An investigation of electronic structure and charge transport in fluoroarene-modified oligothiophene semiconductors

ORGN 100

Sharon E. Koh, s-koh@northwestern.edu1, Julia Medvedeva2, Antonio Facchetti3, Bernard Delley4, Arthur J. Freeman, art@freeman.phys.northwestern.edu5, Tobin J. Marks, t-marks@northwestern.edu1, and Mark Ratner, ratner@northwestern.edu1. (1) Department of Chemistry, Northwestern University, 2145 Sheridan Rd., Evanston, IL 60208, (2) Department of Physics, University of Missouri-Rolla, Rolla, MO 65409, (3) Department of Chemistry and the Materials Research Center, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-3113, (4) Paul Scherrer Institute, WHGA 123, CH-5232 Villigen PSI, Switzerland, (5) Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Rd, Evanston, IL 60208
Density-functional theory (DFT) is employed to investigate structural, electronic, and solid state transport properties of several isomeric fluoroarene-oligothiophene-based semiconductors. Analyses of both intermolecular interactions in dimers and extended interactions in experimentally obtained crystalline structures offer significant insight into the carrier mobilities of these materials as well as the polarity of the charge carriers as measured by organic field effect transistors (OFETs). From calculated carrier effective masses in band structure analyses, we find that sterically-governed molecular planarity plays a crucial role in the transport properties of these semiconductors. The calculations correlate well with experimentally obtained geometries, highest occupied molecular orbital (HOMO)/lowest unoccupied molecular orbital (LUMO) energies, and observed carrier mobility trends among the systems investigated.
 

Materials, Devices, and Switches
1:00 PM-5:00 PM, Sunday, 10 September 2006 Moscone Center -- Room 132, Oral

Division of Organic Chemistry

The 232nd ACS National Meeting, San Francisco, CA, September 10-14, 2006