@article{dong_fu_seyitliyev_darabi_mendes_lei_chen_chang_amassian_gundogdu_et al._2022, title={Cavity Engineering of Perovskite Distributed Feedback Lasers}, volume={9}, ISSN={2330-4022 2330-4022}, url={http://dx.doi.org/10.1021/acsphotonics.2c00917}, DOI={10.1021/acsphotonics.2c00917}, number={9}, journal={ACS Photonics}, publisher={American Chemical Society (ACS)}, author={Dong, Qi and Fu, Xiangyu and Seyitliyev, Dovletgeldi and Darabi, Kasra and Mendes, Juliana and Lei, Lei and Chen, Yi-An and Chang, Chih-Hao and Amassian, Aram and Gundogdu, Kenan and et al.}, year={2022}, month={Aug}, pages={3124–3133} }
 @article{amoah_fu_yin_dong_dong_so_2022, title={Curved Mirror Arrays for Light Extraction in Top-Emitting Organic Light-Emitting Diodes}, volume={2}, ISSN={["1944-8252"]}, DOI={10.1021/acsami.1c21128}, abstractNote={The light outcoupling efficiency of a top-emitting organic light-emitting diode (OLED) is only about 20%, and the majority of the light is trapped in the waveguide modes and surface plasmon polariton (SPP) modes. Extracting the trapped modes can reduce the device power consumption and improve the operating lifetime. In this study, we demonstrate a top-emitting OLED structure with a dielectric spacer to suppress the SPP mode and with a patterned back mirror to extract the waveguide modes. We examine and compare several curved mirror arrays and conclude that a micromirror array (μMA) can efficiently extract the waveguide modes while minimizing the absorption loss. The optimized μMA device with a semi-transparent top electrode shows a 36% external quantum efficiency, 2 times higher than the referenced device. This optical design can be easily incorporated into a top-emitting device and has a great potential for displays and lighting applications.}, journal={ACS APPLIED MATERIALS & INTERFACES}, author={Amoah, Stephen and Fu, Xiangyu and Yin, Shichen and Dong, Qi and Dong, Chen and So, Franky}, year={2022}, month={Feb}, pages={9377–9385} }
 @article{yin_ho_ding_fu_zhu_gullett_dong_so_2022, title={Enhanced Surface Passivation of Lead Sulfide Quantum Dots for Short-Wavelength Photodetectors}, volume={34}, ISSN={["1520-5002"]}, DOI={10.1021/acs.chemmater.2c00293}, abstractNote={Lead sulfide (PbS) quantum dots are promising solution-processed materials for short-wave infrared (SWIR) photodetectors due to their tunable band gap and solution processability. Phase-transfer ligand exchange is a common method to prepare quantum dot (QD) inks used in device fabrication. For large-sized PbS QDs used for SWIR detection, the conventional phase-transfer ligand exchange has been problematic due to the densely packed organic ligands and charge-neutral (100) facets. Here, we report a new strategy to carry out the efficient phase-transfer ligand exchange in large-sized QDs. Specifically, using lead acetate trihydrate (PbAc2·3H2O) as a precursor and methylammonium acetate (MAAc) as an additive in the ligand solution, we can facilitate the efficient phase-transfer ligand exchange and epitaxial growth of perovskite intermediate (MAPbI3–xAcx) on the (100) facets, resulting in a significant improvement in film quality suitable for device fabrication. The resulting photodiodes show a 2.5× enhancement in external quantum efficiency (EQE) compared to devices using QD inks obtained using the conventional method. Considering the low transmittance of the ITO electrode in the SWIR regime, our devices exhibit an internal quantum efficiency of over 90%.}, number={12}, journal={CHEMISTRY OF MATERIALS}, author={Yin, Shichen and Ho, Carr Hoi Yi and Ding, Shuo and Fu, Xiangyu and Zhu, Liping and Gullett, Julian and Dong, Chen and So, Franky}, year={2022}, month={Jun}, pages={5433–5442} }
 @article{fu_mehta_chen_lei_zhu_barange_dong_yin_mendes_he_et al._2021, title={Directional Polarized Light Emission from Thin‐Film Light‐Emitting Diodes}, volume={33}, ISSN={0935-9648 1521-4095}, url={http://dx.doi.org/10.1002/adma.202006801}, DOI={10.1002/adma.202006801}, abstractNote={Abstract}, number={9}, journal={Advanced Materials}, publisher={Wiley}, author={Fu, Xiangyu and Mehta, Yash and Chen, Yi‐An and Lei, Lei and Zhu, Liping and Barange, Nilesh and Dong, Qi and Yin, Shichen and Mendes, Juliana and He, Siliang and et al.}, year={2021}, month={Jan}, pages={2006801} }
 @article{ho_kothari_fu_so_2021, title={Interconnecting layers for tandem organic solar cells}, volume={21}, ISSN={["2468-6069"]}, DOI={10.1016/j.mtener.Y021.100707}, journal={MATERIALS TODAY ENERGY}, author={Ho, C. H. Y. and Kothari, J. and Fu, X. and So, F.}, year={2021}, month={Sep} }
 @article{fu_yin_chen_zhu_dong_chang_so_2021, title={Light extraction in tandem organic light emitting diodes}, volume={119}, ISSN={["1077-3118"]}, url={https://doi.org/10.1063/5.0057325}, DOI={10.1063/5.0057325}, abstractNote={Since the invention of organic light emitting diodes (OLEDs), great research efforts have been dedicated to improving their efficiency and lifetime. For high-brightness applications, tandem OLED structures have advantages because of the lower current densities required to achieve high brightness. With the successful development of highly efficient charge generation layers, high brightness tandem OLEDs are used in displays and lighting. However, the major challenge for tandem OLEDs is the low light extraction efficiency, because about 50% of the light is trapped inside the device as waveguide modes. In this Perspective, we first review the recent works done on light extraction, analyze different waveguide mode extraction structures, and then identify the key factors determining the extraction efficiencies in tandem OLEDs.}, number={6}, journal={APPLIED PHYSICS LETTERS}, author={Fu, Xiangyu and Yin, Shichen and Chen, Yi-An and Zhu, Liping and Dong, Qi and Chang, Chih-Hao and So, Franky}, year={2021}, month={Aug} }
 @article{lei_seyitliyev_stuard_mendes_dong_fu_chen_he_yi_zhu_et al._2020, title={Efficient Energy Funneling in Quasi-2D Perovskites: From Light Emission to Lasing}, volume={32}, ISSN={["1521-4095"]}, DOI={10.1002/adma.201906571}, abstractNote={Abstract}, number={16}, journal={ADVANCED MATERIALS}, author={Lei, Lei and Seyitliyev, Dovletgeldi and Stuard, Samuel and Mendes, Juliana and Dong, Qi and Fu, Xiangyu and Chen, Yi-An and He, Siliang and Yi, Xueping and Zhu, Liping and et al.}, year={2020}, month={Apr} }
 @article{fu_peng_samal_barange_chen_shin_mehta_rozelle_chang_so_2020, title={Mode Dispersion in Photonic Crystal Organic Light-Emitting Diodes}, volume={2}, ISSN={["2637-6113"]}, DOI={10.1021/acsaelm.0c00326}, abstractNote={Similar to an electronic lattice determining the motion of electrons in solids, photonic crystals (PhCs) are periodic photonic nanostructures which determine the propagation of photons. By incorpor...}, number={6}, journal={ACS APPLIED ELECTRONIC MATERIALS}, author={Fu, Xiangyu and Peng, Cheng and Samal, Monica and Barange, Nilesh and Chen, Yi-An and Shin, Dong-Hun and Mehta, Yash and Rozelle, Adam and Chang, Chih-Hao and So, Franky}, year={2020}, month={Jun}, pages={1759–1767} }
 @article{dong_fu_cao_amoah_gundogdu_li_so_2020, title={Multi-mode Organic Light-Emitting Diode to Suppress the Viewing Angle Dependence}, volume={12}, ISSN={["1944-8252"]}, DOI={10.1021/acsami.0c05825}, abstractNote={A typical top emitting OLED has a strong microcavity effect because of the two reflective electrodes. The cavity effect causes a serious color shift with the viewing angles and restricts the organic layer thickness. To overcome these drawbacks, we designed a multi-mode OLED structure having dual-dielectric spacer layers, which extend the cavity length by more than 10 times. This design completely eliminates the intrinsic cavity effect caused by the top and bottom boundaries respectively and provides freedom for the organic layer thickness. We demonstrate these effects in a white multi-mode OLED using a white emitter, which shows a negligible angular chromaticity shift of 0.006 from 0° to 70° and a Lambertian emission profile. The simple design and the perfect angular color profiles make the multi-mode OLED structure promising in large-area displays and solid-state lighting applications.}, number={28}, journal={ACS APPLIED MATERIALS & INTERFACES}, author={Dong, Chen and Fu, Xiangyu and Cao, Linyu and Amoah, Stephen and Gundogdu, Kenan and Li, Jian and So, Franky}, year={2020}, month={Jul}, pages={31667–31676} }
 @article{fu_chen_shin_mehta_chen_barange_zhu_amoah_chang_so_2020, title={Recovering cavity effects in corrugated organic light emitting diodes}, volume={28}, ISSN={["1094-4087"]}, DOI={10.1364/OE.404412}, abstractNote={Cavity effects play an important role in determining the out-coupling efficiency of an OLED. By fabricating OLEDs on corrugated substrates, the waveguide and SPP modes can be extracted by diffraction. However, corrugation does not always lead to an enhancement in out-coupling efficiency due to the reduction of the electrode reflectance and hence the cavity effects. Based on the results of our rigorous couple-wave analysis (RCWA) simulation, we found that the cavity effects can be partially recovered using a low index Teflon layer inserted between the ITO anode and the substrate due to the enhancement of the reflectance of the corrugated electrodes. To verify the simulation results, we fabricated corrugated OLEDs having a low-index Teflon interlayer with an EQE of 36%, which is 29% higher than an optimized planar OLED. By experimentally measuring the OLED air mode dispersion, we confirm the cavity emission of a corrugated OLED is enhanced by the low index layer.}, number={21}, journal={OPTICS EXPRESS}, author={Fu, Xiangyu and Chen, Yi-An and Shin, Dong-Hun and Mehta, Yash and Chen, I-Te and Barange, Nilesh and Zhu, Liping and Amoah, Stephen and Chang, Chih-Hao and So, Franky}, year={2020}, month={Oct}, pages={32214–32225} }
 @article{dong_fu_amoah_rozelle_shin_salehi_mendes_so_2019, title={Eliminate angular color shift in top-emitting OLEDs through cavity design}, volume={27}, ISSN={["1938-3657"]}, DOI={10.1002/jsid.792}, abstractNote={Abstract}, number={8}, journal={JOURNAL OF THE SOCIETY FOR INFORMATION DISPLAY}, author={Dong, Chen and Fu, Xiangyu and Amoah, Stephen and Rozelle, Adam and Shin, Dong-Hun and Salehi, Amin and Mendes, Juliana and So, Franky}, year={2019}, month={Aug}, pages={469–479} }
 @misc{salehi_fu_shin_so_2019, title={Recent Advances in OLED Optical Design}, volume={29}, ISSN={["1616-3028"]}, DOI={10.1002/adfm.201808803}, abstractNote={Abstract}, number={15}, journal={ADVANCED FUNCTIONAL MATERIALS}, author={Salehi, Amin and Fu, Xiangyu and Shin, Dong-Hun and So, Franky}, year={2019}, month={Apr} }
 @article{peng_liu_fu_pan_chen_so_schanze_2016, title={Corrugated Organic Light Emitting Diodes Using Low T-g Electron Transporting Materials}, volume={8}, ISSN={["1944-8244"]}, DOI={10.1021/acsami.6b02669}, abstractNote={A corrugated organic light emitting diode (OLED) with enhanced light extraction is realized by incorporating a corrugated composite electron transport layer (ETL) consisting of two ETLs with different glass transition temperatures. The morphology of the corrugated structure is characterized with atomic force microscopy. The results show that the corrugation can be controlled by the layer thicknesses and annealing temperature. Compared with the control planar device, the corrugated OLED shows a more than 35% enhancement in current efficiency from 31 cd/A to 43 cd/A and a 20% enhancement in external quantum efficiency from 10% to 12% at 100 cd/m(2). In addition, the corrugated OLED also has a greatly improved operational stability. The LT90 lifetime of a device operated at 1000 cd/m(2) is improved greater than 100-fold in the corrugated OLED.}, number={25}, journal={ACS APPLIED MATERIALS & INTERFACES}, author={Peng, Cheng and Liu, Shuyi and Fu, Xiangyu and Pan, Zhenxing and Chen, Ying and So, Franky and Schanze, Kirk S.}, year={2016}, month={Jun}, pages={16192–16199} }