Scientists use graphene to create the world's smallest light bulb

The miracle material is a near-perfect conductor of electricity

Scientists have created the world’s smallest light bulb from a one atom-thick layer of graphene, the miracle material that promises to transform everything from smartphones and computers to cars, buildings and satellites.

The ultrathin graphene was turned into a superheated filament – just like the thin wire of an incandescent light bulb – which glowed at a temperature of about 2500C.

The light was so intense it could be seen with the naked eye even though it was on the atomic scale, which meant the high temperatures were confined to a tiny “hot spot” and did not damage the silicon chip on which it was mounted, scientists said.

The discovery could be used as the basis of a new kind of switching device for future optical computers that use pulses of light rather than electricity to process and transmit digital information far faster than conventional silicon chips, they said.

 

It is the first time that scientists have been able to create a computer chip which has its own visible light source, said James Hone, professor of mechanical engineering at Columbia University in New York, co-author of the study published in the journal Nature Nanotechnology.

“We’ve created what is essentially the world’s thinnest light bulb. This new type of ‘broadband’ light emitter can be integrated into chips and will pave the way towards the realisation of atomically thin, flexible and transparent displays, and graphene-based on-chip optical communications,” Professor Hone said.

“We are just starting to dream about other uses for these structures, for example as micro-hotplates that can be heated to thousands of degrees in a fraction of second to study high-temperature chemical reactions or catalysis,” he said.

Graphene, which was discovered by two Russian émigré scientists working at the University of Manchester, is composed of layers of carbon laid down in a lattice structure just one atom thick. It is extremely strong yet lightweight, and a near-perfect conductor of electricity.

The Columbia scientists, working with researchers in South Korea, attached small strips of graphene to microscopic metal electrodes which passed an electric current through the suspended strips causing them to heat up and bright, visible light.

“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 of Columbia, the co-lead author of the study.

 

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Graphene was discovered by two Russian émigré scientists (AFP)

Creating such small light sources on the surface of a computer chip is considered essential for developing the fully integrated “photonic” circuits of optical computers, which will in theory outperform the processing and speed of conventional silicon chips in today’s computers, the researchers said.

The researchers also found that it was possible to vary the wavelengths of the light by altering the distance of the graphene wafers suspended over the silicon substrate of the chip – a potentially useful way of tuning the light source and expanding its “bandwidth”.

“This is only possible because graphene is transparent, unlike any conventional filament, and allows us to tune the emission spectrum by changing the distance to the substrate,” Dr Kim said.

Graphene's Potential

Drinking water

Graphene could be used to desalinate seawater to make it drinkable – tiny pores in its crystal lattice could let water molecules through while blocking salt.

Smartphones

Being both transparent and conductive, graphene could be perfect for the new generation of touchscreens.

Rust-free cars

Graphene repels water and is highly conductive. This combination delays the oxidising reaction that  causes rust.

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