Scientists from the Georgia Institute of Technology and Columbia Engineering in the US have shown they can generate electricity from a layer of material that’s just one atom thick. The generator is made from molybdenum disulphide (MoS2), which is a clear, flexible and extremely light material that opens up huge possibilities for the future of electricity generation.
The new electrical generator is an example of piezoelectricity, or electricity that’s generated from pressure. Piezoelectric materials have huge potential to be used to create materials that can charge devices, such as footwear that powers an iPod. But until now, scientists have struggled to make these materials thin and flexible enough to be practical.
However, it’s been predicted that a substance capable of forming single-atom-thick molecules, or two-dimensional layers, would be highly piezoelectric.
To test whether MoS2 would be piezoelectric on the atomic scale, the team flaked off extremely thin layers of MoS2 onto a flexible substrate with electrical contact.
Because of the way these flakes were created, each had a slightly different number of layers - for example, while some were just one-atom-thick, others were eight-atoms-thick.
The scientists tested the piezoelectric response of these flakes by stretching the material, and measuring the flow of electrons into an external circuit.
Interestingly, they discovered that when the material had an odd number of layers, it generated electricity when stretched. But when it had an even number of layers, there was no current generated.
A single one-atom-thick layer of the material was able to generate 15 millivolts of electricity when stretched.
They also found that as the number of layers increased, the amount of current generated decreased, until eventually the material got too thick and stopped producing any electricity at all.
Computational studies suggest that this is because the atomic layers all have random orientations, and they eventually cancel each other out.
The research team also arranged these one-atom-thick layers of MoS2 into arrays, and found that together they were capable of generating a large amount of electricity.
This suggests that they’re a promising candidate for powering nano electronics, and could be used to create wearable technologies.
“This material – just a single layer of atoms – could be made as a wearable device, perhaps integrated into clothing, to convert energy from your body movement to electricity and power wearable sensors or medical devices, or perhaps supply enough energy to charge your cell phone in your pocket,” said James Hone, professor of mechanical engineering at Columbia engineering and co-leader of the research, in a press release.
*Update 8am 21/10/2014: We originally said the material could generate 15 megavolts when stretched instead of 15 millivolts. This was a typo, we apologise for any confusion.*