High-Efficiency Phosphorescent White Organic Light-Emitting Diodes with Stable Emission Spectrum Based on RGB Separately Monochromatic Emission Layers

Highly efficient phosphorescent white organic light-emitting diodes (WOLEDs) with stable emission spectra are successfully fabricated by using an RGB three-color separately monochromatic emission layer (EML) struc- ture. The EML consists of a sequence of bis(2-methyldibenzo[f, h]quinoxaline) (acetyl...

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Veröffentlicht in:Chinese physics letters 2014-04, Vol.31 (4), p.122-125
Hauptverfasser: Zhang, Zhi-Qiang, Liu, Yi-Peng, Dai, Yan-Feng, Chen, Jiang-Shan, Ma, Dong-Ge, Zhang, Hong-Mei
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Sprache:eng
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Zusammenfassung:Highly efficient phosphorescent white organic light-emitting diodes (WOLEDs) with stable emission spectra are successfully fabricated by using an RGB three-color separately monochromatic emission layer (EML) struc- ture. The EML consists of a sequence of bis(2-methyldibenzo[f, h]quinoxaline) (acetylacetonate) iridium (Ⅲ) (Ir(MDQ)2(acac)) doped tris(4-carbazoyl-9-ylphenyl)amine (TCTA) as the red emission layer, iridium, tris(2- phenylpyidine)(Ir(ppy)3) doped TCTA as the green emission layer and iridium(Ill) Ibis(4, 6-difuorophenyl)- pyridinato-N, C2']picolinate (FIrpic) doped a mixed-host of TCTA and tris(4-carbazoyl-9-ylphenyl)amine (26DCz PPy) as the blue emission layer. Without using any out-coupling techniques, the resulting WOLEDs achieve a power efficiency of 421m/W at lOO cd/m2, and 34 lm/W at 1000 cd/m2. The WOLEDs also show excellent spec- trum stability with bias voltages, remaining the Commission Internationale de L'Eclairage coordinates at (0.44, 0.43) from 1000 cd/m2 to 10000 cd/m2 and the color rendering index is as high as over 80. We contribute the sta- ble emission spectrum to the RGB separate EML structure that successfully suppresses the undesired competition between host-guest energy transfer and direct exciton formation on emissive dopants by effectively controlling the position of exciton recombination region.
ISSN:0256-307X
1741-3540
DOI:10.1088/0256-307X/31/4/046801