Reduced energy band offset between photoanode and dye in SnO 2 -based DSCs with Cu doping

Tin oxide (SnO 2 ) film is a promising photoanode for dye-sensitized solar cells (DSCs) with excellent optical and electrical properties as well as facile accessibility. Highly efficient DSCs require a fast charge transfer from dye to SnO 2 in order to reduce the recombination from trap states. Herein, we report a Cu-doped SnO 2 film as a photoanode for DSCs with faster charge transfer and higher efficiency. Ultraviolet photoelectron spectroscopy study indicates that conduction band of the Cu-doped SnO 2 is adjusted from − 4.75 to − 4.57 eV via 5 at.% Cu concentrations. By adjusting the Cu concentrations, energy offset between the SnO 2 and dye is reduced, which accelerates the charge transfer. Power conversion efficiency of the DSCs with optimized Cu-doped SnO 2 achieves 4.01%, which is 61.7% higher than its counterpart without Cu doping.