Tuning quantum interference through molecular junctions formed from cross-linked OPE-3 dimers

Abstract

This study highlights a novel strategy for tuning the electrical conductance of single molecules by cross linking the molecules to form a dimer. By studying the electrical conductance of dimers formed by cross linking OPE monomers, we demonstrate that the appearance of destructive or constructive quantum interference in cross-linked OPE-based dimers is independent of the nature of the molecular cross link. Instead, the type of the interference is controlled by the connectivity to external electrodes and is determined by the presence or otherwise of meta-connected phenyl rings in the transport path. This is expected to be an important design feature, when synthesising molecules with cross links of different stiffnesses for thermoelectric energy harvesting, since it shows that the stiffness (and hence phonon transport properties) can be tuned without affecting the nature of the electronic quantum interference.