Effect of trans- and cis-isomeric defects on the localization of the charged excitations in -conjugated organic polymers

    Authors

    I. H. Nayyar; E. R. Batista; S. Tretiak; A. Saxena; D. L. Smith;R. L. Martin

    Comments

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    Abbreviated Journal Title

    J. Polym. Sci. Pt. B-Polym. Phys.

    Keywords

    conducting polymers; conjugated polymers; quantum chemistry; theory; UV-vis spectroscopy; SOLAR-CELLS; POLY(P-PHENYLENE VINYLENE); ENERGY-TRANSFER; CN-PPV; STATES; SEMICONDUCTORS; TRANSISTORS; EXCITONS; CHANNEL; DEVICES; Polymer Science

    Abstract

    We use the long-range-corrected hybrid density functional theory models to study the effect of various conformational distortions of weak-trans and strong-cis nature on the spatial localization of charged states in poly(p-phenylene vinylene) (PPV) and its derivative poly[2-methoxy-5-(2-ethylhexyloxy)-p-phenylene vinylene] (MEH-PPV). The extent of self-trapping of positive (P+) and negative (P) polarons is observed to be highly sensitive to molecular conformation that, in turn, controls the distribution of atomic charges within the polymers. It is shown that, to reach good agreement with recent experimental data on lattice distortion for P+ and P excitations, the polarization of the medium plays a critical role. The introduction of weak-trans defects along the MEH-PPV chain breaks the observed symmetry for P+ and P excitations. The P states exhibit more spatial localization owing to lattice relaxation than their vacuum counterparts in contrast to P+. These observations suggest higher mobilities of holes than that of electrons in MEH-PPV, in agreement with the experimental observations. The predicted binding, reorganization, and solvation energies for PPV and MEH-PPV are analyzed for this difference in the response behavior of holes and electrons for trans and cis distortions. This study allows for a better understanding of charge-transport and photophysical properties in -conjugated organic materials by analyzing their underlying structureproperty correlations. (c) 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 935942

    Journal Title

    Journal of Polymer Science Part B-Polymer Physics

    Volume

    51

    Issue/Number

    12

    Publication Date

    1-1-2013

    Document Type

    Article

    Language

    English

    First Page

    935

    Last Page

    942

    WOS Identifier

    WOS:000318773700002

    ISSN

    0887-6266

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