Efficiency boosting in Sb₂(S,Se)₃ solar cells enabled by tailoring bandgap gradient via a hybrid growth method

Antimony selenosulfide (Sb-2(S,Se)(3)) solar technology has garnered widespread interest in recent years due to its exceptional photovoltaic properties and excellent stability. The hydrothermal deposition method has enabled cell efficiencies of over 10% in state-of-the-art Sb-2(S,Se)(3 )solar cells. Nevertheless, issues arising from the hydrothermal method, such as the formation of an inappropriate bandgap gradient during film growth and the loss of S and Se during the annealing process, remain unresolved. To address these challenges, we developed a hybrid growth method with a specific emphasis on optimizing the unfavorable bandgap gradient. This method consists of two stages: the first stage involves hydrothermal deposition, while the second stage employs vapor transport deposition. By controlling the second-stage process, two types of optimized bandgap gradients have been achieved. As a result, the short-circuit current density (J(sc)) and fill factor (FF) of Sb-2(S,Se)(3) solar cells with a superstrate configuration of Glass/Fluorine-doped Tin Oxide/CdS/Sb-2(S,Se)(3)/Poly(triaryl amine)/Au were significantly improved, resulting in a promising efficiency approaching 8%. The enhanced J(sc) and FF can be attributed to the tailored bandgap gradient of the Sb-2(S,Se)(3) film fabricated using the hybrid method. This work presents a viable approach to enhance the device performance of Sb-2(S,Se)(3) solar cells and sheds new light on the fabrication of high-performance Sb-2(S,Se)(3)-based photovoltaic devices.