Magnetron sputtered tungsten oxide films for electrochromic applications

Electrochromic tungsten oxide (W03) has potential applications in smart windows, switchable mirrors, display devices, and photo-electrochromic devices. The thin films of tungsten oxide with thicknesses of approximately 150 and 200 nm, measured using an optical profilometer, are prepared by reactive magnetron sputtering. The optical properties of the W03 films are characterized using ultraviolet-visible spectroscopy. A change in transmittance is also measured. A reversible color change from transparent to blue is observed during Cyclic Voltametry (CV) measurements. The coloration/bleaching reaction shows a good response in an aqueous acid electrolyte. The 150 nm film shows a better response while the 200 nm film reveals an unbalanced charge transfer indicating incomplete deintercalation of ions. These results can contribute to the development of EC based applications.