Microstructures, optical and electrical properties of TiO2 thin films prepared by unconventional sol–gel route

Band gap lowering in TiO2 is usually done by adding impurity to it. In this paper a new approach is adopted to make TiO2 thin films by unconventional sol–gel method starting with TiO2 powder reagent. The prepared gel is deposited on the microscopic glass slide by doctor blade technique. The prepared films were then subjected to X-ray diffraction for structural and microstructural analysis. Different optical parameters like, thickness, refractive index, extinction coefficient, transmittance and absorbance etc. are calculated and finally band gap of the samples are estimated and are presented in this work. Both the refractive indices and band gap are found to be lower than that reported earlier. Scanning electron microscope image shows dense and uniformly distributed TiO2 particles. The quality and novelty of this paper is that, the micro size nano thick film is prepared from powder reagent unlike other published papers and novelty lies in its very low band gap as direct transition is more favorable for TiO2 nanoparticles in anatase phase.