Post-Treatment of TiO2 Film Enables High-Quality Sb2Se3 Film Deposition for Solar Cell Applications

The TiO2 thin film is considered as a promising wide band gap electron-transporting material. However, due to the strong Ti–O bond, it displays an inert surface characteristic causing difficulty in the adsorption and deposition of metal chalcogenide films such as Sb2Se3. In this study, a simple CdCl2 post-treatment is conducted to functionalize the TiO2 thin film, enabling the induction of nucleation sites and growth of high-quality Sb2Se3. The interfacial treatment optimizes the conduction band offset of TiO2/Sb2Se3 and leads to an essentially improved TiO2/Sb2Se3 heterojunction. With this convenient interface functionalization, the power conversion efficiency of the Sb2Se3 solar cell is remarkably improved from 2.02 to 6.06%. This study opens up a new avenue for the application of TiO2 as a wide band gap electron-transporting material in antimony chalcogenide solar cells.