P‐106: Highly Luminescent Blue Light‐Emitting Diodes Based on Quasi‐2D Multi‐Cation Perovskites

Quasi‐2D perovskites, typically with a standard formula of L2An‐1MnX3n+1, have recently attracted significant attention due to their promising optoelectronic properties. Normally, they contain a mono cation (e.g., butylammonium (BA+) or phenylethylammonium (PEA+) for “L” and methylammonium (MA+) or formamidinium (FA+) for “A”). In this work, multiple cation‐substitution strategy was used to improve the luminescence and emission efficiency of perovskite thin films. As a result, a smooth, compact surface morphology of blue emission perovskite thin films was achieved, with a high photoluminescence quantum yield of 53%. Finally, the corresponding perovskite light‐emitting diodes (PeLEDs) reaches a brightness of 220 cd/m2, and a maximum external quantum efficiency of 0.83%.