Silicon's future replacement?The best known material used in solar cells is silicon, but that might change in the future; graphene, the wunderkind material for which we keep finding new uses, just like its cousin the carbon nanotube, is proving to have very promising qualities for converting light (photons) into electricity (electrons). The reason why solar researchers are excited is well explained by MIT's Technology Review:
Conventional materials that turn light into electricity, like silicon and gallium arsenide, generate a single electron for each photon absorbed. Since a photon contains more energy than one electron can carry, much of the energy contained in the incoming light is lost as heat. Now, new research reveals that when graphene absorbs a photon it generates multiple electrons capable of driving a current. This means that if graphene devices for converting light to electricity come to fruition, they could be more efficient than the devices commonly used today. (source)
Researchers from the Institute of Photonic Sciences in Spain have just published results from their experiments on graphene, testing out the theory to see how real-world applications would fare. While their results so far will probably be more useful to make better image sensors (for cameras, medical sensors, and night-vision optics), they still show promise for third-generation solar cells which could, in theory, reach efficiencies in the range of 60% (!), something that would be a complete game-changer in the clean-energy world.