Synthesis and electrochromic properties of nanocrystalline WO3 thin films

Abstract In the present work, Electron beam evaporated tungsten trioxide (WO3) thin films were prepared under an oxygen partial pressure of 2 × 10−4 mbar by maintaining the well cleaned Corning 7059 glass, Silicon and Indium Tin Oxide (ITO) coated glass substrates at 6–8 °C and room temperature (RT). As deposited films continued subsequently for annealing at 400 °C in air about 2 h and films were systematically characterised for their structural, morphological, vibrational, optical and electrochromic properties. XRD studies reveal that the prepared WO3 films are completely monoclinic structure with different orientations. The morphological images show that the surface is uniform, homogeneous and the grain sizes are comparable with the XRD data. The optical transmission and energy bandgap of the films increases with the lowering of temperatures to 6–8 °C. Lastly, it is commence that coloration efficiency at wavelength of 550 nm for annealed films deposited at 6–8 °C is maximum, 72.60 cm2C-1.