Ion‐Defect Dual Management for Achieving Efficient Air‐Processed Perovskite Solar Cells With Certified Efficiency 27.1%

Achieving high-efficiency and durable perovskite solar cells (PSCs) under ambient fabrication remains a fundamental challenge due to the coupled instabilities arising from halide redox chemistry and Pb-related defects. Here, we introduce a molecular "ion-defect dual-management" strategy using N-Acetylsulfanilyl Chloride (ABSC) that simultaneously regulates iodide redox species in precursor solutions and passivates electronic imperfections in the crystallized films. ABSC selectively induces the in situ formation of I₃ ^- without FA⁺ deprotonation, while its multidentate functional groups strongly coordinate with undercoordinated Pb²⁺ to suppress deep traps and enhance crystallinity. This synergistic regulation yields air-processed inverted PSCs with a certified steady-state efficiency of 27.10% and long-term operational stability retaining over 98% of the initial performance after 1000 h of maximum power point tracking. Importantly, ABSC is fully compatible with vacuum flash-evaporation, enabling scalable fabrication of large-area flexible and bifacial modules exceeding 16% efficiency. Our findings establish a mechanistically grounded and industrially relevant route for stabilizing soft ionic lattices, advancing perovskite photovoltaics toward practical, high-performance deployment.