Graphene-Carbon Nanotubes to Make Transparent Conductors Possible

Rather than trying to devise complicated and very expensive graphene production processes, or novel ways of producing large amounts of carbon nanotubes, researchers at the University of California in Los Angeles (UCLA) have created a new compound, which is a lot faster and easier to produce, and also takes the best of both worlds. Hybrid graphene–carbon nanotubes (GCNT) can be used for the same applications as their precursors, but are also more flexible than any of the other two.

Details of the innovation are published in the May 13th issue of the American Chemical Society's respected journal Nano Letters. The development process of GCNT was led by UCLA Professor of Chemistry and Biochemistry and member of the California NanoSystems Institute (CNSI) Richard Kaner, working together with colleague Yang Yang, who is a UCLA Henry Samueli School of Engineering and Applied Science professor of materials science and engineering, and also a CNSI member.

The two say that the indium tin oxide (ITO) is the best transparent conductor in the world today, but that its costs are well above economic applications. One of the main reasons for this is that indium is very scarce, and also the fact that, once ITO is produced, it becomes very fragile and rigid. At this point, Yang and Kaner share, GCNT is the only alternative to ITO on the market that can achieve and exceed the performances of the oxide. In addition, the method of producing the hybrid graphene–carbon nanotubes is scalable, easy, and very cost-efficient.

“To our knowledge, this is the first report of dispersing CNTs in anhydrous hydrazine. This is important because our method does not require the use of surfactants, which have traditionally been used in these solution processes and can degrade intrinsic electronic and mechanical properties,” Yang adds. In a November 2008 study, the team presented a new method of producing graphene, by simply immersing graphite oxide in a hydrazine solution. They also showed that, by introducing carbon nanotubes in the same solution, they not only obtained graphene, but the new hybrid material as well.

“The potential of this material (GCNT) is not limited to improvements in the physical arrangements of the components. With further work, GCNTs have the potential to provide the building blocks of tomorrow's optical electronics,” the first author of the Nano Letters paper, Vincent Tung, concludes. He is a doctoral student working both in Yang's and Kaner's labs.