• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.6
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• pp.246-251
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• 2014

Recent studies have shown methods of improving solar cell efficiency. Especially on single crystalline silicon wafer which is high-efficiency solar cell material that has been widely studied. Interstitial oxygen (Oi) is the main impurity in the Czochralski (Cz) growing method, and excess of this can form precipitates during cell fabrication. We have demonstrated the effect of Oi impurity and oxygen precipitation concentration of the wafer on Cz-silicon solar cell efficiency. The result showed a decrease in cell efficiency as Oi and oxygen precipitation increase. Moreover, we have found that the critical point of [Oi] to bring higher cell efficiency is at 14.5 ppma in non-existent Bulk Micro Defect (BMD).

• Transactions on Electrical and Electronic Materials
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• v.5 no.2
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• pp.41-49
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• 2004

Layer transfer process has emerged as a promising tool in the field of thin silicon solar cell technology. This process can use mono-crystalline silicon as a surface for the epitaxial growth of a thin layer of silicon. It requires some sort of surface conditioning of the substrate due to which the surface become suitable for homo-epitaxy and lift off after solar cell fabrication. The successful reuse of substrate has been reported. The use of the conditioned surface without any kind of epitaxial layer growth is also the issue to be addressed. This review paper basically describes the five most cost effective methods on which works are in progress. Several types of possible problems envisaged by different research groups are also incorporated here with necessary discussion. Work in Korea has already started in this area in collaboration IC Design and Fabrication Centre, Jadavpur University, India and that also has been mentioned.

• 한국태양에너지학회:학술대회논문집
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• 2009.04a
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• pp.214-219
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• 2009

In high-efficiency crystalline silicon solar cells, If high-efficiency solar cells are to be commercialized. It is need to develop superior contact formation method and material that can be inexpensive and simple without degradation of the solar cells ability. For reason of plated metallic contact is not only high metallic purity but also inexpensive manufacture. It is available to apply mass production. Especially, Nickel, Copper and Silver are applied widely in various electronic manufactures as easily formation is available by plating. The metallic contact system of silicon solar cell must have several properties, such as low contact resistance, easy application and good adhesion. Ni is shown to be a suitable barrier to Cu diffusion as well as desirable contact metal to silicon. Nickel monosilicide(NiSi) has been suggested as a suitable silicide due to its lower resistivity, lower sintering temperature and lower layer stress than $TiSi_2$. Copper and Silver can be plated by electro & light-induced plating method. Light-induced plating makes use the photovoltaic effect of solar cell to deposite the metal on the front contact. The cell is immersed into the electrolytic plating bath and irradiated at the front side by light source, which leads to a current density in the front side grid. Electroless plated Ni/ Electro&light-induced plated Cu/ Light-induced plated Ag contact solar cells result in an energy conversion efficiency of 14.68 % on $0.2{\sim}0.6{\Omega}{\cdot}cm,\;20{\times}20mm^2$, CZ(Czochralski) wafer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.195-196
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• 2008

Doping depth, doping concentration, and resistivity of crystalline silicon solar cell are variables which take important portion in cell's efficiency. To get highly efficient solar cell, PC1D is used to calculate $I_{sc}$, $V_{oc}$, and $P_{max}$. Depth factor, peak doping, and base resistivity was used as variables. As a result, the optimized value of emitter peak doping is $1\times10^{19}cm^{-3}$, depth factor is $1{\mu}m$, and base $\rho$ is $ 0.1\Omega$-cm. Under the optimized condition, the solar cell gets efficiency 19.03(%).

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.65.2-65.2
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• 2011

일반적으로 결정질 실리콘 태양전지에서는 junction depth가 얕아짐으로써 단파장 영역에서의 수집효율이 향상되고 Jsc가 상승하기 때문에 junction depth가 얕은 것이 좋다. 또, 태양전지의 효율을 높이기 위해서는 낮은 재결합 속도가 필요한데 이를 위해서도 얕은 junction depth가 필요하다. 하지만 junction depth가 너무 얕으면 FF와 Voc가 낮아져 효율이 떨어지므로 junction depth를 최적화 할 필요가 있다. 본 논문에서는 PC1D 시뮬레이션을 사용하여 표면 농도를 고정시키고 junction depth를 가변하면서 이에 따른 cell의 parameter변화를 관찰하였다. 그 결과, 면저항 $120{\Omega}/{\square}$에서부터 효율이 saturation되었고, 그에 따른 parameter 값은 FF=76.28%, Jsc=$38.17mA/cm^2$, Voc=596.5V이며 junction depth가 $0.1726{\mu}m$일 때 효율은 17.37%이다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.9
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• pp.823-828
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• 2013

To reduce the cost per watt of photovoltaic power, it is important to reduce the cell thickness of crystalline silicon solar cells. As the thickness of the silicon layer is reduced, two distinctive thermal expansion rates between the silicon and the aluminum layer induce bowing in a solar cell. With a thinner silicon layer, the bowing distance grows exponentially. Excessive bowing could damage the silicon wafer. In this study, we tried to measure an irregularly curved silicon solar cell more accurately using a 3D image scanner. For the detailed analysis of the three-dimensional bowing shape, a least square fit was applied to the point data from the scanned image. It has been found that the bowing distance and shape distortion increase with a decrease in the thickness of the silicon layer. An Ag strip on top of the silicon layer can reduce the bowing distance.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.438-438
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• 2009

We have investigated the effect of forming gas annealing for Upgraded Metallurgical Grade (UMG)-silicon solar cell in order to obtain low-cost high-efficiency cell using post deposition anneal at a relatively low temperature. We have observed that high concentration hydrogenation effectively passivated the defects and improved the minority carrier lifetime, series resistance and conversion efficiency. It can be attributed to significantly improved hydrogen-passivation in high concentration hydrogen process. This improvement can be explained by the enhanced passivation of silicon solar cell with antireflection layer due to hydrogen re-incorporation. The results of this experiment represent a promising guideline for improving the high-efficiency solar cells by introducing an easy and low cost process of post hydrogenation in optimized condition.

• Solar Energy
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• v.17 no.1
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• pp.17-26
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• 1997

Since PESC(passivated emitter solar cell) was developed in 1985, high efficiency silicon solar cell technology based on planar technology has been improved in the order of PERC, Point Contact Solar Cell, PERL. BCSC and DSBC, which do not require photolithography, are expected to replace commercial screen printed cells because of its potential for low cost and high efficiency. In this paper, history and characteristics of each type of cells are reviewed.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.2
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• pp.55-62
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• 1992

Polycrystalline silicon ingots were manufactured using the casting method for polycrystalline silicon solar cells. These ingots were cut into wafers and ten n$^{+}$p type solar cells were made through the following simple process` surface etching, n$^{+}$p junction formation, metalization and annealing. For the grain boundary passivation, the samples were oxidized in O$_2$ for 5 min. at 80$0^{\circ}C$ prior to diffusion in Ar for 100 min. at 95$0^{\circ}C$. The conversion efficiency of polycrystalline silicon solar cells made from these wafers showed about 70-80% of those of the single crystalline silicon solar cell and superior conversion efficiency, compared to those of commercial polycrystalline wafers of Wacker Chemie. The maximum conversion efficiency of our wafers was indicated about 8%(without AR coating) in spite of such a simple fabrication method.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.11a
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• pp.78-81
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• 1994

The Photovoltaics(PV) industry has been evolving over the last 30 years and expanding because of a rising demand for clean and safe energy. Crystalline silicon solar cells will have increased performance and reduced cost in the future. In this paper solution growth process used to fabricate polycrystalline silicon thin film is considered.