Solar cells convert sunlight into electricity using semiconductor materials that exhibit the photovoltaic effect – meaning they absorb photons and release electrons that can be channeled into an electrical current. Photovoltaics are the ultimate source of clean, green and renewable energy but today’s  technologies utilize relatively scarce and expensive semiconductors. But now  High efficiency solar cells could be made from virtually any semiconductor material. This technology has been developed by researchers with the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California (UC) Berkeley. 

“It’s time we put bad materials to good use,” says physicist Alex Zettl, Director of the Center of Integrated Nanomechanical Systems (COINS), who led this research along with colleague Feng Wang. “Our technology allows us to sidestep the difficulty in chemically tailoring many earth abundant, non-toxic semiconductors and instead tailor these materials simply by applying an electric field.”“Our technology reduces the cost and complexity of fabricating solar cells and thereby provides what could be an important cost-effective and environmentally friendly alternative that would accelerate the usage of solar energy.”

Source. http://newscenter.lbl.gov/feature-stories/2012/07/26/photovoltaics-from-any-semiconductor/