Abstract
Nonradiative recombination represents a critical performance limitation in perovskites. Combining time-dependent density functional theory (TD-DFT) with nonadiabatic molecular dynamics (NAMD), we elucidate how the oxidation states of hydrogen interstitial defects (H(0) (i), H(i) (+), and H(i) (-)) dictate recombination dynamics in FAPbI(3). The recombination lifetime depends on the oxidation state, varying over three orders of magnitude, from a short time of 0.1 ns (H(0) (i)) to prolonged times of 44 ns (H(i) (+)) and 72 ns (H(i) (-)). H(0) (i) introduces a deep-level defect state, enhancing nonadiabatic coupling between band edges from 0.35 meV to 1.56 meV. Chlorine passivation (Cl@H(0) (i)) neutralizes H(0) (i) defects by eliminating the deep trapping state, stabilizing the lattice and reducing nonadiabatic coupling to 0.30 meV. This passivation enhances the carrier lifetime by 2-3 orders of magnitude, ultimately reaching 87 ns. Our findings establish a map of oxidation-state-dependent recombination for hydrogen interstitials and provide atomistic insights for developing defect passivation strategies for high-performance perovskites.