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nanotimes News in Brief
“It’s low-cost and very easy to prepare,” said Yun Hang Hu, a professor of materials science and engi- neering. But not just any recipe will do. “If you use too much graphene, it will absorb the light in the solar cell and reduce its efficiency,” he said. “The excellent electrical conductivity of graphene sheets allows them to act as bridges, accelerating electron transfer from the titanium dioxide to the photoelec- trode.”
Their work was presented at the US-Egypt Joint Workshop on Solar Energy Systems, held March 12 to 14 in Cairo.
Real atomic force microscopy image showing a conductive supramolecular fiber, composed of several short fibers. Each grain corresponds to a molecule (the image is 50nm in height). © M. Maaloum, ICS, CNRS
12-04 :: April/May 2012
Researchers from CNRS and the Université de Strasbourg, headed by Nicolas Giuseppone and Bernard Doudin, have succeeded in making highly conductive plastic fibers that are only several nano- meters thick. These nanowires, for which CNRS has filed a patent, “self-assemble” when triggered by a flash of light! Inexpensive and easy to handle, unlike carbon nanotubes, they combine the advan- tages of the two materials currently used to conduct electric current: metals and plastic organic poly- mers. In fact, their remarkable electrical properties are similar to those of metals. In addition, they are light and flexible like plastics, which opens up the possibility of meeting one of the most important challenges of 21st century electronics: miniaturizing components down to the nanometric scale.
Their first important finding was that, when trigge- red by a flash of light, the fibers self-assemble solely between the electrodes. The second surprising re- sult was that these structures, which are as light and flexible as plastics, turn out to be capable of trans- porting extraordinary current densities, above 2.106 Amperes per square centimeter (A.cm2
), approa-
ching those of copper wire. In addition, they have very low interface resistance with metals: 10,000 times below that of the best organic polymers.
The researchers now hope to demonstrate that their fibers can be used industrially in miniaturized elec- tronic devices such as flexible screens, solar cells, transistors, printed nanocircuits, etc.