Tailoring the Optoelectronic Behavior of Hydrothermally Deposited Sb2S3 Thin Films through Controlled Growth and Thermal Annealing

Antimony trisulfide (Sb ₂ S ₃ ) is a promising semiconductor for optoelectronic applications owing to its suitable direct band gap, high absorption coefficient, and compatibility with low-temperature solution processing. In this work, Sb ₂ S ₃ thin films were prepared by a hydrothermal method, and the effects of ethylenediaminetetraacetic acid disodium salt (EDTA-2Na)-assisted growth and post-annealing temperature on their structural, optical, surface, and photoelectrical properties were systematically studied. X-ray diffraction (XRD) results confirmed phase pure orthorhombic Sb ₂ S ₃ and showed that EDTA-2Na promotes stronger (020) preferential orientation and improved crystallinity. Scanning electron microscopy (SEM) analyses revealed denser and more homogeneous surface and cross-sectional morphologies in EDTA-2Na-assisted films. Ultraviolet-Visible (UV-Vis) transmission measurements indicated slight band gap narrowing after EDTA-2Na incorporation, while Energy-Dispersive X-ray Spectroscopy (EDS) analysis demonstrated improved compositional stability. Contact angle measurements further suggest enhanced surface uniformity and higher surface energy for EDTA-2Na-assisted samples. Among the investigated conditions, annealing at 300°C under Ar provided the optimum balance between crystallization and defect control. The EDTA-2Na-assisted film annealed at 300°C exhibited the best device performance, achieving a responsivity of 28.90 mA W ^− 1 and a detectivity of 9.42×10 ¹⁰ Jones under 365 nm illumination, together with stable and reproducible photoresponse in the Ultraviolet-visible (UV-Vis) region. These results indicate that controlled growth chemistry and optimized thermal treatment are key parameters for improving the performance of hydrothermally deposited Sb ₂ S ₃ thin-film photodetectors.