Enhancement of rectification by quantum interference in co-oligomer molecular diodes

We investigate the rectification property theoretically in co-oligomer diodes integrating a destructive quantum interference (DQI) feature. The results demonstrate that by comparing with a similar co-oligomer diode without DQI, the rectification ratio is enhanced by one order of magnitude in the presence of the DQI feature. Mechanism analysis indicates that the high rectification ratio benefits from the strong suppression of transmission in the off-state of the diode by the DQI dip. The strong rectification is attributed to the distinctly asymmetric shift of the DQI dip under bias voltages, which comes out as a result of both bias-induced shift of eigenvalues and redistribution of wave functions of all orbitals. The effect of energy level alignment between the two segments of the co-oligomer on the rectification is also discussed. This work provides a valid way to enhance the performance of intrinsic co-oligomer diodes, which is promising to be designed in a molecular circuit.