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

Abstract Tin dioxide (SnO 2 ) 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 SnO 2 layer is achieved by chemical bath deposition with tunable properties, while the commercial SnO 2 nanocrystals (NCs) with low tunability still face the necessity of further improvement. Here, a kind of highly crystallized Cl‐doped SnO 2 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 SnO 2 NCs regardless of the extrinsic Cl‐doping conditions, the intrinsic Cl‐doped SnO 2 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 SnO 2 NCs achieve a champion efficiency up to ≈25% for small cell (0.085 cm 2 ) and ≈20% for mini‐module (12.125 cm 2 ), indicating its potential as a promising candidate for ETL in high‐performance perovskite photovoltaics.