Paris, 20 April 2012
In previous work published in 20105, Giuseppone and his colleagues succeeded for the first time in obtaining nanowires. To achieve this feat, they chemically modified “triarylamines”, synthetic molecules that have been used for decades by industry in Xerox® photocopying processes. Much to their surprise, they observed that in light and in solution, their new molecules stacked up spontaneously in a regular manner to form miniature fibers. These wires, a few hundred nanometers long (1 nm = 10-9 m, i.e. a billionth of a meter), are made up of what is known as the “supramolecular” assembly of several thousand molecules.
In collaboration with Doudin's team, the researchers then studied the electrical properties of these nanofibers in detail. This time, they placed their molecules in contact with an electronic microcircuit comprising gold electrodes spaced 100 nm apart. They then applied an electric field between these electrodes.
© Graphics: M. Maaloum, ICS (CNRS)
Artist's impression based on a real atomic force microscopy (AFM) image showing conductive supramolecular fibers trapped between two gold electrodes spaced 100 nm apart. Each plastic fiber is composed of several short fibers and is capable of transporting electrical charges with the same efficiency as a metal.
Their first important finding was that, when triggered by a flash of light, the fibers self-assemble solely between the electrodes. The second surprising result was that these structures, which are as light and flexible as plastics, turn out to be capable of transporting extraordinary current densities, above 2.106 Amperes per square centimeter (A.cm-2), approaching those of copper wire. In addition, they have very low interface resistance with metals6: 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 electronic devices such as flexible screens, solar cells, transistors, printed nanocircuits, etc.
© M. Maaloum, ICS (CNRS)
Real atomic force microscopy image showing a conductive supramolecular fiber, composed of several short fibers. Each grain corresponds to a molecule (the image is 50 nm in height).
1Institut Charles Sadron (CNRS).
2Institut de Physique et Chimie des Matériaux de Strasbourg (CNRS / Université de Strasbourg).
3Hollow carbon tubes with a diameter of around one nanometer (1 nm = 10-9 m), displaying outstanding electrical, mechanical and thermal properties, thus opening the way to numerous applications in the microelectronics sector.
4Very large organic molecules, in other words of living origin or derived from oil, mainly containing carbon and hydrogen.
5The Hierarchical Self-Assembly of Charge Nanocarriers: A Highly Cooperative Process Promoted by Visible Light; Giuseppone, N. et co. Angew. Chem. Int. Ed. 2010, 49, 6974-78
6“Force” with which the conductor opposes the flow of current.
Light-triggered Self-construction of Supramolecular Organic Nanowires as Metallic Interconnects. Vina Faramarzi, Frédéric Niess, Emilie Moulin, Mounir Maaloum, Jean-François Dayen, Jean-Baptiste Beaufrand, Silvia Zanettini, Bernard Doudin, and Nicolas Giuseppone. Nature Chemistry, On line on 22 April 2012 (DOI: 10.1038/NCHEM.1332)
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