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On the formation mechanism for electrically generated exciplexes in a carbazole–pyridine copolymer

Authors

  • Anna Hayer,

    1. Experimental Physics II and Bayreuth Institute for Macromolecular Research (BIMF), University of Bayreuth, Universitätsstr. 30, 95448 Bayreuth, Germany
    2. Cavendish Laboratory, University of Cambridge, JJ Thompson Avenue, Cambridge CB3 OHE, United Kingdom
    Current affiliation:
    1. Merck KgaA, Darmstadt, Germany
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  • Tanguy Van Regemorter,

    1. Laboratory for Chemistry of Novel Materials, University of Mons, Place du Parc 20, B-7000 Mons, Belgium
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  • Bianca Höfer,

    1. Experimental Physics II and Bayreuth Institute for Macromolecular Research (BIMF), University of Bayreuth, Universitätsstr. 30, 95448 Bayreuth, Germany
    Current affiliation:
    1. IFW-Dresden, Dresden, Germany
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  • Chris S. K. Mak,

    1. Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
    Current affiliation:
    1. Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, China
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  • David Beljonne,

    1. Laboratory for Chemistry of Novel Materials, University of Mons, Place du Parc 20, B-7000 Mons, Belgium
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  • Anna Köhler

    Corresponding author
    1. Experimental Physics II and Bayreuth Institute for Macromolecular Research (BIMF), University of Bayreuth, Universitätsstr. 30, 95448 Bayreuth, Germany
    • Experimental Physics II and Bayreuth Institute for Macromolecular Research (BIMF), University of Bayreuth, Universitätsstr. 30, 95448 Bayreuth, Germany
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Abstract

Although carbazole-containing copolymers are frequently used as hole-transporting host materials for polymer organic light-emitting diodes (OLEDs), they often suffer from the formation of undesired exciplexes when the OLED is operated. The reason why exciplexes sometimes form for electrical excitation, yet not for optical excitation is not well understood. Here, we use luminescence measurements and quantum chemical calculations to investigate the mechanism of such exciplex formation for electrical excitation (electroplex formation) in a carbazole–pyridine copolymer. Our results suggest that the exciplex is formed via a positively charged interchain precursor complex. This complex is stabilized by interactions that involve the nitrogen lone pairs on both chain segments. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012

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