• Journal of Information Display
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• v.10 no.2
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• pp.92-95
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• 2009

Highly efficient blue and white phosphorescent organic light-emitting diodes (PHOLEDs) with an exciton-confining structure were investigated in this study. Effective charge confinement was achieved by stacking two emitting layers with different charge-transporting properties, and blue PHOLEDs with a maximum luminance efficiency of 47.9 lm/W were developed by using iridium(III) bis(4,6-(difluorophenyl) pyridinato-N,C2')picolinate (FIrpic) as an electrophosphorescent dopant. Moreover, when the optimized green and red emitting layers were sandwiched between the two stacked blue emitting layers, white PHOLEDs (WOLEDs) with peak external and luminance efficiencies of 19.0% coupling technique.and 54.0 lm/W, respectively, were obtained without the use of any out-coupling technique.

• Bulletin of the Korean Chemical Society
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• v.34 no.9
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• pp.2609-2615
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• 2013

A series of fluorene-carbazole copolymers containing the pendant phosphor chromophore $Ir(absn)_2(acac)$ (absn: 2-(1-naphthyl)benzothiazole; acac: acetylacetone) were designed and synthesized via Yamamoto coupling. In the film state, these copolymers exhibited absorption and emission peaks at approximately 389 and 426 nm, respectively, which originated from the fluorene backbone. However, in electroluminescent (EL) devices, a significantly red-shifted emission at approximately 611 nm was observed, which was attributed to the pendant iridium(III) complex. Using these copolymers as a single emission layer, polymer light-emitting devices with ITO/PEDOT:PSS/polymer:DNTPD/TmPyPb/LiF/Al configurations exhibited a saturated red emission at 611 nm. The attached iridium(III) complex had a significant effect on the EL performance. A maximum luminous efficiency of 0.85 cd/A, maximum external quantum efficiency of 0.77, maximum power efficiency of 0.48 lm/W, and maximum luminance of 883 $cd/m^2$ were achieved from a device fabricated with the copolymer containing the iridium(III) complex in a 2% molar ratio.