A combination of ultraviolet and X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, and first principle calculations was used to study the electronic structure at the interface between the strong molecular acceptor 1,3,4,5,7,8-hexafluorotetracyano-naphthoquinodimethane (F6TCNNQ) and a graphene layer supported on either a quartz or a copper substrate. We find evidence for fundamentally different charge redistribution mechanisms in the two ternary systems, as a consequence of the insulating versus metallic character of the substrates. While electron transfer occurs exclusively from graphene to F6TCNNQ on the quartz support (p-doping of graphene), the Cu substrate electron reservoir induces an additional electron density flow to graphene decorated with the acceptor monolayer. Remarkably, graphene on Cu is n-doped and remains n-doped upon F6TCNNQ deposition. On both substrates, the work function of graphene increases substantially with a F6TCNNQ monolayer atop, the effect being more pronounced (∼1.3 eV) on Cu compared to quartz (∼1.0 eV) because of the larger electrostatic potential drop associated with the long-distance graphene-mediated Cu-F6TCNNQ electron transfer. We thus provide a means to realize high work function surfaces for both p- and n-type doped graphene.

Tuning the Electronic Structure of Graphene by Molecular Dopants: Impact of the Substrate / Christodoulou, Christos; Giannakopoulos, Angelos; Ligorio, Giovanni; Oehzelt, Martin; Timpel, Melanie; Niederhausen, Jens; Pasquali, Luca; Giglia, Angelo; Parvez, Khaled; Müllen, Klaus; Beljonne, David; Koch, Norbert; Nardi, Marco V.. - In: ACS APPLIED MATERIALS & INTERFACES. - ISSN 1944-8244. - STAMPA. - 7:34(2015), pp. 19134-19144. [10.1021/acsami.5b04777]

Tuning the Electronic Structure of Graphene by Molecular Dopants: Impact of the Substrate

PASQUALI, Luca;
2015

Abstract

A combination of ultraviolet and X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, and first principle calculations was used to study the electronic structure at the interface between the strong molecular acceptor 1,3,4,5,7,8-hexafluorotetracyano-naphthoquinodimethane (F6TCNNQ) and a graphene layer supported on either a quartz or a copper substrate. We find evidence for fundamentally different charge redistribution mechanisms in the two ternary systems, as a consequence of the insulating versus metallic character of the substrates. While electron transfer occurs exclusively from graphene to F6TCNNQ on the quartz support (p-doping of graphene), the Cu substrate electron reservoir induces an additional electron density flow to graphene decorated with the acceptor monolayer. Remarkably, graphene on Cu is n-doped and remains n-doped upon F6TCNNQ deposition. On both substrates, the work function of graphene increases substantially with a F6TCNNQ monolayer atop, the effect being more pronounced (∼1.3 eV) on Cu compared to quartz (∼1.0 eV) because of the larger electrostatic potential drop associated with the long-distance graphene-mediated Cu-F6TCNNQ electron transfer. We thus provide a means to realize high work function surfaces for both p- and n-type doped graphene.
2015
24-ago-2015
7
34
19134
19144
Tuning the Electronic Structure of Graphene by Molecular Dopants: Impact of the Substrate / Christodoulou, Christos; Giannakopoulos, Angelos; Ligorio, Giovanni; Oehzelt, Martin; Timpel, Melanie; Niederhausen, Jens; Pasquali, Luca; Giglia, Angelo; Parvez, Khaled; Müllen, Klaus; Beljonne, David; Koch, Norbert; Nardi, Marco V.. - In: ACS APPLIED MATERIALS & INTERFACES. - ISSN 1944-8244. - STAMPA. - 7:34(2015), pp. 19134-19144. [10.1021/acsami.5b04777]
Christodoulou, Christos; Giannakopoulos, Angelos; Ligorio, Giovanni; Oehzelt, Martin; Timpel, Melanie; Niederhausen, Jens; Pasquali, Luca; Giglia, Ang...espandi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11380/1072465
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