• Current Photovoltaic Research
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• v.8 no.3
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• pp.94-101
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• 2020

This study was trying to focus on achieving high efficiency of multi junction solar cell with thin film silicon solar cells. The proposed thin film Si-Ge/c-Si tandem junction solar cell concept with a combination of low-cost thin-film silicon solar cell technology and high-efficiency c-Si cells in a monolithically stacked configuration. The tandem junction solar cells using amorphous silicon germanium (a-SiGe:H) as an absorption layer of upper sub-cell were simulated through ASA (Advanced Semiconductor Analysis) simulator for acquiring the optimum structure. Graded Ge composition - effect of E_g profiling and inserted buffer layer between absorption layer and doped layer showed the improved current density (J_sc) and conversion efficiency (η). 13.11% conversion efficiency of the tandem junction solar cell was observed, which is a result of showing the possibility of thin film Si-Ge/c-Si tandem junction solar cell.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.419-419
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• 2016

High efficiency silicon solar cell requires the textured front surface to reduce reflectance and to improve the light trapping. In case of mono-crystalline silicon solar cell, wet etching with alkaline solution is widespread. However, the alkali texturing methods are ineffective in case of multi-crystalline silicon wafer due to grain boundary of random crystallographic orientation. The acid texturing method is generally used in multi-crystalline silicon wafer to reduce the surface reflectance. However the acid textured solar cell gives low short-circuit current due to high reflectivity while it improves the open-circuit voltage. To reduce the reflectivity of multi-crystalline silicon wafer, double texturing method with combination of acid and reactive ion etching is an attractive technical solution. In this paper, we have studied to optimize RIE experimental condition with change of RF power (100W, 150W, 200W, 250W, 300W). During experiment, the gas ratio of SF6 and O2 was fixed as 30:10.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.6
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• pp.1146-1150
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• 2009

Cadmium telluride (CdTe) is one of the most attractive photovoltaic materials due to its low cost, high efficiency and stable performance in physical, optical and electronic properties. Few researches on the influences of uniform surface on the photovoltaic characteristics in large-area CdTe solar cell were not reported. As the preceding study of the effects of thickness-uniformity on the photovoltaic characteristics for the large-area CdTe thin film solar cell, chemical mechanical polishing (CMP) process was investigated for an enhancement of thickness-uniformity. Removal rate of CdTe thin film was 3160 nm/min of the maximum value at the 200 $gf/cm^2$ of down force (pressure) and 60 rpm of table speed (velocity). The removal rate of CdTe thin film was more affected by the down force than the table speed which is the two main factors directly influencing on the removal rate in CMP process. RMS roughness and peak-to-valley roughness of CdTe thin film after CMP process were improved to 96.68% and 85.55%, respectively. The optimum process condition was estimated by 100 $gf/cm^2$ of down force and 60 rpm of table speed with the consideration of good removal uniformity about 5.0% as well as excellent surface roughness for the large-area CdTe solar cell.

• Transactions on Electrical and Electronic Materials
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• v.13 no.1
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• pp.35-38
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• 2012

In this study, we have attempted to characterize the photovoltaic effect in real-time measurement of photoinduced current in a poly-Si-based solar cell using photoconductive atomic force microscopy (PC-AFM). However, the high contact resistance that originates from the metal-semiconductor Schottky contact disturbs the current flow and makes it difficult to measure the photoinduced current. To solve this problem, a thin metallic film has been coated on the surface of the device, which successfully decreases the contact resistance. In the PC-AFM analysis, we used a metal-coated conducting cantilever tip as the top electrode of the solar cell and light from a halogen lamp was irradiated on the PC-AFM scanning region. As the light intensity becomes stronger, the current value increases up to $200{\mu}A$ at 80 W, as more electrons and hole carriers are generated because of the photovoltaic effect. The ratio of the conducting area at different conditions was calculated, and it showed a behavior similar to that generated by a photoinduced current. On analyzing the PC-AFM measurement results, we have verified the correlation between the light intensity and photoinduced current of the poly-Si-based solar cell in nanometer scale.

• Journal of Electrochemical Science and Technology
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• v.3 no.4
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• pp.149-153
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• 2012

Among the various solar-hydrogen production techniques a combination of a photovoltaic (PV) and an electrolytic cell into one single system, a monolithic PV-electrolytic cell, has been suggested as a promising one in terms of efficiency and stability. In this mini-review, we describe our recent efforts on the fabrication of the monolithic PV-electrolytic cell. Particularly, we focus on the electrocatalysts for water oxidation and its fabrication method suitable for a monolithic PV-electrolytic cell. We also introduce proto-type devices with a dye-sensitized solar cell module and an InGaP/GaAs photoelectrodes.

• Advances in Energy Research
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• v.5 no.1
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• pp.31-55
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• 2017

In the present study, PV/T collector was modeled via analysis of governing equations and physics of the problem. Specifications of solar radiation were computed based on geographical characteristics of the location and the corresponding time. Temperature of the collector plate was calculated as a function of time using the energy equations and temperature behavior of the photovoltaic cell was incorporated in the model with the aid of curve fitting. Subsequently, operational range for reaching to maximal efficiency was studied using Genetic Algorithm (GA) technique. Optimization was performed by defining an objective function based on equivalent value of electrical and thermal energies. Optimal values for equipment components were determined. The optimal value of water flow rate was approximately 1 gallon per minute (gpm). The collector angle was around 50 degrees, respectively. By selecting the optimal values of parameters, efficiency of photovoltaic collector was improved about 17% at initial moments of collector operation. Efficiency increase was around 5% at steady condition. It was demonstrated that utilization of photovoltaic collector can improve efficiency of solar energy-based systems.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.453-453
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• 2009

Wafer 태양전지와 Back sheet 및 기타 소재를 사용하는 기존의 Photovoltaic Module은 투과성이 존재하지 않으므로 본 논문에서는 태양전지 모듈의 투과특성을 발휘할 수 있는 Glass to Glass (GtG) Type의 Photovoltaic module에 대해 그 투과 특성 및 효율과의 관계를 분석하였다. 먼저 Module용 소재 중 Poly vinyl butyral (PVB) 및 Ethylene vinyl acetate(EVA) sheet의 Transmittance와 Haze 특성을 분석하였다. GtG 타입의 Photovoltaic Module은 약 90%정도의 투과율을 갖는 강화유리 및 Haze가 없는 PVB sheet를 사용하여 1m $\times$ 1m 크기로 제작하였다. GtG 타입으로 제조한 모둘 중 Cell 16EA를 사용한 모듈은 Cell 25EA를 사용한 모듈에 비해서 36% 투과율이 증가하였으나 효율 면에서 38%감소하였다. 최종적으로 GtG 타입 Module의 효율과 투과율에 관련된 식을 각각 정립하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.04a
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• pp.123-126
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• 2003

Recently, there is a growing concern on the photovoltaic effects using organic materials. This is a phenomena which converts the solar energy into the electrical one. We have fabricated a device structure of $ITO/PEDOT:PSS/CuPc/C_{60}/BCP/AI$. The PEDOT:PSS layer is made by spin coating, and the other organic layers are made by thermal vapor deposition. By measuring the current-voltage characteristics with an illumination of light, we have obtained value of Voc=0.38V, Jsc=$0.5mA/cm^{2}$. And a fill factor and efficiency are about 0.314 and 0.083%, respectively. A 500W xenon lamp(ORIEL) is used for a light source, and the light intensity illuminated into the device was about 10mW.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.505-506
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• 2007

Organic photovoltaic effects were studied in a device structure of ITO/CuPc/Al and ITO/CuPc/$C_{60}$/BCP/Al. A thickness of CuPc layer was varied from 10 nm to 50 nm, we have obtained that the optimum CuPc layer thickness is around 40 nm from the analysis of the current density-voltage characteristics in CuPc single layer photovoltaic cell. From the thickness-dependent photovoltaic effects in CuPc/$C_{60}$ heterojunction devices, higher power conversion efficiency was obtained in ITO/20nm CuPc/40nm $C_{60}$/Al, which has a thickness ratio (CuPc/$C_{60}$) of 1:2 rather than 1:1 or 1:3. Light intensity on the device was measured by calibrated Si-photodiode and radiometer/photometer of International Light Inc(IL 14004).

• 한국태양에너지학회:학술대회논문집
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• 2009.04a
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• pp.27-30
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• 2009

In this paper, we introduce the status of certificate test on crystalline silicon photovoltaic module in Korea. Up to 3. 2009, about 149 models have passed certificate test under KS C IEC61215 standard. Most products are from Korea, Japan, China. And some are from USA, German and Taiwan. A few environmental test items' results and standard test methods will be discussed. The detail discussion will be shown in the following paper.