What Kind Of Graphene For Which Application?
The development of graphene has a very high pace. The production of graphene is made in different ways, for instance by chemical vapor deposition or by growth on Si, and the applications and quality vary a lot. In this blog post we will try to help you deciding which kind of graphene is good for a given application. We will also introduce you to the ratio price/quality that has a real importance for mass scale production.
Properties of graphene
Selecting graphene for a given device (flexible book, sensor, lab on chip, you name it) is a choice based on its outstanding properties. Not every device would benefit from these features of course, but it is amazing to see the number of fields where graphene outperfoms other standard materials.
Property |
Graphene |
Electron mobility (at room temperature) |
2,5 x 105 cm2 V-1 s-1 |
Young's Modulus |
1TPa |
High thermal conductivity |
> 3000 WmK-1 |
Optical absorption |
3,00% |
In addition to that, graphene is impermeable to any gases can sustain high densities of electric current.
These values are for very high quality graphene. In reality, most graphene types will come close to these numbers, so depending on your application you would like to use very pure forms of graphene or not.
Different types of graphene
Liquid phase and thermal exfoliation
Liquid phase and thermal exfoliation is a process in which graphite is exposed to solvents or a thermal shock that will allow the splitting of individual graphene flakes. Despite mass production is already reached, during this process several layers are created, and sometimes impurities are inserted in the flakes. One can also collect smaller platelets of graphene by using nanotubes instead of graphite but the process are longer and more expensive.
Synthesis on Silicon Carbide
Silicon Carbide is a widely used material in the field of electronics. By sublimating the atoms of Si, the remaining face of the SiC has a graphite surface. Nowadays the number of layers of graphene could be controlled and the quality is very high over a wide area (crystallites of some hundreds of micrometers ). Drawbacks are the high cost of SiC and the high temperatures required to produce the sublimation. The two factors will probably confine SiC graphene to niche markets like high-frequency transistors or metrology resistance standards.
Chemical Vapor Deposition
CVD represents nowadays the easiest process to prepare high quality graphene in large amount. After evaporation of carbon atoms on a copper foil, the method allows transfer of graphene to a broad range of substrates. For instance it can be transfered to silicon waffers were nano sized electronics can be designed. CVD graphene does not contain many defects ( grain boundaries or inclusion of thicker layers are common but not critical).
The quality over price ratio already allows CVD graphene to be used for many applications like transparent and flexible electronics. Also, since graphene is an efficient gas barrier, it is used as an anti-corrosion coating.
Other types
Other types of graphene exist, like mechanical exfoliation of molecular assembly, but there use is very limited. Indeed, with mechanical exfolliation, for istance, you can only produce small flakes. The interest is bounded to the academic level for very specific experiments.The same limitation occurs with molecular assembly for instance.
Applications of Graphene
Graphene could be used in various fields like sensors and metrology, biotechnology, high-frequency transistors, flexible and transparent electronics, batteries or photonics. For most of these areas, CVD graphene is the best candidate in terms of cost and quality. However, few of them could require special fabrication methods. Nanoelectronics for example could be done more easily with molecular assembly of graphene. Graphene ink or graphene paint that could be used into printed electronics could be fabricated with liquid phase exfoliation.
You have an application but you are not sure about the technology you need? Tell us on our forums. We will be here to answer you.
To know more :
Novoselov KS, Fal'ko VI, Colombo L, Gellert PR, Schwab MG, & Kim K (2012). A roadmap for graphene. Nature, 490 (7419), 192-200 PMID: 23060189