Design Engineering

Researchers develop new “smart” window material



When incorporated into a window, the material will have the ability to control both heat and light from the sun.

There may be no need for window coverings to shade us from the sun’s heat and light. Researchers at the University of Texas at Austin have invented a new flexible smart window material. When incorporated into windows, sunroofs or even curved glass surfaces, the material will have the ability to control both heat and light from the sun.

Cockrell School of Engineering - flexible smart window material

Photo courtesy of Cockrell School of Engineering

Delia Milliron, an associate professor in the McKetta Department of Chemical Engineering, and her team developed a low-temperature process for coating this new smart material on plastic.

The team demonstrated a flexible electrochromic device, which means a small electric charge (about 4 volts) can lighten or darken the material and control the transmission of heat-producing, near-infrared radiation.

This process generates a material with a unique nanostructure, enhancing the coloration process and can be switched between clear and tinted quickly using less power.


The new electrochromic material has an amorphous structure and the new process yields a unique local arrangement of the atoms in a linear, chain-like structure.

The new linearly structured material, made of chemically condensed niobium oxide, allows ions to flow in and out more freely. As a result, it is twice as energy efficient as the conventionally processed smart window material.

It has been difficult to engineer amorphous materials to enhance their performance.

“There’s relatively little insight into amorphous materials and how their properties are impacted by local structure,” Milliron said. “But, we were able to characterize with enough specificity what the local arrangement of the atoms is, so that it sheds light on the differences in properties in a rational way.”

Graeme Henkelman, a co-author on the paper and chemistry professor in UT Austin’s College of Natural Sciences, explains that determining the atomic structure for amorphous materials is far more difficult than for crystalline materials. The researchers were able to use a combination of techniques and measurements to determine an atomic structure that is consistent in both experiment and theory.

“Such collaborative efforts that combine complementary techniques are, in my view, the key to the rational design of new materials,” Henkelman said.

The team believes that the their findings may help when it comes to deliberate engineering of amorphous materials for other applications such as supercapacitors.

“We want to see if we can marry the best performance with this new low-temperature processing strategy,” Milliron adds.

The research team is an international collaboration, including scientists at the European Synchrotron Radiation Facility and CNRS in France, and Ikerbasque in Spain. Researchers at UT Austin’s College of Natural Sciences provided key theoretical work.


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