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CPP: Chemische Physik und Polymerphysik

CPP 16: Electronic Structure and Spectroscopy II

CPP 16.7: Vortrag

Mittwoch, 29. März 2006, 16:15–16:30, ZEU 160

Torsional Potentials for the Ground and Excited State of Bithiophene Calculated by Time-dependent Density Functional Theory — •Wichard J.D. Beenken¹, Sebastian Westenhoff², and Tõnu Pullerits³ — ¹Technische Universität Ilmenau, FG Theoretische Physik I, Postfach 100565, D-98684 Ilmenau — ²University of Cambridge, Optoelectronics Group, Cavendish Laboratory, CB3 0HE, UK — ³Lunds Universitet, Kemisk Fysik, Box 124, SE-22100 Lund

We have studied bithiophene by time-dependent density functional theory. In particular we have analyzed the dependence of singlet excitation energies and transition dipoles on the torsional angle between the two thiophenyl groups. The torsional spectrum has been computed quantum-mechanically as well as semi-classically in order to understand, how this influences the broadening of absorption and luminescence spectra. We discuss the general consequences for the spectral broadening, Stokes shift and energy relaxation in poly-thiophenes, in particular, how torsional disorder effects the absorption and photoluminescence spectra. Furthermore, such results are necessary input parameters for molecular dynamics. In particular for simulation of polythiophenes in the excited state reliable data are rare. We will show some exemplary simulations.