It is well established that graphene has exceptional electric features and is highly transparent to visible light. The combination of these two features makes it an excellent material for the transparent electrodes used in flexible electronics. But before this material can find its place in the commercial world, a cost-effective method to produce films with high electrical conductivity must be found.

The issue may just have been solved by Jong-Hyun Ahn, Byung Hee Hong and colleagues in Korea, Singapore and Japan1. The researchers have produced 30-inch sheets of graphene that can be readily transferred to a generic substrate, and the film has been used to fabricate touch-panel displays with high flexibility and superior electrical properties and transparency compared to the indium tin oxide used in conventional touch panels.

The graphene films were grown by chemical vapor deposition of carbon onto a sheet of copper foil with a diagonal dimension of 30 inches. To obtain uniform graphene films, the copper sheet was rolled up and suspended in a reaction cylinder, and prior to carbon deposition was heated-treated at 1,000 °C. At this point, Ahn, Hong and their co-workers applied a three-step roll-to-roll transfer protocol.

The first step involved carefully attaching an adhesive thermal polymer tape to the graphene film. The copper foil was then chemically etched away, and the graphene film on the polymer tape was transferred to the target substrate by another roll-to-roll process at 90–120 °C to ensure thermal release from the tape.

Fig. 1: A touch-screen panel fabricated using the roll-to-roll method.Image courtesy of J.H. Hong, M.Y. Kim

The beauty of the process is that the graphene film can be chemically ‘doped’ during growth. Moreover, the transfer protocol can be repeated indefinitely to obtain films having several layers of graphene, which results in higher conductivity. As an example, the team produced a four-layer graphene film with low sheet resistance and 90% transparency, which was then used to fabricate a prototype touch-screen display (Fig. 1).

The achievement could have a considerable impact in industry. “We believe that our results have proved the potential of graphene for practical applications, and could trigger the commercialization of graphene-based electronics very soon,” says Hong.