KR102227333B1 - Method for compensation of pin-holes in CIGS photovoltaic absorber using In2S3-CdS hybrid buffer layer - Google Patents
Method for compensation of pin-holes in CIGS photovoltaic absorber using In2S3-CdS hybrid buffer layer Download PDFInfo
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Abstract
본 발명은 CIGS 박막태양전지에 사용되는 CIGS 광흡수층의 표면에 발생하는 핀홀을 감소하고 표면 거칠기를 완화할 수 있는 방법으로서, CIGS 광흡수층에 In2S3 버퍼층을 먼저 형성한 후 CdS 버퍼층을 형성하는 기술에 관한 것이다.The present invention is a method of reducing pinholes occurring on the surface of the CIGS light absorbing layer used in the CIGS thin film solar cell and alleviating the surface roughness.In the CIGS light absorbing layer, an In 2 S 3 buffer layer is first formed, and then a CdS buffer layer is formed. It is about the technology to do.
Description
본 발명은 화합물 박막태양전지에 관한 기술로서, 더욱 구체적으로는 CdS 버퍼층을 사용하는 CIGS 박막태양전지에 있어서, CIGS 광흡수층 표면에 형성되는 핀홀(Pin-hole)을 In2S3를 이용하여 채워주어 표면특성 및 박막태양전지 성능을 개선하는 기술에 관한 것이다.The present invention relates to a compound thin film solar cell, and more specifically, in a CIGS thin film solar cell using a CdS buffer layer, a pin-hole formed on the surface of the CIGS light absorption layer is filled with In 2 S 3. It relates to a technology for improving the subject surface characteristics and thin film solar cell performance.
주기율표의 IB족(Cu, Ag, Au), ⅢA족(B, Al, Ga, In, Ti) 및 VIA족(O, S, Se, Te, Po) 원소를 일부 포함하는 IB-ⅢA-VIA족 화합물 반도체는 박막태양전지 구조체를 위한 우수한 광흡수 p형 반도체이다. 특히, 상기 p형 반도체는 In과 Ga의 동시 사용 여부, Se과 S의 동시 사용 여부에 따라 CIS, CIGS, CIGSS[Cu(In1-yGay)(Se1-zSz)2, 여기서, 0≤y, z≤1] 등으로 구분하며, 본 발명에서는 설명의 편의상 상기와 같은 다양한 p형 반도체로 이루어진 박막을 통칭하여 "CIGS" 박막이라 호칭하기로 한다. Groups IB-IIIA-VIA including some of the elements of Group IB (Cu, Ag, Au), Group IIIA (B, Al, Ga, In, Ti) and Group VIA (O, S, Se, Te, Po) of the periodic table The compound semiconductor is an excellent light-absorbing p-type semiconductor for a thin film solar cell structure. In particular, the p-type semiconductor is CIS, CIGS, CIGSS[Cu(In 1-y Ga y )(Se 1-z S z ) 2 , where , 0≤y, z≤1], etc., in the present invention, for convenience of description, a thin film made of various p-type semiconductors as described above will be collectively referred to as a "CIGS" thin film.
화합물반도체 태양전지 중 Cu(InGa)Se2(CIGS) 박막태양전지는 높은 광 흡수계수를 가지고, 화합물내 조성조절이 가능하여 에너지 밴드갭(1.0~1.4eV)을 조절 할 수 있다. 또한 최고 셀 효율이 23% 이상을 기록하여 국내외적으로 많은 관심을 가지고 연구 중에 있다.Among compound semiconductor solar cells, Cu(InGa)Se 2 (CIGS) thin-film solar cells have a high light absorption coefficient and can control the composition in the compound, thereby controlling the energy band gap (1.0~1.4eV). In addition, the highest cell efficiency is recorded at over 23%, which is being studied with a lot of interest at home and abroad.
일반적으로 고효율 CIGS 박막은 (a)3단계 동시증발법(Three-stage co-evaporation)과 (b)금속전구체-셀렌화(metal-precursor selenization) 방법에 의해 제조되었으며, 지난 30여년간 실험실규모에서 최고효율의 CIGS 태양전지는 대부분 미국 신재생에너지연구소(National Renewable Energy Lab.)가 제안 및 특허출원한 "3단계 동시증발법"에 의해 제조되어 왔지만, 최근에 일본 솔라프론티어(Solar Frontier)사에서 "금속전구체-셀렌화"에 의해 제조한 CIGS 박막태양전지가 최고효율을 기록한 바 있다.In general, high-efficiency CIGS thin films were manufactured by (a) three-stage co-evaporation and (b) metal-precursor selenization. Most of the efficient CIGS solar cells have been manufactured by the "three-stage simultaneous evaporation method" proposed and applied for a patent by the National Renewable Energy Lab. The CIGS thin film solar cell manufactured by "metal precursor-selenization" recorded the highest efficiency.
3단계 동시증발법(Three-stage co-evaporation)과 금속전구체-셀렌화(metal-precursor selenization)에 의해 제조되는 CIGS 박막의 큰 차이점 중 하나는, 금속전구체-셀렌화 방법에 의해 제조되는 CIGS 박막의 표면이 3단계 동시증발법에 의해 제조되는 CIGS 박막의 표면에 비해 거칠다는 것이다. CIGS 광흡수층(또는 박막이라 혼용함)의 표면이 거칠게 되면 이후의 CIGS 광흡수층에 CdS층과 같은 버퍼층이 균일하게 형성되지 않고, 거친 표면에서 분로(Shunt path)가 발생하여 전자이동을 방해할 수 있다. One of the major differences between CIGS thin films produced by three-stage co-evaporation and metal-precursor selenization is the CIGS thin film produced by the metal precursor-selenization method. The surface of is rougher than the surface of the CIGS thin film produced by the three-step co-evaporation method. If the surface of the CIGS light absorbing layer (or mixed as a thin film) becomes rough, the buffer layer such as the CdS layer is not uniformly formed on the subsequent CIGS light absorbing layer, and a shunt path occurs on the rough surface, which may interfere with electron movement. have.
CIGS 박막태양전지의 버퍼층로 이용되는 물질의 종류는 CdS, In2S3, ZnO, ZnS(O,OH), Zn1-xMgXO, ZnSe 등이 있다. 이 중 가장 널리 사용되는 버퍼층은 CdS이나, Cd의 독성우려로 Cd 저감 혹은 Cd 없는 버퍼층에 대한 연구가 활발히 진행되어 왔다(예를 들어, 한국특허공개 10-2014-0081970, 미국특허공개 2012-0060900 등) . 대표적인 Cd 없는 버퍼층으로는 In2S3와 ZnS(O,OH)가 있으며, In2S3층의 경우에 CIGS 광흡수층에 증착하였을 때 CdS 버퍼층을 사용하였을 때보다 전기적 성능 중 단락전류(Short-circuit current: ISC)가 낮고, 개방전압(Open-circuit voltage: VOC)이 높게 나타나는 것으로 보고되고 있다. 또한 β-In2S3의 구조는 작은 "defect spinel" 구조이며, 나노 크기의 홀(hole) 내부를 채워줄 수 있을 정도로 작고 묽은 입자로 확인된다. Types of materials used as buffer layers of CIGS thin film solar cells include CdS, In 2 S 3 , ZnO, ZnS(O, OH), Zn 1-x Mg X O, and ZnSe. Among them, the most widely used buffer layer is CdS, but studies on Cd reduction or Cd-free buffer layer have been actively conducted due to concerns about toxicity of Cd (e.g., Korean Patent Publication 10-2014-0081970, US Patent Publication 2012-0060900 Etc) . Representative Cd-free buffer layers include In 2 S 3 and ZnS (O, OH). In the case of the In 2 S 3 layer, when deposited on the CIGS light absorbing layer, short-circuit current (short-circuit current) in electrical performance compared to when using the CdS buffer layer. It is reported that the circuit current: I SC ) is low and the open-circuit voltage (V OC) is high. In addition, the structure of β-In 2 S 3 is a small "defect spinel" structure, and it is identified as small and thin particles enough to fill the inside of nano-sized holes.
"금속전구체-셀렌화"에 의해 제조된 CIGS 박막태양전지의 표면을 개선하기 위하여 많은 표면 처리 기법을 연구 중인데, 대표적인 표면처리기법으로 NaF, KF를 이용한 PDT(post deposition treatment)가 있다. 이는 CIGS 광흡수층의 그레인바운더리(Grain boundary)를 더욱 부드럽게 하여 VOC 또는 JSC를 향상시키는 것으로 알려져 있으며, CIGS의 Cu 원자를 밀어냄으로써 Cu 부족상태를 만드는 것으로 알려져 있다. 또한, CIGS 박막의 밴드갭 및 전자-홀 재결합 속도에 영향을 주게 된다. 그러하여 CIGS 박막태양전지의 거친 표면이 그레인바운더리 변화에 의해 개선될 수 있도록 하면 태양전지의 전체적 효율이 향상 될 것으로 예상된다. In order to improve the surface of CIGS thin film solar cells manufactured by "metal precursor-selenization", many surface treatment techniques are being studied. As a representative surface treatment technique, there is a PDT (post deposition treatment) using NaF and KF. This is known to improve V OC or J SC by smoothing the grain boundary of the CIGS light absorbing layer, and is known to create a Cu deficiency state by repelling Cu atoms of CIGS. In addition, it affects the band gap and electron-hole recombination rate of the CIGS thin film. Therefore, if the rough surface of the CIGS thin film solar cell can be improved by the grain boundary change, the overall efficiency of the solar cell is expected to be improved.
하지만, KF, NaF 등을 이용한 PDT 기법이 아닌 CIGS 광흡수층과 CdS버퍼층 사이에 층을 하나 더 도입하여 표면을 개선해주는 방법에 대한 보고가 거의 없는 실정이다. 이에 본 발명에서는 거친 표면을 갖는 "금속전구체-셀렌화" 공정으로 증착된 CIGS 광흡수층과 CdS 버퍼층 사이에 신규한 완충층을 아주 얇게 증착함으로써, CIGS 광흡수층의 표면을 채워주거나 핀홀 부분을 메꾸어 주게 됨으로써, CIGS 광흡수층에서 발생하는 분로를 줄여주고, 더 나아가 이후에 증착될 CdS 버퍼층과 TCO층을 더욱 안정적이고 고르게 증착될 수 있도록 표면을 매끄럽게 할 수 있음을 보여주고자 연구를 한 결과 본 발명을 완성하게 되었다. However, there are few reports on a method of improving the surface by introducing an additional layer between the CIGS light absorbing layer and the CdS buffer layer, not the PDT technique using KF or NaF. Accordingly, in the present invention, a novel buffer layer is deposited very thinly between the CIGS light absorbing layer and the CdS buffer layer deposited by the "metal precursor-selenization" process having a rough surface, thereby filling the surface of the CIGS light absorbing layer or filling the pinhole portion. , The present invention was completed as a result of a study to show that the shunt generated in the CIGS light absorption layer can be reduced, and furthermore, the surface can be smoothed so that the CdS buffer layer and the TCO layer to be deposited later can be deposited more stably and evenly. Was done.
본 발명의 목적은 CIGS 광흡수층과 CdS 버퍼층을 포함하는 CIGS 박막태양전지에 있어서, 상기 CIGS 광흡수층의 핀홀을 메꾸어 줄 뿐만 아니라, CIGS 광흡수층의 거친 표면을 균일하게 만들어 줄 수 있는 CIGS 광흡수층의 핀홀 감소 방법을 제공하는 것이다.An object of the present invention is to provide a CIGS thin film solar cell including a CIGS light absorbing layer and a CdS buffer layer, in addition to filling the pinholes of the CIGS light absorbing layer, as well as making the rough surface of the CIGS light absorbing layer uniform. It is to provide a method of reducing pinholes.
특히, 본 발명의 목적은 CIGS 광흡수층과 CdS 버퍼층 사이에 새로운 층을 하나 더 증착하여 거친 표면의 CIGS 광흡수층의 핀홀을 메꾸어주고 전체적인 표면을 균일하게 만들어 줌으로써, CIGS 박막태양전지의 전력 발생 효율을 증가시킬 수 있는 기술을 제공하는 것을 목적으로 한다.In particular, the object of the present invention is to deposit a new layer between the CIGS light absorbing layer and the CdS buffer layer to fill the pinholes of the rough surface of the CIGS light absorbing layer and make the entire surface uniform, thereby improving the power generation efficiency of the CIGS thin film solar cell. It aims to provide technology that can be increased.
또한, 본 발명은 상기의 방법을 적용하여 전지 효율이 향상된 CIGS 박막태양전지를 제공하는 것을 목적으로 한다.In addition, an object of the present invention is to provide a CIGS thin film solar cell with improved battery efficiency by applying the above method.
본 발명은 기판에 하부전극을 형성하는 단계(1); 하부전극 위에 CIGS 광흡수층을 형성하는 단계(2); 상기 CIGS 광흡수층 위에 In2S3 버퍼층을 형성하는 단계(3); 상기 In2S3 버퍼층 위에 CdS 버퍼층을 형성하는 단계(4); 및 상기 CdS 버퍼층 위에 상부전극을 포함하는 나머지 층을 형성하는 단계(5)를 포함하는 CIGS 광흡수층의 핀홀 감소 효과를 갖는 CIGS 박막태양전지 제조 방법을 제공한다.The present invention comprises the steps of forming a lower electrode on a substrate (1); Forming a CIGS light absorbing layer on the lower electrode (2); Forming an In 2 S 3 buffer layer on the CIGS light absorption layer (3); Forming a CdS buffer layer on the In 2 S 3 buffer layer (4); And it provides a CIGS thin film solar cell manufacturing method having a pinhole reduction effect of the CIGS light absorption layer comprising the step (5) of forming the remaining layer including the upper electrode on the CdS buffer layer.
특히, 상기 CIGS 광흡수층은 금속전구체-셀렌화 공정 또는 3단계 동시증발법에 의해 형성될 수 있다.In particular, the CIGS light absorption layer may be formed by a metal precursor-selenization process or a three-step simultaneous evaporation method.
특히, 상기 In2S3은 CdS 버퍼층보다 두께가 얇게 형성되는 것이 바람직하다.In particular, the In 2 S 3 is preferably formed to be thinner than the CdS buffer layer.
특히, 상기 In2S3은 CBD(Chemical Bath Deposition)에 의해 형성할 수 있다.In particular, In 2 S 3 may be formed by CBD (Chemical Bath Deposition).
특히, 상기 CdS는 CBD(Chemical Bath Deposition)에 의해 형성할 수 있다.In particular, the CdS may be formed by CBD (Chemical Bath Deposition).
또한, 본 발명은 CIGS 광흡수층 및 CdS 버퍼층을 포함하는 CIGS 박막태양전지에 있어서, CIGS 광흡수층과 CdS 버퍼층 사이에 In2S3 버퍼층을 더 구비하는 CIGS 박막태양전지를 제공한다.In addition, the present invention provides a CIGS thin film solar cell further comprising an In 2 S 3 buffer layer between the CIGS light absorbing layer and the CdS buffer layer in the CIGS thin film solar cell including the CIGS light absorbing layer and the CdS buffer layer.
특히, 상기 CIGS 광흡수층은 금속전구체-셀렌화 공정 또는 3단계 동시증발법에 의해 형성될 수 있다.In particular, the CIGS light absorption layer may be formed by a metal precursor-selenization process or a three-step simultaneous evaporation method.
특히, 상기 In2S3 이중버퍼층은 CdS 버퍼층보다 두께가 얇게 형성되는 것이 바람직하다.In particular, the In 2 S 3 double buffer layer is preferably formed to be thinner than the CdS buffer layer.
특히, 상기 In2S3은 CBD(Chemical Bath Deposition)에 의해 형성할 수 있다.In particular, In 2 S 3 may be formed by CBD (Chemical Bath Deposition).
특히, 상기 CdS는 CBD(Chemical Bath Deposition)에 의해 형성할 수 있다.In particular, the CdS may be formed by CBD (Chemical Bath Deposition).
본 발명에서는 거친 표면을 갖는 "금속전구체-셀렌화" 공정으로 증착된 CIGS 광흡수층과 CdS 버퍼층 사이에 In2S3 버퍼층을 아주 얇게 증착함으로써, CIGS 광흡수층 표면에 존재하는 핀홀을 메꾸어주고 평평한 층을 형성해주어 CdS 버퍼층 증착이 더욱 원활하도록 해주며, 이로 인해 TCO층과 이후 공정도 모두 개선되도록 해주는 역할을 한다. 이로 인하여 CIGS 박막태양전지의 양자효율이 증가하고, 분로저항이 증가하여 전지 효율이 향상되게 된다. In the present invention, by depositing a very thin In 2 S 3 buffer layer between the CIGS light absorbing layer and the CdS buffer layer deposited by the "metal precursor-selenization" process having a rough surface, it fills the pinholes existing on the surface of the CIGS light absorbing layer and is a flat layer. The formation of the CdS buffer layer makes the deposition of the CdS buffer layer more smooth, and this plays a role in improving both the TCO layer and subsequent processes. As a result, the quantum efficiency of the CIGS thin film solar cell increases, and the shunt resistance increases, thereby improving the cell efficiency.
또한, 3단계 동시증발법에 의해 형성된 CIGS 광흡수층은 비록 금속전구체-셀렌화 공정으로 제조된 CIGS 광흡수층에 비해 핀홀 숫자도 적고 표면 상태가 양호하기는 하나, 본 발명의 방법은 3단계 동시증발법에 의해 제조된 CIGS 광흡수층의 핀홀을 감소시키고 표면을 더욱 안정화하는 데에도 사용 가능하다.In addition, the CIGS light-absorbing layer formed by the three-stage simultaneous evaporation method has fewer pinholes and a better surface condition than the CIGS light-absorbing layer produced by the metal precursor-selenization process. It can also be used to reduce pinholes and further stabilize the surface of the CIGS light absorption layer manufactured by the method.
도 1은 CBD 기법에 의해 CIGS 박막층에 In2S3 버퍼층(상부 도면) 및 CdS 버퍼층(하부 도면)을 형성하기 위한 CBD 기법을 설명하는 도면이다.
도 2는 본 발명 및 종래 방법에 의해 제조되는 CIGS 박막태양전지의 구조를 설명하는 도면이다.
도 3은 비교예로서 SLG/Mo/CIGS/CdS의 AFM을 이용한 표면 거칠기를 측정한 결과이다.
도 4는 본 발명의 방법에 의해 제조된 SLG/Mo/CIGS/In2S3/CdS의 AFM을 이용한 표면 거칠기를 측정한 결과이다.
도 5는 비교예의 SLG/MoCIGS/CdS와 본 발명의 SLG/Mo/CIGS/In2S3/CdS 샘플의 표면에 대한 SEM 측정 이미지이다.
도 6은 SLG 위에 각각 버퍼 필름으로서 (a) In2S3/CdS, (b) CdS, (c) In2S3 샘플들의 XRD 결과이다.
도 7은 SLG 위에 각각 버퍼 필름으로서 (a) In2S3/CdS, (b) CdS, (c) In2S3 샘플들의 라만 분광 결과이다.
도 8은 FTO/In2S3/CdS와 FTO/CdS 샘플의 UV/Visible spectroscopy 분광 결과이다.
도 9는 FTO/In2S3/CdS와 FTO/CdS 샘플들의 (Ahv)2-hv 커브이다.
도 10은 SLG/Mo/CIGS/In2S3/CdS와 SLG/Mo/CIGS/CdS 샘플의 단면 SEM 측정 결과이다.
도 11은 SLG/Mo/CIGS층에 CdS층과 In2S3/CdS층을 증착한 후 제작된 셀의 QE측정 결과이다. 1 is a diagram illustrating a CBD technique for forming an In 2 S 3 buffer layer (upper view) and a CdS buffer layer (lower view) on a CIGS thin film layer by a CBD technique.
2 is a diagram illustrating the structure of a CIGS thin film solar cell manufactured by the present invention and a conventional method.
3 is a result of measuring the surface roughness using AFM of SLG/Mo/CIGS/CdS as a comparative example.
4 is a result of measuring the surface roughness using AFM of SLG/Mo/CIGS/In 2 S 3 /CdS prepared by the method of the present invention.
5 is an SEM measurement image of the surface of the SLG/MoCIGS/CdS of Comparative Example and the SLG/Mo/CIGS/In 2 S 3 /CdS sample of the present invention.
6 is an XRD result of (a) In 2 S 3 /CdS, (b) CdS, (c) In 2 S 3 samples as buffer films on SLG, respectively.
7 is a Raman spectroscopy result of (a) In 2 S 3 /CdS, (b) CdS, (c) In 2 S 3 samples as buffer films on SLG, respectively.
8 is a result of UV/Visible spectroscopy spectroscopy of FTO/In 2 S 3 /CdS and FTO/CdS samples.
9 is a (Ahv ) 2 - hv curve of FTO/In 2 S 3 /CdS and FTO/CdS samples.
10 is a cross-sectional SEM measurement result of SLG/Mo/CIGS/In 2 S 3 /CdS and SLG/Mo/CIGS/CdS samples.
11 is a QE measurement result of a cell fabricated after depositing a CdS layer and an In 2 S 3 /CdS layer on a SLG/Mo/CIGS layer.
먼저, 본 발명에서는 설명의 편의상 "CIGS" 박막이라 호칭하기로 하나, 본 발명에서 사용된 용어 CIGS는 CIS, CIGS, CIGSS를 모두 포함하는 의미로 사용되었으며, 그 권리범위 역시 CIS 및 CIGSS를 포함하는 의미로 사용되었음을 밝힌다. First, in the present invention, for convenience of explanation, it will be referred to as a "CIGS" thin film, but the term CIGS used in the present invention has been used to include all of CIS, CIGS, and CIGSS, and the scope of rights also includes CIS and CIGSS. It reveals that it was used as a meaning.
본 발명의 방법은 3단계 동시증발법, 금속전구체-셀렌화 공정 등에 의해 제조된 CIGS 광흡수층의 표면에 있는 핀홀을 감소시키고 표면을 매끄럽게 하는 데 적용 가능하다. 특히, 금속전구체-셀렌화 공정에 의해 만들어지는 CIGS 광흡수층의 표면에 핀홀이 많이 생기며 거칠기 때문에 금속전구체-셀렌화 공정에 의해 제조된 CIGS 박막의 핀홀 감소에 본 발명이 매우 유용하다.The method of the present invention can be applied to reduce pinholes on the surface of the CIGS light absorbing layer produced by a three-stage simultaneous evaporation method, a metal precursor-selenization process, and the like and to smooth the surface. In particular, the present invention is very useful for reducing pinholes of CIGS thin films produced by metal precursor-selenization process because many pinholes are generated and rough on the surface of the CIGS light absorbing layer made by the metal precursor-selenization process.
본 발명은 CIGS 광흡수층의 표면에 형성되는 핀홀을 감소시키기 위하여 CIGS 박막태양전지의 제조 방법에 있어서, 기판에 하부전극을 형성하는 단계(1); 하부전극 위에 CIGS 광흡수층을 형성하는 단계(2); 상기 CIGS 광흡수층 위에 In2S3 버퍼층을 형성하는 단계(3); 상기 In2S3 버퍼층 위에 CdS 버퍼층을 형성하는 단계(4); 및 상기 CdS 버퍼층 위에 상부전극을 포함하는 나머지 층을 형성하는 단계(5)를 포함하는 CIGS 광흡수층의 핀홀 감소 효과를 갖는 CIGS 박막태양전지 제조 방법을 제공한다. 즉, 본 발명은 In2S3-CdS의 이중버퍼층을 사용함으로써, CIGS 광흡수층의 표면을 In2S3 버퍼층으로 개질한 후, CdS 버퍼층을 형성함으로써 분로 등을 줄이고 추후 TCO 등의 상부전극을 균일하게 형성할 수 있어, 전지 효율이 증가할 수 있다. The present invention provides a method for manufacturing a CIGS thin film solar cell in order to reduce pinholes formed on the surface of the CIGS light absorbing layer, the method comprising: forming a lower electrode on a substrate (1); Forming a CIGS light absorbing layer on the lower electrode (2); Forming an In 2 S 3 buffer layer on the CIGS light absorption layer (3); Forming a CdS buffer layer on the In 2 S 3 buffer layer (4); And it provides a CIGS thin film solar cell manufacturing method having a pinhole reduction effect of the CIGS light absorption layer comprising the step (5) of forming the remaining layer including the upper electrode on the CdS buffer layer. That is, in the present invention, by using a double buffer layer of In 2 S 3 -CdS, the surface of the CIGS light absorption layer is modified with an In 2 S 3 buffer layer, and then the shunt etc. are reduced by forming a CdS buffer layer, and the upper electrode such as TCO is later Since it can be formed uniformly, the battery efficiency can be increased.
본 발명에서 In2S3 버퍼층은 CIGS 광흡수층의 핀홀을 감소시키고, 표면을 균일하게 만드는 역할을 하기 때문에 CdS 버퍼층보다 얇게 형성하는 것이 바람직하다. In the present invention, the In 2 S 3 buffer layer is preferably formed to be thinner than the CdS buffer layer because it serves to reduce pinholes of the CIGS light absorbing layer and make the surface uniform.
본 발명에서 In2S3 버퍼층은 CIGS 광흡수층은 CBD 공정으로 형성할 수 있으나, 그 외의 방법으로 제조할 수도 있다.In the present invention, the In 2 S 3 buffer layer may be formed by the CBD process, but the CIGS light absorbing layer may be manufactured by other methods.
이하에서는 실험을 통하여 본 발명에 대하여 보다 자세히 설명하기로 한다.Hereinafter, the present invention will be described in more detail through experiments.
실시예Example
도 1은 CBD 기법에 의해 CIGS 박막층에 In2S3 층 및 CdS층을 형성하기 위한 CBD 기법을 설명하는 도면이다. 금속전구체-셀렌화 공정에 의해 제조된 Glass(SLG)/Mo/CIGS 형태의 CIGS 샘플을 이용하여, CBD(Chemical Bath Deoposition) 기법으로 In2S3와 CdS 층을 증착하였다. 1 is a diagram illustrating a CBD technique for forming an In 2 S 3 layer and a CdS layer on a CIGS thin film layer by a CBD technique. The In 2 S 3 and CdS layers were deposited by CBD (Chemical Bath Deoposition) using the CIGS sample in the form of Glass(SLG)/Mo/CIGS manufactured by the metal precursor-selenization process.
CIGS계 박막 위에 이중버퍼층으로 형성되는 In2S3층은 InCl3와 티오아세트아마이드(Thioacetamide)를 사용하는 CBD 기법을 이용하여 제조되었다. 티오아세트아마이드는 황이온을 방출하는 반면, InCl3는 인듐이온 공급원인 인듐염이다. In2S3의 CBD는 0.025M의 In 이온 공급원, 아세트산(2ml) 및 0.1M의 티오아세트아마이드 용액을 사용하여 수행되었다. 3가지 시약을 150ml의 증류수에 용해시킨 후, 용액을 이중비이커에 동시에 부어 총 부피 450ml의 최종 용액을 제조하였다. 이중비이커의 온도가 70℃에 도달하면, 혼합 된 용액을 교반(100rpm) 하고 테프론으로 이중비이커를 덮어주어 용액의 증발을 방지하였다. 용액의 온도가 58℃에 도달한 후, 샘플이 장착된 테프론 홀더를 사용하여 이중비이커에 넣고 용액 중에 수직으로 유지하였다. 2분간 증착 후, 모든 샘플을 증류수로 세척하고 N2 가스를 불어준 후 진공오븐(vacuum annealing oven)을 150℃로 하여 진공중에 열처리하였다. The In 2 S 3 layer formed as a double buffer layer on the CIGS thin film was prepared using a CBD technique using InCl 3 and thioacetamide. Thioacetamide releases sulfur ions, while InCl 3 is an indium salt that is a source of indium ions. CBD of In 2 S 3 was performed using a 0.025 M In ion source, acetic acid (2 ml) and a 0.1 M thioacetamide solution. After dissolving the three reagents in 150 ml of distilled water, the solution was simultaneously poured into a double beaker to prepare a final solution having a total volume of 450 ml. When the temperature of the double beaker reached 70°C, the mixed solution was stirred (100 rpm) and the double beaker was covered with Teflon to prevent evaporation of the solution. After the temperature of the solution reached 58° C., it was placed in a double beaker using a Teflon holder equipped with a sample and held vertically in the solution. After evaporation for 2 minutes, all samples were washed with distilled water and N 2 gas was blown, followed by heat treatment in a vacuum oven at 150°C.
CdS층은 CdSO4, 티오우레아(Thiourea)를 사용하는 CBD 기법을 이용하여 제조되었다. 티오우레아는 황 이온을 방출하는 우레아 성질이고, CdSO4는 카드뮴이온 공급원안 카드뮴 염이다. CdS을 제조하기 위한 CBD는 0.02M의 Cd 이온 공급원,0.25M의 티오우레아, 1.5M의 암모니아 용액을 사용하여 수행되었다. 3가지 시약을 150ml의 증류수에 용해시킨 후, 용액을 이중비이커에 동시에 부어 총 부피 450ml의 최종 용액을 제조하였다. 이중비이커의 온도가 80℃에 도달하면, 혼합된 용액을 교반(100rpm) 시키고 테프론으로 이중비이커를 덮어주어 용액의 증발을 방지하였다. 용액의 온도가 65℃에 도달한 후, 샘플이 장착된 테프론 홀더를 사용하여 이중비이커에 넣고 용액 중에 수직으로 유지시켰다. 10분간 증착 후, 모든 샘플을 증류수로 세척하고 N2가스를 불어준 후 진공오븐을 150℃로 하여 진공 중에 어닐링하였다. The CdS layer was prepared using a CBD technique using CdSO 4 and thiourea. Thiourea is a urea property that releases sulfur ions, and CdSO 4 is a cadmium salt from the source of cadmium ions. CBD to prepare CdS was performed using a 0.02M Cd ion source, 0.25M thiourea, 1.5M ammonia solution. After dissolving the three reagents in 150 ml of distilled water, the solution was simultaneously poured into a double beaker to prepare a final solution having a total volume of 450 ml. When the temperature of the double beaker reached 80° C., the mixed solution was stirred (100 rpm) and the double beaker was covered with Teflon to prevent evaporation of the solution. After the temperature of the solution reached 65° C., it was placed in a double beaker using a Teflon holder equipped with a sample and held vertically in the solution. After evaporation for 10 minutes, all samples were washed with distilled water and N 2 gas was blown, followed by annealing in a vacuum oven at 150°C.
그 결과, 도 2의 우측 도면과 같이 CBD 기법에 의해 CIGS 박막태양전지의 버퍼층을 증착하여 아래와 같이 SLG/Mo/CIGS/In2S3/CdS 구조를 형성하였다. 도 2의 좌측 도면은 종래의 CdS만을 버퍼층으로 사용한 SLG/Mo/CIGS/CdS 구조를 보여준다.As a result, the buffer layer of the CIGS thin film solar cell was deposited by the CBD technique as shown in the right figure of FIG. 2 to form the SLG/Mo/CIGS/In 2 S 3 /CdS structure as follows. The left drawing of FIG. 2 shows a conventional SLG/Mo/CIGS/CdS structure using only CdS as a buffer layer.
실험예 Experimental example
실험예 1 : InExperimental Example 1: In 22 SS 33 층 도입에 따른 CIGS/버퍼층의 표면 거칠기(roughness) 변화 및 표면상태 이미지 분석 실험Changes in surface roughness of CIGS/buffer layer and surface condition image analysis experiment according to layer introduction
박막 표면의 거칠기 측정을 정밀하게 분석해주는 AFM(Atomic Force Microscope) 장비를 이용하여, 버퍼층이 증착된 CIGS표면의 평균거칠기(average roughness, Ra) 값을 비교하였다. Using AFM (Atomic Force Microscope) equipment that precisely analyzes the roughness measurement of the thin film surface, the average roughness (Ra) value of the CIGS surface on which the buffer layer was deposited was compared.
도 3은 비교예로서 SLG/Mo/CIGS/CdS의 표면 거칠기를 측정한 결과이며, 도 4는 본 발명의 방법에 의해 제조된 SLG/Mo/CIGS/In2S3/CdS의 AFM을 이용한 거칠기를 측정한 결과이다. 3 is a result of measuring the surface roughness of SLG/Mo/CIGS/CdS as a comparative example, and FIG. 4 is a roughness using AFM of SLG/Mo/CIGS/In 2 S 3 /CdS manufactured by the method of the present invention. Is the result of measuring.
도 3 및 4의 AFM 측정 결과와 같이, CIGS 광흡수층 위에 CdS 버퍼층을 증착 해준 샘플은 대표적인 거칠기 파라미터인 Ra값이 318.069로 거칠게 분석되고, CIGS층 위에 In2S3층을 얇게 증착해 준 후에 CdS를 증착 해준 샘플은 Ra값이 70.079로 표면이 매우 균일하게 개선된 것을 확인할 수 있었다. 참고로, Ra값은 표면의 상태뿐만 아니라 결정크기, Void의 밀도 등 여러 요소에 의해 영향을 받는 것으로 알려져 있다.As shown in the AFM measurement results of FIGS. 3 and 4, the sample in which the CdS buffer layer was deposited on the CIGS light absorbing layer was roughly analyzed as 318.069, which is a typical roughness parameter, and the In 2 S 3 layer was deposited thinly on the CIGS layer and then CdS It was confirmed that the Ra value of the sample on which was deposited was 70.079, and the surface was very uniformly improved. For reference, it is known that the Ra value is affected not only by the state of the surface, but also by various factors such as the crystal size and the density of voids.
도 5는 비교예의 SLG/MoCIGS/CdS와 본 발명의 SLG/Mo/CIGS/In2S3/CdS 샘플의 표면에 대한 SEM 측정 이미지이다. 도 5와 같이, SEM으로 측정한 각 샘플의 표면 이미지에서 비교예의 CIGS 광흡수층 위에 CdS 버퍼층이 증착된 샘플을 보면 많은 핀홀이 확인되지만, 본 발명의 방법에 의해 제조된 CIGS 광흡수층 위에 In2S3/CdS로 증착된 샘플은 CIGS의 핀홀이 어느 정도는 채워져 있음을 확인할 수 있었다. 따라서 In2S3를 먼저 얇게 증착시켜 준 후에 CdS를 증착해 주면 CIGS 광흡수층의 핀홀을 줄여서 CdS층을 견고하게 증착할 수 있다는 것을 확인할 수 있었다.5 is an SEM measurement image of the surface of the SLG/MoCIGS/CdS of Comparative Example and the SLG/Mo/CIGS/In 2 S 3 /CdS sample of the present invention. 5, in the surface image of each sample measured by SEM, a sample in which a CdS buffer layer was deposited on the CIGS light absorbing layer of Comparative Example confirmed many pinholes, but In 2 S on the CIGS light absorbing layer prepared by the method of the present invention It was confirmed that the sample deposited with 3 /CdS was filled with the pinholes of CIGS to some extent. Therefore, it was confirmed that if In 2 S 3 was first deposited thinly and then CdS was deposited, the CdS layer could be firmly deposited by reducing the pinhole of the CIGS light absorbing layer.
즉, 종래 CdS층 단독으로 형성하는 것에 비하여, In2S3를 먼저 형성한 후, CdS를 형성하는 것이 CIGS 광흡수층의 표면의 핀홀 및 거칠기를 줄여줄 수 있어, CdS 및 TCO 층이 안정적으로 증착되어 결국 전지 효율이 향상되는 것이다.That is, compared to the conventional CdS layer alone, forming In 2 S 3 first and then forming CdS can reduce pinholes and roughness on the surface of the CIGS light absorbing layer, so that the CdS and TCO layers are stably deposited. As a result, battery efficiency is improved.
실험예 2 : InExperimental Example 2: In 22 SS 33 층 및 CdS층의 형성확인유무 및 정성분석결과Formation of layer and CdS layer and qualitative analysis result
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본 발명에 의해 제조된 SLG/Mo/CIGS/In2S3/CdS 샘플에서, 실제로 In2S3 및 CdS성분이 CIGS 위에 잘 형성되었는지 확인하기 위해 정성분석이 가능한 XRD(X-ray diffraction, 라만분광기(Raman spectrometer), UV/Visvible spectroscopy로 확인 하였다. 다만, 위 실험들은 CIGS가 존재하는 경우 CIGS로 인해 In2S3나 CdS가 분석이 되지 않기 때문에 SLG 위에 Mo와 CIGS 없는 상태에서 버퍼층을 형성하여 실험하였다.In the SLG / Mo / CIGS / In 2 S 3 / CdS samples produced according to the present invention, in fact, In 2 S 3 and qualitative analysis is possible XRD (X-ray diffraction to confirm that the CdS components are well formed on the CIGS, Raman However, in the above experiments, when CIGS is present, In 2 S 3 or CdS cannot be analyzed due to CIGS, so a buffer layer is formed on SLG in the absence of Mo and CIGS. And experimented.
도 6은 SLG 위에 각각 버퍼층으로서 (a)In2S3/CdS, (b)CdS, (c)In2S3를 갖는 샘플에 대해 XRD 결과이다. 6 shows XRD results for samples having (a)In 2 S 3 /CdS, (b)CdS, and (c)In 2 S 3 as buffer layers on the SLG, respectively.
도 6과 같이, 각 성분에 해당하는 2θ에 피크가 확인되어, 삼방정계(Trigonal) 및 육방정계(Hexagonal) 구조를 갖는 In2S3가 형성되었고, 입방정계(Cubic) 및 육방정계(Hexagonal) 구조를 갖는 CdS가 형성된 것을 확인할 수 있었다. 또한 In2S3/CdS층의 반치폭(full-width at half-maximum: FWHM)이 CdS층의 반치폭보다 더 낮게 나오는 것을 보아 이는 In2S3/CdS층의 결정성이 더 우수하다는 것을 확인할 수 있었다. CIGS 광흡수층 위에 In2S3를 증착하여 준 후에 CdS를 증착해 주었을 때, CdS만을 증착해준 경우에 비해 CdS가 더 결정성이 좋게 되었다고 해석할 수 있다.As shown in FIG. 6, a peak was confirmed at 2θ corresponding to each component, and In 2 S 3 having a trigonal and hexagonal structure was formed, and a cubic and hexagonal system It was confirmed that CdS having a structure was formed. In addition, In 2 S 3 / full width at half maximum of the CdS layer: seen (full-width at half-maximum FWHM) is shown to be lower than the half-width of the CdS layer, which can be confirmed that the more excellent the crystallinity of the In 2 S 3 / CdS layer there was. When CdS is deposited after In 2 S 3 is deposited on the CIGS light absorbing layer, it can be interpreted that CdS has better crystallinity than when only CdS is deposited.
도 7은 SLG 위에 각각 버퍼 필름으로서 (a)In2S3/CdS, (b)CdS, (c)In2S3 샘플들의 라만 분광 결과이다. 라만 분광계를 통하여 In2S3와 CdS층의 성분 모두 일치하는 영역의 라만이동(Raman shift)을 갖는 것을 확인할 수 있었다. In2S3/CdS 필름의 라만피크는 CdS만 증착하였을 때의 피크보다 1LO부분에서 세기(intensity)가 더 높게 나오는 것을 확인할 수 있어, 이러한 결과로부터 In2S3 층 위에 CdS 버퍼층이 증착될 경우가 더욱 증착이 원활하게 일어난다고 해석된다.7 is a Raman spectroscopy result of (a)In 2 S 3 /CdS, (b)CdS, (c)In 2 S 3 samples as buffer films on SLG, respectively. Through the Raman spectrometer, it was confirmed that both the components of the In 2 S 3 and CdS layer had a Raman shift in the same region. It can be seen that the Raman peak of the In 2 S 3 /CdS film is higher in the 1LO portion than the peak when only CdS is deposited.From these results, when the CdS buffer layer is deposited on the In 2 S 3 layer. It is interpreted that the deposition occurs more smoothly.
도 8은 FTO/In2S3/CdS와 FTO/CdS 샘플들의 UV/Visible spectroscopy 분광 결과이다. 8 is a result of UV/Visible spectroscopy spectroscopy of FTO/In 2 S 3 /CdS and FTO/CdS samples.
UV/Visible spectroscopy를 통하여 350-1300nm 파장영역대의 투과도를 분석하여, CdS만 증착하였을 때와 In2S3를 얇게 증착해준 후 CdS를 증착해 준 샘플 둘의 투과도가 크게 차이나지 않는다는 것을 확인할 수 있었다. 즉, 본 발명과 같이 CIGS 광흡수층에 In2S3/CdS를 형성하여도 CIGS 광흡수층까지 도달하는 태양광이 CdS만을 버퍼층으로 사용한 경우와 차이가 없으므로 태양광 수광에 In2S3가 방해가 되지 않는다.By analyzing the transmittance in the 350-1300nm wavelength range through UV/Visible spectroscopy, it was confirmed that the transmittance of the two samples deposited with CdS after depositing only CdS and after depositing In 2 S 3 thinly did not differ significantly. In other words, to form the In 2 S 3 / CdS the CIGS light absorbing layer as in the present invention because there is no difference in the case of sunlight that reaches the CIGS light absorbing layer used only a CdS buffer layer is the solar light reception is In 2 S 3 disturbance It doesn't work.
도 9는 FTO/In2S3/CdS와 FTO/CIGS/CdS 샘플들의 (Ahv)2-hv 커브이다. 밴드갭에너지를 일반적으로 사용되는 (ahv)2=A(hv-Eg)식을 이용하여 구하면 CdS는 2.31eV, In2S3/CdS는 2.27eV로서, In2S3/CdS는 CIGS 박막태양전지의 버퍼층으로 사용하기에 충분하다는 것을 알 수 있었다. 9 is a (Ahv ) 2 - hv curve of FTO/In 2 S 3 /CdS and FTO/CIGS/CdS samples. When the band gap energy is calculated using the commonly used (ahv) 2 =A(hv-E g ) equation, CdS is 2.31 eV, In 2 S 3 /CdS is 2.27 eV, and In 2 S 3 /CdS is a CIGS thin film. It was found that it was sufficient to be used as a buffer layer for solar cells.
도 10은 SLG/Mo/CIGS/In2S3/CdS와 SLG/Mo/CIGS/CdS 샘플의 단면 SEM 측정 결과이다. SLG/Mo/CIGS층 위에 In2S3 층 및 CdS층이 잘 증착 되었는지를 확인하기 위하여 SEM 단면이미지를 통해 확인하였다. SEM 단면 촬영을 통해 CIGS위에 증착 된 두 개의 다른 버퍼층의 두께는 둘 다 70nm정도로 증착 된 것을 확인할 수 있으며, 확대된 이미지로부터 CdS층 보다 In2S3/CdS층이 더욱 균일하게 증착된 것으로 확인하였다.10 is a cross-sectional SEM measurement result of SLG/Mo/CIGS/In2S3/CdS and SLG/Mo/CIGS/CdS samples. In order to confirm that the In 2 S 3 layer and the CdS layer were well deposited on the SLG/Mo/CIGS layer, it was confirmed through the SEM cross-sectional image. Through SEM cross-sectional photographing, it was confirmed that the thickness of the two different buffer layers deposited on the CIGS were both about 70 nm, and from the enlarged image, it was confirmed that the In 2 S 3 /CdS layer was deposited more evenly than the CdS layer. .
실험예 3 : CdS 버퍼층을 도입한 태양전지 device와 InExperimental Example 3: In the solar cell device and the CdS buffer layer introduced 22 SS 33 /CdS 버퍼층을 도입한 태양전지 device의 성능비교Performance comparison of solar cell device incorporating /CdS buffer layer
도 11은 SLG/Mo/CIGS층 위에 각각 CdS층과 In2S3/CdS층을 증착한 후 제작된 셀의 QE(Quantum Efficiency) 측정 결과이다. 도 11을 참고하면, QE측정을 통하여 In2S3/CdS 버퍼층을 도입한 셀의 EQE(External Quantum Efficiency)가 CdS를 도입한 셀의 EQE가 더 높은 것을 확인 할 수 있는데, 이는 SCR 핀홀이나 결함(defect)에 의한 재결합을 개선했기 때문이라고 추정된다. 이 결과로부터, In2S3/CdS층이 CIGS와 TCO층의 경계면 또한 CdS 단일층에 비하여 더욱 매끈하여 좋아졌음을 예상할 수 있다.11 is a result of QE (Quantum Efficiency) measurement of a cell fabricated after depositing a CdS layer and an In 2 S 3 /CdS layer on SLG/Mo/CIGS layers, respectively. Referring to FIG. 11, through QE measurement, it can be confirmed that the EQE (External Quantum Efficiency) of the cell in which the In 2 S 3 /CdS buffer layer is introduced is higher in the EQE of the cell in which CdS is introduced, which is an SCR pinhole or defect. It is presumed to be due to improved recombination due to (defect). From this result, it can be expected that the In 2 S 3 /CdS layer has a smoother interface between the CIGS and the TCO layer as compared to the CdS single layer and is improved.
아래 표 1은 SLG/Mo/CIGS층 위에 CdS층과 In2S3/CdS층을 증착한 후 제작된 셀의 I-V측정 결과이다.Table 1 below is an IV measurement result of a cell fabricated after depositing a CdS layer and an In 2 S 3 /CdS layer on the SLG/Mo/CIGS layer.
I-V Measurement 측정을 통하여 태양전지의 VOC, JSC, F.F.(Fill Factor) 및 저항을 확인할 수 있었다. CIGS에 CdS만 증착해 준 샘플의 VOC와 JSC는 두 층 모두 비슷하였지만 In2S3/CdS층이 CdS층에 비해 F.F.와 션트 저항이 크게 개선된 것을 확인할 수 있었다. 이는 In2S3가 핀홀을 메꾸어 주어 빈 공간(void)을 줄여주어 결함(defect)이 덜 일어나게 해주어서 분로저항이 개선되고 이에 따라서 F.F.도 증가한 것으로 예상된다.Through the IV measurement measurement, the V OC , J SC , FF (Fill Factor) and resistance of the solar cell could be confirmed. The V OC and J SC of the sample in which only CdS was deposited on CIGS were similar in both layers, but it was confirmed that the In 2 S 3 /CdS layer significantly improved FF and shunt resistance compared to the CdS layer. This is expected that In 2 S 3 fills up the pinhole, reducing voids, making defects less likely, improving shunt resistance, and thus increasing FF.
지금까지의 실험 결과를 종합하면, "금속전구체-셀렌화" 공정을 사용하여 제작 된 CIGS 광흡수층의 표면상태에 의해 이후에 증착되는 CdS 버퍼층 및 TCO층과 접합 시에 결함(defect)이 일어나게 되어 전자의 이동에 방해가 생기고 전자의 이동중에 재결합(recombination) 현상이 일어나 디바이스의 성능에 결함이 된다. 하지만 In2S3 얇은 층을 CIGS 광흡수층 위에 증착시키게 되면, CIGS 표면에 존재하는 핀홀을 메꾸어주고 평평한 층을 형성해주어 CdS 버퍼층 증착이 더욱 원활하도록 해주며, 이로인해 TCO층과 이후 공정도 모두 개선되도록 해주는 역할을 한다. 이로 인하여 양자효율이 증가하고, 션트저항이 증가하여 셀의 효율이 향상되게 된다. Summarizing the results of the experiments so far, defects occur when bonding with the CdS buffer layer and TCO layer to be deposited later by the surface condition of the CIGS light absorbing layer produced using the "metal precursor-selenization" process. The movement of electrons is disturbed, and recombination occurs during the movement of electrons, resulting in a defect in the performance of the device. But In2S3 When a thin layer is deposited on the CIGS light absorbing layer, it fills in the pinholes on the CIGS surface and forms a flat layer to facilitate the deposition of the CdS buffer layer, thereby improving both the TCO layer and subsequent processes. . As a result, the quantum efficiency increases, the shunt resistance increases, and the efficiency of the cell is improved.
XRD, Raman, UV/Visible 분석을 통하여 CdS만 증으로 쌓았을 때에 비하여 In2S3층을 얇게 증착시켜준 후에 CdS를 증착시킨 버퍼층의 결정성, 라만피크가 더 우수하며, 투과도나 밴드갭도 CIGS박막태양전지의 버퍼층으로 쓰이기에 충분하게 확인되었다.Through XRD, Raman, UV/Visible analysis, the crystallinity and Raman peak of the buffer layer on which CdS is deposited after depositing the In 2 S 3 layer thinly compared to the case where only CdS is accumulated is better, and the transmittance or band gap is also better. It has been sufficiently confirmed to be used as a buffer layer for CIGS thin-film solar cells.
기존 CIGS 태양전지 제조시 사용되어 온 CdS 버퍼층에 In2S3 버퍼층을 적용하여 CIGS 태양전지를 제조함으로써, 고성능 박막태양전지 제조에 기여할 것으로 예상된다. By applying an In 2 S 3 buffer layer to the CdS buffer layer used in manufacturing the existing CIGS solar cell, it is expected to contribute to the manufacture of high-performance thin-film solar cells by manufacturing CIGS solar cells.
Claims (10)
상기 하부전극 위에 CIGS 광흡수층을 형성하는 단계(2);
상기 CIGS 광흡수층 위에 In2S3 버퍼층을 형성하는 단계(3);
상기 In2S3 버퍼층 위에 CdS 버퍼층을 형성하는 단계(4); 및
상기 CdS 버퍼층 위에 상부전극을 포함하는 나머지 층을 형성하는 단계(5)를 포함하는, CIGS 광흡수층의 핀홀 감소 효과를 갖는 CIGS 박막태양전지 제조 방법.
Forming a lower electrode on the substrate (1);
Forming a CIGS light absorbing layer on the lower electrode (2);
Forming an In 2 S 3 buffer layer on the CIGS light absorption layer (3);
Forming a CdS buffer layer on the In 2 S 3 buffer layer (4); And
A method of manufacturing a CIGS thin film solar cell having a pinhole reduction effect of the CIGS light absorbing layer, comprising the step (5) of forming a remaining layer including an upper electrode on the CdS buffer layer.
The method of claim 1, wherein the CIGS light absorption layer is formed by a metal precursor-selenization process or a three-stage simultaneous evaporation method, and has a pinhole reduction effect of the CIGS light absorption layer.
The method of claim 1, wherein the In 2 S 3 buffer layer is formed to have a thickness thinner than that of the CdS buffer layer, and has a pinhole reduction effect of the CIGS light absorption layer.
The method of claim 1, wherein the In 2 S 3 is formed by CBD (Chemical Bath Deposition), and has a pinhole reduction effect of the CIGS light absorbing layer.
The method of claim 1, wherein the CdS is formed by CBD (Chemical Bath Deposition), and has a pinhole reduction effect of the CIGS light absorbing layer.
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