title: Graphene nanoribbon heterojunctions.
abstract: Despite graphene's remarkable electronic properties, the lack of an electronic bandgap severely limits its potential for applications in digital electronics. In contrast to extended films, narrow strips of graphene (called graphene nanoribbons) are semiconductors through quantum confinement, with a bandgap that can be tuned as a function of the nanoribbon width and edge structure. Atomically precise graphene nanoribbons can be obtained via a bottom-up approach based on the surface-assisted assembly of molecular precursors. Here we report the fabrication of graphene nanoribbon heterojunctions and heterostructures by combining pristine hydrocarbon precursors with their nitrogen-substituted equivalents. Using scanning probe methods, we show that the resulting heterostructures consist of seamlessly assembled segments of pristine (undoped) graphene nanoribbons (p-GNRs) and deterministically nitrogen-doped graphene nanoribbons (N-GNRs), and behave similarly to traditional p-n junctions. With a band shift of 0.5 eV and an electric field of 2 × 10(8) V m(-1) at the heterojunction, these materials bear a high potential for applications in photovoltaics and electronics.
authors.affiliation: 1] Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland [2].
authors.forename: Jinming
authors.initials: J
authors.lastname: Cai
authors.affiliation: Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland.
authors.forename: Carlo A
authors.initials: CA
authors.lastname: Pignedoli
authors.affiliation: Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland.
authors.forename: Leopold
authors.identifier: 0000000215245903
authors.initials: L
authors.lastname: Talirz
authors.affiliation: Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland.
authors.forename: Pascal
authors.identifier: 0000000157295354
authors.initials: P
authors.lastname: Ruffieux
authors.affiliation: Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland.
authors.forename: Hajo
authors.initials: H
authors.lastname: Söde
authors.affiliation: Department of Physics, Rensselaer Polytechnic Institute, Troy, New York 12180, USA.
authors.forename: Liangbo
authors.identifier: 0000000311990049
authors.initials: L
authors.lastname: Liang
authors.affiliation: Department of Physics, Rensselaer Polytechnic Institute, Troy, New York 12180, USA.
authors.forename: Vincent
authors.initials: V
authors.lastname: Meunier
authors.affiliation: Max Planck Institute for Polymer Research, 55124 Mainz, Germany.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Berger
authors.affiliation: Max Planck Institute for Polymer Research, 55124 Mainz, Germany.
authors.forename: Rongjin
authors.initials: R
authors.lastname: Li
authors.affiliation: Max Planck Institute for Polymer Research, 55124 Mainz, Germany.
authors.forename: Xinliang
authors.initials: X
authors.lastname: Feng
authors.affiliation: Max Planck Institute for Polymer Research, 55124 Mainz, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Müllen
authors.affiliation: 1] Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland [2] Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland.
authors.forename: Roman
authors.initials: R
authors.lastname: Fasel