Researchers create two-segment nanotubes with distinct semiconducting domains

October 21, 2011 by Bob Yirka, report

SEM and TEM micrographs of a research sample. Image: Science, DOI:10.1126/science.1210369
( -- A group of researchers working in Japan has devised a means of creating dual segmented nanotubes where each segment has separate and distinct semiconducting properties. The team describes how they were able to create the unique nanotubes which are joined by means of a heterojunction, in their paper published in Science.

The team, led by Takanori Fukushima and Takuzo Aida and working out of the RIKEN Advanced Science Institute in Saitama, Japan, created the new nanotubes by growing first one segment from an HBC derivative, then adding bipyridine side-chains to help with metal binding. They then coated the outside of the segment with to stabilize them and to prevent them from clumping.

Once they had the first segment, the next task was to grow another segment of a different type from one of the ends of the first segment. They did this by treating a second HBC derivative with just four fluorine atoms, which helped the two segments stick to one another while the second segment grew.

The end result was a single nanotube with segments that had distinctly different . In this case, one side was made of type p (which has relatively few electrons) while the other side was made of type n semiconducting material (which has a lot of electrons).

Such nanotubes could be used to more efficiently move the hole in an electron-hole pair that strikes a solar cell, shunting it off to the p type semiconductor side of the nanotube and the electron to the type n material side. By making the more efficient, i.e. maximizing the electron-hole separation without dissipation, the new technology could conceivably wind up replacing conventional methods used in solar energy and other technologies. Such nanotubes should also extend the life of many such and could be grown in virtually any shape, making them usable in a wide variety of applications.

The next challenge for the group will be to figure out a way to grow the nanotubes standing up so that the whole process can be standardized and then of course industrialized. Once that’s accomplished, the new could be used in all manner of new devices, ranging from lasers to solar collectors to more efficient transistors.

Explore further: High-mobility semiconducting carbon nanotubes

More information: Supramolecular Linear Heterojunction Composed of Graphite-Like Semiconducting Nanotubular Segments, Science, 21 October 2011: Vol. 334 no. 6054 pp. 340-343 DOI: 10.1126/science.1210369

One-dimensionally connected organic nanostructures with dissimilar semiconducting properties are expected to provide a reliable platform in understanding the behaviors of photocarriers, which are important for the development of efficient photon-to-electrical energy conversion systems. Although bottom-up supramolecular approaches are considered promising for the realization of such nanoscale heterojunctions, the dynamic nature of molecular assembly is problematic. We report a semiconducting nanoscale organic heterojunction, demonstrated by stepwise nanotubular coassembly of two strategically designed molecular graphenes. The dissimilar nanotubular segments, thus connected noncovalently, were electronically communicable with one another over the heterojunction interface and displayed characteristic excitation energy transfer and charge transport properties not present in a mixture of the corresponding homotropically assembled nanotubes.

Related Stories

High-mobility semiconducting carbon nanotubes

April 29, 2004

T Durkop, B M Kim and M S Fuhrer reviewed experiments to determine the resistivity and charge-carrier mobility in semiconducting carbon nanotubes in Journal of Physics: Condens. Matter (vol. 16, 2004, R553-R580) Electron ...

Carbon nanotube avalanche process nearly doubles current

February 9, 2009

( -- By pushing carbon nanotubes close to their breaking point, researchers at the University of Illinois have demonstrated a remarkable increase in the current-carrying capacity of the nanotubes, well beyond ...

High Value Semiconducting Carbon Nanotubes

July 12, 2004

A simple technique has been developed for producing high value semiconducting carbon nanotubes from samples of single and multi walled carbon nanotubes. The Oxford Invention is a technique for purifying samples of carbon ...

Unzipping Carbon Nanotubes Can Make Graphene Ribbons

April 20, 2009

( -- By "unzipping" carbon nanotubes, researchers have shown how to make flat graphene ribbons. Graphene, which is a one-atom-thick sheet of carbon that looks like chicken wire, has unique electrical properties ...

Sandia researcher examines the physics of carbon nanotubes

May 1, 2008

Carbon nanotubes, described as the reigning celebrity of the advanced materials world, are all the rage. Recently researchers at Rice University and Rensselaer Polytechnic Institute used them to make the “blackest black” ...

Recommended for you

'Astrocomb' opens new horizons for planet-hunting telescope

February 19, 2019

The hunt for Earth-like planets, and perhaps extraterrestrial life, just got more precise, thanks to record-setting starlight measurements made possible by a National Institute of Standards and Technology (NIST) "astrocomb."


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.