Newly observed properties mean the material could be a highly efficient converter of light to electric power.

Researchers have demonstrated that graphene is highly efficient at generating electrons upon absorbing light, which suggests that the material could be used to make light sensors and perhaps even more efficient solar cells.

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.

Previous theoretical work had inspired hope that graphene had this property, says Frank Koppens, a group leader at the Institute of Photonic Sciences in Spain, who led the research. He says the new result, described this week in Nature Physics, represents the first experimental proof.

To perform the experiment, the researchers used two ultrafast light pulses. The first sent a prescribed amount of energy into a single layer of graphene. The second served as a probe that counted the electrons the first one generated.

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