Hybrid Perovskite Light‐Emitting Diodes Based on Perovskite Nanocrystals with Organic–Inorganic Mixed Cations

Organic–inorganic hybrid perovskite materials with mixed cations have demonstrated tremendous advances in photovoltaics recently, by showing a significant enhancement of power conversion efficiency and improved perovskite stability. Inspired by this development, this study presents the facile synthesis of mixed-cation perovskite nanocrystals based on FA(1−x)CsxPbBr3 (FA = CH(NH2)2). By detailed characterization of their morphological, optical, and physicochemical properties, it is found that the emission property of the perovskite, FA(1−x)CsxPbBr3, is significantly dependent on the substitution content of the Cs cations in the perovskite composition. These mixed-cation perovskites are employed as light emitters in light-emitting diodes (LEDs). With an optimized composition of FA0.8Cs0.2PbBr3, the LEDs exhibit encouraging performance with a highest reported luminance of 55 005 cd m−2 and a current efficiency of 10.09 cd A−1. This work provides important instructions on the future compositional optimization of mixed-cation perovskite for obtaining high-performance LEDs. The authors believe this work is a new milestone in the development of bright and efficient perovskite LEDs.