Phonons and anisotropic mobility in a single crystal organic semiconductor

ORAL

Abstract

Intermolecular phonons are theorized to cause transient localization of charge carriers which is a proposed limiting factor in achieving band-like mobilities in organic semiconductors. In this study we probe the molecular motions associated with phonons in single crystal tetracene within the high-mobility plane correlate with the anisotropy of the field-effect mobility. Phonons measured at low energy (< 25 meV) have associated molecule and lattice distortions that are directionally oriented within the crystal. Calculated changes to the HOMO level show a disruption of orbital overlap between molecules along the high mobility direction for one large amplitude phonon. The measured anisotropic high-to-low mobility ratio in the ab-plane of single crystal tetracene is lower than published static calculations of anisotropy suggesting that transient localization has directionality.

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Presenters

  • Emily Geraldine Bittle

    Nanoscale Device Characterization Division, National Institute of Standards and Technology, National Institute of Standards and Technology

Authors

  • Emily Geraldine Bittle

    Nanoscale Device Characterization Division, National Institute of Standards and Technology, National Institute of Standards and Technology

  • Adam Biacchi

    Nanoscale Device Characterization Division, National Institute of Standards and Technology, National Institute of Standards and Technology

  • Lisa A. Fredin

    Chemical Sciences Division, National Institute of Standards and Technology, Department of Chemistry, Lehigh University

  • Andrew Herzing

    Materials Measurement Science Division, National Institute of Standards and Technology, Materials Measurement Division, National Institute of Standards and Technology, National Institute of Standards and Technology

  • Thomas C. Allison

    Chemical Sciences Division, National Institute of Standards and Technology, National Institute of Standards and Technology

  • Angela Hight Walker

    NIST, Nanoscale Device Characterization Division, National Institute of Standards and Technology, National Institute of Standards and Technology, Nanoscale Device Characterization Division, Physical Measurement Laboratory, National Institute of Standards and Technology, Nanoscale Spectroscopy Group, National Institute of Standards and Technology, Engineering Physics Division, National Institute of Standards and Technology

  • David James Gundlach

    Nanoscale Device Characterization Division, National Institute of Standards and Technology, National Institute of Standards and Technology