• 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.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.234-234
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• 2013

The counter electrodes in dye-sensitized solar cells (DSSCs) play roles in not only collecting electrons from external circuit but also reducing I3- to I- in electrolytes. Generally, conventional counter electrodes for DSSCs are prepared from the high temperature treatment of the H2PtCl6 precursor solution at $400^{\circ}C$ However, the more simplified fabrication process of counter electrodes is required for the commercialization of DSSCs. In this work, we developed novel fabrication process of counter electrodes using nano-second pulsed laser. DSSCs employing counter electrodes prepared by laser process showed conversion efficiency of 6.75% with short-circuit current of 12.73 mA/cm2, open-circuit voltage of 0.74 V and fill factor of 0.72. Closer investigating of photovoltaic properties will be reported.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 C
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• pp.1435-1438
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• 1994

The effects of Ge composition variation in $a-Si_{1-x}Ge_x:H$ alloy p-i-n solar cells on the physical properties and current density-voltage characteristics are analyzed by a new simulation modelling based on the update published experimental datas. The simulation modelling includes newly formulated density of gap density spectrum corresponding to Ge composition variation and utilizes the newly derived generation rate formulars which include the reflection coefficients and can apply to multijunction structures as well as single junction structure. The effects in $a-Si_{1-x}Ge_x:H$ single junction are analyzed through the efficiency, fill factor, open circuit voltage, short circuit current density, free carriers, trap carriers, electric field, generation rate and recombination rate. Based on the results analyzed in single junction structure, the applications to multiple junction structures are discussed and the optimal conditions reaching to a high performance are investigated.

• ETRI Journal
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• 제37권6호
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• pp.1129-1134
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• 2015

In this article, a study of a flower like nanostructured CdS buffer layer for improving the performance of a submicron-thick $CuIn_{1-x}Ga_xSe_2$ (CIGS) solar cell (SC) is presented. Both its synthesis and properties are discussed in detail. The surface reflectance of the device is dramatically decreased. SCs with flower like nanostructured CdS buffer layers enhance short-circuit current density, fill factor, and open-circuit voltage. These enhancements contribute to an increase in power conversion efficiency of about 55% on average compared to SCs that don't have a flower like nanostructured CdS buffer layer, despite them both having the same CIGS light absorbing layer.

• Journal of Electrochemical Science and Technology
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• 제1권2호
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• pp.69-74
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• 2010

Methodologies to improve photovoltaic performance of dye-sensitized solar cell (DSSC) are reviewed. DSSC is usually composed of a dye-adsorbed $TiO_2$ photoanode, a tri-iodide/iodide redox electrolyte and a Pt counter electrode. Among the photovoltaic parameters of short-circuit photocurrent density, open-circuit voltage and fill factor, short-circuit photocurrent density is the collective measure of light harvesting, charge separation and charge collection efficiencies. Internal quantum efficiency is known to reach almost 100%, which indicates that charge separation occurs without loss by recombination. Thus, light harvesting efficiency plays an important role in improvement of photocurrent. In this paper, technologies to improve light harvesting efficiency, including surface area improvement by nano-dispersion, size-dependent light scattering efficiency, bi-functional nano material, panchromatic absorption by selective positioning of three different dyes and transparent conductive oxide (TCO)-less DSSC, are introduced.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.391-392
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• 2008

A surface micromachined uncooled microbolometer based on the amorphous silicon was designed and fabricated. We designed the microbolometer with a pixel size of $35\times35$, $44\times44{\mu}m^2$ and a fill factor of about 70 % by considering such important factors as the thermal conductance, thermal time constant, the temperature coefficient of resistance, and device resistance. Finally, we successfully fabricated the microbolometer by using surface MEMS technology, and the properties of bolometer have been measured as such that TCR and absorptance can be achieved above -2.5%/K and about 90% with titanium layer, respectively.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.1130-1132
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• 2009

We propose a novel way for enhancement of efficiency on a quasi solid-state dye-sensitized solar cell (DSSC). It contained gel type electrolyte mixing the liquid crystal (LC) of specific concentration and applied voltage for alignment of the LC. Aligned LC is supported charge transfer inside electrolyte and efficiency is increased in DSSC. We made a quasi solid-state DSSC which applied DC voltage or not and have measured the power conversion efficiency (PCE) and the fill factor. From measurement, we obtain high performances in case of cell applied voltage compare to reference cell.

• 대한안전경영과학회지
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• 제4권2호
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• pp.199-207
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• 2002

The polycrystalline CdS of large scale were grown by chemical pyrolysis deposition for $Cu_2$S/CdS heterojunction solar cells. For high quality CdS polycrystalline thin films, the chemical solution was deposited on indium tin oxide(ITO) glasses at the temperature of 50$0^{\circ}C$ for 15 second and annealed at 35$0^{\circ}C$ for 20 minute or 50$0^{\circ}C$ for 30 second. To fabricate high efficiency solar cells, optical and electrical properties, morphology by SEM and x-ray diffraction on polycrystalline CdS thin films were investigated. From the I-V characteristics of $Cu_2$S/CdS heterojunction, the open circuit voltage, $V_{oc}$ was 0.7 V and the short circuit current, $I_{sc}$ was 4.2 mA. We found that the fill factor(FF) was 0.5 and the efficiency was 2.5%.

• JSTS:Journal of Semiconductor Technology and Science
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• 제15권3호
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• pp.390-396
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• 2015

This paper proposes a method to reduce flicker when running an AC-power direct-drive type multiple string LED driver IC. The proposed method greatly decreases flicker using one capacitor and P-type MOSFET transistor (PMOS). The flicker index (FI) was reduced by over 40% through experiments, and less than half of the conventional external components are used in the passive valley fill circuit, which gives an advantage in the cost and utilization in the design of LED lighting modules. The 0.35 um 700 V BCD process was used to manufacture this LED driver.

• Bulletin of the Korean Chemical Society
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• 제28권11호
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• pp.1973-1979
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• 2007

Novel organic dyes, JK-34, JK-35 and JK-36 containing bis-dimethylfluorenyl amino coumarin unit are designed and synthesized. Nanocrystalline TiO2 dye-sensitized solar cells were fabricated using these dyes. Under standard global AM 1.5 solar condition, the JK-34 sensitized cell gave a short circuit photocurrent density of 10.05 mA cm?2, open circuit voltage of 0.65 V, and a fill factor of 0.68, corresponding to an overall conversion efficiency η of 4.54%. We found that the power conversion efficiency was shown to be quite sensitive to the structural modifications of bridging thiophene moiety.