Amphoteric Doping of Carbon Nanotubes by Encapsulation of Organic Molecules:
Electronic Transport and Quantum Conductance

Vincent Meunier, Bobby G. Sumpter, Robert J. Harrison

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The unique structural and electronic properties of carbon nanotubes provide a tremendous potential for applications in the field of molecular electronics. However, practical realization of new nanotube-based devices hinges on a number of outstanding problems, such as the capability in achieving large-scale air-stable and controlled doping. Recent experimental evidence (Nature Materials 2, 683,2003) suggests that amphoteric doping of single-walled carbon nanotubes is possible by using simple organic molecules processing different electron affinities and ionization energies. The charge transfer processes induced by the organic molecules tend to stabilize the carbon nanotube in air as well as to achieve efficient n- and p-type doping. Particularly promising is the apparent stability and fine tunability at low carrier density of the n-doped nanotubes, something that has to-date been very difficult to achieve by other processing methodologies. In order to optimize and investigate the electronic transport processes in carbon nanotubes doped with organic molecules we have performed large-scale quantum electronic structure calculations coupled with a Greenís function formulation for determining the transmittance and conductance. This research has demonstrated how the electronic structure of a carbon nanotube can be manipulated quite easily by encapsulating appropriate organic molecules. Computational optimization of the molecule and/or carbon nanotube to achieve desired electronic properties are now on the near horizon. In addition, the chemical reactivity of carbon nanotubes toward air can also be examined within a similar computational framework.

For more information contact:

Vincent Meunier


Oak Ridge National Laboratory, LDRD

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