KR101870236B1 - Method for manufacturing a double-sided CZTS solar cell using a transparent conductive oxide film substrate and a solar cell prepared from same - Google Patents

Method for manufacturing a double-sided CZTS solar cell using a transparent conductive oxide film substrate and a solar cell prepared from same Download PDF

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KR101870236B1
KR101870236B1 KR1020170035360A KR20170035360A KR101870236B1 KR 101870236 B1 KR101870236 B1 KR 101870236B1 KR 1020170035360 A KR1020170035360 A KR 1020170035360A KR 20170035360 A KR20170035360 A KR 20170035360A KR 101870236 B1 KR101870236 B1 KR 101870236B1
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solar cell
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KR20180032486A (en
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김정식
강진규
황대규
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재단법인대구경북과학기술원
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Abstract

본 발명은 투명 전도 산화막을 후면전극으로 이용한 양면 CZTS계 태양전지 및 이의 제조방법에 관한 것이다. 본 발명의 태양전지는 투명 전도 산화막을 후면전극으로 사용함으로써, 양면(전면 및 후면)에서 빛을 흡수함으로써 소자효율을 개선할 수 있다. 뿐만 아니라, 본 발명의 태양전지의 경우 기존 후면전극인 몰리브덴을 대체하는 차세대 후면전극의 가능성을 평가할 수 있다. 또한, 본 발명의 태양전지는 후면전극과 광흡수층 사이에 후면 버퍼층을 도입함으로써, 계면특성을 향상시켜 광전환 효율이 개선된 이점을 갖는다.The present invention relates to a double-side CZTS solar cell using a transparent conductive oxide film as a back electrode and a method for manufacturing the same. The solar cell of the present invention can improve device efficiency by absorbing light on both sides (front and back) by using a transparent conductive oxide film as a back electrode. In addition, in the case of the solar cell of the present invention, it is possible to evaluate the possibility of a next generation rear electrode which replaces molybdenum, which is a conventional rear electrode. In addition, the solar cell of the present invention has an advantage of improving the light conversion efficiency by improving the interface characteristics by introducing the rear buffer layer between the back electrode and the light absorption layer.

Description

투명 전도 산화막 기판을 이용한 양면 CZTS계 태양전지의 제조방법 및 이로부터 제조된 태양전지{Method for manufacturing a double-sided CZTS solar cell using a transparent conductive oxide film substrate and a solar cell prepared from same}BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a double-sided CZTS solar cell using a transparent conductive oxide film substrate and a solar cell produced therefrom,

본 발명은 투명 전도 산화막을 후면전극으로 이용한 양면 CZTS계 태양전지 및 이의 제조방법에 관한 것이다.The present invention relates to a double-side CZTS solar cell using a transparent conductive oxide film as a back electrode and a method for manufacturing the same.

차세대 신재생 에너지원으로 가장 크게 주목받고 있는 태양전지는 친환경성, 반영구성, 실용성 등의 장점 때문에 여러 분야에 걸쳐 폭넓게 연구가 이루어지고 있다. 초기 태양전지는 반도체분야에서의 공정기술을 토대로 결정형 실리콘계(c-Si)가 중심을 이루어졌다. 하지만, 고가의 재료가공비 그리고 간접반도체인 실리콘의 재료적 특성 때문에 얇은 두께에서도 광흡수율이 높은 박막 태양전지가 최근 주목을 받고 있다. 그 중, 선행연구로 높은 효율을 보인 박막태양전지는 CdTe, 구리-인듐-갈륨-황(이하, CIGS)가 있으나, 이들 태양전지 역시 희소원소(인듐, 갈륨)을 사용하기에 수요 대비 가격이 비싸다는 단점이 있다. Solar cells, which have been attracting the greatest attention as the next generation of renewable energy sources, have been extensively studied in various fields because of their advantages such as environment friendliness, reflecting structure, and practicality. The initial solar cell was based on crystalline silicon (c-Si) based on process technology in the semiconductor field. However, thin film solar cells, which have high light absorptivity even at a thin thickness, are attracting attention due to expensive material processing costs and material characteristics of an indirect semiconductor, silicon. Thin film solar cells, which have shown high efficiency as a result of previous studies, have CdTe and copper-indium-gallium-sulfur (CIGS), but these solar cells also use rare elements (indium, gallium) There is a drawback that it is expensive.

이러한 문제를 극복하기 위해 CIGS와 비슷한 결정구조(칼코겐화물)를 가지며 저가의 원소로 구성된 Cu2ZnSnSe4(CZTSe), Cu2ZnSnS4(CZTS) 또는Cu2ZnSn(S,Se)4(CZTSSe)와 같은 Cu-Zn-Sn-(S,Se)계(이하, ‘CZTS계’라 함)가 주목받고 있다. CZTS계 태양전지는 S,Se의 비율을 열처리방식과 흡수층 증착조건에 따라 밴드갭을 1.0~2.7 eV까지 조절할 수 있어 유연한 밴드갭 형성이 가능하다. 또한, 직접천이 반도체로서 광흡수계수가 10-4cm이상이기 때문에 실리콘 태양전지에 비해 매우 얇은 두께(1~2 μm) 로도 고효율 태양전지 제작이 가능하다. 따라서, CZTS계 태양전지는 현재 상용화 되어 있는 고가의 실리콘 태양전지를 대체할 차세대 친환경 저가 태양전지로 활발히 연구가 이루어지고 있다. In order to overcome this problem, Cu 2 ZnSnSe 4 (CZTSe), Cu 2 ZnSnS 4 (CZTS) or Cu 2 ZnSn (S, Se) 4 (CZTSSe) having a similar crystal structure (chalcogenide) (Hereinafter, referred to as "CZTS system") such as Cu-Zn-Sn- (S, Se) CZTS solar cells can control the ratio of S and Se to 1.0 ~ 2.7 eV according to heat treatment method and absorption layer deposition condition, thus forming a flexible bandgap. In addition, since the direct absorption semiconductor has a light absorption coefficient of 10-4 cm or more, a highly efficient solar cell can be manufactured with a very thin thickness (1 to 2 μm) as compared with a silicon solar cell. Therefore, the CZTS solar cell is being actively researched as a next-generation eco-friendly low-cost solar cell that can replace expensive silicon solar cells that are currently in commercial use.

CZTS계 태양전지의 흡수층 제작방법은 진공, 비진공 크게 두가지 방법이 있다. 현재 세계 최고효율은 비진공을 통해 제작된 방법(12.6%)이지만, 맹독성 물질(하이드라진)을 이용하기 때문에 상용화에는 적합하지 않다. 하이드라진을 이용한 공정이외에 고효율을 보이는 방식은 크게 스퍼터링, 동시증발증착기, 전착법 등이 있다. 진공방법은 비진공에 비해 정밀한 박막제어가 가능하며 대량양산화가 가능함으로 흡수층 제작에 널리 이용된다. There are two methods of manufacturing the absorption layer of CZTS-based solar cell, namely, vacuum and non-vacuum. Currently, the world's highest efficiency is achieved through non-vacuum (12.6%), but it is not suitable for commercial use because it uses a toxic substance (hydrazine). In addition to hydrazine-based processes, high-efficiency methods include sputtering, co-evaporation, and electrodeposition. Vacuum method is widely used for making absorbent layer because it can control precise thin film compared with non-vacuum and can mass-produce mass.

한편, 기존의 후면전극으로 사용되는 몰리브덴 전극(Mo)은 빛을 대부분 반사시킴으로 양면태양전지의 구현을 위해선 후면전극을 투명한 전극으로 바꿀 필요성이 있다. On the other hand, the molybdenum electrode (Mo) used as the conventional rear electrode reflects most of the light, so it is necessary to convert the rear electrode to a transparent electrode in order to realize a double-sided solar cell.

이에 본 발명자는 상부에서만 빛을 흡수하는 기존의 태양전지와는 달리, 투명전극을 후면전극에 사용하여 양면에서 빛을 흡수할 수 있는 양면태양전지를 구현하기 위하여 열처리 전 전구체를 투명 전도 산화막 후면전극 위에 증착, 열처리 후 태양전지의 광전환 효율 및 전지특성을 평가하였다.Therefore, unlike conventional solar cells, which absorb light only at the upper part, the present inventors have found that, in order to realize a double-sided solar cell capable of absorbing light from both sides using a transparent electrode as a back electrode, The photoconversion efficiency and cell characteristics of the solar cell were evaluated after deposition and heat treatment.

한국등록특허 제10-1081270호Korean Patent No. 10-1081270

따라서 본 발명의 목적은 양면에서 빛을 흡수할 수 있는 박막 태양전지를제공하는 것이다.Accordingly, an object of the present invention is to provide a thin film solar cell capable of absorbing light on both sides.

본 발명의 또 다른 목적은 양면에서 빛을 흡수할 수 있는 양면태양전지를 구현할 수 있는 박막 태양전지 제조방법을 제공하는 것이다.It is another object of the present invention to provide a method of manufacturing a thin film solar cell capable of realizing a double-sided solar cell capable of absorbing light on both sides.

상기와 같은 본 발명의 목적을 달성하기 위해서, In order to achieve the above-mentioned object of the present invention,

본 발명은 투명 전도 산화막 후면전극을 포함하는 박막 태양전지를 제공한다.The present invention provides a thin film solar cell including a transparent conductive oxide rear electrode.

본 발명의 일실시예에 있어서, 상기 박막 태양전지는 기판, 투명 전도 산화막 후면전극, 광흡수층, 버퍼층, 윈도우층 및 전면전극이 순차적으로 형성될 수 있다.In an exemplary embodiment of the present invention, the thin film solar cell may include a substrate, a transparent conductive oxide film, a light absorbing layer, a buffer layer, a window layer, and a front electrode sequentially.

본 발명의 일실시예에 있어서, 상기 투명 전도 산화막 후면전극과 광흡수층 사이에 후면 버퍼층이 더 포함할 수 있다.In an embodiment of the present invention, a back buffer layer may be further included between the transparent conductive oxide film rear electrode and the light absorption layer.

본 발명의 일실시예에 있어서, 상기 투명 전도 산화막 후면전극은 알루미늄 도핑 아연 산화막(AZO), 주석 도핑 인듐 산화막(ITO), 플로린 도핑 주석 산화막(FTO), 아연 산화막(ZnO), 주석 산화막(SnO2), 카드뮴 산화막(CdO), 인듐 산화막(In2O3), 갈륨 산화막(Ga2O3)으로 이루어진 군으로부터 선택된 1종 이상일 수 있다.In one embodiment of the present invention, the transparent conductive oxide film rear electrode may be formed of at least one selected from the group consisting of an aluminum-doped zinc oxide (AZO), a tin doped indium oxide (ITO), a flourine doped tin oxide (FTO), a zinc oxide (ZnO) 2 ), a cadmium oxide film (CdO), an indium oxide film (In 2 O 3 ), and a gallium oxide film (Ga 2 O 3 ).

본 발명의 일실시예에 있어서, 상기 투명 전도 산화막 후면전극의 두께는 10 내지 700nm일 수 있다.In one embodiment of the present invention, the thickness of the transparent conductive oxide back electrode may be 10 to 700 nm.

본 발명의 일실시예에 있어서, 상기 후면 버퍼층은 NaF 또는 ZnO일 수 있다.In an embodiment of the present invention, the back buffer layer may be NaF or ZnO.

본 발명의 일실시예에 있어서, 상기 후면 버퍼층의 두께는 5 내지 10nm일 수 있다.In an embodiment of the present invention, the thickness of the back buffer layer may be 5 to 10 nm.

본 발명의 일실시예에 있어서, 상기 광흡수층은 CIS(Copper, Indium, Sulfur 또는 Selenide), CIGS(Copper, Indium, Galium, Sulfur 또는 Selenide) 또는 CZTS(Copper, Zinc, Tin, Sulfur 또는 Selenid) 중 선택될 수 있다.In one embodiment of the present invention, the light absorption layer is formed of a material selected from the group consisting of CIS (Copper, Indium, Sulfur or Selenide), CIGS (Copper, Indium, Galium, Sulfur or Selenide) Can be selected.

본 발명의 일실시예에 있어서, 상기 태양전지는 양면에서 빛을 흡수하여 소자효율이 증대될 수 있다.In one embodiment of the present invention, the solar cell absorbs light on both sides and the device efficiency can be increased.

또한, 본 발명은 a) 투명 전도 산화막 후면전극이 형성된 기판을 준비하는 단계; b) 상기 후면전극 상에 광흡수층을 형성하는 단계; c) 상기 광흡수층 상에 버퍼층을 형성하는 단계; d) 상기 버퍼층 상에 윈도우층을 형성하는 단계; 및 e) 상기 윈도우층 상에 전면전극을 형성하는 단계를 포함하는, 박막 태양전지의 제조방법을 제공한다.The present invention also provides a method of manufacturing a semiconductor device, comprising the steps of: a) preparing a substrate on which a transparent conductive oxide film rear electrode is formed; b) forming a light absorbing layer on the rear electrode; c) forming a buffer layer on the light absorption layer; d) forming a window layer on the buffer layer; And e) forming a front electrode on the window layer.

본 발명의 일실시예에 있어서, 상기 a) 단계에서 기판에 형성되는 투명 전도 산화막 후면전극의 두께는 10 내지 700nm일 수 있다.In one embodiment of the present invention, the thickness of the transparent conductive oxide back electrode formed on the substrate in the step a) may be 10 to 700 nm.

본 발명의 일실시예에 있어서, 상기 투명 전도 산화막 후면전극은 알루미늄 도핑 아연 산화막(AZO), 주석 도핑 인듐 산화막(ITO), 플로린 도핑 주석 산화막(FTO), 아연 산화막(ZnO), 주석 산화막(SnO2), 카드뮴 산화막(CdO), 인듐 산화막(In2O3), 갈륨 산화막(Ga2O3)으로 이루어진 군으로부터 선택된 1종 이상일 수 있다.In one embodiment of the present invention, the transparent conductive oxide film rear electrode may be formed of at least one selected from the group consisting of an aluminum-doped zinc oxide (AZO), a tin doped indium oxide (ITO), a flourine doped tin oxide (FTO), a zinc oxide (ZnO) 2 ), a cadmium oxide film (CdO), an indium oxide film (In 2 O 3 ), and a gallium oxide film (Ga 2 O 3 ).

본 발명의 일실시예에 있어서, 상기 a)단계에서 투명 전도 산화막 후면전극은 스퍼터링법(sputtering), 증발법(evaporation), CVD법(Chemical vapor deposition), 유기금속화학기상증착(MOCVD), 근접승화법(Close-spaced sublimation, CSS), 스프레이 피롤리시스(Spray pyrolysis), 화학 스프레이법(Chemical spraying), 스크린프린팅법(Screeen printing), 비진공 액상성막법, CBD법(Chemical bath deposition), VTD법(Vapor transport deposition), 및 전착법(electrodeposition) 중에서 선택된 어느 하나의 방법으로 형성될 수 있다.In one embodiment of the present invention, in the step a), the transparent conductive oxide rear electrode is formed by sputtering, evaporation, CVD (chemical vapor deposition), MOCVD, A spraying method, a spraying method, a spraying method, a spraying method, a spraying method, a spraying method, a spraying method, a spraying method, a spraying method, a spraying method, a spraying method, a spraying method, A vapor deposition method, a vapor deposition method, a vapor deposition method, and an electrodeposition method.

본 발명의 일실시예에 있어서, 상기 a) 단계 이후 및 b) 단계 이전에 후면 버퍼층을 형성하는 단계를 더 포함할 수 있다.In one embodiment of the present invention, the method may further include forming a rear buffer layer after the a) and b).

본 발명의 일실시예에 있어서, 후면 버퍼층은 NaF 또는 ZnO이며, 두께는 5 내지 10nm로 형성될 수 있다.In one embodiment of the present invention, the back buffer layer is NaF or ZnO, and the thickness may be 5 to 10 nm.

본 발명의 일실시예에 있어서, 상기 b) 단계의 광흡수층은 CIS(Copper, Indium, Sulfur 또는 Selenide), CIGS(Copper, Indium, Galium, Sulfur 또는 Selenide) 또는 CZTS(Copper, Zinc, Tin, Sulfur 또는 Selenid) 중 선택될 수 있다.In one embodiment of the present invention, the light absorption layer in the step b) may be a CIS (Copper, Indium, Sulfur or Selenide), CIGS (Copper, Indium, Galium, Sulfur or Selenide) Or Selenid).

본 발명의 일실시예에 있어서, 상기 b) 단계에서 광흡수층은 금속 전구체를 후면전극 상에 증착한 후 VI족 원소 함유 기체 분위기 하에서 열처리하여 형성될 수 있다.In one embodiment of the present invention, in the step b), the light absorption layer may be formed by depositing a metal precursor on the rear electrode and then performing heat treatment in a gas atmosphere containing a group VI element.

본 발명의 일실시예에 있어서, 상기 VI족 원소는 황, 셀레늄 또는 이들의 혼합물일 수 있다.In one embodiment of the present invention, the VI group element may be sulfur, selenium or a mixture thereof.

본 발명의 일실시예에 있어서, 상기 열처리는 200℃ 내지 400℃의 온도에서 1분 내지 60분 동안 예비열처리를 수행한 후, 400℃ 내지 700℃의 온도에서 1분 내지 120분 동안 본열처리를 수행될 수 있다.In one embodiment of the present invention, the heat treatment is performed by preliminary heat treatment at a temperature of 200 ° C to 400 ° C for 1 minute to 60 minutes, followed by heat treatment at a temperature of 400 ° C to 700 ° C for 1 minute to 120 minutes .

본 발명의 일실시예에 있어서, 상기 본열처리는 700내지 800 Torr 압력에서 진행될 수 있다.In one embodiment of the present invention, the present heat treatment may be conducted at a pressure of 700 to 800 Torr.

본 발명의 일실시예에 있어서, 상기 b) 단계의 광흡수층은 50 nm 내지 2 ㎛의 두께로 형성될 수 있다.In one embodiment of the present invention, the light absorption layer of step b) may be formed to a thickness of 50 nm to 2 탆.

본 발명의 일실시예에 있어서, 상기 c) 단계의 버퍼층은 CdS, ZnS, Zn(O,S), CdZnS 및 ZnSe로 이루어지는 군으로부터 선택되는 1종 이상일 수 있다.In one embodiment of the present invention, the buffer layer in step c) may be at least one selected from the group consisting of CdS, ZnS, Zn (O, S), CdZnS and ZnSe.

본 발명의 일실시예에 있어서, 상기 d) 단계의 윈도우층은 ZnO:Al, ZnO:AZO, ZnO:B(BZO) 및 ZnO:Ga(GZO)로 이루어지는 군으로부터 선택되는 1종 이상일 수 있다.In one embodiment of the present invention, the window layer in the step d) may be at least one selected from the group consisting of ZnO: Al, ZnO: AZO, ZnO: B (BZO) and ZnO: Ga (GZO).

본 발명의 태양전지는 투명 전도 산화막을 후면전극으로 사용함으로써, 양면(전면 및 후면)에서 빛을 흡수함으로써 소자효율을 개선할 수 있다. 뿐만 아니라, 본 발명의 태양전지의 경우 기존 후면전극인 몰리브덴을 대체하는 차세대 후면전극의 가능성을 평가할 수 있다. 또한, 본 발명의 태양전지는 후면전극과 광흡수층 사이에 후면 버퍼층을 도입함으로써, 계면특성을 향상시켜 광전환 효율이 개선된 이점을 갖는다.The solar cell of the present invention can improve device efficiency by absorbing light on both sides (front and back) by using a transparent conductive oxide film as a back electrode. In addition, in the case of the solar cell of the present invention, it is possible to evaluate the possibility of a next generation rear electrode which replaces molybdenum, which is a conventional rear electrode. In addition, the solar cell of the present invention has an advantage of improving the light conversion efficiency by improving the interface characteristics by introducing the rear buffer layer between the back electrode and the light absorption layer.

도 1은 열처리 전에 증착된 전구체층의 단면도의 개략도를 나타낸 것이다.
도 2는 CZTS계 태양전지 제조 공정의 흐름도를 나타낸 것이다.
도 3은 실시예 1-1의 흡수층 단면의 SEM사진이다.
도 4는 실시예 1-2의 흡수층 단면의 SEM사진이다.BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows a schematic view of a cross-sectional view of a precursor layer deposited prior to heat treatment.
2 is a flow chart of a CZTS solar cell manufacturing process.
3 is an SEM photograph of the cross section of the absorbent layer of Example 1-1.
4 is a SEM photograph of the section of the absorbent layer of Example 1-2.

본 발명은 투명 전도 산화막 후면전극을 포함하는 박막 태양전지에 관한 것이다.The present invention relates to a thin film solar cell including a transparent conductive oxide rear electrode.

본 발명의 실시예들은 여러 가지 형태로 변형될 수 있으며, 본 발명의 범위가 아래에서 상술하는 실시예들에 한정되는 것은 아니다. 본 발명의 실시예들은 본 발명을 보다 완전하게 설명하기 위하여 제공되는 것이다. 본 명세서에서 어떤 막(또는 층)이 다른 막(또는 층) 또는 기판의 “위(또는 상)”에 있다고 기재된 경우, 상기 어떤 막(또는 층)이 상기 다른 막(또는 층) 위에 직접 존재할 수 있고, 그 사이에 제3의 다른 막(또는 층)이 개재될 수 있다.The embodiments of the present invention can be modified in various forms, and the scope of the present invention is not limited to the embodiments described below. Embodiments of the present invention are provided to more fully describe the present invention. It is to be understood that any film (or layer) may be directly present on the other film (or layer) if it is described herein as being "on (or over) And a third other film (or layer) may be interposed therebetween.

이하, 첨부된 도면을 참조하여 본 발명의 일 실시예에 따른 태양전지 및 그 제조 방법에 대하여 상세히 설명한다. 명세서 전체에 걸쳐 동일 참조 부호는 동일 구성 요소를 지칭한다.Hereinafter, a solar cell and a manufacturing method thereof according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Like reference numerals refer to like elements throughout the specification.

도 1은 본 발명의 일 실시예에 따른 태양전지의 구성을 개략적으로 나타낸 단면도이다.1 is a cross-sectional view schematically showing a configuration of a solar cell according to an embodiment of the present invention.

도 1을 참조하면, 본 발명의 박막 태양전지는 기판(100), 투명 전도 산화막 후면전극(200), 광흡수층(400), 버퍼층(500), 윈도우층(600, 700) 및 전면전극(800)이 순차적으로 형성될 수 있으며, 상기 투명 전도 산화막 후면전극(200)과 광흡수층(400) 사이에 후면 버퍼층(300)이 더 포함될 수 있다.Referring to FIG. 1, the thin film solar cell of the present invention includes a substrate 100, a transparent conductive oxide rear electrode 200, a light absorption layer 400, a buffer layer 500, window layers 600 and 700, And a back buffer layer 300 may be further formed between the transparent conductive oxide layer rear electrode 200 and the light absorption layer 400. [

기판(100)은 단단한(hard) 재질의 기판 또는 유연성(flexible) 재질의 기판을 사용한다. 예를 들어, 기판(110)으로 단단한 재질의 기판을 사용하는 경우, 유리 플레이트, 석영 플레이트, 실리콘 플레이트, 합성수지 플레이트, 금속 플레이트 등을 포함할 수 있다. 상기 유리 플레이트는 소다 라임 유리(soda lime glass), 보로실리케이트 유리(borosilicate glass) 및 무알칼리 유리(alkali free glass) 등이 사용될 수 있다. 상기 합성수지 플레이트는 폴리에틸렌나프탈레이트, 폴리에틸렌테레프탈레이트, 폴리카보네이트, 폴리비닐알코올, 폴리아크릴레이트, 폴리이미드, 폴리노르보넨, 폴리에테르설폰 등이 사용될 수 있다. 상기 금속 플레이트로는 알루미늄 호일 등이 사용될 수 있다.The substrate 100 uses a substrate of hard material or a flexible material. For example, when the substrate 110 is made of a rigid substrate, it may include a glass plate, a quartz plate, a silicon plate, a synthetic resin plate, a metal plate, and the like. The glass plate may be made of soda lime glass, borosilicate glass, alkali free glass, or the like. The synthetic resin plate may be made of polyethylene naphthalate, polyethylene terephthalate, polycarbonate, polyvinyl alcohol, polyacrylate, polyimide, polynorbornene, polyether sulfone, or the like. As the metal plate, an aluminum foil or the like may be used.

상기 기판(100) 위에는 후면전극(200)이 형성될 수 있다. 상기 투명 전도 산화막 후면전극은 알루미늄 도핑 아연 산화막(AZO), 주석 도핑 인듐 산화막(ITO), 플로린 도핑 주석 산화막(FTO), 아연 산화막(ZnO), 주석 산화막(SnO2), 카드뮴 산화막(CdO), 인듐 산화막(In2O3), 갈륨 산화막(Ga2O3)으로 이루어진 군으로부터 선택될 수 있다. 후면전극 두께는 10 내지 700nm일 수 있다.A rear electrode 200 may be formed on the substrate 100. The transparent conductive oxide rear electrode may include at least one selected from the group consisting of an aluminum-doped zinc oxide (AZO), a tin-doped indium oxide (ITO), a flourine doped tin oxide (FTO), a zinc oxide (ZnO), a tin oxide (SnO 2 ), a cadmium oxide An indium oxide film (In 2 O 3 ), and a gallium oxide film (Ga 2 O 3 ). The back electrode thickness may be between 10 and 700 nm.

일반적으로 후면전극은 높은 전기전도도가 요구되고 고온 안정성을 가져야 하며, 종래에는 이러한 요건을 충족시킬 수 있는 몰리브덴(Mo)이 주로 사용되어져 왔으나, 본 발명에서는 태양전지의 전면뿐 아니라 후면에서도 빛을 흡수하여 소자효율을 증대시키기 위해 토명 전도 산화막을 후면전극으로 사용하였다.In general, molybdenum (Mo), which can meet these requirements, has been mainly used for the back electrode, which requires high electrical conductivity and high temperature stability. In the present invention, however, In order to increase the device efficiency, a buried conducting oxide film was used as the back electrode.

상기 후면전극(200) 위에 형성되는 광흡수층(400)은 빛을 흡수하여 전자-정공 쌍을 형성하고, 전자와 정공을 각각 다른 전극으로 전달하여 전류를 흐르게 하는 역할을 수행한다. 광흡수층은 CIS(Copper, Indium, Sulfur 또는 Selenide), CIGS(Copper, Indium, Galium, Sulfur 또는 Selenide) 또는 CZTS(Copper, Zinc, Tin, Sulfur 또는 Selenid) 계열의 광흡수층일 수 있다.The light absorbing layer 400 formed on the rear electrode 200 absorbs light to form electron-hole pairs, and transmits electrons and holes to the other electrodes to flow current. The light absorbing layer may be a light absorbing layer of CIS (Copper, Indium, Sulfur or Selenide), CIGS (Copper, Indium, Galium, Sulfur or Selenide) or CZTS (Copper, Zinc, Tin, Sulfur or Selenide)

본 발명의 일구체예에서, 상기 투명 전도 산화막 후면전극(200)과 광흡수층(400) 사이에 후면 버퍼층(300)이 더 포함할 수 있으며, 후면 버퍼층(300)은 NaF 또는 ZnO일 수 있으며, 투명 전도 산화막 후면전극(200)과 광흡수층(400) 사이의 계면특성을 향상시키는 역할을 한다. 후면 버퍼층(300)은 NaF 또는 ZnO일 수 있으며, 5 내지 10nm의 두께를 가질 수 있다.The rear buffer layer 300 may be formed of NaF or ZnO, and the rear buffer layer 300 may be formed between the transparent conductive oxide rear electrode 200 and the light absorption layer 400. In this case, Thereby improving the interface characteristics between the transparent conductive oxide film rear electrode 200 and the light absorbing layer 400. The back buffer layer 300 may be NaF or ZnO, and may have a thickness of 5 to 10 nm.

상기 광흡수층(400) 위에 형성되는 버퍼층(500)은 CdS, ZnS, Zn(O,S), CdZnS 및 ZnSe로 이루어지는 군으로부터 선택되는 1종 이상일 수 있으며, 윈도우층(600)과 광흡수층(400) 사이의 높은 밴드 갭을 해소해 주는 역할을 한다.The buffer layer 500 formed on the light absorbing layer 400 may be at least one selected from the group consisting of CdS, ZnS, Zn (O, S), CdZnS and ZnSe. ) Of the high band gap.

상기 버퍼층(500) 위에 형성되는 윈도우층(600, 700)은 ZnO:Al, ZnO:AZO, ZnO:B(BZO) 및 ZnO:Ga(GZO)로 이루어지는 군으로부터 선택되는 1종 이상일 수 있으며, 광투과율이 높고, 전기전도도가 좋을 수 있다.The window layers 600 and 700 formed on the buffer layer 500 may be at least one selected from the group consisting of ZnO: Al, ZnO: AZO, ZnO: B (BZO), and ZnO: Ga (GZO) The transmittance can be high and the electric conductivity can be good.

상기 윈도우층(600, 700) 위에 형성되는 전면전극은 태양전지의 표면에서 전류 수집을 위한 기능을 하며, 하기 실시예에서는 알루미늄을 사용하였으나, 당업계에서 사용하는 전면전극이라면 그 종류를 특별히 제한하는 것은 아니다.The front electrodes formed on the window layers 600 and 700 function to collect current from the surface of the solar cell. In the following embodiments, aluminum is used. However, if the front electrodes used in the art are limited, It is not.

본 발명은 또한, a) 투명 전도 산화막 후면전극이 형성된 기판을 준비하는 단계; b) 상기 후면전극 상에 광흡수층을 형성하는 단계; c) 상기 광흡수층 상에 버퍼층을 형성하는 단계; d) 상기 버퍼층 상에 윈도우층을 형성하는 단계; 및 e) 상기 윈도우층 상에 전면전극을 형성하는 단계를 포함하는, 박막 태양전지의 제조방법에 관한 것이다.The present invention also provides a method of manufacturing a semiconductor device, comprising the steps of: a) preparing a substrate on which a transparent conducting oxide film rear electrode is formed; b) forming a light absorbing layer on the rear electrode; c) forming a buffer layer on the light absorption layer; d) forming a window layer on the buffer layer; And e) forming a front electrode on the window layer.

이하, 본 발명에 따른 태양전지용 박막의 제조방법을 단계적으로 상세히 설명한다.Hereinafter, a method of manufacturing a thin film for a solar cell according to the present invention will be described in detail.

본 발명의 a) 단계는 투명 전도 산화막 후면전극이 형성된 기판을 준비하는 단계로서, 상기 투명 전도 산화막 후면전극은 알루미늄 도핑 아연 산화막(AZO), 주석 도핑 인듐 산화막(ITO), 플로린 도핑 주석 산화막(FTO), 아연 산화막(ZnO), 주석 산화막(SnO2), 카드뮴 산화막(CdO), 인듐 산화막(In2O3), 갈륨 산화막(Ga2O3)으로 이루어진 군으로부터 선택될 수 있으며, 10 내지 700nm의 두께를 형성할 수 있다.(A) of the present invention is a step of preparing a substrate on which a transparent conductive oxide film rear electrode is formed, wherein the transparent conductive oxide film rear electrode is formed of an aluminum doped zinc oxide (AZO), a tin doped indium oxide (ITO) ), Zinc oxide (ZnO), tin oxide (SnO 2 ), cadmium oxide (CdO), indium oxide (In 2 O 3 ) and gallium oxide (Ga 2 O 3 ) Can be formed.

본 발명의 일구체예에서, 상기 a) 단계를 통해 준비된 투명 전도 산화막 후면전극이 형성된 기판은 b) 단계 이전에 열처리 또는 플라즈마 오존 처리 공정을 더 거칠 수 있으며, 이때 열처리는 전열처리 혹은 후열처리로서 100℃ 내지 400℃의 온도에서 5분 내지 60분 동안 선택적으로 수행될 수 있으며, 프라즈마 오존 처리는 5분 내지 60분 동안 수행될 수 있다.In one embodiment of the present invention, the substrate on which the transparent conductive oxide film rear electrode prepared through step a) is formed may be further subjected to a heat treatment or a plasma ozone treatment process before step b), wherein the heat treatment is performed by a pre- At a temperature of 100 DEG C to 400 DEG C for 5 minutes to 60 minutes, and the plasma ozone treatment may be performed for 5 minutes to 60 minutes.

상기 a)단계에서 투명 전도 산화막 후면전극은 스퍼터링법(sputtering), 증발법(evaporation), CVD법(Chemical vapor deposition), 유기금속화학기상증착(MOCVD), 근접승화법(Close-spaced sublimation, CSS), 스프레이 피롤리시스(Spray pyrolysis), 화학 스프레이법(Chemical spraying), 스크린프린팅법(Screeen printing), 비진공 액상성막법, CBD법(Chemical bath deposition), VTD법(Vapor transport deposition), 및 전착법(electrodeposition) 중에서 선택된 어느 하나의 방법으로 형성될 수 있다.In the step a), the transparent conductive oxide rear electrode may be formed by sputtering, evaporation, CVD (Chemical Vapor Deposition), MOCVD, Close-spaced sublimation (CSS) , Spray pyrolysis, chemical spraying, screen printing, non-vacuum liquid phase film deposition, CBD chemical vapor deposition, VTD vapor deposition, And may be formed by any one method selected from electrodeposition.

본 발명의 다른 구체예에서, 상기 a) 단계 이후 및 b) 단계 이전에 후면 버퍼층을 형성하는 단계를 더 포함할 수 있다. 자세하게는, a) 단계 이후 투명 전도 산화막 후면전극 상에 후면 버퍼층을 형성하는 단계로서, 후면 버퍼층은 NaF 또는 ZnO일 수 있으며, 이때 형성되는 후면 버퍼층은 5 내지 10nm의 두께가 바람직하다. 하기 실험예에서는 후면 버퍼층의 두께에 따른 태양전지의 에너지 전환 효율을 살펴보았으며, 그 결과 후면 버퍼층이 10nm보다 더 두꺼워질 경우 효율이 하락하는 것을 확인하였다. 후면 버퍼층은 투명 전도 산화막 후면전극과 광흡수층 사이의 계면특성을 향상시키는 역할을 한다. In another embodiment of the present invention, the method may further comprise forming a back buffer layer after the a) and b). Specifically, a step of forming a rear buffer layer on the transparent conductive oxide rear electrode after step a) may be NaF or ZnO, and the thickness of the rear buffer layer formed is preferably 5 to 10 nm. In the following experiment example, the energy conversion efficiency of the solar cell according to the thickness of the back buffer layer was examined. As a result, it was confirmed that the efficiency decreased when the back buffer layer was thicker than 10 nm. The back buffer layer improves the interface characteristics between the transparent conductive oxide back electrode and the light absorption layer.

본 발명의 b) 단계는 상기 후면전극 상에 광흡수층을 형성하는 단계로서, 광흡수층은 CIS(Copper, Indium, Sulfur 또는 Selenide), CIGS(Copper, Indium, Galium, Sulfur 또는 Selenide) 또는 CZTS(Copper, Zinc, Tin, Sulfur 또는 Selenid) 계열일 수 있으며, 바람직하게는 CZTS 계열일 수 있다.The step b) of the present invention is a step of forming a light absorbing layer on the rear electrode, wherein the light absorbing layer is made of CIS (Copper, Indium, Sulfur or Selenide), CIGS (Copper, Indium, Galium, Sulfur or Selenide) , Zinc, Tin, Sulfur, or Selenid) series, preferably CZTS series.

상기 b) 단계의 광흡수층 형성은 전구체층을 형성하는 단계(단계 1); 및 상기 전구체층을 황화공정 또는 셀렌화공정을 통하여 광흡수층으로 형성하는 단계(단계 2);를 포함하는 방법으로 수행될 수 있다.The light absorption layer formation in the step b) includes forming a precursor layer (step 1); And a step (step 2) of forming the precursor layer as a light absorbing layer through a sulfiding step or a selenizing step.

CZTS계 박막을 광흡수층으로 형성하기 위해, 구리(Cu), 아연(Zn), 주석(Sn), 황(S) 및 셀레늄(Se) 중 1종 이상을 선택하여 전구체 박막을 구성할 수 있다.A precursor thin film can be formed by selecting at least one of copper (Cu), zinc (Zn), tin (Sn), sulfur (S) and selenium (Se) to form a CZTS thin film as a light absorbing layer.

이때, 상기 b) 단계에서 전구체층을 형성하는 단계(단계 1)는, Cu 층, Zn 층, Sn 층, CuS 층, ZnS 층, SnS 층, CuSe 층, ZnSe 층, SnSe 층, CuSSe 층, ZnSSe 층 및 SnSSe 층으로 이루어진 군으로부터 선택된 1종 이상의 층이 적층된 구조로 형성된 것일 수 있으나 이에 제한되는 것은 아니며, 열처리 후 광흡수층의 조성비 및 균일도를 고려하여 Zn-Sn-Cu의 순서로 형성될 수 있다.At this time, the step of forming the precursor layer in the step b) (step 1) may include a step of forming a precursor layer (Step 1) by forming a Cu layer, a Zn layer, a Sn layer, a CuS layer, a ZnS layer, a SnS layer, a CuSe layer, a ZnSe layer, Layer and a SnSSe layer may be stacked, but the present invention is not limited thereto, and may be formed in the order of Zn-Sn-Cu considering the composition ratio and uniformity of the light absorption layer after heat treatment. have.

여기서 산화막 버퍼층 및 전구체층을 형성은 스퍼터링법(sputtering), 동시증발증착법(evaporation), CVD법(Chemical vapor deposition), 유기금속화학기상증착(MOCVD), 근접승화법(Close-spaced sublimation, CSS), 스프레이 피롤리시스(Spray pyrolysis), 화학 스프레이법(Chemical spraying), 스크린프린팅법(Screeen printing), 비진공 액상성막법, CBD법(Chemical bath deposition), VTD법(Vapor transport deposition), 및 전착법(electrodeposition) 중에서 어느 하나의 방법에 의하여 증착될 수 있다. Here, the oxide buffer layer and the precursor layer may be formed by a sputtering method, a simultaneous evaporation method, a CVD method, a metal-organic chemical vapor deposition (MOCVD) method, a close-spaced sublimation (CSS) , Spray pyrolysis, chemical spraying, screen printing, non-vacuum liquid phase deposition, CBD (chemical bath deposition), VTD (vapor transport deposition), and electrodeposition And may be deposited by any one of electrodeposition methods.

상기 b) 단계에서 전구체층을 황화공정 또는 셀렌화공정을 통하여 광흡수층으로 형성하는 단계(단계 2)는 상기 1 단계를 통해 형성된 전구체층을 VI족 원소(S, Se) 함유 기체 분위기에서 챔버 내에서 열처리하는 단계이다. 이 때, 열처리는 예비열처리, 본 열처리, 후속열처리가 가능하다. 예비열처리 및 후속열처리의 경우 200℃ 내지 400℃의 온도에서 1분 내지 60분 동안 수행될 수 있으며, 본열처리의 경우, 400℃ 내지 700℃의 온도에서 1분 내지 120분 동안 수행될 수 있다. 다만, 조건에 따라서 본열처리를 제외한 예비열처리 및 후속열처리는 생략할 수도 있다. In the step b), the precursor layer is formed into a light absorption layer through a sulphidation process or a selenization process (step 2), the precursor layer formed in the step 1 is formed in a chamber containing a Group VI element (S, Se) . At this time, the heat treatment can be a preliminary heat treatment, a main heat treatment, and a subsequent heat treatment. In the case of the preliminary heat treatment and the subsequent heat treatment, the heat treatment may be performed at a temperature of 200 ° C to 400 ° C for 1 minute to 60 minutes, and in the case of the present heat treatment, at a temperature of 400 ° C to 700 ° C for 1 minute to 120 minutes. However, depending on the conditions, the preliminary heat treatment and the subsequent heat treatment excluding the present heat treatment may be omitted.

만약, 상기 황화공정이 400℃ 미만의 온도에서 수행되는 경우에는 CZTS계 흡수층의 4성분계 물질이 비정상적으로 형성되어 ZnS, Cu2S 등의 2차상이 생성되며, 흡수층의 결정성이 저하되어 광흡수 계수 및 전기적 특성이 저하되는 문제점이 있고, 상기 황화공정이 700℃를 초과하는 온도에서 수행되는 경우에는 기판의 변형으로 인해 소자의 특성이 구현되지 않는 문제점이 있다.If the sulfidation process is performed at a temperature lower than 400 ° C., the quaternary substance of the CZTS absorption layer is abnormally formed to generate a secondary phase such as ZnS and Cu 2 S, and the crystallinity of the absorption layer is lowered, There is a problem that the electrical characteristics are degraded. When the sulfurization process is performed at a temperature exceeding 700 ° C, the characteristics of the device are not realized due to the deformation of the substrate.

상기 열처리는 불활성 기체 분위기 하에서 700 내지 800 Torr 의 조건하에서 수행될 수 있으며, 전구체 구성원소의 손실을 최소화하기 위해서 760 내지 770 Torr가 적당할 수 있다. The heat treatment can be performed under an inert gas atmosphere at 700 to 800 Torr, and 760 to 770 Torr may be suitable in order to minimize the loss of the precursor constituent elements.

상기 황화공정 또는 셀렌화공정은 밀폐된 챔버 내에서 불활성 기체 분위기하에서 수행되는 것일 수 있다. 밀폐된 챔버를 사용하는 경우, 셀레늄 또는 황 원소의 침투를 효과적으로 진행할 수 있다. 상기 불활성 기체는 아르곤(Ar)일 수 있으나, 상기 불활성 기체가 이에 제한되는 것은 아니다.The sulfiding step or the selenization step may be performed in an inert gas atmosphere in a closed chamber. When a sealed chamber is used, penetration of selenium or sulfur element can be effectively carried out. The inert gas may be argon (Ar), but the inert gas is not limited thereto.

이러한 과정을 통해 형성된 상기 광흡수층의 두께는 50nm 내지 2㎛일 수 있다.The thickness of the light absorbing layer formed through this process may be 50 nm to 2 탆.

본 발명의 상기 c) 단계는 광흡수층 상에 버퍼층을 형성하는 단계이다.The step c) of the present invention is a step of forming a buffer layer on the light absorption layer.

상기 버퍼층은 진공공정, 열 증착공정 및 화학적 용액 성장법(Chemical Bath Deposition) 등으로 형성할 수 있으나, 상기 버퍼층의 형성 방법이 이에 제한되는 것은 아니다.The buffer layer may be formed by a vacuum process, a thermal deposition process, or a chemical solution deposition (Chemical Bath Deposition) method, but the method of forming the buffer layer is not limited thereto.

이때, 상기 버퍼층은 CdS, ZnS, Zn(O,S), CdZnS 및 ZnSe 등으로 제조할 수 있으나, 상기 버퍼층이 이에 제한되는 것은 아니다.At this time, the buffer layer may be made of CdS, ZnS, Zn (O, S), CdZnS, ZnSe or the like, but the buffer layer is not limited thereto.

한편, 상기 버퍼층의 두께는 10 내지 200nm일 수 있다.The thickness of the buffer layer may be 10 to 200 nm.

만약, 상기 버퍼층의 두께가 10 nm 미만이거나 200nm를 초과하는 경우에는 광투과율이 감소하며, 공핍층 폭의 증가로 인해 전자가 상부 전극으로 전달되기 어려운 문제점이 있다.If the thickness of the buffer layer is less than 10 nm or more than 200 nm, the light transmittance is decreased, and electrons are difficult to be transmitted to the upper electrode due to the increase of the depletion layer width.

본 발명의 상기 d) 단계는 버퍼층 상에 윈도우층을 형성하는 단계이다.The step d) of the present invention is a step of forming a window layer on the buffer layer.

상기 윈도우층은 스퍼터링법(sputtering), 진공공정, 열 증착공정 및 화학적 용액 성장법(Chemical Bath Deposition) 등의 방법으로 형성될 수 있으나, 상기 윈도우층의 형성방법이 이에 제한되는 것은 아니다.The window layer may be formed by a sputtering method, a vacuum method, a thermal deposition method, or a chemical solution deposition method, but the method of forming the window layer is not limited thereto.

이때, 윈도우층은 ZnO:Al, ZnO:AZO, ZnO:B(BZO) 및 ZnO:Ga(GZO)등으로 제조될 수 있으나, 상기 윈도우층이 이에 제한되는 것은 아니며, 광투과율이 높고 전기 전도성이 우수한 재료를 적절히 선택하여 사용할 수 있다. 본 발명의 하기 실시예에서는 ZnO(50nm):AZO(350nm)로 제조되었다.At this time, the window layer may be made of ZnO: Al, ZnO: AZO, ZnO: B (BZO) and ZnO: Ga (GZO), but the window layer is not limited thereto and may have a high light transmittance Excellent materials can be appropriately selected and used. In the following examples of the present invention, ZnO (50 nm): AZO (350 nm) was prepared.

한편, 상기 윈도우층의 두께는 100 내지 1000nm일 수 있다.Meanwhile, the thickness of the window layer may be 100 to 1000 nm.

만약, 상기 윈도우층의 두께가 100nm 미만이거나 1000nm 를 초과하는 경우에는 광투과율의 감소와 전류-전압 특성의 저하로 소자의 광효율이 감소하는 문제점이 발생할 수 있다.If the thickness of the window layer is less than 100 nm or more than 1000 nm, a decrease in light transmittance and a decrease in the current-voltage characteristic may cause a problem that the light efficiency of the device is reduced.

본 발명의 상기 e) 단계는 윈도우층 상에 전면전극을 형성하는 단계이다.The step e) of the present invention is a step of forming a front electrode on the window layer.

이때, 전면전극은 알루미늄이나 ITO, IZO, IGZO와 같은 투명전극을 사용할 수 있으나, 특별히 그 종류를 제한하는 것은 아니다. At this time, a transparent electrode such as aluminum, ITO, IZO, or IGZO may be used as the front electrode, but the kind thereof is not particularly limited.

이하, 실시예를 통하여 본 발명을 보다 상세히 설명하고자 한다. 이들 실시예는 본 발명을 보다 구체적으로 설명하기 위한 것으로, 본 발명의 범위가 이들 실시예에 한정되는 것은 아니다.Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are for further illustrating the present invention, and the scope of the present invention is not limited to these examples.

<< 실시예Example 1> 1>

투명 전도 산화막을 후면전극으로 이용한 태양전지 제조Manufacturing solar cell using transparent conductive oxide film as back electrode

플로린 도핑 주석 산화막(FTO)과 주석 도핑 인듐산화막(ITO)을 각각 650, 150 nm 증착된 SLG(Soda Lime Glass)기판을 아세톤, 메탄올로 각각 300℃, 초음파로 10분씩 세척 후 증류수로 세척하였다. FTO와 ITO의 두께는 면저항을 기준(30 Ω/sq)으로 결정되었다. Cu 전구체, Zn 전구체, Sn 전구체를 DC 스퍼터링으로 Cu, Zn, Sn 순수메탈 타켓을 이용해 Cu/Sn/Zn/후면전극 순으로 증착하였다. 준비된 광흡수층 전구체를 급속열처리장비(SNTEK, 09SN047)안의 챔버에 넣고 로터리 펌프로 진공을 3 mTorr 이하로 만든후 상압(760 Torr)으로 Ar가스를 채웠다. 이후 VI원소 함유 기체 분위기에서 300℃에서 1500초간 예비열처리를 하고 490℃에서 900초간 본열처리를 진행하여 광흡수층을 제작하였다. CdS 버퍼층을 Chemical Bath Depositon(CBD)방식으로 50nm 형성 후 원도우층으로 ZnO 50nm/ AZO 350nm를 스퍼터링으로 증착 후 동시증착기를 이용해 알루미늄(Al) 전면전극를 1㎛ 증착 후 소자 특성을 측정하였다. 소자 특성은 전면조사, 후면조사, 동시조사 세가지 경우에 따라 평가하였다. 이 때, 후면 전극의 종류를 표 1에 나타내었다.SLG (Soda Lime Glass) substrates deposited with 650 nm and 150 nm films were cleaned with acetone and methanol, respectively, at 300 ° C for 10 minutes by ultrasonication, and then washed with distilled water. The thickness of FTO and ITO was determined based on the sheet resistance (30 Ω / sq). Cu precursor, Zn precursor and Sn precursor were deposited by DC sputtering in order of Cu / Sn / Zn / rear electrode using Cu, Zn, Sn pure metal target. The prepared light absorbing layer precursor was placed in a chamber in a rapid thermal annealing equipment (SNTEK, 09SN047), the vacuum was made to 3 mTorr or less by a rotary pump, and Ar gas was filled at normal pressure (760 Torr). Thereafter, preliminary heat treatment was performed at 300 DEG C for 1500 seconds in a VI element-containing gas atmosphere, and this heat treatment was performed at 490 DEG C for 900 seconds to prepare a light absorption layer. After the CdS buffer layer was formed to 50 nm by Chemical Bath Deposition (CBD) method, ZnO 50 nm / AZO 350 nm was deposited as a window layer by sputtering, and then the aluminum (Al) front electrode was deposited to a thickness of 1 μm using a co-evaporator. The device characteristics were evaluated according to three cases of frontal irradiation, backward irradiation, and simultaneous irradiation. Table 1 shows the types of the rear electrodes.

실시예 1-1Example 1-1 실시예 1-2Examples 1-2 후면전극 투명 전도산화막 종류Rear electrode Transparent conductive oxide film type 플로린 도핑
산화주석(FTO)Florin doping
Tin oxide (FTO) 주석 도핑 산화인듐(ITO)Tin doped indium oxide (ITO)

<< 실험예Experimental Example 1> 1>

투명 전도 산화막을 후면전극으로 이용한 태양전지의 박막 흡수층과 후면전극의 계면 평가Interfacial Evaluation of Thin Film Absorption Layer and Backside Electrode of Solar Cell Using Transparent Conducting Oxide as Backside Electrode

실시예 1-1 및 실시예 1-2에 따른 CZTS계 흡수층 단면의SEM 사진을 촬영하여 흡수층의 계면을 평가하였다.SEM photographs of cross sections of the CZTS absorption layer according to Examples 1-1 and 1-2 were taken to evaluate the interface of the absorption layer.

그 결과 도3 및 4에서 나타낸 바와 같이, CZTS/FTO 계면에 비해 CZTS/ITO 계면이 공극이 많은 걸 알 수 있다. 열처리 과정에서 FTO 및 ITO 기판과 Cu/Sn/Zn 전구체 사이의 흡수층 반응과정이 상이한 걸 알 수 있다. 계면향상을 위해 완충 버퍼층 혹은 열처리 조건의 변화가 필요하다고 판단되었다.As a result, as shown in FIGS. 3 and 4, it can be seen that the CZTS / ITO interface has more vacancy than the CZTS / FTO interface. It can be seen that the reaction process of the absorption layer between the FTO and ITO substrate and the Cu / Sn / Zn precursor in the heat treatment process is different. It was determined that the buffer buffer layer or the heat treatment conditions need to be changed in order to improve the interface.

<< 실험예Experimental Example 2> 2>

투명 전도 산화막을 후면전극으로 이용한 태양전지의 Solar cell using transparent conductive oxide as back electrode 광전환Light conversion 효율의 평가 Evaluation of efficiency

실시예 1에 따른 투명전극을 포함하는 태양전지의 광전환 효율 비교하였다. 아래 표 2를 참조하면, 실시예 1-1, 1-2에 따른 CZTS계 태양전지의 전기적 특성이 전면조사에 비해 양면조사 시에 향상됨을 알 수 있다. 특히, 양면조사에서의 효율향상은 단락전류가 증가가 주된 원인으로, 개방전압은 그 반대로 전면조사 시와 비교해 조금 감소하는 것을 알 수 있다. 양면 조사 시 보인 효율 증가는 추후 양면태양전지 및 템덤태양전지의 후면전극으로서 투명전도산화막의 유효성을 보여주는 결과라고 할 수 있다.The light conversion efficiency of the solar cell including the transparent electrode according to Example 1 was compared. Referring to Table 2 below, it can be seen that the electrical characteristics of the CZTS-based solar cells according to Examples 1-1 and 1-2 are improved in the two-side irradiation as compared with the front irradiation. In particular, it can be seen that the improvement in efficiency in double-sided irradiation is mainly caused by an increase in short-circuit current, and the open-circuit voltage is slightly reduced as compared with the front-side irradiation. The increase in the efficiency of double-sided irradiation is a result of showing the effectiveness of the transparent conductive oxide film as a back electrode of the double-sided solar cell and the Temem solar cell.

조사Research η(%)侶 (%) Voc(V)Voc (V) Jsc(mA/cm2)Jsc (mA / cm 2 ) FF(%)FF (%) 실시예 1-1Example 1-1 양면조사Double-sided survey 4.154.15 0.3170.317 36.236.2 36.236.2 전면조사Front survey 3.513.51 0.3330.333 27.427.4 38.538.5 후면조사Back investigation 0.770.77 0.2400.240 10.310.3 31.231.2 실시예 1-2Examples 1-2 양면조사Double-sided survey 3.943.94 0.3170.317 37.137.1 33.533.5 전면조사Front survey 3.213.21 0.3140.314 28.128.1 36.336.3 후면조사Back investigation 0.770.77 0.2330.233 10.510.5 31.331.3

<< 실시예Example 2> 2>

투명 전도 산화막을 후면전극으로 이용하고 상부에 후면 A transparent conductive oxide film is used as the back electrode, 버퍼층이The buffer layer 도입된 태양전지 제조 Manufacture of introduced solar cell

상기 실시예 1을 통해 제조된 태양전지의 계면향상을 위해 후면전극 상부에 후면 버퍼층을 도입하였다. In order to improve the interface of the solar cell manufactured in Example 1, a rear buffer layer was introduced on the rear electrode.

플로린 도핑 주석 산화막(FTO)과 주석 도핑 인듐산화막(ITO)을 각각 650, 150 nm 증착된 SLG(Soda Lime Glass)기판을 아세톤, 메탄올로 각각 300℃, 초음파로 10분씩 세척 후 증류수로 세척하였다. FTO와 ITO의 두께는 면저항을 기준(30 Ω/sq)으로 결정되었다. 후면전극 상부에 후면 버퍼층으로 NaF 및 ZnO 각각을 5, 10, 20nm 두께로 형성하였다. 이때, 후면전극으로 FTO를 이용한 경우 상부에 버퍼층으로 ZnO를 형성하였으며, 후면전극으로 ITO를 이용한 경우 상부에 버퍼층으로 NaF를 형성하였다. NaF 버퍼층은 열진공증착기(Thermal Evaporator)를 이용해 0.1 nm/s의 증착속도로 증착하였으며, ZnO 버퍼층은 RF스퍼터링을 이용해 Ar/O2 양을 각각 60/10 sccm, Ar압력 10 mTorr, 스퍼터 파워 200W, 상온에서 증착하였다. 이후 Cu 전구체, Zn 전구체, Sn 전구체를 DC 스퍼터링으로 Cu, Zn, Sn 순수메탈 타켓을 이용해 Cu/Sn/Zn/Mo순으로 증착하였다. 준비된 광흡수층 전구체를 급속열처리장비(SNTEK, 09SN047)안의 챔버에 넣고 로터리 펌프로 진공을 3 mTorr이하로 만든후 상압(760 Torr)으로 Ar가스를 채웠다. 이 후 VI원소 함유 기체 분위기에서 300℃에서 1500초간 예비열처리를 하고 490℃에서 900초간 본열처리를 진행하여 광흡수층을 제작하였다. CdS 버퍼층을 Chemical Bath Depositon(CBD)방식으로 50nm 형성 후 원도우층으로 ZnO 50nm/ AZO 350nm를 스퍼터링으로 증착 후 동시증착기를 이용해 알루미늄(Al) 전면전극를 1㎛ 증착 후 소자 특성을 측정하였다. 소자 특성은 양면조사, 전면조사 및 후면조사로 각각 평가하였다. 이 때, 후면전극의 종류 및 버퍼층의 종류를 표 3에 나타내었다.SLG (Soda Lime Glass) substrates deposited with 650 nm and 150 nm films were cleaned with acetone and methanol, respectively, at 300 ° C for 10 minutes by ultrasonication, and then washed with distilled water. The thickness of FTO and ITO was determined based on the sheet resistance (30 Ω / sq). NaF and ZnO were formed as back buffer layers on the back electrode at 5, 10 and 20 nm, respectively. In this case, ZnO was formed as a buffer layer on the upper surface when FTO was used as a back electrode, and NaF was formed on the upper surface of ITO as a buffer layer. The NaF buffer layer was deposited at a deposition rate of 0.1 nm / s using a thermal evaporator. The ZnO buffer layer was deposited by RF sputtering using Ar / O2 at 60/10 sccm, Ar pressure of 10 mTorr, sputter power of 200 W, Lt; / RTI &gt; Then Cu precursor, Zn precursor and Sn precursor were deposited by DC sputtering in order of Cu / Sn / Zn / Mo using Cu, Zn, and Sn pure metal targets. The prepared light absorbing layer precursor was placed in a chamber in a rapid thermal annealing equipment (SNTEK, 09SN047), the vacuum was made to 3 mTorr or less by a rotary pump, and Ar gas was filled at normal pressure (760 Torr). After this, preliminary heat treatment was performed at 300 캜 for 1500 seconds in a VI element-containing gas atmosphere, and this heat treatment was performed at 490 캜 for 900 seconds to prepare a light absorbing layer. After the CdS buffer layer was formed to 50 nm by Chemical Bath Deposition (CBD) method, ZnO 50 nm / AZO 350 nm was deposited as a window layer by sputtering, and then the aluminum (Al) front electrode was deposited to a thickness of 1 μm using a co-evaporator. The device characteristics were evaluated by two-side irradiation, frontal irradiation and backward irradiation, respectively. At this time, the type of the rear electrode and the type of the buffer layer are shown in Table 3.

후면전극 종류Rear Electrode Type 버퍼층 종류Buffer layer type 버퍼층 두께Buffer layer thickness 실시예 2-1Example 2-1 FTOFTO ZnOZnO 5nm5 nm 실시예 2-2Example 2-2 FTOFTO ZnOZnO 10nm10 nm 실시예 2-3Example 2-3 FTOFTO ZnOZnO 20nm20 nm 실시예 2-4Examples 2-4 ITOITO NaFNaF 5nm5 nm 실시예 2-5Example 2-5 ITOITO NaFNaF 10nm10 nm 실시예 2-6Examples 2-6 ITOITO NaFNaF 20nm20 nm

<< 실험예Experimental Example 3> 3>

투명 전도 산화막을 후면전극으로 이용하고 상부에 후면 A transparent conductive oxide film is used as the back electrode, 버퍼층이The buffer layer 도입된 태양전지의  Of the introduced solar cell 광전환Light conversion 효율의 평가 Evaluation of efficiency

실시예 2에 따른 태양전지의 광전환 효율 비교하였다. 아래 표 4을 참조하면, 실시예 2에 따른 CZTS계 태양전지의 전기적 특성의 경우, 후면전극 상부에 버퍼층이 도입되지 않은 대조군 대비 버퍼층이 도입된 태양전지의 광전환 효율이 높아지는 것을 확인할 수 있었다. 또한, ZnO, NaF 두께에 따라 각각 10nm, 5nm에서 효율이 가장 높았으며 그보다 두께가 높아지면 효율이 감소하는 것을 확인하였다. 특히, 후면전극으로 플로린 도핑 산화주석(FTO)을 사용하고 여기에 후면 버퍼층으로 ZnO이 10nm로 형성된 태양전지의 경우 양면조사시 광전환 효율이 대조군 및 다른 실시예 대비 두드러지게 증대된 것을 확인할 수 있었다.The light conversion efficiency of the solar cell according to Example 2 was compared. Referring to Table 4 below, it can be seen that the electrical characteristics of the CZTS solar cell according to Example 2 are higher than that of the control electrode in which the buffer layer is not formed above the rear electrode. In addition, the efficiency was the highest at 10 nm and 5 nm depending on the thickness of ZnO and NaF, respectively, and it was confirmed that the efficiency decreased as the thickness increased. Particularly, it was confirmed that the photoconversion efficiency of the photovoltaic cell in the case of using the FTO as the back electrode and the 10 nm thick ZnO layer as the back buffer layer was remarkably increased in comparison with the control group and the other examples .

조사Research 항목Item η(%)侶 (%) Voc(V)Voc (V) Jsc(mA/cm2)Jsc (mA / cm 2 ) FF(%)FF (%) 양면조사Double-sided survey FTO(Reference)FTO (Reference) 4.154.15 0.3170.317 36.236.2 36.236.2 ZnO 5nm/FTOZnO 5 nm / FTO 4.894.89 0.3530.353 38.438.4 36.236.2 ZnO 10nm/FTOZnO 10 nm / FTO 5.505.50 0.3450.345 38.338.3 41.741.7 ZnO 20nm/FTOZnO 20 nm / FTO 4.354.35 0.3190.319 38.638.6 35.335.3 ITO(Reference)ITO (Reference) 3.943.94 0.3170.317 37.137.1 33.533.5 NaF 5nm/ITONaF 5 nm / ITO 4.504.50 0.3520.352 41.741.7 30.630.6 NaF 10nm/ITONaF 10 nm / ITO 3.553.55 0.3230.323 34.134.1 32.332.3 NaF 20nm/ITONaF 20 nm / ITO 1.141.14 0.1870.187 23.323.3 26.126.1 전면조사Front survey FTO(Reference)FTO (Reference) 3.513.51 0.3330.333 27.427.4 38.538.5 ZnO 5nm/FTOZnO 5 nm / FTO 3.993.99 0.3650.365 28.728.7 38.038.0 ZnO 10nm/FTOZnO 10 nm / FTO 4.564.56 0.3540.354 28.728.7 44.944.9 ZnO 20nm/FTOZnO 20 nm / FTO 3.503.50 0.3290.329 28.928.9 36.736.7 ITO(Reference)ITO (Reference) 3.213.21 0.3140.314 28.128.1 36.336.3 NaF 5nm/ITONaF 5 nm / ITO 3.743.74 0.3570.357 33.233.2 31.631.6 NaF 10nm/ITONaF 10 nm / ITO 2.982.98 0.3110.311 26.326.3 36.436.4 NaF 20nm/ITONaF 20 nm / ITO 0.730.73 0.1580.158 17.817.8 26.026.0 후면조사Back investigation FTO(Reference)FTO (Reference) 0.770.77 0.2400.240 10.310.3 31.231.2 ZnO 5nm/FTOZnO 5 nm / FTO 1.111.11 0.2960.296 10.710.7 34.934.9 ZnO 10nm/FTOZnO 10 nm / FTO 1.121.12 0.2890.289 10.710.7 36.236.2 ZnO 20nm/FTOZnO 20 nm / FTO 0.840.84 0.2480.248 10.610.6 31.731.7 ITO(Reference)ITO (Reference) 0.770.77 0.2330.233 10.510.5 31.331.3 NaF 5nm/ITONaF 5 nm / ITO 1.201.20 0.2950.295 11.011.0 36.936.9 NaF 10nm/ITONaF 10 nm / ITO 0.890.89 0.2680.268 10.110.1 32.932.9 NaF 20nm/ITONaF 20 nm / ITO 0.240.24 0.1550.155 6.16.1 25.025.0

이제까지 본 발명에 대하여 그 바람직한 실시예들을 중심으로 살펴보았다. 본 발명이 속하는 기술 분야에서 통상의 지식을 가진 자는 본 발명이 본 발명의 본질적인 특성에서 벗어나지 않는 범위에서 변형된 형태로 구현될 수 있음을 이해할 수 있을 것이다. 그러므로 개시된 실시예들은 한정적인 관점이 아니라 설명적인 관점에서 고려되어야 한다. 본 발명의 범위는 전술한 설명이 아니라 특허청구범위에 나타나 있으며, 그와 동등한 범위 내에 있는 모든 차이점은 본 발명에 포함된 것으로 해석되어야 할 것이다.The present invention has been described with reference to the preferred embodiments. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is defined by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present invention.

100: 기판
200: 후면전극
300: 후면 버퍼층
400: 광흡수층
500: 버퍼층
600: 윈도우층(Intrinsic Layer)
700: 윈도우층
800: 전면전극100: substrate
200: rear electrode
300: rear buffer layer
400: light absorbing layer
500: buffer layer
600: Window layer (Intrinsic Layer)
700: window layer
800: front electrode

Claims (23)

박막 태양전지로서,
상기 박막 태양전지는 기판, 투명 전도 산화막 후면전극, 후면 버퍼층, 광흡수층, 버퍼층, 윈도우층 및 전면전극이 순차적으로 형성되어 있으며,
상기 후면 버퍼층은 NaF 또는 ZnO인 박막 태양전지.As thin film solar cells,
The thin film solar cell includes a substrate, a transparent conductive oxide back electrode, a rear buffer layer, a light absorption layer, a buffer layer, a window layer, and a front electrode sequentially formed,
Wherein the back buffer layer is NaF or ZnO. 삭제delete 삭제delete 제1항에 있어서,
상기 투명 전도 산화막 후면전극은 알루미늄 도핑 아연 산화막(AZO), 주석 도핑 인듐 산화막(ITO), 플로린 도핑 주석 산화막(FTO), 아연 산화막(ZnO), 주석 산화막(SnO2), 카드뮴 산화막(CdO), 인듐 산화막(In2O3), 갈륨 산화막(Ga2O3)으로 이루어진 군으로부터 선택된 1종 이상인 것을 특징으로 하는 박막 태양전지.The method according to claim 1,
The transparent conductive oxide rear electrode may include at least one selected from the group consisting of an aluminum-doped zinc oxide (AZO), a tin-doped indium oxide (ITO), a flourine doped tin oxide (FTO), a zinc oxide (ZnO), a tin oxide (SnO 2 ), a cadmium oxide An indium oxide film (In 2 O 3 ), and a gallium oxide film (Ga 2 O 3 ). 제1항에 있어서,
상기 투명 전도 산화막 후면전극의 두께는 10 내지 700nm인 것을 특징으로 하는 박막 태양전지.The method according to claim 1,
And the thickness of the transparent conductive oxide film rear electrode is 10 to 700 nm. 삭제delete 제1항에 있어서,
상기 후면 버퍼층의 두께는 5 내지 10nm인 것을 특징으로 하는 박막 태양전지.The method according to claim 1,
Wherein the thickness of the back buffer layer is 5 to 10 nm. 제1항에 있어서,
상기 광흡수층은 CIS(Copper, Indium, Sulfur 또는 Selenide), CIGS(Copper, Indium, Galium, Sulfur 또는 Selenide) 또는 CZTS(Copper, Zinc, Tin, Sulfur 또는 Selenid) 중 선택되는 것을 특징으로 하는 박막 태양전지.The method according to claim 1,
Wherein the light absorption layer is selected from among CIS (Copper, Indium, Sulfur or Selenide), CIGS (Copper, Indium, Galium, Sulfur or Selenide), or CZTS (Copper, Zinc, Tin, Sulfur or Selenide) . 제1항에 있어서,
상기 태양전지는 양면에서 빛을 흡수하여 소자효율이 증대되는 것을 특징으로 하는 박막 태양전지.The method according to claim 1,
Wherein the solar cell absorbs light on both sides to increase device efficiency. a) 투명 전도 산화막 후면전극이 형성된 기판을 준비하는 단계;
b) 상기 후면전극 상에 후면 버퍼층으로 NaF 또는 ZnO을 형성한 후 광흡수층을 형성하는 단계;
c) 상기 광흡수층 상에 버퍼층을 형성하는 단계;
d) 상기 버퍼층 상에 윈도우층을 형성하는 단계; 및
e) 상기 윈도우층 상에 전면전극을 형성하는 단계를 포함하는, 박막 태양전지의 제조방법.a) preparing a substrate on which a transparent conductive oxide film rear electrode is formed;
b) forming a light absorbing layer after forming NaF or ZnO as a rear buffer layer on the rear electrode;
c) forming a buffer layer on the light absorption layer;
d) forming a window layer on the buffer layer; And
e) forming a front electrode on the window layer. 제10항에 있어서,
상기 a) 단계에서 기판에 형성되는 투명 전도 산화막 후면전극의 두께는 10 내지 700nm인 것을 특징으로 하는 박막 태양전지의 제조방법.11. The method of claim 10,
Wherein the thickness of the transparent conductive oxide back electrode formed on the substrate in the step a) is 10 to 700 nm. 제10항에 있어서,
상기 투명 전도 산화막 후면전극은 알루미늄 도핑 아연 산화막(AZO), 주석 도핑 인듐 산화막(ITO), 플로린 도핑 주석 산화막(FTO), 아연 산화막(ZnO), 주석 산화막(SnO2), 카드뮴 산화막(CdO), 인듐 산화막(In2O3), 갈륨 산화막(Ga2O3)으로 이루어진 군으로부터 선택된 1종 이상인 것을 특징으로 하는 박막 태양전지의 제조방법.11. The method of claim 10,
The transparent conductive oxide rear electrode may include at least one selected from the group consisting of an aluminum-doped zinc oxide (AZO), a tin-doped indium oxide (ITO), a flourine doped tin oxide (FTO), a zinc oxide (ZnO), a tin oxide (SnO 2 ), a cadmium oxide (In 2 O 3 ), gallium oxide (Ga 2 O 3 ), and the like. 제10항에 있어서,
상기 a)단계에서 투명 전도 산화막 후면전극은 스퍼터링법(sputtering), 증발법(evaporation), CVD법(Chemical vapor deposition), 유기금속화학기상증착(MOCVD), 근접승화법(Close-spaced sublimation, CSS), 스프레이 피롤리시스(Spray pyrolysis), 화학 스프레이법(Chemical spraying), 스크린프린팅법(Screeen printing), 비진공 액상성막법, CBD법(Chemical bath deposition), VTD법(Vapor transport deposition), 및 전착법(electrodeposition) 중에서 선택된 어느 하나의 방법으로 형성되는 것을 특징으로 하는 박막 태양전지 제조방법.11. The method of claim 10,
In the step a), the transparent conductive oxide rear electrode may be formed by sputtering, evaporation, CVD (Chemical Vapor Deposition), MOCVD, Close-spaced sublimation (CSS) , Spray pyrolysis, chemical spraying, screen printing, non-vacuum liquid phase film deposition, CBD chemical vapor deposition, VTD vapor deposition, Wherein the thin film solar cell is formed by any one method selected from electrodeposition. 삭제delete 제10항에 있어서,
상기 후면 버퍼층의 두께는 5 내지 10nm로 형성되는 것을 특징으로 하는 박막 태양전지의 제조방법.11. The method of claim 10,
Wherein the thickness of the back buffer layer is 5 to 10 nm. 제10항에 있어서,
상기 b) 단계의 광흡수층은 CIS(Copper, Indium, Sulfur 또는 Selenide), CIGS(Copper, Indium, Galium, Sulfur 또는 Selenide) 또는 CZTS(Copper, Zinc, Tin, Sulfur 또는 Selenid) 중 선택되는 것을 특징으로 하는 박막 태양전지의 제조방법.11. The method of claim 10,
The light absorption layer in the step b) is selected from CIS (Copper, Indium, Sulfur or Selenide), CIGS (Copper, Indium, Galium, Sulfur or Selenide) or CZTS (Copper, Zinc, Tin, Sulfur or Selenide) Wherein the method comprises the steps of: 제10항에 있어서,
상기 b) 단계에서 광흡수층은 금속 전구체를 후면전극 상에 증착한 후 VI족 원소 함유 기체 분위기 하에서 열처리하여 형성되는 것을 특징으로 하는 박막 태양전지의 제조방법.11. The method of claim 10,
Wherein the light absorbing layer is formed by depositing a metal precursor on a rear electrode and then performing heat treatment in a group VI element-containing gas atmosphere in the step b). 제17항에 있어서,
상기 VI족 원소는 황, 셀레늄 또는 이들의 혼합물인 것을 특징으로 하는 박막 태양전지의 제조방법.18. The method of claim 17,
Wherein the Group V element is sulfur, selenium or a mixture thereof. 제17항에 있어서,
상기 열처리는 200℃ 내지 400℃의 온도에서 1분 내지 60분 동안 예비열처리를 수행한 후, 400℃ 내지 700℃의 온도에서 1분 내지 120분 동안 본열처리를 수행하는 것을 특징으로 하는 박막 태양전지의 제조방법.18. The method of claim 17,
Wherein the heat treatment is performed by performing a preliminary heat treatment at a temperature of 200 ° C to 400 ° C for 1 minute to 60 minutes and then performing the present heat treatment at a temperature of 400 ° C to 700 ° C for 1 minute to 120 minutes. &Lt; / RTI &gt; 제19항에 있어서,
상기 본열처리는 700내지 800 Torr 압력에서 진행되는 것을 특징으로 하는 태양전지의 제조방법.20. The method of claim 19,
Wherein the heat treatment is performed at a pressure of 700 to 800 Torr. 제10항에 있어서,
상기 b) 단계의 광흡수층은 50 nm 내지 2 ㎛의 두께로 형성되는 것을 특징으로 하는 태양전지의 제조방법.11. The method of claim 10,
Wherein the light absorption layer in step b) is formed to a thickness of 50 nm to 2 占 퐉. 제10항에 있어서,
상기 c) 단계의 버퍼층은 CdS, ZnS, Zn(O,S), CdZnS 및 ZnSe로 이루어지는 군으로부터 선택되는 1종 이상인 것을 특징으로 하는 박막 태양전지의 제조방법.11. The method of claim 10,
Wherein the buffer layer in step c) is at least one selected from the group consisting of CdS, ZnS, Zn (O, S), CdZnS, and ZnSe. 제10항에 있어서,
상기 d) 단계의 윈도우층은 ZnO:Al, ZnO:AZO, ZnO:B(BZO) 및 ZnO:Ga(GZO)로 이루어지는 군으로부터 선택되는 1종 이상인 것을 특징으로 하는 박막 태양전지의 제조방법.11. The method of claim 10,
Wherein the window layer in the step d) is at least one selected from the group consisting of ZnO: Al, ZnO: AZO, ZnO: B (BZO), and ZnO: Ga (GZO).
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