Multi-Cation Blue Perovskites Light-Emitting Diodes with Enhanced Luminescence

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, brightly blue emission with a high photoluminescence quantum yield of 26% was achieved. Finally, the according perovskite light-emitting diodes reached a brightness of 110 cd/m2, and a maximum external quantum efficiency of 0.79%.