Charge-transport through redox-active single-molecules
The use of molecules to build electronic circuits was historically motivated by the rapid size reductions of conventional electronic components in line with Moore’s Law. Single-molecule devices represent the limit in device miniaturization, with work over the past two decades demonstrating that molecules can indeed function as nanoscale wires, switches and diodes. However, photolithographic technologies have since advanced to a point where they can produce circuits with feature sizes approaching molecular dimensions. Rather than working towards immediate technological applications, present-day efforts in molecular-scale electronics focus on the increased functionality of these materials over their solid-state counterparts as well as on fundamental structure-property relationships. Routine, reproducible studies at the single-molecule level are now possible using scanning probe microscope-based methods, where ‘molecular junctions’ form via the self-assembly of components between nanogap separated electrodes. Where previous studies have primarily used redox-inactive compounds which typically limit the mode of transport to single-step tunneling, we are working to systematically investigate multi-site redox-active species in which sequential tunneling processes are thought to dominate.