Influence of Ti and Zn Dopants on Structural Properties and Electrochromic Performance of Sol-Gel Derived WO3 Thin Films

The influence of different transition metals doping (Ti and Zn) on structural properties and electrochromic adjustment and performance of sol-gel derived WO3 thin films was conducted and investigated. Ti-doped WO3 and Zn-doped WO3 thin films were deposited onto F-doped tin oxide (FTO) substrates using spin coating technique. Tungsten powder, Titanium butoxide and zinc acetate dehydrate were used as starting precursors. The as-deposited films were annealed at 500 °C for 2 h. The effect of Ti and Zn doping on structural, surface morphologies, optical properties of the films were examined using X-ray diffractometer, scanning electron microscope and UV-VIS spectrophotometer. The XRD analyses suggest that the crystalline of WO3 can be identified as a monoclinic WO3 structure. XRD results additionally indicate the existence of ZnWO4 structure in the Zn-doped films, which is clearly observed by SEM. The optical measurement of all films indicate good transparency in the visible region and near infrared region with more than 60% in transmittance. In addition, It was found that the electrochromic performance of WO3 can be enhanced by small doping concentration of titanium due to structural modification of the films caused by close ionic radius of Ti to W rather than that of Zn.