Berlin 2001 – scientific programme
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CPP: Chemische Physik und Polymerphysik
CPP 16: Poster: Dynamics of Molecular Systems, Polymer Dynamics, Glass Transition, Crystallization, Electronic Properties of Polymers
CPP 16.28: Poster
Monday, April 2, 2001, 12:30–15:00, AT1
Space charge distributions in luminescent and nonluminescent conjugated polymers — •Frank Feller1, Dieter Geschke1, and Andy P. Monkman2 — 1University of Leipzig, Faculty of Physics and Earth Sciences, Institute of Experimental Physics I, Polymer Research Group, Linn*strasse 5, D-04103 Leipzig, Germany — 2Organic Electroactive Materials Research Group, Department of Physics, University of Durham, South Road, Durham DH1 3LE, UK
We present measurements of the spatial distribution of space charges in luminescent and nonluminescent conjugated polymers. We have applied a thermal wave technique (LIMM) to study the pyroelectric response originating from trapped charge at the surface and in the bulk of films of conjugated polymers. It is found that the devices can be poled, i.e. charge can be permanently stored within the film and can only be relieved under electric bias in the time scale of minutes. The poling process as well as the spatial distribution of the space charge is strongly dependent on the applied electric field and on sample temperature.
The results demonstrate that the electric field drops within the first 20 percent of the film thickness due to space charge layers, which should make an impact on the carrier transport and mobility in the bulk and hence on the performance of electric devices such as conjugated polymer light emitting diodes.