Wednesday, 16 May 2007 - 2:00 PM
209 (Pfahler Hall)
100

Amorphous Solids of Sterically Unencumbered, Low Molecular Weight Ethyne-Bridged (Porphinato)zinc(II) Oligomers with Extremely High Dark Electrical Conductivitie

Paul R. Frail1, Kimihiro Susumu2, Michael Huynh1, Jennie Fong3, Paul Angiolillo4, Jay M. Kikkawa1, and Michael J. Therien1. (1) University of Pennsylvania, Philadelphia, PA, (2) US Naval Research Laboratory, Washington, DC, (3) Massachusetts Institute of Technology, Cambridge, MA, (4) Saint Joseph's University, Philadelphia, PA

Semi-conducting organic p-conjugated oligomers and polymers manifest demonstrated utility in device applications ranging from light-emitting diodes, photovoltaic cells, and optical waveguides, to inexpensive light-weight flexible transistors. High-value electronic device components based on processable polymers require the development of organic semiconductors that not only possess considerably larger magnitude charge mobilities, but have the capacity to be both hole and electron doped. We demonstrate that the radical cation states highly soluble oligomeric ethyne-bridged (porphinato)zinc(II) structures manifest polaron delocalization lengths approximately 4 times longer than that thus far observed in the classic semi-conducting polymers based on conjugated thiophenes, arylenes, arylethynylenes, pyrroles, and anilines; impressively, EPR spectroscopy shows unequivocally that large magnitude hole polaron mobilities are maintained in these species even at cryogenic temperatures. Appropriate modification of macrocycle ancillary substituents gives rise to oligomers and polymers that feature substantial inter-chain electronic coupling. Amorphous, solid-state dark conductivities of these materials rival that of porous silicon. Corresponding conductivities of hole- and electron-doped samples, resistivities, charge carrier densities (from Hall Effect measurements), and photogenerated drift mobilities further underscore the revolutionary electronic properties of this new class of organic semiconductors.

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