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