5458
Chemistry and Nanotechnology
Physics and Electro-Optics

High-Performance Electrochromic Devices (No. T4-1380)

Lead Researcher: Prof. Milko van der Boom

Summary

High performance electrochromic materials that exhibit a practical combination of low-voltage operation and efficient color switching as well as long-term stability have been developed by the group of Prof.< size=2 face=Verdana> van der Boom. Electrochromic materials undergo reversible optical changes in response to external applied voltage, which results in a reversible color change. This property enables electrochromic materials to be used for a wide range of applications, including smart glass, electrochromic mirrors, color displays, electrochromic paper, electrochromic goggles and motorcycle helmet-visors.  The presented technology utilizes electrochromic coordination complexes and offers an easy and cost-effective coating process, diverse color palette, intense coloration, short switching time and long term stability.

Applications
  • Smart windows/smart glass
  • Color displays and electrochromic paper
  • Smart mirrors
  • Electrochromic lenses, goggles and helmet-visors
  • Wearables
Advantages
  • Fully reversible optical responses
  • Very high coloration efficiency
  • Color tuning via molecular design
  • Low response time (up to 400 ms for >95% switching)
  • High switching efficiency (efficient switching at 100 ms) and stability
  • Uniform coating technique, applicable for large scale surfaces
Technology's Essence

The invention includes the design, synthesis, and electrochemical switching of optical properties of molecular coatings for electrochromic devices. Fully reversible optical responses occur with variation of the oxidation state of metal organic complexes. The low-voltage operation of <1.5 V combined with the high stability makes this system an ideal candidate for multiple electrochromic device applications. A diverse color palette is available by simple synthetic means and the coloration intensity is highly adjustable owing to the coating technique. Moreover, our design approach allows the incorporation of multiple complexes into a single coating. With each complex individually accessible at a different voltage, such coatings can display multi-color states.

Electrochromic devices (ECDs) bearing a surface area of 6 cm × 6 cm. Top: Schematic presentation of the ECDs based on working electrodes. Middle: Photographs of the colored and bleached states of the ECDs C. Bottom: Chronoamperometric stability measurements.