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Discovery Opens Door to Metal-Based Solar Cells

Category: Science & Technology
Posted: 05:20AM
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In a single day, the Sun dumps far more energy onto Earth than humanity uses, which is one of the reasons many want to see solar energy grow in use. Among the problems with this family of technologies is the cost of the materials used, such as gallium and indium. By shifting to other, cheaper materials, solar power can become more common, and researchers at Rice University have made an important to that end.

This discovery concerns the plasmonic properties of metallic nanoparticles. When light shines on these nanoparticles, some of the photons will couple with electrons to form plasmons, but some electrons will be excited to even higher levels, becoming 'hot electrons.' These hot electrons are what one wants for solar power, but their formation and behavior has not been well understood because they could not be filtered out from less-energetic electrons. This is what the Rice researchers have overcome by placing a gold nanowire on top of titanium dioxide, with a layer of titanium between during some tests. When the titanium was present, all of the excited electrons would flow through, but when it was not, only the hot electrons were collected.

This discrimination between the systems allowed the researchers to correlate systems properties with hot electrons. They found the hot electrons were by a plasmonic mechanism called field-intensity enhancement, and not the total absorption of light by the nanoparticle. With this discovery it should be possible to design and tune metallic nanoparticles for solar power, which will be cheaper than modern solar cells and also more capable, as the nanoparticles can be made to absorb the whole spectrum, and not just specific pieces of it.

Source: Rice University



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