@article{dong_zhu_yin_lei_gundogdu_so_2023, title={High-Efficiency Linearly Polarized Organic Light-Emitting Diodes}, volume={10}, ISSN={["2330-4022"]}, DOI={10.1021/acsphotonics.3c00812}, abstractNote={Thin-film light-emitting diodes (LEDs) with linearly polarized emission enable advanced photonic applications. Here, we demonstrate a linearly polarized light emission organic LED by utilizing the intrinsic polarization nature of the transverse electric (TE) waveguide mode present in the device and extracting it using a linear grating. With a device having 67.6% of the light trapped in the TE waveguide mode, we demonstrated a linearly polarized organic LED with a high current efficiency (CE) of 136 cd/A and a large polarization ratio above 30. Our analysis indicates that the CE can further be increased at least by 2-fold to 280 cd/A. Our device architecture can easily be adopted for other thin-film LED platforms for photonic applications.}, number={9}, journal={ACS PHOTONICS}, author={Dong, Qi and Zhu, Liping and Yin, Shichen and Lei, Lei and Gundogdu, Kenan and So, Franky}, year={2023}, month={Sep}, pages={3342–3349} }
 @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{worku_ben-akacha_sridhar_frick_yin_he_robb_chaaban_liu_winfred_et al._2021, title={Band Edge Control of Quasi-2D Metal Halide Perovskites for Blue Light-Emitting Diodes with Enhanced Performance}, volume={8}, ISSN={["1616-3028"]}, DOI={10.1002/adfm.202103299}, abstractNote={Abstract}, journal={ADVANCED FUNCTIONAL MATERIALS}, author={Worku, Michael and Ben-Akacha, Azza and Sridhar, Samanvitha and Frick, Jordan R. and Yin, Shichen and He, Qingquan and Robb, Alex J. and Chaaban, Maya and Liu, He and Winfred, J. S. Raaj Vellore and et al.}, year={2021}, month={Aug} }
 @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{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{dong_liu_barange_lee_pardue_yi_yin_so_2019, title={Long-Wavelength Lead Sulfide Quantum Dots Sensing up to 2600 nm for Short-Wavelength Infrared Photodetectors}, volume={11}, ISSN={["1944-8252"]}, DOI={10.1021/acsami.9b16539}, abstractNote={Lead sulfide nanoparticles (PbS NPs) are used in the short wavelength infrared (SWIR) photodetectors because of their excellent photosensitivity, bandgap tunability, and solution processability. It has been a challenge to synthesize high quality PbS NPs with an absorption peak beyond 2000 nm. In this work, using PbS seed crystals with an absorption peak at 1960 nm, we report a successful synthesis of very large mono-dispersed PbS NPs having a diameter up to 16 nm by multiple injections. The resulting NPs have an absorption peak over 2500 nm with a small full-width-at-half-maximum (FWHM) of 24 meV. To demonstrate the applications of such large QDs, broadband heterojunction photodetectors are fabricated with the large PbS QDs of an absorption peak at 2100 nm. The resulting devices have an EQE of 25% (over 50% IQE) at 2100 nm corresponding to a responsivity of 0.385 A/W, and an EQE ~60% in the visible range.}, number={47}, journal={ACS APPLIED MATERIALS & INTERFACES}, author={Dong, Chen and Liu, Shuyi and Barange, Nilesh and Lee, Jaewoong and Pardue, Tyler and Yi, Xueping and Yin, Shichen and So, Franky}, year={2019}, month={Nov}, pages={44451–44457} }