ELECTROCHROMIC PROPERTIES OF TUNGSTEN TRIOXIDE THIN-FILMS PREPARED BY PHOTOCHEMICAL VAPOR-DEPOSITION

Electrochromic tungsten trioxide thin films were prepared by a photochemical vapor deposition. The source material was tungsten carbonyl. A 6 W low pressure mercury lamp was used as a light source. Amorphous tungsten trioxide thin films were obtained at a substrate temperature of 200-degrees-C. The UV radiation enhances the oxidation of tungsten, in addition to the acceleration of the deposition of the films. Reduction and oxidation of the films in a 0.3M LiClO4 propylene carbonate solution resulted in desirable changes in optical absorption. The bleaching time was short compared to the amorphous CVD film. Coulometry indicated that the coloration efficiency was 222 cm2 . C-1.