Open AccessSpin dependent transport and recombination in organic lightemitting diodes
Author(s) -
Silva George B.,
Nüesch Frank,
Zuppiroli Libero,
Graeff Carlos F. O.
Publication year - 2005
Publication title -
physica status solidi (c)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.21
H-Index - 46
eISSN - 1610-1642
pISSN - 1610-1634
DOI - 10.1002/pssc.200461744
Subject(s) - exciton , laser linewidth , electroluminescence , diode , chemistry , singlet state , spin (aerodynamics) , electron paramagnetic resonance , optoelectronics , oled , chemical physics , materials science , atomic physics , condensed matter physics , nuclear magnetic resonance , laser , physics , optics , excited state , organic chemistry , layer (electronics) , thermodynamics
Electrically Detected Magnetic Resonance (EDMR) was used to study a series of multilayer organic devices based on aluminum (III) 8‐hydroxyquinoline (Alq 3 ). 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 (Δ H PP ) 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 electroluminescency is smaller than 25%. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)