Abstract
TiO2 nanocrystalline films were successfully deposited onto glass substrates by sol-gel method at different annealing temperatures (0, 300,400,500 and 600 degrees C). The effect of annealing process on structural, optical and photocatalytic Activity were mainly investigated. The structural analysis shows that the un-annealed and films annealed at 300 degrees C are amorphous, and after annealing from 400 degrees C to 600 degrees C results in polycrystalline TiO2 thin films. XRD showed the structural orientation of the films especially in (101) plane corresponding anatasa phase of TiO2.Crystallite size and films thickness increase gradually with annealing temperature due to the decrease in concentration of lattice imperfections and enhancement of nucleation and coalescence. TiO2 have highly transmittance in the visible range and the optical band gap value of the TiO2 thin films decreases from 3.95 to 3.65 eV with the annealing temperature increment as a result of the improved crystalline structure. The refractive index as a function of wavelength was determined. The photocatalytic activity of TiO2 shows that the degradation under sun light was high comparing to UV. Thus, the annealing effects on the physical properties of TiO2 thin films will be useful for the formation of highly crystalline and high-transmittance TiO(2 )thin films for solar cell application.