Titanium doping effects in electrochromic pulsed spray pyrolysed WO3 thin films

• Published in: Solid state ionics Vol. 179; no. 9-10; pp. 314 - 323
• Main Authors: BATHE, S, PATIL, P
• Format: Journal Article
• Language: English
• Published: 15.05.2008
• ISSN: 0167-2738
• DOI: 10.1016/j.ssi.2008.02.052

The influence of titanium doping on the electrochromic properties of WO3 thin films is studied. The systematics of different properties such as the structural phase change, the color-bleach kinetics, coloration efficiency, reversibility, stability, ion insertion/extraction capacity and change of W+ 6 states to W+ 5 states are observed to depend on doping concentration. The X-ray diffraction results reveal an amorphous phase at lower Ti concentration (2 and 6 at.%) and mixed WO3-TiO2 (monoclinic epsilon WO3 and rutile TiO2) phases at higher Ti concentration (10 at.%). The fibrous-reticulated morphology wanes and surface roughness increases as doping concentration increases. At higher Ti concentration (10 at.%), the film becomes completely granular and rough without fibrous-bridge-like network. The cycle stability, charge storage capacity and reversibility of the films are improved upon doping; however, coloration efficiency is decreases as Ti concentration increases. These results are discussed in terms of the effects of doping induced compositional inhomogeneity and disorder structure on the film properties.