White light with a pinch of graphene
doi:10.1038/nindia.2010.134 Published online 29 September 2010
New research has shown that a minute amount of graphene — a single layer of carbon atoms — can be used to 'tune' zinc oxide (ZnO) nanoparticles to emit white light. ZnO nanoparticles admixed with graphene is promising for use in solid-state lighting devices.
The researchers made graphene from the reduction of single-layer graphene oxide in dimethyl formamide, as well as 2–3 layers of graphene prepared by the arc discharge of graphite in hydrogen. They also studied the emission properties of ZnO nanoparticles in admixture with gallium nitride nanoparticles, nitrogen and boron-doped graphene by illuminating them with ultraviolet light.
The study found that blue light from graphene admixed with green–yellow light from ZnO resulted in the emission of white light. ZnO admixed with 7.5% of the equivalent mass of boron-doped graphene gave a bluish white light. Gallium nitride nanoparticles also demonstrated the ability to tune ZnO to give off white light.
Ultraviolet light triggers electron transfer from ZnO to graphene, which helps to achieve good a photoluminescence spectra and white light emission.
"The use of a minute amount of graphene to tune the photoresponse of ZnO nanoparticles makes this system potentially useful as an ultraviolet light detector," says lead researcher C. N. R. Rao.