Cyclically Dynamic Defect Management Enables High‐efficiency Sn─Pb Perovskite Photovoltaics with Enhanced Photostability and Fatigue Resistance

Abstract

Abstract Narrow‐bandgap mixed Sn‐Pb perovskite solar cells (PSCs) have showcased great promise to approach the Shockley‐Queisser limit. Despite continuously proven elevated power conversion efficiencies (PCEs), the practical application and commercial use of Sn‐Pb PSCs are hindered by poor photostability and anti‐fatigue performance. These issues arise from multiple intrinsic imperfections formed during crystallization and light‐triggered defects generated during device operation under intermittent illumination. Herein, we introduced a novel “dynamic defect management” (DDM) strategy that mitigated photodegradation of Sn‐Pb perovskites and significantly enhanced the device lifespan. The strong coordination between metallocene intercalation and metal cations (Pb 2+ /Sn 2+ ) within the perovskite lattice effectively passivated the crystallographic defects, reduced the defect densities by 34.5% and suppressed the non‐radiative recombination. Furthermore, the metallocene and corresponding cation could function as a redox pair, offering a dynamic and continuous healing mechanism to restore the light‐induced defects in a cyclical manner. Additionally, the metallocene interlayer itself acted as a shield against the ultraviolet radiation during the light aging process. Consequently, we achieved decent PCEs up to 23.59% for the mixed Sn‐Pb PSCs modified with DDM strategy, 14.7% higher than that of the reference devices, accompanied by enhanced photostability which witnessed a 7‐fold enhancement compared to the pristine device under MPP operation tracking and remarkable anti‐fatigue performance, retaining 83% of the original PCE after 22 accelerated fatigue test cycles (12/12 h UV light/dark cycle).