@article{du_luong_sabury_therdkatanyuphong_chae_welton_jones_zhang_peng_zhu_et al._2023, title={Additive-free molecular acceptor organic solar cells processed from a biorenewable solvent approaching 15% efficiency}, volume={10}, ISSN={["2051-6355"]}, DOI={10.1039/d3mh01133j}, abstractNote={We report on the use of molecular acceptors and donor polymers processed with a biomass-derived solvent 2-methyltetrahydrofuran to facilitate bulk heterojunction organic photovoltaics with power conversion efficiency approaching 15%.}, journal={MATERIALS HORIZONS}, author={Du, Zhifang and Luong, Hoang Mai and Sabury, Sina and Therdkatanyuphong, Pattarawadee and Chae, Sangmin and Welton, Claire and Jones, Austin L. and Zhang, Junxiang and Peng, Zhengxing and Zhu, Ziyue and et al.}, year={2023}, month={Oct} }
 @article{siddika_peng_balar_dong_zhong_you_ade_oconnor_2023, title={Molecular interactions that drive morphological and mechanical stabilities in organic solar cells}, volume={7}, ISSN={["2542-4351"]}, DOI={10.1016/j.joule.2023.06.002}, abstractNote={Morphological and mechanical stabilities of organic solar cells (OSCs) are of paramount importance to ensure long-lived devices. However, the fundamental drivers of these stability metrics and their competing relationship have yet to be well defined. Here, several high-performance polymers and small molecule acceptors (SMAs) are considered to assist in the development of a comprehensive view of the molecular drivers of, and interrelationships between, morphological and mechanical stabilities. We find that the SMAs drive much of the embrittlement and diffusion characteristics in the blend films. However, the heterointeraction of the SMA and polymer, probed through dynamic mechanical analysis, is a key contributing factor to the film toughness. The heterointeraction energy is ideally maximally negative (i.e., repulsive), deviating from the geometric mean of the homointeraction energy. These findings assist in introducing a framework to understand the active layer stability and highlight material properties that lead to morphologically stable and physically robust OSCs.}, number={7}, journal={JOULE}, author={Siddika, Salma and Peng, Zhengxing and Balar, Nrup and Dong, Xinyun and Zhong, Xiaowei and You, Wei and Ade, Harald and OConnor, Brendan T.}, year={2023}, month={Jul}, pages={1593–1608} }
 @article{wang_peng_balar_ade_2023, title={Suppressing pre-aggregation to increase polymer solar cell ink shelf life}, volume={11}, ISSN={["2050-7496"]}, DOI={10.1039/d3ta06617g}, abstractNote={An approach to slow down the polymer solar cell ink aging by employing an additive (i.e., PCBM variants) was developed. It is inferred that PCBMs in the ink act as a co-solvent and slow down the polymer pre-aggregation.}, journal={JOURNAL OF MATERIALS CHEMISTRY A}, author={Wang, Zhen and Peng, Zhengxing and Balar, Nrup and Ade, Harald}, year={2023}, month={Nov} }
 @article{peng_ade_2023, title={Unveiling re-entrant phase behavior and crystalline-amorphous interactions in semi-conducting polymer:small molecule blends}, volume={4}, ISSN={["2051-6355"]}, DOI={10.1039/d3mh00034f}, abstractNote={It is revealed that the re-entrant phase behavior of the conjugated polymer:small molecule systems is indeed a result of thermodynamics. The composition difference (Δϕ) between liquidus and binodal reflects the crystalline–amorphous interaction.}, journal={MATERIALS HORIZONS}, author={Peng, Zhengxing and Ade, Harald}, year={2023}, month={Apr} }
 @article{fu_peng_fan_lin_qi_ran_wu_fan_jiang_woo_et al._2022, title={A Top-Down Strategy to Engineer ActiveLayer Morphology for Highly Efficient and Stable All-Polymer Solar Cells}, volume={7}, ISSN={["1521-4095"]}, DOI={10.1002/adma.202202608}, abstractNote={Abstract}, journal={ADVANCED MATERIALS}, author={Fu, Huiting and Peng, Zhengxing and Fan, Qunping and Lin, Francis R. and Qi, Feng and Ran, Yixin and Wu, Ziang and Fan, Baobing and Jiang, Kui and Woo, Han Young and et al.}, year={2022}, month={Jul} }
 @article{gao_qi_peng_lin_jiang_zhong_kaminsky_guan_lee_marks_et al._2022, title={Achieving 19% Power Conversion Efficiency in Planar-Mixed Heterojunction Organic Solar Cells Using a Pseudosymmetric Electron Acceptor}, volume={7}, ISSN={["1521-4095"]}, DOI={10.1002/adma.202202089}, abstractNote={Abstract}, journal={ADVANCED MATERIALS}, author={Gao, Wei and Qi, Feng and Peng, Zhengxing and Lin, Francis R. and Jiang, Kui and Zhong, Cheng and Kaminsky, Werner and Guan, Zhiqiang and Lee, Chun-Sing and Marks, Tobin J. and et al.}, year={2022}, month={Jul} }
 @article{ho_pei_qin_zhang_peng_angunawela_jones_yin_iqbal_reynolds_et al._2022, title={Importance of Electric-Field-Independent Mobilities in Thick-Film Organic Solar Cells}, volume={10}, ISSN={["1944-8252"]}, url={http://dx.doi.org/10.1021/acsami.2c11265}, DOI={10.1021/acsami.2c11265}, abstractNote={In organic solar cells (OSCs), a thick active layer usually yields a higher photocurrent with broader optical absorption than a thin active layer. In fact, a ∼300 nm thick active layer is more compatible with large-area processing methods and theoretically should be a better spot for efficiency optimization. However, the bottleneck of developing high-efficiency thick-film OSCs is the loss in fill factor (FF). The origin of the FF loss is not clearly understood, and there a direct method to identify photoactive materials for high-efficiency thick-film OSCs is lacking. Here, we demonstrate that the mobility field-dependent coefficient is an important parameter directly determining the FF loss in thick-film OSCs. Simulation results based on the drift-diffusion model reveal that a mobility field-dependent coefficient smaller than 10-3 (V/cm)-1/2 is required to maintain a good FF in thick-film devices. To confirm our simulation results, we studied the performance of two ternary bulk heterojunction (BHJ) blends, PTQ10:N3:PC71BM and PM6:N3:PC71BM. We found that the PTQ10 blend film has weaker field-dependent mobilities, giving rise to a more balanced electron-hole transport at low fields. While both the PM6 blend and PTQ10 blend yield good performance in thin-film devices (∼100 nm), only the PTQ10 blend can retain a FF = 74% with an active layer thickness of up to 300 nm. Combining the benefits of a higher JSC in thick-film devices, we achieved a PCE of 16.8% in a 300 nm thick PTQ10:N3:PC71BM OSC. Such a high FF in the thick-film PTQ10 blend is also consistent with the observation of lower charge recombination from light-intensity-dependent measurements and lower energetic disorder observed in photothermal deflection spectroscopy.}, journal={ACS APPLIED MATERIALS & INTERFACES}, publisher={American Chemical Society (ACS)}, author={Ho, Carr Hoi Yi and Pei, Yusen and Qin, Yunpeng and Zhang, Chujun and Peng, Zhengxing and Angunawela, Indunil and Jones, Austin L. and Yin, Hang and Iqbal, Hamna F. and Reynolds, John R. and et al.}, year={2022}, month={Oct} }
 @article{jiang_zhang_zhong_lin_qi_li_peng_kaminsky_jang_yu_et al._2022, title={Suppressed recombination loss in organic photovoltaics adopting a planar-mixed heterojunction architecture}, volume={7}, ISSN={["2058-7546"]}, DOI={10.1038/s41560-022-01138-y}, number={11}, journal={NATURE ENERGY}, author={Jiang, Kui and Zhang, Jie and Zhong, Cheng and Lin, Francis R. and Qi, Feng and Li, Qian and Peng, Zhengxing and Kaminsky, Werner and Jang, Sei-Hum and Yu, Jianwei and et al.}, year={2022}, month={Nov}, pages={1076–1086} }
 @article{yu_luo_sun_angunawela_qi_peng_zhou_han_wei_pan_et al._2021, title={A Difluoro-Monobromo End Group Enables High-Performance Polymer Acceptor and Efficient All-Polymer Solar Cells Processable with Green Solvent under Ambient Condition}, volume={31}, ISSN={["1616-3028"]}, DOI={10.1002/adfm.202100791}, abstractNote={Abstract}, number={25}, journal={ADVANCED FUNCTIONAL MATERIALS}, author={Yu, Han and Luo, Siwei and Sun, Rui and Angunawela, Indunil and Qi, Zhenyu and Peng, Zhengxing and Zhou, Wentao and Han, Han and Wei, Rong and Pan, Mingao and et al.}, year={2021}, month={Jun} }
 @article{ghasemi_balar_peng_hu_qin_kim_rech_bidwell_mask_mcculloch_et al._2021, title={A molecular interaction-diffusion framework for predicting organic solar cell stability}, volume={20}, ISSN={["1476-4660"]}, DOI={10.1038/s41563-020-00872-6}, abstractNote={Rapid increase in the power conversion efficiency of organic solar cells (OSCs) has been achieved with the development of non-fullerene small-molecule acceptors (NF-SMAs). Although the morphological stability of these NF-SMA devices critically affects their intrinsic lifetime, their fundamental intermolecular interactions and how they govern property-function relations and morphological stability of OSCs remain elusive. Here, we discover that the diffusion of an NF-SMA into the donor polymer exhibits Arrhenius behaviour and that the activation energy E a  scales linearly with the enthalpic interaction parameters χ H  between the polymer and the NF-SMA. Consequently, the thermodynamically most unstable, hypo-miscible systems (high χ) are the most kinetically stabilized. We relate the differences in E a  to measured and selectively simulated molecular self-interaction properties of the constituent materials and develop quantitative property-function relations that link thermal and mechanical characteristics of the NF-SMA and polymer to predict relative diffusion properties and thus morphological stability.}, number={4}, journal={NATURE MATERIALS}, author={Ghasemi, Masoud and Balar, Nrup and Peng, Zhengxing and Hu, Huawei and Qin, Yunpeng and Kim, Taesoo and Rech, Jeromy J. and Bidwell, Matthew and Mask, Walker and McCulloch, Iain and et al.}, year={2021}, month={Apr}, pages={525-+} }
 @article{chen_bai_peng_zhu_zhang_zou_qin_kim_yuan_ma_et al._2021, title={Asymmetric Alkoxy and Alkyl Substitution on Nonfullerene Acceptors Enabling High-Performance Organic Solar Cells}, volume={11}, ISSN={["1614-6840"]}, DOI={10.1002/aenm.202003141}, abstractNote={Abstract}, number={3}, journal={ADVANCED ENERGY MATERIALS}, author={Chen, Yuzhong and Bai, Fujin and Peng, Zhengxing and Zhu, Lei and Zhang, Jianquan and Zou, Xinhui and Qin, Yunpeng and Kim, Ha Kyung and Yuan, Jun and Ma, Lik-Kuen and et al.}, year={2021}, month={Jan} }
 @article{zheng_sun_zhang_chen_peng_wu_yuan_yu_wang_wu_et al._2021, title={Baseplate Temperature-Dependent Vertical Composition Gradient in Pseudo-Bilayer Films for Printing Non-Fullerene Organic Solar Cells}, volume={10}, ISSN={["1614-6840"]}, DOI={10.1002/aenm.202102135}, abstractNote={Abstract}, journal={ADVANCED ENERGY MATERIALS}, author={Zheng, Yina and Sun, Rui and Zhang, Meng and Chen, Zhihao and Peng, Zhengxing and Wu, Qiang and Yuan, Xinxin and Yu, Yue and Wang, Tao and Wu, Yao and et al.}, year={2021}, month={Oct} }
 @article{schopp_brus_lee_dixon_karki_liu_peng_graham_ade_bazan_et al._2021, title={Effect of Palladium-Tetrakis(Triphenylphosphine) Catalyst Traces on Charge Recombination and Extraction in Non-Fullerene-based Organic Solar Cells}, volume={31}, ISSN={["1616-3028"]}, DOI={10.1002/adfm.202009363}, abstractNote={Abstract}, number={15}, journal={ADVANCED FUNCTIONAL MATERIALS}, author={Schopp, Nora and Brus, Viktor V. and Lee, Jaewon and Dixon, Alana and Karki, Akchheta and Liu, Tuo and Peng, Zhengxing and Graham, Kenneth R. and Ade, Harald and Bazan, Guillermo C. and et al.}, year={2021}, month={Apr} }
 @article{du_mainville_vollbrecht_dixon_schopp_schrock_peng_huang_chae_ade_et al._2021, title={Insights into Bulk-Heterojunction Organic Solar Cells Processed from Green Solvent}, volume={5}, ISSN={["2367-198X"]}, url={https://doi.org/10.1002/solr.202100213}, DOI={10.1002/solr.202100213}, abstractNote={The environmental impact of solution processed organic solar cells (OSCs) can be mitigated by introducing so‐called green solvents during the fabrication processes. However, the effects of such green solvents on the molecular‐level structures and optoelectronic properties lack in‐depth characterization. Here, insights into the structure–processing–property correlation of a PPDT2FBT:PC61BM bulk‐heterojunction (BHJ) system processed from a green solvent, ortho‐xylene (o‐XY), is investigated in comparison with the same blend processed from a traditional halogenated solvent, chlorobenzene (CB). The BHJ blends are characterized with various techniques probing at difference length scales, and an increased donor:acceptor (D:A) interfacial area as well as well‐mixed features in the bulk morphologies of the active layer are observed for the o‐XY processed BHJ blend. Furthermore, molecular‐level differences in the D–A intermolecular interactions at the BHJ interfaces in o‐XY and CB cast films are elucidated by 2‐dimensional solid‐state nuclear magnetic resonance (ssNMR) measurements and analysis. These results are consistent with the device properties, suggesting that the green‐solvent‐processed devices have longer charge carrier lifetimes and faster charge carrier extraction. The optimized PPDT2FBT:PC61BM devices processed from o‐XY can achieve a noteworthy higher power conversion efficiency (PCE) owing to a higher short‐circuit current density and fill factor.}, journal={SOLAR RRL}, publisher={Wiley}, author={Du, Zhifang and Mainville, Mathieu and Vollbrecht, Joachim and Dixon, Alana L. and Schopp, Nora and Schrock, Max and Peng, Zhengxing and Huang, Jianfei and Chae, Sangmin and Ade, Harald and et al.}, year={2021}, month={Jun} }
 @article{jiang_zhang_peng_lin_wu_li_chen_yan_ade_zhu_et al._2021, title={Pseudo-bilayer architecture enables high-performance organic solar cells with enhanced exciton diffusion length}, volume={12}, ISSN={["2041-1723"]}, url={https://doi.org/10.1038/s41467-020-20791-z}, DOI={10.1038/s41467-020-20791-z}, abstractNote={Abstract}, number={1}, journal={NATURE COMMUNICATIONS}, publisher={Springer Science and Business Media LLC}, author={Jiang, Kui and Zhang, Jie and Peng, Zhengxing and Lin, Francis and Wu, Shengfan and Li, Zhen and Chen, Yuzhong and Yan, He and Ade, Harald and Zhu, Zonglong and et al.}, year={2021}, month={Jan} }
 @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 of semiconducting polymers is often critical to the performance of devices using these materials. The degree and quality of ordering are revealed by grazing-incidence wide-angle X-ray scattering and thermal analysis.}, 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{peng_balar_ghasemi_ade_2021, title={Upper and Apparent Lower Critical Solution Temperature Branches in the Phase Diagram of Polymer:Small Molecule Semiconducting Systems}, volume={12}, ISSN={["1948-7185"]}, DOI={10.1021/acs.jpclett.1c02848}, abstractNote={Solution-processable semiconducting materials are complex materials with a wide range of applications. Despite their extensive study and utility, their molecular interactions as manifested, for example, in phase behavior are poorly understood. Here, we aim to understand the phase behavior of conjugated systems by determining phase diagrams spanning extensive temperature ranges for various combinations of the highly disordered semiconducting polymer (PTB7-Th) with crystallizable (IT-M and PC61BM) and noncrystallizable (di-PDI) small molecule acceptors (SMAs), with polystyrene as an amorphous control, a nonsemiconducting commodity polymer. We discover that the apparent binodal of the studied blends frequently consists of an upper critical solution temperature (UCST) and lower critical solution temperature (LCST) branch, exhibiting a sharp kink where the branches join. Our work suggests that phase diagrams might be a probe in combination with sophisticated models to understand the complexity of semiconducting materials, including microstructure and molecular interactions.}, number={44}, journal={JOURNAL OF PHYSICAL CHEMISTRY LETTERS}, author={Peng, Zhengxing and Balar, Nrup and Ghasemi, Masoud and Ade, Harald}, year={2021}, month={Nov}, pages={10845–10853} }
 @article{li_guo_peng_qu_yan_ade_zhang_forrest_2020, title={Color-neutral, semitransparent organic photovoltaics for power window applications}, volume={117}, ISSN={["0027-8424"]}, DOI={10.1073/pnas.2007799117}, abstractNote={Significance}, number={35}, journal={PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA}, author={Li, Yongxi and Guo, Xia and Peng, Zhengxing and Qu, Boning and Yan, Hongping and Ade, Harald and Zhang, Maojie and Forrest, Stephen R.}, year={2020}, month={Sep}, pages={21147–21154} }
 @article{yi_peng_xu_seyitliyev_ho_danilov_kim_reynolds_amassian_gundogdu_et al._2020, title={Critical Role of Polymer Aggregation and Miscibility in Nonfullerene-Based Organic Photovoltaics}, volume={10}, ISSN={["1614-6840"]}, url={http://dx.doi.org/10.1002/aenm.201902430}, DOI={10.1002/aenm.201902430}, abstractNote={Abstract}, number={8}, journal={ADVANCED ENERGY MATERIALS}, author={Yi, Xueping and Peng, Zhengxing and Xu, Bing and Seyitliyev, Dovletgeldi and Ho, Carr Hoi Yi and Danilov, Evgeny O. and Kim, Taesoo and Reynolds, John R. and Amassian, Aram and Gundogdu, Kenan and et al.}, year={2020}, month={Feb} }
 @article{chai_chang_peng_jia_zou_yu_yu_chen_chow_wong_et al._2020, title={Enhanced hindrance from phenyl outer side chains on nonfullerene acceptor enables unprecedented simultaneous enhancement in organic solar cell performances with 16.7% efficiency}, volume={76}, ISSN={["2211-3282"]}, DOI={10.1016/j.nanoen.2020.105087}, abstractNote={Inner side-chain engineering on Y6 has been proven successful in improving short-circuit current density (JSC) through fine-tuning aggregated structures of acceptors. However, it fails in tuning the lowest unoccupied molecular orbital level (LUMO) and open-circuit voltage (VOC). In this paper, we turn to focus on engineering the outer side chains on the flanking thienothiophene units with 4-hexylphenyl (PhC6) and 6-phenylhexyl (C6Ph) chains. Use of PhC6 enhances the steric effect between the attached phenyl and the ending group, which in combination with the additional conjugation effect provided by the linking phenyl leads to upshifted energy levels and increased VOC as a result. Again, substitution with the bulkier PhC6 unprecedentedly improves film-morphology with reduced paracrystalline disorder and long period and increased root-mean-square composition variations as well, leading to increased electron and hole mobilities and suppressed monomolecular recombination with JSC and fill-factor (FF) simultaneously enhanced. The PM6:BTP-PhC6-based devices yield a higher efficiency value of 16.7% than the PM6:BTP-C6Ph-based one (15.5%). Therefore, this study shows a conceptual advance in materials design towards reducing the conflict between VOC and JSC in binary blended organic solar cells, which can be achieved by introducing bulkier chains to twist the backbone and simultaneously enhance the packing order.}, journal={NANO ENERGY}, author={Chai, Gaoda and Chang, Yuan and Peng, Zhengxing and Jia, Yanyan and Zou, Xinhui and Yu, Dian and Yu, Han and Chen, Yuzhong and Chow, Philip C. Y. and Wong, Kam Sing and et al.}, year={2020}, month={Oct} }
 @article{qin_xu_peng_hou_ade_2020, title={Low Temperature Aggregation Transitions in N3 and Y6 Acceptors Enable Double-Annealing Method That Yields Hierarchical Morphology and Superior Efficiency in Nonfullerene Organic Solar Cells}, volume={30}, ISSN={["1616-3028"]}, DOI={10.1002/adfm.202005011}, abstractNote={Abstract}, number={46}, journal={ADVANCED FUNCTIONAL MATERIALS}, author={Qin, Yunpeng and Xu, Ye and Peng, Zhengxing and Hou, Jianhui and Ade, Harald}, year={2020}, month={Nov} }
 @article{zhang_li_peng_bai_ma_ade_li_yan_2020, title={Near-infrared electron acceptors with fused nonacyclic molecular backbones for nonfullerene organic solar cells}, volume={4}, ISSN={["2052-1537"]}, DOI={10.1039/c9qm00754g}, abstractNote={Two strong electron-donating moieties were fused into the molecular backbone of small molecular acceptors showing dramatically extended absorption beyond 900 nm.}, number={6}, journal={MATERIALS CHEMISTRY FRONTIERS}, author={Zhang, Jianquan and Li, Yunke and Peng, Zhengxing and Bai, Fujin and Ma, Lik-Kuen and Ade, Harald and Li, Zhengke and Yan, He}, year={2020}, month={Jun}, pages={1729–1738} }
 @article{samson_rech_perdigon-toro_peng_shoaee_ade_neher_stolterfoht_you_2020, title={Organic Solar Cells with Large Insensitivity to Donor Polymer Molar Mass across All Acceptor Classes}, volume={2}, ISSN={["2637-6105"]}, DOI={10.1021/acsapm.0c01041}, abstractNote={Donor polymer number-average molar mass (Mn) has long been known to influence organic photovoltaic (OPV) performance via changes in both the polymer properties and the resulting bulk heterojunction...}, number={11}, journal={ACS APPLIED POLYMER MATERIALS}, author={Samson, Stephanie and Rech, Jeromy and Perdigon-Toro, Lorena and Peng, Zhengxing and Shoaee, Safa and Ade, Harald and Neher, Dieter and Stolterfoht, Martin and You, Wei}, year={2020}, month={Nov}, pages={5300–5308} }
 @article{liang_pan_chai_peng_zhang_luo_han_chen_shang_bai_et al._2020, title={Random Polymerization Strategy Leads to a Family of Donor Polymers Enabling Well-Controlled Morphology and Multiple Cases of High-Performance Organic Solar Cells}, volume={32}, ISSN={["1521-4095"]}, DOI={10.1002/adma.202003500}, abstractNote={Abstract}, number={52}, journal={ADVANCED MATERIALS}, author={Liang, Jiaen and Pan, Mingao and Chai, Gaoda and Peng, Zhengxing and Zhang, Jianquan and Luo, Siwei and Han, Qi and Chen, Yuzhong and Shang, Ao and Bai, Fujin and et al.}, year={2020}, month={Dec} }
 @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 ...}, 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{arunagiri_peng_zou_yu_zhang_wang_lai_zhang_zheng_cui_et al._2020, title={Selective Hole and Electron Transport in Efficient Quaternary Blend Organic Solar Cells}, volume={4}, ISSN={["2542-4351"]}, DOI={10.1016/j.joule.2020.06.014}, abstractNote={Multi-component organic solar cells (OSCs) comprising more than two donor and acceptor materials have attracted significant research attention, as they can offer broader and better absorption, hence increasing solar cell performance. However, the morphology of multi-component OSCs is exceptionally complicated and challenging to control. Here, we develop a highly efficient (near 17.7%) quaternary OSC (q-OSC) using two polymer donors (namely PM6 and PTQ10) along with a fullerene (PC71BM) and a non-fullerene acceptor (N3). Our quaternary system demonstrates a new type of “rivers and streams” functional hierarchical (multi-length scale) morphology, where small domains of PTQ10 and PC71BM act as separators that spatially separate PM6 and N3, which effectively suppressed charge recombination, enhanced hole transport, and balanced charge transportation. These improvements in the quaternary system contribute to the increased internal quantum efficiency (IQE) and, thus, lead to an excellent JSC and device performance, which surpass their respective binary and ternary OSCs.}, number={8}, journal={JOULE}, author={Arunagiri, Lingeswaran and Peng, Zhengxing and Zou, Xinhui and Yu, Han and Zhang, Guangye and Wang, Zhen and Lai, Joshua Yuk Lin and Zhang, Jianquan and Zheng, Yan and Cui, Chaohua and et al.}, year={2020}, month={Aug}, pages={1790–1805} }
 @article{hu_ghasemi_peng_zhang_rech_you_yan_ade_2020, title={The Role of Demixing and Crystallization Kinetics on the Stability of Non-Fullerene Organic Solar Cells}, volume={32}, ISSN={["1521-4095"]}, url={https://doi.org/10.1002/adma.202005348}, DOI={10.1002/adma.202005348}, abstractNote={Abstract}, number={49}, journal={ADVANCED MATERIALS}, publisher={Wiley}, author={Hu, Huawei and Ghasemi, Masoud and Peng, Zhengxing and Zhang, Jianquan and Rech, Jeromy James and You, Wei and Yan, He and Ade, Harald}, year={2020}, month={Dec} }
 @article{karki_vollbrecht_gillett_xiao_yang_peng_schopp_dixon_yoon_schrock_et al._2020, title={The role of bulk and interfacial morphology in charge generation, recombination, and extraction in non-fullerene acceptor organic solar cells}, volume={13}, ISSN={["1754-5706"]}, DOI={10.1039/d0ee01896a}, abstractNote={This study provides insight into the detailed bulk and interfacial morphological features critical in achieving high PCEs in polymer:NFA OSCs.}, number={10}, journal={ENERGY & ENVIRONMENTAL SCIENCE}, author={Karki, Akchheta and Vollbrecht, Joachim and Gillett, Alexander J. and Xiao, Steven Shuyong and Yang, Yali and Peng, Zhengxing and Schopp, Nora and Dixon, Alana L. and Yoon, Sangcheol and Schrock, Max and et al.}, year={2020}, month={Oct}, pages={3679–3692} }
 @article{wang_peng_xiao_seyitliyev_gundogdu_ding_ade_2020, title={Thermodynamic Properties and Molecular Packing Explain Performance and Processing Procedures of Three D18:NFA Organic Solar Cells}, volume={32}, ISSN={["1521-4095"]}, DOI={10.1002/adma.202005386}, abstractNote={Abstract}, number={49}, journal={ADVANCED MATERIALS}, author={Wang, Zhen and Peng, Zhengxing and Xiao, Zuo and Seyitliyev, Dovletgeldi and Gundogdu, Kenan and Ding, Liming and Ade, Harald}, year={2020}, month={Dec} }
 @article{karki_vollbrecht_gillett_selter_lee_peng_schopp_dixon_schrock_nadazdy_et al._2020, title={Unifying Charge Generation, Recombination, and Extraction in Low-Offset Non-Fullerene Acceptor Organic Solar Cells}, volume={10}, ISSN={["1614-6840"]}, DOI={10.1002/aenm.202001203}, abstractNote={Abstract}, number={29}, journal={ADVANCED ENERGY MATERIALS}, author={Karki, Akchheta and Vollbrecht, Joachim and Gillett, Alexander J. and Selter, Philipp and Lee, Jaewon and Peng, Zhengxing and Schopp, Nora and Dixon, Alana L. and Schrock, Max and Nadazdy, Vojtech and et al.}, year={2020}, month={Aug} }
 @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{ghasemi_hu_peng_rech_angunawela_carpenter_stuard_wadsworth_mcculloch_you_et al._2019, title={Delineation of Thermodynamic and Kinetic Factors that Control Stability in Non-fullerene Organic Solar Cells}, volume={3}, ISSN={["2542-4351"]}, DOI={10.1016/j.joule.2019.03.020}, abstractNote={Although non-fullerene small molecular acceptors (NF-SMAs) are dominating current research in organic solar cells (OSCs), measurements of thermodynamics drivers and kinetic factors determining their morphological stability are lacking. Here, we delineate and measure such factors in crystallizable NF-SMA blends and discuss four model systems with respect to their meta-stability and degree of vitrification. We determine for the first time the amorphous-amorphous phase diagram in an NF-SMA system and show that its deep quench depth can result in severe burn-in degradation. We estimate the relative phase behavior of four other materials systems. Additionally, we derive room-temperature diffusion coefficients and conclude that the morphology needs to be stabilized by vitrification corresponding to diffusion constants below 10−22 cm2/s. Our results show that to achieve stability via rational molecular design, the thermodynamics, glass transition temperature, diffusion properties, and related structure-function relations need to be more extensively studied and understood.}, number={5}, journal={JOULE}, author={Ghasemi, Masoud and Hu, Huawei and Peng, Zhengxing and Rech, Jeromy James and Angunawela, Indunil and Carpenter, Joshua H. and Stuard, Samuel J. and Wadsworth, Andrew and McCulloch, Iain and You, Wei and et al.}, year={2019}, month={May}, pages={1328–1348} }
 @article{zhang_rech_yan_liang_peng_ade_wu_you_2019, title={Effect of Cyano Substitution on Conjugated Polymers for Bulk Heterojunction Solar Cells}, volume={1}, ISSN={["2637-6105"]}, DOI={10.1021/acsapm.9b00767}, abstractNote={The design of polymer structures has played a vital role in improving the efficiency of organic solar cells (OSCs). A common approach to increase solar cell efficiency is to add a specific substitu...}, number={12}, journal={ACS APPLIED POLYMER MATERIALS}, author={Zhang, Qianqian and Rech, Jeromy James and Yan, Liang and Liang, Quanbin and Peng, Zhengxing and Ade, Harald and Wu, Hongbin and You, Wei}, year={2019}, month={Dec}, pages={3313–3322} }
 @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{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}, 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{bauer_zhang_rech_dai_peng_ade_wang_zhan_you_2019, title={The impact of fluorination on both donor polymer and non-fullerene acceptor: The more fluorine, the merrier}, volume={12}, ISSN={["1998-0000"]}, DOI={10.1007/s12274-019-2362-3}, number={9}, journal={NANO RESEARCH}, author={Bauer, Nicole and Zhang, Qianqian and Rech, Jeromy James and Dai, Shuixing and Peng, Zhengxing and Ade, Harald and Wang, Jiayu and Zhan, Xiaowei and You, Wei}, year={2019}, month={Sep}, pages={2400–2405} }
 @article{rech_yan_peng_dai_zhan_ade_you_2019, title={Utilizing Difluorinated Thiophene Units To Improve the Performance of Polymer Solar Cells}, volume={52}, ISSN={["1520-5835"]}, DOI={10.1021/acs.macromol.9b01168}, abstractNote={While there are numerous approaches to functionalize conjugated polymers for organic solar cells (OSCs), one widely adopted approach is fluorination. Of the many different locations for fluorinatio...}, number={17}, journal={MACROMOLECULES}, author={Rech, Jeromy J. and Yan, Liang and Peng, Zhengxing and Dai, Shuixing and Zhan, Xiaowei and Ade, Harald and You, Wei}, year={2019}, month={Sep}, pages={6523–6532} }
 @article{hu_li_zhang_peng_ma_xin_huang_ma_jiang_zhang_et al._2018, title={Effect of Ring-Fusion on Miscibility and Domain Purity: Key Factors Determining the Performance of PDI-Based Nonfullerene Organic Solar Cells}, volume={8}, ISSN={["1614-6840"]}, DOI={10.1002/aenm.201800234}, abstractNote={Abstract}, number={26}, journal={ADVANCED ENERGY MATERIALS}, author={Hu, Huawei and Li, Yunke and Zhang, Jianquan and Peng, Zhengxing and Ma, Lik-kuen and Xin, Jingming and Huang, Jiachen and Ma, Tingxuan and Jiang, Kui and Zhang, Guangye and et al.}, year={2018}, month={Sep} }
 @article{huang_bin_peng_qiu_sun_liebman-pelaez_zhang_zhu_ade_zhang_et al._2018, title={Effect of Side-Chain Engineering of Bithienylbenzodithiophene-alt-fluorobenzotriazole-Based Copolymers on the Thermal Stability and Photovoltaic Performance of Polymer Solar Cells}, volume={51}, ISSN={["1520-5835"]}, DOI={10.1021/acs.macromol.8b01036}, abstractNote={Side-chain engineering of conjugated polymer donor materials is an important way for improving photovoltaic performances of polymer solar cells (PSCs). On the basis of the polymer J61 synthesized in our group, here, we design and synthesize three new 2D-conjugated polymers J62, J63, and J64 with different types of side chains to further investigate the effect of side chain on their physicochemical and photovoltaic properties. With the narrow bandgap n-type organic semiconductor (n-OS) ITIC as acceptor, the optimized PSCs based on polymer donor of J62 with linear octyl, J63 with linear unsaturated hexylene, and J64 with cyclohexane side chains display power conversion efficiency (PCE) of 10.81%, 8.13%, and 8.59%, respectively. After thermal treatment at 200 °C for 2 h on the active layer,the PCE of the PSC based on J63 still keeps 92% of the original value, which verifies that the cross-linking of the polymer can improve the thermal stability of PSCs. Morphological studies show that the active layer based ...}, number={15}, journal={MACROMOLECULES}, author={Huang, He and Bin, Haijun and Peng, Zhengxing and Qiu, Beibei and Sun, Chenkai and Liebman-Pelaez, Alex and Zhang, Zhi-Guo and Zhu, Chenhui and Ade, Harald and Zhang, Zhanjun and et al.}, year={2018}, month={Aug}, pages={6028–6036} }
 @article{li_huang_peng_sun_yang_zhou_liebman-pelaez_zhu_zhang_zhang_et al._2018, title={Effects of fused-ring regiochemistry on the properties and photovoltaic performance of n-type organic semiconductor acceptors}, volume={6}, ISSN={["2050-7496"]}, DOI={10.1039/c8ta05920a}, abstractNote={The effects of fused-ring regiochemistry on the physicochemical and photovoltaic properties of n-type organic semiconductor (n-OS) acceptors are investigated.}, number={33}, journal={JOURNAL OF MATERIALS CHEMISTRY A}, author={Li, Xiaojun and Huang, He and Peng, Zhengxing and Sun, Chenkai and Yang, Dengchen and Zhou, Jiadong and Liebman-Pelaez, Alex and Zhu, Chenhui and Zhang, Zhi-Guo and Zhang, Zhanjun and et al.}, year={2018}, month={Sep}, pages={15933–15941} }
 @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 tec...}, 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{kelly_zhang_peng_noman_zhu_ade_you_2018, title={The finale of a trilogy: comparing terpolymers and ternary blends with structurally similar backbones for use in organic bulk heterojunction solar cells}, volume={6}, ISSN={["2050-7496"]}, DOI={10.1039/c8ta05132a}, abstractNote={Comparing the efficiency of terpolymers vs. ternary blends, this study focuses on two polymers with structurally similar backbones (monoCNTAZ and FTAZ) yet markedly different open circuit voltages.}, number={39}, journal={JOURNAL OF MATERIALS CHEMISTRY A}, author={Kelly, Mary Allison and Zhang, Qianqian and Peng, Zhengxing and Noman, Victoria and Zhu, Chenhui and Ade, Harald and You, Wei}, year={2018}, month={Oct}, pages={19190–19200} }
 @article{bauer_zhang_zhu_peng_yan_zhu_ade_zhan_you_2017, title={Donor polymer fluorination doubles the efficiency in non-fullerene organic photovoltaics}, volume={5}, ISSN={["2050-7496"]}, DOI={10.1039/c7ta07882j}, abstractNote={Donor polymer fluorination in ITIC-based device led to a large increase in the current and an efficiency twice that of the non-fluorinated polymer based device.}, number={43}, journal={JOURNAL OF MATERIALS CHEMISTRY A}, author={Bauer, Nicole and Zhang, Qianqian and Zhu, Jingshuai and Peng, Zhengxing and Yan, Long and Zhu, Chenhui and Ade, Harald and Zhan, Xiaowei and You, Wei}, year={2017}, month={Nov}, pages={22536–22541} }
 @article{zhang_yan_jiao_peng_liu_rech_klump_ade_so_you_2017, title={Fluorinated Thiophene Units Improve Photovoltaic Device Performance of Donor–Acceptor Copolymers}, volume={29}, ISSN={0897-4756 1520-5002}, url={http://dx.doi.org/10.1021/ACS.CHEMMATER.7B01683}, DOI={10.1021/acs.chemmater.7b01683}, abstractNote={Fluorinated conjugated polymers leading to enhanced photovoltaic device performance has been widely observed in a variety of donor–acceptor copolymers; however, almost all these polymers have fluorine substituents on the acceptor unit. Building upon our previously reported PBnDT-FTAZ, a fluorinated donor–acceptor conjugated polymer with impressive device performance, we set this study to explore the effect of adding the fluorine substituents onto the flanking thiophene units between the donor unit (BnDT) and the acceptor unit (TAZ). We developed new synthetic approaches to control the position of the fluorination (3′ or 4′) on the thiophene unit, and synthesized four additional PBnDT-TAZ polymers incorporating the fluorine-substituted-thiophene (FT) units, 3′-FT-HTAZ, 4′-FT-HTAZ, 3′-FT-FTAZ, and 4′-FT-FTAZ. We discover that relocating the fluorine substituents from the acceptor to the flanking thiophene units have a negligible impact on the device characteristics (short circuit current, open circuit volta...}, number={14}, journal={Chemistry of Materials}, publisher={American Chemical Society (ACS)}, author={Zhang, Qianqian and Yan, Liang and Jiao, Xuechen and Peng, Zhengxing and Liu, Shubin and Rech, Jeromy James and Klump, Erik and Ade, Harald and So, Franky and You, Wei}, year={2017}, month={Jul}, pages={5990–6002} }
 @article{li_huang_bin_peng_zhu_xue_zhang_zhang_ade_li_2017, title={Synthesis and Photovoltaic Properties of a Series of Narrow Bandgap Organic Semiconductor Acceptors with Their Absorption Edge Reaching 900 nm}, volume={29}, ISSN={["1520-5002"]}, DOI={10.1021/acs.chemmater.7b03928}, abstractNote={Three n-OS acceptors with Eg values of <1.4 eV were synthesized by introducing double-bond π-bridges into ITIC (ITVIC) and ITIC with monofluorine (ITVfIC) or bifluorine (ITVffIC) substituents on its end groups, and the structure–property relationships of the acceptors were systematically studied. The three n-OS films show broad absorption covering the wavelength range of 550–900 nm with narrow Eg values of 1.40 eV for ITVIC, 1.37 eV for ITVfIC, and 1.35 eV for ITVffIC. Additionally, the fluorine substitution downshifted the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of the compounds. The photovoltaic properties of the n-OS acceptors were investigated by using a medium bandgap conjugated polymer J71 as a donor. The optimized polymer solar cells (PSCs) based on J71:ITVffIC demonstrated a power conversion efficiency (PCE) of 10.54% with a high Jsc of 20.60 mA cm–2 and a Voc of 0.81 V, and the highest Jsc reached 22.83 mA cm–2. The high Jsc values of...}, number={23}, journal={CHEMISTRY OF MATERIALS}, author={Li, Xiaojun and Huang, He and Bin, Haijun and Peng, Zhengxing and Zhu, Chenhui and Xue, Lingwei and Zhang, Zhi-Guo and Zhang, Zhanjun and Ade, Harald and Li, Yongfang}, year={2017}, month={Dec}, pages={10130–10138} }