• 한국재료학회:학술대회논문집
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• 한국재료학회 2010년도 춘계학술발표대회
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• pp.13-13
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• 2010

The solar energy conversion will take 10 % global energy need by 2033. A thin film type solar cell has been considered as one of the promising candidates for a large area applicable solar cell fabrication at a low cost. The metal-assisted growth of microcrystalline Si (mc-Si) films has been reported for a quality Si film synthesis at a low temperature. It discusses the spontaneous growth of a Si film above a metal-layer for a thin film solar cell. Quite recently, a substantial demand of nanomaterials has been addressed for cost-effective solar cells. The nanostructure provides a large photoactive surface at a fixed volume, which is an advantage in the effective use of solar power. But the promising of nanostructure active solar cell has not been much fulfilled due mainly to the difficulty in architecture of nanostructures. We present here the Si nanowire (SiNW)-embedded Schottky solar cell. Multiple SiNWs were connected to two different metals to form a Schottky or an ohmic contact according to the metal work function values. It discusses the scheme of rectifying contact between metals and SiNWs and the SiNW-embedded Schottky solar cell performances.

• 한국전기전자재료학회논문지
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• 제18권7호
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• pp.662-666
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• 2005

Silicon nitride $(SiN_x)$ film is a promising material for anti-reflection coating and passivation of multicrystalline silicon (me-Si) solar cells. In this work, a plasma-enhanced chemical vapor deposition (PECVD) system with batch-type reactor tube was used to prepare highly robust $SiN_x$ films for screen-printed mc-Si solar cells. The Gas flow ratio, $R=[SiH_4]/[NH_3]$, in a mixture of silane and ammonia was varied in the range of 0.0910.235 while maintaining the total flow rate of the process gases to 4,200 sccm. The refractive index of the $SiN_x$ film deposited with a gas flow ratio of 0.091 was measured to be 2.03 and increased to 2.37 as the gas flow ratio increased to 0.235. The highest efficiency of the cell was $14.99\%$ when the flow rate of $SiH_4$ was 350 sccm (R=0.091). Generally, we observed that the efficiency of the mc-Si solar cell decreased with increasing R. From the analysis of the reflectance and the quantum efficiency of the cell, the decrease in the efficiency was shown to originate mainly from an increase in the surface reflectance for a high flow rate of $SiH_4$ during the deposition of $SiN_x$ films.

• 한국표면공학회지
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• 제49권3호
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• pp.301-306
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• 2016

The effects of nanotexturing and post-etching on the reflection and quantum efficiency properties of diamond wire sawn (DWS) multicrystalline silicon (mc-Si) solar cell have been investigated. The chemical solutions, which are acidic etching solution (HF-$HNO_3$), metal assisted chemical etching (MAC etch) solutions ($AgNO_3$-HF-DI, HF-$H_2O_2$-DI) and post-etching solution (diluted KOH at $80^{\circ}C$), were used for micro- and nano-texturing at the surface of diamond wire sawn (DWS) mc-Si wafer. Experiments were performed with various post-etching time conditions in order to determine the optimized etching condition for solar cell. The reflectance of mc-Si wafer texturing with acidic etching solution showed a very high reflectance value of about 30% (w/o anti-reflection coating), which indicates the insufficient light absorption for solar cell. The formation of nano-texture on the surface of mc-Si contributed to the enhancement of light absorption. Also, post-etching time condition of 240 s was found adequate to the nano-texturing of mc-Si due to its high external quantum efficiency of about 30% at short wavelengths and high short circuit current density ($J_{sc}$) of $35.4mA/cm^2$.

• 한국진공학회지
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• 제20권3호
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• pp.225-232
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• 2011

다결정 실리콘 태양전지 표면의 광흡수율을 극대화시키기 위하여 플라즈마기반의 reactive ion etching (RIE) 공정을 적용하였으며 maskless 표면 texturing조건을 최적화하여 310~1,100 nm 파장대역의 평균 표면반사율을 $4{\pm}1%$ 내외로 감소시킬 수 있는 grass-like 한 블랙실리콘을 제조할 수 있었다. Saw damage를 가진 $15.6{\times}15.6\;cm^2$ bare 웨이퍼에서부터 중요 공정단계별로 처리된 시료들의 평균반사율, 표면형상, 소수운반자 수명 등의 위치분포를 측정하여 최종 제작된 태양전지의 광전변환효율과 외부양자효율 등과 비교 검토하여 고효율 다결정 실리콘 태양전지 양산에 필요한 표면 texturing 조건들을 연구하였다. 평균 반사율을 4% 이하로 감소시키는 texturing 공정조건에서 웨이퍼 중앙에서 가장자리로 갈 수록 표면구조의 깊이 2배 반치폭 3배의 불균일성이 발생하였으며 이에 따라 입사광자의 다중반사확률이 높아져 평균반사율이 1% 정도 낮아지는 것으로 밝혀졌다. 비반사막이 코팅된 시료에서 측정된 소수운반자수명분포도 중앙에서 가장자리로 갈수록 약 40% 이상 더 긴 수명을 갖는 것으로 밝혀져 표면구조의 크기에 따른 사이즈효과가 발생하는 것으로 판단된다. 제조된 태양전지의 위치에 따른 광전변환효율도 낮은 반사율과 더 긴 소수운반자수명을 갖는 가장자리에서 2% 가량 높은 광전변환효율을 보였으며, 380~1,100nm 파장대역의 외부양자효율 측정결과도 이를 뒷받침하고 있다. 균일한 에미터 층 형성 및 ARC 증착에 있어서 구조적으로 가장자리 부분의 구조가 유리한 것으로 예상되며, 동시에 표면 구조의 사이즈 효과 때문에 표면 재결합확률이 중앙보다 가장자리에서 더 감소되어 더 높은 광전변환효율을 보이는 것으로 해석된다.

• 공업화학
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• 제24권1호
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• pp.31-37
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• 2013

텍스쳐링에 의해 실리콘 웨이퍼의 표면반사율을 감소시키는 것은 실리콘 태양전지의 효율향상을 위해 매우 중요한 공정이다. 본 연구에서는 에칭속도 제어를 위해 촉매제를 포함한 산 용액으로 텍스쳐링 처리한 웨이퍼의 표면효과와 그 태양전지 특성을 평가 고찰하였다. 텍스쳐링 전 $HNO_3-H_2O_2-H_2O$ 용액의 전처리는 표면반사율의 초기 저감효과를 가져왔다. 이는 산화특성에 의해 유기 불순물이 제거되고 텍스쳐링을 위한 핵의 생성에 기인한다고 할 수 있다. 이후 공정에서 불산/질산 용액에 인산 및 초산과 같은 완충제를 첨가한 혼합용액을 제조하고, 적정 농도 조합과 그 처리시간의 최적화를 통해 개선된 텍스쳐링 효과를 얻을 수 있었으며 이 효과는 표면반사율 감소를 통해 확인할 수 있었다. 이렇게 제조된 실리콘 웨이퍼에 반사방지막 코팅 후 태양전지를 제작하여 그 변환효율을 측정한 결과 16.4%의 양호한 특성을 나타냈다. 이는 개선된 텍스쳐링 처리에 의해 저감된 표면특성에 의한 단락전류의 증가에 기인한 것으로 추정된다.

• Current Photovoltaic Research
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• 제7권4호
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• pp.130-133
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• 2019

The Ag crystallite formed during the formation of the front electrode forms a contact between the metal of the electrode and the emitter of the cell. Contact between the electrode and emitter plays an important role in collecting electrons generated by the solar cell. Therefore, Ag crystallite formation is an important factor. In order for solar cells to have good characteristics, it is important to understand the factors influencing the Ag crystallite formation. Factors affecting the formation of Ag crystallites include Si emitter, morphology, Si defect and firing temperature. The influence of surface morphology on Ag crystallite formation was confirmed throughout this study. In the case of fine texturing, the Ag crystallites were formed at the pointed parts. The finer the texturing, the sharper areas and more Ag crystallites were formed. This was confirmed by SEM image and FF calculation.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.243-243
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• 2010

This paper two different etching, HF : HNO3 :DI and RIE were used for etching in multi-crystalline Silicon(Mc-Si) solar cell fabrication. The wafers etched in RIE texture showed low reflectance compared to the wafers etched in Acid soultion after SiNx deposition. In light current-voltage results, the cells etched in RIE texture exhibited higher short circuit current and open circuit voltage than those of the cells etched in acid solution. We have obtained 15.1% conversion efficiency in large area($156cm^2$) Multi-Si solar cells etched in RIE texture.

• 한국세라믹학회지
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• 제46권6호
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• pp.685-688
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• 2009

Surface Texturing is very important process for high cell efficiency in crystalline silicon solar cell. Anisotropic texturing with an alkali etchant was known not to be able to produce uniform surface morphology in multi-crystalline silicon (mc-Si), because of its different etching rate with random crystal orientation. In order to reduce surface reflectance of mc-Si wafer, the general etching tendency was studied with HF/HN$O_3$/De-ionized Water acidic solution. And the surface structures of textured mc-Si in various HF/HN$O_3$ ratios were compared. The surface morphology and reflectance of textured silicon wafers were measured by FE-SEM and UVvisible spectrophotometer, respectively. We obtained average reflectance of $16{\sim}19$% for wavelength between 400 nm and 900 nm depending on different etching conditions.

• 신재생에너지
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• 제9권2호
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• pp.30-39
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• 2013

Multi-crystalline silicon solar cells is not exist a specific crystal direction different from single crystalline silicon solar cells. In functional materials, therefore, isotropic wet etching of mc-Si solar cell is easy the acid solution rather than the alkaline solution. The reflectance of wet texturing process is about 25% and the reflectance of RIE texturing process is achieved less than 10%. In addition, wet texturing has many disadvantages as well as reflectance. So wet texturing process has been replaced by a RIE texturing process. In order to apply BIPV, RIE and wet textured multi-crystalline silicon solar cell modules was manufactured by different kind of EVA sheet. Moreover, in case of BIPV, the short circuit current characteristics according to the angle of incidence is more important, because the installation of BIPV is fixed location. In this study, we has measured SEM image and I-V curve of RIE and wet textured silicon solar cell and PV module. Also we has analyzed quantum efficiency characteristics of RIE and wet textured silicon solar cell for PV modules depending on incidence angle.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 춘계학술발표대회 논문집
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• pp.293-298
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• 2011

The most widely used method to form an electrode in industrial solar cells are screen printing. Screen printing is characterized by a relatively simple and well-known production sequence with high throughput rates. However the method is difficult to implement a fine line width of high-efficiency solar cells can not be made. The open circuit voltage(Voc) and the short circuit current density(Jsc) and fill factor(FF) need to be further improved to increase the efficiency of silicon solar cells. In this study, gravure offset printing method using the multicrystalline-silicon solar cells were fabricated. Gravure off-set printing method which can print the fine line width of finger electrode can have the ability reduce the shaded area and increase the Jsc. Moreover it can make a high aspect ratio thereby series resistance is reduced and FF is increased. Approximately $50{\mu}m$ line width with $35{\mu}m$ height was achieved. The efficiency of gravure off set was 0.7% higher compare to that of scree printing method.