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The Internal Field Distribution in Light Emitting Electrochemical Cells and Light Emitting Diodes: A Comparative Study

Published online by Cambridge University Press:  21 March 2011

Erik Moderegger ,
Franz P. Wenzl ,
Stefan Tasch  and
Günther Leising
Erik Moderegger
Affiliation:
Institut für Festkärperphysik, Technische Universität Graz, A-8010 Graz, AUSTRIA
Franz P. Wenzl
Affiliation:
Institut für Festkärperphysik, Technische Universität Graz, A-8010 Graz, AUSTRIA
Stefan Tasch
Affiliation:
Institut für Festkärperphysik, Technische Universität Graz, A-8010 Graz, AUSTRIA
Günther Leising
Affiliation:
Institut für Festkärperphysik, Technische Universität Graz, A-8010 Graz, AUSTRIA
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Abstract

We determined the internal electric field distribution in light emitting electro-chemical cells (LECs) and light emitting diodes (LEDs) based on methyl substituted poly(paraphenylen) (mLPPP) by performing electroabsorption measurements as a function of an external bias voltage. Based on these results we outline the working principle of both types of devices. In the case of the LEC we observed an abrupt increase in the EA signal above a threshold voltage of about 2V which we attributed to junction formation due to in-situ electrochemical doping. For single layer LEDs we found the behavior expected for metal/insulator/metal/structures, i.e. the electric field drops linearly over the bulk polymer and no space-charge regions were observed.

These findings are important for improving the performance of organic electroluminescent devices.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 598: Symposium BB – Electrical, Optical, & Magenetic Properties...V , 1999 , BB3.47
Copyright
Copyright © Materials Research Society 1999

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