• Proceedings of the Polymer Society of Korea Conference
• /
• 2006.10a
• /
• pp.233-233
• /
• 2006

[ $Y_{2}O_{2}S:Eu$ ], a red phosphor, coated with silica nanoparticles or nanocomposites composed of silica nanoparticles and polymeric materials such as PMMA and PVP was prepared via sol-gel process. Samples were prepared from four different methods coded P1, P2, P3, and P4. P1 includes a conventional sol-gel process and a dip-coating method while P2 has the same procedure with P1 except that nanocomposites containing both silica nanoparticles and polymer prepared by sol-gel process were used as coating materials. In P3 method, phosphors were dispersed in a solution containing silica precursor, i.e., TEOS and then polymerization was performed to coat onto the phosphors surface while P4 followed the same procedure with P3 except that a solution containing both TEOS and organic monomer were used in preparing coating materials. Among various coating methods examined in this study, uniform coating of phosphor could be achieved by using method P4, i.e., phosphor surface coating in a solution containing hydrophobic monomer and TEOS. Furthermore, $Y_{2}O_{2}S:Eu$ red phosphor coated with nanocomposite composed of PMMA matrix and silica nanoparticles exhibited enhanced PL intensity and long-term stability.

• The Journal of the Convergence on Culture Technology
• /
• v.9 no.5
• /
• pp.523-528
• /
• 2023

The applicability as a material to improve solar cell performance was reviewed by synthesizing a phosphor that emits red wavelengths by a liquid synthesis method using a metal salt aqueous solution and a polymer medium as a starting material. An aqueous solution was prepared using nitrate of metals such as Ca, Zn, Al, and Eu, and a precursor impregnated with starch, a natural polymer, was sintered to synthesize CaZnAlO:Eu phosphor powder. The surface structure and composition analysis of the synthesized CaZnAlO:Eu phosphor powder were analyzed by scanning electron microscope(SEM) and energy-dispersed X-ray spectroscopy(EDS). The crystal structure of CaZnAlO:Eu phosphor particles was analyzed by an X-ray diffraction analyzer (XRD). As a result of measuring the photoluminescence(PL) characteristics of the phosphor, it was confirmed that a red phosphor with a light emitting wavelength of 650-780nm was successfully synthesized. According to SEM and EDS analysis, the synthesized Ca₁₄Zn₆Al_9.93O₃₅:Eu³⁺_0.07 phosphor powder has a uniform particle size, and Eu ions used as an activator are present. The synthesized CZA:Eu³⁺ phosphor can be used as a material that can increase the light absorption efficiency of the solar cell by converting ultraviolet or visible light down conversion into a wavelength in the near-infrared region.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.415.2-415.2
• /
• 2014

Cost-effective, robust devices for solid-state lighting industry that converts electricity to light revolutionize the current lighting industry. Phosphor materials used in these devices should be synthesized in a low-cost and effective method for use in WLEDs. In this presentation, the synthesis of Eu3+ ions doped BaMoO4 phosphor samples by a facile synthesis process for red component of WLEDs will be shown. The tetragonal phase of the host lattice was substantiated by the X-ray diffraction patterns. The morphological studies were carried out by using a field-emission scanning electron microscope and transmission electron microscope. These confirmed the formation of a shuttle like particles with perpendicular protrusions in the middle of the particle. The photoluminescence (PL) properties exhibited good emission with a high asymmetry ratio when excited with ultraviolet B wavelengths (~ 280-315 nm). The cathodoluminescence (CL) spectra showed similar results to the PL spectra, indicating the rich red emission. The results suggest that this phosphor is a good material as red region component in the development of tri-band UV excitation based WLEDs.

• Transactions on Electrical and Electronic Materials
• /
• v.9 no.2
• /
• pp.57-61
• /
• 2008

The $(Y,Gd)_2O_3$:Eu phosphors were synthesized using the impregnation method in order to improve the performance of red-emitting phosphors for plasma display panels. $(Y,Gd)_2O_3$:Eu phosphors, with a particle size ranging from 150 and 200 nm, exhibited a strong red emission at around 615 nm. The emission intensity and particle size of the powders were controlled by adjusting the sintering temperature and raw material composition. The resulting particle size was very uniform and photoluminescence (PL) characteristic was excellent, being about twice that of commercial red phosphor.

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

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1999.11a
• /
• pp.594-597
• /
• 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
• /
• v.29 no.2
• /
• pp.116-120
• /
• 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.

• Korean Journal of Materials Research
• /
• v.19 no.3
• /
• pp.163-168
• /
• 2009

$Eu^{3+}$-doped $Y_2O_3$ red phosphor was synthesized in a flux method using the chemicals $Y_2O_3,\;Eu_2O_3,\;H_3BO_3$ and $BaCl_2{\cdot}2H_2O$. The effect of a flux addition on the preparation of $Y_2O_3:Eu_{3+}$ red phosphor used as a cold cathode fluorescence lamp was investigated. $H_3BO_3$ and $BaCl_2{\cdot}2H_2O$ fluxes were used due to their different melting points. The crystallinity, thermal properties, morphology, and emission characteristics were measured using XRD, TG-DTA, SEM, and a photo-excited spectrometer. Under UV excitation of 254 nm, $Eu_2O_3$ 3.7 mol% doped $Y_2O_3$ exhibited a strong narrow-band red emission, peaking at 612 nm. From this result, the phosphor synthesized by firing $Y_2O_3$ with 3.7 mol% of $Eu_2O_3$, 0.25 mol% of $H_3BO_3$ and 0.5 mol% of $BaCl_2{\cdot}2H_2O$ fluxes at $1400^{\circ}C$ for 2 hours had a larger particle size of $4{\mu}m$ on average compared to the phosphor of the $H_3BO_3$ flux alone. In addition, a phosphor synthesized by the two fluxes together had a rounder corner shape, which led to the maximum emission intensity.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.33 no.1
• /
• pp.1-16
• /
• 2023

A non-rare earth-based strontium-aluminate red light emitting phosphor was synthesized by a solid-state reaction method and the effect of synthesis temperature and Mn⁴⁺ activator concentration on the photoluminescence characteristics of the phosphor was studied. The synthesized SrAl₂O₄:Mn⁴⁺ phosphor showed broad band absorption characteristics in the near-ultraviolet and blue regions with peaks at wavelengths of near 330 and 460 nm, and a triple band deep red emission consisted of three peaks at near 644, 658, and 673 nm. The SrAl₂O₄:Mn⁴⁺ phosphor synthesized at a temperature 1600℃ and a Mn⁴⁺ activator concentration of 0.5 mol% showed the strongest PL emission intensity, and concentration quenching was observed at concentrations higher than 0.7 mol%. FE-SEM and DLS particle size distribution analysis showed that the synthesized SrAl₂O₄:Mn⁴⁺ phosphor had a particle size distribution of 2~6.4 ㎛ and an irregular spherical shape with an average particle size of ~4 ㎛.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.21 no.9
• /
• pp.12-17
• /
• 2007

The dynamic false contour noise was analyzed with consideration for the phosphor decay time of an ac PDP by computer simulation based on the measurement of the 1/10 phosphor decay times of the primary colors red, green and blue at the main wavelengths of each phosphor. The noise level of dynamic false contour is strongly dependent on phosphor decay time. The noise level decreases incrementally with the phosphor decay time, whereas the noise width increases. The moving velocity of an object does not affect the noise level. The entire experiment was performed under the condition of 8 subfields ADS driving scheme, 2.5[${\mu}sec$] scan speed, and 5[${\mu}sec$] sustain period with VGA grade panel.