A new way of creating a voltage by shining light on a solid has been developed by researchers in the US and Europe. Unlike most photovoltaic devices, the new system does not rely on semiconductors but rather on surface plasmons in tiny metal nanostructures. The team is now working to create new types of devices that convert light into electrical energy.

Surface plasmons are collective excitations of electrons at the surface of a metal that interact very strongly with light. As a result, plasmons are of great technological interest as an interface between photonics and electronics. This interaction is strongest at the plasmon-resonance frequency, which is defined by the size and shape of an object and its charge density. In 2009 Paul Mulvaney and colleagues at the University of Melbourne in Australia applied an electrical potential to gold nanoparticles, and found that they could tune the plasmon-resonance frequency by injecting or removing electrons.

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