Towards Understanding Energy Level Alignment in Single Molecule Charge Transport with Break Junctions

Single molecule based devices represent the ultimate limit in device design, but uncovering the major factors that determine energy level alignment in single molecule junctions and their effect on the quantum transport through single molecules is still a major challenge. We have developed a robust experimental platform, using lithographically-fabricated mechanically controlled break-junctions (MCBJ) in conjunction with high-speed custom instrumentation to address this issue. By introducing electrostatic moments in the molecular design, we are able to tune the energy level alignment in the molecular junction and reveal its influence on electronic transport in a set of closely related molecules. Analysis of the resulting data benefits from advanced data clustering methods capable of revealing the deep structure of the highly stochastic data.