• Title/Summary/Keyword: Cathode Layer

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Emission Characteristics of Dual Emission Tandem OLED with Charge Generation Layer MoOx and Cathode Al Thickness (전하생성층 MoOx와 음극 Al의 두께에 따른 양면발광 적층 OLED의 발광 특성)

  • Kim, Ji-Hyun;Ju, Sung-Hoo
    • Journal of Surface Science and Engineering
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    • v.49 no.3
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    • pp.316-321
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    • 2016
  • To study emission characteristics for dual-emission tandem organic light emitting display (OLED), we fabricated blue fluorescent OLED according to thickness variation of $MoO_x$ as charge generation layer and Al as cathode. The bottom emission characteristics of OLED with $MoO_x$ 2, 3, 5 nm thickness showed threshold voltage of 9, 7, 9 V, maximum current emission efficiency of 19.32, 23.18, 15.44 cd/A and luminance of $1,000cd/m^2$ at applied voltage of 17.6, 13.2, 16.5 V, respectively. The top emission characteristics of OLED with $MoO_x$ 2, 3, 5 nm thickness indicated threshold voltage of 13, 10, 13 V, maximum current emission efficiency of 0.17, 0.23, 0.16 cd/A and luminance of $50cd/m^2$ at applied voltage of 22.6, 16.5, 20.1 V, respectively. In case of thicker or thinner than $MoO_x$ of 3 nm, the emission characteristics were decreased because of mismatching of electron and hole in emission layer. The bottom emission characteristics of OLED with Al 15, 20, 25 nm thickness showed threshold voltage of 8, 8, 7 V, maximum current emission efficiency of 18.42, 22.98, 23.18 cd/A and luminance of $1000cd/m^2$ at applied voltage of 16.2, 13.9, 13.2 V, respectively. The reduction of threshold voltage and increase of maximum current emission efficiency are caused by the increase of current injection according to increase of Al cathode thickness. The top emission characteristics of OLED with Al 15, 20, 25 nm thickness indicated threshold voltage of 7, 7, 8 V, maximum emission luminance of 371, 211, $170cd/m^2$, respectively. The top emission OLED of Al cathode with 15 nm thickness showed maximum luminance and it decreased at thickness of 20 nm. These phenomena are caused by the decrease of intensity of emitted light by reduction of optical transmittance according to increase of Al cathode thickness.

Enhanced Electrochemical Properties of All-Solid-State Batteries Using a Surface-Modified LiNi0.6Co0.2Mn0.2O2 Cathode

  • Lim, Chung Bum;Park, Yong Joon
    • Journal of Electrochemical Science and Technology
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    • v.11 no.4
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    • pp.411-420
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    • 2020
  • Undesirable interfacial reactions between the cathode and sulfide electrolyte deteriorate the electrochemical performance of all-solid-state cells based on sulfides, presenting a major challenge. Surface modification of cathodes using stable materials has been used as a method for reducing interfacial reactions. In this work, a precursor-based surface modification method using Zr and Mo was applied to a LiNi0.6Co0.2Mn0.2O2 cathode to enhance the interfacial stability between the cathode and sulfide electrolyte. The source ions (Zr and Mo) coated on the precursor-surface diffused into the structure during the heating process, and influenced the structural parameters. This indicated that the coating ions acted as dopants. They also formed a homogenous coating layer, which are expected to be layers of Li-Zr-O or Li-Mo-O, on the surface of the cathode. The composite electrodes containing the surface-modified LiNi0.6Co0.2Mn0.2O2 powders exhibited enhanced electrochemical properties. The impedance value of the cells and the formation of undesirable reaction products on the electrodes were also decreased due to surface modification. These results indicate that the precursor-based surface modification using Zr and Mo is an effective method for suppressing side reactions at the cathode/sulfide electrolyte interface.

Electrical, Optical and Structural Properties of Indium Zinc Oxide Top Cathode Grown by Box Cathode Sputtering for Top-emitting OLEDs (박스 캐소드 스퍼터로 성장시킨 전면 발광 OLED용 상부 InZnO 캐소드 박막의 전기적, 광학적, 구조적 특성 연구)

  • Bae Jung-Hyeok;Moon Jong-Min;Kim Han-Ki
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.19 no.5
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    • pp.442-449
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    • 2006
  • Electrical, optical, and structural properties of indium zinc oxide (IZO) films grown by a box cathode sputtering (BCS) were investigated as a function of oxygen flow ratio. A sheet resistance of $42.6{\Omega}/{\Box}$, average transmittance above 88% in visible range, and root mean spare roughness of $2.7{\AA}$ were obtained even in the IZO layers grown at room temperature. In addition, it is shown that electrical characteristics of the top-emitting organic light emitting diodes (TOLEDs) with the BCS grown-IZO top cathode layer is better than that of TOLEDs with DC sputter grown IZO top cathode, due to absence of plasma damage effect. Furthermore the effects of oxygen flow ratio in IZO films are investigated, based on x-ray photoelectron spectroscopy (XPS), ultra violet/visible (UV/VIS) spectro-meter, scanning electron microscopy (SEM), and atomic force microscopy (AFM) analysis results.

Fabrication and Characteristics of Ceramic Fuel Cell with a Large Electrode Area (대면적 세라믹 연료전지용 단전지 제조 및 특성 연구)

  • Song, Rak-Hyun;Shin, Dong-Ryul
    • Proceedings of the KIEE Conference
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    • 1999.07d
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    • pp.1544-1546
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    • 1999
  • The fabrication process for ceramic fuel cell with a large electrode area was investigated. A cofired cell of two layer, electrolyte/anode, yielded a power of $200mW/cm^2$. Its performance loss was mainly due to iR drop in the anode side. The performance of the cofired of three layer. cathode/electrolyte/ anode, was much lower than that of two layer, which resulted from the large iR drop and overvoltage at the cathode side. Also a flat cell with a large area of $7.7{\times}10.8cm^2$ was fabricated successfully and tested using ceramic and metallic interconnectors. The large cell with metallic interconnectror showed a good performance of 0.6 V, 4.5 A.

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Enhancement of the Thickness Uniformity of a Phosphor Layer in the Cold Cathode Fluorescent Lamp

  • Kim, Min-Wan;Kim, Hie-Chul;Kim, Suk-Hwan;Lee, Sang-Woo;Choi, Byung-Ho;Kim, Kyung-Hwan;Sohn, Woo-Keun
    • 한국정보디스플레이학회:학술대회논문집
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    • 2004.08a
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    • pp.1068-1071
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    • 2004
  • We report the techniques to obtain the high uniformity of the phosphor film thickness in the cold cathode fluorescent lamps, which are widely used as a back-light for the liquid crystal display. The thickness variation of the phosphor layer was sensitive to blowing conditions. The optimum conditions were obtained at flow rate of 15 sccm for 30 min at 40 $^{\circ}C$. The optimum and uniform thickness of a phosphor layer gives good luminous output.

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Fabrication of the Electroluminescence Devices with Al electrode deposited by DC sputtering (DC 스퍼터링 증착에 의한 AI 전극을 갖는 전계발광소자 제작)

  • 윤석범
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.13 no.5
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    • pp.376-382
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    • 2000
  • We successfully fabricated OLED(Organic Light Emitting Diodes) with Al cathodes electrode deposited by the DC magnetron sputtering. The effects of a controlled Al cathode layer of an Indium Tin Oxide (ITO)/blended single polymer layer (PVK Bu:PBD:dye)/Al light emitting diodes are described. The PVK (Poly(N-vinylcarbazole)) and Bu-PBD (2-(4-biphenyl-phenyl)-1,3,4-oxadiazole) are used hole transport polymer and electron transport molecule respectively. We found that both current injection and electroluminescence output are significantly different with a variable DC sputtering power. The difference is believed to be due to the influence near the blended polymer layer/cathode interface that results from the DC power and H$\sub$2//O in a chamber. And DC sputtering deposition is an effective way to fabricate Al electrodes with pronounced orientational characteristics without damage occurring to metal-organic interface during the sputtering deposition.

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Structure and Optical Properties of the Ca/Ag Double Layer for Transparent Cathode in TEOLED

  • Kim, Boo-Kyung;Moon, D.G.;Ahn, B.T.
    • 한국정보디스플레이학회:학술대회논문집
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    • 2006.08a
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    • pp.1071-1074
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    • 2006
  • Ca/Ag double layer which is fabricated by thermal evaporation exists as the double layer of (Ca+O)/(Ag+Ca). In Ca layer, are crystalline Ca(OH)2 and amorphous Ca and in Ag layer, are crystalline Ag and amorphous Ca. And for the certain thickness of Ag, in the Ca/Ag double layer, the thicker Ca is, the higher transmittance is.

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Quantitative Analysis of Patents Concerning Cathode Active Materials for Lithium-Ion Secondary Batteries Based on Layer Structure (층상구조기반의 리튬이차전지용 양극 활물질에 관한 특허정량분석)

  • Kim, Byung-Nam;Lim, Yong-Hwan;Lee, Chul-Tae
    • Applied Chemistry for Engineering
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    • v.26 no.3
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    • pp.287-293
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    • 2015
  • This paper discusses quantitative analyses of patents published for cathode active materials for lithium secondary batteries based on layer structure. Numbers of the patents analyzed were 356, 1628, 2915, 439, and 611 for Korea, USA, Japan, Europe, and PCT (WO), respectively. Trends of improved technologies and alternative technologies concerning lithium cobalt, from 1991 to 2012 were examined and the patent shares distribution of each principal countries about lithium secondary battery technologies were also scrutinized. The number of patents for the mixed structure technology and next-generation lithium secondary battery technology increased numerously in 2000. Particularly in 2005, lots of patents were also published and SANYO (34.5%), SONY (17.5%), LG (7%), and SAMSUNG (5.5%) possessed leading patent applicants. Finally, the research focus on cathode active materials for lithium secondary batteries was confirmed by bubble chart distributions for component-by-step process.

A Study on the Performance Analysis and Design of Cathode in Fuel Cells (연료전지 전극(Cathode)의 성능해석 및 설계에 관한 연구)

  • Kim, H.G.;Kang, S.S.;Song, H.Y.;Kang, Y.W.;Kwac, L.K.
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.16 no.1
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    • pp.75-79
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    • 2007
  • The cathode design is one of the most important parts in order to enhance the performance of fuel cells. A 3-D model of the porous oxygen reducing cathode with perforated current collectors is analysed for the enhanced design in fuel cells. Simulation is performed using equations of electric potential balance, momentum balance, and mass balance. The gas concentrations are quite large and are significantly affected by the reactions that take place. The weight fraction of oxygen, velocity field for the gas phase, and local overvoltage are illustrated in the porous reactive cathode layer. The current density is also analysed and the result shows the distribution and variation are stated in a wide range. It is found that the rate of reaction and the current production is higher beneath the orifice, and decreases as the distance to the gas inlet increases. The significance of the results is discussed in the viewpoint of the mass transportation phenomena, which is inferred that the mass transport of reactants dictates the efficiency of the electrode in this design and at these conditions.

Advances in High Emission Sc2O3-W Matrix Cathode Materials

  • Wang, Jinshu;Yang, Yunfei;Liu, Wei;Wang, Yiman
    • Applied Microscopy
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    • v.46 no.1
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    • pp.20-26
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    • 2016
  • Our work on $Sc_2O_3-W$ matrix dispenser cathodes had been reviewed in this paper. The cathode with uniform distribution of $Sc_2O_3$ had been obtained using liquid-liquid doping method. The cathode had excellent emission property, i.e., the emission current density in pulse condition could reach over $35A/cm^2$. It was found that the cathode surface was covered by a Ba-Sc-O active substance multilayer with a thickness of about 100 nm, which was different from the monolayer and semiconducting layer in thickness. Furthermore, the observation results displayed that nanoparticles appeared at the growth steps and the surface of tungsten grains of the fully activated cathode. The calculation result indicated that the nanoparticles could cause the increase of local electric field strengths. We proposed the emission model that both the Ba-Sc-O multilayer and the nanoparticles distributing mainly on the growth steps of the W grains contributed to the emission. The future work on this cathode has been discussed.