Promise of high efficiency solar cells from Nobel winners

Since Andre Geim and Kostya Novoselov made their discovery, for which they won Nobel prize, everyone knows that graphene can be isolated as single layers and used in a lot of applications that exploit its extraordinary structural and electronic properties. However, graphene has not been used so much in practical applications as active material for photovoltaic devices. This is a pity, because the semi-metallic band structure of graphene would allow fast absorption of every wavelength radiation and almost every photon absorbed is converted in an electron-hole pair (high internal quantum efficiency). Unfortunately, the external quantum efficiency is very low, so that it can absorbs only a small fraction of the light incoming on its surface. Now, it seems something is changed and that this could be not a discovery affected by too much emphasis, considered that among the authors of the paper I’m talking about there are the above mentioned Nobel winners. Indeed Geim and Novoselov in collaboration with Andrea Ferrari from the University of Cambridge and other researchers published an article in Nature Communications 10.1038/ncomms1464, where it is explained that coupling graphene with plasmonic nanostructures they have been able to dramatically enhance the quantum efficiency of the light to current conversion. They used metal nanostructures fabricated on top of graphene samples that enhanced local electromagnetic fields so that the coupling of incoming light with electrons on the surface of the metal was improved. In this region of the material light is converted to electrical current, in such a way to increase the generated photovoltage. The researchers think that by suitable design of plasmonic nanostructures they could also achieve almost ‘ideal’ solar cells.

Andre Geim and Kostya Novoselov

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