Polycrystalline tungsten oxide (WO3) thin films were prepared using the spray pyrolysis method at various substrate temperatures (200, 250, 300, 350, and 400 °C) on the quartz substrate. The X-ray diffraction pattern showed polycrystalline films with a monoclinic structure. Analysis using field-emission scanning electron microscopy revealed a porous fibrous reticulate morphology. The EDs results reflected the formation of stoichiometric films with optimum stoichiometry at 350 °C substrate temperature. The transmittance spectra at the 300–1100 nm spectral range reached about 55% with a direct band gap of 3.3 eV. The optical constant was also estimated and analyzed, where optical conductivity was found to be about 5.4669 x1014 (Ω cm)-1 while, 2.09 eV was the value of Urbach energy at 350 oC.
