• Title/Summary/Keyword: hole injection

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산소 분압에 따른 ITO의 일함수 변화와 그에 따른 이종접합 태양전지 특성 분석

  • Jo, Jae-Hyeon;Choe, Hyeong-Uk;Lee, Won-Baek;Jeong, Seong-Uk;Lee, Jun-Sin
    • Proceedings of the Korean Vacuum Society Conference
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    • 2010.02a
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    • pp.216-216
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    • 2010
  • 이종접합 태양전지의 투명전도막으로 사용되는 ITO는 박막 증착시 Ar과 O2의 공정 가스비증가에 따라 일함수가 증가한다고 보고되어지고 있다. 이러한 일함수의 증가는 ITO와 n a-si:H과의 계면에서 barrier height를 낮춤으로써 hole injection을 원활하게 만들어줌으로써 이종접합 태양전지의 효율 향상을 기대할 수 있게 해준다. RF sputtering system으로 증착된 ITO 증착시 순수 Ar만으로 증착된 ITO와 0.1에서 0.5% 까지 미세산소함량으로 증착된 ITO의 단일막 특성과 이를 이종접합 태양전지에 적용하였을 때의 특성을 분석하였다. ITO의 단일막 전기적 특성 분석을 위하여 Hall measurement를 이용하였고 광학적 특성 분석을 위해 UV-Vis를 이용하였다. 또한 광전자 분광장치를 이용하여 일함수 변화를 측정하였다. 그리고 산소 함량에 따른 ITO 박막의 특성 변화를 통해 이종접합 태양전지의 광특성을 비교하였다. 전기적인 특성의 경우 0.1%의 산소함량에서 가장 낮은 비저항을 얻었고 이동도의 경우 산소 함량에 따라 점차 증가하게 되었다. 반면 Carrier concentration은 점차 감소하였다. 투과도의 경우 산소함량을 통해 제작된 ITO가 Ar만으로 제작된 ITO보다 500 nm 파장대에서 1% 정도의 높은 투과율을 갖게 되었다. 그리고 ITO 공정시 Ar 만으로 증착한 경우 4.3 eV의 일함수를 보이고 공정중 산소가 첨가됨으로써 4.8 eV 으로 일함수가 증가하게 되었고 이종접합 태양전지를 제작하여 Voc, Jsc, Eff 등이 각각 15mV, 2mA/cm2, 1.5% 정도의 광특성 향상을 얻을 수 있었다.

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The Review of Studies on Heat Transfer in Impinging Jet

  • Hong, Sung-Kook;Cho, Hyung-Hee
    • International Journal of Air-Conditioning and Refrigeration
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    • v.13 no.4
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    • pp.196-205
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    • 2005
  • In this paper, recent research trend on heat transfer in impinging jet is reviewed. We focused on submerged jet that air issued into air or liquid issued into liquid. To control and enhance the heat transfer in single jet, researchers have performed a lot of experiments by considering the nozzle geometry, impinging surface and active method such as jet vibration, secondary injection and suction flow. The studies on multiple jet have been mainly focused on finding out the optimum condition and on investigating many different factors concerned with application condition (crossflow, rotation and geometry etc.) and combined techniques (rib turbulator, pin fin, dimple and effusion hole etc.). All most experiments showed the detailed heat transfer data by using liquid crystal method, infrared camera technique and naphthalene sublimation method. Many numerical calculations have been performed to investigate the flow and heat transfer characteristics in laminar jet region. Various turbulence models such as $k-\varepsilon-\bar{\nu^2}$, modified $k-\varepsilon-f_{\mu}$ were applied to the calculation for turbulent jet and the predicted results showed a good agreement with the experimental data. Although a lot of studies on impinging jet have performed consistently up to recently, further studies are still required to understand the flow and heat transfer characteristics more accurately, and to give a guideline for optimum impinging jet design in various applications.

Analysis of morphological and electrical properties of optoelectronic devices with trimethoxy(proply)silane

  • Myung-Gyun Baek;Sang-Seok Yun;Jin-Sa Kim;Hong-Gyu Park;Sang-Geon Park
    • Journal of Ceramic Processing Research
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    • v.23 no.3
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    • pp.320-325
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    • 2022
  • In this study, we investigated the deposition of trimethoxy(propyl)silane as a self-assembled monolayer (SAM) on the surface of an indium tin oxide (ITO) substrate in organic light-emitting diodes (OLEDs) by examining the changes in surface characteristics of the modified substrate with variations in deposition time and temperature. The highest contact angle was obtained at 160 ℃, and for each deposition time, the contact angles were 63°, 66°, 80°, 96°, 103°, 103°, 103°, and 104°, respectively, indicating the contact angle, and thus the hydrophobicity, increased with increasing deposition time and temperature. In addition, after 90 min of deposition, adequate SAM coverage was achieved on the ITO surface. When the coverage ratio was calculated, ≥ 99% coverage was obtained after 90 min of deposition at 160 ℃. Atomic force microscopy of samples with SAM coverage obtained after 90 min at different deposition tem-peratures revealed improvement in the surface roughness of the fabricated samples. The work function, measured using a photoelectron spectrometer, demonstrated a characteristic increase with increasing temperature. Thus, SAM deposition can improve the ITO surface properties depending on the time and temperature of deposition.

A Study on the High Pressure Pump Simulation Model of a Diesel Injection System (디젤 분사시스템의 고압펌프 시뮬레이션 모델에 대한 연구)

  • Kim, Joongbae
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.10
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    • pp.102-109
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    • 2017
  • The high pressure pump of a diesel injection system compresses the fuel supplied at low pressure into high pressure fuel and maintains the fuel of the common rail at the required pressure level according to the engine operating conditions. The high pressure pump is required to operate normally in order to compress the fuel to a high pressure of 2000 bar during the entire lifetime of the vehicle. Consequently, a suitable design technique, material durability and high precision machining are required. In this study, the high pressure pump simulation model of a 1-plunger radial piston pump is modelled by using the AMESim code. The main simulation parameters are the displacement, flow rate and pressure characteristics of the inlet and outlet valves, cam torque characteristics, and operating characteristics of the fuel metering valve and overflow valve. In addition, the operating characteristics of the pump are simulated according to the parameter changes of the hole diameter and the spring initial force of the inlet valve. The simulation results show that the operation of the developed pump model is logically valid. This paper also proposes a simulation model that can be used for current pump design changes and new pump designs.

Combustion Characteristics and On-site Performance Test of a Double-cone Partial Premixed Nozzle with Various Fuel hole Patterns (이중 콘형 부분예혼합 GT 연료노즐의 연소특성 및 발전플랜트 실증)

  • Kim, Han Seok;Cho, Ju Hyeong;Kim, Min Kuk;Hwang, Jeongjae;Lee, Won June;Min, Kyungwook;Kang, Do Won
    • Journal of the Korean Institute of Gas
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    • v.25 no.6
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    • pp.22-28
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    • 2021
  • Combustion characteristics were examined experimentally for a swirl-stabilized double cone premixed burner nozzle used for industrial gas turbines for power generation. An original model and a variant with a different fuel injection pattern are tested to compare their combustion characteristics such as NOx, CO and stability in pressurized conditions with single burner-flame and in an ambient multi-flame conditions with multi-burners. Test results show that NOx emissions are smaller for the variant, whose number of fuel holes is reduced with the same total area of fuel holes, in ambient and pressurized single-flame conditions with single burner, which results from enhanced fuel/air mixing due to a higher penetration of fuel into the air stream. The multi-burnerflame test results show that NOx emissions are smaller for the variant due to reduced flame interactions, which, on the contrary, slightly reduces the stability margin. On-site test results fromin an actual power plants also show that NOx emissions are reduced for the variant, compared with the original one, which is in agreement with the lab test results stated above.

Single mode yield analysis of complex-coupled DFB lasers above threshold for various coupling coefficient ratios and facet reflectivity combinations (문턱 전류 이상에서 Complex-Coupled DFB 레이저 다이오드의 여러 가지 결합 계수 비와 양 단면 반사율 조합에 따른 단일 모드 수율 해석)

  • 김부균;김상택;전재두
    • Korean Journal of Optics and Photonics
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    • v.14 no.5
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    • pp.521-529
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    • 2003
  • For complex-coupled (CC) DFB lasers, we found that there might be little correlation between the single mode yields at threshold and above threshold. At threshold, the single mode yield considering f number of in-phase (IP) CC DFB lasers is the same as that of anti-phase (AP) CC DFB lasers. However, the single mode yield as a function of injection current above threshold of IP CC DFB lasers is much different from that of AP CC DFB lasers. In the case of IP CC DFB lasers, the single mode yield increases as the coupling coefficient ratio (CR) increases, while, in the case of AP CC DFB lasers, the single mode yield decreases rapidly regardless of CR as the injection current increases. In the case of AR-HR combinations, the effect of AR ref1ectivity on the single mode yield increases as the coupling strength decreases. As the coupling strength decreases, the CR at which the increase rate of the single mode yield starts to decrease, increases, and the maximum single mode yield increases. Single mode yields of AR-HR and AR-AR combinations are larger than those of AR-CL and CL-CL combinations.

A Study on Radio-Protection Mechanism of Platelet Cells After Injection of Alliin (알리인 투여 후 혈소판의 방사선 방어기전 연구)

  • Ji, Tae-Jeong
    • Journal of radiological science and technology
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    • v.33 no.3
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    • pp.185-192
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    • 2010
  • Platelets originating from Megakaryocyte are sensitive to radiation along with white blood cells, and thus these platelets are used as an index of radiation hazard as they decrease in advance. Thus, when there is a scarcity of platelets, dot hemorrhage occurs and it leads to decrease of blood corpuscle and a decline in immunity. In particular, when 4~6 Gy whole body irradiation is received, after three weeks, the platelets will decrease to the lowest level, which can be a cause of death by bleeding and anemia. Therefore, this study tried to identify the mechanism of platelet damage and protection effect. The protection substance used in the experiment is Alliin, which is a component of garlic, and it was observed by an Transmission Electron Microscope(TEM) after its injection to the rat's tail vein. In the study, it was found that the cell membrane was severely damaged in a 10-day progressed platelet organ after receiving 5 Gy irradiation. It billowed as balloon-like figure and the glycocalyx became hyperplasia. The minute organ was damaged to the point that it was beyond recognition in a 20-day progressed platelet organ after receiving irradiation, and the cytoplasmic contents were exposed to epilepsy parts and outrageously damaged. Furthermore, the form of granules could also not be observed. A hole was formed in the middle, and the damaged organ was found in a 30-day progressed platelet. However, the form of granules was consistently maintained in the experiment group injecting Alliin, as with the control group, and there was no damage to the cell membrane recognized. Thus, it was possible to verify the effectiveness of radiation protection of the platelet when Alliin was injected to the blood vessel.

Preparation and Characterization of White Polymer Light Emitting Diodes using PFO:MEH-PPV (PFO:MEH-PPV를 이용한 White PLED의 제작과 특성평가)

  • Shin, Sang-Baie;Gong, Su-Choel;Park, Hyung-Ho;Jeon, Hyeong-Tag;Chang, Ho-Jung
    • Journal of the Microelectronics and Packaging Society
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    • v.15 no.4
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    • pp.59-64
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    • 2008
  • In this paper, white polymer light emitting diodes(WPLEDs) were fabricated and investigated the electrical and optical properties for the prepared devices. ITO(indium tin oxide) and PEDOT:PSS [poly(3,4-ethylenedioxythiophene):poly(styrene sulfolnate)] as anode and hole injection materials, PFO [poly(9,9-dioctylfluorene)] and MEH-PPV [poly(2-methoxy-5(2-ethylhe xoxy)-1,4-phenylenevinyle)] were used as the light emitting host and guest materials, respectively. The LiF(lithium flouride) and Al(aluminum) were used electron injection materials and cathode materials. Finally, the WPLED with structure of ITO/PEDOT:PSS/PFO:MEH-PPV/LiF/Al was fabricated. The prepared WPLED showed white emission with CIE coordinates of (x=0.36, y=0.35) at the applied voltage of 9V. The maximum current density and luminance were about $740mA/cm^2\;and\;900cd/m^2$ at 13V, respectively. And the maximum current efficiency was 0.37 cd/A at $200cd/m^2$ in luminance.

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Effect of nozzle diameter on the reduction of smoke emission from naval ship diesel engines (함정용 디젤엔진의 노즐 직경 변화가 매연 발생에 미치는 영향)

  • Son, Min-Soo;Choi, Jae-Sung;Cho, Kwon-Hae
    • Journal of Advanced Marine Engineering and Technology
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    • v.40 no.3
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    • pp.180-184
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    • 2016
  • Legislative and regulatory actions regarding the exhaust gas from ships are being strengthened by both international organizations and national governments, to protect human health and the environment. Exhaust gas traps are excluded from exhaust gas regulation applications, but, recently, the United States, Britain, and other developed countries have examined a variety of ways to improve the system, including the introduction of electric propulsion systems to prevent air pollution generated by naval ships. This study investigates a large number of smoke problems of naval diesel engines to verify the effect of improving the nozzle characteristics. An exhaust gas emission measurement method to determine the quality of pollutant exhaust gas generated during low-load operation is proposed through the research methodology of the smoke problem. It was confirmed that the emissions value is improved by decreasing the nozzle hole diameter and increasing the injection pressure. At the same time, the flow rate decrease equation and setting up a test memo based on the nozzle diameter confirmed that the fuel consumption, to which the nozzle diameter in the flow path is related, is reduced.

In-situ Thermally Curable Hyper-branched 10H-butylphenothiazine

  • Jo, Mi-Young;Lim, Youn-Hee;Ahn, Byung-Hyun;Lee, Gun-Dae;Kim, Joo-Hyun
    • Bulletin of the Korean Chemical Society
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    • v.33 no.2
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    • pp.492-498
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    • 2012
  • A hyper branched 10-butylphenothiazine with in-situ thermally curable methacrylate (1,3,5-tris-[$\{$10-Butyl-3-(4-(2-methyl-acryloyloxy)-phenyl)-7-yl-10H-phenothiazine$\}$]-benzene, (tris-PTMA)) was synthesized successfully. From the TGA thermogram of tris-PTMA was thermally stable up to $336^{\circ}C$. In the first heating scan of DSC thermogram, tris-PTMA showed glass transition temperature (Tg) at $140^{\circ}C$ and broad endothermic process in the region of $144-179^{\circ}C$, which is thermally curing temperature. In the second heating process, $T_g$ exhibited at $158.7^{\circ}C$ and endothermic process was not observed. Thermally cured tris-PTMA showed no big change in the UV-visible spectrum after washing with organic solvent such as methylene chloride, chloroform, toluene, indicating that thermally cured film was very good solvent resistance. Thermally cured tris-PTMA was electrochemically stable and the HOMO energy level of tris-PTMA was -5.54 eV. The maximum luminance efficiency of double layer structured polymer light-emitting diode based on in-situ thermally cured tris-PTMA was 0.685 cd/A at 16.0 V, which was higher than that of the device without thermally cured tris-PTMA (0.348 cd/A at 15.0 V).