title: Measurement of molecular motion in organic semiconductors by thermal diffuse electron scattering.
abstract: Many of the remarkable electrical and optical properties of organic semiconductors are governed by the interaction of electronic excitations with intra- and intermolecular vibrational modes. However, in specific systems this interaction is not understood in detail at a molecular level and this has been due, at least in part, to the lack of easy-to-use and widely available experimental probes of the structural dynamics. Here we demonstrate that thermal diffuse scattering in electron diffraction patterns from organic semiconductors, such as 6,13-bistriisopropyl-silylethynyl pentacene, allows the dominant lattice vibrational modes to be probed directly. The amplitude and direction of the dominant molecular motions were determined by comparison of the diffuse scattering with simulations and molecular dynamics calculations. Our widely applicable approach enables a much deeper understanding of the structural dynamics in a broad range of organic semiconductors.
authors.affiliation: Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ, UK.
authors.forename: Alexander S
authors.initials: AS
authors.lastname: Eggeman
authors.forename: Steffen
authors.initials: S
authors.lastname: Illig
authors.forename: Alessandro
authors.initials: A
authors.lastname: Troisi
authors.forename: Henning
authors.initials: H
authors.lastname: Sirringhaus
authors.forename: Paul A
authors.initials: PA
authors.lastname: Midgley
references.citation: Acta Crystallogr B. 1995 Dec 1;51 ( Pt 6):1021-8
references.pmid: 8554724
references.citation: Ultramicroscopy. 2001 Feb;86(3-4):371-80
references.pmid: 11281157
references.citation: J Am Chem Soc. 2001 Sep 26;123(38):9482-3
references.pmid: 11562247
references.citation: Chem Rev. 2007 Apr;107(4):926-52
references.pmid: 17378615
references.citation: J Phys Chem A. 2006 Mar 23;110(11):4065-70
references.pmid: 16539430
references.citation: Adv Mater. 2012 Jan 24;24(4):503-8
references.pmid: 22213424
references.citation: Ultramicroscopy. 2010 Feb;110(3):195-8
references.pmid: 20022177
references.citation: Phys Rev Lett. 2011 Aug 5;107(6):066601
references.pmid: 21902350
references.citation: Adv Mater. 2010 Sep 8;22(34):3778-98
references.pmid: 20533415
references.citation: Phys Rev Lett. 2012 Jul 6;109(1):016601
references.pmid: 23031122