Encapsulated Organic Molecules in Carbon Nanotubes: Novel p-n junctions

Recently Lu et al [1] have shown that both p- and n-type doping can be realized on single-walled carbon nanotubes (SWCNTs) by encapsulating various organic or organometallic molecules, such as TCNQ, F$_{4}$TCNQ, TTF, and TDAE, with different electron affinities or ionization potentials. Using a method that combines density functional theory and Keldysh nonequilibrium Green's functions, we have investigated the charge transport properties of such encapsulated SWCNTs. We have found that the current-voltage characteristics of p-type and n-type doped SWCNTs are very different, which can be explained in terms of their individual band structures. More importantly, if these p-type and n-type doped SWCNTs are joined together, p-n junctions can be achieved. Current-voltage curves for such p-n junctions will be presented. \begin{enumerate} \item J. Lu, S. Nagase, D. Yu, H. Ye, R. Han, Z. Gao, S. Zhang, and L. Peng, Phys. Rev. Lett. \textbf{93,} 116804 (2004). \end{enumerate} *Supported through the NSF grant No. DMR-0097187