Spin dependent transport and recombination in organic light-emitting diodes

Electrically detected magnetic resonance (EDMR) was used to study a series of multilayer organic devices based on aluminum (III) 8-hydroxyquinoline (Alq<sub>3</sub>). These devices were designed to identify the microscopic origin of different spin dependent process, i.e., hopping and exciton formation. For electroluminescent diode the EDMR signal can be decomposed in at least two Gaussian components with peak-to-peak linewidth (&Delta;H<sub>PP</sub>) of 1.6 mT and another with 2.0 mT to 3.4 mT. These components are dependent on the applied bias or current used during EDMR measurements. The narrower line was attributed to the exciton precursor cations, while the broad one to the anions. These attributions are supported by the investigation of unipolar diodes, where hopping process related to dication and dianion formation were observed. In this work it is found that the probability of singlet exciton formation during electrolumincscency is smaller than 25%


Published in:
Physica Status Solidi C, 10, 3661
Year:
2005
Publisher:
Wiley-VCH
Keywords:
Note:
Departamento de Fisica e Matematica, FFCLRP-Univ. de Sao Paulo, Ribeirao Preto, Brazil
Copyright 2006, IEE
8810738
1610-1634
spin dependent transport
spin dependent recombination
organic light-emitting diodes
electrically detected magnetic resonance
multilayer organic devices
hopping process
exciton formation
electroluminescent diode
Gaussian components
unipolar diodes
dication formation
dianion formation
charge injection
Laboratories:




 Record created 2007-04-03, last modified 2018-12-03


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