Trinity researchers have achieved a world first, producing multiple carbon sheets just an atom thick. It could transform electronics, writes Dick Ahlstrom
The research team that delivered the hardest known substance in the world has accomplished yet another feat - producing sheets of carbon just one atom thick.
This exotic material, known as graphene, could transform the world of electronics and open up the possibility of new composite materials, suggests Trinity College Dublin's Prof Jonathan Coleman.
A professor in the school of physics and a principal investigator at Trinity's Crann nanotechnology research centre, Prof Coleman, along with his team, has come up with a way to produce large amounts of this previously elusive substance.
Researchers from the University of Manchester produced the first graphene in 2004, and there have been efforts since to find ways to deliver supplies of this material for study.
Existing techniques involve the use of a graphite crystal - more or less the same as an ordinary "lead" pencil - which is rubbed across a surface. While most of the graphite is deposited in multiple layers, every so often this "exfoliation" method deposits a single layer of graphene, explains Prof Coleman.
He has come up with a new method, however, that could transform the study of graphene, a substance sought for use in new types of electronic devices. "We can now make graphene on demand, hundreds to thousands of times more than has previously been produced," he says. "And this is upscalable, you could build a plant to do this."
His approach follows earlier work which helped produce the strongest substance yet known.
He specialises in developing composite materials using carbon nanotubes, the mainstay of nanotechnology research.
Made entirely of carbon atoms formed into a tube-shape, they are extremely strong and researchers seek to use this strength in composites that include plastics.
"They are 50 times stronger than steel, but the challenge is how do you use that," says Prof Coleman, whose lab forms part of Crann, which yesterday celebrated its arrival in a new home, in the Naughton Institute Building on Pearse Street.
An early approach was to introduce carbon nanotubes into a composite to add strength. The object is to distribute the nanotubes evenly through the composite but the problem is they tend to clump together.
"The nanotubes have to be uniformly dispersed and this proved to be a very, very difficult problem to solve," he says.
His group overcame this by finding solvents which coat the nanotube surface and prevent them from clumping together. They now have 12 different solvents suited to different composite mixes.
Along the way, they produced a composite with carbon nanotubes which arguably was the hardest substance yet created. More importantly, his group also became involved in a Science Foundation Ireland research programme worth €1.7 million in co-operation with Hewlett Packard to make flexible nanotube composites.
Its goal is to produce clear plastics that also conduct electricity. These would feature in new kinds of flexible displays. He says they could use this to make plastics that are many times more conductive, yet the composite sheets could be rolled up.
The creation of graphene at Manchester attracted Prof Coleman's attention and he wondered whether solvents might work in separating graphene's two-dimensional carbon sheets. "We did the experiments and lo and behold it works," he says.
While the exfoliation does produce graphene, his solvent-based approach delivers large amounts of the material very quickly. His group has also found a selection of solvents able to do this, which will speed the application of graphene both in composites and in electronics.
These sheets are unimaginably thin and because of this they display "quantum electro-dynamics", unusual characteristics associated with their small size. They can move their electrons very quickly when conducting electricity, and they also perform as semiconductors.
These two characteristics are of fundamental importance to the central component of a computer, the transistor. Transistors are made of semiconductors and the faster the transistor the better the computer performance.
Graphene could prove hugely important as a new, faster semiconductor. Prof Coleman's work means graphene will be readily available for use in novel composites, but also as a new kind of semiconductor.