Transparent Carbon Nanotube Films Likely Successor to ITO for Commercial Applications

Apr 10, 2009 by David Hecht weblog
Flexible carbon nanotube film on plastic. Photo courtesy of Unidym.

(PhysOrg.com) -- Will the legacy of Nobel prize winner Richard Smalley finally be fulfilled? Ever since his pioneering work in the mid 1990's on the synthesis of carbon nanotubes, companies have been struggling to find a commercial application for this amazing material. There was a nanotech "bubble" of start-up companies, none of which managed to successfully IPO due to lack of realizable commercial revenue. Is that about to change? Recent research by Rice University and Unidym indicate that a fully realizable application is finally here for carbon nanotubes. Fortunately, it's in one of the fastest growing display markets, touch screens.

Carbon nanotubes (CNTs) are tiny hollow cylinders of carbon with tremendous electrical and optical properties. It turns out that very thin CNT films as thin as 10 or 20 nanometers are transparent to and can conduct enough electricity to make them useful for many applications where these properties are needed. These applications include thin film solar cells, organic LEDs, and touch screens.

Currently, a ceramic material called indium tin oxide (ITO) is used in these applications. This material is deposited in vacuum and is quite brittle. Carbon nanotubes, on the other hand, can be deposited from solution, and are remarkably robust and flexible. Films can be coated about 50 times faster than ITO films, and are almost unbreakable when flexed, tapped, strained, or smashed with a hammer, while ITO films are brittle and easy to crack under strain.

Researchers predict that the first applications for these transparent CNT films will be as the in touch screens. This is because they already meet all technical requirements, and ITO has an issue in that it tends to crack after repeated use, thus degrading the response. Touch screens are a rapidly expanding market due to the popularity of the iPhone amongst other devices. By the end of the year, CNT films will begin to replace ITO in touch screens. As the technology continues to improve it will continue to take market share from ITO. This will be a remarkable achievement, and may issue in a new day for carbon nanotubes in various markets. I think Smalley would be pleased.

More information can be found in: "Continuous and Scalable Fabrication of Transparent Conducting Films" by Dan, Irvin, and Pasquali in ACS Nano, published on the web April 08, 2009.

© 2009 PhysOrg.com

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User comments : 12

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John_balls
3 / 5 (2) Apr 10, 2009
Sweet! I can't wait to these actually hit the market.
superhuman
3.3 / 5 (6) Apr 10, 2009
Carbon nanotubes are seriously toxic, you certainly don't want them in your touchscreen.

Here is just a sample of articles showing their toxicity:
Pulmonary Toxicity of Single-Wall Carbon Nanotubes in Mice 7 and 90 Days After Intratracheal Instillation
http://toxsci.oxf...77/1/126

Carbon nanotubes introduced into the abdominal cavity of mice show asbestos-like pathogenicity in a pilot study
http://www.nature...111.html

Lung inflammation and genotoxicity following pulmonary exposure to nanoparticles in ApoE-/- mice.
http://www.ncbi.n...alpos=14&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DefaultReportPanel.Pubmed_RVDocSum

Adverse effects of industrial multiwalled carbon nanotubes on human pulmonary cells.
http://www.ncbi.n...alpos=33&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DefaultReportPanel.Pubmed_RVDocSum

SWCNT suppress inflammatory mediator responses in human lung epithelium in vitro.
http://www.ncbi.n...nalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DiscoveryPanel.Pubmed_Discovery_RA&linkpos=1&log$=relatedarticles&logdbfrom=pubmed

Potential in vitro effects of carbon nanotubes on human aortic endothelial cells.
http://www.ncbi.n...nalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DefaultReportPanel.Pubmed_RVDocSum

Environmental:
Acute and long-term effects after single loading of functionalized multi-walled carbon nanotubes into zebrafish (Danio rerio).
http://www.ncbi.n...alpos=16&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DefaultReportPanel.Pubmed_RVDocSum

Ecotoxicity of engineered nanoparticles to aquatic invertebrates: a brief review and recommendations for future toxicity testing.
http://www.ncbi.n...nalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DiscoveryPanel.Pubmed_Discovery_RA&linkpos=5&log$=relatedreviews&logdbfrom=pubmed

You can go to pubmed and search for more:
http://www.ncbi.n...s/entrez
earls
3.7 / 5 (3) Apr 10, 2009
The nanotubes are embedded in the plastic.

While the nanotubes do pose serious health risks as evidenced by your extensive list of links, armed with knowledge of the risks will allow us to overcome them and take full advantage of the beneficial properties of the nanotubes.
dhecht
3.5 / 5 (4) Apr 10, 2009
While the health risks of carbon nanotubes are still a topic of much discussion, for these devices they will be hermetically sealed inside the device. The carbon nanotube film faces inwards towards the touch screen device, such that the person's finger actuating the device touches the backside (uncoated side) of the plastic, so will not come into contact with the tubes. Furthermore, the nanotubes will be overcoated with a polymer binder layer, in which they will be locked into place. Don't forget that almost every device uses materials that are unhealthy if used improperly. And carbon is fairly low on the list of unhealthy elements.
zbarlici
3.7 / 5 (3) Apr 10, 2009
"While the health risks of carbon nanotubes are still a topic of much discussion,"



Are you joking me? This technology`s already been proven way hazardous... the govt should get on the bandwagon



The typical cell of the human body is 10um(micrometers) in size. The smallest nanotube is 0.4nm(nanometers). That`s 0.0004um (HELLO??!!) Don`t be BS`ing yourself and nobody that they`re not toxic theyll seriously screw up your genome(DNA sequenciing! HELLO!!?? anybody home?)...



"...they will be hermetically sealed inside the device. The carbon nanotube film faces inwards towards the touch screen device, such that the person's finger actuating the device touches the backside (uncoated side) of the plastic, so will not come into contact with the tubes..."



Whatever... all these devices will age ant the protective layers will get brittle and break. w Because CNT`s have so many positive properties, sooner or later everything you use will have CNT`s in it, and the landfills will be full of CNT`s, they will be carried away by water and wind. But theres no way itll ever get to that point because for sure before that the risks associated with the CNTs will have been realised.

Sure CNTs have a lot of potential but they have to be studied properly. The stupid Govt have to fully investigate the hazards associated with nanotube technology. They are small enough so they can penetrate your cells and REALLY F_ _ K YOU UP.



I`m sure if they gave a rat`s ass the studies would already have been done, hazards properly addressed, and because of Govt intervention would have raised more awareness to the CNT field. As a result we would have a lot more CNT development companies and we would probably have realised a lot more with this technology than what we have now...



Also when they finally wake up and do a study on the technology because of some human turning into a monster, they will most likely strictly regulate the CNT`s.. as they must be properly disposed of. That means ANY product using CNT`s must be identified as so.



Nonetheless the potential for CNT`s is great.
superhuman
5 / 5 (2) Apr 11, 2009
The nanotubes are embedded in the plastic.

They cannot be completely embedded in plastic as the idea here is to have a conductive transparent surface.

While the health risks of carbon nanotubes are still a topic of much discussion, for these devices they will be hermetically sealed inside the device. The carbon nanotube film faces inwards towards the touch screen device, such that the person's finger actuating the device touches the backside (uncoated side) of the plastic, so will not come into contact with the tubes.

Yes, that's certainly much better if they will be sealed inside and not in contact with skin but still those devices would have to be recycled properly and if added to something mass produced like cell phones they are bound to end up in the environment sooner or later.

Don't forget that almost every device uses materials that are unhealthy if used improperly.

Many devices do contain toxic materials but none of them poses the risks nanoparticles do, the cells simply did not evolve to deal with such materials. Other toxic substances can be handled by cells pretty well unless present in high concentrations, but CNT, which penetrate both skin and cell membranes easily, cannot be handled by cells and simply accumulate in your organism, the cells have no efficient way to get rid of them.

All in all if you weigh in both health and environmental risks and our still very limited knowledge about their toxicity the dangers certainly outweigh the benefit of having less brittle touch screens (especially since current touch screens are perfectly fine).

CNT have many great properties but their health risks need to be taken very seriously, and it is especially important now as it looks like they are bound to end up in many mass produced items very soon.
jimbo92107
3 / 5 (2) Apr 11, 2009
Maybe I'm mistaken, but aren't these particular carbon nanotubes permanently bound up in a polymer? Unless these plastic sheets somehow release nanotubes, how can they become a health hazard? Even if the plastic sheet were burned, wouldn't such delicate structures be destroyed?
vos
3 / 5 (2) Apr 11, 2009
nanotubes are harmless ... they only cause cancer in California.
Soylent
1 / 5 (1) Apr 12, 2009
nanotubes are harmless ... they only cause cancer in California.


Oh, don't worry. California won't stand in the way of this particular bit of progress, even if it does turn out to actually be a significant health hazzard.

Without a cheap and effective replacement for indium tin oxide transparent electrodes it will be impossible to make cost effective solar photovoltaics in the not so distant future and this is far out and ahead the lead contender.( well, as cost effective as todays panels, not cost effective compared to other technologies; PV may never be that).
Nartoon
1 / 5 (2) Apr 18, 2009
Just use gloves.
EdP
1 / 5 (1) Apr 29, 2009
Drugs in drinking water.



Chemicals in all living creatures on Earth.



Giant islands of plastics floating in the pacific ocean.



And 50 years from now, most cells will be poluted with nanotubes, and there is no way of removing it.





Let's give a round of aplause for the human race!
Soylent
1 / 5 (1) Apr 30, 2009
Drugs in drinking water


The quality of drinking water is better and for more people than it has ever been in human history.

Chemicals in all living creatures on Earth.


Living creatures ARE chemicals.

Giant islands of plastics floating in the pacific ocean.


A few milligrams of inert plastic per square metre. Oh the humanity!

And 50 years from now, most cells will be poluted with nanotubes, and there is no way of removing it.


Good, then maybe you'll finally STFU and do something useful.