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Proceedings Paper

Space charge effect in organic light-emitting devices (OLEDs)
Author(s): Harry L. Kwok
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Paper Abstract

Space charge is known to affect current transport in organic light emitting devices (OLEDs). This normally occurs at low bias when current density varies quadratically with the bias voltage. A transition exists when current flow changes from space-charge limited to “recombination” limited. In order to further investigate this transition, we extended our model on exciton formation based on bimolecular recombination [7] to include the existence of space charge. In examining the model characteristics, we found that where the transition occurs depends on the density of the space charge in the active layer and the fraction of it associated with "recombination". This also relates to a parameter a0 defining the optimal charge separation for "recombination" to take place. Our results indicated that the transition would vary for different organic semiconductors and would be an important factor affecting the device performance. In comparing our model with experimental data, we are of the opinion that space charge effect may be responsible for the occasional occurrence of an "anomalous" current reported in the J-V characteristics of OLEDs.

Paper Details

Date Published: 9 July 2003
PDF: 8 pages
Proc. SPIE 5218, Complex Mediums IV: Beyond Linear Isotropic Dielectrics, (9 July 2003); doi: 10.1117/12.505781
Show Author Affiliations
Harry L. Kwok, Univ. of Victoria (Canada)

Published in SPIE Proceedings Vol. 5218:
Complex Mediums IV: Beyond Linear Isotropic Dielectrics
Martin W. McCall; Graeme Dewar, Editor(s)

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