• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.966-969
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• 2003

Thin film capacitors with Al-Polymer-Al sandwich structure were fabricated. The bottom and top aluminium (Al) electrodes were deposited by vacuum evaporation and copper phthalocyanine (CuPc), polyaniline-emeraldine base (Pani-EB) and cobalt phthalocyanine/polyaniline - emeraldine base (CoPc /Pani-EB) blend films (which can be used as buffer hole injection layer in OLEDs) were deposited by spin coating technique. X-ray diffractograms indicated amorphous nature of the polymer films whose thicknesses were measured by capacitance and Rutherford Backscattering Spectrometry (RBS) methods. AC conduction studies revealed that the conduction mechanism responsible in these films is variable range hopping of polarons. From D.C conduction studies, it is observed that, the nature of conduction is ohmic in the lower fields and at higher fields the dominating D.C conduction is of Poole-Frenkel type.

• Proceedings of the KIEE Conference
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• 2002.11a
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• pp.230-233
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• 2002

A new lithium niobate optical modulator with a polymer buffer layer on Ni in-diffused optical waveguide is proposed for the fist time, successfully fabricated and examined at a wavelength of 1.3 ${\mu}m$. The experimental results show that the measured half-wave voltage is of ${\sim}10$ V and the total measured fiber-to-fiber insertion loss is of ${\sim}-6.4$ dB for a 40 mm long waveguide at a wavelength of 1.3 ${\mu}m$, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.1003-1006
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• 2003

We have investigated the effect of hole-injection buffer layer and cathodes in organic light-emitting diodes u sing poly (3,4-ethylenedioxythiophene) : poly (stylenesulfonate) (PEDOT: PSS) in a device structure of $ITO/PEDOT:PSS/TPD/Alq_3/Cathode$. Polymer PEDOT:PSS buffer layer was made using spin casting method. Current-voltage, luminance-voltage characteristics and efficiency of device were measured at room temperature with a variation of cathode materials. The device with LiF/Al cathode shows an improvement of external quantum efficiency approximately by a factor of ten compared to that of Al cathode only device. Our observation shows that the energy barrier-height in cathode side is important in improving the efficiency of the organic light-emitting diodes.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.301-301
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• 2010

In order to enhance the efficiency of the organic solar cells, the effects of plasma surface treatment with using $CF_4$ and $O_2$ gas on the anode ITO were studied. The polymer solar cell devices were fabricated on ITO glasses an active layer of P3HT (poly-3-hexylthiophene) and PCBM ([6,6]-phenyl C61-butyric acid methyl ester) mixture, without anode buffer layer, such as PEDOT:PSS layer. The metallic electrode was formed by thermally evaporated Al. Before the coating of organic layers, ITO surface was exposed to plasma made of $CF_4$ and $O_2$ gas, with/without heat treatment. In order to identify the effect the surface treatment, the current density and voltage characteristics were measured by solar simulator and the chemical composition of plasma treated ITO surface was analyzed by using X-ray photoelectron spectroscopy(XPS). In addition, the work function of the plasma treated ITO surface was measured by using ultraviolet photoelectron spectroscopy(UPS). The effects of plasma surface treatment can be attributed to the removal organic contaminants of the ITO surface, to the improvement of contact between ITO and buffer layer, and to the increase of work function of the ITO.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1805-1808
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• 2006

In this paper, we describe a versatile use of fullerene(C60) as a charge transporting material for organic light-emitting diodes. The use of fullerene as a buffer layer for an anode, a doping material for hole transport layer, and an electron transport layer was investigated. Fullerene improved the hole injection from an anode to a hole transport layer by lowering the interfacial energy barrier and enhanced the lifetime of the device as a doping material for a hole transport layer. In addition, it was also effective as an electron transporting material to get low driving voltage in the device.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.1070-1073
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• 2003

We have studied the characteristics of organic light-emitting diodes(OLEDs) with the PTFE buffer layer. The OLEDs have been based on the molecular compounds, N,N'-diphenyl-N,N'-bis (3-methylphenyl)-1, 1'- biphenyl-4, 4'-diamine (TPD) as a hole transport, tris(8-hydroxyquinolinoline) aluminum (III) ($Alq_3$) as an electron transport and the Polytetrafluoroethylene (PTFE) as a buffer layer. The devices of structure were fabricated ITO/PTFE/TPD(40nm)/$Alq_3$(60nm)/Al( 150nm) to see the effects of the PTFE buffer layer in organic EL devices. The thickness of the PTFE layer varied from 0.5 to 10[nm]. We were measured Current-Voltage-Luminance Characteristics and Luminance efficiency due to the variation of PTFE thickness. the PTFE layer was reported that helped to enhance the hole tunneling injection and effectively impede induim diffusion from the ITO electrode. We have obtained an improvement of luminance efficiency when the PTFE thickness is 0.5[nm] is used. The improvement of efficiency of is expected due to a function of hole-blocking of PTFE in OLEDs.

• Applied Chemistry for Engineering
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• v.34 no.2
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• pp.161-169
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• 2023

In this study, we prepared naproxen (NP) imprinted biodegradable polymer based multi-layer biomaterials using allbanggae starch (ABS), polyvinyl alcohol (PVA), and alginic acid (SA), and investigated their physicochemical properties and the controlled drug release effects. In addition, the prepared multi-layer biomaterials were characterized by FE-SEM and FT-IR. In order to confirm the controlled drug release effect for the transdermal drug delivery system (TDDS), the NP release properties of NP imprinted multi-layer biomaterials were investigated using various pH buffer solutions and artificial skin at 36.5 ℃. The results of NP release in various pH buffer solutions indicated that the NP release at high pH was about 1.3 times faster than that at low pH. In addition, NP release in multi-layer biomaterials was about 4.0 times slower than that in single-layer biomaterials. It was confirmed that the NP release rate in triple-layer biomaterials was 4.0 times slower than that in single-layer biomaterials while using artificial skin. Also, it could be found that NP in double-layer biomaterials and triple-layer biomaterials was released sustainably for 12 h. The NP release mechanism in pH buffer solutions followed the Fickian diffusion mechanism, but followed the non-Fickian diffusion mechanism with artificial skin.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.7 no.3
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• pp.359-365
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• 1995

The drag reduction phenomenon with an additives of surfactant(STAC, stearlytrimethyl ammonium chloride) and polymer(PEO, polyethlene oxide) was investigated in fully developed turbulent pipe and channel flows at various low Reynolds numbers as well as very low additives concentration. A maximum of 70% drag reduction compared with plain water flow was found. This maximum drag reduction percentage obtained with surfactant solution was slightly higher than that of the Virk's asymptote in polymer solution.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.182-183
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• 2008

We fabricated a pentacene thin film transistor with Poly-vinylalcohol (PVA) as a dielectric. And we used Poly(9-vinylcarbazole) (PVK) as a buffer layer to improve the electrical characteristics. PVK is a material used often host material for OLED device, as it has good film forming properties, large HOMO-LUMO(highest occupied molecular orbital-lowest unoccupied molecular orbital) bandgap. The performance of a OTFT device with PVA gate dielectric was improved by using the PVK. Field effect mobility, threshold voltage, and on-off current ratio of device with PVK layer were about 0.6 $cm^2$/Vs, -17V, and $5\times10^5$, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.11a
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• pp.125-128
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• 1998

Electroluminescent(EL) devices based on organic thin films have attracted lots of interests in large-area light-emitting display. One of the problems of such device is a lifetime, where a degradation of the cell is possibly due to an organic layer's thickness, morphology and interface with electrode. In this study, light-emitting organic electroluminescent devices were fabricated using Alq$_3$(8-hydroxyquinolinate aluminum) and TPD(N,N'-diphenyl-N,N'-bis(3-methylphenyl)-[1-1'-biphenyl]-4,4'-diamine).Where Alq$_3$ is an electron-transport and emissive layer, TPD is a hole-transport layer. The cell structure is ITO/TPD/Alq$_3$/Al and the cell is fabricated by vacuum evaporation method. In a measurement of current-voltage characteristics, we obtained a turn-on voltage at about 9 V. And we used other buffer layer of PPy(Polypyrrole) with ITO/PPy/TPD/Alq$_3$/Al structure. We observed a surface morphology by AFM(Atomic Force Microscopy), UV/visible absorption spectrum, and PL(Photoluminescence) spectrum. We obtained the UV/visible absorption peak at 358nm in TPD and at 359nm in Alq$_3$, and at 225nm and the PL peaks at 410nm in TPD and at 510nm in Alq$_3$ and at 350nm. We also studied EL spectrum in the cell structure of ITO/TPD/Alq$_3$/Al and ITO/PPy/TPD/Alq$_3$/Al and we observed the EL spectrum peak at 510nm from our cell