A New Photomechanical Molecular Switch Based on a Linear {\pi}-Conjugated System

TL;DR

This paper introduces a novel photo-addressable molecular switch based on a linear { extpi}-conjugated system, demonstrating reversible conductance changes driven by photochemical isomerization with significant contrast.

Contribution

It presents a new molecular switch design utilizing linear { extpi}-conjugated systems and provides experimental and theoretical insights into its switching mechanism.

Findings

Conductance ratio up to 1000 in switching experiments

Reversible conductance change driven by azobenzene isomerization

Theoretical calculations support experimental observations

Abstract

We report the electronic transport properties of a new photo-addressable molecular switch. The switching process relies on a new concept based on linear {\pi}-conjugated dynamic systems, in which the geometry and hence the electronic properties of an oligothiophene chain can be reversibly modified by the photochemical trans-cis isomerization of an azobenzene unit fixed in a lateral loop. Electron transport measurements through self-assembled monolayers on gold, contacted with eGaIn top contact, show switching with a conductance ratio up to 1E3. Ab initio calculations have been used to identify the most energetically stable conformations of the molecular switch, the corresponding calculated conductances qualitatively explain the trend observed in the photo-switching experiments.