Radical‐Mediated Surface Reconstruction of SnO 2 Nanocrystals Enables Efficient and Durable Perovskite Solar Cells and Modules

ABSTRACT Charge‐transport layers fundamentally dictate interfacial recombination, carrier extraction, and operational stability in perovskite solar cells (PSCs), yet scalable routes to simultaneously regulate their colloidal stability and defect chemistry remain elusive. Here, we report a radical‐mediated surface reconstruction strategy for ligand‐free SnO 2 nanocrystals that enables concurrent gains in device efficiency, scalability, and durability. Sonochemical activation generates hydroxyl radicals that selectively passivate oxygen‐deficient Sn sites while inducing electrostatically stabilized dispersions with exceptional shelf stability, allowing the SnO 2 colloids to be stored for over 2 years without aggregation or performance degradation. This stabilization enables the formation of uniform electron transport layers with reduced trap density and enhanced electron mobility. These improvements promote buried‐interface perovskite crystallization and accelerate charge extraction, yielding PSCs with an efficiency of 26.47% (certified 26.12%). Importantly, the strategy is inherently scalable, enabling a perovskite module (∼110 cm 2 ) with an efficiency of 21.45%. Devices exhibit enhanced operational stability, retaining 92% efficiency after 1000 h thermal aging (ISOS‐D‐2), maintaining 88% efficiency under maximum power point tracking (ISOS‐L‐1), and showing negligible degradation over 500 thermal cycles (ISOS‐T‐3). These results establish radical‐mediated engineering of SnO 2 nanocrystals as a general pathway in perovskite photovoltaics, bridging high efficiency, large‐area manufacturability, and long‐term operational stability.