• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.302.2-302.2
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• 2014

유기발광소자는 고휘도, 넓은 시야각, 빠른 응답속도, 높은 색재현성, 좋은 유연성의 소자 특성 때문에 디스플레이 제품에 많이 응용되고 연구가 활발하게 진행되고 있다. 최근에 저소비전력, 고휘도, 소형화 및 장수명의 장점을 가진 유기발광소자의 상용화가 진행되면서 차세대 디스플레이소자로서 관심을 끌게 되었다. 최근에는 고효율의 장점을 가지는 무기 형광체와 양자점을 이용한 백색 유기발광 소자에 대한 연구가 활발하게 진행되고 있으나 색 안정성이 좋지 않은 문제점이 있다. 본 연구에서는 적색 빛을 방출하는 CdSe/ZnS 양자점과 녹색 빛을 방출하는 YAG:Ce3+ 무기 형광체를 포함하는 polymethylmethacrylate (PMMA)를 색변환층으로 이용하여 청색 유기발광소자에 결합한 백색 유기발광소자를 제작하였다. CdSe/ZnS 양자점과 YAG:Ce3+ 무기 형광체의 광흡수대역은 250 nm에서 500 nm이므로 470 nm의 청색 발광소자의 청색 빛을 흡수하여 색변환층에서 재 발광할 때 색 변환 결과를 무기 형광체와 양자점의 여러 가지 혼합 비율에 따라 전계발광 스펙트럼을 통해 관측하였다. 또한, 전압을 12 V 에서 16 V까지 변화하였을 때 색좌표가 (0.32, 0.34)에서 (0.30, 0.33)으로 적은 변화를 보여 높은 색안정성을 확인 할 수 있었다. 이 연구 결과는 양자점과 무기 형광체를 혼합한 색변환층을 이용한 백색 유기발광소자의 색 변환 효율 증가와 색안정성에 대한 기초자료로 활용할 수 있다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.644-646
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• 2004

We have investigated luminescence properties of Ln-SiAlON materials doped with $Ce^{3+}$. Low-energy 4f${\leftrightarrow}$5d transitions were observed as compared to the luminescence of this ion doped in oxidic host-lattices.$^1$ Ce-doped Y-a-SiAlON show bright long wavelength luminescence with high absorption for 305 and 455nm excitation. In our experiment, the sintering temperature of this material(1400$^{\circ}C$) was lower than that of normal sintering temperature (1700$^{\circ}C$). However, Single phase of SiAlON was not composed we observed the YAG phase.

• 마이크로전자및패키징학회지
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• 제7권2호
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• pp.43-46
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• 2000

Nd:YAG laser of 355 nm wavelength, which amounts to 3.5 eV, produced by a harmonic generator was used to create Ag metallic particles as seeds for nucleation in photosensitive glass containing $Ag^+$ and $Ce^{3+}$ . The pulse widths and frequency of the laser were 8ns and 10 Hz, respectively. For crystalline growth, heat-treatment following laser irradiation was carried out at $570^{\circ}C$ for 1h. Then, the $LiAlSi_3O^8$ crystal phase appeared in the laser irradiated lithium aluminum silicate glass. We present the effect of laser-induced nucleation compared with spontaneous nucleation by heat treatment fur crystallization in the glass.

• 한국정보통신학회논문지
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• 제6권7호
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• pp.1095-1099
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• 2002

본 논문은 1064 m의 Q-스위칭 Nd:YAG로 펌핑된 단일통과 라만레이저에서 nano-초의 스토크스 펄스발생에 관한 연구이며, 라만 매질로는 GeO2로 도핑된 grad index형 다중모드 파이버 220 m를 사용하였다. 실험 결과에서 펌핑 에너지의 변화에 따라 1.5∼2.7 nano 초의 펄스폭을 갖는 스토크스 펄스 트래인 싱분이 효율적으로 발생함을 알 수 있었다.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2000년도 Proceedings of 5th International Joint Symposium on Microeletronics and Packaging
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• pp.112-117
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• 2000

Nd:YAG laser of 355nm wavelength, which amounts to 3.5eV, produced by a harmonic generator was used to create Ag metallic particles as seeds for nucleation in photosensitive glass containing Ag+ and Ce3+. The pulse widths and frequency of the laser were 8ns and 10Hz, respectively. For crystalline growth, heat-treatment following laser irradiation was carried out at $570^{\circ}C$ fur 1h. Then, the LiAlSi3O8. crystal phase appeared in the laser irradiated lithium aluminum silicate glass. We present the effect of laser-induced nucleation compared with spontaneous nucleation by heat treatment for crystallization in the glass.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.79-82
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• 2009

This work presents a novel lighting technology based on a YAG:$Ce^{3+}$ phosphor converter with micro line lenticular structure, to accompany an array of bare LED chips on a board. This technology is especially effective in TFT-LCD backlight applications as it offers the advantages of high light radiation efficiency, low color deviation, uniform luminance distribution and compact backlight thickness. Additionally, the proposed configuration is low-cost, can be manufactured quickly, and can be mass-produced economically.

• 한국재료학회지
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• 제23권1호
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• pp.31-34
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• 2013

Trivalent cerium-ion-doped $Y_3(Al,\;Ga)_5O_{12}$ nanoparticle phosphor nanoparticles were synthesized using the reverse micelle process. The Ce doped $Y_3(Al,\;Ga)_5O_{12}$ particles were obtained from nitrate solutions dispersed in the nanosized aqueous domains of a micro emulsion consisting of cyclohexane as the oil phase and poly(oxyethylene) nonylphenyl ether (Igepal CO-520) as the non-ionic surfactant. The crystallinity, morphology, and thermal properties of the synthesized $Y_3(Al,\;Ga)_5O_{12}:Ce^{3+}$ powders were characterized by thermogravimetry-differential thermal analysis (TGA-DTA), X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), and transmission electron microscopy. The crystallinity, morphology, and chemical states of the ions were characterized; the photo-physical properties were studied by taking absorption, excitation, and emission spectra for various concentrations of cerium. The photo physical properties of the synthesized $Y_3(Al,\;Ga)_5O_{12}:Ce^{3+}$ powders were studied by taking the excitation and emission spectra for various concentrations of cerium. The average particle size of the synthesized YAG powders was below $1{\mu}m$. Excitation spectra of the $Y_3Al_5O_{12}$ and $Y_3Al_{3.97}Ga_{1.03}O_{12}$ samples were 485 nm and 475 nm, respectively. The emission spectra of the $Y_3Al_5O_{12}$ and $Y_3Al_{3.97}Ga_{1.03}O_{12}$ were around 560 nm and 545 nm, respectively. $Y_3(Al,\;Ga)_5O_{12}:Ce^{3+}$ is a red-emitting phosphor; it has a high efficiency for operation under near UV excitation, and may be a promising candidate for photonic applications.

• 센서학회지
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• 제25권5호
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• pp.333-336
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• 2016

In this study, a beta monitoring sensor was developed as a part of basic research for quantitative beta monitoring underwater, and its performance was evaluated using a calibration source. A beta detection sensor was manufactured by using SiPM(silicon photomultiplier) and $CaF_2$:Eu, YAG:Ce, YAP:Ce scintillator. A large-area light guide was introduced to improve beta-ray detection efficiency. As calibration sources, the Beta source $^{90}Sr$, which is the main fission product of a nuclear accident, and the gamma source $^{137}Cs$ are used. In the performance evaluation, it is confirmed that scintillator $CaF_2:Eu$ gives the highest beta-ray detection response. Compared to gamma ray, beta-ray detection responsivity and detection efficiency are verified. Therefore, this study is expected to contribute to basic research in the development of an underwater beta-ray monitoring system.

• 한국세라믹학회지
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• 제53권2호
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• pp.258-262
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• 2016

The effect of zirconium dioxide ($ZrO_2$) on the properties of color conversion glasses was examined in the $BaO-ZnO-B_2O_3-SiO_2$ system. The difference in refractive index between glass and phosphor affect the optical properties of the color conversion glass because of light scattering. Reducing the difference in refractive index is a method to improve the luminous efficacy of color conversion glasses. As a reference, a type of glass that contains 25 mol% of each component was used. To increase the refractive index of the glass samples, the BaO content was increased from 25 to 40 mol%, and $ZrO_2$ was added at levels of 1, 3, and 5 mol%. Color conversion glasses were prepared by sintering a mixture of glass and 5 wt% $YAG:Ce^{3+}$ phosphor. As a result, the refractive index of the glass was found to be dependent on the BaO and $ZrO_2$ contents in the BaO-ZnO-$B_2O_3-SiO_2$ system. As the BaO and $ZrO_2$ contents were increased, the luminous efficacy of the color conversion glass was improved because the refractive index difference between the glass and the $YAG:Ce^{3+}$ phosphor decreased.

• Nuclear Engineering and Technology
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• 제54권7호
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• pp.2579-2585
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• 2022

Ceramics of quaternary garnets (Gd,Y)₃Al₂Ga₃O₁₂ doped with Ce, Tb have been fabricated and evaluated as prospective materials for indirect energy converters of α-and β-voltaic. Samples were characterized at excitation with an X-ray source and an intense 150 keV electron beam and showed good temperature stability of their emission and tolerance to irradiation. The role of X-rays accompanied the α-particle emitting in the increase of the conversion efficiency is clarified. The garnet-type structure of the matrix in the developed materials allows the production of quality crystalline mass with a light yield exceeding that of the commonly used YAG: Ce scintillator by a factor of two times.