Impact of Hydrogen Vacancies on Non‐Radiative Recombination in Metal‐Halide Perovskites

Hydrogen vacancies (V_H) were considered major non-radiative recombination centers in hybrid perovskites. By employing a multiscale approach that combines first-principles calculations and molecular dynamics (MDs) simulations, our findings indicated that the V_H impact was overestimated due to the previous metastable V_H configurations. The organic molecules with V_H located on either the nitrogen or carbon atom act as the ligands that form energetically stable dimers with Pb²⁺ cations. These dimers lower V_H energy by 0.35-0.97 eV in MAPbI₃ and by 0.88-1.01 eV in FAPbI₃, compared to non-bonding configurations. These dimers significantly boosted potential energy barriers of hole capture, resulting in a dramatic reduction in carrier capture coefficients by over 10 orders of magnitude. Consequently, the total capture coefficients (C_total) for the dominant V_H in MAPbI₃ and FAPbI₃ are on the order of 10^-17 and 10^-31 cm^-3s^-1, respectively. By uncovering the negligible impact of V_H on non-radiative recombination, this work shifts the focus toward more significant defects, for instance, iodine interstitial (with a capture coefficient on the order of 10^-8 cm^-3s^-1), thereby paving the way for optimizing perovskite solar cells efficiency to meet the Shockley-Queisser limit.