Regensburg 2004 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 12: Poster I
HL 12.97: Poster
Montag, 8. März 2004, 16:30–19:00, Poster A
Exciton transport in PTCDA layers studied by time-resolved, temperature dependent luminescence quenching experiments. — •R. Schüppel, K. Leo, and M. Hoffmann — Institut für Angewandte Photophysik, TU Dresden, 01062 Dresden, Germany
For opto-electronic applications of organic semiconductors, the properties of the photo-excited states (excitons) have to be understood in detail. In particular, the transport properties of excitons, which are described in terms of diffusion, are significant for the optimization process of devices, e.g. solar cells. We performed luminescence quenching experiments with thin vapor-deposited films of PTCDA (perylene-3,4:9,10-tetracarboxylic-dianhydride), which are partially covered by a quenching layer, in our case TiOPc (titanyl-phthalocyanine). From the time-resolved PTCDA luminescence, we can distinguish between primarily excited states (lifetime τa<10ps) and long-living emitting states (τe>1ns). The transport, which is accessible from the luminescence quenching by a variation of the layer thickness, shows no temperature dependence for the short-living states. The transport in the emitting states is thermally activated for high temperatures (T>60K), which suggests incoherent hopping transport. For low temperatures, we observe no temperature dependence, which can be explained by several transport mechanisms.