Mechanical force adjusts the bonding orientation with respect to the electrode to regulate electronic transport in single-molecule devices

Abstract

The paper studies the mechanical force adjusting the bonding orientation with respect to the molecule to regulate electronic transport in single-molecule devices by using first-principle calculations. We designed molecular junctions by connecting tetraphenylene molecules to gold electrodes via amino or pyridine anchoring groups. By applying horizontal compressive force, the bonding orientation angle was adjusted from 0° to 45°, and the corresponding current-voltage characteristics were calculated. For the single-molecule device connected to gold electrodes via amino group, the transmission spectra exhibited a pronounced leftward shift as the orientation angle increased, accompanied by a gradual rise in the current. In contrast, the single-molecule device connected to gold electrodes via pyridine group showed no significant shift in the transmission spectra under mechanical compression. When the orientation angle increases to 30° and 45°, significant negative differential resistance behaviors are observed in the molecular devices. Our research results provide an understanding of the influence of bonding orientation on the electronic transport properties in molecular devices, and offering an approach to the realization of molecular functional devices.