Effect of Deposition Temperature on the Electrochromic Properties of Electron Beam-Evaporated WO3 Thin Films

Tungsten oxide (WO3) thin films were deposited on ITO/glass substrates using the electron beam evaporation technique. The WO3 films were grown on substrates at temperatures varying from room temperature (RT) to 240 degrees C. The structural characterization and surface morphology were examined using X-ray diffraction (XRD) and a field emission scanning electron microscope (FE-SEM). The electrochromic properties of WO3 thin films were investigated using cyclic voltammograms (CVs) and in situ transmittance measurements, which were performed on WO3 thin films immersed in an electrolyte of 1M LiClO4 in propylene carbonate (PC). An amorphous 510-nm-thick WO3 film heated at RT exhibits the maximum transmittance variation (Delta T%) of 61.8% between the bleached state and the colored state, with a Delta OD of 0.739, Q of 17.31 mC/cm(2) and eta of 42.69cm(2)/C at a wavelength (lambda) of 550nm.