Highly Efficient Color‐Stable Deep‐Blue Multilayer PLEDs: Preventing PEDOT:PSS‐Induced Interface Degradation
Sebastian Nau1, Niels Schulte2, Stefanie Winkler3, Johannes Frisch4, Antje Vollmer3, Norbert Koch4, Stefan Sax1, Emil J. W. List‐Kratochvil1,5
(1)NanoTecCenter Weiz Forschungsgesellschaft mbH Franz‐Pichler Straße 32, A‐8160 Weiz (Austria) (2)Merck KGaA Frankfurter Str. 250, D‐64293 Da
15:20 - 17:30 Thursday 24 October 2013 Foyer Alte Technik Organic light emitting diodes are doubtless the most advanced application in the field of organic electronics;
Impressive technological progress was achieved in the last decade not least because of the vital academic
interest on this topic. To enable for large‐area and low‐cost display and lighting applications, solution processable
and color stable materials are an ultimate prerequisite. In this contribution we address these key issues and
present a set of novel copolymers comprising building blocks with designed functionality with respect to blue
light emission, exciton generation and charge‐carrier transport. Furthermore we demonstrate that PEDOT:PSS,
the commonly used charge transport material, can induce a chemical degradation of the light emitting polymer at
their interface, resulting in an undesired bias voltage dependent emission color shift of the device. By
implementing a novel acid stable polymer interlayer, this process can be avoided. Due to the favourable hole
transporting properties of this interlayer and the beneficial type‐II band level alignment with the light emitting
polymer, the performance of the polymer light emitting diodes (PLEDs) is strongly enhanced. The final optimized
solution based multilayer PLEDs showed deep blue emission (CIE1931 x=0.144; y=0.129), luminance up to 16000
cd/m² and an efficiency of 9.7 cd/A, one of the highest ever reported values for blue emitting PLEDs.
The content of this contribution is published in Advanced Materials 25, 4420–4424 (2013).
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