Graphene giving life to science fiction
CAPE TOWN – Graphene is an amazing material of the 4th Industrial Revolution (4IR) that is hundreds of times stronger than steel, can stretch by 20-25%, is so light that a sheet of graphene covering a football field will weigh less than a gram, is better than silver and copper at carrying heat, transmits 97-98% of light (compared to the 80-90% of glass), is a super conductor of electricity, and is impermeable to gases.
This wonder material has opened up numerous possibilities and has the potential to create the next-generation of electronics currently only seen in Sci-Fi movies. It is now possible to imagine such incredible future situations as extremely fast transistors (a device used to amplify or switch electronic signals and electrical power) and semiconductors; lightning fast, yet super-small lightweight computers; invisibility cloaks; smart phone batteries that last weeks between charges; and computers that we can fold up and carry in our pockets.
The remarkable properties also make graphene an ideal candidate for future electronic devices and as channel material for radio frequency (RF) flexible electronics. The flexible property of graphene allows for various electronic devices on flexible substrates, such as flexible, all-solid-state graphene-based supercapacitors, wearable touch panels, strain sensors, and self-powered triboelectric sensors. Triboelectric charging is a type of contact electrification on which certain materials become electrically charged after they are separated from a different material with which they were in contact.
All these devices have been recently demonstrated with applications such as flexible, improved touchscreen devices with a coating of graphene to make it more robust and durable. Indium-tin oxide is currently used for touch screens due to its excellent conductivity, but it is very brittle.
Graphene has also been used in the newer bendable smart phones and wristwatches that are on the market. Future smart phones that could be worn on the wrist and tablets that could be rolled or folded up like a piece of paper are being planned.
Graphene will probably also lead to foldable televisions and electronic flexible newspapers containing content that can be updated via wireless data transfer. Flexible, wearable electronics take advantage of graphene's mechanical properties as well as its conductivity.
Due to the ultrahigh transparency of graphene it is expected to enable smart and extremely durable windows in homes, with the possible ability to display content and virtual curtains. Silicon transistors have consistently become smaller and more powerful over the last few decades, but are now approaching basic limitations imposed by the laws of physics.
The unique characteristics of thinness and high conductivity make graphene an ideal semiconductor that could dramatically increase the speed at which information is processed. Since it is just one atom thick and has the ability to conduct electricity at room temperature, graphene semiconductors could replace current technology in computer chips that have been pushed to their physical limits.
Miniaturisation of electronic technology is an important challenge to the electronics industry. Over the years many electronic devices have become smaller such as computers. Numerous technologies, increasingly powerful processors and growing memory capacity are packed into smart phones. Now researchers at the University of Manchester in the UK have created the world's smallest transistor by using graphene to replace silicon. This breakthrough will enable even smaller and more efficient devices, since the smaller the transistor, the better they perform within circuits and the less energy they use.
The electronic properties of graphene are highly unusual. The electrons are faster and much more mobile, allowing computer chips to work much faster and with less power than the chips we are using today. To be more precise, electrons move through graphene almost like photons (particles of light) at speeds close to the speed of light. Recent experiments have already shown that graphene chips are significantly faster than current silicon chips. And faster chips mean faster computers.
But since graphene is the world’s thinnest material and also the material with the highest surface-area to volume ratio it is a promising material for the storage of energy. Graphene can enable batteries and supercapacitors to store more energy and to charge faster. The creation of supercapacitors out of graphene will be one of the greatest breakthroughs in electronic engineering. Unlike the exponential progress in electronic components over the past decades, power storage solutions such as batteries and capacitors have been a serious limiting factor due to size, power capacity and efficiency as everyone owning a smart phone will know too well.
During experiments, laser-scribed graphene (LSG) supercapacitors demonstrated power density comparable to that of high-power lithium-ion batteries that are in use today. Furthermore, LSG supercapacitors are highly flexible, light, quick to charge, thin, and comparably inexpensive to produce. Graphene supercapacitors could thus provide massive amounts of power while using much less energy than conventional devices.
The problem with solar and wind power until now has been the necessity of a grid base load, especially during the night and wind still days. At the University of Manchester researchers are investigating graphene's potential in grid applications and the storing of wind and solar power.
Graphene is also being used to improve not only the capacity and charge rate of batteries but also the lifespan. While lithium is able to store large amounts of energy, that potential amount diminishes with every discharge/recharge due to electrode wear. When graphene tin oxide is used as an anode (positively charged electrode) in lithium ion batteries, the batteries last much longer between charges, and with almost no reduction in storage capacity.
This significant improvement in capacity and lifespan makes technology such as electronically powered vehicles much more viable in the future. These much higher capacity batteries would last much longer and could be recharged within seconds, rather than minutes or hours.
Graphene could also make batteries more flexible and light that they could be stitched into clothing, used in smart contact lenses or even implanted in the human body. For soldiers who easily carry up to 7 kg of batteries at a time, the impact of graphene could be huge. Carrying less weight, and using batteries that can be recharged by the sun or body heat would allow them to remain in the field for longer.
Graphene is both highly conductive and transparent and therefore has great potential as a material in solar cells by replacing silicon. When a photon hits silicon it only releases one electron, while graphene releases multiple electrons for each photon that hits it. This property makes graphene superior in the conversion of solar energy, with a projected 60% efficiency compared to the roughly 25% efficiency that silicon cells are capable of.
Graphene has therefore inspired the development of new technologies by improving and augmenting the efficiency of solar photovoltaic panels, such as those manufactured by Solargise in Canada in collaboration with Elcora Advanced Material. Solar panels of the future will certainly be much more energy efficient.
It is also very probable that the market will in the future see clothing containing flexible graphene-enhanced photovoltaic cells and miniature supercapacitors, allowing people to charge their mobile telephones and tablet computers in a matter of minutes or even seconds whilst walking.
Graphene is an amazing material and the likelihood that we will develop numerous innovative and currently unimaginable technologies that take advantage of graphene's unique properties is highly likely. And just a plastic did not simply replace older materials such as metal and wood, but completely changed our culture into one where disposability and convenience overtook durability, so might graphene again change our whole culture and our way of living during the 4IR.
Professor Louis C H Fourie is a futurist and technology strategist [email protected]