Microstructural, optical, and electrophysical properties of Sb2(SxSe1-x)3 films for solar cells

A new method was developed for fabricating high-quality Sb₂(S_xSe_1-x)₃ solid solution thin films using chemical molecular beam deposition from Sb₂Se₃ and Sb₂S₃ compounds. Structural analysis showed that increasing sulfur content (x = 0.1–0.35) reduced grain length and shifted XRD peaks to higher angles, indicating lattice contraction. Raman spectroscopy revealed a decrease in Sb–Se modes (110 and 151 cm⁻¹) and an increase in Sb–S modes (280 and 310 cm⁻¹). The optical bandgap expanded from 1.15 eV to 1.39 eV due to the smaller atomic radius and higher electronegativity of sulfur. The electrical conductivity (σ) dropped from 2.3 × 10⁻⁵ to 3.4 × 10⁻⁶ (Ω·cm)⁻¹ with increasing sulfur content. These variations are attributed to bandgap widening and composition-driven phase transitions in Sb₂(S_xSe_1-x)₃ thin films. Acceptor defects with activation energies of 89 meV and 107 meV were observed at lower sulfur ratios, while donor-type traps with energies of 308 meV and 450 meV dominated at higher x. These results demonstrate the tunable structural and electronic properties of Sb₂(S_xSe_1-x)₃ thin films for photovoltaic applications.