▎ 摘　　要

We demonstrate that the tunable molecule-substrate interaction offers possibility to realize a single cobalt phthalocyanine (CoPc) molecule rectifier. CoPc molecule shows a prominent rectifying effect at about -0.30eV when a monolayer graphene (MG) is intercalated between CoPc and Ru(0001) substrate. First-principles calculations show that CoPc molecule couples with MG/Ru(0001) substrate mainly through the d(z2) orbital of Co atom. The tunneling between CoPc molecule and MG/Ru(0001) substrate is mainly intermediated by the Co-d(z2) orbital locating at -0.35 eV. The resonant tunneling through this single orbital gives rise to the abrupt current enhancement and hence the rectifying effect. (C) 2013 AIP Publishing LLC [http://dx.doi.org/10.1063/1.4803443]