Single-molecule junctions formed using different electrode metals under an inert atmosphere

The electrical and mechanical properties of single-molecule junctions, electronic devices approaching the limits of miniaturization, have typically been probed using inert gold electrodes. Such studies have clearly exposed the role of the molecular bridge and linker groups, as well as the impact of the surrounding environment (solvent, temperature, electric field), on interfacial charge transport and chemical reactivity. However, a complete understanding and the ultimate technological exploitation of molecular devices may only be realized if they can also be readily evaluated using non-gold electrode metals – a task broadly impeded by the rapid oxidation of such materials in air. Here we demonstrate that single-molecule junctions can be formed using seven metals (gold, silver, copper, platinum, zinc, nickel, cobalt) under an inert atmosphere inside of a glovebox. We identify the characteristic conductance features of atomic-sized junctions for each metal at room temperature and ambient pressure, a guiding signature of nanoscale electrode formation. We further show the conductance of single-molecule junctions comprising the same molecule and up to five different metals does not strongly correlate with electrode work function, corroborating previous reports and inviting future targeted studies to rationalize the trends observed. Snapback measurements on five metals reveal that the size of the nanogap opened upon breaking atomic point contacts exponentially correlates with the material’s melting point, a proxy for the rate of surface atom diffusion. Together, this work exposes exciting new opportunities to experimentally probe the influence of electrode metal on the formation, stability, and function of these nanoscale structures.