Close Space Sublimation Growth of Sb ₂ (S,Se) ₃ Thin-Film Solar Cells

This study reports the synthesis and characterization of Sb₂(S,Se)₃ thin films for thin-film photovoltaics via a single-source close space sublimation (CSS) approach. We demonstrate power conversion efficiencies of up to 4.3% with notable improvements in open-circuit voltage (<i>V</i>_oc >490 mV) compared to those of Sb₂Se₃ equivalents. Secondary ion mass spectrometry, X-ray diffraction, and cross-sectional scanning and transmission electron microscopies identified some issues in controlling film stoichiometry, particularly with sulfur loss, leading to oxide formation and elevated series resistance, reducing the fill factor in completed devices. We also identify clear discrepancies between the determined bandgap, sulfur content inferred from X-ray diffraction analysis, and sulfur content of the synthesized source material. We conclude that while CSS is a promising method for Sb₂(S,Se)₃ film fabrication, addressing sulfur loss during deposition is crucial to achieving further improvements in device efficiency.