Electrical and Optical Properties of Electrochromic Devices Utilizing Polymer Electrodes

We describe the preparation, electrical and optical analysis of prototype electrochromic electrodes and solid polymer electrolyes and complete switching devices. The electrodes studied are nickel oxide, nickel-manganese oxide, nickel-cobalt oxide, and tungsten-molybdenum oxide. These electrodes were found to be useful as active electrochromics or ion storage layers. Solid polymer electrolytes were synthesized from poly(ethylene oxide), a PEO, and poly(ethyleneimine). Also, an inorganic borate silicate glass was used as an ion conductors. The best performing devices were made with a-PEO electrolytes. Electrochromic devices were made using nickel oxide/tungsten-molybdenum, and nickel oxide/nickel manganese electrode combinations. Optical spectra as a function of voltage was obtained for each device. Our best nickel oxide/a-PEO/tungsten-molybdenum device showed the photopic transmittance (T_p) to be T_p(bleached)=0.79 and T_p(Colored)=0.39. The corresponding integrated solar transmittance was (T_s) to be T_s(bleached)=0.55, T_s(colored)=0.35. Our best nickel oxide/nickel-manganese device showed the photopic transmittance to be T_p(bleached)=0.71 and T_p(colored)=0.23. The corresponding integrated solar transmittance was T_s(bleached)=0.52, T_s(colored)=0.44. Better device properties are expected with improvements in the solid polymer electrolyte.