• 한국재료학회지
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• 제26권4호
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• pp.194-199
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• 2016

We prepared polymethyl methacrylate (PMMA) beads with a particle size of 80 nm to improve the energy conversion efficiency (ECE) by increasing the effective surface area and the dye absorption ability of the working electrodes (WEs) in a dye sensitized solar cell (DSSC). We prepared the $TiO_2$ layer with PMMA beads of 0.0~1.0 wt%; then, finally, a DSSC with $0.45cm^2$ active area was obtained. Optical microscopy, transmission electron microscopy, field emission scanning electron microscopy, and atomic force microscopy were used to characterize the microstructure of the $TiO_2$ layer with PMMA. UV-VIS-NIR was used to determine the optical absorbance of the WEs with PMMA. A solar simulator and a potentiostat were used to determine the photovoltaic properties of the PMMA-added DSSC. Analysis of the microstructure showed that pores of 200 nm were formed by the decomposition of PMMA. Also, root mean square values linearly increased as more PMMA was added. The absorbance in the visible light regime was found to increase as the degree of PMMA dispersion increased. The ECE increased from 4.91% to 5.35% when the amount of PMMA beads added was increased from 0.0 to 0.4 wt%. However, the ECE decreased when more than 0.6 wt% of PMMA was added. Thus, adding a proper amount of PMMA to the $TiO_2$ layer was determined to be an effective method for improving the ECE of a DSSC.

• 한국재료학회지
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• 제28권4호
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• pp.235-240
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• 2018

We propose a speedy two-step deposit process to form an Au electrode on hole transport layer(HTL) without any damage using a general thermal evaporator in a perovskite solar cell(PSC). An Au electrode with a thickness of 70 nm was prepared with one-step and two-step processes using a general thermal evaporator with a 30 cm source-substrate distance and $6.0{\times}10^{-6}$ torr vacuum. The one-step process deposits the Au film with the desirable thickness through a source power of 60 and 100 W at a time. The two-step process deposits a 7 nm-thick buffer layer with source power of 60, 70, and 80 W, and then deposits the remaining film thickness at higher source power of 80, 90, and 100 W. The photovoltaic properties and microstructure of these PSC devices with a glass/FTO/$TiO_2$/perovskite/HTL/Au electrode were measured by a solar simulator and field emission scanning electron microscope. The one-step process showed a low depo-temperature of $88.5^{\circ}C$ with a long deposition time of 90 minutes at 60 W. It showed a high depo-temperature of $135.4^{\circ}C$ with a short deposition time of 8 minutes at 100 W. All the samples showed an ECE lower than 2.8 % due to damage on the HTL. The two-step process offered an ECE higher than 6.25 % without HTL damage through a deposition temperature lower than $88^{\circ}C$ and a short deposition time within 20 minutes in general. Therefore, the proposed two-step process is favorable to produce an Au electrode layer for the PSC device with a general thermal evaporator.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 춘계학술대회 논문집 전력기술부문
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• pp.190-193
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• 2001

In order to verify the efficiency or availability and stability of photovoltaic(PV) generation systems, huge system apparatuses are needed, in general, in which an actual size of solar panel, a type of converter system and some amount of load facilities should be installed in a particular location. It is also hardly possible to compare a Maximum Power Point Tracking (MPPT) control scheme with others under the same weather and load conditions in an actual PV generation system. The only and a possible way to bring above-mentioned problem to be solved is to realize a transient simulation scheme for PV generation systems using real weather conditions such as insolation and surface temperature of solar cell. The authors, in this paper, introduces a novel simulation method, which is based on a real-time digital simulator (RTDS), for PV generation systems under the real weather conditions. Firstly, VI characteristic equation of a solar cell is developed as an empirical formula and reconstructed in the RTDS system, then the real data of weather conditions are interfaced to the analogue inputs of the RTDS. The outcomes of the simulation demonstrate the effectiveness of the proposed simulation scheme in this paper. The results shows that the cost effective verifying for the efficiency or availability and stability of PV generation systems and the comparison research of various control schemes like MPPT under the same real weather conditions are possible.

• 한국정보시스템학회지:정보시스템연구
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• 제27권2호
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• pp.95-114
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• 2018

Purpose The recent concern over environmental problems such as greenhouse gas emission and fine dust contributes increasing interest in renewable energies. However the intrinsic characteristics of renewable energies, intermittent and stochastic generation, might cause serious problems to the stability and controllability of power grid. Therefore countermeasures such as virtual power plant (VPP) must be prepared in advance of the spread of uncontrollable distributed renewable energy resources to be one of major energy sources. Design/methodology/approach This study deals with the design concept of the VPP platform. we proposed as a technology solution for achieving the stability of power grid by guaranteeing a single power profile combining multiple distributed power sources with ICT. The core characteristics of VPP should be able to participate in the grid operation by responding to operation instructions from the system operator, KPX, as well as the wholesale electricity market. Findings Therefore this study includes energy storage device(ESS) as a controllable component as well as renewable energy resources such as photovoltaic and wind power generation. Based on this configuration, we discussed core element technologies of VPP and protype design of VPP solution platform according to system requirements. In the proposed solution platform, UX design for the integrated control center and brokerage system were included as well as ancillary service function to respond to KPX's operation instruction with utilizing the capability of ESS. In addition, a simulator was suggested to verify the VPP operations.

• 한국재료학회지
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• 제27권2호
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• pp.94-99
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• 2017

Dinickel-silicide $(Ni_2Si)/glass$ was employed as a counter electrode for a dye-sensitized solar cell (DSSC) device. $Ni_2Si$ was formed by rapid thermal annealing (RTA) at $700^{\circ}C$ for 15 seconds of a 50 nm-Ni/50 nm-Si/glass structure. For comparison, $Ni_2Si$ on quartz was also prepared through conventional electric furnace annealing (CEA) at $800^{\circ}C$ for 30 minutes. XRD, XPS, and EDS line scanning of TEM were used to confirm the formation of $Ni_2Si$. TEM and CV were employed to confirm the microstructure and catalytic activity. Photovoltaic properties were examined using a solar simulator and potentiostat. XRD, XPS, and EDS line scanning results showed that both CEA and RTA successfully led to tne formation of nano $thick-Ni_2Si$ phase. The catalytic activity of $CEA-Ni_2Si$ and $RTA-Ni_2Si$ with respect to Pt were 68 % and 56 %. Energy conversion efficiencies (ECEs) of DSSCs with $CEA-Ni_2Si$ and $RTA-Ni_2Si$catalysts were 3.66 % and 3.16 %, respectively. Our results imply that nano-thick $Ni_2Si$ may be used to replace Pt as a reduction catalytic layer for a DSSCs. Moreover, we show that nano-thick $Ni_2Si$ can be made available on a low-cost glass substrate via the RTA process.

• 한국태양에너지학회 논문집
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• 제33권2호
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• pp.35-41
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• 2013

Dye-sensitized solar cell (DSC) allows light transmission and the application of various colors that make it especially suitable for building-integrated PV (BIPV) application. In order to apply DSC module into windows, it has to be panelized: DSC module should be protected with reinforced glass to the entire surface. Up to date, it seems to be common to make double glazing with DSC modules with air gaps between the glasses and the DSC modules. Few research has been conducted on the characteristics of various glazing types with DSC modules. This study aims to analyze the electrical performance of DSC modules according to panelizing method for glazing unit with DSC modules. The prototype of the DSC glazing that applied silicone filler between DSC modules and glasses was developed. The electrical performances of this type of DSC glazing with the filler and rather conventional double glazing with DSC modules were compared. Their performances were measured using a solar simulator that is suitable for DSC performance testing. The results indicated that the electrical performance of the filler type DSC glazing improved by 7% compared to that of the conventional DSC double glazing type.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.210-211
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• 2007

Amid booming PV(photovoltaic) industry, BIPV(Building Integrated PV) is one of the best fascinating PV application technologies. To apply PV in building, variable factors should be reflected such as installation position, shading, temperature effect and so on. Especially a temperature should be considered, for it affects both electrical efficiency of PV module and heating and cooling load in building. Transparent PV modules were designed as finished material for spandrels are presented in this paper. The temperature variation of the modules with and without air gap and insulation were compared and analyzed. The results showed that the module with air gap and insulation has a much larger temperature variation than another transparent module. The temperature of the module reached by 55degree C under vertical irradiance of lower 500$W/m^2$. And the temperature difference between these modules was about 15degree C. To analyze the output performance of module according to temperature variation, separate module was manufactured and measured by sun-simulator. The results showed that 1 degree temperature rise reduced about 0.45% of output power.

• 한국산학기술학회논문지
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• 제18권4호
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• pp.1-7
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• 2017

염료감응형 태양전지 촉매층으로 CoSi의 신뢰성을 확인하기 위해 전자빔증착기를 이용하여 100 nm-Co/300 nm-Si/quartz의 적층구조를 형성하고, $700^{\circ}C$-60분의 진공열처리하여 약 350 nm-CoSi를 형성하였다. 이때 잔류 Co를 제거하기 위해 $80^{\circ}C$-30%의 황산처리를 진행하였다. 또한 비교를 위해 100 nm-Pt/glass 상대전극을 준비하였다. CoSi 상대전극이 채용된 DSSC 소자의 신뢰성을 확인하기 위해 $80^{\circ}C$ 온도조건에서 0, 168, 336, 504, 672, 840시간동안 유지하였다. 이들을 채용한 DSSC 소자의 광전기적 특성을 분석하기 위해 solar simulator와 potentiostat을 이용하였다. CoSi 상대전극의 촉매활성도, 미세구조, 그리고 조성 분석을 확인하기 위해 CV, FE-SEM, FIB-SEM, EDS를 이용하여 분석하였다. 시간에 따른 에너지변환효율 결과, Pt와 CoSi 상대전극 모두 에너지변환효율이 504시간까지는 유지되다가 672시간 경과 후 처음의 50%로 감소하는 특성을 보였다. 촉매활성도 분석 결과, 시간이 지남에 따라 Pt와 CoSi 상대전극 모두 촉매활성도가 감소하여 각각 64%, 57%의 촉매활성도를 보였다. 미세구조 분석 결과, CoSi층은 전해질에 대한 안정성은 우수하였으나, 하부 쿼츠 기판과 CoSi층의 접촉면에 스트레스가 집중되어 국부적으로 크렉이 형성되며, 궁극적으로 ${\mu}m$급의 박리현상을 확인하였다. 따라서 CoSi 상대전극은 실리사이드화 되는 과정에서 잔류응력 때문에 열화가 일어나므로 신뢰성의 확보를 위해서는 이러한 잔류응력의 대책이 필요하였다.