Regensburg 2007 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 1: Organic Thin Films I
DS 1.1: Vortrag
Montag, 26. März 2007, 09:30–09:45, H32
Anisotropic optical constants and exciton-phonon coupling of diindenoperylene thin films — •Ute Heinemeyer1, Stefan Kowarik1, Alexander Gerlach1, Reinhard Scholz2, M. Isabel Alonso3, Miquel Garriga3, J. Oriol Ossó3, and Frank Schreiber1 — 1Institut für Angewandte Physik, Universität Tübingen — 2Walter Schottky Institut, Technische Universität München — 3Institut de Ciència de Materials de Barcelona
Diindenoperylene (DIP) has received increased attention due to its well defined ordering and promising electronic transport properties [1,2]. We investigate the optical properties of DIP thin films on Si-substrates by spectroscopic ellipsometry. Since the molecules are highly ordered, the DIP films exhibit strong anisotropic optical properties with uniaxial symmetry so that it is necessary to perform variable angle ellipsometry. The data analysis of such anisotropic systems and the results in the energy range of 1.25 to 3 eV are presented. The aggregated molecules show a pronounced vibrational progression, allowing direct access to the exciton-phonon coupling. In addition a new mode appears that does not exist in the absorption spectra of free molecules in solution. It cannot be assigned to the vibronic progression and it is probably due to intermolecular coupling. Furthermore it is possible to take the spectra sufficiently fast to follow organic molecular beam deposition in detail. The analysis of the in-situ and real-time data taken at one fixed angle of incidence will be discussed. [1] S. Kowarik et al., PRL 96, 125504 (2006) [2] A. K. Tripathi and J. Pflaum, APL 89, 082103 (2006).