219. "Utilization of Trapped Optical Modes for White Perovskite Light-Emitting Diodes with Efficiency over 12%"

Ziming Chen, Zhenchao Li, Zhen Chen, Ruoxi Xia, Guangruixing Zou, Linghao Chu, Shi-Jian Su, Junbiao Peng, Hin-Lap Yip, Yong Cao

Joule.,  2021, DOI:https://doi.org/10.1016/j.joule.2020.12.008

The inferior light extraction efficiency (LEE), which is generally less than 20%, based on optical modeling, and the difficulty in achieving white emission are the two main challenges in the metal-halide-perovskite light-emitting diode (PeLED) field. Herein, we report a simple and efficient approach to construct high-performance white PeLEDs with much-enhanced LEE by coupling a blue PeLED with a layer of red perovskite nanocrystal (PeNC) down-converter through a rationally designed multilayer semitransparent electrode (LiF/Al/Ag/LiF). The red PeNC layer allows the extraction of the trapped waveguide mode and surface plasmon polariton mode in a blue PeLED and converts them to red emission, resulting in over 50% LEE improvement. Simultaneously, the complementary emission spectrum of blue photons and down-converting red photons contributes to a white PeLED with a high external quantum efficiency and luminance of more than 12% and approximately 2,000 cd m −2, respectively, which represent state-of-the-art results in this field.

218. "D-A-π-A-D-type Dopant-free Hole Transport Material for Low-Cost, Efficient, and Stable Perovskite Solar Cells"

Tianqi Niu, Weiya Zhu, Yiheng Zhang, Qifan Xue, Xuechen Jiao, Zijie Wang, Yue-Min Xie, Ping Li, Runfeng Chen, Fei Huang, Yuan Li, Hin-Lap Yip, Yong Cao

Joule.,  2021, DOI:https://doi.org/10.1016/j.joule.2020.12.003

The development of low-cost and efficient hole transport materials (HTMs) is important for the commercialization of perovskite solar cells (PSCs). Comparing with the widely studied D-A-D and D-π-D linear-type small molecule HTMs, DTB-FL with a D-A-π-A-D molecular design is proposed, featuring facile synthesis and excellent optoelectronic properties. Moreover, the HTM with efficient surface passivation effects and proper energy level alignment at the hole extraction interface effectively inhibits recombination loss and improves the charge collection property. As a result, the champion efficiencies of 21.5% and 19.6% for active areas of 0.09 and 1.0 cm 2, respectively, with superior operational stability are achieved by using DTB-FL HTM. In addition, DTB-FL can also be used as efficient HTM for all-inorganic PSCs, producing an impressive PCE of 17.0% with a high V oc of 1.30 V. These results underscore the promising potential of the D-A-π-A-D molecular design in preparing low-cost dopant-free HTMs toward stable and efficient PSCs.

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