Effect of deposition parameters on the properties of TiO2 thin films prepared by spray pyrolysis

Titanium dioxide (TiO2) thin films had been deposited onto glass substrates at various substrate temperatures by spray pyrolysis technique. X-ray diffraction analysis of deposited TiO2 films exhibited nanocrystalline nature and preferentially oriented along (101) direction. Scanning electron microscopy depicted that the films were uniform and adherent to the glass substrate. The field emission scanning electron microscopy (FE-SEM) films, exhibiting almost spherical shape of nanosized particles, was observed. The size of particles of 9.2 nm was observed from high-resolution transmission electron microscopy analysis. The decreased surface roughness observed in atomic force microscopy was due to the decrease in grain size with increased substrate temperatures. All films exhibited a transmittance of about 80 % in the visible region. The direct band gap values were from 2.1 to 3.6 eV by increasing substrate temperature. The photoluminescence spectra measurements indicated that the intensity of emission peaks significantly varies with substrate temperature. Further, these TiO2 films showed effective antibacterial activity against tested pathogens. Photocatalytic activity of the TiO2 thin film was studied using an organic dye, methylene blue, under solar irradiation.