Structural and Optical Properties of TiO2 Thin Films prepared by the Dip-Coating Method: Effect of Thickness and Annealing Temperature

In this work, the Sol-Gel dip-coating technique is used to report the effect of thickness and annealing temperature on structural and optical properties of TiO2 thin films. To study the effect of the annealing temperature, the prepared samples were annealed at different temperatures: 300, 400, and 500 °C for 1 h. By increasing the annealing temperature, an amelioration of the crystalline quality is observed. The best crystalline quality was obtained at 500 °C. Additionally, the band gap value Eg, evaluated from transmission spectra, does not vary with the increasing of the annealing temperature. All the films with different thicknesses present crystalize in the Anatase structure, and the crystallite size value does not practically change with thickness increase. It was also found that the TiO2 film band gap value decreases with the film thickness increase, demonstrating the possibility of band gap tuning by varying the TiO2 film thickness.