Hamburg 2001 – scientific programme

Parts | Days | Selection | Search | Downloads | Help

SYOF: Organische Festkörper

SYOF 5: Poster Session

SYOF 5.13: Poster

Tuesday, March 27, 2001, 17:00–19:00, Aula S3

Space-charge limited conduction in organic light-emitting diodes: the role of charge carrier mobility and trap states — •Wolfgang Brütting, Stefan Berleb, and Anton G. Mückl — Experimental Physics II, University of Bayreuth, 95440 Bayreuth

The identification of the current-limiting mechanism in organic light-emitting diodes based on tris(8-hydroxyquinolato)aluminium (Alq) has been the subject of controversial discussions. We demonstrate that especially the thickness dependence of the current provides a unique criterion to discriminate between (a) injection-limited behaviour, (b) trap-limited conduction with a constant mobility and (c) trap-free space-charge limited conduction with a hopping-type charge carrier mobility. By comparing experimental results of thickness and temperature dependent current-voltage characteristics with numerical simulations, the field and temperature dependence of the mobility and the trap distribution is obtained. Impedance spectroscopy yields additional information about the dispersive nature of charge carrier transport in this material.