Solitonic waves in polyene dications and principles of charge carrier localization in pi-conjugated organic materials
Abbreviated Journal Title
Int. J. Quantum Chem.
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
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.
International Journal of Quantum Chemistry
"Solitonic waves in polyene dications and principles of charge carrier localization in pi-conjugated organic materials" (2012). Faculty Bibliography 2010s. 2668.