JP2011176286A - Photoelectric conversion element, thin film solar cell, and method of manufacturing photoelectric conversion element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photoelectric conversion element that secures a sufficient supply amount of alkali metal to a photoelectric conversion layer, controls it precisely with good reproducibility, and enhances conversion efficiency, and is lightweight, superior in insulation and flexible; and to provide a thin film solar cell, and a method of manufacturing the photoelectric conversion element. <P>SOLUTION: The photoelectric conversion element includes a substrate with an insulating layer that has a metallic substrate 12 and the electrical insulating layer 16 formed on a surface of the metallic substrate 12, an alkali supply layer 50 formed on the electrical insulating layer 16, a lower electrode 32 formed on the alkali supply layer 50, the photoelectric conversion layer 34 formed on the lower electrode 32 and comprising a compound semiconductor layer, and an upper electrode 38 formed on the photoelectric conversion layer 34. The alkali supply layer 50 is a compound which principally comprises silicon oxide and includes a sodium compound, whose content is 7 to 20 at.% in terms of Na. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a flexible photoelectric conversion element, a thin film solar cell, and a method for manufacturing a photoelectric conversion element, which have excellent withstand voltage characteristics using a substrate with an insulating layer provided with an insulating layer and have high conversion efficiency. The present invention relates to a photoelectric conversion element, a thin-film solar cell, and a method for manufacturing a photoelectric conversion element that can control the amount of alkali metal supplied to a layer precisely and with high reproducibility and can increase conversion efficiency.

As the thin film solar cell substrate, a glass substrate is mainly used. However, the glass substrate is fragile and requires sufficient care in handling, and the range of application is limited because it lacks flexibility (flexibility). Recently, solar cells have attracted attention as a power supply source for buildings such as houses, and it is indispensable to increase the size of solar cells in order to secure sufficient power supply. In view of the above, it is desired to reduce the weight of the substrate.
However, for the purpose of reducing the weight, there is a demand for a substrate material that is more difficult to break and flexible and that can be made lighter than the glass substrate because the glass substrate becomes more easily broken when it is made thinner.

In addition, the price of the glass substrate is relatively high compared to the price of the photoelectric conversion layer material of the solar cell, and an inexpensive substrate material is desired in order to promote the spread of solar cells. When a metal is used as such a substrate material, it is difficult to insulate the solar cell material formed thereon, and when a resin is used, a solar cell is formed. There is a problem that it cannot withstand high temperatures exceeding 400 ° C. necessary for the above.
In other words, although glass substrates such as blue plate glass have sufficient insulation, they cannot achieve flexibility and weight reduction, and metal substrates are excellent in flexibility and weight reduction, but insulation cannot be ensured. It is difficult to develop a substrate that achieves both flexibility and weight reduction.

On the other hand, a copper-indium-gallium-selenium (CIGS) solar cell is known to improve power generation efficiency when sodium (Na) diffuses into a light absorption layer (photoelectric conversion layer). Conventionally, Na contained in blue glass is diffused into the light absorption layer by using blue glass as a substrate.
However, when using a metal plate or the like other than blue plate glass as the substrate of the solar cell, there is a problem that Na must be separately supplied to the light absorption layer in addition to the above-described insulation problem. For example, in Patent Literature 1 and Patent Literature 2, Na ₂ Se is vapor-deposited, in Patent Literature 3, Na ₂ O is vapor-deposited, and in Patent Literature 4, Na ₂ S is vapor-deposited. In Patent Document 5, sodium phosphate is deposited on molybdenum (Mo). In Patent Document 6, an aqueous solution containing sodium molybdate is adhered to a precursor. In Patent Document 7, Na ₂ S and Na ₂ Se are formed, and in Patent Document 8, Na ₃ AlF ₆ is formed between Mo and the substrate and / or the light absorption layer to supply Na. In Patent Document 9, Na ₂ S or Na ₂ Se is deposited on the Mo electrode, and in Patent Document 10 and Patent Document 11, NaF is coated on Mo and Na is supplied.

Moreover, in patent document 12, when using a metal substrate as a board | substrate for solar cells using a chalcopyrite type semiconductor, forming a glass layer on a metal substrate as an insulating layer interposed between photoelectric conversion layers. Thus, the withstand voltage of the substrate is increased, and the substrate is provided at low cost.
In Patent Document 13, a Na supply layer is provided on a conductive substrate, and Na is supplied to the light absorption layer through an electrode layer formed thereon.

In Non-Patent Document 1, a soda lime glass (SLG) thin film is formed on each of a Ti foil and a zirconia (ZrO ₂ ) substrate, and a lower electrode of molybdenum (Mo), a so-called back electrode is formed thereon. Yes. Non-Patent Document 1 discloses the thickness of a soda lime glass thin film that maximizes efficiency when using a Ti foil and a zirconia substrate.

Japanese Patent Laid-Open No. 10-74966 Japanese Patent Laid-Open No. 10-74967 JP-A-9-55378 Japanese Patent Application Laid-Open No. 10-125941 JP 2005-1117012 A Japanese Patent Laid-Open No. 2006-210424 JP 2003-318424 A JP 2005-86167 A JP-A-8-222750 JP 2004-158556 A JP 2004-79858 A JP 2006-80370 A Japanese Patent No. 3503824

APPLIED PHYSICS LETTERS 93, 124105 (2008)

As described above, when a metal plate other than blue glass (SLG) is used as a solar cell substrate, an alkali metal such as Na must be separately supplied in order to improve the conversion efficiency of the photoelectric conversion layer. There is. For example, even in an anodized aluminum substrate, an Na supply layer may be formed to diffuse an appropriate concentration of Na into the CIGS photoelectric conversion layer formed on the substrate, improve CIGS crystal quality, and realize improved conversion efficiency. Needed.
However, as in the prior art described in Patent Documents 1 to 11 described above, in order to diffuse Na into the photoelectric conversion layer, a layer of Na is formed on the back electrode by vapor deposition, sputtering, coating, or the like. Due to deliquescence and the like, problems have been pointed out such that the deposited Na layer is altered and easily peeled off.

In addition, as in Patent Document 12, when a metal substrate is used, a glass layer is formed as an insulating layer, but depending on the type of metal substrate, the difference in thermal expansion coefficient between the metal substrate and the photoelectric conversion layer is large. Has a problem that peeling occurs due to high temperature during film formation, and if the difference in thermal expansion coefficient between the metal substrate and the photoelectric conversion layer is small, it may withstand high temperature, but the thickness of the glass layer in the first place However, there is also a problem that a sufficient withstand voltage cannot be obtained. Further, since the glass layer contains alkali metal ions such as Na, the alkali metal ions diffuse into the photoelectric conversion layer during the formation of the photoelectric conversion layer, but at the same time also diffuse into the metal substrate. There is also a drawback. For this reason, there is a problem that the metal substrate is altered or peeled off, and a necessary amount of Na cannot be diffused in the photoelectric conversion layer.
Further, in the method for supplying Na to the photoelectric conversion layer disclosed in Patent Document 13, Na is diffused also in the substrate. Need to be thick enough. At this time, it has been confirmed that when the thickness increases, peeling occurs from the supply layer as a starting point.
Further, the Ti foil substrate disclosed in Non-Patent Document 1 has a drawback that it is difficult to ensure insulation and a solar cell having an integrated structure cannot be formed. Further, the zirconia substrate disclosed in Non-Patent Document 1 has a drawback that a flexible photoelectric conversion element and a solar cell cannot be formed, and also has a disadvantage that the cost is high.

In general, there is a problem that, for example, a joint portion between an insulating layer and a back electrode layer or a photoelectric conversion material layer is easily peeled due to a difference in thermal expansion coefficient.
In particular, in the case of an anodized aluminum substrate, the diffused Na changes the film quality of the anodized film, increasing the strain after CIGS growth and causing CIGS peeling.
In order to reduce the cost of solar cells and increase productivity, a method of diffusing alkali metal from the substrate side to the photoelectric conversion layer side within a short film formation time is required.

The object of the present invention is to solve the problems based on the above prior art, to ensure a sufficient supply amount of alkali metal to the photoelectric conversion layer, and to control precisely and with high reproducibility, and to increase the conversion efficiency. It is possible to provide a photoelectric conversion element, a thin-film solar cell, and a photoelectric conversion element manufacturing method that are lightweight, excellent in insulation, and flexible.
In addition to the above object, another object of the present invention is a photoelectric conversion element, a thin-film solar cell, and an excellent adhesion property between an insulating layer and a layer formed thereon, and having suitable withstand voltage characteristics and heat resistance characteristics. It is providing the manufacturing method of a photoelectric conversion element.

To achieve the above object, according to a first aspect of the present invention, there is provided a substrate with an insulating layer comprising a metal substrate and an electric insulating layer formed on a surface of the metal substrate, and an alkali formed on the electric insulating layer. A supply layer, a lower electrode formed on the alkali supply layer, a photoelectric conversion layer formed on the lower electrode and composed of a compound semiconductor layer, and an upper electrode formed on the photoelectric conversion layer The alkali supply layer is a compound containing silicon oxide as a main component and containing a sodium compound, and the content of the sodium compound is 7 to 20 at. It is intended to provide a photoelectric conversion element characterized by being%.
The content of sodium compounds alkali supply layer, in terms of Na 2 _O, the main component in silicon oxide, and 10 to 30% based on the total amount of the compound containing a sodium compound.

In order to achieve the above object, according to a second aspect of the present invention, there is provided a step of forming an electrical insulating layer on a surface of a metal substrate to obtain a substrate with an insulating layer, and silicon oxide on the electrical insulating layer. The main component is a compound containing a sodium compound, and the content of the sodium compound is 7 to 20 at. % Forming an alkali supply layer, forming a lower electrode on the alkali supply layer, forming a photoelectric conversion layer on the lower electrode, and forming an upper electrode on the photoelectric conversion layer The present invention provides a method for producing a photoelectric conversion element comprising a step.
Here, the metal substrate is a laminated plate in which a metal substrate and an Al substrate are laminated and integrated, and the step of obtaining the substrate with an insulating layer includes anodizing the Al substrate, The step of forming an anodic oxide film on the surface of the Al base is preferred.

  In each embodiment of the present invention, the compound semiconductor is preferably at least one compound semiconductor having a chalcopyrite structure, and at least one compound semiconductor comprising a group Ib element, a group IIIb element, and a group VIb element. More preferably, the Ib group element is at least one selected from the group consisting of Cu and Ag, and the IIIb group element is at least selected from the group consisting of Al, Ga, and In. More preferably, the group VIb element is at least one selected from the group consisting of S, Se, and Te.

In addition, the photoelectric conversion layer is preferably divided into a plurality of elements by a plurality of groove portions, and the plurality of elements are electrically connected in series.
Moreover, it is preferable that the said alkali supply layer is comprised with the silicate glass containing a sodium compound, and it is preferable that the said alkali supply layer is the film | membrane formed by the sputtering method. The alkali supply layer preferably has a thickness of 50 nm to 200 nm.
The lower electrode is made of Mo, and the thickness is preferably 200 nm to 600 nm, and more preferably 200 nm to 400 nm.

Moreover, it is preferable to have a diffusion prevention layer which prevents at least the diffusion of alkali metal into the substrate with an insulating layer between the alkali supply layer and the electrical insulating layer.
The diffusion prevention layer is preferably a nitride, and the nitride is preferably an insulator, more preferably at least one of TiN, ZrN, BN, and AlN. Most preferably.
Moreover, the thickness of the diffusion preventing layer is preferably 10 nm to 200 nm, and more preferably 10 nm to 100 nm.

Further, the metal substrate is preferably a laminated plate in which a metal base material and an Al base material are laminated and integrated, and the metal base material and the Al base material are integrated by pressure bonding. More preferably, it is a laminate.
Further, the metal base material is preferably a steel material, an alloy steel material, a Ti foil or a two-layer base material of a Ti foil and a steel material, and the alloy steel material is made of carbon steel or ferritic stainless steel. Preferably, the difference in thermal expansion coefficient between the metal substrate and the photoelectric conversion layer is preferably less than 3 × 10 ⁻⁶ / ° C., and more preferably less than 1 × 10 ⁻⁶ / ° C. The electrical insulating layer is preferably an aluminum anodic oxide film.
Further, the metal substrate is made of a laminated plate in which an alloy steel material made of carbon steel or ferritic stainless steel and an Al base material are integrated by pressure bonding, and the lower electrode is made of Mo. The photoelectric conversion layer is preferably a layer mainly composed of at least one compound semiconductor composed of an Ib group element, an IIIb group element, and a VIb group element.
The anodic oxide film preferably has a porous structure.
Moreover, in order to achieve the said objective, the 3rd aspect of this invention provides the thin film solar cell characterized by having the photoelectric conversion element of the said 1st aspect.

According to the present invention, the sodium compound content is 7 to 20 at. By providing the% alkali supply layer, the amount of alkali metal supplied to the photoelectric conversion layer can be controlled accurately and with good reproducibility. For this reason, a photoelectric conversion element with high photoelectric conversion efficiency can be obtained.
In addition, according to the present invention, since the diffusion amount of alkali metal to the photoelectric conversion layer can be increased by providing the diffusion prevention layer, a photoelectric conversion layer with higher conversion efficiency can be obtained.
In addition, by providing the diffusion preventing layer, a photoelectric conversion layer with good conversion efficiency can be obtained even if the thickness of the alkali supply layer is reduced. In particular, when the alkali supply layer is soda lime glass (SLG), by reducing the thickness of the layer, the alkali supply layer can be prevented from becoming a starting point of peeling. The film formation time can be shortened, and the productivity can be improved.

In addition, according to the present invention, the thermal expansion coefficients of the diffusion prevention film and the metal substrate or photoelectric conversion layer can be made uniform, and as a result, the adhesion between the diffusion prevention film and the metal substrate or photoelectric conversion layer is ensured. Can be improved, and peeling between the metal substrate and the photoelectric conversion layer can be prevented.
Furthermore, in the present invention, an insulating layer is formed on the substrate with an insulating layer, and the insulation (voltage resistance) of the substrate with the insulating layer is further improved by configuring the diffusion prevention layer with an insulator. Can be made.
In addition, according to the present invention, since a metal substrate mainly composed of aluminum (Al) having a flexible insulating layer can be used, the substrate has characteristics such that distortion is small and cracks do not occur even at high temperatures. be able to.

It is typical sectional drawing which shows the thin film solar cell which has a photoelectric conversion element which concerns on the 1st Embodiment of this invention. (A) is typical sectional drawing which shows the board | substrate used for the thin film solar cell which has a photoelectric conversion element which concerns on the 1st Embodiment of this invention, (b) is the photoelectric conversion which concerns on embodiment of this invention. It is typical sectional drawing which shows the other example of the board | substrate used for the thin film solar cell which has an element. It is typical sectional drawing which shows the thin film solar cell which has a photoelectric conversion element which concerns on the 2nd Embodiment of this invention. It is a graph which shows the relationship between conversion efficiency and the thickness of an alkali supply layer.

Hereinafter, based on preferred embodiments shown in the accompanying drawings, a photoelectric conversion element, a thin-film solar cell, and a method for manufacturing a photoelectric conversion element of the present invention will be described in detail.
FIG. 1 is a schematic cross-sectional view showing a thin-film solar cell having a photoelectric conversion element according to the first embodiment of the present invention.

  A thin film solar cell 30 of this embodiment shown in FIG. 1 is used as a solar cell module or a solar cell submodule constituting this solar cell module. For example, a substantially rectangular metal substrate 15 and a metal substrate that are grounded A substrate 10 with an insulating layer (hereinafter simply referred to as substrate 10) formed of an electrical insulating layer 16 formed on 15, an alkali supply layer 50 formed on the insulating layer 16, and an alkali supply layer 50; Power generation comprising a plurality of power generation cells (solar battery cells) 54 connected in series, a first conductive member 42 connected to one of the plurality of power generation cells 54, and a second conductive member 44 connected to the other side Layer 56. In addition, although the thing which consists of each part of the one electric power generation cell 54 and the board | substrate 10 and the alkali supply layer 50 corresponding to this is called the photoelectric conversion element 40 here, the thin film solar cell 30 itself shown in FIG. You may call it an element.

First, the board | substrate used for the thin film solar cell which has a photoelectric conversion element which concerns on embodiment of this invention is demonstrated.
Fig.2 (a) is typical sectional drawing which shows the board | substrate used for the thin film solar cell which has a photoelectric conversion element which concerns on embodiment of this invention shown in FIG. 1, (b) is embodiment of this invention. It is a typical sectional view showing other examples of a substrate used for a thin film solar cell which has such a photoelectric conversion element.

As shown in FIG. 2 (a), the substrate 10 includes a metal substrate 15 composed of a metal substrate 12 and an aluminum substrate 14 (hereinafter referred to as an Al substrate 14) mainly composed of aluminum, and an insulating layer 16. A substrate with an insulating layer.
In the substrate 10, an Al base 14 is formed on the surface 12 a of the metal base 12 to constitute a metal substrate 15, and an insulating layer 16 is formed on the surface 14 a of the Al base 14 of the metal substrate 15. Further, the metal substrate 15 is a laminate in which the metal base 12 and the Al base 14 are laminated and integrated, that is, an Al clad base or an Al clad substrate.

  The board | substrate 10 of this embodiment is utilized for the board | substrate of a photoelectric conversion element and a thin film solar cell, for example, is flat form. The shape, size, and the like of the substrate 10 are appropriately determined according to the size of the applied photoelectric conversion element and thin film solar cell. When used for a thin film solar cell, the substrate 10 has, for example, a rectangular shape or a rectangular shape in which the length of one side exceeds 1 m.

In the substrate 10, a flat or foil-like metal material is used for the metal base 12, and for example, a steel material such as carbon steel and ferritic stainless steel is used.
The steel material used for the metal base 12 has higher heat resistance at 300 ° C. or higher than the aluminum alloy, and the substrate 10 can obtain predetermined heat resistance.

As the carbon steel used for the metal base 12 described above, for example, carbon steel for mechanical structure having a carbon content of 0.6% by mass or less is used. As carbon steel for machine structure, what is generally called SC material is used, for example.
Moreover, as a ferritic stainless steel, SUS430, SUS405, SUS410, SUS436, SUS444, etc. can be used.
In addition to this, what is generally called SPCC (cold rolled steel sheet) is used as the steel material.

In addition to the above, the metal substrate 12 may be made of Kovar alloy, titanium, or titanium alloy. As titanium, pure Ti is used, and as the titanium alloy, Ti-6Al-4V and Ti-15V-3Cr-3Al-3Sn, which are alloys for extending, are used. These metals are also used in a flat plate shape or a foil shape.
The metal substrate 12 is preferably a metal or alloy having a smaller coefficient of thermal expansion, higher rigidity, and higher heat resistance than aluminum and aluminum alloys.

Since the thickness of the metal substrate 12 affects the flexibility, it is preferable to make it thin within a range that does not involve an excessive lack of rigidity.
In the board | substrate 10 of this embodiment, the thickness of the metal base material 12 is 10-800 micrometers, for example, Preferably it is 30-300 micrometers. More preferably, it is 50-150 micrometers. It is preferable to reduce the thickness of the metal substrate 12 from the viewpoint of raw material costs.
When the metal substrate 12 is flexible, that is, flexible, the metal substrate 12 is preferably ferritic stainless steel.

The Al base material 14 is composed of aluminum (Al) as a main component, and aluminum as a main component means that the aluminum content is 90% by mass or more.
As the Al base material 14, for example, aluminum or an aluminum alloy is used. The aluminum or aluminum alloy used for the Al substrate 14 preferably does not contain unnecessary intermetallic compounds. Specifically, aluminum having a purity of 99% by mass or more with few impurities is preferable. As purity, for example, 99.99 mass% Al, 99.96 mass% Al, 99.9 mass% Al, 99.85 mass% Al, 99.7 mass% Al, 99.5 mass% Al, etc. are preferable. . Moreover, what added the element which is hard to make an intermetallic compound can be used for an aluminum alloy. For example, it is an aluminum alloy obtained by adding 2.0 to 7.0% by mass of magnesium to Al having a purity of 99.9% by mass. In addition to magnesium, elements having a high solid solubility limit such as Cu and Si can be added.

  By increasing the purity of the aluminum of the Al base 14, it is possible to avoid intermetallic compounds resulting from precipitates, and to increase the soundness of the insulating layer 16. This is because, when anodizing of an aluminum alloy is performed, an intermetallic compound may be the starting point, which may cause insulation failure. If there are many intermetallic compounds, the possibility increases.

Moreover, the thickness of Al base material 14 is 5-150 micrometers, for example, Preferably it is 10-100 micrometers. More preferably, it is 20-50 micrometers.
Moreover, the surface roughness of the Al base 14 is, for example, 1 μm or less in terms of arithmetic average roughness Ra. Preferably, it is 0.5 μm or less, more preferably 0.1 μm or less.
Note that the surface of the Al base 14 may be mirror-finished. This mirror finish is performed, for example, by the methods described in Japanese Patent No. 4212621, Japanese Patent Application Laid-Open No. 2003-341696, Japanese Patent Application Laid-Open No. 7-331379, Japanese Patent Application Laid-Open No. 2007-196250, and Japanese Patent Application Laid-Open No. 2000-223205. The

In the substrate 10, the insulating layer 16 is for preventing insulation and damage due to mechanical shock during handling. This insulating layer 16 is composed of an anodized film (aluminum anodized film (alumina film)).
The insulating layer 16 is not limited to the anodic oxide film, and may be formed by, for example, vapor deposition, sputtering, or CVD.

The thickness of the insulating layer 16 is preferably 5 μm or more, and more preferably 10 μm or more. When the thickness of the insulating layer 16 is excessively large, it is not preferable because flexibility is lowered and cost and time required for forming the insulating layer 16 are required. In practice, the thickness of the insulating layer 16 is 50 μm or less, preferably 30 μm or less at maximum. For this reason, the preferable thickness of the insulating layer 16 is 0.5-50 micrometers.
Further, the surface roughness of the surface 18a of the insulating layer 16 is, for example, an arithmetic average roughness Ra of 1 μm or less, preferably 0.5 μm or less, more preferably 0.1 μm or less.

The substrate 10 needs to have a tensile strength of 5 MPa or more, preferably 10 MPa or more, while being heat-treated at 500 ° C. or more.
Further, in order to prevent creep deformation during heat treatment at 500 ° C. or higher, it is preferable that the strength causing plastic deformation of 0.1% at the maximum when held at 500 ° C. for 10 minutes is 0.2 MPa or higher. More preferably, it is 0.4 MPa or more, and further preferably 1 MPa or more.

In addition, the board | substrate 10 becomes flexible as the board | substrate 10 whole by making all the metal base material 12, the Al base material 14, and the insulating layer 16 have flexibility, ie, a flexible thing. Thereby, for example, in the roll-to-roll method, on the insulating layer 16 side of the substrate 10, an alkali supply layer, a diffusion prevention layer, a back electrode serving as a lower electrode, a photoelectric conversion layer, a transparent electrode serving as an upper electrode, etc. Can be formed.
Further, in the present embodiment, the substrate 10 is formed on the metal substrate 15 in which the metal base 12 and the Al base 14 are laminated and integrated, and the surface 14a of the Al base 14 of the metal substrate 15. By using an insulating layer-equipped substrate including the insulating layer 16, for example, high insulating properties and high strength can be maintained even after a film forming process at a temperature of 500 ° C. or higher, and the occurrence of strain is suppressed. It is possible to form various films at a high temperature of 500 ° C. or higher, for example, by a roll-to-roll method.

Further, the substrate 10 of the present embodiment is configured to include the metal substrate 15 having a two-layer structure of the metal substrate 12 and the Al substrate 14, but the present invention is not limited to the metal substrate 12 having at least one layer. Therefore, it is not limited to one layer, and a plurality of layers may be used.
Like the board | substrate 10a shown in FIG.2 (b), the metal base material may be 2 layer structure which has the 1st metal base material 13a and the 2nd metal base material 13b, for example.
In this case, for example, the first metal base 13 a is made of titanium or a titanium alloy, and the second metal base 13 b is made of a steel material like the metal base 12. The second metal base 13b may be made of titanium or a titanium alloy, and the first metal base 13a may be made of steel similarly to the metal base 12.
Furthermore, it is good also as a structure by which the Al base material 14 is formed in the surface 12a and back surface of the metal base material 12, and the insulating layer 16 is formed in the surface 14a of each Al base material 14 as a board | substrate. In this case, the Al base material 14 and the insulating layer 16 are formed symmetrically around the metal base material 12. In addition, what laminated | stacked and integrated the metal base material 12 and the two Al base materials 14 becomes a metal substrate.

Next, the manufacturing method of the board | substrate 10 of this embodiment is demonstrated.
First, the metal substrate 12 is prepared. The metal base 12 is formed in a predetermined shape and size depending on the size of the substrate 10 to be formed.
Next, the Al base material 14 is formed on the surface 12 a of the metal base material 12. Thereby, the metal substrate 15 is configured.
The method for forming the Al base material 14 on the surface 12a of the metal base material 12 is particularly limited as long as an integrated bond capable of ensuring the adhesion between the metal base material 12 and the Al base material 14 is achieved. is not. As a method for forming the Al base material 14, for example, a vapor phase method such as an evaporation method or a sputtering method, a plating method, and a pressure bonding method after surface cleaning can be used. As a method for forming the Al base material 14, pressure bonding by roll rolling or the like is preferable from the viewpoint of cost and mass productivity.

  Next, the insulating layer 16 is formed on the surface 14 a of the Al base 14 of the metal substrate 15. In this way, the substrate 10 is obtained. Hereinafter, a method of forming the anodic oxide film that is the insulating layer 16 will be described.

When forming the anodic oxide film which is the insulating layer 16, the anodic oxide film can be formed by using the metal substrate 12 as an anode, immersing it in an electrolyte together with a cathode, and applying a voltage between the anode and the cathode. At this time, when the metal substrate 12 comes into contact with the electrolyte, in order to form a local battery with the Al substrate 14, the metal substrate 12 in contact with the electrolyte is masked and insulated by a masking film (not shown). It is necessary to keep. That is, it is necessary to insulate the end surface and the back surface of the metal substrate 12 other than the surface 14a of the Al substrate 14 using a masking film (not shown).
Prior to the anodizing treatment, the surface of the Al base 14 is subjected to cleaning treatment, polishing smoothing treatment, or the like as necessary.

Carbon, Al, or the like is used as a cathode during anodization. As the electrolyte, an acidic electrolytic solution containing one or more acids such as sulfuric acid, phosphoric acid, chromic acid, oxalic acid, sulfamic acid, benzenesulfonic acid, and amidesulfonic acid is used. Anodizing conditions are not particularly limited by the type of electrolyte used. As anodizing conditions, for example, electrolyte concentration 1 to 80% by mass, liquid temperature 5 to 70 ° C., current density 0.005 to 0.60 A / cm ² , voltage 1 to 200 V, electrolysis time 3 to 500 minutes It is appropriate if it exists. As the electrolyte, sulfuric acid, phosphoric acid, oxalic acid or a mixture thereof is preferable. When such an electrolyte is used, the electrolyte concentration is preferably 4 to 30% by mass, the liquid temperature is 10 to 30 ° C., the current density is 0.002 to 0.30 A / cm ² , and the voltage is 20 to 100V.

During the anodizing treatment, an oxidation reaction proceeds in a substantially vertical direction from the surface 14a of the Al base material 14, and an anodized film is generated on the surface 14a of the Al base material 14. When the above acidic electrolytic solution is used, the anodic oxide film has a fine columnar body having a substantially regular hexagonal shape in plan view arranged without gaps, and has a round bottom at the center of each fine columnar body. Holes are formed, and a porous type in which a barrier layer (usually 0.02 to 0.1 μm in thickness) is formed at the bottom of the fine columnar body.
Such an anodic oxide film having a porous structure has a low Young's modulus of the film compared to a non-porous aluminum oxide single film, and has a high resistance to bending and cracking caused by a difference in thermal expansion at high temperatures. Become.

When electrolytic treatment is carried out with a neutral electrolytic solution such as boric acid without using an acidic electrolytic solution, a dense anodic oxide film (non-porous aluminum oxide simple substance film) is formed instead of an anodic oxide film in which porous fine columnar bodies are arranged. Become. After the porous anodic oxide film is formed with the acidic electrolytic solution, an anodic oxide film having a thicker barrier layer may be formed by a pore filling method in which re-electrolytic treatment is performed with the neutral electrolytic solution. By increasing the thickness of the barrier layer, it is possible to obtain a coating with higher insulation.
As the electrolytic solution used for the anodizing treatment, an aqueous sulfuric acid solution or an aqueous oxalic acid solution is preferably used. An oxalic acid aqueous solution is excellent in soundness of the anodic oxide film, and a sulfuric acid aqueous solution is excellent in continuous treatment productivity.
The preferable thickness of the anodic oxide film that is the insulating layer 16 is 0.5 to 50 μm as described above. This thickness is controllable by constant current electrolysis, constant voltage electrolysis current, voltage magnitude, and electrolysis time.

The insulating layer 16 formed by anodic oxidation is subjected to sealing treatment in a boric acid solution when it is particularly desired to enhance the insulation.
As the sealing treatment, an electrochemical method or a chemical method is known, and an electrochemical method (anodic treatment) using aluminum or an aluminum alloy as an anode is particularly preferable.
The electrochemical method is preferably a method in which aluminum or an alloy thereof is used as an anode and a direct current is applied to perform sealing treatment. The electrolytic solution is preferably an aqueous boric acid solution, and is preferably an aqueous solution obtained by adding a borate containing sodium to an aqueous boric acid solution. Examples of borates include disodium octaborate, sodium tetraphenylborate, sodium tetrafluoroborate, sodium peroxoborate, sodium tetraborate, and sodium metaborate. These borates are available as anhydrous or hydrated.

As an electrolytic solution used for the sealing treatment, it is particularly preferable to use an aqueous solution obtained by adding 0.01 to 0.5 mol / L sodium tetraborate to a 0.1 to 2 mol / L boric acid aqueous solution. It is preferable that 0 to 0.1 mol / L of aluminum ion is dissolved. Aluminum ions are chemically or electrochemically dissolved in the electrolytic solution by a sealing treatment, and a method of electrolyzing by adding aluminum borate in advance is particularly preferable. Further, trace elements contained in the aluminum alloy may be dissolved.
Preferred sealing treatment conditions are a liquid temperature of 10 to 55 ° C. (particularly preferably 10 to 30 ° C.), a current density of 0.01 to 5 A / dm ² (particularly preferably 0.1 to 3 A / dm ² ), and an electrolytic treatment time. 0.1 to 10 minutes (particularly preferably 1 to 5 minutes).

As the current, an alternating current, a direct current, or an AC / DC superimposed current can be used. The method of applying the current may be constant or gradually increasing from the initial stage of electrolysis, but a method using direct current is particularly preferable. Either a constant voltage method or a constant current method may be used for applying the current.
At this time, the voltage between the substrate and the counter electrode is preferably 100 to 1000 V, and the voltage depends on the electrolytic bath composition, the liquid temperature, the flow velocity at the aluminum interface, the power waveform, the distance between the substrate and the counter electrode, the electrolysis time, and the like. Change.
As the electrolyte flow rate on the substrate surface and the method of giving the flow rate, the electrolytic bath, the electrode, and the concentration control method of the electrolytic solution can use the known anodizing method and the sealing method described in the anodizing treatment. It is. The film thickness when anodizing in a boric acid aqueous solution containing sodium borate is preferably 100 nm or more, and more preferably 300 nm or more. The upper limit is the film thickness of the porous anodic oxide film. Thereby, it can use for the board | substrate of a thin film solar cell which requires especially high temperature intensity | strength and has the merit of flexibility.

In addition, a chemically preferable method may be a structure in which pores and / or vacancies are filled with Si oxide after anodizing. For filling with Si oxide, a solution containing a compound having a Si—O bond is applied, or a sodium silicate aqueous solution (No. 1 sodium silicate or No. 3 sodium silicate, 1 to 5 mass% aqueous solution, 20 to 70 ° C.) is 1 A method of washing and drying after immersing for ˜30 seconds and further baking at 200 to 600 ° C. for 1 to 60 minutes is also possible.
As a chemically preferable method, in addition to the sodium silicate aqueous solution, the concentration of sodium fluoride zirconate and / or sodium dihydrogen phosphate alone or a mixed aqueous solution having a mixing ratio of 5: 1 to 1: 5 by weight A method of performing a sealing treatment by immersing in 1 to 5% by mass of a liquid at 20 to 70 ° C. for 1 to 60 seconds can also be used.
In addition, about an anodizing process, it can carry out with the well-known what is called a roll-to-roll system anodizing apparatus, for example.

Next, after the anodizing treatment, the masking film (not shown) is peeled off. Thereby, the substrate 10 can be formed.
Since the substrate 10 of the present invention can use the metal substrate 15 having the Al base 14 mainly composed of aluminum (Al) having an anodic oxide film having flexibility as the insulating layer 16, there is little distortion even at a high temperature. Excellent characteristics such as no cracks.

Next, the photoelectric conversion element 40 of the thin film solar cell 30 of this embodiment shown in FIG. 1 will be described.
In the thin film solar cell (for example, the thin film solar cell submodule) 30 of this embodiment, the alkali supply layer 50 is formed on the surface of the substrate 10 described above, that is, the surface 16a of the insulating layer 16.
The thin film solar cell 30 includes a plurality of photoelectric conversion elements 40, a first conductive member 42, and a second conductive member 44.

The photoelectric conversion element 40 constitutes the thin-film solar cell 30, and includes a power generation cell (substrate 10, an alkali supply layer 50, a back electrode 32, a photoelectric conversion layer 34, a buffer layer 36, and a transparent electrode 38). Solar cell) 54.
As described above, the alkali supply layer 50 is formed on the surface 16 a of the insulating layer 16. On the surface 50 a of the alkali supply layer 50, the back electrode 32, the photoelectric conversion layer 34, the buffer layer 36, and the transparent electrode 38 of the power generation cell 54 are sequentially stacked.

  The back electrode 32 is formed on the surface 50 a of the alkali supply layer 50 by providing an adjacent back electrode 32 and a separation groove (P 1) 33. A photoelectric conversion layer 34 is formed on the back electrode 32 while filling the separation groove (P1) 33. A buffer layer 36 is formed on the surface of the photoelectric conversion layer 34. The photoelectric conversion layer 34 and the buffer layer 36 are separated from other photoelectric conversion layers 34 and the buffer layer 36 by a groove (P2) 37 reaching the back electrode 32. The groove (P2) 37 is formed at a position different from the separation groove (P1) 33 of the back electrode 32.

A transparent electrode 38 is formed on the surface of the buffer layer 36 while filling the groove (P2) 37.
An opening groove (P3) 39 that penetrates the transparent electrode 38, the buffer layer 36, and the photoelectric conversion layer 34 and reaches the back electrode 32 is formed. In the thin film solar cell 30, each photoelectric conversion element 40 is electrically connected in series in the longitudinal direction L of the substrate 10 by the back electrode 32 and the transparent electrode 38.

The photoelectric conversion element 40 of this embodiment is called an integrated photoelectric conversion element (solar cell). For example, the back electrode 32 is composed of a molybdenum electrode, and the photoelectric conversion layer 34 is a semiconductor having a photoelectric conversion function. A compound, for example, is composed of a CIGS layer, the buffer layer 36 is composed of CdS, and the transparent electrode 38 is composed of ZnO.
The photoelectric conversion element 40 is formed to extend in the width direction perpendicular to the longitudinal direction L of the substrate 10. For this reason, the back electrode 32 and the like also extend long in the width direction of the substrate 10.

  As shown in FIG. 1, a first conductive member 42 is connected on the back electrode 32 at the right end. The first conductive member 42 is for taking out an output from a negative electrode to be described later. Originally, the photoelectric conversion element 40 is formed on the back electrode 32 at the right end. For example, the photoelectric conversion element 40 is removed by laser scribing or mechanical scrubbing to expose the back electrode 32.

  The first conductive member 42 is, for example, an elongated belt-like member, extends in a substantially linear shape in the width direction of the substrate 10, and is connected to the right end back electrode 32. As shown in FIG. 1, the first conductive member 42 is, for example, a copper ribbon 42a covered with an indium copper alloy coating 42b. The first conductive member 42 is connected to the back electrode 32 by, for example, ultrasonic soldering.

  The second conductive member 44 is for taking out an output from a positive electrode described later to the outside. Similarly to the first conductive member 42, the second conductive member 44 is an elongated belt-like member, extends substantially linearly in the width direction of the substrate 10, and is connected to the back electrode 32 at the left end. Originally, the photoelectric conversion element 40 is formed on the leftmost back electrode 32. For example, the photoelectric conversion element 40 is removed by laser scribing or mechanical scrub, and the back electrode 32 is exposed.

The second conductive member 44 has the same configuration as the first conductive member 42. For example, a copper ribbon 44a is covered with a coating material 44b of indium copper alloy.
The first conductive member 42 and the second conductive member 44 may be tin-plated copper ribbons. Further, the connection between the first conductive member 42 and the second conductive member 44 is not limited to the ultrasonic soldering. For example, the first conductive member 42 and the second conductive member 44 may be connected using a conductive adhesive or a conductive tape.

In addition, the photoelectric conversion layer 34 of the photoelectric conversion element 40 of this embodiment is comprised by CIGS, for example, and can be manufactured with the manufacturing method of a well-known CIGS type solar cell.
The separation groove (P1) 33 of the back electrode 32, the groove (P2) 37 reaching the back electrode 32, and the opening groove (P3) 39 reaching the back electrode 32 can be formed by laser scribe or mechanical scribe.

  In the thin film solar cell 30, when light is incident on the photoelectric conversion element 40 from the transparent electrode 38 side, this light passes through the transparent electrode 38 and the buffer layer 36, and an electromotive force is generated in the photoelectric conversion layer 34. A current from the transparent electrode 38 toward the back electrode 32 is generated. The arrows shown in FIG. 1 indicate the direction of current, and the direction of movement of electrons is opposite to the direction of current. For this reason, in the photoelectric conversion unit 48, the leftmost back electrode 32 in FIG. 1 becomes a positive electrode (plus electrode), and the rightmost back electrode 32 becomes a negative electrode (minus electrode).

In the present embodiment, the electric power generated in the thin film solar cell 30 can be taken out of the thin film solar cell 30 from the first conductive member 42 and the second conductive member 44.
In the present embodiment, the first conductive member 42 is a negative electrode, and the second conductive member 44 is a positive electrode. Further, the first conductive member 42 and the second conductive member 44 may have opposite polarities, and are appropriately changed according to the configuration of the photoelectric conversion element 40, the configuration of the thin film solar cell 30, and the like.
Further, in the present embodiment, each photoelectric conversion element 40 is formed to be connected in series in the longitudinal direction L of the substrate 10 by the back electrode 32 and the transparent electrode 38, but is not limited thereto. For example, each photoelectric conversion element 40 may be formed such that each photoelectric conversion element 40 is connected in series in the width direction by the back electrode 32 and the transparent electrode 38.

  In the photoelectric conversion element 40, the back electrode 32 and the transparent electrode 38 are for taking out current generated in the photoelectric conversion layer 34. Both the back electrode 32 and the transparent electrode 38 are made of a conductive material. The transparent electrode 38 on the light incident side needs to have translucency.

The back electrode 32 is made of, for example, Mo, Cr, or W and a combination thereof. The back electrode 32 may have a single layer structure or a laminated structure such as a two-layer structure. The back electrode 32 is preferably composed of Mo.
Moreover, the formation method of the back surface electrode 32 is not specifically limited, It can form by vapor phase film-forming methods, such as an electron beam vapor deposition method and sputtering method.

  The back electrode 32 generally has a thickness of about 800 nm, but the back electrode 32 preferably has a thickness of 200 nm to 600 nm, and more preferably 200 nm to 400 nm. Thus, by making the film thickness of the back surface electrode 32 thinner than a general one, the diffusion rate of the alkali metal from the alkali supply layer 50 to the photoelectric conversion layer 34 can be increased as will be described later. In addition, the material cost of the back electrode 32 can be reduced, and the formation speed of the back electrode 32 can be increased.

The transparent electrode 38 is made of, for example, ZnO to which Al, B, Ga, Sb or the like is added, ITO (indium tin oxide), SnO ₂ or a combination thereof. The transparent electrode 38 may have a single layer structure or a laminated structure such as a two-layer structure. Further, the thickness of the transparent electrode 38 is not particularly limited, and is preferably 0.3 to 1 μm.
The method for forming the transparent electrode 38 is not particularly limited, and can be formed by a vapor deposition method such as an electron beam evaporation method or a sputtering method, or a coating method.

The buffer layer 36 is formed to protect the photoelectric conversion layer 34 when the transparent electrode 38 is formed and to transmit light incident on the transparent electrode 38 to the photoelectric conversion layer 34.
The buffer layer 36 is made of, for example, CdS, ZnS, ZnO, ZnMgO, ZnS (O, OH), or a combination thereof.
The buffer layer 36 preferably has a thickness of 30 to 100 nm. The buffer layer 36 is formed by, for example, a CBD (chemical bath) method.

  The photoelectric conversion layer 34 is a layer that generates a current by absorbing light that has passed through the transparent electrode 38 and the buffer layer 36, and has a photoelectric conversion function. In the present embodiment, the configuration of the photoelectric conversion layer 34 is not particularly limited, and includes, for example, at least one compound semiconductor having a chalcopyrite structure. Further, the photoelectric conversion layer 34 may be at least one compound semiconductor composed of a group Ib element, a group IIIb element, and a group VIb element.

Further, since the light absorption rate is high and high photoelectric conversion efficiency is obtained, the photoelectric conversion layer 34 is composed of at least one group Ib element selected from the group consisting of Cu and Ag, and a group consisting of Al, Ga, and In. It is preferably at least one compound semiconductor composed of at least one type IIIb group element selected more and at least one type VIb group element selected from the group consisting of S, Se and Te. As this compound semiconductor, CuAlS ₂ , CuGaS ₂ , CuInS ₂ , CuAlSe ₂ , CuGaSe ₂ , CuInSe ₂ (CIS), AgAlS ₂ , AgGaS ₂ , AgInS ₂ , AgAlSe ₂ , AgGaSe ₂ , AgInSe ₂ , AgInSe ₂ , AgInSe ₂ , AgInSe ₂ , AgInT , AgInTe ₂ , Cu (In _1-x Ga _x ) Se ₂ (CIGS), Cu (In _1-x Al _x ) Se ₂ , Cu (In _1-x Ga _x ) (S, Se) ₂ , Ag (In _1-x Ga _x ) Se ₂ , Ag (In _1-x Ga _x ) (S, Se) _{2 and the} like.

The photoelectric conversion layer 34 particularly preferably includes CuInSe ₂ (CIS) and / or Cu (In, Ga) Se ₂ (CIGS) in which Ga is dissolved. CIS and CIGS are semiconductors having a chalcopyrite crystal structure, have high light absorption, and high photoelectric conversion efficiency has been reported. Moreover, there is little degradation of efficiency by light irradiation etc. and it is excellent in durability.

The photoelectric conversion layer 34 contains impurities for obtaining a desired semiconductor conductivity type. Impurities can be contained in the photoelectric conversion layer 34 by diffusion from adjacent layers and / or active doping. In the photoelectric conversion layer 34, the constituent elements and / or impurities of the I-III-VI group semiconductor may have a concentration distribution, and a plurality of layer regions having different semiconductor properties such as n-type, p-type, and i-type May be included.
For example, in the CIGS system, when the Ga amount in the photoelectric conversion layer 34 has a distribution in the thickness direction, the band gap width / carrier mobility and the like can be controlled, and the photoelectric conversion efficiency can be designed high.

The photoelectric conversion layer 34 may include one or more semiconductors other than the I-III-VI group semiconductor. As a semiconductor other than the I-III-VI group semiconductor, a semiconductor composed of a group IVb element such as Si (group IV semiconductor), a semiconductor composed of a group IIIb element such as GaAs and a group Vb element (group III-V semiconductor), and Examples thereof include semiconductors (II-VI group semiconductors) composed of IIb group elements such as CdTe and VIb group elements. The photoelectric conversion layer 34 may contain an optional component other than a semiconductor and impurities for obtaining a desired conductivity type as long as the characteristics are not hindered.
Further, the content of the I-III-VI group semiconductor in the photoelectric conversion layer 34 is not particularly limited. 75 mass% or more is preferable, as for content of the I-III-VI group semiconductor in the photoelectric converting layer 34, 95 mass% or more is more preferable, and 99 mass% or more is especially preferable.

  In the present embodiment, when the photoelectric conversion layer 34 is composed of a compound semiconductor composed of a group Ib element, a group IIIb element, and a group VIb element, the metal substrate 12 is composed of carbon steel or ferritic stainless steel. The back electrode 32 is preferably made of molybdenum.

  As CIGS layer deposition methods, 1) multi-source co-evaporation, 2) selenization, 3) sputtering, 4) hybrid sputtering, and 5) mechanochemical process are known.

1) As a multi-source simultaneous vapor deposition method,
Three-stage method (JRTuttle et.al, Mat.Res.Soc.Symp.Proc., Vol.426 (1996) p.143. Etc.) and EC group co-evaporation method (L. Stolt et al .: Proc. 13th ECPVSEC (1995, Nice) 1451, etc.).
In the former three-stage method, In, Ga, and Se are first co-deposited at a substrate temperature of 300 ° C. in a high vacuum, and then heated to 500 to 560 ° C., and Cu and Se are co-evaporated. In this method, Ga and Se are further vapor-deposited. The latter EC group simultaneous vapor deposition method is a method in which Cu-excess CIGS is vapor-deposited in the early stage of vapor deposition and In-rich CIGS is vapor-deposited in the latter half.

In order to improve the crystallinity of the CIGS film, as a method of improving the above method,
a) a method using ionized Ga (H. Miyazaki, et.al, phys.stat.sol. (a), Vol.203 (2006) p.2603, etc.),
b) Method of using cracked Se (68th Japan Society of Applied Physics Academic Lecture Proceedings (Autumn 2007, Hokkaido Institute of Technology) 7P-L-6 etc.),
c) Method using radicalized Se (Proceedings of the 54th Japan Society of Applied Physics (Aoyama Gakuin University) 29P-ZW-10 etc.)
d) A method using a photoexcitation process (the 54th Japan Society of Applied Physics Academic Lecture Proceedings (Spring 2007 Aoyama Gakuin University) 29P-ZW-14 etc.) is known.

2) The selenization method is also called a two-step method. First, a metal precursor of a laminated film such as a Cu layer / In layer or a (Cu—Ga) layer / In layer is formed by sputtering, vapor deposition, or electrodeposition. This is a method of forming a selenium compound such as Cu (In _1-x Ga _x ) Se ₂ by a thermal diffusion reaction by forming a film and heating it in selenium vapor or hydrogen selenide to about 450 to 550 ° C. . This method is called a vapor phase selenization method. In addition, there is a solid-phase selenization method in which solid-phase selenium is deposited on a metal precursor film and selenized by a solid-phase diffusion reaction using the solid-phase selenium as a selenium source.

  In the selenization method, in order to avoid the rapid volume expansion that occurs during selenization, a method of previously mixing selenium in a metal precursor film at a certain ratio (T. Nakada et.al, Solar Energy Materials and Solar Cells 35 (1994) 204-214, etc.), and multilayer precursor film with selenium sandwiched between thin metal layers (for example, Cu layer / In layer / Se layer ... stacked with Cu layer / In layer / Se layer) (T. Nakada et.al, Proc. Of 10th European Photovoltaic Solar Energy Conference (1991) 887-890. Etc.) is known.

  In addition, as a method for forming a graded band gap CIGS film, a Cu—Ga alloy film is first deposited, an In film is deposited thereon, and when this is selenized, natural thermal diffusion is used to form Ga. There is a method in which the concentration is inclined in the film thickness direction (K. Kushiya et.al, Tech.Digest 9th Photovoltaic Science and Engineering Conf. Miyazaki, 1996 (Intn. PVSEC-9, Tokyo, 1996) p.149.).

3) As a sputtering method,
A method using CuInSe ₂ polycrystal as a target, a two-source sputtering method using Cu ₂ Se and In ₂ Se ₃ as a target and a H ₂ Se / Ar mixed gas as a sputtering gas (JHErmer, et.al, Proc. 18th IEEE Photovoltaic Specialists Conf. (1985) 1655-1658. Etc.), and a three-source sputtering method in which a Cu target, an In target, and a Se or CuSe target are sputtered in Ar gas (T. Nakada, et.al, Jpn. J. Appl. Phys. 32 (1993) L1169-L1172.

  4) As the hybrid sputtering method, in the sputtering method described above, Cu and In metal are DC sputtering, and only Se is vapor deposition (T. Nakada, et.al., Jpn.Appl.Phys.34 ( 1995) 4715-4721.

  5) In the mechanochemical process method, raw materials corresponding to the CIGS composition are put into a planetary ball mill container, and the raw materials are mixed by mechanical energy to obtain CIGS powder, which is then applied onto the substrate by screen printing and annealed. To obtain a CIGS film (T. Wada et.al, Phys.stat.sol. (A), Vol.203 (2006) p2593, etc.).

  Examples of other CIGS film formation methods include screen printing, proximity sublimation, MOCVD, and spray (wet film formation). For example, a fine particle film containing a group Ib element, a group IIIb element, and a group VIb element is formed on a substrate by a screen printing method (wet film forming method) or a spray method (wet film forming method), and then pyrolyzed ( At this time, a crystal having a desired composition can be obtained by performing a thermal decomposition treatment in a VIb group element atmosphere (JP-A-9-74065, JP-A-9-74213, etc.).

Moreover, in this embodiment, it is preferable that the difference of the linear thermal expansion coefficient of the metal base material 12 and the photoelectric converting layer 34 is less than 3 * 10 < ^-6 > / degreeC.
The linear thermal expansion coefficient of the main compound semiconductor used as the photoelectric conversion layer 34 is 5.8 × 10 ⁻⁶ / ° C. for GaAs, which is representative of the III-V group, and 4 for CdTe, which is representative of the II-VI group. 5 × 10 ⁻⁶ / ° C. and 10 × 10 ⁻⁶ / ° C. for Cu (InGa) Se ₂ , which is representative of the I-III-VI group.
When the compound semiconductor is formed as a photoelectric conversion layer 34 on the substrate 10 at a high temperature of 500 ° C. or higher and then cooled to room temperature, if the difference in thermal expansion from the metal substrate 12 is large, film formation defects such as peeling may occur. Arise. Moreover, the photoelectric conversion efficiency of the photoelectric converting layer 34 may fall by the strong internal stress in the compound semiconductor resulting from a thermal expansion difference with the metal base material 12. It is preferable that the difference in coefficient of linear thermal expansion between the metal substrate 12 and the photoelectric conversion layer 34 (compound semiconductor) is less than 3 × 10 ⁻⁶ / ° C. because film formation defects such as peeling are unlikely to occur. More preferably, the difference in coefficient of linear thermal expansion is less than 1 × 10 ⁻⁶ / ° C. Here, the thermal expansion coefficient and the difference between the thermal expansion coefficients are both room temperature (23 ° C.) values.

The alkali supply layer 50 supplies, for example, an alkali metal during film formation of the photoelectric conversion layer 34 in order to diffuse an alkali metal (ion), for example, Na (Na ⁺ ), into the photoelectric conversion layer 34 (CIGS layer). Is for.

The alkali supply layer 50 is composed of a compound containing silicon oxide as a main component and containing a sodium compound.
In the alkali supply layer 50, the content (concentration) of a sodium compound (for example, oxide: Na ₂ O) is calculated as Na ₂ O with respect to the total amount of the compound containing the sodium compound as the main component and containing the sodium compound. 10 to 30% (7 to 20 at.% In terms of Na). The content (concentration) of this sodium compound may be the content at the time when the alkali supply layer 50 is formed, or the content at the time when the photoelectric conversion element 40 is formed.
The content of sodium compounds alkali supply layer 50 is preferably (10~16at.% Is calculated as Na) 15-25% by the above terms of Na ₂ O.

  Since the alkali supply layer 50 is easy to obtain a compound that is chemically stable and easy to handle Na, is easily released from the alkali supply layer 50 by heating, and the effect of improving the crystallinity of the photoelectric conversion layer 34 is high. Including sodium compounds.

The composition of the alkali supply layer 50 is not particularly limited as long as the content in Na ₂ O conversion is 10 to 30% (7 to 20 at.% In Na conversion). Two or more alkali metals and / or alkaline earth metals may be included.
The alkali supply layer 50 is made of an insulating material made of a compound containing a sodium compound and containing silicon oxide as a main component. The alkali supply layer 50 may have a single layer structure or a multilayer structure in which layers having different compositions are stacked.

In the present invention, when the content of the alkali supply layer 50 in terms of Na ₂ O is less than 10% (7 at.% In terms of Na), the amount of alkali metal diffusing into the photoelectric conversion layer 34 is small and the conversion efficiency is poor. . When the amount of alkali metal diffusing into the photoelectric conversion layer 34 is small, it is necessary to increase the thickness in order to sufficiently supply the alkali metal to the alkali supply layer 50. When the thickness of the alkali supply layer 50 is increased, it may be a starting point of peeling, and thus cannot be increased.
On the other hand, the alkali supply layer 50 having a Na ₂ O equivalent content exceeding 30% (20 at.% Na equivalent) is composed of a target used for forming the alkali supply layer 50 by sputtering. The production of the target becomes difficult due to unevenness.

In the present embodiment, the alkali supply layer 50 can be made of, for example, silicate glass containing a sodium compound. When the alkali supply layer 50 is a silicate glass compound containing a sodium compound, the content of the sodium compound with respect to the entire silicate glass (total amount) is 10 to 30% in terms of Na ₂ O.
Specifically, as the alkali supply layer 50, for example, as shown in Table 1 below, soda lime glass containing sodium oxide (Na ₂ O) as a sodium compound can be used. In this case, the content of the sodium compound is the content of sodium oxide (Na ₂ O) in the soda lime glass shown in Table 1 below. The soda lime glass shown in Table 1 below has a Na ₂ O content of 15%. That is, the content of the sodium compound is 15% in terms of Na ₂ O (10 at.% In terms of Na). Soda lime glass is also referred to as blue plate glass or soda lime silica glass.

In the soda lime glass shown in Table 1, when the content of sodium oxide (Na ₂ O) increases or decreases, the amount of Na ₂ O increases or decreases, and the amount of SiO ₂ or the like decreases accordingly.
When a soda lime glass layer is formed as the alkali supply layer 50, for example, a PVD method (physical vapor deposition method) such as an RF sputtering method or a vapor deposition method using soda lime glass as a vapor deposition source can be used.

Moreover, since it will become easy to peel when the film thickness of the alkali supply layer 50 is thick, the thickness of the alkali supply layer 50 is preferably 50 to 200 nm.
In this embodiment, since the content (concentration) of the sodium compound in the alkali supply layer 50 is 10 to 30% in terms of Na ₂ O (7 to 20 at.% In terms of Na), the film of the alkali supply layer 50 Even if the thickness is as thin as 50 to 200 nm, an alkali metal sufficient to improve the conversion efficiency can be supplied to the photoelectric conversion layer 34. As described above, in the present invention, since the thickness of the alkali supply layer 50 can be reduced, the alkali supply layer 50 can be prevented from becoming a starting point of peeling, and the film formation time of the alkali supply layer 50 and the like can be shortened. And the productivity of the solar cell can be improved. In particular, as the content of the sodium compound is larger, it is easier to obtain the effect of improving the conversion efficiency of the above-described photoelectric conversion layer 34 and shortening the film formation time of the alkali supply layer 50 and the like. For this reason, it is preferable that content of the sodium compound in the alkali supply layer 50 is near the upper limit of 30% in Na ₂ O conversion (20 at.% In Na conversion).
In the present invention, the diffusion amount of sodium such as Na from the alkali supply layer 50 to the photoelectric conversion layer 34 can be favorably and appropriately controlled by the film thickness of the alkali supply layer 50.

Next, the manufacturing method of the thin film solar cell 30 of this embodiment is demonstrated.
First, the substrate 10 formed as described above is prepared.
Next, on the surface 16a of the insulating layer 16 of the substrate 10, as the alkali supply layer 50, for example, a soda lime glass layer having a sodium compound content of 10 to 30% in terms of Na ₂ O is formed using a film forming apparatus. It is formed by RF sputtering.
Next, a molybdenum film to be the back electrode 32 is formed on the surface 50a of the alkali supply layer 50 by, for example, a sputtering method using a film forming apparatus.
Next, the molybdenum film is scribed at a first position using, for example, a laser scribing method to form a separation groove (P1) 33 extending in the width direction of the substrate 10. Thereby, the back surface electrodes 32 separated from each other by the separation groove (P1) 33 are formed.

Next, for example, a CIGS layer that becomes the photoelectric conversion layer 34 (p-type semiconductor layer) is formed by any one of the above-described film formation methods so as to cover the back electrode 32 and fill the separation groove (P1) 33. It forms using a membrane apparatus.
Next, a CdS layer (n-type semiconductor layer) to be the buffer layer 36 is formed on the CIGS layer by, for example, a CBD (chemical bath) method. Thereby, a pn junction semiconductor layer is formed.
Next, a second position different from the first position of the separation groove (P1) 33 is scribed using a laser scribing method, and extends to the back surface electrode 32 extending in the width direction of the substrate 10 (P2). ) 37 is formed.

Next, a ZnO layer to which, for example, Al, B, Ga, Sb or the like to be the transparent electrode 38 is added so as to fill the groove (P2) 37 on the buffer layer 36 is formed using a film formation apparatus. It is formed by sputtering or coating.
Next, a third position different from the first position of the separation groove (P1) 33 and the second position of the groove (P2) 37 is scribed using a laser scribing method, and extends in the width direction of the substrate 10. Further, an opening groove (P3) 39 reaching the back electrode 32 is formed. In this way, a plurality of power generation cells 54 are formed on the laminate of the substrate 10 and the alkali supply layer 50, and the power generation layer 56 is formed.

Next, the respective photoelectric conversion elements 40 formed on the left and right end electrodes 32 in the longitudinal direction L of the substrate 10 are removed by, for example, laser scribing or mechanical scrubbing to expose the back electrode 32. Next, the first conductive member 42 is connected to the back electrode 32 at the right end, and the second conductive member 44 is connected to the back electrode 32 at the left end using, for example, ultrasonic soldering.
Thereby, as shown in FIG. 1, the thin film solar cell 30 in which the some photoelectric conversion element 40 was connected in series can be manufactured.

  Next, a sealing adhesive layer (not shown), a water vapor barrier layer (not shown) and a surface protective layer (not shown) are arranged on the surface side of the obtained thin film solar cell 30, and the back surface of the thin film solar cell 30. A sealing adhesive layer (not shown) and a back sheet (not shown) are arranged on the side, that is, the back side of the substrate 10, and are laminated by, for example, a vacuum laminating method. Thereby, a thin film solar cell module can be obtained.

In this embodiment, by providing the alkali supply layer 50 with a sodium compound content of 10 to 30% in terms of Na ₂ O (7 to 20 at.% In terms of Na), the photoelectric conversion layer 34 (CIGS layer) is provided. The amount of alkali metal supplied can be controlled accurately and with good reproducibility. Thereby, while the conversion efficiency of the photoelectric conversion element 40 can be improved, the photoelectric conversion element 40 can be manufactured with a sufficient yield.

In the present embodiment, as described above, the substrate 10 is combined with the metal substrate 15 in which the metal base 12 and the Al base 14 are laminated and the surface 14a of the Al base 14 of the metal substrate 15. By using the substrate with an insulating layer provided with the insulating layer 16 formed in the above, for example, high insulation and high strength can be maintained even after a film forming process at a temperature of 500 ° C. or higher, and the temperature is 500 ° C. or higher. A manufacturing process at a high temperature is possible. For this reason, a compound semiconductor can be formed as a photoelectric conversion layer at 500 ° C. or higher. Since the compound semiconductor that constitutes the photoelectric conversion layer can be improved in photoelectric conversion characteristics when formed at a high temperature, the photoelectric conversion element 40 having the photoelectric conversion layer 34 with improved photoelectric conversion characteristics can be obtained accordingly. Can be manufactured.
In addition, since the manufacturing process can be performed at a high temperature of 500 ° C. or higher, it is possible to eliminate restrictions on handling during manufacturing.
Thus, since the board | substrate 10 is excellent in heat resistance, the thin film solar cell 30 excellent in durability and a shelf life can be obtained. For this reason, durability and a shelf life are excellent also about a solar cell submodule and a thin film solar cell module.

  Moreover, in this embodiment, the board | substrate 10 is manufactured by a roll-to-roll system, and has flexibility. For this reason, the photoelectric conversion element 40 and the thin film solar cell 30 can also be manufactured by a roll-to-roll method, for example, conveying the board | substrate 10 to the longitudinal direction L. Thus, since the thin film solar cell 30 can be manufactured by an inexpensive roll-to-roll method, the manufacturing cost of the thin film solar cell 30 can be reduced. Thereby, the cost of a solar cell submodule or a thin film solar cell module can be reduced.

Next, a second embodiment of the present invention will be described.
FIG. 3: is typical sectional drawing which shows the thin film solar cell submodule which comprises the thin film solar cell which concerns on the 2nd Embodiment of this invention.
In the present embodiment, the same components as those of the substrate 10 shown in FIG. 2A and the thin film solar cell 30 of the first embodiment shown in FIG. To do.

Compared to the thin-film solar cell 30 of the first embodiment, the thin-film solar cell 30 a of the present embodiment does not have the alkali supply layer 50 formed on the surface 16 a of the insulating layer 16 but the surface of the insulating layer 16. The difference is that the alkali supply layer 50 is formed on the surface 52a of the diffusion prevention layer 52 formed on 16a, and the other configuration is the same as that of the thin film solar cell 30 of the first embodiment.
In the present embodiment, the diffusion preventing layer 52 is formed between the alkali supply layer 50 and the insulating layer 16. In the present embodiment, a single power generation cell 54 and the corresponding parts of the substrate 10, the diffusion prevention layer 52, and the alkali supply layer 50 are referred to as the photoelectric conversion element 40, but are shown in FIG. 3. The thin film solar cell 30a itself may be called a photoelectric conversion element.
Of course, also in this embodiment, the board | substrate 10a shown in FIG.2 (b) may be used.

  The diffusion prevention layer 52 of this embodiment is for preventing the alkali metal contained in the alkali supply layer 50 from diffusing into the substrate 10 and increasing the diffusion amount of the alkali metal into the photoelectric conversion layer 34. .

The diffusion preventing layer 52 can be made of nitride, for example, and is preferably an insulator.
Specifically, the diffusion preventing layer 52, when a ^{nitride, TiN (9.4 × 10 -6 /℃),ZrN(7.2×10} -6 /℃),BN(6.4× it can be used 10 ^-6 /℃),AlN(5.7×10 ^-6 / ℃). Among these, the diffusion preventing layer 52 is preferably a material having a small difference in thermal expansion coefficient from the insulating layer 16 of the substrate 10 and the aluminum anodic oxide film, and therefore, ZrN, BN, and AlN are preferable. Among these, the insulator is BN or AlN, and these are more preferable as the diffusion prevention layer 52. Furthermore, AlN having the smallest difference in thermal expansion coefficient from the aluminum anodic oxide film is most preferable.
Thus, the thermal expansion coefficients of the diffusion prevention layer 52 and the substrate 10 or the photoelectric conversion layer 34 can be made uniform, and as a result, the adhesion between the diffusion prevention layer 52 and the substrate 10 or the photoelectric conversion layer 34 is ensured. Can be improved, and peeling between the substrate 10 and the photoelectric conversion layer 34 can be prevented.
Further, the diffusion preventing layer 52 may be made of an oxide. In this case, as the oxide, TiO ₂ (9.0 × 10 −6 / ° C.), ZrO ₂ (7.6 × 10 ⁻⁶ / ° C.), HfO ₂ (6.5 × 10 ⁻⁶ / ° C.), Al ₂ O ₃ (8.4 × 10 ⁻⁶ / ° C.) can be used. Even when the diffusion preventing layer 52 is made of an oxide, it is preferably an insulator.

  Here, the oxide film contains Na in the film, thereby preventing Na from diffusing into the substrate 10. However, the nitride film hardly contains an alkali metal such as Na in the film, and the nitride film contains It is considered that the diffusion of Na to the photoelectric conversion layer 34 (CIGS layer), which is an upper layer than the alkali supply layer 50, is promoted by preventing the diffusion to the alkali supply layer 50. Therefore, as the diffusion preventing layer 52, the effect of diffusing the alkali metal into the photoelectric conversion layer 34 (CIGS layer) is obtained in the nitride diffusion preventing layer than in the oxide diffusion preventing layer. For this reason, a nitride diffusion prevention layer is more preferred.

It is preferable that the diffusion prevention layer 52 is thicker because the diffusion prevention function to the substrate 10 and the function of increasing the diffusion amount of alkali metal to the photoelectric conversion layer 34 are enhanced. However, when the film thickness is thick, it becomes a starting point of peeling, and thus the diffusion prevention layer 52 preferably has a thickness of 10 nm to 200 nm, more preferably 10 to 100 nm.
As described above, when the diffusion preventing layer 52 is made of an insulator, in addition to the insulating layer 16 of the substrate 10, the insulating property (voltage resistance property) and heat resistance property of the substrate 10 can be further improved. In addition, the photoelectric conversion element 40 and the solar cell 30 having high withstand voltage characteristics can be obtained.

Compared with the thin film solar cell 30 of the first embodiment, the thin film solar cell 30a of the present embodiment has a TiN film and a ZrN film formed on the surface 16a of the insulating layer 16 by, for example, sputtering using a film forming apparatus. The BN film or the AlN film is the same as the manufacturing method of the thin-film solar cell 30 of the first embodiment except that the BN film or the AlN film is formed as the diffusion prevention layer 52, and thus detailed description thereof is omitted.
Also in this embodiment, as shown in FIG. 3, the thin film solar cell 30a in which the some photoelectric conversion element 40 was electrically connected in series can be manufactured.
Next, a sealing adhesive layer (not shown), a water vapor barrier layer (not shown) and a surface protective layer (not shown) are arranged on the surface side of the obtained thin film solar cell 30a, and the back surface of the thin film solar cell 30a. A sealing adhesive layer (not shown) and a back sheet (not shown) are arranged on the side, that is, the back side of the substrate 10, and are laminated by, for example, a vacuum laminating method. Thereby, a thin film solar cell module can be obtained.

In this embodiment, since only the diffusion preventing layer 52 is provided, the same effect as that of the thin film solar cell 30 of the first embodiment can be obtained.
Furthermore, since the diffusion amount of the alkali metal into the photoelectric conversion layer 34 can be increased by providing the diffusion prevention layer 52, the photoelectric conversion element 40 with higher conversion efficiency can be obtained.
Further, by providing the diffusion preventing layer 52, even if the thickness of the alkali supply layer 50 is reduced, the photoelectric conversion element 40 having the same conversion efficiency as that of the first thin film solar cell 30 can be obtained. Thus, since the thickness of the alkali supply layer 50 can be reduced, the alkali supply layer 50 can be formed quickly, and the production rate of the photoelectric conversion element 40 can be increased. Moreover, it can also suppress that the alkali supply layer 50 becomes a starting point of peeling.

  Furthermore, in the present embodiment, the insulating layer 16 is formed, and the insulation (voltage resistance characteristic) of the substrate 10 can be further improved by configuring the diffusion prevention layer 52 with an insulator. Moreover, as described above, the substrate 10 is excellent in heat resistance. Thereby, it can be set as the thin film solar cell 30a whose durability and the shelf life were more excellent. For this reason, durability and a shelf life are further excellent also about a solar cell submodule and a thin film solar cell module.

  The present invention is basically as described above. As mentioned above, although the manufacturing method of the photoelectric conversion element of this invention, the thin film solar cell, and the photoelectric conversion element was demonstrated in detail, this invention is not limited to the said embodiment, In the range which does not deviate from the main point of this invention, it is various improvement. Of course, changes may be made.

Examples of the photoelectric conversion element of the present invention will be specifically described below.
In this example, Examples 1 to 9 and Comparative Example 1 shown below were prepared, and the content of the sodium compound in the photoelectric conversion layer and the conversion efficiency of the photoelectric conversion element were examined.

Example 1
By using a commercially available ferritic stainless steel material (material SUS430) and a high purity aluminum material (hereinafter referred to as Al material) with a purity of 4N, pressure bonding and reducing the thickness by cold rolling method, the ferrite type A three-layer clad material having a stainless steel material thickness of 50 μm and an Al material thickness of 30 μm was formed to obtain a metal substrate. The configuration of this metal substrate is Al material (30 μm) / ferritic stainless steel material (50 μm) / Al material (30 μm).
With respect to this metal substrate, the stainless steel surface and end surface of the metal substrate were covered with a masking film. Then, after ultrasonic cleaning with ethanol, electropolishing with acetic acid + perchloric acid solution, electrolysis with constant voltage of 40 V in an 80 g / L oxalic acid solution, the thickness of the insulating layer is 10 μm. An anodized film was formed on the surface of the Al material. The thickness of the Al material after the anodizing treatment was 15 μm. The substrate with an insulating layer having the structure of anodized film (10 μm) / Al material (15 μm) / ferritic stainless steel material (50 μm) / Al material (15 μm) / anodized film (10 μm) was obtained by the above process.

Next, blue plate glass (SLG) was formed into a thickness of 200 nm by RF sputtering as an alkali supply layer (Na supply source) on one surface of the substrate with an insulating layer. The content of sodium oxide (sodium compound) in this blue plate glass is 10% in terms of Na ₂ O (7 at.% In terms of Na). In Table 2, Na converted values are shown.
On the alkali supply layer, Mo was formed to a thickness of 800 nm as a back electrode by DC sputtering.
Next, as a photoelectric conversion layer (semiconductor layer), on the back electrode, a substrate temperature of 550 ° _C., was deposited _{Cu (In 0.7 Ga 0.3) Se} 2.
Cu (In _0.7 Ga _0.3 ) Se ₂ was formed to a thickness of 2 μm by an evaporation method using a K cell (knudsen-Cell) as an evaporation source.

  Next, a CdS buffer layer was formed on the surface of the photoelectric conversion layer (CIGS layer) by a CBD method (chemical precipitation method) to a thickness of 50 nm. Next, a ZnO layer having a thickness of 50 nm was formed on the surface of the CdS buffer layer by sputtering. Further, an Al—ZnO layer as a transparent electrode layer was formed to a thickness of 300 nm by sputtering. Finally, an Al layer was formed on the surface of the Al—ZnO layer as an extraction electrode by a vapor deposition method. This was designated Example 1.

(Example 2)
Using the same metal substrate with an insulating layer as in Example 1, blue plate glass was formed into a thickness of 200 nm by RF sputtering as an alkali supply layer (Na supply source) on one side of the metal substrate with an insulating layer. The content of sodium oxide in this blue plate glass is 15% in terms of Na ₂ O (10 at.% In terms of Na). In Table 2, Na converted values are shown.
Next, Mo was formed to a thickness of 800 nm on the alkali supply layer as a back electrode by a DC sputtering method. On the back electrode, a photoelectric conversion layer (CIGS layer), a CdS buffer layer, a ZnO layer, an Al—ZnO layer, and an extraction electrode were formed in the same manner as in Example 1 described above. This was designated Example 2.

(Example 3)
Using the same metal substrate with an insulating layer as in Example 1, blue plate glass was formed into a thickness of 200 nm by RF sputtering as an alkali supply layer (Na supply source) on one side of the metal substrate with an insulating layer. The content of sodium oxide in this blue plate glass is 20% in terms of Na ₂ O (14 at.% In terms of Na). In Table 2, Na converted values are shown.
Next, Mo was formed to a thickness of 800 nm on the alkali supply layer as a back electrode by a DC sputtering method. On the back electrode, a photoelectric conversion layer (CIGS layer), a CdS buffer layer, a ZnO layer, an Al—ZnO layer, and an extraction electrode were formed in the same manner as in Example 1 described above. This was designated as Example 3.

Example 4
Using the same metal substrate with an insulating layer as in Example 1, blue plate glass was formed into a thickness of 100 nm by RF sputtering as an alkali supply layer (Na supply source) on one side of the metal substrate with an insulating layer. The content of sodium oxide in this blue plate glass is 20% in terms of Na ₂ O (14 at.% In terms of Na). In Table 2, Na converted values are shown.
Next, Mo was formed to a thickness of 800 nm on the alkali supply layer as a back electrode by a DC sputtering method. On the back electrode, a photoelectric conversion layer (CIGS layer), a CdS buffer layer, a ZnO layer, an Al—ZnO layer, and an extraction electrode were formed in the same manner as in Example 1 described above. This was designated Example 4.

(Example 5)
Using the same metal substrate with an insulating layer as in Example 1, blue plate glass was formed into a thickness of 200 nm by RF sputtering as an alkali supply layer (Na supply source) on one side of the metal substrate with an insulating layer. The content of sodium oxide in this blue plate glass is 20% in terms of Na ₂ O (14 at.% In terms of Na). In Table 2, Na converted values are shown.
Next, Mo was formed on the alkali supply layer as a back electrode to a thickness of 400 nm by DC sputtering. On the back electrode, a photoelectric conversion layer (CIGS layer), a CdS buffer layer, a ZnO layer, an Al—ZnO layer, and an extraction electrode were formed in the same manner as in Example 1 described above. This was designated as Example 5.

(Example 6)
The same metal substrate with an insulating layer as in Example 1 was used, and aluminum nitride (AlN) was formed to a thickness of 100 nm as a diffusion prevention layer on one surface of the metal substrate with an insulating layer by a reactive sputtering method.
Next, as an alkali supply layer (Na supply source), a soda-lime glass was formed to a thickness of 200 nm by RF sputtering on the diffusion prevention layer. The content of sodium oxide in this blue plate glass is 15% in terms of Na ₂ O (10 at.% In terms of Na). In Table 2, Na converted values are shown.
Next, Mo was formed to a thickness of 800 nm on the alkali supply layer as a back electrode by a DC sputtering method. On the back electrode, a photoelectric conversion layer (CIGS layer), a CdS buffer layer, a ZnO layer, an Al—ZnO layer, and an extraction electrode were formed in the same manner as in Example 1 described above. This was designated Example 6.

(Example 7)
The same metal substrate with an insulating layer as in Example 1 was used, and titanium nitride (TiN) was formed as a diffusion prevention layer to a thickness of 100 nm on one surface of the metal substrate with an insulating layer by a reactive sputtering method.
Next, as an alkali supply layer (Na supply source), a soda-lime glass was formed to a thickness of 200 nm by RF sputtering on the diffusion prevention layer. The content of sodium oxide in this blue plate glass is 15% in terms of Na ₂ O (10 at.% In terms of Na). In Table 2, Na converted values are shown.
Next, Mo was formed to a thickness of 800 nm on the alkali supply layer as a back electrode by a DC sputtering method. On the back electrode, a photoelectric conversion layer (CIGS layer), a CdS buffer layer, a ZnO layer, an Al—ZnO layer, and an extraction electrode were formed in the same manner as in Example 1 described above. This was designated as Example 7.

(Example 8)
Using the same metal substrate with an insulating layer as in Example 1, blue plate glass was formed into a thickness of 200 nm by RF sputtering as an alkali supply layer (Na supply source) on one side of the metal substrate with an insulating layer. The content of sodium oxide in this blue plate glass is 25% in terms of Na ₂ O (16 at.% In terms of Na). In Table 2, Na converted values are shown.
Next, Mo was formed to a thickness of 800 nm on the alkali supply layer as a back electrode by a DC sputtering method. On the back electrode, a photoelectric conversion layer (CIGS layer), a CdS buffer layer, a ZnO layer, an Al—ZnO layer, and an extraction electrode were formed in the same manner as in Example 1 described above. This was designated Example 8.

Example 9
Using the same metal substrate with an insulating layer as in Example 1, blue plate glass was formed into a thickness of 200 nm by RF sputtering as an alkali supply layer (Na supply source) on one side of the metal substrate with an insulating layer. The content of sodium oxide in this blue plate glass is 30% in terms of Na ₂ O (20 at.% In terms of Na). In Table 2, Na converted values are shown.
Next, Mo was formed to a thickness of 800 nm on the alkali supply layer as a back electrode by a DC sputtering method. On the back electrode, a photoelectric conversion layer (CIGS layer), a CdS buffer layer, a ZnO layer, an Al—ZnO layer, and an extraction electrode were formed in the same manner as in Example 1 described above. This was designated as Example 9.

(Example 10)
The same metal substrate with an insulating layer as in Example 1 was used, and aluminum oxide (Al ₂ O ₃ ) was formed as a diffusion preventing layer on one surface of the metal substrate with an insulating layer to a thickness of 100 nm by a reactive sputtering method. .
Next, as an alkali supply layer (Na supply source), a soda-lime glass was formed to a thickness of 200 nm by RF sputtering on the diffusion prevention layer. The content of sodium oxide in this blue plate glass is 15% in terms of Na ₂ O (10 at.% In terms of Na). In Table 2, Na converted values are shown.
Next, Mo was formed to a thickness of 800 nm on the alkali supply layer as a back electrode by a DC sputtering method. On the back electrode, a photoelectric conversion layer (CIGS layer), a CdS buffer layer, a ZnO layer, an Al—ZnO layer, and an extraction electrode were formed in the same manner as in Example 1 described above. This was designated Example 10.

(Comparative Example 1)
Using the same metal substrate with an insulating layer as in Example 1, blue plate glass was formed into a thickness of 200 nm by RF sputtering as an alkali supply layer (Na supply source) on one side of the metal substrate with an insulating layer. The content of sodium oxide in this blue plate glass is 5% in terms of Na ₂ O (3 at.% In terms of Na). In Table 2, Na converted values are shown.
Next, Mo was formed to a thickness of 800 nm on the alkali supply layer as a back electrode by a DC sputtering method. On the back electrode, a photoelectric conversion layer (CIGS layer), a CdS buffer layer, a ZnO layer, an Al—ZnO layer, and an extraction electrode were formed in the same manner as in Example 1 described above. This was designated as Comparative Example 1.

  Table 2 below shows the presence or absence of the diffusion prevention layer, the configuration of the diffusion prevention layer, the configuration of the alkali supply layer, and the configuration of the back electrode for the photoelectric conversion elements of Examples 1 to 9 and Comparative Example 1.

In the present Example, about the photoelectric conversion element of Examples 1-9 and the comparative example 1, Na density | concentration (alkali content) of a photoelectric converting layer (CIGS layer) was measured.
The Na concentration was measured using SIMS (secondary ion mass spectrometer), the primary ion species for measurement was O ₂ ⁺ , and the acceleration voltage was 6.0 kV. The Na concentration in the photoelectric conversion layer (CIGS layer) has a distribution in the thickness direction but is integrated to derive an average value, and this average value was used for evaluating the Na concentration. The results are shown in Table 2 below.

Moreover, photoelectric conversion efficiency was evaluated about the photoelectric conversion element of Examples 1-9 and the comparative example 1. FIG.
About the produced photoelectric conversion element, photoelectric conversion efficiency was evaluated using the artificial sunlight of Air Mass (AM) = 1.5 and 100 mW / cm < ² >.
About the photoelectric conversion elements of Examples 1 to 9 and Comparative Example 1, 8 samples were produced. For each photoelectric conversion element of each of Examples 1 to 9 and Comparative Example 1, the photoelectric conversion efficiency was measured under the above conditions, and a sample of the photoelectric conversion element that had a photoelectric conversion efficiency of 80% or more with respect to the highest value among them. Was regarded as an acceptable product, and other products were regarded as unacceptable products. The average value of the accepted products was defined as the conversion efficiency of the photoelectric conversion elements of Examples 1 to 9 and Comparative Example 1. The results are shown in Table 2 below.

As shown in Table 2 above, when Examples 1 to 3 are compared with Comparative Example 1, when the thickness of the alkali supply layer is the same, the Na concentration contained in the alkali supply layer is higher in the CIGS layer. Becomes higher. In addition, conversion efficiency is improved accordingly.
Further, when Example 3 and Example 4 are compared, when the Na concentration contained in the alkali supply layer is the same, the thicker the alkali supply layer, the higher the concentration of Na in the CIGS layer, that is, in the CIGS layer The amount of Na contained increases.
Further, when Example 3 and Example 5 are compared, when the Na concentration contained in the alkali supply layer is the same as the thickness of the alkali supply layer, Na diffuses into CIGS when the Mo film as the back electrode is thinner. The concentration of Na in the CIGS layer increases, that is, the amount of Na contained in the CIGS layer increases.

Further, when Example 2, Example 6, and Example 7 are compared, the concentration of Na in the CIGS layer increases when the diffusion prevention layer exists, that is, the amount of Na contained in the CIGS layer increases. Further, from the comparison between Example 6 and Example 7, there is no great difference in the effect of the diffusion preventing layer as long as it is a nitride diffusion preventing layer. If a diffusion prevention layer exists from here, even if the Na concentration in the alkali supply layer (SLG layer) is low or the thickness of the alkali supply layer is small, a large amount of Na is supplied into the CIGS layer. be able to.
Further, comparing Example 6, Example 7, and Example 10, the diffusion prevention layer can supply more Na into the CIGS layer than the oxide, and the conversion is accompanied by the conversion. Efficiency is improved.
In Examples 8 and 9, since the thickness of the alkali supply layer (SLG layer) is as thick as 200 nm, the content of sodium oxide is 16 at. % At 20 at. % (25% or 30% in terms of Na ₂ O) provides a sufficient amount of Na to the CIGS layer. For this reason, although conversion efficiency improves rather than other Na density | concentrations, content of sodium oxide is 16 at. If it is% (25% in terms of Na ₂ O) or more, it does not contribute to the improvement of efficiency.

Examples of the photoelectric conversion element of the present invention will be specifically described below.
In this example, Examples 11 to 38 and Comparative Examples 10 to 14 shown below were prepared, and the content of the sodium compound in the photoelectric conversion layer and the conversion efficiency of the photoelectric conversion element were examined. In addition to Examples 11 to 38 and Comparative Examples 10 to 14, those disclosed in Non-Patent Document 1 were used as Comparative Examples 15 to 19 for comparison.

(Example 11)
Using a commercially available ferritic stainless steel material (material: SUS430) 12 and a high-purity aluminum material (hereinafter referred to as Al material) 14 having an aluminum purity of 4N, press bonding and reducing the thickness by cold rolling. As a result, a three-layer clad material having a ferritic stainless steel material thickness of 100 μm and an Al material thickness of 30 μm was formed, and a metal substrate 15 was obtained. The configuration of the metal substrate 15 is Al material (30 μm) / ferritic stainless steel material (100 μm) / Al material (30 μm).

  The metal substrate 15 was covered with a masking film on the stainless steel surface and the end surface of the metal substrate 15. Thereafter, ultrasonic cleaning is performed using ethanol, and electropolishing is performed using an acetic acid + perchloric acid solution, followed by constant voltage electrolysis in a 1M malonic acid solution at a voltage of 80 V and a temperature of 80 ° C. An anodic oxide film having a thickness of 10 μm was formed on the surface of the Al material 14. The thickness of the Al material 14 after the anodizing treatment was 15 μm. The substrate 10 with an insulating layer having a structure of anodized film (10 μm) / Al material (15 μm) / ferritic stainless steel material (100 μm) / Al material (15 μm) / anodized film (10 μm) was obtained by the above steps.

Next, as an alkali supply layer 50 (Na supply source) on one side of the substrate with an insulating layer, blue plate glass (SLG) is formed to a thickness of 50 nm by RF sputtering, and a blue plate glass layer (hereinafter referred to as SLG layer). Got. The content of sodium oxide (sodium compound) in this SLG layer is 10% in terms of Na ₂ O (7 at.% In terms of Na).
Further, a Mo film having a thickness of 400 nm was formed as a back electrode 32 on the alkali supply layer 50 by DC sputtering.

Next, using a vapor deposition method using a K cell as a vapor deposition source, the substrate temperature is set to 520 ° C., and Cu (In 0.7 Ga 0.3) Se ₂ is formed as a photoelectric conversion layer 34 on the back electrode 32 to a thickness of 2 μm. Formed.
Next, a CdS buffer layer 36 was formed on the surface of the photoelectric conversion layer 34 to a thickness of 50 nm by the CBD method. Next, an Al—ZnO layer as a transparent electrode layer 38 was formed on the CdS buffer layer 36 to a thickness of 200 nm by sputtering. Finally, an Al layer (first and second conductive members 42 and 44) was formed as an extraction electrode on the surface of the Al—ZnO layer, which is the transparent electrode layer 38, to obtain a photoelectric conversion element. The photoelectric conversion element thus obtained was referred to as Example 11.

In this embodiment, as the alkali supply layer, an SLG layer is used, an RF power source is used, a soda lime glass target having a target size of 8 inches in diameter, a power density of 2 W / cm ² , and a deposition pressure of 1. The film was formed under film forming conditions of ₂ Pa (Ar + O ₂ atmosphere). In this case, the film formation rate was 4 nm / min.
On the other hand, the Mo film formed as the back electrode 32 is formed by using a pulsed DC power source with a target size of 8 inches in diameter, a power density of 7 W / cm ² and a film forming pressure of 0.5 Pa (Ar atmosphere). In this case, the film formation rate is 300 nm / min. The SLG layer formed as the alkali supply layer had a film formation rate of about 1/75 of that of the Mo film.

(Example 12 to Example 15)
Examples 12 to 15 have the same configuration as that of Example 11 described above except that the thickness of the SLG layer (alkali supply layer) is different from that of Example 11.
Example 12 has an SLG layer thickness of 100 nm, Example 13 has an SLG layer thickness of 150 nm, Example 14 has an SLG layer thickness of 200 nm, and Example 15 has an The thickness of the SLG layer is 250 nm.

(Example 16 to Example 20)
Example 16 is the same as Example 11 except that the content of sodium oxide in the alkali supply layer is 15% in terms of Na ₂ O (10 at.% In terms of Na) compared to Example 11. It is the same composition.
In Examples 17 to 20, the content of sodium oxide in the alkali supply layer is 15% in terms of Na ₂ O (10 at.% In terms of Na), and the thickness of the SLG layer (alkali supply layer) is different. Except for this point, the configuration is the same as that of Example 11 described above.
Example 17 has an SLG layer thickness of 100 nm, Example 18 has an SLG layer thickness of 150 nm, Example 19 has an SLG layer thickness of 200 nm, and Example 20 has an The thickness of the SLG layer is 250 nm.

(Examples 21 to 23)
In Example 21, as compared with Example 11, aluminum nitride (AlN) was formed to a thickness of 100 nm as a diffusion preventing layer on one side of the metal substrate with an insulating layer by a reactive sputtering method. On top, the SLG layer (alkali supply layer) having a thickness of 200 nm is formed, and the content of sodium oxide in the alkali supply layer is 15% in terms of Na ₂ O (10 at.% In terms of Na). Except for certain points, the configuration is the same as that of Example 11 described above.
In Example 22, as compared with Example 11, titanium nitride (TiN) was formed into a thickness of 100 nm as a diffusion preventing layer on one side of the metal substrate with an insulating layer by a reactive sputtering method. On top, the SLG layer (alkali supply layer) having a thickness of 200 nm is formed, and the content of sodium oxide in the alkali supply layer is 15% in terms of Na ₂ O (10 at.% In terms of Na). Except for certain points, the configuration is the same as that of Example 11 described above.
In Example 23, as compared with Example 11, aluminum oxide (Al ₂ O ₃ ) was formed to a thickness of 100 nm as a diffusion prevention layer on one side of a metal substrate with an insulating layer by a reactive sputtering method. The SLG layer (alkali supply layer) having a thickness of 200 nm is formed on the diffusion prevention layer, and the content of sodium oxide in the alkali supply layer is 15% in terms of Na ₂ O (10 at. %), The configuration is the same as that of Example 11 described above.

(Examples 24-28)
Example 24 is the same as Example 11 except that the content of sodium oxide in the SLG layer (alkali supply layer) is 20% in terms of Na ₂ O (14 at.% In terms of Na). The configuration is the same as in Example 11.
In Examples 25 to 28, compared to Example 11, the content of sodium oxide in the SLG layer (alkali supply layer) is 20% in terms of Na ₂ O (14 at.% In terms of Na), and The configuration is the same as that of Example 11 described above except that the thickness of the SLG layer (alkali supply layer) is different.
Example 25 has an SLG layer thickness of 100 nm, Example 26 has an SLG layer thickness of 150 nm, Example 27 has an SLG layer thickness of 200 nm, and Example 28 has an The thickness of the SLG layer is 250 nm.

(Examples 29 to 33)
Example 29 is similar to Example 11 except that the content of sodium oxide in the alkali supply layer is 25% in terms of Na ₂ O (16 at.% In terms of Na), compared to Example 11. It is the same composition.
In Examples 30 to 33, compared to Example 11, the content of sodium oxide in the alkali supply layer was 25% in terms of Na ₂ O (16 at.% In terms of Na), and the SLG layer (alkaline The configuration is the same as that of Example 11 except that the thickness of the supply layer is different.
Example 30 has an SLG layer thickness of 100 nm, Example 31 has an SLG layer thickness of 150 nm, Example 32 has an SLG layer thickness of 200 nm, and Example 33 has an The thickness of the SLG layer is 250 nm.

(Examples 34 to 38)
Example 34 is the same as Example 11 except that the content of sodium oxide in the SLG layer (alkali supply layer) is 30% in terms of Na ₂ O (20 at.% In terms of Na). The configuration is the same as in Example 11.
In Examples 35 to 38, the content of sodium oxide in the SLG layer (alkali supply layer) is 30% in terms of Na ₂ O (20 at.% In terms of Na) as compared to Example 11, and The configuration is the same as that of Example 11 except that the thickness of the alkali supply layer is different.
Example 35 has an SLG layer thickness of 100 nm, Example 36 has an SLG layer thickness of 150 nm, Example 37 has an SLG layer thickness of 200 nm, and Example 38 has an The thickness of the SLG layer is 250 nm.

(Comparative Example 10 to Comparative Example 14)
Comparative Example 10 is the same as Example 11 except that the content of sodium oxide in the SLG layer (alkali supply layer) is 5% in Na ₂ O conversion (3 at.% In Na conversion). The configuration is the same as in Example 11.
In Comparative Examples 11 to 14, the sodium oxide content of the SLG layer (alkali supply layer) is 5% in terms of Na ₂ O (3 at.% In terms of Na) as compared to Example 11, and The configuration is the same as that of Example 11 described above except that the thickness of the SLG layer (alkali supply layer) is different.
Comparative Example 11 has an SLG layer thickness of 100 nm, Comparative Example 12 has an SLG layer thickness of 150 nm, Comparative Example 13 has an SLG layer thickness of 200 nm, and Comparative Example 14 has The thickness of the SLG layer is 250 nm.

(Comparative Examples 15-19)
Comparative Examples 15 to 19 are disclosed in Non-Patent Document 1. In order to clarify that it is disclosed in Non-Patent Document 1, “* Document” is written in the remarks column of Comparative Examples 15 to 19 in Table 3 below.
In Comparative Example 15, a Ti foil substrate having a thickness of 20 μm was used, and Mo was formed as a back electrode on the Ti foil substrate to a thickness of 800 nm by sputtering. On the back electrode, Cu (In, Ga) Se ₂ is formed as the photoelectric conversion layer 34 using a three-stage method. The deposition temperature of Cu (In, Ga) Se ₂ is 350 ° C. in the first stage, and 550 ° C. in the second stage and the third stage.

Comparative Example 16 has the same configuration as Comparative Example 15 except that an SLG layer having a thickness of 50 nm is formed as an alkali supply layer on the Ti foil substrate as compared with Comparative Example 15. .
Comparative Example 17 has the same configuration as Comparative Example 15 described above except that an SLG layer having a thickness of 120 nm is formed on the Ti foil substrate as compared with Comparative Example 15.
Comparative Example 18 has the same configuration as Comparative Example 15 described above except that an SLG layer having a thickness of 150 nm is formed on the Ti foil substrate as compared with Comparative Example 15.
Comparative Example 19 has the same configuration as Comparative Example 15 described above except that an SLG layer having a thickness of 230 nm is formed on the Ti foil substrate as compared with Comparative Example 15.

  Table 3 below shows the presence or absence of the diffusion prevention layer, the configuration of the diffusion prevention layer, the configuration of the alkali supply layer, and the configuration of the back electrode for the photoelectric conversion elements of Examples 11 to 38 and Comparative Examples 10 to 19. In Table 3, the content of sodium oxide is expressed in terms of Na.

In this example, the Na concentration (alkali content) of the photoelectric conversion layer (CIGS layer) was measured for the photoelectric conversion elements of Examples 11 to 38 and Comparative Examples 10 to 14.
The Na concentration was measured using SIMS (secondary ion mass spectrometer), the primary ion species for measurement was O ₂ ⁺ , and the acceleration voltage was 6.0 kV. The Na concentration in the photoelectric conversion layer (CIGS layer) has a distribution in the thickness direction but is integrated to derive an average value, and this average value was used for evaluating the Na concentration. The results are shown in Table 3 below.

Moreover, the photoelectric conversion efficiency was evaluated about the photoelectric conversion element of Examples 11-38 and Comparative Examples 10-14. About the produced photoelectric conversion element, photoelectric conversion efficiency was evaluated using the artificial sunlight of Air Mass (AM) = 1.5 and 100 mW / cm < ² >.
For each of the photoelectric conversion elements of Examples 11 to 38 and Comparative Examples 10 to 14, eight samples were produced. For each of the photoelectric conversion elements of Examples 11 to 38 and Comparative Examples 10 to 14, the photoelectric conversion efficiency was measured under the above conditions, and the photoelectric conversion element had a photoelectric conversion efficiency of 80% or more with respect to the highest value among them. These samples were regarded as acceptable products, and other samples were regarded as unacceptable products. The average value of the accepted products was defined as the conversion efficiency of the photoelectric conversion elements of Examples 11 to 38 and Comparative Examples 10 to 14. The results are shown in Table 3 below. Of Examples 11 to 38 and Comparative Examples 10 to 14, the results other than Examples 21 to 23 are shown in FIG.
In addition, about the sample which produced the 8 photoelectric conversion elements, more than half are unacceptable goods, the * mark was attached | subjected to Table 3 below.

In Comparative Examples 15 to 19, as shown in Non-Patent Document 1, the photoelectric conversion efficiency is measured under the conditions of Air Mass (AM) = 1.5 and 100 mW / cm ² . The results of Comparative Examples 20 to 25 are also shown in Table 3 below and FIG.

In FIG. 4, α ₁ is a plot of Examples 11 to 15, α ₂ is a plot of Examples 16 to 20, and α ₃ is a plot of Examples 24 to 28. Yes, α ₄ is a plot of Examples 29 to 33, α ₅ is a plot of Examples 34 to 38, α ₆ is a plot of Comparative Examples 10 to 14, and α ₇ is It plots Comparative Examples 15-19.

In Examples 11 to 38 and Comparative Examples 10 to 14 shown in Table 3 above, those having a small amount of Na in the CIGS layer and having a conversion efficiency of around 10% are not very different in performance, and the conversion efficiency is around 10%. The variation is included in the error range.
As shown in Table 3 above, when Examples 11 to 38 and Comparative Examples 10 to 14 are compared, when the thickness of the alkali supply layer is the same, the higher the Na concentration contained in the alkali supply layer, the CIGS layer The Na concentration tends to increase, and the conversion efficiency improves as the Na concentration increases.
In addition, a group of Examples 11 to 15 (α _{1 in} FIG. 4), a group of Examples 16 to 20 (α _{2 in} FIG. 4), and a group of Examples 24 to 28 (FIG. 4) having the same Na concentration in the alkali supply layer. 4 is α ₃ ), a group of Examples 29 to 33 (α _{4 in} FIG. 4), and a group of Examples 34 to 38 (α _{5 in} FIG. 4), the Na concentration in the alkali supply layer is the same. The thicker the alkali supply layer, the higher the concentration of Na in the CIGS layer.
As shown in Table 3 and FIG. 4, in Examples 11 to 38 (α _{1 to} α ₅ ), the effect of improving the conversion efficiency is not seen without the Na supply layer having a certain thickness.
Further, the substrates with an insulating layer (anodized substrates) of Examples 11 to 38 (α _{1 to} α ₅ ) require a larger amount of alkali than the substrates of Comparative Examples 15 to 19 (α ₇ ), or the CIGS layer side It tends to be difficult to diffuse.

  However, the Na concentration in the alkali supply layer is 16 at. % (Na conversion) and Examples 32 and 33 having an alkali supply layer of 200 nm or more, and the Na concentration in the alkali supply layer was 20 at. % (Na conversion) and the alkali supply layer has a thickness of 100 nm or more, and the Na concentration of the alkali supply layer is increased as in Examples 35 to 38. It is considered that the element abnormality increases due to peeling or cracking.

Further, when Examples 21 to 23 having the same alkali supply layer and having a diffusion preventing layer are compared with Example 19 having no diffusion preventing layer, Examples 21 to 23 having the diffusion preventing layer are compared. However, more Na can be supplied into the CIGS layer, and the conversion efficiency is improved accordingly.
Therefore, if there is a diffusion prevention layer, even if the Na concentration in the alkali supply layer is low, even if the thickness of the alkali supply layer is thin, a large amount of Na can be supplied into the CIGS layer, and the conversion efficiency It is clear that the alkali supply layer for improvement can be thinned. As described above, since the alkali supply layer having a low film formation rate can be thinned, productivity can be improved. Furthermore, the diffusion prevention layer suppresses the diffusion of the alkali element toward the substrate with the insulating layer, so that the film alteration due to the reaction between the alkali element and the anodic oxide film can be suppressed, and as a result, the substrate with the insulating layer peels off due to the film alteration. Can also be suppressed.
In Examples 21 to 23, Examples 21 and 22 in which the diffusion preventing layer is a nitride are not much different as the effects of the diffusion preventing layer, but Examples 21 and 22 are more diffused. More Na can be supplied into the CIGS layer than in Example 23 where the prevention layer is an oxide.

10 Substrate 12 Metal base 14 Aluminum base (Al base)
DESCRIPTION OF SYMBOLS 16 Insulating layer 30 Thin film solar cell 32 Back surface electrode 34 Photoelectric conversion layer 36 Buffer layer 38 Transparent electrode 40 Photoelectric conversion element 42 1st electroconductive member 44 2nd electroconductive member 50 Alkali supply layer 52 Diffusion prevention layer

Claims (29)

A substrate with an insulating layer comprising a metal substrate and an electrically insulating layer formed on the surface of the metal substrate;
An alkali supply layer formed on the electrical insulating layer;
A lower electrode formed on the alkali supply layer;
A photoelectric conversion layer formed on the lower electrode and composed of a compound semiconductor layer;
An upper electrode formed on the photoelectric conversion layer,
The alkali supply layer is a compound containing silicon oxide as a main component and containing a sodium compound, and the content of the sodium compound is 7 to 20 at. % Of a photoelectric conversion element.   The photoelectric conversion element according to claim 1, wherein the compound semiconductor is at least one compound semiconductor having a chalcopyrite structure.   The photoelectric conversion device according to claim 2, wherein the compound semiconductor is at least one compound semiconductor composed of a group Ib element, a group IIIb element, and a group VIb element. The Ib group element is at least one selected from the group consisting of Cu and Ag,
The IIIb group element is at least one selected from the group consisting of Al, Ga and In,
The photoelectric conversion element according to claim 3, wherein the group VIb element is at least one selected from the group consisting of S, Se, and Te. The photoelectric conversion layer according to any one of claims 1 to 4, wherein the photoelectric conversion layer is divided into a plurality of elements by a plurality of open grooves, and the plurality of elements are electrically connected in series. Conversion element.   The said alkali supply layer is a photoelectric conversion element of any one of Claims 1-5 comprised by the silicate glass containing a sodium compound.   The photoelectric conversion element according to claim 1, wherein the alkali supply layer is a layer formed by a sputtering method.   The photoelectric conversion element according to claim 1, wherein the alkali supply layer has a thickness of 50 nm to 200 nm.   The photoelectric conversion element according to claim 1, wherein the lower electrode is made of Mo and has a thickness of 200 nm to 600 nm.   The photoelectric conversion element according to claim 9, wherein the lower electrode has a thickness of 200 nm to 400 nm.   The photoelectric conversion element according to any one of claims 1 to 10, further comprising a diffusion prevention layer that prevents at least diffusion of alkali metal into the substrate with an insulating layer between the alkali supply layer and the electrical insulating layer. .   The photoelectric conversion element according to claim 11, wherein the diffusion prevention layer is a nitride.   The photoelectric conversion element according to claim 12, wherein the nitride is an insulator.   The photoelectric conversion element according to claim 12 or 13, wherein the nitride is composed of TiN, ZrN, BN, or AlN.   The photoelectric conversion element according to claim 14, wherein the nitride is AlN.   The photoelectric conversion element according to claim 11, wherein the diffusion prevention layer has a thickness of 10 nm to 200 nm.   The photoelectric conversion element according to claim 16, wherein the diffusion preventing layer has a thickness of 10 nm to 100 nm.   The photoelectric conversion element according to claim 1, wherein the metal substrate is a laminated plate in which a metal base material and an Al base material are laminated and integrated.   The photoelectric conversion element according to claim 18, wherein the metal substrate is a laminated plate in which a metal base and an Al base are integrated by pressure bonding.   The photoelectric conversion element according to claim 19, wherein the metal substrate is a steel material, an alloy steel material, a Ti foil, or a two-layer substrate of a Ti foil and a steel material.   The photoelectric conversion element according to claim 20, wherein the alloy steel material is made of carbon steel or ferritic stainless steel.   The photoelectric conversion element according to claim 1, wherein the electrical insulating layer is an anodized film of aluminum. The photoelectric conversion element according to any one of claims 18 to 22, wherein a difference in coefficient of linear thermal expansion between the metal substrate and the photoelectric conversion layer is less than 3 x ^10-6 / ° C. 24. The photoelectric conversion element according to claim 23, wherein a difference in coefficient of linear thermal expansion between the metal substrate and the photoelectric conversion layer is less than 1 × 10 ⁻⁶ / ° C.   The metal substrate is made of a laminated plate in which an alloy steel material made of carbon steel or ferritic stainless steel and an Al base material are integrated by pressure bonding, and the lower electrode is made of Mo, The photoelectric conversion element according to any one of claims 1 to 24, wherein the photoelectric conversion layer is a layer mainly comprising at least one compound semiconductor composed of a group Ib element, a group IIIb element, and a group VIb element.   The photoelectric conversion element according to any one of claims 1 to 25, wherein the anodic oxide film has a porous structure.   A thin film solar cell comprising the photoelectric conversion element according to claim 1. Forming an electrical insulating layer on the surface of the metal substrate to obtain a substrate with an insulating layer;
On the electrical insulating layer, a compound containing silicon oxide as a main component and containing a sodium compound, and the content of the sodium compound is 7 to 20 at. % Forming an alkali supply layer;
Forming a lower electrode on the alkali supply layer;
Forming a photoelectric conversion layer on the lower electrode;
And a step of forming an upper electrode on the photoelectric conversion layer. The metal substrate is a laminated plate in which a metal substrate and an Al substrate are laminated and integrated,
The method for producing a photoelectric conversion element according to claim 28, wherein the step of obtaining the substrate with an insulating layer is a step of anodizing the Al base material to form an anodized film on the surface of the Al base material.