Mechanistic Study of the Transition from Antimony Oxide to Antimony Sulfide in the Hydrothermal Process to Obtain Highly Efficient Solar Cells

Abstract Obtaining high‐quality absorber layers is a major task for constructing efficient thin‐film solar cells. Hydrothermal deposition is considered a promising method for preparing high‐quality antimony sulfide (Sb 2 S 3 ) films for solar cell applications. In the hydrothermal process, the precursor reactants play an important role in controlling the film formation process and thus the film quality. In this study, Sb 2 O 3 is applied as a new Sb source to replace the traditional antimony potassium tartrate to modulate the growth process of the Sb 2 S 3 film. The reaction mechanism of the transition from Sb 2 O 3 to Sb 2 S 3 in the hydrothermal process is revealed. Through controlling the nucleation and deposition processes, high‐quality Sb 2 S 3 films are prepared with longer carrier lifetimes and lower deep‐level defect densities than those prepared from the traditional Sb source of antimony potassium tartrate. Consequently, a solar cell device based on this improved Sb 2 S 3 delivers a high power conversion efficiency of 6.51 %, which is in the top tier for Sb 2 S 3 ‐based solar devices using hydrothermal methods. This research provides a new and competitive Sb source for hydrothermal growth of high‐quality antimony chalcogenide films for solar cell applications.