Electrochromic properties of tungsten trioxide (WO3) layers grown on ITO/glass substrates by magnetron sputtering

Abstract WO 3 layers were grown on glass substrates by pulsed DC magnetron sputtering. A series of WO 3 layers were deposited at different growth powers changing from 0.7 kW to 1.5 kW. The effects of the growth power on the electrochromic properties of WO 3 thin films were investigated. By using X-ray diffractometry, it was obtained that WO 3 thin films had amorphous crystal structure. Electrochromic measurements were studied by cyclic voltmeter, chronoamperometry and lifetime cycle measurements. An increase in the coloration efficiency from 55 cm 2 /C to 87 cm 2 /C was found with decreasing growth power. Moreover, the decrease in the growth power leads to a decrease in the coloration and bleaching times from 11.75 s to 5.93 s and from 17.35 s to 9.69 s, respectively. All the changes in the coloration efficiency and coloration and bleaching times with a decrease in growth power could be explained by the kinetics of electrochromic reactions. This is associated with the density of the WO 3 thin films which is increasing from 7.06 g/cm 3 to 7.59 g/cm 3 by increasing the growth power from 0.7 kW to 1.5 kW.