Defect Passivation Efficacy of 2D Perovskite Interlayer for Perovskite Sky‐Blue Emission Toward High Device Efficiency.

The deviated crystallization kinetics of solution‐processed perovskite layers caused by the bottom interface is a barrier to comprehensively suppressing the defect formation and further to efficaciously improve the film quality and device performance. Herein, it is reported that the incorporation of a PEA2PbBr4 interlayer can effectively modify the crystallization process of the quasi‐2D mixed‐halide perovskite layers, resulting in enhanced Lewis acid‐base interaction and improved film homogeneity, which contributes to the strong defect passivation efficacy toward efficient sky‐blue emission. As a result, the devices with the bottom‐interface modification show a maximum external quantum efficiency of 14.2%, impressively an outstanding power efficiency of 17.0 lm W−1, and an external quantum efficiency of 12.3% at 1000 cd m−2. This work provides an insight into crystallization kinetics for defect suppression of the perovskite layer and further highlights the defect passivation efficacy of 2D perovskite‐based bottom‐interface modification toward high‐efficiency sky blue‐emitting diodes. [ABSTRACT FROM AUTHOR]