Effects of Heteroatom Substitutions on the Crystal Structure, Film Formation, and Optoelectronic Properties of Diketopyrrolopyrrole-Based Materials

Authors

  • Jianhua Liu,

    1. Center for Polymers and Organic Solids, Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA 93106, USA
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  • Bright Walker,

    1. Center for Polymers and Organic Solids, Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA 93106, USA
    Current affiliation:
    1. Interdisciplinary School of Green Energy, Ulsan National Institute of Science and Technology, Ulsan 689–798, Republic of Korea
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  • Arnold Tamayo,

    1. Center for Polymers and Organic Solids, Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA 93106, USA
    Current affiliation:
    1. Next Energy Technologies, 5385 Hollister Avenue, Santa Barbara, CA 93111, USA
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  • Yuan Zhang,

    1. Center for Polymers and Organic Solids, Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA 93106, USA
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  • Thuc-Quyen Nguyen

    Corresponding author
    1. Center for Polymers and Organic Solids, Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA 93106, USA
    • Center for Polymers and Organic Solids, Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA 93106, USA.
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Abstract

Substitution of the heteroatoms in the aromatic end-groups of three diketopyrrolopyrrole containing small molecules is investigated to evaluate how such substitutions affect various physical properties, charge transport, and the performance in bulk heterojunction solar cells. While the optical absorption and frontier orbital energy levels are insensitive to heteroatom substitution, the materials' solubility, thermal properties, film morphology, charge carrier mobility, and photovoltaic performance are altered significantly. Differences in material properties are found to arise from changes in intra- and intermolecular interactions in the solid state caused by heteroatom substitution, as revealed by the single crystal structures of three compounds. This study demonstrates a systematic investigation of structure–property relationships in conjugated small molecules.

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