Electrochromic behavior of the α-WO3 thin films grown by thermal evaporation

Amorphous tungsten trioxide (α-WO3) thin films were deposited by thermal evaporation on an ITO coated glass substrates held at room temperature. The electrochromic behavior of WO3 thin film was investigated using electrochemical technique with H+ ions intercalated/de-intercalated. The diffusion coefficient of the H+ ion in α-WO3 thin film was ∼10-13 - 10-14 cm2/sec. The transmittance of the α-WO3 thin film decreases with the increase in intercalation of ions and the coloration efficiency is 31 cm2/C and 37 cm2/C for 650 nm and 1000 nm wavelength, respectively. The α-WO3 thin films show faster switching responses with intercalated H+ ions for 650 nm wavelength. (author)