Metallo-supramolecular Polymer Applicable for Electrochromic (EC) Light Control Glass

　Light-control glass containing an electrochromic (EC) material is capable of electrically-driven variable color transparency and is attracting attention as a next-generation smart glass with applications to blinds and curtains. Conventional EC materials are generally composed of inorganic tungsten oxides and organic viologen materials. Recently, metallo-supramolecular polymers for EC materials have also been reported.
　Poly(Fe-btpyb) Purple (1) is one such metallo-supramolecular polymer containing Fe ions. It was developed by Higuchi et al.¹⁾ and its color changes based on the oxidation state (Figure 1). Fabrication of films using 1 is possible by a wet process, large-area, low-cost production of EC devices is expected using this material. The transparency of the glass at different wavelengths can be controlled an electrical voltage. EC devices fabricated using 1 have high color responsivity, and maintain their color thein the absence of an applied voltage (memory effect), which leads to low power consumption.