Multicolor electrochromic behavior of polyaniline composite films combined with tungsten trioxide

Abstract

Abstract The electrochromic behavior of polyaniline‐poly(vinyl alcohol) composite films (CPAn‐PVA) combined with an electrochemically synthesized tungsten trioxide film (WO 3 ) was investigated in LiClO 4 CH 3 CN aprotic non‐aqueous solution. The combination was achieved by chemical deposition of CPAn‐PVA on WO 3 . The combined film shows an electrochromic behavior roughly identical with the sum of the behaviors of each component material. The color change of the combined film from blue to green in the cathodic region is of lower contrast in comparison with that expected from the combination. From ex‐situ FT‐IR spectroscopy it became clear that the weakened electrochromic change is due to some interaction between polyaniline and WO 3 . However, this interaction also activates the electrochemical oxidation process of polyaniline. As a result, the combined film shows a color change owing to the oxidation of polyaniline applying much lower potential than for CPAn‐PVA. This suggests the possibility of construction of electrochromic devices with high electrochemical stability operating at low potentials.