The Smallest Molecular Switch

TL;DR

This paper demonstrates through ab-initio calculations that benzene-dithiolate molecules on gold can act as electrically bi-stable switches, changing conductance states via tip-induced conformational changes, representing the smallest molecular switches known.

Contribution

It reveals that Au/BDT/Au nanowires can function as bi-stable molecular switches, a novel finding in molecular electronics.

Findings

Molecules exhibit two low-energy conformations with different symmetries.

Conformational changes induce switching between high and low conductance states.

Switching can be triggered by tip movement or excitation.

Abstract

Ab-initio total energy calculations reveal benzene-dithiolate (BDT) molecules on a gold surface, contacted by a monoatomic gold STM tip to have two classes of low energy conformations with differing symmetries. Lateral motion of the tip or excitation of the molecule cause it to change from one conformation class to the other and to switch between a strongly and a weakly conducting state. Thus, surprisingly, despite their apparent simplicity these Au/BDT/Au nanowires are shown to be electrically bi-stable switches, the smallest two-terminal molecular switches to date. Experiments with a conventional or novel self-assembled STM are proposed to test these predictions.