Graphene: finding practical applications for a remarkable material
After Manchester scientists successfully isolated graphene from graphite for the first time in 2004 by using adhesive tape, later going on to win the Nobel Prize for Physics for their research, graphene instantly became the most interesting new material for many scientists. But what is this material with all of these special qualities? We talked to TMC Employeneur Jos Giesbers, who has done many studies into graphene for Philips Research and is now developing products using the material for Philips Innovation Services (PInS).
“Graphene is a two-dimensional layer of carbon atoms that are interconnected in a honeycomb structure. The most remarkable property of graphene is its electrical conductivity, which is even better than copper, with charge carriers travelling at almost the speed of light. This means we can now do relativistic quantum mechanics research in a piece of graphene instead of doing it at CERN in Switzerland. Graphene is also transparent and because it’s a perfect crystal, very strong and chemically inert. On top of that, you can stretch it by 20%, so it’s very flexible and you could roll it up around a pen.”
“These qualities were found in lab tests done on graphene at a micrometre scale. At Philips, we wanted to test these qualities on larger pieces of graphene. Bigger pieces of graphene are produced by growing it from a gas phase onto a metal. Multiple pieces of graphene grow at the same time and attach to each other where they meet. But since every piece is not perfectly orientated towards the others, imperfections arise at those joining points, creating a patchwork of graphene structures. We at Philips wanted to know how these imperfections influenced the quality of graphene for certain applications.”
“Because of its great electrical conductivity, thinness, flexibility and transparency, graphene seems perfect for an application in OLED-lighting. But our research showed that the imperfections had a negative impact on conduction, which resulted in us needing multiple layers to get the best results. But as we did that, we had to pay with a loss in total transparency. The imperfections also had a negative influence on the strength upon bending, making the graphene we used only as flexible as the current standard in OLEDs, Indium-Tin-Oxide. In another study, we were able to show that these imperfections also made graphene no longer impermeable to, for example, water. Water molecules were able to pass through the material exactly at the point of those imperfections, and actually made the imperfections clearly visible when reacting with a water sensitive layer positioned underneath the graphene. With that knowledge, we can now easily find imperfections in graphene without using a transmission electron microscope for example.”
“We are now looking at using the strength of the material to reinforce other materials, to make them thinner. I think in the short-term, the strength quality shows the most potential – for use as a polymer in 3D printing, for example. A second short-term application might be super capacitors and batteries. Graphene is practically only surface, which gives you a great area for the exchange and storage of electrons. For the future, this could mean an increase in battery capacity, faster charging times and longer life. Improvements in better quality graphene is continuous and it’s just a matter of time till we reach the Holy Grail of perfect graphene, and then the possible applications of the material will be innumerable.”