• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.762-766
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• 2009

We have synthesized and demonstrated a red emission in Organic Light Emitting Diodes (OLEDs) using phosphorescent iridium(III) complexes based on the 2-phenylpyridine ligands with electron-withdrawing carbonyl groups. Among those, a device exhibited highly efficient red-orange emission with the luminance of 20460 cd/$m^2$ at 12 V, the luminous efficiency of 22.0 cd/A at 20 mA/$cm^2$, and the $CIE_{x,y}$ coordinates of (x=0.560, y=0.439 ) at 10 V.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.433-433
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• 2010

A microplasma current switch (MPCS) for a device operated in a current mode like organic light-emitting diodes (OLEDs), which features matrix addressability and current switching, is presented as well as its architecture and operational principle. The MPCS utilizes the intrinsic memory and conductivity of plasmas to achieve matrix addressability and current switching. We have fabricated a $100\;mm\;{\times}\;100\;mm$ MPCS panel in which its cell pitch is $1080\;{\mu}m\;{\times}\;1080\;{\mu}m$. The matrix addressability and current switching were verified. In addition, the current-voltage (I-V) characteristic of the unit cell was measured when plasmas were ignited. In principle, the scheme of the MPCS is equivalent to that of a double Langmuir probe diagnosing plasma parameters except for their relative dimensions to a plasma volume. Accordingly, the I-V characteristic was analyzed by a double Langmuir probe theory, and the plasma density and electron temperature were estimated from the I-V curve using a collisional double Langmuir probe theory.

• Journal of the Semiconductor & Display Technology
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• v.21 no.1
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• pp.39-43
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• 2022

In this paper, a study was conducted on encapsulation technology for high mechanical stability of flexible displays. First, unlike conventional encapsulation barrier that exclude cracks as much as possible for low water vapor transmission rate (WVTR), mechanical properties were improved by using a defect suppression mechanism introduced with crack arresters. The zero-stress encapsulation barrier optimizes the residual stress of the thin film based to improve the internal mechanical stability. The zero-stress encapsulation barrier was applied to the organic light emitting diodes (OLEDs) to confirm its characteristics and lifetime. Due to improved internal mechanical stability, it has a longer lifetime more than 35% compared to conventional encapsulation technologies. As the zero-stress encapsulation barrier proposed in this study does not require additional deposition process, it is not difficult to apply it. Based on various advantages, it is expected to play an important role in flexible displays.

• Bulletin of the Korean Chemical Society
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• v.31 no.2
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• pp.389-396
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• 2010

In this paper, we reported the synthesis and electroluminescent properties of blue fluorescent styrylamine derivatives end-capped with a diphenylvinyl group. A new series of styrylamine derivatives have been synthesized via the Horner-Wadsworth-Emmons reaction. To explore electroluminescent properties of these molecules, multilayer organic lighte-mitting devices with the configuration of ITO/NPB/1-5 doped in MADN/Bphen/Liq/Al were fabricated. All devices exhibited blue emissions with good EL performances. Among those reported herein, the device using dopant 5 exhibited a maximum luminance of $24,000\;cd/m^2$ at 11.0 V, a luminous efficiency of 12.5 cd/A at $20\;mA/cm^2$, a power efficiency of 6.50 lm/W at $20\;mA/cm^2$, and $CIE_{x,y}$ coordinates of (x = 0.173, y = 0.306) at 8.0 V, all of which demonstrate the superiority of these materials in blue OLEDs.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.1038-1041
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• 2002

We have investigated the effects of cathode in organic light-emitting diodes of ITO/TPD/$Alq_3$/Cathodes(Al, LiF/Al, Ca/Al, and LiAl) by measuring current-voltage-luminance characteristics. The device with cathodes other than Al cathode shows the efficiency by an oder of one compared with Al cathode only. This improvement is due to a reduction of barrier height in cathode side.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.349-350
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• 2008

In the structure of ITO/N,N'-diphenyl-N,N' bis (3-methylphenyl)-1,1'-biphenyl-4,4'-diamine(TPD) /2,9-Dimethy 1-4,7-diphenyl-1,10-phenanthroline (BCP)/tris (8-hydroxyquinoline)aluminum$(Alq_3)$/Al device, we studied the efficiency improvement of organic light-emitting diodes due to thickness variation of BCP materials used for a electron breaking layer. The thickness of TPD and $Alq_3$ was manufactured 40 nm, 60 nm, respectively under a base pressure of $5\times10^{-6}$Torr using a thermal evaporation. The TPD and $Alq_3$ layer were evaporated to be at a deposition rate of 2.0 A/s. The BCP was evaporated to be at a deposition of 1.0 A/s. When the thickness of BCP increased from 5 to 30 nm, we found that the luminous efficiency and the external quantum efficiency is superior to the others when the thickness of BCP is 20 nm. Compared to the ones from the devices made without BCP, the luminous efficiency and the external quantum efficiency was improved by 57 %, 70%, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.423-424
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• 2008

A facing target sputtering (FTS) equiment is fabricated and its process characteristics are investigated to search for the possibility of applications to film passivation system for organic light emitting diodes (OLEDs). We report that the FTS system can prepare a high quality $ZrO_2$ films with a dense micro structure and an excellent uniformity less than 5% and a high transmittance over an average 80% in the visible range. We suggest that the FTS is one of the suitable deposition techniques for the thin film passivation layer of OLEDs and the gas barrier layer of polymer substrate.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.04a
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• pp.54-55
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• 2006

Organic light-emitting diodes(OLEOs) are attractive because of possible application in display with low operating voltage, low power consumption, self-emission and capability of multicolor emission by the selection of emissive material. We investigated the effects of deposition rate on the electrical characteristics, physical characteristics and optical characteristics of OLEOs in the ITO(indium-tin-oxide)/N.N'-diphenyl-N,N'-bis(3-methyphenyl)-1,1'-biphenyl-4,4'-diamine(TPD)/tris(8-hydroxyquinoline)aluminum($Alq_3$)/Al device. We measured current density, luminous flux and luminance characteristics of devices with varying deposition rates of TPD and $Alq_3$. It has been found that optimal deposition rate of TPD and $Alq_3$ were respectively $1.5{\AA}/s$ from the device structure. An AFM measurement results, surface roughness of the deposited film was the lowest when deposition rate was $1.5{\AA}/s$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.4
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• pp.357-362
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• 2007

AZO(Aluminum-doped Zinc Oxide) films are attractive materials as transparent conductive electrode because they are inexpensive, nontoxic and abundant element compared with ITO(Indium Tin Oxide). AZO films have been deposited on glass (corning 1737) substrates by RF magnetron sputtering. The AZO film was post-annealed at $600^{\circ}C$ for 2 hr with $N_2$ atmosphere. The AZO films were used as an anode contact to fabricate OLEDs(Organic Light Emitting Diodes). OLEDs with $AZO/TPD/Alq_3/Al$ configuration were fabricated by thermal evaporation. We investigated that the electric, structural and optical properties of AZO thin films, which measured using the methods of XRD, SEM, Hall measurement and Spectrophotometer. The current density-voltage and luminescence-voltage properties of devices were studied and compared with ITO devices fabricated under the same conditions.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1463-1464
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• 2011

An indium thin oxide(ITO) is used as a substrate material for organic light-emitting diodes(OLEDs) and organic photovoltaic cells. This study examined the effects of an $O_2$ plasma treatment on the electrical properties of an organic photovoltaic cell. The four probe method and Atomic force microscope(AFM) revealed the lowest surface resistance at the plasma treatment intensity of 250 [W] and the lowest average surface roughness of 2.0 [nm] at 250 [W]. The lowest average resistance of 17 [${\Omega}$/sq] was also observed at 250 [W] 40 [sec]. The $O_2$ plasma treatment device and a basic device in a structure of CuPc/C60/BCP/Al on ITO glass were fabricated by thermal evaporation, respectively. When the $O_2$ plasma treatment was used to the ITO, The experimental results revealed that the power conversion efficiency(PCE) indicated 65 [%] higher in the PCE than that without the plasma treatment.