Creation of Organic-Metallic Hybrid Polymers with Electrochromic Properties and the Device Application to Displays

Electronic paper has received much attention as next generation display to contribute energy-and resource-saving, because electronic paper can hold images even after the power is turned off unlike conventional displays such as liquid crystalline one. Electronic books bearing an electrophoretic type of electronic paper are already commercially available, but the colorization is becoming one of significant subjects in electronic paper. Electrochromic type of electronic paper is expected to achieve the colorization, since electrochromic materials can show various colors. Recently, we found organic-metallic hybrid polymers formed by the complexation of metal ions as Fe (II) or Ru (II) with bis (terpyridine) ligands have specific colors based on metal-to-ligand charge transfer (MLCT) absorption and show electrochromic properties, which is caused by electrochemical redox of the metal ions. Interestingly, multicolor electrochromic change is also possible by the introduction of two types of metal ions into the polymer. In addition, solid-state electrochromic displays using the organic-metallic hybrid polymers was fabricated successfully. The new electrochromic materials and the devices have possibility to be applied to color electronic paper in the future.