A layer-by-layer film developed by researchers at the Massachusetts Institute of Technology could harvest sunlight and release heat on demand hours or days later.
The thermal fuel polymer film includes three distinct layer, four to five microns in thickness for each. Cross-linking after each layer enables a tunable thickness.
Chemically-based storage materials, known as solar thermal fuels (STFs), remain stable in either of two different configurations. When exposed to sunlight, the light's energy moves the molecules into their “charged” configuration, and they can stay that way for long periods. Then, when triggered by a very specific temperature or other stimulus, the molecules snap back to their original shape, giving off a burst of heat in the process.
The MIT team created the heat-storing material in the form of a thin film, which can be incorporated into many different materials, including glass or even fabric.
Possible applications include clothing that releases heat and car windshields that use the material to store solar energy and then release it as a burst of heat to melt away a layer of ice.
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