Regensburg 2004 – scientific programme

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SYOH: Organic and Hybrid Systems for Future Electronics

SYOH 5: Poster

SYOH 5.82: Poster

Thursday, March 11, 2004, 18:00–21:00, B

Investigation of electric field in organic thin film devices by electroabsorption spectroscopy — •Wenge Guo, Jens Drechel, Michael Hoffmann, Martin Pfeiffer, and Karl Leo — Institut fuer Angewandt Photophysik, Dresden,Germany

Electroabsorption (EA) spectroscopy is a non-destructive technique used to study the internal electric field distribution in organic light emitting diodes and organic solar cells. In EA measurement, an electric field modulation is applied to the device and a synchronous change in the optical absorption coefficient is detected. The change in the amplitude of the optical absorption coefficient at the fundamental frequency ? of the applied electric field is proportional to the static internal electric field in the device. As a starting point, we conduct electroabsorption measurements on polycrystalline MePTCDI and PTCDA thin single layer devices. EA spectra at 1? and 2? are obtained. In EA measurements at 1?, the EA signal vanishes as applied DC bias compensate the build-in potential due to the work function difference of the two electrodes. From this, a reasonable built-in potential (0.5 0.7eV) is observed. Since the EA response at 1? is linear with the applied DC bias in single layer devices, this method can be used further for characterization of static field distribution in multilayer devices.