Electrochromic devices with solid electrolytes based on natural polymers

Solid-state electrochromic devices (ECDs) are of considerable technological and commercial interest because of their controllable transmission, absorption, and/or reflectance. For instance, a major application of these devices is in smart windows that can regulate the solar gains of buildings and also in glare attenuation in automobile rear view mirrors. A typical electrochromic device has a five-layer structure: GS/TC/EC/IC/IS/TC/GS, where GS is a glass substrate, TC is a transparent conductor, usually ITO ( indium tin oxide) or FTO (fluorine tin oxide), EC is an electrochromic coating (typically WO3, Nb2O5, Nb2O5: Li+ or Nb2O5 - TiO2), IC is an ion conductor (solid or liquid electrolyte), in our case polymeric films based on natural polymers like starch or cellulose, and IS is an ion storage coating (typically CeO2 - TiO2, CeO2 - ZrO2, or CeO2 - TiO2 - ZrO2). This paper describes properties of two electrochromic devices with a WO3/natural-polymer-based electrolyte/CeO2 - TiO2 configuration.