Bias-Voltage-Driven Single-Molecule Switches with Positive and Negative Responses

Developing all-electrically driven molecular switches with different responses is crucial for molecular circuits to achieve complex logical operations and self-protection. Herein, benzothiadiazole (BTZ)-centered molecular wires were synthesized, and their charge transport properties were investigated. Conductance measurements revealed that all wires exhibited bias voltage-driven switching behaviors under low bias voltage. Specifically, the wires with thiomethyl as an anchor displayed positive response switching, while those with pyridine as an anchor showed negative response switching. The maximum on/off conductance ratios reached up to 28.8 and 30.2 for positive and negative response switches, respectively, which are among the highest values for all-electrically driven molecular switches. Control experiments and theoretical calculations indicated that the switching characteristics originated from the dependence of the frontier energy levels of the wires and the Au-π interactions of the junctions on the bias voltage. These findings will aid in the design of high-performance bias voltage-driven molecular devices and advance the development of molecular electronics.