Low-cost fabrication of WO3 films using a room temperature and low-vacuum air-spray based deposition system for inorganic electrochromic device applications

Abstract We report the deposition of tungsten oxide (WO3) thin films on fluorine-doped tin oxide (FTO) and indium-doped tin oxide (ITO) glass substrates by using a room-temperature deposition system based on low-vacuum air-spray for the fabrication of inorganic electrochromic windows. The structure of the WO3 films was characterized using X-ray diffraction, and the surface morphology and film thickness were investigated using scanning electron microscopy and atomic force microscopy. The color of the prepared WO3 films changed from slight yellow to dark blue under applied voltages, demonstrating electrochromism. The WO3 film coated FTO glass exhibited a large electrochromic contrast of up to 50% at a wavelength of 800 nm. The electrochemical properties of the films were examined using cyclic voltammetry and chronocoulometry.