Kum Hee Lee

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where ε equals permittivity, εr equals relative permittivity, ε0 equals permittivity of free space (8.85 10 12 F Laboratory tests were conducted to simultaneously measure soil m 1), ε r equals dielectric constant (the real part of relawater content and salinity using a four-electrode Wenner array sensor. The sensor was modified to enhance the capacitive(More)
The authors have demonstrated white organic light-emitting diodes for emotion solid-state lighting (ESSL) by using hole modulating layer (HML), N,N'-diphenyl-N,N'-bis-[4-(phenyl-m-tolyl-amino)-phenyl]-biphenyl-4,4'-diamine and N,N'-bis-(1-naphyl)-N,N'-diphenyl-1,1'-biphenyl-4, 4'-diamine, and mixed spacer (MS), 4,4',4"-tris(N-carbazolyl)-triphenylamine and(More)
Blue fluorescent materials with a 2-(diphenylamino)fluoren-7-ylvinylarene emitting unit and tert-butyl-based blocking units were synthesized. The photophysical properties of these materials, including UV/Vis absorption, photoluminescent properties, and HOMO-LUMO energy levels, were characterized and rationalized with quantum-mechanical DFT calculations. The(More)
We have demonstrated a highly efficient blue phosphorescent organic light emitting diodes (PHOLED) using iridium (111) bis[(4,6-di-fluoropheny)-pyridinato-N,C2] picolinate doped in double emitting layers (D-EML), N,N-dicarbazolyl-3,5-benzene (mCP) and p-bis (triphenylsilyly)benzene (UGH2). D-EML layers were employed to broaden the exciton formation zone and(More)
A series of blue fluorescent materials 1-6 based on N, N-diphenyl aminofluorene styryl derivatives with six heteroatoms (PhOPh, PhSPh, PhSePh, PhPPh2, thiophene and dibenzothiophene), were synthesized and multilayer devices were fabricated. Interestingly, the EL efficiencies were very sensitive to the structural features of dopants in the emitting layers.(More)
Blue fluorescent materials based on diphenylaminofluorenylstyryl derivatives connected with the various end-capping aromatic groups were synthesized and characterized. An OLED, using (E)-9,9-diethyl-7-(4-(4-fluoronaphthalen-1-yl)styryl)-N,N-diphenyl-9 H-fluoren-2-amine(5) in emitting layer, was fabricated. This device showed the highly efficient blue(More)
A series of bipolar anthracene derivatives containing triphenylamine as an electron donating group and pyridine, quinoline, isoquinoline and benzothiazole as electron withdrawing groups were synthesized and characterized. Particularly, a material, 9-quinolinyl-10-triphenylamin anthracene (3) exhibits a highly efficient sky-blue EL emission with the luminous(More)
In this work, we designed and synthesized two red emitters 2-(6,8-di-tert-butyl-2-(2-(1,1-dimethyl-7-(trimethylsilyl)-7-((trimethylsilyl)methyl)-1,2,3,5,6,7-hexahydropyrido[3,2,1-ij]quinolin-9-yl)vinyl)-4H-chromen-4-ylidene)malononitrile (Red 1) and(More)
The authors have demonstrated efficient and color-stable white organic light-emitting diodes (WOLEDs) by using three emitters, 4"-(2,2-diphenylvinyl)-1-[4-(N,N-diphenylamino)-styryl]-terphenyl (PVAS-tPh), fac tris(2-phenypyridine) irdium(III) (Ir(ppy)3), and Bis(5-benzoyl-2-phenylpyridinato-C,N)iridium(III) (acetylacetonate) (Bzppy)2Ir(III)acac). In this(More)
In this paper, we described a donor-acceptor-donor type red fluorescence material, which have the bulky trimethylsilane groups in the donor moieties. To explore the electroluminescence properties of these materials, multilayered OLEDs were fabricated with a device structure of ITO/2-TNATA (60 nm)/NPB (40 nm)/Red 1 (2%):rubrene (50%):Alq3 (30 nm)/Alq3 (60(More)