• Bulletin of the Korean Chemical Society
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• v.26 no.9
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• pp.1344-1346
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• 2005

We report microcavity effect of top emission organic light-emitting diodes (OLEDs) by using Al cathode and anode, which are feasible for not only top emission EL and angle dependant effects but facile evaporation process without ion sputtering. The device in case of $Alq_3$ green emission showed largely shifted EL maximum wavelength as 650 nm maximum emission. It was also observed that detection angle causes different EL maximum wavelength and different CIE values in R, G, B color emission. As a result, the green device using $Alq_3$ emission showed 650 nm emission ($0^{\circ}$) to 576 nm emission ($90^{\circ}$) as detection angle changed. We believe that these phenomena can be also explained with microcavity effect which depends on the different length of light path caused by detection angle.

• Fibers and Polymers
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• v.1 no.1
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• pp.25-31
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• 2000

Poly(3-hexyl thiophene)(P3HT) and poly(3-dodecyl thiophene)(P3DT) were polymerized by oxidative coupling with ferric chloride. The P3HT light-emitting device emitted red light and it could be observable in the ordinary indoor light. The device had the turn-on electric field of about 3$\times$$10^7$ V/m. The maximum electroluminescene (EL) intensity was obtained when the thickness of polymer layer was about 130 nm in IT0/P3HT/Al device. The maximum external quantum yield was 0.002%. The maximum luminance was 21 cd/$m^2$. The EL intensity decreases with increasing the crystallinity of the polymer layer. By using the oriented poly(3-alkyl thiophene)(PAT) layer as an electroluminescent layer in the ITO/polymer/Al light-emitting devices, the polarized EL light emission was observed. The EL intensity ratio of parallel to perpendicular direction to the stretch direction for P3HT was about 1.40.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.545-548
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• 2008

We report the synthesis of blue emitting materials with a new core structure containing indenopyrazine. Non-doped device using one of these materials as a blue emitter was found to exhibit high external quantumn efficiency of 4.6% and excellent color purity of (0.154, 0.078) as well as narrow emission band of 47nm FWHM.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.496-498
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• 2008

We have developed green phosphorescent organic light-emitting diodes (OLEDs) with high quantum efficiency. Wide-energy-gap material, 1,1-bis[(di-4-tolylamino) phenyl]cyclohexane (TAPC), with high triplet energy level was used as a hole transporting layer. Electrophosphorescent devices fabricated using TAPC as a hole-transporting layer and N,N'-dicarbazolyl-4,4'-biphenyl (CBP) doped with fac-tris(2-phenylpyridine) iridium [Ir(ppy)3] as the emitting layer showed the maximum external quantum efficiency ($\eta_{ext}$) of 19.8 %, which is much higher than the devices adopting 4,4'-bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl (NPB) (${\eta}B_{ext}=14.6%$) as a hole transporting layer.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.609-612
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• 2008

Characteristics of indium-zinc-oxide (IZO)-Ag-IZO multilayer grown on a PET substrate were investigated for flexible organic emitting diodes. By inserting very thin Ag layer between amorphous IZO, IZO-Ag-IZO (IAI) multilayer anode exhibited remarkably reduced sheet resistance and high transmittance due to the surface plasmon resonance effect and Ag layer.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.443-445
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• 2008

We have fabricated vertical type organic thin film transistor using $C_{60}$ as a n-type active material to improve the problems of conventional OTFTs. In general, it can be argued that the characteristics of organic transistor were influenced by carrier mobility and density. We have used several kinds of metals as source and gate electrodes to optimize the device characteristics using $C_{60}$. In addition, we have examined the feasibility of fabrication of organic light-emitting transistor (OLET) using MEH-PPV as an emission layer.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.424-427
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• 2008

We make performance simulations of three different organic light-emitting diodes (OLEDs), one of which is based on a conventional layered structure and the others on a blended structure where an emitting layer (EML) is either uniformly or stepwise mixed with an electron transport layer (ETL), Tris-(8-hydroxyquinoline) aluminum ($Alq_3$).

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.980-983
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• 2006

New blue light emitting branched molecules were synthesized by reacting 3,5-bis-(3,5-bis-benzyloxy)- benzoic moiety or 3,5-bis-(3,5-bis-benzyloxy-benzyloxy)- benzoic moiety with biscarbazolyl vinyl biphenyl moiety by dicyclohexylcarbodiimide (DCC) catalyzed esterification. Similar synthetic strategy was also applied to prepare a red light emitting dendrimer. In this paper, we described two blue emitting dendrimers for investigating the effect of the dendronized structures on photoluminescence (PL) and electroluminescence (EL). EL properties of the dendrimers were investigated using heterostructured samples in detalil.

• Journal of Information Display
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• v.6 no.1
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• pp.33-36
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• 2005

To obtain various colors from the blue emitting poly(fluorene)s, two different approaches are introduced. One is copolymerization with low band gap comonomers and the other is molecular doping with various dyes. As fast and efficient exciton migration and trapping and/or energy transfer between the chromorphoric segments or doped dyes in conjugated polymers can shift the emission to longer wavelengths, these phenomena can be utilized to obtain various colors from the intrinsically blue light emitting poly(fluorene)s.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1813-1818
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• 2006

We demonstrate a new approach to form gradient hole injection layer (HIL) in organic light-emitting diodes (OLEDs). Single spincoating of hole-injecting conducting polymer compositions with a perfluorinated ionomer results in gradient workfunction through the layer by self-organization, which lead to remarkably efficient single layer polymer light-emitting diodes (PLEDs) (${\sim}21$ cd/A). The device lifetime was significantly improved (${\sim50$ times) compared with the conventional hole injection layer, poly(3,4-ethylenedioxy-thiophene)/polystyrene sulfonate. This solution processed HIL also produced dramatically enhanced luminous efficiency (${\sim}34$ cd/A) in vacuum- deposited green fluorescent OLEDs while the vacuum deposited HIL gave the luminous efficiency of ${\sim}23$ cd/A in the same device structure.