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Proceedings Paper

Studies of the internal electric field in organic light-emitting diodes and solar cells by electroabsorption spectroscopy
Author(s): Paul A. Lane; Carsten Giebeler; S. A. Whitelegg; Simon J. Martin; Alasdair J. Campbell; Joern Rostalski; Dieter Meissner; Donal D. C. Bradley
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Paper Abstract

We report electroabsorption studies of electric fields in organic light emitting diodes made form substituted poly(para phenylene vinylene) derivatives and solar cells made form zinc phthalocyanine (ZnPc) and perylenetetracarboxylic diimide (PTCDI). The electric field in LEDs is not proportional to the applied bias due to the development of an internal electric field during operation that opposes the applied bias. This counter field is weaker for devices measured in vacuum than for those measured in an ambient atmosphere and is no longer apparent for devices that were prepared and tested under an inert atmosphere. We also observed that the built-in potential increased with operating time. The combination of these two processes leads to an increase in the turn-on voltage of organic LEDs with increasing operating time. We have detected an electric field at the electrode/organic LEDs with increasing operating time. We have detected an electric field at the electrode/organic interface of organic solar cells which is insensitive to the external DC bias. The interface field has a different spectral signature from that of the bulk of the two layers and is attributed to charged transfer-induced dipoles. Rectifying behavior due to the formation of a pn junction under illumination is observed in bilayer solar cells, but not single layer devices made from ZnPc or PTCDI.

Paper Details

Date Published: 19 May 2000
PDF: 14 pages
Proc. SPIE 3939, Organic Photonic Materials and Devices II, (19 May 2000); doi: 10.1117/12.386369
Show Author Affiliations
Paul A. Lane, Univ. of Sheffield (United Kingdom)
Carsten Giebeler, Univ. of Sheffield (United States)
S. A. Whitelegg, Univ. of Sheffield (United Kingdom)
Simon J. Martin, Univ. of Sheffield (United Kingdom)
Alasdair J. Campbell, Univ. of Sheffield (United Kingdom)
Joern Rostalski, Forschungszentrum Juelich GmbH (Germany)
Dieter Meissner, Forschungszentrum Juelich GmbH (Austria)
Donal D. C. Bradley, Univ. of Sheffield (United Kingdom)

Published in SPIE Proceedings Vol. 3939:
Organic Photonic Materials and Devices II
Donal D. C. Bradley; Bernard Kippelen, Editor(s)

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