Graphene, a form of pure carbon arranged in a lattice just one atom thick, has interested researchers with its unique strength and its electrical and thermal conductivity. However, it lacks the ability to form a band gap needed for devices such as transistors, computer chips and solar cells. Now, a team of scientists at the Massachusetts Institute of Technology (MIT) has found a way to produce graphene in significant quantities in a two- or three-layer form.
When the layers are arranged just right, these structures give graphene the much-desired band gap-an energy range that falls between the bands, or energy levels, where electrons can exist in a given material.
“It’s a breakthrough in graphene technology,” says Michael Strano, the Charles and Hilda Roddey associate professor of chemical engineering at MIT. The new work is described in a recent paper published in the journal Nature Nanotechnology.
Graphene was first proven to exist in 2004 (leading to the 2010 Nobel Prize in physics), but making it in quantities large enough for anything but small-scale laboratory research has been a challenge. The standard method remains using adhesive tape to pick up tiny flakes of graphene from a block of highly purified graphite (the material of pencil lead)-a technique that does not lend itself to commercial-scale production.
While it’s hard to predict how long it would take to develop this method to the point of commercial applications, Strano says, “It’s coming about at a breakneck pace.” A similar solvent-based method for making single-layer graphene is already being used to manufacture some flat-screen television sets, and “this is definitely a big step” towards making bilayer or trilayer devices, he says.
