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.