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Defrosting car windows is a frequent cause of headaches for winter drivers, but now researchers have come up with a solar-powered solution.

Thomas Schutzius at ETH Zurich in Switzerland and his colleagues have developed a nanoscale-thick coating made from gold and titanium dioxide. The tightly-packed gold particles are good absorbers of sunlight and embedding them in titanium dioxide enhances this absorption.

The material fights ice by concentrating solar energy into a small volume, raising the temperature at its surface and leading to rapid defrosting. This coat can be deposited on glass and other materials.

Crucially, the material is transparent, meaning it won’t cover up a driver’s windscreen. Creating a material that can both absorb energy from sunlight and let visible light pass through is difficult, says Schutzius, because the two properties are at odds with each other.

Clear windows

The researchers hope that their material could prove more environmentally friendly than existing methods for defrosting windows, such as using hot air from the engine.

“The main advantage of this approach compared to other defrosting techniques is that it does not require chemicals, electricity, or mechanical scraping,” says Schutzius.

Solar energy alone is enough to substantially remove ice or prevent it from forming, says Hadi Eghlidi, also at ETH Zurich. That makes it an environmentally-friendly alternative, he says.

The team is now focusing on using the material in windscreens and windows, and are hoping to see their material used in commercial products in about five years, says Schutzius.