Modification of TiO₂ template with In₂S₃ for quasi-epitaxial growth of Sb₂S₃ thin film solar cells

Abstract Thin film solar cells based on the wide band gap absorber antimony sulfide (Sb 2 S 3 ) have great application potential and prospect. Typical Sb 2 S 3 thin-film solar cells usually use a low-cost solution method (such as hydrothermal deposition) to prepare the light-absorbing material, and use a toxic CdS film with a narrow band gap (about 2.4 eV) as the electron transport layer (ETL). TiO 2 , a non-toxic ETL alternative with a wide band gap (3.1–3.4 eV), fulfills the photoelectric needs of the ETL. But when the TiO 2 is used as a template for Sb 2 S 3 deposition, it shows an island of uneven growth. Herein, an ion layer adsorption and reaction method was used to modify the surface of TiO 2 with an ultra-thin layer of In 2 S 3 , thereby improving the nucleation and growth characteristics of Sb 2 S 3 during hydrothermal deposition. In this way, the Sb 2 S 3 film forms a compact and specular state on the TiO 2 surface similar to that on the CdS surface, realizing the quasi-epitaxial growth of the Sb 2 S 3 film, which provides a new solution for efficient and environmentally friendly solar cells.