Interface between FePc and Ni(111): Influence of Graphene Buffer Layers

The alteration of the electronic interface properties of iron phthalocyanine (FePc) on Ni(111) by graphene interlayers is studied using both photoemission techniques (XPS and UPS) and X-ray absorption spectroscopy (XAS). Both XPS and XAS clearly indicate a charge transfer from Ni(111) to the Fe ion of FePc. In contrast to CoPc, this charge transfer can be completely suppressed by the introduction of a graphene buffer layer between FePc and Ni(111). Further UPS measurements indicate that the interfacial charge transfer include also the FePc macrocycle. Surprisingly, for FePc and CoPc the energy level alignment after the formation of the interface dipoles is rather unaffected by both the introduction of a graphene buffer layer and charge transfer processes between the central metal atom of the Pc and the substrates.