Date

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[P2-124]
14:00 ~ 15:30
Title:Characteristics of Thermal Activated Delayed Fluorescent Organic Light Emitting Diode as 4CzIPn Doping Concentration
Kang-Hee Kim, Dong-A Ahn, Eun-Ji Um, and Chan-Jae Lee (KETI, Korea)
Abstract: Novel organic light emitting diodes (OLEDs) utilizing up-conversion of triplet excitons into a singlet state can remarkably increase the external quantum efficiency (EQE) up to the values far beyond those obtained for conventional fluorescent OLEDs and comparable with those of phosphorescent OLEDs. Thermally activated delayed fluorescence (TADF) allows a light emission efficiency of nearly 100% from efficient spin up-conversion system from T1 to S1 state. Because TADF materials show the emission delay phenomena due to the up-conversion system, a device with TADF shows the slow emission characteristics. So we analyzed transient EL that the TADF device with different doping concentrations in the emission layer. The green TADF device was fabricated as followed structure, ITO/HAT-CN(5 nm)/TAPC(50 nm)/mCP:4CzIPn(35 nm, X wt%)/TmPyPB(30 nm)/LiF(0.5 nm)/Al(100 nm). Here, emissive layer was composed mCP and (4s,6s)-2,4,5,6-tetra(9H-carbazol-9-yl)isophthalonitrile(4CzIPn) as a host and a dopant, respectively. And doping concentration was controlled from 1 to 15%. And we analyzed transient EL properties using 120Hz rectangular pulse by an oscilloscope and a high speed photodiode.
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