Color stability and suppressed efficiency roll-off in white organic light-emitting diodes through management of interlayer and host properties

Color stability and efficiency roll-off of white light-emitting diodes (WOLEDs) with blue fluorescent and red phosphorescent emitting materials were manipulated by controlling the charge transport properties of interlayer and triplet host materials. A pure white emission was observed in WOLEDs with a bipolar interlayer and a hole transport type triplet host material. A white color coordinate of (0.31, 0.35) and a current efficiency of 14.4 cd/A were obtained. In addition, color index of WOLEDs could be kept stable up to a high luminance of 10,000 cd/m(2) and an efficiency roll-off was also suppressed. (C) 2009 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.