Regensburg 2004 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 23: Organische Halbleiter

HL 23.7: Vortrag

Dienstag, 9. März 2004, 18:15–18:30, H13

Ultrafast excitonic relaxation processes in perylene derivatives — •E. Engel, M. Koschorreck, M. Hoffmann, T. W. Canzler, T. Hasche, and K. Leo — Institut für Angewandte Photophysik, TU Dresden, 01062 Dresden, Germany, www.iapp.de

Perylene derivatives are interesting model systems because of their quasi-1D organic molecular crystal structure, their strong molecular interaction and their potential for use in low-cost optoelectronic devices. We investigated polycrystalline thin films of N-N’-dimethyl-perylene-3,4,9,10-dicarboximide (MePTCDI) and perylene-3,4,9,10-tetracarboxylic-dianhydride (PTCDA). Using ultrafast pump-probe spectroscopy, we temporally resolved the relaxation process of free excitons from the absorbing states down to the indirectly emitting states. The time constant, measured by photoinduced absorption, is about 30 fs. Furthermore, we investigated signal contributions from stimulated emission and ground state bleaching. The relaxation processes are discussed within the framework of an exciton band structure model [1].

[1] M. Hoffmann, Z. G. Soos and K. Leo, Nonlinear Optics 29, 227 (2002)