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."
Jessika Trancik | EurekAlert!
New value added to the ICSD (Inorganic Crystal Structure Database)
27.03.2017 | FIZ Karlsruhe – Leibniz-Institut für Informationsinfrastruktur GmbH
Argon is not the 'dope' for metallic hydrogen
24.03.2017 | Carnegie Institution for Science
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
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In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
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