Nara Technology Institute Develops Highly Efficient Electrochromic Material Expected to Contribute to Energy Conservation

A Japanese research group led by associate professor Takuya Nakashima and professor Tsuyoshi Kawai at the Graduate School of Materials Science at the Nara Institute of Science and Technology announced on December 7, 2012, that they succeeded in developing an ultra-efficient decolorable electrochromic molecular material. The efficiency of the new decolorable technology is 20 times higher than that long thought to be ideal.

Electrochromic molecules, which switch between states of coloration and decoloration when electrically charged, can be used to control brightness of light and therefore are expected to serve an important role in energy conservation, such as for improving air conditioning efficiency. However, they also have disadvantages, including the coloring or decoloring process requiring electricity, the efficiency of which has not improved as expected. The newly developed electrochromic molecular material requires electricity only for the decoloration process and the efficiency of this process is high, allowing an improvement in energy efficiency over 10 times as high as that of existing technologies.

The research group had already reported a super highly sensitive photochromic molecule with a 100% coloring sensitivity. The group made the discovery of its new electrochromic molecule, which can take on color with light and be made to lose color with high efficiency, by adding a process that facilitates electrochemical reactions in this photochromic molecule. Professor Kawai set the stage for this finding with his discovery of photochromic molecules 20 years ago.