Compact SnO(2)/Mesoporous TiO(2) Bilayer Electron Transport Layer for Perovskite Solar Cells Fabricated at Low Process Temperature

Charge transport layers have been found to be crucial for high-performance perovskite solar cells (PSCs). SnO(2) has been extensively investigated as an alternative material for the traditional TiO(2) electron transport layer (ETL). The challenges facing the successful application of SnO(2) ETLs are degradation during the high-temperature process and voltage loss due to the lower conduction band. To achieve highly efficient PSCs using a SnO(2) ETL, low-temperature-processed mesoporous TiO(2) (LT m-TiO(2)) was combined with compact SnO(2) to construct a bilayer ETL. The use of LT m-TiO(2) can prevent the degradation of SnO(2) as well as enlarge the interfacial contacts between the light-absorbing layer and the ETL. SnO(2)/TiO(2) bilayer-based PSCs showed much higher power conversion efficiency than single SnO(2) ETL-based PSCs.