(Nanowerk News) A Rice University team has hit upon a method to produce nearly transparent films of electrically conductive carbon nanotubes, a goal sought by researchers around the world.
The lab of Rice researcher Matteo Pasquali found that slides dipped into a solution of pure nanotubes in chlorosulfonic acid (CSA) left them with an even coat of nanotubes that, after further processing, had none of the disadvantages seen with other methods.
The films may be suitable for flexible electronic displays and touchscreens, according to the paper published this month in the American Chemical Society journal ACS Nano (« High-Performance Carbon Nanotube Transparent Conductive Films by Scalable Dip Coating »).
A thin film of pure carbon nanotubes produced at Rice University shows promise as a component of flexible, transparent touchscreens. (Image: Pasquali Lab/Rice University)
“I think this could be the way that high-performance transparent electrodes are made in the future,” said Pasquali, a professor of chemical and biomolecular engineering and of chemistry. “The solution is straightforward. It’s a very simple process.”
The method is scalable to high-throughput processes like slot, slide and roll coating used by industry, Pasquali said.
A frustrating characteristic of nanotubes, particularly long ones, is that they attract each other in common solvents, making it a challenge to disperse them. Long nanotubes are believed to be the key to high-performance films.
Researchers have tried other ways to keep them from aggregating, Pasquali said. Functionalizing nanotubes – dressing them with chemicals – can make them less attractive to each other, but it degrades their desirable electrical properties. Combinations of surfactants and sonication have also been tried, but the nanotubes break during sonication, and the surfactant leaves a residue that cannot be washed away, he said.
Source: By Mike Williams, Rice University
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