Electro-responsive Tri-state Switch in Supramolecular Circuits

Efficiently manipulating charge transport at the molecular level is critical to developing multifunctional and responsive molecular electronic devices. Here, we report the first electroresponsive tristate switch in a supramolecular circuit, overcoming the binary limitation and enabling richer logic encoding, governed solely by a bias voltage (electric field). At low electric fields, p-phenylenediamine (PPD) molecules exhibit a high-conductance state, which transitions successively to two distinct low-conductance states as the external electric field strength increases. This precise control of supramolecular junctions through electric field manipulation achieved an on/off ratio G_H/G_L of ∼1.25×10³, which is one of the largest values reported to date. Flicker noise analysis and density functional theory calculations reveal the intrinsic mechanism for the observation, i.e., electric field promoting the formation of trimer supramolecular junctions leads to the striking on/off ratio. These findings provide new insights into the design of molecular circuits with tunable conductance, paving a way for the design of molecular computation, memory devices, and sensors.