Perfecting a solar cell by adding imperfectionsJune 17, 2008Nanotechnology is paving the way toward improved solar cells. New research shows that a film of carbon nanotubes may be able to replace two of the layers normally used in a solar cell, with improved performance at a lower cost. Researchers have found a surprising way to give the nanotubes the properties they need: add defects. Currently, these solar cells, called dye-sensitized solar cells, have a transparent film made of an oxide that is applied to glass and conducts electricity. In addition, a separate film made of platinum acts as a catalyst to speed the chemical reactions involved. Both of these materials have disadvantages, though. The oxide films can't easily be applied to flexible materials: they perform much better on a rigid and heat resistant substrate like glass. This increases costs and limits the kinds of products that can be made. And expensive equipment is necessary to create the platinum films.
Jessika Trancik of the Santa Fe Institute, Scott Calabrese Barton of Michigan State University and James Hone of Columbia University decided to use carbon nanotubes to create a single layer that could perform the functions of both the oxide and platinum layers. They needed it to have three properties: transparency, conductivity, and catalytic activity. Ordinary carbon nanotubes films are so-so in each of these properties. The obvious ways of improving one, though, sacrifice one of the others. For example, making the film thicker makes it a better catalyst, but then it's less transparent. Previous theory had suggested that materials may function better as catalysts when they have tiny defects, providing sites for chemicals to attach. So the researchers tried exposing the carbon nanotubes to ozone, which roughs them up a bit. Very thin films, they found, became dramatically better catalysts, with more than ten-fold improvement. In fact, the performance gets close to that of platinum. "That's remarkable," Trancik says, "because platinum is considered pretty much the best catalyst there is." In order to address the trade-off between transparency and conductivity, the researchers tried another trick on a bottom layer of tubes: they created carbon nanotubes that were longer. This improved both conductivity and transparency. The carbon nanotube films might be used in fuel cells and batteries as well. "This study is an example of using nanostructuring of materials - changing things like defect density and tube length at very small scales - to shift trade-offs between materials properties and get more performance out of a given material," Trancik says. "Making inexpensive materials behave in advanced ways is critical for achieving low-carbon emissions and low cost energy technologies." Santa Fe Institute Science News and Science Current Events Tag Cloud This tag cloud is a visual representation of term frequencies of random science news topics with common terms grouped together and emphasized by their display size. Stem Cell Wildlife Conservation Evolution Hubble Space Telescope Natural Selection Neanderthal Cognition Health Insurance Antidepressant Kidney Transplant Cavities Comet Dust Omega-3 Fatty Acids Depleted Uranium Radiation Treatment Space Telescope Nanoparticle Life Expectancy DNA repair Telemedicine Titanium Language Overweight Mars Embryonic Development
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Related Solar Cell Current Events and Solar Cell News Articles Flexible Solar Strips Light Up Campus Bus Shelter There won't be anymore waiting in the dark at this campus bus shelter. New flexible solar cell technology developed by a group of engineering researchers at McMaster University has been installed to power lighting for night-time transit users. Lasers are making solar cells competitive Solar electricity has a future: It is renewable and available in unlimited quantities, and it does not produce any gases detrimental to the climate. Discovered after 40 years: Moon dust hazard influenced by Sun's elevation In the 1960s and 1970s, the Apollo Moon Program struggled with a minuscule, yet formidable enemy: sticky lunar dust. Four decades later, a new study reveals that forces compelling lunar dust to cling to surfaces -- ruining scientific experiments and endangering astronauts' health --change during the lunar day with the elevation of the sun. Ancient diatoms lead to new technology for solar energy Engineers at Oregon State University have discovered a way to use an ancient life form to create one of the newest technologies for solar energy, in systems that may be surprisingly simple to build compared to existing silicon-based solar cells. University of Alberta and NINT researchers make solar energy breakthrough The University of Alberta and the National Research Council's National Institute (NINT) for Nanotechnology have engineered an approach that is leading to improved performance of plastic solar cells (hybrid organic solar cells). heaper materials could be key to low-cost solar cells Unconventional solar cell materials that are as abundant but much less costly than silicon and other semiconductors in use today could substantially reduce the cost of solar photovoltaics, according to a new study from the Energy and Resources Group and the Department of Chemistry at the University of California, Berkeley, and the Lawrence Berkeley National Laboratory (LBNL). Research highlights potential for improved solar cells A team of Los Alamos researchers led by Victor Klimov has shown that carrier multiplication-when a photon creates multiple electrons-is a real phenomenon in tiny semiconductor crystals and not a false observation born of extraneous effects that mimic carrier multiplication. The research, explained in a recent issue of Accounts of Chemical Research, shows the possibility of solar cells that create more than one unit of energy per photon. Boosting the power of solar cells New ways of squeezing out greater efficiency from solar photovoltaic cells are emerging from computer simulations and lab tests conducted by a team of physicists and engineers at MIT. Precise measurement of phenomenon advances solar cell understanding Researchers at Washington University in St. Louis have shed light on a basic process that could improve future solar cells. Just Scratching the Surface: New Technique Maps Nanomaterials as They Grow Researchers at Rensselaer Polytechnic Institute have developed a measurement technique that will help scientists and companies map nanomaterials as they grow. More Solar Cell Current Events and Solar Cell News Articles |
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