Molecular rectification of thiol-linked Au|PTCDI-[CH2]n|Au junctions

The electronic transport properties of the PTCDI-[CH2]n(0≤n≤6) molecular junctions with different molecular lengths are theoretically investigated via the first-principles density functional theory (DFT) and non-equilibrium Greenʹs function (NEGF) method. Our results show that the transport properties depend on molecular lengths. The equilibrium conductance of the probed systems decreases exponentially with the increasing number n of the CH2 unit. With n≥1, the rectifying effect has been found. In the n=6 case, a significant rectification ratio of 72.6 is achieved at the bias of ±2.1 V in our probed voltage range. The rectification effect arises from asymmetric molecular structures. Our results suggest these molecules have great potential application in the molecular-scale device.