• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.305-306
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• 2009

In this study, we have invastigated the recombination zone in the blue phosphorescent organic light-emitting devices with various partially doped structures. The basic device structure of the blue PHOLED was anode / hole injection layer (HIL) / hole transport layer (HTL) / emittingvastigated the recombination zone in the blue layer (EML) / hole blocking layer (HBL) / electron transport layer (ETL) / electron injection layer (EIL) / cathode. After the preparation of the blue PHOLED, the current density (J) - voltage (V) - luminance (L) and current efficiency characteristics were measured.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2002년도 International Meeting on Information Display
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• pp.773-776
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• 2002

Efficient organic white light-emitting diodes are fabricated by doping [bis(2-methyl-8-quinolinolato) (tripheny-siloxy)aluminium (III)] (SAlq), a blue-emitting layer, with a red fluorescent dye of 4-dicyanomethylene-2-methyl-6-{2-(2,3,6,7-tetrahydro-1H,5H-benzo[i,j]quinolizin-8-yl)vinyl}-4H-pyran (DCM2). The incomplete energy transfer from blue-emitting SAlq to red-emitting DCM2 enables to obtain a balanced white light-emission. A device with the structure of ITO/TPD (50 nm)/SAlq:DCM2 (30 nm, 0.5 %)/$Alq_3$ (20 nm)/LiF (0.5 nm)/AI shows emission peaks at 456 nm and 482 nm from SAlq and at 570 nm from DCM2. The white light-emitting device shows an external quantum efficiency of about 2.3 %, a luminous efficiency of about 2.4 lm/W, and the CIE chromaticity coordinates of (0.32, 0.37) at 100 cd/m^2. A maximum luminance of about 23,800 cd/m^2. is obtained at 15 V and the current density of 782 mA/cm^2.

• 한국전기전자재료학회논문지
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• 제16권7호
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• pp.616-621
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• 2003

The white-light-emitting organic LED with two-wavelength was fabricated using blue emitting material(DPVBi) and a series of orange color fluorescent dye(Rubrene) by vacuum evaporation processes. The basic structure of white-light-emitting OLED was ITO/NPB(150$\AA$)/DPVBi(150$\AA$)/Alq$_3$:Rubrene(150$\AA$)/BCP(100$\AA$)/Alq$_3$(150$\AA$)/Al(600$\AA$). The changes of the CIE coordiante strongly depended on the doping concentration of Rubrene and the thickness of NPB layer. We obtained the white-light-emitting OLED close to the pure white color light and the CIE coordinate of the device was (0.315, 0.330) at applied voltage of 13V when the doping concentration of Rubrene was 0.5wt% and the thickness of NPB layer is 200$\AA$. At a current of 100mA/$\textrm{cm}^2$, the quantum efficiency was 0.35%.

• 한국전기전자재료학회논문지
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• 제22권12호
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• pp.1045-1057
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• 2009

The authors investigated the InGaN/GaN multi-quantum well blue light emitting devices with the implementation of the photonic crystals fabricated at the top surface of p-GaN layer and the bottom interface of n-GaN layer. The top photonic crystals result in the lattice-dependent photoluminescence spectra at the wavelength of 450 nm and however, the bottom photonic crystal shows a big shift of the photoluminescence peak from 444 nm to 394 nm. The sample with the bottom photonic crystal structure also shows the lasing effect at the wavelength of 468 nm. Furthermore, the quality enhancement for the crystal growth of GaN thin film on the bottom photonic crystal comes from the modulated compressive stress which was measured by the micro-Raman spectroscopy.

• 한국전기전자재료학회논문지
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• 제16권12호
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• pp.1121-1124
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• 2003

We report the photo (PL) and electro luminescence (EL) properties of new conjugated compounds based on imidazole moiety, 4,4' -di(4,5 diphenyl-N-imidazolyl)stilbene(DDPIS) and 4,4'-di(2,4,5-triphenyl-N-imidazolyl)stilbene(DTPIS), as emitting materials. ITO/m-MTDATA/NPB/DDPIS/Alq3/LiF/AI device shows blue EL spectrum at 456 ㎚ and 0.3 cd/ A and turn on voltage at 7 ∼ 8 V. DTPIS shows blue EL spectrum at around λmax=453㎚ and 0.5 cd/A efficiency in ITO/m-MTDATA/NPB/DTPIS/Alq3/LiF/Al device.

• 한국전기전자재료학회논문지
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• 제26권9호
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• pp.682-685
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• 2013

We have fabricated blue phosphorescent organic light-emitting devices (OLEDs) on a plastic substrate. The solution coated poly (9-vinylcarbazole) (PVK) host doped with Bis (3,5-difluoro-2-(2-pyridyl)phenyl_(2-carboxypyridyl)irdium(III) (FIrPic) guest molecules was used as an hole transporting emission layer. The device structure was ITO/PVK:FIrpic (50 nm, xwt%)/TAZ 50 nm)/LiF (0.5 nm)/Al (100 nm). The concentration of FIrpic molecule was varied from 1 wt% to 10 wt%. The OLED on plastic substrate exhibited maximum current efficiency of 18 cd/A with 5 wt% FIrpic molecules were doped into the PVK layer.

• 한국전기전자재료학회논문지
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• 제19권8호
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• pp.775-779
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• 2006

In this study, sputtered $Al_2O_3$ thin films were evaluated as a passivation layer in the process of InGaN-based blue LEDs in order to improve the brightness of LED lamps. In terms of packaged LED lamps, lamps with $Al_2O_3$ passivation layer emanated higher brightness than those with $SiO_2$ passivation layer, and LED lamps with 90 nm $Al_2O_3$ passivation layer were the brightest among four kinds of lamps. Although lamps with $Al_2O_3$ passivation had a slight increase in operating voltage, their brightness was improved about 13.6 % compare to the lamps made of conventional LEDs without the changes of emitting wavelength.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.228-230
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• 2001

We synthesized Bis(3-N-ethylcarbazolyl) terephthalidene(BECP) and Bis(3-7-ethyl-carbazolyl) cyanoterephthalidene(BECCP) and characterized EL properties of these materials. Our device shows a strong blue emission at 472 nm with a luminance efficiency of 0.9 lm/W at a voltage, a current density, and a brightness of 8 V, 5.7 mA/cm$^2$, and 130 cd/m$^2$, respectively.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.620-622
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• 2004

In this study, a mono-chelated compound as novel blue light emitting material, $BPh_2$(pbi) (pbi = 2-(2-Pyridyl)benzimidazole) was synthesized Organic light emitting Diodes (OLEDs), which has a ITO/NPB(40 nm)/Boron(30 nm)/$Alq_3$(1 nm)/Liq(3 nm)/Al(150 nm) structure, has been fabricated. The maximum brightness of the device is up to about 900 cd/$m^2$ and 0.54 cd/A at 11.5 V. The EL peaks and CIE coordinates of our OLEDs is 457 nm and (0.26, 0.29), respectively.

• Bulletin of the Korean Chemical Society
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• 제34권5호
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• pp.1355-1360
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• 2013

We have developed a new multifunctional material, 4,4',4"-tris(4-naphthalen-2-yl-phenyl)amine (2-TNPA), which can be used as a blue-emitting and hole-transporting material in organic light-emitting diodes (OLEDs), as well as a donor material in organic solar cells (OSCs) and an active material in organic thin-film transistors (OTFTs). The OLED device doped with 3% 2-TNPA shows a maximum current efficiency of 3.0 $cdA^{-1}$ and an external quantum efficiency of 3.0%. 2-TNPA is a more efficient hole-transporting material than 4,4'-bis[N-(naphthyl-N-phenylamino)]biphenyl (NPD). Furthermore, 2-TNPA shows a power-conversion efficiency of 0.39% in OSC and a field-effect mobility of $3.2{\times}10^{-4}cm^2V^{-1}s^{-1}$ in OTFTs.