Hokkaido University Research Profiles

Nanotechnology / Materials

Electrochemically Responsive Organic Dyes

From electrochromism to multiple responses (fluorescence, circularity)

Based on cationic organic dyes, which allow easy control of color tone, we offer a group of materials that can respond in multiple ways, including fluorescence and optical rotation (circular dichroism). This technology is designed to suppress the decomposition process of reduced species, and the bi-stability of oxidized and reduced species is such that exchange does not occur, even when they are mixed.

Content of research

Electrochromism is a general term for compounds that change their color tone in response to changes in external electrical potential. As materials that can undergo reversible color changes, they are attracting attention as light control materials for smart windows and display functions for electronic paper. Materials of which not only the color tone, but also fluorescence, optical rotation (circular dichroism), etc. can be changed, enable tailor-made responses according to the application.
With this technology, we provide a group of substances with multiple responses based on cationic organic dyes of which the color tone can easily be controlled. The reduced species of cationic dyes are generally reactive, and the repeatability of the response is low, but with this technology, the decomposition process of the reduced species is suppressed by incorporating two cationic moieties. The bi-stability of the oxidized and reduced species, in which no exchanges occur, even when they are mixed, makes it possible to apply this technology to high-density recording materials.

Potential for social implementation

  • ・Smart windows
  • ・Anti-glare mirrors
  • ・Electronic paper
  • ・E-Ink
  • ・High-density recording devices

Appealing points to industry and local governments

The ultimate goal of this technology is to create an extremely high-density random-access memory that uses each molecule as a single bit. With the process, we have developed a number of electrochromism-responsive molecules, and have accumulated results with color tone, operating potential, and multiple response functions.