High-efficiency solution processed electrophosphorescent organic light emitting diodes based on a simple bi-layer device architecture

Mathew Mathai; Vi-En Choong; Stelios A. Choulis; Franky So

doi:10.1117/12.617458

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9 October 2005 High-efficiency solution processed electrophosphorescent organic light emitting diodes based on a simple bi-layer device architecture

Mathew Mathai, Vi-En Choong, Stelios A. Choulis, Franky So

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Proceedings Volume 5937, Organic Light-Emitting Materials and Devices IX; 59370C (2005) https://doi.org/10.1117/12.617458
Event: Optics and Photonics 2005, 2005, San Diego, California, United States

Abstract

In this study molecular doping in non-conjugated polymeric systems is utilized in order to obtain high efficiency electrophosphorescent light emitting devices (PHOLEDs). The device consists of a light emitting thin film layer composed of hole and electron transporting moieties dispersed in a polymer matrix of polyvinylcarbazole (PVK). Light emission is obtained by harvesting singlet as well as triplet excitons by means of a phosphorescent dye, Iridium (III) tris(2-(4-tolyl)pyridinato-N,C²) (Ir(m-ppy)₃), also dispersed in the polymer matrix. By incorporating a low conductivity polyethylene dioxythiophene-polystyrene-sulfonate (PEDOT) hole injection layer between the indium tin oxide transparent anode and the light emitting molecularly doped layer, the efficiency of these devices reaches values as high as 41 cd/A with a peak luminous efficacy of 28 lm/W. At the same time, triplet quenching by the hole transporting moiety as well as the electrodes are expected to be limiting the efficiency of these devices. In this paper we discuss several alternative device architectures studied in order to understand the factors affecting the device performance. In particular the effect of incorporating alternative hole transporting moieties and hole blocking layers are addressed.

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Mathew Mathai, Vi-En Choong, Stelios A. Choulis, and Franky So "High-efficiency solution processed electrophosphorescent organic light emitting diodes based on a simple bi-layer device architecture", Proc. SPIE 5937, Organic Light-Emitting Materials and Devices IX, 59370C (9 October 2005); https://doi.org/10.1117/12.617458

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