Structural and electrochromic properties of WO3-doped TiO2 thin films prepared by peroxo sol-gel method

WO3-doped titanium oxide (TiO2: W) films were prepared by peroxo sol-gel process. Ti(OBu ")(4) and metallic tungsten powder, as raw materials, were dissolved in H2O2 solution, respectively. Two solutions were mixed in a certain ratio for preparing TiO2: W films. The effect of heat treatment conditions on the structure of the films was investigated by XRD and TEM. The experimental results showed that with heat treatment temperature increasing from 250 to 550 degrees C, the structure of the TiO2: W films changed from amorphous to anatase, and to a mixture of anatase, rutile and brookite. The TiO2: W films, after heat treatment at 450 degrees C for 1 h, were found to possess a nanocrystalline structure. Effects of the addition of WO3 on the electrochromic properties of TiO2 films were studied by cyclic voltammetry and in situ monochromatic transmittance measurements.