• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.578-580
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• 2008

Blue-emitting $CaAl_2Si_2O_8:Eu^{2+}(CAS:Eu^{2+})$ phosphor, prepared by solid-state reaction, is described in this paper. We researched the effect of boron ion substitution in the host materials. The phase and luminescent properties were investigated using the powder X-ray diffraction(XRD) and photoluminescence(PL) spectra.

• Textile Coloration and Finishing
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• v.19 no.6
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• pp.35-38
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• 2007

FTriphenylamine dye compound having diheteryl moiety was synthesized and its photoluminescent property was investigated. Organic luminescent materials have received great attentions due to potential application subjects onto full color image displays. In this context, the dye (III) for light emitting materials was synthesized using 2-(4-amino-2-hydroxyphenyl)benzoxazole (I) and 4,4'-diformyltriphenylamine (II). It is well known that the amino groups of compound (I) react with carbonyl groups, especially an aldehyde, to afford azomethine linkages. The dye shows bulish-green fluorescence property, which is anticipated for the light-emitting material for display devices. In this context, our aim is to synthesize diheteryl-substituted triphenylamine fluorescent dye as an emitting material. The spectroscopic characteristics and the fluorescent properties of this dye molecule were examined and determined.

• Bulletin of the Korean Chemical Society
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• v.32 no.3
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• pp.973-976
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• 2011

The addition of organic ligand (${\beta}$-diketone or heterocyclic compound) to the europium (III)-containing ionic liquid resulted in bright luminescent soft materials with the molar ratio of europium/ionic liquid (IL)/ligand being 1:3:1 that exhibit bright red light under UV lamp. The luminescent properties such as emission features and lifetime of $^5D_0$ $Eu^{3+}$ excited level are dependent on the organic ligands. The materials were characterized by FT-IR and luminescence spectroscopy. The data shows that at least parts of the ILs (carboxylic acid) are replaced with ${\beta}$-diketone ligand rather than the formation of europium complex with the molar ratio of $Eu^{3+}$:IL: ligand being 1:3:1, while no ILs could be replaced by the heterocyclic ligand such as Bpy and Phen.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.6
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• pp.531-535
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• 2007

To invest the luminescent characteristics of red light emitting OLED device, a dual dopant system was incorporated into the emitting layer. The multiple layer OLED device structure was $ITO(1500\;{\AA})/HIL(200\;{\AA})/a-NPD(600\;{\AA})/EML(300\;{\AA})/Alq_3(200\;{\AA})/LiF(7\;{\AA})/Al(1800\;{\AA})$. The concentrations of the rubrene dopant were tested at 0 vol.%, 3 vol.%, 6 vol.% and 9 vol.%. The maximum device efficiency and life time were obtained at the rubrene dopant concentration of 6 vol.%. Emission spectrum and color coordinate of devices showed no relationship with rubrene dopant concentration. Experiment results show that rubrene dopant absorbs energy from $Alq_3$ host and transfer it to RD1 dopant acting as an energy intermediate and influencing the device efficiency, finally the red light is emitted from the RD1 dopant.

• Journal of Integrative Natural Science
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• v.14 no.4
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• pp.147-154
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• 2021

A luminescent porous silicon sensor, whose surface was passivated with organic molecule via hydrosilylation under various conditions, has been researched to measure the photoluminescence (PL) stability of porous silicon (PSi). Photoluminescent PSi were synthesized by an electrochemical etching of n-type silicon wafer under the illumination with a 300 W tungsten filament bulb during the etching process. The PL of PSi displayed at 650 nm, which is due to the quantum confinement of silicon quantum dots in the PSi. To stabilized the photoluminescence of PSi, the hydrosilylation of PSi with silole molecule containg vinyl group was performed. Surface morphologies of fresh PSi and surface-modified PSi were obtained with a cold FE-SEM. Optical characterization of red photoluminescent silicon quantum dots was investigated by UV-vis and fluorescence spectrometer.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.643-643
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• 2013

Recently, synthesis of low-dimensional nanostructures is gaining more importance due to their structural properties and growing potential applications. On the other hand, luminescent materials doped with rare earth ions have drawn immense attention. The commercial phosphors are based on many host materials. Among them, tungstates are being currently investigated by many research groups owing to a wide range of applications. Tungstates are formed by different metal cations (e.g., SrWO4, Na2WO4, NiWO4, Cr2WO6, and ZrW2O8) and their structure depends on the size of the metal cation. Tungstates with large bivalent cations (${\gg}0.1\;nm$) have the scheelite structure and the wolframite structure with smaller ions (＜0.1 nm). Strontium tungstate has the scheelite structure which is tetragonal with space group I41/a. The luminescent properties of the tungstate have been extensively explored in application fields such as sensors, detectors, lasers, photoluminiscent devices, photo catalysts, etc. In this work, we synthesized SrWO4 phosphors with different Eu3+ concentrations by using a facile route. The morphology was analyzed by using a field-emission scanning electron microscope, which exhibits the spherical shape. Transmission electron microscope image revealed the spheres composed of nanoparticles. X-ray diffraction patterns confirmed their tetragonal shape. The photoluminescence excitation and emission spectra were analyzed by varying the Eu3+ concentration, which shows a dominant red emission.

• Journal of Powder Materials
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• v.16 no.3
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• pp.203-208
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• 2009

$Y_2O_3$:Eu red phosphor was prepared by microwave synthesis. The crystal phase, particle morphology, and luminescent properties were characterized by XRD, SEM, and spectrofluorometer, respectively. The prepared $Y_2O_3$:Eu particles had good crystallinity and strong red emission under ultravioletet excitation. The crystallite size increased with calcination temperature and satuarated at $1200^{\circ}C$. The primary particle size initially formed was varied from 30 to 450 nm with microwave-irradiation (MI) time. It was found that the emission intensity of $Y_2O_3$:Eu phosphor strongly depends on the MI time. In terms of the emission intensity, it was recommended that the MI time should be less than 15 min. The emission intensity of $Y_2O_3$:Eu phosphor prepared by microwave syntehsis strongly depended on the crystallite size of which an optimal size range was 50-60 nm.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.3
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• pp.258-263
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• 2002

We present a new toed phosphor, $Gd_{2-x-y}Li_xEu_yO_3$ with superior luminescent Properties compared to the commercially available red phosphor $Y_2O_3:Eu^{3+}$. The phosphor, with a diameter of about $2\mu\textrm{m}$, consists of the psedospherical particles in a regular array. The photoluminescence measurements as a function of the laser power and the Eu mole fraction were performed at zoom temperature The luminescence intensity linearly increases as both the laser power and the Eu mole fraction Increase. As for the dependence on cathodoluminescence, the incorporation of Eu and Li ions into $Gd_2O_3$ lattice brings about an increase in luminescent efficiency. The highest emission intensity for the phosphor occurs at the applied voltage of 500 V, its value is larger than that of $Y_2O_3:Eu^{3+}$ powder by 70%.

• Korean Journal of Materials Research
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• v.15 no.8
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• pp.548-553
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• 2005

Trivalent cerium$(Ce^{3+})$ activated YAG (yttrium aluminum garnet, $Y_3Al_5O_{12})$) thin films phosphor were deposited on quartz glass substrates by rf magnetron sputtering. The effects of sputtering parameters, annealing atmosphere, and substrates on growing behaviors and luminescent properties were investigated. The sputtering parameters were $O_2/(Ar+O_2)$ gas ratio, rf power, and deposition time. XRD (X-ray diffractometery) spectra exhibited that as-deposited films were amorphous, while they were transformed to the crystalline phases by post-annealing. The crystallinity and the atomic ratio strongly depended on the sputtering gas ratio $O_2/(Ar+O_2)$. High quality YAG:Ce thin films could be obtained at the gas ratio of $50\%$ oxygen. After annealing process, PL (Photoluminescence) spectra excited at 450nm showed a yellow single band at 550nm. The films deposited at the sputtering gas ratio of 50% oxygen exhibited the highest PL intensity.

• Journal of the Optical Society of Korea
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• v.18 no.1
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• pp.45-49
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• 2014

Well-crystallized $BaSi_2O_5:Eu^{2+}$ phosphor films were synthesized by heat treatment of spin-coated BaO:Eu on $SiO_2$ glass. We investigated luminescence-structure properties of these phosphor films as a function of heat-treatment temperature. From x-ray diffraction patterns, our $BaSi_2O_5:Eu^{2+}$ phosphor films revealed that (111)- and (204)-crystal planes of $BaSi_2O_5$ crystal were dominantly increased with an increase of heat-treatment temperature. Photoluminescence intensities of $BaSi_2O_5:Eu^{2+}$ phosphor films were increased with amount of these crystal planes. It can be explained that $Eu^{2+}$ ions were stably occupied at specific crystal orientation of $BaSi_2O_5$ crystal, enhancing the luminescent intensities of $BaSi_2O_5:Eu^{2+}$ phosphor films. In addition, our $BaSi_2O_5:Eu^{2+}$ phosphor films had transmittance of 70% at 510 nm,.due to the dense morphology and specific crystallinity of $BaSi_2O_5:Eu^{2+}$ phosphor films.