Method for manufacturing solar cells and solar cells

Abstract

To provide a method for manufacturing a solar battery which attains a high performance and a high productivity, and a method for manufacturing the solar battery.SOLUTION: The method for manufacturing a solar battery includes forming an n-type oxide semiconductor by a sputtering technique while supplying gas including a hydrogen source and an oxygen source, thereby forming an electronic transfer layer on a base material including a light adsorption layer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to a method for manufacturing a solar cell and to a solar cell. [Background technology]

[0002] One type of solar cell is made of chalcopyrite compounds, kestelite compounds, or perovsky Compound solar cells exist that use compounds such as t-compounds. Compound solar cells have a p-type light-absorbing layer. It has a structure in which a different n-type material is stacked as an electron transport layer. Cadmium sulfide is used in it.

[0003] In Non-Patent Documents 1 and 2, zinc oxide is used instead of cadmium sulfide as the electron transport layer. , tin oxide, titanium oxide, zinc sulfide oxide, magnesium zinc oxide, tin zinc oxide, and acid The use of n-type oxide semiconductors such as titanium dioxide zinc is being considered. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] EB Yousfi et al., Cadmium-free buffer layers deposited by atomic later epitaxy for copper indium diselenide solar cells, Thin Solid Films, 361-362, 183-186 (2000) [Non-Patent Document 2] Soumyadeep Sinha et al., A review on atomic layer deposited buffer layers for Cu(In,Ga)Se2 (CIGS) thin film solar cells: Past, present, and future, Solar Energy, 209, 515-537 (2020) [Overview of the project] [Problems that the invention aims to solve]

[0005] However, if an n-type oxide semiconductor is used instead of cadmium sulfide as the electron transport layer Compared to solar cells using cadmium sulfide, they tend to have higher resistance and inferior performance. There is a tendency for this to happen. Also, when depositing n-type oxide semiconductors as electron transport layers, the mass production efficiency is excellent. Using the puttering method makes it difficult to improve performance, while atomic layer deposition (APL) can be used to manufacture high-performance solar cells. Using the layer method makes it difficult to improve productivity.

[0006] This invention has been made in view of the above problems, and achieves both high performance and high productivity in solar energy. The objective is to provide a method for manufacturing batteries and a solar cell. [Means for solving the problem]

[0007] A method for manufacturing a solar cell according to one embodiment of the present invention involves supplying a gas containing an oxygen source and a hydrogen source. By depositing an n-type oxide semiconductor film using the sputtering method while supplying a light-absorbing layer, The process includes forming an electron transport layer on a substrate.

[0008] The inventors have found that when an n-type oxide semiconductor is deposited using the sputtering method, the solar cell One of the factors that degrades performance is the deposition of film dust on the surface of the substrate to which the n-type oxide semiconductor film is deposited. It was found that damage occurs. The method for manufacturing a solar cell according to one embodiment of the present invention is acid By depositing an n-type oxide semiconductor film while supplying a gas containing not only an elementary source but also a hydrogen source, This reduces or suppresses damage to the substrate caused by sputtering. As a result, production It is possible to manufacture highly efficient and high-performance solar cells.

[0009] A solar cell according to one embodiment of the present invention comprises a first electrode layer, a light-absorbing layer, and a hydrogen element added An electron transport layer which is an n-type oxide semiconductor and a second electrode layer are provided in this order, at least El.

[0010] In solar cells, the electron transport layer is made of an n-type oxide semiconductor doped with hydrogen. Sputtering is performed while reducing or suppressing the film deposition damage to the layer beneath the electron transport layer. This allows for the formation of an electron transport layer. As a result, such a solar cell has high performance and high energy efficiency. It is possible to achieve both productivity and productivity. [Effects of the Invention]

[0011] According to the present invention, a method for manufacturing a solar cell that achieves both high performance and high productivity, and a solar cell are provided. It can be provided. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic cross-sectional view of a solar cell according to one embodiment of the present invention. [Figure 2] This is a schematic cross-sectional view of a solar cell according to another embodiment of the present invention. [Figure 3] This figure shows the relationship between atmospheric conditions in the n-type oxide semiconductor film deposition process and film deposition damage caused by sputtering. [Modes for carrying out the invention]

[0013] Hereinafter, with reference to the drawings as necessary, embodiments of the present invention (hereinafter referred to as "this embodiment") will be described. The present invention will be described in detail, but is not limited thereto. Various modifications are possible within the limits of not exceeding the specified dimensions. Note that identical elements are denoted by the same reference numeral in the drawings. We will omit redundant explanations. Furthermore, we will not specify the relative positions such as top, bottom, left, or right. As far as is concerned, the positional relationships shown in the drawings shall be as indicated. Furthermore, the dimensional ratios in the drawings shall be as shown in the illustrations. It's not limited.

[0014] [Solar cell] The solar cell according to this embodiment comprises a first electrode layer, a light-absorbing layer, and an n-type solar cell with added hydrogen element. The device comprises, in this order, at least an electron transport layer made of an oxide semiconductor and a second electrode layer. The battery may have layers other than these layers, or it may have multiple layers of these layers. .

[0015] Figure 1 shows a schematic cross-sectional view of a solar cell according to one embodiment. Pond 100 consists of a substrate 107, a first electrode layer 101 provided on the substrate 107, and the first electrode layer A hole transport layer 102 provided on 101, and a light absorption layer 1 provided on the hole transport layer 102 03, an electron transport layer 104 provided on the light absorption layer 103, and provided on the electron transport layer 104 It comprises a second electrode layer 105 and a grid electrode 106 provided on the second electrode layer 105. The solar cell 100 typically generates electricity by receiving light from the second electrode layer 105 side. .

[0016] The solar cell 100 of this embodiment has an electron transport layer 104 which is an n-type oxide with added hydrogen element. It is a material semiconductor. Therefore, as detailed in [Method for Manufacturing Solar Cells], it absorbs light. Damage to the light absorption layer 103 when depositing the electron transport layer 104 on layer 103. The electron transport layer 104 can be formed by sputtering while mitigating or suppressing the process. It is presumed that such solar cells can achieve both high performance and high productivity. However, the present invention is not limited by the above inference.

[0017] The thickness of the solar cell 100 excluding the substrate 107 is not particularly limited, but for example, 1.0 μm m or more and 10.0 μm or less, 1.1 μm or more and 8.0 μm or less, and 1.2 μm or more. It is 6.0 μm or less. The solar cell 100 of this embodiment is formed with each layer sufficiently thin. This allows for the construction of a thin-film solar cell.

[0018] The following provides a detailed explanation of each possible configuration included in solar cell 100.

[0019] In this specification, each layer, or the semiconductor contained in each layer, is referred to by the name of a certain compound. If this occurs, not only the pure compound itself, but also to the extent that the properties of the compound are not lost, This also includes compounds that have been doped with trace amounts of elements, etc.

[0020] Furthermore, in this embodiment, the elements in each layer of the solar cell exist in different oxidation states. To obtain, all oxidation states are referred to by the name of the element unless otherwise specifically stated. For example, "hydrogen element" can refer to hydrogen atoms, hydrogen ions, hydride ions, and compounds in various states. This can refer to hydrogen, or hydrogen in its elemental state.

[0021] (substrate) The substrate 107 is not particularly limited, but for example, blue glass, low alkali glass, etc. Glass substrates, stainless steel plates, aluminum foil and other metal substrates, polyimide resin substrates, epoxy resin A resin substrate such as a circuit board can be used. The thickness of the substrate 107 is not particularly limited, but for example... For example, 10 μm to 500 μm, 20 μm to 250 μm, and 30 μm The thickness is between m and 100 μm. Because the thickness of the substrate 107 is within the above range, solar power There is a trend towards making ponds lighter and more flexible.

[0022] (1st electrode layer) The first electrode layer 101 extracts, for example, the current generated by holes in the light absorption layer 103, which will be described later. It is provided for this purpose. The first electrode layer 101 is not particularly limited as long as it is conductive. However, this does not apply to metal conductive layers made of metals such as Mo, Cr, or Ti; other materials. A conductive inorganic compound conductive layer made of a conductive inorganic compound; a conductive organic compound made of a conductive organic compound A conductive organic compound conductive layer can be used. The thickness of the first electrode layer 101 is not particularly limited. However, for example, 200nm to 800nm, or 300nm to 700nm Below. Because the thickness of the first electrode layer 101 is within the above range, the current is sufficiently transmitted without loss. While extracting the solar cells, there is a trend towards making solar cells lighter and more flexible.

[0023] (Hole transport layer) The solar cell 100 of this embodiment includes a hole transport layer 102, but this may be omitted. The transport layer 102 efficiently removes holes generated in the light absorption layer 103, for example, from the light absorption layer 103. The electrons and holes generated simultaneously in the light-absorbing layer 103 described later are recombined. It has the function of preventing [something]. The hole transport layer 102 is preferably a p-type semiconductor. The material contained in the conductor is not particularly limited, but for example, poly(3,4-ethylene- Dioxythiophene: Polystyrene sulfonate (PEDOT:PSS), poly(3 -Hexylthiophene) (P3HT), and poly(3-octylthiophene) (P3OT ) and other polythiophene derivatives; 2,2'-7,7'-tetrakis-(N,N-di-p-methyl Toxyphenylamine)-9,9'-spirobifluorene (spiro-MeO-TAD Fluorene derivatives such as polyvinylcarbazole; carbazole derivatives such as polyvinylcarbazole; triphenic acid Diphenylamine derivatives; diphenylamine derivatives; polysilane derivatives; polyaniline derivatives, etc. Organic compounds, as well as nickel oxide, molybdenum oxide, copper gallium oxide, aluminum oxide Examples include inorganic compounds such as copper, molybdenum selenide, and molybdenum selenide sulfide. The p-type semiconductor in the hole transport layer 102 may be used alone, or two or more types may be used in combination. That's good too.

[0024] The hole transport layer 102 is preferably substantially composed of the aforementioned organic or inorganic compounds. It is preferable that the hole transport layer 102 is an organic compound or an inorganic compound as described above. The content of the aforementioned organic or inorganic compounds in the hole transport layer 102 is, Preferably, it is 80% by mass or more and 100% by mass or less, and 90% by mass or more and 100% by mass or less. It is between 95% by mass and 100% by mass, and between 99% by mass and 100% by mass. ru.

[0025] The thickness of the hole transport layer 102 is preferably 10 nm to 100 nm, and 15 nm. The thickness of the hole transport layer 102 is between m and 80 nm, and between 20 nm and 60 nm. Because it is within the above range, the holes generated in the light absorption layer 103 described later are removed from the light absorption layer 103. They are efficiently extracted, and the electrons and holes generated simultaneously with the holes in the light absorption layer 103 described later are recombined. While possessing functions to prevent this, there is a trend toward making solar cells lighter and more flexible. be.

[0026] (Light-absorbing layer) The light-absorbing layer 103 absorbs light such as near-infrared light, visible light, and ultraviolet light, and reacts with electrons and holes. It has the function of generating light. Examples of light such as near-infrared light, visible light, and ultraviolet light include sunlight. The light-absorbing layer 103 is preferably a perovskite compound, chalcopyrite-based. It contains a compound or kestelite compound. The perovskite compound may be used alone. Two or more types may be used in combination. The chalcopyrite compound may be used alone, or two types may be used together. More than one type may be used in combination. Kestelite compounds may be used alone, or two or more types may be used. They can be used together.

[0027] Perovskite compounds include those represented by the general formula AMX3 and those represented by the general formula A2MX4. Examples include those represented by , where M is a divalent cation and A is a monovalent cation. X represents a monovalent anion.

[0028] The monovalent cation A is not particularly limited, and for example, it could be a cation of a Group 1 element of the periodic table. And organic cations are also mentioned. Among these, cesium ions, rubidium ions, Ammonium ions (including amidinium ions) which may have substituents, A phosphonium ion which may be present, or an amidinium ion which may have substituents A is preferred. An example of an ammonium ion that may have substituents is a primary ammonium ion. Examples include nium ions and secondary ammonium ions. They may have substituents. Specific examples of ammonium ions include alkylammonium ions and arylammonium ions. Examples include mu ions, amidinium ions, and guanidium ions. In particular, steric hindrance To avoid harm, monoalkylammonium ions are preferred, and from the viewpoint of improving stability. This involves using alkylammonium ions substituted with one or more fluorine atoms. It is preferable. Furthermore, a combination of two or more cations can be used as cation A. Yes. Examples of monovalent cation A include methylammonium ion and methyl monofluoride. ammonium ions, methylammonium difluoride ions, methylammonium trifluoride Umium ion, ethylammonium ion, isopropylammonium ion, n-prop Isobutylammonium ions, isobutylammonium ions, n-butylammonium ions t-butylammonium ion, dimethylammonium ion, diethylammonium Ions, phenylammonium ions, benzylammonium ions, phenethylammonium Nium ion, guanidium ion, formamidinium ion, acetamidinium ion Examples include ions and imidazolium ions.

[0029] The divalent cation M is not particularly limited and includes, for example, divalent metal cations and semi-metallic cations. Examples include cations of group 14 elements in the periodic table. A more specific example is lead cation (Pb 2+ ), tin cation (Sn 2+ ), and gel Manium cation (Ge 2+ ) are examples. In addition, there are two or more types of cation M. Combinations of them can also be used.

[0030] The monovalent anion X is not particularly limited. For example, halide ions, acetate ions , nitrate ions, sulfate ions, borate ions, acetylacetonate ions, carbonate ions , citrate ions, sulfur ions, tellurium ions, thiocyanate ions, titanate ions, zirconate ions, 2,4-pentanedionato ions, and silicon fluoride ions, etc. can be mentioned. X may be one type of anion, or a combination of two or more types of anions. As X, it is preferable to use halide ions, or a combination of halide ions and other anions. Examples of the halide ion X include chloride ions, bromide ions, and iodide ions, etc.

[0031] Perovskite compounds include organic-inorganic perovskite compounds, particularly halide-based organic-inorganic perovskite compounds. Specific examples of perovskite compounds include CH3NH3PbI3, CH3NH3PbBr3, CH3NH3PbCl3, CH3NH 3SnI3, CH3NH3SnBr3, CH3NH3SnCl3, CH3NH3PbI Cl (3-x) Cl x , CH3NH3PbI (3-x) Br x CH3NH3PbBr (3-x) Cl x CH3NH3Pb (1-y) S n y I3, CH3NH3Pb (1-y) Sn y Br3, CH3NH3Pb (1-y) Sn y Cl3, CH3NH3 Pb (1-y) Sny I (3-x) Cl x CH3NH3Pb (1-y) Sn y I (3-x) Br x , and CH3NH3 Pb (1-y) Sn y Br (3-x) Cl x Furthermore, in the above compounds, C is used instead of CH3NH3. Examples include those using FH2NH3, CF2HNH3, CF3NH3, or NH2CH=NH2. In the above formula, x represents any value between 0 and 3 (inclusive), and y represents any value between 0 and 1 (inclusive).

[0032] Preferably, the chalcopyrite compound is a Group I-III-VI2 chalcopyrite. Examples of such compounds include the I-III-VI2 chalcopyrite compounds. It is not defined, but for example, CuAlS2, CuAlSe2, CuAlTe2, CuGaS2, C uGaSe2, CuGaTe2, CuInS2, CuInSe2, CuInTe2, AgAl S2, AgAlSe2, AgAlTe2, AgGaS2, AgGaSe2, AgGaTe2, A Examples include gInS2, AgInSe2, AgInTe2, and combinations thereof. These combinations are not particularly limited, but include, for example, CuGaS2 and CuInS When combining e2, Cu(In x Ga 1-x )(Se y S 1-y )2(0≦x≦1, 0≦y≦ 1) is one example. Among these chalcopyrite compounds, CuGaS2, CuGa Se2, CuInS2, CuInSe2, Cu(In x Ga 1-x )(Se y S 1-y )2(0≦x≦ 1, 0 ≤ y ≤ 1) is preferred, Cu(In x Ga 1-x )(Se y S 1-y )2(0≦x≦1, 0 ≤y≦1) is more preferable. Note that in this embodiment, when referring to a CIS compound, it means C A chalcopyrite compound containing u, In, and Se, and referred to as a CIGS compound, C It is a chalcopyrite compound containing u, In, Ga, and Se, and is called a CIGSS compound. It is a chalcopyrite compound containing Cu, In, Ga, Se, and S.

[0033] Preferably, the kesterite compound is an I2-II-IV-VI4 kesterite compound. Compounds are one example. I2-II-IV-VI4 kestelite compounds are particularly limited. However, for example, Cu2ZnSnS4, Cu2ZnSnSe4, Cu2ZnGeS4, Cu2 ZnGeSe4, Cu2MnSnS4, Cu2MnSnSe4, Cu2MnGeS4, Cu2Mn GeSe4, Ag2ZnSnS4, Ag2ZnSnSe4, Ag2ZnGeS4, Ag2ZnGe Se4, Ag2MnSnS4, Ag2MnSnSe4, Ag2MnGeS4, Ag2MnGeSe 4. and combinations thereof. "These combinations" is not particularly limited. However, for example, when Cu2ZnSnS4 and Ag2ZnSnSe4 are combined (Cu x Ag 1-x )2ZnSn(S y Se 1-y )4 (0≦x≦1) is one example. Cu2ZnSn(S x Se 1-x )4 (0≦x≦1, 0≦y≦1) are examples. Among these kestellite compounds However, Cu2ZnSnS4, Cu2ZnSnSe4, Ag2ZnSnS4, Ag2ZnSnSe4 , (Cu x Ag 1-x )2ZnSn(S y Se 1-y )4 (0≦x≦1, 0≦y≦1) is preferred, (Cu x Ag 1-x )2ZnSn(S y Se 1-y )4(0≦x≦1, 0≦y≦1) is more preferable. In this embodiment, when referring to a CZTS compound, it means a compound containing Cu, Zn, Sn, and S. It is a kestelite compound, and when referred to as an ACZTS compound, it is Ag, Cu, Zn, Sn It is a kestelite compound containing S, and when referred to as an ACZTSS compound, Ag, Cu, It is a kestelite compound containing Zn, Sn, S, and Se.

[0034] Perovskite compound, chalcopyrite compound, or kest in the light-absorbing layer 103 The amount of light compound is such that the light-absorbing layer 103 absorbs light such as visible light and ultraviolet light and positively It is not particularly limited as long as it has the function of creating pores. More specifically, it is not particularly limited, The amount is 50% to 100% of the total mass of the light-absorbing layer 103, and 60% of the total mass. The above is 100% by mass or less, 70% by mass or more and 100% by mass or less, and 80% by mass or more. It is 100% by mass or less, and between 90% by mass and 100% by mass.

[0035] The light-absorbing layer 103 may also contain additives such as binders and surfactants in addition to the above materials. The amount of the above additive is not particularly limited, but for example, relative to the total mass of the light-absorbing layer 103 The amount is 0.1 to 10% by mass. The light-absorbing layer 103 does not necessarily have to contain the above additives.

[0036] The thickness of the light-absorbing layer 103 is preferably 0.5 μm or more and 10.0 μm or less. 5 μm to 7.5 μm, 0.5 μm to 5.0 μm, and 0.5 μm or larger. It is 3.0 μm or less. Because the thickness of the light-absorbing layer 103 is within the above range, visible light, It has the function of absorbing light such as ultraviolet light to generate electrons and holes, while also contributing to the weight reduction and flexibility of solar cells. There is a tendency for it to become possible to make it flexible.

[0037] The solar cell 100 of this embodiment may have two light-absorbing layers 103. In this case, The material contained in the first light-absorbing layer 103 and the material contained in the second light-absorbing layer 103 are different. They may be the same, but it is preferable that they be different. The solar cell 100 has two light-absorbing layers 103. By adding a layer, the wavelength range of light that the light-absorbing layer 103 can absorb tends to be expanded. As a result, the performance of solar cells tends to improve. Also, the solar cell 10 of this embodiment 0 may have three or more light-absorbing layers 103.

[0038] (electron transport layer) The electron transport layer 104 is an n-type oxide semiconductor doped with hydrogen, and the light absorption layer 103 The electrons generated are efficiently extracted from the light absorption layer 103, and simultaneously with the electrons generated in the light absorption layer 103 It has the function of preventing the recombination of holes and electrons.

[0039] The band gap of the hydrogen-doped n-type oxide semiconductor is preferably 3.3 eV. The values ​​are above 3.4 eV, above 3.5 eV, and above 3.6 eV. Furthermore, the band gap of an n-type oxide semiconductor doped with hydrogen is not particularly limited, For example, if the reading is between 3.3 eV and 5.0 eV, and between 3.4 eV and 4.5 eV, It is between 3.5eV and 4.0eV. The band gap is within the above numerical range. As a result, the transmittance of the electron transport layer 104 is improved, and the amount of light absorbed by the light absorption layer 103 increases. As a result, the conversion efficiency of solar cells tends to improve.

[0040] For measuring the band gap, known methods can be used. More specifically This is not particularly limited, but for example, it can be measured by spectral transmittance measurement or spectral quantum efficiency measurement. It can be done.

[0041] The carrier concentration of the hydrogen-doped n-type oxide semiconductor is preferably 1.0 × 10⁻⁶. 20 cm -3 The following is true: 5.0 × 10 19 cm -3 The following is true: 2.5 × 10 19 cm -3 Below Furthermore, the carrier concentration of the n-type oxide semiconductor to which hydrogen is added is not particularly limited. However, for example, 1.0 × 10 16 cm -3 The above 1.0 × 10 20 cm -3 The following is true: 1.0 × 10 17 cm -3 The above 5.0 × 10 19 cm -3 The following is true: 1.0 × 10 18 cm -3 The above 2.5 × 10 19 cm -3 The following applies: As the carrier concentration is within the above numerical range, the light-absorbing layer 103 Because the electrons generated can be efficiently extracted from the light absorption layer 103, the electrons are absorbed in the same way as the light absorption layer 103. This makes it possible to prevent the recombination of holes and electrons that sometimes occur, and as a result, solar power The conversion efficiency of ponds tends to improve.

[0042] For measuring carrier concentration, known methods can be used. More specifically, It is not particularly limited, but can be measured by, for example, a Hall measurement.

[0043] The refractive index of an n-type oxide semiconductor with added hydrogen is not particularly limited. The refractive index of the conductor is, for example, 1.8 or higher, preferably 2.1 or higher. The rate is not particularly limited, but for example, it may be between 1.8 and 3.0, and between 2.1 and 2.8. It is below 2.1 and between 2.6 and above. The refractive index of the electron transport layer 104 is relative to the refractive index of the adjacent layer. It is preferable to adjust the folding ratio as needed to prevent it from becoming too large.

[0044] Known methods can be used to measure the refractive index. More specifically, While not limited to these, measurements can be taken, for example, by spectral transmittance measurement or spectral ellipsometry. It can be done.

[0045] The resistivity of the hydrogen-doped n-type oxide semiconductor is preferably 1.6 × 10⁻⁶. -2 Ω It is 1.8 × 10 cm or larger. -2 It is greater than Ωcm and 2.0 × 10 -2 It is greater than Ωcm. Furthermore, the resistivity of an n-type oxide semiconductor doped with hydrogen is not particularly limited, for example... ba, 1.6 × 10 -2 Ωcm or greater: 1.0 × 10 2 It is less than Ωcm and 1.8 × 10 -2 Ωcm The above is 10.0 Ωcm or less, and 2.0 × 10 -2 The ratio is between Ωcm and 1.0Ωcm. When the resistivity falls within the above numerical range, the conversion efficiency of the solar cell tends to improve.

[0046] Known methods can be used to measure the resistivity. More specifically, While not limited to these methods, they can be measured, for example, by the four-probe method.

[0047] As an n-type oxide semiconductor with added hydrogen, the band gap is 3.3 eV or higher. Yes, the carrier concentration is 1.0 × 10 20 cm -3 The following are preferred. Furthermore, hydrogen element As an n-type oxide semiconductor with added elements, the band gap is 3.3 eV or higher, Carrier concentration is 1.0 × 10 20 cm -3 The following is true, and the resistivity is 1.6 × 10⁻⁶. -2 Ωcm or larger Something is preferable.

[0048] The band gap is 3.3 eV or greater, and the carrier concentration is 1.0 × 10⁻⁶ 20 cm -3 Below Yes, with a resistivity of 1.6 × 10⁻⁶. -2 n-type oxide semiconductors with hydrogen element doped to a density of Ωcm or greater The substances included in the n-type oxide semiconductor in the body are preferably zinc oxide and tin oxide. Titanium dioxide, zinc sulfide (zinc oxide with added sulfur), magnesium oxide, zinc (Zinc oxide with added magnesium), zinc tin oxide (zinc oxide with added tin) Examples include zinc, and titanium dioxide zinc (zinc oxide with added titanium). However, titanium dioxide zinc (zinc oxide with added titanium) is preferred. n-type oxide semiconductors The body may be used individually or in combination of two or more types.

[0049] In zinc oxide with added sulfur, the function of the electron transport layer 104 is made more reliable. From the viewpoint of expressing this, preferably the molar ratio of sulfur to oxygen is 0 or more and 0.7 or less. It is below the limit, and is between 0.1 and 0.4.

[0050] In zinc oxide with added magnesium, the function of the electron transport layer 104 is further enhanced. From the viewpoint of ensuring reliable expression, preferably the molar ratio of magnesium to zinc is It is between 0 and 0.4, and between 0.1 and 0.3.

[0051] In zinc oxide with added tin, the function of the electron transport layer 104 is more reliably activated. From the viewpoint of expressing this, preferably the molar ratio of tin to zinc is 0 or more and 1.0 or less. It is below the limit, and is between 0.2 and 0.4.

[0052] In zinc oxide doped with titanium, the function of the electron transport layer 104 is made more reliable. From the viewpoint of achieving the desired effect, preferably, the molar ratio of titanium to zinc is 0 or greater. It is 3 or less, and between 0.05 and 0.2.

[0053] In an n-type oxide semiconductor doped with hydrogen, the function of the electron transport layer 104 is further enhanced. From the viewpoint of ensuring reliable expression, preferably, the molar ratio of hydrogen to all metal elements is It is between 0.001 and 0.030, between 0.005 and 0.020, and 0.00 It is between 7 and 0.015, and between 0.009 and 0.013.

[0054] The electron transport layer 104, which is an n-type oxide semiconductor with added hydrogen, is responsible for the electron transport described later. The electron transport layer may be formed by a layer formation process.

[0055] The electron transport layer 104, which is an n-type oxide semiconductor, is made of zinc oxide, tin oxide, titanium oxide, and oxide Substantially composed of zinc sulfide, zinc magnesium oxide, zinc tin oxide, or zinc titanium oxide. Preferably, zinc oxide, tin oxide, titanium oxide, zinc sulfide oxide, magnesium oxide, and tincture are used. It is preferable that the material is lead, zinc tin oxide, or zinc titanium oxide. Also, n-type oxide semiconductors are preferred. The electron transport layer 104 contains zinc oxide, tin oxide, titanium oxide, zinc sulfide oxide, and The content of magnesium zinc, tin zinc oxide, or titanium zinc oxide in the electron transport layer 104 Preferably, the amount is 80% by mass or more and 100% by mass or less relative to the total amount, and 90% by mass or more. It is 00% by mass or less, 95% by mass or more and 100% by mass or less, and 99% by mass or more and 100% by mass It is less than or equal to a percent of mass.

[0056] The thickness of the electron transport layer 104 is preferably 50 nm or more and 150 nm or less, and 55 nm m or more and 140 nm or less, 60 nm or more and 135 nm or less, 65 nm or more and 130 It is less than nm. Because the thickness of the electron transport layer 104 is within the above range, the light absorption layer 10 The electrons generated in step 3 are efficiently extracted from the light absorption layer 103, and simultaneously with the electrons in the light absorption layer 103. It has a function to prevent the recombination of the resulting holes and electrons, while also contributing to the weight reduction and flexibility of solar cells. There is a growing trend towards making them usable.

[0057] (2nd electrode layer) The second electrode layer 105 is, for example, used to extract the current generated by electrons in the light absorption layer 103. It is provided in the solar cell 100, typically, the light that has passed through the second electrode layer 105 Since the light-absorbing layer 103 absorbs light, in order to increase the amount of light absorbed by the light-absorbing layer 103, The second electrode layer 105 is preferably a transparent electrode layer. A transparent electrode is one that has high electrical conductivity and high This electrode uses a material that also possesses visible light transmittance. High electrical conductivity is not particularly limited. However, for example, if the resistivity is 5.0 × 10 -3 This means it is less than or equal to Ωcm. Light transmittance is not particularly limited, but for example, it refers to the average light transmission in the wavelength range of 400 to 1300 nm. This means that the uniform transmittance is 80% or higher. Known materials are used as the material for the transparent electrode. It can be, for example, indium tin oxide (ITO), hydrogen-containing indium oxide (ITO). OH), fluorine-containing tin oxide (FTO), boron-containing zinc oxide (ZnO:B), aluminum Examples include zinc oxide containing aluminum (ZnO:Al).

[0058] When the second electrode layer 105 is a transparent electrode, the content of the above material in the second electrode layer 105 is It is not particularly limited as long as it functions as a transparent electrode. More specifically, it is not particularly limited, but above The content of the material is 50% by mass or more and 100% by mass or less of the total mass of the second electrode layer 105. It is below, and is between 60% and 100% by mass, and between 70% and 100% by mass. Yes, 80% to 100% by mass, and 90% to 100% by mass. The mass is between 95% and 100%.

[0059] The thickness of the second electrode layer 105 is not particularly limited, but for example, 100 nm or more and 1500 nm. The thickness is less than or equal to m, and between 200 nm and 1000 nm. Being within the range allows for sufficient current extraction without loss, while also enabling weight reduction and flexibility in solar cells. There is a tendency for it to become possible to make it flexible.

[0060] (Grid electrode) The grid electrode 106 is provided, for example, to extract electricity from the second electrode layer 105. However, this may be omitted. The material of the grid electrode 106 is conductive. However, this is not particularly limited to metals such as Mo, Cr, Ag, Cu, Ni, Al, or Ti. Conductive inorganic compounds other than metals; conductive organic compounds can be used.

[0061] The content of the above material in the grid electrode 106 is such that the grid electrode 106 functions as an electrode. It is not particularly limited as long as it is possible. More specifically, it is not particularly limited, but the content of the above materials is , with respect to the total mass of the grid electrode 106, it is 50% by mass or more and 100% by mass or less, and 60 It is between 100% and 100% by mass, between 70% and 100% by mass, and 80% by mass It is between % and 100% by mass, and between 90% and 100% by mass.

[0062] The thickness of the grid electrode 106 is not particularly limited, but for example, 5 μm or more and 50 μm or less. Therefore, because the thickness of the grid electrode 106 is within the above range, the current is sufficiently supplied without loss. While extracting the solar cells, there is a trend towards making solar cells lighter and more flexible.

[0063] [Differentiation] The solar cell 100 shown in Figure 1 above is an example for illustrating the present invention, and the present invention is not limited to this example. The present invention is not intended to be limited to these embodiments only, and without departing from its spirit, various embodiments are possible. It is deformable.

[0064] For example, the solar cell 100 of this embodiment has a hole transport layer 102 and on the hole transport layer 102 A light-absorbing layer 103 is provided on the surface, and an electron transport layer 104 is provided on the light-absorbing layer 103. The second electrode layer 105, which is provided on the electron transport layer 104, and the first electrode layer are considered as one set. Two sets of the above set may be stacked on top of 101, or three or more sets may be stacked. Alternatively, a grid electrode 106 may be provided on the uppermost second electrode layer 105.

[0065] If any of layers 101-107 exist in multiples, then those multiple layers are the same as each other. It's perfectly fine for them to be different. For example, if there are multiple light-absorbing layers, each light-absorbing layer absorbs... It may contain compounds with different spectra, and electron transport layers and hole transport layers in contact with each light absorption layer. The transmitting layer may be selected according to the properties of the light-absorbing layer it is in contact with.

[0066] Furthermore, the solar cell 100 of this embodiment may, if necessary, have grid electrodes 106 between each layer. There may be other layers on top of or below the substrate 107. For example, the hole transport layer 102 may be It may have two or more hole transport layers, each containing a different material, on the grid electrode 106. It may also have a contamination prevention layer to prevent contamination from the outside. 4 may have two or more electron transport layers, each containing a different material. At least one of our layers is an n-type oxide semiconductor doped with hydrogen.

[0067] Figure 2 shows a schematic cross-sectional view of a solar cell according to one embodiment, which has two electron transport layers. The solar cell 200 of the embodiment shown comprises a substrate 107 and a first electrode provided on the substrate 107. Layer 101, hole transport layer 102 provided on the first electrode layer 101, and on the hole transport layer 102 A light-absorbing layer 103 is provided on the and a first electron transport layer 201 is provided on the light-absorbing layer 103. , a second electron transport layer 202 provided on the first electron transport layer 201, and the second electron transport layer 202 A second electrode layer 105 is provided on top, and a grid electrode 10 is provided on the second electrode layer 105. The solar cell 200 typically receives light from the second electrode layer 105 side. To generate electricity.

[0068] The solar cell 200 shown in Figure 2 differs from the solar cell 100 shown in Figure 1 in that its electron transport layer 10 It differs in that it has a first electron transport layer 201 and a second electron transport layer 202 instead of 4. The configuration may be the same as that of solar cell 100.

[0069] (electron transport layer) The solar cell 200 comprises a first electron transport layer 201 and a second electron transport layer 202. At least one of the electron transport layer 201 and the second electron transport layer 202 is made of n-ion material with added hydrogen. It is a type oxide semiconductor. Either the first electron transport layer 201 or the second electron transport layer 202 is water It may also be an n-type oxide semiconductor with elementary elements added, and both may have hydrogen added. It may also be an n-type oxide semiconductor. The first electron transport layer 201 or the second electron transport layer 202 , in the case of an n-type oxide semiconductor with added hydrogen element, examples of said n-type oxide semiconductor and A preferred embodiment is the same as or identical to the electron transport layer 104.

[0070] Either the first electron transport layer 201 or the second electron transport layer 202 is doped with hydrogen. The electron transport layer may be anything other than an n-type oxide semiconductor. Such an electron transport layer may be an n-type oxide semiconductor. It is preferable that it be a semiconductor. The material included in the n-type semiconductor is not particularly limited, but For example, zinc oxide, tin oxide, titanium oxide, zinc sulfide oxide, magnesium oxide, zinc, acid Oxide semiconductors such as zinc tin oxide and zinc titanium oxide; cadmium sulfide and indioxin sulfide Sulfide semiconductors such as indium sulfide; and PEIE (ethylene ethoxylated polyethylene). Examples include organic compounds such as lenimine and PEI (polyethyleneimine), among which Furthermore, sulfide semiconductors are preferred, and cadmium sulfide and indium sulfide are preferred. The n-type semiconductors in the sub-transport layer 201 and the second electron transport layer 202 may be used individually. You may use two or more types in combination.

[0071] Electron transport layers other than n-type oxide semiconductors doped with hydrogen are the aforementioned oxide semiconductors, sulfur Preferably, it consists substantially of an oxide semiconductor or an organic compound, and is similar to the aforementioned oxide semiconductor, sulfur It is preferable that it is a hydrocarbon semiconductor or an organic compound. Also, an n-type acid to which a hydrogen element has been added. The aforementioned oxide semiconductors, sulfide semiconductors, or organic compounds in electron transport layers other than oxide semiconductors The content of the substance is preferably 80% by mass or more and 100% by mass relative to the total amount of the electron transport layer. % or less, 90% by mass or more and 100% by mass or less, and 95% by mass or more and 100% by mass or less It is below the limit, and is between 99% and 100% by mass.

[0072] As detailed in [Method of Manufacturing Solar Cells], hydrogen is added as an electron transport layer. When forming a n-type oxide semiconductor, the film deposition damage to the underlying layer of the n-type oxide semiconductor is It is presumed that the jerk can be reduced or suppressed. Furthermore, n-type oxide semiconductors with added hydrogen are Therefore, when forming another layer on top of it, film deposition damage is less likely to occur. When layer 201 is an n-type oxide semiconductor doped with hydrogen, the light absorption layer 103 This can reduce or suppress film formation damage, and furthermore, the first electron transport layer 201 is the second electron transport layer It is resistant to film formation damage when forming the transport layer 202. The second electron transport layer 202 is a hydrogen element When an n-type oxide semiconductor with added elements is used, the deposition damage to the first electron transport layer 201 The second electron transport layer 202 can reduce or suppress the second electrode layer 105. It is resistant to film formation damage during the manufacturing process.

[0073] In one embodiment, the solar cell 200 has a first electron transport layer 201 to which hydrogen is added. It is an n-type oxide semiconductor. In this case, the n-type oxide semiconductor with added hydrogen absorbs light. It is provided on layer 103.

[0074] In one embodiment, the solar cell 200 has a second electron transport layer 202 to which hydrogen is added. It is an n-type oxide semiconductor. In this embodiment, the first electron transport layer 201 is doped with hydrogen element If it is not an n-type oxide semiconductor, it is different from an n-type oxide semiconductor with added hydrogen. The electron transport layer is a second electron, which is an n-type oxide semiconductor doped with a light absorption layer 103 and hydrogen elements. It is provided between the transport layer 202 and the transport layer 202.

[0075] The first electron transport layer 201 or the second electron transport layer 202 is an n-type oxide with added hydrogen. If it is a semiconductor, the thickness of the first electron transport layer 201 or the second electron transport layer 202 is preferred. Or, 40nm to 140nm, 50nm to 130nm, and 55 The range is between 120 nm and 120 nm.

[0076] The first electron transport layer 201 or the second electron transport layer 202 is an n-type oxide with added hydrogen. If it is not a semiconductor, the thickness of the first electron transport layer 201 or the second electron transport layer 202 is The electron transport layer's function and the materials it contains can be adjusted accordingly, for example, between 10 nm and 60 nm. It is less than or equal to m, between 15nm and 50nm, and between 20nm and 40nm.

[0077] [Method of manufacturing solar cells] (Electron transport layer formation process) The method for manufacturing a solar cell according to this embodiment involves supplying a gas containing an oxygen source and a hydrogen source while By depositing an n-type oxide semiconductor film using the sputtering method, an electric field is created on a substrate containing a light-absorbing layer. This includes a step of forming a sub-transport layer (hereinafter referred to as the "electron transport layer formation step").

[0078] The inventors have found that when an n-type oxide semiconductor is deposited using the sputtering method, the solar cell One of the factors that degrades performance is that n-type oxide semiconductors are deposited by the sputtering method. We found that film deposition damage occurs on the target substrate to which the body is deposited. The method for manufacturing the pond involves supplying not only an oxygen source but also a gas containing a hydrogen source while simultaneously producing an n-type oxide semiconductor. By forming a film, the film formation damage caused on the substrate by sputtering is reduced or suppressed. This allows for the production of highly productive, high-performance solar cells. The inventors One of the factors contributing to the reduction or suppression of film deposition damage by supplying gas containing a hydrogen source is Therefore, it is estimated that the hydrogen source captures the reactive oxygen species generated on the substrate surface during sputtering. In other words, when depositing oxide semiconductor films by sputtering, an oxygen source is included. When a gas is supplied, the inventors have found that one of the factors causing film formation damage is the oxygen source The active species generated damage the surface of the substrate where the oxide semiconductor is being formed. The inventors hypothesized that this would be the case. As a result of diligent research, the inventors found that while capturing the active species, electro As a method for forming an n-type oxide semiconductor suitable as a transport layer, a gas containing a hydrogen source is supplied. We discovered that n-type oxide semiconductors can be deposited using the sputtering method. The predictions and hypotheses described herein are made for the purpose of explaining the present invention and are not intended to limit the present invention. do not have.

[0079] The method for manufacturing a solar cell according to this embodiment is even more advanced than conventional methods for manufacturing solar cells. The following advantages may be available. As described above, the electron transport layer can be formed by sputtering using the conventional method. Forming this layer causes deposition damage to the layer below the electron transport layer, unlike conventional solar systems. The manufacturing method of the battery involves high-efficiency methods such as atomic layer stacking and chemical solution deposition when forming the electron transport layer. A film deposition method is used. In contrast, the method for manufacturing a solar cell according to this embodiment uses electron transport Because the layer can be formed using a sputtering method suitable for mass production, productivity is high. High-performance solar cells can be manufactured. Furthermore, film deposition methods such as chemical solution deposition can be used in wet applications. While it is a process, most of the steps in the manufacturing of solar cells are dry processes. Therefore, compared to methods that use a wet process when depositing the electron transport layer, this embodiment In this solar cell manufacturing method, the electron transport layer can also be formed by a dry process, Furthermore, the time required for manufacturing can be reduced. In this specification, wet p A process refers to a process that uses a solution. A dry process, on the other hand, does not use a solution. It means a process.

[0080] The film deposition damage caused on the substrate by sputtering is due to open-circuit voltage retention, as shown in Example 1. It can be evaluated by measuring the retention rate. In other words, film deposition damage is in this embodiment A solar cell manufactured by the aforementioned manufacturing method and an electron transport layer formed using chemical solution deposition. For the solar cell (control example), the open-circuit voltage was measured under standard test conditions, and the thickness of the control example was measured. Using the open-circuit voltage of the solar cell as a reference, the open-circuit voltage of the solar cell manufactured by the manufacturing method according to this embodiment It can be evaluated by calculating the discharge voltage. The standard test conditions for solar cells are spectral... The light of Pectol AM1.5 has an irradiance of 1 kW / m². 2 The incident light was placed in the solar cell and the solar cell temperature was 25°C. These are the experimental conditions.

[0081] In the method for manufacturing a solar cell according to this embodiment, and in the electron transport layer formation step, open-circuit voltage resin The retention rate is preferably 60% or more, 70% or more, 75% or more, and 80%. The above, 85% or more, and 90% or more. The manufacturing method according to this embodiment is oxygen An electron transport layer is formed by sputtering while supplying a gas containing a source and a hydrogen source. Therefore, even though the electron transport layer is formed using the sputtering method, it is not applied to the substrate. This can reduce or suppress film deposition damage. Therefore, instead of sputtering, chemical solution deposition can be used. It maintains a high level of open-circuit voltage even when compared to solar cells that form electron transport layers using the stacking method. It is considered possible.

[0082] As a standard for maintaining open-circuit voltage, a solar cell with an electron transport layer formed using chemical solution deposition was used. Alternatively, a solar cell in which an electron transport layer has been formed using atomic layer stacking may be used. A method for manufacturing a solar cell relating to its form, and in the electron transport layer formation process, using an atomic layer stacking method A solar cell having an electron transport layer formed thereon is manufactured according to the manufacturing method of this embodiment. The open-circuit voltage of the solar cell is preferably 60% or more, 70% or more, and 75%. It is % or more, 80% or more, 85% or more, and 90% or more.

[0083] In the electron transport layer formation process, sputtering is performed while supplying a gas containing an oxygen source and a hydrogen source. By depositing an n-type oxide semiconductor film using this method, an electron transport layer is formed on a substrate containing a light absorption layer. More specifically, a substrate containing a light-absorbing layer is heated, and a gas containing an oxygen source and a hydrogen source is used. While supplying the material, an n-type oxide semiconductor is placed on the substrate using a suitable sputtering target. A thin film is formed.

[0084] A substrate for forming an n-type oxide semiconductor film can be any substrate containing a light-absorbing layer, but the light-absorbing layer, A substrate including the light absorption layer, hole transport layer, and first electrode is preferred, and the light absorption layer, hole transport layer, and first electrode are stacked in this order. A substrate having a layered laminated structure is more preferable, comprising a light absorption layer, a hole transport layer, a first electrode, and a base A substrate having a laminated structure in which plates are stacked in this order is even more preferable.

[0085] In one embodiment, the substrate may have a light-absorbing layer on its surface, in which case n-type oxide semiconductor The conductor is formed on a light-absorbing layer. In one embodiment, the substrate has an electron transport layer on its surface. In this case, the n-type oxide semiconductor is deposited on the electron transport layer. The substrate is, for example, light A laminate in which an absorption layer, a hole transport layer, a first electrode, and a substrate are stacked in this order, an electron transport layer, and light A laminate in which an absorption layer, a hole transport layer, a first electrode, and a substrate are stacked in this order, or a stack of these The laminate may not contain a hole transport layer in the layered structure. If a layer is included, such electron transport layer is an n-type oxide semiconductor doped with hydrogen. It may be a transport layer, or any other electron transport layer. Specifically, in the solar cell 200 It may be the first electron transport layer 201. Using the above-mentioned substrate makes it simpler. Solar cells can be manufactured.

[0086] The substrate may contain an electron transport layer, a light absorption layer, a hole transport layer, a first electrode, and the substrate itself. The first electron transport layer 201, the light absorption layer 103, the hole transport layer 102, the first electrode layer 101, and The substrate may be the same as or similar to substrate 107.

[0087] The sputtering target in the electron transport layer formation process is the n-type oxide semiconductor film to be deposited. It is sufficient that the elements contained in the material are included, and that the metal elements contained in the n-type oxide semiconductor to be formed are not included. It is preferable that the n-type oxide semiconductor to be formed contains an oxide of the metal. For example, titanium dioxide zinc (zinc oxide with added titanium element) is made of titanium dioxide and A zinc oxide mixture can be used as a sputtering target to form a thin film. Furthermore, n-type oxide semiconductors containing sulfur elements are formed from the sulfur of the metal contained in the n-type oxide semiconductor. The film can be deposited by using a sputtering target containing a chromium. The content of metal elements in oxide semiconductors, as well as other elements including oxygen and sulfur. The yield can be controlled by adjusting the elements added to the sputtering target. ru.

[0088] In one embodiment, the sputtering target is a mixture of titanium oxide and zinc oxide. This allows for the formation of titanium dioxide zinc (zinc oxide with added titanium). The titanium dioxide content in the sputtering target is, relative to the total mass of the mixture. Preferably, 4.0% by mass or more and 20% by mass or less, and 5.0% by mass or more and 19% by mass or less. The content is below 6.0% by mass or more and 18% by mass or less. The remainder is the zinc oxide content. That's fine.

[0089] The gas supplied in the electron transport layer formation process includes an oxygen source and a hydrogen source. An active gas, preferably argon gas, may be the main component. The oxygen source may contain the element oxygen. While not particularly limited to any gas, examples include H2O vapor, O2 gas, and O3 gas. O2 gas is preferred. The hydrogen source is not particularly limited as long as it is a gas containing the element hydrogen. However, examples include H2O vapor and H2 gas, with H2 gas being preferred.

[0090] The oxygen source concentration in the supply gas is preferably 0.12% by volume or more, in terms of oxygen molecules. 2.0% by volume or less, 0.40% by volume or more and 1.8% by volume or less, and 0.70% by volume The above is 1.6 volume% or less, 0.80 volume% to 1.5 volume%, and 0.90 units. The concentration is between 1.5% by volume and between 1.0% by volume and between 1.5% by volume. (Oxygen molecule) The concentration of the oxygen source for conversion is calculated specifically as follows: When the oxygen source is H2O vapor, Since H2O vapor contains one oxygen element, the concentration of H2O vapor in the above gas is 1.0% by volume. In this case, the concentration of the oxygen source in terms of oxygen molecules is 0.5 volume%, which is half of 1.0 volume%. Yes. When the oxygen source is O2 gas, O2 gas contains two oxygen elements, therefore, the O in the above gas When the concentration of the two gases is 1.0 volume%, the concentration of the oxygen source in terms of oxygen molecules is 1.0 volume%. This is the result.

[0091] The molar ratio of hydrogen to oxygen (H / O) contained in the supply gas is preferably , 0.60 or more and 4.0 or less, 0.80 times or more and 3.0 times or less, 1.0 times or more and 2 It is 0.5 times or less, between 1.2 times and 2.0 times, and between 1.3 times and 1.8 times. The molar ratio of hydrogen to oxygen is calculated specifically as follows: (Using an oxygen source) The above gas uses O2 gas and H2O vapor as a hydrogen source, and the oxygen source in the above gas When the concentration of is 0.8 volume%, and the concentration of the hydrogen source in the above gas is 1.6 volume%, The source, H2O vapor, has two hydrogen atoms and one oxygen atom per molecule, and is an oxygen source. O2 gas has 2 oxygen atoms per molecule. Therefore, hydrogen is relative to oxygen. The molar ratio of elements is calculated as (1.6 × 2) ÷ (1.6 + 0.8 × 2) = 1.0 times. When using O2 gas as the primary source and H2 gas as the hydrogen source, the volume ratio of O2 gas to H2 gas is This corresponds to the molar ratio.

[0092] The oxygen and hydrogen sources of the supply gas are particularly preferred to satisfy either condition (1) or (2) below. It's nice. (1) The concentration of the oxygen source is 0.80% by volume or more and 1.6% by volume or less, in terms of oxygen molecules. Let y be the concentration of the oxygen source (in terms of oxygen molecules, as a volume percentage), and y be the molar ratio of hydrogen to oxygen. When (H / O) is x, the following equation is satisfied: 0.85y + 0.1 ≤ x ≤ 3.0y - 0.9 (2) The concentration of the oxygen source is 0.12% by volume or more and less than 0.80% by volume in terms of oxygen molecules. Let y be the concentration of the oxygen source (in terms of oxygen molecules, as a volume percentage), and y be the number of moles of hydrogen relative to the number of oxygen elements. When the ratio (H / O) is x, the following equation is satisfied: 0.78 ≤ x ≤ -2.2y + 3.3

[0093] The concentration of the inert gas (e.g., argon gas) in the supply gas is not particularly limited, however For example, 90.0% by volume or more and 99.0% by volume or less, and 91.0% by volume or more and 98% by volume. 5% by volume or less, 92.0% by volume or more and 98.0% by volume or less, 93.0% by volume % or more and 97.5% by volume or less, 94.0% by volume or more and 97.0% by volume or less. The remainder excluding the oxygen source and the hydrogen source may be used as an inert gas.

[0094] In the electron transport layer forming step, it is preferable to perform sputtering treatment while heating a substrate including a light absorption layer. The heating temperature (heat source temperature) is not particularly limited, but for example, it may be 80 °C or higher and 230 °C or lower, preferably 100 °C or higher and 200 °C or lower, 120 °C or higher and 180 °C or lower. When a metal substrate is used as the substrate, the temperature of the substrate and the heating temperature are substantially the same.

[0095] Other film formation conditions of the sputtering method may be adjusted according to the type of the n-type oxide semiconductor to be formed and the type of the sputtering target. For example, the applied power: 0.5 to 3.0 W / cm 2 , and the film formation pressure: 0.5 to 3.0 Pa may be used. Also, the temperature of the atmosphere during sputtering does not have to be controlled.

[0096] The method for manufacturing a solar cell according to the present embodiment may include a step of preparing a substrate including a light absorption layer and the above-described electron transport layer forming step following this. The method for manufacturing a solar cell according to the present embodiment may include a step of forming another layer on the electron transport layer following the above-described electron transport layer forming step.

[0097] The step of preparing a substrate including a light absorption layer may include at least one of a step of forming a first electrode layer, a step of forming a hole transport layer, a step of forming a light absorption layer, and a step of forming an electron transport layer. The step of forming another layer on the electron transport layer may include a step of forming a further electron transport layer ​ include at least one of the step of forming a first electrode layer, the step of forming a second electrode layer, and the step of forming a grid electrode. It may be.

[0098] The method for manufacturing a solar cell according to the present embodiment includes at least the step of forming a first electrode layer, the step of forming a light absorption layer, the above-described electron transport layer forming step, and the step of forming a second electrode layer, in this order.

[0099] Hereinafter, each step that may be included in the method for manufacturing a solar cell according to the present embodiment will be described in detail with reference to FIGS. 1 and 2 as appropriate. will be described in detail.

[0100] (First electrode layer forming step) In the first electrode layer forming step, for example, the first electrode layer 101 may be formed on the substrate 107. Examples of the method for forming the first electrode layer 101 include a dry process and a wet process, but the dry process is preferred. The dry process is not particularly limited, but for example, a method of forming the first electrode layer 101, which is a metal conductive layer, by sputtering may be used. The film formation conditions of the sputtering method are not particularly limited, but for example, the applied power: 1.0 to 3.0 W / cm 2 , the film formation atmosphere: argon atmosphere, the film formation pressure: 0.5 to 3.0 Pa may be used. Also, during sputtering, the temperature of the atmosphere and the temperature of the sputtered substrate do not have to be controlled. Note that the sputtered substrate is the substrate on the stage during sputtering, and the compound derived from the sputtering target is laminated thereon. It is the substrate. In the first electrode layer forming step, for example, the substrate 107 may be used as the sputtered substrate. temperature may not be controlled. The sputtered substrate is the substrate on the stage during sputtering, and the compound derived from the sputtering target is laminated thereon. It is the substrate. In the first electrode layer forming step, for example, the substrate 107 may be used as the sputtered substrate. substrate. It may be.

[0101] (Hole transport layer forming step) In the hole transport layer formation process, for example, a hole transport layer 102 is formed on the first electrode layer 101. Possible methods for forming the hole transport layer 102 include dry processes and wet processes. While some methods exist, a dry process is preferred. The dry process is not particularly limited to... However, for example, by sputtering, p-type semiconductors containing organic or inorganic compounds can be produced. One method is to form a hole transport layer 102. The film deposition conditions for the sputtering method are as follows: However, this is not particularly limited, but for example, applied power: 0.5~3.0W / cm 2 , film formation atmosphere Argon atmosphere, deposition pressure: 0.5~3.0 Pa may be used. Also, sputtering The temperature of the ambient air and the temperature of the sputtered substrate do not need to be controlled. Also, the light absorption layer 1 When forming 03, the elements of the first electrode layer 101 and the elements contained in the light absorption layer 103 undergo a chemical reaction. A composite is formed, and a hole transport layer 102 is formed between the first electrode layer 101 and the light absorption layer 103. A method is also acceptable.

[0102] (Light-absorbing layer formation process) In the light absorption layer formation process, for example, the light absorption layer 103 may be formed on the hole transport layer 102. i. If there is no hole transport layer 102, a light absorption layer 103 is formed on the first electrode layer 101. The method for forming the light-absorbing layer 103 may be a dry process or a wet process. While some methods exist, a dry process is preferred. The dry process is not particularly limited to... However, for example, by sputtering, perovskite compounds can be chalcopyricated. One method is to form a light-absorbing layer 103 containing a compound or kestelite compound. The deposition conditions for the taring method are not particularly limited, but for example, applied power: 0.5~3. 0W / cm2 The film formation atmosphere may be an argon atmosphere, and the film formation pressure may be 0.5 to 3.0 Pa. Also, during sputtering, the temperature of the atmosphere and the temperature of the substrate to be sputtered do not have to be controlled. After sputtering, annealing may be performed at 350°C or higher and 650°C or lower in a nitrogen or selenium and sulfur atmosphere. When the light absorption layer 103 contains an alkali metal element, the light absorption layer forming step preferably forms the light absorption layer 103 containing a perovskite compound, a chalcopyrite compound or a kesterite compound by a sputtering method using a sputtering target to which an alkali metal element is added. Alternatively, an alkali metal element may be added to the substrate 107 or the first electrode layer 101, and the alkali metal element may be thermally diffused into the light absorption layer 103 when the light absorption layer 103 is formed.

[0103]

[0104] (Additional electron transport layer forming step) The method for manufacturing a solar cell according to the present embodiment may include an additional electron transport layer forming step in addition to the above-described electron transport layer forming step. When including the additional electron transport layer forming step, a solar cell 200 including a first electron transport layer 201 and a second electron transport layer 202 as shown in FIG. 2 can be formed.

[0105]

[0106]

[0107] It may be formed on the first electron transport layer 201 formed in the above electron transport layer formation step. A second electron transport layer 202 may be formed therein.

[0106] A process for forming an electron transport layer using a method different from the electron transport layer formation process described above is hydrogen A process for depositing n-type oxide semiconductor films by sputtering while supplying a gas that does not contain a source. Examples include processes for depositing n-type oxide semiconductor films by methods other than sputtering. ru.

[0107] The film deposition conditions for the sputtering method are not particularly limited, but for example, applied power: 0. 5~3.0W / cm 2 Deposition atmosphere: Argon atmosphere that may contain oxygen, Deposition pressure: 0.5 It may be set to ~3.0 Pa. Also, the ambient temperature does not need to be controlled during sputtering. Good. It is preferable to heat the substrate to be sputtered during sputtering. Other The sputtering conditions may refer to the electron transport layer formation process described above.

[0108] Processes for depositing n-type oxide semiconductors by methods other than sputtering include chemical dissolution Examples include liquid deposition and atomic layer deposition. These methods are conventionally known.

[0109] (Second electrode layer formation process) In the second electrode layer formation step, for example, on the electron transport layer 104 or the second electron transport layer 202, A second electrode layer 105 may be formed. A method for forming the second electrode layer 105 is to use a dryer. While both wet and dry processes are possible, a dry process is preferred. The material is not particularly limited, but for example, a transparent electrode layer can be made by sputtering. One method for forming the second electrode layer 105 is to use sputtering. The film deposition conditions for the sputtering method are as follows: While not particularly limited, for example, applied power: 0.5~3.0W / cm² 2 Deposition atmosphere: Aluminium A GON atmosphere and deposition pressure of 0.5 to 3.0 Pa may be used. Also, during sputtering, the atmosphere The ambient temperature and the temperature of the substrate being sputtered do not need to be controlled.

[0110] (Grid electrode formation process) In the grid electrode formation process, for example, a grid electrode 106 is formed on the second electrode layer 105. This may also be done. Methods for forming the grid electrode 106 include a dry process and a wet process. Processes can be cited. Specifically, for example, sputtering, vapor deposition, and paste-like processes. A method for printing a conductive material onto the second electrode layer 105, or a method for crimping a conductive wire. It can be listed.

[0111] [How to use solar cells] The solar cell of this embodiment, like conventional solar cells, operates at a temperature of approximately 45-85°C. It can be used in a normal temperature environment, where the temperature is such that it is 3 degrees. Furthermore, the solar cell of this embodiment is conventional Unlike conventional solar cells, under high temperature conditions where the solar cell temperature exceeds 85°C ( (For example, outer space, the stratosphere, deserts, tropical regions, building rooftops, car roofs, airplane exteriors, etc.) However, it can be used suitably.

[0112] Furthermore, the solar cell of this embodiment is an independent solar cell used in streetlights, sensors, digital signage, etc. It can be used as a power supply device. Furthermore, the solar cell of this embodiment is a mobile energy It can also be used as a health device.

[0113] [Note] Embodiments of this disclosure include the following aspects: [1] n-type oxide semiconductor by sputtering while supplying gas containing oxygen and hydrogen sources. The process includes forming an electron transport layer on a substrate containing a light absorption layer by depositing a film. A method for manufacturing solar cells. [2] The open-circuit voltage of the manufactured solar cell under standard test conditions is the electron transport layer Instead of the aforementioned process, an electron transport layer, which is an n-type oxide semiconductor, was formed using a chemical solution deposition method. Compared to solar cells, it is 70% or more, preferably 80% or more. The manufacturing method described in [1]. [3] The substrate has a light-absorbing layer on its outermost surface, or a material different from the n-type oxide semiconductor. Having a second electron transport layer, The manufacturing method described in [1] or [2]. [4] The substrate has the light-absorbing layer on its outermost surface, The light-absorbing layer is a chalcopyrite compound, a kestelite compound, or a perovskite Contains compounds A manufacturing method described in any one of [1] to [3]. [5] The concentration of the oxygen source in the gas supplied in the above process is 0.12 in terms of oxygen molecules. The amount is between 1% by volume and 2.0% by volume, preferably between 0.8% by volume and 1.6% by volume. The manufacturing method described in any one of [1] to [4]. [6] The moles of hydrogen element relative to oxygen element contained in the gas supplied in the above process The ratio is 0.60 times or more and 4.0 times or less, preferably 1.0 times or more and 2.0 times or less. A manufacturing method described in any one of [1] to [5]. [7] The aforementioned n-type oxide semiconductor has a band gap of 3.3 eV or higher, and a carrier concentration The degree is 1.0 × 10 20 cm -3 The following oxide semiconductors are: A manufacturing method described in any one of [1] to [6]. [8] The aforementioned n-type oxide semiconductor is zinc oxide, tin oxide, titanium oxide, zinc sulfide oxide, magnesium oxide. It is zinc nezium, zinc tin oxide, or zinc titanium oxide. The manufacturing method described in [7]. [9] The aforementioned n-type oxide semiconductor is titanium zinc oxide. The aforementioned film formation contains 4.0% to 20% by mass of titanium oxide, zinc oxide and titanium oxide. This is carried out using a mixture with tan on a sputtering target. A manufacturing method described in any one of [1] to [8].

[10] The aforementioned film formation is carried out while heating the substrate to a temperature of 100°C to 200°C. The manufacturing method described in [9].

[11] The first electrode layer and Light-absorbing layer, An electron transport layer which is an n-type oxide semiconductor with hydrogen elements added, The second electrode layer and the following are included in this order, at least: Solar cell.

[12] The electron transport layer is provided on the light absorption layer.

[11] The solar cell described above.

[13] Between the light-absorbing layer and the second electrode layer is an n-type oxide semiconductor with hydrogen elements added. The device further comprises a second electron transport layer made of a different material from the aforementioned electron transport layer.

[11] The solar cell described above.

[14] The second electron transport layer is an n-type oxide semiconductor doped with the light absorption layer and hydrogen. provided between the electron transport layer and the hole transport layer The solar cell according to

[13] .

[15] The light absorption layer contains a chalcopyrite compound, a kesterite compound, or a perovskite compound. The solar cell according to any one of

[11] to

[14] .

[16] The n-type oxide semiconductor has a band gap of 3.3 eV or more and a carrier concentration of 1.0×10 20 cm -3 or less. The solar cell according to any one of

[11] to

[15] .

[17] The n-type oxide semiconductor is zinc oxide, tin oxide, titanium oxide, zinc oxide sulfide, magnesium zinc oxide, zinc tin oxide, or zinc titanium oxide. The solar cell according to

[16] .

Examples

[0114] Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. The present invention is not limited to the following Examples.

[0115] [Example 1] (Method for manufacturing a solar cell) A solar cell having a single-layer electron transport layer as shown in FIG. 1 was manufactured. As the substrate 107, a titanium foil with a thickness of 50 μm was used. On this substrate 107, a first electrode layer 101 containing a metal molybdenum was formed to a thickness of 600 nm using a sputtering method.

[0116] Next, on the first electrode layer 101, a light absorption layer 103 containing a sodium element, a potassium element, which are alkali metal elements, and a CIGSS compound was formed to a thickness of 2 using a sputtering method. It was formed in μm. Also, when forming the light absorption layer 103, the first electrode layer 101 and the light absorption layer 1 During the 03 phase, a hole transport layer 102 containing molybdenum selenide was formed with a thickness of 50 nm.

[0117] Next, hydrogen is added to the light-absorbing layer 103 using a sputtering method, and titanium An electron transport layer 104, which is an n-type oxide semiconductor containing element-doped zinc oxide, is provided with a thickness of 100. The material was formed in nm. The sputtering conditions were as follows: Sputtering target: Mixture of zinc oxide and titanium oxide (14% by mass of titanium oxide) (I made it so that it would be like this.) Deposition atmosphere: Argon, hydrogen gas, oxygen gas atmosphere (oxygen gas in the supplied mixed gas) Regarding the volume concentration of sputtering, sputtering was performed under multiple conditions ranging from 0.12% to 1.6% by volume. The experiment was conducted. Furthermore, multiple volume ratios of hydrogen gas to oxygen gas were used, ranging from 0.67 to 4.0. Sputtering was performed under the following conditions. Heating temperature of the substrate to be sputtered during film deposition: 160℃

[0118] The volume concentration of hydrogen gas in the supplied mixed gas was 1.6 vol%, and the volume of oxygen gas was... The amount of hydrogen element in the electron transport layer 104 deposited under the condition of a concentration of 1.2 volume% is RBS / Measurements using the HFS method revealed that the molar ratio of hydrogen to all metal elements was 0.011. That was the case.

[0119] Next, hydrogen-containing indium oxide ( A second electrode layer 105, which is a transparent electrode layer containing IOH, was formed with a thickness of 300 nm.

[0120] (Estimation of film formation damage) First, a control solar cell was fabricated. Similar to Example 1, a first electrode layer and a photon ray were laid on a substrate. The absorption layer was formed. Subsequently, zinc oxide with added titanium was deposited using a chemical solution deposition method. An electron transport layer, which is an n-type oxide semiconductor containing [the specified element], was formed on the light absorption layer with a thickness of 100 nm. Subsequently, a second electrode layer was formed on the electron transport layer. The method for forming the second electrode layer was the same as in Example 1. They treated it the same way.

[0121] The formation of the electron transport layer by chemical solution deposition was carried out as follows: After placing an aqueous solution containing domium, thiourea, and ammonia into a beaker, add to this solution After immersing the surface of the light-absorbing layer, the aqueous solution is gradually heated from room temperature, and the n-type oxide semiconductor An electron transport layer, which is the body of the structure, was formed.

[0122] Next, the open-circuit voltage (V) of the control solar cell and the solar cells fabricated under each condition of Example 1. oc ) The voltage was measured. The open-circuit voltage can be determined from the IV curve. Specifically, the IV curve and The point where the graph intersects with the x-axis (voltage axis) is V oc The IV curve is a standard test curve for solar cells. Under these conditions (spectral spectrum AM1.5 light at an irradiance of 1 kW / m²), 2 The solar cell temperature is affected by the incident light. The measurement was taken under test conditions of 25°C. The open-circuit voltage of the solar cells fabricated under each condition of Example 1 was The open-circuit voltage maintenance rate was calculated by dividing the value by the open-circuit voltage of the control solar cell. The volume concentration of oxygen gas in the mixed gas supplied during the mixing process, and the relative volume of oxygen gas to hydrogen gas. Table 1 shows the relationship between the volume ratio and the open-circuit voltage maintenance ratio. Values ​​highlighted in bold and underlined in Table 1 are shown below. However, these are measured values, while the other values ​​are the average of at least two adjacent values. Also, Figure 3 shows the graph created by linear interpolation based on Table 1. Under the condition that the volume concentration of hydrogen gas is 1.6 vol% and the volume concentration of oxygen gas is 1.2 vol% ( The volume ratio of hydrogen gas to oxygen gas was adopted from 1.3).

[0123] [Table 1]

[0124] [Example 2] (Method for manufacturing solar cells) In the solar cell fabrication method of Example 1, an n-type solar cell containing titanium-doped zinc oxide is used. The thickness of the electron transport layer, which is an oxide semiconductor, and the proportion of titanium oxide in the sputtering target. Multiple solar cells were fabricated by changing the heating temperature of the sputtered substrate during film deposition (each item See Table 2-3 below for details.

[0125] (Conversion efficiency) First, a control solar cell was fabricated. The control solar cell, except for the electron transport layer, was identical to the example. It was fabricated in the same manner as solar cell 1. In the control solar cell, the electron transport layer was light-absorbing. On the layer, an n-type semiconductor containing cadmium sulfide is formed to a thickness of 70 nm using chemical solution deposition. I did it.

[0126] Next, the conversion efficiency was measured for the solar cell of Example 2 and the solar cell of the control example. - The V curve was calculated under standard test conditions for solar cells (spectral spectrum AM1.5 light at irradiance 1k). W / m 2 The measurement was taken under test conditions where light was incident and the solar cell temperature was 25°C. The conversion of each solar cell... The efficiency was calculated using the following formula. Note that the conversion efficiency is calculated at the optimal operating point in the IV curve. Output (Maximum output: P) max This value is obtained by dividing ) by the light energy E received by the solar cell. Conversion efficiency (%) = P max÷E × 100

[0127] The conversion efficiency of the solar cells produced under each condition of Example 2 is divided by the conversion efficiency of the solar cell in the control example. The values ​​were calculated as the conversion efficiency ratio. This includes n-type oxides containing zinc oxide with added titanium. The thickness of the electron transport layer, which is a semiconductor, the proportion of titanium oxide in the sputtering target, or the composition Table 2-3 below shows the relationship between the heating temperature of the sputtered substrate during film deposition and the conversion efficiency ratio. In the table, "-" indicates that solar cells are not manufactured.

[0128] [Table 2]

[0129] [Table 3]

[0130] [Example 3] (Method for manufacturing solar cells) A solar cell with two electron transport layers, as shown in Figure 2, was fabricated. Aside from the actions taken, the solar cell was fabricated in the same manner as in Example 1.

[0131] The electron transport layer was formed as follows. First, indium sulfide was placed on the light absorption layer 103. The first electron transport layer 201 is made of an n-type semiconductor containing or an n-type semiconductor containing cadmium sulfide. The n-type semiconductor containing cadmium sulfide was formed at a thickness of 30 nm. It was achieved. Furthermore, the n-type semiconductor containing indium sulfide was formed using the sputtering method. The conditions for the sputtering method were as follows: Sputtering target: Indium sulfide Deposition atmosphere: Argon atmosphere Heating temperature of the substrate to be sputtered during film deposition: 200℃

[0132] Next, hydrogen is added to the first electron transport layer 201 using the sputtering method. The second electron transport layer 202 is an n-type oxide semiconductor containing titanium-doped zinc oxide. Formed. Thickness of n-type oxide semiconductor (second electron transport layer 202), sputtering target The proportion of titanium dioxide and / or the heating temperature of the sputtered substrate during film formation are shown in Table 4-5 below. Except for changing each of the values, the second electron transport layer is constructed in the same manner as the electron transport layer in Example 1. Formed 202.

[0133] The conversion efficiency of the solar cells fabricated under each condition was measured in the same manner as in Example 2. Similarly, a control example of a solar cell having an electron transport layer that is an n-type semiconductor containing cadmium sulfide. The conversion efficiency ratio for the pond was calculated. The results are shown in Table 4-5 below. Note that "-" in the table indicates bold. This indicates that the solar cell was not fabricated, and "RT" indicates that the temperature is room temperature.

[0134] [Table 4]

[0135] [Table 5] [Explanation of Symbols]

[0136] 100, 200…solar cell, 101…first electrode layer, 102…hole transport layer, 103…photoabsorbent 104... electron transport layer, 105... second electrode layer, 106... grid electrode, 107... substrate , 201...first electron transport layer, 202...second electron transport layer.

Claims

1. The process includes a step of forming an electron transport layer on a substrate containing a light-absorbing layer by depositing an n-type oxide semiconductor film by sputtering while supplying a gas containing an oxygen source and a hydrogen source to the substrate, The aforementioned n-type oxide semiconductor is titanium zinc oxide. The aforementioned film formation is carried out using a sputtering target containing a mixture of zinc oxide and titanium oxide, comprising 4.0% to 20% by mass of titanium oxide. A method for manufacturing solar cells.

2. The aforementioned film formation is carried out while heating the substrate to a temperature of 100°C to 200°C. The manufacturing method according to claim 1.

3. The aforementioned n-type oxide semiconductor has a carrier concentration of 1.0 × 10⁻⁶ 20 cm -3 The following oxide semiconductors are: The manufacturing method according to claim 1 or 2.

4. In the electron transport layer formed, the molar ratio of hydrogen to all metal elements is 0.005 or more and 0.020 or less. The manufacturing method according to claim 1 or 2.

5. The open-circuit voltage of the manufactured solar cell under standard test conditions is 70% or more compared to a solar cell in which an electron transport layer made of an n-type oxide semiconductor is formed using a chemical solution deposition method instead of the process of forming the electron transport layer. The manufacturing method according to claim 1 or 2.

6. The substrate has a second electron transport layer on its outermost surface, which is made of a material different from the light-absorbing layer or the n-type oxide semiconductor. The manufacturing method according to claim 1 or 2.

7. The substrate has the light-absorbing layer on its outermost surface, The light-absorbing layer comprises a chalcopyrite compound, a kestelite compound, or a perovskite compound. The manufacturing method according to claim 1 or 2.

8. The concentration of the oxygen source in the gas supplied in the above process is 0.12% by volume or more and 2.0% by volume or less, in terms of oxygen molecules. The manufacturing method according to claim 1 or 2.

9. In the process described above, the molar ratio of hydrogen to oxygen contained in the gas supplied is 0.60 to 4.

0. The manufacturing method according to claim 1 or 2.

10. The aforementioned n-type oxide semiconductor has a band gap of 3.3 eV or more and a carrier concentration of 1.0 × 10⁻¹⁶ 20 cm -3 The following oxide semiconductors are: The manufacturing method according to claim 1 or 2.

11. The first electrode layer and Light-absorbing layer, An electron transport layer which is an n-type oxide semiconductor with hydrogen elements added, The second electrode layer and the following are provided in this order, at least: The aforementioned n-type oxide semiconductor has a carrier concentration of 1.0 × 10⁻⁶ 20 cm -3 The following oxide semiconductors are used: The n-type oxide semiconductor is titanium dioxide zinc, and the molar ratio of titanium to zinc is 0.05 or more and 0.2 or less. Solar cell.

12. The electron transport layer is provided on the light absorption layer. The solar cell according to claim 11.

13. The light-absorbing layer and the second electrode layer further comprise a second electron transport layer made of a different material from the electron transport layer, which is an n-type oxide semiconductor doped with hydrogen. The solar cell according to claim 11.

14. The second electron transport layer is provided between the light absorption layer and the electron transport layer which is an n-type oxide semiconductor doped with hydrogen. The solar cell according to claim 13.

15. The light-absorbing layer comprises a chalcopyrite compound, a kestelite compound, or a perovskite compound. A solar cell according to any one of claims 11 to 14.

16. The aforementioned n-type oxide semiconductor has a band gap of 3.3 eV or more. A solar cell according to any one of claims 11 to 14.

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