GRAPHENE

April 13, 2014


THE MATERIAL:

If you follow my posts you know I enjoy discussing all areas of technology especially new and exciting products, materials, processes, etc.   The material Graphene is certainly one of those.   Graphene is  a two-dimensional physical form of carbon.  Its amazing properties include being the lightest and strongest material, relative to all other carbon-based materials.    Graphene also has the ability to conduct heat and electricity better than just about any other substance, thereby enabling integration into a huge number of exciting applications.  It also conducts electricity better than copper and is 200 times stronger than steel but six times lighter.  It is almost perfectly transparent and only absorbs two percent (2%) light.  It is impermeable to gases, even those as light as hydrogen or helium, and, if that were not enough, chemical components can be added to its surface to alter its properties.  Graphene is one form — an allotrope — of carbon, the basis of all life on earth. More familiar carbon allotropes include diamonds and graphite. What makes it unique is its thinness — at one atom thick it is as good as two-dimensional. Its flexibility means that it could potentially be used for flexible or wearable devices.  The carbon represents a single layer of carbon that is bonded together in a repeating pattern of hexagons. Graphene is one million times thinner than paper; so thin that it is actually considered two dimensional. A digital photograph of the lattice-structure is given as follows:

LATTACE STRUCTURE

DISCOVERY:

About ten years ago, the Dutch-British physicist Andre Geim stumbled across a substance that would revolutionize the way we understand matter and win him and his colleague Kostya Novoselow the 2010 Nobel Prize for Physics.  That material was graphene — a one atom thin substance.  According to Dr. Geim;   “It’s the thinnest material you can get — it’s only one atom thick. A tiny amount can cover a huge area, so one gram could cover a whole football pitch. It’s the strongest material we are aware of because you can’t slice it any further. Of course, we know that atoms can be divided into elementary particles, but you can’t get any material that is thinner than one atom, or it wouldn’t count as a material anymore”.

 

APPLICATIONS:

Because of its range of extraordinary properties, people are considering using graphene in a myriad of different applications. For example, because graphene is so strong, people want to use it to reinforce plastics, making them conductive at the same time. People are also considering using it to go beyond silicon technology and make our integrated circuits even denser and speedier. Those are just a few examples.   Typically it takes 40 years for a new material to move from an academic lab into a consumer product, but within less than ten years graphene has jumped from a laboratory environment to an industrial lab and now there are pilot products all over the world. Governments and probably more than 100 companies are spending billions on researching these materials.  So, it probably deserves the superlative of being the fastest developing material we know today.

Other applications include:

Solar cells: Solar cells rely on semiconductors to absorb sunlight. Semiconductors are made of an element like silicon and have two layers of electrons. At one layer, the electrons are calm and stay by the semiconductor’s side. At the other layer, the electrons can move about freely, forming a flow of electricity. Solar cells work by transferring the energy from light particles to the calm electrons, which become excited and jump to the free-flowing layer, creating more electricity. Graphene’s layers of electrons actually overlap, meaning less light energy is needed to get the electrons to jump between layers. In the future, that property could give rise to very efficient solar cells. Using graphene would also allow cells that are hundreds of thousands of times thinner and lighter than those that rely on silicon.

Transistors: Computer chips rely on billions of transistors to control the flow of electricity in their circuits. Research has mostly focused on making chips more powerful by packing in more transistors, and graphene could certainly give rise to the thinnest transistors yet. But transistors can also be made more powerful by speeding the flow of electrons — the particles that make up electricity. As science approaches the limit for how small transistors can be, graphene could push the limit back by both moving electrons faster and reducing their size to a few atoms or less.

Transparent screens: Devices such as plasma TVs and phones are commonly coated with a material called indium tin oxide. Manufacturers are actively seeking alternatives that could cut costs and provide better conductivity, flexibility and transparency. Graphene is an emerging option. It is non-reflective and appears very transparent. Its conductivity also qualifies it as a coating to create touch-screen devices. Because graphene is both strong and thin, it can bend without breaking, making it a good match for the bendable electronics that will soon hit the market.

Graphene could also have applications for camera sensorsDNA sequencinggas sensingmaterial strengtheningwater desalination and beyond.

The published paper fromGeim and Novoselov’s was wildly interesting to other scientists because of graphene’s  strange physical properties.  Electrons move through the material incredibly fast and begin to exhibit behaviors as if they were massless, mimicking the physics that governs particles at super small scales.

According to their article published in Scientific American,  “That kind of interaction inside a solid, so far as anyone knows, is unique to graphene,” wrote Geim and another famous graphene researcher, Philip Kim, in a 2008 Scientific American article. “Thanks to this novel material from a pencil, relativistic quantum mechanics is no longer confined to cosmology or high-energy physics; it has now entered the laboratory.”

DRAWBACKS:

Every new technology is somewhat evolutionary instead of revolutionary.  For this reason, obstacles will need to be overcome for mass production and use.

The material is still in an infantile stage compared to developed materials like silicon and ITO. In order for it to be widely adopted, it will need to be produceable in large quantities at costs equal to or lower than existing materials. Emerging roll-to-roll, vapor deposit and other production techniques hint that this is possible, but they’re not yet ready to bring graphene to every mobile device screen out there. Researchers will also need to continue to work at improving  graphene’s transparency and conductivity in its commercial form.

PRODUCTION

While graphene shows promise for transistors, it has a major problem: It can’t switch the flow of electricity “off” like materials such as silicon, which means the electricity will flow constantly. That means graphene can’t serve as a transistor on its own. Researchers are now exploring ways to adjust it and combine it with other materials to overcome this limitation. One technique involves placing a layer of boron nitride–another one-atom-thick material–between two layers of graphene. The resulting transistor can be switched on and off, but the electrons’ speed is slowed somewhat. Another technique involves introducing impurities into graphene.

Graphene may also be emerging too late for many of its possible applications. Electric car batteries and carbon fiber could be made with graphene, but they already rely on activated carbon and graphite, respectively — two very inexpensive materials. Graphene will remain more expensive for the time being, and may never be inexpensive enough to convince manufacturers to switch.

The world is only a decade into exploring what it can do with graphene. In contrast, silicon has been around for nearly 200 years. At the pace research is moving, we could know very soon if graphene will become ubiquitous or just another step in discovering the next wonder material.

I welcome your comments.

 

 

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