Charge transport through perylene bisimide molecular junctions: An electrochemical approach

Single molecular junction conductances of a family of five symmetric and two unsymmetric perylene tetracarboxylic bisimides (PBI) with variable bay-area substituents were studied employing a scanning tunneling microscope (STM)-based break junction technique. The stretching experiments provide clear evidence for the formation of single molecular junctions and π–π stacked dimers. Electrolyte gating demonstrates a distinct gating effect in symmetric molecular junctions, which strongly depends on molecular structure and properties of the solvent/electrolyte. Weak π–π-coupling in the unsymmetric dimers prevents rectification.