MrSeb writes with news out of MIT about another interesting and potentially useful property of graphene. Researchers have known for several years that graphene generates electricity when exposed to sunlight, but incorrectly attributed it to the photovoltaic effect. A new paper shows that the current is actually generated from the much more unusual 'hot-carrier' response. Quoting: "The material’s electrons, which carry current, are heated by the light, but the lattice of carbon nuclei that forms graphene’s backbone remains cool. It’s this difference in temperature within the material that produces the flow of electricity. ... Such differential heating has been observed before, but only under very special circumstances: either at ultralow temperatures (measured in thousandths of a degree above absolute zero), or when materials are blasted with intense energy from a high-power laser. This response in graphene, by contrast, occurs across a broad range of temperatures all the way up to room temperature, and with light no more intense than ordinary sunlight." It will take more work to determine what new applications are reasonable from an efficiency perspective, but it does broaden graphene's already-impressive capabilities.
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