Columbia University physics professor Philip Kim, who is a coauthor of the new paper, says that chemical vapor deposition is one of the cheapest ways to make quality graphene on a large scale and should be compatible with existing semiconductor fabrication technologies. Right now, the researchers can make four-inch pieces, but Hong says that they could easily scale up the process.
The new graphene films are less defective than ones made in the past, Hong says, which is why they are about 30 times more conductive and have about 20 times higher mobility than do previous graphene sheets. “The conductivity is sufficient for some entry-level applications in small LCD displays and touch-panel displays,” says Yang Yang, a materials-science and engineering professor at the University of California, Los Angeles. However, he adds, the conductivity would still need to be 10 times better in order to replace ITO in organic solar cells and OLEDs.
Many other materials are being considered for transparent, bendable electronics. Carbon nanotubes could be a tough competitor. For example, researchers are making headway with creating flexible nanotube transistors, and Unidym, based in Menlo Park, CA, will soon start selling nanotube-coated plastic films, which could be used instead of ITO coatings on displays.
Others have made flexible, see-through transistors using indium-oxide coatings, or zinc-oxide and indium-oxide nanowires. Meanwhile, University of Michigan researchers have made transparent electrodes using a grid of very thin metal wires.
Graphene’s advantage could be its exceptional strength and high mobility (predicted to be twice that of nanotubes). Tao He, a graphene researcher at Rice University, says that the conductivity and mobility values of the new films are impressive. “I didn’t see any [other work] similar or comparable to this one,” he says, adding that the new work could make large-scale, low-cost manufacture of flexible graphene electronics possible.