• Applied Chemistry for Engineering
• /
• v.20 no.2
• /
• pp.227-233
• /
• 2009

Recently, dye-sensitized solar cell (DSSC), one of the solar cells, has been widely investigated. Studies on DSSCs can be classified into 4 fields such as $TiO_2$ nanocrystalline materials, dyes, electrolytes and conductive plate. In this work, $TiO_2$ nanoparticles for dye adsorption were synthesized, and added into the photo-electrode paste with different phosphor types and contents. Then, the influence of phosphor additives on the conversion efficiency of DSSCs was investigated. It was found that the maximum conversion efficiency was 8.81% when 0.5% of YAG phospher having the particle size of 400 nm was used.

• Journal of the Optical Society of Korea
• /
• v.14 no.4
• /
• pp.415-419
• /
• 2010

A phosphor-conversion white light source is demonstrated using an InGaN-based blue laser diode (LD) and a yellow-emitting phosphor excited by the blue LD. The photometric and colorimetric properties of this blue-LD-based white light source are characterized. When injection current of the LD is 100 mA, luminous flux and luminous efficiency of the white light are found to be over 5 lm and 10 lm/W, respectively. When injection current is >90 mA, luminance is estimated to be larger than 10 Mcd/$cm^2$. In addition, color characteristics of the white light such as chromaticity coordinates, a correlated color temperature, and a color rendering index are found to be quite stable as current and temperature of the LD varies. The demonstrated LD-based white light source is expected to be used in high-brightness illumination applications with good color stability.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2007.08b
• /
• pp.1559-1560
• /
• 2007

BGR mixture phosphor pumped by 400 nm is developed for white-light-emitting diode of liquid crystal display backlight. White-emitting phosphor is prepared by mixing $Ba_2SiO_4:Eu^{2+}$ and $(Ba,Sr)_3MgSi_2O_8:Eu^{2+},Mn^{2+}$ phosphors.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.25 no.3
• /
• pp.121-126
• /
• 2015

A novel $Ce^{3+}$ doped $Lu_3MgAl_3SiO_{12}$ phosphor ($Lu_{2.94}Ce_{0.06}MgAl_3SiO_{12}$) was successfully synthesized by a conventional solid-state reaction at $1450^{\circ}C$ for 5 h. The crystal structure of the synthesized phosphor powder was characterized by X-ray diffraction and Rietveld refinement. The prepared phosphor powder showed a broad peak at 550 nm, and the temperature dependence on photoluminescence properties of the prepared $Lu_{2.94}Ce_{0.06}MgAl_3SiO_{12}$ phosphor was investigated from 300 to 525 K. The activation energy for thermal quenching was determined by Arrhenius fitting. The experimental results clearly indicate that prepared $Lu_{2.94}Ce_{0.06}MgAl_3SiO_{12}$ phosphor has great potential for a down-conversion yellow phosphor in white light-emitting diodes.

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

• Journal of the Korean Ceramic Society
• /
• v.53 no.2
• /
• pp.258-262
• /
• 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.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.26 no.8
• /
• pp.614-619
• /
• 2013

Recently, remote phosphor is reported for white LED enhancing of phosphor efficiency compared with conventional phosphor-based W-LED. In this study, Remote phosphor was produced by screen printing coating on glass substrate with phosphor contents rated paste and heat treatment. The paste consists of phosphor, lowest softening glass frit and organic binders. Remote phosphor can be well controlled by varying the phosphor content rated paste. After mounting remote phosphor on top of blue LED chip, CCT, CRI, and luminance efficiency were measured. The measurement results showed that CCT, CRI, and luminance efficiency were 6,645, 68, and 1,16l m/W in phosphor 80 wt.% remote phosphor sintered at $600^{\circ}C$.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.26 no.2
• /
• pp.80-83
• /
• 2016

In the present paper, garnet structured $Y_3Al_5O_{12}:Ce^{3+}$ (YAG : Ce) ceramic phosphor plate (CPP) for high power laser diode (LD) was prepared and optical properties were analyzed. We synthesized monodispersed spherical nano-sized YAG : Ce particles by liquid phase method, fabricated phosphor ceramic plate with the addition of $Al_2O_3$. $75{\mu}m$ and $100{\mu}m$ thick YAG : Ce CPPs were compared in terms of the factors of conversion efficacy, thermal quenching, luminance and correlated color temperature (CCT). In conclusion, conversion efficacy decreased by 25 % in both samples and $100{\mu}m$ thick sample provides better optical properties of thermal quenching, maximum light conversion efficacy and maximum luminance value.

• Journal of Information Display
• /
• v.11 no.3
• /
• pp.128-133
• /
• 2010

The quantum efficiencies of CRT and FL tubes that use a phosphor screen as transducer of invisible particles to light in visible spectrum wavelengths were calculated in this study. The phosphor screens in CRT tubes have quantum efficiencies greater than 3,000, which give the luminance of comfortable images on phosphor devices for the observation by the eyes. The established FL tubes have the amazing quantum efficiency of $3{\times}10^{10}$ photons per moving electron per FL tube, which allows the illumination of a $5{\times}5\;m^2$ room by three FL tubes, with heating at $40^{\circ}C$. Thus, FL tubes, including for backlighting of LCD displays, have a superior over other illumination sources.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2016.02a
• /
• pp.408.2-409
• /
• 2016

Theoretically, the dye-sensitized solar cells (DSSCs) are high efficiency solar cells. However DSSCs have low power conversion efficiency (PCE) than silicon based solar cells. In this study, we use the phosphor materials, such as $Y_2O_3:Eu$ (Red), $Zn_2SiO_4:Mn$ (Green), $BaMgAl_{14}O_{23}:Eu$ (Blue), to enhance the PCE of DSSCs. Three phosphors were prepared and used as an effective scattering layer on the transparent $TiO_2$ with doctor blade method. We confirmed that the three scattering layers improve the PCE and Jsc due to the light harvesting enhancement via increased the scattering and absorbance in visible range. Under the sun illumination AM 1.5 conditions, the PCE of the mesoporous $TiO_2$ based DSSCs is 5.18 %. The PCE of the DSSCs with Y2O3:Eu, $Zn_2SiO_4:Mn$ and $BaMgAl_{14}O_{23}:Eu$ as scattering layer were enhanced to 5.66 %, 5.72% and 5.82%, respectably. In order to compare the optical properties change, DSSCs were measured by EQE, reflectance and PCE. At the same time, FE-SEM and XRD were used to confirm the structural changes of each layer.