Solar cells that harness infrared light

摘要

No batteries? No sunshine? No problem. One day, your cell phone may be fully charged by a plastic photovoltaic cell built right into the case that can use indoor light and heat, making the technology truly wireless. This futuristic scenario just got a few years closer with the invention of a plastic infrared (IR) solar cell by Ted Sargent and his colleagues at the University of Toronto. The discovery opens the door to making cheap, efficient solar photovoltaic cells that produce more power per penny than fossil fuels. "We have made the first infrared photovoltaics based on solution-processing," Sargent says. He and his team suspended lead sulfide semiconducting nanocrystals, measuring a mere 4 nanometers (nm) in diameter, in a semiconducting plastic (Nat. Mater. 2005, 4,138-142). By controlling the size of the nanocrystals, or quantum dots, the scientists can tune the solar cells to absorb IR light at wavelengths of 980,1200, and 1355 nm and turn it into electric current. The low cost of plastic, combined with the advantages of harvesting power from abundant IR light, could help transform the new device into an affordable source of energy, he says.