Manipulating Electron‐Phonon Coupling for Efficient Tin Halide Perovskite Blue LEDs

Abstract Low‐dimensional perovskites have opened up a new frontier in light‐emitting diodes (LED) due to their excellent properties. However, concerns regarding the potential toxicity of Pb limited their commercial development. Sn‐based perovskites are regarded as a promising candidate to replace Pb‐based counterparts, while they generally exhibit strong electron–phonon coupling and consequently blue emission quenching at room temperature (RT), thus the Sn‐based perovskite blue LED devices have not yet been reported. Herein, the luminescence properties are regulated by assembling a rigid organic skeleton within perovskite structure, and the protonated 4‐bromobenzylamine (BrPMA + = C 7 H 9 BrN + ) is employed as A site cation to synthesize a 100‐oriented 2D perovskite (BrPMA) 2 SnBr 4 , which exhibits a strong lattice rigidity via strong intermolecular interaction and consequently weak electron–phonon coupling, achieving the excellent blue PL emission at RT. The high quality (BrPMA) 2 SnBr 4 perovskite thin films are obtained by further inhibiting oxidation and promoting crystallization. Finally, the Sn‐based perovskite blue emission LED is successfully fabricated for the first time at 467 nm with a champion EQE of 1.3% and a maximum brightness of 800 cd m −2 . This work gives insights into the luminescence mechanism of Sn‐based perovskites and provides a new theoretical basis for the development of lead‐free blue LEDs.