Selenium‐Rich Sb₂(S,Se)₃ Thin Films Deposited via Sequential Chemical Bath Deposition for High‐Efficiency Solar Cells

Abstract Recently, solution‐processed antimony sulfoselenide (Sb₂(S,Se)₃) thin films and solar cells have gained popularity and achieved impressive results. One of the most effective improvements is the chemical bath deposition (CBD) approach, which is gentle, highly adjustable, and scalable. However, development in alloyed Sb₂(S,Se)₃ using this process has been modest, with a power conversion efficiency (PCE) of roughly 8%. In this work, a sequential CBD deposition strategy is designed, introducing sulfur (S) or selenium (Se) sources at different stages of the CBD process to achieve high‐quality Sb₂(S,Se)₃ thin films and devices. Impressively, adding a moderate amount of sodium thiosulfate and thioacetamide as mixed sulfur sources during the CBD deposition of Sb₂Se₃ can produce Se‐rich Sb₂(S,Se)₃ films with high crystallinity, suitable bandgaps, low defect density, and favorable energy level alignment. With a short‐circuit current density (J_SC) of 26.80 mA cm⁻² and a fill factor (FF) of 65.89%, the solar cells with the FTO/CdS/Sb₂(S,Se)₃/Spiro‐OMeTAD/Au structure obtained an impressive PCE of 9.29%, the highest to date for Sb₂(S,Se)₃ solar cells manufactured with the CBD process. This study provides a feasible approach for enhancing the performance of CBD‐produced Sb₂(S,Se)₃ solar cells and offers new insights and techniques for the synthesis of other complex multicomponent thin films.