Carbon coming to a TV screen near you
UK researchers have created a tiny liquid crystal display using a transparent material harder than diamond and only one atom thick.
The LCD display, based on the material graphene, could one day be used in everything from mobile phone touch screens to televisions.
"This LCD is probably the first realistic application that we have seen from graphene," says Dr Kostya Novoselov, a researcher at the University of Manchester and co-author of the study that appears in the American Chemical Society's Nano Letters.
Novoselov isolated graphene in 2004. Since then research into this cousin of coal has grown rapidly.
"Virtually every university now has someone working with graphene," says Novoselov.
Graphene is about as hard and clear as most diamonds, and made entirely out of carbon atoms, but its atomic structure makes it unique.
Pure diamond is a 3D crystal made of six carbon atoms shaped, appropriately enough, like a diamond, with eight facets on the crystal.
Graphene is also made of six carbon atoms, but instead forms a 2D 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 when viewed 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," says Novoselov.
Graphene's structure and bonding makes it as hard and clear as diamond but also able to conduct electricity, something many diamonds can't do. This makes it ideal for electronic devices.
To create the graphene LCD the researchers dissolved pieces of graphite (the hard stuff buried inside a pencil) into graphene, and sprayed the resulting suspension 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," says Novoselov.
The proof-of-concept LCD screen was small, only one pixel in resolution and about one micrometre in size.
But if that is scaled up, the resolution would be about the same as in a mobile phone screen, say the researchers.
Scaling up their design is the next step in Novoselov's research. But before graphene-based mobile phones and televisions become reality, two hurdles must be overcome.
The first is creating large amounts of high-quality graphene. The other is controlling the surface structure.
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 mobile phones.
Currently, most touch screens are based on indium tin oxide. But indium is a rare element and some researchers have calculated that the world's supply of indium could run out within 10 years.
Unless researchers develop a substitute for indium, touch screens could face an increasingly tough future.
"[So] it's important that people are starting to find applications for graphene," says Pablo Jarillo-Herrero, an assistant professor at the Massachusetts Institute of Technology who studies graphene but was not involved in the UK research.
"Graphene could be used in used in computers, electronics, nanodevices and nanosensors," says Jarillo-Herrero.
"[But] there is still a need for basic research before graphene can be functionalised," for use in commercial devices, he says.