Efficient carbon-based planar CsPbBr₃ perovskite solar cells with Li-doped amorphous Nb₂O₅ layer

Facile electron injection and extraction are two important attributes desired in electron transportation layer (ETL) to improve the power conversion efficiency (PCE) of planar CsPbBr₃ perovskite solar cell (PSC). Here, it is demonstrated that Li-doping of amorphous compact Nb₂O₅ (Li: Nb₂O₅) can effectively increase the electronic conductivity and facilitate the charge extraction with low recombination. Comparing with the PSC with Nb₂O₅ ETL, the PCE of the Li: Nb₂O₅-based PSC is enhanced from 5.79% to 7.06%. Furthermore, the Li: Nb₂O₅-based CsPbBr₃ PSC exhibits a fabulous stability when exposed in air with moisture of ∼40% for 60 days. This work shows that ion doping provides new opportunities for preparing effective ETLs and high-performance inorganic PSCs.