22 May 2009 Performance optimization of polymer doped electrophosphorescent organic light emitting diodes
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Proceedings Volume 7282, 4th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Advanced Optical Manufacturing Technologies; 72823D (2009); doi: 10.1117/12.831027
Event: AOMATT 2008 - 4th International Symposium on Advanced Optical Manufacturing, 2008, Chengdu, Chengdu, China
Abstract
Polymer doped electrophosphorescent organic light-emitting diodes with a structure of indium tin oxide (ITO) /poly(N-vinylcarbazole)(PVK) : bis(1,2-dipheny1-1H-benzoimidazole) iridium (acetylacetonate) [(pbi)2Ir(acac)] (1wt%)(70 nm)/bathocuproine(BCP)(× nm)/tris(8-hydroxyquinolate)-aluminum (Alq3)(30-× nm)/Mg:Ag have been fabricated. The light-emitting layer is processed by doping noble metal iridium complex (pbi)2Ir(acac) into a carbazole copolymer of PVK matrix with the low doping concentration of 1wt% using spin coating method. The influence of film thickness of the hole blocking layer and electron transporting layer between the emitting layer and the cathode on the performance of device are investigated. Results show that to keep the whole thickness of the hole blocking layer and electron transporting layer as a constant, charge carrier recombination zone is transferred from electron transporting layer to light-emitting layer by gradual increase the hole blocking layer thickness. The device performance is enhanced simultaneously. The efficiency enhancement may be attributed to the formation of a narrow recombination zone, in which both charge carriers and excitons are confined. High charge concentrations in the emissive layer results in the efficient collision capture in the electron-hole recombination process, and exciton confinement leads to improving energy transfer and charge trapping in polymer doped phosphorescent system.
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Xiaoqing Tang, Junsheng Yu, Wen Wen, Lu Li, Yadong Jiang, "Performance optimization of polymer doped electrophosphorescent organic light emitting diodes", Proc. SPIE 7282, 4th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Advanced Optical Manufacturing Technologies, 72823D (22 May 2009); doi: 10.1117/12.831027; https://doi.org/10.1117/12.831027
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KEYWORDS
Polymers

Electron transport

Excitons

Organic light emitting diodes

Electroluminescence

Doping

Energy transfer

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