Transport properties of a single-molecular diode with one backbone, and two backbones in parallel: Frontier orbital analysis and NEGF-DFT study

The conductance and electronic transport properties of a single-molecular diode with one backbone (1), and two backbones in parallel (2) have been investigated using frontier orbital analysis, and the NEGF formalism combined with DFT. The frontier orbital analysis results demonstrate that the electron transport from one end of the studied molecules to other end is symmetrically allowed and the conductance of the molecule with two parallel backbones is more than the molecule with a single backbone. Transmission spectra study based on the NEGF-DFT of the selected molecules sandwiched between two gold (1 1 1) electrodes showed that, due to a higher coupling between the two electrodes and the molecule 2, the zero-bias conductance is more than twice that of the other molecular junction. Transmission spectra under different biases showed that the maximum constructive interference exists at the bias voltage 0.2, while in some of the biases destructive effects are observed. I-V curves showed that the rectifying directions of molecular junctions 1 and 2 are opposite.