Synergy Between Dynamic Behavior of Hydrogen Defects and Non‐Radiative Recombination in Metal‐Halide Perovskites

Abstract In organic‐inorganic hybrid perovskite solar cells (PSCs), hydrogen defects introduce deep‐level trap states, significantly influencing non‐radiative recombination processes. Those defects are primarily observed in MA‐PSCs rather than FA‐PSCs. As a result, MA‐PSCs demonstrated a lower efficiency of 23.6% compared to 26.1% of FA‐PSCs. In this work, both hydrogen vacancy (V H − ) and hydrogen interstitial (H i − ) defects in MAPbI 3 bulk and on surfaces, respectively are investigated. i) Bulk V H − defects have dramatic impact on non‐radiative recombination, with lifetime varying from 67 to 8 ns, depending on whether deprotonated MA 0 are ion‐bonded or not. ii) Surface H‐defects exhibited an inherent self‐healing mechanism through a chemical bond between MA 0 and Pb 2+ , indicating a self‐passivation effect. iii) Both V H − and H i − defects can be mitigated by alkali cation passivation; while large cations are preferable for V H − passivation, given strong binding energy of cation/perovskite, as well as, weak band edge non‐adiabatic couplings; and small cations are suited for H i − passivation, considering the steric hindrance effect. The dual passivation strategy addressed diverse experimental outcomes, particularly in enhancing performance associated with cation selections. The dynamic connection between hydrogen defects and non‐radiative recombination is elucidated, providing insights into hydrogen defect passivation essential for high‐performance PSCs fabrication.