Researchers at the National Renewable Energy Laboratory (NREL), in Golden, CO, showed that silicon nanocrystals can produce two or three electrons per photon of high-energy sunlight.

The effect could lead to a new type of solar cell that is both cheap and more than twice as efficient as today’s typical photovoltaics.

Solar cells made of silicon nanocrystals could theoretically convert more than 40 percent of the energy in light into electrical power; today’s flat rooftop solar panels are at best just over 20 percent efficient and theoretically limited to about 30 percent efficiency.