A new type of light sources has been created, based on individual graphene nanoribbons

Researchers at the CNR Institute for Nanotechnology, Modena, Italy, and the University of Strasbourg, France, have demonstrated workable light sources based on a single graphene nanoribbon just 7 atoms wide. By measuring the parameters of light, the scientists found that the brightness of these sources is comparable to the brightness of light-emitting devices based on carbon nanotubes; in addition, the color of the emitted light can be controlled by changing the voltage applied to the nanoribbon.

Note that the electronic and electrical properties of graphene have been studied quite well in recent years, however, much less is known about the optical properties of this material. One of the disadvantages of graphene as a light-emitting material is that it does not have an electronic band gap. However, when graphene is formed into long narrow strips, nanoribbons, several atoms wide, it acquires a band gap, which opens up opportunities for efficient light emission.

Some time ago, scientists have already experimentally demonstrated the possibility of using graphene in light-emitting devices. However, the devices created earlier could emit only rather weak light or they consisted of a large number of graphene nanoribbons operating in parallel. Against this background, obtaining bright light emitted by a separate nanoribbon opens up much wider possibilities for using the optical potential of this material.

The high intensity of the light emitted from the nanoribbon was obtained by shaping the nanoribbon using a microscope tip. One end of the nanoribbon was attached to a flat metal base that acted as one of the electrodes. The second end was raised above the surface and attached to the second electrode. This approach made it possible to reduce the optical bonding between the nanoribbon and the base, which otherwise suppresses the light-emitting ability of graphene.

Measurements have shown that the nanoribbon emits light in the amount of 10 million photons per second. This is 100 times higher than the radiation intensity of devices based on monomolecular materials and this is comparable to the radiation intensity of devices based on carbon nanotubes. In addition, the scientists found that the position of the main peak of the spectrum of the emitted light depends on the applied voltage, which makes it quite easy to change the color of the light emitted by the nanoribbon.

“In the very near future, we will study the effect of the width of a graphene nanoribbon on the spectrum of light emitted by it. We have no doubts about the existence of such a dependence, because the band gap directly depends on the width of the tape itself, “the researchers write,” In parallel, we will try to find out how the presence of defects in the graphene structure affects the light-emitting ability. And as a result of all this, a technology should be born that allows you to integrate “nanoribbon” light sources into complex circuits of electronic chips.

“Source: www.dailytechinfo.org