What is graphene?
Graphene is a form of carbon consisting of flat sheets of carbon atoms arranged in a regular hexagonal lattice. It can be thought of as a special case of graphite, but has different physical properties. Graphene is a good conductor of both heat and electricity, and is very transparent and flexible. These properties make it interesting as a transparent electrode (required for photovoltaic solar cells and organic light emitting diodes or OLEDs). The 2010 Nobel prize in physics was awared to Andre Geim and Konstantin Novoselov ‘for groundbreaking experiments regarding the two-dimensional material graphene’. More information about graphene can be found e.g. in the Wikipedia entry.
What is CVD graphene?
CVD refers to a particular way of making graphene – by Chemical Vapour Deposition. In this technique, gases flow over a hot catalyst and react their to grow a graphene film. The composition of the gas and the temperature, composition and surface of the catalyst must be very carefully controlled in order to grow large single layers of graphene. Graphene produced in this way is typically of high quality (i.e large domains and few defects, almost all single-layer).
What are the aims of the GLADIATOR project?
GLADIATOR seeks to scale-up the production of high-quality graphene in order to eventually make it a viable material for the mass production of transparent electrodes for organic electronics. In order to achieve this, graphene must be available in sufficient quantities (and areas), with low enough sheet-resistivity and high enough transparency, and be cheap enough to compete with alternative materials. If this can be achieved, then Europe will be able to supply electrodes that have a low environmental impact (compare e.g. the extraction and shipping of indium for the widely used Indium Tin Oxide electrodes), low cost and high performance (including excellent flexibility).
In order to utilise such graphene electrodes in organic electronics, the project also seeks to develop optmised barrier layers.
What is meant by a barrier layer?
Most types of organic electronics (OLEDs for lighting or displays, solar cells) are very sensitive to water and oxygen from the atmosphere. In order to have a long lifetime they must be sealed in materials that are practically impermeable to water vapour and oxygen, but at the same time transparent (rather like super clingfilm). The demands of the organic electronics industry for such barrier layers are far more severe than those for food or medical packaging, and comparable to the needs of vacuum insulation panels used in buildings. Because graphene doesn’t stick well to most materials, barrier layers which will have a graphene electrode next to them need to be adapted to the graphene.