In the advanced online edition of Nature Nanotechnology, researchers have developed a new method to produce graphene sheets leading to a diagonal dimension of 30 in. – larger than ever before. This could result in cheaper electrodes for flexible displays. The graphene has already been used to construct a touchscreen that is twice as flexible as one made using indium titanium oxide, the material usually used in touchscreens.
Using chemical vapor deposition, researchers at University of Texas, Austin heated methane and hydrogen gas to 1000 °C above a flexible copper substrate, causing a reaction that left a layer of graphene deposited on the copper. Once the graphene cooled, they transferred it onto a piece of flexible plastic.
Now Jong-Hyun Ahn and Byung Hee Hong of Sungkyunkwan University in Suwon, South Korea, and colleagues, have adapted this approach to produce still larger graphene sheets. They ran the reactions inside a modified roll-to-roll machine through which they fed the flexible copper sheets. The result was a rectangular graphene sheet with a diagonal diameter of 30 in.
The team built a palm-sized touchscreen with the film. The touchscreen was able to withstand up to 6 percent combined compressive and tensile strain before breaking, compared with only about 3 percent for touch panels based on indium tin oxide.
Graphene could be a cheaper and more flexible alternative to indium tin oxide, and this work is a step towards producing commercially useful quantities. The researchers still have to show that their graphene sheets can be made to a consistently high quality, without introducing tears or discontinuities that could affect performance, Colombo says.