Efficiency Enhancement of Solid-State CuInS2 Quantum Dot-Sensitized Solar Cells by Improving the Charge Recombination

a Schematic of the device architecture. b The cross-sectional SEM image of the solar cell (corresponding to the sample prepared with 20？cycles and annealed at 400？°C). c The elemental distribution maps of Cu, In, and S elements in TiO2/CIS laye