Nanotube Transparent Conductors Challenge Technology for Touchscreens

Nanowerk spotlight recently did an article on the recent work of Dr. Mark C. Hersam, a professor of Materials Science and Engineering at Northwestern University and his team of graduate students. The team used a technique called density gradient ultracentrifugation (DGU) to produce single-walled carbon nanotube transparent conductors (SWCNTs) with uniform electrical and optical properties. This enables the production of transparent conductors consisting predominantly of metallic SWCNTs with small diameter distributions.

What is unique about this is that thin films formulated from these carbon nanotubes have 10-fold improvements in conductivity compared to current carbon nanotube materials. Films generated from sorted metallic SWCNTs offer two major improvements. The first is that DGU eliminates poorly conducting, strongly absorbing The second is the angstrom-level control over nanotube diameter afforded by DGU results in films possessing a variety of different colors which offer an unprecedented degree of control over the optical properties of the transparent conductor.

Conductive SWCNT coatings enhance transparent conductor performance in multiple applications and the high transmittance regions could be employed to increase the efficiency of devices such as solar cells, flat panel displays, and LEDs. On the other hand the low transmittance regions of the coatings could be used to filter out unwanted portions of the optical spectrum. Further this has potential to speed up development in energy efficient technologies such as organic LEDS and organic photovoltaic devices.

The technology developed by Dr. Hersam can challenge the current technology for touch screens. The current technology consists of indium tin oxide which is brittle, has limited chemical, electrical properties that greatly depend on the film preparation, and the amount of indium is rapidly decreasing. Professor Hersam has demonstrated the use of metallic nanotubes to make thin films that are semitransparent, highly conductive, flexible, and come in a variety of colors that can potentially have significant importance in the future.

This article was well done as the journalist regularly writes on the subject of nano technology and also conducted an interview with the researcher, Professor Hersam. Upon looking over the journal article I think the author could have made a strongly conclusion and tied together the beginning of the article with the end of the article better than he did. For example, in the research paper published in the journal the final sentence is "As longer SWNT sources become available, we expect that metallic SWNTs of monodisperse diameter will increasingly challenge ITO in transparent conductor applications, particularly those in which a high degree of optical turnability is required." I feel as if the author of the news article touched on most of these issues in the article but could have made a stronger case for increasing the monodisperse diameter.

However, it is likely that the author did not want to become too technical in the article as the journal paper did. This may also stem from my preference to read the journal paper and get my news and information from there. Upon seeing this information published at other major news websites such as Science Daily, it becomes clear that the average reader would not have understood and been able to comprehend effectively the article that I am critiquing from nanowerk. This is likely due to the difference in audiences and thus writing styles by the authors writing the article. Nanowerk may be geared towards an audience base that has more interest and knowledge in materials science issues than your average science reader. I think the nanowerk article did a great job of getting the reader's attention in the first few paragraphs of the article, but did not do quite as good a job for the conclusion. In the later paragraphs the focus of the article became misleading and the major issues involved were somewhat lost. A more effective conclusion could have been written to better bring home the point of the article. (Also of note is that the article abbreviates single-walled carbon nanotube transparent conductors as SWCNTs where as the journal article abbreviates them as SWNTs)

References:

http://www.nanowerk.com/spotlight/spotid=5286.php