PREPARATION AND CHARACTERISTICS OF ALL SOLID-STATE ELECTROCHROMIC DISPLAY WITH CATION-CONDUCTIVE POLYMER ELECTROLYTES

The preparation and characterization of an electrochromic display device composed of cation-conductive polymer electrolyte were firstly described. Oligo(oxyethylene) methacrylate (MEO) was copolymerized with methacrylic acid alkali metal salts (MAA-M+; M+ = Li+, Na+, K+, Rb+, and Cs+). The obtained cation-conductive polymer electrolytes were used to construct an all solid-state electrochromic display device (ECD) composed of Prussian blue and WO3 as coloring layers. The ECD showed reversible coloring-bleaching cycling. The initial coloring rate was found to be essentially controlled by the cationic conductivity of the applied polymer electrolytes regardless of the cation species. Not only Li+ but also Na+ and K+ were confirmed to be effective for the reversible intercalation into and disintercalation from both WO3 and Prussian blue layers. Larger alkali metal cations showed better electrochromic characteristics because of a higher ionic conductivity. K+-conductive polymer electrolyte showed better characteristics than Li+- or Na+-conductive systems. Although Rb+ and Cs+ showed faster ion migration in the polymer electrolytes, their electrochromic characteristics were not as good because of a larger cation size than the cavity in the Prussian blue lattice.