Single-Molecule Junctions Formed Using Different Electrode Metals Under an Inert Atmosphere.

The properties of single-molecule junctions, electronic devices approaching the limits of miniaturization, have typically been probed using inert gold electrodes. However, a complete understanding and the ultimate technological exploitation of molecular devices may only be realized if they can be readily evaluated using non-gold electrode metals - a task broadly impeded by the rapid oxidation of such materials in the air. This study demonstrates that single-molecule junctions can be formed using seven metals (gold, silver, copper, platinum, zinc, nickel, and cobalt) under an inert atmosphere inside a glovebox. The characteristic conductance features of atomic-sized junctions are first identified for each metal at room-temperature and ambient pressure, a guiding signature of nanoscale electrode formation. It is then shown that the conductance of single-molecule junctions comprising four different components does not strongly correlate with electrode work function. Snapback measurements 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 metal diffusion constant. 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, a critical step toward the practical utilization of molecule-based nanoelectronic circuitry.