Statistical investigation of current-voltage characterization in single molecule-metal junctions

Abstract

We show statistical measurements of single molecule-metal contacts using the mechanically controllable break junction technique. The measurements are carried out in a solvent, in order to allow in situ binding of the molecules to the metallic contacts during the measurements. Statistics is gathered by opening and closing the junctions repeatedly and recording current-voltage characteristics at various stages of the opening and closing curves. By modeling the data with a single level model we can extract parameters such as the position of the molecular energy level, which carries the current, and the coupling between the metal and the molecule. In first experiments we use this method to characterize different anchoring groups, which mediate the mechanical and electrical coupling between the metallic electrodes and the molecules. We use tolane molecules, which are structurally simple, as model systems for this purpose.