Charge Trap Formation and Passivation in Methylammonium Lead Tribromide

Owing to spectacular optoelectronic properties, halide perovskites hold great promises in various fields, including photovoltaics and light-emission devices. Although hybrid halide perovskites are known to be unstable when exposed durably to water and oxygen, it has been shown that humid air and oxygen can restore the photoluminescent properties of methylammonium lead tribromide (MAPbBr(3)) that vanish under vacuum [Fang, H.-H. et al. Sci. Adv. 2016, 2, e1600534]. Here, thanks to density functional theory-based calculations, we propose that the quenching and revival of surface photoluminescent properties are due to the formation and passivation of surface charge traps. Moreover, we establish that bulk properties are preserved either because molecules are unlikely to penetrate the bulk or because they do not interfere with the electronic states involved in the optical properties.