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 (Sb2S3) have great application potential and prospect. Typical Sb2S3 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). As an alternative material, TiO₂ with non-toxic and wide band gap (3.1-3.4 eV) can meet the photoelectric requirements of ETL, but when the TiO2 is used as a template for Sb2S3 deposition , it shows an island of uneven growth. Herein, an ion layer adsorption and reaction (ILAR) method was used to modify the surface of TiO2 with an ultra-thin layer of In2S3, thereby improving the nucleation and growth characteristics of Sb2S3 during hydrothermal deposition. In this way, the Sb2S3 film forms a compact and specular state on the TiO2 surface similar to that on the CdS surface, realizing the quasi-epitaxial growth of the Sb2S3 film, which provides a new solution for efficient and environmentally friendly solar cells.