Organic Nano-Devices Composed by Carbon NanoTube/Oligophenylenes/Carbon NanoTube Junctions: Transition-Voltage Spectroscopy, Applications and Chirality versus Geometry

摘要

Molecular junctions offer a viable alternative for applications in nanoscale electronic devices. In this work we investigate the electronic transport in single-molecules junctions composed by CNT/oligophenylenes/CNT through of the Transition Voltage Spectroscopy (TVS) by means of the coherent transport model given by the Landauer-Buttiker formula for the case of the conductance (G) that is related to transmittance T(E, V-e, theta) of a two-lead system where negative differential conductance voltage V-NDC matches with minima voltage V-min in the Fowler-Nordheim plot. The results exhibit: (i) one linear region (showing resistive behavior given by Ohm's Law); (ii) two nonlinear regions (resonance and NDC); (iii) the possibility of a fourth nonlinear region of operation (or second resonance). We find that the conductance (G/G(o)) in these systems is strongly correlated to the Frontiers Molecular Orbitals (HOMO and LUMO) and to the chiral index psi, which depends only on atomic positions and it is found quantitatively by Group Theory calculations. The atomic positions are related the conformation change (twist angle, theta) where each phenylene ring can rotate about the single C-C bonds that connects them that influences in the symmetry properties (psi) and electronic transport (G/G(o)) of the CNT/oligophenylene/CNT junctions, giving rise to the cos(2)theta law.