Crystal Growth Regulation and Iodine Management for High Performance Inverted Inorganic Perovskite Solar Cells

ABSTRACT Lead coordination chemical environment and intermolecular interactions in the precursor solution influence crystallization kinetics and defect distribution of inorganic perovskite. Meanwhile, inhibiting the formation of iodine related species is crucial for mitigating inorganic perovskite decomposition. Here, we introduce 4‐chlorobenzenesulfinic acid (CBSA), a Lewis base with strong coordination ability, into the inorganic perovskite precursor solution to modulate Pb 2+ chemistry environment and implement iodine management. The robust interaction between CBSA and [PbI 6 ] 4− octahedra promotes the ion exchange process dominated by DMAI volatilization and cesium ion intercalation, inducing uniform nucleation and the formation of large grains size. Moreover, CBSA locks iodide ions through hydrogen bonding to reduce the formation of iodine defects and iodine species, while reducing trap density and alleviating perovskite decomposition by passivating undercoordinated lead defects. Ultimately, the power conversion efficiency (PCE) of inverted inorganic perovskite solar cells (IPSCs) with CBSA is increased from 18.88% to 21.67%. More importantly, unencapsulated devices maintained 95% of their initial efficiency after 550 h of maximum power point tracking (MPPT) under continuous 1‐sun illumination, demonstrating exceptional operational stability.