Oct 23, 2002
Sugar coating insulates molecular wires
A team of scientists from University College London, Cambridge University and Oxford University in the UK, and Humboldt University Berlin, Germany, has used supramolecular chemistry to insulate molecular wires made from conducting polymer molecules. Coating the molecules with ring-like sugars called cyclodextrins improved their light-emitting properties.
"Our results demonstrate the potential for the control of intermolecular interactions in the solid state," Franco Cacialli of University College London told nanotechweb.org. "Our approach, based on threading the conjugated backbone [of the polymer molecule] into cyclodextrin rings, is rewarded by a number of advantages."
The advantages include a reduction of the wires' tendency to aggregate; increased luminescence efficiency and blue-shifted emission; and encapsulation of the active groups in a protected environment that increases the molecule's stability and makes it more resistant to quenching by impurities.
The insulation also enhanced the molecules' solubility in water, which Cacialli says allows spin-coating without toxic solvents and paves the way for biocompatible processes and structures. "It is especially attractive for ink-jet printing, as print-heads have a longer lifetime if inks are based on water instead of organic solvents," he added.
Cacialli believes that applications for the work will be in the area of functional polymers, particularly for plastic electronics and optoelectronics. "We hope that our findings will stimulate the interest of other researchers and technologists working in this area, so as to produce a synergic, integrated effort to make it happen," he said. "Given enough funds and collaborators we consider that five years could be a reasonable approximation [until the first commercial use of the technique]."
Now the scientists, who reported their work in Nature Materials, are working "to implement more sophisticated charge injection schemes into the molecular wires, and to improve the luminescence efficiency of the materials."
About the author
Liz Kalaugher is editor of nanotechweb.org.