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Research Abstracts Online
January 2010 - March 2011

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University of Minnesota Twin Cities
College of Science and Engineering
Department of Chemical Engineering and Materials Science

PI: C. Daniel Frisbie

Tuning the Charge Transport Properties of Organic Semiconductors

As electron and hole charge carriers in organic semiconductors generally exist as polaron-like quasi-particles, understanding the instantaneous nature of both intra- and intermolecular electronic polarization is key to developing a robust description of charge transport. These researchers have recently shown that a mixed quantum-mechanics/molecular-mechanics (QM/MM) approach can provide such detailed insight into the influence of solid-state polarization effects on the charge-transport properties. They are significantly expanding their QM/MM approach and applying it to the study of pentacene versus perfluoropentacene—two molecules that have permanent quadrupole moments oriented in opposite directions, which should greatly affect the electrostatic environment of the charge carrier and, hence, the polarization energy—and TIPS-substituted acenes. In addition, the organic-electrode/dielectric interface will be investigated for molecular crystals to examine how these interfaces affect the molecular charge distribution at the interface and, ultimately, the surface potential. Of particular importance will be to examine how the molecular orientation with respect to the substrate might influence this charge redistribution. This information will provide valuable insight that may be used for future molecular design.

Group Member

Chad Risko, School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia