• 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 2009년도 9th International Meeting on Information Display
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• pp.486-488
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• 2009

High efficiency deep blue and pure white phosphorescent organic light emitting diodes were developed using a new deep blue phosphorescent dopant, tris((3,5-difluoro-4-cyanophenyl)pyridine) iridium (FCNIr). A high quantum efficiency of 9.1 % with a color coordinate of (0.15, 0.16) at 1,000 cd/$m^2$ was obtained in the deep blue device and a high quantum efficiency of 15.2 % with a color coordinate (0.30, 0.32) was obtained in the pure white organic light-emitting diodes. The quantum efficiency of the pure white device is the best quantum efficiency value reported in the pure white device up to now.

• Bulletin of the Korean Chemical Society
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• 제35권2호
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• pp.513-517
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• 2014

Two donor-acceptor-donor monomers such as 3,5-bis(4-bromophenyl)-1,2,4-oxadiazole (BOB) and 3,5-bis(5-bromothiophen-2-yl)-1,2,4-oxadiazole (TOT) incorporating electron transporting and hole blocking 1,2,4-oxadiazloe moiety were copolymerized with light emitting fluorene derivative via Suzuki polycondensation to afford two new polymers, PFBOB and PFTOT, respectively. The optical studies for polymers PFBOB and PFTOT revealed that the band gaps are 3.10 eV and 2.72 eV, respectively, and polymer PFBOB exhibited a deep-blue emission while polymer PFTOT showed blue emission in chloroform and as thin film. The photoluminescence quantum efficiencies (${\Phi}_f$) of polymers PFBOB and PFTOT in chloroform calculated against highly blue emitting 9,10-diphenylanthracene (DPA, ${\Phi}_f=0.90$) were 1.00 and 0.44, respectively.

• ETRI Journal
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• 제45권6호
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• pp.1056-1064
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• 2023

The optical properties of the materials composing organic light-emitting diodes (OLEDs) are considered when designing the optical structure of OLEDs. Optical design is related to the optical properties, such as the efficiency, emission spectra, and color coordinates of OLED devices because of the microcavity effect in top-emitting OLEDs. In this study, the properties of top-emitting blue OLEDs were optimized by adjusting the thicknesses of the thin metal layer and capping layer (CPL). Deep blue emission was achieved in an OLED structure with a second cavity length, even when the transmittance of the thin metal layer was high. The thin metal film thickness ranges applicable to OLEDs with a second microcavity structure are wide. Instead, the thickness of the thin metal layer determines the optimized thickness of the CPL for high efficiency. A thinner metal layer means that higher efficiency can be obtained in OLED devices with a second microcavity structure. In addition, OLEDs with a thinner metal layer showed less color change as a function of the viewing angle.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2002년도 International Meeting on Information Display
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• pp.762-765
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• 2002

The bilayer organic light-emitting diode using Al (DBM) $_3$ (DBM=Dibenzoylmethane) as an emitting material and poly (N-vinylcarbazole) (PVK) as hole-transport material, emitted bright blue-green light instead of blue light. The blue-green emission is attributed to exciplex formation at the solid interface between Al (DBM) $_3$ and the hole-transport material. The exciplex formation was evidenced by the measurement of the photoluminescence spectra and lifetimes of Al (DBM) $_3$, PVK and an equimolar amount of mixture of Al (DBM) $_3$ and PVK.

• 한국세라믹학회지
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• 제42권3호
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• pp.145-149
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• 2005

[ $Eu^{2+}$ ]-activated barium magnesium silicate phosphor, $(Ba,Ca)_{3}MgSi_{2}O_{8}:Eu_{x}$, has been known to emit blue-green light. In this study we report the manufacturing processes for producing either pure green or pure blue light-emitting phosphor from the same composition of $Ba_{2-x}Ca_{2}CaMgSi_{2}O_{8}:Eu_{x}$ (0 < x < 1) by controlling heat treatment conditions. Green light emitting phosphor of $Ba_{1.9}CaMgSi_{2}O_{8}:Eu_{0.1}$ can be produced under the sample preparation condition of highly reducing atmosphere of $23\%\;H_2/77\%\;N_2$, while blue or blue-green light emitting phosphor under reducing atmosphere of $5\~20\%\;H_2\;/\;95\~80\%$ N_2. The green light-emitting phosphors are prepared in two steps: firing at $800\~1000^{\circ}C$ for $2\~5$ h in air then at $1100\~1350^{\circ}C$ for 2-5 h under reducing atmo­sphere $23\%$ $H_2/77\%\;N_2$. The excitation spectrum of the green light-emitting phosphor shows a broadband of $300\~410$ nm. The emission spectrum has a maximum intensity at the wavelength of about 501 nm. The CIE value of green light emission is (0.162, 0.528). The pure blue light-emitting phosphors can be produced using the $Ba{2_x}CaMgSi_{2}O_{8}:Eu_{x}$ by introducing additional firing step at $1150\~1300^{\circ}C$ in air before the final reducing treatment. The XRD analysis shows that the green light-emitting phosphor mainly consisted of $Ba_{1.31}Ca_{0.69}SiO_{4}$ (JCPDS $\#$ 36-1449) and other minor phases i.e., $MgSiO_3$ (JCPDS $\#$ 22-0714) and $Ca_{2}BaMgSi_{2}O_{8}$ (JCPDS $\#$ 31-0128). The blue light-emitting phosphor mainly consisted of $Ca_{2}BaMgSi_{2}O_{8}$ phase.

• 한국전기전자재료학회논문지
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• 제25권6호
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• pp.456-461
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• 2012

We studied the emission characteristics of white phosphorescent organic light-emitting diodes (PHOLEDs), which were fabricated using a two-wavelength method. To optimize emission characteristics of white PHOLEDs, white PHOLEDs with red/blue, blue/red and red/blue/red emitting layer (EML) structures were fabricated using a host-dopant system. In case of white PHOLEDs with red/blue structure, the best efficiency was obtained at a structure of red (15 nm)/blue (15 nm). But the emission color was blue-shifted white. In case of white PHOLEDs with blue/red structure, the better color purity and efficiency were observed at a blue (29 nm)/red (1 nm) structure. For additional improvement of color purity in white PHOLEDs with blue (29 nm)/red (1 nm) EMLs, we fabricated white PHOLEDs with red (1 nm)/blue (28 nm)/red (1 nm) structure. The current efficiency, external quantum efficiency, and CIE (x, y) coordinate were 27.2 cd/A, 15.1%, and (0.382, 0.369) at 1,000 $cd/m^2$, respectively.

• ETRI Journal
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• 제33권1호
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• pp.32-38
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• 2011

We investigated the light-emitting performances of blue phosphorescent organic light-emitting diodes, known as PHOLEDs, by incorporating an N,N'-dicarbazolyl-3,5-benzen interlayer between the hole transporting layer and emitting layer (EML). We found that the effects of the introduced interlayer for triplet exciton confinement and hole/electron balance in the EML were exceptionally dependent on the host materials: 9-(4-tert-butylphenyl)-3,6-bis(triphenylsilyl)-9H-carbazole, 9-(4-tert-butylphenyl)-3,6-ditrityl-9H-carbazole, and 4,4'-bis-triphenylsilanyl-biphenyl. When an appropriate interlayer and host material were combined, the peak external quantum efficiency was greatly enhanced by over 21 times from 0.79% to 17.1%. Studies on the recombination zone using a series of host materials were also conducted.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.415-417
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• 2009

Color stable and efficient two wavelength white organic light emitting diodes (OLEDs) were fabricated using a iridium(III)[bis(4,6-difluorophenyl)-pyridinato-N,$C^2$'] picolinate (FIrpic) as a blue phosphorescent emitter and a bis(1-phenylisoquinolinato-$C^2$,N)iridium (acetylacetonate) ((piq)$_2$Ir(acac)) as a red phosphorescent emitter. The emitting layers consist of two blue emitting layers and one red emitting layer which is between the two blue layers. The device reaches the peak efficiencies of 7.84 % and 10.3 cd/A at 0.6 mA/$cm^2$. Furthermore, there was little change of EL spectra according to current density change in the device.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.606-609
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• 1999

We fabricated white light-emitting diode which have a mixed single emitting layer containing poly(N-vinylcarbazole), trois(8-hydroxyquinoline)aluminum and poly(3-hexylthiophene) and investigated the emission properties of it. It is possible to obtain a blue light from poly(N-vinylcarbazole). green light from tris(8-hydroxyquinoline)aluminum and red light from poly(3-hexylthiophene). The fabricated device emits white light with slight orange light. We think that the energy transfer in a mixed layer occurred from PVK to Alq₃ and P3HT resulted in decreasing the blue light intensity from PVK. We find that the efficiency of the white light electroluminescent device can be improved by injecting electron more effectively and blue light need to improve the color purity of white light.