Iodide Management and Oriented Crystallization Modulation for High‐Performance All‐Air Processed Perovskite Solar Cells

Abstract Halide‐related defects at the buried interface not only cause nonradiative recombination, but also seriously impair the long‐term stability of perovskite solar cells (PSCs). Herein, a bottom‐up, all‐in‐one modification strategy is proposed by introducing a multisite antioxidant ergothioneine (EGT) at the buried interface to manage iodide ions and manipulate crystallization dynamics. The findings demonstrate that EGT not only passivates uncoordinated Sn 4+ /Pb 2+ defects, but also firmly anchors iodide ions and inhibits their oxidation to I 2 . Additionally, the modification by EGT enhances the oriented crystallization of perovskite, improves the carrier dynamics, and releases residual stresses. Consequently, the optimized all‐air processed device (Rb 0.02 (FA 0.95 Cs 0.05 ) 0.98 PbI 2.91 Br 0.03 Cl 0.06 ) achieves a remarkable power conversion efficiency (PCE) of 25.13%, which is among the highest values reported for devices fabricated in air, along with ultrahigh open‐circuit voltage ( V OC ) of 1.191 V and fill factor (FF) of 84.9%. The optimized device without encapsulation exhibits strong humidity, thermal, and operational stability under ISOS protocol. Specifically, the initial efficiency of the device is retained at 90.12% after 1512 h of thermal ageing at 65 °C and 90.14% after 930 h of continuous maximum power point tracking (MPPT) under simulated AM1.5 illumination.