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

Abstract

Antimony selenosulfide (Sb₂(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 Sb₂(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 Sb₂(S,Se)₃ solar cells with a superstrate configuration of Glass/Fluorine-doped Tin Oxide/CdS/Sb₂(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 Sb₂(S,Se)₃ film fabricated using the hybrid method. This work presents a viable approach to enhance the device performance of Sb₂(S,Se)₃ solar cells and sheds new light on the fabrication of high-performance Sb₂(S,Se)₃-based photovoltaic devices.