar More articles by this author , Ting Zhang Department of Chemistry, Institute of Molecular Plus, Tianjin Key Laboratory of Molecular Optoelectronic Science, Tianjin University, Tianjin 300072 Google Scholar More articles by this author , Guolong Xing Department of Chemistry, Institute of Molecular Plus, Tianjin Key Laboratory of Molecular Optoelectronic Science, Tianjin University, Tianjin 300072 Google Scholar More articles by this author and Long Chen *Corresponding author: E-mail Address: [email protected] Department of Chemistry, Institute of Molecular Plus, Tianjin Key Laboratory of Molecular Optoelectronic Science, Tianjin University, Tianjin 300072 Google Scholar More articles by this author https://doi.org/10.31635/ccschem.021.202101025 SectionsSupplemental MaterialAboutAbstractPDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareFacebookTwitterLinked InEmail Fabrication of highly crystalline covalent organic framework (COF) films with tunable thickness and good substrate adaptability remains a substantial challenge. Here, we have developed an effective approach for fabricating crystalline COF films based on elaborately designed bifunctional A2B2 monomers. Typically, amorphous drop-casted monomer [e.g., 1,4-bis(4-formylphenyl)-2,5-bis((4-aminophenyl)ethynyl))benzene (BFBAEB)] films were directly transformed into corresponding highly crystalline BFBAEB-COF film upon in situ vapor-assisted self-polycondensation in high yields (93–97%). The thickness of the BFBAEB-COF film could be modulated readily by varying the monomer concentration. These crystalline COF films could be grown on various substrates, including silicon, indium-doped tin oxide (ITO), glass, and gold. Moreover, such an in situ film-to-film transformation approach has been demonstrated as versatile and applicable to different A2B2 monomers. This work provides a novel pathway toward homogeneous and highly crystalline COF films, representing a key step forward to explore the application of COFs. Download figure Download PowerPoint Introduction Covalent organic frameworks (COFs) are a burgeoning class of porous crystalline polymers, typically obtained as polycrystalline but unprocessable powders.1–4 The predesigned regular structures and ordered open channels enable COFs with abundant tailored functionalities such as efficient charge transfer and proton conduction, endowing COFs as promising candidates for optoelectronics,5–7 energy storage,8,9 and so forth.10,11 It is well known that the film qualities of active layers play vital roles in electronic devices. The insolubilities of COFs in common solvents impede the film fabrication via well-developed wet-processing techniques. In this regard, much effort has been devoted to exploring new approaches to construct COF films such as in situ growth on specific substrates,12,13 interfacial polymerization,14–19 physical/chemical exfoliation,20–23 electrophoretic deposition,24,25 and others.26 Unfortunately, all the aforementioned methods still suffer from respective drawbacks. For instance, the difficulties in film-thickness control, prolonged reaction time, poor adaptability, and low production yield severely encumber the applications of COF films. Thus, green, efficient, and economic approaches for the fabrication of continuous and crystalline COF films are highly desired. Recently, we developed a “two-in-one” molecular design strategy in which a series of A2B2 monomers were utilized to synthesize COFs with excellent reproducibility and solvent adaptability.27–31 Thanks to the good solubilities of such A2B2 monomers and the ideal stoichiometry of the reactive groups, aspiring us to presume that it is possible to transform the A2B2 monomer film into crystalline COF film directly using appropriate protocols like vapor-assisted conversion.32 Herein, we proposed an in situ film-to-film transformation approach to fabricate crystalline COF films. As a proof of concept, a typical A2B2-type monomer: 1,4-bis(4-formylphenyl)-2,5-bis((4-aminophenyl)ethynyl))benzene (BFBAEB) was selected as the precursor on account of its high solubility [∼12.5 mg/mL in N,N-dimethylformamide (DMF)] and feasibility to afford highly crystalline bulk BFBAEB-COF readily.22 The general procedure was presented in Figure 1a and described as follows: BFBAEB was dissolved in DMF (8 mg/mL) to obtain a clear solution; afterward, 100 μL BFBAEB monomer solution was dropped on a clean Si wafer substrate (1 cm × 1 cm). After solvent evaporation under ambient conditions, a uniform yellow-colored BEBAEB monomer film was formed (Figure 1b, left). The resulted monomer film was placed into a 20 mL Schott Duran bottle which contained a 3 mL vial with a mixture of tetrahydrofuran (THF) and 6 M acetic acid (AcOH) (5:1, v/v). Subsequently, the Schott Duran bottle was transferred into an oven and heated at 85 °C for 24 h ( Supporting Information Figures S1, S2). After cooling to room temperature, the resulted dark brown BFBAEB-COF film on the Si wafer was washed thoroughly with DMF, ethanol and finally dried under reduced pressure (the inset picture in Figure 1b, right). Remarkably, almost quantitative monomer-to-COF conversions of 93–97% yields were achieved (see Supporting Information Table S1, Figure S45). Figure 1 | (a) Schematic illustration of the in situ film-to-film transformation approach. (b) Reaction scheme for fabricating BFBAEB-COF film by self-condensation of BFBAEB monomers. The inset pictures denote the film of BFBAEB monomer (left) and BFBAEB-COF film on Si wafer (1 cm × 1 cm, the monomer concentration is 8 mg/mL in DMF). Download figure Download PowerPoint Results and Discussion Fourier transform infrared (FT-IR), confocal Raman, and X-ray photoelectron spectroscopies (XPS) were employed to confirm the chemical composition of the BFBAEB-COF film. As shown in Figure 2a, the FT-IR spectra of BFBAEB-COF film showed a new signal at 1628 cm−1, corresponding to the characteristic stretching mode of –C=N linkages compared with that of BFBAEB monomer. Meanwhile, both the peaks of –C=O (1677 cm−1) and –NH2 (3365–3459 cm−1) stretching in the COF were significantly attenuated compared with those of the monomer. The few signals of amine and aldehyde group residues were attributed to the terminal groups in the frameworks of COFs.27,33 In addition, the IR spectra of the BFBAEB-COF film agreed well with that of BFBAEB-COF bulk powder synthesized by the solvothermal method.27 Raman spectra of the COF film also verified the formation of imine linkage due to the presence of a distinct band at ∼1583 cm−1 ascribed to the imines16,17,33 ( Supporting Information Figure S5). As depicted in Figure 2b, the XPS spectra displayed an N 1s band at 398.1 eV assignable to –C=N bonds, which again confirmed the successful formation of imine linkages in BFBAEB-COF film. Notably, the resulting BFBAEB-COF film was porous, stable, and could not be dissolved in common organic solvents like THF, DMF, which were suitable solvents for BFBAEB monomer ( Supporting Information Figures S7, S46 and S47). Collectively, these results suggested efficient monomer-to-framework conversion. Figure 2 | (a) FT-IR spectra comparison of the monomer and BFBAEB-COF film on Si wafer. (b) The XPS spectra of N 1s of BFBAEB-COF film on Si wafer. (c and d) SEM top views of BFBAEB-COF film on Si wafer. (The COF film was prepared with a monomer concentration of 8 mg/mL in DMF.) Download figure Download PowerPoint The morphology of the BEBAEB-COF film was investigated via scanning electron microscopy (SEM, Figure S8). As displayed in Figures 2c and 2d, the BFBAEB-COF film on Si wafer substrate showcased a homogeneous morphology and continuous coverage, consistent with the results from optical microscopy images ( Supporting Information Figure S7). A series of BFBAEB-COF films with different thicknesses (440 nm to 12 μm, Supporting Information Figure S9) were fabricated on Si wafers (1 cm × 1 cm) by modulating the concentration of BFBAEB (from 0.4 to 8 mg/mL). The cross-sectional SEM images revealed that all the BFBAEB-COF films on the Si wafers were continuous (Figures 3a–3c). Notably, there was almost a linear relationship between the concentration of the monomer and the thickness of the COF film ( Supporting Information Figure S10). Therefore, the thickness of BFBAEB-COF film could be regulated readily by varying the initial concentration of the A2B2-type monomer. Figure 3 | Cross-sectional SEM images of BFBAEB-COF films on Si wafers with a monomer concentration of (a) 8 mg/mL, (b) 4 mg/mL, and (c) 2 mg/mL. (d) Typical GIWAXS pattern of BFBAEB-COF film on Si wafer, prepared with a monomer concentration of 8 mg/mL in DMF. (e) Projections of GIWAXS data of BFBAEB-COF film (monomer concentration: 8 mg/mL in DMF) sets qxy = 0 (pink), BFBAEB monomer film (dark yellow), PXRD data of BFBAEB-COF powder (violet), and simulated AA-Stacking profile (royal blue). Download figure Download PowerPoint Synchrotron radiation-based two-dimensional grazing incidence wide-angle X-ray scattering (2D-GIWAXS) experiments were performed to evaluate the crystallinity and orientational order of the BFBAEB-COF film. As displayed in Figure 3d, the BFBAEB-COF film with a thickness of ∼12 μm shows intense reflections in the 2D-GIWAXS pattern, which discloses a good crystallinity of this film. Additionally, we observed that the intensities of in-plane Bragg peaks were almost identical to those of out-of-plane ones, which indicated that the BFBAEB-COF within the film had almost no preferential orientation. Projections of these datasets near qxy = 0 (Figure 3e) generated the peaks at 0.21, 0.43, 0.65, 0.87, 1.08, and 1.29 Å−1, assignable to the (100), (200), (300), (400), (140), and (610) reflection planes, respectively. The out-of-plane GIWAXS profiles were in good agreement with the results of powder X-ray diffraction (PXRD) of bulk BFBAEB-COF powder and simulated AA-stacking profiles. Moreover, all these BFBAEB-COF films fabricated from different monomer concentrations (0.4–8 mg/mL) manifested similar arc-like GIWAXS patterns ( Supporting Information Figure S14), which demonstrated high crystallinity but no favored orientation of these COF films. The increased intensity of the COF (100) reflection in GIWAXS patterns of the COF films (Figure S16) was probably attributable to the enhanced film thickness. The feasibility of growing COF films on different substrates would enable the practical applications of COF films in diverse fields. In this respect, indium-doped tin oxide(ITO), gold/glass, and glass were used as the substrates to prepare BFBAEB-COF films ( Supporting Information Figure S3). Remarkably, uniform and continuous BFBAEB-COF films could be formed on all substrates, as revealed by SEM images ( Supporting Information Figures S11–S13). Similarly, the thicknesses of the BFBAEB-COF films on these substrates could also be easily tuned by mediating the concentration of the monomer. Furthermore, the GIWAXS pattern and in-house grazing incidence XRD (GI-XRD) results indicated that the BFBAEB-COF films were crystalline with isotropic stacking on these substrates ( Supporting Information Figures S17–S20). However, we found that such a film-to-film transformation approach could not be applied to the conventional co-condensation of two different monomers for COF formation. For instance, when 1,2,4,5-tetra((4-aminophenyl)ethynyl)benzene (TAEB) and 1,2,4,5-tetra(4-formylphenyl)benzene (TFPB) were utilized as the cocondensation monomers, only amorphous oligomer films were afforded under the same conditions as that for the fabrication of BFBAEB-COF film (see Supporting Information Section 6, Figures S42–S44). It might be due to the inhomogeneous and disordered distributions of the two monomers with different solubility (TAEB ∼0.014 mmol/mL in DMF, TFPB ∼0.021 mmol/mL in DMF), for example, segregation of the two materials or aggregation of individual monomers on the substrate. Thus, A2B2 monomers are more advantageous for growing COF films using this in situ transformation strategy. To demonstrate the versatility of this film-to-film transformation approach, another two A2B2-type monomers, viz, 1,4-bis(4-formylphenyl)-2,5-bis(4-aminophenyl)benzene (BFBAB) and 1,6-bis(4-formylphenyl)-3,8-bis(4-aminophenyl)pyrene (BFBAPy) were applied to construct the corresponding COF films (Figures 4a and 4d). As expected, highly crystalline COF films with intense XRD peaks were obtained (Figures 4b, 4c, 4e, and 4f). FT-IR, confocal Raman, and XPS spectra all supported the successful formation of corresponding COF films ( Supporting Information Figures S22–S24 and S33–S35). The SEM and optical microscopy images suggested that the COF films produced were homogeneous with uniform thickness ( Supporting Information Figures S25–S27 and S36–S37). Similarly, the thicknesses of the respective COF films increased with increments in monomer concentrations. The high crystallinity of these COF films was demonstrated by 2D-GIWAXS and GI-XRD results ( Supporting Information Figures S28–S31 and S38–S41). Figure 4 | Reaction scheme for the self-condensation of BFBAPy-COF film (a) and BFBAB-COF film (d). 2D-GIWAXS patterns of BFBAPy-COF film (b) and BFBAB-COF film (e) obtained with a monomer concentration of 4 mg/mL on Si wafer. Projections of GIWAXS data of BFBAPy-COF film (c) and BFBAB-COF film (f) with a monomer concentration of 4 mg/mL on Si wafer. Download figure Download PowerPoint Conclusion An in situ film-to-film transformation approach was developed to fabricate highly crystalline COF films using A2B2 bifunctional monomers. Efficient conversion of the monomer films to corresponding crystalline COF films was realized in high yields (93–97%). Further, the thicknesses of the COF films could be tuned readily by varying the concentration of A2B2 precursors. Moreover, this novel approach is versatile and can be applied to different monomers and substrates such as Si wafer, glass, ITO, and gold. This work highlights a facile, effective, and general method to fabricate uniform and highly crystalline COF films from monomer films, thereby producing cost-effective processing solution techniques like drop-casting, spin-coating, and blade-coating, and so on, and thus, beneficial to explore the application scopes of COF films in the removal of organic pollutant, optoelectronic devices, and many other research fields. Supporting Information Supporting Information is available and includes experiment details and characterization of the monomer, BFBAEB-COF film, BFBAB-COF film, and BFBAPy-COF film. Conflict of Interest The authors declare no competing financial interests. 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Soc.2019, 141, 13822–13828. Google Scholar 28. Hao W.; Chen D.; Li Y.; Yang Z.; Xing G.; Li J.; Chen L.Facile Synthesis of Porphyrin Based Covalent Organic Frameworks via an A2B2 Monomer for Highly Efficient Heterogeneous Catalysis.Chem. Mater.2019, 31, 8100–8105. Google Scholar 29. Yan X.; Liu H.; Li Y.; Chen W.; Zhang T.; Zhao Z.; Xing G.; Chen L.Ultrastable Covalent Organic Frameworks via Self-Polycondensation of an A2B2 Monomer for Heterogeneous Photocatalysis.Macromolecules2019, 52, 7977–7983. Google Scholar 30. Zhang B.; Song X.; Li Y.; Li Y.; Peng Z.; Ye L.; Chen L.2D Covalent Organic Framework Thin Films via Interfacial Self-Polycondensation of An A2B2 Type Monomer.Chem. Commun.2020, 56, 3253–3256. Google Scholar 31. Li Y.; Guo L.; Lv Y.; Zhao Z.; Ma Y.; Chen W.; Xing G.; Jiang D.; Chen L.Polymorphism of 2D Imine Covalent Organic Frameworks.Angew. Chem. Int. Ed.2021, 60, 5363–5369. Google Scholar 32. Medina D. D.; Rotter J. M.; Hu Y.; Dogru M.; Werner V.; Auras F.; Markiewicz J. T.; Knochel P.; Bein T.Room Temperature Synthesis of Covalent–Organic Framework Films through Vapor-Assisted Conversion.J. Am. Chem. Soc.2015, 137, 1016–1019. Google Scholar 33. Sun B.; Zhu C.-H.; Liu Y.; Wang C.; Wan L.-J.; Wang D.Oriented Covalent Organic Framework Film on Graphene for Robust Ambipolar Vertical Organic Field-Effect Transistor.Chem. Mater.2017, 29, 4367–4374. Google Scholar Previous articleNext article FiguresReferencesRelatedDetails Issue AssignmentVolume 4Issue 5Page: 1519-1525Supporting Information Copyright & Permissions© 2021 Chinese Chemical SocietyKeywordsself-polycondensationCOF filmsA2B2 monomersin situ transformationAcknowledgmentsThis work was financially supported by the National Key Research and Development Program of China (grant no. 2017YFA0207500) and the Natural Science Foundation of China (grant no. 51973153). L.Y. and L.C. are grateful to access the beamline 1W1A of the Beijing Synchrotron Radiation Facility (BSRF). Downloaded 2,189 times PDF DownloadLoading ...}, journal={CCS Chemistry}, year={2022} }
@article{brominated polythiophene reduces the efficiency-stability-cost gap of organic and quantum dot hybrid solar cells_2022, url={https://publons.com/wos-op/publon/53064657/}, DOI={10.1002/AENM.202201975}, abstractNote={Abstract The emerging solution‐processed solar cells have attracted worldwide effort in the last decade. Developing efficient, stable, and cost‐effective solar cells is strongly desirable in countering the growing global warming. Nevertheless, the photovoltaic performance and stability of hybrid solar cells based on low‐cost polythiophenes are far from satisfactory, due to their high‐lying energy levels and excessive aggregation. Herein, it is shown that brominated polythiophene (P3HT‐Br), prepared via a facile two‐step approach can effectively facilitate charge transport and suppress recombination in quantum dot (QD)/organic heterojunctions. Accordingly, the power conversion efficiency of the optimized hybrid polythiophene/QD cell is boosted from 8.7% to 11% (a 26% increase) with markedly reduced energy loss. More strikingly, the device achieves record‐high thermal stability with a lifetime of over 400 h maintaining 80% of the initial performance. Both device efficiency and stability are the best reported for polythiophene/QD hybrid solar cells. Moving forward, brominated polythiophenes hold great application in perovskite solar cells with significantly improved performance and offer new opportunities for other emerging solar cells.}, journal={Advanced Energy Materials}, year={2022} }
@article{xian_liu_liu_yu_xing_peng_zhou_gao_zhao_lu_et al._2022, title={Delicate crystallinity control enables high-efficiency P3HT organic photovoltaic cells}, volume={10}, url={http://dx.doi.org/10.1039/d1ta10161g}, DOI={10.1039/d1ta10161g}, abstractNote={The time-dependent evolution of a P3HT:nonfullerene blend was revealed during annealing. The optimal blend gives 10.7%, which breaks the 10% benchmark for P3HT-solar cells.}, number={7}, journal={Journal of Materials Chemistry A}, publisher={Royal Society of Chemistry (RSC)}, author={Xian, Kaihu and Liu, Yang and Liu, Junwei and Yu, Jinde and Xing, Yifan and Peng, Zhongxiang and Zhou, Kangkang and Gao, Mengyuan and Zhao, Wenchao and Lu, Guanghao and et al.}, year={2022}, pages={3418–3429} }
@article{xiong_ye_zhang_2022, title={Eco‐friendly solution processing of all‐polymer solar cells: Recent advances and future perspective}, volume={60}, url={https://doi.org/10.1002/pol.20210745}, DOI={10.1002/pol.20210745}, abstractNote={Abstract All‐polymer solar cells (all‐PSCs) exhibit great potentials in commercial applications. All‐PSCs have observed steady performance gains with power conversion efficiency now reaching over 17% in the open literature. However, the current processing of all‐PSCs relies predominantly on toxic, chlorinated solvents in moisture‐free environments, representing a significant barrier for their commercialization due to the added costs to handle and dispose of such solvents. There is thus an urgent need for safe, environmentally benign, and sustainable ink‐based processing methods to produce all‐PSC devices reliably and reproducibly in ambient air. In this perspective, fundamental insights on the interplay between all‐polymer blend morphologies and eco‐friendly solvents are provided. Also, we discuss the recent successes of the green processing methods to manipulate the photoactive morphologies for high‐efficiency all‐PSCs. In the end, we provide an outlook on future challenges and opportunities of eco‐friendly solvents processed all‐PSCs for large‐scale manufacturing.}, number={6}, journal={Journal of Polymer Science}, publisher={Wiley}, author={Xiong, Yuan and Ye, Long and Zhang, Chao}, year={2022}, month={Mar}, pages={945–960} }
@article{low-cost and high-performance poly(thienylene vinylene) derivative donor for efficient versatile organic photovoltaic cells_2022, url={https://publons.com/wos-op/publon/53099554/}, DOI={10.1016/J.NANOEN.2022.107463}, abstractNote={The utilization of donor materials with complex structures obviously increases the costs of organic photovoltaic (OPV) cells. Therefore, low-cost and high-performance are two issues that must be considered when designing polymer donors for the preparations of large-area OPV cells. Here, a poly(thienylene vinylene) derivative, named PTVT-BT was reported. PTVT-BT has a very simple completely non-fused molecular structure. PTVT-BT shows planar molecular structure and obvious solution aggregation effect. Besides, PTVT-BT demonstrates a high hole mobility up to the magnitude of 10-2 cm-2 V-1 s-1. The external quantum efficiency of electroluminescence of PTVT-BT is 7 × 10-3. As a result, the OPV cell based on PTVT-BT:eC9 demonstrates a power conversion efficiency (PCE) of 16.31%, which is the highest value among the poly(thienylene vinylene)- and polythiophene-based OPV cells. The tandem OPV cell with PTVT-BT as the donor of the sub-cell yields an outstanding PCE of 18.49%. Besides, the indoor OPV cell based on PTVT-BT:BTA3 exhibits a PCE of 27.30% under a light-emitting diode (LED) illumination of 1000 lux (2700 K). This study indicates that PTV-derivative is a kind of promising material for the future OPV industrialization.}, journal={Nano Energy}, year={2022} }
@article{zhou_xian_ye_2022, title={Morphology control in high‐efficiency all‐polymer solar cells}, volume={4}, url={https://doi.org/10.1002/inf2.12270}, DOI={10.1002/inf2.12270}, abstractNote={Abstract All‐polymer solar cells (All‐PSCs) have attracted tremendous research interest in the recent decade due to the great potentials in stretchable electronic applications in terms of long‐term stability and mechanical stretchability. Driven by the molecular design of novel polymer acceptors and morphology optimization, the power conversion efficiency (PCE) of All‐PSCs has developed rapidly and now exceeded 17%. This review outlines the promising strategies for high‐performance All‐PSCs from the aspect of morphology control with the motivation to rationally guide the optimization. In this review, we briefly discuss the thermodynamic mixing principles of all‐polymer blends and the effects of the molecular structure of conjugated polymers on thin‐film morphology in All‐PSCs. The crucial role of molecular miscibility in influencing morphological features and performance metrics was highlighted. We also expound on the effective methods of controlling film morphology through properly tuning the aggregation behavior of polymers. In particular, insightful studies on the commonly used naphthalene diimide‐based acceptor polymers and the newly emerging polymerized nonfullerene small molecule acceptors (ITIC‐series, Y6 ‐series, etc) are discussed in detail. Finally, we present an outlook on the major challenges and the new opportunities of All‐PSCs for efficiency breakthroughs targeting 20%. image}, number={4}, journal={InfoMat}, publisher={Wiley}, author={Zhou, Kangkang and Xian, Kaihu and Ye, Long}, year={2022}, month={Apr} }
@article{gao_ma_liu_gao_qi_yu_gao_ma_ye_min_et al._2022, title={Novel Third Components with (Thio)barbituric Acid as the End Groups Improving the Efficiency of Ternary Solar Cells}, url={https://doi.org/10.1021/acsami.2c03196}, DOI={10.1021/acsami.2c03196}, abstractNote={Developing novel third component is critical for the ternary organic solar cells (TOSCs). Herein, we design and synthesize two novel third components, MAZ-1 and MAZ-2, with 1,3-diethyl-2-thiobarbituric acid and 1,3-dimethylbarbituric acid as the weak electron withdrawing end groups, respectively. Both MAZ-1 and MAZ-2 could improve the photovoltaic performance of the binary OSCs based on D18:Y6 which exhibit the power conversion efficiency (PCE) of 17%, because the third components can optimize the phase separation, suppress the bimolecular recombination, and decrease the nonradiative energy loss in ternary blends. The PCE of the optimized TOSCs approaches 18% along with the simultaneous increase in open circuit voltage, short circuit current density, and fill factor by incorporating 10 wt % MAZ-1 and MAZ-2 in acceptors. This work enriches the building blocks for novel third components for achieving highly efficient TOSCs.}, journal={ACS Applied Materials & Interfaces}, author={Gao, Xiang and Ma, Xiaoling and Liu, Zifeng and Gao, Jiaxin and Qi, Qingchun and Yu, Yue and Gao, Yang and Ma, Zaifei and Ye, Long and Min, Jie and et al.}, year={2022}, month={May} }
@article{previews the rise of polythiophene photovoltaics_2022, url={https://publons.com/wos-op/publon/52987655/}, DOI={10.1016/J.JOULE.2022.04.006}, abstractNote={Compared with prevailing photovoltaic polymers with complex structures and tedious synthesis, polythiophenes possess a greater commercial promise. However, their photovoltaic performances are rather poor due to mismatched energy levels and unfavorable mixing with state-of-the-art non-fullerene acceptors. In a recent Joule article, Duan and colleagues developed a new series of polythiophene-based donors (P5TCN-Fx) via just four steps and achieved a record-high efficiency that surpasses 17%. Furthermore, both polymer solubility and molecular miscibility were found to play crucial roles in achieving this unprecedented performance. The future perspectives are discussed.}, journal={Joule}, year={2022} }
@article{wang_liu_zhou_xian_qi_zhao_chen_ye_2022, title={Processing Poly(3‐Hexylthiophene) Interlayer with Nonhalogenated Solvents for High‐Performance and Low‐Cost Quantum Dot Solar Cells}, url={https://doi.org/10.1002/solr.202200779}, DOI={10.1002/solr.202200779}, abstractNote={Hybrid solar cells with organic semiconductors and quantum dots (QDs) have witnessed great advance in the past few years. Nevertheless, the great majority of organic and QD hybrid solar cells generally employ halogenated solvents for the processing of organic hole‐transporting interlayers. Herein, the impact of solvents on the organic semiconductor material for hybird solar cells is systematically explored. The o ‐xylene‐processed polythiophene delivers a champion photovoltaic performance of 8.7%, which is the record value for QD and poly(3‐hexylthiophene) (P3HT) hybrid solar cells. The morphology results reveal that P3HT films processed with o ‐XY present the moderate morphology and characteristic length scales, enabling the high photovoltaic performance. Moreover, the relationships between solvents, molecular stacking, film morphology, and photovoltaic performance are built to offer the guideline of solvents screening for these hybrid solar cells. Moreover, the great superiority of nonhalogenated solvents in fabricating high‐performance optoelectronic devices with low hazards is demonstrated.}, journal={Solar RRL}, author={Wang, Jingjing and Liu, Junwei and Zhou, Kangkang and Xian, Kaihu and Qi, Qingchun and Zhao, Wenchao and Chen, Yu and Ye, Long}, year={2022}, month={Nov} }
@article{gui_liu_chen_wang_chen_shi_zhang_qin_ye_hao_et al._2022, title={Reproducibility in Time and Space—The Molecular Weight Effects of Polymeric Materials in Organic Photovoltaic Devices}, volume={4}, url={http://dx.doi.org/10.1002/smtd.202101548}, DOI={10.1002/smtd.202101548}, abstractNote={The reproducibility issue is one of the major challenges for the commercialization of large-area organic electronic devices. It involves both the device-to-device variation and opto-electronic properties in different positions of a single thin film. Herein, the molecular weight effects in polymeric semiconductors with three widely used photovoltaic donor materials P3HT, PBDB-T, and PM6 are systematically investigated. A simple but effective method is proposed to evaluate the uniformity of large-area devices by adopting the micron-level grid electrodes in organic thin films. An interesting phenomenon is observed that the device is gradually improved uniformly with the Mw range lower than 100 kg mol-1 . In neat films, both the mobility and energetic disorder values of hole carriers exhibit relatively lower coefficient of variation (cv ) in high molecular-weight systems. After blending with the electron-accepting materials, their bulk heterojunction films also enjoy more uniform hole transfer rates, fluorescence lifetimes, and power conversion efficiencies in single and different devices. This work not only proposes a facile approach to evaluate the electrical properties of large-area organic thin films, but also demonstrates the relationship between molecular weight and device reproducibility in polymer solar cells. This contribution provides a new insight into the commercial large-scale production of organic electronics.}, journal={Small Methods}, publisher={Wiley}, author={Gui, Ruohua and Liu, Yang and Chen, Zhihao and Wang, Tong and Chen, Tao and Shi, Rui and Zhang, Kangning and Qin, Wei and Ye, Long and Hao, Xiaotao and et al.}, year={2022}, month={Apr}, pages={2101548} }
@article{qi_zhong_liu_gao_peng_li_zhao_ke_zhang_ye_2022, title={Revealing the Molar Mass Dependence on Thermal, Microstructural, and Electrical Properties of Direct Arylation Polycondensation Prepared Poly(3-hexylthiophene)}, volume={2}, url={https://doi.org/10.1021/acsapm.1c01651}, DOI={10.1021/acsapm.1c01651}, abstractNote={Poly(3-hexylthiophene) (P3HT) is a “fruit fly” conjugated polymer in the field of organic electronics due to its simple chemical structure, decent photoelectric properties, and low cost. To date, the design of nonfullerene acceptors matching P3HT and the synthesis of high-quality P3HT via sustainable methods hold tremendous promises for advancing the P3HT solar cells. The use of P3HT via direct arylation polycondensation (DArP) has recently proven to be an efficient means for constructing efficient polythiophene solar cells, while the intrinsic properties of DArP prepared P3HT remain poorly understood, thus impeding further performance enhancements. Herein, six batches of P3HTs with weight-average molecular weights from 8.5 to 73.9 kg/mol were successfully synthesized via DArP, and multitechnique characterizations were employed to investigate the molecular weight effect of P3HT on its optical properties, crystallization behaviors, morphology, and electrical properties. P-52k with relatively high crystallinity and hole mobility was applied in photovoltaic devices matching a variant of the popular nonfullerene acceptor Y6. This photovoltaic combination afforded a good power conversion efficiency of over 7% in P3HT/nonfullerene solar cells. Importantly, this research not only provides insights into the physical properties of DArP prepared P3HT as a function of molecular weight but reveals the correlation between the key structure parameter and the electrical performance of P3HT for optoelectronic applications as well.}, journal={ACS Applied Polymer Materials}, publisher={American Chemical Society (ACS)}, author={Qi, Qingchun and Zhong, Yuan and Liu, Yang and Gao, Mengyuan and Peng, Zhongxiang and Li, Saimeng and Zhao, Wenchao and Ke, Huizhen and Zhang, Jidong and Ye, Long}, year={2022}, month={Mar} }
@article{liu_xian_gui_zhou_liu_gao_zhao_jiao_deng_yin_et al._2022, title={Simple Polythiophene Solar Cells Approaching 10% Efficiency via Carbon Chain Length Modulation of Poly(3-alkylthiophene)}, volume={55}, url={http://dx.doi.org/10.1021/acs.macromol.1c02187}, DOI={10.1021/acs.macromol.1c02187}, abstractNote={Poly(3-alkylthiophene)s are the most extensively studied polymeric materials in organic and hybrid solar cells due to the unique advantages of extremely low cost in material synthesis. However, the inferior power conversion efficiencies (PCEs) are still the main obstacle in the commercial applications of poly(3-alkylthiophene)-based solar cells. In this contribution, the carbon chain length of poly(3-alkylthiophene) is modulated to reveal its impact on the molecular packing and charge transport behaviors in neat films and bulk heterojunction films with nonfullerene small-molecule acceptors for the first time. The odd–even effect can be clearly observed in poly(3-alkylthiophene):ZY-4Cl bulk heterojunction films, which has a great impact on the charge transport behavior and device performance. The poly(3-pentylthiophene) (P3PT) cell achieves a significantly high PCE of nearly 10% and a desirable fill factor of ∼71%, which are the highest values of P3PT-based solar cells to date. The boosted efficiency is attributed to the altered van der Waals surfaces of alkyl segments through density functional theory calculation. This work reveals the odd–even effects of the carbon chain length modulation on the molecular packing and interaction of polythiophene:nonfullerene blends, which casts a new light on optimizing low-cost polythiophene solar cells and other promising electronics.}, number={1}, journal={Macromolecules}, publisher={American Chemical Society (ACS)}, author={Liu, Yang and Xian, Kaihu and Gui, Ruohua and Zhou, Kangkang and Liu, Junwei and Gao, Mengyuan and Zhao, Wenchao and Jiao, Xuechen and Deng, Yunfeng and Yin, Hang and et al.}, year={2022}, month={Jan}, pages={133–145} }
@article{simultaneously enhanced efficiency and mechanical durability in ternary solar cells enabled by low-cost incompletely separated fullerenes_2022, url={https://publons.com/wos-op/publon/52191459/}, DOI={10.1002/MARC.202200139}, abstractNote={All-polymer solar cells (all-PSCs) are one of the most promising application-oriented organic photovoltaic technologies due to their excellent operational and mechanical stability. However, the power conversion efficiencies (PCEs) are mostly lower than 16%, restricting their core competitiveness. Furthermore, the improvement of mechanical durability is rarely paid attention to cutting-edge all-PSCs. This work deploys a low-cost "technical grade" PCBM (incompletely separated but pure mixtures containing ≥90% [70]PCBM or [60]PCBM), into the efficient PM6:PY-IT all-polymer blend, successfully yielding a high-performance ternary device with 16.16% PCE, among the highest PCE values for all-PSCs. Meanwhile, an excellent mechanical property (i.e., crack onset strain = 11.1%) promoted from 9.5% for the ternary system is also demonstrated. The "technical grade" PCBM slightly disrupts the crystallization of polymers, and disperses well into the amorphous polymer regions of the all-PSC blends, thus facilitating charge transport and improving film ductility simultaneously. All these results confirm introducing low-cost "technical grade" PCBM with high electron mobility into all-polymer blends can improve carrier mobility, reduce charge recombination, and optimize morphology of the amorphous polymer regions, thus yielding more efficient and mechanically durable all-PSCs.}, journal={Macromolecular Rapid Communications}, year={2022} }
@article{li_zhou_sun_zhao_ye_2022, title={Status and prospects of ternary all-polymer organic solar cells}, url={https://doi.org/10.1016/j.mtener.2022.101166}, DOI={10.1016/j.mtener.2022.101166}, abstractNote={All-polymer solar cells (all-PSCs) exhibit tremendous potential in fields such as smart and wearable electronic devices due to the benefits of low-cost, flexibility and large-area processability. Researches related to all-PSCs is mushrooming with the development of new polymeric donor and acceptor materials and the continuous optimization of active layer morphology and device performance. It is imperative to further boost the performance of all-PSCs with more productive methods. Ternary blend strategy is widely considered as a straightforward and effective method to optimize the morphology, photovoltaic efficiency and stability. In this review, we present the recent progress in three kinds of ternary blend based all-PSCs, namely, dual-donor and dual-acceptor ternary all-PSCs and the introduction of small-molecules in binary all-PSCs, and discuss in depth how the ternary strategy in all-PSCs can improve cell performance by optimizing film morphology and charge carrier transport properties, helping readers to better understand the morphology-efficiency/stability relationship. Simultaneously, we provide a concise discussion on the challenges and opportunities for the future development of ternary all-PSCs targeting 20% efficiency.}, journal={Materials Today Energy}, author={Li, Saimeng and Zhou, Kangkang and Sun, Bing and Zhao, Wenchao and Ye, Long}, year={2022}, month={Dec} }
@article{gao_liu_xian_peng_zhou_liu_li_xie_zhao_zhang_et al._2022, title={Thermally stable poly(3‐hexylthiophene): Nonfullerene solar cells with efficiency breaking 10%}, volume={3}, url={http://dx.doi.org/10.1002/agt2.190}, DOI={10.1002/agt2.190}, abstractNote={Abstract Solar cells featuring polythiophenes as donors are one of the optoelectronic devices that hold notable promises for commercial application, profiting from the lowest synthetic complexity and excellent scalability. However, the complex phase behaviors of polythiophenes and their blends put constraints on modulating electrical performance and thus realizing stable performance under thermal stress. In this contribution, we present a multi‐technique approach that combines calorimetry, scattering, spectroscopy, and microscopy to thoroughly probe the thermodynamic mixing, thermal properties of materials, the evolution of nanoscale domain structure, and device performance of poly(3‐hexylthiophene) (P3HT) with a range of nonfullerene acceptors (NFAs) such as ITIC, IDTBR, and ZY‐4Cl. Accordingly, two blending guidelines are established for matching these popular NFAs with P3HT to enable highly efficient and thermally stable cells. First, blend systems with weak vitrification and hypo‐miscibility are excellent candidates for efficient solar cells. Furthermore, high thermal stability can be achieved by selecting NFAs with diffusion‐limited crystallization. The P3HT:ZY‐4Cl blend was found to endow the best performance of over 10% efficiency and an exceptionally high T 80 lifetime of >6000 h under continuous thermal annealing, which are among the highest values for P3HT‐based solar cells. This realization of high thermal stability and efficiency demonstrates the remarkable potentials of simple polythiophene :nonfullerene pairs in electronic applications.}, journal={Aggregate}, publisher={Wiley}, author={Gao, Mengyuan and Liu, Yang and Xian, Kaihu and Peng, Zhongxiang and Zhou, Kangkang and Liu, Junwei and Li, Saimeng and Xie, Fei and Zhao, Wenchao and Zhang, Jidong and et al.}, year={2022}, month={Mar} }
@article{wu_wang_chen_xia_gao_shen_zhu_lu_ye_xia_et al._2022, title={Understanding the molecular mechanisms of the differences in the efficiency and stability of all-polymer solar cells}, url={https://doi.org/10.1039/D1TC05548H}, DOI={10.1039/D1TC05548H}, abstractNote={This work provides an in-depth insight into the rational selection of the P D s– P A s pair and fine-tuning of the active layer morphology, which is conducive to understanding the miscibility–morphology–function relations.}, journal={Journal of Materials Chemistry C}, publisher={Royal Society of Chemistry (RSC)}, author={Wu, Qiang and Wang, Wei and Chen, Zeng and Xia, Xinxin and Gao, Mengyuan and Shen, Hao and Zhu, Haiming and Lu, Xinhui and Ye, Long and Xia, Jianlong and et al.}, year={2022} }
@article{unraveling the correlations between mechanical properties, miscibility, and film microstructure in all-polymer photovoltaic cells_2022, url={https://publons.com/wos-op/publon/52562407/}, DOI={10.1002/ADFM.202201781}, abstractNote={Abstract The rapid development of low bandgap polymer acceptors has promoted the efficiency up to ≈17% for all‐polymer solar cells (all‐PSCs). Nevertheless, the polymeric blend film, core to the photoelectric conversion of all‐PSCs, has not been thoroughly understood in terms of the influence and regulatory factors of mechanical properties, which hinders the advances in flexible and wearable applications. Herein, a range of characterization methods is combined to investigate the mechanical properties, miscibility, and film microstructure of the blends based on several representative polymer donors (PTzBI‐Si, PTVT‐T, PM6 and PTQ10) and a benchmark polymer acceptor N2200, and to further reveal the miscibility‐property relationships of the miscibility property. The results stress that fracture behaviors and elastic moduli of these blends with varied compositions show different changing trends, which are affected by molecular interactions and aggregated structure of the blends. The elastic moduli of the four all‐polymer blends can be nicely predicted by different models that are deduced from macromolecular mechanics. Most crucially, the correlations between elastic modulus, morphology, and miscibility of all‐polymer blends are elucidated for the first time. The derived relationships is validated with another high‐efficiency blend and will be the key to the successful fabrication of mechanically robust and stretchable all‐PSCs with high efficiency.}, journal={Advanced Functional Materials}, year={2022} }
@article{wang_gao_he_shi_deng_han_ye_geng_2022, title={Unraveling the Molar Mass Dependence of Shearing‐Induced Aggregation Structure of a High‐Mobility Polymer Semiconductor}, volume={1}, url={https://doi.org/10.1002/adma.202108255}, DOI={10.1002/adma.202108255}, abstractNote={Aggregation-structure formation of conjugated polymers is a fundamental problem in the field of organic electronics and remains poorly understood. Herein, the molar mass dependence of the aggregation structure of a high-mobility conjugated copolymer (TDPP-Se) comprising thiophene-flanked diketopyrrolopyrrole and selenophene is thoroughly shown. Five batches of TDPP-Se are prepared with the number-average molecular weights (Mn ) varied greatly from 21 to 135 kg mol-1 . Small-angle neutron scattering and transmission electron microscopy are combined to probe the solution structure of these polymers, consistently using a deuterated solvent. All the polymers adopt 1D rod-like aggregation structures and the radius of the 1D rods is not sensitive to the Mn , while the length increases monotonically with Mn . By utilizing the ordered packing of the aggregated structure in solution, a highly aligned and ordered film is prepared and, thereafter, a reliable hole mobility of 13.8 cm2 V-1 s-1 is realized in organic thin-film transistors with the moderate Mn batch via bar coating. The hole mobility is among the highest values reported for diketopyrrolopyrrole-based polymers. This work paves the way to visualize the real aggregated structure of polymer semiconductors in solution and sheds light on the microstructure control of high-performance electronic devices.}, journal={Advanced Materials}, publisher={Wiley}, author={Wang, Zhongli and Gao, Mengyuan and He, Chunyong and Shi, Weichao and Deng, Yunfeng and Han, Yang and Ye, Long and Geng, Yanhou}, year={2022}, month={Feb}, pages={2108255} }
@article{unraveling the photovoltaic, mechanical, and microstructural properties and their correlations in simple poly(3-pentylthiophene) solar cells_2022, url={https://publons.com/wos-op/publon/52887653/}, DOI={10.1002/MARC.202200229}, abstractNote={Abstract The power conversion efficiency of polythiophene organic solar cells is constantly refreshed. Despite the renewed device efficiency, very few efforts have been devoted to understanding how the type of electron acceptor alters the photovoltaic and mechanical properties of these low‐cost solar cells. Herein, the authors conduct a thorough investigation of photovoltaic and mechanical characteristics of a simple yet less‐explored polythiophene, namely poly(3‐pentylthiophene) (P3PT), in three different types of organic solar cells, where ZY‐4Cl, PC 71 BM, and N2200 are employed as three representative acceptors, respectively. Compared with the reference poly(3‐hexylthiophene) (P3HT)‐based solar cells, P3PT‐based devices, all perform more efficiently. Particularly, the P3PT:ZY‐4Cl blend exhibits the highest efficiency (ca. 10%) among the six combinations and outperforms the prior top‐performance system P3HT:ZY‐4Cl. Furthermore, the blend films based on N2200 exhibit a high crack‐onset strain of ∼38% on average, which is approximately 15‐ and 17‐times higher than those of ZY‐4Cl and PC 71 BM, respectively. The microstructural origins for the above difference are well elucidated by detailed grazing incidence X‐ray scattering and microscopy analysis. This work not only underlines the potential of P3PT in prolific solar cell research but also demonstrates the superior tensile properties of polythiophene‐based all‐polymer blends for the preparation of stretchable solar cells.}, journal={Macromolecular Rapid Communications}, year={2022} }
@article{when electronically inert polymers meet conjugated polymers: emerging opportunities in organic photovoltaics_2022, url={https://publons.com/wos-op/publon/53266612/}, DOI={10.1007/S10118-022-2762-9}, journal={Chinese Journal of Polymer Science (English Edition)}, year={2022} }
@article{advances and prospective in thermally stable nonfullerene polymer solar cells_2021, url={https://publons.com/wos-op/publon/50063281/}, DOI={10.1007/S11426-021-1087-8}, journal={Science China Chemistry}, year={2021} }
@article{calculation aided miscibility manipulation enables highly efficient polythiophene:nonfullerene photovoltaic cells_2021, url={https://publons.com/wos-op/publon/37929250/}, DOI={10.1007/S11426-020-9890-6}, journal={Science China Chemistry}, year={2021} }
@article{wu_fan_xiong_wang_chen_liu_gao_ye_guo_fang_et al._2021, title={Carboxylate substituted pyrazine: A simple and low-cost building block for novel wide bandgap polymer donor enables 15.3% efficiency in organic solar cells}, volume={82}, ISSN={["2211-3282"]}, url={https://publons.com/wos-op/publon/33566889/}, DOI={10.1016/j.nanoen.2020.105679}, abstractNote={In addition to high power conversion efficiency (PCE) and good stability, the low-cost of photovoltaic materials is also very important for the practical application of organic solar cells (OSCs). Herein, we synthesized a carboxylate substituted pyrazine-based electron-deficient building block (DTCPz) with a simple structure and low synthetic cost, and then developed a novel wide bandgap polymer donor PFBCPZ. Due to the synergistic electron-withdrawing effects of the fluorination in donor unit (BDT-TF) and esterification and C=N double-bond in DTCPz unit, PFBCPZ shows a deeper HOMO level of −5.60 eV, a strong intermolecular π-π interaction, good crystallinity and stacking, and high hole-mobility of 2.11 × 10−3 cm2 V−1 s−1. Matched with a low bandgap acceptor IT-4F, excellent charge transfer, weak recombination, and small non-radiative energy loss in OSCs was achieved, resulting in an impressive fill factor of 0.785 and a high open-circuit voltage of 0.92 V. As a result, a PCE of up to 15.3% is obtained in OSCs, which is the highest value in the IT-4F-based binary OSCs so far and indicates that low-cost DTCPz with a simple structure is a promising building block to construct high-performance polymer donors for application in efficient OSCs.}, journal={NANO ENERGY}, author={Wu, Jingnan and Fan, Qunping and Xiong, Minghai and Wang, Qiutang and Chen, Kai and Liu, Haiqin and Gao, Mengyuan and Ye, Long and Guo, Xia and Fang, Jin and et al.}, year={2021}, month={Apr} }
@article{challenges and recent advances in photodiodes-based organic photodetectors_2021, url={https://publons.com/wos-op/publon/50793340/}, DOI={10.1016/J.MATTOD.2021.08.004}, abstractNote={Organic photodetectors (OPDs) have drawn extensive research efforts due to their tailorable spectral response, ease of processing, compatibility with flexible devices and cooling-free operations. In this review, we outline the promising strategies for constructing high-performance and highly stable photodiodes-based OPDs from the perspectives of molecular engineering, morphology control, and device structure design. Firstly, the impact of molecular design and morphology control on OPD performance is clearly underlined and the molecular design rules and quantitative analysis methods are presented for high-performance OPDs. Subsequently, some striking device designs for multifunctional applications are discussed to elucidate the corresponding mechanism for various responses. What follows are the research efforts of boosting OPD stability for commercial applications. This review not only presents the detailed discussion on various OPD strategies aiming at simultaneously enhancing performance and stability but also provides some insights for the remaining challenges to make further breakthrough of OPDs.}, journal={Materials Today}, year={2021} }
@article{gao_wang_hou_ye_2021, title={Control of aggregated structure of photovoltaic polymers for high‐efficiency solar cells}, volume={2}, url={https://doi.org/10.1002/agt2.46}, DOI={10.1002/agt2.46}, abstractNote={Abstract π‐Conjugated organic/polymer materials‐based solar cells have attracted tremendous research interest in the fields of chemistry, physics, materials science, and energy science. To date, the best‐performance polymer solar cells (PSCs) have achieved power conversion efficiencies exceeding 18%, mostly driven by the molecular design and device structure optimization of the photovoltaic materials. This review article provides a comprehensive overview of the key advances and current status in aggregated structure research of PSCs. Here, we start by providing a brief tutorial on the aggregated structure of photovoltaic polymers. The characteristic parameters at different length scales and the associated characterization techniques are overviewed. Subsequently, a variety of effective strategies to control the aggregated structure of photovoltaic polymers are discussed for polymer:fullerene solar cells and polymer:nonfullerene small molecule solar cells. Particularly, the control strategies for achieving record efficiencies in each type of PSCs are highlighted. More importantly, the in‐depth structure–performance relationships are demonstrated with selected examples. Finally, future challenges and research prospects on understanding and optimizing the aggregated structure of photovoltaic polymers and their blends are provided.}, number={5}, journal={Aggregate}, publisher={Wiley}, author={Gao, Mengyuan and Wang, Wenxuan and Hou, Jianhui and Ye, Long}, year={2021}, month={Oct} }
@article{fluorination enables tunable molecular interaction and photovoltaic performance in non-fullerene solar cells based on ester-substituted polythiophene_2021, url={https://publons.com/wos-op/publon/46817843/}, DOI={10.3389/FCHEM.2021.687996}, abstractNote={Owing to the advantages of low synthetic cost and high scalability of synthesis, polythiophene and its derivatives (PTs) have been of interest in the community of organic photovoltaics (OPVs). Nevertheless, the typical efficiency of PT based photovoltaic devices reported so far is much lower than those of the prevailing push-pull type conjugated polymer donors. Recent studies have underscored that the excessively low miscibility between PT and nonfullerene acceptor is the major reason accounting for the unfavorable active layer morphology and the inferior performance of OPVs based on a well-known PT, namely PDCBT-Cl and a non-halogenated nonfullerene acceptor IDIC. How to manipulate the miscibility between PT and acceptor molecule is important for further improving the device efficiency of this class of potentially low-cost blend systems. In this study, we introduced different numbers of F atoms to the end groups of IDIC to tune the intermolecular interaction of the hypo-miscible blend system (PDCBT-Cl:IDIC). Based on calorimetric, microscopic, and scattering characterizations, a clear relationship between the number of F atoms, miscibility, and device performance was established. With the increased number of F atoms in IDIC, the resulting acceptors exhibited enhanced miscibility with PDCBT-Cl, and the domain sizes of the blend films were reduced substantially. As a result, distinctively different photovoltaic performances were achieved for these blend systems. This study demonstrates that varying the number of F atoms in the acceptors is a feasible way to manipulate the molecular interaction and the film morphology toward high-performance polythiophene:nonfullerene based OPVs.}, journal={Frontiers in Chemistry}, year={2021} }
@article{chen_zhang_wang_gao_kirby_peng_deng_li_ye_2021, title={High T g Polymer Insulator Yields Organic Photovoltaic Blends with Superior Thermal Stability at 150 o C}, url={https://doi.org/10.1002/cjoc.202100270}, DOI={10.1002/cjoc.202100270}, abstractNote={Main observation and conclusion Record‐breaking organic solar cells (OSCs) based on blends of polymer donors and small molecule acceptors often show undesirable degradation, which severely precludes their practical use. Herein, we demonstrate a facile and cost‐effective approach to construct thermally stable OSCs at 150 o C by incorporating a small amount of a polymer insulator polyacenaphthylene (PAC) with high glass‐transition temperature over 230 o C into polymer:acceptor blends. The model PTB7‐Th:EH‐IDTBR blend with 10 wt% PAC maintained above 85% of its initial efficiency upon continuous heating at 150 o C for over 800 h, while the efficiency of the blend without PAC sharply dropped by 70% after ~300 h. Owing to high miscibility with acceptors, PAC confines the motion of the acceptor molecules and suppresses the acceptor crystallization at elevated temperatures, leading to significantly improved stability. Importantly, the effectiveness of this blending approach was also validated in many other OSC systems, showing great potential for achieving high‐performance thermally stable electronics.}, journal={Chinese Journal of Chemistry}, author={Chen, Fei and Zhang, Ying and Wang, Qi and Gao, Mengyuan and Kirby, Nigel and Peng, Zhongxiang and Deng, Yunfeng and Li, Miaomiao and Ye, Long}, year={2021}, month={May} }
@article{zhao_liu_wu_zhang_prine_zhang_pang_yin_ye_gu_et al._2021, title={High-Performance All-Polymer Solar Cells and Photodetectors Enabled by a High-Mobility n-Type Polymer and Optimized Bulk-Heterojunction Morphology}, volume={33}, url={https://doi.org/10.1021/acs.chemmater.1c00825}, DOI={10.1021/acs.chemmater.1c00825}, abstractNote={All-polymer solar cells (all-PSCs) and all-polymer photodetectors (all-PPDs) are promising for application in flexible electronics, but their performance is greatly limited by the lack of polymer acceptors and the difficulties in morphology control. Herein, we report the use of a high-mobility n-type polymer semiconductor, PNDI-DTBT, for fabricating high-performance all-PSCs and all-PPDs. By pairing PNDI-DTBT with a matched polymer donor, a prominent power conversion efficiency of 8.5% was obtained in all-PSCs, demonstrating the great potential of high-mobility n-type polymers with a conventional donor–acceptor skeleton for photovoltaic application. Moreover, all-PPDs with a low dark current density of 1.32 × 10–8 A cm–2 at −0.1 V bias and a high specific detectivity of 4.77 × 1012 Jones were achieved, which belong to the best results of organic photodetectors. Morphology investigations revealed that the formation of a bicontinuous interpenetrating network with optimal phase separation scale, high domain purity, and preferential vertical composition distribution in the bulk-heterojunction active layer contribute to the remarkable device performance. These results suggest that combining high-mobility n-type polymers and morphology optimization is fruitful to achieving high-performance all-PSCs and all-PPDs.}, number={10}, journal={Chemistry of Materials}, publisher={American Chemical Society (ACS)}, author={Zhao, Yanfei and Liu, Tao and Wu, Baoqi and Zhang, Song and Prine, Nathaniel and Zhang, Long and Pang, Shuting and Yin, Bingyan and Ye, Long and Gu, Xiaodan and et al.}, year={2021}, month={May}, pages={3746–3756} }
@article{ma_yao_wang_xu_gao_zu_cui_zhang_ye_hou_2021, title={Impact of Electrostatic Interaction on Bulk Morphology in Efficient Donor–Acceptor Photovoltaic Blends}, volume={133}, url={https://doi.org/10.1002/ange.202102622}, DOI={10.1002/ange.202102622}, abstractNote={Abstract Bulk heterojunctions comprising mixed donor (D) and acceptor (A) materials have proven to be the most efficient device structures for organic photovoltaic (OPV) cells. The bulk morphology of such cells plays a key role in charge generation, recombination, and transport, thus determining the device performance. Although numerous studies have discussed the morphology‐performance relationship of these cells, the method of designing OPV materials with the desired morphology remains unclear. Herein, guided by molecular electrostatic potential distributions, we have established a connection between the chemical structure and bulk morphology. We show that the molecular orientation at the D‐A interface and the domain purity in the blend can be effectively modulated by modifying the functional groups. Enhancing the D‐A interaction is beneficial for charge generation. However, the resulting low domain purity and increased charge transfer ratio in its hybridization with the local excitation states lead to severe charge recombination. Fine‐tuning the bulk morphology can give balanced charge generation and recombination, which is crucial for further boosting the efficiency of the OPV cells.}, number={29}, journal={Angewandte Chemie}, publisher={Wiley}, author={Ma, Lijiao and Yao, Huifeng and Wang, Jingwen and Xu, Ye and Gao, Mengyuan and Zu, Yunfei and Cui, Yong and Zhang, Shaoqing and Ye, Long and Hou, Jianhui}, year={2021}, month={Jul}, pages={16124–16130} }
@article{ma_yao_wang_xu_gao_zu_cui_zhang_ye_hou_2021, title={Impact of Electrostatic Interaction on Bulk Morphology in Efficient Donor–Acceptor Photovoltaic Blends}, volume={60}, url={https://doi.org/10.1002/anie.202102622}, DOI={10.1002/anie.202102622}, abstractNote={Abstract Bulk heterojunctions comprising mixed donor (D) and acceptor (A) materials have proven to be the most efficient device structures for organic photovoltaic (OPV) cells. The bulk morphology of such cells plays a key role in charge generation, recombination, and transport, thus determining the device performance. Although numerous studies have discussed the morphology‐performance relationship of these cells, the method of designing OPV materials with the desired morphology remains unclear. Herein, guided by molecular electrostatic potential distributions, we have established a connection between the chemical structure and bulk morphology. We show that the molecular orientation at the D‐A interface and the domain purity in the blend can be effectively modulated by modifying the functional groups. Enhancing the D‐A interaction is beneficial for charge generation. However, the resulting low domain purity and increased charge transfer ratio in its hybridization with the local excitation states lead to severe charge recombination. Fine‐tuning the bulk morphology can give balanced charge generation and recombination, which is crucial for further boosting the efficiency of the OPV cells.}, number={29}, journal={Angewandte Chemie International Edition}, publisher={Wiley}, author={Ma, Lijiao and Yao, Huifeng and Wang, Jingwen and Xu, Ye and Gao, Mengyuan and Zu, Yunfei and Cui, Yong and Zhang, Shaoqing and Ye, Long and Hou, Jianhui}, year={2021}, month={Jul}, pages={15988–15994} }
@article{cheng_li_liang_gao_ye_geng_2021, title={Implications of Crystallization Temperatures of Organic Small Molecules in Optimizing Nonfullerene Solar Cell Performance}, volume={7}, url={https://doi.org/10.1021/acsaem.1c01657}, DOI={10.1021/acsaem.1c01657}, abstractNote={Crystallization behaviors of both small-molecule donors and acceptors are critical yet complicated factors that determine the microstructure of all small-molecule organic solar cells. To achieve desired photovoltaic performance, it is of vital importance to elucidate the role of key crystallization parameters of each component in optimizing the morphology of blend films. To this end, four binary blends based on crystalline donors with various crystallization temperatures (namely DRTT-R, DRTT-T, DRTT-2T, and DRTT-TT) and a weakly crystalline acceptor N3 were selected. We determined the crystallization onset temperature (Tc,onset) and aggregation transition temperature of the small molecules in neat/blend films by temperature-dependent X-ray diffraction and UV–vis measurements. Based on the detailed analysis of molecular crystallization, film morphology evolution, and device performance, a strong correlation between the Tc,onset of photoactive materials and optimal thermal annealing (TA) conditions for device performance was established across these systems. Guided by this finding, a two-step TA approach was used to realize DRTT-T:N3 blend films with highly ordered molecular packing and appropriate phase separation morphology, thereby yielding a high power conversion efficiency of 13.21%. Our study demonstrates that using simple crystallization parameters, that is, Tc,onset, can rationalize the annealing protocols, which is instructive for promoting the performance of all small-molecule electronic blends.}, journal={ACS Applied Energy Materials}, publisher={American Chemical Society (ACS)}, author={Cheng, Xiafei and Li, Miaomiao and Liang, Ziqi and Gao, Mengyuan and Ye, Long and Geng, Yanhou}, year={2021}, month={Aug} }
@article{low-bandgap conjugated polymers based on benzodipyrrolidone with reliable unipolar electron mobility exceeding 1 cm(2) v-1 s(-1)_2021, url={https://publons.com/wos-op/publon/46837749/}, DOI={10.1007/S11426-021-9991-0}, journal={Science China Chemistry}, year={2021} }
@article{ma_zhang_wang_ren_gao_zhang_zhang_yao_ye_hou_2021, title={Miscibility Control by Tuning Electrostatic Interactions in Bulk Heterojunction for Efficient Organic Solar Cells}, volume={7}, url={https://doi.org/10.1021/acsmaterialslett.1c00328}, DOI={10.1021/acsmaterialslett.1c00328}, abstractNote={The morphology of the bulk heterojunction plays a vital role in determining the efficiencies of the organic photovoltaic (OPV) cells. Although the device efficiencies have been greatly improved, the practice guidelines in morphology control are still lacking. In this work, impressive performance of 17.7% was achieved by modulating the electrostatic interaction and, thus, the miscibility between the newly designed polymer donors (P5T, P5T-2F) and a nonfullerene acceptor (NFA) named eC9. Three model compounds (8T, 8T-2F, and TT-2Cl) are prepared to deeply study the miscibility of the donors and acceptors in the active layers. Our findings demonstrate that the decreased molecular interaction and miscibility in P5T-2F:eC9 combinations is more favorable for obtaining suitable phase separation morphology. This work proposes specific molecular design strategy to optimize the donor:acceptor (D:A) bulk morphology, which is crucial for further boosting the efficiency of the OPV cells.}, journal={ACS Materials Letters}, publisher={American Chemical Society (ACS)}, author={Ma, Lijiao and Zhang, Shaoqing and Wang, Jingwen and Ren, Junzhen and Gao, Mengyuan and Zhang, Jianqi and Zhang, Tao and Yao, Huifeng and Ye, Long and Hou, Jianhui}, year={2021}, month={Sep}, pages={1276–1283} }
@article{peng_jiang_qin_li_balar_brendan t. o'connor_ade_ye_geng_2021, title={Modulation of Morphological, Mechanical, and Photovoltaic Properties of Ternary Organic Photovoltaic Blends for Optimum Operation}, volume={11}, ISSN={["1614-6840"]}, url={https://doi.org/10.1002/aenm.202003506}, DOI={10.1002/aenm.202003506}, abstractNote={Abstract Ternary solar cells comprising both fullerene and nonfullerene acceptors have shown a rapid increase in power conversion efficiency, which holds promise in commercial applications. Despite the rapid progress, there is still a lack of fundamental understanding of the relations between microstructure and (photovoltaic/mechanical) properties in these ternary blend systems. In this work, the dependence of molecular packing, phase separation, mechanical properties, and photovoltaic performance on acceptor composition of a recently certificated ternary system is thoroughly investigated by combined scattering and microscopy characterizations. It is demonstrated that incorporating a small amount (20% by weight) PC 71 BM to the PM6:N3 binary blend can afford the best device efficiency and the highest ductility simultaneously. This maximum performance is due to the optimized molecular order, orientational texture, and phase separation. Additionally, increasing the amount of PC 71 BM results in higher elastic modulus, as probed by two distinct methods. A more crucial observation is that the elastic modulus of ternary blends can be well captured by an extended Halpin–Tsai model. This finding is expected to enable the prediction of the elastic modulus of various kinds of ternary blends that are widely used in solar cells and other electronics.}, number={8}, journal={ADVANCED ENERGY MATERIALS}, publisher={Wiley}, author={Peng, Zhongxiang and Jiang, Kui and Qin, Yunpeng and Li, Miaomiao and Balar, Nrup and Brendan T. O'Connor and Ade, Harald and Ye, Long and Geng, Yanhou}, year={2021}, month={Feb} }
@article{zhang_huang_duan_peng_ye_kirby_huang_cao_2021, title={Morphology evolution with polymer chain propagation and its impacts on device performance and stability of non-fullerene solar cells}, url={https://doi.org/10.1039/D0TA10163J}, DOI={10.1039/D0TA10163J}, abstractNote={Blending morphology evolves with polymer chain propagation with reduced phase separation scale and increased phase purity while blending morphological stability is dominated by the miscibility between the donor and acceptor.}, journal={Journal of Materials Chemistry A}, publisher={Royal Society of Chemistry (RSC)}, author={Zhang, Long and Huang, Xuelong and Duan, Chunhui and Peng, Zhongxiang and Ye, Long and Kirby, Nigel and Huang, Fei and Cao, Yong}, year={2021} }
@article{near-infrared absorbing non-fullerene acceptors with unfused d-a-d core for efficient organic solar cells_2021, url={https://publons.com/wos-op/publon/44615154/}, DOI={10.1016/J.ORGEL.2021.106131}, abstractNote={Two non-fullerene acceptors based on D-A-D-type unfused central units, i.e., BCPDT-1 and BCPDT-2, were synthesized, employing 3-bis(4-(2-ethylhexyl)-thiophen-2-yl)-5,7-bis(2ethylhexyl)benzo-[1,2:4,5-c′]-dithiophene-4,8-dione (BDD) unit as the A moiety and 4,4-dialkyl-4H-cyclopenta[2,1-b:3,4-b′]dithiophene (CPDT) unit as the D moiety. The two molecules possess identical backbones, but carry different side chains (octyl for BCPDT-1 and 2-ethylhexyl for BCPDT-2) on CPDT units. Both BCPDT-1 and BCPDT-2 presented broad absorption extending to near-infrared region with optical band gaps of 1.36 and 1.39 eV, respectively. Organic solar cells (OSCs) were fabricated with PBDB-T as donor and BCPDT-1 or BCPDT-2 as acceptor. The devices based on BCPDT-2 exhibited efficient exciton dissociation and charge collection as well as weak charge recombination, attributed to the proper film morphology with nano-scale phase separation and favorable molecular orientation. Consequently, the BCPDT-2 based device displayed a higher power conversion efficiency (PCE) of 10.65%, while the BCPDT-1 based device showed an inferior PCE of 7.54%.}, journal={Organic Electronics}, year={2021} }
@article{wu_liu_ye_guo_fan_lv_zhang_wong_2021, title={New Electron Acceptor with End-Extended Conjugation for High-Performance Polymer Solar Cells}, volume={35}, ISSN={["1520-5029"]}, url={https://publons.com/wos-op/publon/50556823/}, DOI={10.1021/acs.energyfuels.1c02470}, abstractNote={To develop high-efficiency polymer solar cells (PSCs), the acceptors in a bulk heterojunction (BHJ) blend are supposed to possess complementary absorption bands in the near-infrared region and a suitable energy level to be well-matched with the donors. In this work, a new small molecular acceptor (SMA) named IDTT8-N based on an indacenodithienothiophene (IDTT) core was designed and synthesized. In comparison to the counterpart molecule IDTN with an indacenodithiophene (IDT) core, IDTT8-N with the extended π-conjugation length of an IDT core not only exhibits a red shift of ca. 35 nm in optical absorption but also has little change on its lowest unoccupied molecular orbital (LUMO) energy level. Therefore, PSCs based on PM6:IDTT8-N exhibit a superior short-circuit current density (Jsc) and high open-circuit voltage (Voc). Moreover, apart from the strong face-on molecular stacking, distinct end-group π–π stacking of IDTT8-N can be observed in the blends, facilitating the charge transport. Therefore, the optimized PM6:IDTT8-N-based devices exhibit dramatically high and balanced electron mobility (μe) and hole mobility (μh), whose magnitudes are over 10–3 cm2 V–1 s–1. Consequently, an extraordinary PCE of 14.1% with a relatively high Jsc of 20.98 mA cm–2 and a Voc of 0.94 V was recorded. To our knowledge, it is the new record among PSCs with a SMA based on 2-(3-oxocyclopentylidene)malononitrile (INCN) as end groups. These results indicate that extending the π-conjugation length of the fused ring core of a SMA is an efficient method to both enhance the absorption and the molecular interaction of the acceptor as well as the photovoltaic performance of PSCs.}, number={23}, journal={ENERGY & FUELS}, author={Wu, Jingnan and Liu, Qi and Ye, Long and Guo, Xia and Fan, Qunping and Lv, Junfang and Zhang, Maojie and Wong, Wai-Yeung}, year={2021}, month={Dec}, pages={19061–19068} }
@article{li_huang_ding_sheriff_ye_liu_li_ade_forrest_2021, title={Non-fullerene acceptor organic photovoltaics with intrinsic operational lifetimes over 30 years}, volume={12}, ISSN={["2041-1723"]}, url={https://publons.com/wos-op/publon/49626481/}, DOI={10.1038/s41467-021-25718-w}, abstractNote={Abstract Organic photovoltaic cells (OPVs) have the potential of becoming a productive renewable energy technology if the requirements of low cost, high efficiency and prolonged lifetime are simultaneously fulfilled. So far, the remaining unfulfilled promise of this technology is its inadequate operational lifetime. Here, we demonstrate that the instability of NFA solar cells arises primarily from chemical changes at organic/inorganic interfaces bounding the bulk heterojunction active region. Encapsulated devices stabilized by additional protective buffer layers as well as the integration of a simple solution processed ultraviolet filtering layer, maintain 94% of their initial efficiency under simulated, 1 sun intensity, AM1.5 G irradiation for 1900 hours at 55 °C. Accelerated aging is also induced by exposure of light illumination intensities up to 27 suns, and operation temperatures as high as 65 °C. An extrapolated intrinsic lifetime of > 5.6 × 10 4 h is obtained, which is equivalent to 30 years outdoor exposure.}, number={1}, journal={NATURE COMMUNICATIONS}, author={Li, Yongxi and Huang, Xiaheng and Ding, Kan and Sheriff, Hafiz K. M., Jr. and Ye, Long and Liu, Haoran and Li, Chang-Zhi and Ade, Harald and Forrest, Stephen R.}, year={2021}, month={Sep} }
@article{liu_xian_ye_zhou_2021, title={Open‐Circuit Voltage Loss in Lead Chalcogenide Quantum Dot Solar Cells}, volume={6}, url={https://doi.org/10.1002/adma.202008115}, DOI={10.1002/adma.202008115}, abstractNote={Abstract Lead chalcogenide colloidal quantum dot solar cells (CQDSCs) have received considerable attention due to their broad and tunable absorption and high stability. Presently, lead chalcogenide CQDSC has achieved a power conversion efficiency of ≈14%. However, the state‐of‐the‐art lead chalcogenide CQDSC still has an open‐circuit voltage ( V oc ) loss of ≈0.45 V, which is significantly higher than those of c‐Si and perovskite solar cells. Such high V oc loss severely limits the performance improvement and commercialization of lead chalcogenide CQDSCs. In this review, the V oc loss is first analyzed via detailed balance theory and the origin of V oc loss from both solar absorber and interface is summarized. Subsequently, various strategies for improving the V oc from the solar absorber, including the passivation strategies during the synthesis and ligand exchange are overviewed. The great impact of the ligand exchange process on CQD passivation is highlighted and the corresponding strategies to further reduce the V oc loss are summarized. Finally, various strategies are discussed to reduce interface V oc loss from charge transport layers. More importantly, the great potential of achieving performance breakthroughs via various organic hole transport layers is highlighted and the existing challenges toward commercialization are discussed.}, journal={Advanced Materials}, publisher={Wiley}, author={Liu, Junwei and Xian, Kaihu and Ye, Long and Zhou, Zhihua}, year={2021}, month={Jul}, pages={2008115} }
@article{optimization of monomer molecular structure for polymer electrodes fabricated through in-situ electro-polymerization strategy_2021, url={https://publons.com/wos-op/publon/49626480/}, DOI={10.1002/CSSC.202101553}, abstractNote={In-situ electro-polymerization of redox-active monomers has been proved to be a novel and facile strategy to prepare polymer electrodes with superior electrochemical performance. The monomer molecular structure would have a profound impact on electro-polymerization behavior and thus electrochemical performance. However, this impact is poorly understood and has barely been investigated yet. Herein, three carbazole-based monomers, 9-phenylcarbazole (CB), 1,4-bis(carbazol-9-yl)benzene (DCB), and 2,6-bis(carbazol-9-yl)naphthalene (DCN), were applied to study the above issue systematically and achieve excellent long cycle performance. The monomers were rationally designed with different polymerizable sites and solubilities. It was found that a monomer with increased polymerizable sites and decreased solubility brought about enhanced electrochemical performance. This is because poor solubility could enhance utilization of the monomer for polymerization and more polymerizable sites could lead to a stable crosslinked polymer network after electro-polymerization. DCN with four polymerizable sites and the poorest solubility displayed the best electrochemical performance, which showed stable cycling up to 5000 cycles with high capacity retention of 76.2 % (among the best cycle in the literature). Our work for the first time reveals the relationship between monomer structure and in-situ electro-polymerization behavior. This work could shed light on the structure design/optimization of monomers for high-performance polymer electrodes prepared through in-situ electro-polymerization.}, journal={ChemSusChem}, year={2021} }
@article{guo_fan_wu_li_peng_su_lin_hou_qin_ade_et al._2021, title={Optimized Active Layer Morphologies via Ternary Copolymerization of Polymer Donors for 17.6 % Efficiency Organic Solar cells with Enhanced Fill Factor}, volume={60}, ISSN={["1521-3773"]}, url={https://publons.com/wos-op/publon/36593750/}, DOI={10.1002/anie.202010596}, abstractNote={Abstract Regulating molecular structure to optimize the active layer morphology is of considerable significance for improving the power conversion efficiencies (PCEs) in organic solar cells (OSCs). Herein, we demonstrated a simple ternary copolymerization approach to develop a terpolymer donor PM6‐Tz20 by incorporating the 5,5′‐dithienyl‐2,2′‐bithiazole (DTBTz, 20 mol%) unit into the backbone of PM6 (PM6‐Tz00). This method can effectively tailor the molecular orientation and aggregation of the polymer, and then optimize the active layer morphology and the corresponding physical processes of devices, ultimately boosting FF and then PCE. Hence, the PM6‐Tz20: Y6‐based OSCs achieved a PCE of up to 17.1% with a significantly enhanced FF of 0.77. Using Ag (220 nm) instead of Al (100 nm) as cathode, the champion PCE was further improved to 17.6%. This work provides a simple and effective molecular design strategy to optimize the active layer morphology of OSCs for improving photovoltaic performance.}, number={5}, journal={ANGEWANDTE CHEMIE-INTERNATIONAL EDITION}, author={Guo, Xia and Fan, Qunping and Wu, Jingnan and Li, Guangwei and Peng, Zhongxiang and Su, Wenyan and Lin, Ji and Hou, Lintao and Qin, Yunpeng and Ade, Harald and et al.}, year={2021}, month={Feb}, pages={2322–2329} }
@article{p3ht-based organic solar cells with a photoresponse to 1000 nm enabled by narrow band gap nonfullerene acceptors with high homo levels_2021, url={https://publons.com/wos-op/publon/50998621/}, DOI={10.1021/ACSAMI.1C21089}, abstractNote={Three narrow band gap (NBG) acceptors, namely, TTDTC-0F, TTDTC-2F, and TTDTC-4F, were synthesized by introducing a strong electron-donating unit as the central core. The enhanced intramolecular charge transfer endows the three acceptors with high-lying highest occupied molecular orbitals (HOMOs) of ∼-5.20 eV and ultranarrow band gaps (∼1.25 eV). When blended with poly(3-hexylthiophene) (P3HT), all organic solar cells (OSCs) exhibited a broad photoresponse from 300 to ∼1000 nm. Among them, P3HT:TTDTC-4F-based devices achieved the highest efficiency of 7.81% with a prominent Jsc exceeding 22 mA·cm-2. This study demonstrates that the conjugated molecules with high HOMOs can also function as acceptor materials for P3HT-based OSCs, which opens a window to increase PCEs of P3HT-based OSCs in the future to the level of the devices based on the current state-of-the-art polymer donor materials.}, journal={ACS Applied Materials & Interfaces}, year={2021} }
@article{printable and stable all-polymer solar cells based on non-conjugated polymer acceptors with excellent mechanical robustness_2021, url={https://publons.com/wos-op/publon/50793341/}, DOI={10.1007/S11426-021-1094-Y}, journal={Science China Chemistry}, year={2021} }
@article{quadrupole moment induced morphology control via a highly volatile small molecule in efficient organic solar cells_2021, url={https://publons.com/wos-op/publon/37692106/}, DOI={10.1002/ADFM.202010535}, abstractNote={Abstract Developing novel solid additives has been regarded as a promising strategy to achieve highly efficient organic solar cells with good stability and reproducibility. Herein, a small molecule, 2,2′‐(perfluoro‐1,4‐phenylene)dithiophene (DTBF), designed with high volatility and a strong quadrupole moment, is applied as a solid additive to implement active layer morphology control in organic solar cells. Systematic theory simulations have revealed the charge distribution of DTBF and its analog and their non‐covalent interaction with the active layer materials. Benefitting from the more vital charge–quadrupole interaction, the introduction, and volatilization of DTBF effectively induced more regular and condensed molecular packing in the active layer, leading to enhanced photoelectric properties. Thus, high efficiency of over 17% is obtained in the DTBF‐processed devices, which is higher than that of the control devices. Further application of DTBF in different active layer systems contributed to a deeper comprehension of this type of additive. This study highlights a facile approach to optimizing the active layer morphology by finely manipulating the quadrupole moment of volatile solid additives.}, journal={Advanced Functional Materials}, year={2021} }
@article{recent advances in the development of radiative sky cooling inspired from solar thermal harvesting_2021, url={https://publons.com/wos-op/publon/42599541/}, DOI={10.1016/J.NANOEN.2020.105611}, abstractNote={Radiative sky cooling (RSC) technology dissipates the terrestrial heat to the extremely cold outer space, without any energy input and any pollutant produced. It has the potential to simultaneously alleviate the two challenges of energy crisis and global warming. In this review, we look for the inspirations from the relatively mature solar thermal harvesting (STH) technology to solve the challenges in the RSC field. We firstly summarize the comparability and similarity of the two technologies from five levels: principles, materials and structures, devices, systems, and applications. Subsequently, the valuable inspirations or strategies from the STH technology are proposed to advance the development and application of the RSC technology. Finally, we discuss the application of the RSC technology to solve the challenges of water shortage and night lighting in remote areas, aim to broaden the application scope of this technology.}, journal={Nano Energy}, year={2021} }
@article{arneson_huang_huang_fan_gao_ye_ade_li_forrest_2021, title={Relationship between charge transfer state electroluminescence and the degradation of organic photovoltaics}, volume={118}, ISSN={["1077-3118"]}, url={https://publons.com/wos-op/publon/43514815/}, DOI={10.1063/5.0037710}, abstractNote={The degradation of archetype organic photovoltaics comprising both vacuum and solution-deposited bulk heterojunction active regions is investigated and quantified using a theory based on detailed balance, which relates the open-circuit voltage to the efficiency of charge transfer state emission. To describe this relationship, we account for the difference between electroluminescent external quantum efficiency and the charge transfer emission efficiency. An empirical factor, m, is introduced to distinguish between nonradiative defect sites both within, m = 1, and outside, m >1, of the photoactive heterojunction. The m-factor is used to determine the primary sources of degradation for archetype solution- and vacuum-processed material systems. We conclude that degradation occurs primarily within the donor–acceptor heterojunction for the vacuum-processed devices (where m = 1.020 ± 0.002) and outside of the photoactive heterojunction for the solution-processed devices studied, both with and without an anode buffer layer (where m = 2.93 ± 0.09 and m = 1.90 ± 0.01, respectively).}, number={6}, journal={APPLIED PHYSICS LETTERS}, author={Arneson, Claire and Huang, Xinjing and Huang, Xiaheng and Fan, Dejiu and Gao, Mengyuan and Ye, Long and Ade, Harald and Li, Yongxi and Forrest, Stephen R.}, year={2021}, month={Feb} }
@article{remove the water-induced traps toward improved performance in organic solar cells_2021, url={https://publons.com/wos-op/publon/33727459/}, DOI={10.1007/S40843-021-1703-4}, abstractNote={Clusters of water molecules have low ionization energies because of stabilization of charge from the dipole moment of surrounding molecules, and thus can form potential traps resulting in the undesirable photovoltaic performance in organic solar cells (OSCs). Herein, we demonstrated a solvent-water evaporation (SWE) strategy, which can effectively remove the water-induced traps that are omnipresent in photoactive layers, leading to a significant improvement in device performance. A higher power conversion efficiency of 17.10% and a better device photostability are achieved by using this SWE method, as compared with the untreated binary PM6:Y6 system (15.83%). We highlight the water-related traps as a limiting factor for carrier transport and extraction properties, and further reveal the good universality of the SWE strategy applied into OSCs. In addition, organic light-emitting diodes and organic field-effect transistors are investigated to demonstrate the applicability of this SWE approach. This strategy presents a major step forward for advancing the field of organic electronics.}, journal={Science China Materials}, year={2021} }
@article{balar_rech_siddika_song_schrickx_sheikh_ye_bonilla_awartani_ade_et al._2021, title={Resolving the Molecular Origin of Mechanical Relaxations in Donor-Acceptor Polymer Semiconductors}, volume={10}, ISSN={["1616-3028"]}, url={https://publons.com/wos-op/publon/49897193/}, DOI={10.1002/ADFM.202105597}, abstractNote={Abstract The thermomechanical behavior of polymer semiconductors plays an important role in the processing, morphology, and stability of organic electronic devices. However, donor–acceptor‐based copolymers exhibit complex thermal relaxation behavior that is not well understood. This study uses dynamic mechanical analysis (DMA) to probe thermal relaxations of a systematic set of polymers based around the benzodithiophene (BDT) moiety. The loss tangent curves are resolved by fitting Gaussian functions to assign and distinguish different relaxations. Three prominent transitions are observed that correspond to: i) localized relaxations driven primarily by the side chains (γ ), ii) relaxations along the polymer backbone (β ), and iii) relaxations associated with aggregates (α ). The side chains are found to play a clear role in dictating T γ , and that mixing the side chain chemistry of the monomer to include alkyl and oligo(ethylene glycol) moieties results in splitting the γ ‐relaxation. The β relaxations are shown to be associated with backbone elements along with the monomer. In addition, through processing, it is shown that the α‐relaxation is due to aggregate formation. Finally, it is demonstrated that the thermal relaxation behavior correlates well with the stress–strain behavior of the polymers, including hysteresis and permanent set in cyclically stretched films.}, number={4}, journal={ADVANCED FUNCTIONAL MATERIALS}, publisher={Wiley}, author={Balar, Nrup and Rech, Jeromy James and Siddika, Salma and Song, Runqiao and Schrickx, Harry M. and Sheikh, Nadeem and Ye, Long and Bonilla, Anthony Megret and Awartani, Omar and Ade, Harald and et al.}, year={2021}, month={Oct} }
@article{revealing the side-chain-dependent ordering transition of highly crystalline double-cable conjugated polymers_2021, url={https://publons.com/wos-op/publon/50063280/}, DOI={10.1002/ANIE.202111192}, abstractNote={We developed a series of highly crystalline double-cable conjugated polymers for application in single-component organic solar cells (SCOSCs). These polymers contain conjugated backbones as electron donor and pendant perylene bisimide units (PBIs) as electron acceptor. PBIs are connected to the backbone via alkyl units varying from hexyl (C6 H12 ) to eicosyl (C20 H40 ) as flexible linkers. For double-cable polymers with short linkers, the PBIs tend to stack in a head-to-head fashion, resulting in large d-spacings (e.g. 64 Å for the polymer P12 with C12 H24 linker) along the lamellar stacking direction. When the length of the linker groups is longer than a certain length, the PBIs instead adopt a more ordered packing likely via H-aggregation, resulting in short d-spacings (e.g. 50 Å for the polymer P16 with C16 H32 linker). This work highlights the importance of linker length on the molecular packing of the acceptor units and the influences on the photovoltaic performance of SCOSCs.}, journal={Angewandte Chemie International Edition}, year={2021} }
@article{li_wang_liu_geng_ye_2021, title={Sequential deposition enables high-performance nonfullerene organic solar cells}, url={https://doi.org/10.1039/D1QM00407G}, DOI={10.1039/D1QM00407G}, abstractNote={The morphology optimization strategies and great potentials in constructing stable and large-area organic solar cells via sequential deposition are discussed.}, journal={Materials Chemistry Frontiers}, publisher={Royal Society of Chemistry (RSC)}, author={Li, Miaomiao and Wang, Qi and Liu, Junwei and Geng, Yanhou and Ye, Long}, year={2021} }
@article{zou_ye_2021, title={Stabilizing the microstructure for Y6-series nonfullerene solar cells}, volume={7}, url={http://dx.doi.org/10.1016/j.chempr.2021.10.009}, DOI={10.1016/j.chempr.2021.10.009}, abstractNote={Recently in Joule, Qin and co-workers determined the glass transition temperatures (Tg) of Y6 and its six close variations to infer relative stabilities and established a structure-Tg framework. They further proposed the key guidelines to stabilize the microstructure and performance in both binary and ternary solar cells. Recently in Joule, Qin and co-workers determined the glass transition temperatures (Tg) of Y6 and its six close variations to infer relative stabilities and established a structure-Tg framework. They further proposed the key guidelines to stabilize the microstructure and performance in both binary and ternary solar cells. Main textSince the first report of Y6,1Yuan J. Zhang Y. Zhou L. Zhang G. Yip H.-L. Lau T.-K. Lu X. Zhu C. Peng H. Johnson P.A. et al.Single-Junction Organic Solar Cell with over 15% Efficiency Using Fused-Ring Acceptor with Electron-Deficient Core.Joule. 2019; 3: 1140-1151Abstract Full Text Full Text PDF Scopus (2826) Google Scholar the most popular and successful A-DA′D-A structured nonfullerene acceptor, the performance of organic solar cells (OSCs) has increased considerably from ∼15% to ∼19% in three years.2Wei Q. Yuan J. Yi Y. Zhang C. Zou Y. Y6 and its derivatives: molecular design and physical mechanism.Natl. Sci. Rev. 2021; 8: nwab121Crossref PubMed Scopus (16) Google Scholar A significant challenge for such cells is to achieve high efficiency and high stability simultaneously.3Burlingame Q. Ball M. Loo Y.-L. It’s time to focus on organic solar cell stability.Nat. Energy. 2020; 5: 947-949Crossref Scopus (61) Google Scholar To date, attaining stable operation throughout the cell lifetime while under various stresses is widely recognized as a challenging task for commercializing OSCs.4Xu X. Li D. Yuan J. Zhou Y. Zou Y. Recent advances in stability of organic solar cells.Energy Chem. 2021; 3: 100046Crossref Scopus (26) Google Scholar Particularly, a key requirement is that the film microstructure of the bulk-heterojunction polymer:acceptor should not evolve rapidly with time.The microstructure stability of Y6 (also named BTP-4F) and its dependence on structural parameters (side chains) on the molecular level remain unclear. Recently in Joule, the Ade group and Hou group jointly addressed this issue by thoroughly investigating a wide range of Y6-series nonfullerene acceptors (Figure 1).5Qin Y. Balar N. Peng Z. Gadisa A. Angunawela I. Bagui A. Kashani S. Hou J. Ade H. The performance-stability conundrum of BTP-based organic solar cells.Joule. 2021; 5: 2129-2147Abstract Full Text Full Text PDF Scopus (30) Google Scholar These acceptors of interest mainly include two homologous groups: fluorinated molecules (BTP-4F, BTP-4F-C12, BTP-4F-DT) and chlorinated molecules (BTP-eC7, BTP-eC9, BTP-eC11). In addition, a well-studied analog N36Jiang K. Wei Q. Lai J.Y.L. Peng Z. Kim H.K. Yuan J. Ye L. Ade H. Zou Y. Yan H. Alkyl Chain Tuning of Small Molecule Acceptors for Efficient Organic Solar Cells.Joule. 2019; 3: 3020-3033Abstract Full Text Full Text PDF Scopus (521) Google Scholar (also called BTP-C3-4F) was investigated. The challenges in morphological stability of organic solar cells based on the “star” acceptor Y6 and related analogs were delineated by using secondary ion mass-spectroscopy depth profiles and complementary characterizations, and consequently a molecular structure-glass transition temperature (Tg) framework was developed.By analyzing the deviation metric results from ultraviolet-visible spectra, Qin et al.5Qin Y. Balar N. Peng Z. Gadisa A. Angunawela I. Bagui A. Kashani S. Hou J. Ade H. The performance-stability conundrum of BTP-based organic solar cells.Joule. 2021; 5: 2129-2147Abstract Full Text Full Text PDF Scopus (30) Google Scholar determined the Tg of these seven Y6-series acceptors. They also discussed the impact of molecular design on Tg to explore whether a stable Y6 analog can be created. The roles of side-chain length, branching points, and halogenation were well understood. It was found that the smaller the total length of all side chains (in relation to the given backbone), the higher the Tg of the acceptor. To estimate how high the Tg of Y6 analogs can be pushed with molecular design, they further compared and re-analyzed these data by plotting Tg against the side-chain mass fraction (φ). The reported results of poly(3-alkyl-thiophene), poly N-(n-alkyl-maleimides), and poly(styrene-co-alkyl-maleimide) also follow excellent linear relations between Tg and φ with Pearson correlation coefficients of >0.98. In striking similarity to the three homologous reference materials from the literature, the two homologous Y6 analogs investigated by Qin et al. yield linear fits with very similar slopes and asymptotic Tg. In the case of the Y6 analogs and most likely in general, a most critical and unresolved molecular design conundrum emerges on how to simultaneously achieve high processibility, performance, and intrinsic stability. Their results point out the need for a Y6 analog with a higher Tg and lower diffusion coefficients7Ghasemi M. Hu H. Peng Z. Rech J. Angunawela I. Carpenter J. Stuard S. Wadsworth A. McCulloch I. You W. Ade H. Delineation of Thermodynamic and Kinetic Factors that Control Stability in Non-fullerene Organic Solar Cells.Joule. 2019; 3: 1328-1348Abstract Full Text Full Text PDF Scopus (81) Google Scholar to target superior intrinsic stability.Lastly, more complicated systems based on Y6-series acceptors were also explored. To construct highly efficient and stable ternary blend cells, an ideal third component should possess differential miscibility in the donor polymer that can only impact percolation,8Ye L. Li S. Liu X. Zhang S. Ghasemi M. Xiong Y. Hou J. Ade H. Quenching to the Percolation Threshold in Organic Solar Cells.Joule. 2019; 3: 443-458Abstract Full Text Full Text PDF Scopus (132) Google Scholar and the third component with differential miscibility with the Y6-series acceptor only impacts diffusion behaviors. Moving forward, it is highly desirable to build a predictive paradigm on performance and stability simply from the chemical structure. As stability gains increasing interest, it is the right time to realize high efficiency, excellent stability, and low cost in the same material system. Fortunately, developing cost-effective, efficient, and stable polythiophene:Y6-series acceptor systems9Liang Z. Li M. Wang Q. Qin Y. Stuard S.J. Peng Z. Deng Y. Ade H. Ye L. Geng Y. Optimization Requirements of Efficient Polythiophene:Nonfullerene Organic Solar Cells.Joule. 2020; 4: 1278-1295Abstract Full Text Full Text PDF Scopus (90) Google Scholar,10Xiao J. Jia X. Duan C. Huang F. Yip H.L. Cao Y. Surpassing 13% Efficiency for Polythiophene Organic Solar Cells Processed from Nonhalogenated Solvent.Adv. Mater. 2021; 33: e2008158Crossref PubMed Scopus (46) Google Scholar is presently on the way. Main textSince the first report of Y6,1Yuan J. Zhang Y. Zhou L. Zhang G. Yip H.-L. Lau T.-K. Lu X. Zhu C. Peng H. Johnson P.A. et al.Single-Junction Organic Solar Cell with over 15% Efficiency Using Fused-Ring Acceptor with Electron-Deficient Core.Joule. 2019; 3: 1140-1151Abstract Full Text Full Text PDF Scopus (2826) Google Scholar the most popular and successful A-DA′D-A structured nonfullerene acceptor, the performance of organic solar cells (OSCs) has increased considerably from ∼15% to ∼19% in three years.2Wei Q. Yuan J. Yi Y. Zhang C. Zou Y. Y6 and its derivatives: molecular design and physical mechanism.Natl. Sci. Rev. 2021; 8: nwab121Crossref PubMed Scopus (16) Google Scholar A significant challenge for such cells is to achieve high efficiency and high stability simultaneously.3Burlingame Q. Ball M. Loo Y.-L. It’s time to focus on organic solar cell stability.Nat. Energy. 2020; 5: 947-949Crossref Scopus (61) Google Scholar To date, attaining stable operation throughout the cell lifetime while under various stresses is widely recognized as a challenging task for commercializing OSCs.4Xu X. Li D. Yuan J. Zhou Y. Zou Y. Recent advances in stability of organic solar cells.Energy Chem. 2021; 3: 100046Crossref Scopus (26) Google Scholar Particularly, a key requirement is that the film microstructure of the bulk-heterojunction polymer:acceptor should not evolve rapidly with time.The microstructure stability of Y6 (also named BTP-4F) and its dependence on structural parameters (side chains) on the molecular level remain unclear. Recently in Joule, the Ade group and Hou group jointly addressed this issue by thoroughly investigating a wide range of Y6-series nonfullerene acceptors (Figure 1).5Qin Y. Balar N. Peng Z. Gadisa A. Angunawela I. Bagui A. Kashani S. Hou J. Ade H. The performance-stability conundrum of BTP-based organic solar cells.Joule. 2021; 5: 2129-2147Abstract Full Text Full Text PDF Scopus (30) Google Scholar These acceptors of interest mainly include two homologous groups: fluorinated molecules (BTP-4F, BTP-4F-C12, BTP-4F-DT) and chlorinated molecules (BTP-eC7, BTP-eC9, BTP-eC11). In addition, a well-studied analog N36Jiang K. Wei Q. Lai J.Y.L. Peng Z. Kim H.K. Yuan J. Ye L. Ade H. Zou Y. Yan H. Alkyl Chain Tuning of Small Molecule Acceptors for Efficient Organic Solar Cells.Joule. 2019; 3: 3020-3033Abstract Full Text Full Text PDF Scopus (521) Google Scholar (also called BTP-C3-4F) was investigated. The challenges in morphological stability of organic solar cells based on the “star” acceptor Y6 and related analogs were delineated by using secondary ion mass-spectroscopy depth profiles and complementary characterizations, and consequently a molecular structure-glass transition temperature (Tg) framework was developed.By analyzing the deviation metric results from ultraviolet-visible spectra, Qin et al.5Qin Y. Balar N. Peng Z. Gadisa A. Angunawela I. Bagui A. Kashani S. Hou J. Ade H. The performance-stability conundrum of BTP-based organic solar cells.Joule. 2021; 5: 2129-2147Abstract Full Text Full Text PDF Scopus (30) Google Scholar determined the Tg of these seven Y6-series acceptors. They also discussed the impact of molecular design on Tg to explore whether a stable Y6 analog can be created. The roles of side-chain length, branching points, and halogenation were well understood. It was found that the smaller the total length of all side chains (in relation to the given backbone), the higher the Tg of the acceptor. To estimate how high the Tg of Y6 analogs can be pushed with molecular design, they further compared and re-analyzed these data by plotting Tg against the side-chain mass fraction (φ). The reported results of poly(3-alkyl-thiophene), poly N-(n-alkyl-maleimides), and poly(styrene-co-alkyl-maleimide) also follow excellent linear relations between Tg and φ with Pearson correlation coefficients of >0.98. In striking similarity to the three homologous reference materials from the literature, the two homologous Y6 analogs investigated by Qin et al. yield linear fits with very similar slopes and asymptotic Tg. In the case of the Y6 analogs and most likely in general, a most critical and unresolved molecular design conundrum emerges on how to simultaneously achieve high processibility, performance, and intrinsic stability. Their results point out the need for a Y6 analog with a higher Tg and lower diffusion coefficients7Ghasemi M. Hu H. Peng Z. Rech J. Angunawela I. Carpenter J. Stuard S. Wadsworth A. McCulloch I. You W. Ade H. Delineation of Thermodynamic and Kinetic Factors that Control Stability in Non-fullerene Organic Solar Cells.Joule. 2019; 3: 1328-1348Abstract Full Text Full Text PDF Scopus (81) Google Scholar to target superior intrinsic stability.Lastly, more complicated systems based on Y6-series acceptors were also explored. To construct highly efficient and stable ternary blend cells, an ideal third component should possess differential miscibility in the donor polymer that can only impact percolation,8Ye L. Li S. Liu X. Zhang S. Ghasemi M. Xiong Y. Hou J. Ade H. Quenching to the Percolation Threshold in Organic Solar Cells.Joule. 2019; 3: 443-458Abstract Full Text Full Text PDF Scopus (132) Google Scholar and the third component with differential miscibility with the Y6-series acceptor only impacts diffusion behaviors. Moving forward, it is highly desirable to build a predictive paradigm on performance and stability simply from the chemical structure. As stability gains increasing interest, it is the right time to realize high efficiency, excellent stability, and low cost in the same material system. Fortunately, developing cost-effective, efficient, and stable polythiophene:Y6-series acceptor systems9Liang Z. Li M. Wang Q. Qin Y. Stuard S.J. Peng Z. Deng Y. Ade H. Ye L. Geng Y. Optimization Requirements of Efficient Polythiophene:Nonfullerene Organic Solar Cells.Joule. 2020; 4: 1278-1295Abstract Full Text Full Text PDF Scopus (90) Google Scholar,10Xiao J. Jia X. Duan C. Huang F. Yip H.L. Cao Y. Surpassing 13% Efficiency for Polythiophene Organic Solar Cells Processed from Nonhalogenated Solvent.Adv. Mater. 2021; 33: e2008158Crossref PubMed Scopus (46) Google Scholar is presently on the way. Since the first report of Y6,1Yuan J. Zhang Y. Zhou L. Zhang G. Yip H.-L. Lau T.-K. Lu X. Zhu C. Peng H. Johnson P.A. et al.Single-Junction Organic Solar Cell with over 15% Efficiency Using Fused-Ring Acceptor with Electron-Deficient Core.Joule. 2019; 3: 1140-1151Abstract Full Text Full Text PDF Scopus (2826) Google Scholar the most popular and successful A-DA′D-A structured nonfullerene acceptor, the performance of organic solar cells (OSCs) has increased considerably from ∼15% to ∼19% in three years.2Wei Q. Yuan J. Yi Y. Zhang C. Zou Y. Y6 and its derivatives: molecular design and physical mechanism.Natl. Sci. Rev. 2021; 8: nwab121Crossref PubMed Scopus (16) Google Scholar A significant challenge for such cells is to achieve high efficiency and high stability simultaneously.3Burlingame Q. Ball M. Loo Y.-L. It’s time to focus on organic solar cell stability.Nat. Energy. 2020; 5: 947-949Crossref Scopus (61) Google Scholar To date, attaining stable operation throughout the cell lifetime while under various stresses is widely recognized as a challenging task for commercializing OSCs.4Xu X. Li D. Yuan J. Zhou Y. Zou Y. Recent advances in stability of organic solar cells.Energy Chem. 2021; 3: 100046Crossref Scopus (26) Google Scholar Particularly, a key requirement is that the film microstructure of the bulk-heterojunction polymer:acceptor should not evolve rapidly with time. The microstructure stability of Y6 (also named BTP-4F) and its dependence on structural parameters (side chains) on the molecular level remain unclear. Recently in Joule, the Ade group and Hou group jointly addressed this issue by thoroughly investigating a wide range of Y6-series nonfullerene acceptors (Figure 1).5Qin Y. Balar N. Peng Z. Gadisa A. Angunawela I. Bagui A. Kashani S. Hou J. Ade H. The performance-stability conundrum of BTP-based organic solar cells.Joule. 2021; 5: 2129-2147Abstract Full Text Full Text PDF Scopus (30) Google Scholar These acceptors of interest mainly include two homologous groups: fluorinated molecules (BTP-4F, BTP-4F-C12, BTP-4F-DT) and chlorinated molecules (BTP-eC7, BTP-eC9, BTP-eC11). In addition, a well-studied analog N36Jiang K. Wei Q. Lai J.Y.L. Peng Z. Kim H.K. Yuan J. Ye L. Ade H. Zou Y. Yan H. Alkyl Chain Tuning of Small Molecule Acceptors for Efficient Organic Solar Cells.Joule. 2019; 3: 3020-3033Abstract Full Text Full Text PDF Scopus (521) Google Scholar (also called BTP-C3-4F) was investigated. The challenges in morphological stability of organic solar cells based on the “star” acceptor Y6 and related analogs were delineated by using secondary ion mass-spectroscopy depth profiles and complementary characterizations, and consequently a molecular structure-glass transition temperature (Tg) framework was developed. By analyzing the deviation metric results from ultraviolet-visible spectra, Qin et al.5Qin Y. Balar N. Peng Z. Gadisa A. Angunawela I. Bagui A. Kashani S. Hou J. Ade H. The performance-stability conundrum of BTP-based organic solar cells.Joule. 2021; 5: 2129-2147Abstract Full Text Full Text PDF Scopus (30) Google Scholar determined the Tg of these seven Y6-series acceptors. They also discussed the impact of molecular design on Tg to explore whether a stable Y6 analog can be created. The roles of side-chain length, branching points, and halogenation were well understood. It was found that the smaller the total length of all side chains (in relation to the given backbone), the higher the Tg of the acceptor. To estimate how high the Tg of Y6 analogs can be pushed with molecular design, they further compared and re-analyzed these data by plotting Tg against the side-chain mass fraction (φ). The reported results of poly(3-alkyl-thiophene), poly N-(n-alkyl-maleimides), and poly(styrene-co-alkyl-maleimide) also follow excellent linear relations between Tg and φ with Pearson correlation coefficients of >0.98. In striking similarity to the three homologous reference materials from the literature, the two homologous Y6 analogs investigated by Qin et al. yield linear fits with very similar slopes and asymptotic Tg. In the case of the Y6 analogs and most likely in general, a most critical and unresolved molecular design conundrum emerges on how to simultaneously achieve high processibility, performance, and intrinsic stability. Their results point out the need for a Y6 analog with a higher Tg and lower diffusion coefficients7Ghasemi M. Hu H. Peng Z. Rech J. Angunawela I. Carpenter J. Stuard S. Wadsworth A. McCulloch I. You W. Ade H. Delineation of Thermodynamic and Kinetic Factors that Control Stability in Non-fullerene Organic Solar Cells.Joule. 2019; 3: 1328-1348Abstract Full Text Full Text PDF Scopus (81) Google Scholar to target superior intrinsic stability. Lastly, more complicated systems based on Y6-series acceptors were also explored. To construct highly efficient and stable ternary blend cells, an ideal third component should possess differential miscibility in the donor polymer that can only impact percolation,8Ye L. Li S. Liu X. Zhang S. Ghasemi M. Xiong Y. Hou J. Ade H. Quenching to the Percolation Threshold in Organic Solar Cells.Joule. 2019; 3: 443-458Abstract Full Text Full Text PDF Scopus (132) Google Scholar and the third component with differential miscibility with the Y6-series acceptor only impacts diffusion behaviors. Moving forward, it is highly desirable to build a predictive paradigm on performance and stability simply from the chemical structure. As stability gains increasing interest, it is the right time to realize high efficiency, excellent stability, and low cost in the same material system. Fortunately, developing cost-effective, efficient, and stable polythiophene:Y6-series acceptor systems9Liang Z. Li M. Wang Q. Qin Y. Stuard S.J. Peng Z. Deng Y. Ade H. Ye L. Geng Y. Optimization Requirements of Efficient Polythiophene:Nonfullerene Organic Solar Cells.Joule. 2020; 4: 1278-1295Abstract Full Text Full Text PDF Scopus (90) Google Scholar,10Xiao J. Jia X. Duan C. Huang F. Yip H.L. Cao Y. Surpassing 13% Efficiency for Polythiophene Organic Solar Cells Processed from Nonhalogenated Solvent.Adv. Mater. 2021; 33: e2008158Crossref PubMed Scopus (46) Google Scholar is presently on the way. The performance-stability conundrum of BTP-based organic solar cellsQin et al.JouleJuly 12, 2021In BriefWe determine the thermal transition temperatures (Tg) of seven BTP-based non-fullerene acceptors and have developed a structure-Tg framework. We also show that PC71BM has a miscibility above the percolation threshold in PM6 and thus can maintain local charge percolation. However, PC71BM is not miscible with BTP-C3-4F and can, thus, not prevent BTP-C3-4F diffusion, and the unfavorable vertical gradients that still degrades performance, a high Tg component with suitable electronic structures that prevent BTP diffusion would be required to achieve commercial viability. Full-Text PDF Open Archive}, number={11}, journal={Chem}, publisher={Elsevier BV}, author={Zou, Yingping and Ye, Long}, year={2021}, month={Nov}, pages={2853–2854} }
@article{zhang_pan_peng_deng_zhang_yuan_chen_ye_wu_gao_et al._2021, title={Ternary copolymers containing 3,4-dicyanothiophene for efficient organic solar cells with reduced energy loss}, url={https://doi.org/10.1039/D1TA03161A}, DOI={10.1039/D1TA03161A}, abstractNote={The introduction of 3,4-dicyanothiophene into the polymer backbone has led to monotonically reduced of non-radiative recombination ΔE3.}, journal={Journal of Materials Chemistry A}, publisher={Royal Society of Chemistry (RSC)}, author={Zhang, Yue and Pan, Langheng and Peng, Zhongxiang and Deng, Wanyuan and Zhang, Bo and Yuan, Xiyue and Chen, Zhili and Ye, Long and Wu, Hongbin and Gao, Xiang and et al.}, year={2021} }
@article{ye_ke_liu_2021, title={The renaissance of polythiophene organic solar cells}, volume={3}, url={https://doi.org/10.1016/j.trechm.2021.09.008}, DOI={10.1016/j.trechm.2021.09.008}, abstractNote={Solar cells comprising P3HT and nonfullerene acceptors have surpassed the 10% efficiency barrier. Polythiophenes are on the way to catch up with the photovoltaic performance of the prevalent push–pull-type polymers. Miscibility matching and crystallization control are two key approaches for the performance optimization of polythiophene-based bulk-heterojunction films. Polythiophenes are low-cost conjugated polymers of great application potential in organic electronics. The past decade has witnessed tremendous advances in the power conversion efficiency (PCE) of organic photovoltaic cells. Concomitantly, the chemical structures of present high-efficiency photovoltaic polymers have become more complex, leading to tedious and harsh synthetic processes and high batch-to-batch variations. By comparison, polythiophenes have gained considerable traction and hold tremendous promise in terms of cost and scalability. In this review, we present state-of-the-art developments in polythiophene solar cells, with a focus on those made of poly(3-hexylthiophene) (P3HT) and nonfullerene small-molecule acceptors. First, the structural optimization of polythiophenes is briefly discussed. Then, we provide a concise discussion of two notable aspects (miscibility matching and crystallization control) for performance optimization and associated research highlights in the past 5 years. We also highlight guidelines to ascertain the scientific challenges for polythiophene:nonfullerene solar cells. The development of new polythiophenes and their bulk-heterojunction blends will help to stimulate advances in many kinds of cost-effective electronics. The past decade has witnessed tremendous advances in the power conversion efficiency (PCE) of organic photovoltaic cells. Concomitantly, the chemical structures of present high-efficiency photovoltaic polymers have become more complex, leading to tedious and harsh synthetic processes and high batch-to-batch variations. By comparison, polythiophenes have gained considerable traction and hold tremendous promise in terms of cost and scalability. In this review, we present state-of-the-art developments in polythiophene solar cells, with a focus on those made of poly(3-hexylthiophene) (P3HT) and nonfullerene small-molecule acceptors. First, the structural optimization of polythiophenes is briefly discussed. Then, we provide a concise discussion of two notable aspects (miscibility matching and crystallization control) for performance optimization and associated research highlights in the past 5 years. We also highlight guidelines to ascertain the scientific challenges for polythiophene:nonfullerene solar cells. The development of new polythiophenes and their bulk-heterojunction blends will help to stimulate advances in many kinds of cost-effective electronics. characterizes the molecular energy of interaction between the components of a binary amorphous system. χaa is often known as the Flory–Huggins interaction parameter. characterizes the molecular energy of interaction between the crystalline component and the amorphous component of a binary system containing crystalline components. a parameter that describes the efficiency, stability, and synthetic complexity of photovoltaic materials. the percentage of the solar energy shining on a solar-cell device that is converted into usable electricity; defined as the proportion of the area under the J–V curve of a solar cell to the input illumination intensity (typically 100 mW/cm2). polymers or small-molecule acceptors that comprise alternating electron-rich and electron-deficient units. a parameter that describes the extent of a polymer in which each repeat unit is derived from the same isomer of the monomer. the current density through a solar-cell device when the voltage across the solar cell is zero.}, number={12}, journal={Trends in Chemistry}, publisher={Elsevier BV}, author={Ye, Long and Ke, Huizhen and Liu, Yang}, year={2021}, month={Dec}, pages={1074–1087} }
@article{thermoplastic elastomer tunes phase structure and promotes stretchability of high-efficiency organic solar cells_2021, url={https://publons.com/wos-op/publon/49339321/}, DOI={10.1002/ADMA.202106732}, abstractNote={Abstract Top‐performance organic solar cells (OSCs) consisting of conjugated polymer donors and nonfullerene small molecule acceptors (NF‐SMAs) deliver rapid increases in efficiencies. Nevertheless, many of the polymer donors exhibit high stiffness and small molecule acceptors are very brittle, which limit their applications in wearable devices. Here, a simple and effective strategy is reported to improve the stretchability and reduce the stiffness of high‐efficiency polymer:NF‐SMA blends and simultaneously maintain the high efficiency by incorporating a low‐cost commercial thermoplastic elastomer, polystyrene‐ block ‐poly(ethylene‐ran‐butylene)‐ block ‐polystyrene (SEBS). The microstructure, mechanical properties, and photovoltaic performance of PM6:N3 with varied SEBS contents and the molecular weight dependence of SEBS on microstructure and mechanical properties are thoroughly characterized. This strategy for mechanical performance improvement exhibits excellent applicability in some other OSC blend systems, e.g., PBQx‐TF:eC9‐2Cl and PBDB‐T:ITIC. More crucially, the elastic modulus of such complex ternary blends can be nicely predicted by a mechanical model. Therefore, incorporating thermoplastic elastomers is a widely applicable and cost‐effective strategy to improve mechanical properties of nonfullerene OSCs and beyond.}, journal={Advanced Materials}, year={2021} }
@article{liu_xian_peng_gao_shi_deng_geng_ye_2021, title={Tuning the molar mass of P3HT via direct arylation polycondensation yields optimal interaction and high efficiency in nonfullerene organic solar cells}, url={https://doi.org/10.1039/D1TA02253A}, DOI={10.1039/D1TA02253A}, abstractNote={The application and the molar mass dependence of P3HT via direct arylation polycondensation are explored in fullerene-free solar cells. The medium molar mass batch delivered a top efficiency of ∼10%.}, journal={Journal of Materials Chemistry A}, publisher={Royal Society of Chemistry (RSC)}, author={Liu, Yang and Xian, Kaihu and Peng, Zhongxiang and Gao, Mengyuan and Shi, Yibo and Deng, Yunfeng and Geng, Yanhou and Ye, Long}, year={2021} }
@article{peng_ye_ade_2021, title={Understanding, quantifying, and controlling the molecular ordering of semiconducting polymers: from novices to experts and amorphous to perfect crystals}, volume={9}, ISSN={["2051-6355"]}, url={https://doi.org/10.1039/D0MH00837K}, DOI={10.1039/D0MH00837K}, abstractNote={Molecular packing and texture of semiconducting polymers are often critical to the performance of devices using these materials. Although frameworks exist to quantify the ordering, interpretations are often just qualitative, resulting in imprecise use of terminology. Here, we reemphasize the significance of quantifying molecular ordering in terms of degree of crystallinity (volume fractions that are ordered) and quality of ordering and their relation to the size scale of an ordered region. We are motivated in part by our own imprecise and inconsistent use of terminology in the past, as well as the need to have a primer or tutorial reference to teach new group members. We strive to develop and use consistent terminology with regards to crystallinity, semicrystallinity, paracrystallinity, and related characteristics. To account for vastly different quality of ordering along different directions, we classify paracrystals into 2D and 3D paracrystals and use paracrystallite to describe the spatial extent of molecular ordering in 1-10 nm. We show that a deeper understanding of molecular ordering can be achieved by combining grazing-incidence wide-angle X-ray scattering and differential scanning calorimetry, even though not all aspects of these measurements are consistent, and some classification appears to be method dependent. We classify a broad range of representative polymers under common processing conditions into five categories based on the quantitative analysis of the paracrystalline disorder parameter (g) and thermal transitions. A small database is presented for 13 representative conjugated and insulating polymers ranging from amorphous to semi-paracrystalline. Finally, we outline the challenges to rationally design more perfect polymer crystals and propose a new molecular design approach that envisions conceptual molecular grafting that is akin to strained and unstrained hetero-epitaxy in classic (compound) semiconductors thin film growth.}, number={2}, journal={MATERIALS HORIZONS}, publisher={Royal Society of Chemistry (RSC)}, author={Peng, Zhengxing and Ye, Long and Ade, Harald}, year={2021}, month={Dec} }
@article{zhang_song_li_li_peng_ye_chen_2020, title={2D covalent organic framework thin films via interfacial self-polycondensation of an A2B2 type monomer}, url={https://doi.org/10.1039/D0CC00758G}, DOI={10.1039/D0CC00758G}, abstractNote={Highly crystalline and oriented 2DPy-COFthin films were readily fabricatedviaan elaborately designed A2B2monomer, and served as stable acidichromism sensors with rapid response, low detection limit and good repeatability.}, journal={Chemical Communications}, publisher={Royal Society of Chemistry (RSC)}, author={Zhang, Bowen and Song, Xiaoyu and Li, Yusen and Li, Yang and Peng, Zhongxiang and Ye, Long and Chen, Long}, year={2020} }
@article{zhang_yu_zhou_wang_tang_xie_xie_hu_yip_ye_et al._2020, title={3,4-Dicyanothiophene-a Versatile Building Block for Efficient Nonfullerene Polymer Solar Cells}, volume={10}, ISSN={["1614-6840"]}, url={https://publons.com/wos-op/publon/32099461/}, DOI={10.1002/aenm.201904247}, abstractNote={Abstract In this contribution, a versatile building block, 3,4‐dicyanothiophene (DCT), which possesses structural simplicity and synthetic accessibility for constructing high‐performance, low‐cost, wide‐bandgap conjugated polymers for use as donors in polymer solar cells (PSCs), is reported. A prototype polymer, PB3TCN‐C66, and its cyano‐free analogue polymer PB3T‐C66, are synthesized to evaluate the potential of using DCT in nonfullerene PSCs. A stronger aggregation property in solution, higher thermal transition temperatures with higher enthalpies, a larger dipole moment, higher relative dielectric constant, and more linear conformation are exhibited by PB3TCN‐C66. Solar cells employing IT‐4F as the electron acceptor offer power conversion efficiencies (PCEs) of 11.2% and 2.3% for PB3TCN‐C66 and PB3T‐C66, respectively. Morphological characterizations reveal that the PB3TCN‐C66:IT‐4F blend exhibits better π–π paracrystallinity, a contracted domain size, and higher phase purity, consistent with its higher molecular interaction parameter, derived from thermodynamic calculations. Moreover, PB3TCN‐C66 offers a higher open‐circuit voltage and reduced energy loss than most state‐of‐the‐art wide‐bandgap polymers, without the need of additional electron‐withdrawing substituents. Two additional polymers derived from DCT also demonstrate promising performance with a higher PCE of 13.4% being achieved. Thus, DCT represents a versatile and promising building block for constructing high‐performance, low‐cost, conjugated polymers for application in PSCs.}, number={12}, journal={ADVANCED ENERGY MATERIALS}, author={Zhang, Bo and Yu, Yonggao and Zhou, Jiadong and Wang, Zhenfeng and Tang, Haoran and Xie, Shenkun and Xie, Zengqi and Hu, Liuyong and Yip, Hin-Lap and Ye, Long and et al.}, year={2020}, month={Mar} }
@article{jiang_huang_sun_li_gao_ye_ade_forrest_fan_2020, title={A 3D nonfullerene electron acceptor with a 9,9 ' -bicarbazole backbone for high -efficiency organic solar cells}, volume={84}, ISSN={["1878-5530"]}, url={https://publons.com/wos-op/publon/32099481/}, DOI={10.1016/j.orgel.2020.105784}, abstractNote={One-dimensional ladder-type nonfullerene electron acceptors (NFAs) with large fused ring cores have been widely used in highly efficient organic solar cells (OSCs). Recent studies have demonstrated that small molecule acceptors with three-dimensional (3D) structures may exhibit low energy loss, and hence can lead to improved OSC performance. In this study, a new 3D NFA (99CZ-8F) with a 9,9′-bicarbazole backbone was designed, synthesized, and characterized, where two linear A-D-A architectures were linked by a single N–N bond. 99CZ-8F showed strong absorption in the range of 500–800 nm in the solid state, which is complementary to the absorption of the donor material PM6. After regulating the morphology of the active layer via binary solvent mixture, the optimized device exhibited a maximum power conversion efficiency (PCE) of 6.6 ± 0.1%, which is among the best reported values for 3D nonfullerene electron acceptor based OSCs.}, journal={ORGANIC ELECTRONICS}, author={Jiang, Chao and Huang, Xinjing and Sun, Bangjin and Li, Yongxi and Gao, Mengyuan and Ye, Long and Ade, Harald and Forrest, Stephen R. and Fan, Jian}, year={2020}, month={Sep} }
@article{a narrow-bandgap n-type polymer with an acceptor-acceptor backbone enabling efficient all-polymer solar cells_2020, url={https://publons.com/wos-op/publon/34238211/}, DOI={10.1002/ADMA.202004183}, abstractNote={Abstract Narrow‐bandgap polymer semiconductors are essential for advancing the development of organic solar cells. Here, a new narrow‐bandgap polymer acceptor L14, featuring an acceptor–acceptor (A–A) type backbone, is synthesized by copolymerizing a dibrominated fused‐ring electron acceptor (FREA) with distannylated bithiophene imide. Combining the advantages of both the FREA and the A–A polymer, L14 not only shows a narrow bandgap and high absorption coefficient, but also low‐lying frontier molecular orbital (FMO) levels. Such FMO levels yield improved electron transfer character, but unexpectedly, without sacrificing open‐circuit voltage ( V oc ), which is attributed to a small nonradiative recombination loss ( E loss,nr ) of 0.22 eV. Benefiting from the improved photocurrent along with the high fill factor and V oc , an excellent efficiency of 14.3% is achieved, which is among the highest values for all‐polymer solar cells (all‐PSCs). The results demonstrate the superiority of narrow‐bandgap A–A type polymers for improving all‐PSC performance and pave a way toward developing high‐performance polymer acceptors for all‐PSCs.}, journal={Advanced Materials}, year={2020} }
@article{guo_lin_liu_dong_guo_ye_ma_tang_ade_zhang_et al._2020, title={Asymmetrically noncovalently fused-ring acceptor for high-efficiency organic solar cells with reduced voltage loss and excellent thermal stability}, volume={74}, ISSN={["2211-3282"]}, url={https://publons.com/wos-op/publon/32099469/}, DOI={10.1016/j.nanoen.2020.104861}, abstractNote={Simultaneously broadening the spectral response and reducing the energy loss are challenging tasks in the material design of organic solar cells (OSCs). Herein, a novel asymmetrically noncovalently fused-ring electron acceptor (NFEA) with unilateral alkylthio-substituted thiophene π-bridge, namely IDST-4F, is synthesized. IDST-4F exhibits a broader absorption, higher-lying energy levels, larger dipole moments and suppressed crystallinity than its symmetric counterpart (ID-4F) without the π-bridge. Compared to the devices of PM6:ID-4F, the optimized PM6:IDST-4F-based devices display simultaneously enhanced current density and photovoltage, resulting in an excellent power conversion efficiency (PCE) of 14.3%, which is the highest value among the OSCs based on NFEAs reported in the literature to date. More importantly, the PM6:IDST-4F-based OSCs possess excellent thermal stability with 82% of the initial PCE after thermal treatment at 150 °C for 1200 min. In summary, this study indicates that asymmetrically NFEAs are promising to achieve high efficiency with excellent thermal stability.}, journal={NANO ENERGY}, author={Guo, Qing and Lin, Ji and Liu, Haiqin and Dong, Xingliang and Guo, Xia and Ye, Long and Ma, Zaifei and Tang, Zheng and Ade, Harald and Zhang, Maojie and et al.}, year={2020}, month={Aug} }
@article{sun_guo_wu_zhang_yang_guo_shi_zhang_kahmann_ye_et al._2020, title={Correction: A multi-objective optimization-based layer-by-layer blade-coating approach for organic solar cells: rational control of vertical stratification for high performance}, url={https://doi.org/10.1039/C9EE90064K}, DOI={10.1039/C9EE90064K}, abstractNote={Correction for ‘A multi-objective optimization-based layer-by-layer blade-coating approach for organic solar cells: rational control of vertical stratification for high performance’ by Rui Sun et al., Energy Environ. Sci., 2019, 12, 3118–3132.}, journal={Energy & Environmental Science}, publisher={Royal Society of Chemistry (RSC)}, author={Sun, Rui and Guo, Jie and Wu, Qiang and Zhang, Zhuohan and Yang, Wenyan and Guo, Jing and Shi, Mumin and Zhang, Yaohong and Kahmann, Simon and Ye, Long and et al.}, year={2020} }
@article{sui_shi_deng_li_bai_wang_dang_han_kirby_ye_et al._2020, title={Direct Arylation Polycondensation of Chlorinated Thiophene Derivatives to High-Mobility Conjugated Polymers}, volume={53}, url={https://doi.org/10.1021/acs.macromol.0c02206}, DOI={10.1021/acs.macromol.0c02206}, abstractNote={High-mobility conjugated polymers (CPs) that can be synthesized in a large scale by direct arylation polycondensation (DArP) are highly desired for printable electronics. To realize this purpose, a readily accessible C–H monomer with high reactivity and selectivity is crucial. Herein, we demonstrated that chlorination enables the efficient DArP of thiophene derivatives, i.e., 3,3′,4,4′-tetrachloro-2,2′-bithiophene (4ClBT) and (E)-1,2-bis(3,4-dichlorothien-2-yl)ethene (4ClTVT), which can be prepared with no more than two steps. No evidence of structure defects was found in the resulting polymers. This finding allows the facile synthesis of high-molecular-weight CPs via DArP. The presence of Cl···S weak intramolecular interaction, which can improve the coplanarity of conjugated skeleton, was confirmed by single-crystal structural analysis. With diketopyrrolopyrrole derivatives as C–Br monomers, CPs with electron mobility up to 1.44 cm2 V–1 s–1 in air have been obtained via DArP. This work demonstrates that chlorinated thiophene derivatives are promising C–H monomers for large-scale synthesis of high-mobility CPs via an atom-economical and “green” method, i.e., DArP.}, number={22}, journal={Macromolecules}, publisher={American Chemical Society (ACS)}, author={Sui, Ying and Shi, Yibo and Deng, Yunfeng and Li, Riqing and Bai, Junhua and Wang, Zhongli and Dang, Yanfeng and Han, Yang and Kirby, Nigel and Ye, Long and et al.}, year={2020}, month={Nov}, pages={10147–10154} }
@article{efficient as-cast polymer solar cells with high and stabilized fill factor_2020, url={https://publons.com/wos-op/publon/35093467/}, DOI={10.1002/SOLR.202000275}, abstractNote={Molecular ordering and miscibility of donor and acceptor materials play critical roles in developing high‐performance as‐cast polymer solar cells (PSCs). In this work, a highly crystalline nonfullerene small molecular acceptor, namely, C8‐IT‐4F, based on alkylated indacenodithieno[3,2‐ b ]thiophene as the aromatic core and 2‐(5,6‐difluoro‐3‐oxo‐2,3‐dihydro‐1 H ‐inden‐1‐ylidene)malononitrile moieties as end groups, is selected and synthesized. The π–π stacking distance in C8‐IT‐4F film can be tuned from 3.88 Å to a more compact (3.48 Å) state by a film‐formation process and the confinement induced by the preaggregated polymer donor PM7, leading to broadened absorption and fine phase separation in the blend film. The optimal morphology with a framework of preaggregated polymer donor, J‐type face‐on π–π stacked acceptor, and appropriate donor/acceptor miscibility facilitates charge generation and transport and reduces charge recombination. As a result, the best PSC based on the as‐cast PM7:C8‐IT‐4F blend film exhibits power conversion efficiency of 14.3%, with an open‐circuit voltage of 0.82 V, a short‐circuit current density of 22.7 mA cm −2 , a fill factor of 77.1%, and good photostability with a stabilized fill factor.}, journal={Solar Rrl}, year={2020} }
@article{pan_liu_wang_ye_luo_ma_pang_chen_ade_yan_et al._2020, title={Efficient Organic Ternary Solar Cells Employing Narrow Band Gap Diketopyrrolopyrrole Polymers and Nonfullerene Acceptors}, volume={32}, url={https://doi.org/10.1021/acs.chemmater.0c02133}, DOI={10.1021/acs.chemmater.0c02133}, abstractNote={Currently, high-performance organic solar cells (OSCs) are mainly composed of narrow band gap (NBG) nonfullerene acceptors and medium band gap (MBG) polymer donors, whereas the solar cells based on NBG polymer donors and MBG nonfullerene acceptors were much less successful. Herein, we report a new diketopyrrolopyrrole (DPP) polymer (PffBT-DPP) with a band gap of 1.33 eV for use in nonfullerene OSCs. When blended with a fullerene acceptor [6, 6]-phenyl C71 butyric acid methyl ester ([70]PCBM) and an MBG nonfullerene acceptor MeIC, the binary OSCs offered a power conversion efficiency (PCE) of 6.8 and 2.0%, respectively. Interestingly, a much higher PCE of 9.0% was achieved for the PffBT-DPP/[70]PCBM/MeIC ternary OSC, which is the sum of the two binary OSCs. The phase-separated morphology in this ternary OSC was characterized and correlated to the device performance. Moreover, the PCE of the ternary OSC is the best result for OSCs employing polymer donors with an optical band gap of <1.40 eV and nonfullerene acceptors. This work demonstrates the potential of constructing high-performance OSCs by employing NBG polymer donors and MBG nonfullerene acceptors.}, number={17}, journal={Chemistry of Materials}, publisher={American Chemical Society (ACS)}, author={Pan, Langheng and Liu, Tao and Wang, Junyi and Ye, Long and Luo, Zhenghui and Ma, Ruijie and Pang, Shuting and Chen, Yuzhong and Ade, Harald and Yan, He and et al.}, year={2020}, month={Sep}, pages={7309–7317} }
@article{ye_xiong_zhang_guo_guan_zou_ade_2020, title={Enhanced efficiency in nonfullerene organic solar cells by tuning molecular order and domain characteristics}, volume={77}, url={https://doi.org/10.1016/j.nanoen.2020.105310}, DOI={10.1016/j.nanoen.2020.105310}, abstractNote={Despite significant advances in the design and synthesis of photovoltaic materials, halogenated solvent additives have been predominately used in the device fabrication of state-of-the-art materials. Also, little attention has been paid to replace these additives with halogen-free ones. Aimed at addressing this problem, this study shows the effectiveness of a hydrocarbon solvent additive, namely 1-phenylnaphthalene (PN) in two high-efficiency polymer:nonfullerene blends (PTB7-Th:IEICS-4F and PM6:Y6) and importantly presents a detailed understanding of the role of PN by combined X-ray scattering and calorimetric analysis. Tuning the concentration of PN allows us to control the film crystallinity and domain correlation characteristics of polymer:nonfullerene blend films, thereby resulting in distinct device performances. Inclusion of 0.5% volume amount of PN dramatically enhances the nonfullerene ordering in the blend films, as evidenced by sharp reflection peaks and high melting enthalpies. The promoted paracrystalline order together with the highest composition variation related to domain purity result in ~35% improvement in the device efficiency of PTB7-Th:IEICS-4F over reference devices. Applying the same treatment results in enhanced efficiency in the PM6:Y6 device, which outperforms its additive-free control device. This mechanistic understanding will be of great significance to the future development of OPVs towards eco-friendly fabrication.}, journal={Nano Energy}, publisher={Elsevier BV}, author={Ye, Long and Xiong, Yuan and Zhang, Maojie and Guo, Xia and Guan, Huilan and Zou, Yingping and Ade, Harald}, year={2020}, month={Nov}, pages={105310} }
@article{pei_wang_peng_zhang_deng_han_ye_geng_2020, title={Impact of Molecular Weight on the Mechanical and Electrical Properties of a High-Mobility Diketopyrrolopyrrole-Based Conjugated Polymer}, volume={53}, url={https://doi.org/10.1021/acs.macromol.0c00209}, DOI={10.1021/acs.macromol.0c00209}, abstractNote={Understanding the key factors influencing the mechanical and electrical properties of semiconducting polymers is crucial to the development of stretchable electronics. In this work, a high-mobility diketopyrrolopyrrole-based conjugated polymer with varied number-average molecular weights (Mn) was used as the model system to explore the impact of molecular weight on the electrical and mechanical properties. Higher-Mn films are more ductile and stretchable. Both hole mobilities of thin-film transistors and elastic modulus become maximum at a moderate Mn of 88 kg/mol. It was found that film continuity, entanglements, and relative degree of crystallinity are critical factors for approaching the best device performance and highest elastic modulus. The transition molecular weight of a given polymer semiconductor is the key to achieving stretchable high-mobility transistors that are practically useful. This work would help to offer guidance to manipulate the mechanical and electrical properties for other polymer semiconductors.}, number={11}, journal={Macromolecules}, publisher={American Chemical Society (ACS)}, author={Pei, Dandan and Wang, Zhongli and Peng, Zhongxiang and Zhang, Jidong and Deng, Yunfeng and Han, Yang and Ye, Long and Geng, Yanhou}, year={2020}, month={Jun}, pages={4490–4500} }
@article{miscibility-controlled phase separation in double-cable conjugated polymers for single-component organic solar cells with efficiencies over 8 %_2020, url={https://publons.com/wos-op/publon/34421637/}, DOI={10.1002/ANIE.202009272}, abstractNote={Abstract A record power conversion efficiency of 8.40 % was obtained in single‐component organic solar cells (SCOSCs) based on double‐cable conjugated polymers. This is realized based on exciton separation playing the same role as charge transport in SCOSCs. Two double‐cable conjugated polymers were designed with almost identical conjugated backbones and electron‐withdrawing side units, but extra Cl atoms had different positions on the conjugated backbones. When Cl atoms were positioned at the main chains, the polymer formed the twist backbones, enabling better miscibility with the naphthalene diimide side units. This improves the interface contact between conjugated backbones and side units, resulting in efficient conversion of excitons into free charges. These findings reveal the importance of charge generation process in SCOSCs and suggest a strategy to improve this process: controlling miscibility between conjugated backbones and aromatic side units in double‐cable conjugated polymers.}, journal={Angewandte Chemie International Edition}, year={2020} }
@article{wang_qin_li_ye_geng_2020, title={Molecular Engineering and Morphology Control of Polythiophene:Nonfullerene Acceptor Blends for High‐Performance Solar Cells}, volume={10}, url={https://doi.org/10.1002/aenm.202002572}, DOI={10.1002/aenm.202002572}, abstractNote={Abstract With the advances in organic photovoltaics (OPVs), the development of low‐cost and easily accessible polymer donors is of vital importance for OPV commercialization. Polythiophene (PT) and its derivatives stand out as the most promising members of the photovoltaic material family for commercial applications, owing to their low cost and high scalability of synthesis. In recent years, PTs, paired with nonfullerene acceptors, have progressed rapidly in photovoltaic performance. This Review gives an overview of the strategies in designing PTs for nonfullerene OPVs from the perspective of energy level modulation. A survey of the typical classes of nonfullerene acceptors designed for pairing with the benchmark PT, i.e., poly(3‐hexylthiophene) (P3HT) is also presented. Furthermore, recent achievements in understanding and controlling the film morphology for PT:nonfullerene blends are discussed in depth. In addition to the effects of molecular weight and blend ratio on film morphology, the crucial roles of miscibility between PT and nonfullerene and processing solvent in determining film microstructure and morphology are highlighted, followed by a discussion on thermal annealing and ternary active layers. Finally, the remaining questions and the prospects of the low‐cost PT:nonfullerene systems are outlined. It is hoped that this review can guide the optimization of PT:nonfullerene blends and advance their commercial applications.}, journal={Advanced Energy Materials}, publisher={Wiley}, author={Wang, Qi and Qin, Yunpeng and Li, Miaomiao and Ye, Long and Geng, Yanhou}, year={2020}, month={Dec}, pages={2002572} }
@article{yang_zhang_ren_gao_bi_ye_hou_2020, title={Molecular design of a non-fullerene acceptor enables a P3HT-based organic solar cell with 9.46% efficiency}, url={https://doi.org/10.1039/D0EE01763A}, DOI={10.1039/D0EE01763A}, abstractNote={A record PCE of ∼9.5% is achieved for a P3HT-based non-fullerene OSC with enhanced VOC and optimized phase separation morphology by modifying the end groups of the NFA, ZY-4Cl.}, journal={Energy & Environmental Science}, publisher={Royal Society of Chemistry (RSC)}, author={Yang, Chenyi and Zhang, Shaoqing and Ren, Junzhen and Gao, Mengyuan and Bi, Pengqing and Ye, Long and Hou, Jianhui}, year={2020} }
@article{xiong_booth_kim_ye_liu_dong_zhang_so_zhu_amassian_et al._2020, title={Novel Bimodal Silver Nanowire Network as Top Electrodes for Reproducible and High‐Efficiency Semitransparent Organic Photovoltaics}, volume={4}, url={https://doi.org/10.1002/solr.202000328}, DOI={10.1002/solr.202000328}, abstractNote={Semitransparent organic photovoltaics (ST‐OPVs) provide a potentially facile route for some applications in building integrated photovoltaics. One of the challenges in developing large‐scale, printable ST‐OPVs is to address the need for high‐performance and fully solution‐processed top electrodes, allowing the replacement of the evaporated thin metallic films (Ag, Au, and Al). Silver nanowire (AgNW) is considered a promising candidate for the substitution due to its excellent transparency, conductivity, and solution processability. Herein, a novel bimodal AgNW (AgNW‐BM) electrode is reported, comprising AgNWs of two different aspect ratios. It is shown that the AgNW‐BM film achieves lower sheet resistance and higher visible transmittance than each monodisperse AgNW film, respectively. Furthermore, ST‐OPVs based on PTB7‐Th:IEICO‐4F with AgNW‐BM top electrodes are fabricated, which can obtain a maximum power conversion efficiency (PCE) of 7.49% with an average visible transmittance (AVT) of 33%. The ST‐devices also demonstrate an enhanced reproducibility and excellent color‐rendering index of 90. In addition, the bimodal top electrode is successfully implemented in the PM6:Y6 system with a higher PCE of 9.79% and with an AVT of 23%, demonstrating the universality for various semiconductor systems. Our work provides a simple strategy to realize fully solution‐processed, highly efficient ST‐OPVs.}, number={10}, journal={Solar RRL}, publisher={Wiley}, author={Xiong, Yuan and Booth, Ronald E. and Kim, Taesoo and Ye, Long and Liu, Yuxuan and Dong, Qi and Zhang, Maojie and So, Franky and Zhu, Yong and Amassian, Aram and et al.}, year={2020}, month={Oct}, pages={2000328} }
@article{liang_li_wang_qin_stuard_peng_deng_ade_ye_geng_2020, title={Optimization Requirements of Efficient Polythiophene:Nonfullerene Organic Solar Cells}, volume={4}, ISSN={["2542-4351"]}, url={https://publons.com/wos-op/publon/33106087/}, DOI={10.1016/J.JOULE.2020.04.014}, abstractNote={Polythiophene (PT) and its derivatives have attracted long-standing attention in the organic photovoltaic community for their low cost and high scalability of synthesis. However, due to the lack of rational guidelines in controlling morphology and matching materials, the power conversion efficiencies (PCEs) based on PTs reported so far are generally below 10%. Here, we establish the first-ever relationship between miscibility, morphology, and device performance of binary blends, based on various nonfullerene acceptors (ITIC-Th1, ITIC, IT4F, IDIC, and Y6) and a PT derivative named PDCBT-Cl by scattering and calorimetric characterizations. Benefiting from a properly quenched mixed phase, PDCBT-Cl:ITIC-Th1 system shows the best efficiency of over 12%. Conversely, the blend of PDCBT-Cl and the star acceptor Y6 remained in a homogeneous state due to their high miscibility, resulting in abysmal performance with PCE of 0.5%. Specific guidelines are also proposed to remediate the performance of PDCBT-Cl:Y6, which are crucial for advancing their practical applications.}, number={6}, journal={JOULE}, author={Liang, Ziqi and Li, Miaomiao and Wang, Qi and Qin, Yunpeng and Stuard, Sam J. and Peng, Zhongxiang and Deng, Yunfeng and Ade, Harald and Ye, Long and Geng, Yanhou}, year={2020}, month={Jun}, pages={1278–1295} }
@article{zheng_yao_ye_xu_zhang_hou_2020, title={PBDB-T and its derivatives: A family of polymer donors enables over 17% efficiency in organic photovoltaics}, volume={35}, url={https://doi.org/10.1016/j.mattod.2019.10.023}, DOI={10.1016/j.mattod.2019.10.023}, abstractNote={Due to the advantages such as being low cost, light weight, and flexible as well as having low toxicity, organic solar cells (OSCs) have attracted extensive interest. The field of OSCs progressed dramatically after the emergence of non-fullerene small molecule acceptors. In addition to the development of these acceptor materials, a key driver in the rapid progress of OSC research was the introduction of the PBDB-T polymer and its derivatives. In this review, we first give a brief overview of the structural features of PBDB-T congeners and the strategies used to design these polymers. The interesting aggregation effects of PBDB-T congeners in solution and solid-states are highlighted. Recent advances in the morphological understanding OSCs based on PBDB-T congeners are discussed using selected examples. In addition, the versatile applications of PBDB-T congeners in OSC devices, including interfacially modified binary, ternary and tandem devices, are also summarized. Importantly, we assess the energy loss and provide a meta-analysis of a library of high-performance PBDB-T type polymers, which are compared with other types of conjugated polymers. Finally, the remaining questions and the prospects of these exciting polymers are suggested.}, journal={Materials Today}, publisher={Elsevier BV}, author={Zheng, Zhong and Yao, Huifeng and Ye, Long and Xu, Ye and Zhang, Shaoqing and Hou, Jianhui}, year={2020}, month={May}, pages={115–130} }
@article{zhang_deng_wu_ye_sun_wang_gao_wu_duan_huang_et al._2020, title={Reduced Energy Loss in Non-Fullerene Organic Solar Cells with Isomeric Donor Polymers Containing Thiazole π-Spacers}, volume={12}, url={https://doi.org/10.1021/acsami.9b18048}, DOI={10.1021/acsami.9b18048}, abstractNote={Large energy loss is one of the key factors that limit the power conversion efficiency (PCE) of organic solar cells (OSCs). In this work, we report reduced energy losses of OSCs via introducing thiazole π-spacers with different orientations to replace the thiophene π-spacers of the prototype polymer PBDB-T. The newly formed thiazole-containing isomeric polymers, PBDBTz-2 and PBDBTz-5, exhibited blue-shifted absorption and deeper lying energy levels compared to PBDB-T. When blended with IT-4F, the two polymers realized PCEs of 10.4% for PBDBTz-2 and 9.6% for PBDBTz-5, respectively, which were higher than that of PBDB-T (PCE = 9.3%). More critically, considerable open-circuit voltage (Voc) enhancements were achieved by PBDBTz-2 and PBDBTz-5, which were 0.14 and 0.21 V higher than that of PBDB-T. A detailed analysis showed that the reduced energy loss resulted from the lower radiative recombination below the band gap and nonradiative recombination loss. This study demonstrated that the introduction of thiazole π-spacers with different orientations is effective to reduce the energy losses of OSCs, which provided valuable inspirations for the development of new conjugated polymers to the efficiency breakthrough of OSCs in future.}, number={1}, journal={ACS Applied Materials & Interfaces}, publisher={American Chemical Society (ACS)}, author={Zhang, Long and Deng, Wanyuan and Wu, Baoqi and Ye, Long and Sun, Xiaofei and Wang, Zhenfeng and Gao, Ke and Wu, Hongbin and Duan, Chunhui and Huang, Fei and et al.}, year={2020}, month={Jan}, pages={753–762} }
@article{balar_siddika_kashani_peng_rech_ye_you_ade_brendan t. o'conner_2020, title={Role of Secondary Thermal Relaxations in Conjugated Polymer Film Toughness}, volume={32}, ISSN={["1520-5002"]}, url={https://publons.com/wos-op/publon/35208553/}, DOI={10.1021/acs.chemmater.0c01910}, abstractNote={Conjugated polymers have proven to be an important class of materials for flexible and stretchable electronics. To ensure long-term thermal and mechanical stability of associated devices, there is a need to determine the origin of the polymer ductility and toughness. In this work, we investigate a variety of high-performance conjugated polymers and relate their thermomechanical behavior to film toughness. Dynamic mechanical analysis (DMA) is used to probe thermomechanical relaxations of the conjugated polymers. Film ductility is measured as a function of temperature to determine the temperature that corresponds to a significant loss in film toughness. We systematically study polymers with changes to the side-chain structure, backbone structure, and crystallinity. We also compare polymers that have a clear glass transition (Tg) to those that do not. It is found that secondary thermal relaxations (sub-Tg) play a critical role in film toughness. This sub-Tg is found to be a local molecular relaxation that appears to relate to side-chain and backbone mobility. We also find that many of the polymers considered continue to show moderate ductility below their sub-Tg, which is attributed to crystallites or aggregates that have active slip systems. These results provide new insights into how conjugated polymer structure and related thermal relaxations influence film toughness that will assist in realizing mechanically robust devices.}, number={15}, journal={CHEMISTRY OF MATERIALS}, author={Balar, Nrup and Siddika, Salma and Kashani, Somayeh and Peng, Zhengxing and Rech, Jeromy James and Ye, Long and You, Wei and Ade, Harald and Brendan T. O'Conner}, year={2020}, month={Aug}, pages={6540–6549} }
@article{gao_liang_geng_ye_2020, title={Significance of thermodynamic interaction parameters in guiding the optimization of polymer:nonfullerene solar cells}, url={https://doi.org/10.1039/D0CC04869K}, DOI={10.1039/D0CC04869K}, abstractNote={Polymer solar cells (PSCs) based on polymer donors and nonfullerene small molecule acceptors are a very attractive technology for solar energy conversion, and their performance is heavily determined by film morphology. It is of considerable interest to reveal instructive morphology-performance relationships of these blends. This feature article discusses the recent advances in analysing the morphology formation of nonfullerene PSCs with an effective polymer thermodynamic quantity, i.e., Flory-Huggins interaction parameter χ. In particular, guidelines of high and low χ systems are summarized. The fundamental understanding of χ and its correlations to film morphology and photovoltaic device parameters is of utmost relevance for providing essential material design criteria, establishing suitable morphology processing guidelines, and thus advancing the practical applications of PSCs based on nonfullerene acceptors.}, journal={Chemical Communications}, publisher={Royal Society of Chemistry (RSC)}, author={Gao, Mengyuan and Liang, Ziqi and Geng, Yanhou and Ye, Long}, year={2020} }
@article{yu_yao_hong_gao_ye_hou_2020, title={TCNQ as a volatilizable morphology modulator enables enhanced performance in non-fullerene organic solar cells}, url={https://doi.org/10.1039/C9TC04892H}, DOI={10.1039/C9TC04892H}, abstractNote={New use of TCNQ as a volatilizable solid additive to optimize the morphology and improve the photovoltaic performance of non-fullerene-based OSCs.}, journal={Journal of Materials Chemistry C}, publisher={Royal Society of Chemistry (RSC)}, author={Yu, Runnan and Yao, Huifeng and Hong, Ling and Gao, Mengyuan and Ye, Long and Hou, Jianhui}, year={2020} }
@article{xu_yao_ma_hong_li_liao_zu_wang_gao_ye_et al._2020, title={Tuning the Hybridization of Local Exciton and Charge‐Transfer States in Highly Efficient Organic Photovoltaic Cells}, volume={59}, url={https://doi.org/10.1002/anie.201915030}, DOI={10.1002/anie.201915030}, abstractNote={Decreasing the energy loss is one of the most feasible ways to improve the efficiencies of organic photovoltaic (OPV) cells. Recent studies have suggested that non-radiative energy loss ( Enon-radloss ) is the dominant factor that hinders further improvements in state-of-the-art OPV cells. However, there is no rational molecular design strategy for OPV materials with suppressed Enon-radloss . Herein, taking molecular surface electrostatic potential (ESP) as a quantitative parameter, we establish a general relationship between chemical structure and intermolecular interactions. The results reveal that increasing the ESP difference between donor and acceptor will enhance the intermolecular interaction. In the OPV cells, the enhanced intermolecular interaction will increase the charge-transfer (CT) state ratio in its hybridization with the local exciton state to facilitate charge generation, but simultaneously result in a larger Enon-radloss . These results suggest that finely tuning the ESP of OPV materials is a feasible method to further improve the efficiencies of OPV cells.}, number={23}, journal={Angewandte Chemie International Edition}, publisher={Wiley}, author={Xu, Ye and Yao, Huifeng and Ma, Lijiao and Hong, Ling and Li, Jiayao and Liao, Qing and Zu, Yunfei and Wang, Jingwen and Gao, Mengyuan and Ye, Long and et al.}, year={2020}, month={Jun}, pages={9004–9010} }
@article{xu_yao_ma_hong_li_liao_zu_wang_gao_ye_et al._2020, title={Tuning the Hybridization of Local Exciton and Charge‐Transfer States in Highly Efficient Organic Photovoltaic Cells}, volume={132}, url={https://doi.org/10.1002/ange.201915030}, DOI={10.1002/ange.201915030}, abstractNote={Abstract Decreasing the energy loss is one of the most feasible ways to improve the efficiencies of organic photovoltaic (OPV) cells. Recent studies have suggested that non‐radiative energy loss ( ) is the dominant factor that hinders further improvements in state‐of‐the‐art OPV cells. However, there is no rational molecular design strategy for OPV materials with suppressed . Herein, taking molecular surface electrostatic potential (ESP) as a quantitative parameter, we establish a general relationship between chemical structure and intermolecular interactions. The results reveal that increasing the ESP difference between donor and acceptor will enhance the intermolecular interaction. In the OPV cells, the enhanced intermolecular interaction will increase the charge‐transfer (CT) state ratio in its hybridization with the local exciton state to facilitate charge generation, but simultaneously result in a larger . These results suggest that finely tuning the ESP of OPV materials is a feasible method to further improve the efficiencies of OPV cells.}, number={23}, journal={Angewandte Chemie}, publisher={Wiley}, author={Xu, Ye and Yao, Huifeng and Ma, Lijiao and Hong, Ling and Li, Jiayao and Liao, Qing and Zu, Yunfei and Wang, Jingwen and Gao, Mengyuan and Ye, Long and et al.}, year={2020}, month={Jun}, pages={9089–9095} }
@article{kang_ye_xu_an_stuard_zhang_yao_ade_hou_2019, title={A Printable Organic Cathode Interlayer Enables over 13% Efficiency for 1-cm(2) Organic Solar Cells}, volume={3}, ISSN={["2542-4351"]}, url={https://publons.com/wos-op/publon/17838771/}, DOI={10.1016/j.joule.2018.10.024}, abstractNote={Currently, most cathode interlayer (CIL) materials for organic solar cells (OSCs) cannot be processed by printing techniques, which severely limits their use in practical productions. Herein, we report a naphthalene diimide (NDI)-based small-molecular compound (N,N-dimethylamino)propyl naphthalene diimide (NDI-N) as printable CIL for OSCs. NDI-N exhibits a unique advantage that combines the merits of high crystallinity and good film-forming property in one material, endowing the semiconductor with excellent electron-transport properties and good processability. By using the NDI-N as CIL, a high power-conversion efficiency (PCE) of 13.9% was achieved in a PBDB-T-2F:IT-4F-based OSC device. More importantly, a large-area OSC device of 1 cm2 was fabricated by using the blade-coated NDI-N CIL and an outstanding PCE of 13.2% was achieved, which represents the highest efficiency of large-area OSCs. The results in this work may pave the way for low-cost and mass production of OSCs.}, number={1}, journal={JOULE}, author={Kang, Qian and Ye, Long and Xu, Bowei and An, Cunbin and Stuard, Samuel J. and Zhang, Shaoqing and Yao, Huifeng and Ade, Harald and Hou, Jianhui}, year={2019}, month={Jan}, pages={227–239} }
@article{sun_guo_wu_zhang_yang_guo_shi_zhang_kahmann_ye_et al._2019, title={A multi-objective optimization-based layer-by-layer blade-coating approach for organic solar cells: rational control of vertical stratification for high performance}, volume={12}, url={https://doi.org/10.1039/C9EE02295C}, DOI={10.1039/C9EE02295C}, abstractNote={This article analyzes and discusses a multi-objective optimization-based layer-by-layer blade-coating approach, which provides a new technology choice for large-scale manufacturing of organic solar cells.}, number={10}, journal={Energy & Environmental Science}, publisher={Royal Society of Chemistry (RSC)}, author={Sun, Rui and Guo, Jie and Wu, Qiang and Zhang, Zhuohan and Yang, Wenyan and Guo, Jing and Shi, Mumin and Zhang, Yaohong and Kahmann, Simon and Ye, Long and et al.}, year={2019}, pages={3118–3132} }
@article{jiang_wei_lai_peng_kim_yuan_ye_ade_zou_yan_2019, title={Alkyl Chain Tuning of Small Molecule Acceptors for Efficient Organic Solar Cells}, volume={3}, ISSN={["2542-4351"]}, url={https://publons.com/wos-op/publon/27161014/}, DOI={10.1016/j.joule.2019.09.010}, abstractNote={The field of organic solar cells has seen rapid developments after the report of a high-efficiency (15.7%) small molecule acceptor (SMA) named Y6. In this paper, we design and synthesize a family of SMAs with an aromatic backbone identical to that of Y6 but with different alkyl chains to investigate the influence of alkyl chains on the properties and performance of the SMAs. First, we show that it is beneficial to use branched alkyl chains on the nitrogen atoms of the pyrrole motif of the Y6. In addition, the branching position of the alkyl chains also has a major influence on material and device properties. The SMA with 3rd-position branched alkyl chains (named N3) exhibits optimal solubility and electronic and morphological properties, thus yielding the best performance. Further device optimization using a ternary strategy allows us to achieve a high efficiency of 16.74% (and a certified efficiency of 16.42%).}, number={12}, journal={JOULE}, author={Jiang, Kui and Wei, Qingya and Lai, Joshua Yuk Lin and Peng, Zhengxing and Kim, Ha Kyung and Yuan, Jun and Ye, Long and Ade, Harald and Zou, Yingping and Yan, He}, year={2019}, month={Dec}, pages={3020–3033} }
@article{yang_ye_yao_jin_ade_chen_2019, title={Black phosphorus nanoflakes as morphology modifier for efficient fullerene-free organic solar cells with high fill-factor and better morphological stability}, volume={12}, ISSN={["1998-0000"]}, url={https://publons.com/wos-op/publon/19724081/}, DOI={10.1007/s12274-019-2288-9}, number={4}, journal={NANO RESEARCH}, author={Yang, Weitao and Ye, Long and Yao, Fenfa and Jin, Chuanhong and Ade, Harald and Chen, Hongzheng}, year={2019}, month={Apr}, pages={777–783} }
@article{wu_fan_liu_chen_yang_ye_ade_zhu_2019, title={Conjugation-Curtailing of Benzodithionopyran-Cored Molecular Acceptor Enables Efficient Air-Processed Small Molecule Solar Cells}, volume={15}, ISSN={["1613-6829"]}, url={https://publons.com/wos-op/publon/29105600/}, DOI={10.1002/smll.201902656}, abstractNote={Abstract Small molecule solar cells (SMSCs) lag a long way behind polymer solar cells. A key limit is the less controllable morphology of small molecule materials, which can be aggravated when incorporating anisotropic nonfullerene acceptors. To fine‐tune the blending morphology within SMSCs, a π‐conjunction curtailing design is applied, which produces a efficient benzodithionopyran‐cored molecular acceptor for nonfullerene SMSCs (NF‐SMSCs). When blended with a molecular donor BDT3TR‐SF to fabricate NF‐SMSCs, the π‐conjunction curtailed molecular acceptor NBDTP‐M obtains an optimal power conversion efficiency (PCE) of up to 10.23%, which is much higher than that of NBDTTP‐M of longer π‐conjunction. It retains 93% of the PCE of devices fabricated in a glove box when all spin‐coating and post‐treating procedures are conducted in ambient air with relative humidity of 25%, which suggests the good air‐processing capability of π‐conjunction curtailed molecules. Detailed X‐ray scattering investigations indicate that the BDT3TR‐SF:NBDTP‐M blend exhibits a blend morphology featuring fine interpenetrating networks with smaller domains and higher phase purity, which results in more efficient charge generation, more balanced charge transport, and less recombination compared to the low‐performance BDT3TR‐SF:NBDTTP‐M blend. This work provides a guideline for molecular acceptors' design toward efficient, low‐cost, air‐processed NF‐SMSCs.}, number={44}, journal={SMALL}, author={Wu, Hao and Fan, Haijun and Liu, Wuyue and Chen, Shanshan and Yang, Changduk and Ye, Long and Ade, Harald and Zhu, Xiaozhang}, year={2019}, month={Oct} }
@article{duan_peng_colberts_pang_ye_awartani_hendriks_ade_wienk_janssen_et al._2019, title={Efficient Thick-Film Polymer Solar Cells with Enhanced Fill Factors via Increased Fullerene Loading}, volume={11}, ISSN={["1944-8252"]}, url={https://doi.org/10.1021/acsami.9b00337}, DOI={10.1021/acsami.9b00337}, abstractNote={Developing effective methods to make efficient bulk-heterojunction polymer solar cells at roll-to-roll relevant active layer thickness is of significant importance. We investigate the effect of fullerene content in polymer:fullerene blends on the fill factor (FF) and on the performance of thick-film solar cells for four different donor polymers PTB7-Th, PDPP-TPT, BDT-FBT-2T, and poly[5,5′-bis(2-butyloctyl)-(2,2′-bithiophene)-4,4′-dicarboxylate-alt-5,5′-2,2′-bithiophene] (PDCBT). At a few hundreds of nanometers thickness, increased FFs are observed in all cases and improved overall device performances are obtained except for PDCBT upon increasing fullerene content in blend films. This fullerene content effect was studied in more detail by electrical and morphological characterization. The results suggest enhanced electron mobility and suppressed bimolecular recombination upon increasing fullerene content in thick polymer:fullerene blend films, which are the result of larger fullerene aggregates and improved interconnectivity of the fullerene phases that provide continuous percolating pathways for electron transport in thick films. These findings are important because an effective and straightforward method that enables fabricating efficient thick-film polymer solar cells is desirable for large-scale manufacturing via roll-to-roll processing and for multijunction devices.}, number={11}, journal={ACS APPLIED MATERIALS & INTERFACES}, publisher={American Chemical Society (ACS)}, author={Duan, Chunhui and Peng, Zhengxing and Colberts, Fallon J. M. and Pang, Shuting and Ye, Long and Awartani, Omar M. and Hendriks, Koen H. and Ade, Harald and Wienk, Martijn M. and Janssen, Rene A. J. and et al.}, year={2019}, month={Mar}, pages={10794–10800} }
@article{yang_liang_ye_ade_yuan_hou_2019, title={Enhanced JSC of P3HT-based non-fullerene polymer solar cells by modulating aggregation effect of P3HT in solution state}, volume={68}, ISSN={1566-1199}, url={http://dx.doi.org/10.1016/J.ORGEL.2019.01.047}, DOI={10.1016/j.orgel.2019.01.047}, abstractNote={Poly(3-hexylthiophene) (P3HT) is a broadly used donor material for polymer solar cells (PSCs) due to its simple molecular structure and low production cost. In recent years, the P3HT-based non-fullerene PSCs have been extensively studied as the rapid development of the non-fullerene small molecular acceptors (NFSMAs). However, the active layers based on the P3HT and NFSMAs blend usually exhibit unfavorable phase separation morphologies, resulting in relatively low short-circuit currents (JSCs) and power conversion efficiencies (PCEs) of the corresponding PSC devices. Herein, we utilized the chloroform (CF)/anisole solvent mixture to adjust the aggregation effect of P3HT in solution state to optimize the phase separation morphology of the active layers. As a result, the combination of CF, anisole, and 1,8-diiodooctane (DIO) affords an enhanced JSC of 14.23 mA cm−2 for a P3HT:IEICO-based PSC.}, journal={Organic Electronics}, publisher={Elsevier BV}, author={Yang, Chenyi and Liang, Ningning and Ye, Long and Ade, Harald and Yuan, Xiaotao and Hou, Jianhui}, year={2019}, month={May}, pages={15–21} }
@article{hu_ye_ghasemi_balar_rech_stuard_you_brendan t. o'connor_ade_2019, title={Highly Efficient, Stable, and Ductile Ternary Nonfullerene Organic Solar Cells from a Two-Donor Polymer Blend}, volume={31}, ISSN={["1521-4095"]}, url={https://publons.com/wos-op/publon/18518240/}, DOI={10.1002/adma.201808279}, abstractNote={Abstract Organic solar cells (OSCs) are one of the most promising cost‐effective options for utilizing solar energy, and, while the field of OSCs has progressed rapidly in device performance in the past few years, the stability of nonfullerene OSCs has received less attention. Developing devices with both high performance and long‐term stability remains challenging, particularly if the material choice is restricted by roll‐to‐roll and benign solvent processing requirements and desirable mechanical durability. Building upon the ink (toluene:FTAZ:IT‐M) that broke the 10% benchmark when blade‐coated in air, a second donor material (PBDB‐T) is introduced to stabilize and enhance performance with power conversion efficiency over 13% while keeping toluene as the solvent. More importantly, the ternary OSCs exhibit excellent thermal stability and storage stability while retaining high ductility. The excellent performance and stability are mainly attributed to the inhibition of the crystallization of nonfullerene small‐molecular acceptors (SMAs) by introducing a stiff donor that also shows low miscibility with the nonfullerene SMA and a slightly higher highest occupied molecular orbital (HOMO) than the host polymer. The study indicates that improved stability and performance can be achieved in a synergistic way without significant embrittlement, which will accelerate the future development and application of nonfullerene OSCs.}, number={17}, journal={ADVANCED MATERIALS}, publisher={Wiley}, author={Hu, Huawei and Ye, Long and Ghasemi, Masoud and Balar, Nrup and Rech, Jeromy James and Stuard, Samuel J. and You, Wei and Brendan T. O'Connor and Ade, Harald}, year={2019}, month={Apr} }
@article{wu_fan_xu_ye_guo_yi_ade_zhu_2019, title={Isomery-Dependent Miscibility Enables High-Performance All-Small-Molecule Solar Cells}, volume={15}, ISSN={["1613-6829"]}, url={https://publons.com/wos-op/publon/14860771/}, DOI={10.1002/smll.201804271}, abstractNote={Abstract Nonfullerene polymer solar cells develop quickly. However, nonfullerene small‐molecule solar cells (NF‐SMSCs) still show relatively inferior performance, attributing to the lack of comprehensive understanding of the structure–performance relationship. To address this issue, two isomeric small‐molecule acceptors, NBDTP‐F out and NBDTP‐F in , with varied oxygen position in the benzodi(thienopyran) (BDTP) core are designed and synthesized. When blended with molecular donor BDT3TR‐SF, devices based on the two isomeric acceptors show disparate photovoltaic performance. Fabricated with an eco‐friendly processing solvent (tetrahydrofuran), the BDT3TR‐SF:NBDTP‐F out blend delivers a high power conversion efficiency of 11.2%, ranked to the top values reported to date, while the BDT3TR‐SF:NBDTP‐F in blend almost shows no photovoltaic response (0.02%). With detailed investigations on inherent optoelectronic processes as well as morphological evolution, this performance disparity is correlated to the interfacial tension of the two combinations and concludes that proper interfacial tension is a key factor for effective phase separation, optimal blend morphology, and superior performance, which can be achieved by the “isomerization” design on molecular acceptors. This work reveals the importance of modulating the materials miscibility by interfacial‐tension‐oriented molecular design, which provides a general guideline toward efficient NF‐SMSCs.}, number={1}, journal={SMALL}, author={Wu, Hao and Fan, Haijun and Xu, Shengjie and Ye, Long and Guo, Yuan and Yi, Yuanping and Ade, Harald and Zhu, Xiaozhang}, year={2019}, month={Jan} }
@article{zhang_ma_ye_qin_xu_liu_wu_zhao_ade_yao_et al._2019, title={Modulation of Building Block Size in Conjugated Polymers with D–A Structure for Polymer Solar Cells}, volume={52}, url={https://doi.org/10.1021/acs.macromol.9b01742}, DOI={10.1021/acs.macromol.9b01742}, abstractNote={D–A conjugated polymers have played critical roles in recently reported nonfullerene acceptors-based polymer solar cells (NF-PSCs) with high performance. Although the molecular design of the D–A polymers is getting more mature, there are still some fundamental unknowns to be unveiled. Here, three new D–A polymers with varied conjugated length for the D-units in their backbones, namely, PDB-1, PDB-2, and PDB-3, were designed, synthesized, and characterized. It was demonstrated that a longer D-unit leads to stronger interchain interaction and higher hole mobility for pristine polymer films. While blending with IT-4F to fabricate photoactive layers in PSCs, it was found that the domain purity, aggregation size, and π–π stacking effect of the polymers can be greatly affected by the D-unit size. Compared to polymers with shorter D-units, for the polymer with the largest D-units (PDB-3), hole and electron transport channels can be much more easily formed in the blend films. Interestingly, the highest efficiency was obtained in the PSCs based on a PDB-2:IT-4F blend, in which PDB-2 shows similar D-unit size to the polymers with state-of-the-art high photovoltaic performance. The correlations between the molecular structure and photovoltaic property of PDB-x polymers demonstrate that the modulation of building block size is an important method for designing high-performance D–A conjugated polymers for PSCs.}, number={20}, journal={Macromolecules}, publisher={American Chemical Society (ACS)}, author={Zhang, Shaoqing and Ma, Lijiao and Ye, Long and Qin, Yunpeng and Xu, Ye and Liu, Xiaoyu and Wu, Yi and Zhao, Wenchao and Ade, Harald and Yao, Huifeng and et al.}, year={2019}, month={Oct}, pages={7929–7938} }
@article{angunawela_ye_bin_zhang_gadisa_li_ade_2019, title={Multi-length scale morphology of nonfullerene all-small molecule blends and its relation to device function in organic solar cells}, volume={3}, ISSN={["2052-1537"]}, url={https://doi.org/10.1039/C8QM00503F}, DOI={10.1039/c8qm00503f}, abstractNote={Device characteristics of a pair of nonfullerene small molecule solar cells were well correlated to their mesoscale morphologyviaresonant soft X-ray scattering.}, number={1}, journal={MATERIALS CHEMISTRY FRONTIERS}, publisher={Royal Society of Chemistry (RSC)}, author={Angunawela, Indunil and Ye, Long and Bin, Haijun and Zhang, Zhi-Guo and Gadisa, Abay and Li, Yongfang and Ade, Harald}, year={2019}, month={Jan}, pages={137–144} }
@article{ye_li_guo_zhang_ade_2019, title={Polymer Side-Chain Variation Induces Microstructural Disparity in Nonfullerene Solar Cells}, volume={31}, ISSN={0897-4756 1520-5002}, url={http://dx.doi.org/10.1021/ACS.CHEMMATER.9B00174}, DOI={10.1021/acs.chemmater.9b00174}, abstractNote={In addition to the innovation of nonfullerene acceptors, the development of highly efficient nonfullerene organic solar cells requires the design of new polymer donors and fundamental understanding of their structural and morphological properties. Utilizing meta-alkoxy-phenyl-substituted benzodithiophene and benzodithiophene-4,8-dione building blocks, we designed and prepared a new class of structurally similar photovoltaic polymers named PBDx (x = 1–4), which are capable of being processed from nonchlorinated solvents. From PBD1 to PBD4, the total carbon number of the alkyl side chains in each repeat unit increased by four in turn. The effect of side chain structure variation on the molecular aggregation, molecular arrangement, mesoscale phase separation, charge transport, and nonfullerene solar cell performance was systematically studied. Our hard and soft X-ray scattering results indicate that small side chain variation yields vastly different molecular packing and mesoscale morphology for these analogues. It was found that PBD1 with the shortest alkyl side chain exhibited the strongest molecular aggregation, most attractive interaction with solvent additive, highest composition variation at a small length scale of 30 nm, and best photovoltaic performance of over 12% efficiency among the four polymers. Moreover, the structure–performance connections were discussed in the context of polymer thermodynamics, and the composition of the mixed phase was most likely quenched closer to the percolation threshold for the PBD1:IDIC system according to solubility limit measurements. This work thus elaborates the origin of such disparity in morphology and performance of nonfullerene solar cells.}, number={17}, journal={Chemistry of Materials}, publisher={American Chemical Society (ACS)}, author={Ye, Long and Li, Wanbin and Guo, Xia and Zhang, Maojie and Ade, Harald}, year={2019}, month={Feb}, pages={6568–6577} }
@article{ye_li_liu_zhang_ghasemi_xiong_hou_ade_2019, title={Quenching to the Percolation Threshold in Organic Solar Cells}, volume={3}, ISSN={["2542-4351"]}, url={https://doi.org/10.1016/j.joule.2018.11.006}, DOI={10.1016/j.joule.2018.11.006}, abstractNote={The general lack of knowing the quench depth and the convolution with key kinetic factors has confounded deeper understanding of the respective importance of these factors in the morphology development of organic solar cells. Here, we determine the quench depth of a high-efficiency system and delineate the need to kinetically quench the mixed domains to a composition close to the percolation threshold. Importantly, the ability to achieve such a quench is very sensitive to structural parameters in polymer solar cells (PSCs) of the polymer PBDB-TF. Only the highest-molecular-weight polymer is able of earlier liquid-solid transition to “lock in” a high-performing PSC morphology with a composition above the miscibility limit and with an efficiency of over 13%. Systems with deep quench depths are therefore sensitive to molecular weight and the kinetic factors of the casting, likely impacting fabrication yield and reliability. They also need to be vitrified for stable performance.}, number={2}, journal={JOULE}, publisher={Elsevier BV}, author={Ye, Long and Li, Sunsun and Liu, Xiaoyu and Zhang, Shaoqing and Ghasemi, Masoud and Xiong, Yuan and Hou, Jianhui and Ade, Harald}, year={2019}, month={Feb}, pages={443–458} }
@article{zhu_gadisa_peng_ghasemi_ye_xu_zhao_ade_2019, title={Rational Strategy to Stabilize an Unstable High-Efficiency Binary Nonfullerene Organic Solar Cells with a Third Component}, volume={9}, ISSN={["1614-6840"]}, url={https://doi.org/10.1002/aenm.201900376}, DOI={10.1002/aenm.201900376}, abstractNote={Abstract Long device lifetime is still a missing key requirement in the commercialization of nonfullerene acceptor (NFA) organic solar cell technology. Understanding thermodynamic factors driving morphology degradation or stabilization is correspondingly lacking. In this report, thermodynamics is combined with morphology to elucidate the instability of highly efficient PTB7‐Th:IEICO‐4F binary solar cells and to rationally use PC 71 BM in ternary solar cells to reduce the loss in the power conversion efficiency from ≈35% to <10% after storage for 90 days and at the same time improve performance. The hypomiscibility observed for IEICO‐4F in PTB7‐Th (below the percolation threshold) leads to overpurification of the mixed domains. By contrast, the hypermiscibility of PC 71 BM in PTB7‐Th of 48 vol% is well above the percolation threshold. At the same time, PC 71 BM is partly miscible in IEICO‐4F suppressing crystallization of IEICO‐4F. This work systematically illustrates the origin of the intrinsic degradation of PTB7‐Th:IEICO‐4F binary solar cells, demonstrates the structure–function relations among thermodynamics, morphology, and photovoltaic performance, and finally carries out a rational strategy to suppress the degradation: the third component needs to have a miscibility in the donor polymer at or above the percolation threshold, yet also needs to be partly miscible with the crystallizable acceptor.}, number={20}, journal={ADVANCED ENERGY MATERIALS}, publisher={Wiley}, author={Zhu, Youqin and Gadisa, Abay and Peng, Zhengxing and Ghasemi, Masoud and Ye, Long and Xu, Zheng and Zhao, Suling and Ade, Harald}, year={2019}, month={May} }
@article{qin_zhang_xu_ye_wu_kong_xu_yao_ade_hou_et al._2019, title={Reduced Nonradiative Energy Loss Caused by Aggregation of Nonfullerene Acceptor in Organic Solar Cells}, volume={9}, ISSN={["1614-6840"]}, url={https://publons.com/wos-op/publon/28504183/}, DOI={10.1002/aenm.201901823}, abstractNote={Abstract Reducing energy loss ( E loss ) is of critical importance to improving the photovoltaic performance of organic solar cells (OSCs). Although nonradiative recombination () is investigated in quite a few works, the method for modulating is seldom reported. Here, a new method of depressing E loss is reported for nonfullerene OSCs. In addition to ternary‐blend bulk heterojunction (BHJ) solar cells, it is proved that a small molecular material (NRM‐1) can be selectively dispersed into the acceptor phase in the PBDB‐T:IT‐4F‐based OSC, resulting in lower and , and hence a significant improvement in the open‐circuit voltage ( V OC ); under an optimal feed ratio of NRM‐1, an enhanced power conversion efficiency can also be gained. Moreover, the role of NRM‐1 in the method is illustrated and its applicability for several other representative OSCs is validated. This work paves a new pathway to reduce the E loss for nonfullerene OSCs.}, number={35}, journal={ADVANCED ENERGY MATERIALS}, author={Qin, Yunpeng and Zhang, Shaoqing and Xu, Ye and Ye, Long and Wu, Yi and Kong, Jingyi and Xu, Bowei and Yao, Huifeng and Ade, Harald and Hou, Jianhui and et al.}, year={2019}, month={Sep} }
@article{ye_xiong_chen_zhang_fei_henry_heeney_o’connor_you_ade_et al._2019, title={Sequential Deposition of Organic Films with Eco-Compatible Solvents Improves Performance and Enables Over 12%-Efficiency Nonfullerene Solar Cells}, volume={31}, ISSN={["1521-4095"]}, url={https://doi.org/10.1002/adma.201808153}, DOI={10.1002/adma.201808153}, abstractNote={Abstract Casting of a donor:acceptor bulk‐heterojunction structure from a single ink has been the predominant fabrication method of organic photovoltaics (OPVs). Despite the success of such bulk heterojunctions, the task ofcontrolling the microstructure in a single casting process has been arduous and alternative approaches are desired. To achieve OPVs with a desirable microstructure, a facile and eco‐compatible sequential deposition approach is demonstrated for polymer/small‐molecule pairs. Using a nominally amorphous polymer as the model material, the profound influence of casting solvent is shown on the molecular ordering of the film, and thus the device performance and mesoscale morphology of sequentially deposited OPVs can be tuned. Static and in situ X‐ray scattering indicate that applying (R)‐(+)‐limonene is able to greatly promote the molecular order of weakly crystalline polymers and form the largest domain spacing exclusively, which correlates well with the best efficiency of 12.5% in sequentially deposited devices. The sequentially cast device generally outperforms its control device based on traditional single‐ink bulk‐heterojunction structure. More crucially, a simple polymer:solvent interaction parameter χ is positively correlated with domain spacing in these sequentially deposited devices. These findings shed light on innovative approaches to rationally create environmentally friendly and highly efficient electronics.}, number={17}, journal={ADVANCED MATERIALS}, publisher={Wiley}, author={Ye, Long and Xiong, Yuan and Chen, Zheng and Zhang, Qianqian and Fei, Zhuping and Henry, Reece and Heeney, Martin and O’Connor, Brendan T. and You, Wei and Ade, Harald and et al.}, year={2019}, month={Apr} }
@article{soft x-ray scattering characterization of polymer semiconductors_2019, url={https://publons.com/wos-op/publon/39003343/}, DOI={10.1201/9780429190520-13}, abstractNote={This chapter provides a timely overview of the application of resonant and polarized soft X-ray scattering in polymer electronics to date. It reviews the basic principles and morphological parameters that dictate the morphology and applications of soft X-ray scattering in the field of polymer semiconductors. The chapter presents a non-exhaustive survey of soft X-ray scattering studies on the basis of representative semiconducting polymeric systems, such as neat polymers, polymer:fullerene blends, polymer:nonfullerene small molecule blends, polymer:polymer blends, and ternary blend systems. It argues that the new quantitative relations established will vastly reduce the parameter space of the trial-and-error synthesis and optimization approach by clearly delineating why a particular set of materials and processing condition might fail, or which aspect may need to be improved. The chapter highlights the state-of-the-art achievements, remaining challenges, and future research developments of soft X-ray scattering.}, journal={CONJUGATED POLYMERS: PERSPECTIVE, THEORY, AND NEW MATERIALS, VOL 2, EDITION}, year={2019} }
@article{soft x-ray scattering characterization of polymer semiconductors_2019, url={https://publons.com/wos-op/publon/49456059/}, journal={CONJUGATED POLYMERS: PROPERTIES, PROCESSING, AND APPLICATIONS, VOL 1, EDITION}, year={2019} }
@article{balar_rech_henry_ye_ade_you_o’connor_2019, title={The Importance of Entanglements in Optimizing the Mechanical and Electrical Performance of All-Polymer Solar Cells}, volume={31}, ISSN={0897-4756 1520-5002}, url={http://dx.doi.org/10.1021/acs.chemmater.9b01011}, DOI={10.1021/acs.chemmater.9b01011}, abstractNote={Organic solar cells that have all-polymer active layers may have several advantages compared with polymer–small molecule systems including improved mechanical and thermodynamic stability; however, an all-polymer active layer does not guarantee robust mechanical behavior. Here, we consider key parameters that may influence the mechanical behavior and power conversion efficiency of all-polymer solar cells (all-PSCs). Considerations include the thermal transition temperature of the polymers, the molecular weight (MW) of the polymers, and film morphology. The impact these features have on mechanical behavior is probed by measuring the cohesive fracture energy (Gc), crack onset strain, and elastic modulus. We find that the selection of ductile polymers with high MW enhances interchain interactions that improve the mechanical resilience of the films. High-MW polymers are also found to maximize the power conversion efficiency (PCE). Using this strategy, BHJ films with the best reported combination of Gc (7.96 J m–2) and PCE (6.94%) are demonstrated. Finally, it is found that increasing the film thickness increases the fracture energy of the films but at the cost of PCE. These findings provide a fundamental perspective on the design strategy to achieve high performance and mechanically robust organic solar cells.}, number={14}, journal={Chemistry of Materials}, publisher={American Chemical Society (ACS)}, author={Balar, Nrup and Rech, Jeromy James and Henry, Reece and Ye, Long and Ade, Harald and You, Wei and O’Connor, Brendan T.}, year={2019}, month={Jun}, pages={5124–5132} }
@article{rech_bauer_dirkes_kaplan_peng_zhang_ye_liu_gao_ade_et al._2019, title={The crucial role of end group planarity for fused-ring electron acceptors in organic solar cells}, volume={3}, url={https://doi.org/10.1039/C9QM00314B}, DOI={10.1039/C9QM00314B}, abstractNote={Planar acceptor moieties in FREAs are necessary, as expanding the π–π stacking by only 1 Å disrupts the packing and decreases performance.}, number={8}, journal={Materials Chemistry Frontiers}, publisher={Royal Society of Chemistry (RSC)}, author={Rech, Jeromy J. and Bauer, Nicole and Dirkes, David and Kaplan, Joseph and Peng, Zhengxing and Zhang, Huotian and Ye, Long and Liu, Shubin and Gao, Feng and Ade, Harald and et al.}, year={2019}, pages={1642–1652} }
@article{cheng_li_guo_yu_lu_bu_ye_ade_chen_geng_2019, title={“Twisted” conjugated molecules as donor materials for efficient all-small-molecule organic solar cells processed with tetrahydrofuran}, url={https://doi.org/10.1039/C9TA07760J}, DOI={10.1039/C9TA07760J}, abstractNote={Appropriately “twisted” conjugated molecules present good solubility in non-halogenated solvents and ordered molecular packing in films.}, journal={Journal of Materials Chemistry A}, publisher={Royal Society of Chemistry (RSC)}, author={Cheng, Xiafei and Li, Miaomiao and Guo, Ziqi and Yu, Jinde and Lu, Guanghao and Bu, Laju and Ye, Long and Ade, Harald and Chen, Yongsheng and Geng, Yanhou}, year={2019} }
@article{li_ye_li_yao_ade_hou_2018, title={A High-Efficiency Organic Solar Cell Enabled by the Strong Intramolecular Electron Push-Pull Effect of the Nonfullerene Acceptor}, volume={30}, ISSN={["1521-4095"]}, url={https://publons.com/wos-op/publon/7528271/}, DOI={10.1002/adma.201707170}, abstractNote={Besides broadening of the absorption spectrum, modulating molecular energy levels, and other well-studied properties, a stronger intramolecular electron push-pull effect also affords other advantages in nonfullerene acceptors. A strong push-pull effect improves the dipole moment of the wings in IT-4F over IT-M and results in a lower miscibility than IT-M when blended with PBDB-TF. This feature leads to higher domain purity in the PBDB-TF:IT-4F blend and makes a contribution to the better photovoltaic performance. Moreover, the strong push-pull effect also decreases the vibrational relaxation, which makes IT-4F more promising than IT-M in reducing the energetic loss of organic solar cells. Above all, a power conversion efficiency of 13.7% is recorded in PBDB-TF:IT-4F-based devices.}, number={16}, journal={ADVANCED MATERIALS}, author={Li, Wanning and Ye, Long and Li, Sunsun and Yao, Huifeng and Ade, Harald and Hou, Jianhui}, year={2018}, month={Apr} }
@article{li_ye_zhao_yan_yang_liu_li_ade_hou_2018, title={A Wide Band Gap Polymer with a Deep Highest Occupied Molecular Orbital Level Enables 14.2% Efficiency in Polymer Solar Cells}, volume={140}, ISSN={["0002-7863"]}, url={https://doi.org/10.1021/jacs.8b02695}, DOI={10.1021/jacs.8b02695}, abstractNote={To simultaneously achieve low photon energy loss (Eloss) and broad spectral response, the molecular design of the wide band gap (WBG) donor polymer with a deep HOMO level is of critical importance in fullerene-free polymer solar cells (PSCs). Herein, we developed a new benzodithiophene unit, i.e., DTBDT-EF, and conducted systematic investigations on a WBG DTBDT-EF-based donor polymer, namely, PDTB-EF-T. Due to the synergistic electron-withdrawing effect of the fluorine atom and ester group, PDTB-EF-T exhibits a higher oxidation potential, i.e., a deeper HOMO level (ca. −5.5 eV) than most well-known donor polymers. Hence, a high open-circuit voltage of 0.90 V was obtained when paired with a fluorinated small molecule acceptor (IT-4F), corresponding to a low Eloss of 0.62 eV. Furthermore, side-chain engineering demonstrated that subtle side-chain modulation of the ester greatly influences the aggregation effects and molecular packing of polymer PDTB-EF-T. With the benefits of the stronger interchain π–π interaction, the improved ordering structure, and thus the highest hole mobility, the most symmetric charge transport and reduced recombination are achieved for the linear decyl-substituted PDTB-EF-T (P2)-based PSCs, leading to the highest short-circuit current density and fill factor (FF). Due to the high Flory–Huggins interaction parameter (χ), surface-directed phase separation occurs in the P2:IT-4F blend, which is supported by X-ray photoemission spectroscopy results and cross-sectional transmission electron microscope images. By taking advantage of the vertical phase distribution of the P2:IT-4F blend, a high power conversion efficiency (PCE) of 14.2% with an outstanding FF of 0.76 was recorded for inverted devices. These results demonstrate the great potential of the DTBDT-EF unit for future organic photovoltaic applications.}, number={23}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, publisher={American Chemical Society (ACS)}, author={Li, Sunsun and Ye, Long and Zhao, Wenchao and Yan, Hongping and Yang, Bei and Liu, Delong and Li, Wanning and Ade, Harald and Hou, Jianhui}, year={2018}, month={Jun}, pages={7159–7167} }
@article{qin_ye_zhang_zhu_yang_ade_hou_2018, title={A polymer design strategy toward green solvent processed efficient non-fullerene polymer solar cells}, volume={6}, ISSN={["2050-7496"]}, url={https://doi.org/10.1039/C8TA00368H}, DOI={10.1039/c8ta00368h}, abstractNote={This work suggests an effective material design strategy to prepare efficient PSCs with a green solvent, which is important in PSCs.}, number={10}, journal={JOURNAL OF MATERIALS CHEMISTRY A}, publisher={Royal Society of Chemistry (RSC)}, author={Qin, Yunpeng and Ye, Long and Zhang, Shaoqing and Zhu, Jie and Yang, Bei and Ade, Harald and Hou, Jianhui}, year={2018}, month={Mar}, pages={4324–4330} }
@article{song_gasparini_ye_yao_hou_ade_baran_2018, title={Controlling Blend Morphology for Ultrahigh Current Density in Nonfullerene Acceptor-Based Organic Solar Cells}, volume={3}, ISSN={2380-8195 2380-8195}, url={http://dx.doi.org/10.1021/ACSENERGYLETT.7B01266}, DOI={10.1021/ACSENERGYLETT.7B01266}, abstractNote={In this Letter, we highlight a system with a well-known polymer donor (PTB7-Th) blended with a narrow band gap nonfullerene acceptor (IEICO-4F) as the active layer and 1-chloronaphthalene (CN) as the solvent additive. Optimization of the photoactive layer nanomorphology yields a short-circuit current density value of 27.3 mA/cm2, one of the highest values in organic solar cells reported to date, which competes with other types of solution-processed solar cells such as perovskite or quantum dot devices. Along with decent open-circuit voltage (0.71 V) and fill factor values (66%), a power conversion efficiency of 12.8% is achieved for the champion devices. Morphology characterizations elucidate that the origin of this high photocurrent is mainly the increased π–π coherence length of the acceptor, the domain spacing, as well as the mean-square composition variation of the blend. Optoelectronic measurements confirm a balanced hole and electron mobility and reduced trap-assisted recombination for the best devices.}, number={3}, journal={ACS Energy Letters}, publisher={American Chemical Society (ACS)}, author={Song, Xin and Gasparini, Nicola and Ye, Long and Yao, Huifeng and Hou, Jianhui and Ade, Harald and Baran, Derya}, year={2018}, month={Jan}, pages={669–676} }
@article{bin_yao_yang_angunawela_sun_gao_ye_qiu_xue_zhu_et al._2018, title={High-Efficiency All-Small-Molecule Organic Solar Cells Based on an Organic Molecule Donor with Alkylsilyl-Thienyl Conjugated Side Chains}, volume={30}, ISSN={["1521-4095"]}, url={https://publons.com/wos-op/publon/7528268/}, DOI={10.1002/adma.201706361}, abstractNote={Abstract Two medium‐bandgap p‐type organic small molecules H21 and H22 with an alkylsily‐thienyl conjugated side chain on benzo[1,2‐ b :4,5‐ b ′]dithiophene central units are synthesized and used as donors in all‐small‐molecule organic solar cells (SM‐OSCs) with a narrow‐bandgap n‐type small molecule 2,2′‐((2Z,2′Z)‐((4,4,9,9‐tetrahexyl‐4,9‐dihydro‐ s ‐indaceno[1,2‐ b :5,6‐ b ′]dithiophene‐2,7‐diyl)bis(methanylylidene))bis(3‐oxo‐2,3‐dihydro‐1H‐indene‐2,1‐diylidene))dimalononitrile (IDIC) as the acceptor. In comparison to H21 with 3‐ethyl rhodanine as the terminal group, H22 with cyanoacetic acid esters as the terminal group shows blueshifted absorption, higher charge‐carrier mobility and better 3D charge pathway in blend films. The power conversion efficiency (PCE) of the SM‐OSCs based on H22:IDIC reaches 10.29% with a higher open‐circuit voltage of 0.942 V and a higher fill factor of 71.15%. The PCE of 10.29% is among the top efficiencies of nonfullerene SM‐OSCs reported in the literature to date.}, number={27}, journal={ADVANCED MATERIALS}, author={Bin, Haijun and Yao, Jia and Yang, Yankang and Angunawela, Indunil and Sun, Chenkai and Gao, Liang and Ye, Long and Qiu, Beibei and Xue, Lingwei and Zhu, Chenhui and et al.}, year={2018}, month={Jul} }
@article{feng_yang_xu_zhang_yan_awartani_ye_ade_li_peng_et al._2018, title={High-Performance Wide Bandgap Copolymers Using an EDOT Modified Benzodithiophene Donor Block with 10.11% Efficiency}, volume={8}, ISSN={["1614-6840"]}, url={https://publons.com/wos-op/publon/7528267/}, DOI={10.1002/aenm.201602773}, abstractNote={Abstract Newly developed benzo[1,2‐b:4,5‐b′]dithiophene (BDT) block with 3,4‐ethylenedioxythiophene (EDOT) side chains is first employed to build efficient photovoltaic copolymers. The resulting copolymers, PBDTEDOT‐BT and PBDTEDOTFBT, have a large bandgap more than 1.80 eV, which is attributed to the increased steric hindrance between the BDT and EDOT skeletons. Both copolymers possess the satisfied absorptions, low‐lying highest occupied molecular orbital (HOMO) levels and high crystallinity. Using the fluorination strategy, PBDTEDOT‐FBT exhibits a wider and stronger absorption and a deeper HOMO level than those of PBDTEDOT‐BT. PBDTEDOT‐FBT:[6,6]‐Phenyl C 71 butyric acid methyl ester (PC 71 BM) blend also shows the higher hole mobility and better surface morphology compared with the PBDTEDOTBT:PC 71 BM blend. Combination of above advantages, PBDTEDOT‐FBT devices exhibit much higher power conversion efficiency (PCE) of 10.11%, with an improved open circuit voltage (V oc ) of 0.86 V, short circuit current densities (J sc ) of 16.01 mA cm −2 , and fill factor (FF) of 72.6%. This work not only provides a newly efficient candidate of BDT donor block modified with EDOT conjugated side chains, but also achieves high‐performance large bandgap copolymers for polymer solar cells (PSCs) via the synergistic effect of fluorination and side chain engineering strategies.}, number={6}, journal={ADVANCED ENERGY MATERIALS}, author={Feng, K. and Yang, G. F. and Xu, X. P. and Zhang, G. J. and Yan, H. and Awartani, O. and Ye, Long and Ade, H. and Li, Y. and Peng, Q. and et al.}, year={2018}, month={Feb} }
@article{hu_jiang_chow_ye_zhang_li_carpenter_ade_yan_2018, title={Influence of Donor Polymer on the Molecular Ordering of Small Molecular Acceptors in Nonfullerene Polymer Solar Cells}, volume={8}, ISSN={["1614-6840"]}, url={https://publons.com/wos-op/publon/7528287/}, DOI={10.1002/aenm.201701674}, abstractNote={Abstract Nonfullerene polymer solar cells (PSCs) based on polymer donors and nonfullerene small molecular acceptors (SMAs) have recently attracted considerable attention. Although much of the progress is driven by the development of novel SMAs, the donor polymer also plays an important role in achieving efficient nonfullerene PSCs. However, it is far from clear how the polymer donor choice influences the morphology and performance of the SMAs and the nonfullerene blends. In addition, it is challenging to carry out quantitative analysis of the morphology of polymer:SMA blends, due to the low material contrast and overlapping scattering features of the π–π stacking between the two organic components. Here, a series of nonfullerene blends is studied based on ITIC‐Th blended with five different donor polymers. Through quantitative morphology analysis, the (010) coherence length of the SMA is characterized and a positive correlation between the coherence length of the SMA and the device fill factor (FF) is established. The study reveals that the donor polymer can significantly change the molecular ordering of the SMA and thus improve the electron mobility and domain purity of the blend, which has an overall positive effect that leads to the enhanced device FF for nonfullerene PSCs.}, number={5}, journal={ADVANCED ENERGY MATERIALS}, author={Hu, Huawei and Jiang, Kui and Chow, Philip C. Y. and Ye, Long and Zhang, Guangye and Li, Zhengke and Carpenter, Joshua H. and Ade, Harald and Yan, He}, year={2018}, month={Feb} }
@article{ziffer_jo_zhong_ye_liu_lin_zhang_li_ade_jen_et al._2018, title={Long-Lived, Non-Geminate, Radiative Recombination of Photogenerated Charges in a Polymer/Small-Molecule Acceptor Photovoltaic Blend}, volume={140}, ISSN={0002-7863 1520-5126}, url={http://dx.doi.org/10.1021/JACS.8B05834}, DOI={10.1021/jacs.8b05834}, abstractNote={Minimization of open-circuit-voltage ( VOC) loss is required to transcend the efficiency limitations on the performance of organic photovoltaics (OPV). We study charge recombination in an OPV blend comprising a polymer donor with a small molecule nonfullerene acceptor that exhibits both high photovoltaic internal quantum efficiency and relatively high external electroluminescence quantum efficiency. Notably, this donor/acceptor blend, consisting of the donor polymer commonly referred to as PCE10 with a pseudoplanar small molecule acceptor (referred to as FIDTT-2PDI) exhibits relatively bright delayed photoluminescence on the microsecond time scale beyond that observed in the neat material. We study the photoluminescence decay kinetics of the blend in detail and conclude that this long-lived photoluminescence arises from radiative nongeminate recombination of charge carriers, which we propose occurs via a donor/acceptor CT state located close in energy to the singlet state of the polymer donor. Additionally, crystallographic and spectroscopic studies point toward low subgap disorder, which could be beneficial for low radiative and nonradiative losses. These results provide an important demonstration of photoluminescence due to nongeminate charge recombination in an efficient OPV blend, a key step in identifying new OPV materials and materials-screening criteria if OPV is to approach the theoretical limits to efficiency.}, number={31}, journal={Journal of the American Chemical Society}, publisher={American Chemical Society (ACS)}, author={Ziffer, Mark E. and Jo, Sae Byeok and Zhong, Hongliang and Ye, Long and Liu, Hongbin and Lin, Francis and Zhang, Jie and Li, Xiaosong and Ade, Harald W. and Jen, Alex K.-Y. and et al.}, year={2018}, month={Jul}, pages={9996–10008} }
@article{peng_jiao_ye_li_rech_you_hou_ade_2018, title={Measuring Temperature-Dependent Miscibility for Polymer Solar Cell Blends: An Easily Accessible Optical Method Reveals Complex Behavior}, volume={30}, ISSN={["1520-5002"]}, url={https://doi.org/10.1021/acs.chemmater.8b00889}, DOI={10.1021/acs.chemmater.8b00889}, abstractNote={In bulk-heterojunction polymer solar cells (PSC), the molecular-level mixing between conjugated polymer donors and small-molecule acceptors plays a crucial role in obtaining a desirable morphology and good device stability. It has been recently shown that the thermodynamic limit of this mixing can be quantified by the liquidus miscibility, the composition of the small-molecule acceptor in amorphous phases in the presence of small-molecule crystals, and then converted to the Flory–Huggins interaction parameter χ. This conversion maps out the amorphous miscibility. Moreover, the quantitative relations between χ and the fill factor of PSC devices were established recently. However, the commonly used measurement of this liquidus miscibility, scanning transmission X-ray microscopy, is not easily and readily accessible. Here, we delineate a method based on common visible light microscopy and ultraviolet–visible absorption spectroscopy to replace the X-ray measurements. To demonstrate the feasibility of this technique and methodology, a variety of conjugated polymers (PffBT4T-C9C13, PDPP3T PBDT-TS1, PTB7-Th, and FTAZ) and their miscibility with fullerenes or nonfullerene small molecules (PC71BM, PC61BM, and EH-IDTBR) are characterized. The establishment of this methodology will pave the way to a wider use of the liquidus miscibility and the critical miscibility-function relations to optimize the device performance and obtain good stability in PSCs and other devices.}, number={12}, journal={CHEMISTRY OF MATERIALS}, publisher={American Chemical Society (ACS)}, author={Peng, Zhengxing and Jiao, Xuechen and Ye, Long and Li, Sunsun and Rech, Jeromy James and You, Wei and Hou, Jianhui and Ade, Harald}, year={2018}, month={Jun}, pages={3943–3951} }
@article{ye_collins_jiao_zhao_yan_ade_2018, title={Miscibility-Function Relations in Organic Solar Cells: Significance of Optimal Miscibility in Relation to Percolation}, volume={8}, ISSN={["1614-6840"]}, url={https://doi.org/10.1002/aenm.201703058}, DOI={10.1002/aenm.201703058}, abstractNote={Abstract Polymer solar cells (PSCs) continue to be a promising low‐cost and lead‐free photovoltaic technology. Of critical importance to PSCs is understanding and manipulating the composition of the amorphous mixed phase, which is governed by the thermodynamic molecular interactions of the polymer donor and acceptor molecules and the kinetics of the casting process. This progress report clarifies and defines nomenclature relating to miscibility and its relevance and implications to PSC devices in light of new developments. Utilizing a scanning transmission X‐ray microscopy method, the temperature dependences of “molecular miscibility” in the presence of fullerene crystals, now referred to liquidus miscibility, are presented for a number of representative blends. An emphasis is placed on relating the amorphous miscibility of high‐efficiency PSC blends at a given processing temperature with their actual device performance and stability. It is shown and argued that a system with an amorphous miscibility close to percolation exhibits the most stable morphology. Furthermore, an approach is outlined to convert liquidus miscibility to an effective Flory–Huggins interaction parameter χ. Crucially, determination of temperature‐dependent amorphous miscibility paves a way to rationally optimize the stability and mixing behaviors of PSCs at actual processing and operating temperatures.}, number={28}, journal={ADVANCED ENERGY MATERIALS}, publisher={Wiley}, author={Ye, Long and Collins, Brian A. and Jiao, Xuechen and Zhao, Jingbo and Yan, He and Ade, Harald}, year={2018}, month={Oct} }
@article{ye_hu_ghasemi_wang_collins_kim_jiang_carpenter_li_li_et al._2018, title={Quantitative relations between interaction parameter, miscibility and function in organic solar cells}, volume={17}, ISSN={["1476-4660"]}, url={https://doi.org/10.1038/s41563-017-0005-1}, DOI={10.1038/s41563-017-0005-1}, number={3}, journal={NATURE MATERIALS}, publisher={Springer Nature}, author={Ye, Long and Hu, Huawei and Ghasemi, Masoud and Wang, Tonghui and Collins, Brian A. and Kim, Joo-Hyun and Jiang, Kui and Carpenter, Joshua H. and Li, Hong and Li, Zhengke and et al.}, year={2018}, month={Mar}, pages={253–260} }
@article{xiong_ye_gadisa_zhang_rech_you_ade_2018, title={Revealing the Impact of F4-TCNQ as Additive on Morphology and Performance of High-Efficiency Nonfullerene Organic Solar Cells}, volume={29}, ISSN={1616-301X}, url={http://dx.doi.org/10.1002/ADFM.201806262}, DOI={10.1002/adfm.201806262}, abstractNote={Abstract Fluorinated molecule 2,3,5,6‐tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane (F4‐TCNQ) and its derivatives have been used in polymer:fullerene solar cells primarily as a dopant to optimize the electrical properties and device performance. However, the underlying mechanism and generality of how F4‐TCNQ affects device operation and possibly the morphology is poorly understood, particularly for emerging nonfullerene organic solar cells. In this work, the influence of F4‐TCNQ on the blend film morphology and photovoltaic performance of nonfullerene solar cells processed by a single halogen‐free solvent is systematically investigated using a set of morphological and electrical characterizations. In solar cells with a high‐performance polymer:small molecule blend FTAZ:IT‐M, F4‐TCNQ has a negligibly small effect on the molecular packing and surface characteristics, while it clearly affects the electronic properties and mean‐square composition variation of the bulk. In comparison to the control devices with an average power conversion efficiency (PCE) of 11.8%, inclusion of a trace amount of F4‐TCNQ in the active layer has improved device fill factor and current density, which has resulted into a PCE of 12.4%. Further increase in F4‐TCNQ content degrades device performance. This investigation aims at delineating the precise role of F4‐TCNQ in nonfullerene bulk heterojunction films, and thereby establishing a facile approach to fabricate highly optimized nonfullerene solar cells.}, number={1}, journal={Advanced Functional Materials}, publisher={Wiley}, author={Xiong, Yuan and Ye, Long and Gadisa, Abay and Zhang, Qianqian and Rech, Jeromy James and You, Wei and Ade, Harald}, year={2018}, month={Nov}, pages={1806262} }
@article{ye_xiong_zhang_li_wang_jiang_hou_you_ade_2018, title={Surpassing 10% Efficiency Benchmark for Nonfullerene Organic Solar Cells by Scalable Coating in Air from Single Nonhalogenated Solvent}, volume={30}, ISSN={0935-9648}, url={http://dx.doi.org/10.1002/ADMA.201705485}, DOI={10.1002/adma.201705485}, abstractNote={The commercialization of nonfullerene organic solar cells (OSCs) critically relies on the response under typical operating conditions (for instance, temperature and humidity) and the ability of scale-up. Despite the rapid increase in power conversion efficiency (PCE) of spin-coated devices fabricated in a protective atmosphere, the efficiencies of printed nonfullerene OSC devices by blade coating are still lower than 6%. This slow progress significantly limits the practical printing of high-performance nonfullerene OSCs. Here, a new and relatively stable nonfullerene combination is introduced by pairing the nonfluorinated acceptor IT-M with the polymeric donor FTAZ. Over 12% efficiency can be achieved in spin-coated FTAZ:IT-M devices using a single halogen-free solvent. More importantly, chlorine-free, blade coating of FTAZ:IT-M in air is able to yield a PCE of nearly 11% despite a humidity of ≈50%. X-ray scattering results reveal that large π-π coherence length, high degree of face-on orientation with respect to the substrate, and small domain spacing of ≈20 nm are closely correlated with such high device performance. The material system and approach yield the highest reported performance for nonfullerene OSC devices by a coating technique approximating scalable fabrication methods and hold great promise for the development of low-cost, low-toxicity, and high-efficiency OSCs by high-throughput production.}, number={8}, journal={Advanced Materials}, publisher={Wiley}, author={Ye, Long and Xiong, Yuan and Zhang, Qianqian and Li, Sunsun and Wang, Cheng and Jiang, Zhang and Hou, Jianhui and You, Wei and Ade, Harald}, year={2018}, month={Jan}, pages={1705485} }
@article{ye_xiong_zhang_li_wang_jiang_hou_you_ade_2018, title={Surpassing 10% efficiency benchmark for nonfullerene organic solar cells by scalable coating in air from single nonhalogenated solvent}, volume={30}, DOI={10.1002/adma.201870054}, abstractNote={Realizing over 10% efficiency in printed organic solar cells via scalable materials and less toxic solvents remains a grand challenge. In article number 1705485, Harald Ade and co-workers report chlorine-free, in-air blade-coating of a new photoactive combination, FTAZ:IT-M, which is able to yield an efficiency of nearly 11%, despite a high humidity of ≈50%.}, number={8}, journal={Advanced Materials}, author={Ye, Long and Xiong, Y. and Zhang, Q. Q. and Li, S. S. and Wang, C. and Jiang, Z. and Hou, J. H. and You, W. and Ade, H.}, year={2018} }
@article{bin_yang_zhang_ye_ghasem_chen_zhang_zhang_sun_xue_et al._2017, title={9.73% Efficiency Nonfullerene All Organic Small Molecule Solar Cells with Absorption-Complementary Donor and Acceptor}, volume={139}, ISSN={["0002-7863"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=MEDLINE&KeyUT=MEDLINE:28322045&KeyUID=MEDLINE:28322045}, DOI={10.1021/jacs.6b12826}, abstractNote={In the last two years, polymer solar cells (PSCs) developed quickly with n-type organic semiconductor (n-OSs) as acceptor. In contrast, the research progress of nonfullerene organic solar cells (OSCs) with organic small molecule as donor and the n-OS as acceptor lags behind. Here, we synthesized a D-A structured medium bandgap organic small molecule H11 with bithienyl-benzodithiophene (BDTT) as central donor unit and fluorobenzotriazole as acceptor unit, and achieved a power conversion efficiency (PCE) of 9.73% for the all organic small molecules OSCs with H11 as donor and a low bandgap n-OS IDIC as acceptor. A control molecule H12 without thiophene conjugated side chains on the BDT unit was also synthesized for investigating the effect of the thiophene conjugated side chains on the photovoltaic performance of the p-type organic semiconductors (p-OSs). Compared with H12, the 2D-conjugated H11 with thiophene conjugated side chains shows intense absorption, low-lying HOMO energy level, higher hole mobility and ordered bimodal crystallite packing in the blend films. Moreover, a larger interaction parameter (χ) was observed in the H11 blends calculated from Hansen solubility parameters and differential scanning calorimetry measurements. These special features combined with the complementary absorption of H11 donor and IDIC acceptor resulted in the best PCE of 9.73% for nonfullerene all small molecule OSCs up to date. Our results indicate that fluorobenzotriazole based 2D conjugated p-OSs are promising medium bandgap donors in the nonfullerene OSCs.}, number={14}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, publisher={American Chemical Society (ACS)}, author={Bin, Haijun and Yang, Yankang and Zhang, Zhi-Guo and Ye, Long and Ghasem, Masoud and Chen, Shanshan and Zhang, Yindong and Zhang, Chunfeng and Sun, Chenkai and Xue, Lingwei and et al.}, year={2017}, month={Apr}, pages={5085–5094} }
@article{zhong_ye_chen_jo_chueh_carpenter_ade_jen_2017, title={A regioregular conjugated polymer for high performance thick-film organic solar cells without processing additive}, volume={5}, ISSN={["2050-7496"]}, url={https://doi.org/10.1039/C7TA02391J}, DOI={10.1039/c7ta02391j}, abstractNote={Regioregular PTB7-Th with pre-designated repeat units achieves over 10% efficiency in thick-film solar cells without the assistance of a solvent additive.}, number={21}, journal={JOURNAL OF MATERIALS CHEMISTRY A}, publisher={Royal Society of Chemistry (RSC)}, author={Zhong, Hongliang and Ye, Long and Chen, Jung-Yao and Jo, Sae Byeok and Chueh, Chu-Chen and Carpenter, Joshua H. and Ade, Harald and Jen, Alex K. -Y.}, year={2017}, month={Jun}, pages={10517–10525} }
@article{yao_ye_hou_jang_han_cui_su_wang_gao_yu_et al._2017, title={Achieving Highly Efficient Nonfullerene Organic Solar Cells with Improved Intermolecular Interaction and Open-Circuit Voltage}, volume={29}, ISSN={0935-9648}, url={http://dx.doi.org/10.1002/ADMA.201700254}, DOI={10.1002/ADMA.201700254}, abstractNote={A new acceptor–donor–acceptor‐structured nonfullerene acceptor ITCC (3,9‐bis(4‐(1,1‐dicyanomethylene)‐3‐methylene‐2‐oxo‐cyclopenta[ b ]thiophen)‐5,5,11,11‐tetrakis(4‐hexylphenyl)‐dithieno[2,3‐ d ′:2,3‐ d′ ]‐s‐indaceno[1,2‐ b :5,6‐ b′ ]‐dithiophene) is designed and synthesized via simple end‐group modification. ITCC shows improved electron‐transport properties and a high‐lying lowest unoccupied molecular orbital level. A power conversion efficiency of 11.4% with an impressive V OC of over 1 V is recorded in photovoltaic devices, suggesting that ITCC has great potential for applications in tandem organic solar cells.}, number={21}, journal={Advanced Materials}, publisher={Wiley}, author={Yao, Huifeng and Ye, Long and Hou, Junxian and Jang, Bomee and Han, Guangchao and Cui, Yong and Su, Gregory M. and Wang, Cheng and Gao, Bowei and Yu, Runnan and et al.}, year={2017}, month={Mar}, pages={1700254} }
@article{bauer_zhang_zhao_ye_kim_constantinou_yan_so_ade_yan_et al._2017, title={Comparing non-fullerene acceptors with fullerene in polymer solar cells: a case study with FTAZ and PyCNTAZ}, volume={5}, ISSN={["2050-7496"]}, url={https://doi.org/10.1039/C6TA10450A}, DOI={10.1039/c6ta10450a}, abstractNote={Non-fullerene acceptors (NFAs) are becoming a serious contender to fullerene-based electron acceptors in organic photovoltaics, due to their structural versatility and easily tunable optical and electronic properties.}, number={10}, journal={JOURNAL OF MATERIALS CHEMISTRY A}, publisher={Royal Society of Chemistry (RSC)}, author={Bauer, Nicole and Zhang, Qianqian and Zhao, Jingbo and Ye, Long and Kim, Joo-Hyun and Constantinou, Iordania and Yan, Liang and So, Franky and Ade, Harald and Yan, He and et al.}, year={2017}, month={Mar}, pages={4886–4893} }
@article{ye_jiao_zhang_yao_qin_ade_hou_2017, title={Control of Mesoscale Morphology and Photovoltaic Performance in Diketopyrrolopyrrole-Based Small Band Gap Terpolymers}, volume={7}, ISSN={["1614-6840"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000394940100003&KeyUID=WOS:000394940100003}, DOI={10.1002/aenm.201601138}, abstractNote={Morphology control is one of the key strategies in optimizing the performance of organic photovoltaic materials, particularly for diketopyrrolopyrrole (DPP)‐based donor polymers. The design of DPP‐based polymers that provide high power conversion efficiency (PCE) presents a significant challenge that requires optimization of both energetics and morphology. Herein, a series of high performance, small band gap DPP‐based terpolymers are designed via two‐step side chain engineering, namely introducing alternating short and long alkyls for reducing the domain spacing and inserting alkylthio for modulating the energy levels. The new DPP‐based terpolymers are compared to delineate how the side chain impacts the mesoscale morphology. By employing the alkylthio‐substituted terpolymer PBDPP‐TS, the new polymer solar cell (PSC) device realizes a good balance of a high V oc of 0.77 V and a high J sc over 15 mA cm −2 , and thus realizes desirable PCE in excess of 8% and 9.5% in single junction and tandem PSC devices, respectively. The study indicates better control of domain purity will greatly improve performance of single junction DPP‐based PSCs toward 10% efficiency. More significantly, the utility of this stepwise side chain engineering can be readily expanded to other classes of well‐defined copolymers and triggers efficiency breakthroughs in novel terpolymers for photovoltaic and related electronic applications.}, number={3}, journal={ADVANCED ENERGY MATERIALS}, author={Ye, Long and Jiao, Xuechen and Zhang, Shaoqing and Yao, Huifeng and Qin, Yunpeng and Ade, Harald and Hou, Jianhui}, year={2017}, month={Feb} }
@article{li_ye_zhao_liu_zhu_ade_hou_2017, title={Design of a New Small‐Molecule Electron Acceptor Enables Efficient Polymer Solar Cells with High Fill Factor}, volume={29}, ISSN={0935-9648 1521-4095}, url={http://dx.doi.org/10.1002/ADMA.201704051}, DOI={10.1002/ADMA.201704051}, abstractNote={Abstract Improving the fill factor (FF) is known as a challenging issue in organic solar cells (OSCs). Herein, a strategy of extending the conjugated area of end‐group is proposed for the molecular design of acceptor–donor–acceptor (A–D–A)‐type small molecule acceptor (SMA), and an indaceno[1,2‐b:5,6‐b′]dithiophene‐based SMA, namely IDTN, by end‐capping with the naphthyl fused 2‐(3‐oxocyclopentylidene)malononitrile is synthesized. Benefiting from the π‐conjugation extension by fusing two phenyls, IDTN shows stronger molecular aggregation, more ordered packing structure, thus over one order of magnitude higher electron mobility relative to its counterpart. By utilizing the fluorinated polymer (PBDB‐TF) as the electron donor, the corresponding device exhibits a high efficiency of 12.2% with a record‐high FF of 0.78, which is approaching the theoretical limit of OSCs. Compared with the reference molecule, such a high FF in the IDTN system can be mainly attributed to the more ordered π–π packing of acceptor aggregates, higher domain purity and symmetric carrier transport in the blend. Hence, enlarging the conjugated area of the terminal‐group in these A–D–A‐type SMAs is a promising approach not only for enhancing the electron mobility, but also for improving the blend morphology, and both of them are conducive to the fill‐factor breakthrough.}, number={46}, journal={Advanced Materials}, publisher={Wiley}, author={Li, Sunsun and Ye, Long and Zhao, Wenchao and Liu, Xiaoyu and Zhu, Jie and Ade, Harald and Hou, Jianhui}, year={2017}, month={Oct}, pages={1704051} }
@article{bin_yang_peng_ye_yao_zhong_sun_gao_huang_li_et al._2017, title={Effect of Alkylsilyl Side-Chain Structure on Photovoltaic Properties of Conjugated Polymer Donors}, volume={8}, ISSN={1614-6832}, url={http://dx.doi.org/10.1002/AENM.201702324}, DOI={10.1002/AENM.201702324}, abstractNote={Abstract Side‐chain engineering is an important strategy for optimizing photovoltaic properties of organic photovoltaic materials. In this work, the effect of alkylsilyl side‐chain structure on the photovoltaic properties of medium bandgap conjugated polymer donors is studied by synthesizing four new polymers J70 , J72 , J73 , and J74 on the basis of highly efficient polymer donor J71 by changing alkyl substituents of the alkylsilyl side chains of the polymers. And the photovoltaic properties of the five polymers are studied by fabricating polymer solar cells (PSCs) with the polymers as donor and an n‐type organic semiconductor (n‐OS) m ‐ITIC as acceptor. It is found that the shorter and linear alkylsilyl side chain could afford ordered molecular packing, stronger absorption coefficient, higher charge carrier mobility, thus results in higher J sc and fill factor values in the corresponding PSCs. While the polymers with longer or branched alkyl substituents in the trialkylsilyl group show lower‐lying highest occupied molecular orbital energy levels which leads to higher V oc of the PSCs. The PSCs based on J70 : m ‐ITIC and J71 : m ‐ITIC achieve power conversion efficiency (PCE) of 11.62 and 12.05%, respectively, which are among the top values of the PSCs reported in the literatures so far.}, number={8}, journal={Advanced Energy Materials}, publisher={Wiley}, author={Bin, Haijun and Yang, Yankang and Peng, Zhengxing and Ye, Long and Yao, Jia and Zhong, Lian and Sun, Chenkai and Gao, Liang and Huang, He and Li, Xiaojun and et al.}, year={2017}, month={Dec}, pages={1702324} }
@article{zhao_ye_li_liu_zhang_zhang_ghasemi_he_ade_hou_et al._2017, title={Environmentally-friendly solvent processed fullerenefree organic solar cells enabled by screening halogen-free solvent additives}, volume={60}, ISSN={["2199-4501"]}, url={https://publons.com/wos-op/publon/5290953/}, DOI={10.1007/s40843-017-9080-x}, abstractNote={Though the power conversion efficiencies (PCEs) of organic solar cells (OSCs) have been boosted to 12%, the use of highly pollutive halogenated solvents as the processing solvent significantly hinders the mass production of OSCs. It is thus necessary to achieve high-efficiency OSCs by utilizing the halogen-free and environmentally-friendly solvents. Herein, we applied a halogen-free solvent system (oxylene/1-phenylnaphthalene, XY/PN) for fabricating fullerene-free OSCs, and a high PCE of 11.6% with a notable fill factor (FF) of 72% was achieved based on the PBDB-T:IT-M blend, which is among the top efficiencies of halogen-free solvent processed OSCs. In addition, the influence of different halogen-free solvent additives on the blend morphology and device performance metrics was studied by synchrotron-based tools and other complementary methods. Morphological results indicate the highly ordered molecular packing and highest average domain purity obtained in the blend films prepared by using XY/PN co-solvent are favorable for achieving increased FFs and thus higher PCEs in the devices. Moreover, a lower interaction parameter (χ) of the IT-M:PN pair provides a good explanation for the more favorable morphology and performance in devices with PN as the solvent additive, relative to those with diphenyl ether and N-methylpyrrolidone. Our study demonstrates that carefully screening the non-halogenated solvent additive plays a vital role in realizing the efficient and environmentally-friendly solvent processed OSCs.}, number={8}, journal={SCIENCE CHINA-MATERIALS}, author={Zhao, W. C. and Ye, Long and Li, S. S. and Liu, X. Y. and Zhang, S. Q. and Zhang, Y. and Ghasemi, M. and He, C. and Ade, H. and Hou, J. H. and et al.}, year={2017}, month={Aug}, pages={697–706} }
@article{ye_zhao_li_mukherjee_carpenter_awartani_jiao_hou_ade_2017, title={High-Efficiency Nonfullerene Organic Solar Cells: Critical Factors that Affect Complex Multi-Length Scale Morphology and Device Performance}, volume={7}, ISSN={["1614-6840"]}, url={https://publons.com/wos-op/publon/5290907/}, DOI={10.1002/aenm.201602000}, abstractNote={Organic solar cells (OSCs) made of donor/acceptor bulk‐heterojunction active layers have been of widespread interest in converting sunlight to electricity. Characterizing of the complex morphology at multiple length scales of polymer:nonfullerene small molecular acceptor (SMA) systems remains largely unexplored. Through detailed characterizations (hard/soft X‐ray scattering) of the record‐efficiency polymer:SMA system with a close analog, quantitative morphological parameters are related to the device performance parameters and fundamental morphology–performance relationships that explain why additive use and thermal annealing are needed for optimized performance are established. A linear correlation between the average purity variations at small length scale (≈10 nm) and photovoltaic device characteristics across all processing protocols is observed in ≈12%‐efficiency polymer:SMA systems. In addition, molecular interactions as reflected by the estimated Flory–Huggins interaction parameters are used to provide context of the room temperature morphology results. Comparison with results from annealed devices suggests that the two SMA systems compared show upper and lower critical solution temperature behavior, respectively. The in‐depth understanding of the complex multilength scale nonfullerene OSC morphology may guide the device optimization and new materials development and indicates that thermodynamic properties of materials systems should be studied in more detail to aid in designing optimized protocols efficiently.}, number={7}, journal={ADVANCED ENERGY MATERIALS}, author={Ye, Long and Zhao, Wenchao and Li, Sunsun and Mukherjee, Subhrangsu and Carpenter, Joshua H. and Awartani, Omar and Jiao, Xuechen and Hou, Jianhui and Ade, Harald}, year={2017}, month={Apr} }
@article{liu_ye_zhao_zhang_li_su_wang_ade_hou_2017, title={Morphology control enables thickness-insensitive efficient nonfullerene polymer solar cells}, volume={1}, ISSN={["2052-1537"]}, url={https://doi.org/10.1039/C7QM00182G}, DOI={10.1039/c7qm00182g}, abstractNote={Thermal annealing can be used to achieve thickness-insensitive non-fullerene polymer solar cells.}, number={10}, journal={MATERIALS CHEMISTRY FRONTIERS}, publisher={Royal Society of Chemistry (RSC)}, author={Liu, Xiaoyu and Ye, Long and Zhao, Wenchao and Zhang, Shaoqing and Li, Sunsun and Su, Gregory M. and Wang, Cheng and Ade, Harald and Hou, Jianhui}, year={2017}, month={Oct}, pages={2057–2064} }
@article{ghasemi_ye_zhang_yan_kim_awartani_you_gadisa_ade_2017, title={Panchromatic Sequentially Cast Ternary Polymer Solar Cells}, volume={29}, ISSN={0935-9648}, url={http://dx.doi.org/10.1002/ADMA.201604603}, DOI={10.1002/adma.201604603}, abstractNote={A sequential-casting ternary method is developed to create stratified bulk heterojunction (BHJ) solar cells, in which the two BHJ layers are spin cast sequentially without the need of adopting a middle electrode and orthogonal solvents. This method is found to be particularly useful for polymers that form a mechanically alloyed morphology due to the high degree of miscibility in the blend.}, number={4}, journal={Advanced Materials}, publisher={Wiley}, author={Ghasemi, Masoud and Ye, Long and Zhang, Qianqian and Yan, Liang and Kim, Joo-Hyun and Awartani, Omar and You, Wei and Gadisa, Abay and Ade, Harald}, year={2017}, month={Jan}, pages={1604603} }
@misc{zhang_ye_hou_2017, title={Precise Characterization of Performance Metrics of Organic Solar Cells}, volume={1}, ISSN={["2366-9608"]}, url={https://publons.com/wos-op/publon/7528288/}, DOI={10.1002/smtd.201700159}, abstractNote={Organic/carbon-based semiconductors and organometal halide perovskites such as CH3NH3PbIxCl3−x have been extensively pursued as potential active materials for cost-effective, solution-processable, and high-performance photovoltaic devices. Many research groups and researchers with different backgrounds are currently involved in this field, and the record power conversion efficiencies have increased dramatically in recent years. Accurately determining the figure of merit is essential to compare the absolute results and practical applications of these photovoltaic materials. Herein, the critical factors affecting the efficiency determination and some specific examples of solar cells employing representative organic photovoltaic materials with different bandgaps are summarized. Moreover, general methods and checklists for the efficiency determination of organic (tandem) solar cells and perovskite solar cells are presented. Future prospects in efficiency characterizations of the emerging solar cells are also discussed to aid researchers in developing a best practice.}, number={8}, journal={SMALL METHODS}, author={Zhang, Yun and Ye, Long and Hou, Jianhui}, year={2017}, month={Aug} }
@article{ye_xiong_li_ghasemi_balar_turner_gadisa_hou_o’connor_ade_et al._2017, title={Precise Manipulation of Multilength Scale Morphology and Its Influence on Eco-Friendly Printed All-Polymer Solar Cells}, volume={27}, ISSN={1616-301X}, url={http://dx.doi.org/10.1002/ADFM.201702016}, DOI={10.1002/adfm.201702016}, abstractNote={Significant efforts have lead to demonstrations of nonfullerene solar cells (NFSCs) with record power conversion efficiency up to ≈13% for polymer:small molecule blends and ≈9% for all‐polymer blends. However, the control of morphology in NFSCs based on polymer blends is very challenging and a key obstacle to pushing this technology to eventual commercialization. The relations between phases at various length scales and photovoltaic parameters of all‐polymer bulk‐heterojunctions remain poorly understood and seldom explored. Here, precise control over a multilength scale morphology and photovoltaic performance are demonstrated by simply altering the concentration of a green solvent additive used in blade‐coated films. Resonant soft X‐ray scattering is used to elucidate the multiphasic morphology of these printed all‐polymeric films and complements with the use of grazing incidence wide‐angle X‐ray scattering and in situ spectroscopic ellipsometry characterizations to correlate the morphology parameters at different length scales to the device performance metrics. Benefiting from the highest relative volume fraction of small domains, additive‐free solar cells show the best device performance, strengthening the advantage of single benign solvent approach. This study also highlights the importance of high volume fraction of smallest domains in printed NFSCs and organic solar cells in general.}, number={33}, journal={Advanced Functional Materials}, publisher={Wiley}, author={Ye, Long and Xiong, Yuan and Li, Sunsun and Ghasemi, Masoud and Balar, Nrup and Turner, Johnathan and Gadisa, Abay and Hou, Jianhui and O’Connor, Brendan T. and Ade, Harald and et al.}, year={2017}, month={Jul}, pages={1702016} }
@article{jiao_ye_ade_2017, title={Quantitative Morphology-Performance Correlations in Organic Solar Cells: Insights from Soft X-Ray Scattering}, volume={7}, ISSN={["1614-6840"]}, url={https://doi.org/10.1002/aenm.201700084}, DOI={10.1002/aenm.201700084}, abstractNote={Organic/polymer semiconductors provide unique possibilities and flexibility in tailoring their optoelectronic properties to match specific application demands. One of the key factors contributing to the rapid and continuous progress of organic photovoltaics (OPVs) is the control and optimization of photoactive‐layer morphology. The impact of morphology on photovoltaic parameters has been widely observed. However, the highly complex and multilength‐scale morphology often formed in efficient OPV devices consisting of compositionally similar components impose obstacles to conventional morphological characterizations. In contrast, due to the high compositional and orientational sensitivity, resonant soft X‐ray scattering (R‐SoXS), and related techniques lead to tremendous progress of characterization and comprehension regarding the complex mesoscale morphology in OPVs. R‐SoXS is capable of quantifying the domain characteristics, and polarized soft X‐ray scattering (P‐SoXS) provides quantitative information on orientational ordering. These morphological parameters strongly correlate the fill factor (FF), open‐circuit voltage ( V oc ), as well as short‐circuit current ( J sc ) in a wider range of OPV devices, including recent record‐efficiency polymer:fullerene solar cells and 12%‐efficiency fullerene‐free OPVs. This progress report will delineate the soft X‐ray scattering methodology and its future challenges to characterize and understand functional organic materials and provide a non‐exhaustive overview of R‐SoXS characterization and its implication to date.}, number={18}, journal={ADVANCED ENERGY MATERIALS}, publisher={Wiley}, author={Jiao, Xuechen and Ye, Long and Ade, Harald}, year={2017}, month={Sep} }
@article{balar_xiong_ye_li_nevola_dougherty_hou_ade_o’connor_2017, title={Role of Polymer Segregation on the Mechanical Behavior of All-Polymer Solar Cell Active Layers}, volume={9}, ISSN={1944-8244 1944-8252}, url={http://dx.doi.org/10.1021/ACSAMI.7B13719}, DOI={10.1021/ACSAMI.7B13719}, abstractNote={An all-polymer bulk heterojunction (BHJ) active layer that removes the use of commonly used small molecule electron acceptors is a promising approach to improve the thermomechanical behavior of organic solar cells. However, there has been limited research on their mechanical properties. Here, we report on the mechanical behavior of high-performance blade-coated all-polymer BHJ films cast using eco-friendly solvents. The mechanical properties considered include the elastic modulus, crack onset strain, and cohesive fracture energy. We show that the mechanical behavior of the blend is largely unaffected by significant changes in the segregation characteristics of the polymers, which was varied systematically through solvent formulation. In comparison to a polymer:fullerene BHJ counterpart, the all-polymer films were found to have lower stiffness and increased ductility. Yet, the fracture energy of the all-polymer films is not significantly improved compared to that of the polymer:fullerene films. This study highlights that improved mechanical behavior of all-polymer systems cannot be assumed, and that details of the molecular structure, molecular weight, and film morphology play an important role in both the optoelectronic and mechanical properties. Furthermore, we show that simple composite modeling provides a predictive tool for the mechanical properties of the polymer blend films, providing a framework to guide future optimization of the mechanical behavior.}, number={50}, journal={ACS Applied Materials & Interfaces}, publisher={American Chemical Society (ACS)}, author={Balar, Nrup and Xiong, Yuan and Ye, Long and Li, Sunsun and Nevola, Daniel and Dougherty, Daniel B. and Hou, Jianhui and Ade, Harald and O’Connor, Brendan T.}, year={2017}, month={Dec}, pages={43886–43892} }
@article{li_ye_zhao_zhang_ade_hou_2017, title={Significant Influence of the Methoxyl Substitution Position on Optoelectronic Properties and Molecular Packing of Small-Molecule Electron Acceptors for Photovoltaic Cells}, volume={7}, ISSN={["1614-6840"]}, url={https://publons.com/wos-op/publon/5290958/}, DOI={10.1002/aenm.201700183}, abstractNote={Molecular engineering of nonfullerene electron acceptors is of great importance for the development of organic photovoltaics. In this study, a series of methoxyl‐modified dithieno[2,3‐d:2′,3′‐d′]‐ s ‐indaceno[1,2‐b:5,6‐b′]dithiophene‐based small‐molecule acceptor (SMA) isomers are synthesized and characterized to determine the effect of substitution position of the terminal group in these acceptor–donor–acceptor‐type SMAs. Minor changes in the substitution position are demonstrated to greatly influence the optoelectronic properties and molecular packing of the isomers. Note that SMAs with planar molecular backbones show more ordered molecular packing and smaller π–π stacking distances, thus dramatically higher electron mobilities relative to their counterparts with distorted end‐groups. By utilizing polymer poly[(2,6‐(4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)benzo[1,2‐b:4,5‐b′]dithiophen)‐ co ‐(1,3‐di(5‐thiophene‐2‐yl)‐5,7‐bis(2‐ethylhexyl)benzo[1,2‐c:4,5‐c′]dithiophene‐4,8‐dione)] (PBDB‐T) as an electron donor, an optimum power conversion efficiency (PCE) of 11.9% is achieved in the device based on PBDB‐T:IT‐OM‐2, which is among the top efficiencies reported as of yet. Moreover, the PCE stays above 10% as the film thickness increases to 250 nm, which is very advantageous for large‐area printing. Overall, the intrinsic molecular properties as well as the morphologies of blends can be effectively modulated by manipulating the substituent position on the terminal groups, and the structure–property relationships gleaned from this study will aid in designing more efficient SMAs for versatile applications.}, number={17}, journal={ADVANCED ENERGY MATERIALS}, author={Li, Sunsun and Ye, Long and Zhao, Wenchao and Zhang, Shaoqing and Ade, Harald and Hou, Jianhui}, year={2017}, month={Sep} }
@article{zhang_ye_hou_2016, title={Breaking the 10% Efficiency Barrier in Organic Photovoltaics: Morphology and Device Optimization of Well-Known PBDTTT Polymers}, volume={6}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000379311500008&KeyUID=WOS:000379311500008}, DOI={10.1002/aenm.201502529}, abstractNote={With the advances in organic photovoltaics (OPVs), the invention of model polymers with superior properties and wide applicability is of vital importance to both the academic and industrial communities. The recent inspiring advances in OPV research have included the emergence of poly(benzodithiophene‐co‐thieno[3,4‐b]thiophene) (PBDTTT)‐based materials. Through the combined efforts on PBDTTT polymers, over 10% efficiencies have been realized recently in various types of OPV devices. This review attempts to critically summarize the recent advances with respect to five well‐known PBDTTT polymers and their design considerations, basic properties, photovoltaic performance, as well as device application in conventional, inverted, tandem solar cells. These PBDTTT polymers also make great contributions to the rapid advances in the field of emerging ternary blends and fullerene‐free OPVs with top performances. Addtionally, new challenges in developing novel photovoltaic polymers with more superior properties are prospected. More importantly, the research of highly efficient PBDTTT‐based polymers provides useful insights and builds fundamentals for new types of OPV applications with various architectures.}, number={11}, journal={Advanced Energy Materials}, author={Zhang, Shaoqing and Ye, Long and Hou, Jianhui}, year={2016} }
@book{ye_li_hou_2016, title={CHAPTER 2: New polymer donors for polymer solar cells}, volume={2016-January}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84952360276&partnerID=MN8TOARS}, DOI={10.1039/9781782622307-00032}, abstractNote={Conjugated polymers have been regarded as promising candidates in organic photovoltaics owing to the outstanding electronic, optical and mechanical flexible properties. In this chapter, first, we summarize and discuss the requirements and design strategies of donor polymers in polymer solar cells (PSCs). Second, the design concepts and representative donor–acceptor (D–A) copolymer donors based on six types of donor building blocks are discussed. Notably, the blooming developments of novel two-dimensional conjugated polymer donors are emphasized. Third, the design considerations and examples of novel terpolymer donors are introduced. Finally, we summarize the future directions and approaches to developing higher performance donor polymers for photovoltaic applications.}, number={17}, journal={RSC Polymer Chemistry Series}, author={Ye, L. and Li, S. and Hou, J.}, year={2016}, pages={32–77} }
@article{yao_zhang_ye_zhao_zhang_hou_2016, title={Dialkylthio Substitution: An Effective Method to Modulate the Molecular Energy Levels of 2D-BDT Photovoltaic Polymers}, volume={8}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84959017081&partnerID=MN8TOARS}, DOI={10.1021/acsami.5b07311}, abstractNote={Dialkylthio-substituted thienyl-benzodithiophene (BDT-DST) was designed and synthesized as a building block to modulate the molecular levels of the conjugated polymers, and three copolymers named PDST-BDD, PDST-TT and PDST-DPP were prepared and applied in polymer solar cells (PSCs). Theoretical calculations and electrochemical cyclic voltammetry (CV) measurement suggested that the dialkylthio group could decrease the molecular energy levels of the resulting polymers distinctly. The open-circuit voltage (VOC) of PSC devices based on PDST-BDD, PDST-TT, and PDST-DPP are as high as 1.0, 0.98, and 0.88 V, respectively, which are ∼0.15 V higher than those of the corresponding alky-substituted analogues. Moreover, the influence of the dialkylthio group on the absorption spectra, crystalline properties, hole mobilities, and blend morphologies of the polymers was also investigated. The results indicate that the dialkythio substitution is an effective method to modulate the molecular energy levels and that the BDT-DST unit has potential for constructing high-efficiency photovoltaic polymers.}, number={6}, journal={ACS Applied Materials and Interfaces}, author={Yao, H. and Zhang, H. and Ye, L. and Zhao, W. and Zhang, S. and Hou, J.}, year={2016}, pages={3575–3583} }
@article{wang_zhang_xu_ye_yao_cui_zhang_yuan_hou_2016, title={Effectively Improving Extinction Coefficient of Benzodithiophene and Benzodithiophenedione-based Photovoltaic Polymer by Grafting Alkylthio Functional Groups}, volume={11}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000387464000006&KeyUID=WOS:000387464000006}, DOI={10.1002/asia.201501387}, abstractNote={Alkylthio groups have received much attention in the polymer community for their molecular design applications in polymer solar cells. In this work, alkylthio substitution on the conjugated thiophene side chains in benzodithiophene (BDT) and benzodithiophenedione (BDD)-based photovoltaic polymer was used to improve the extinction coefficient. The introduction of alkylthio groups into the polymer increased its extinction coefficient while the HOMO levels, bandgaps, and absorption bands remained the same. Thus, the short circuit current density (Jsc ) and the efficiency of the device were much better than those of the control device. Thus, introducing the alkylthio functional group in polymer is an effective method to tune the extinction coefficient of photovoltaic polymer. This provides a new path to improve photovoltaic performance without increasing active layer thickness, which will be very helpful to design advanced photovoltaic materials for high photovoltaic performance.}, number={19}, journal={Chemistry-an Asian Journal}, author={Wang, Qi and Zhang, Shaoqing and Xu, Bowei and Ye, Long and Yao, Huifeng and Cui, Yong and Zhang, Hao and Yuan, Wenxia and Hou, Jianhui}, year={2016}, pages={2650–2655} }
@article{li_ye_zhao_zhang_mukherjee_ade_hou_2016, title={Energy-Level Modulation of Small-Molecule Electron Acceptors to Achieve over 12% Efficiency in Polymer Solar Cells}, volume={28}, ISSN={["1521-4095"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=MEDLINE&KeyUT=MEDLINE:27606970&KeyUID=MEDLINE:27606970}, DOI={10.1002/adma.201602776}, abstractNote={Fine energy-level modulations of small-molecule acceptors (SMAs) are realized via subtle chemical modifications on strong electron-withdrawing end-groups. The two new SMAs (IT-M and IT-DM) end-capped by methyl-modified dicycanovinylindan-1-one exhibit upshifted lowest unoccupied molecular orbital (LUMO) levels, and hence higher open-circuit voltages can be observed in the corresponding devices. Finally, a top power conversion efficiency of 12.05% is achieved.}, number={42}, journal={ADVANCED MATERIALS}, author={Li, Sunsun and Ye, Long and Zhao, Wenchao and Zhang, Shaoqing and Mukherjee, Subhrangsu and Ade, Harald and Hou, Jianhui}, year={2016}, month={Nov}, pages={9423-+} }
@article{li_zhang_zhao_ye_yao_yang_zhang_hou_2016, title={Green-Solvent-Processed All-Polymer Solar Cells Containing a Perylene Diimide-Based Acceptor with an Efficiency over 6.5%}, volume={6}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000372525500009&KeyUID=WOS:000372525500009}, DOI={10.1002/aenm.201501991}, abstractNote={To realize high power conversion efficiencies (PCEs) in green‐solvent‐processed all‐polymer solar cells (All‐PSCs), a long alkyl chain modified perylene diimide (PDI)‐based polymer acceptor PPDIODT with superior solubility in nonhalogenated solvents is synthesized. A properly matched PBDT‐TS1 is selected as the polymer donor due to the red‐shifted light absorption and low‐lying energy level in order to achieve the complementary absorption spectrum and matched energy level between polymer donor and polymer acceptor. By utilizing anisole as the processing solvent, an optimal efficiency of 5.43% is realized in PBDT‐TS1/PPDIODT‐based All‐PSC with conventional configuration, which is comparable with that of All‐PSCs processed by the widely used binary solvent. Due to the utilization of an inverted device configuration, the PCE is further increased to over 6.5% efficiency. Notably, the best‐performing PCE of 6.58% is the highest value for All‐PSCs employing PDI‐based polymer acceptors and green‐solvent‐processed All‐PSCs. The excellent photovoltaic performance is mainly attributed to a favorable vertical phase distribution, a higher exciton dissociation efficiency ( P diss ) in the blend film, and a higher electrode carrier collection efficiency. Overall, the combination of rational molecular designing, material selection, and device engineering will motivate the efficiency breakthrough in green‐solvent‐processed All‐PSCs.}, number={5}, journal={Advanced Energy Materials}, author={Li, Sunsun and Zhang, Hao and Zhao, Wenchao and Ye, Long and Yao, Huifeng and Yang, Bei and Zhang, Shaoqing and Hou, Jianhui}, year={2016} }
@article{zhang_ye_zhang_hou_2016, title={Green-solvent-processable organic solar cells}, volume={19}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84961223535&partnerID=MN8TOARS}, DOI={10.1016/j.mattod.2016.02.019}, abstractNote={Solution-processable organic photovoltaics (OPV) has emerged as a promising clean energy-generating technology due to its potential for low-cost manufacturing with a high power/weight ratio. The state-of-the-art OPV devices are processed by hazardous halogenated solvents. Fabricating high-efficiency OPV devices using greener solvents is a necessary step toward their eventual commercialization. In this review, recent research efforts and advances in green-solvent-processable OPVs are summarized, and two basic strategies including material design and solvent selection of light-harvesting layers are discussed. In particular, the most recent green-solvent-processable OPVs with high efficiencies in excess of 9% are highlighted.}, number={9}, journal={Materials Today}, author={Zhang, S. and Ye, L. and Zhang, H. and Hou, J.}, year={2016}, pages={533–543} }
@article{ye_xiong_yao_dinku_zhang_li_ghasemi_balar_hunt_o'connor_et al._2016, title={High Performance Organic Solar Cells Processed by Blade Coating in Air from a Benign Food Additive Solution}, volume={28}, ISSN={0897-4756 1520-5002}, url={http://dx.doi.org/10.1021/ACS.CHEMMATER.6B03083}, DOI={10.1021/acs.chemmater.6b03083}, abstractNote={Solution processable conjugated organic materials have gained tremendous interest motivated by their potential of low cost, lightweight and especially easy manufacturing of large-area and flexible electronics. Toxic halogen-containing solvents have been widely used in the processing of organic electronics, particularly organic photovoltaics (OPVs). To transition this technology to more commercially attractive manufacturing approaches, removing these halogenated solvents remains one of the key challenges. Our morphological (hard/soft X-ray scattering) and calorimetric characterizations reveal that using o-methylanisole, a certified food additive, as processing solvent can achieve similar crystalline properties and domain spacing/purity with that achieved by widely used binary halogenated solvents (chlorobenzene and 1,8-diiodooctane), thus yielding comparable photovoltaic performance in spin-casted films. To move a step forward, we further present the potential of o-methylanisole as processing solvent in the blade-coating of several cases of OPVs in air. Remarkably, this single nonhazardous solvent yields ∼8.4% and ∼5.2% efficiency in OPVs by respectively blade-coating PBDT-TSR:PC71BM and all-polymeric PBDT-TS1:PPDIODT in ambient air, which are among the highest values for the respective kind of device. We postulate this simple nonhazardous solvent approach will also be applicable in the large area roll-to-roll coating and industrial scale printing of high-efficiency OPVs in air.}, number={20}, journal={Chemistry of Materials}, publisher={Link}, author={Ye, L. and Xiong, Y. and Yao, H. and Dinku, A.G. and Zhang, H. and Li, S. and Ghasemi, M. and Balar, N. and Hunt, A. and O'Connor, B.T. and et al.}, year={2016}, pages={7451–7458} }
@article{zhang_yao_zhao_ye_hou_2016, title={High-Efficiency Polymer Solar Cells Enabled by Environment-Friendly Single-Solvent Processing}, volume={6}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000373149700016&KeyUID=WOS:000373149700016}, DOI={10.1002/aenm.201502177}, abstractNote={Green-single-solvent-prepared polymer solar cells (PSCs) with efficiency of 9.7% based on PBDT-TS1:PC71BM are realized without resorting to any additives or further treatments. An environment-friendly solvent 2-methylanisole is proposed to fabricate PSCs for the first time. It reveals the possibility of replacing binary systems with a single solvent to fabricate highly efficient PSCs. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.}, number={6}, journal={Advanced Energy Materials}, author={Zhang, Hao and Yao, Huifeng and Zhao, Wenchao and Ye, Long and Hou, Jianhui}, year={2016} }
@article{li_ye_wang_zhang_zhao_hou_2016, title={Improving the open-circuit voltage of alkylthio-substituted photovoltaic polymers via post-oxidation}, volume={28}, url={https://doi.org/10.1016/j.orgel.2015.10.004}, DOI={10.1016/j.orgel.2015.10.004}, abstractNote={Molecular designing of photovoltaic polymers based on benzodithiophene (BDT) building blocks for high power conversion efficiency (PCE) in polymer solar cells (PSCs) arouse much attention in the past few years. To meliorate the energy levels of photovoltaic polymers featuring alkylthio substituted BDT units, a novel post-polymerization oxidation method was proposed applied in converting sulfur atom into sulfonyl group on side chains of the pristine polymer PBT-S. After treating with tiny amount of meta-chloroperoxybenzoic acid (m-CPBA) and hydrogen peroxide (H2O2), two batches of the target polymers, namely, PBT-SO2-M and PBT-SO2-H were prepared for the first time, respectively. The photochemical and electrochemical results indicate that both the HOMO levels are distinctly dropped with almost no influence on band gaps by introducing strong electron-withdrawing sulfonyl groups on side chains of BDT. Accordingly, the photovoltaic results reveal that the Voc of devices based on PBT-SO2-M and PBT-SO2-H are 0.81, 0.71 V which are 0.17 and 0.07 V higher than that of pristine polymer PBT-S, respectively. Moreover, the Jsc and PCE of PBT-SO2-H devices are comparable with those of the devices based on PBT-S. Overall, this work suggests that the molecular energy levels of D–A copolymers can be effectively tuned by a post-oxidation method.}, journal={Organic Electronics}, publisher={Elsevier BV}, author={Li, Sunsun and Ye, Long and Wang, Qi and Zhang, Shaoqing and Zhao, Wenchao and Hou, Jianhui}, year={2016}, month={Jan}, pages={39–46} }
@article{ye_jiao_zhao_zhang_yao_li_ade_hou_2016, title={Manipulation of Domain Purity and Orientational Ordering in High Performance All-Polymer Solar Cells}, volume={28}, ISSN={["1520-5002"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000383318500021&KeyUID=WOS:000383318500021}, DOI={10.1021/acs.chemmater.6b02222}, abstractNote={All-polymer solar cells (All-PSCs) are of great interest as a renewable and economically viable energy technology, which has shown potential advantages in practical photovoltaic applications due to the highly tunable optical, electronic, and mechanical properties. A quantitative understanding of the domain composition variations and orientational ordering of all-polymeric films affected by solvent additives had been unattainable until now. This study demonstrates how the use of trace amount solvent additive can indeed manipulate domain purity and molecular orientational ordering as revealed by polarized soft X-ray scattering (P-SoXS). Additionally, the BDDT/PNDI all-polymeric blend exhibits enhanced average domain purity with the use of a trace amount of solvent additive and thus improved charge mobility, device fill factor and power conversion efficiency. A high power conversion efficiency of ∼7.1% was obtained in the All-PSC mainly contributed by this morphology control strategy. Manipulation of domain purity and orientation ordering, both of which are impacted by the aggregation kinetics, may be a key to further boost the efficiency of new fullerene-free solar cells and all-anisotropic materials-based devices.}, number={17}, journal={CHEMISTRY OF MATERIALS}, author={Ye, Long and Jiao, Xuechen and Zhao, Wenchao and Zhang, Shaoqing and Yao, Huifeng and Li, Sunsun and Ade, Harald and Hou, Jianhui}, year={2016}, month={Sep}, pages={6178–6185} }
@article{yao_ye_zhang_li_zhang_hou_2016, title={Molecular Design of Benzodithiophene-Based Organic Photovoltaic Materials.}, volume={116}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=MEDLINE&KeyUT=MEDLINE:27251307&KeyUID=MEDLINE:27251307}, DOI={10.1021/acs.chemrev.6b00176}, abstractNote={Advances in the design and application of highly efficient conjugated polymers and small molecules over the past years have enabled the rapid progress in the development of organic photovoltaic (OPV) technology as a promising alternative to conventional solar cells. Among the numerous OPV materials, benzodithiophene (BDT)-based polymers and small molecules have come to the fore in achieving outstanding power conversion efficiency (PCE) and breaking 10% efficiency barrier in the single junction OPV devices. Remarkably, the OPV device featured by BDT-based polymer has recently demonstrated an impressive PCE of 11.21%, indicating the great potential of this class of materials in commercial photovoltaic applications. In this review, we offered an overview of the organic photovoltaic materials based on BDT from the aspects of backbones, functional groups, alkyl chains, and device performance, trying to provide a guideline about the structure-performance relationship. We believe more exciting BDT-based photovoltaic materials and devices will be developed in the near future.}, number={12}, journal={Chemical reviews}, author={Yao, Huifeng and Ye, Long and Zhang, Hao and Li, Sunsun and Zhang, Shaoqing and Hou, Jianhui}, year={2016}, pages={7397–457} }
@article{new polymer donors for polymer solar cells_2016, url={https://publons.com/wos-op/publon/7528283/}, journal={POLYMER PHOTOVOLTAICS: MATERIALS, PHYSICS, AND DEVICE ENGINEERING}, year={2016} }
@article{ye_jiao_zhang_li_yao_ade_hou_2015, title={2D-Conjugated Benzodithiophene-Based Polymer Acceptor: Design, Synthesis, Nanomorphology, and Photovoltaic Performance}, volume={48}, ISSN={["1520-5835"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000362921500041&KeyUID=WOS:000362921500041}, DOI={10.1021/acs.macromol.5b01537}, abstractNote={All polymer photovoltaic cells offer unique potentials owing to the chemical and electronic tunability of both polymer donors and polymer acceptors. Compared with the numerous π-conjugated polymer donors, choices of π-conjugated polymer acceptors are limited for photovoltaic applications. Although 2D-conjugated benzo[1,2-b:4,5-b′]dithiophene (BDT) units are widely used as building blocks in highly efficient donor polymers in recent years, polymer acceptors based on these units have not been reported yet. Herein, a novel 2D-conjugated polymer acceptor (PBDTNDI-T) based on naphthalene diimide (NDI) and alkylthiothiophene-substituted BDT was designed, synthesized, and in-depth characterized. The polymers’ photophysical, electrical, crystallinity, and morphological properties are addressed in homopolymer and blend films and well correlated with device performance. Under the weight ratio of 1.5:1 and 3 vol % of 1-chloronaphthalene, the PBDTNDI-T-based all polymer photovoltaic device exhibited a desirable PCE of nearly 3%, which is ascribed to the relatively high domain purity and small domain characteristic length observed by resonant soft X-ray scattering (R-SoXS) characterizations. These results demonstrated PBDTNDI-T is a novel polymer acceptor and also promising candidate material for efficient energy-related applications.}, number={19}, journal={MACROMOLECULES}, author={Ye, Long and Jiao, Xuechen and Zhang, Hao and Li, Sunsun and Yao, Huifeng and Ade, Harald and Hou, Jianhui}, year={2015}, month={Oct}, pages={7156–7163} }
@article{zhao_ye_zhang_sun_hou_2015, title={A universal halogen-free solvent system for highly efficient polymer solar cells}, volume={3}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000356022800019&KeyUID=WOS:000356022800019}, DOI={10.1039/c4ta07029a}, abstractNote={A high power conversion efficiency over 9.4% was realized in polymer solar cells by halogen-free solvent processing.}, number={24}, journal={Journal of Materials Chemistry a}, author={Zhao, Wenchao and Ye, Long and Zhang, Shaoqing and Sun, Mingliang and Hou, Jianhui}, year={2015}, pages={12723–12729} }
@article{zhao_ye_zhang_yao_sun_hou_2015, title={An Easily Accessible Cathode Buffer Layer for Achieving Multiple High Performance Polymer Photovoltaic Cells}, volume={119}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000366339000017&KeyUID=WOS:000366339000017}, DOI={10.1021/acs.jpcc.5b09575}, abstractNote={Here we report a successful efficiency improvement strategy in both conventional and inverted polymer solar cells (PSCs) based on multiple polymer blends, using a feasible and commercially available cathode buffer layer (CBL), namely barium hydroxide [Ba(OH)2], to modify the photoactive blend and cathode contacts. High performance PSCs with an identical Ba(OH)2 buffer layer were fabricated based on the multiple light-harvesting PBDT-TS1:PC71BM, PffBT4T-2OD:PC71BM, and PBDT-TS1:N2200 blends. The conventional PSC with Ba(OH)2 as the CBL showed a higher power conversion efficiency (PCE) of 9.65% based on the PBDT-TS1:PC71BM system under the illumination of 100 mW/cm2. For the inverted cells based on the PffBT4T-2OD:PC71BM system, the PCE can be improved from 4.26% (without CBL) to 9.02% after inserting the Ba(OH)2 buffer layer. More importantly, the Ba(OH)2 buffer layer presents similar positive effects in the conventional and inverted all-polymer devices based on a new combination, i.e., the PBDT-TS1:N2200 system. The dramatic enhancement in device performance resulted from the suitable work function of Ba(OH)2, extremely high transmittance, and excellent film-forming capability. Therefore, inserting Ba(OH)2 as the CBL is a simple, low-cost, and widely applicable method to simultaneously improve the conventional and inverted photovoltaic device performance.}, number={49}, journal={Journal of Physical Chemistry C}, author={Zhao, Wenchao and Ye, Long and Zhang, Shaoqing and Yao, Huifeng and Sun, Mingliang and Hou, Jianhui}, year={2015}, pages={27322–27329} }
@inbook{ye_hou_li_2015, title={Conjugated Polymer Photovoltaic Materials}, volume={91}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000365084800006&KeyUID=WOS:000365084800006}, DOI={10.1007/978-3-319-16862-3_5}, abstractNote={During the past few decades, conjugated polymers with various molecular structures have been explored for applications in polymer solar cells (PSCs). In this chapter, an overview of conjugated polymer photovoltaic materials is given to provide insights for molecular design and fine-tuning of high-performance photovoltaic polymers. First, we briefly summarize and provide design considerations of conjugated polymer photovoltaic materials. Second, representative photovoltaic polymers are introduced. Third, representative conjugated polymer acceptor materials are briefly introduced and discussed.}, booktitle={Organic Optoelectronic Materials}, author={Ye, Long and Hou, Jianhui and Li, Y}, year={2015}, pages={195–239} }
@article{ye_sun_jiang_zhang_zhao_yao_wang_hou_2015, title={Enhanced Efficiency in Fullerene-Free Polymer Solar Cell by Incorporating Fine-designed Donor and Acceptor Materials}, volume={7}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000354338800039&KeyUID=WOS:000354338800039}, DOI={10.1021/acsami.5b02012}, abstractNote={Among the diverse nonfullerene acceptors, perylene bisimides (PBIs) have been attracting much attention due to their excellent electron mobility and tunable molecular and electronic properties by simply engineering the bay and head linkages. Herein, guided by two efficient small molecular acceptors, we designed, synthesized, and characterized a new nonfullerene small molecule PPDI with fine-tailored alkyl chains. Notably, a certificated PCE of 5.40% is realized in a simple structured fullerene-free polymer solar cell comprising PPDI as the electron acceptor and a fine-tailored 2D-conjugated polymer PBDT-TS1 as the electron donor. Moreover, the device behavior, morphological feature, and origin of high efficiency in PBDT-TS1/PPDI-based fullerene-free PSC were investigated. The synchronous selection and design of donor and acceptor materials reported here offer a feasible strategy for realizing highly efficient fullerene-free organic photovoltaics.}, number={17}, journal={Acs Applied Materials & Interfaces}, author={Ye, Long and Sun, Kai and Jiang, Wei and Zhang, Shaoqing and Zhao, Wenchao and Yao, Huifeng and Wang, Zhaohui and Hou, Jianhui}, year={2015}, pages={9274–9280} }
@article{zhao_ye_zhao_zhang_yao_xu_sun_hou_2015, title={Enhanced efficiency of polymer photovoltaic cells via the incorporation of a water-soluble naphthalene diimide derivative as a cathode interlayer}, volume={3}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000367310200001&KeyUID=WOS:000367310200001}, DOI={10.1039/c5tc02172c}, abstractNote={A novel water-soluble naphthalene diimide derivative was utilized as a cathode interlayer for two types of high performance polymer photovoltaic cells.}, number={37}, journal={Journal of Materials Chemistry C}, author={Zhao, Kang and Ye, Long and Zhao, Wenchao and Zhang, Shaoqing and Yao, Huifeng and Xu, Bowei and Sun, Mingliang and Hou, Jianhui}, year={2015}, pages={9565–9571} }
@article{liu_zhao_zhang_ye_zheng_cui_chen_hou_2015, title={Highly Efficient Photovoltaic Polymers Based on Benzodithiophene and Quinoxaline with Deeper HOMO Levels}, volume={48}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000359500100013&KeyUID=WOS:000359500100013}, DOI={10.1021/acs.macromol.5b00829}, abstractNote={We present the synthesis and photovoltaic application of four conjugated polymers composed of benzo[1,2-b:4,5-b′]dithiophene (BDT)-based and 2,3-diphenyl-5,8-di(thiophen-2-yl)quinoxaline (DTQx)-based units. Fluorination of the DTQx units and the conjugated side groups of the BDT unit shows synergistic effect on molecular energy level modulation of the polymers, and as a result, the polymer PBQ-4 exhibits the deepest HOMO and LUMO levels in these four polymers. The characterizations of the photovoltaic properties of the polymer solar cells (PSCs) based on these four polymers reveal that the fluorination has little influence on short-circuit current density (JSC) and fill factor (FF) but is very helpful to enhance open-circuit voltage (VOC) of the devices. Benefiting from the synergistic effect of the fluorination, the device based on PBQ-4 shows a high VOC of 0.90 V, which is 0.26 V higher than the polymer without fluorine and ca. 0.10 V higher than the other two polymers with less fluorine. As a result, a power conversion efficiency (PCE) of 8.55% was recorded in the PBQ-4 based device, which is much higher than those of the other three polymers and also the highest one for the BDT-Qx-based polymers.}, number={15}, journal={Macromolecules}, author={Liu, Delong and Zhao, Wenchao and Zhang, Shaoqing and Ye, Long and Zheng, Zhong and Cui, Yong and Chen, Yu and Hou, Jianhui}, year={2015}, pages={5172–5178} }
@article{zheng_zhang_zhang_zhao_ye_chen_yang_hou_2015, title={Highly Efficient Tandem Polymer Solar Cells with a Photovoltaic Response in the Visible Light Range}, volume={27}, url={https://publons.com/wos-op/publon/5290889/}, DOI={10.1002/ADMA.201404525}, abstractNote={Highly efficient polymer solar cells with a tandem structure are fabricated by using two excellent photovoltaic polymers and a highly transparent intermediate recombination layer. Power conversion -efficiencies over 10% can be realized with a photovoltaic response within 800 nm.}, number={7}, journal={Advanced Materials}, author={Zheng, Zhong and Zhang, Shaoqing and Zhang, Maojie and Zhao, Kang and Ye, Long and Chen, Yu and Yang, Bei and Hou, Jianhui}, year={2015}, pages={1189–94} }
@article{yao_ye_fan_huo_hou_2015, title={Influence of the alkyl substitution position on photovoltaic properties of 2D-BDT-based conjugated polymers}, volume={58}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000364477200006&KeyUID=WOS:000364477200006}, DOI={10.1007/s40843-015-0036-3}, abstractNote={Three conjugated polymers based on thienyl-substituted benzodithiophene (BDT) and 4,7-bis-thienyl-benzothiadiazole (DTBT) with varied substitution positions of the alkyl side chains were synthesized to investigate the correlations between the structure and photovoltaic performance of the polymer photovoltaic materials. The three polymers named PBDTDTBT-p, PBDTDTBT-o and PBDTDTBT-m were characterized by a set of methods including absorption spectroscopy, cyclic voltammetry, thermogravimetric analysis, X-ray diffraction, density functional theory and photovoltaic measurements. The results show that the steric hindrance caused by the different substitution positions of the alky chains has a significant influence on the photovoltaic properties of the polymers. The open-circuit voltage (V oc) of the photovoltaic devices based on the three polymers could range from 0.67 to 0.90 V. Clearly, this finding provides us a feasible strategy to optimize the photovoltaic properties by simply changing the positions of the alkyl chains.}, number={3}, journal={Science China-Materials}, author={Yao, Huifeng and Ye, Long and Fan, Benhu and Huo, Lijun and Hou, Jianhui}, year={2015}, pages={213–222} }
@article{ye_jiao_zhou_zhang_yao_zhao_xia_ade_hou_2015, title={Manipulating Aggregation and Molecular Orientation in All-Polymer Photovoltaic Cells}, volume={27}, ISSN={["1521-4095"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=MEDLINE&KeyUT=MEDLINE:26315155&KeyUID=MEDLINE:26315155}, DOI={10.1002/adma.201503218}, abstractNote={Manipulating molecular orientation at the donor/acceptor interface is the key to boosting charge separation properties and efficiencies of anisotropic-materials-based organic photovoltaics (OPVs). By replacing the polymeric donor PBDTBDD with its 2D-conjugated polymer PBDTBDD-T, the power conversion efficiency of OPVs featuring the anisotropic polymer acceptor PNDI is drastically boosted from 2.4% up to 5.8%.}, number={39}, journal={ADVANCED MATERIALS}, author={Ye, Long and Jiao, Xuechen and Zhou, Meng and Zhang, Shaoqing and Yao, Huifeng and Zhao, Wenchao and Xia, Andong and Ade, Harald and Hou, Jianhui}, year={2015}, month={Oct}, pages={6046–6054} }
@article{yao_zhang_ye_zhao_zhang_hou_2015, title={Molecular Design and Application of a Photovoltaic Polymer with Improved Optical Properties and Molecular Energy Levels}, volume={48}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000356201100011&KeyUID=WOS:000356201100011}, DOI={10.1021/acs.macromol.5b00649}, abstractNote={(E)-5-(2-(5-(Alkylthio)thiophen-2-yl)vinyl)thiophene-2-yl functional groups were introduced onto 4- and 8-positions of BDT units, and this building block was used to construct a new derivative polymer of PTB7, named as PBT-TVT. Benefiting from the prolonged conjugation of the conjugated side groups on BDT units, the optical absorption property of PBT-TVT can be improved greatly compared to that of PTB7, so an inspiring result of 7.67% was obtained by using PBT-TVT as the donor and PC61BM as the acceptor in polymer solar cells (PSCs), which is much higher than that of the PTB7:PC61BM-based device and also one of the highest results for PSCs with PC61BM. In electrochemical cyclic voltammetry (CV) measurements, PBT-TVT showed a deeper HOMO level than PTB7 so the device based on the former exhibits higher open circuit voltage than the latter. Moreover, in comparison with PTB7, the new polymer PBT-TVT exhibited stronger interchain π–π interaction and thus higher hole mobility. Overall, the results in this work indicated that PBT-TVT is a promising donor polymer, and the strategy used in this work will be beneficial for molecular design of polymer photovoltaic materials for large-scale production of PSCs.}, number={11}, journal={Macromolecules}, author={Yao, Huifeng and Zhang, Hao and Ye, Long and Zhao, Wenchao and Zhang, Shaoqing and Hou, Jianhui}, year={2015}, pages={3493–3499} }
@article{zhang_ye_hou_2015, title={Molecular design strategies for voltage modulation in highly efficient polymer solar cells}, volume={64}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000357334600003&KeyUID=WOS:000357334600003}, DOI={10.1002/pi.4895}, abstractNote={Abstract Open‐circuit voltage ( V oc ) is one of the key parameters in determining the photovoltaic performance of polymer solar cells ( PSCs ). Although significant advances in materials and device physics of PSCs have been achieved in the past decade, the low V oc values still hamper the enhancement of power conversion efficiencies ( PCEs ) of PSCs based on the widely known polymers like polythiophenes ( PTs ) and poly(benzo[1,2‐b:4,5‐b′]dithiophene‐ co ‐thieno[3,4‐b]thiophene) ( PBDTTT ) polymers. In order to pursue high PCE , more efforts should be directed towards improving V oc through molecular design of conjugated polymers, i.e. to reduce the highest occupied molecular orbital levels without sacrificing optical absorption properties. In this mini‐review, some feasible and effective strategies, such as inserting conjugated side groups with various electron‐withdrawing effects, manipulating alkyl chains and introducing functional substituents, to improve V oc of PSCs based on some highly efficient photovoltaic polymers, especially PTs and PBDTTT polymers, are summarized and discussed. Owing to these strategies, PCEs of PSCs based on PTs and PBDTTT polymers can be further boosted to ca 7% and ca 10%, respectively. Apparently, these strategies offer opportunities for achieving new breakthroughs in other π ‐conjugated photovoltaic materials. © 2015 Society of Chemical Industry}, number={8}, journal={Polymer International}, author={Zhang, Hao and Ye, Long and Hou, Jianhui}, year={2015}, pages={957–962} }
@article{zhang_uddin_zhao_ye_woo_liu_yang_yao_cui_hou_2015, title={Optimization of side chains in alkylthiothiophene-substituted benzo[1,2-b:4,5-b '] dithiophene-based photovoltaic polymers}, volume={6}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000351720100017&KeyUID=WOS:000351720100017}, DOI={10.1039/c5py00071h}, abstractNote={Alkyl side chains play critical roles in the molecular design of conjugated polymers for applications in bulk-heterojunction (BHJ) polymer solar cells (PSCs).}, number={14}, journal={Polymer Chemistry}, author={Zhang, Shaoqing and Uddin, Mohammad Afsar and Zhao, Wenchao and Ye, Long and Woo, Han Young and Liu, Delong and Yang, Bei and Yao, Huifeng and Cui, Yong and Hou, Jianhui}, year={2015}, pages={2752–2760} }
@article{ye_fan_zhang_li_yang_qin_zhang_hou_2015, title={Perovskite-polymer hybrid solar cells with near-infrared external quantum efficiency over 40%}, volume={58}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000383100400008&KeyUID=WOS:000383100400008}, DOI={10.1007/s40843-015-0102-x}, abstractNote={In the past several years, conjugated polymers and organometal halide perovskites have become regarded as promising light-absorbing materials for next-generation photovoltaic devices and have attracted a great deal of interest. As the main part of this contribution, we describe the enhancement of near-infrared (NIR) photoresponse of well-known CH3NH3PbI3−x Cl x -based solar cells by the integration of bulk heterojunction (BHJ) small band gap polymer:fullerene absorbers. Particularly, the integration of a commercially available polymer PDPP3T and PCBM-based BHJ boosts the peak external quantum efficiency (EQE) by up to 46% in the NIR region (800−1000 nm), which is outside of the photoresponsive region (300−800 nm) of conventional perovskite solar cells. This substantial improvement in the EQE over the NIR region offers an additional current density of ∼5 mA cm−2 for the control perovskite solar cell, and a high power conversion efficiency (PCE) of over 12% was obtained in the perovskite/BHJ-based solar cells. In addition, the insertion of the BHJ absorber consisting of a small band gap polymer PDTP-DFBT and PCBM also results in nearly 40% EQE for the perovskite/BHJ solar cell. The results also reveal that controlling over the polymer/PCBM weight ratio for a BHJ absorber is the key to achieving the optimal efficiency for this type of perovskite-polymer hybrid solar cell.}, number={12}, journal={Science China-Materials}, author={Ye, Long and Fan, Benhu and Zhang, Shaoqing and Li, Sunsun and Yang, Bei and Qin, Yunpeng and Zhang, Hao and Hou, Jianhui}, year={2015}, pages={953–960} }
@article{zhang_ye_zhao_yang_wang_hou_2015, title={Realizing over 10% efficiency in polymer solar cell by device optimization}, volume={58}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84922231541&partnerID=MN8TOARS}, DOI={10.1007/s11426-014-5273-x}, number={2}, journal={Science China Chemistry}, author={Zhang, S. and Ye, L. and Zhao, W. and Yang, B. and Wang, Q. and Hou, J.}, year={2015}, pages={248–256} }
@article{ye_jiang_zhao_zhang_cui_wang_hou_2015, title={Toward efficient non-fullerene polymer solar cells: Selection of donor polymers}, volume={17}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84920822711&partnerID=MN8TOARS}, DOI={10.1016/j.orgel.2014.12.020}, abstractNote={Recently, perylene bisimides have been explored and developed as potential candidates for non-fullerene acceptors and power conversion efficiencies (PCEs) exceeding 3% were realized in the non-fullerene polymer solar cells (NF-PSCs) featuring perylene bisimides as acceptors. Considering that only a few donor polymers like P3HT and PBDTTT-C-T were utilized in non-fullerene PSCs, screening donor polymers with well-matched energy levels, absorption spectrum as well as hole mobility in NF-PSCs will be the key to promote the current PCEs. Herein, four high performance donor polymers including PBDTTPD, PBDTTT-EFT, PDPP3T, PSBTBT were employed for the optimization of single bond-linked perylene bisimide (SDIPBI)-based NF-PSCs. A clear criterion in selection of donor polymers has been established for the SDIPBI-based NF-PSCs. Suitable energy level differences, finer morphology, and broad absorption ranges could be successively screened for donor polymers. Interestingly, NF-PSCs based on PBDTTPD/SDIPBI delivers a high Voc of 1.04 V and a desirable PCE of 3.4%. Moreover, the SDIPBI-based NF-PSC employing PBDTTT-EFT as donor polymer exhibits a high PCE up to 4.5%. The results implicate that to select donor polymers is a feasible strategy to boost the photovoltaic performance of NF-PSCs further.}, journal={Organic Electronics: physics, materials, applications}, author={Ye, L. and Jiang, W. and Zhao, W. and Zhang, S. and Cui, Y. and Wang, Z. and Hou, J.}, year={2015}, pages={295–303} }
@article{ye_zhou_meng_wu_lin_liao_zhang_hou_2015, title={Toward reliable and accurate evaluation of polymer solar cells based on low band gap polymers}, volume={3}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84919684213&partnerID=MN8TOARS}, DOI={10.1039/c4tc02449d}, abstractNote={To accurately evaluate the power conversion efficiencies, a general set of procedures were provided for low band gap polymers.}, number={3}, journal={Journal of Materials Chemistry C}, author={Ye, L. and Zhou, C. and Meng, H. and Wu, H.-H. and Lin, C.-C. and Liao, H.-H. and Zhang, S. and Hou, J.}, year={2015}, pages={564–569} }
@article{jiang_ye_li_xiao_tan_zhao_hou_wang_2014, title={Bay-linked perylene bisimides as promising non-fullerene acceptors for organic solar cells}, volume={50}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84890848848&partnerID=MN8TOARS}, DOI={10.1039/c3cc47204c}, abstractNote={A series of bay-linked perylene bisimides as non-fullerene acceptors for organic solar cells are designed. The best power conversion efficiency up to 3.63% based on s-diPBI (1b) is demonstrated by fine-tuning optoelectronic properties resulting from different degrees of twisting and flexibility by bay-linkages.}, number={8}, journal={Chemical Communications}, author={Jiang, Wei and Ye, Long and Li, Xiangguang and Xiao, Chengyi and Tan, Fang and Zhao, Wenchao and Hou, Jianhui and Wang, Zhaohui}, year={2014}, pages={1024–1026} }
@article{cheng_ye_zhao_hou_li_zhan_2014, title={Binary additives synergistically boost the efficiency of all-polymer solar cells up to 3.45%}, volume={7}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84894031115&partnerID=MN8TOARS}, DOI={10.1039/c3ee43041c}, abstractNote={Binary additives synergistically boost the power conversion efficiency of all-polymer solar cells up to 3.45%. The nonvolatile additive PDI-2DTT suppresses aggregation of the acceptor PPDIDTT and enhances donor/acceptor mixing, while the additive DIO facilitates aggregation and crystallization of the donor PBDTTT-C-T as well as improves phase separation. Combination of DIO and PDI-2DTT leads to suitable phase separation and improved and balanced charge transport, which is beneficial to efficiency enhancement.}, number={4}, journal={Energy & Environmental Science}, author={Cheng, Pei and Ye, Long and Zhao, Xingang and Hou, Jianhui and Li, Yongfang and Zhan, Xiaowei}, year={2014}, pages={1351–1356} }
@article{guo_zhang_ma_ye_zhang_liu_ade_huang_hou_2014, title={Enhanced Photovoltaic Performance by Modulating Surface Composition in Bulk Heterojunction Polymer Solar Cells Based on PBDTTT-C-T/PC71BM}, volume={26}, ISSN={["1521-4095"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84903160839&partnerID=MN8TOARS}, DOI={10.1002/adma.201400411}, abstractNote={For the blend film of PBDTTT-C-T:PC71 BM, the use of 1,8-diiodooctane as the solvent additive enriches the polymer at the top surface, so that a power conversion efficiency of 9.13% is recorded in the inverted polymer solar cell based on the blend, which is much higher than that of the device with conventional structure.}, number={24}, journal={ADVANCED MATERIALS}, author={Guo, Xia and Zhang, Maojie and Ma, Wei and Ye, Long and Zhang, Shaoqing and Liu, Shengjian and Ade, Harald and Huang, Fei and Hou, Jianhui}, year={2014}, month={Jun}, pages={4043–4049} }
@article{ye_zhang_zhao_yao_hou_2014, title={Highly Efficient 2D-Conjugated Benzodithiophene-Based Photovoltaic Polymer with Linear Alkylthio Side Chain}, volume={26}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000338089500004&KeyUID=WOS:000338089500004}, DOI={10.1021/cm501513n}, abstractNote={ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTHighly Efficient 2D-Conjugated Benzodithiophene-Based Photovoltaic Polymer with Linear Alkylthio Side ChainLong Ye†‡, Shaoqing Zhang†, Wenchao Zhao†, Huifeng Yao†‡, and Jianhui Hou*†View Author Information† State Key Laboratory of Polymer Physics and Chemistry, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China‡ University of Chinese Academy of Sciences, Beijing 100049, China*E-mail: [email protected]Cite this: Chem. Mater. 2014, 26, 12, 3603–3605Publication Date (Web):June 12, 2014Publication History Received18 April 2014Revised8 June 2014Published online12 June 2014Published inissue 24 June 2014https://doi.org/10.1021/cm501513nCopyright © 2014 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views8298Altmetric-Citations512LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit Read OnlinePDF (1002 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information SUBJECTS:Absorption,Conjugated polymers,Photovoltaics,Polymers,Power conversion efficiency Get e-Alerts}, number={12}, journal={Chemistry of Materials}, author={Ye, Long and Zhang, Shaoqing and Zhao, Wenchao and Yao, Huifeng and Hou, Jianhui}, year={2014}, pages={3603–3605} }
@article{wang_zhang_ye_cui_fan_hou_2014, title={Investigations of the Conjugated Polymers Based on Dithienogermole (DTG) Units for Photovoltaic Applications}, volume={47}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84906675984&partnerID=MN8TOARS}, DOI={10.1021/ma500831z}, abstractNote={Conjugated polymers based on the dithienogermole (DTG) units showed promising properties for the applications in polymer solar cells (PSCs), so that the investigations of the natures and photovoltaic properties of the DTG-based polymers with varied backbone structures would be of great interest. In this work, four DTG-based polymers named as PDTG-BDD, PDTG-IID, PDTG-BT, and PDTG-DPP were synthesized and characterized. The results indicate that the DTG-based polymers show varied absorption bands and molecular energy levels. In X-ray diffraction measurements, these polymers show different laminar packing and π–π stacking distances in solid films. The PSC devices based on the four DTG-based polymers were fabricated, and their photovoltaic properties were characterized. The results show that different device fabrication conditions are needed to get optimal photovoltaic performance of these four polymers. The device of PDTG-BDD shows a PCE of 6.3% with a high Voc of 0.935 V, a FF of 65.0%, and a Jsc of 10.3 mA/cm2, which is the highest one in these four polymers; the devices of PDTG-DPP showed a miserably low Jsc of 3.19 mA/cm2 due to the unfavorable morphologies of the polymer:PC71BM blend. Overall, the comparisons among these four polymers provide fundamental information for understanding the correlations among molecular structures and photovoltaic properties of the DTG-based polymers, and how to control or modulate the bandgaps, molecular energy levels, and morphologies of the DTG-polymers will be the key to fully explore their potentials as photovoltaic materials.}, number={16}, journal={Macromolecules}, author={Wang, Qi and Zhang, Shaoqing and Ye, Long and Cui, Yong and Fan, Huili and Hou, Jianhui}, year={2014}, pages={5558–5565} }
@article{ye_zhang_huo_zhang_hou_2014, title={Molecular Design toward Highly Efficient Photovoltaic Polymers Based on Two-Dimensional Conjugated Benzodithiophene}, volume={47}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84901270303&partnerID=MN8TOARS}, DOI={10.1021/ar5000743}, abstractNote={As researchers continue to develop new organic materials for solar cells, benzo[1,2-b:4,5-b']dithiophene (BDT)-based polymers have come to the fore. To improve the photovoltaic properties of BDT-based polymers, researchers have developed and applied various strategies leading to the successful molecular design of highly efficient photovoltaic polymers. Novel polymer materials composed of two-dimensional conjugated BDT (2D-conjugated BDT) have boosted the power conversion efficiency of polymer solar cells (PSCs) to levels that exceed 9%. In this Account, we summarize recent progress related to the design and synthesis of 2D-conjugated BDT-based polymers and discuss their applications in highly efficient photovoltaic devices. We introduce the basic considerations for the construction of 2D-conjugated BDT-based polymers and systematic molecular design guidelines. For example, simply modifying an alkoxyl-substituted BDT to form an alkylthienyl-substituted BDT can improve the polymer hole mobilities substantially with little effect on their molecular energy level. Secondly, the addition of a variety of chemical moieties to the polymer can produce a 2D-conjugated BDT unit with more functions. For example, the introduction of a conjugated side chain with electron deficient groups (such as para-alkyl-phenyl, meta-alkoxyl-phenyl, and 2-alkyl-3-fluoro-thienyl) allowed us to modulate the molecular energy levels of 2D-conjugated BDT-based polymers. Through the rational design of BDT analogues such as dithienobenzodithiophene (DTBDT) or the insertion of larger π bridges, we can tune the backbone conformations of these polymers and modulate their photovoltaic properties. We also discuss the influence of 2D-conjugated BDT on polymer morphology and the blends of these polymers with phenyl-C61 (or C71)-butyric acid methyl ester (PCBM). Finally, we summarize the various applications of the 2D-conjugated BDT-based polymers in highly efficient PSC devices. Overall, this Account correlates the molecular structures of the 2D-conjugated BDT-based polymers with their photovoltaic properties. As a result, this Account can guide the molecular design of organic photovoltaic materials and the development of organic materials for other types of optoelectronic devices.}, number={5}, journal={Accounts of Chemical Research}, author={Ye, Long and Zhang, Shaoqing and Huo, Lijun and Zhang, Maojie and Hou, Jianhui}, year={2014}, pages={1595–1603} }
@article{ma_tumbleston_ye_wang_hou_ade_2014, title={Photovoltaics: Quantification of Nano- and Mesoscale Phase Separation and Relation to Donor and Acceptor Quantum Efficiency,Jsc, and FF in Polymer:Fullerene Solar Cells (Adv. Mater. 25/2014)}, volume={26}, ISSN={0935-9648}, url={http://dx.doi.org/10.1002/ADMA.201470171}, DOI={10.1002/adma.201470171}, abstractNote={On page 4234, J. Hou, H. Ade, and co-workers quantify the composition variations in a complex three-phase, hierarchical morphology of polymer/fullerene devices and establish novel structure–function relations by combining different X-ray scattering techniques. Anti-correlated composition variations between meso- and nanoscale separation are observed and impacted by the solvent mixture.}, number={25}, journal={Advanced Materials}, publisher={Wiley}, author={Ma, Wei and Tumbleston, John R. and Ye, Long and Wang, Cheng and Hou, Jianhui and Ade, Harald}, year={2014}, month={Jul}, pages={4399–4399} }
@article{ma_tumbleston_ye_wang_hou_ade_2014, title={Quantification of Nano- and Mesoscale Phase Separation and Relation to Donor and Acceptor Quantum Efficiency, J(SC), and FF in Polymer:Fullerene Solar Cells}, volume={26}, ISSN={["1521-4095"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84903724646&partnerID=MN8TOARS}, DOI={10.1002/adma.201400216}, abstractNote={Two characteristic length scales are revealed and quantified in a complex hierarchical polymer–fullerene blend by combining different X-ray scattering techniques. Anti-correlated composition variations between meso- and nanoscale separation are observed and impacted by the solvent mixture. Due to competition between the impact of the two length scales, the relation to device performance is complex and an ideal morphology is yet to be delineated.}, number={25}, journal={ADVANCED MATERIALS}, author={Ma, Wei and Tumbleston, John R. and Ye, Long and Wang, Cheng and Hou, Jianhui and Ade, Harald}, year={2014}, month={Jul}, pages={4234–4241} }
@article{ye_jiang_zhao_zhang_qian_wang_hou_2014, title={Selecting a Donor Polymer for Realizing Favorable Morphology in Efficient Non-fullerene Acceptor-based Solar Cells}, volume={10}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000345366800016&KeyUID=WOS:000345366800016}, DOI={10.1002/smll.201401082}, abstractNote={A highly efficient non-fullerene small molecule-based polymer solar cell (n-PSC) is realized by employing PBDTBDD as donor polymer and singly linked perylene bisimide (SDIPBI) as acceptor with PCE up to 4.4%, which is one of the outstanding values among n-PSCs so far. In particular, high Voc of 0.87 V and FF over 60% are achieved for PBDTBDD: SDIPBI based PSCs.}, number={22}, journal={Small}, author={Ye, Long and Jiang, Wei and Zhao, Wenchao and Zhang, Shaoqing and Qian, Deping and Wang, Zhaohui and Hou, Jianhui}, year={2014}, pages={4658–4663} }
@article{zhang_ye_zhao_liu_yao_hou_2014, title={Side Chain Selection for Designing Highly Efficient Photovoltaic Polymers with 2D-Conjugated Structure}, volume={47}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84904648056&partnerID=MN8TOARS}, DOI={10.1021/ma500829r}, abstractNote={Recently, the benzodithiophene- (BDT-) based polymers with conjugated side groups attracted considerable attention due to their superior properties in polymer solar cells (PSCs), so the investigation of the side chain effects on the photovoltaic properties of this type of polymers is an interesting and important topic for molecular design. Herein, three conjugated polymers based on BDT and thieno[3,4-b]thiophene units with furan, thiophene and selenophene as side groups, named as PBDTTT-EFF, PBDTTT-EFT, and PBDTTT-EFS, were synthesized and applied in polymer solar cells. The polymers were characterized in parallel by absorption spectroscopy, thermogravimetric analysis (TGA), density functional theory (DFT), ultraviolet photoemission spectroscopy (UPS), X-ray diffraction (XRD), and photovoltaic measurements. The results show that the dihedral angles between the BDT and conjugated side groups play important roles in affecting the absorption bands, HOMO levels, crystallinities, and aggregation sizes of the polymers. The photovoltaic results indicate that PBDTTT-EFT and PBDTTT-EFS show similar photovoltaic characteristics in device, and PCEs of 9.0% and 8.78% were obtained, respectively. The device of PBDTTT-EFF shows a Voc of 0.69 V and a Jsc of 11.77 mA/cm2, which are lower than those in the devices based on the other two polymers. Overall, this work suggests that the photovoltaic properties of the BDT-based polymers can be effectively tuned by introducing conjugated side groups with varied steric hindrance.}, number={14}, journal={Macromolecules}, author={Zhang, Shaoqing and Ye, Long and Zhao, Wenchao and Liu, Delong and Yao, Huifeng and Hou, Jianhui}, year={2014}, pages={4653–4659} }
@article{zhao_ye_zhang_fan_sun_hou_2014, title={Ultrathin Polyaniline-based Buffer Layer for Highly Efficient Polymer Solar Cells with Wide Applicability}, volume={4}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000343082600001&KeyUID=WOS:000343082600001}, DOI={10.1038/srep06570}, abstractNote={Interfacial buffer layers often attribute the improved device performance in organic optoelectronic device. Herein, a water-soluble hydrochloric acid doped polyanilines (HAPAN) were utilized as p-type electrode buffer layer in highly efficient polymer solar cells (PSC) based on PBDTTT-EFT and several representative polymers. The PBDTTT-EFT-based conventional PSC featuring ultrathin HAPAN (1.3 nm) delivered high PCE approximately 9%, which is one of the highest values among conventional PSC devices. Moreover, ultrathin HAPAN also exhibited wide applicability in a variety of efficient photovoltaic polymers including PBDTTT-C-T, PTB7, PBDTBDD, PBTTDPP-T, PDPP3T and P3HT. The excellent performances were originated from the high transparency, small film roughness and suitable work function.}, journal={Scientific Reports}, author={Zhao, Wenchao and Ye, Long and Zhang, Shaoqing and Fan, Bin and Sun, Mingliang and Hou, Jianhui}, year={2014} }
@article{zhang_lu_ye_zhan_hou_zhang_jiang_zhao_huang_zhang_et al._2013, title={A Potential Perylene Diimide Dimer-Based Acceptor Material for Highly Efficient Solution-Processed Non-Fullerene Organic Solar Cells with 4.03% Efficiency}, volume={25}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84886440285&partnerID=MN8TOARS}, DOI={10.1002/adma.201300897}, abstractNote={A highly efficient acceptor material for organic solar cells (OSCs) – based on perylene diimide (PDI) dimers – shows significantly reduced aggregation compared to monomeric PDI. The dimeric PDI shows a best power conversion efficiency (PCE) approximately 300 times that of the monomeric PDI when blended with a conjugate polymer (BDTTTT-C-T) and with 1,8-diiodooctane as co-solvent (5%). This shows that non-fullerene materials also hold promise for efficient OSCs. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.}, number={40}, journal={Advanced Materials}, author={Zhang, Xin and Lu, Zhenhuan and Ye, Long and Zhan, Chuanlang and Hou, Jianhui and Zhang, Shaoqing and Jiang, Bo and Zhao, Yan and Huang, Jianhua and Zhang, Shanlin and et al.}, year={2013}, pages={5791-+} }
@article{ye_zhang_qian_wang_hou_2013, title={Application of Bis-PCBM in Polymer Solar Cells with Improved Voltage}, volume={117}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84890379846&partnerID=MN8TOARS}, DOI={10.1021/jp409216e}, abstractNote={In recent years, fullerene bis-adducts have gained significant interest within the academic community due to their high-lying LUMO level. Herein, we carried out device optimization of the photovoltaic performances of novel photovoltaic polymer PBDTBDD with Bis-PCBM, and several characterization techniques including photoluminescence quench analysis, X-ray diffraction patterns, and atomic force microscopy were employed. As the synergistic result of balanced mobility, better crystallinity, efficient exciton dissociation, and charge transport efficiency, high fill factor and short-circuit current density as well as power conversion efficiency were achieved in the PBDTBDD/Bis-PCBM device. In addition, the optimized PSC device based on PBDTBDD:Bis-PCBM (1:1, wt/wt) with 3 vol % DIO yielded a high PCE of 6.07% with Voc of 1.00 V, Jsc of 10.02 mA/cm2, and FF of 60.54% under the illumination of AM1.5G, 100 mW/cm2. Therefore, we reported that polymer/Bis-PCBM-based polymer solar cells obtain both high efficiency ∼6% and high Voc ≈ 1 V, which exhibited PBDTBDD/Bis-PCBM and is a promising blue absorber unit for tandem devices, and also paved a path to optimization of other polymer/Bis-PCBM systems.}, number={48}, journal={Journal of Physical Chemistry C}, author={Ye, Long and Zhang, Shaoqing and Qian, Deping and Wang, Qi and Hou, Jianhui}, year={2013}, pages={25360–25366} }
@article{huo_li_guo_wu_zhang_ye_zhang_hou_2013, title={Benzodifuran-alt-thienothiophene based low band gap copolymers: substituent effects on their molecular energy levels and photovoltaic properties}, volume={4}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000317936500016&KeyUID=WOS:000317936500016}, DOI={10.1039/c3py00074e}, abstractNote={A series of low band gap photovoltaic copolymers containing benzodifuran-alt-thieno[3,4-b]thiophene (BDF-alt-TT) were designed and synthesized. Functional groups with different electron-withdrawing abilities such as carbonyl, ester, fluorine, sulfuryl and cyano were introduced to the thieno[3,4-b]thiophene unit to finely tune the molecular energy levels of these copolymers. All these copolymers are characterized by UV-Vis spectroscopy and electrochemical cyclic voltammetry (CV) to evaluate the effects of these electron-deficient functional groups. According to their electrochemical behaviours, the electron-deficient abilities of these functional groups can be arranged in the order carbonyl < fluorine + ester < fluorine + carbonyl < sulfuryl < cyano + ester. It was found the sulfuryl group and cyano substituted copolymers show blue-shift in absorption spectra compared to the other three copolymers, indicating that sulfuryl and cyano groups may cause stronger steric hindrance to the conjugated backbones. The photovoltaic properties of these copolymers were also investigated by making polymer solar cell (PSC) devices. Interestingly, although the copolymers have different molecular structures, the optimal D/A (polymer/PC71BM, wt/wt) ratios of all of the devices are 1 : 1.5. 1,8-Diiodooctane (DIO) was used to further improve the photovoltaic performance of the devices. The champion efficiency of 5.23% with an open circuit voltage (Voc) of 0.63 V was achieved from PBDFTT-CF/PC71BM based devices. The device based on the cyano-substituted copolymer, PBDFTT-ECN, shows a rather high Voc of 0.87 V, but the short current density (Jsc) is significant lower than the device based on PBDFTT-CF, and its seems that the offset between the LUMO levels of PBDFTT-ECN and PC71BM is too small to achieve efficient charge separation. In conclusion, the molecular energy level of the copolymers with the alternating aromatic–quinoid (A–Q) structure, BDF-alt-TT, can be tuned effectively by introducing electron-deficient groups. Furthermore, according to the photovoltaic results of PBDFTT-S and PBDFTT-CNF, a LUMO level of −3.70 eV may reach the threshold of getting efficient charge separation of the polymer/PC71BM blend.}, number={10}, journal={Polymer Chemistry}, author={Huo, Lijun and Li, Zhaojun and Guo, Xia and Wu, Yue and Zhang, Maojie and Ye, Long and Zhang, Shaoqing and Hou, Jianhui}, year={2013}, pages={3047–3056} }
@article{ma_ye_zhang_hou_ade_2013, title={Competition between morphological attributes in the thermal annealing and additive processing of polymer solar cells}, volume={1}, ISSN={2050-7526 2050-7534}, url={http://dx.doi.org/10.1039/C3TC30679H}, DOI={10.1039/c3tc30679h}, abstractNote={Thermal annealing and additive processing are employed and compared using alkoxy substituted (QxO) and extended π conjugated alkythienyl substituted (QxT) benzo[1,2-b:4,5 b′]dithiophene based heterojunction (BHJ) solar cells. The characteristic median length of the morphology, average composition fluctuations, interface structure, crystallinity and molecular miscibility are investigated based on these two processes. Our results suggest that focusing on single structural, morphological or thermodynamic measurements is not sufficient to explain differences in device performance. In the current work, no blends are close to the ideal morphology containing either domains that are too large, too mixed or too pure. An optimization strategy is proposed to improve those devices. Importantly, we find that domain size and relative domain purity are overall correlated with molecular miscibility, i.e. the more immiscible system induces larger and purer domains irrespective of the processing and even in non-equilibrium structures. This indicates that the relative domain size and purity, and device performance can be potentially predicted by the donor–acceptor molecular miscibility, a factor not yet widely considered when designing new materials for BHJ devices.}, number={33}, journal={Journal of Materials Chemistry C}, publisher={Royal Society of Chemistry (RSC)}, author={Ma, Wei and Ye, Long and Zhang, Shaoqing and Hou, Jianhui and Ade, Harald}, year={2013}, pages={5023} }
@article{zhang_ye_wang_li_guo_huo_fan_hou_2013, title={Enhanced Photovoltaic Performance of Diketopyrrolopyrrole (DPP)-Based Polymers with Extended pi Conjugation}, volume={117}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84878040754&partnerID=MN8TOARS}, DOI={10.1021/jp312450p}, abstractNote={To extend the π conjugation along backbone units is an effective way to tune the optoelectronic properties of conjugated polymers. In this work, to investigate the influence of the extended conjugation on photovoltaic properties of the polymer, we employed a two-step molecular optimization process, and a series of diketopyrrolopyrrole (DPP)-based conjugated polymers, PBDPP-1, PBDPP-2, and PBDPP-3, was prepared and applied in polymer solar cells. After this two-step optimization of molecular structure, the compatibility between the polymer and PC71BM becomes much better; as a result, bicontinuous phase separation with appropriate domain size can be formed in the blend of PBDPP-3/PC71BM. Therefore, the PBDPP-3/PC71BM-based device shows a short circuit current density (Jsc) of 16.25 mA/cm2, which is more than two times of that of the PBDPP-1/PC71BM-based device. In addition, the blend films processed by DIO/CB showed smoother surfaces as well as smaller domain size compared with the blend films processed by pure CB. The results in this work indicate that when conjugation of the DPP-polymer’s backbone is extended in two dimensions the morphology of the active layers in photovoltaic device can be optimized effectively, and hence the overall efficiency can be improved from 2.83 to 6.18%.}, number={19}, journal={Journal of Physical Chemistry C}, author={Zhang, Shaoqing and Ye, Long and Wang, Qi and Li, Zhaojun and Guo, Xia and Huo, Lijun and Fan, Huili and Hou, Jianhui}, year={2013}, pages={9550–9557} }
@article{qian_ma_li_guo_zhang_ye_ade_tan_hou_2013, title={Molecular Design toward Efficient Polymer Solar Cells with High Polymer Content}, volume={135}, ISSN={["1520-5126"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84878954003&partnerID=MN8TOARS}, DOI={10.1021/ja402971d}, abstractNote={A novel polythiophene derivative, PBT1, was designed, synthesized, and applied in polymer solar cells (PSCs). This work provides a successful example of using molecular structure as a tool to realize optimal photovoltaic performance with high polymer content, thus enabling the realization of efficient photoabsorption in very thin films. As a result, an efficiency of 6.88% was recorded in a PSC with a 75 nm active layer.}, number={23}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, author={Qian, Deping and Ma, Wei and Li, Zhaojun and Guo, Xia and Zhang, Shaoqing and Ye, Long and Ade, Harald and Tan, Zhan'ao and Hou, Jianhui}, year={2013}, month={Jun}, pages={8464–8467} }
@article{ye_jing_guo_sun_zhang_zhang_huo_hou_2013, title={Remove the Residual Additives toward Enhanced Efficiency with Higher Reproducibility in Polymer Solar Cells}, volume={117}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84880809279&partnerID=MN8TOARS}, DOI={10.1021/jp404395q}, abstractNote={Undesirable efficiency reproducibility was sometimes observed in fabrication of high performance polymer solar cell devices incorporating high boiling point additives. The anomalous results originated from the slow drying of additives not only reduced the controllability of device performance but also impeded the studies of device physics and material design. How to remove the residual additives and achieve stable interface properties is crucial for both the academic and industrial community. Herein, we demonstrated that the morphological stability is enhanced and efficiency reproducibility is increased obviously from 7.07 ± 0.27% to 7.53 ± 0.12% after spin-coating inert solvents for the PBDTTT-C-T/PCBM system. The relationship between processing conditions and photovoltaic performance was well explored and demonstrated via multiple techniques including atomic force microscopy, Kelvin probe force microscopy, transmission electron microscopy, and X-ray photospectroscopy. Most importantly, this method was successfully employed in more than five representative donor polymers. Our study suggested that the slow drying process of the residual high boiling point additives could induce undesirable morphological variation as well as unfavorable interfacial contact, and by washing with low boiling point “inert” solvent, like methanol, the negative influence caused by the residual additive can be avoided and hence the additives would perform more efficiently in the optimization of device performance of highly efficient PSCs.}, number={29}, journal={Journal of Physical Chemistry C}, author={Ye, Long and Jing, Yan and Guo, Xia and Sun, Hao and Zhang, Shaoqing and Zhang, Maojie and Huo, Lijun and Hou, Jianhui}, year={2013}, pages={14920–14928} }
@article{subnanosecond charge photogeneration and recombination in polyfluorene copolymer-fullerene solar cell: effects of electric field_2013, volume={21}, number={5}, journal={Optics Express}, year={2013}, pages={A241–A249} }
@article{zhang_huang_xing_jing_ye_fu_ai_hou_zhang_2013, title={Subnanosecond charge photogeneration and recombination in polyfluorene copolymerfullerene solar cell: Effects of electric field}, volume={21}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84875199130&partnerID=MN8TOARS}, DOI={10.1364/OE.21.00A241}, abstractNote={Influence of electric field on the subnanosecond charge photogeneration dynamics in the polymer solar cell based on polyfluorene copolymer BisDMO-PFDTBT blended with PC(61)BM was examined with transient absorption spectroscopy. The charge dynamics showed no difference under short- or open-circuit conditions and under a forward bias of 0.79 V (1.6 × 10(5) V/cm), implying negligible field effects on the subnanosecond dynamics of charge photogeneration/recombination. However, under the reverse biases of -2 V (4.0 × 10(5) V/cm) and -5 V (1.0 × 10(6) V/cm), significant enhancement of charge photogeneration and apparent suppression of polaron pair recombination were observed, which agrees with the field-assisted enhancement of external quantum efficiency of the solar cell devices.}, number={SUPPL.2}, journal={Optics Express}, author={Zhang, W. and Huang, Y. and Xing, Y.-D. and Jing, Y. and Ye, L. and Fu, L.-M. and Ai, X.-C. and Hou, J.-H. and Zhang, J.-P.}, year={2013} }
@article{duan_ye_guo_huang_wang_zhang_zhang_huo_hou_2012, title={Application of Two-Dimensional Conjugated Benzo 1,2-b:4,5-b ' dithiophene in Quinoxaline-Based Photovoltaic Polymers}, volume={45}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84859621582&partnerID=MN8TOARS}, DOI={10.1021/ma300060z}, abstractNote={Two new donor–acceptor (D–A) alternative copolymers, PBDTDTQx-T and PBDTDTQx-O, were designed and synthesized to investigate the influence of two-dimensional conjugated structure on photovoltaic properties of conjugated polymers. In these two polymers, PBDTDTQx-O was used as control material, which is an alternative copolymer based on a quinoxaline derivative (DTQx) and alkoxy-substituted benzo[1,2-b:4,5-b′]dithiophene (BDT-O) unit; PBDTDTQx-T has an identical conjugated backbone as PBDTDTQx-O, but a simple two-dimensional conjugated BDT unit (BDT-T) was used to replace the alkoxy-BDT. The polymers were characterized by TGA, UV–vis absorption, electrochemical cyclic voltammetry, hole mobility of space-charge-limited current (SCLC) model, and photovoltaic measurements. It was found that PBDTDTQx-T exhibits similar molecular energy levels and higher hole mobility than PBDTDTQx-O. The power conversion efficiency (PCE) of the polymer solar cells (PSCs) based on PBDTDTQx-T: [6,6]-phenyl-C-71-butyric acid methyl ester (PC71BM) = 1/2 (w/w) reached ∼5%, which is 60% higher than that of PBDTDTQx-O-based PSC. On the basis of these results, it can be concluded that the application of two-dimensional conjugated structure would be a feasible approach to improve photovoltaic properties of conjugated polymers.}, number={7}, journal={Macromolecules}, author={Duan, Ruomeng and Ye, Long and Guo, Xia and Huang, Ye and Wang, Peng and Zhang, Shaoqing and Zhang, Jianping and Huo, Lijun and Hou, Jianhui}, year={2012}, pages={3032–3038} }
@article{huo_ye_wu_li_guo_zhang_zhang_hou_2012, title={Conjugated and Nonconjugated Substitution Effect on Photovoltaic Properties of Benzodifuran-Based Photovoltaic Polymers}, volume={45}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84866104855&partnerID=MN8TOARS}, DOI={10.1021/ma301254x}, abstractNote={In order to investigate the influence of two-dimensional (2D) conjugated structure on photovoltaic properties of benzo[1,2-b:4,5-b′]difuran (BDF)-based polymers, two low band gap photovoltaic polymers, named PBDFTT-CF-O and PBDFTT-CF-T, were designed and synthesized. These two polymers have the same backbones and different side groups. Although these two polymers show similar optical band gaps (ca. 1.5 eV), the polymer with alkylthienyl side groups, PBDFTT-CF-T, exhibits stronger absorption in long wavelength direction than the polymer with alkoxyl side groups, PBDFTT-CF-O. Meanwhile, PBDFTT-CF-T exhibits a HOMO level of −5.21 eV, which is 0.23 eV lower than that of PBDFTT-CF-O due to weaker electron-donating ability of alkylthienyl side groups than that of aloxyl side groups. The hole mobility of the blend of PBDFTT-CF-T/PC71BM (1:1.5, w/w) is 0.128 cm2 V–1 s–1, which is 1 order of magnitude higher than that of the blend of PBDFTT-CF-O/PC71BM. Density functional theory (DFT) model shows thiophene pendants on dithienyl-BDF are more coplanar than it on dithienyl-BDT. These results indicate that the 2D-conjugated structure is helpful for molecular structure design of the BDF-based polymers in enhancing the intermolecular π–π stacking and improving charge transport property. Furthermore, the photovoltaic devices based on these two polymers show similar short circuit density and fill factor values, while the open circuit voltage of the PBDFTT-CF-T-based device is 0.78 V, which is 0.15 V higher than that of the PBDFTT-CF-O-based device. Therefore, the efficiencies of the devices based PBDFTT-CF-T/PC71BM and PBDFTT-CF-O/PC71BM are 6.26% and 5.22%, respectively. The results in this work demonstrate that the weak electron-donating ability of alkylthienyl side groups can be seen as an effective strategy to improve photovoltaic properties of the BDF-based polymers and the 2D-conjugated molecular structure is favorable to improve hole mobility.}, number={17}, journal={Macromolecules}, author={Huo, Lijun and Ye, Long and Wu, Yue and Li, Zhaojun and Guo, Xia and Zhang, Maojie and Zhang, Shaoqing and Hou, Jianhui}, year={2012}, pages={6923–6929} }
@article{qian_ye_zhang_liang_li_huang_guo_zhang_tan_hou_2012, title={Design, Application, and Morphology Study of a New Photovoltaic Polymer with Strong Aggregation in Solution State}, volume={45}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84871603029&partnerID=MN8TOARS}, DOI={10.1021/ma301900h}, abstractNote={A new conjugated polymer based on 5,7-bis(2-ethylhexyl)benzo[1,2-c:4,5-c′]dithiophene-4,8-dione, named as PBDTBDD, was designed, synthesized, and applied in polymer solar cells (PSCs). A power conversion efficiency (PCE) of 6.67% was obtained from the PBDTBDD/PC61BM-based PSC, which is a remarkable result for the PSCs using PC61BM as electron acceptor. The PBDTBDD/PC61BM-based device exhibits a narrow absorption band and excellent quantum efficiency in the range from 500 to 700 nm. Furthermore, PBDTBDD shows a strong aggregation effect in solution state, and the study indicates that although the temperature used in solution preparation has little influence on molecular orientation as well as crystallinity of the D/A blend, it plays an important role in forming proper domain size in the blend. This work provides a good example to reveal the correlation between the morphology of the blend films and the processing temperature of the solution preparation. Furthermore, the study in this work suggests an interesting and feasible approach to modulate domain size without changing crystallinity of the blend films in PSCs.}, number={24}, journal={Macromolecules}, author={Qian, D. and Ye, L. and Zhang, M. and Liang, Y. and Li, L. and Huang, Y. and Guo, X. and Zhang, S. and Tan, Z. and Hou, J.}, year={2012}, pages={9611–9617} }
@article{ye_zhang_ma_fan_guo_huang_ade_hou_2012, title={From Binary to Ternary Solvent: Morphology Fine-tuning of D/A Blends in PDPP3T-based Polymer Solar Cells}, volume={24}, ISSN={["1521-4095"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84870872663&partnerID=MN8TOARS}, DOI={10.1002/adma.201202855}, abstractNote={Advanced MaterialsVolume 24, Issue 47 p. 6335-6341 Communication From Binary to Ternary Solvent: Morphology Fine-tuning of D/A Blends in PDPP3T-based Polymer Solar Cells Long Ye, Long Ye State Key Laboratory of Polymer Physics and Chemistry, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China Graduate University of Chinese Academy of Sciences, Beijing 100049, P. R. ChinaSearch for more papers by this authorShaoqing Zhang, Shaoqing Zhang State Key Laboratory of Polymer Physics and Chemistry, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. ChinaSearch for more papers by this authorWei Ma, Corresponding Author Wei Ma wma5@ncsu.edu Department of Physics, North Carolina State University, Raleigh, NC 27695, USA Wei Ma, Department of Physics, North Carolina State University, Raleigh, NC 27695, USA. Jianhui Hou, State Key Laboratory of Polymer Physics and Chemistry, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. ChinaSearch for more papers by this authorBenhu Fan, Benhu Fan State Key Laboratory of Polymer Physics and Chemistry, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. ChinaSearch for more papers by this authorXia Guo, Xia Guo State Key Laboratory of Polymer Physics and Chemistry, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China Graduate University of Chinese Academy of Sciences, Beijing 100049, P. R. ChinaSearch for more papers by this authorYe Huang, Ye Huang State Key Laboratory of Polymer Physics and Chemistry, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. ChinaSearch for more papers by this authorHarald Ade, Harald Ade Department of Physics, North Carolina State University, Raleigh, NC 27695, USASearch for more papers by this authorJianhui Hou, Corresponding Author Jianhui Hou hjhzlz@iccas.ac.cn State Key Laboratory of Polymer Physics and Chemistry, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China Wei Ma, Department of Physics, North Carolina State University, Raleigh, NC 27695, USA. Jianhui Hou, State Key Laboratory of Polymer Physics and Chemistry, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. ChinaSearch for more papers by this author Long Ye, Long Ye State Key Laboratory of Polymer Physics and Chemistry, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China Graduate University of Chinese Academy of Sciences, Beijing 100049, P. R. ChinaSearch for more papers by this authorShaoqing Zhang, Shaoqing Zhang State Key Laboratory of Polymer Physics and Chemistry, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. ChinaSearch for more papers by this authorWei Ma, Corresponding Author Wei Ma wma5@ncsu.edu Department of Physics, North Carolina State University, Raleigh, NC 27695, USA Wei Ma, Department of Physics, North Carolina State University, Raleigh, NC 27695, USA. Jianhui Hou, State Key Laboratory of Polymer Physics and Chemistry, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. ChinaSearch for more papers by this authorBenhu Fan, Benhu Fan State Key Laboratory of Polymer Physics and Chemistry, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. ChinaSearch for more papers by this authorXia Guo, Xia Guo State Key Laboratory of Polymer Physics and Chemistry, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China Graduate University of Chinese Academy of Sciences, Beijing 100049, P. R. ChinaSearch for more papers by this authorYe Huang, Ye Huang State Key Laboratory of Polymer Physics and Chemistry, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. ChinaSearch for more papers by this authorHarald Ade, Harald Ade Department of Physics, North Carolina State University, Raleigh, NC 27695, USASearch for more papers by this authorJianhui Hou, Corresponding Author Jianhui Hou hjhzlz@iccas.ac.cn State Key Laboratory of Polymer Physics and Chemistry, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China Wei Ma, Department of Physics, North Carolina State University, Raleigh, NC 27695, USA. Jianhui Hou, State Key Laboratory of Polymer Physics and Chemistry, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. ChinaSearch for more papers by this author First published: 19 September 2012 https://doi.org/10.1002/adma.201202855Citations: 278Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Abstract For the PDPP3T/PCBM system investigated here, atomic force microscopy, resonant soft X-ray scattering, and grazing incidence wide angle X-ray scattering are used as an initial set of tools to determine the surface texture, the bulk compositional morphology, and the crystallization behavior, respectively. We find systematic variations and relate them to device performance. A solvent mixture of DCB/CF/DIO = 76:19:5 (v/v/v) yields a PCE of 6.71%. Citing Literature Supporting Information Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Filename Description adma_201202855_sm_suppl.pdf925.8 KB suppl Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article. Volume24, Issue47December 11, 2012Pages 6335-6341 RelatedInformation}, number={47}, journal={ADVANCED MATERIALS}, author={Ye, Long and Zhang, Shaoqing and Ma, Wei and Fan, Benhu and Guo, Xia and Huang, Ye and Ade, Harald and Hou, Jianhui}, year={2012}, month={Dec}, pages={6335–6341} }
@article{huang_zhang_ye_guo_han_li_hou_2012, title={Molecular energy level modulation by changing the position of electron-donating side groups}, volume={22}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000300838100060&KeyUID=WOS:000300838100060}, DOI={10.1039/c2jm16474d}, abstractNote={An investigation on the opto-electronic and photovoltaic properties of a pair of alkoxy substituted quinoxaline-based copolymers PTTQx is performed in order to describe the effect of changing the position of alkoxy substituents on the peripheral phenyl rings. The copolymer with meta-positioned alkoxy showed lower HOMO and LUMO levels and a higher Voc of 0.73 V, while the copolymer with para-positioned alkoxy displayed higher HOMO and LUMO levels and lower Voc of 0.60 V when a polymer/PC71BM blend film was used as the active layer in polymer solar cells (PSCs) under AM 1.5 G irradiation (100 mW cm−2). With the good agreement between theoretical calculation and experimental observation, it has been observed that the effect of the substituents depends on the position of the alkoxy group which exhibits a stronger electron donating effect in the para-position than in the meta-position. The resonance electron donating effect of the alkoxy group on the para-position can elevate the HOMO and LUMO levels simultaneously, while this effect is not obviously reflected on the meta-position. Therefore, PTTQx-m exhibits lower HOMO level, higher Voc correspondingly and thereby higher PCE of the PSCs based on it.}, number={12}, journal={Journal of Materials Chemistry}, author={Huang, Ye and Zhang, Mingqian and Ye, Long and Guo, Xia and Han, Charles C. and Li, Yongfang and Hou, Jianhui}, year={2012}, pages={5700–5705} }