Regensburg 2002 – scientific programme

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SYOH: Organische Halbleiter

SYOH 7: Poster

SYOH 7.20: Poster

Monday, March 11, 2002, 18:00–21:00, C

Absorption spectra of PTCDA derivatives in the framework of Holstein models — •Michael Hoffmann and Zoltan G. Soos — Department of Chemistry, Princeton University, Princeton, NJ 08544

We present a numerical scheme for the direct diagonalization of the Holstein Hamiltonian and discuss the optical absorption spectrum and the internal structure of the band-edge excited states of the infinite chain. In addition to the original Holstein model with one electronic state, we include charge-transfer states with linear vibrational coupling on adjacent molecules. By comparison with experimental spectra we determine the exciton hopping and charge-transfer integrals for PTCDA (3,4,9,10-perylenetetracarboxylicdianhydride) and MePTCDI (N-N^′-dimethylperylene-3,4,9,10-dicarboximide). We discuss the structure of the delocalized phonon clouds and the applicability of approximations.