Graphene for large-area flexible electronics

Electrically and thermally conductive, but also transparent, graphene was first isolated from graphite in 2004. Six years later, the work was awarded a Nobel Prize in Physics and the potential applications of this material continue to increase seemingly without bound.

The EU is supporting the GLADIATOR (Graphene layers: Production, characterization and integration) project to facilitate industrial-scale production of less expensive, higher quality and larger area graphene sheets. This will make graphene an important alternative to expensive tin indium oxide for transparent electrodes whose market is predicted to be worth over USD 11 million in 2016.

Chemical vapour deposition (CVD) is perhaps the best way to produce graphene, but reliable large-volume production of high-quality undoped graphene is still problematic. CVD plays a critical role. Within the first year, the team optimised the catalysts and increased catalyst coverage of the substrate. Further, scientists demonstrated reuse of the expensive copper catalysts used in the transfer process five times with no effect on graphene quality. The green technique to minimise natural resource usage has now been patented.

Researchers have also made important progress increasing the conductivity of graphene by external doping. In addition, excellent progress has been made improving substrate and barrier properties to prevent water and humidity damage for large-area flexible transparent electronics such as organic light-emitting diodes.

One of the main challenges with CVD is separating the graphene from the substrate after growth, particularly for large areas. Scientists have already lowered the average delamination time for large sheet sizes by an order of magnitude and are investigating the potential of removing smaller tiles and reconnecting them to form a graphene 'patchwork'.

An in-line CVD tool for process monitoring able to evaluate both optical and electrical properties is under development and will be complemented by technology to assess electrical properties after transfer from the substrate. The team has already conducted in vitro toxicity tests and is currently completing in vivo tests with promising results.

The 16-partner GLADIATOR consortium has achieved the critical mass to develop technology that improves graphene production. The project has already produced a patent and several high-profile publications. Potential socioeconomic impact could be tremendous.