Carbon Nanotubes (CNTs), graphene and their compounds exhibit extraordinary electrical properties for organic materials.
Applications
They have a huge potential in electrical and electronic applications such as photovoltaics, sensors, semiconductor devices, displays, conductors, smart textiles and energy conversion devices such as fuel cells and batteries.
Opportunities for CNT
Depending on their chemical structure, carbon nanotubes (CNTs) can be used as an alternative to organic or inorganic semiconductors as well as conductors, but the cost is currently the greatest restraint. Challenges are material purity, device fabrication, and the need for other device materials such as suitable dielectrics. However, the opportunity is large, given the high performance, flexibility, transparency and printability. The cost will rapidly fall as new, cheaper mass production processes are established. In electronics, other than electromagnetic shielding, one of the first large applications for CNTs will be conductors.
Advantages of CNT
In addition to their high conductance, they can be transparent, flexible and even stretchable making them suitable for displays, replacing ITO; touch screens, photovoltaics and display bus bars and beyond. It has higher mobilities which are several magnitudes higher than silicon, meaning that fast switching transistors can be fabricated. CNTs can be solution processed making it suitable for printing over large areas thus reducing the cost of manufacturing. As super capacitors, it bridges the gap between batteries and capacitors, leveraging the energy density of batteries with the power density of capacitors and transistors
CNT material availability
A number of companies are already selling CNTs with metallic and semi conducting properties grown by several techniques in a commercial scale but mostly as raw material and in limited quantities. However, printable CNT inks are beginning to hit the market.
Challenges
Presently purifying the raw material without significantly degrading the quality is difficult in the fabrication of thin carbon nanotube films because there is relatively poor quality of the nanotube starting material, which mostly shows a low crystallinity, low purity and high bundling. There is difficulty in getting good dispersions in solution and to remove the deployed surfactants from the deposited films. However, the selective and uniform production of CNTs with specific diameter, length and electrical properties is yet to be achieved in commercial scale.
Sales
More than one hundred companies and academic institutions are working on carbon nanotubes, graphene and their compounds, with North America focusing more on single wall CNTs, with Japan on top and China second in the production of multi wall CNTS.
Graphene
Graphene is a cheap organic material having good conductivity and hence used in some applications as a significantly cheaper printed conductor compared to silver ink. It is used to make transistors that show extremely good performance.
Graphene is a one-atom-thick planar sheet of carbon atoms that are densely packed in a honeycomb crystal lattice. It can be thought of as a network of carbon atoms and their bonds. It can also be considered an infinitely large aromatic molecule, the limiting case of the family of flat polycyclic aromatic hydrocarbons. Graphene is the basic structural element of several carbon allotropes, including graphite, carbon nanotubes, and other fullerenes.
Making graphene
Researchers made use of spun carbon-rich materials such as plexiglass onto a nickel or copper substrate to make graphene. When exposed to hydrogen and argon gas, the metal acted as a catalyst, and the material reduced to pure carbon, producing a single layer of grapheme.
Researchers of Rice University have used ordinary table sugar to process sheets of graphene. The breakthrough in graphene manufacturing is notable not only for its use of sugar, but also because it resulted in a common, non-toxic material that can be used at low temperature.
Applications
Useful for applications such as touchscreens, liquid crystal displays, organic photovoltaic cells, organic light-emitting diodes, component of integrated circuits, graphene nanoribbons for making ballistic transistors, conductive plates of ultracapacitors and for a new technique for rapid DNA sequencing