Preparation and Characterization of WO3 Electrochromic Films Obtained by the Sol-Gel Process

Abstract

<em>Tungsten trioxide (WO₃) films have been coated on indium thin oxide (ITO) conductive glass substrate, using aqueous solution of peroxotungstic acid (PTA) by the sol-gel dip coating method. X-ray diffractometery (XRD) analysis confirmed monoclinic and triclinic structure for the film and powdered WO₃ respectively. Fourier transforms infrared spectroscopy (FT-IR) exhibited the structure of peroxotungstic acid. The SEM micrograph of annealed species revealed micro cracks due to decrease of density and contraction of layers. Energy- dispersive X-ray (EDX) study determined 1:3 ratios of oxygen and tungsten atoms in the prepared films at heat treatment temperature higher than 200ºC. The electrochromical behavior was investigated in 1M HCL solution employing cyclic voltammetry. It was found that WO₃ films demonstrated good reversibility at 200 ºC.</em>