Spray-On Solar Power Coming Soon?

Powering your tablet could soon be as simple as wrapping it in cling wrap, thanks to a team of scientists that recently invented a way to spray on solar power.

Lead researcher Illan Kramer and his colleagues at the University of Toronto developed miniscule light-sensitive materials called colloidal quantum dots (CQDs) that can be used to spray solar cells onto virtually any surface, from patio furniture to an airplane's wing.

The breakthrough has the potential to make manufacturing solar cells cheap and easy.

"My dream is that one day you'll have two technicians with Ghostbusters backpacks come to your house and spray your roof," Kramer explained in a statement.

And just because these solar cells spray on doesn't mean they're not as powerful as normal solar cells. A surface the size of your car's roof wrapped with CQD-coated film, for example, would produce enough energy to power three 100-Watt light bulbs - or 24 compact fluorescents.

Kramer calls this technology sprayLD, after the manufacturing process known as atomic layer deposition, or ALD. In this system, materials are laid down on a surface one atom-thickness at a time.

Until now, light-sensitive CQDs could only be incorporated onto surfaces through batch processing, which is inefficient, slow and expensive. But sprayLD blasts a liquid containing CQDs directly onto flexible surfaces, such as film or plastic, like printing a newspaper by applying ink onto a roll of paper. This method makes manufacturing solar cells much easier than the conventional approach, not to mention without compromising solar-cell efficiency.

And sprayLD was made from everyday, cheap parts, like paint brushes from an art store and spray nozzles found in steel mills.

"As quantum dot solar technology advances rapidly in performance, it's important to determine how to scale them and make this new class of solar technologies manufacturable," said project supervisor Ted Sargent. "We were thrilled when this attractively manufacturable spray-coating process also led to superior performance devices showing improved control and purity."

The technology is described further in three journals: Advanced Materials, Applied Physics Letters, and ACS Nano.

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