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21 May 2009 Study on charge carrier recombination zone with ultrathin rubrene layer as probe
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Proceedings Volume 7282, 4th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Advanced Optical Manufacturing Technologies; 72823B (2009) https://doi.org/10.1117/12.831025
Event: AOMATT 2008 - 4th International Symposium on Advanced Optical Manufacturing, 2008, Chengdu, Chengdu, China
Abstract
The characteristic of charge carrier recombination zone in N,N'-bis-(1-naphthyl)-N,N'-biphenyl-1,1'-biphenyl-4,4'-diamine (NPB) based OLEDs is studied using an ultrathin 5,6,11,12-tetraphenylnaphthacene (rubrene) as a probe. By adjusting the rubrene thickness and location in NPB light-emitting layer, the luminescent spectra and electrical properties of the devices are investigated. The results show that when the thickness ranges from 0.2 to 0.8 nm, the surface morphology of rubrene exists as the discontinuous island-like state locating on the surface of NPB film and seldom affect the electrical characteristics. While the location of rubrene shifted from the interface of NPB/2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) to NPB side, the maximum exciton concentration is found within 2 nm away from the interface, which is the main charge carrier recombination zone. With an optimized structure of indium-tin-oxide (ITO)/NPB (40nm)/rubrene (0.3nm)/NPB (7nm)/BCP (30nm)/Mg:Ag, the device exhibits a turn on voltage as low as 3 V and stable white light. The peaks of EL spectra are located at 431 and 555 nm corresponding to the Commissions Internationale De L'Eclairage (CIE) coordinates of (0.32, 0.32), which are relatively stable under the bias voltage from 5 to 15 V. A maximum luminance of 5630 cd/m2 and a maximum power efficiency of 0.6 lm/W is achieved. The balanced spectra are attributed to the stable confining of charge carriers and exciton by the thin emitting layers.
© (2009) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Wen Wen, Jungsheng Yu, Yi Li, Lu Li, and Yadong Jiang "Study on charge carrier recombination zone with ultrathin rubrene layer as probe", Proc. SPIE 7282, 4th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Advanced Optical Manufacturing Technologies, 72823B (21 May 2009); https://doi.org/10.1117/12.831025
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