Benign Hydrogen Vacancy in Bromide-Based Organic-Inorganic Hybrid Perovskites

Bromide-based organic-inorganic hybrid perovskites (OIHPs) have emerged as one of the outstanding photovoltaic materials. We demonstrate using density functional theory and nonadiabatic molecular dynamics simulations that detrimental hydrogen vacancy (V_H) in iodide-based OIHPs turns out to be benign in bromide-based OIHPs. Benign V_H in MAPbBr₃ [MA = CH₃NH₃] is mainly attributed to the absence of deep trap states. Although the V_H in FAPbBr₃ [FA = HC(NH₂)₂] has been demonstrated to be a deep-level defect, its remarkably high formation energy and low total capture coefficient (7.69 × 10^-13 cm³ s^-1), associated with the weak electron-phonon coupling and efficient thermal excitation, effectively suppress the nonradiative charge recombination. As a result, the long charge carrier lifetime of FAPbBr₃ can be maintained. These findings reveal the intrinsic advantage owing to benign V_H in bromide-based OIHPs and provide critical theoretical insights for minimizing nonradiative charge losses.