Scientists have observed for the first time a light emission from individual graphene nanoribbons. This discovery may lead to future development of the intense graphene-based light sources.
Graphene nanoribbons also referred to as nano-graphite ribbons are narrow strips of graphene with less than 50 nm in width that are arranged in a honeycomb structure. These graphenes have interesting optical, electrical, and mechanical properties that could be applied in electronics, transparent conductive films, actuators, optoelectronic devices, composites and sensors, among others, according to Sigma-Aldrich.
In the new study, which was published in the current issue of Nano Letters, the researchers have detailed their observations of the first electroluminescence from individual graphene nanoribbons. The study was led by Deborah Prezzi at the CNR-Nanoscience Institute in Modena, Italy and Guillaume Schull at the University of Strasbourg in France and other colleagues.
Graphene is known for its excellent electronic properties, yet little is known about its optical properties. It is known that graphene sheets do not have an optical band, which could be a disadvantage of using it as a light-emitting device. However, in the recent studies, they indicated that when graphene was cut into thin ribbons into smaller sizes, the graphene obtains a sizable optical band gap that leads to the possibility of light emission, according to Phys.org.
Schull said that in their study, they prove that individual graphene nanoribbons could be used as intense, stable, and controllable light sources. She further said that these could be decisive steps leading to real-world optoelectronic applications with nanoscale organic systems.
The scientists have utilized a new configuration method and discovered that the individual graphene nanoribbons connect two metallic electrodes that create an electronic circuit for the first time. Then, the team used the microscope tip to partially lifted the nanoribbon so that it lay to a certain extent on the substrate and quite suspended.
The results showed that the individual graphene nanoribbons had an extreme optical emission of up to 10 million photons per second. This is about 100 times more extreme than the emission that was gauged for the single-molecular optoelectronic devices in the past.
The scientists also found that the color could be changed by adjusting the voltage. The team plans to study this influence of the width of graphene nanoribbons on the color of the discharged light in the future.