Characteristics of electrochromic device with polypyrrole and WO3

The characteristics of electrochromic films (WO3, V2O5) prepared by sol-gel-spin coating and a vacuum evaporation process were compared to identify a new application of an electrochromic display. Polypyrrole films were prepared by electropolymerization in a pyrrole solution, acetonitrile, and TEPS (tetraethylammonium p-toluenesulfonate). The liquid electrolyte was prepared using LiClO4, propylene carbonate, polymethylmetacrylate, and ethyl acetate. The optical modulation of the electrochromic device was measured as the LiClO4: PMMA weight ratio changed from 10:3 to 10:5. The highest optical modulation value was when the LiClO4: PMMA weight ratio was 10:4. Each type of film was analyzed using a four-point probe, a differential scanning calorimeter (DSC), an X-ray diffractometer (XRD), and a UV-vis spectrophotometer (DR/4000H). The ESCA spectra of the WO3 films showed that the tungsten oxidation number decreased in a coloration state. (C) 2001 Kluwer Academic Publishers.