Cooperative Ion Migration Suppression via Multi‐Scale Regulation for Enhancing the Performance of Inverted Perovskite Solar Cells

ABSTRACT Interstitial doping of metal cations has emerged as a promising strategy to suppress ion migration and enhance the stability of perovskite solar cells. However, excessive doping often introduces lattice strain that undermines structural integrity. Here we present a multi‐scale regulation strategy using sodium 2,3,4,5,6‐pentafluorobenzoate (PFSBZ) additive to concurrently inhibit ion migration across crystalline lattices, grain boundaries (GBs) and interfaces. The cationic and anionic moieties of PFSBZ suppress iodide‐related defects from perovskite lattices and GBs via interstitial occupancy and anion– π interaction, respectively. This cooperative suppression strategy reduces the required additive contents, thereby preserving crystal structure integrity. Density functional theory calculations further reveal that PFSBZ prevents direct contact between the perovskite and fullerene ring, effectively immobilizing iodide species at the perovskite/PCBM interface. As a result, the PFSBZ‐modified perovskite films exhibit enhanced ion‐migration energy barriers, reduced trap density, prolonged carrier lifetime, and improved band alignment. The resulting devices achieve a champion power conversion efficiency of 25.53% and retain 90.21% of initial performance after 800 h of continuous operation. Our work offers a multi‐scale design principle for stabilizing metal halide perovskites against ion migration.