Metal halide perovskites have received considerable attention in the field of electroluminescence, and the external quantum efficiency of perovskite light-emitting diodes has exceeded 20%. CH 3 NH 3 PbBr 3 has been intensely investigated as an emitting layer in perovskite light-emitting diodes. However, perovskite films comprising CH 3 NH 3 PbBr 3 often exhibit low surface coverage and poor crystallinity, leading to high current leakage, severe nonradiative recombination, and limited device performance. Herein, we demonstrate a rationale for composition engineering to obtain high-quality perovskite films. We first reduce pinholes by adding excess CH 3 NH 3 Br to the actual CH 3 NH 3 PbBr 3 films, and we then add CsBr to improve the crystalline quality and to passivate nonradiative defects. As a result, the (CH 3 NH 3 ) 1− x Cs x PbBr 3 based perovskite light-emitting diodes exhibit significantly improved external quantum and power efficiencies of 6.97% and 25.18 lm/W, respectively, representing an improvement in performance dozens of times greater than that of pristine CH 3 NH 3 PbBr 3 -based perovskite light-emitting diodes. Our study demonstrates that composition engineering is an effective strategy for enhancing the device performance of perovskite light-emitting diodes.
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Yan et al. (2020) studied this question.