Highly Crystalized Cl‐Doped SnO₂ Nanocrystals for Stable Aqueous Dispersion Toward High‐Performance Perovskite Photovoltaics

Abstract Tin dioxide (SnO₂) with high conductivity and low photocatalytic activity has been reported as one of the best candidates for highly efficient electron transport layer (ETL) in perovskite solar cell (PSC). The state‐of‐the‐art SnO₂ layer is achieved by chemical bath deposition with tunable properties, while the commercial SnO₂ nanocrystals (NCs) with low tunability still face the necessity of further improvement. Here, a kind of highly crystallized Cl‐doped SnO₂ NCs is reported that can form very stable aqueous dispersion with shelf life up to one year without any stabilizer, which can facilitate the fabrication of PSCs with satisfactory performance. Compared to the commercial SnO₂ NCs regardless of the extrinsic Cl‐doping conditions, the intrinsic Cl‐doped SnO₂ NCs effectively suppress the energy barrier and reduces the trap state density at the buried interface between perovskite and ETL. Consequently, stable PSCs based on such Cl‐doped SnO₂ NCs achieve a champion efficiency up to ≈25% for small cell (0.085 cm²) and ≈20% for mini‐module (12.125 cm²), indicating its potential as a promising candidate for ETL in high‐performance perovskite photovoltaics.