Superfast computing
Graphene could also revolutionise telecoms. "Researchers have already demonstrated incredible speeds over 100 times the current speed of the internet backbone in transmitting information," says Curran. "At present, optical switches, which route information over optical cables, respond at rate of a few picoseconds – around a trillionth of a second. With graphene, this can be improved to one hundred femtoseconds, which is almost 100 times quicker."
Electrons can travel across graphene at almost the speed of light, nearly 250 times faster than they move through silicon – graphene's killer app could be ultrafast transistors. On the lookout for silicon's replacement for years, the world of computing is holding its breath.
However, for graphene to replace silicon, scientists need to solve the problem of the on-off state, which could take years, and may not prove possible.
"Currently graphene transistors are difficult to turn off, and that can be a game-stopper because in digital electronics you need the off-state to block current flow, and to have no dissipation when the transistor is in the off-state," says Curran. This is known as the 'bandgap' problem.
The 'bandgap' problem
"We are targeting two-dimensional materials with a bandgap to create a transformational new flexible transistor device that will enable a wide range of high frequency switching applications," says Mike Banach, Technical Director at Cambridge-based FlexEnable. One of those materials is graphene.
FlexEnable has just joined the Graphene Flagship, an EU initiative to support the transition of graphene and other advanced materials from academia to industry. The 140+ members include Nokia, Airbus, Philips, Alcatel Lucent, BASF, Ericsson and BAE, which gives clues as to who's most excited about graphene, and why. Think more efficient electronics, lighter aircraft components and faster telecoms.
So why hasn't graphene been commercialised yet? "Graphene is a material, not a technology," says Banach. "It does take time to develop good technology from new materials, and I believe that the wider commercialisation of graphene will occur as more applications emerge that truly utilise the material's unique properties."
The transition from university labs to the real world all hinges on the development of cost effective industrial processes. That's exactly what FlexEnable is doing – last year it showed off a truly flexible display based on a transparent graphene conductor, which was integrated into its flexible transistor array. Using graphene as the completely transparent conductive layer on plastic, the aim is to create flexible, unbreakable LCD and OLED displays, a market forecast to be worth £25 billion (around $38 billion, or AU$50 billion) by 2020.
The brittle truth
However, there is a major manufacturing problem at the core of the embryonic graphene manufacturing industry. "Graphene frays at the edges in most manufacturing processes, which leads to brittleness," says Curran. "It is also very difficult to manufacture in a pure form over an area, as one of the key beneficial properties come from its symmetrical, honeycomb-like single atomic layer structure."
Graphene is also a potentially hazardous substance. "There is also an issue of these ultra-small sharp edges piercing lung or skin cells and perhaps interfering with their function by rupturing cell membranes," says Curran.
Scarce and expensive
If graphene isn't easily manufactured, neither is it easily sourced; there's a lack of high-quality defect-free graphene available. Though there are graphite producers in South Korea, India, Mexico, Ukraine, North Korea, Brazil, Turkey and the Czech Republic, the majority of graphite mining is in China, and threefold price hikes in recent years have earned it a place on the British Geological Survey's most recent 'risk list' of chemical elements or element groups of economic value.
The price increase is in response to the increased demand for graphite – the most stable form of carbon – to manufacture golf clubs, tennis rackets, and electrical components and circuitry. "The amount of material to cover the head of a pin can cost anywhere between £1,000 to £3,000, so when we scale this up to the size of small handheld consumer appliances, we are speaking about a premium price," says Curran. "By comparison, electronics-grade silicon is about 800 times cheaper." So semiconductors probably aren't going to swap to graphene anytime soon.
That hasn't stopped 10,000 graphene-related patents proposing that this so-called wonder material be used in everything from electric vehicle batteries and aircraft, through to superfast phone chargers, medical diagnostic devices, sports equipment, and even super-high buildings.
Ice on helicopter blades could be melted in seconds. Graphene could even be used as the base material for solar cells, which could lead to innovations like photovoltaic paint – the walls of a house could literally soak up energy from the sun, and heat the house. There are even suggestions that graphene could soak up radiation, and be used to treat paralysis.
However, the true potential of graphene will always remain theoretical until scientists conquer the problems of both mass production and the band-gap. And either of those could take decades to be resolved.
