A new method of growing graphene nano ribbons may be the key to unlocking it’s full potential in electronic applications, according to scientists at Oak Ridge National Laboratory in Tennessee.
Phys.org reported, “‘Confinement changes graphene‘s behavior,’ said An-Ping Li, a physicist at the Department of Energy’s Oak Ridge National Laboratory. Graphene in sheets is an excellent electrical conductor, but narrowing graphene can turn the material into a semiconductor if the ribbons are made with a specific edge shape.”
Previous efforts to create graphene nanoribbons were attempted using a metal substrate that hindered the ribbons’ useful electronic properties.
Now, scientists at ORNL and North Carolina State University report in the journal Nature Communications that they’ve successfully grown graphene nanoribbons without a metal substrate.
Instead, they injected charge carriers that promote a chemical reaction that converts a polymer precursor into a graphene nanoribbon. At selected sites, this new technique can create interfaces between materials with different electronic properties. Such interfaces are the basis of semiconductor electronic devices from integrated circuits and transistors to light-emitting diodes and solar cells.
Per phys.org, “Graphene is wonderful, but it has limits,” said Li. “In wide sheets, it doesn’t have an energy gap—an energy range in a solid where no electronic states can exist. That means you cannot turn it on or off.”
When a voltage is applied to a sheet of graphene in a device, electrons flow freely as they do in metals, severely limiting graphene’s application in digital electronics.
“When graphene becomes very narrow, it creates an energy gap,” Li said. “The narrower the ribbon is, the wider is the energy gap.”
Phys.org continued, “In narrow graphene nanoribbons, with a width of a nanometer or even less, how structures terminate at the edge of the ribbon is important too. For example, cutting graphene along the side of a hexagon creates an edge that resembles an armchair; this material can act like a semiconductor. Excising triangles from graphene creates a zigzag edge—and a material with metallic behavior.”The full study and its results can be seen below