The effect of palladium doping on optical and electrochromic properties of sol-gel deposited tungsten oxide films

In this paper, palladium doped-tungsten oxide thin films have been prepared by sol-gel deposition method. In this way, tungstic ‎acid obtained by Kudo method was doped by different amounts of palladium chloride and were deposited on transparent ‎conductive oxide of ITO/glass by dip-coating method. The effect of Pd doping on morphology and optical properties as well as ‎electrochemical characteristics were investigated using scanning electron microscopic (SEM), UV-Vis spectroscopy, cyclic ‎voltammetry (CV) and optical transmission at 632.8 nm constant wavelength. SEM revealed that the WO3 layers have a thickness ‎of 450-500 nm were obtained with smooth and uniform surfaces. Also, the transparency of layers was above 85%, for which the ‎optical gap was decreased by increasing Pd content. The voltammetry results showed that the doped palladium reduces the ‎catholic potential, increases the chemical stability of tungsten oxide thin films, stabilizing the electrochemical performance of ‎these layers. Finally, we measured the electrochromic response time and the corresponding electrochemical efficiencies