Study of a Novel Electrochromic Device with Crystalline WO₃ and Gel Electrolyte

Most ECDs are coated with an electrochromic material on the transparent conductive oxide (TCO) substrate. A novel electrochromic device (ECD), having a variable optical performance, was prepared by using tungsten foil as a substrate in this study. It was found that the WO₃ discoloration layer, having a monoclinic phase crystalline structure made of 600 °C calcined, had optimum charge transmission performance with PADA gel polymer electrolyte. Ionic conductivity of PADA gel polymer electrolyte was 2.3 × 10^-3 S cm^-1 at -20 °C, and it was possible to help Li⁺ to implement embedding and extraction from WO₃ even in low-temperature conditions. The colored time (t_c) and the bleached time (t_b) of the electrochromic device were 15 s and 26 s, and it showed yellowish-brown in the colored state and navy blue in the bleached state. The ECD (WO₃-600) exhibited good cycle stability reach at least 150 times.