- Category: Technology
08 Mar 2013
- Published on Friday, 08 March 2013 09:16
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Researchers from the University of Connecticut have developed nanosized antennas that could allow a solar cell to harvest and convert more solar energy from sunlight.
Scientists have long theorized that small nanosized antenna arrays could harvest and convert more than 70 percent of the sun’s electromagnetic radiation; a vast improvement over current silicon solar panels which collect only about 20 percent.
The nanoantennas known as rectennas are also capable of automatically converting the sunlight into energy.
Rectennas are extremely difficult to construct. They must be capable of operating at the speed of visible light and be built in such a way that their core pair of electrodes is a mere 1 or 2 nanometers apart.
UConn engineering professor Brian Willis developed and patented a novel fabrication technique called selective area atomic layer deposition that enabled the fabrication of a working rectenna device.
In a rectenna device, one of the two interior electrodes must have a sharp tip, and the tip of that electrode must hold within one or two nanometers of the opposite electrode.
Previous attempts using lithographic fabrication techniques failed to get the proper spacing between the electrodes. Through atomic layer deposition, Mr. Willis was able to precisely coat the tip of the rectenna with layers of individual copper atoms until a gap of about 1.5 nanometers was achieved.
The size of the gap is critical because it creates an ultra-fast tunnel junction between the electrodes, allowing a maximum transfer of electricity. Because of these tunnels, rectennas can also covert solar radiation in the infrared region.
Silicon solar panels have a single band gap which allows the panel to convert electromagnetic radiation efficiently at only one small portion of the solar spectrum. The rectanna doesn’t rely on a band gap and devices using it may be tuned to harvest light over the whole solar spectrum.
“This new technology could get us over the hump and make solar energy cost-competitive with fossil fuels,” said Mr. Willis. “This is brand new technology, a whole new train of thought.”
The Federal government has taken notice of the work and Mr. Willis and a team of scientists from Penn State Altoona, along with private research and development company SciTech Associates Holdings Inc., have received a $650,000 three-year grant from the National Science Foundation to fabricate rectennas and search for new ways to maximize their performance. – EcoSeed Staff