Solar halo
A man cycles past the solar halo occurring in the sky of Kathmandu July 8, 2015. This weather phenomenon creates rainbows around the sun, and according to meteorologist, the halo is formed by the reflection of ice crystals. Reuters/Navesh Chitrakar

People could soon use sweaters that could increase temperature on command and cars that could clear ice on the windshield by releasing heat with the development of a new material capable of storing solar energy and releasing it when needed. A new transparent polymer film could be used in clothes and glass to harvest heat from the sun and save it for later use.

The research, published in Advanced Energy Materials, claims that the material can be used like a solar panel in saving solar energy but produces heat instead of electricity, which can be used by people.

Researchers at Massachusetts Institute of Technology (MIT) developed the polymer film with a chemical reaction that creates heat rather than power. The reaction allows the energy in the cloth or glass to be stored in "a stable molecular configuration" until it's ready to be released.

“This work presents an exciting avenue for simultaneous energy harvesting and storage within a single material,” Ted Sargent, a professor at the University of Toronto, who was not involved in the research, told MIT news. “The research is a major advance towards the practical application of solid-state energy-storage/heat-release materials from both a scientific and engineering point of view.”

The researchers designed the polymer film with materials called azobenzenes to make it capable of storing useful amount of heat and ensuring it could be manufactured easily and reliably. They enhanced the molecular configuration of azobenzenes to respond to light.

A tiny pulse of heat can easily stimulate azobenzenes to return to its original configuration and release more heat to be used. The team also improved its energy density, its ability to form smooth, uniform layers and its responsiveness to the heat pulse.

The researchers believe that the polymer film can widely be manufactured in the future as it was based on inexpensive materials. However, they noted that more work is needed before it is made commercially available.

The team is working on improving the polymer’s transparency as it has a slight yellowish tinge. They also aim to increase the heat level it can produce to 20°C from the current 10°C.