Indium‐Assisted Carrier Transport Enhancement for Efficient Sb ₂ (S,Se) ₃ Solar Cells

Post-treatment has been regarded as an important strategy in thin-film fabrication, which surmounts the limitations in directly deposited films through manipulating the chemical, electrical, morphological, and defect properties. In terms of the emerging photovoltaic material antimony selenosulfide (Sb₂(S,Se)₃), conventional hydrothermal synthesis of Sb₂(S,Se)₃ thin film has achieved great improvement toward 10% efficiency bottleneck in solar cell applications. However, this fabrication method fails to achieve desirable carrier transport and defective properties. In this study, we develop an InCl₃-based post-treatment method to enhance the carrier transport and passivate the deep-level defects, including S and Se vacancies and anti-site defects (Sb_S(e)3). We find that the indium ions generated by post-treatment preferentially diffuse into the interstitial sites of (Sb₄S(e)₆)_n ribbons, leading to the formation of In-S(e) chemical bonds. These atomic interactions facilitate efficient carrier transport across the entire film. Furthermore, the synergistic effects of energy level alignment optimization, deep-level defect passivation, and interfacial trap inhibition effectively suppress non-radiative carrier recombination and improve photovoltaic performance. Consequently, this post-treatment enables the Sb₂(S,Se)₃ solar cell to achieve a remarkable power conversion efficiency of 10.55%. This study provides a novel post-treatment method for defect passivation, electronic structure regulation, and carrier transport management for high-performance antimony selenosulfide solar cells.