March 25, 2013
Super-Efficient Nanowires Could Be Future Of Solar Energy
Brett Smith for redOrbit.com - Your Universe Online
Extremely thin nanowires are expected to revolutionize the field of electronics, and a new study in the journal Nature Photonics shows that they could have an impact on solar energy production as well.
According to the study, researchers at the Niels Bohr Institut in Denmark and Switzerland´s Ãcole polytechnique fÃ©dÃ©rale de Lausanne (EPFL) have been able to use a single nanowire to concentrate sunlight up to 15 times its normal intensity. The development has expanded what researchers previously believed to be the potential theoretical limit on how much energy can be collected from the sun´s radiation.
The previous limit, which was held up as the maximum value of solar cell efficiency for many years, is known as the Shockley Queisser Limit. Devised by William Shockley and“¯Hans Queisser in 1961, the limit asserts that the maximum solar conversion efficiency is 33.7 percent, meaning that the most efficient solar cell can only convert 33.7 percent of the sunlight that it receives.
The study´s results are the culmination of work by several research groups that have been developing and improving the quality of the crystals that make up a nanowire. The crystals have a cylindrical structure with a diameter of about one 10,000th that of a human hair. Not only have the nanowires proven useful for collecting the sun´s rays, they have also demonstrated great potential in developing quantum computers and similar products.
Nanowires are able to concentrate the sun's rays up to a factor 15 because the diameter of a nanowire crystal is actually smaller than the wavelength of sunlight. The size differential causes a resonance in light intensity within and around nanowires, resulting in a form of ℠concentrated´ sunlight. When the energy is converted in the wire, it could give future solar cells a higher conversion efficiency of the sun's rays, say the study´s authors.
“It's exciting as a researcher to move the theoretical limits, as we know,” said lead researcher said Peter Krogstrup, from the Niels Bohr Institute at the University of Copenhagen, in a statement. “Although it does not sound like much, that the limit is moved by only a few percent, it will have a major impact on the development of solar cells, exploitation of nanowire solar rays and perhaps the extraction of energy at international level.”
“However, it will take some years before production of solar cells consisting of nanowires becomes a reality,” Krogstrup added.
Besides impacting the green energy industry, the potential of nanowires is being realized across many fields. In February, Mobile Dev&Design´s Rahul Gupta wrote about the emergence and potential of silver nanowires in touch screen technology. Gupta noted that a nanowire network found that could be incorporated into a touch screen would be “light, thin, and shatterproof.”
“The nanowires also create a flexible transparent conductive layer that is conducive to bendable and curved form factors, or devices with touch capacities wrapped around their edges,” he added.
An additional bonus to using nanowire technology is that its material and processing costs tend to be relatively low.