Electrochromic devices employing methacrylate-based polymer electrolytes

Poly(ethyl methacrylate) (PEMA)- and poly(2-ethoxyethyl methacrylate) (PEOEMA)-based polymer gel electrolytes with entrapped solutions of lithium perchlorate in propylene carbonate (PC) were prepared by direct, UV-initiated polymerization. The electrolytes were studied using electrochemical methods and they exhibit good ionic conductivity (up to 0.7 mS cm −1 at 20 °C) as well as electrochemical stability up to 2.5 V vs. Cd/Cd 2+ (5.1 V vs. Li/Li +) on gold electrode. The electrolytes have thermal stability up to 125 °C. The electrolytes were successfully tested as ionic conductors in the electrochromic device FTO/WO 3/Li +-electrolyte/V 2O 5/FTO using coupled optoelectrochemical methods to discuss the relationship between the electrolyte composition and parameters such as change of transmittance, response time and stability. The transmittance change Δ τ was found to be 30–45% at 634 nm.