Electron correlation enhancement of the diode property of asymmetric molecules

Stimulated by recent experiments for diblock molecular junctions, we investigated a possible mechanism to explain the giant diode property by focusing on the electron correlation effect. Based on our observation that the first-principles generalized gradient approximation (GGA) fails to account for the large rectification behavior at high voltage, we have made nonequilibrium many-body calculations using the extended Hubbard model. Theoretical calculations including the electron correlation effect within the self-consistent GW approximation using Keldysh Green's functions give a large enhancement of the diode property over the mean-field result. We suggest that the many-body electron collision effect confined in one of the diblocks is necessary to explain the large rectification behavior found in experiments.