• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.565-568
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• 2008

In this study, a blue-emitting $Sr_2MgSi_2O_7:Eu^{2+}$ (SMS) phosphor for white light-emitting diodes is reported. Through transition of $4f{\rightarrow}5d$ in $Eu^{2+}$, SMS showed a strong blue emission under UV excitation. Additionally, the variation of emission wavelength of SMS is explained by crystal field effect and is supported by rietveld refinement.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1046-1049
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• 2006

We proposed a simplified fabrication structure and method which can provide separate Red (R), Green (G), Blue (B), and White (W) OLED pixels with 2 metal-mask changes in emitting layer fabrication inspired from the structure of multi-layer white OLED and carrier blocking mechanism. A red emission layer for the R and W pixel with 1st mask, and then a blue emission layer with hole blocking layer for the B and W pixel with 2nd mask, and finally a common green emission layer were deposited sequentially. We expect that this concept would be very useful to the actual fabrication of multi-color OLED display although additional optimization is needed.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.1024-1027
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• 2002

In this study, we have investigated the substitutional effects of In ions with divalent ones in the $Srln_2O_4:Pr^{3+}$ phosphors and the relative change of the red and blue emissions. The substitutional Zn ions greatly intensified the blue emission band at 492 nm, but the red emission band at 608 nm was relatively less changed. On the other hand, Cd ions have no effect on the relative intensities. We explained the phenomena in connection with the distance of Pr-D, i.e., covalency experienced by a $Pr^{3+}$ion.

• The Korean Journal of Ceramics
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• v.3 no.1
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• pp.43-46
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• 1997

Thulium (Tm) has been incorporated into $YAlO_3$ and $YTa_7O_{19}$ host materials to obtain blue phosphors. $Tm^{3+}$-doped $YAlO_3$ and $YTa_7O_{19}$ phosphors were prepared by the conventional solid state reaction method. According to the results of excitation and emission spectra measured at room temperature, the blue emission intensity of $Tm^{3+}$-doped $YTa_7O_{19}$, peaking at 455 nm was much higher than that of $Tm^{3+}-doped\; YAlO_34, peaking at 458 nm. The maximum of relative intensity of $Tm^{3+}-doped\; YAlO_3\; and\; YTa_7O_{19}$ was obtained at the doping concentration of 0.016 and 0.120 mol% $Tm^{3+}$, respectively. These emission spectra revealed the concentration quenching effect.

• Bulletin of the Korean Chemical Society
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• v.16 no.2
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• pp.135-138
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• 1995

A series of new polymers containing phenylenevinylene (PV) units were synthesized by Wittig polycondensation reaction and properties of the synthesized polymers were characterized by FT-IR and UV-visible spectroscopy, and their light-emitting properties were studied. All of the synthesized polymers were soluble in organic solvents and showed good film quality. The absorption maxima and band edges of the polymers were moved to shorter wavelength region by reducing the electron donating alkoxy groups incorporated in phenylenevinylene unit. The photo-induced emission spectra were obtained and all of the polymers revealed their emission in blue region. The observed emission maxima of the polymers were ranged from 480-495 nm.

• Journal of Ceramic Processing Research
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• v.13 no.spc1
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• pp.59-63
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• 2012

Ga2O3-core/CdO-shell nanowires were synthesized by a two step process comprising thermal evaporation of GaN powders and sputter-deposition of CdO. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) analyses revealed that the cores and the shells of the annealed coaxial nanowires were single crystal of monoclinic Ga2O3 and FCC CdO, respectively. As-synthesized Ga2O3 nanowires showed a broad emission band at approximately 460 nm in the blue region. The blue emission intensity of the Ga2O3 nanowires was slightly decreased by CdO coating, but it was significantly increased by subsequent thermal annealing in a reducing atmosphere. The major emission peak was also shifted from ~500 nm by annealing in a reducing atmosphere, which is attributed to the increases in the Cd interstitial and O vacancy concentrations in the cores.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.773-776
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• 2005

In the fabrication of high performance Blue organic light emitting diode, 2-TNATA[4,4',4"-tris(2-naphthylphenyl-phenylamino)-triphenylamine] as hole injection material and NPB[N,N'-bis(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine] as hole transport material were deposited on the ITO (Indium Tin Oxide)/Glass substrate by vacuum evaporation. And then, Blue color emission layer was deposited using GDI602 as a host material and GDI691 as a dopant. Finally, small molecule OLED with the structure of ITO/2-TNATA/NPB/GDI602+GDI691/Alq3/LiF/Al was obtained by in-situ deposition of Alq3, LiF and Al as electron transport material, electron injection material and cathode, respectively. Blue OLED fabricated in our experiments showed the color coordinate of CIE(0.14, 0.16) and the maximum luminescence efficiency of 1.06 lm/W at 11 V with the peak emission wavelength of 464 nm.

• Bulletin of the Korean Chemical Society
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• v.28 no.8
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• pp.1280-1284
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• 2007

A series of Ca1-xSrxS:Eu (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) phosphors were synthesized by solid-state reactions. The Ca1-xSrxS:Eu phosphors have a strong absorption at 455 nm, which corresponds to the emission wavelength of a blue LED. The emission peak of Ca1-xSrxS:Eu is blue shifted from 655 to 618 nm with increasing Sr content. The characteristics of Ca1-xSrxS:Eu phosphors make them suitable for use as wavelengthtunable red-emitting phosphors for three-band white LEDs pumped by a blue LED. In support of this, we fabricated a three-band white LED by coating SrGa2S4:Eu and Ca0.6Sr0.4S:Eu phosphors onto a blue LED chip, and characterized its optical properties.

• Journal of the Korean Electrochemical Society
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• v.1 no.1
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• pp.24-27
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• 1998

Electroluminescence (EL) comes from the light emission obtained by the electrical excitation energy passing through a phosphor layer undo. an applied high electrical field $(10^6 V/cm)$. The preparation of white and blue phosphors and characterizations of light emitting alternating current powder electroluminescent devices (ACPELDs) were investigated. In this work, we fabricated two kinds of ELDs, that is, yellow electroluminescent device (B-ELD), blue electroluminescent device (B-ELD). The basic st.uctures of Y-ELD and B-ELD are ITO (Indium Tin Oxide)/phosphor layer/Insulator layer/Carbon electrode and ITO/Phosphor layer/Insulating layer/carbon electrode, respectively. Another structures of ITO/Phosphor and Insulator mixture layer/Backelectrode are introduced. EL spectra and luminance of two types of ELDs were measured by changing voltage at fixed frequency 0.4kHz, 1.5kHz. Blue and yellow phosphors prepared in this work show $50cd/m^2\;and\;30cd/m^2$ of luminance at 400Hz, 150V.

• Journal of Information Display
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• v.12 no.1
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• pp.51-55
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• 2011

Efficient two-color-mixed white organic light-emitting diodes are presented herein by employing a sky-blue phosphorescent dopant of iridium(III)bis[4,6-(difluorophenyl)-pyridinato-N,$C^{2'}$]picolinate (FIrpic) and an orange phosphorescent dopant of bis(2-phenylquinoline)(acetylacetonate)iridium(III) ($Ir(phq)_2$acac) on the emissive layer. Very stable color variation under ${\Delta}$0.02 until a 5000 cd/$m^2$ brightness value was realized by efficient carrier control in a multi-stacked emitting layer of blue/red/blue colors. Maximum current and power efficiencies of 23.8 cd/A and 22.9 lm/W in the forward direction were obtained. With balanced emission from the two emitters, the white-light emission of high correlated color temperature of 7308K and the Commission Internationale de I'Eclairage coordinates of (0.30, 0.33) were achieved.