German researchers say they've figured out how to grab infrared sunlight with solar cells. The advantage comes from a special black silicon and panels made from it produce twice the electricity of regular PV panels.

"Black silicon is produced by irradiating standard silicon with femtosecond laser pulses under a sulfur containing atmosphere," said Stefan Kontermann, researcher at the Fraunhofer Institute for Telecommunications at the Heinrich-Hertz-Institut in Germany. "This structures the surface and integrates sulfur atoms into the silicon lattice, making the treated material appear black."

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The researchers said they were able to double the efficiency of black silicon solar cells by modifying the shape of the laser pulse used to irradiate the silicon.

In Colorado, scientists at the National Renewable Energy Laboratory this month reported they, too, had figured out how to boost efficiency of their black solar cells. They said they have figured out how to grab more electricity by reducing reflectivity from sunlight.

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The NREL project is being licensed by New Jersey-based Natcoresolar Technology, which is hoping to commercialize the idea. "Consumers will benefit from both the low reflection and low cost of our solar cell," said NREL's Jihun Oh, who authored the recent study in Nature Nanotechnology. "So you'd pay less to put a black Silicon PV array on your house and get more electricity from it. This means shorter payback times for your investment."

Credit: Fraunhofer HHI