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 Green's 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.

► Experiment studies suggest the ability to adjust the length of the PTCDIs series. ► Transport properties of the PTCDIs molecular junctions are first investigated. ► The rectifying effect appears in all PTCDI-[CH2]n(1≤n≤6) molecular junctions. ► The significant rectification ratio of 72.6 is achieved in case of PTCDI-[CH2]6. ► The PTCDI-(CH2)n molecules show great utilities in the molecular electronics.