"We've created what is essentially the world's thinnest light bulb," said Columbia professor James Hone. "This new type of 'broadband' light emitter can be integrated into chips and will pave the way towards the atomically thin, flexible and transparent displays, and graphene based on-chip optical communications."
Until now, researchers have been unable to integrate incandescent light onto a chip because the filaments must be very hot in order to glow in the visible range and microscale metal wires cannot withstand such temperatures.
However, graphene is said to achieve high temperatures without melting the substrate or the metal electrodes. The team discovered that as graphene heats up, it becomes a poorer conductor of heat and the high temperature stays confined to a small 'hot spot'.
"The visible light from atomically thin graphene is so intense that it is visible even to the naked eye, without any additional magnification," said Young Duck Kim, a researcher at Columbia.
SNU Professor Yun Daniel Park noted the team was working with the same material used by Thomas Edison when he was developing the incandescent light bulb. "Edison originally used carbon as a filament for his light bulb and here we are going back to the same element, but using it in its pure form – graphene – and at its ultimate size limit – one atom thick."
The team has demonstrated the scalability of their technique by creating large scale of arrays of graphene light emitters. It is now characterising device performance, including how quickly they can be turned on and off, and working on ways to integrate them into flexible substrates.
