Unravelling the effects of an iodine vacancy and a dipolar molecular stabilizer on hot-electron recombination of metal halide perovskites

Abstract

The surface properties including both defect-modified and surface functionalization by dipolar molecules has a significant influence on the dynamics of charge carriers within metal halide perovskites (MHPs), which is crucial for achieving highly efficient and stable optoelectronic devices. Herein, we considered the sulfobetaine (SFB) as a model structure of dipolar molecular stabilizer, and systematically explored the surface defects and SFB passivation to regulate geometrical/electronic structures of perovskites, as well as its impact on spatial separation of photogenerated carriers by first-principles calculations. We further utilized time-dependent ab initio nonadiabatic molecular dynamics to simulate the photogenerated carrier dynamical behavior and elucidate the exact influence of surface iodine vacancy and SFB passivators have in tuning excited state lifetime. These theoretical results provide insight into physical mechanism behind defect passivation via dipolar stabilizers, promising routes towards improved optoelectronic applications for MHPs.