Preparation and Characterization of Sol-Gel Spin Coated Nanocrystalline TiO_2 Films

摘要

Titanium dioxide (TiO_2) thin films with nanocrystallites have been prepared using sol-gel spin coating technique. HRTEM studies indicated that the films are composed of small grains having an average size of 20 nm. Transmittance spectra has been recorded for the spin coated TiO_2 films and red shift of absorption edge on annealing has been observed. The optical band gap determined using the transmittance spectra revealed that the band gap decreased from 3.71 to 3.19 eV on annealing. The photoluminescence measurements of the TiO_2 films showed a visible broad luminescence band in the region of 350 to 550 nm which can be ascribed to the presence of defect states.