Defect Passivation in Air-Stable Tin(IV)-Halide Single Crystal for Emissive Self-Trapped Excitons

Tin(IV)-based metal halides are promising optoelectronic materials due to their robust structure and eco-friendly nature, but these materials exhibit poor photoluminescence (PL) properties and the underlying mechanisms are still elusive. Here, a novel air-stable hybrid Sn 4+ -halide material (C 8 H 22 N 2 Cl) 2 SnCl 6 that is resistant to moisture ( > 70% relative humidity) for > 1 year is reported. The inferior PL property of (C 8 H 22 N 2 Cl) 2 SnCl 6 is limited by the lattice defects and robust crystal structure, which however could be effectively improved by introducing Sb 3+ ion with stereoactive 5s 2 lone pair. As a result, Sb 3+ -doped (C 8 H 22 N 2 Cl) 2 SnCl 6 exhibits a superbly stable room-temperature PL centered at 690 nm with an unprecedented quantum yield (QY) of 41.76% from self-trapped excitons, which is the highest PLQY of hybrid tin(IV)-based perovskite materials. The improved PL efficiency is attributed to the defect passivation and remarkable structure distortion induced by Sb 3+ dopants. This dopant-induced defect passivation and exciton self-trapping approach offers an avenue to improve optoelectronic material performance.