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

Hydrogen vacancies (V) 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 impact was overestimated due to the previous metastable V configurations. The organic molecules with V located on either the nitrogen or carbon atom act as the ligands that form energetically stable dimers with Pb cations. These dimers lower V energy by 0.35-0.97 eV in MAPbI and by 0.88-1.01 eV in FAPbI, 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) for the dominant V in MAPbI and FAPbI are on the order of 10 and 10 cms, respectively. By uncovering the negligible impact of V 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 cms), thereby paving the way for optimizing perovskite solar cells efficiency to meet the Shockley-Queisser limit.