Insight into negative differential resistance in polyphenylene molecular device with graphene electrodes

The organic molecule deposited between gaphene electrodes to form a molecular device has been demonstrated experimentally. Motivated by this case, devices consisting of the polyphenylene molecule bonded covalently with armchair-edged graphene nanoribbon (AGNR) electrodes are constructed and the selective doping with N atom is considered theoretically. Our modeling calculations show that such devices hold the nonlinear and doping-site-dependent transport properties, prominently with multi-peak NDR (negative differential resistance) effect. And, for a peculiar doping site, a very large NDR can be observed, which could be attributed to interactions of the molecular core and doped AGNR electrodes, namely, these hybridized wave functions hold distinctly different delocalization in different benzene rings of the polyphenylene molecule when the applied bias is altered. Also shown is that this large NDR is robust regarding the length increasing and rotation of molecule.