• 한국태양에너지학회 논문집
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• 제40권5호
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• pp.35-45
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• 2020

Photovoltaic (PV) power system prices have been steadily dropping in recent years due to their mass production and advances in relevant technology. Crystalline silicon (c-Si wafers) account for the largest share of the price of solar cells; reducing the thickness of these wafers is an essential part of increasing the price competitiveness of PV power systems. However, reducing the thickness of c-Si wafers is challenging; typically, phenomena such as bowing and cracking are encountered. While several approaches to address the bowing phenomenon of the c-Si solar cells exist, the only method to study the crack phenomenon (related to the strength of the c-Si solar cells) is the bending test method. Moreover, studies on determining the strength properties of the solar cells have focused largely on c-Si wafers, while those on the strength properties of front and rear-side electrodes and SiNx, the other components of c-Si solar cells, are scarce. In this study, we analyzed the strength characteristics of each layer of c-Si solar cells. The strength characteristics of the sawing mark direction produced during the production of c-Si wafers were also tested. Experiments were conducted using a 4bending tester for a specially manufactured c-Si solar cell. The results indicate that the back side electrode is the main component that experienced bowing, while the front electrode was the primary component regulating the strength of the c-Si solar cell.

• 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.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.209-209
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• 2012

High-efficient transparent conductive oxide (TCO) film-embedding Si heterojunction solar cells were fabricated. An additional doping was not applied for heterojunction solar cells due to the spontaneous junction formation between TCO films and an n-type Si substrate. Three different TCO coatings were formed by sputtering method for an Al-doped ZnO (AZO) film, an indium-tin-oxide (ITO) film and double stacks of ITO/AZO films. An improved crystalline ITO film was grown on an AZO template upon hetero-epitaxial growth. This double TCO films-embedding Si heterojunction solar cell provided significantly enhanced efficiency of 9.23% as compared to the single TCO/Si devices. The effective arrangement of TCO films (ITO/AZO) provides benefits of a lower front contact resistance and a smaller band offset to Si leading enhanced photovoltaic performances. This demonstrates a potential scheme of the effective TCO film-embedding heterojunction Si solar cells.

• Current Photovoltaic Research
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• 제11권4호
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• pp.114-117
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• 2023

Transparent Photovoltaic (PV) modules have recently been in the spotlight because they can be applied to buildings and vehicles. However, crystalline silicon (c-Si) solar modules, which account for about 90% of the PV module market, have the disadvantage of applying transparent PV modules due to their unique opacity. Recently, a see-through type PV module using a crystalline silicon solar strap has been developed. However, there is a problem due to a decrease in aesthetics due to the metal ribbon in the center of the see-through type PV module and difficulty bonding the metal ribbon due to the low voltage output of the strap. In this study, to solve this problem, we developed a fabrication process of series connected c-Si solar strap cells using the c-Si solar cells. We succeeded in fabricating a series connected strap with a width of 2-10 mm, and we plan to manufacture an aesthetic see-through type c-Si PV module.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 추계학술발표대회 논문집
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• pp.245-248
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• 2011

Many researches have been carried out to improve light absorption in the crystalline silicon solar cell fabrication. The rear reflection is applied to increase the path length of light, resulting in the light absorption enhancement and thus the efficiency improvement mainly due to increase in short circuit current. In this paper, we manufactured the silicon solar cell using the mono crystalline silicon wafers with $156{\times}156mm^2$, 0.5~3.0 ${\Omega}{\cdot}cm$ of resistivity and p-type. After saw damage removal, the dielectric film ($SiN_x$)on the back surface was deposited, followed by surface texturing in the KOH solution. It resulted in single-side texturing wafer. Then the dielectric film was removed in the HF solution. The silicon wafers were doped with phosphorus by $POCl_3$ with the sheet resistance 50 ${\Omega}/{\Box}$ and then the silicon nitride was deposited on the front surface by the PECVD with 80nm thickness. The electrodes were formed by screen-printing with Ag and Al paste for front and back surface, respectively. The reflectance and transmittance for the single-sided and double-sided textured wafers were compared. The double-sided textured wafer showed higher reflectance and lower transmittance at the long wavelength region, compared to single-sided. The completed crystalline silicon solar cells with different back surface texture showed the conversion efficiency of 17.4% for the single sided and 17.3% for the double sided. The efficiency improvement with single-sided textured solar cell resulted from reflectance increase on back surface and light absorption enhancement.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.91.2-91.2
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• 2010

The use of plated front contact for metallization of silicon solar cell may alternative technologies as a screen printed and silver paste contact. This technologies should allow the formation of contact with low contact resistivity a high line conductivity and also reduction of shading losses. The better performance of Ni/Cu contacts is attributed to the reduced series resistance due to better contact conductivity of Ni with Si and subsequent electroplating of Cu on Ni. The ability to pattern narrower grid lines for reduced light shading combined with the lower resistance of a metal silicide contact and improved conductivity of plated deposit. This improves the FF as the series resistance is deduced. This is very much required in the case of low concentrator solar cells in which the series resistance is one of the important and dominant parameter that affect the cell performance. A selective emitter structure with highly dopes regions underneath the metal contacts, is widely known to be one of the most promising high-efficiency solution in solar cell processing. This paper using selective emitter structure technique, fabricated Ni/Cu plating metallization cell with a cell efficiency of 17.19%.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.235-235
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• 2010

The Anti-reflection coating(ARC) properties can be formed on silicon substrate using a simple electrochemical etching technique. This etching step can be improve solar cell efficiency for a solar cell manufacturing process. This paper is based on the removal of silicon atoms from the surface a layer of porous silicon(PSi). Porous silicon is form by anodization and can be obtained in an electrolyte with hydrofluoric. It have demonstrated the feasibility of a very efficient porous Si layer, prepared by a simple, cost effective, electrochemical etching method. We expect our research can results approaching to lower than 10% of reflectance by optimization of process parametaer.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제52권10호
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• pp.447-450
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• 2003

This paper presents a process optimization of antireflection (AR) coating on crystalline Si solar cells. Theoretical and experimental investigations were performed on a double-layer AR (DLAR) coating of MgF$_2$/CeO$_2$. We investigated CeO$_2$ films as an AR layer because they have a proper refractive index of 2.46 and demonstrate the same lattice constant as Si substrate. RF sputter grown CeO$_2$ film showed strong dependence on a deposition temperature. The CeO$_2$ deposited at 40$0^{\circ}C$ exhibited a strong (111) preferred orientation and the lowest surface roughness of 6.87 $\AA$. Refractive index of MgF$_2$ film was measured as 1.386 for the most of growth temperature. An optimized DLAR coating showed a reflectance as low as 2.04% in the wavelengths ranged from 0.4${\mu}{\textrm}{m}$ to 1.1${\mu}{\textrm}{m}$. We achieved the efficiencies of solar cells greater than 15% with 3.12% improvement with DLAR coatings. Further details on MgF$_2$, CeO$_2$ films, and cell fabrication parameters are presented in this paper.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.52-52
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• 2011

A novel deposition process for n-type nanocrystalline silicon (n-type nc-Si) thin films at room temperature has been developed by adopting the neutral beam assisted chemical vapor deposition (NBa-CVD). During formation of n-type nc-Si thin film by the NBa-CVD process with silicon reflector electrode at room temperature, the energetic particles could induce enhance doping efficiency and crystalline phase in polymorphous-Si thin films without additional heating on substrate; The dark conductivity and substrate temperature of P-doped polymorphous~nano crystalline silicon thin films increased with increasing the reflector bias. The NB energy heating substrate(but lower than $80^{\circ}C$ and increase doping efficiency. This low temperature processed doped nano-crystalline can address key problem in applications from flexible display backplane thin film transistor to flexible solar cell.

• 한국전기전자재료학회논문지
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• 제26권1호
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• pp.73-79
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• 2013

Crystalline silicon solar cells with $SiN_x/SiN_x$ and $SiN_x/SiO_x$ double layer anti-reflection coatings(ARC) were studied in this paper. Optimizing passivation effect and optical properties of $SiN_x$ and $SiO_x$ layer deposited by PECVD was performed prior to double layer application. When the refractive index (n) of silicon nitride was varied in range of 1.9~2.3, silicon wafer deposited with silicon nitride layer of 80 nm thickness and n= 2.2 showed the effective lifetime of $1,370{\mu}m$. Silicon nitride with n= 1.9 had the smallest extinction coefficient among these conditions. Silicon oxide layer with 110 nm thickness and n= 1.46 showed the extinction coefficient spectrum near to zero in the 300~1,100 nm region, similar to silicon nitride with n= 1.9. Thus silicon nitride with n= 1.9 and silicon oxide with n= 1.46 would be proper as the upper ARC layer with low extinction coefficient, and silicon nitride with n=2.2 as the lower layer with good passivation effect. As a result, the double layer AR coated silicon wafer showed lower surface reflection and so more light absorption, compared with $SiN_x$ single layer. With the completed solar cell with $SiN_x/SiN_x$ of n= 2.2/1.9 and $SiN_x/SiO_x$ of n= 2.2/1.46, the electrical characteristics was improved as ${\Delta}V_{oc}$= 3.7 mV, ${\Delta}_{sc}=0.11mA/cm^2$ and ${\Delta}V_{oc}$=5.2 mV, ${\Delta}J_{sc}=0.23mA/cm^2$, respectively. It led to the efficiency improvement as 0.1% and 0.23%.