Solitonic waves in polyene dications and principles of charge carrier localization in pi-conjugated organic materials

    Authors

    A. O. Gerasov; I. H. Nayyar; A. E. Masunov; O. V. Przhonska; O. D. Kachkovsky; D. O. Melnyk; O. B. Ryabitsky;O. O. Viniychuk

    Comments

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    Abbreviated Journal Title

    Int. J. Quantum Chem.

    Keywords

    linear conjugated systems; polyene dications; neutral polyenes; polymethine dyes; solitonic wave; wave of charge; wave of bond length; alternation; molecular wires; organic photovoltaics; charge carrier; organic semiconductors; NEGATIVE-DEFECT TRANSPOLYACETYLENE; BROOKER POLYMETHINECYANINE CATIONS; SYMMETRY-BREAKING; ELECTRONIC-PROPERTIES; POLYACETYLENE CHAINS; CONDUCTING POLYMERS; FINITE-LENGTH; SYSTEMS; POLARONS; DYES; Chemistry, Physical; Mathematics, Interdisciplinary Applications; Physics, Atomic, Molecular & Chemical

    Abstract

    The quantum-chemical investigations by ab initio method (restricted HartreeFock/6-31G**) have been performed for a series of unsubstituted, monosubstituted, and disubstituted neutral polyenes and their double charged cations. The waves of charge alternation (characterized by the difference in the electron densities at the nearest carbon atoms or ?q function) and bond length alternation (characterized by the lengths difference of the nearest carboncarbon bonds or ?l function) are reported. Comparisons are made with the corresponding monocationic polymethine molecules. We found that ionization by two electrons results in formation of two solitonic waves of charge alternation, rather than superposition of two overlapping solitonic waves into one. These waves behave similar to two independent elastic particles, which do not penetrate into each other despite the special confinement by the length of chromophore p-system. In monosubstituted polyene dication, ?q and ?l functions contain two waves each; however, only one wave is mobile and sensitive to a change of the chemical nature of the terminal group, whereas the second wave remains practically unchanged. The introduction of one oxymethyl or phenyl terminal groups leads to a relatively small shift of the mobile wave from the center to a direction of the terminal group. The effect of the amino or tropilium terminal groups is much more pronounced and leads to a shift of the mobile wave to the end of the molecule. In disubstituted polyene dication, both solitonic waves become mobile and shift symmetrically to both ends. The general principles of the charge localization described in this study may be used in molecular design and fine-tuning of the charge transport properties in plastic photovoltaics and other organic semiconducting materials. (C) 2012 Wiley Periodicals, Inc.

    Journal Title

    International Journal of Quantum Chemistry

    Volume

    112

    Issue/Number

    14

    Publication Date

    1-1-2012

    Document Type

    Article

    Language

    English

    First Page

    2659

    Last Page

    2667

    WOS Identifier

    WOS:000305511800008

    ISSN

    0020-7608

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