EU-funded researchers have conclusively shown that large-scale, cost-effective manufacturing of graphene is possible, opening up new product possibilities and ensuring that Europe remains at the cutting edge of applied nanotechnology.
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Graphene is a carbon sheet just one atom thick that offers manufacturers amazing strength, flexibility and electrical conductivity. A key barrier to transferring graphene-based innovations from the lab to the market, however, has been a lack of large-scale, cost-effective production techniques.
Material benefits for Europe
The EU-funded GRAFOL project, completed in September 2015, has taken a significant step forward in addressing this challenge by combining a new mass manufacturing technique with an effective means of ‘growing’ graphene, and by using advanced spectroscopy – the study of visible light scatter by materials – to accurately evaluate graphene growth.
Project coordinator John Robertson from the University of Cambridge, UK, is certain that the €6.9 million investment from the EU will be repaid handsomely in the opportunities created for SMEs and in the growth of new markets for graphene-based products.
“The project results will definitely attract companies from different sectors to graphene technology, because the production costs are now at an affordable level for their industries,” he says. “The companies involved in the project also plan to take the project results to the next level by introducing new products in the market, like for example the roll- to-roll deposition tool, and all carbon interconnects.”
The key breakthrough has been the application of this roll-to-roll, or R2R, processing – a mass manufacturing technology – that offers improved cost-effectiveness and production scale benefits in the field of graphene. R2R, which as its name implies involves processing flexible material onto a large roll, has been used extensively to produce flexible electronics, thin-film solar cells and separation membranes efficiently and cheaply.
This technique has now been adapted to achieve large-scale graphene production. In addition, the GRAFOL team has adapted a technique known as chemical vapour deposition (CVD) for growing low-cost batches of single or layered graphene onto silicon wafers.
“The R2R CVD tool is the key result to come out of GRAFOL,” confirms Robertson. “This is the first time something like this has been realised commercially; other developments in this field have mainly appeared in scientific journals. We have shown that the tool, which operates at atmospheric pressure and at reduced operating temperature, is the best route to low-cost manufacture.”
The project also conclusively demonstrated that graphene can replace indium-tin-oxide (ITO) as the transparent electrode in light-emitting diodes (LEDs). While ITO is currently one of the most widely used transparent conducting oxides, limited supplies of indium and the fragility and lack of flexibility of ITO layers has led researchers to seek out viable lower cost alternatives for lighting.
“We demonstrated that this works, and that it is flexible, but the main point here is cost,” Robertson emphasises. “Nobody will use graphene if it costs many times more than other materials. This is the big deal about the R2R tool; that it can lower the cost.”
LEDs offer many advantages over incandescent light sources, including lower energy consumption, longer lifetime, improved physical robustness, smaller size, and faster switching. They are increasingly used in applications as diverse as aviation lighting, automotive headlamps, advertising and home lighting.
While the project has demonstrated the feasibility of mass manufacturing graphene, Robertson remains realistic about the challenges ahead. “Applying graphene to other substrates still requires a transfer process that forms a big log jam and there needs to be a large-scale commercial demonstration of this step,” he says. Nonetheless, the GRAFOL team believes its project represents an important step forward towards mass-produced graphene products.
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