A comparison of the behaviors of tungsten trioxide and anodic iridium oxide film electrochromics in a nonaqueous acidic medium

The performance of anodic iridium oxide film (AIROF) and WO3 electrochromic electrodes was tested in a water-free perchloric acid/dimethylsulfoxide solution. WO3 could be colored and bleached electrochemically to nearly the same extent as in water solutions, albeit much more slowly. By contrast, no electrochromic effect could be produced with AIROF electrodes. This proves that the electrochromic processes for these two materials are fundamentally different and that a simple proton-electron injection mechanism cannot account for AIROF electrochromism.