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US researchers have made a breakthrough with an industrial-scale graphene production process.
The single-atom-thick carbon material’s characteristics, such as strength, flexibility and high conductivity, mean it has been mooted for use in many future products and applications.
However, it is difficult to produce in large quantities. Current methods include quickly removing sticky tape from a block of graphite and making films of the substance on copper or nickel foils.
Now, though, researchers at MIT and the University of Michigan have developed a process that produces sheets of graphene on large panes of glass. The research leader, Anastasios John Hart, Mitsui career development associate professor of mechanical engineering at MIT, said: “To make the graphene useful, you have to get it off the metal and onto a substrate, such as a silicon wafer or a polymer sheet, or something larger like a sheet of glass. But the process of transferring it can damage and contaminate it.”
The new method still uses a metal film as the template, but makes graphene on both the top and bottom of the film. Silicon dioxide is used as a substrate, with a film of nickel on top. Chemical vapour deposition is used to deposit a graphene layer on the nickel. The nickel film can then be peeled away, leaving just the graphene on the nonmetallic substrate.
The process eliminates the need to attach the graphene to the intended substrate, for example a large plate of glass for a display screen, or a thin, flexible base for a lightweight, portable solar cell.
The research team has partnered with a glass manufacturer, Guardian Industries, to develop the process. Hart said: “To meet manufacturing needs, it must be scaleable. We still need to improve the uniformity and quality. But the ability to produce graphene directly on nonmetal substrates could be used for large-format displays and touch-screens, and for ‘smart’ windows that have integrated devices such as heaters and sensors.”