Light-driven molecular switching achieves 6-order magnitude conductance change in OPE dimers

Functional molecular devices have garnered significant research interest over the past ten years due to their promising potential for applications in both non-volatile memory and novel computing architectures. In this work, we investigate light-induced switching of electrical conductance in linear oligo(phenylene-ethylene)-based (OPE) molecules that incorporate an azobenzene bridging unit to form OPE dimers. We demonstrate that a light stimulus can cause electron transport through the molecule to switch from constructive to destructive quantum interference through an <i>E</i> to <i>Z</i> (<i>trans</i> to <i>cis</i>) azobenzene isomerisation, leading to an on-off conductance ratio of up to 6 orders of magnitude, which is comparable with the best molecular switches obtained to date.