Thermal and mechanical cracking in bis(triisopropylsilylethnyl) pentacene thin films

Authors

  • Jihua Chen,

    1. Macromolecular Science and Engineering Center, University of Michigan, Ann Arbor, Michigan 48109
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  • Chee Keong Tee,

    1. Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109
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  • Junyan Yang,

    1. Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109
    Current affiliation:
    1. Dow Chemical Company, Freeport, Texas
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  • Charles Shaw,

    1. Macromolecular Science and Engineering Center, University of Michigan, Ann Arbor, Michigan 48109
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  • Max Shtein,

    1. Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109
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  • John Anthony,

    1. Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506
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  • David C. Martin

    Corresponding author
    1. Macromolecular Science and Engineering Center, University of Michigan, Ann Arbor, Michigan 48109
    2. Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109
    3. Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan 48109
    • Macromolecular Science and Engineering Center, University of Michigan, Ann Arbor, Michigan 48109
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Abstract

Bis(triisopropylsilylethnyl) pentacene (TIPS pentacene) was synthesized to increase its solubility in common liquid solvents and, at the same time, enhance the π–π stacking between neighboring acenes in the crystallized state in comparison with unmodified pentacene. Hot-stage microscopy experiments revealed that during heating voids develop along the long axis of the TIPS pentacene films {along the [210] direction/parallel to the (120) planes} and crystals overlap along the short axis {along the [120] direction/parallel to the (210) planes}. From molecular mechanics simulations, the predominant twin boundaries of (120) and commonly observed cracking planes of (120), (120), and (210) had relatively low surface energies in comparison with planes with similar Miller indices. Organic thin-film transistors with TIPS pentacene as the active layer were fabricated, and the mobility values decreased from 0.4–1.0 cm2/V s before cracking to ∼0.2 cm2/V s after cracking. To maintain the high charge carrier mobility of TIPS pentacene devices, these cracks should be avoided. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3631–3641, 2006

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