Nicolas Giuseppone and Bernard Doudin have headed a team from CNRS and the University of Strasbourg that has managed to synthesise a kind of nanofibre with a range of potentially useful properties.
In 2010, Giuseppone and his team published a paper in which they described the chemical modification of triarylamines – synthetic molecules used for decades in Xerox machines – to produce molecules which, when in solution, stacked themselves uniformly in response to light. This resulted in miniscule 'supramolecular' wires, several nanometres thick and a few hundred nanometres long.
Follow-up work with Doudin and his colleagues looked in detail at the electrical properties of the nanofibres. When they applied an electric current to the molecules while in contact with a grid of gold electrodes in a microcircuit, it was discovered that the fibres formed only between electrodes. They self-assembled in response to a flash of light.
Real atomic force microscopy image showing a conductive supramolecular fibre. Each grain corresponds to a molecule.
They also found that the fibres conducted relatively high current densities, almost on a par with copper wire, in fact. It is claimed that the new nanofibres combine the most advantageous features of both types of material currently used to transport electric currents, namely metals and plastic organic polymers.
The supramolecular fibres have the edge over carbon nanotubes in that they are inexpensive, flexible and comparatively easy to handle, according to the researchers involved. In addition, the amount of interface or contact resistance they exhibit with metals is considerably lower (up to 10,000 times less) than in other comparable organic polymers.
It is hoped that the work carried out to date will pave the way for the integration of the fibres in industrial applications, for example in solar cells, flexible screens, transistors, printed nanocircuits, and other electronic devices on the nanometric scale.