Lanthanum-Doped Strontium Stannate for Efficient Electron-Transport Layers in Planar Perovskite Solar Cells

Strontium stannate SrSnO3 (SSO) has been proposed as a promising alternative electron-transport layer (ETL) for perovskite solar cells (PSCs) due to its superior conductivity and photoelectronic properties. Here, we demonstrate a versatile lanthanum-doped SrSnO3 (La-SSO) perovskite oxide nanocrystals prepared at relatively low temperatures as an efficient ETL, which is compatible with the processing of the flexible device and could significantly reduce the manufacturing cost. Systematic investigations show that the La-SSO ETLs form better interfacial contact with perovskite layers and thus improve the film crystal quality by reducing the grain boundaries and voids, resulting in the reduced charge recombination in perovskite layers. Furthermore, the La-SSO ETLs can improve electron transport due to its superior conductivity and electron mobility. As a result, the La-SSO ETL-based PSCs enable a power conversion efficiency of 18.7% with a significantly reduced hysteresis. Our work reveals that La doping is a promising ETL candidate for highly efficient and stable PSCs.