Carbazole‐Containing Polymer‐Assisted Trap Passivation and Hole‐Injection Promotion for Efficient and Stable CsCu<sub>2</sub>I<sub>3</sub>‐Based Yellow LEDs
Zhuangzhuang Ma, Xinzhen Ji, Meng Wang, Fei Zhang, Zibin Liu, Dongwen Yang, Mochen Jia, Xu Chen, Di Wu, Yù Zhang, Xinjian Li, Zhifeng Shi, Chongxin Shan
Abstract
Abstract Perovskite light‐emitting diodes (LEDs) are emerging light sources for next‐generation lighting and display technologies; however, their development is greatly plagued by difficulty in achieving yellow electroluminescence, environmental instability, and lead toxicity. Copper halide CsCu 2 I 3 with intrinsic yellow emission emerges as a highly promising candidate for eco‐friendly LEDs, but the electroluminescent performance is limited by defect‐related nonradiative losses and inefficient charge transport/injection. To solve these issues, a hole‐transporting poly(9‐vinlycarbazole) (PVK)‐incorporated engineering into CsCu 2 I 3 emitter is proposed. PVK with carbazole groups is permeated at the grain boundaries of CsCu 2 I 3 films by interacting with the uncoordinated Cu + , reducing the Cu Cs and Cu I antisite defects to increase the radiative recombination and enhancing the hole mobility to balance the charge transport/injection, resulting in substantially enhanced device performances. Eventually, the yellow LEDs exhibit an 8.5‐fold enhancement of external quantum efficiency, and the half‐lifetime reaches 14.6 h, representing the most stable yellow LEDs based on perovskite systems reported so far.