Endogenous Redox‐Sensitive UV Absorbers Enable Efficient and Stable Full Air‐Processed Perovskite Solar Cells

ABSTRACT Perovskite solar cells (PSCs) face significant obstacles to commercialization due to the rapid degradation of perovskite materials under non‐equilibrium conditions, especially under ultraviolet (UV) radiation from sunlight. To address this critical challenge, an endogenous redox‐sensitive UV absorber, 2,2″‐Thiobis‐(4‐tert‐octylphenoxy)‐butylamine nickel (TTOB), was introduced into the perovskite precursor solution. The integrated TTOB enhances the efficiency and stability of PSCs through multiple synergistic functions, including superior UV shielding capability and sustained chemical passivation effects for ongoing defect repair. Ultimately, the resultant device fabricated entirely in air achieved a best‐in‐class power conversion efficiency (PCE) of 25.24%, accompanied by greatly improved stability under various environmental conditions, with retaining approximately 86% of initial efficiency after 1,000 h of continuous UV exposure, about 87% after 40 days of outdoor real‐time storage, and over 80% after 1430 h of continuous illumination. This innovative UV protection strategy with endogenous redox‐sensitive offers transformative potential for the large‐scale application of perovskite photovoltaic technology during actual outdoor operation.