Metal Phosphorus Chalcogenide Nanosheet-Modified SnO2 Electron Transport Layers for Efficient Perovskite Solar Cells

The electron transport layer (ETL) of tin dioxide (SnO 2 ) plays a pivotal role in n–i–p perovskite solar cells (PSCs) by facilitating the extraction of photogenerated electrons and blocking the transport of holes. However, the presence of oxygen vacancies in SnO 2 adversely affects the quality of the ETLs and impairs the electron transport properties, reducing the performance of PSCs. Here, we present a novel interfacial engineering route by incorporating an exfoliated two-dimensional (2D) metal–phosphorus–chalcogen complex of the SnPS 3 nanosheets into the SnO 2 ETL. The sulfur atoms in the SnPS 3 nanosheets fill the oxygen vacancies in SnO 2, reducing the trap state density. Meanwhile, the SnPS 3 -modified SnO 2 layer exhibits an improved energy level alignment and enhanced electrical conductivity. As a result, a remarkable efficiency improvement from 21.51 to 23.01% was observed, accompanied by optimized stability. These results expand the application scenarios of 2D metal–phosphorus–chalcogen complexes and provide a novel approach to tune SnO 2 -based interfaces for PSCs.