Anharmonic Motion-Induced Self-Passivation of Hydrogen Defects in Hybrid Organic–Inorganic Perovskites: Ab Initio Quantum Dynamics

Hydrogen defects in hybrid organic–inorganic perovskites have garnered increasing attention due to their impact on device performance. Using nonadiabatic molecular dynamics on CH 3 NH 3 PbI 3, we demonstrate that anharmonic motions at room temperature facilitate the formation of a stable Pb–N coordination bond between the Pb 2+ ion and the CH 2 NH 3 molecule in the presence of a negatively charged hydrogen interstitial defect. This bond eliminates the midgap hole trap state arising from the lone-pair electrons on the nitrogen of the dissociated CH 3 NH 3 + cation at 0 K, enabling defect self-healing. It also reduces nonadiabatic coupling by decreasing the electron–hole wave function overlap and slows decoherence by suppressing thermal fluctuations. The reduced coupling, combined with a slight increase in the bandgap, dominates over the slower decoherence, extending the charge carrier lifetime to over 1.5 times that of the pristine system. This study establishes a self-passivation mechanism for hydrogen defects in perovskites under operational conditions.