Phase tuning and optoelectronic properties of solution-processed Ba-doped Sb2S3 chalcogenide thin films

Abstract

Antimony ethyl xanthate (1) and barium isopropyl xanthate (2) were synthesised and used as single-source precursors (SSPs) to prepare solution-processed Ba-doped Sb₂S₃ films. Ternary Sb_2-xBa_xS₃ films (0 ≤ x ≤ 100) mol% Ba and (BaS) film were synthesised by spin-coating the solution on glass substrates and annealing at 550 °C for 1.5 h, and (Sb₂S₃) films were annealed at 250 °C for 1 h. Compositional, structural, morphological, optical, and electrical properties were characterised by p-XRD, EDX, ICP, Raman spectroscopy, SEM, TEM, and resistivity measurements (ρ). (p-XRD) reveals that the (Sb₂S₃) film has an orthorhombic structure with a dominant (210) orientation. Ba incorporation induced a progressive phase transition; the (103) orientation was promoted at intermediate doping, and it was modified into a cubic (111) BaS phase at higher doping levels. SEM shows lamellar morphology at 50 mol% Ba. The existence of Sb, Ba, and S was verified using (EDX) and (ICP), confirming intact decomposition and phase purity, consistent with the X-ray diffraction (XRD) and Raman results. The optical bandgap (E_g), estimated from Tauc plots, ranged from 1.7 eV (Sb₂S₃) to 3.85 eV (BaS), indicating tunable optoelectronic properties. Resistivity increased with Ba content. (BaS) exhibited a raised resistivity (18.4 Ω cm), showing reduced conductivity compared to (Sb₂S₃).