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Investigation of energy transfer mechanisms between two adjacent phosphorescent emission layers
The investigation of energy transfer mechanisms between two adjacent phosphorescent emission layers comprising the green emitter molecule fac -tris(2-phenly-pyridin)iridium (Ir(ppy) 3 ) and the red emitter molecule iridium(III)bis(2-methyldibenzo[f,h]quinoxaline(acetylacetonate) (Ir(MDQ) 2 (acac)) i...
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Published in: | Journal of applied physics 2012-06, Vol.111 (11), p.113102-113102-9 |
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Main Authors: | , , , |
Format: | Article |
Language: | English |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | The investigation of energy transfer mechanisms between two adjacent phosphorescent emission layers comprising the green emitter molecule
fac
-tris(2-phenly-pyridin)iridium (Ir(ppy)
3
) and the red emitter molecule iridium(III)bis(2-methyldibenzo[f,h]quinoxaline(acetylacetonate) (Ir(MDQ)
2
(acac)) is presented. We show that the performance can be enhanced by a variation of the emission layer thickness and the emitter concentration. By inserting different interlayer materials between the emission units, we demonstrate that triplet excitons are formed on the Ir(ppy)
3
and subsequently transferred to the Ir(MDQ)
2
(acac) molecules via the hole transporting host material N,N′-bis(naphthalen-1-yl)-N,N′-bis(phenyl)-benzidine of the red emission layer. The variation of the interlayer thickness shows that the triplet diffusion length is several tens of nanometers. After optimization of the guest-host system an efficiency enhancement by 15% was achieved and the lifetime of the red-green emissive unit could be enhanced by 55%. Additionally, it is shown that this improved red-green unit can be combined with a fluorescent blue emitter in a state-of-the-art stacked white emissive organic light emitting diode. |
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ISSN: | 0021-8979 1089-7550 |
DOI: | 10.1063/1.4724346 |