Physical Properties of Cu, Co, and Zn doped TiO2 nanocrystalline thin films prepared using spray pyrolysis

This research focuses on the preparation and characterization of TiO2 thin films in both pure and doped forms. The films were deposited onto glass substrates using the spray pyrolysis technique. The pure film was doped with Cu, Co, and Zn at a constant ratio of 3 wt% in the starting solution. XRD analysis revealed the presence of anatase TiO2 phase in all deposited films. The crystallite size of the pure film was determined using Scherer's equation and found to be 8.3 nm, while the doped films had sizes of 11.3 nm (Cu), 13.8 nm (Co), and 11.3 nm (Zn). SEM images showed the formation of fine grains with a normal distribution, with average sizes of 27.02 nm (pure), 39.37 nm (Cu), 33.4 nm (Co), and 29.37 nm (Zn) for the respective doped TiO2 films. EDX analysis confirmed the presence of the dopant elements in the deposited films. It was observed that all films exhibited a direct band gap, with a value of 3.79 eV for the pure film, which slightly decreased upon doping. Additionally, various optical constants such as refractive index, extinction coefficient, dielectric constant, relaxation time, and optical mobility were estimated and presented in this study.