Multiple striking negative differential resistance in a polyyne wire doped with an organometallic fragment

Inspired by the recent experimental progress on the synthesization of a new type of molecule, a polyyne wire doped with the organometallic Ru ( dppe ) 2 fragment, which exhibits superior electronic properties to similar organic molecules reported before, we studied the electronic transport of it contacted with Au electrodes through first-principles calculations. Multiple striking negative differential resistance (NDR) behavior is observed, where the current could decrease to nearly zero. Moreover, such a phenomenon is found to be robust to the conformational change of the molecule, indicating it is the intrinsic feature of it. Further analysis shows that it is the suppression of the transmission peaks at the border of the bias window that results in the NDR. And, the suppression is resulted from the decay of the local density of states in the two-probe system, especially in the central axis of the molecule, where the states are found to originate from the p orbital of C atoms and the d orbital of Ru atoms. The multiple striking NDR behavior is achieved at the single-molecule level under low bias, showing great application potentials. These findings may throw light on the development of molecular devices.