Tuning the conductance of a molecular switch

Abstract

The ability to control the conductance of single molecules will have a major impact in nanoscale electronics. Azobenzene, a molecule that changes conformation as a result of a trans/cis transition when exposed to radiation, could form the basis of a light-driven molecular switch. It is therefore crucial to clarify the electrical transport characteristics of this molecule. Here, we investigate, theoretically, charge transport in a system in which a single azobenzene molecule is attached to two carbon nanotubes. In clear contrast to gold electrodes, the nanotubes can act as true nanoscale electrodes and we show that the low-energy conduction properties of the junction may be dramatically modified by changing the topology of the contacts between the nanotubes and the molecules, and/or the chirality of the nanotubes (that is, zigzag or armchair). We propose experiments to demonstrate controlled electrical switching with nanotube electrodes.

Conductance of a conjugated molecule with carbon nanotube contacts

“…The CNT-molecule-CNT transport studies published to date have been limited to model or proposed systems [16,17,18,19,20,21,22,23] where the CNT-molecule interface chemistry, interface geometry, CNT chirality, or molecular conformation were the areas of focus. Comparisons between theory and experiment for these systems have not yet been performed.…”

Current-induced conformational switching in single-molecule junctions

“…An essential requirement for electric circuits of nanoscale dimensions is a molecular device that can be switched between two distinct conductive states. Because of intrinsic bistabilities, many single-molecule junctions reveal switching behavior, e.g., involving cis and trans isomers of a molecule [15][16][17][18][19][20][21][22][23][24][25].…”

Fine structure of the local pseudogap and Fano effect for superconducting electrons near a zigzag graphene edge

“…Another issue this study focuses on is the connection between the local electronic structure of zigzag- infinite graphene, by analogy with similar quantum-dot structures 21,22,23,24 …”