• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.58-58
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• 2010

We designed and synthesized DFPCE blue emitting materials by Mc Murry coupling reaction in order to improve the device efficiency and stability. The structure was confirmed by $^1H$-NMR. The physical properties were characterized by differential scanning calorimetry, thermogravimetric analysis, UV-vis, photoluminescence spectrum and cyclic voltammetry. The decomposition temperature of the material, which correspond to a 5% weight loss upon heating, is $513.58^{\circ}C$. The photoluminescence (PL) spectrum of DFPCE exhibited blue emission at 425 nm in chloroform solution and 462 nm in film.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.155-155
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• 2010

We have investigated organic light-emitting devices by doping phosphorescent orange and fluorescent blue emitters into the separate layers of single host. The electroluminescence spectra and current efficiency were strongly dependent on the location of each doped layers. The luminance-voltage (L-V) characteristics of the device2 (ITO/Hole Transport Layer/Orange Phosphorescent emissive layer/Blue Fluorescent emissive layer/Electron Transport Layer/liF/Al) showed the maximum current efficiency of 19.5 cd/A.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2002.05a
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• pp.167-171
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• 2002

We have investigated the optical properties of Te-doped ZnSSe:Te epitaxial layers grown on (100) GaAs substrates by molecular beam epitaxy. The Te-doped ternary specimen shows strong blue or green emission (at 300k) which is assigned to Te$_{1}$ or Te$_{n}$( n$\geq$2) cluster bound exciton. Bright green and blue light-emitting diodes (LEDs) have been developed using ZnSSe:Te system as an active layer. The green LEDs exhibit a fairly long device lifetime (>2000 h) when operated at 3 A/cm$^{2}$ under CW condition at room temperature. It is confirmed that the Te-doping induced "crystal-hardening effect" plays a significant role in both efficient and strong suppression of the optical device degradation.gradation.

• Journal of Information Display
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• v.8 no.1
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• pp.10-13
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• 2007

We synthesized new blue and bluish green emitting materials by using fully substituted ethylene moieties. Multi-layered EL devices were fabricated with synthesized materials and evaluated in terms of emission color and luminescence efficiency. TBBPE[EML 2] device showed bluish-green CIE value of (0.236, 0.412) and 5.02cd/A at $10mA/cm^2$. BPBBPE[EML 3] device also showed sky-blue CIE value of(0.218, 0.355) and 2.31cd/A at $l0mA/cm^2$.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.798-802
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• 2009

New blue emitting materials of o,p-TP-EPY and m,m-TP-EPY were synthesized using two terphenyl units with different structures in the new core of indenopyrazine. EL spectrum of o,p-TP-EPY was more blue shifted than m,m-TP-EPY, and external quantum efficiency of o,p-TP-EPY was showed improvement of about 60% compared to efficiency of m,m-TP-EPY.

• Journal of Information Display
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• v.4 no.2
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• pp.13-18
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• 2003

We synthesized bis (2-methyl-8-quinolinolato)(triphenylsiloxy) aluminum (III) (SAlq), a blue-emitting material having a high luminous efficiency, through a homogeneous-phase reaction. The photoluminescence (PL) and electroluminescence (EL) spectra of SAlq show two peaks at 454 nm and 477 nm. Efficient white light-emitting devices are fabricated by doping SAlq with a red fluorescent dye of 4-dicyanomethylene-2-methyl-6-{2-(2,3,6,7-tetrahydro-1H,5H-benzo[i,j]quinolizin-8yl) vinyl}-4H-pyran (DCM2). The incomplete energy transfer from blue-emitting SAlq to red-emitting DCM2 results in light-emission of both blue and orange colors. Devices with the structure of ITO/TPD (50 nm)/SAlq:DCM2 (30 nm, 0.5 %)/$Alq_3$ (20 nm)/LiF (0.5 nmj/Al show EL peaks at 456 nm and 482 nm originating from SAlq and at 570 nm from DCM2, resulting in the Commission Internationale d'Eclairage (CIE) chromaticity coordinates of (0.32, 0.37). The device exhibits an external quantum efficiency of about 2.3 % and a luminous efficiency of about 2.41m/W at 100 $cd/m^2$. A maximum luminance of about 23,800 $cd/m^2$ is obtained at the bias voltage of 15 V.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.137-140
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• 2007

We prepared ambipolar organic field-effect transistors and observed blue emission when both hole and electron accumulation layers were in the channel. We found that the reduction of carrier traps and controlling devices' preparation and measurement conditions were crucial for ambipolar operation.

• Journal of the Korean Chemical Society
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• v.50 no.3
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• pp.232-236
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• 2006

The Y1.99-xMxCe0.01SiO5(M=Li, La, Nd, and Gd) phosphors were synthesized by solid-state reaction at 1350oC for 10h under reducing atmosphere in order to improve properties of blue emitting phosphors. Compared with commercial blue phosphors, the Y2SiO5:Ce blue phosphors substituted with various elements showed significant enhancement of the emission intensity. Particularly, 1 mol% Li doped Y2SiO5:Ce phosphors indicated the maximum emission intensity in the photoluminescence spectra. Thanks to SEM analyses revealed that the morphology of Y2SiO5:(Ce,Li) blue phosphors was a pseudo-spherical with particle size of 3m.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.04a
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• pp.36-36
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• 2008

Organic light-emitting device (OLED) have become very attractive due to their potential application in flat panel displays. One important problem to be solved for practical application of full-color OLED is development of three primary color (Red, Green and Blue) emitting molecule with high luminous operation. Particularly, the development of organic materials for blue electroluminescence (EL) lags significantly behind that for the other two primary colors. For this reason, Flu-Si was synthesized and characterized by means of high-resolution mass spectro metry and elemental analyses. Flu-Si has the more wide optical band gap (Eg = 3.86) than reference material (Cz-Si, Eg = 3.52 eV). We measured the photophysical and electrochemical properties of Flu-Si. The HOMO-LUMO levels were estimated by the oxidation potential and the onset of the UV-Vis absorption spectra. The EL properties were studied by the device fabricated as a blue light emitting material with FIrpic.

• Journal of Information Display
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• v.3 no.1
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• pp.1-5
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• 2002

A series of fully conjugated polymers containing new arylenevinylene units were synthesized and their light-emitting properties were investigated. A bisphosphonate containing tetraphenyl group was made to react with three different dialdehyde monomers to produce fully conjugated alternating copolymers. The photoluminescence (PL) and the electroluminescence (EL) peak wavelengths of the polymers were varied from 500 nm to 460 nm depending on the polymer structure. Single layer EL devices using the polymers as an emissive layer have been fabricated. The single layer EL devices became visible between 12-22 V and emitted blue light.