Efficient material for solar cells studied

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EVANSTON, Ill., Nov. 2 (UPI) -- U.S. researchers say a newly developed material that can absorb a wide range of wavelengths could lead to more efficient and less expensive solar technology.

Scientists at Northwestern University say solar cells are only as efficient as the amount of sunlight they collect, and the new material can increase the range of wavelengths that can be turned into electrical energy.

"The solar spectrum is not like a laser -- it's very broadband, starting with UV and going up to near-infrared," Koray Aydin, a professor of electrical engineering and computer science, said in a university release Wednesday.

"To capture this light most efficiently, a solar cell needs to have a broadband response. This design allows us to achieve that."

Using metal and silicon oxide, the researchers created thin but complex trapezoid-shaped metal gratings on the nanoscale that can trap a wider range of visible light.

The uniquely shaped grating captures a wide range of wavelengths due to a phenomenon known as optical resonances that causes light to spend more time inside the material until it gets absorbed, the researchers said.

If applied to semiconducting materials, the technology could yield thinner, lower-cost and more efficient solar cells, Aydin said.