Investigation of the structural and optical properties of Co-doped TiO2 thin films

In this work, the structural and optic properties of doped and undoped TiO2 films were obtained by sol-gel technique.Thin films of TiO2 were coated on glass substrates. The solution used was a mixture of titanium (IV) isopropoxide, ethanol, hydrocloric acid and deionized water. The films were prepared by dipping the substrates into the solution. Each time the substrates were withdrawn from the solution with the speed of 0.52 cm/s and multilayer films were prepared. After each coating the film was allowed to dry at 120 oC for 30 minutes and than sintered 2 hours at 650 oC.The structure analyses of the crystalline films were studied through XRD. According to the experimental results, TiO2 films showed anatase phase.Morphology of the films was measured by scanning electron microscopy (SEM) and atomic force microscopy (AFM). It was observed that increasing cobalt concentration increased the pore structure and particle size of TiO2 films.Optical properties of the films were obtained by using UV spectrometer. Using absorption spectrum, the band gap of the films was determined. It was determined that increasing cobalt concentration decreased the band gap of TiO2 films.