Electrochromic imaging with polymer electrolyte having high-temperature-dependent conductivity

Space-selective electrochromic imaging was successfully performed with a novel polymer electrolyte composed of poly(vinylbutyral) (PVB), poly(ethyleneglycole) (PEG) and tetra-butylammonium perchlorate (TBAP). The spreading of the electrochromic image is a shortcoming when the image is space-selectively formed by electrochemical reaction. This is due to a cell formation between colored and uncolored parts through an ionic conductor. In order to inhibit the spreading, it would be effective to apply a polymer electrolyte with very low ionic conductivity at room temperature to the imaging system. Based on this, we designed the polymer electrolyte to have a large difference in ionic conductivity between high and low temperatures. This polymer electrolyte enables writing and erasing at a high temperature due to high ionic conductivity, and the image is to be preserved without change in ambient temperature due to very low ionic conductivity. In fact, space-selective image was successfully formed on the electrochromic device with the present polymer electrolyte at 100 °C, and was stable without change for more than a week when the device was kept at 20 °C.