Peipei Yuan

Effects of different electrodes and substituent groups on molecular switching

We investigate the electronic transport properties of hydroxychalcone and flavanone molecules sandwiched between zigzag-edge or armchair-edge graphene electrodes using density functional theory and non-equilibrium Green’s function. The substitutions of electron-donating –NH2 and electron-withdrawing group –NO2 with armchair-edge graphene electrodes enhance the switching performance, which are analyzed by the transmission spectra, molecular projected self-consistent Hamiltonian and transmission eigenstates. It is found that the negative differential resistance effect observed in the device results from molecule–electrodes coupling with increased bias. The results suggest that different electrodes and substituent groups can influence the currents and switching ratios, indicating a potential application in future molecular circuits.

FIRST-PRINCIPLES STUDY ON PHOTOSWITCHING BEHAVIOR IN SINGLE MOLECULE JUNCTION

We carry out first-principles calculations based on density functional theory and non-equilibrium Green’s function to investigate the electronic transport properties of a diarylethene-based molecule sandwiched between two Au electrodes. This molecular switch can be reversed between open and close forms by using light stimulation. We analyze the switch behavior of these two forms through the current–voltage curves, transmission spectra and molecular projected self-consistent Hamiltonian. It has been found that the current of the close form is significantly larger than the open form, and there is a large and stable switch ratio in a wide bias window. This result indicates that this molecule can become one of the good candidates for optical molecular switch in the future.