Universität zu Köln

Tenopala-Carmona, Francisco, Lee, Oliver S., Crovini, Ettore, Neferu, Ana M., Murawski, Caroline ORCID: 0000-0002-3496-4110, Olivier, Yoann, Zysman-Colman, Eli ORCID: 0000-0001-7183-6022 and Gather, Malte C. (2021). Identification of the Key Parameters for Horizontal Transition Dipole Orientation in Fluorescent and TADF Organic Light-Emitting Diodes. Adv. Mater., 33 (37). WEINHEIM: WILEY-V C H VERLAG GMBH. ISSN 1521-4095

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Abstract

In organic light-emitting diodes (OLEDs), horizontal orientation of the emissive transition dipole moment (TDM) can improve light outcoupling efficiency by up to 50% relative to random orientation. Therefore, there have been extensive efforts to identify drivers of horizontal orientation. The aspect ratio of the emitter molecule and the glass-transition temperature (T-g) of the films are currently regarded as particularly important. However, there remains a paucity of systematic studies that establish the extent to which these and other parameters control orientation in the wide range of emitter systems relevant for state-of-the-art OLEDs. Here, recent work on molecular orientation of fluorescent and thermally activated delayed fluorescent emitters in vacuum-processed OLEDs is reviewed. Additionally, to identify parameters linked to TDM orientation, a meta-analysis of 203 published emitter systems is conducted and combined with density-functional theory calculations. Molecular weight (MW) and linearity are identified as key parameters in neat systems. In host-guest systems with low-MW emitters, orientation is mostly influenced by the host T-g, whereas the length and MW of the emitter become more relevant for systems involving higher-MW emitters. To close, a perspective of where the field must advance to establish a comprehensive model of molecular orientation is given.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Tenopala-Carmona, Francisco UNSPECIFIED UNSPECIFIED UNSPECIFIED Lee, Oliver S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Crovini, Ettore UNSPECIFIED UNSPECIFIED UNSPECIFIED Neferu, Ana M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Murawski, Caroline UNSPECIFIED orcid.org/0000-0002-3496-4110 UNSPECIFIED Olivier, Yoann UNSPECIFIED UNSPECIFIED UNSPECIFIED Zysman-Colman, Eli UNSPECIFIED orcid.org/0000-0001-7183-6022 UNSPECIFIED Gather, Malte C. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-581430
DOI:	10.1002/adma.202100677
Journal or Publication Title:	Adv. Mater.
Volume:	33
Number:	37
Date:	2021
Publisher:	WILEY-V C H VERLAG GMBH
Place of Publication:	WEINHEIM
ISSN:	1521-4095
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language ACTIVATED DELAYED FLUORESCENCE; MOLECULAR-ORBITAL METHODS; HIGHLY EFFICIENT BLUE; AGGREGATION-INDUCED EMISSION; EXTERNAL QUANTUM EFFICIENCY; DENSITY-FUNCTIONAL THEORY; GAUSSIAN-TYPE BASIS; EXCITATION-ENERGIES; BASIS-SETS; GEOMETRIC DERIVATIVES Multiple languages Chemistry, Multidisciplinary; Chemistry, Physical; Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Physics, Applied; Physics, Condensed Matter Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/58143