• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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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.

• Bulletin of the Korean Chemical Society
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• v.28 no.12
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• pp.2477-2480
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• 2007

MgAl2O4:Eu3+ red-light emitting powder phosphor was prepared at temperature as low as 500 oC within a few minutes by using the combustion route. The prepared powder was characterized by X-ray diffraction, scanning electron microscopy and Fourier-transform infrared spectrometry. The luminescence of Eu3+-activated MgAl2O4 shows a strong red emission dominant peak around 611 nm, which can be attributed to the 5D0-7F2 transition of Eu3+ ions from the synthesized phosphor particles under excitation (394 nm). Electron paramagnetic resonance (EPR) measurements at the X-band showed that no signal could be attributed to Eu2+ ions in MgAl2O4.

• Journal of the Optical Society of Korea
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• v.11 no.2
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• pp.67-70
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• 2007

A Wide Color Gamut Backlight system was studied using a three-band white Light-Emitting Diode. A three-band white light-emitting diode (LED) was fabricated using an InGaN-based blue LED chip that emits 445-nm blue peak, and a green phosphor and red phosphor that emit 535-nm green and 621-nm red peak emissions, respectively, when excited by 450-nm blue light. Using for this three-band white LED, wide color gamut backlight unit (BLU) was attained. The luminance of BLU and CIE 1931 chromaticity coordinates was $1,700Cd/m^2$ and (0.337, 0.346). Color filter matching simulations for this configuration show that the three-band white LED backlight can be enhanced by up to 16% over conventional white LED backlight color gamut.

• Korean Journal of Materials Research
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• v.27 no.6
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• pp.312-317
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• 2017

In the construction of a white LED, the region of the red emission is a very important factor. Red light emitting materials play an important role in improving the color rendering index of commercial lighting. These materials also increase the color gamut of display products. Therefore, the development of novel phosphors with red emission and the study of color tuning are actively underway to improve product quality. In the present study, heuristic algorithms were used to search for phosphors capable of increasing the color rendering index and color gamut. Using a heuristic algorithm, the phosphors that were identified were $SrGe_4O_9:Mn^{4+}$ and $BaGe_4O_9:Mn^{4+}$. Emission spectra study confirmed that these phosphors emit light in the deep red wavelength region, which can fulfill the requirement for the improvement in color rendering index and color gamut for a white LED.

• Journal of Institute of Convergence Technology
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• v.4 no.1
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• pp.21-27
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• 2014

White LEDs (light-emitting diodes) are promising new-generation light sources which can replace conventional lamps due to their high reliability, low energy consumption and eco-friendly effects. This paper briefly reviews recent progress of oxy/nitride host phosphor and quantum dot materials with broad excitation band characteristics for phosphor-converted white LEDs. Among oxy/nitride host materials, $M_2Si_5N_8:Eu^{2+}$, $MAlSiN_3:Eu^{2+}$ M-SiON(M=Ca, Sr, Ba), ${\alpha}/{\beta}-SiAlON:Eu^{2+}$ are excellent phosphors for white LED using blue-emitting chip. They have very broad excitation bands in the range of 440-460 nm and exhibit emission from green to red. In this paper, In this review we focus on recent developments in the crystal structure, luminescence and applications of the oxy/nitride phosphors for white LEDs. In addition, the application prospects and current trends of research and development of quantum dot phosphors are also discussed.

• Korean Journal of Materials Research
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• v.21 no.1
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• pp.46-49
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• 2011

Bi co-doped ZnS:Mn,Bi yellow phosphors for white light emitting diodes were prepared by the conventional solidstate reaction method. The optical and structural properties of ZnS:Mn,Bi phosphors were investigated by x-ray diffraction, scanning electro microscopy and photoluminescence. ZnS:Mn,Bi phosphors showed XRD patterns of hexagonal structure. The photoluminescence of ZnS:Mn,Bi phosphors showed spectra extending from 480 to 700 nm, peaking at 580 nm. The photoluminescence of 580 nm in the ZnS:Mn,Bi phosphors was associated with the 4T1 ${\rightarrow}$ 6A1 transition of the Mn2+ ions. The highest photoluminescent intensity of the phosphors under 405 nm and 450 nm excitation was obtained at Bi concentration of 7mol%. The optimum mixing conditions with epoxy and yellow phosphor for white light emitting diodes were observed in a ratio of epoxy:yellow phosphor of 1:3.5. The CIE chromaticity of the white LED at the 1:3.5 ratio was X = 0.3454 and Y = 0.2449.

• Transactions of Materials Processing
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• v.24 no.2
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• pp.95-100
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• 2015

It was confirmed that when phosphor slurry is formed in the cavity of an elastic mold, the pressure distribution of the phosphor slurry varies as a function of the major squeegee parameters (squeegee angle, squeegee velocity, and the viscosity of the phosphor slurry). The higher the slurry viscosity, the faster the squeegee velocity, and the smaller the squeegee angle, the higher the filling completeness of the phosphor slurry. The optimum conditions for complete filling of the phosphor slurry were found when the squeegee angle was between 30 to 45 degrees, squeegee velocity at 40 to 70mm/sec, and the viscosity of the phosphor slurry composite was at 6,556 cps (i.e. phosphor content around 50 wt. %).

• Journal of the Korean Ceramic Society
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• v.43 no.3 s.286
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• pp.169-172
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• 2006

We have synthesized a $Eu^{2+}-activated\;{(Sr,Ba)}_2SiO_4$ yellow phosphor and investigated the development of blue LEDs by combining the phosphor with a InGaN blue LED chip (${\lambda}_{em}$=405 nm). The InGaN-based ${(Sr,Ba)}_2SiO_{4}:Eu$ LED lamp shows two bands at 405 nm and 550 nm. The 405 nm emission band is due to a radiative recombination from a InGaN active layer. This 405 nm emission was used as an optical transition of the ${(Sr,Ba)}_2SiO_{4}:Eu$ phosphor. The 550 nm emission band is ascribed to a radiative recombination of $Eu^{2+}$ impurity ions in the ${(Sr,Ba)}_2SiO_4$ host matrix. In the preparation of UV Yellow LED Lamp with ${(Sr,Ba)}_2SiO_{4}:Eu$ yellow phosphor, the highest luminescence efficiency was obtained at the epoxy-to-yellow phosphor ratio of 1:0.45. At this ratio, the CIE chromaticity was x=0.4097 and y=0.5488.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.1062-1065
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• 2004

The importance of display is becoming increasingly important due to the development of information and industry where it leads to diverse and abundant information in today's society. The demand and application range for FPD(Flat Panel Display), specifically represented by LCD(Liquid Crystal Display) and PDP(Plasma Display Panel), have been rapidly growing for its outstanding performance and convenience amongst many other forms of display. The current focus has been on OLED(Organic Light Emitting Diode) in the mobile form, which has just entered into mass production amid the different types of FPD. Many studies are being conducted in regards to device, vacuum evaporation, encapsulation, and drive circuits with the development of device as a matter of the utmost concern. This study develops a new type of light-emitting materials by synthesizing medical polymer organic chitosan and phosphor material CuS. Chitosan itself satisfies the Pool-Frenkel Effect, an I-V specific curve, with a thin film under $20{mu}m$, and demonstrates production possibility for a living body sensors solely with the thin film. Furthermore, it enables production possibility for EML of organic EL device(Emitting Layer) with liquid Green light emitting and Blue light emitting as a result of synthesis with phosphor material.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.7
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• pp.567-574
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• 2013

An optical model is proposed in the white LED using phosphor and LED chip. In this paper a new model that describes the absorption rate and quantum efficiency with increasing the mixing ratio of phosphor in silicone, and the allotment of the phosphor absorption optical power in the several phosphor mixing in the silicone. Single phosphor in silicone from the optical measurement data before and after molding, the solution to get the blue optical power and the phosphor emission optical power is proposed. By these solution the absorption rate and the quantum efficiency was obtained. The model with single phosphor mixing in the silicone the validity was confirmed.