Composition pinning growth for efficient and stable all‐inorganic Pb‐Sn perovskite solar cells

Abstract All‐inorganic Pb‐Sn perovskites offer near‐optimal bandgaps for photovoltaics but suffer from compositional inhomogeneity and limited operational stability, particularly in large‐area devices. Here, we demonstrate that the film formation pathway plays a decisive role in governing the optoelectronic properties and device performance of all‐inorganic CsPb _0.5 Sn _0.5 I ₃ perovskite solar cells (PSCs). By employing a composition pinning growth (CPG) strategy, the formation of segregation‐prone crystallization states is suppressed, leading to reduced surface Sn enrichment and Sn oxidation, lower defect density, and more favorable charge‐carrier dynamics. As a result, CPG‐based devices achieve power conversion efficiencies (PCEs) of 19.37% at the unit‐cell level, among the highest of reported all‐inorganic Pb‐Sn PSCs, and 17.03% for 64 cm ² aperture area modules and enhanced operational stability, retaining approximately 87% of the initial efficiency after 1000 h of continuous operation at 85°C and 85% relative humidity. This work establishes growth‐pathway engineering as a scalable and effective strategy for achieving high‐efficiency, stable all‐inorganic CsPb _0.5 Sn _0.5 I ₃ perovskite photovoltaics. image