• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.553-556
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• 1999

This paper presents a proper condition to achieve above 19 % conversion efficiency using PC1D simulator. Cast poly-Si wafers with resistivity of 1 $\Omega$-cm and thickness of 250 ${\mu}{\textrm}{m}$ were used as a starting material. Various efficiency influencing parameters such as rear surface recombination velocity and minority carrier diffusion length in the base region, front surface recombination velocity, junction depth and doping concentration in the Emitter layer, BSF thickness and doping concentration were investigated. Optimized cell parameters were given as rear surface recombination of 1000 cm/s, minority carrier diffusion length in the base region 200 ${\mu}{\textrm}{m}$, front surface recombination velocity 100 cnt/s, sheet resistivity of emitter layer 100 $\Omega$/$\square$, BSF thickness 5 ${\mu}{\textrm}{m}$, doping concentration 5$\times$10$^{19}$ cm$^3$ . Among the investigated variables, we learn that a diffusion length of base layer acts as a key factor to achieve conversion efficiency higher than 19 %. Further details of simulation parameters and their effects to cell characteristics are discussed in this paper.

• Journal of the Korean Vacuum Society
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• v.21 no.1
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• pp.62-68
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• 2012

The conversion efficiency of solar cells depending on incident angle of light is important for building-integrated photovoltaics (BIPV) applications. The quantum efficiency is the ratio of the number of charge carriers collected by the solar cell to the number of photons of a given energy shining on the solar cell. The analysis of angle dependence of quantum efficiencies give more information upon the variation of power output of a solar cell by the incident angle of light. The variations in power output of solar cells with increasing angle of incidence is different for the type of cell structures. In this study we present the results of the quantum efficiency measurement of single-crystalline silicon solar cells and a-Si:H thin-film solar cells with the angle of incidence of light. As a result, as the angle of incidence increases in single-crystalline silicon solar cells, quantum efficiency at all wavelength (300~1,100 nm) of light were reduced. But in case of a-Si:H thin-film solar cells, quantum efficiency was increased or maintained at the angle of incidence from 0 degree to about 40 degrees and dramatically decrease at more than 40 degrees in the range of visible light. This results of quantum efficiency with increasing incident angle were caused by haze and interference effects in thin-film structure. Thus, the structural optimization considering incident angle dependence of solar cells is expected to benefit BIPV.

• Korean Journal of Construction Engineering and Management
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• v.18 no.5
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• pp.11-19
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• 2017

The purpose of this study is to analyze the efficiency of PV according to installation condition in the complex type buildings. For this purpose, annual performance of solar power generation in a certain area was investigated and various methods were conducted including post operation evaluation. In addition, we tried to find out influencing factors that affect the efficiency and sought to identify their relative impact of degree through the data analysis and site visits together. In the middle of this process we can draw up major considerations for the efficient photovoltaic power generation installation. In the mean while, previous studies are making something new related with method for efficiency enhancement and individual influential factors based on experimental environment rather than the empirical data site based. As a result of the study, it was confirmed that even if installed in the same area, the power generation efficiency is 1.5 times as high as the installation condition. Furthermore, statistical analyses were performed on azimuth, tilted angle and shade, which are variables affecting conversion efficiency, and it was statistically confirmed that all variables are meaningful factors that affect the conversion efficiency which is a dependent variable. The most influential factor is the azimuth, followed by the tilted angle and the shade factor. From this result, we expect to be able to provide installation guidelines for the solar power generation equipments on the rooftop zone.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.247.1-247.1
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• 2016

Low-cost, high efficiency solar cells are tremendous interests for the realization of a renewable and clean energy source. ZnTe based solar cells have a possibility of high efficiency with formation of an intermediated energy band structure by impurity doping. In this work, ZnO/ZnTe:Cr and ZnO/i-ZnTe structures were fabricated by pulsed laser deposition (PLD) technique. A pulsed (10 Hz) Nd:YAG laser operating at a wavelength of 266 nm was used to produce a plasma plume from an ablated a ZnTe target, whose density of laser energy was 10 J/cm2. The base pressure of the chamber was kept at approximately $4{\times}10-7Torr$. ZnTe:Cr and i-ZnTe thin films with thickness of 210 nm were grown on p-Si substrate, respectively, and then ZnO thin films with thickness of 150 nm were grown on ZnTe:Cr layer under oxygen partial pressure of 3 mTorr. Growth temperature of all the films was set to $250^{\circ}C$. For fabricating ZnO/i-ZnTe and ZnO/ZnTe:Cr solar cells, indium metal and Ti/Au grid patterns were deposited on back and front side of the solar cells by using thermal evaporator, respectively. From the fabricated ZnO/ZnTe:Cr and ZnO/i-ZnTe solar cell, dark currents were measured by using Keithley 2600. Solar cell parameters were obtained under Air Mass 1.5 Global solar simulator with an irradiation intensity of 100 mW/cm2, and then the photoelectric conversion efficiency values of ZnO/ZnTe:Cr and ZnO/i-ZnTe solar cells were measured at 1.5 % and 0.3 %, respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.34 no.1
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• pp.73-77
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• 2021

Inorganic-organic hybrid perovskite solar cells have demonstrated considerable improvements, reaching 25.5% of certified power conversion efficiency in 2020 from 3.8% in 2009. In normal structured perovskite solar cells, TiO2 electron-transporting materials require heat treatment process at a high temperature over 450℃ to induce crystallinity. Inverted perovskite solar cells have also been studied to exclude the additional thermal process by using [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) as a non-oxide electron-transporting layer. However, the drawback of the PCBM layer is a charge accumulation at the interface between PCBM and a metal electrode. The impact of bathocuproin (BCP) buffer layer on photovoltaic performance has been investigated herein to solve the problem of PCBM. 2-mM BCP-modified perovskite solar cells were observed to exhibit a maximum efficiency of 12.03% compared with BCP-free counterparts (5.82%) due to the suppression of the charge accumulation at the PCBM-Au interface and the resulting reduction of the charge recombination between perovskite and the PCBM layer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.145-146
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• 2007

Dye-Sensitized Solar Cell Solar cells(DSSC) were appeared for overcoming global environmental problems and lack of fossil fuel problems. And it is one of study field that is getting into the spotlight lately because manufacturing method is more simple and inexpensive than existing silicon solar cells. Oxide semiconductor is used for adsorption of dye and electron transfer in DSSC study, and $TiO_2$ is used most usually. Overall light conversion efficiency is changed by several elements such as $TiO_2$ particle size and structure, pore size and shape. In this study, we report the solar cell performance of titania$(TiO_2)$ film electrodes with various particle sizes. $TiO_2$ particle size was 16 nm, 25 nm, and mixture of 16nm and 25 nm, and manufactured using Doctor blade method. When applied each $TiO_2$ film to DSSC, the best efficiency was found at 16nm of $TiO_2$ particle. 16nm of $TiO_2$ particle has the highest efficiency compared to the others, because particles with smaller diameters would adsorb more dye due to larger surface area. And in case of the mixture of 16nm and 25 nm, the surface area was smaller than expected. It is estimated that double layer is adsorbed a large amount of chemisorbed dye and improved light scattering leading due to efficiency concentration light than mono layer.

• Korean Chemical Engineering Research
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• v.48 no.4
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• pp.506-510
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• 2010

Electron recombinations in electrolyte solution reduce light-to-energy conversion efficiency at the nanoporous electrode surface of dye sensitized solar cells. In this study, we improved the conversion efficiency using an energy barrier at the nanoporous electrode surface to control the recombination process. The energy barrier was formed by coating nanoporous $TiO_2$ electrode with $Nb_2O_5$ material. We investigated the influence of energy barrier on the cell efficiency depending on the coating thickness. Nanoporous $TiO_2$ electrode was coated about 5 nm thickness by 12 times coatings, and so the coating layer was grown about 0.417 nm for every time. Enhancement of conversion efficiency from 2.55% to 4.25% was achieved at 0.834 nm coating thickness, and it was believed as the optimum thickness for minimizing the electron recombination process in our experimental system.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.86.2-86.2
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• 2015

Cu2ZnSn(S,Se)4 thin film solar cells have been fabricated using sputtered Cu/Sn/Zn metallic precursors on Mo coated sodalime glass substrate without using a toxic H2Se and H2S atmosphere. Cu/Sn/Zn metallic precursors with various thicknesses were prepared using DC magnetron sputtering process at room temperature. As-deposited metallic precursors were sulfo-selenized inside a graphite box containing S and Se pellets using rapid thermal processing furnace at various sulfur to selenium (S/Se) compositional ratio. Thin film solar cells were fabricated after sulfo-selenization process using a 65 nm CdS buffer, a 40 nm intrinsic ZnO, a 400 nm Al doped ZnO, and Al/Ni top metal contact. Effects of sulfur to selenium (S/Se) compositional ratio on the microstructure, crystallinity, electrical properties, and cell efficiencies have been studied using X-ray diffraction, Raman spectroscopy, field emission scanning electron microscope, I-V measurement system, solar simulator, quantum efficiency measurement system, and time resolved photoluminescence spectrometer. Our fabricated Cu2ZnSn(S,Se)4 thin film solar cell shows the best conversion efficiency of 9.24 % (Voc : 454.6 mV, Jsc : 32.14 mA/cm2, FF : 63.29 %, and active area : 0.433 cm2), which is the highest efficiency among Cu2ZnSn(S,Se)4 thin film solar cells prepared using sputter deposited metallic precursors and without using a toxic H2Se gas. Details about other experimental results will be discussed during the presentation.

• 한국태양에너지학회:학술대회논문집
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• 2009.04a
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• pp.230-234
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• 2009

It is significant technique to increase competitiveness that solar cells have a high energy conversion efficiency and cost effectiveness. When making high efficiency crystalline Si solar cells, evaporated Ti/Pd/Ag contact system is widely used in order to reduce the electrical resistance of the contact fingers. However, the evaporation process is no applicable to mass production because high vacuum is needed. Furthermore, those metals are too expensive to be applied for terrestrial applications. Ni/Cu/Ag contact system of silicon solar cells offers a relatively inexpensive method of making electrical contact. Ni silicide formation is one of the indispensable techniques for Ni/Cu/Ag contact sytem. Ni was electroless plated on the front grid pattern, After Ni electroless plating, the cells were annealed by RTP(Rapid Thermal Process). Ni silicide(NiSi) has certain advantages over Ti silicide($TiSi_2$), lower temperature anneal, one step anneal, low resistivity, low silicon consumption, low film stress, absence of reaction between the annealing ambient. Ni/Cu/Ag metallization scheme is an important process in the direction of cost reduction for solar cells of high efficiency. In this article we shall report an investigation of rapid thermal silicidation of nickel on silngle crystalline silicon wafers in the annealing range of $350-390^{\circ}C$. The samples annealed at temperatures from 350 to $390^{\circ}C$ have been analyzed by SEM(Scanning Electron Microscopy).

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.30 no.2
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• pp.61-65
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• 2020

The depletion of fossil fuels and the increase in environmental awareness have led to greater interest in renewable energy. In particular, solar cells have attracted attention because they can convert an infinite amount of solar energy into electricity. Dye-sensitize solar cells (DSSCs) are low cost third generation solar cells that can be manufactured using environmentally friendly materials. However, DSSC photoelectrodes are generally produced by screen printing, which requires high temperature heat treatment, and low temperature processes that can be used to produce flexible DSSCs are limited. To overcome these temperature limitations, this study fabricated photoelectrodes using room-temperature aerosol deposition. The resulting DSSCs had an energy conversion efficiency of 4.07 %. This shows that it is possible to produce DSSCs and flexible devices using room-temperature processes.