title: Strain effects on the work function of an organic semiconductor.
abstract: Establishing fundamental relationships between strain and work function (WF) in organic semiconductors is important not only for understanding electrical properties of organic thin films, which are subject to both intrinsic and extrinsic strains, but also for developing flexible electronic devices. Here we investigate tensile and compressive strain effects on the WF of rubrene single crystals. Mechanical strain induced by thermal expansion mismatch between the substrate and rubrene is quantified by X-ray diffraction. The corresponding WF change is measured by scanning Kelvin probe microscopy. The WF of rubrene increases (decreases) significantly with in-plane tensile (compressive) strain, which agrees qualitatively with density functional theory calculations. An elastic-to-plastic transition, characterized by a steep rise of the WF, occurs at ∼0.05% tensile strain along the rubrene π-stacking direction. The results provide the first concrete link between mechanical strain and WF of an organic semiconductor and have important implications for understanding the connection between structural and electronic disorder in soft organic electronic materials.
authors.affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Ave SE, Minneapolis, 55455 Minnesota, USA.
authors.forename: Yanfei
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Department of Materials Science and Engineering, Stanford University, 476 Lomita Mall, Stanford, 94305 California, USA.
authors.forename: Annabel R
authors.initials: AR
authors.lastname: Chew
authors.affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Ave SE, Minneapolis, 55455 Minnesota, USA.
authors.forename: Geoffrey A
authors.initials: GA
authors.lastname: Rojas
authors.affiliation: Laboratoire de Physico-chimie des Polymères et des Interfaces, Université de Cergy-Pontoise, 5 Mail Gay Lussac, Neuville sur Oise, Cergy-Pontoise Cedex 95031, France.|Physical Science and Engineering Division, Solar &Photovoltaics Engineering Research Center, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.
authors.forename: Gjergji
authors.initials: G
authors.lastname: Sini
authors.affiliation: Characterization Facility, University of Minnesota, 100 Union St SE, Minneapolis, 55455 Minnesota, USA.
authors.forename: Greg
authors.initials: G
authors.lastname: Haugstad
authors.affiliation: Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, 1 Bethel Valley Rd., Oak Ridge, 37831 Tennessee, USA.
authors.forename: Alex
authors.initials: A
authors.lastname: Belianinov
authors.affiliation: Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, 1 Bethel Valley Rd., Oak Ridge, 37831 Tennessee, USA.
authors.forename: Sergei V
authors.initials: SV
authors.lastname: Kalinin
authors.affiliation: School of Chemistry and Biochemistry &Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, 30332 Georgia, USA.
authors.forename: Hong
authors.initials: H
authors.lastname: Li
authors.affiliation: Department of Chemistry &Center for Applied Energy Research, University of Kentucky, Lexington, 40506 Kentucky, USA.
authors.forename: Chad
authors.initials: C
authors.lastname: Risko
authors.affiliation: Physical Science and Engineering Division, Solar &Photovoltaics Engineering Research Center, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Brédas
authors.affiliation: Department of Materials Science and Engineering, Stanford University, 476 Lomita Mall, Stanford, 94305 California, USA.
authors.forename: Alberto
authors.initials: A
authors.lastname: Salleo
authors.affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Ave SE, Minneapolis, 55455 Minnesota, USA.
authors.forename: C Daniel
authors.initials: CD
authors.lastname: Frisbie
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