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Abstract
Phosphorescence polymer LEDs (PhPLEDs) with the structure of ITO/PEDOT:PSS/PVK:Ir(ppy)3:PFO:Ir(pq)2acac/TPBI/LiF/Al were fabricated to investigate the effects of the doping concentration of Ir(pq)2acac on the electrical and optical properties of the devices. PVK(poly-vinylcarbazole) and Ir(ppy)3[tris(2-phenylpyridine)iridium(III)] polymers were used as the host and guest materials, respectively. PFO[poly(9,9-dioctylfluorene)] and Ir(pq)2(acac)[bis(2-phenyl-1-quinoline)iridiumacetyl acetonate] were also introduced as blue and red component guest materials for the white emission. The concentration ratio of PVK:Ir(ppy)3:PFO was fixed at 100:2.0:1.0 vol%. The Ir(pq)2acac concentration in the emission layer was varied from 1.0 to 5.0 vol%. White PhPLEDs were obtained for the samples with 5.0 vol% of Ir(pq)2acac, for which the luminance and current density were about 2530 cd/m2 and 720 mA/cm2 at 8 V, respectively. The CIE color coordinates were x, y = 0.33, 0.33, showing a pure white color.
Acknowledgments
This work was supported by a Korea Research Foundation Grant funded by the Korean Government (KRF-2008-521-D00261).