Al-Attar, H.A. and Monkman, A.P. (2011) 'Solution processed multilayer polymer light-emitting diodes based on different molecular weight host.', Journal of applied physics., 109 (7). 074516.
Solution processed multilayer polymer light-emitting diodes (PLEDs) based on different molecular weight host have been investigated. A PLED based on high molecular weight poly (vinyl carbazole) PVKH and low molecular weight poly (vinyl carbazole) PVKL, doped with iridium, tris(2-phenylpyidine) Ir(ppy)3 as a host-guest emitting layer (EML), shows a dramatic increase in device efficiency. When the PVKH was used as a hole transport electron blocking layer (HT-EBL), effective electron blocking was achieved, which leads to an increase exciton population in the phosphorescent zone. The use of low molecular weight PVKL as a host material in the top layer prevents barrier formation for hole transport from the poly(3,4-ethylenedioxy-thiophene) (PEDOT)–EBL to the EML. External quantum efficiency of 11%, current efficiencies of 38 cd/A, power efficiency of 13 lm/W and brightness of 7000 cd/m2, were obtained. The effect of the PVKH layer on the electrical and optical device characteristics was investigated. Simulation of the optical outcoupling using SETFOS 3.1 software is in agreed with the observed results and allowed us to predict the emissive dipole location and distribution in the EML layer. The effect of the PVKH on the exciton quenching by the electrodes was also investigated using time resolved fluorescence photon counting, which indicates weak exciton quenching by the PEDOT layer and the device enhancement predominantly achieved by exciton confinement in the emissive layer.
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|Publisher Web site:||http://dx.doi.org/10.1063/1.3569831|
|Publisher statement:||© 2011 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Al-Attar, H.A. and Monkman, A.P. (2011) 'Solution processed multilayer polymer light-emitting diodes based on different molecular weight host.', Journal of applied physics., 109 (7). 074516 and may be found at http://dx.doi.org/10.1063/1.3569831|
|Record Created:||25 Sep 2012 11:20|
|Last Modified:||26 Sep 2012 09:42|
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