Thursday, January 15, 2009

Bigger, Stretchier Graphene

From MIT's Technology Review:
Big and bendy: A transparent graphene film, two centimeters on each side, stretches and flexes when transferred to a rubber stamp. The stamp can be used to deposit the film on any substrate.
Credit: Ji Hye Hong

Korean researchers have found a way to make large graphene films that are both strong and stretchy and have the best electrical properties yet. These atom-thick sheets of carbon are a promising material for making flexible, see-through electrodes and transistors for flat-panel displays. Graphene could also lead to foldable organic light-emitting diode (OLED) displays and organic solar cells. However, it has not been easy finding a way make large, high-quality sheets of graphene.

Researchers from the Sungkyunkwan University and the Samsung Advanced Institute of Technology, in Suwon, Korea, have made centimeters-wide graphene films that are 80 percent transparent and can be bent and stretched without breaking or losing their electrical properties. Others have made large graphene films using simpler techniques, but the new films are 30 times more conductive. In addition, it is easy to transfer the new films onto different substrates. "We have demonstrated that graphene is one of the best materials for stretchable transparent electronics," says Byung Hee Hong, who led the work, which is published in Nature.

Graphene is an excellent conductor, and it transports electrons tens of times faster than silicon does. It could replace the brittle indium tin oxide (ITO) electrodes that are currently used in displays, organic solar cells, and touch screens. Graphene transistors could also replace silicon thin-film transistors, which are not transparent and are hard to fabricate on plastic....MORE