High-Quality Electrical Conductivity Co3S4 Thin Films Prepared by Spray Pyrolysis

This study reports the deposition of cobalt sulfide (Co3S4) thin films on glass substrates using the spray pyrolysis technique at a substrate temperature of 350 ± 5 °C. The precursor solution was prepared from cobalt chloride hexahydrate and thiourea dissolved in bidistilled water, while a small amount of acetic acid was added to enhance the solubility and stability of the solution. The structural properties of the deposited films were investigated using X-ray diffraction analysis, which confirmed the formation of polycrystalline Co3S4 with a cubic spinel structure (Fd-3m). The films exhibited a preferred orientation along the (113) crystallographic plane. The average crystallite size was found to be approximately 13.4 nm, with a calculated lattice parameter of 9.405 Å, indicating good crystalline quality. Optical characterization revealed that the films possess a direct optical band gap of 1.88 eV, suggesting strong absorption in the visible region, which is advantageous for optoelectronic applications. FTIR spectroscopy confirmed the presence of characteristic Co-S bonding vibrations, verifying successful sulfide formation. Electrical measurements showed a high electrical conductivity of about 9.60 x 104 (Ω x cm) – 1, indicating quasi-metallic behavior and efficient charge transport within the film. These combined structural, optical, and electrical properties demonstrate that spray pyrolysis is a simple, low-cost, and effective method for producing high-quality Co3S4 thin films, making them promising candidates for applications in optoelectronic devices, sensors, and energy-related technologies.