Kyoung Soo Yook

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Recently, great progress has been made in the device performance of deep blue phosphorescent organic light-emitting diodes (PHOLEDs) by developing high triplet energy charge-transport materials, high triplet energy host and deep blue emitting phosphorescent dopant materials. A high quantum efficiency of over 25% and a high power efficiency of over 15 lm/W(More)
Highly efficient green thermally activated delayed fluorescent organic light-emitting diodes with an external quantum efficiency of 31.2% were investigated by using 3-(3-(carbazole-9-yl)phenyl) pyrido[3',2':4,5]furo[2,3-b]pyridine (3CzPFP) derived from carbazole and pyrido[3',2':4,5]furo[2,3-b]pyridine. The host material showed well-matched(More)
Solution processed phosphorescent organic light-emitting diodes (OLEDs) have been actively developed due to merits of high quantum efficiency of phosphorescent materials and simple fabrication processes of solution processed OLEDs. The device performances of the solution processed phosphorescent OLEDs have been greatly improved in the last 10 years and the(More)
The development of soluble phosphorescent organic lightemitting diodes (PHOLEDs) is important because the low effi ciency of soluble fl uorescent organic light-emitting diodes (OLEDs) can be improved by using soluble PHOLEDs instead. [ 1–3 ] In particular, the effi ciency of soluble blue OLEDs is quite low compared to red and green OLEDs, and the(More)
2010 WILEY-VCH Verlag Gmb Blue-phosphorescent organic light-emitting diodes (PHOLEDs) have been developed for more than 10 years towards use in active-matrix-type organic light-emitting diodes. There has been much improvement in quantum efficiency, lifetime, and color purity although the device performances of the blue PHOLEDs are not yet good enough for(More)
A hybrid white organic light-emitting diode (WOLED) with an external quantum efficiency above 20% was developed using a new blue thermally activated delayed fluorescent material, 4,6-di(9H-carbazol-9-yl)isophthalonitrile (DCzIPN), both as a blue emitter and a host for a yellow phosphorescent emitter. DCzIPN showed high quantum efficiency of 16.4% as a blue(More)
Titania embedded silica hollow nanospheres were synthesized from sonication-mediated etching and re-deposition of silica/titania core/shell nanospheres. The designed structure of the hollow nanospheres was proved to be a key factor for the charge trapping/detrapping and resulting bistability in non-volatile organic bistable memory devices (OBDs).
High efficiency hybrid type white organic light-emitting diodes (WOLEDs) combining a green thermally activated delayed fluorescent (TADF) emitting material with red/blue phosphorescent emitting materials were developed by manipulating the device architecture of WOLEDs. Energy transfer between a blue phosphorescent emitting material and a green TADF emitter(More)