Rigidity of the conductance of anchored dithioazobenzene opto-mechanical switch

TL;DR

This study investigates the conductance stability of an azobenzene-based molecular switch, revealing that conductance remains similar across conformations and is significantly reduced by linker groups, questioning its effectiveness as a switch.

Contribution

The paper provides a detailed theoretical analysis of conductance in an azobenzene molecular switch, highlighting the rigidity of conductance across conformations and the impact of linker groups.

Findings

Conductance is similar in cis and trans conformations.

Linker groups reduce conductance by up to two orders of magnitude.

The device shows limited potential as a conductance-based molecular switch.

Abstract

Reversible opto-mechanical molecular switch based on a single azobenzene molecule suspended via thiolate links between realistic models of gold tips is investigated. Using a combination of the transfer matrix technique and density functional theory we focus on conductance of the nano-device in the two (meta)stable cis and trans junction conformations. We find the conductance of both conformations to be broadly similar. In qualitative agreement with related experiments, we find that the same nano-device with one/two methylene linker group(s) inserted on one/both ends of the azobenzene molecule is driven into tunneling regime and reduces the conductances by up to two orders of magnitude, again almost uniformly for both conformations. These results clarify the huge differences in switching ratios found previously and indicate that this nano-device is not particularly suited for use as a molecular switch based on conductance change.