Wednesday, April 25, 2007
Tailored Nanowires for electron extraction
A cross-section of the nanoscale coaxial cable, in which nitrogen, phosphorus, and gallium atoms are shown in blue, yellow, and magenta, respectively. White spheres represent hydrogen atoms, which help render the surface of the wire chemically non-reactive.
A nano scale co-axial technique developed at the LBNL shows promise in increasing the yield from solar power generators. Read more here. Excerpt from the article.
The nanowire, developed by researchers from the National Renewable Energy Laboratory (NREL) and Lawrence Berkeley National Laboratory, may solve several problems currently associated with renewable energy applications.
One overarching problem is that current semiconducting materials with the potential for use in renewable energy devices lack one key characteristic. When electrons in these materials are excited by light and jump to higher energy levels (leaving vacancies, known as “holes,” in the lower levels), both the electrons and the holes typically move around in the same region. Thus, they tend to recombine. This is desirable for certain applications, such as light-emitting devices, where electron-hole recombination produces light, but is not ideal for renewable energy devices. A better scenario is the separation of the excited electrons from the holes such that, in the case of solar cells, for example, the electrons can be drawn off and used for electricity.
“Our nanowires were designed to provide this feature, along with a superior electrical conductivity,” said NREL materials scientist Yong Zhang, the study's corresponding researcher, to PhysOrg.com. “Both of these properties are critical in order for renewable energy devices to reach their ultimate efficiency limits.”