Post-Treatment of TiO 2 Film Enables High-Quality Sb 2 Se 3 Film Deposition for Solar Cell Applications.

The TiO 2 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 Sb 2 Se 3 . In this study, a simple CdCl 2 post-treatment is conducted to functionalize the TiO 2 thin film, enabling the induction of nucleation sites and growth of high-quality Sb 2 Se 3 . The interfacial treatment optimizes the conduction band offset of TiO 2 /Sb 2 Se 3 and leads to an essentially improved TiO 2 /Sb 2 Se 3 heterojunction. With this convenient interface functionalization, the power conversion efficiency of the Sb 2 Se 3 solar cell is remarkably improved from 2.02 to 6.06%. This study opens up a new avenue for the application of TiO 2 as a wide band gap electron-transporting material in antimony chalcogenide solar cells.