Fig. 3From: In Situ-Formed and Low-Temperature-Deposited Nb:TiO2 Compact-Mesoporous Layer for Hysteresis-Less Perovskite Solar Cells with High PerformanceXPS spectra of 2% Nb:TiO2. a Survey, b Ti 2p, c Nb 3d, and d O 1sBack to article page