May 15, 2008 -- Using a transparent material harder than diamond and only one atom thick, researchers in the U.K. have created a tiny liquid crystal display. The display, based on a material called graphene, could one day be used in everything from cell phone touch screens to TVs.
"This LCD is probably the first realistic application that we have seen from graphene," said Kostya Novoselov, a researcher at the University of Manchester and coauthor of the study that appeared in the American Chemical Society's Nano Letters.
Graphene was discovered in 2004 by Novoselov. Since then research into this cousin of coal has grown rapidly.
"Virtually every university now has someone working with graphene," said Novoselov.
While graphene is about as hard and clear as most diamonds, and made entirely out of carbon atoms, its atomic structure makes it unique.
Pure diamond is a three-dimensional crystal made of six carbon atoms shaped, appropriately enough, like a diamond, with eight facets on the crystal.
GraphenePure graphene is also made of six carbon atoms but instead forms a two-dimensional hexagon. Each side of the hexagon forms one side of six more hexagons and so on, until one flat sheet of pure, tightly bonded carbon atoms is formed. A sheet of graphene looks like chicken wire at the atomic level.
Carbon nanotubes, which have also generated a great deal of research in everything from bone repair to electronics, can be regarded as a tube of graphene.
"Anything carbon nanotubes can do graphene could do as well," said Novoselov.
The structure and bonding of graphene makes it as hard and clear as diamond but also able to conduct electricity, something many diamonds can't do, and which makes it ideal for electronic devices.
To create the graphene LCD the researchers first dissolved common and abundant graphite (the hard stuff buried inside a pencil) and another form of carbon bonded to itself, and sprayed the resulting solution onto a glass surface. Once the solution dried, the researchers picked up the small flakes and used them as the electrodes for the small LCD.
The way we got [graphene] was almost trivial," said Novoselov.
The proof of concept LCD screen was small, only one pixel in resolution and about one micron in size. But if that was scaled up, the resolution would be about the same as in a cell phone screen today, say the researchers.
Scaling up their design is the next step in Novoselov's research, but before graphene-based cell phones and TVs become reality, two hurdles must be overcome.
The first is creating large amounts of high quality graphene. The other is controlling the structure of the surface.
Overcoming these two barriers is quickly becoming more important. Because graphene is electrically conductive it's ideal for touch screens, like those found on many cell phones.
Currently most touch screens are based on indium tin oxide. Indium is a rare element, however, and some researchers have calculated that the world's supply of indium could run out in as soon as 10 years. Unless a substitute for indium is developed, touch screens could face an increasingly tough future.
For these reasons, "it's important that people are starting to find applications for graphene," said Pablo Jarillo-Herrero, a professor at the Massachusetts Institute of Technology who studies graphene but was not involved in the U.K. research.
"Graphene could be used in used in computers, electronics, nanodevices and nanosensors," said Jarillo-Herrero.
However, "there is still a need for basic research before graphene can be functionalized," for use in commercial devices, said Jarill-Herrero.
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