• 제목/요약/키워드: trapping efficiency

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Red Organic Light-emitting Diodes utilizing Energy Transfer and Charge Trapping

  • Kim, Ju-Seung;Gu, Hal-Bon
    • Transactions on Electrical and Electronic Materials
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    • 제6권3호
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    • pp.91-96
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    • 2005
  • We report the efficient red light-emitting diodes based on the fluorescent dye 4-(dicyanomethylene)-2-i-propyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTI) and 5,6,11,12-tetraphenyl naphthacene (rubrene) codoped in the tris(8-hydroxyquinoline)aluminum $(Alq_3)$. Luminance efficiency of 2.2 cd/A with a Commission International De L'Eclairage (CIE) chromaticity coordinate of x, y = (0.640, 0:350) are achieved at the driving current density of $20\;mA/cm^2$. Adding the rubrene to the DCJTI in tris(8-hydroxyquinoline)aluminum $(Alq_3)$, the red color purity and luminance efficiency improved comparing to the DCJTI only doped devices because the rubrene molecules assist the polarization effect of DCJTI by molecular interaction and enhance the energy transfer from $(Alq_3)$ to DCJTI.

Analysis of Sediment Reduction with VFS and Diversion Channel with Enhancements in SWAT Landuse-Subbasin Overland Flow and VFS Modules

  • Park, Youn-Shik;Kim, Jong-Gun;Kim, Nam-Won;Engel, Bernie;Lim, Kyoung-Jae
    • 한국수자원학회:학술대회논문집
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    • 한국수자원학회 2009년도 학술발표회 초록집
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    • pp.752-757
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    • 2009
  • In the last decade, many methods such as greet chamber, reservoir, or debris barrier, have been utilized to manage and prevent muddy water problem. The Vegetative Filter Strip (VFS) has been thought to be one of the most effective methods to trap sediment effectively. The VFS are usually installed at the edge of agricultural areas adjacent to stream or drainage ditches, and it has been shown that the VFS effectively removes pollutants transported with upland runoff. But, if the VFS is installed without any scientific analysis of rainfall-runoff characteristics, soil erosion, and sediment analysis, it may not reduce the sediment as much as expected. Although Soil and Water Assessment Tool (SWAT) model has been used worldwide for many hydrologic and Non-Point Source Pollution (NPSP) analysis at a watershed scale. but it has many limitations in simulating the VFS. Because it considers only 'filter strip width' when the model estimates sediment trapping efficiency, and does not consider the routing of sediment with overland flow option which is expected to maximize the sediment trapping efficiency from upper agricultural subbasin to lower spatially-explicit filter strip. Therefore, the SWAT overland flow option between landuse-subbasins with sediment routing capability was enhanced with modifications in SWAT watershed configuration and SWAT engine. The enhanced SWAT can simulate the sediment trapping efficiency of the VFS in the similar way as the desktop VFSMOD-w system does. Also it now can simulate the effects of overland flow from upper subbasin to reflect the increased runoff volume at the receiving subbasin, which is what is occurring at the field if no diversion channel is installed. In this study, the enhanced SWAT model was applied to small watershed located at Jaun-ri in South Korea to simulate diversion channel and spatially-explicit VFS. It was found that approximately sediment can be reduced by 31%, 65%, 68%, with diversion channel, the VFS, and the VFS with diversion channel, respectively.

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트랩 종류와 수간내 위치가 광릉긴나무좀, Platypus koryoensis(딱정벌레목: 긴나무좀과) 포획에 미치는 영향 (Influence of Trap Type and Location on Tree Trunk on Platypus koryoensis (Coleoptera: Platypodidae) Trapping)

  • 김준헌;이정수;박일권;최원일
    • 한국응용곤충학회지
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    • 제49권2호
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    • pp.145-149
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    • 2010
  • 참나무시들음병 매개충인 광릉긴나무좀 (Platypus koryoensis (Murayama)) (Coleoptera: Platypodidae) 모니터링에 활용 가능한 트랩 종류, 색, 설치위치가 포획수에 미치는 영향이 조사되었다. 조사는 경기도 파주시 광탄면에서 수행되었으며 끈끈이 평판 트랩과 다중깔때기 트랩 두 종류 트랩이 이용되었다. 조사된 두 트랩의 종류는 광릉긴나무좀 포획수에 영향을 미치지 않았다. 끈끈이 평판 트랩의 경우 노란색, 검정색, 흰색, 투명색으로 시험한 결과 트랩색이 광릉긴나무좀 포획효율에 영향을 미치지 않았다. 끈끈이 평판 트랩과 다중깔때기 트랩 모두 수간내 경사 위쪽과 아래쪽에 설치된 경우, 산의 경사 위쪽에 설치한 트랩에 유의하게 많은 수의 광릉긴나무좀이 포획되었다. 이는 두 가지 트랩이 모두 광릉긴나무좀 모니터링 및 방제에 효율적으로 활용될 수 있음을 보여주는 것이다.

Controlled Charge Carrier Transport and Recombination for Efficient Electrophosphorescent OLED

  • Chin, Byung-Doo;Choi, Yu-Ri;Eo, Yong-Seok;Yu, Jai-Woong;Baek, Heume-Il;Lee, Chang-Hee
    • 한국정보디스플레이학회:학술대회논문집
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    • 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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    • pp.1418-1420
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    • 2008
  • In this paper, the light emitting efficiency, spectrum, and the lifetime of the phosphorescent devices, whose emission characteristics are strongly dominated not only by the energy transfer but also by the charge carrier trapping induced by the emissive dopant, are explained by differences in the energy levels of the host, dopant, and nearby transport layers. On the basis of our finding on device performance and photocurrent measurement data by time-of-flight (TOF), we investigated the effect of the difference of carrier trapping dopant and properties of the host materials on the efficiency roll-off of phosphorescent organic light emitting diode (OLED), along with a physical interpretation and practical design scheme, such as a multiple host system, for improving the efficiency and lifetime of devices.

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태양전지 텍스처 표면구조 개선 및 빛 흡수효율 향상에 관한 연구 - 식물 잎의 표면구조 적용 - (A study on improving the surface structure of solar cell and increasing the light absorbing efficiency - Applying the structure of leaves' surface -)

  • 김태민;홍주표
    • 한국신재생에너지학회:학술대회논문집
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    • 한국신재생에너지학회 2010년도 추계학술대회 초록집
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    • pp.38.2-38.2
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    • 2010
  • Biomimetc is a new domain of learning that proposes a solution getting clues from nature. There seems to be a sign of this phenomenon in fields of Renewable Energy. Foe example, Wind power was imitate the whale's fin that was improve efficiency of generating energy. This study focused on the photovoltaic generation as the instance of applying biomimetic. Efficiency is the most important factor in field of Photovoltaic generation. When given solar cell taking the sun light, most important fields of the study are absorb more light and increase the quantity of generation. For improving efficiency, the solar cell were builded up textures of taking a pyramid form, such a surface structure taking a role for remaining the light. This effects do the role as increasing absorbing efficiency. Such phenomenon calls Light Trapping, locking up the light on the surface of solar cell for a long time. Light is a vital factor to plants in the nature. Plants grow up through the photosynthesis that absorbing light for growth and propagation. So, plants make a effort how can absorb more the light in poor surroundings. This study set up a goal that imitates the minute surface structure of plants and applies to the existing solar cells's surface structure, so it can improve the efficiency of absorbing light. We used Light Tools software analyzing geometrical optics to analyze efficiency about new designed textures on the computer. We made a comparison between existing textures and new designed textures. Consequently, new designed textures were advanced efficiency, absorbing rates of light increasing about 7 percent. In comparison with existing and new textures, advancing about 20 percent in the efficient aspect.

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Charge Confinement and Interfacial Engineering of Electrophosphorescent OLED

  • Chin, Byung-Doo;Lee, Chang-Hee
    • 한국정보디스플레이학회:학술대회논문집
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    • 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권2호
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    • pp.1203-1205
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    • 2007
  • Confinement of charge carrier and exciton is the essential factor for enhancing the efficiency and stability of the electrophosphorescent devices. The interplay between the properties of emitters and other adjacent layers are studied based on the physical interpretation with difference of energy level, charge carrier mobility, and corresponding charge-trapping behavior.

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Plasma Textured Glass Surface Morphologies for Amorphous Silicon Thin Film Solar Cells-A review

  • Hussain, Shahzada Qamar;Balaji, Nagarajan;Kim, Sunbo;Raja, ayapal;Ahn, Shihyun;Park, Hyeongsik;Le, Anh Huy Tuan;Kang, Junyoung;Yi, Junsin;Razaq, Aamir
    • Transactions on Electrical and Electronic Materials
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    • 제17권2호
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    • pp.98-103
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    • 2016
  • The surface morphology of the front transparent conductive oxide (TCO) films plays a vital role in amorphous silicon thin film solar cells (a-Si TFSCs) due to their high transparency, conductivity and excellent light scattering properties. Recently, plasma textured glass surface morphologies received much attention for light trapping in a-Si TFSCs. We report various plasma textured glass surface morphologies for the high efficiency of a-Si TFSCs. Plasma textured glass surface morphologies showed high rms roughness, haze ratio with micro- and nano size surface features and are proposed for future high efficiency of a-Si TFSCs.

TCAD Simulation of Silicon Pillar Array Solar Cells

  • Lee, Hoong Joo
    • 반도체디스플레이기술학회지
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    • 제16권1호
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    • pp.65-69
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    • 2017
  • This paper presents a Technology-CAD (TCAD) simulation of the characteristics of crystalline Si pillar array solar cells. The junction depth and the surface concentration of the solar cells were optimized to obtain the targeted sheet resistance of the emitter region. The diffusion model was determined by calibrating the emitter doping profile of the microscale silicon pillars. The dimension parameters determining the pillar shape, such as width, height, and spacing were varied within a simulation window from ${\sim}2{\mu}m$ to $5{\mu}m$. The simulation showed that increasing pillar width (or diameter) and spacing resulted in the decrease of current density due to surface area loss, light trapping loss, and high reflectance. Although increasing pillar height might improve the chances of light trapping, the recombination loss due to the increase in the carrier's transfer length canceled out the positive effect to the photo-generation component of the current. The silicon pillars were experimentally formed by photoresist patterning and electroless etching. The laboratory results of a fabricated Si pillar solar cell showed the efficiency and the fill factor to be close to the simulation results.

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Single-Cycle 기법을 이용한 포핏밸브형 2-행정기관의 RSSV 형상에 따른 소기효율 측정에 관한 연구 (A Study on the Scavenging Efficiency Evaluation for the RSSV Configuration of 2-Stroke Engine with Popet Valve Type Using Single-Cycle Method)

  • 이진욱;강건용;정용일;이주헌;박정규
    • 한국자동차공학회논문집
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    • 제5권2호
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    • pp.69-79
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    • 1997
  • This paper deals with the measurement and analysis on the scavenging performance of the oppet-valve type two-stroke engine with different shroud system. The scavenging flow characteristics is investigated by flow visualization under steady condition, in which a dye is introduced into single-cycle method using the difference of specific gravity between two working fluids is used to evaluate the scavenging efficiency and the trapping efficiency. The 90° shroud system was found to be the highest efficiency system through both flow visualization and single-cycle test, as well as the shroud system to generally be efficient for reducing a short-circuiting flow during scavenging process in a two-stoke engine.

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