TW201427054A - Photoelectric conversion element and method of producing the same, manufacturing method for buffer layer of photoelectric conversion element, and solar cell - Google Patents

Photoelectric conversion element and method of producing the same, manufacturing method for buffer layer of photoelectric conversion element, and solar cell Download PDF

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TW201427054A
TW201427054A TW102141974A TW102141974A TW201427054A TW 201427054 A TW201427054 A TW 201427054A TW 102141974 A TW102141974 A TW 102141974A TW 102141974 A TW102141974 A TW 102141974A TW 201427054 A TW201427054 A TW 201427054A
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photoelectric conversion
layer
buffer layer
group
substrate
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TW102141974A
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Keigo Sato
Tetsuo Kawano
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Fujifilm Corp
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    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L31/00Semiconductor devices sensitive to infra-red radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/04Semiconductor devices sensitive to infra-red radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/06Semiconductor devices sensitive to infra-red radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by at least one potential-jump barrier or surface barrier
    • H01L31/072Semiconductor devices sensitive to infra-red radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by at least one potential-jump barrier or surface barrier the potential barriers being only of the PN heterojunction type
    • H01L31/0749Semiconductor devices sensitive to infra-red radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by at least one potential-jump barrier or surface barrier the potential barriers being only of the PN heterojunction type including a AIBIIICVI compound, e.g. CdS/CulnSe2 [CIS] heterojunction solar cells
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L31/00Semiconductor devices sensitive to infra-red radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/0248Semiconductor devices sensitive to infra-red radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies
    • H01L31/036Semiconductor devices sensitive to infra-red radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by their crystalline structure or particular orientation of the crystalline planes
    • H01L31/0392Semiconductor devices sensitive to infra-red radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by their crystalline structure or particular orientation of the crystalline planes including thin films deposited on metallic or insulating substrates ; characterised by specific substrate materials or substrate features or by the presence of intermediate layers, e.g. barrier layers, on the substrate
    • H01L31/03923Semiconductor devices sensitive to infra-red radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by their crystalline structure or particular orientation of the crystalline planes including thin films deposited on metallic or insulating substrates ; characterised by specific substrate materials or substrate features or by the presence of intermediate layers, e.g. barrier layers, on the substrate including AIBIIICVI compound materials, e.g. CIS, CIGS
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00Energy generation through renewable energy sources
    • Y02E10/50Photovoltaic [PV] energy
    • Y02E10/541CuInSe2 material PV cells
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02PCLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50Manufacturing or production processes characterised by the final manufactured product

Abstract

The present invention provides a photoelectric conversion element having a buffer layer which suppresses characteristics variation among elements. The photoelectric conversion element has a bottom electrode layer 20, a photoelectric conversion layer 30, a buffer layer 40, and a translucent conductive layer 60 laminated on a substrate 10, wherein the photoelectric conversion layer contains a compound semiconductor of a chalcopyrite structure of at least one of group Ib element, group IIIb element and group VIb element as a main component. The buffer layer 40 comprises a compound with an alkali metal, which is at least one of lithium, sodium, and potassium. A content of the alkali metal in the compound forming the buffer layer is 0.1at% to 5at%.

Description

光電轉換元件及光電轉換元件的緩衝層的製造方法 Method for manufacturing buffer layer of photoelectric conversion element and photoelectric conversion element

本發明是有關於用於太陽電池、CCD(固態感測元件)感測器等的光電變換元件與光電變換元件的緩衝層的製造方法,以及光電變換元件的製造方法。 The present invention relates to a method of manufacturing a buffer layer for a photoelectric conversion element and a photoelectric conversion element of a solar cell, a CCD (Solid State Sensor) sensor, and the like, and a method of manufacturing the photoelectric conversion element.

具備有光電變換層及與其導通的電極的光電變換元件用於太陽電池等用途。以往,在太陽電池中,採用塊狀(Bulk)的單晶矽或多晶矽,或是薄膜的非晶矽的矽系太陽電池蔚為主流。不仰賴矽的化合物半導體系太陽電池的研究開發一直在進行。以化合物半導體系的太陽能電池而言,GaAs(砷化鎵)系等的塊狀系以及包含Ib族元素與IIIb族元素與VIb族元素的CIS(銅銦硒)或是CIGS(銅銦鎵硒)等的薄膜系都已為人所知。CI(G)S是以一般式Cu1-zIn1-xGaxSe2-ySy(式中,0≦x≦1,0≦y≦2,0≦z≦1)表示的化合物半導體,x=0的時候為CIS系,x>0的時候為CIGS系。在本說明書中,CIS與CIGS是合併以「CI(G)S」記述。 A photoelectric conversion element including a photoelectric conversion layer and an electrode that is electrically connected thereto is used for applications such as solar cells. In the past, in solar cells, monocrystalline germanium or polycrystalline germanium in bulk, or amorphous germanium solar cells in thin films have been the mainstream. Research and development of compound semiconductor solar cells that do not rely on bismuth have been ongoing. In a compound semiconductor-based solar cell, a bulk system such as GaAs (gallium arsenide) or a CIS (copper indium selenide) or CIGS (copper indium gallium selenide) containing a group Ib element and a group IIIb element and a group VIb element Film systems such as those are well known. CI(G)S is a compound represented by the general formula Cu 1-z In 1-x Ga x Se 2-y S y (wherein, 0≦x≦1, 0≦y≦2, 0≦z≦1) The semiconductor is a CIS system when x=0, and a CIGS system when x>0. In the present specification, CIS and CIGS are combined and described as "CI(G)S".

在CI(G)S系等以往的薄膜系光電變換元件中,一般來說,在光電變換層與其上形成的透光性導電層之間設有CdS(硫化 鎘)緩衝層。在這樣的系統中通常是藉由化學浴沉積法(CBD法:Chemical Bath Deposition)使緩衝層加以成膜。 In a conventional thin film photoelectric conversion element such as CI (G)S system, generally, CdS (vulcanization) is provided between the photoelectric conversion layer and the light-transmitting conductive layer formed thereon. Cadmium) buffer layer. In such a system, the buffer layer is usually formed into a film by a chemical bath deposition method (CBD method: Chemical Bath Deposition).

近年來,考量到環境負荷而對緩衝層的無Cd化(Cd free)進行研究探討。對作為無Cd緩衝層之主成分的Zn(S,O)等的鋅系化合物加以研究。 In recent years, the Cd free of the buffer layer has been studied in consideration of the environmental load. A zinc-based compound such as Zn(S, O) which is a main component of the Cd-free buffer layer is studied.

在專利文獻1、專利文獻2中提出了包含Zn(S,O)系的緩衝層的光電變換元件的製造方法。 Patent Document 1 and Patent Document 2 propose a method of manufacturing a photoelectric conversion element including a Zn (S, O) based buffer layer.

【先行技術文獻】 [First technical literature]

【專利文獻】 [Patent Literature]

【專利文獻1】特開2011-119764號公報 [Patent Document 1] JP-A-2011-119764

【專利文獻2】特開2012-18953號公報 [Patent Document 2] JP-A-2012-18953

然而,由本發明者們的研究中已明白地知道,將應用了以往的Zn系化合物緩衝層的CIGS光電變換元件加以積體化而得到的太陽電池的光電變換效率,從單電池胞來看比預期更低。本發明者們發現,具備了包含Zn系化合物的緩衝層的光電變換元件,在電池胞間的特性偏差非常的大,因此,對大面積的太陽電池來說(例如,將多個單電池胞串聯連接而成子模組),特性受到較低效率的電池胞的影響,有無法顯現預期性能的情況。 However, it has been clarified by the inventors of the present invention that the photoelectric conversion efficiency of a solar cell obtained by integrating a CIGS photoelectric conversion element to which a conventional Zn-based compound buffer layer is applied is seen from a single cell. Expected to be lower. The present inventors have found that a photoelectric conversion element including a buffer layer containing a Zn-based compound has a very large variation in characteristics between cells, and therefore, for a large-area solar cell (for example, a plurality of single cell cells) The sub-modules are connected in series, and the characteristics are affected by the battery cells with lower efficiency, and the expected performance cannot be exhibited.

與Cds系緩衝層比較,Zn系化合物緩衝層的均勻性較低,因此認為電池胞間的偏差比較大。因此,在開發包含Zn系化合物緩衝層的光電變換元件的時候,在提升光電變換效率的同時,降低電池胞間的特性偏差是相當重要。並且,較佳是電池胞 間的特性偏差小者,並不只限於Zn系化合物緩衝層,在包含任何組成的化合物的緩衝層的情況下也是相同。 Compared with the Cds-based buffer layer, the uniformity of the Zn-based compound buffer layer is low, and therefore it is considered that the variation between the cell cells is relatively large. Therefore, when developing a photoelectric conversion element including a buffer layer of a Zn-based compound, it is important to reduce the variation in characteristics between the cells while improving the photoelectric conversion efficiency. And, preferably, the battery cell The difference in characteristics between the two is not limited to the Zn-based compound buffer layer, and is also the same in the case of a buffer layer containing a compound of any composition.

有鑑於上述狀況,本發明的目的在於提供具備有可抑制元件間特性偏差的緩衝層的光電變換元件。 In view of the above circumstances, an object of the present invention is to provide a photoelectric conversion element including a buffer layer capable of suppressing variations in characteristics between elements.

另外,本發明的目的在於除了提供可抑制元件的特性偏差的緩衝層的製造方法,更進一步地提供應用該緩衝層的製造方法的光電變換元件的製造方法。 Further, an object of the present invention is to provide a method for producing a buffer layer which can suppress variation in characteristics of an element, and to further provide a method for producing a photoelectric conversion element to which the method for producing a buffer layer is applied.

本發明的光電變換元件,其是在基板上積層有底電極層與光電變換層、緩衝層與透光性導電層的光電變換元件,上述光電變換層以包含Ib族元素、IIIb族元素與VIb族元素中至少一種的黃銅礦(Chalcopyrite)構造的化合物半導體作為主成分,其特徵在於:緩衝層包括含有鹼金屬的化合物,鹼金屬為鋰、鈉及鉀中的至少一種,上述化合物中的鹼金屬的含量為0.1at%以上、5at%以下。 The photoelectric conversion element of the present invention is a photoelectric conversion element in which a bottom electrode layer, a photoelectric conversion layer, a buffer layer, and a light-transmitting conductive layer are laminated on a substrate, and the photoelectric conversion layer contains an Ib group element, a Group IIIb element, and VIb. a compound semiconductor of a chalcopyrite structure of at least one of the group elements as a main component, wherein the buffer layer comprises an alkali metal-containing compound, and the alkali metal is at least one of lithium, sodium and potassium, among the above compounds The content of the alkali metal is 0.1 at% or more and 5 at% or less.

構成緩衝層的化合物較佳的是含有金屬、硫及氧。金屬是選自於包含Cd、Zn、In及Sn所組成的群組中的至少一種。 The compound constituting the buffer layer preferably contains a metal, sulfur and oxygen. The metal is at least one selected from the group consisting of Cd, Zn, In, and Sn.

進一步,上述金屬為Zn、In及Sn中的任一種,特別是Zn為較佳。 Further, the above metal is any one of Zn, In and Sn, and particularly Zn is preferable.

鹼金屬的含量較佳的是在0.5at%以上、2.5at%以下。 The content of the alkali metal is preferably 0.5 at% or more and 2.5 at% or less.

緩衝層的厚度較佳的是在1nm以上、100nm以下。 The thickness of the buffer layer is preferably 1 nm or more and 100 nm or less.

較佳的是,Ib族元素是選自Cu及Ag所組成的群組中的至少一種,IIIb族元素是選自Al、Ga及In所組成的群組中的至少一種,VIb族元素是選自S、Se及Te所組成的群組中的至少一種。 Preferably, the Group Ib element is at least one selected from the group consisting of Cu and Ag, and the Group IIIb element is at least one selected from the group consisting of Al, Ga, and In, and the Group VIb element is selected. At least one of the group consisting of S, Se, and Te.

本發明的太陽電池,其特徵在於是將本發明之光電變換元件多個積體化而形成。 The solar cell of the present invention is characterized in that a plurality of photoelectric conversion elements of the present invention are integrated.

本發明的緩衝層的製造方法,其是在基板上積層有底電極層、光電變換層、緩衝層、透光性導電層之光電變換元件的緩衝層的製造方法,上述的光電變換層以包含Ib族元素、IIIb族元素與VIb族元素中至少一種的黃銅礦構造的化合物半導體作為主成分,其特徵在於:準備含有規定的金屬離子、硫脲、1M以上的鹼金屬離子的化學浴沉積用的反應液,使在基板上將底電極層及光電變換層以此順序積層而成的緩衝成膜用基板的至少上述光電變換層的表面接觸反應液,藉此在光電變換層表面上析出緩衝層。 The method for producing a buffer layer according to the present invention is a method for producing a buffer layer in which a bottom electrode layer, a photoelectric conversion layer, a buffer layer, and a light-transmitting conductive layer of a photoelectric conversion element are laminated on a substrate, and the photoelectric conversion layer is included A compound semiconductor of a chalcopyrite structure of at least one of a group Ib element, a group IIIb element and a group VIb element as a main component, wherein a chemical bath deposition containing a predetermined metal ion, thiourea, or an alkali metal ion of 1 M or more is prepared. In the reaction liquid to be used, at least the surface of the photoelectric conversion layer of the buffer film formation substrate in which the bottom electrode layer and the photoelectric conversion layer are laminated in this order is brought into contact with the reaction liquid, thereby depositing on the surface of the photoelectric conversion layer. The buffer layer.

規定的金屬較佳為Cd、Zn、In、Sn中的至少一種,Zn、In或Sn更佳,特別好的是Zn。 The predetermined metal is preferably at least one of Cd, Zn, In, and Sn, and Zn, In, or Sn is more preferable, and Zn is particularly preferable.

以鹼金屬而言,較佳為鈉、鉀、鋰中的至少一種。 In the case of an alkali metal, at least one of sodium, potassium and lithium is preferred.

本發明的光電變換元件的製造方法,其是在基板上積層有底電極層、光電變換層、緩衝層、透光性導電層之光電變換元件的製造方法,上述光電變換層以包含Ib族元素、IIIb族元素與 VIb族元素中至少一種的黃銅礦構造的化合物半導體作為主成分, 其特徵在於,藉由本發明的緩衝層的製造方法形成緩衝層。 A method for producing a photoelectric conversion element according to the present invention is a method for producing a photoelectric conversion element in which a bottom electrode layer, a photoelectric conversion layer, a buffer layer, and a light-transmitting conductive layer are laminated on a substrate, wherein the photoelectric conversion layer contains an Ib element , IIIb elements and a compound semiconductor of a chalcopyrite structure of at least one of the group VIb elements as a main component, It is characterized in that a buffer layer is formed by the method for producing a buffer layer of the present invention.

本發明的光電變換元件在以黃銅礦構造的化合物半導體作為主成分的光電變換層上設有緩衝層,由於緩衝層具備含有0.1at%以上、5at%以下比率的鈉、鉀及/或鋰的鹼金屬的化合物,因此特性的面內均勻性優良。具備含有鹼金屬在0.1at%以上、5at%以下的緩衝層的元件,在同一基板上同時形成光電變換元件之間的特性偏差會變小,而能得到具有均勻特性的光電變換元件。 In the photoelectric conversion element of the present invention, a buffer layer is provided on a photoelectric conversion layer containing a compound semiconductor having a chalcopyrite structure as a main component, and the buffer layer has sodium, potassium and/or lithium in a ratio of 0.1 at% or more and 5 at% or less. The alkali metal compound is therefore excellent in in-plane uniformity of properties. An element having a buffer layer containing an alkali metal in an amount of 0.1 at% or more and 5 at% or less has a small variation in characteristics between the photoelectric conversion elements formed on the same substrate, and a photoelectric conversion element having uniform characteristics can be obtained.

由於在緩衝層含有鹼金屬,而能使此緩衝層作為用於對光電變換層的鹼金屬供給層,能在不增加製程數的情況下,藉由在光電變換層添加鹼金屬而得到光電變換效率增加的效果。 Since the buffer layer contains an alkali metal and the buffer layer can be used as an alkali metal supply layer for the photoelectric conversion layer, photoelectric conversion can be obtained by adding an alkali metal to the photoelectric conversion layer without increasing the number of processes. The effect of increased efficiency.

本發明的太陽電池,由於能具備均勻性高的光電變換元件,因此而能抑制在光電變換元件間的均勻性低下的情況所造成的問題的因特性差的元件的影響所造成的光電變換效率低下,結果可獲得高光電變換效率。 In the solar cell of the present invention, since the photoelectric conversion element having high uniformity can be provided, it is possible to suppress the photoelectric conversion efficiency caused by the influence of the element having poor characteristics due to the problem that the uniformity between the photoelectric conversion elements is low. When it is low, a high photoelectric conversion efficiency can be obtained.

1‧‧‧光電變換元件 1‧‧‧ photoelectric conversion components

2‧‧‧太陽電池 2‧‧‧Solar battery

10‧‧‧基板 10‧‧‧Substrate

11‧‧‧Al基材 11‧‧‧Al substrate

12‧‧‧陽極氧化膜 12‧‧‧Anodized film

20‧‧‧底電極層 20‧‧‧ bottom electrode layer

30‧‧‧光電變換層 30‧‧‧ photoelectric conversion layer

40‧‧‧緩衝層 40‧‧‧buffer layer

60‧‧‧透光性導電層 60‧‧‧Translucent conductive layer

61‧‧‧劃線 61‧‧‧dick

62‧‧‧劃線 62‧‧‧dick

64‧‧‧劃線 64‧‧‧dick

70‧‧‧柵極 70‧‧‧ Grid

圖1顯示關於本發明的實施形態的光電變換元件的層構造的剖面示意圖。 Fig. 1 is a schematic cross-sectional view showing a layer structure of a photoelectric conversion element according to an embodiment of the present invention.

圖2顯示可以應用於本發明的光電變換元件的陽極氧化基板的例子的剖面示意圖。 Fig. 2 is a schematic cross-sectional view showing an example of an anodized substrate which can be applied to the photoelectric conversion element of the present invention.

圖3關於本發明的實施形態的積體化太陽電池的平面示意 圖。 Fig. 3 is a schematic plan view showing an integrated solar cell according to an embodiment of the present invention; Figure.

圖4為積體化太陽電池的一部分放大剖面圖。 4 is a partially enlarged cross-sectional view showing an integrated solar cell.

圖5顯示實施例3的試樣中深度方向的組成分析結果的圖。 Fig. 5 is a graph showing the results of composition analysis in the depth direction of the sample of Example 3.

以下,對本發明的實施形態做詳細的說明。 Hereinafter, embodiments of the present invention will be described in detail.

參照圖面,對關於本發明的一實施形態的光電變換元件的構造及製造方法加以說明。圖1為顯示光電變換元件1的概略構成的剖面圖。為了更易於辨視,對圖中各構成要素的比例等相對實際的物件做了適當的改變。 A structure and a manufacturing method of a photoelectric conversion element according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a schematic configuration of a photoelectric conversion element 1. In order to make it easier to recognize, the proportion of each component in the figure is appropriately changed from the actual object.

光電變換元件1為在基板10上順序積層有底電極層(背面電極,back electrode)20、光電變換層30、緩衝層40、作為上部電極層的透光性導電層(透明電極)60與柵極(grid electrode)70而成的元件。上述光電變換層30以包含Ib族元素、IIIb族元素與VIb族元素中至少一種的黃銅礦構造的化合物半導體作為主成分,其特徵在於:緩衝層40包括含有鹼金屬0.1at%以上、5at%以下的比例的化合物,該鹼金屬為鋰、鈉及鉀中的至少一種。 The photoelectric conversion element 1 has a bottom electrode layer (back electrode) 20, a photoelectric conversion layer 30, a buffer layer 40, and a light-transmitting conductive layer (transparent electrode) 60 and a gate as an upper electrode layer, which are sequentially laminated on the substrate 10. An element made up of a grid electrode 70. The photoelectric conversion layer 30 has a compound semiconductor containing a chalcopyrite structure of at least one of a group Ib element, a group IIIb element, and a group VIb element as a main component, and the buffer layer 40 includes an alkali metal content of 0.1 at% or more and 5 at A compound having a ratio of at least 100%, the alkali metal being at least one of lithium, sodium, and potassium.

並且,在緩衝層40與透光性導電層60之間也可以具有所謂的窗層(window layer)。 Further, a so-called window layer may be provided between the buffer layer 40 and the light-transmitting conductive layer 60.

緩衝層40是為了下述目的而設置的層:光生成載子的再結合的防止、能帶不連續的整合、晶格匹配(lattice matching)、光電變換層的表面凹凸的涵蓋率(coverage)、進一步地透光性導電層60成膜時的損害(damage)緩和等。 The buffer layer 40 is a layer provided for the purpose of preventing recombination of photo-generated carriers, integration of band discontinuities, lattice matching, and coverage of surface irregularities of the photoelectric conversion layer. Further, the damage of the light-transmitting conductive layer 60 at the time of film formation is moderated.

在本實施形態中,構成緩衝層40的化合物是含有金屬、硫及氧的化合物。金屬(也可以有無法避免的雜質)選自Cd、Zn、In及Sn所組成的群組中的至少一種。當金屬是Zn、In或Sn的時候,更有效果。特別是金屬為Zn的時候,即緩衝層40為Zn系化合物的時候,本發明的效果特別大。 In the present embodiment, the compound constituting the buffer layer 40 is a compound containing a metal, sulfur, and oxygen. The metal (which may also have unavoidable impurities) is at least one selected from the group consisting of Cd, Zn, In, and Sn. When the metal is Zn, In or Sn, it is more effective. In particular, when the metal is Zn, that is, when the buffer layer 40 is a Zn-based compound, the effect of the present invention is particularly large.

金屬是Zn的時候,構成緩衝層40的主成分為Zn(S,O)或是Zn(S,O,OH)。關於Zn(S,O)及Zn(S,O,OH)的說明,可被解釋為硫化鋅與氧化鋅的混晶及硫化鋅與氧化鋅與氫氧化鋅的混晶的意思,也可以為一部分硫化鋅或氧化鋅、氫氧化鋅以非晶等不形成混晶而存在。在此情況下,緩衝層40包含的鹼金屬可以被解釋為緩衝層40是在主成分Zn(S,O)及Zn(S,O,OH)中各自添加鹼金屬元素而形成的化合物所構成。並且,在金屬為Cd、In、Sn的情況下,就成為使上述化學式的Zn被Cd、In、Sn各自取代的化合物。 When the metal is Zn, the main component constituting the buffer layer 40 is Zn(S, O) or Zn(S, O, OH). The description of Zn(S,O) and Zn(S,O,OH) can be explained as the mixed crystal of zinc sulfide and zinc oxide and the mixed crystal of zinc sulfide and zinc oxide and zinc hydroxide. A part of zinc sulfide or zinc oxide or zinc hydroxide exists in the form of amorphous or the like without forming a mixed crystal. In this case, the alkali metal contained in the buffer layer 40 can be interpreted as a buffer layer 40 composed of a compound formed by adding an alkali metal element to each of the main components Zn(S, O) and Zn(S, O, OH). . Further, when the metal is Cd, In, or Sn, a compound in which Zn of the above chemical formula is substituted with each of Cd, In, and Sn is obtained.

並且,在構成緩衝層40的化合物中的鹼金屬的含量為0.1at%以上、5at%以下。本發明者們發現(參考後面實施例),若使其含有0.1at%以上,緩衝層的面內均勻性會提高,具備有此種緩衝層的光電變換元件在電池胞間的特性偏差會變得非常小。並且,在利用CBD法的緩衝層的成膜中,難以在緩衝層中添加超過5at%的鹼金屬。並且,在緩衝層中鹼金屬的含量較佳的是在0.5at%以上、2.5at%以下。 Further, the content of the alkali metal in the compound constituting the buffer layer 40 is 0.1 at% or more and 5 at% or less. The present inventors have found that (in the following embodiments), when it is contained in an amount of 0.1 at% or more, the in-plane uniformity of the buffer layer is improved, and the variation in characteristics of the photoelectric conversion element having such a buffer layer between cells is changed. Very small. Further, in the film formation of the buffer layer by the CBD method, it is difficult to add an alkali metal exceeding 5 at% to the buffer layer. Further, the content of the alkali metal in the buffer layer is preferably 0.5 at% or more and 2.5 at% or less.

並且,構成緩衝層的化合物中,也可以含有兩種以上的鹼金屬。在含有兩種以上的鹼金屬的情況,合計的含量為0.1at% 以上、5at%以下,而更好的是使含量在0.5at%以上、1.5at%以下。 Further, the compound constituting the buffer layer may contain two or more kinds of alkali metals. In the case of containing two or more alkali metals, the total content is 0.1 at% The above is 5 at% or less, and more preferably, the content is 0.5 at% or more and 1.5 at% or less.

緩衝層的組成,例如經由X射線光電子光譜法(X-ray photoelectron spectroscopy,XPS)量測而能加以確定,由此量測結果而能求得鹼金屬的含有量。 The composition of the buffer layer can be determined, for example, by X-ray photoelectron spectroscopy (XPS) measurement, and the content of the alkali metal can be determined by measuring the result.

藉由使緩衝層中含有鹼金屬,而使元件間的光電變換效率的偏差減少的效果的作用機制雖然目前尚未清楚,但認為是由於含有鹼金屬而使緩衝層的能帶結構產生變化,並產生了抑制在光電變換層發生的載子再結合之效果。 The mechanism of action for reducing the variation in photoelectric conversion efficiency between elements by containing an alkali metal in the buffer layer is not known at present, but it is considered that the energy band structure of the buffer layer is changed by the presence of an alkali metal, and An effect of suppressing recombination of carriers occurring in the photoelectric conversion layer is produced.

再者,藉由使緩衝層含有鹼金屬,而藉由用於包含CIGS層的光電變換層的鹼金屬供給,也能預期使光電變換層的特性提升。由於在CIGS層添加鹼金屬而使光電變換效率有所改善為以往習知。作為用於CIGS之鹼金屬的添加方式,已知有:使用含有鹼金屬的鈉鈣玻璃(soda-lime glass)等的玻璃基板或是設置有鹼金屬供給層的基板,藉由在CIGS成膜時來自基板的熱擴散而在CIGS中添加鹼金屬的技術(特開2011-233874號公報);或者在CIGS前驅物(precursor)成膜以後,在CIGS表面形成含有鹼金屬的化合物,並藉由熱處理而形成含有鹼金屬的CIGS的技術(國際公開第2005/109525號小冊)。就使用預先含有鹼金屬的鈉鈣玻璃等的玻璃基板以外的方法而言,產生必須增加用於CIGS層的鹼金屬供給的製程。在本發明,由於使含有鹼金屬的緩衝層加以成膜,緩衝層可以兼備有用於CIGS層的鹼金屬供給層的作用。亦即,緩衝層成膜之後,藉由以適當的溫度進行熱處理,而使鹼金屬朝CIGS 層擴散,而能使光電變換效率改善。 Further, by supplying the alkali metal to the buffer layer and supplying the alkali metal for the photoelectric conversion layer containing the CIGS layer, it is also expected to improve the characteristics of the photoelectric conversion layer. It has been conventionally known to improve the photoelectric conversion efficiency by adding an alkali metal to the CIGS layer. As a method of adding an alkali metal for CIGS, a glass substrate using an alkali metal-containing soda-lime glass or a substrate provided with an alkali metal supply layer is known, and a film is formed in CIGS. A technique of adding an alkali metal to CIGS at the time of thermal diffusion from a substrate (JP-A-2011-233874); or forming an alkali metal-containing compound on the surface of CIGS after film formation of a CIGS precursor A technique of forming an alkali metal-containing CIGS by heat treatment (International Publication No. 2005/109525). In the method other than the glass substrate using a soda-lime glass or the like containing an alkali metal in advance, a process of increasing the supply of the alkali metal for the CIGS layer is generated. In the present invention, since the buffer layer containing an alkali metal is formed into a film, the buffer layer can function as an alkali metal supply layer for the CIGS layer. That is, after the buffer layer is formed into a film, the alkali metal is directed to the CIGS by heat treatment at an appropriate temperature. Layer diffusion allows for improved photoelectric conversion efficiency.

緩衝層40的厚度為1nm以上、1μm以下,較佳的是在1nm以上、10nm以下,更進一步,在5nm以上,特別是10nm以上較佳。 The thickness of the buffer layer 40 is 1 nm or more and 1 μm or less, preferably 1 nm or more and 10 nm or less, and more preferably 5 nm or more, particularly preferably 10 nm or more.

再者,緩衝層40較佳的是具有結晶質部與非晶質部。緩衝層40中的硫原子與氧原子合計莫耳數對硫原子的莫耳數比較佳為0.2~0.8。該莫耳數比更佳為0.4~0.5。 Further, the buffer layer 40 preferably has a crystalline portion and an amorphous portion. The molar number of the sulfur atom and the oxygen atom in the buffer layer 40 is preferably 0.2 to 0.8 in terms of the molar number of the sulfur atom. The molar ratio is preferably from 0.4 to 0.5.

再者,緩衝層40的導電型並未特別加以限制,特別較佳的是n型。 Further, the conductivity type of the buffer layer 40 is not particularly limited, and an n-type is particularly preferable.

以下對緩衝層40的製造方法加以說明。另外,化合物中可以含有無法避免的雜質。 Hereinafter, a method of manufacturing the buffer layer 40 will be described. In addition, the compound may contain unavoidable impurities.

<成膜步驟> <film formation step>

緩衝層的成膜是利用CBD法。 The film formation of the buffer layer is by the CBD method.

所謂的「CBD」法,如以一般式「M(L)im+ Mn+iL表示(式中,M:金屬元素,L:配位子,m、n、i:各自代表一個正數。)表示,藉由平衡且達到過飽和條件,在安定的環境下以適當的速度,在基板上使結晶析出的方法。 The so-called "CBD" method, such as the general formula "M(L) i " m+ M n +iL means (wherein M: metal element, L: ligand, m, n, i: each represents a positive number.) means that by balancing and achieving supersaturation conditions, in a stable environment, appropriate Speed, a method of depositing crystals on a substrate.

化學浴沉積使用的反應液中,採用含有規定的金屬離子、硫脲、1M以上的鹼金屬離子者。以下,對用於化學浴沉積的反應液較佳的組成加以說明。在以下中,對於以設定的金屬為鋅的情況下來加以說明,鎘、銦、錫的情況也大致相同。 In the reaction liquid used for chemical bath deposition, a predetermined metal ion, thiourea, or an alkali metal ion of 1 M or more is used. Hereinafter, a preferred composition of the reaction liquid for chemical bath deposition will be described. In the following, the case where the set metal is zinc will be described, and the case of cadmium, indium, and tin is also substantially the same.

作為鋅的來源,較佳為選自於包含硫酸鋅、醋酸鋅、硝 酸鋅、檸檬酸鋅及這些的水合物所組成的群組中的至少一種。濃度並沒有特別加以限制,較佳為0.001~0.5M。 As a source of zinc, it is preferably selected from the group consisting of zinc sulfate, zinc acetate, and nitrate. At least one of the group consisting of zinc acid, zinc citrate, and hydrates of these. The concentration is not particularly limited, and is preferably 0.001 to 0.5 M.

硫脲的濃度並沒有特別加以限制,較佳為0.01~1.0M。 The concentration of thiourea is not particularly limited, and is preferably 0.01 to 1.0 M.

進一步,含有1M以上的鹼金屬離子。在此,作為鹼金屬的來源,較佳的是含有檸檬酸三鈉、檸檬酸三鉀、檸檬酸三鋰及/或其水合物。當使用檸檬酸三鈉的時候是鈉,當使用檸檬酸三鉀的時候是鉀,當使用檸檬酸三鋰的時候是鋰,而被納入緩衝層中。 Further, it contains 1 M or more of an alkali metal ion. Here, as a source of the alkali metal, it is preferred to contain trisodium citrate, tripotassium citrate, trilithium citrate, and/or a hydrate thereof. Sodium is used when trisodium citrate is used, potassium is used when tripotassium citrate is used, and lithium is used when trilithium citrate is used, and is incorporated into the buffer layer.

並且,此檸檬酸三鈉、檸檬酸三鉀、檸檬酸三鋰兼備有作為錯化劑等功能的成份,其是根據以往的化學浴沉積法,而添加於緩衝層形成時的反應液中。例如,專利文獻1中記載,反應液中的檸檬酸三鈉濃度較佳為0.001~0.25M。在本發明中,反應液中的鹼金屬離子濃度是設定為1M以上,因此檸檬酸三鈉的濃度是在0.34M以上。為了使緩衝層中具有充分地的鹼金屬,此種程度的濃度是必需的。就以往的檸檬酸三鈉的較佳的濃度範圍而言,鈉離子的濃度最大只到0.75M的程度,在取得鈉含量在0.1at%以上的緩衝層有難度。 Further, the trisodium citrate, tripotassium citrate, and trilithium citrate have a function as a correcting agent, and are added to the reaction liquid at the time of formation of the buffer layer by a conventional chemical bath deposition method. For example, Patent Document 1 discloses that the concentration of trisodium citrate in the reaction liquid is preferably 0.001 to 0.25 M. In the present invention, the concentration of the alkali metal ion in the reaction liquid is set to 1 M or more, and therefore the concentration of trisodium citrate is 0.34 M or more. In order to have a sufficient alkali metal in the buffer layer, such a concentration is necessary. In the preferred concentration range of the conventional trisodium citrate, the concentration of sodium ions is as large as 0.75 M, and it is difficult to obtain a buffer layer having a sodium content of 0.1 at% or more.

並且,在反應液中較佳為含有用作為pH值調整劑(pH control chemicals)等功能的NH4OH等銨鹽。銨鹽亦可以用作為錯化劑等功能的成分。銨鹽的濃度較佳的是在0.001~0.40M。藉由如此調整pH值,而能調整金屬離子的溶解度及過飽和度。銨鹽的濃度若在0.001~0.40M的範圍內,反應速度較快,即使在成膜步驟之前不提供微粒子層的形成步驟,也可能以實用的生產速度實施 成膜;銨鹽的濃度在超過0.40M時,反應速度就會變慢,在成膜步驟前就必需增加微粒層等的手段。銨鹽的濃度較佳的是在0.01~0.03M。 Further, the reaction liquid preferably contains an ammonium salt such as NH 4 OH which functions as a pH control chemical. The ammonium salt can also be used as a component of a function such as a correcting agent. The concentration of the ammonium salt is preferably from 0.001 to 0.40 M. By adjusting the pH in this way, the solubility and supersaturation of the metal ions can be adjusted. If the concentration of the ammonium salt is in the range of 0.001 to 0.40 M, the reaction rate is fast, and even if the step of forming the fine particle layer is not provided before the film forming step, film formation may be carried out at a practical production speed; the concentration of the ammonium salt exceeds At 0.40 M, the reaction rate becomes slow, and it is necessary to increase the particle layer or the like before the film formation step. The concentration of the ammonium salt is preferably from 0.01 to 0.03 M.

反應開始之前的反應液pH值是設為9.0~12.0。 The pH of the reaction solution before the start of the reaction was set to 9.0 to 12.0.

若反應液在反應開始前的pH值是小於9.0,則不會進行硫脲等的成分(S)的分解反應,即使有進行也是極為緩慢,因此不會進行析出反應。硫脲的分解反應如下述方式。關於硫脲的的分解反應,記載於電化學學會期刊141期、205-210頁(1994年)(Journal of the Electrochemical Society,141,205-210(1994))及晶體成長期刊299期,136-141頁(2007年)(Journal of Crystal Growth 299,136-141(2007))等。 When the pH of the reaction liquid before the start of the reaction is less than 9.0, the decomposition reaction of the component (S) such as thiourea is not performed, and even if it is carried out, it is extremely slow, so that the precipitation reaction does not proceed. The decomposition reaction of thiourea is as follows. The decomposition reaction of thiourea is described in Journal of Electrochemistry Society 141, 205-210 (1994) (Journal of the Electrochemical Society, 141, 205-210 (1994)) and Crystal Growth Journal 299, pp. 136-141. (2007) (Journal of Crystal Growth 299, 136-141 (2007)) and the like.

若反應液的反應開始前的pH值超過12,則作為錯化劑等功能的成分(N)對製造安定溶液的效果將會增加,不進行析出反應,或是即使有進行也是進行極為緩慢。反應液在反應開始前的pH值較佳的是在9.5~11.5。 When the pH before the start of the reaction of the reaction liquid exceeds 12, the effect of the component (N), which is a function such as a distorting agent, is increased, and the precipitation reaction is not carried out, or it is extremely slow even if it is carried out. The pH of the reaction solution before the start of the reaction is preferably from 9.5 to 11.5.

本發明使用的反應液,成分(N)的濃度是預定在0.001~0.40M,如果為這樣的濃度的話,即使未使用成分(N)以外的pH調整劑等將pH值調整到特別的值,通常反應開始前的反應液的pH值是設在9.0~12.0的範圍內。 In the reaction liquid to be used in the present invention, the concentration of the component (N) is set to be 0.001 to 0.40 M. If the concentration is such a concentration, the pH is adjusted to a specific value even without using a pH adjuster other than the component (N). Usually, the pH of the reaction liquid before the start of the reaction is set in the range of 9.0 to 12.0.

對反應液在反應完成後的pH值並未加以限制。反應液在 反應完成後的pH值較佳的是在7.5~11.0。反應液在反應完成後的pH值若小於7.5,則意味著包含有不進行反應的期間,若考慮到有效率的製造則是無意義的。並且,在即使將有緩衝作用的氨加入系統後pH值依然低下的情況下,氨在加熱步驟中揮發過多的可能性很高,則製造上的改善是有必要的。反應液在反應完成後的pH值超過11.0的話,雖會促進硫脲的分解,但由於大多數的鋅離子作為氨錯合物而變得安定,因此造成析出反應的進行顯著延緩的情況。反應液在反應完成後的pH值更為較佳的是在9.5~10.5。 The pH of the reaction solution after completion of the reaction is not limited. Reaction solution The pH after completion of the reaction is preferably from 7.5 to 11.0. When the pH of the reaction liquid after the completion of the reaction is less than 7.5, it means that the reaction period is not included, and it is meaningless in consideration of efficient production. Further, in the case where the pH is still lowered even after the buffering ammonia is added to the system, there is a high possibility that ammonia is excessively volatilized in the heating step, and improvement in manufacturing is necessary. When the pH of the reaction liquid exceeds 11.0, the decomposition of thiourea is promoted. However, since most of the zinc ions are stabilized as an ammonia complex, the progress of the precipitation reaction is remarkably delayed. The pH of the reaction liquid after completion of the reaction is more preferably 9.5 to 10.5.

在本發明的反應液中,即使在未使用成分(N)以外的pH值調整劑加以調整為特別的pH值,通常反應開始後的反應液的pH值設為7.5~11.0的範圍內。 In the reaction liquid of the present invention, even if the pH adjusting agent other than the component (N) is not adjusted to a specific pH value, the pH of the reaction liquid after the start of the reaction is usually in the range of 7.5 to 11.0.

反應溫度設為70℃~95℃。若反應溫度在小於70℃,反應速度就會變慢,薄膜不成長,或是薄膜雖有成長但是卻難以在實用的反應速度下得到預期的厚度。反應溫度超過95℃時,在反應液中氣泡等的產生變多,那些氣泡等將會附著在膜的表面,而難以成長平坦且均勻的膜。進一步地,於反應在開放系統下實施的情況,由於會發生溶劑蒸發等使濃度變化等狀況,安定的薄膜析出條件將變得難以維持。反應溫度較佳的是在80℃~90℃。 The reaction temperature is set to 70 ° C to 95 ° C. If the reaction temperature is less than 70 ° C, the reaction rate becomes slow, the film does not grow, or the film grows but it is difficult to obtain a desired thickness at a practical reaction rate. When the reaction temperature exceeds 95 ° C, the generation of bubbles or the like in the reaction liquid increases, and those bubbles or the like adhere to the surface of the film, and it is difficult to grow a flat and uniform film. Further, in the case where the reaction is carried out in an open system, stable concentration of film deposition conditions is difficult to maintain due to a change in concentration such as solvent evaporation. The reaction temperature is preferably from 80 ° C to 90 ° C.

反應時間並沒有特別加以限制。以本發明而言,即使不設置微粒子層,亦能以合乎實用的反應速度來實施反應。反應時間取決於反應溫度,例如10~90分之間,對底塗層(undercoat)有良好的被覆,而可以進行成膜得到具有足夠厚度能作為緩衝層的 層。 The reaction time is not particularly limited. In the case of the present invention, the reaction can be carried out at a practical reaction rate even without providing a fine particle layer. The reaction time depends on the reaction temperature, for example, between 10 and 90 minutes, and has a good coating on the undercoat, and can be formed into a film to have a sufficient thickness to serve as a buffer layer. Floor.

本發明所使用的反應液為水系溶液,反應液的pH值並非是強酸性條件。雖然反應液的pH值在11.0~12.0也可以,但小於11.0的溫和的pH值條件也可以實施反應,因此可以形成氫氧化物離子與錯離子的金屬等,在使用於包含易於在鹼性溶劑中溶解的金屬的基板,例如:可以應用於作為可撓性基板的陽極氧化基板等的情況下,也不用擔心對基板造成損害,而能夠成膜出均勻性高的緩衝層。上述陽極氧化基板包括:在以Al作為主成分的Al基材的至少一側的面上形成有以Al2O3作為主成分的陽極氧化膜的陽極氧化基板;在以Fe做為主成分的Fe材料的至少一側的面上複合有以Al為主成分的Al材料的複合基材的至少一側的面上形成有以Al2O3作為主成分的陽極氧化膜的陽極氧化基板;在以Fe作為主成分的Fe材料的至少一側的面上成膜有以Al作為主成分的Al膜的基材的至少一側的面上形成有以Al2O3作為主成分的陽極氧化膜的陽極氧化基板等。 The reaction liquid used in the present invention is an aqueous solution, and the pH of the reaction liquid is not a strongly acidic condition. Although the pH of the reaction solution may be from 11.0 to 12.0, the reaction may be carried out under mild pH conditions of less than 11.0, so that a hydroxide ion and a metal of a counter ion can be formed, and it is easy to use in an alkaline solvent. For example, when the substrate of the metal to be dissolved can be applied to an anodized substrate or the like as a flexible substrate, it is possible to form a buffer layer having high uniformity without causing damage to the substrate. The anodized substrate includes an anodized substrate on which an anodized film containing Al 2 O 3 as a main component is formed on at least one surface of an Al substrate containing Al as a main component; and Fe as a main component An anodized substrate in which an anodized film containing Al 2 O 3 as a main component is formed on at least one surface of a composite substrate of an Al material containing Al as a main component on at least one surface of the Fe material; An anodic oxide film containing Al 2 O 3 as a main component is formed on at least one surface of a substrate on which at least one surface of an Fe material containing Fe as a main component is formed on at least one surface of a Fe material containing Fe as a main component. Anodized substrate, etc.

另外,成膜步驟後,在基板的耐熱溫度以下的溫度,至少要對緩衝層進行退火處理。退火處理的溫度設為150℃以上是由於要得到使光電變換效率提高的效果。退火處理的方法並沒有特別加以限制,也可以是在加熱裝置中或是乾燥機中加熱,也可以是雷射退火或閃光燈退火(flash lamp annealing)等光退火(light annealing)。 Further, after the film formation step, at least the buffer layer is annealed at a temperature lower than the heat resistance temperature of the substrate. The temperature of the annealing treatment is set to 150 ° C or higher because an effect of improving the photoelectric conversion efficiency is obtained. The annealing treatment method is not particularly limited, and may be heating in a heating device or a dryer, or may be light annealing such as laser annealing or flash lamp annealing.

本發明的光電變換元件,關於緩衝層以外的結構並未特 別加以限制。以下,依序說明關於緩衝層以外的各構成要件的較佳例子。 The photoelectric conversion element of the present invention has no structure other than the buffer layer. Do not limit it. Hereinafter, preferred examples of the respective constituent elements other than the buffer layer will be described in order.

(基板) (substrate)

以基板10而言,並沒有特別加以限制,可以使用玻璃基板、表面上成膜有絕緣膜的不鏽鋼等的金屬基板、在以Al作為主成分的Al基材的至少其中一側的面上形成有以Al2O3作為主成分的陽極氧化膜的陽極氧化基板、在以Fe作為主成分的Fe材料的至少一側的面上複合有以Al為主成分的Al材料的複合基材的至少一側的面上形成有以Al2O3作為主成分的陽極氧化膜的陽極氧化基板、在以Fe作為主成分的Fe材料的至少一側的面上成膜有以Al作為主成分的Al膜的基材的至少一側的面上形成有以Al2O3作為主成分的陽極氧化膜的陽極氧化基板、及聚醯亞胺等的樹脂基板等。 The substrate 10 is not particularly limited, and a glass substrate, a metal substrate such as stainless steel on which an insulating film is formed on the surface, or a surface on at least one side of an Al substrate containing Al as a main component can be used. An anodized substrate having an anodized film containing Al 2 O 3 as a main component, and at least one surface of an Fe material containing Fe as a main component, at least a composite substrate of an Al material containing Al as a main component An anodized substrate having an anodized film containing Al 2 O 3 as a main component is formed on one surface thereof, and Al having Al as a main component is formed on at least one surface of a Fe material containing Fe as a main component. An anodized substrate of an anodized film containing Al 2 O 3 as a main component, a resin substrate such as polyimide, or the like is formed on at least one surface of the substrate of the film.

從能夠經由捲撓式製程(Roll to roll)步驟生產的觀點來看,較佳的是在表面成膜了絕緣膜的金屬基板、陽極氧化基板,及樹脂基板等的可撓性基板。 From the viewpoint of being able to be produced by a roll-to-roll process, a metal substrate, an anodized substrate, and a flexible substrate such as a resin substrate on which an insulating film is formed on the surface is preferable.

若將熱膨脹係數、耐熱性,及基板的絕緣性等列入考慮,陽極氧化基板特別較佳的是選自在Al作為主成分的Al基材的至少一側的面上形成有以Al2O3作為主成分的陽極氧化膜的陽極氧化基板、在以Fe作為主成分的Fe材料的至少一側的面上複合有以Al為主成分的Al材料的複合基材的至少一側的面上形成有以Al2O3作為主成分的陽極氧化膜的陽極氧化基板、及在以Fe作為 主成分的Fe材料的至少一側的面上成膜有以Al作為主成分的Al膜的基材的至少一側的面上形成有以Al2O3作為主成分的陽極氧化膜的陽極氧化基板所組成的群組。 In view of the thermal expansion coefficient, the heat resistance, and the insulating properties of the substrate, the anodized substrate is particularly preferably formed of Al 2 O 3 on a surface selected from at least one side of an Al substrate having Al as a main component. An anodized substrate of an anodized film as a main component is formed on at least one surface of a composite substrate in which an Al material containing Al as a main component is compounded on at least one surface of a Fe material containing Fe as a main component. An anodized substrate having an anodized film containing Al 2 O 3 as a main component and a substrate on an Al film containing Al as a main component are formed on at least one surface of a Fe material containing Fe as a main component. A group of anodized substrates of an anodized film containing Al 2 O 3 as a main component is formed on at least one surface.

圖2的左圖為在Al基材11的兩面側形成有陽極氧化膜12的基板,圖2的右圖為Al基材11的一面上形成有陽極氧化膜12的基板示意圖。陽極氧化膜12是以Al2O3作為主成分。 2 is a substrate on which the anodized film 12 is formed on both sides of the Al substrate 11, and the right side of FIG. 2 is a schematic view of a substrate on which an anodized film 12 is formed on one surface of the Al substrate 11. The anodized film 12 is made of Al 2 O 3 as a main component.

在元件的製造過程中,對於抑制起因於Al與Al2O3的熱膨脹係數差異造成的基板彎曲及由其造成的薄膜剝離(film peeling),如圖2的左圖所示,較佳的是在Al基材11的兩面上形成有陽極氧化膜12的基板。 In the manufacturing process of the element, it is preferable to suppress the bending of the substrate caused by the difference in thermal expansion coefficient between Al and Al 2 O 3 and the film peeling caused thereby, as shown in the left diagram of FIG. A substrate on which the anodized film 12 is formed on both surfaces of the Al substrate 11.

進一步說,在陽極氧化基板的陽極氧化膜上也可以設有鈉鈣玻璃(SLG,soda-lime glass)層。藉由具備有鈉鈣玻璃層,而能將Na擴散至光電變換層30,藉由使光電變換層30含有Na,而使光電變換效率能進一步的提升。 Further, a layer of soda-lime glass (SLG) may be provided on the anodized film of the anodized substrate. By providing the soda lime glass layer, Na can be diffused to the photoelectric conversion layer 30, and the photoelectric conversion layer 30 contains Na, whereby the photoelectric conversion efficiency can be further improved.

進一步而言,也可以是在基板上設有鈉鈣玻璃層。藉由具備有鈉鈣玻璃層,而能將Na擴散至光電變換層30,藉由使光電變換層30含有Na,而使光電變換效率能進一步的提升。 Further, a soda lime glass layer may be provided on the substrate. By providing the soda lime glass layer, Na can be diffused to the photoelectric conversion layer 30, and the photoelectric conversion layer 30 contains Na, whereby the photoelectric conversion efficiency can be further improved.

(底電極) (bottom electrode)

作為底電極(背面電極)20的主成分並未受到特別限制,較佳的是Mo、Cr、W及將這些加以組合,特佳為Mo。底電極(背面電極)20的膜厚並未受到限制,較佳的是在200~1000nm的程度。例如,底電極20也可以是藉由在基板上藉由濺鍍(spatter)法來成膜。 The main component of the bottom electrode (back surface electrode) 20 is not particularly limited, and Mo, Cr, W, and these are preferably combined, and particularly preferably Mo. The film thickness of the bottom electrode (back surface electrode) 20 is not limited, but is preferably about 200 to 1000 nm. For example, the bottom electrode 20 may be formed by sputtering on a substrate by a sputtering method.

(光電變換層) (photoelectric conversion layer)

作為光電變換層30的主成分並沒有特別受到限制,從得到高光電變換效率的觀點來看,較佳的是至少一種黃銅礦構造的化合物半導體,更為較佳的是包含Ib族元素與IIIb族元素與VIb族元素中的至少一種化合物半導體。 The main component of the photoelectric conversion layer 30 is not particularly limited, and from the viewpoint of obtaining high photoelectric conversion efficiency, at least one compound semiconductor of a chalcopyrite structure is preferable, and it is more preferable to contain an Ib element and At least one compound semiconductor of a group IIIb element and a group VIb element.

作為光電變換層30的主成分,較佳的是包含Ib族元素、IIIb族元素及、VIb族元素中的至少一種的化合物半導體。上述Ib族元素選自Cu及Ag所組成的群組中的至少一種。上述IIIb族元素選自Al、Ga及In所組成的群組中的至少一種。上述VIb族元素選自S、Se與Te所組成的群組中的至少一種。 As a main component of the photoelectric conversion layer 30, a compound semiconductor containing at least one of a group Ib element, a group IIIb element, and a group VIb element is preferable. The above Group Ib element is selected from at least one of the group consisting of Cu and Ag. The above Group IIIb element is at least one selected from the group consisting of Al, Ga, and In. The above Group VIb element is selected from at least one of the group consisting of S, Se and Te.

作為上述化合物半導體,例如CuAlS2、CuGaS2、CuInS2、CuAlSe2、CuGaSe2、AgAlS2、AgGaS2、AgInS2、AgAlSe2、AgGaSe2、AgInSe2、AgAlTe2、AgGaTe2、AgInTe2、Cu(In,Al)Se2、Cu(In,Ga)(S,Se)2、Cu1-zIn1-xGaxSe2-ySy(式中,0≦x≦1,0≦y≦2,0≦z≦1)(CI(G)S)、Ag(In,Ga)Se2及Ag(In,Ga)(S,Se)2等。 As the compound semiconductor, e.g. CuAlS 2, CuGaS 2, CuInS 2 , CuAlSe 2, CuGaSe 2, AgAlS 2, AgGaS 2, AgInS 2, AgAlSe 2, AgGaSe 2, AgInSe 2, AgAlTe 2, AgGaTe 2, AgInTe 2, Cu ( In, Al)Se 2 , Cu(In,Ga)(S,Se) 2 , Cu 1-z In 1-x Ga x Se 2-y S y (wherein 0≦x≦1,0≦y≦ 2,0≦z≦1)(CI(G)S), Ag(In,Ga)Se 2 and Ag(In,Ga)(S,Se) 2 and the like.

另外,也可以是Cu2ZnSnS4、Cu2ZnSnSe4、Cu2ZnSn(S,Se)4等。 Further, Cu 2 ZnSnS 4 , Cu 2 ZnSnSe 4 , Cu 2 ZnSn(S, Se) 4 or the like may be used.

光電變換層30的膜厚並沒有被特別限制,較佳的是1.0~4.0μm,特別較佳的是1.5~3.5μm。 The film thickness of the photoelectric conversion layer 30 is not particularly limited, but is preferably 1.0 to 4.0 μm, and particularly preferably 1.5 to 3.5 μm.

光電變換層30的成膜方法並沒有被特別限制,可以藉由真空蒸鍍法、濺鍍法、有機金屬化學氣相沈積(MOCVD)法等方法加以成膜。 The film formation method of the photoelectric conversion layer 30 is not particularly limited, and it can be formed by a method such as a vacuum deposition method, a sputtering method, or an organic metal chemical vapor deposition (MOCVD) method.

(窗層) (window layer)

如前所述,在緩衝層40與透光性導電層60之間也可以具備作為窗層的絕緣層。此絕緣層為取入光的中間層,防止受光激發的電子與電洞的再結合,而對提升發電效率有所貢獻。絕緣層的組成也並未有特別限制,但較佳為i-ZnO等。此處的膜厚並未特別加以限制,較佳為10nm~2μm,更佳的是15~200nm。成膜方法未加以限制,但較適用的是濺鍍法及MOCVD法。另一方面,緩衝層40在藉由液相法進行製造的情況下,由於製造程序較簡易,因此應用液相法較佳。 As described above, an insulating layer as a window layer may be provided between the buffer layer 40 and the light-transmitting conductive layer 60. The insulating layer is an intermediate layer for taking in light, and prevents recombination of electrons excited by light and holes, and contributes to improving power generation efficiency. The composition of the insulating layer is also not particularly limited, but is preferably i-ZnO or the like. The film thickness here is not particularly limited, and is preferably 10 nm to 2 μm, more preferably 15 to 200 nm. The film formation method is not limited, but sputtering and MOCVD are more suitable. On the other hand, in the case where the buffer layer 40 is produced by the liquid phase method, since the manufacturing process is simple, it is preferable to apply the liquid phase method.

(透光性導電層) (translucent conductive layer)

透光性導電層(透明電極)60為在取入光的同時,對應於底電極20,供光電變換層30生成的電流流入而作為上電極功能的層。作為透光性導電層60的組成並未特別被限制,較佳的是ZnO:Al等的n-ZnO等。透光性導電層60的膜厚並未特別被限制,較佳為50nm~2μm。透光性導電層60的成膜方法雖未特別被限制,與窗層相同,適合的是MOCVD法、反應性電漿蒸鍍法、離子鍍著法。另一方面,由於製造程序較簡易,因此應用液相法較佳。 The translucent conductive layer (transparent electrode) 60 is a layer that functions as an upper electrode in response to the bottom electrode 20 while the light is taken in, and the current generated by the photoelectric conversion layer 30 flows in. The composition of the light-transmitting conductive layer 60 is not particularly limited, and n-ZnO such as ZnO:Al or the like is preferable. The film thickness of the light-transmitting conductive layer 60 is not particularly limited, but is preferably 50 nm to 2 μm. The film forming method of the light-transmitting conductive layer 60 is not particularly limited, and is similar to the window layer, and is preferably an MOCVD method, a reactive plasma vapor deposition method, or an ion plating method. On the other hand, since the manufacturing process is relatively simple, it is preferable to apply the liquid phase method.

(柵極) (gate)

柵極70是為了將電力由元件取出而運用的電極,其主成分並未特別受到限制,舉例為Al等。柵極70的膜厚也並未特別被限制,較佳的是0.1~3μm。 The gate electrode 70 is an electrode that is used to extract electric power from the element, and its main component is not particularly limited, and is exemplified by Al or the like. The film thickness of the gate electrode 70 is also not particularly limited, and is preferably 0.1 to 3 μm.

本實施形態的光電變換元件1是如上述的構成。 The photoelectric conversion element 1 of the present embodiment has the above configuration.

光電變換元件1的製造方法,只要利用上述緩衝層的製造方法來形成緩衝層的話,關於其它層的形成方法則無特別限制,可以適用在上述各層之說明處所做的說明中的各種成膜方法。 In the method of producing the photoelectric conversion element 1, the method of forming the buffer layer is not particularly limited as long as the buffer layer is formed by the method for producing the buffer layer, and various film formation methods in the description of the respective layers can be applied. .

光電變換元件1能夠有利地使用於太陽電池等。將光電變換元件1積體化並且對應需要而裝配蓋板玻璃(cover glass)、保護膜等而製成太陽電池。 The photoelectric conversion element 1 can be advantageously used for a solar cell or the like. The photoelectric conversion element 1 is integrated and a cover glass, a protective film, or the like is attached as needed to prepare a solar cell.

圖3顯示光電變換元件1經過多數積體化形成的太陽電池2的平面圖,圖4為圖3的一部分的放大剖面圖。 3 is a plan view showing a solar cell 2 in which the photoelectric conversion element 1 is formed by a majority of integration, and FIG. 4 is an enlarged cross-sectional view showing a portion of FIG.

如圖3及圖4所示,太陽電池2是將在一片基板10上積層有底電極20、光電變換層30、緩衝層40及透光性導電層60而形成的光電變換元件(電池胞)1以多數個串聯連接而成。 As shown in FIG. 3 and FIG. 4, the solar cell 2 is a photoelectric conversion element (battery cell) formed by laminating a bottom electrode 20, a photoelectric conversion layer 30, a buffer layer 40, and a light-transmitting conductive layer 60 on a single substrate 10. 1 is made up of a plurality of series connected.

在基板10上成膜了底電極20後,對此電極層進行劃線而形成第一劃線61(scribe line),在其上依序成膜光電變換層30、緩衝層40,並形成將這些予以貫通至電極層表面的劃線62(scribe line),並積層透光性導電層(上電極)60,藉由形成從透光性導電層60至底電極20的表面的劃線64(scribe line),而能得到將多數電池胞1加以積體化的太陽電池2。鄰接的電池胞1間是經由劃線64而分離,鄰接的電池胞1間是經由埋入劃線62的透光性導電層材料而串聯連接。 After the bottom electrode 20 is formed on the substrate 10, the electrode layer is scribed to form a first scribe line 61, and the photoelectric conversion layer 30 and the buffer layer 40 are sequentially formed thereon, and formed. These are passed through a scribe line 62 on the surface of the electrode layer, and a light-transmitting conductive layer (upper electrode) 60 is laminated, by forming a scribe line 64 from the surface of the light-transmitting conductive layer 60 to the bottom electrode 20 ( The scribe line) can obtain the solar cell 2 in which a plurality of battery cells 1 are integrated. The adjacent battery cells 1 are separated by a scribe line 64, and the adjacent battery cells 1 are connected in series via a light-transmitting conductive layer material embedded in the scribe line 62.

藉此,串聯連接了多個光電變換元件1的太陽電池,由於受到多個光電變換元件中的較低效率的電池胞特性影響,在過去,由電池胞的平均光電變換效率僅可以預期,但並不見得能得 到此效率。但是,本發明的光電變換元件,由於將各元件間的效率的變動抑制在小,而能實現從單電池胞得到的效率來預期積體化太陽電池的效率,並能得到比過去更加安定的高光電變換效率的太陽電池。 Thereby, the solar cells in which the plurality of photoelectric conversion elements 1 are connected in series are affected by the lower efficiency of the cell characteristics of the plurality of photoelectric conversion elements, and in the past, the average photoelectric conversion efficiency by the battery cells was only expected, but Not necessarily able to get To this efficiency. However, in the photoelectric conversion element of the present invention, since the fluctuation in efficiency between the elements is suppressed to be small, the efficiency obtained from the single cell can be realized, and the efficiency of the integrated solar cell can be expected, and it can be more stable than in the past. High photoelectric conversion efficiency of solar cells.

「設計變更」 "Design changes"

本發明並未受限於上述之實施形態,在未脫離本發明之意旨的範圍內,可以作適當的變更設計。 The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit and scope of the invention.

有關於本發明的實施例及比較例之說明。 Description of the embodiments and comparative examples of the present invention.

<基板~光電變換層> <Substrate ~ Photoelectric Conversion Layer>

對基板來說,是準備下述的基板1、基板2。 For the substrate, the substrate 1 and the substrate 2 described below are prepared.

基板1:鈉鈣玻璃基板 Substrate 1: Soda-lime glass substrate

基板2:100μm厚的不鏽鋼(SUS)-使30μm厚的Al複合基材進行陽極氧化而使Al的表面上形成有陽極氧化鋁膜(anodic aluminium oxide,AAO)的陽極氧化基板的AAO表面上設置有鈉鈣玻璃(SLG)層的基板。基板2的各層厚度是SUS(100μm),Al(20μm),AAO(10μm),SLG(0.2μm)。 Substrate 2: 100 μm thick stainless steel (SUS) - Anodized 30 μm thick Al composite substrate was placed on the AAO surface of an anodized substrate on which an anodic aluminum oxide (AAO) was formed on the surface of Al. A substrate having a soda lime glass (SLG) layer. The thickness of each layer of the substrate 2 was SUS (100 μm), Al (20 μm), AAO (10 μm), and SLG (0.2 μm).

在上述基板1或是基板2上,經由濺鍍法而成膜0.8μm厚的Mo底電極,在Mo的底電極上,利用三階段的方式而成膜作為光電變換層之膜厚1.8μm的Cu(In0.7Ga0.3)Se2層。另外,將此稱為緩衝成膜用基板。 On the substrate 1 or the substrate 2, a 0.8 μm thick Mo bottom electrode was formed by sputtering, and a film thickness of 1.8 μm as a photoelectric conversion layer was formed on the bottom electrode of Mo by a three-stage method. Cu(In 0.7 Ga 0.3 )Se 2 layer. In addition, this is called a buffer film formation substrate.

<表面處理> <surface treatment>

準備置入了10%的KCN水溶液的反應槽,在緩衝成膜用基板 的最表面的CIGS層的表面在室溫下將其浸漬3分鐘,將CIGS層表面的雜質去除。取出後以充分的水洗清。 Prepare a reaction tank in which a 10% KCN aqueous solution is placed, and buffer the substrate for film formation The surface of the outermost CIGS layer was immersed for 3 minutes at room temperature to remove impurities from the surface of the CIGS layer. After taking out, wash with plenty of water.

使用基板1或是基板2進行了Mo電極、CIGS層的形成和表面處理後,在下述的實施例1~10及比較例1~3的條件下,在CIGS層的表面成膜緩衝層40。 After the formation of the Mo electrode and the CIGS layer and the surface treatment using the substrate 1 or the substrate 2, the buffer layer 40 was formed on the surface of the CIGS layer under the conditions of the following Examples 1 to 10 and Comparative Examples 1 to 3.

(實施例1) (Example 1)

使用的是基板1。 The substrate 1 is used.

分別調製作為水溶液(I)的硫酸鋅水溶液(0.18[M])、作為水溶液(II)的硫脲溶液(硫脲0.30[M])、作為水溶液(III)的檸檬酸三鈉水溶液(2.4[M])及作為水溶液(IV)的氨水(0.3[M])。接下來,將這些水溶液中的I、II、III各以同體積加以混合,而完成由硫酸鋅0.06[M]、硫脲0.10[M]、檸檬酸三鈉0.8[M]構成的混合溶液,將此混合溶液與0.3[M]的氨水各以同體積加以混合而得到反應液1。當混合水溶液(I)~(IV)的時候,必須使水溶液(IV)在最後添加。對於成為透明的反應液而言,將水溶液(IV)在最後添加是相當重要的。反應液1為硫酸鋅0.03[M]、硫脲0.05[M]、檸檬酸三鈉0.4[M]、氨0.15[M]。此反應液1中的鹼金屬為鈉,該濃度為1.2M。得到的反應液1的pH值為10.4。 A zinc sulfate aqueous solution (0.18 [M]) as an aqueous solution (I), a thiourea solution (thiourea 0.30 [M]) as an aqueous solution (II), and an aqueous solution of trisodium citrate as an aqueous solution (III) were separately prepared (2.4 [ M]) and ammonia water (0.3 [M]) as an aqueous solution (IV). Next, I, II, and III in each of the aqueous solutions are mixed in the same volume, and a mixed solution composed of zinc sulfate 0.06 [M], thiourea 0.10 [M], and trisodium citrate 0.8 [M] is completed. This mixed solution was mixed with 0.3 [M] of aqueous ammonia in the same volume to obtain a reaction liquid 1. When the aqueous solutions (I) to (IV) are mixed, the aqueous solution (IV) must be added at the end. For the reaction liquid to be transparent, it is quite important to add the aqueous solution (IV) at the end. The reaction solution 1 was zinc sulfate 0.03 [M], thiourea 0.05 [M], trisodium citrate 0.4 [M], and ammonia 0.15 [M]. The alkali metal in the reaction liquid 1 was sodium, and the concentration was 1.2M. The obtained reaction solution 1 had a pH of 10.4.

接下來,在緩衝層成膜用基板的最表面的光電變換層(CIGS)的表面,使用反應液1藉由CBD法,成膜以Zn(S,O)及/或Zn(S,O,OH)作為主成分的緩衝層。具體來說,在調溫至90℃的反應液500ml中,將緩衝成膜用基板浸漬120分鐘之後再將基板 取出,再以純水將表面充分的洗淨後,將此基板放在室溫下乾燥。在將基板浸漬於反應液中的步驟中,對於反應液的容器的底面而將基板面呈垂直的方式來設置基板。 Next, on the surface of the photoelectric conversion layer (CIGS) on the outermost surface of the buffer layer film-forming substrate, Zn(S, O) and/or Zn (S, O, Zn(S, O) and/or Zn (S, O) are formed by the CBD method using the reaction solution 1. OH) A buffer layer as a main component. Specifically, the substrate for buffer film formation was immersed for 120 minutes in 500 ml of a reaction liquid adjusted to a temperature of 90 ° C, and then the substrate was placed. After taking out, the surface was sufficiently washed with pure water, and the substrate was dried at room temperature. In the step of immersing the substrate in the reaction liquid, the substrate is provided so that the substrate surface is vertical with respect to the bottom surface of the container of the reaction liquid.

在上述緩衝層成膜後,在200℃下進行一小時的退火處理,藉此而形成緩衝層。 After the buffer layer was formed into a film, annealing treatment was performed at 200 ° C for one hour to form a buffer layer.

(實施例2) (Example 2)

除了以基板2取代基板1使用之外,與實施例1同樣地形成緩衝層。 A buffer layer was formed in the same manner as in Example 1 except that the substrate 2 was used instead of the substrate 1.

(實施例3) (Example 3)

在反應液中除了緩衝成膜用基板的浸漬時間(反應時間)設為60分鐘此點外,與實施例1同樣地形成緩衝層。 A buffer layer was formed in the same manner as in Example 1 except that the immersion time (reaction time) of the buffer film formation substrate was 60 minutes.

(實施例4) (Example 4)

除了以基板2取代基板1使用之外,與實施例3同樣地形成緩衝層。 A buffer layer was formed in the same manner as in Example 3 except that the substrate 2 was used instead of the substrate 1.

(實施例5) (Example 5)

在反應液中除了緩衝成膜用基板的浸漬時間(反應時間)設為90分鐘此點外,與實施例1同樣地形成緩衝層。 A buffer layer was formed in the same manner as in Example 1 except that the immersion time (reaction time) of the buffer film formation substrate was 90 minutes.

(實施例6) (Example 6)

除了以基板2取代基板1使用之外,是與實施例5同樣地形成緩衝層。 A buffer layer was formed in the same manner as in Example 5 except that the substrate 2 was used instead of the substrate 1.

(實施例7) (Example 7)

以硫酸鋅0.03[M]、硫脲0.05[M]、檸檬酸三鉀0.4[M]、氨 0.15[M]調製反應液2。 Zinc sulfate 0.03 [M], thiourea 0.05 [M], tripotassium citrate 0.4 [M], ammonia The reaction liquid 2 was prepared at 0.15 [M].

除了使用此反應液2之外,與實施例1同樣地形成緩衝層。 A buffer layer was formed in the same manner as in Example 1 except that this reaction liquid 2 was used.

(實施例8) (Example 8)

除了以基板2取代基板1使用之外,與實施例7同樣地形成緩衝層。 A buffer layer was formed in the same manner as in Example 7 except that the substrate 2 was used instead of the substrate 1.

(實施例9) (Example 9)

以硫酸鋅0.03[M]、硫脲0.05[M]、檸檬酸三鋰0.4[M]、氨0.15[M]調製反應液3。除了使用此反應液3之外,與實施例1同樣地形成緩衝層。 The reaction liquid 3 was prepared with zinc sulfate 0.03 [M], thiourea 0.05 [M], trilithium citrate 0.4 [M], and ammonia 0.15 [M]. A buffer layer was formed in the same manner as in Example 1 except that this reaction liquid 3 was used.

(實施例10) (Embodiment 10)

除了以基板2取代基板1使用之外,與實施例9同樣地形成緩衝層。 A buffer layer was formed in the same manner as in Example 9 except that the substrate 2 was used instead of the substrate 1.

(比較例1) (Comparative Example 1)

以硫酸鋅0.16[M]、硫脲0.6[M]、氨7.5[M]調製反應液4。即,比較例1的反應液4中不含有鹼金屬離子。 The reaction liquid 4 was prepared with zinc sulfate 0.16 [M], thiourea 0.6 [M], and ammonia 7.5 [M]. That is, the reaction liquid 4 of Comparative Example 1 did not contain an alkali metal ion.

使用反應液4,在反應液溫度為80℃,在反應液中除了緩衝成膜用基板的浸漬時間(反應時間)設為40分鐘此點外,與實施例1同樣地形成緩衝層。 In the reaction liquid 4, a buffer layer was formed in the same manner as in Example 1 except that the temperature of the reaction liquid was 80 ° C, and the immersion time (reaction time) of the substrate for buffer film formation was 40 minutes.

(比較例2) (Comparative Example 2)

以硫酸鋅0.025[M]、硫脲0.4[M]、氨2.5[M]調製反應液5。以反應液1~4而言,Zn的來源是不同的,並且,在反應液5中並未含有鹼金屬離子。 The reaction liquid 5 was prepared with zinc sulfate 0.025 [M], thiourea 0.4 [M], and ammonia 2.5 [M]. In the case of the reaction liquids 1 to 4, the sources of Zn are different, and the alkali metal ions are not contained in the reaction liquid 5.

使用反應液5,在反應液溫度為80℃,在反應液中除了緩衝成膜用基板的浸漬時間(反應時間)設為180分鐘此點外,與實施例1同樣地形成緩衝層。 The reaction liquid 5 was used, and a buffer layer was formed in the same manner as in Example 1 except that the temperature of the reaction liquid was 80 ° C, and the immersion time (reaction time) of the substrate for buffer film formation was 180 minutes.

(比較例3) (Comparative Example 3)

以硫酸鋅0.03[M]、硫脲0.05[M]、檸檬酸三鈉0.03[M]、氨0.15[M]調製反應液6。反應液6中的鹼金屬離子濃度為0.09[M]。 The reaction liquid 6 was prepared with zinc sulfate 0.03 [M], thiourea 0.05 [M], trisodium citrate 0.03 [M], and ammonia 0.15 [M]. The alkali metal ion concentration in the reaction liquid 6 was 0.09 [M].

除了使用此反應液6之外,與實施例3同樣地形成緩衝層。 A buffer layer was formed in the same manner as in Example 3 except that this reaction liquid 6 was used.

在表1將各實施例及比較例的緩衝層成膜條件總結表示。 The buffer layer film formation conditions of the respective examples and comparative examples are summarized in Table 1.

<緩衝層的組成的評價> <Evaluation of the composition of the buffer layer>

在預先切割為的1cm見方的CIGS基板(基板上形成有CIGS層者)上,以與實施例1~實施例10及比較例1~3同樣的條件,直到緩衝層成膜為止,對得到的樣品實施組成分析。在量測中,經由X射線光電子光譜法對緩衝層的成膜實施在深度方向上的組成分析。作為一個例子,實施例3的結果顯示於圖5中。圖5中從緩衝層表面蝕刻的深度方向表示於橫軸,各元素的濃度表示於縱軸。另外,圖5中顯示的濃度為相對於構成樣品的元素O、C、Na、S、Zn、Cu、Ga、In、Se的合計含有量之各別的元素濃度。雖然量測是對這些所有的元素實施,但在圖5中僅顯示了O、C、S、Zn及Cu。 The obtained 1 cm square CIGS substrate (the CIGS layer was formed on the substrate) was obtained under the same conditions as in Examples 1 to 10 and Comparative Examples 1 to 3 until the buffer layer was formed. Samples were analyzed for composition. In the measurement, composition analysis of the buffer layer was performed in the depth direction by X-ray photoelectron spectroscopy. As an example, the results of Example 3 are shown in FIG. The depth direction etched from the surface of the buffer layer in Fig. 5 is shown on the horizontal axis, and the concentration of each element is shown on the vertical axis. In addition, the concentration shown in FIG. 5 is the respective element concentration with respect to the total content of the elements O, C, Na, S, Zn, Cu, Ga, In, and Se which constitute a sample. Although the measurement is performed on all of these elements, only O, C, S, Zn, and Cu are shown in FIG.

另外,伴隨著蝕刻的XPS量測是以下述條件實施。在圖5中橫軸表示由濺鍍時間(分)求出的蝕刻深度[nm]。由濺鍍時間換算的蝕刻深度是利用作為標準樣品的已知膜厚的SiO2膜(基板為Si晶圓)所計算出的蝕刻率作為基準而計算得到。緩衝層的厚度的換算是相對緩衝層中的S成分的最大濃度,以濃度減半的位置作為基準而計算得到。 Further, the XPS measurement accompanying the etching was carried out under the following conditions. In Fig. 5, the horizontal axis represents the etching depth [nm] obtained from the sputtering time (minutes). The etching depth converted from the sputtering time is calculated by using the etching rate calculated from the SiO 2 film (substrate is a Si wafer) of a known film thickness as a standard sample. The conversion of the thickness of the buffer layer is calculated as the maximum concentration of the S component in the buffer layer, based on the position at which the concentration is halved.

XPS分析 XPS analysis

裝置:X射線光電子能譜置PHI公司製Quantera SXM Device: X-ray photoelectron spectroscopy set with Quantera SXM manufactured by PHI

X射線源:單結晶分光AlK α線 X-ray source: single crystal spectroscopic AlK α line

輸出/分析範圍:25W/φ 100μm Output / analysis range: 25W / φ 100μm

通能(Pass Energy):深度方向分析Narrow Scan-280.0ev(0.25eV/Step) Pass Energy: Analysis of depth direction Narrow Scan-280.0ev (0.25eV/Step)

幾何(Geometry):θ=45°(樣品表面與偵檢器間的角度) Geometry: θ=45° (angle between the sample surface and the detector)

Ar+蝕刻條件 Ar + etching conditions

加速電壓:1kV、光柵尺寸(raster size):2*2mm、速率(rate):約2.6nm/min(SiO2的情況) Acceleration voltage: 1kV, raster size: 2*2mm, rate: about 2.6nm/min (in the case of SiO 2 )

如圖5所示,藉由以XPS測定緩衝層的厚度,及求出緩衝層中的各成分分布。該結果確認緩衝層中S與O兩者的存在。另外,相對於S的最大濃度,以在濃度減半的位置作為基準而計算求得緩衝層的厚度。關於各實施例及比較例的厚度分別顯示於表2中。從XPS光譜峰值所在的位置,而能鑑定鹼金屬的種類。另外,由於藉由上述方式求得了緩衝層的厚度,因此從鹼金屬的蝕刻深度方向的濃度分布,而能計算求得緩衝層中的鹼金屬的平均濃度。 As shown in Fig. 5, the thickness of the buffer layer was measured by XPS, and the distribution of each component in the buffer layer was determined. This result confirms the presence of both S and O in the buffer layer. Further, with respect to the maximum concentration of S, the thickness of the buffer layer was calculated by calculating the position at which the concentration was halved. The thicknesses of the respective examples and comparative examples are shown in Table 2, respectively. The type of alkali metal can be identified from the position where the peak of the XPS spectrum is located. Further, since the thickness of the buffer layer is obtained by the above-described method, the average concentration of the alkali metal in the buffer layer can be calculated from the concentration distribution in the etching depth direction of the alkali metal.

在S未被檢出的位置亦能確認有Zn的存在。這應是由於在CBD步驟中CIGS層中Zn2+的擴散造成。 The presence of Zn was also confirmed at the position where S was not detected. This should be due to the diffusion of Zn 2+ in the CIGS layer during the CBD step.

並且,在表2中是將緩衝層中的S成分的比例以S/(S+O)值表示。S/(S+O)值在實施例1~實施例8中為0.51~0.55而幾乎沒有差異,在比較例1~3中則存在有0.42~0.6的偏差。然而,即使在實施例1~8及比較例1~3的任一個條件下製造,可以說緩衝層的組成是含有S,O或是S,O,OH。 Further, in Table 2, the ratio of the S component in the buffer layer is represented by an S/(S+O) value. The S/(S+O) value was 0.51 to 0.55 in Examples 1 to 8, and there was almost no difference, and in Comparative Examples 1 to 3, there was a deviation of 0.42 to 0.6. However, even if it was produced under any of the conditions of Examples 1 to 8 and Comparative Examples 1 to 3, it can be said that the composition of the buffer layer contained S, O or S, O, OH.

<光電變換元件的製作-續> <Production of Photoelectric Conversion Element - Continued>

在實施例1~10及比較例1~3製作的緩衝層上,藉由濺鍍方法 成膜包含膜厚300nm的摻雜Al導電性氧化鋅薄膜的透光性導電膜。其後,藉由以蒸鍍法形成作為柵極的Al電極,而製作光電變換元件(單電池胞的太陽電池)。 On the buffer layers prepared in Examples 1 to 10 and Comparative Examples 1 to 3, by sputtering method A light-transmitting conductive film containing an Al-conductive zinc oxide film having a film thickness of 300 nm was formed. Thereafter, an Al electrode as a gate electrode was formed by a vapor deposition method to fabricate a photoelectric conversion element (a solar cell of a single cell).

另外,對於各實施例及比較例而製作八個電池胞。在各個例子中的八個電池胞是在一片基板上的各層形成之後,以規定的尺寸切出而製作,在同時的同一個步驟中得到。 Further, eight battery cells were produced for each of the examples and comparative examples. The eight battery cells in each of the examples were formed by cutting out a plurality of layers on one substrate, and cutting them at a predetermined size, which were obtained in the same step at the same time.

<光電變換效率的評價> <Evaluation of photoelectric conversion efficiency>

關於所獲得的實施例及比較例的光電變換元件(八個電池胞),利用太陽模擬器(solar simulator),在氣團(Air Mass,AM)=1.5、100mW/cm2的擬似太陽光的使用條件下,量測光電變換效率。另外,光電變換效率的量測是在實施光照射之後的30分後進行。 With respect to the obtained photoelectric conversion elements (eight battery cells) of the examples and the comparative examples, the use of pseudo-sunlight at air mass (AM) = 1.5, 100 mW/cm 2 using a solar simulator was used. Under the conditions, the photoelectric conversion efficiency is measured. In addition, the measurement of the photoelectric conversion efficiency was performed after 30 minutes after the light irradiation was performed.

獲得的結果如表2所示。在表2中展示關於各實施例及比較例的八個電池胞的光電變換效率的最大值、平均值或最小值,且進一步展示由這些得到的變異係數。變異係數為將八個電池胞的光電變換效率的標準差除以八個電池胞的光電變換效率的平均值的比值(在此是以百分率表示)。 The results obtained are shown in Table 2. The maximum value, the average value, or the minimum value of the photoelectric conversion efficiencies of the eight battery cells of the respective examples and comparative examples are shown in Table 2, and the coefficient of variation obtained from these is further shown. The coefficient of variation is a ratio of the standard deviation of the photoelectric conversion efficiency of eight battery cells divided by the average value of the photoelectric conversion efficiencies of eight battery cells (herein expressed as a percentage).

如表2所示,關於本發明的實施例的變異係數是在12%以下,除了實施例5以外,則皆能抑制在10%以下。考慮到比較例皆是變異係數在20%以上,很明顯本發明的實施例可以得到抑制高變異係數的效果。使用不含有鹼金屬的金屬源的反應液而成膜緩衝層的比較例1及比較例2,在緩衝層中並沒有檢測到鹼金屬,這些變異係數會變得非常大。如在實施例1~實施例8中,鹼金屬在緩衝層含有0.7at%以上之時,與含有量為0.05at%的比較例3相比,變異係數顯著變小。作為鹼金屬來說,鈉、鉀、鋰添加任一種都同樣能得到均勻性高的效果。 As shown in Table 2, the coefficient of variation of the examples of the present invention was 12% or less, and it was suppressed to 10% or less except for Example 5. Considering that the comparative examples are all having a coefficient of variation of 20% or more, it is apparent that the embodiment of the present invention can obtain an effect of suppressing a high coefficient of variation. In Comparative Example 1 and Comparative Example 2 in which a buffer layer was formed using a reaction liquid containing no metal source of an alkali metal, no alkali metal was detected in the buffer layer, and these coefficient of variation were extremely large. In the examples 1 to 8, when the alkali metal contained 0.7 at% or more in the buffer layer, the coefficient of variation was remarkably small as compared with the comparative example 3 in which the content was 0.05 at%. As an alkali metal, the addition of any of sodium, potassium, and lithium can also achieve a high uniformity effect.

在上述中,雖僅顯示緩衝層包含Zn系化合物的情況的實施例,但緩衝層包含有Cd系化合物、In系化合物或是Sn系化合物,由於認為是同樣也能藉由使緩衝層中含有鹼金屬而使能帶結構產生變化,且產生了抑制在光電變換層發生的載子再結合的效果,而認為能得到提升光電變換特性之均勻性的效果。 In the above, although the embodiment in which the buffer layer contains the Zn-based compound is shown, the buffer layer contains the Cd-based compound, the In-based compound, or the Sn-based compound, and it is considered that the buffer layer can be contained in the buffer layer. The alkali metal causes a change in the band structure, and an effect of suppressing recombination of carriers generated in the photoelectric conversion layer is produced, and it is considered that an effect of improving the uniformity of the photoelectric conversion characteristics can be obtained.

Claims (9)

一種光電變換元件,其是在基板上積層有底電極層、光電變換層、緩衝層與透光性導電層的光電變換元件,上述光電變換層以包含Ib族元素、IIIb族元素與VIb族元素中至少一種的黃銅礦構造的化合物半導體作為主成分,其特徵在於:上述緩衝層包括含有鹼金屬的化合物;上述鹼金屬為鋰、鈉及鉀中的至少一種;以及上述化合物中的上述鹼金屬的含量為0.1at%以上、5at%以下。 A photoelectric conversion element is a photoelectric conversion element in which a bottom electrode layer, a photoelectric conversion layer, a buffer layer, and a light-transmitting conductive layer are laminated on a substrate, and the photoelectric conversion layer contains an Ib group element, a group IIIb element, and a group VIb element. a compound semiconductor of a chalcopyrite structure as at least one of the above, characterized in that the buffer layer comprises a compound containing an alkali metal; the alkali metal is at least one of lithium, sodium and potassium; and the alkali in the above compound The content of the metal is 0.1 at% or more and 5 at% or less. 如申請專利範圍第1項所述的光電變換元件,其中構成上述緩衝層的化合物含有金屬、硫及氧,上述金屬是選自Cd、Zn、In及Sn所組成的群組中的至少一種。 The photoelectric conversion element according to claim 1, wherein the compound constituting the buffer layer contains a metal, sulfur, and oxygen, and the metal is at least one selected from the group consisting of Cd, Zn, In, and Sn. 如申請專利範圍第2項所述的光電變換元件,其中上述金屬為Zn。 The photoelectric conversion element according to claim 2, wherein the metal is Zn. 如申請專利範圍第1項所述的光電變換元件,其中上述鹼金屬的含量是0.5at%以上、2.5at%以下。 The photoelectric conversion element according to claim 1, wherein the content of the alkali metal is 0.5 at% or more and 2.5 at% or less. 如申請專利範圍第1項所述的光電變換元件,其中上述緩衝層的厚度是在1nm以上、100nm以下。 The photoelectric conversion element according to claim 1, wherein the buffer layer has a thickness of 1 nm or more and 100 nm or less. 如申請專利範圍第1項所述的光電變換元件,其中上述Ib族元素是選自Cu及Ag所組成的群組中的至少一種,上述IIIb族元素是選自Al、Ga及In所組成的群組中的至少一種,上述VIb族元素是選自S、Se及Te所組成的群組中的至少一種。 The photoelectric conversion element according to claim 1, wherein the Group Ib element is at least one selected from the group consisting of Cu and Ag, and the Group IIIb element is selected from the group consisting of Al, Ga, and In. At least one of the group, the group VIb element is at least one selected from the group consisting of S, Se, and Te. 一種太陽電池,其特徵在於,將申請專利範圍第1~6項中任一項所述的光電變換元件多個積體化而形成。 A solar cell, which is formed by integrating a plurality of photoelectric conversion elements according to any one of claims 1 to 6. 一種緩衝層的製造方法,其是在基板上積層有底電極層、光電變換層、緩衝層、透光性導電層之光電變換元件中的緩衝層的製造方法,上述光電變換層以包含Ib族元素、IIIb族元素與VIb族元素中至少一種的黃銅礦構造的化合物半導體作為主成分,其特徵在於:準備含有規定的金屬離子、硫脲、1M以上的鹼金屬離子的化學浴沉積用的反應液,使在上述基板上將上述底電極層及上述光電變換層以此順序積層而成的緩衝成膜用基板的至少上述光電變換層的表面接觸上述反應液,藉此在上述光電變換層上析出緩衝層。 A method for producing a buffer layer, which is a method for producing a buffer layer in a photoelectric conversion element in which a bottom electrode layer, a photoelectric conversion layer, a buffer layer, and a light-transmitting conductive layer are laminated on a substrate, wherein the photoelectric conversion layer contains an Ib group A compound semiconductor having a chalcopyrite structure of at least one of an element, a group IIIb element, and a group VIb element as a main component, which is prepared by chemical bath deposition containing a predetermined metal ion, thiourea, or an alkali metal ion of 1 M or more. In the reaction liquid, at least the surface of the photoelectric conversion layer of the buffer film-forming substrate on which the bottom electrode layer and the photoelectric conversion layer are laminated in this order are brought into contact with the reaction liquid, whereby the photoelectric conversion layer is A buffer layer is deposited on it. 一種光電變換元件的製造方法,其是在基板上積層有底電極層、光電變換層、緩衝層、透光性導電層的光電變換元件的製造方法,上述光電變換層以包含Ib族元素、IIIb族元素與VIb族元素中至少一種的黃銅礦構造的化合物半導體作為主成分,其特徵在於:藉由申請專利範圍第8項所記載之緩衝層的製造方法形成上述的緩衝層。 A method for producing a photoelectric conversion element, which is a method for producing a photoelectric conversion element in which a bottom electrode layer, a photoelectric conversion layer, a buffer layer, and a light-transmitting conductive layer are laminated on a substrate, wherein the photoelectric conversion layer contains a group Ib element, IIIb The compound semiconductor of the chalcopyrite structure of at least one of the group element and the group VIb element is a main component, and the buffer layer is formed by the method for producing a buffer layer according to the eighth aspect of the invention.
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US9520530B2 (en) 2014-10-03 2016-12-13 Taiwan Semiconductor Manufacturing Co., Ltd. Solar cell having doped buffer layer and method of fabricating the solar cell
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