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Molecular origin of the anisotropic dye orientation in emissive layers of organic light emitting diodes

Friederich, Pascal ORCID iD icon 1; Coehoorn, Reinder; Wenzel, Wolfgang 1
1 Institut für Nanotechnologie (INT), Karlsruher Institut für Technologie (KIT)

Abstract (englisch):

Molecular orientation anisotropy of the emitter molecules used in organic light emitting diodes (OLEDs) can give rise to an enhanced light-outcoupling efficiency, when their transition dipole moments are oriented preferentially parallel to the substrate, and to a modified internal quantum efficiency, when their static dipole moments give rise to a locally modified internal electric field. Here, the orientation anisotropy of state-of-the-art phosphorescent dye molecules is ivestigated using a simulation approach which mimics the physical vapor deposition process of amorphous thin films. The simulations reveal for all studied systems significant orientation anisotropy. Various types are found, including a preference of the static dipole moments to a certain direction or axis. However, only few systems show an improved outcoupling efficiency. The outcoupling efficiency predicted by the simulations agrees with experimentally reported values. The simulations reveal in some cases a significant effect of the host molecules, and suggest that the driving force of molecular orientation lies in the molecule-specific van der Waals interactions of the dye molecule within the thin film surface. ... mehr

Postprint §
DOI: 10.5445/IR/1000076157
Veröffentlicht am 22.12.2022
DOI: 10.1021/acs.chemmater.7b03742
Zitationen: 38
Web of Science
Zitationen: 32
Zitationen: 37
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Nanotechnologie (INT)
Publikationstyp Zeitschriftenaufsatz
Publikationsdatum 25.10.2017
Sprache Englisch
Identifikator ISSN: 0897-4756, 1520-5002
KITopen-ID: 1000076157
HGF-Programm 43.21.04 (POF III, LK 01) Molecular Engineering
Erschienen in Chemistry of materials
Verlag American Chemical Society (ACS)
Band 29
Heft 21
Seiten 9528-9535
Nachgewiesen in Dimensions
Web of Science
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