• 한국세라믹학회지
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• 제53권4호
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• pp.456-462
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• 2016

$NaCaGd(MoO_4)_3:Ho^{3+}/Yb^{3+}$ ternary molybdates were successfully synthesized by microwave sol-gel method for the first time. Well-crystallized particles formed after heat-treatment at $900^{\circ}C$ for 16 h showed a fine and homogeneous morphology with particle sizes of $3-5{\mu}m$. Under excitation at 980 nm, the UC intensities of the doped samples exhibited strong yellow emissions based on the combination of strong emission bands at the 520-nm and 630-nm emission bands in the green and red spectral regions, respectively. The strong 520-nm emission band in the green region corresponds to the $^5S_2/^5F_4{\rightarrow}^5I_8$ transition of $Ho^{3+}$ ions, while the strong 630-nm emission band in the red region appears to be due to the $^5F_5{\rightarrow}^5I_8$ transition of the $Ho^{3+}$ ions. The optimal $Yb^{3+}:Ho^{3+}$ ratio was found at 9:1, as indicated by the composition-dependent quenching effect of $Ho^{3+}$ ions. The pump power dependence of the upconversion emission intensity and the Commission Internationale de L'Eclairage chromaticity coordinates of the phosphors were evaluated in detail.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.688-691
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• 2004

In this study, we synthesized a new red emitting material of a Red225 doped into $Alq_3$ (tris(8-quinolinolato)aluminum (III)) and fabricated white organic light-emitting diodes (OLEDs) with a simple device structure. With a blue emitting material of DPVBi (4,4'-bis(2,2'-diphenylvinyl)1,1'-biphenyl) that can transfer effectively both a hole and an electron, OLEDs with a narrow emission layer could be possible without a hole-blocking layer. Consequently, the driving voltage and stability of devices have been improved. The devices show the Commission Internationale d'Eclairage (CIE) chromaticity coordinates of (0.36, 0.35) at luminance of 2000 cd/$m^2$. The luminous efficiency is about 3.5 cd/A, luminance is about 12000 cd/$m^2$ and current density is about 350 mA/$cm^2$ at 12 V, respectively.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.1091-1094
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• 2004

High-luminous efficiency full-color emissions in photoluminescence (PL) were obtained in $GdVO_4$ phosphor thin films co-doped with various amounts of Eu, Er and/or Tm and postannealed at approximately 1000$^{\circ}C$. The $GdVO_4$:Eu,Er,Tm phosphor thin films were deposited on thick $BaTiO_3$ ceramic sheets by r.f. magnetron sputtering using powder targets and postannealed in an air atmosphere. The rare earth (RE) content (RE/(Gd+V+RE) atomic ratio) in the oxide phosphor thin films was varied in the range from 0.1 to 2 at.%. It was found that the excitation of $GdVO_4$:Eu.Er,Tm thin films is attributed to band-to-band transition. A white PL emission was obtained in a $GdVO_4$:Eu,Er,Tm thin film with Eu, Er and Tm contents of 0.2, 0.7 and 1 at.%, respectively: CIE chromaticity color coordinates. (X=0.352 and Y=0.351). In addition, a white emission was obtained in a thin-film electroluminescent (TFEL) device made with this thin film.

• 한국안광학회지
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• 제5권1호
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• pp.31-37
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• 2000

제1~3색각 이상 검사용 Farnsworth Dichotomous Test Panel D-15의 칼라분석을 위하여 380~780 nm의 반사광 spectrum 세기를 측정하여 CIE system을 도입하였다. Panel D-15의 색상변환은 650nm 이상, 500~600 nm, 400~450 nm의 3개 파장영역의 광 반사율 세기에 의존한다. 반사 spectrum으로부터 3극치 X, Y, Z 값, 보색 평면과 명암축으로 하는 3차원 CIELAB system의 $L^*a^*b^*$와 Lab 값, CIELUV system $U^*V^*$ 값, 색도도 좌표 x, y 값을 구했다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.II
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• pp.1378-1380
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• 2005

The efficiency and the optical properties of the yellow organic light-emitting devices (OLEDs) were significantly affected by the existence of the multiple quantum well (MQW) structures consisting of N, N'- bis-(1-naphthyl)-N, N'-diphenyl-1,1-biphenyl-4,4'- diamine(NPB)/5,6,11,12 - tetraphenylnaphthacene (rubrene). The maximum efficiency and the luminance of OLEDs with 3-periods of the NPB/rubrene MQWs at 41.6 $mA/cm^2$ were 3.66 cd/A and 1524 $cd/m^2$, respectively, and their Commission Internationale de l'Eclairage chromaticity coordinates were (0.34, 0.55), which indicates a yellow color. These results indicate that the efficiencies of the OLEDs by using MQW emitting layers can be improved.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.940-943
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• 2003

We report the fabrication and the characterization of white organic light-emitting devices consisting of a red-emitting layer of a new DCM derivative doped into 4,4'bis[N-(1-napthyl)-N-phenyl-amino]-biphenyl (${\alpha}-NPD$) and a blue-emitting layer of 1,4-bis(2,2-diphenyl vinyl)benzene (DPVBi). The device structure is ITO/PEDOT:PSS/${\alpha}-NPD$ (50 nm)/${\alpha}-NPD$:DCM (5 nm, 0.2 %)/DPVBi (x)/Alq3 (40 nm)/LiF (0.5 nm)/Al. The electroluminescence (EL) spectra consist of two broad peaks around 470 nm and 580 nm with the spectral emission depending on the thickness of DPVBi. The device with the DPVBi thickness of about 20 nm show a white light-emission with the Commission Internationale d'Eclairage(CIE) chromaticity coordinates of (0.33, 0.36). The external quantum efficiency is 2.6% and luminous efficiency is 2.0 lm/W at a luminance of 100 $cd/m^{2}$. The maximum luminance is about 30,270 $cd/m^{2}$ at 13.9 V.

• ALGAE
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• 제30권2호
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• pp.171-179
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• 2015

Organic light-emitting materials in marine macrophytes from various coastal environments were identified. Twentyeight species from the solvent fractions were examined and identified as candidates for bioorganic light-emitting materials using photoluminescence (PL) spectra and gas chromatography-mass spectrometry. We selected 16 solvent fractions from a total of 1,221 prepared from Ishige okamurae, Sargassum confusum, Grateloupia elliptica, Chondracanthus intermedius, Porphyra yezoensis, Meristotheca papulosa, Gelidium amansii, and Scytosiphon lomentaria. The maximum light-emitting PL spectra appeared at various colors, mainly between blue and green, based on chromaticity coordinates, from solvent fractions of M. papulosa, G. amansii, G. elliptica, P. yezoensis, S. lomentaria, I. okamurae, and C. intermedius. These results will contribute to the development of novel organic light-emitting materials.

• Bulletin of the Korean Chemical Society
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• 제28권3호
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• pp.443-446
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• 2007

The novel blue light emitting material, 9,10-bis(3',5'-diphenylphenyl)anthracene (BDA) was synthesized by Suzuki coupling reaction and characterized by the measurements of 1H NMR, 13C NMR and FT-IR. The new anthracene derivative, which contains anthracene as a main core unit and 3',5'-diphenylphenyl group derivative as wings, has high fluorescence yield, good thermal stability, and high glass transition temperature at 188 oC. With the newly non-doped blue emitting material in the multilayer device structure, it was possible to achieve the current efficiency of 3.0 cd/A. The EL spectrum of the ITO/CuPc/α-NPD/BDA/Alq3/LiF/Al device showed a maximum wavelength (λmax) at 440 nm. The emitting color of device showed the blue emission (x,y) = (0.18,0.19) at 10 mA/cm2 in CIE (Commission Internationale de l'Eclairage) chromaticity coordinates.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2002년도 International Meeting on Information Display
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• pp.701-705
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• 2002

In order to realize full color display, two approaches were used. The first method is the patterning of red, green, and blue emitters using a selective deposition. Another approach is based on a white-emitting diode, from which the three primary colors could be obtained by micro-patterned color filters. White-light-emitting organic light emitting devices (OLEDs) are attracting much attention recently due to potential applications such as backlights in liquid crystal displays (LCDs) or other illumination purposes. In order for the white OLEDs to be used as backlights in LCDs, the light emission should be bright and have Commission Internationale d'Eclairage (CIE) chromaticity coordinates of (0.33, 0.33). For obtaining white emission from OLEDs, different colors should be mixed with proper balances even though there are a few different methods for mixing colors. In this study, we will report a white organic electroluminescent device based on an incomplete energy transfer. In which the blue and green emission come from the same layer via incomplete energy transfer.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.156-156
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• 2011

Nanocrystalline $Ca_2Gd_8Si_6O_{26}$ (CGS) : $Sm^{3+}$ and CGS : $Tb^{3+}/Sm^{3+}$ phosphors were prepared by solvothermal reaction method for light emitting diode (LED) and field emission display (FED) applications. The XRD patterns of these phosphors confirmed their oxyapatite structure in the hexagonal lattice. The visible luminescence properties of these phosphors were investigated by exciting with ultraviolet (UV) or near-UV light and low voltage electron beam. The photoluminescence (PL) properties of $Ca_2Gd_8Si_6O_{26}$ (CGS) : $Sm^{3+}$ and CGS : $Tb^{3+}/Sm^{3+}$ phosphors were investigated as a function of $Sm^{3+}$ concentration. Cathodoluminescence (CL) properties were examined by changing the acceleration voltage. The CGS : $Sm^{3+}$ showed the dominant orange emission due to the $^4G_{5/2}{\rightarrow}^6H_{7/2}$ transition. The CGS : $Tb^{3+}/Sm^{3+}$ phosphor showed the green, white and orange emissions when excited with 275, 378, and 405 nm wavelengths, respectively. The chromaticity coordinates of these phosphors were comparable to or better than those of standard phosphors for LED or FED devices.