title: Graphene-enhanced intermolecular interaction at interface between copper- and cobalt-phthalocyanines.
abstract: Interfacial electronic structures of copper-phthalocyanine (CuPc), cobalt-phthalocyanine (CoPc), and graphene were investigated experimentally by using photoelectron spectroscopy. While the CuPc/graphene interface shows flat band structure and negligible interfacial dipole indicating quite weak molecule-substrate interaction, the CuPc/CoPc/graphene interface shows a large interfacial dipole and obvious energy level bending. Controlled experiments ruled out possible influences from the change in film structure of CuPc and pure π-π interaction between CoPc and CuPc. Analysis based on X-ray photoelectron spectroscopy and density functional theory reveals that the decrease in the work function for the CuPc/CoPc/graphene system is induced by the intermolecular interaction between CuPc and CoPc which is enhanced owning to the peculiar electronic properties at the CoPc-graphene interface.
authors.affiliation: Department of Physics, Shaoxing University, Shaoxing 312000, China.
authors.forename: Wei-Dong
authors.initials: WD
authors.lastname: Dou
authors.affiliation: Department of Chemistry, University of South Dakota, Vermillion, South Dakota 57069, USA.
authors.forename: Shu-Ping
authors.initials: SP
authors.lastname: Huang
authors.affiliation: Center of Super-Diamond and Advanced Films (COSDAF) and Department of Physics and Material Science, City University of Hong Kong, Hong Kong, China.
authors.forename: Chun-Sing
authors.initials: CS
authors.lastname: Lee