|
The development of nanosized molecular electronics has been precluded by the difficulty in wiring molecules between nanoelectrodes. Therefore, a new molecular interconnect method needs to be developed to produce a molecular device from a long molecule. Here we report an interconnect method for molecular devices that can control electrode-molecule binding, molecular orientation, and device functions. Our self-organized interconnect method consists of three steps with three kinds of molecules: interface control molecule (4-iodo-benzenethiol), orientation control molecule (polyrotaxane), and a function control molecule (diarylethene). The interconnect method is a simple liquid solution process in which nanoelectrodes that are placed with a nanoscale spacing are dipped into three kinds of solutions sequentially. In the first step, the electrodes and interface control molecules are bound to each other through sulfur. The interface control molecules bound to the electrodes are the π-conjugated molecules that have thiol and iodo groups. In the second step, Suzuki coupling reaction binds the orientation control molecules with the interface control molecules. The orientation control molecules are π-conjugated molecules that covered with α-cyclodextrin to keep the molecular structure almost straight and control the growth direction of the molecules along the electrode spacing and have two boronic acid groups at their ends. In the third step, Suzuki coupling reaction binds to function control molecules (diiododiarylethene) with orientation control molecules. After the second and third steps, we measured electric conduction in thus-formed molecular wires at room temperature under ultraviolet radiation to the molecules to drive them into the closed-ring state, and then applied visible light to switch them into the ring-opening state. The electric current in the molecular wire increased under ultraviolet radiation by 20-fold, but it was reduced under visible light, indicating a reversible switching property with light. The optical switching property was not observed after the second step, indicating that the switching molecules were bound chemically in the third step, and that the electrodes were wired with the optical switching molecule. |