Method for manufacturing solar battery and solar battery

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] The present invention relates to a method for manufacturing a solar cell and a solar cell. [Background technology]

[0002] A type of solar cell made of chalcopyrite, kesterite, or perovskite There are also compound solar cells that use p-type light absorbing layers. The n-type layer is generally made of a different material, which acts as an electron transport layer. Cadmium sulfide is used for this purpose.

[0003] In Non-Patent Documents 1 and 2, zinc oxide is used in place of cadmium sulfide in the electron transport layer. , tin oxide, titanium oxide, zinc oxide sulfide, magnesium zinc oxide, zinc tin oxide, and acid The use of n-type oxide semiconductors such as zinc titanium oxide 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) Summary of the Invention [Problem to be solved by the invention]

[0005] However, when an n-type oxide semiconductor is used instead of cadmium sulfide as the electron transport layer, , tend to have higher resistance and lower performance than solar cells using cadmium sulfide In addition, when forming an n-type oxide semiconductor as an electron transport layer, a process that is excellent in mass productivity is required. It is difficult to improve the performance by using the sputtering method, but the atomic layer stacking method that can manufacture high-performance solar cells is It is difficult to improve productivity using the layer method.

[0006] The present invention has been made in view of the above problems, and provides a solar cell that achieves both high performance and high productivity. The present invention aims to provide a method for manufacturing a battery 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 includes providing a gas containing an oxygen source and a hydrogen source. By supplying a large amount of oxygen to the substrate while sputtering, an n-type oxide semiconductor film is formed, including a light absorption layer. The method includes forming an electron transport layer on a substrate.

[0008] The present inventors have found that the n-type oxide semiconductor film of a solar cell is One of the factors that reduces performance is the deposition of oxide semiconductor on the surface of the substrate. The present invention relates to a method for producing a solar cell. By depositing an n-type oxide semiconductor film while supplying gas containing not only the element source but also a hydrogen source, This reduces or prevents damage to the substrate caused by sputtering. This makes it possible to manufacture highly flexible and high-performance solar cells.

[0009] The solar cell according to one embodiment of the present invention includes a first electrode layer, a light absorbing layer, and a hydrogen-doped semiconductor layer. and a second electrode layer, in this order. can.

[0010] In solar cells, the electron transport layer is made of an n-type oxide semiconductor with added hydrogen elements. This reduces or suppresses damage to the layer below the electron transport layer during sputtering. As a result, such solar cells have high performance and high yield. It is possible to achieve both productivity and Effect of the Invention

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

[0012] [Figure 1] 1 is a schematic cross-sectional view of a solar cell according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic cross-sectional view of a solar cell according to another embodiment of the present invention. [Diagram 3] FIG. 1 is a diagram showing the relationship between atmospheric conditions in a film formation process of an n-type oxide semiconductor and film formation damage caused by sputtering. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention (hereinafter, referred to as "the present embodiment") will be described with reference to the drawings as necessary. However, the present invention is not limited thereto, and the gist of the present invention is not limited thereto. In the drawings, the same elements are denoted by the same reference numerals. In addition, the positional relationship such as up, down, left, right, etc. will not be specified. Insofar as possible, the positional relationship shall be based on that shown in the drawings. Furthermore, the dimensional ratios of the drawings shall be in accordance with the ratios shown in the drawings. It is not limited to this.

[0014] [Solar cell] The solar cell according to this embodiment includes a first electrode layer, a light absorbing layer, and an n-type The solar cell includes at least an electron transport layer, which is an oxide semiconductor, and a second electrode layer, in this order. The battery may include layers other than these layers, or may include more than one of these layers. .

[0015] FIG. 1 shows a schematic cross-sectional view of a solar cell according to an embodiment. The pond 100 includes a substrate 107, a first electrode layer 101 provided on the substrate 107, and a first electrode layer A hole transport layer 102 is provided on the substrate 101, and a light absorbing layer 1 is provided on the hole transport layer 102. 03, an electron transport layer 104 provided on the light absorbing layer 103, and and a grid electrode 106 provided on the second electrode layer 105. The solar cell 100 typically receives light from the second electrode layer 105 side and generates electricity. .

[0016] In the solar cell 100 of this embodiment, the electron transport layer 104 is an n-type oxide semiconductor layer to which hydrogen elements are added. Therefore, as described in detail in [How to manufacture solar cells], The electron transport layer 104 is formed on the light absorbing layer 103. The electron transport layer 104 can be formed by sputtering while reducing or preventing the formation of As a result, it is believed that such a solar cell can achieve both high performance and high productivity. However, the present invention is not limited to the above speculation.

[0017] The thickness of the solar cell 100 excluding the substrate 107 is not particularly limited, but is, 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, 1.2 μm or more The solar cell 100 of this embodiment has each layer formed to be sufficiently thin. Thus, a thin-film solar cell can be formed.

[0018] Each component that may be included in the solar cell 100 will be described in detail below.

[0019] In this specification, each layer or the semiconductor contained in each layer is represented by the name of a certain compound. When this occurs, not only the pure compound itself but also the compound's properties are not lost, This also includes compounds doped with trace amounts of elements, etc.

[0020] In this embodiment, the elements in each layer of the solar cell are present in different oxidation states. To obtain the chemical formula, all oxidation states are referred to by the name of the element unless specifically stated otherwise. For example, "hydrogen element" can be expressed as a hydrogen atom, a hydrogen ion, a hydride ion, or a compound. It can refer to hydrogen and hydrogen in its elemental state.

[0021] (substrate) The substrate 107 is not particularly limited, but may be made of, for example, blue plate glass, low alkali glass, etc. Glass substrates, stainless steel plates, metal substrates such as aluminum foil, polyimide resin substrates, epoxy resin The thickness of the substrate 107 is not particularly limited, but for example, For example, it is 10 μm or more and 500 μm or less, 20 μm or more and 250 μm or less, and 30 μm or more. The thickness of the substrate 107 is in the above range, so that the solar cell There is a trend towards making ponds lighter and more flexible.

[0022] (1st electrode layer) The first electrode layer 101 is, for example, a layer for extracting a current caused by holes generated in a light absorbing layer 103 described later. There are no particular limitations on the first electrode layer 101 as long as it is conductive. Metal conductive layers made of metals such as Mo, Cr, or Ti, but not limited to metals; Conductive inorganic compound conductive layer made of conductive inorganic compound; Conductive organic compound conductive layer made of conductive organic compound The thickness of the first electrode layer 101 is not particularly limited. However, for example, 200 nm to 800 nm or 300 nm to 700 nm By having the thickness of the first electrode layer 101 within the above range, the current can be sufficiently passed without loss. This will enable solar cells to be made lighter and more flexible while still allowing for easy extraction.

[0023] (Hole transport layer) The solar cell 100 of this embodiment includes a hole transport layer 102, but this layer may be omitted. The transport layer 102 is, for example, a layer for efficiently transporting holes generated in the light absorbing layer 103 described later from the light absorbing layer 103. The electrons and holes generated simultaneously with the holes are recombined in the light absorbing layer 103 described below. 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; 9,9'-spirobifluorene (spiro-MeO-TAD fluorene derivatives such as polyvinylcarbazole; diphenylamine derivatives; polysilane derivatives; polyaniline derivatives, etc. Organic compounds, as well as nickel oxide, molybdenum oxide, copper gallium oxide, and aluminum oxide. Examples of suitable molybdenum-containing oxides include inorganic compounds such as molybdenum copper, molybdenum selenide, and molybdenum sulfide selenide. The p-type semiconductor in the hole transport layer 102 may be used alone or in combination of two or more kinds. Good too.

[0024] The hole transport layer 102 preferably consists essentially of the organic or inorganic compounds described above. The hole transport layer 102 is preferably an organic compound or an inorganic compound as described above. The content of the organic compound or inorganic compound in the hole transport layer 102 is, relative to the total amount of the hole transport layer 102, Preferably, the content is 80% by mass or more and 100% by mass or less, and more preferably, 90% by mass or more and 100% by mass or less. and is 95% by mass or more and 100% by mass or less, and 99% by mass or more and 100% by mass or less. do.

[0025] The thickness of the hole transport layer 102 is preferably 10 nm or more and 100 nm or less, and more preferably 15 nm or less. The thickness of the hole transport layer 102 is from 20 nm to 60 nm. By being within the above range, holes generated in the light absorbing layer 103 described below can be transported from the light absorbing layer 103 to the The electrons and holes generated at the same time as the holes are recombined in the light absorbing layer 103 described later. There is a trend toward making solar cells lighter and more flexible while still having the function of preventing the be.

[0026] (Light absorbing layer) The light absorbing layer 103 absorbs light such as near infrared light, visible light, and ultraviolet light, and converts it into electrons and holes. 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, a chalcopyrite compound, or a The perovskite compound may be used alone. The chalcopyrite compound may be used alone or in combination of two or more. The kesterite compound may be used alone or in combination of two or more kinds. They may be used in combination.

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

[0028] The monovalent cation A is not particularly limited and may be, for example, a cation of an element of Group 1 of the periodic table, and organic cations. Among these, cesium ion, rubidium ion, Ammonium ions (including amidinium ions) which may have a substituent; A phosphonium ion which may have a substituent, or an amidinium ion which may have a substituent Examples of ammonium ions which may have a substituent include primary ammonium ions. ammonium ion and secondary ammonium ion. Specific examples of the ammonium ion include alkyl ammonium ions, aryl ammonium ions, Examples of ions include methyl ions, amidinium ions, and guanidinium ions. To avoid harmful effects, monoalkylammonium ions are preferred, and from the viewpoint of improving stability, can use alkylammonium ions substituted with one or more fluorine atoms. It is also possible to use a combination of two or more types of cations as cation A. Examples of monovalent cation A include methylammonium ion, methyl monofluoride ion, and ammonium ion, methylammonium difluoride ion, methylammonium trifluoride ion ammonium ion, ethylammonium ion, isopropylammonium ion, n-propion ammonium ion, isobutylammonium ion, n-butylammonium ion , t-butylammonium ion, dimethylammonium ion, diethylammonium ion, phenylammonium ion, benzylammonium ion, phenethylammonium nium ion, guanidinium ion, formamidinium ion, acetamidinium ion ions, and imidazolium ions.

[0029] The divalent cation M is not particularly limited, and examples thereof include divalent metal cations and semi-metal cations. Specific examples include cations of group 14 elements of the periodic table. A more specific example is lead cation (Pb 2+ ), tin cation (Sn 2+ ), and gel Manium cation (Ge 2+ In addition, there are two or more kinds of cations M. A combination of the above may also be used.

[0030] The monovalent anion X is not particularly limited, and examples thereof include halide ions, acetate ions, etc. ion, nitrate ion, sulfate ion, borate ion, acetylacetonate ion, carbonate ion , citrate ion, sulfur ion, tellurium ion, thiocyanate ion, titanate ion, Examples include zirconate ion, 2,4-pentanedionato ion, and silicofluoride ion. X may be one kind of anion or a combination of two or more kinds of anions. X may be a halide ion, or a combination of a halide ion and another ion. It is preferable to use a combination of X and OH. Examples of halide ions X include chloride ions. Examples of ions include fluoride ions, bromide ions, and iodide ions.

[0031] Perovskite compounds include organic-inorganic perovskite compounds, particularly halo perovskite compounds. Examples of perovskite compounds include organic-inorganic perovskite compounds based on rhodium. Examples include CH3NH3PbI3, CH3NH3PbBr3, CH3NH3PbCl3, and CH3NH 3SnI3, CH3NH3SnBr3, CH3NH3SnCl3, CH3NH3PbI (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 , and in the above compounds, C instead of CH3NH3 Examples include those using FH2NH3, CF2HNH3, CF3NH3, or NH2CH=NH2. In the above formula, x represents an arbitrary value of 0 or more and 3 or less, and y represents an arbitrary value of 0 or more and 1 or less.

[0032] The chalcopyrite compound is preferably a I-III-VI2 group chalcopyrite. There are no particular limitations on the I-III-VI2 group chalcopyrite compounds. Not specified, but examples include CuAlS2, CuAlSe2, CuAlTe2, CuGaS2, C uGaSe2, CuGaTe2, CuInS2, CuInSe2, CuInTe2, AgAl S2, AgAlSe2, AgAlTe2, AgGaS2, AgGaSe2, AgGaTe2, A AgInS2, AgInSe2, AgInTe2, and combinations thereof. The "combination of these" is not particularly limited, but may be, for example, CuGaS2 and CuInS e2 combined with Cu(In x Ga 1-x )(Se y S 1-y )2(0≦x≦1, 0≦y≦ 1) 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, and Cu(In x Ga 1-x )(Se y S 1-y )2(0≦x≦1, 0 It is more preferable that y≦1). In this embodiment, the CIS compound is It is a chalcopyrite compound containing U, In, and Se, and when it comes to CIGS compounds, It is a chalcopyrite compound containing U, In, Ga, and Se, and is called a CIGSS compound. The compound is a chalcopyrite compound containing Cu, In, Ga, Se, and S.

[0033] The kesterite compound is preferably a group I2-II-IV-VI4 kesterite compound. The I2-II-IV-VI4 group kesterite compound is not 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. The term "combinations thereof" is not limited to these. However, for example, when Cu2ZnSnS4 and Ag2ZnSnSe4 are combined (Cu x Ag 1-x )2ZnSn(S y Se 1-y )4(0≦x≦1). x Se 1-x )4 (0≦x≦1, 0≦y≦1). Among these kesterite compounds, But 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, the CZTS compound refers to a compound containing Cu, Zn, Sn, and S. ACZTS compounds are kesterite compounds that contain Ag, Cu, Zn, Sn , S-containing kesterite compound, and when it is called ACZTSS compound, it is Ag, Cu, It is a kesterite compound containing Zn, Sn, S, and Se.

[0034] The perovskite compound, the chalcopyrite compound, or the cesium oxide in the light absorbing layer 103 The content of the light compound is determined by the amount of light that the light absorbing layer 103 absorbs light such as visible light and ultraviolet light and converts it into electrons and positive charges. There are no particular limitations as long as the material has a function of forming holes. More specifically, although there are no particular limitations, With respect to the total mass of the light absorbing layer 103, the content is 50 mass % or more and 100 mass % or less, and 60 mass % or less 70% by mass or more and 100% by mass or less, 80% by mass or more It is 100% by mass or less, and is 90% by mass or more and 100% by mass or less.

[0035] In addition to the above materials, the light absorbing layer 103 may contain additives such as a binder and a surfactant. The content of the additive is not particularly limited, but for example, The content is 0.1 to 10 mass %. The light absorbing layer 103 does not necessarily need to contain the additives.

[0036] The thickness of the light absorbing layer 103 is preferably 0.5 μm or more and 10.0 μm or less, and 0. 5μm or more and 7.5μm or less, 0.5μm or more and 5.0μm or less, 0.5μm or more When the thickness of the light absorbing layer 103 is within the above range, the visible light, The material has the function of absorbing ultraviolet light and other light to generate electrons and holes, while also contributing to the lightweight and frameless construction of solar cells. There is a tendency that it is possible to oxidize the material.

[0037] The solar cell 100 of this embodiment may have two light absorbing layers 103. In this case, The substance contained in the first light absorbing layer 103 is different from the substance contained in the second light absorbing layer 103. The solar cell 100 has two light absorbing layers 103, one for each of the first and second light absorbing layers 103 and the other for each of the second and third light absorbing layers 103. By having the layer, the wavelength range of light that the light absorbing layer 103 can absorb tends to be expanded. As a result, the performance of the solar cell tends to improve. The light absorbing layer 103 may have three or more layers.

[0038] (electron transport layer) The electron transport layer 104 is an n-type oxide semiconductor to which hydrogen elements are added, and the light absorption layer 103 The electrons generated in the photoabsorption layer 103 are efficiently extracted from the photoabsorption layer 103, and the electrons are generated simultaneously in the photoabsorption layer 103. The function of this is to prevent the recombination of the holes and electrons that are generated.

[0039] The band gap of the n-type oxide semiconductor to which hydrogen elements are added is preferably 3.3 eV. or more, 3.4 eV or more, 3.5 eV or more, or 3.6 eV or more. In addition, the band gap of the n-type oxide semiconductor to which hydrogen elements are added is not particularly limited, but may be For example, 3.3 eV or more and 5.0 eV or less, 3.4 eV or more and 4.5 eV or less, The band gap is 3.5 eV or more and 4.0 eV or less. This improves the transparency of the electron transport layer 104, and therefore 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] The band gap can be measured by a known method. is not particularly limited, but may be measured, for example, by spectral transmittance measurement or spectral quantum efficiency measurement. can be.

[0041] The carrier concentration of the n-type oxide semiconductor to which hydrogen elements are added is preferably 1.0×10 20 cm -3 is less than or equal to 5.0 x 10 19 cm -3 is less than or equal to 2.5 x 10 19 cm -3 Below In addition, the carrier concentration of the n-type oxide semiconductor to which hydrogen elements are added is not particularly limited. But, for example, 1.0×10 16 cm -3 Above 1.0×10 20 cm -3 is less than or equal to 1.0 x 10 17 cm -3 Above 5.0×10 19 cm -3 is less than or equal to 1.0 x 10 18 cm -3 More than 2.5 x 10 19 cm -3 By having the carrier concentration within the above range, the light absorbing layer 103 Since the electrons generated in the photo-absorption layer 103 can be efficiently extracted from the photo-absorption layer 103, the electrons are absorbed in the photo-absorption layer 103 at the same time. This makes it possible to prevent the recombination of holes and electrons that sometimes occur, resulting in There is a tendency for the conversion efficiency of ponds to improve.

[0042] The carrier concentration can be measured by a known method. More specifically, The measurement is not particularly limited, but may be performed, for example, by Hall measurement.

[0043] The refractive index of the n-type oxide semiconductor doped with hydrogen is not particularly limited. The refractive index of the conductor is, for example, 1.8 or more, and preferably 2.1 or more. The ratio is not particularly limited, but is, for example, 1.8 to 3.0, and is, for example, 2.1 to 2.8. The refractive index of the electron transport layer 104 is equal to or lower than 2.1 and equal to or lower than 2.6. It is preferable to appropriately adjust the refractive index so that it does not become too large.

[0044] The refractive index can be measured by a known method. More specifically, For example, the measurement may be performed by, but is not limited to, a spectroscopic transmittance measurement or a spectroscopic ellipsometry measurement. can be.

[0045] The resistivity of the n-type oxide semiconductor to which hydrogen elements are added is preferably 1.6×10 -2 Ω cm or more, 1.8 × 10 -2 Ωcm or more, 2.0×10 -2 Ωcm or more. The resistivity of the n-type oxide semiconductor to which hydrogen elements are added is not particularly limited. For example, 1.6×10 -2 Ωcm or more 1.0×10 2 Ωcm or less, 1.8×10 -2 Ωcm 10.0Ωcm or more, 2.0×10 -2 Ωcm or more and 1.0Ωcm or less. If the resistivity is within the above range, the conversion efficiency of the solar cell tends to be improved.

[0046] The resistivity can be measured by a known method. For example, the measurement is performed by a four-probe method, but is not limited thereto.

[0047] As n-type oxide semiconductors to which hydrogen elements have been added, the band gap is 3.3 eV or more. and the carrier concentration is 1.0×10 20 cm -3 It is preferable that the hydrogen atom is: The n-type oxide semiconductor with added oxygen has a band gap of 3.3 eV or more. Carrier concentration is 1.0×10 20 cm -3 The resistivity is less than or equal to 1.6×10 -2 Ωcm or more Something is preferred.

[0048] The band gap is 3.3 eV or more, and the carrier concentration is 1.0 × 10 20 cm -3 Below The resistivity is 1.6×10 -2 n-type oxide semiconductors doped with hydrogen with a resistivity of Ωcm or more The material contained in the n-type oxide semiconductor in the body is preferably zinc oxide or tin oxide. , titanium oxide, zinc oxide sulfide (zinc oxide with added elemental sulfur), magnesium zinc oxide (zinc oxide with magnesium added), zinc tin oxide (zinc oxide with tin added) zinc oxide (zinc oxide with added titanium element) and zinc titanium oxide (zinc oxide with added titanium element). However, zinc titanium oxide (zinc oxide with titanium added) is preferred. The body may be used alone or in combination of two or more kinds.

[0049] In zinc oxide to which sulfur elements are added, the function of the electron transport layer 104 is more reliably exerted. From the viewpoint of realizing the above, the molar ratio of sulfur element to oxygen element is preferably 0 or more and 0.7 or less. and is between 0.1 and 0.4.

[0050] In zinc oxide to which magnesium element is added, the function of the electron transport layer 104 is enhanced. From the viewpoint of ensuring the expression, preferably, the molar ratio of magnesium element to zinc element is , greater than or equal to 0 and less than or equal to 0.4, and greater than or equal to 0.1 and less than or equal to 0.3.

[0051] In zinc oxide to which tin element is added, the function of the electron transport layer 104 is more reliably exerted. From the viewpoint of realizing the above, the molar ratio of tin element to zinc element is preferably 0 or more and 1.0 or less. and is between 0.2 and 0.4.

[0052] In zinc oxide to which titanium element is added, the function of the electron transport layer 104 is more reliable. From the viewpoint of expression, preferably, the molar ratio of titanium element to zinc element is 0 or more and 0. It is equal to or less than 3 and is equal to or greater than 0.05 and equal to or less than 0.2.

[0053] In the n-type oxide semiconductor to which hydrogen elements are added, the function of the electron transport layer 104 is further enhanced. From the viewpoint of ensuring the expression, preferably, the molar ratio of hydrogen element to all metal elements is 0.001 or more and 0.030 or less, 0.005 or more and 0.020 or less, 0.00 7 or more and 0.015 or less, and 0.009 or more and 0.013 or less.

[0054] The electron transport layer 104, which is an n-type oxide semiconductor to which hydrogen elements have been added, is It may be an electron transport layer formed by a layer forming process.

[0055] The electron transport layer 104, which is an n-type oxide semiconductor, is made of zinc oxide, tin oxide, titanium oxide, or Consisting essentially of zinc sulfide, zinc magnesium oxide, zinc tin oxide, or zinc titanium oxide It is preferable that the oxide is zinc oxide, tin oxide, titanium oxide, zinc oxide sulfide, or zinc magnesium oxide. It is preferable that the oxide is lead, zinc tin oxide, or zinc titanium oxide. The electron transport layer 104 may be formed of zinc oxide, tin oxide, titanium oxide, zinc sulfide, or oxide. The content of magnesium zinc, zinc tin oxide, or zinc titanium oxide is The total amount is preferably 80% by mass or more and 100% by mass or less, and more preferably 90% by mass or more and 1 00% by mass or less, 95% by mass or more and 100% by mass or less, 99% by mass or more and 100% by mass or less It is less than mass %.

[0056] The thickness of the electron transport layer 104 is preferably 50 nm or more and 150 nm or less. m or more and 140 nm or less, 60 nm or more and 135 nm or less, 65 nm or more and 130 The thickness of the electron transport layer 104 is within the above range, so that the light absorption layer 10 The electrons generated in step 3 are efficiently extracted from the light absorbing layer 103, and the light absorbing layer 103 simultaneously extracts the electrons and the The new material has the function of preventing the recombination of the generated holes and electrons, while also contributing to the weight reduction and flexible construction of solar cells. There is a tendency for it to be possible to make it sible.

[0057] (2nd electrode layer) The second electrode layer 105 is, for example, a layer for extracting a current due to electrons generated in the light absorbing layer 103. In the solar cell 100, typically, the light passing through the second electrode layer 105 is Since the light absorbing layer 103 absorbs light, in order to increase the amount of light absorbed by the light absorbing layer 103, The electrode layer 105 is preferably a transparent electrode layer. A transparent electrode has high electrical conductivity and high The electrode is made of a material that has high electrical conductivity and good visible light transparency. However, for example, if the resistivity is 5.0×10 -3 This means that the resistance is less than Ωcm. The visible light transmittance is not particularly limited, but may be, for example, the average visible light transmittance in the wavelength range of 400 to 1300 nm. This means that the average transmittance is 80% or more. The transparent electrode is made of a known material. For example, indium tin oxide (ITO), hydrogen-containing indium oxide (I OH), fluorine-containing tin oxide (FTO), boron-containing zinc oxide (ZnO:B), aluminum Examples include aluminum-containing zinc oxide (ZnO:Al).

[0058] In the case where the second electrode layer 105 is a transparent electrode, the content of the above-mentioned material is There is no particular limitation as long as it functions as a transparent electrode. More specifically, although there is no particular limitation, The content of the material is 50% by mass or more and 100% by mass or less with respect to the total mass of the second electrode layer 105. 60% by mass or more and 100% by mass or less, 70% by mass or more and 100% by mass or less 80% by mass or more and 100% by mass or less, 90% by mass or more and 100% by mass or less , 95% by mass or more and 100% by mass or less.

[0059] The thickness of the second electrode layer 105 is not particularly limited, but is, for example, 100 nm or more and 1500 nm or less. The thickness of the second electrode layer 105 is equal to or less than 200 nm and equal to or less than 1000 nm. By being within this range, it is possible to extract sufficient current without loss while reducing the weight and flexibility of the solar cell. There is a tendency that it is possible to oxidize the material.

[0060] (Grid electrode) The grid electrode 106 is provided, for example, to extract electricity from the second electrode layer 105. However, it may be omitted. The material of the grid electrode 106 can be any material as long as it is conductive. Examples of the metal include, but are not limited to, Mo, Cr, Ag, Cu, Ni, Al, and Ti. conductive inorganic compounds other than metals; conductive organic compounds can be used.

[0061] The content of the above-mentioned material in the grid electrode 106 is determined so that the grid electrode 106 functions as an electrode. More specifically, the content of the above-mentioned materials is not particularly limited, but , 50% by mass or more and 100% by mass or less with respect to the total mass of the grid electrode 106, % by mass or more and 100% by mass or less, 70% by mass or more and 100% by mass or less, 80% by mass or more and % or more and 100% or less by mass, and preferably 90% or more and 100% or less by mass.

[0062] The thickness of the grid electrode 106 is not particularly limited, but is, for example, 5 μm or more and 50 μm or less. By setting the thickness of the grid electrode 106 within the above range, the current can be sufficiently passed without loss. This will enable solar cells to be made lighter and more flexible while still allowing for easy extraction.

[0063] [Variations] The solar cell 100 shown in FIG. 1 is an example for explaining the present invention. The present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present invention. Variations are possible.

[0064] For example, the solar cell 100 of this embodiment includes a hole transport layer 102 and a a light absorbing layer 103 provided on the light absorbing layer 103, and an electron transport layer 104 provided on the light absorbing layer 103; The first electrode layer 105 and the second electrode layer 105 provided on the electron transport layer 104 are regarded as one set. Two sets of the above-mentioned sets may be stacked on 101, or three or more sets may be stacked. In addition, a grid electrode 106 may be provided on the uppermost second electrode layer 105 .

[0065] When any of the layers 101 to 107 is present in a plurality of layers, the plurality of layers are the same as each other. For example, when a plurality of light absorbing layers are provided, each light absorbing layer may have an absorbing Each light absorbing layer may include a compound having a different spectrum, and an electron transport layer and a hole transport layer may be provided adjacent to each light absorbing layer. The light transmitting layer may be selected depending on the properties of the light absorbing layer that it is in contact with.

[0066] In addition, in the solar cell 100 of this embodiment, the grid electrode 106 may be disposed between the layers as necessary. The substrate 107 may have other layers on top of it or underneath it. For example, the hole transport layer 102 may be The pixel may have two or more hole transport layers each containing a different material, and the pixel may be formed on the grid electrode 106. In addition, the electron transport layer 10 may have a contamination prevention layer for preventing contamination from the outside. 4 may have two or more electron transport layers, each of which may comprise a different material, provided that At least one of the layers is an n-type oxide semiconductor doped with hydrogen elements.

[0067] FIG. 2 shows a schematic cross-sectional view of a solar cell according to one embodiment having two electron transport layers. The solar cell 200 of the embodiment shown in FIG. 1 includes a substrate 107 and a first electrode provided on the substrate 107. a hole transport layer 102 provided on the first electrode layer 101; a light absorbing layer 103 provided on the first electron transport layer 201; , a second electron transport layer 202 provided on the first electron transport layer 201; A second electrode layer 105 is provided on the substrate 10 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. Generate electricity.

[0068] The solar cell 200 shown in FIG. 2 has an electron transport layer 10 in comparison with the solar cell 100 shown in FIG. 4 in that it includes a first electron transport layer 201 and a second electron transport layer 202. The configuration may be the same as that of the solar cell 100.

[0069] (electron transport layer) The solar cell 200 includes 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 a n-type ZnO layer doped with hydrogen. Either the first electron transport layer 201 or the second electron transport layer 202 is a water-type oxide semiconductor. The n-type oxide semiconductor may be an n-type oxide semiconductor to which an element is added, and both of them may be an n-type oxide semiconductor to which an element is added. Alternatively, the first electron transport layer 201 or the second electron transport layer 202 may be an n-type oxide semiconductor. In the case of an n-type oxide semiconductor to which hydrogen elements have been added, examples of the n-type oxide semiconductor and A preferred embodiment is similar to or the same as 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 an electron transport layer other than an n-type oxide semiconductor. The n-type semiconductor is preferably a semiconductor. The substance contained in the n-type semiconductor is not particularly limited, but , for example, zinc oxide, tin oxide, titanium oxide, zinc sulfide oxide, magnesium zinc oxide, acid Oxide semiconductors such as zinc tin oxide and zinc titanium oxide; cadmium sulfide, indium oxide sulfide and sulfide semiconductors such as indium sulfide; and PEIE (polyethylene ethoxylate). Examples of organic compounds include polyethyleneimine (PEI) and poly(ethyleneimine), among which Of these, sulfide semiconductors are preferred, with cadmium sulfide and indium sulfide being preferred. The n-type semiconductor in the electron transport layer 201 and the second electron transport layer 202 may be one type alone. Two or more types may be used in combination.

[0071] The electron transport layer other than the n-type oxide semiconductor to which hydrogen elements are added is the aforementioned oxide semiconductor, sulfur It is preferable that the semiconductor layer substantially consists of the above-mentioned oxide semiconductor, sulfide semiconductor, or organic compound. It is preferable that the material is a n-type oxide semiconductor or an organic compound. The above-mentioned oxide semiconductor, sulfide semiconductor, or organic compound in the electron transport layer other than the oxide semiconductor The content of the material is preferably 80% by mass or more and 100% by mass or less based on the total amount of the electron transport layer. % or less, 90% by mass or more and 100% by mass or less, 95% by mass or more and 100% by mass or less and is 99% by mass or more and 100% by mass or less.

[0072] As described in detail in [Method of manufacturing solar cells], hydrogen elements are added as an electron transport layer. When forming an n-type oxide semiconductor having a high conductivity, the film formation damage to the lower layer of the n-type oxide semiconductor is It is presumed that the hydrogen-added n-type oxide semiconductor can reduce or suppress the degradation. Therefore, when forming another layer on the first electron transport layer, the film is less likely to be damaged. When the layer 201 is an n-type oxide semiconductor doped with hydrogen, the Damage caused by deposition can be reduced or suppressed. Furthermore, the first electron transport layer 201 is The second electron transport layer 202 is resistant to film damage caused when the second electron transport layer 202 is formed. In the case of using an n-type oxide semiconductor to which nitrogen is added, film formation damage to the first electron transport layer 201 is reduced. The second electron transport layer 202 can reduce or suppress the formation of the second electrode layer 105. It is resistant to damage caused during deposition.

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

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

[0075] The first electron transport layer 201 or the second electron transport layer 202 is an n-type oxide having hydrogen added thereto. When the first electron transport layer 201 or the second electron transport layer 202 is a semiconductor, the thickness of the first electron transport layer 201 or the second electron transport layer 202 is preferably 100 μm or more. Or, 40 nm or more and 140 nm or less, 50 nm or more and 130 nm or less, 55 nm or more and 120 nm or less.

[0076] The first electron transport layer 201 or the second electron transport layer 202 is an n-type oxide having hydrogen added thereto. In the case where the first electron transport layer 201 or the second electron transport layer 202 is not a semiconductor, the thickness of the first electron transport layer 201 or the second electron transport layer 202 is The thickness may be adjusted according to the function of the electron transport layer and the materials contained therein. For example, the thickness is set to 10 nm or more and 60 nm or less. m or less, 15 nm or more and 50 nm or less, and 20 nm or more and 40 nm or less.

[0077] [Solar cell manufacturing method] (Electron transport layer formation process) The method for producing a solar cell according to the present embodiment includes the steps of: By forming an n-type oxide semiconductor film by sputtering, an electric field is formed on the substrate including the light absorption layer. The method includes a step of forming an electron transport layer (hereinafter referred to as an "electron transport layer forming step").

[0078] The present inventors have found that the n-type oxide semiconductor film of a solar cell is One of the factors that causes the performance to decrease is that the n-type oxide semiconductor is formed by the sputtering method. It was found that the deposition damage occurred on the target substrate on which the body was deposited. The method for producing the pond is to supply gas containing not only an oxygen source but also a hydrogen source while heating the n-type oxide semiconductor By forming a film, damage to the substrate caused by sputtering is reduced or suppressed. As a result, it is possible to manufacture high-performance solar cells with high productivity. One of the factors that contribute to the reduction or suppression of damage to the film formed by supplying a gas containing a hydrogen source is It is assumed that the hydrogen source captures the active oxygen species that are generated on the substrate surface during sputtering. That is, when an oxide semiconductor is formed by sputtering, an oxygen source is added. The inventors have found that one of the causes of damage to the film is the oxygen source. The active species generated from the oxide semiconductor can damage the surface of the substrate on which the oxide semiconductor is to be formed. As a result of intensive research, the present inventors have hypothesized that the active species is captured while the electric field is generated. As a method for forming an n-type oxide semiconductor suitable as a electron transport layer, a gas containing a hydrogen source is supplied. They found that it is possible to form an n-type oxide semiconductor film by sputtering while The above predictions and hypotheses are made by way of illustration of the invention and are not intended to limit the invention. do not have.

[0079] The method for producing a solar cell according to this embodiment is further advantageous in comparison with the conventional method for producing a solar cell. As described above, the electron transport layer can be formed by a sputtering method in a conventional manner. When the electron transport layer is formed, damage to the lower layer of the electron transport layer occurs. The manufacturing method of the battery uses high-cost methods such as atomic layer deposition and chemical solution deposition to form the electron transport layer. In contrast, the method for manufacturing a solar cell according to the present embodiment uses a conventional film formation method. The transfer layer can be formed by the sputtering method, which is suitable for mass production, resulting in high productivity and high performance. In addition, the deposition method such as the chemical solution deposition method can be used to produce solar cells with high performance. While this is a process, most of the steps in the manufacturing process of solar cells are dry processes. Therefore, compared with a method using a wet process when forming the electron transport layer, the present embodiment In the manufacturing method of the solar cell, the electron transport layer can also be formed by a dry process. Furthermore, the time required for manufacturing can be shortened. The process refers to a process using a solution. The dry process refers to a process not using a solution. It means a process.

[0080] The damage to the film formed on the substrate caused by sputtering is reduced by maintaining the open circuit voltage as shown in Example 1. In other words, the damage to the film can be evaluated by measuring the retention rate. A solar cell manufactured by the above manufacturing method and an electron transport layer formed by chemical solution deposition method The open-circuit voltage of the solar cell (control example) was measured under standard test conditions, and the solar cell of the control example was The open-circuit voltage of the solar cell manufactured by the manufacturing method according to this embodiment is taken as the standard. The standard test conditions for solar cells are spectroscopic Spectrum AM1.5 light with irradiance of 1kW / m 2 The solar cell temperature is 25°C. These are the experimental conditions.

[0081] In the method for producing a solar cell according to the present embodiment and the electron transport layer forming step, The retention rate is preferably 60% or more, 70% or more, 75% or more, or 80% The oxygen concentration in the manufacturing method according to the present embodiment is 85% or more, and 90% or more. An electron transport layer is formed by a sputtering method while supplying a gas containing an oxygen source and a hydrogen source. Therefore, even though the electron transport layer is formed using a sputtering method, the Therefore, the chemical solution deposition method is used instead of the sputtering method. Maintains a high open circuit voltage compared to solar cells with electron transport layers formed using the multilayer method It is believed that this is possible.

[0082] As a benchmark for open-circuit voltage maintenance, a solar cell with an electron transport layer formed using a chemical solution deposition method Alternatively, a solar cell may be used in which the electron transport layer is formed by atomic layer deposition. A method for manufacturing a solar cell according to the present invention, and an electron transport layer forming process using an atomic layer deposition method The solar cell manufactured by the manufacturing method according to the present embodiment is based on the solar cell in which the electron transport layer is formed by The open circuit voltage value of the solar cell is preferably 60% or more, 70% or more, and more preferably 75% or more. % or more, 80% or more, 85% or more, or 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 forming an n-type oxide semiconductor film using this method, an electron transport layer is formed on a substrate including a light absorbing layer. More specifically, a substrate including a light absorbing layer is heated, and a gas including an oxygen source and a hydrogen source is introduced into the substrate. While supplying a gas, an n-type oxide semiconductor is deposited on the substrate using an appropriate sputtering target. A film is formed.

[0084] The substrate on which the n-type oxide semiconductor film is formed may be a substrate including a light absorbing layer. and a first electrode. A substrate having a laminated structure in which a light absorbing layer, a hole transport layer, a first electrode, and a substrate are preferably used. More preferred is a substrate that includes a laminated structure in which plates are laminated in this order.

[0085] In one embodiment, the substrate may have a light absorbing layer on the surface, in this case an n-type oxide semiconductor. The conductor is deposited on the light absorbing layer. In one embodiment, the substrate has an electron transport layer on a surface thereof. In this case, the n-type oxide semiconductor is deposited on the electron transport layer. A laminate in which an absorption layer, a hole transport layer, a first electrode, and a substrate are laminated in this order, an electron transport layer, a light A laminate in which an absorption layer, a hole transport layer, a first electrode, and a substrate are laminated in this order, or a laminate of these layers. The laminate may be a laminate not including a hole transport layer. When the electron transport layer includes a hydrogen-doped n-type oxide semiconductor, the electron transport layer is preferably an n-type oxide semiconductor. Specifically, the solar cell 200 may include a The first electron transport layer 201 in the above-mentioned embodiment may be used as the first electron transport layer 201 in the above-mentioned embodiment. Solar cells can be manufactured in a single process.

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

[0087] The sputtering target in the electron transport layer formation process is an n-type oxide semiconductor It is sufficient that the element contained in the n-type oxide semiconductor film is included. It is preferable that the oxide of the metal contained in the n-type oxide semiconductor to be formed is included. For example, zinc titanium oxide (zinc oxide with added titanium element) is a material that is By using a mixture of zinc oxide as a sputtering target, it is possible to form a film. In addition, the n-type oxide semiconductor containing sulfur element is formed by dissolving the metal sulfur contained in the n-type oxide semiconductor. The film can be formed by using a sputtering target containing a silicide. The inclusion of metal elements, oxygen elements and sulfur elements in the oxide semiconductors of the The rate can be controlled by adjusting the elements added to the sputtering target. do.

[0088] In one embodiment, the sputtering target is a mixture of titanium oxide and zinc oxide. This allows the deposition of a film of zinc titanium oxide (zinc oxide with added titanium). The content of titanium oxide in the sputtering target is based on the total mass of the mixture. Preferably, the content is 4.0% by mass or more and 20% by mass or less, and more preferably, 5.0% by mass or more and 19% by mass or less. The content of zinc oxide is 6.0 mass% or more and 18 mass% or less. It may be.

[0089] The gas supplied in the electron transport layer forming step includes an oxygen source and a hydrogen source. The main component may be an active gas, preferably argon gas. The oxygen source may be a gas containing oxygen element. The gas is not particularly limited as long as it can be used, but examples thereof include H2O vapor, O2 gas, and O3 gas. The hydrogen source is not particularly limited as long as it is a gas containing hydrogen element. Examples of the gas include, but are not limited to, H2O vapor and H2 gas, with H2 gas being preferred.

[0090] The concentration of the oxygen source 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, 0.70% by volume or less 0.80% by volume or more and 1.5% by volume or less, and 0.90% by volume or more and 1.6% by volume or less % or more and 1.5% or less by volume, and 1.0% or more and 1.5% or less by volume. The concentration of the converted oxygen source is calculated 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. When the oxygen concentration is calculated as 1.0 volume %, the oxygen source concentration is 0.5 volume %. When the oxygen source is O2 gas, O2 gas contains two oxygen elements, so the O When the concentration of two gases is 1.0% by volume, the concentration of the oxygen source in terms of oxygen molecules is 1.0% by volume. It becomes.

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

[0092] It is particularly preferred that the oxygen source and hydrogen source of the feed gas satisfy the following condition (1) or (2): It is. (1) The concentration of the oxygen source is, in terms of oxygen molecules, 0.80 volume % or more and 1.6 volume % or less; The concentration of the oxygen source (oxygen molecule equivalent, volume percent value) is y, and the molar ratio of hydrogen element to oxygen element is When (H / O) is x, the following formula is satisfied: 0.85y+0.1≦x≦3.0y-0.9 (2) The concentration of the oxygen source is, in terms of oxygen molecules, 0.12 volume % or more and less than 0.80 volume %. , the concentration of the oxygen source (in terms of oxygen molecules, in volume percent) is y, and the moles of hydrogen element relative to oxygen element When the ratio (H / O) is x, the following formula 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. For example, 90.0% by volume or more and 99.0% by volume or less, and 91.0% by volume or more and 98. 5% or less by volume, 92.0% or more by volume and 98.0% or less by volume, 93.0% or more by volume % or more and 97.5% volume % or less, and 94.0 vol % or more and 97.0 vol % or less. The balance, excluding the oxygen source and the hydrogen source, may be an inert gas.

[0094] In the electron transport layer forming step, the substrate including the light absorbing layer is heated while being subjected to a sputtering treatment. The heating temperature (heat source temperature) is not particularly limited, but is, for example, 80°C. The temperature may be from 100° C. to 200° C., preferably from 120° C. to 180° C. When a metal substrate is used as the substrate, the temperature of the substrate and the heating temperature are approximately Become identical.

[0095] Other film formation conditions for the sputtering method depend on the type of n-type oxide semiconductor to be formed and the sputtering temperature. The power can be adjusted according to the type of target. For example, the applied power is 0.5 to 3.0 W. / cm 2 The deposition pressure may be 0.5 to 3.0 Pa. During sputtering, the atmosphere The temperature does not have to be controlled.

[0096] The method for producing a solar cell according to this embodiment includes the steps of preparing a substrate including a light absorbing layer; The method for producing a solar cell according to the present embodiment may include the above-mentioned electron transport layer forming step. The method includes, following the above-mentioned electron transport layer formation step, forming another layer on the electron transport layer. It's okay to be.

[0097] The step of preparing a substrate including a light absorbing layer includes a step of forming a first electrode layer, a step of forming a hole transport layer, and a step of forming a second electrode layer. forming a light absorbing layer; and forming an electron transport layer. The step of forming another layer on the electron transport layer may include forming a further electron transport layer. The method includes at least one of a step of forming a second electrode layer and a step of forming a grid electrode. That's fine.

[0098] The method for producing a solar cell according to this embodiment includes at least a step of forming a first electrode layer, The process for forming the absorption layer, the process for forming the electron transport layer, and the process for forming the second electrode layer are carried out. The order may include:

[0099] Hereinafter, the manufacturing method of the solar cell according to the present embodiment will be described with reference to FIGS. Each possible step will now be described in detail.

[0100] (First electrode layer formation process) In the first electrode layer forming step, for example, the first electrode layer 101 may be formed on the substrate 107. The first electrode layer 101 can be formed by a dry process or a wet process. The dry process is preferably used, but is not particularly limited to the dry process. For example, a method of forming the first electrode layer 101, which is a metal conductive layer, by a sputtering method. The film formation conditions for the sputtering method are not particularly limited, but for example, Applied power: 1.0~3.0W / cm 2 , Film formation atmosphere: Argon atmosphere, Film formation pressure: 0.5~ During sputtering, the atmospheric temperature and the substrate pressure may be adjusted to 3.0 Pa. The temperature does not need to be controlled. The sputtered substrate is the substrate on which the sputtering is performed. a substrate on a stage, on which a compound from the sputtering target is deposited; In the first electrode layer forming step, for example, the substrate 107 is a substrate to be sputtered. It may also be a board.

[0101] (Hole transport layer forming process) In the hole transport layer forming step, for example, a hole transport layer 102 is formed on a first electrode layer 101. The hole transport layer 102 may be formed by a dry process or a wet process. The dry process is preferably used. The dry process is not particularly limited. However, for example, a p-type semiconductor containing an organic compound or an inorganic compound can be formed by a sputtering method. The hole transport layer 102 is formed under the following conditions: The power to be applied is not particularly limited, but for example, 2 , deposition atmosphere The deposition pressure may be 0.5 to 3.0 Pa. During this process, the temperature of the atmosphere and the temperature of the substrate to be sputtered do not need to be controlled. When forming the first electrode layer 101, the elements of the first electrode layer 101 and the elements contained in the light absorbing layer 103 are condensed. A mixture is formed, and a hole transport layer 102 is formed between the first electrode layer 101 and the light absorbing layer 103. A method is also possible.

[0102] (Light absorbing layer forming process) In the light absorbing layer forming step, for example, the light absorbing layer 103 may be formed on the hole transport layer 102. In the case where the hole transport layer 102 is not provided, the light absorbing layer 103 is formed on the first electrode layer 101. The light absorbing layer 103 may be formed by a dry process or a wet process. The dry process is preferably used. The dry process is not particularly limited. However, for example, perovskite compounds and chalcopyrite compounds can be produced by sputtering. A method for forming the light absorbing layer 103 containing a sputtering compound or a kesterite compound is given. The film formation conditions for the tapping method are not particularly limited, but for example, applied power: 0.5 to 3. 0W / cm2 Film formation atmosphere: argon atmosphere, film formation pressure: 0.5 to 3.0 Pa During sputtering, the temperature of the atmosphere and the temperature of the substrate to be sputtered are not controlled. After sputtering, the film may be heated at 350°C or higher to 65°C in a nitrogen or selenium and sulfur atmosphere. Annealing at temperatures below 0°C is also possible.

[0103] When the light absorbing layer 103 contains an alkali metal element, the light absorbing layer forming step is Using a sputtering target doped with boron, perovskite was deposited by sputtering. A light absorbing layer 103 containing a kite compound, a chalcopyrite compound, or a kesterite compound. It is preferable to form an alkali metal element on the substrate 107 or the first electrode layer 101. The alkali metal element is added to the light absorbing layer 103 by thermal diffusion during the formation of the light absorbing layer 103. A method in which

[0104] (Additional Electron Transport Layer Formation Process) In addition to the above-mentioned electron transport layer forming step, the method for producing a solar cell according to this embodiment further includes the steps of: In the case where an additional electron transport layer forming step is included, the method shown in FIG. Thus, a solar cell 200 is formed including a first electron transport layer 201 and a second electron transport layer 202. The additional electron transport layer forming step can be carried out in the same manner as the above-mentioned electron transport layer forming step. An n-type oxide semiconductor was grown by sputtering while supplying gas containing an oxygen source and a hydrogen source. The process may be a process of forming an electron transport layer on a substrate including a light absorbing layer by depositing a film. The electron transport layer may be formed by a method different from the above-mentioned electron transport layer forming step.

[0105] In the additional electron transport layer forming step, for example, a first electron transport layer 201 is formed on the light absorbing layer 103. On the first electron transport layer 201 formed in the above-mentioned electron transport layer forming step, A second electron transport layer 202 may be formed on the first electron transport layer 202 .

[0106] As a process for forming an electron transport layer by a method different from the above-mentioned electron transport layer forming process, a hydrogen A process for forming an n-type oxide semiconductor film by sputtering while supplying a gas that does not contain a source. and a process of forming an n-type oxide semiconductor film by a method other than the sputtering method. do.

[0107] The film formation conditions for the sputtering method are not particularly limited, but for example, applied power: 0. 5~3.0W / cm 2 , Film formation atmosphere: Argon atmosphere that may contain oxygen, Film formation pressure: 0.5 The atmospheric temperature may be controlled to 3.0 Pa. It is preferable to heat the substrate during sputtering. The sputtering conditions may be those described in the above electron transport layer forming step.

[0108] As a process for forming an n-type oxide semiconductor film by a method other than the sputtering method, chemical dissolution These methods include liquid deposition and atomic layer deposition, which are well known in the art.

[0109] (Second electrode layer formation process) In the second electrode layer formation step, for example, a first electrode layer is formed on the electron transport layer 104 or the second electron transport layer 202. The second electrode layer 105 may be formed by a dry process. The dry process is preferred. The substrate is not particularly limited, but for example, a transparent electrode layer can be formed by a sputtering method. The second electrode layer 105 is formed by the sputtering method under the following conditions: Although not particularly limited, for example, applied power: 0.5 to 3.0 W / cm 2 , deposition atmosphere: Al The atmosphere during sputtering may be 0.5 to 3.0 Pa. The temperature of the atmosphere and the temperature of the sputtered substrate do not need to be controlled.

[0110] (Grid electrode formation process) In the grid electrode forming step, for example, a grid electrode 106 is formed on the second electrode layer 105. The grid electrode 106 may be formed by a dry process or a wet process. Specifically, for example, sputtering, deposition, and paste-like processes are available. A method of printing a conductive material onto the second electrode layer 105 or a method of crimping a conductive wire are available. Some examples include:

[0111] [How to use solar cells] The solar cell of this embodiment, like the conventional solar cell, can be used when the temperature of the solar cell is about 45 to 85°C. The solar cell of the present embodiment can be used in a normal temperature environment. Unlike conventional solar cells, the temperature of the solar cell exceeds 85°C. (e.g., space, stratosphere, desert, tropical climate, building rooftops, car roofs, airplane exteriors, etc.) However, it can be suitably used.

[0112] In addition, the solar cell of this embodiment can be used as an independent solar cell for street lighting, sensors, digital signage, etc. The solar cell of this embodiment can be used as a power source device. It can also be used as an energy device.

[0113] [Note] Embodiments of the present disclosure include the following aspects. [1] An n-type oxide semiconductor was deposited by sputtering while supplying gas containing an oxygen source and a hydrogen source. forming an electron transport layer on a substrate including a light absorbing layer by forming a film of the How solar cells are manufactured. [2] The open circuit voltage of the solar cell formed under standard test conditions is Instead of the conventional process, a chemical solution deposition method was used to form an electron transport layer, which is an n-type oxide semiconductor. Compared to solar cells, it is 70% or more, preferably 80% or more. The manufacturing method described in [1]. [3] The substrate has an outermost layer made of a material different from the light absorbing layer or the n-type oxide semiconductor. a second electron transport layer comprising The manufacturing method described in [1] or [2]. [4] the substrate has the light absorbing layer as an outermost layer, The light absorbing layer is a chalcopyrite compound, a kesterite compound, or a perovskite compound. Compounds include The manufacturing method according to any one of [1] to [3]. [5] The concentration of the oxygen source in the gas supplied in the step is 0.12 in terms of oxygen molecules. % or more and 2.0% or less by volume, preferably 0.8% or more and 1.6% or less by volume; The manufacturing method according to any one of [1] to [4]. [6] The mole ratio of hydrogen atoms to oxygen atoms contained in the gas supplied in the step 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. The manufacturing method according to any one of [1] to [5]. [7] The n-type oxide semiconductor has a band gap of 3.3 eV or more and a carrier concentration Degree is 1.0×10 20 cm -3 The following oxide semiconductor: The manufacturing method according to any one of [1] to [6]. [8] The n-type oxide semiconductor is zinc oxide, tin oxide, titanium oxide, zinc sulfide oxide, magnesium oxide, etc. zinc nesium oxide, zinc tin oxide, or zinc titanium oxide; The manufacturing method described in [7]. [9] the n-type oxide semiconductor is titanium zinc oxide, The film is formed by mixing zinc oxide and titanium oxide, the titanium oxide content being 4.0 mass % or more and 20 mass % or less. The sputtering target is made of a mixture of tungsten and tungsten. The manufacturing method according to any one of [1] to [8].

[10] The film formation is carried out while heating the substrate to 100° C. or more and 200° C. or less. The manufacturing method described in [9].

[11] A first electrode layer; A light absorbing layer; an electron transport layer which is an n-type oxide semiconductor to which hydrogen elements are added; A second electrode layer, Solar cell.

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

[11] The solar cell according to claim 1.

[13] An n-type oxide semiconductor having hydrogen added thereto is disposed between the light absorbing layer and the second electrode layer. a second electron transport layer made of a different material than the electron transport layer;

[11] The solar cell according to claim 1.

[14] The second electron transport layer is an n-type oxide semiconductor to which hydrogen elements are added in addition to the light absorbing layer. and the electron transport layer is provided between the

[13] The solar cell according to claim 1.

[15] The light absorbing layer is a chalcopyrite compound, a kesterite compound, or a perovskite compound. Compounds include 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 Degree is 1.0×10 20 cm -3 The following oxide semiconductor: 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 sulfide oxide, magnesium oxide, etc. zinc nesium oxide, zinc tin oxide, or zinc titanium oxide;

[16] The solar cell according to claim 1. EXAMPLES

[0114] The present invention will be described in more detail below with reference to examples and comparative examples. The examples are not intended to be limiting in any way.

[0115] [Example 1] (How to make solar cells) A solar cell having one electron transport layer was fabricated as shown in FIG. A titanium foil having a thickness of 50 μm was used. A gold film was deposited on the substrate 107 by sputtering. A first electrode layer 101 containing metal molybdenum was formed to a thickness of 600 nm.

[0116] Next, on the first electrode layer 101, sodium, which is an alkali metal element, is deposited by sputtering. The light absorbing layer 103 containing thorium and potassium elements and a CIGSS compound is formed to a thickness of 2 In forming the light absorbing layer 103, the first electrode layer 101 and the light absorbing layer 1 During step 03, a hole transport layer 102 containing molybdenum selenide was formed to a thickness of 50 nm.

[0117] Next, hydrogen elements are added to the light absorbing layer 103 by using a sputtering method, and titanium The electron transport layer 104, which is an n-type oxide semiconductor containing zinc oxide to which elements are added, is formed to a thickness of 100 mm. The sputtering conditions were as follows: Sputtering target: A mixture of zinc oxide and titanium oxide (14% by mass of titanium oxide) It was made to be like this.) Film formation atmosphere: Argon, hydrogen, and oxygen gas atmosphere (oxygen gas in the supplied mixed gas) The volume concentration of the sputtering was varied from 0.12% to 1.6% by volume. The volume ratio of hydrogen gas to oxygen gas was also varied from 0.67 to 4.0. Sputtering was carried out under the following conditions.) Heating temperature of the sputtered substrate during film formation: 160℃

[0118] The volume concentration of hydrogen gas in the supplied mixed gas was 1.6 volume percent, and the volume concentration of oxygen gas was 1. The amount of hydrogen elements in the electron transport layer 104 formed under the condition of a concentration of 1.2% by volume was measured by RBS / The molar ratio of hydrogen to all metal elements was 0.011 when measured by the HFS method. It was.

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

[0120] (Estimation of film damage) First, a solar cell of a control example was produced. In the same manner as in Example 1, a first electrode layer, a photodiode layer, and a photodiode layer were formed on a substrate. The absorption layer was then formed. Then, titanium-doped zinc oxide was deposited on the substrate using a chemical solution deposition method. An electron transport layer, which is an n-type oxide semiconductor containing , was formed to a thickness of 100 nm on the light absorption layer. Thereafter, 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. The same was true.

[0121] The formation of the electron transport layer by chemical solution deposition was carried out as follows. An aqueous solution containing domium, thiourea, and ammonia was placed in a beaker, and then After immersing the surface of the light absorbing layer, the solution is gradually heated from room temperature while the n-type oxide semiconductor An electron transport layer was formed as a body.

[0122] Next, the open circuit voltage (V oc ) The open circuit voltage can be calculated from the IV curve. , the intersection point with the x-axis (voltage axis) on the graph is V oc The IV curve is a standard test for solar cells. Under the conditions (spectral spectrum AM1.5 light with irradiance of 1kW / m 2 The solar cell temperature rises The open circuit voltage of the solar cell manufactured under each condition in Example 1 was measured at 25°C. The open-circuit voltage maintenance rate was calculated by dividing the open-circuit voltage of the solar cell of the control example by the open-circuit voltage of the solar cell of the control example. The volume concentration of oxygen gas in the mixed gas supplied in the mixing process and the ratio of oxygen gas to hydrogen gas The relationship between the volume ratio and the open circuit voltage retention rate is shown in Table 1. In Table 1, the values ​​highlighted in bold and underlined are is the actual measured value, and the other values ​​are the averages of at least two adjacent values. A graph created by linear interpolation based on Table 1 is shown in FIG. , the volume concentration of hydrogen gas is 1.6 volume %, and the volume concentration of oxygen gas is 1.2 volume % ( The volume ratio of hydrogen gas to oxygen gas was 1.3.

[0123] [Table 1]

[0124] [Example 2] (How to make solar cells) In the method for producing a solar cell according to Example 1, an n-type solar cell containing zinc oxide to which titanium element is added is used. The thickness of the electron transport layer which is an oxide semiconductor, the ratio of titanium oxide in the sputtering target, By changing the heating temperature of the sputtered substrate during film formation, multiple solar cells were fabricated (see each article). (See Table 2-3 below for details.)

[0125] (Conversion efficiency) First, a solar cell of the control example was fabricated. The solar cell of the control example was fabricated in the same manner as in Example 1 except for the electron transport layer. The solar cell was fabricated in the same manner as in Example 1. In the control solar cell, a light absorbing A 70-nm-thick n-type semiconductor containing cadmium sulfide was formed on the layer by chemical solution deposition. Successful.

[0126] Next, the conversion efficiency of the solar cell of Example 2 and the solar cell of the control example was measured. The -V curve was measured under standard test conditions for solar cells (light with spectrum AM1.5 and irradiance of 1k W / m 2 The measurements were taken under test conditions where the solar cell temperature was 25°C and the incident light was 10 ... The efficiency was calculated using the following formula. Note that the conversion efficiency is the value at the optimum operating point on the IV curve. Output (Maximum output: P max ) divided by the light energy E received by the solar cell. Conversion efficiency (%) = P max÷E×100

[0127] The conversion efficiency of the solar cell produced under each condition in Example 2 was divided by the conversion efficiency of the solar cell in the control example. The value obtained was calculated as the conversion efficiency ratio. The thickness of the semiconductor electron transport layer, the proportion of titanium oxide in the sputtering target, or the composition The relationship between the heating temperature of the sputtered substrate during deposition and the conversion efficiency ratio is shown in Table 2-3 below. In the table, "-" indicates that no solar cell was fabricated.

[0128] [Table 2]

[0129] [Table 3]

[0130] [Example 3] (How to make solar cells) As shown in Figure 2, a solar cell with a two-layer electron transport layer was fabricated. A solar cell was fabricated in the same manner as in Example 1, except that the above-mentioned steps were carried out.

[0131] The electron transport layer was formed as follows. First, indium sulfide was deposited on the light absorbing layer 103. The first electron transport layer 201 is an n-type semiconductor containing cadmium sulfide or an n-type semiconductor containing cadmium sulfide. The n-type semiconductor containing cadmium sulfide was formed using a chemical solution deposition method. The n-type semiconductor containing indium sulfide was formed by sputtering. The conditions for the sputtering method were as follows: Sputtering target: Indium sulfide Film deposition atmosphere: Argon atmosphere Heating temperature of the sputtered substrate during film formation: 200℃

[0132] Next, hydrogen elements are added onto the first electron transport layer 201 by using a sputtering method, The second electron transport layer 202 is an n-type oxide semiconductor containing zinc oxide doped with titanium. The thickness of the n-type oxide semiconductor (second electron transport layer 202), the sputtering target The ratio of titanium oxide in the sample and / or the heating temperature of the sputtered substrate during film formation are shown in Table 4-5 below. The second electron transport layer was prepared in the same manner as in Example 1, except that the values ​​of 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 solar cell having an electron transport layer that is an n-type semiconductor containing cadmium sulfide was also prepared. The conversion efficiency ratio for the pond was calculated. The results are shown in Table 4-5 below. In the table, "-" indicates a bold It indicates that no solar cell was fabricated, and "RT" indicates 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... light absorption a second electrode layer, a grid electrode, and a substrate; , 201...first electron transport layer, 202...second electron transport layer.

Claims

1. A method for manufacturing a semiconductor device comprising: forming an n-type oxide semiconductor film on a substrate including a light absorbing layer by a sputtering method while supplying a gas containing an oxygen source and a hydrogen source to the substrate; How solar cells are manufactured.

2. The n-type oxide semiconductor is an oxide semiconductor having a carrier concentration of 1.0 × 10 20 cm −3 or less. The method of claim 1.

3. In the electron transport layer formed, the molar ratio of hydrogen elements to all metal elements is 0.001 or more and 0.030 or less. The method of claim 2.

4. the open circuit voltage of the manufactured solar cell under standard test conditions is 70% or more compared to that of a solar cell in which an electron transport layer made of an n-type oxide semiconductor is formed by a chemical solution deposition method instead of the step of forming the electron transport layer; The method of claim 1.

5. the substrate has, as an outermost layer, a second electron transport layer made of a material different from the light absorbing layer or the n-type oxide semiconductor; The method of claim 1.

6. the substrate has the light absorbing layer as an outermost layer, The light absorbing layer contains a chalcopyrite compound, a kesterite compound, or a perovskite compound. The method of claim 1.

7. the concentration of the oxygen source in the gas supplied in the step is 0.12 vol% or more and 2.0 vol% or less in terms of oxygen molecules; The method according to any one of claims 1 to 6.

8. a molar ratio of hydrogen elements to oxygen elements contained in the gas supplied in the step is 0.60 times or more and 4.0 times or less; The method according to any one of claims 1 to 6.

9. 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 The following oxide semiconductors: The method according to any one of claims 1 to 6.

10. the n-type oxide semiconductor is zinc oxide, tin oxide, titanium oxide, zinc oxide sulfide, magnesium zinc oxide, zinc tin oxide, or titanium zinc oxide; The method of claim 9.

11. the n-type oxide semiconductor is titanium zinc oxide, The film formation is carried out using a mixture of zinc oxide and titanium oxide containing 4.0 mass % or more and 20 mass % or less of titanium oxide as a sputtering target. The method according to any one of claims 1 to 6.

12. The film formation is carried out while heating the substrate to 100°C or higher and 200°C or lower. The method of claim 11.

13. a first electrode layer; a light absorbing layer; an electron transport layer that is an n-type oxide semiconductor doped with hydrogen; a second electrode layer, the n-type oxide semiconductor has a carrier concentration of 1.0×10 20 cm −3 or less; Solar cell.

14. In the electron transport layer, a molar ratio of hydrogen elements to all metal elements is 0.001 or more and 0.030 or less. The solar cell according to claim 13.

15. the electron transport layer is provided on the light absorbing layer; The solar cell according to claim 13.

16. a second electron transport layer between the light absorbing layer and the second electrode layer, the second electron transport layer being made of a material different from that of the electron transport layer, which is an n-type oxide semiconductor doped with hydrogen; The solar cell according to claim 14.

17. the second electron transport layer is provided between the light absorbing layer and the electron transport layer which is an n-type oxide semiconductor to which hydrogen elements are added; The solar cell according to claim 16.

18. The light absorbing layer contains a chalcopyrite compound, a kesterite compound, or a perovskite compound. The solar cell according to any one of claims 13 to 17.

19. The n-type oxide semiconductor has a band gap of 3.3 eV or more. The solar cell according to any one of claims 13 to 17.

20. the n-type oxide semiconductor is zinc oxide, tin oxide, titanium oxide, zinc oxide sulfide, magnesium zinc oxide, zinc tin oxide, or titanium zinc oxide; The solar cell of claim 19.

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