• 한국재료학회지
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• 제18권2호
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• pp.77-83
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• 2008

Green-emitting $Ba_{1.468}Sr_{0.5}SiO_4\;:\;Eu_{0.012},\;Y_{0.02}$ phosphor powders under long-wavelength ultraviolet light were prepared via high-temperature flame spray pyrolysis from spray solutions with and without $NH_4Cl$ flux. The effects of the temperature of the diffusion flame and the $NH_4Cl$ flux on the morphologies, crystal structures and photoluminescence intensities of the $Ba_{1.468}Sr_{0.5}SiO_4\;:\;Eu_{0.012},\;Y_{0.02}$ phosphor powders were investigated. The phosphor powders obtained from the spray solution with the $NH_4Cl$ flux had higher photoluminescence intensities compared to phosphor powders obtained from the spray solution without the flux. The photoluminescence intensity of the phosphor powders obtained from the spray solution without the flux decreased as the flow rate of the fuel gas increased. On the other hand, the photoluminescence intensity of the phosphor powders obtained from the spray solution with the flux increased as the flow rate of the fuel gas increased. The difference of in the phase purity and morphology of the powders affected the photoluminescence intensities of the phosphor powders.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.272-275
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• 2009

A new green phosphor, ($Mg_{1-x-yZnx)$)$Al_2O_4:Mn^{2+}{_y}$ (0 x 0.6, 0.001 y 0.01), was synthesized by a flux-assisted solid reaction and its vacuum ultraviolet (VUV) excitation and emission characteristics were examined in this study. The chromaticity and peak intensity of the $(Mg_{0.79}Zn_{0.2})Al_2O_4:Mn^{2+}{_{0.01}}$ (x = 0.177, y = 0.745) phosphor were found to be more desirable than that of $Zn_2SiO_4:Mn^{2+}$ (x = 0.216, y = 0.72) phosphor as a green primary color.

• 한국재료학회지
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• 제15권8호
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• pp.496-502
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• 2005

Green-light emitting $BaMgAl_{10}O_{19}:Mn^{2+}$ (BAM:Mn) phosphor particles were prepared by spray Pyrolysis. The effect of reactor temperature and flow rate of carrier gas in the spray Pyrolysis on the morphology, crystallinity and photoluminescence characteristics under vacuum ultraviolet were investigated. The morphology of the as-Prepared Particles obtained by spray Pyrolysis had spherical shape and non-aggregation characteristics regardless of the reactor temperature. The spherical shape of the as-prepared Particles obtained by spray pyrolysis at low temperature disappeared after Post-treatment. On the other hand the as-Prepared Particles obtained by spray Pyrolysis at $1600^{\circ}C$ maintained spherical shape and non-aggregation characteristics after post-treatment at $1400^{\circ}C$ for 3 h under reducing atmosphere. The BAM:Mn Phosphor Particles Prepared by spray Pyrolysis at different reactor temperatures had pure crystal structure and high photoluminescence intensities under vacuum ultraviolet after post-treatment. BAM:Mn phosphor particles prepared by spray Pyrolysis at low How rate of carrier gas had complete spherical shape and filed morphology and high photoluminescence intensity after post-treatment under reducing atmosphere.

• KIEE International Transactions on Electrophysics and Applications
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• 제11C권3호
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• pp.53-57
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• 2001

The organic light-emitting devices (OLEDs) based on fluorescence have low efficiency due to the requirement of spin-symmetry conservation. By using the phosphorescent material, internal quantum efficiency can reach 100%, compared with 25% in the case of the fluorescent material. Thus, phosphorescent OLEDs have recently been extensively studied and shown higher internal quantum efficiency than the conventional OLEDs. In this study, we investigated the characteristics of the phosphorescent OLEDs with the green emitting phosphor, $Ir(ppy)_3$ (tris(2-phenylpyridine)iridium). The device with a structure of ITO/TPD$Ir(ppy)_3$ doped in BCP/BCP/$Alq_3$/Li:Al/Al was fabricated, and its electrical and optical characteristics were studied. By changing the doping concentration of $Ir(ppy)_3$, we fabricated several devices and investigated their characteristics.

• 한국세라믹학회지
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• 제52권4호
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• pp.229-233
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• 2015

Currently, the majority of commercial white LEDs are phosphor converted LEDs made of a blue-emitting chip and YAG yellow phosphor dispersed in organic silicone. However, silicone in high-power devices results in long-term performance problems such as reacting with water, color transition, and shrinkage by heat. Additionally, yellow phosphor is not applicable to warm white LEDs that require a low CCT and high CRI. To solve these problems, mixing of green phosphor, red phosphor and glass, which are stable in high temperatures, is common a production method for high-power warm white LEDs. In this study, we fabricated conversion lenses with LUAG green phosphor, SCASN red phosphor and low-softening point glass for high-power warm white LEDs. Conversion lenses can be well controlled through the phosphor content and heat treatment temperature. Therefore, when the green phosphor content was increased, the CRI and luminance efficiency gradually intensified. Moreover, using high heat treatment temperatures, the fabricated conversion lenses had a high CRI and low luminance efficiency. Thus, the fabricated conversion lenses with green and red phosphor below 90 wt% and 10 wt% with a sintering temperature of $500^{\circ}C$ had the best optical properties. The measured values for the CCT, CRI and luminance efficiency were 3200 K, 80, and 85 lm/w.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권2호
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• pp.1529-1530
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• 2007

The manganese co-doped $Ca_8Mg_1(SiO_4)_4Cl_2:Eu^{2+}$,$Mn^{2+}$ phosphor was synthesized by solid-state reaction and its photoluminescence characteristics were investigated. The synthesized phosphor show two emission spetrums: green band of 512nm and yellow band of 550nm. White light-emitting diodes (LEDs) were fabricated through combination of a 405nm-emitting InGaN chip and a synthesis phosphor in a single package. Under 20mA current, its CIE chromaticity coordinates are x=0.40 and y=0.45 and a color temperature of 4053K.

• Transactions on Electrical and Electronic Materials
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• 제8권3호
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• pp.121-124
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• 2007

The $Zn_2SiO_4:Mn$ phosphors were prepared using polymer matrix technique in order to improve the performance of green emitting phosphors for plasma display panel(PDP). $Zn_2SiO_4:Mn$ phosphor exhibits a strong green emission around 520-530 nm. The emission intensity and particle size of powders were controlled by sintering temperature and raw material composition. The zinc silicate $Zn_2SiO_4:Mn$ single phase were obtained at lower temperature than prepared by solid-state reaction method. PL luminance of $Zn_2SiO_4:Mn$ phosphor was similar to the commercial material.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2002년도 International Meeting on Information Display
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• pp.807-810
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• 2002

$GdPO_4$:Tb phosphor particles with spherical shape and high photoluminescence were prepared by spray pyrolysis. The brightness of prepared $GdPO_4$:Tb under the vacuum ultraviolet(VUV) illumination was comparable with that of the commercial $Zn_2SiO_4$:Mn phosphor particles. The photoluminescence spectra of $GdPO_4$:Tb phosphor particles had maximum peak at 547 nm, and the sharp peaks at 480 nm, 580 nm, and 620 nm. The spherical morphology of prepared $GdPO_4$:Tb particles was completely maintained even after the posttreatment up to 1100 $^{\circ}C$. When the posttreatment temperature was over 1100 $^{\circ}C$, the particles did not have the spherical shape anymore. The average particle size of $GdPO_4$:Tb phosphor particles prepared by using $(NH_4)_2HPO_4$ was changed from 0.5 to 1.9 ${\mu}m$ and its effect on the PL intensity was investigated. It was found that the optimized $GdPO_4$:Tb particles have a good excitation spectrum comparable to that of the commercial $Zn_2SiO_4$:Mn phosphor particles under the VUV illumination from 140 to 220 nm. We concluded that the $GdPO_4$:Tb phosphor particles with spherical shape prepared by spray pyrolysis is a promising candidate for a green-emitting PDP phosphor.

• 대한화학회지
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• 제48권4호
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• pp.371-378
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• 2004

기존의 $SrGa_2S_4:Eu^{2+}$ 녹색 발광 형광체는 주로 CRT (Cathode Ray Tube)용이나 FED (Field Emission Display), 그리고 EL (Electroluminescence)용 발광소자로 많이 연구되어졌다. 현재는 장파장 영역의 여기 특성을 이용한 LED (Light Emitting Diode)용 형광체로 주목 되어지고 있다. $SrGa_2S_4:Eu^{2+}$ 형광체의 일반적 합성 방법은 Flux를 이용하여 인체에 유해한 $H_2S$나 $CS_2$ 기체를 사용할 뿐만 아니라 높은 합성온도, 긴 반응시간 및 공정이 복잡한 단점을 지니고 있다. 따라서 본 실험은 황화물계 원료인 SrS, $Ga_2S_3$ 그리고 EuS를 출발 물질로 하여 $H_2S$ 기체를 사용하지 않고 혼합 기체$(5% H_2/95% N_2)$를 사용해 환원 분위기 하에서 $SrGa_2S_4:Eu^{2+}$을 합성하였다. 그리고 다양한 합성 조건과 LED용으로 사용되기 위해 수세처리와 Sieving 과정을 거친 형광체의 발광특성을 검토하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.178-181
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• 2001

The organic light-emitting devices (OLEDs) based on fluorescence have low efficiencies due to the requirement of spin-symmetry conservation. By using the phosphorescent material, the internal quantum efficiency can reach 100 %, compared to 25 % in the case of the fluorescent material. Thus, the phosphorescent OLEDs have recently been extensively studied and showed higher internal quantum efficiencies then the conventional OLEDs. In this study, we investigated the characteristics of the phosphorescent OLEDs, with the green emitting phosphor, Ir(ppy)$_3$ (tris(2-phenylpyridine)iridium). The devices with a structure of ITO/TPD/Ir(PPy)$_3$ doped in the host material/BCP/Alq$_3$/Li:Al/Al were fabricated, and its electrical and optical characteristics were studied. By changing the doping concentration of Ir(PPy)$_3$ and the host materials, we fabricated several devices and investigated the device characteristics.