Universität zu Köln

Deng, Yali, Keum, Changmin, Hillebrandt, Sabina, Murawski, Caroline ORCID: 0000-0002-3496-4110 and Gather, Malte C. ORCID: 0000-0002-4857-5562 . Improving the Thermal Stability of Top-Emitting Organic Light-Emitting Diodes by Modification of the Anode Interface. Adv. Opt. Mater.. WEINHEIM: WILEY-V C H VERLAG GMBH. ISSN 2195-1071

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Abstract

Top-emitting organic light-emitting diodes (OLEDs) are of interest for numerous applications, in particular for displays with high fill factors. To maximize efficiency and luminance, molecular p-doping of the hole transport layer (p-HTL) and a highly reflective anode contact, for example, made from silver, are used. Atomic layer deposition (ALD) is attractive for thin film encapsulation of OLEDs but generally requires a minimum process temperature of 80 degrees C. Here it is reported that the interface between the p-HTL and the silver anode of top-emitting OLEDs degrades during an 80 degrees C ALD encapsulation process, causing an over fourfold reduction in OLED current and luminance. To understand the underlying mechanism of device degradation, single charge carrier devices are investigated before and after annealing. A spectroscopic study of p-HTLs indicates that degradation is due to the interaction between diffusing silver ions and the p-type molecular dopant. To improve the stability of the interface, either an ultrathin MoO3 buffer layer or a bilayer HTL is inserted at the anode/organic interface. Both approaches effectively suppress degradation. This work shows a route to successful encapsulation of top-emitting OLEDs using ALD without sacrificing device performance.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Deng, Yali UNSPECIFIED UNSPECIFIED UNSPECIFIED Keum, Changmin UNSPECIFIED UNSPECIFIED UNSPECIFIED Hillebrandt, Sabina UNSPECIFIED UNSPECIFIED UNSPECIFIED Murawski, Caroline UNSPECIFIED orcid.org/0000-0002-3496-4110 UNSPECIFIED Gather, Malte C. UNSPECIFIED orcid.org/0000-0002-4857-5562 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-311045
DOI:	10.1002/adom.202001642
Journal or Publication Title:	Adv. Opt. Mater.
Publisher:	WILEY-V C H VERLAG GMBH
Place of Publication:	WEINHEIM
ISSN:	2195-1071
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Chemistry > Institute of Physical Chemistry
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language HIGH-EFFICIENCY; DEGRADATION; TECHNOLOGY; DIFFUSION; EMISSION; LAYER; FILMS Multiple languages Materials Science, Multidisciplinary; Optics Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/31104