Spray pyrolysis synthesis of high-transmittance ZnS thin films

Zinc sulfide (ZnS) thin films were successfully synthesized using the spray pyrolysis technique, systematically exploring the structural, compositional, and optical properties across substrate temperatures ranging from 275 to 400 °C. X-ray diffraction (XRD) analysis revealed a critical transformation from polycrystalline structures with residual ZnO phases in as-deposited samples to pure hexagonal wurtzite ZnS upon thermal annealing at 375 °C. Raman spectroscopy confirmed the wurtzite structure, with characteristic phonon modes detected at 288 cm⁻¹ (TO), 344 cm⁻¹ (E1LO), and 553 cm⁻¹ (2TO). Optical transmittance measurements demonstrated a progressive enhancement in visible light transparency, reaching maximum values of 91.5%, 95.2%, and 96.8% at deposition temperatures of 275 °C, 357 °C, and 400 °C, respectively. The observed structural evolution and optical properties suggest that thermally processed ZnS thin films hold significant potential for optoelectronic applications, particularly as buffer and electron transport layers in photovoltaic devices.