Regulation of π-π interactions between single aromatic molecules by bias voltage.

π-stacking interaction, as a fundamental type of intermolecular interaction, plays a crucial role in generating new functional molecules, altering the optoelectronic properties of materials, and maintaining protein structural stability. However, regulating intermolecular π-π interactions at the single-molecule level without altering the molecular conformation as well as the chemical properties remains a significant challenge. To this end, conductance measurement with thousands of single molecular junctions employing a series of aromatic molecules, we demonstrate that the π-π coupling between neighboring aromatic molecules with rigid structures in a circuit can be greatly enhanced by increasing the bias voltage.