title: Two-Dimensional Excitonic Photoluminescence in Graphene on a Cu Surface.
abstract: Despite having outstanding electrical properties, graphene is unsuitable for optical devices because of its zero band gap. Here, we report two-dimensional excitonic photoluminescence (PL) from graphene grown on a Cu(111) surface, which shows an unexpected and remarkably sharp strong emission near 3.16 eV (full width at half-maximum ≤3 meV) and multiple emissions around 3.18 eV. As temperature increases, these emissions blue shift, displaying the characteristic negative thermal coefficient of graphene. The observed PL originates from the significantly suppressed dispersion of excited electrons in graphene caused by hybridization of graphene π and Cu d orbitals of the first and second Cu layers at a shifted saddle point 0.525(M+K) of the Brillouin zone. This finding provides a pathway to engineering optoelectronic graphene devices, while maintaining the outstanding electrical properties of graphene.
authors.affiliation: Center for Superfunctional Materials, Department of Chemistry and Department of Physics, Ulsan National Institute of Science and Technology (UNIST) , Ulsan 44919, Korea.
authors.forename: Youngsin
authors.initials: Y
authors.lastname: Park
authors.affiliation: Department of Physics, Sungkyunkwan University , Suwon 16418, Korea.
authors.forename: Yooseok
authors.initials: Y
authors.lastname: Kim
authors.affiliation: Center for Superfunctional Materials, Department of Chemistry and Department of Physics, Ulsan National Institute of Science and Technology (UNIST) , Ulsan 44919, Korea.
authors.forename: Chang Woo
authors.initials: CW
authors.lastname: Myung
authors.affiliation: Clarendon Laboratory, Department of Physics, University of Oxford , Parks Road, Oxford OX1 3PU, U.K.
authors.forename: Robert Anthony
authors.identifier: 0000-0003-2578-9645
authors.initials: RA
authors.lastname: Taylor
authors.affiliation: Clarendon Laboratory, Department of Physics, University of Oxford , Parks Road, Oxford OX1 3PU, U.K.
authors.forename: Christopher C S
authors.initials: CC
authors.lastname: Chan
authors.affiliation: Clarendon Laboratory, Department of Physics, University of Oxford , Parks Road, Oxford OX1 3PU, U.K.
authors.forename: Benjamin P L
authors.initials: BP
authors.lastname: Reid
authors.affiliation: Clarendon Laboratory, Department of Physics, University of Oxford , Parks Road, Oxford OX1 3PU, U.K.
authors.forename: Tim J
authors.identifier: 0000-0002-3215-2960
authors.initials: TJ
authors.lastname: Puchtler
authors.affiliation: Clarendon Laboratory, Department of Physics, University of Oxford , Parks Road, Oxford OX1 3PU, U.K.
authors.forename: Robin J
authors.initials: RJ
authors.lastname: Nicholas
authors.affiliation: Center for Superfunctional Materials, Department of Chemistry and Department of Physics, Ulsan National Institute of Science and Technology (UNIST) , Ulsan 44919, Korea.
authors.forename: Laishram Tomba
authors.initials: LT
authors.lastname: Singh
authors.affiliation: Center for Superfunctional Materials, Department of Chemistry and Department of Physics, Ulsan National Institute of Science and Technology (UNIST) , Ulsan 44919, Korea.
authors.forename: Geunsik
authors.initials: G
authors.lastname: Lee
authors.affiliation: Beamline Division, Pohang Accelerator Laboratory , Pohang 37673, Korea.
authors.forename: Chan-Cuk
authors.initials: CC
authors.lastname: Hwang
authors.affiliation: Department of Physics, Sungkyunkwan University , Suwon 16418, Korea.
authors.forename: Chong-Yun
authors.initials: CY
authors.lastname: Park
authors.affiliation: Center for Superfunctional Materials, Department of Chemistry and Department of Physics, Ulsan National Institute of Science and Technology (UNIST) , Ulsan 44919, Korea.
authors.forename: Kwang S
authors.identifier: 0000-0002-6929-5359
authors.initials: KS
authors.lastname: Kim
keywords: Cu surface; exciton; graphene; optoelectronics; photoluminescence