Electrochemically and Thermally Switchable Optical Coating

Physical Sciences : Chemical

Available for licensing


  • Delia Milliron, Ph.D. , Chemical Engineering
  • Gabriel LeBlanc, Ph.D.
  • Amy Bergerud

Background/unmet need

A variety of materials possess contrasting optical properties under different conditions. One industrial application for this property is in the area of "smart windows," though other applications such as sensors and optical filters can be envisioned. Two general classes of "smart windows" exist: electrochromics and thermochromics.

Electrochromic films undergo changes to their optical properties under electrochemical bias. While this provides optical contrast on demand, the system must be turned-on in order to function. This means that the energy efficiency of these system depends on the user or on an expensive, system-wide control platform.

Thermochromic materials, on the other hand, do not require any user or control platform. These materials operate by undergoing a material change at a critical temperature. While thermochromic materials provide "automatic" or intrinsic control, the film cannot be operated on demand. Additionally, thermochromic materials only function at specific temperatures dictated by the specific material. For example, vanadium dioxide has been suggested as a material for thermochromic applications, but the optical changes occur at too high a temperature (68°C) to be practically relevant.

Invention Description

This invention is a concept for combining the versatility of an electrochromic system with the intrinsic functionality of thermochromic materials. The invention utilizes a thermochromic material (vanadium dioxide) as the active component on conductive glass that can be electrochemically tuned or triggered below the intrinsic thermochromic threshold of the native material.


  • Independent electrochromic or thermochromic behavior
  • On-demand or automatic optical transformation at user-defined temperatures


  • Rapid electrochemical modulation in the NIR region of the electromagnetic spectrum
  • Intrinsic thermal modulation in the NIR region
  • Tunable thermal modulation

Market potential/applications

"Smart windows" 

Development Stage

Proof of concept