title: Electronic interaction between nitrogen-doped graphene and porphyrin molecules.
abstract: The chemical doping of graphene is a promising route to improve the performances of graphene-based devices through enhanced chemical reactivity, catalytic activity, or transport characteristics. Understanding the interaction of molecules with doped graphene at the atomic scale is therefore a leading challenge to be overcome for the development of graphene-based electronics and sensors. Here, we use scanning tunneling microscopy and spectroscopy to study the electronic interaction of pristine and nitrogen-doped graphene with self-assembled tetraphenylporphyrin molecules. We provide an extensive measurement of the electronic structure of single porphyrins on Au(111), thus revealing an electronic decoupling effect of the porphyrins adsorbed on graphene. A tip-induced switching of the inner hydrogen atoms of porphyrins, first identified on Au(111), is observed on graphene, allowing the identification of the molecular conformation of porphyrins in the self-assembled molecular layer. On nitrogen-doped graphene, a local modification of the charge transfer around the nitrogen sites is evidenced via a downshift of the energies of the molecular elecronic states. These data show how the presence of nitrogen atoms in the graphene network modifies the electronic interaction of organic molecules with graphene. These results provide a basic understanding for the exploitation of doped graphene in molecular sensors or nanoelectronics.
authors.affiliation: Laboratoire Matériaux et Phénomènes Quantiques, CNRS-Université Paris 7 , 10 Rue Alice Domon et Léonie Duquet, 75205 Paris Cedex 13, France.
authors.forename: Van Dong
authors.initials: VD
authors.lastname: Pham
authors.forename: Jérôme
authors.initials: J
authors.lastname: Lagoute
authors.forename: Ouafi
authors.initials: O
authors.lastname: Mouhoub
authors.forename: Frédéric
authors.initials: F
authors.lastname: Joucken
authors.forename: Vincent
authors.initials: V
authors.lastname: Repain
authors.forename: Cyril
authors.initials: C
authors.lastname: Chacon
authors.forename: Amandine
authors.initials: A
authors.lastname: Bellec
authors.forename: Yann
authors.initials: Y
authors.lastname: Girard
authors.forename: Sylvie
authors.initials: S
authors.lastname: Rousset
keywords: charge transfer; graphene; nitrogen doping; scanning tunneling microscopy; scanning tunneling spectroscopy; self-assembly; tetraphenylporphyrins