Evidence for charge-carrier mediated magnetic-field modulation of electroluminescence in organic light-emitting diodes

Electroluminescence (EL) from organic light-emitting diodes can be surprisingly sensitive ( ∼ 20 % ) to modest magnetic fields B ( 0 - 2 T ) . The origin of this magnetic-field effect has not been clearly identified, although the magnetic-field effect in some devices resembles that of delayed fluore...

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Bibliographic Details
Published in:Applied physics letters 2005-03, Vol.86 (11), p.111109-111109-3
Main Authors: Wilkinson, John, Davis, A. H., Bussmann, K., Long, J. P.
Format: Article
Language:English
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Summary:Electroluminescence (EL) from organic light-emitting diodes can be surprisingly sensitive ( ∼ 20 % ) to modest magnetic fields B ( 0 - 2 T ) . The origin of this magnetic-field effect has not been clearly identified, although the magnetic-field effect in some devices resembles that of delayed fluorescence in anthracene, which originates from magnetic-field-dependent singlet-exciton production via triplet-triplet annihilation (TTA). Here, we test the role of TTA at low magnetic fields ( ∼ 80 mT ) by measuring transient EL and by employing dc drive levels so low that the bimolecular rate of TTA is unimportant. Under these conditions, we find enhancements of EL exceeding 14% at the lowest drives, which excludes TTA-mediated magnetic-field effects and indicates a role for charge-carrier pair states.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.1883322