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

The electron transport layer (ETL) of tin dioxide (SnO2) 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 SnO2 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 SnPS3 nanosheets into the SnO2 ETL. The sulfur atoms in the SnPS3 nanosheets fill the oxygen vacancies in SnO2, reducing the trap state density. Meanwhile, the SnPS3-modified SnO2 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 SnO2-based interfaces for PSCs.