Title

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

Authors

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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