Single-Molecule Junctions with Strong Molecule−Electrode Coupling

We fabricated Au−TTF−Au (tetrathiafulvalene, TTF) and Au−TSF−Au (tetraselenafulvalene, TSF) single-molecule junctions using a nanofabricated mechanically controllable break junction. We found that Au−TSF−Au and Au−TTF−Au single-molecule junctions have one and two stable configurations, respectively, and that the Au−TTF−Au single-molecule conductance is larger than that of Au−TSF−Au. The difference in single-molecule conductances of the two types of junctions originates from the difference in the strength of the molecule−electrode coupling through face-to-face overlapping configurations.