Flexible electrochromic windows: a comparison using liquid and solid electrolytes

In the present work, two electrochromic devices (or electrochromic windows) based on intrinsically conducting polymers were assembled and characterized. For both devices, the materials used on the assembling were the same except for the electrolyte layer. In the first, we used as electrolyte a propylene carbonate solution and in the second the elastomer poly(epichlorohydrin-co-ethylene oxide), both containing LiClO4. The conductivity of the liquid electrolyte (10-3 S cm-1) is approximately two orders of magnitude higher than for the solid electrolyte and we obtained very good electrochromic properties in both cases. The calculated electrochromic efficiency at 640 nm was 700 C cm-2 for the liquid electrolyte device and 360 C cm-2 for the solid state device. Solid state electrochromic windows have been investigated and some of its advantages over windows with liquid electrolytes are discussed.