• Journal of the Korean Crystal Growth and Crystal Technology
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• v.25 no.1
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• pp.35-38
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• 2015

LEDs are considered to be an alternative for enhancement of energy efficiency, applied for numerous areas such as display, automotive headlight not only lights. Yellow phosphor is generally utilized with blue LEDs to generate WLED, $Y_3Al_{5}O_{12}:Ce^{3+}$ is typically used as the yellow phosphor. The phosphor, mixed with epoxy resin, has been used by being spread and hardened on the blue LED chip. This paste-based packaging gives rise to problems of degradation of phosphor by heat and decrease of luminous efficiency. Although phosphor plate is used instead of the epoxy-phosphor mixture to solve these problems, loss of luminous efficacy by total internal reflection inside the plate also should be solved. In this study, we coated the side of the plate with silver as one of the solution.

• Journal of the Korean institute of surface engineering
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• v.49 no.1
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• pp.81-86
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• 2016

$Eu^{3+}$-doped $MgMoO_4$ phosphor thin films were deposited on quartz substrates by radio frequency magnetron sputtering with changing various growth temperatures. The effects of growth temperature on the structure, transmittance, optical band gap, and luminescence of the phosphor thin films were characterized. All the phosphor thin films, irrespective of growth temperature, showed a monoclinic structure with a main (220) diffraction peak. The thin film deposited at a growth temperature of $400^{\circ}C$ indicated an average transmittance of 90% in the wavelength range of 500 ~ 1100 nm and band gap energy of 4.81 eV. The excitation spectra of the phosphor thin films consisted of a broad charge transfer band peaked at 284 nm in the range of 230 ~ 330 nm and two weak peaks located at 368 and 461 nm, respectively. The emission spectra under ultraviolet excitation at 284 nm exhibited a sharp emission peak at 614 nm and several weak bands. All the phosphor thin films showed high asymmetry ratio values, indicating that $Eu^{3+}$ ions incorporated into the host lattice occupied at the non-inversion symmetry sites. The results suggest that the growth temperature plays an important role in growing high-quality phosphor thin films.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.594-597
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• 1999

The new green and red phosphors for PDP application activated by T $b^{3+}$ and E $u^{3+}$ were synthesized, and their photoluminance properties were investigated. It was found that the brightness of $Al_3$Gd $B_4$ $O_{12}$ :T $b^{3+}$ green phosphor under 147nm VUV irradiation was higher than that of commercial Z $n_2$ $SiO_4$:M $n^{2+}$ phosphor. But the emitting intensity of A1$_3$Gd $B_4$ $O^{12}$ :E $u^{3+}$ red phosphor was inferior to the commercial (Y,Gd)B $O_3$:E $u^{3+}$. $Al_3$Gd $B_4$ $O_{12}$ Phosphor had a strong excitation band at 160nm associated with the host absorption, and also the photoluminance excitation intensity of $Al_3$Gd $B_4$ $O_{12}$ :T $b^{3+}$ was higher than that of Z $n_2$ $SiO_4$:M $n^{2+}$, but the intensity of $Al_3$Gd $B_4$ $O_{12}$ :E $u^{3+}$ phosphor was smaller than (Y,Gd)B $O_3$:E $u^{3+}$ phosphor In the VUV range. C $e^{3+}$ co-doping in A1$_3$Gd $B_4$ $O^{12}$ :E $u^{3+}$ and substitution of $Al^{3+}$ by G $a^{3+}$ A1$_3$Gd $B_4$ $O^{12}$ :E $u^{3+}$ phosphor were tried, but they did not improved the optical property .d the optical property .ty .

• Korean Journal of Materials Research
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• v.29 no.2
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• pp.116-120
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• 2019

We prepared $Y_3Al_5O_{12};Ce^{3+},Pr3^{+}$ transparent ceramic phosphor using a solid state reaction method. By XRD pattern analysis and SEM measurement, our phosphors reveal an Ia-3d(230) space group of cubic structure, and the transparent ceramic phosphor has a polycrystal state with some internal cracks and pores. In the Raman scattering measurement with an increasing temperature, lattice vibrations of the transparent ceramic phosphor decrease due to its more perfect crystal structure and symmetry. Thus, low phonon generation is possible at high temperature. Optical properties of the transparent ceramic phosphor have broader excitation spectra due to a large internal reflection. There is a wide emission band from the green to yellow region, and the red color emission between 610 nm and 640 nm is also observed. The red-yellow phosphor optical characteristics enable a high Color Rendering Index (CRI) in combination with blue emitting LED or LD. Due to its good thermal properties of low phonon generation at high temperature and a wide emission range for high CRI characteristics, the transparent ceramic phosphor is shown to be a good candidate for high power solid state white lighting.

• Proceedings of the Korean Ceranic Society Conference
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• 2000.10a
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• pp.56.1-56
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• 2000

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.10
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• pp.704-709
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• 1999

The optical properties such as luminance and color coordinates for phosphor layer were studied with applied voltage and gas pressure, Xe mixing ratio, frequency using He and Xe mixing gas in chamber like AC PDP. The luminance of red phosphor layer at constant pressure(300Toor) is increased with increasing voltage, but color purity is not varied. The luminance of red phosphor layer at constant voltage(280V)is decreased with increasing pressure, but the color purity is not varied. But the luminance is increased with increasing Xe mixing ratio at constant pressure(200Toor). And also the color purity is improved by this process. The luminance is increased up to 40kHz, but the color purity with frequency is not varied.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.640-643
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• 2004

We have synthesized SrS:Eu red phosphor by solid state method and investigated to adopt a red phosphor for LEDs. The SrS:Eu phosphor shows broad emission band at 600nm region due to f-d energy transfer of $Eu^{2{\cdot}}$. Our results show that the SrS:Eu red phosphor exhibits the better luminescence efficiency than that of the industrially available product SrS:Eu phosphor.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1526-1528
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• 2007

In this report, Manganese doped magnesium germanate ($Mg_4GeO_2:Mn$) phosphor has been synthesized by the solid state method. Also, this phosphor was prepared by simple process under an air atmosphere for oxidation of Mn. The prepared phosphor shows a main luminescent peak at 661nm. Therefore, this phosphor is possible to be applicable to white LED lamp by GaN or InGaN chips.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1350-1352
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• 2008

Research on down conversion phosphor materials is the key for the development of solid state lighting (SSL). Especially finding alternative red phosphor for white LEDs based on blue or NUV LEDs are important research task. Under this view, we have synthesized a series of $Eu^{3+}$ substituted $La_2W_{2-x}Mo_xO_9$ (x = 0 ~ 2, insteps of 0.1) red phosphor and characterized by X-ray diffraction (XRD) and photoluminescence. XRD results reveal a phase transition from triclinic to cubic structure for $x\;{\geq}\;0$. All the compositions show broad charge transfer band due to charge transfer from oxygen to tungsten/molybdenum and red emission due to $Eu^{3+}$ ions. Select compositions show high red emission intensity compared to the commercial red phosphor under NUV/blue ray excitation. Hence, this candidate can be possible red emitting phosphors for white LEDs.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.109-112
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• 2003

In this paper, we investigated the phosphor degradation characteristics on the ultra violet ray (UV) irradiation as well as ion bombardment. We propose a novel experiment method which is related with phosphor degradation causes. The phosphor deterioration experiments were made on the UV irradiation as well as ion bombardment. To carry out the experiment and compare the results, we made up the specific experimental setup. The results show that the deterioration by ion damage is more rigorous than that by vacuum ultra violet (VUV) on the phosphor efficiency.