Laminate, solar cell, multi-junction solar cell, solar cell module, photovoltaic power generation system, and method for manufacturing the laminate.

Abstract

The embodiment provides a high-quality laminate. [Solution] The laminate of the embodiment comprises a transparent substrate, a p-electrode including an oxide transparent conductive film provided on the substrate, and a p-type light-absorbing layer having a cuprous oxide compound provided on the p-electrode. The grain size of the cuprous oxide compound is 1.2 times or more the thickness of the p-type light-absorbing layer. The carrier concentration of the p-type light-absorbing layer is 5.0 × 10 14 [cm -3 The above is true. Cuprous oxide compounds contain copper, oxygen, and optionally an element represented by M1. The element represented by M1 is one or more selected from the group consisting of Li, Na, K, Al, Ga, In, C, Si, Ge, Sn, N, P, Sb, and Bi.

Description

Technical Field

[0001] The present invention relates to a laminate, a solar cell, a multi-junction solar cell, a solar cell module, a solar power generation system, and a method for manufacturing a laminate.

Background Art

[0002] One of the new solar cells is a solar cell using cuprous oxide (Cu2O) as a light absorption layer. Cu2O is a wide-gap semiconductor. Since Cu2O is a safe and inexpensive material composed of copper and oxygen that is abundantly present on the earth, it is expected to realize a highly efficient and low-cost solar cell.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The problem to be solved by the present invention is to provide a high-quality laminate.

Means for Solving the Problems

[0005] The laminate of the embodiment has a transparent substrate, a p electrode including a transparent conductive oxide film provided on the substrate, and a p-type light absorption layer having a cuprous oxide compound provided on the p electrode. The crystal grain size of the cuprous oxide compound is 1.2 times or more the thickness of the p-type light absorption layer. The carrier concentration of the p-type light absorption layer is 5.0×10 [cm <00000​​​​

[0006] [Figure 1] Figure 1 is a schematic cross-sectional view of the laminate according to the embodiment. [Figure 2] Figure 2 illustrates the analysis spots of the laminate in the embodiment. [Figure 3] Figure 3 is a schematic diagram of the surface of the p-type light-absorbing layer in the embodiment. [Figure 4] Figure 4 is a flowchart of the manufacturing method for the laminate according to the embodiment. [Figure 5] Figure 5 is a schematic diagram of the manufacturing apparatus according to the embodiment. [Figure 6] Figure 6 is a schematic cross-sectional view of a solar cell according to an embodiment. [Figure 7] Figure 7 is a cross-sectional view of a multi-junction solar cell according to an embodiment. [Figure 8] Figure 8 is a perspective view of a solar cell module according to an embodiment. [Figure 9] Figure 9 is a cross-sectional view of a solar cell module according to an embodiment. [Figure 10] Figure 10 is a diagram showing the configuration of a solar power generation system according to an embodiment. [Figure 11] Figure 11 is a schematic diagram of the vehicle according to the embodiment. [Figure 12] Figure 12 is a schematic diagram of the flying object according to the embodiment. [Figure 13] Figure 13 is a table relating to the examples. [Figure 14] Figure 14 is a table relating to the examples. [Figure 15] Figure 15 shows a cross-sectional SEM image of the laminate in the example. [Figure 16] Figure 16 is a table relating to the examples. [Modes for carrying out the invention]

[0007] A preferred embodiment of the present invention will be described in detail below with reference to the drawings. Unless otherwise specified, the physical properties are shown at 25°C and 1 atmosphere (atmosphere). The average is the arithmetic mean. Unless otherwise specified, each concentration is the average concentration of the region or layer in question. In each layer, "contains a specific element" means, for example, an element whose presence can be confirmed by SIMS (Secondary Ion Mass Spectrometry), and "does not contain a specific element" means, for example, an element whose presence cannot be confirmed by SIMS (an element below the detection limit).

[0008] In the specification, " / " represents the division symbol. However, " / " in "or / and" means "or". In the specification, "·" and "*" represent the multiplication symbol. In the specification, "." in numbers represents the decimal point.

[0009] (First Embodiment) The first embodiment relates to a laminate. Figure 1 shows a schematic cross-sectional view of the laminate. The laminate 10 shown in the schematic cross-sectional view of Figure 1 comprises a substrate 1, a p-electrode 2, and a p-type light-absorbing layer 3. A member on which the p-electrode 2 is provided on the substrate 1 is used as the base material. The laminate 10 is suitable for use in solar cells.

[0010] Substrate 1 is a substrate that transmits infrared and visible light. As substrate 1, inorganic substrates such as physically strengthened glass, chemically strengthened glass (e.g., borosilicate glass), crystallized glass (e.g., Neoceram®), or quartz glass can be used.

[0011] The thickness of the substrate 1 is preferably, for example, 10 [μm] or more and 5 [mm] or less. The thickness of the substrate 1 is measured as follows: First, the substrate 1 is measured with a scale. In this case, if the thickness of the substrate 1 can be measured in millimeters (for example, if the thickness of the base material is 1 [mm] or more), it is measured directly with the scale. If it cannot be measured in millimeters, it is determined by cross-sectional observation with an electron microscope or by a step gauge.

[0012] The heat resistance temperature (usable limit temperature) of substrate 1 is preferably at or above the temperature of the substrate during sputtering of the p-type light absorption layer 3. If the heat resistance temperature of substrate 1 is close to the temperature of the substrate during sputtering of the p-type light absorption layer 3, the heat resistance temperature of substrate 1 may be lower than the temperature of the substrate during sputtering of the p-type light absorption layer 3. The heat resistance temperature of substrate 1 can be any temperature relative to the temperature of sputtering of the p-type light absorption layer 3, as long as it does not undergo excessive deformation or other changes.

[0013] The softening point [°C] of the substrate 1 is preferably equal to or greater than the temperature of the substrate during sputtering of the p-type light absorption layer 3.

[0014] The p-electrode 2 is provided on the substrate 1 and is positioned between the substrate 1 and the p-type light absorption layer 3. It is preferable that the p-electrode 2 is ohmic-junctioned with the p-type light absorption layer 3. The p-electrode 2 is provided on the side of the p-type light absorption layer 3 and is a conductive layer that transmits light to visible light from a wavelength of approximately 1200 nm. The thickness of the p-electrode 2 is typically between 50 nm and 2000 nm. In Figure 1, the p-electrode 2 is in direct contact with the p-type light absorption layer 3. An intermediate layer (not shown) may be provided between the p-electrode 2 and the p-type light absorption layer 3.

[0015] The p electrode 2 preferably contains an oxide transparent conductive film. The p electrode 2 preferably contains one or more layers of oxide transparent conductive film. The oxide transparent conductive film can be a semiconductor conductive film such as indium tin oxide (ITO), aluminum-doped zinc oxide (AZO), boron-doped zinc oxide (BZO), gallium-doped zinc oxide (GZO), doped tin oxide, titanium-doped indium oxide (ITiO), indium zinc oxide (IZO), indium gallium zinc oxide (IGZO), or hydrogen-doped indium oxide (IOH), and is not particularly limited. The oxide transparent conductive film may be a laminated film having multiple layers. The dopant used for the tin oxide film is not particularly limited, as long as it is one or more elements selected from the group consisting of In, Si, Ge, Ti, Cu, Sb, Nb, Ta, W, Mo, F, and Cl. The p electrode 2 preferably contains a tin oxide film doped with one or more elements selected from the group consisting of In, Si, Ge, Ti, Cu, Sb, Nb, Ta, W, Mo, F, and Cl. Considering heat resistance, it is preferable to use a tin oxide film doped with Sb for the p electrode 2. In the doped tin oxide film, it is preferable that one or more elements selected from the group consisting of In, Si, Ge, Ti, Cu, Sb, Nb, Ta, W, Mo, F, and Cl are present in an amount of 10 atomic percent or less relative to the tin contained in the tin oxide film. A laminated film, in which an oxide transparent conductive film and a metal film are laminated, can be used as the p electrode 2. The metal film is preferably 1 nm or more and 500 μm or less in thickness, and the metal (including alloys) contained in the metal film is not particularly limited, such as Mo, Au, Cu, Ag, Al, Ta, or W. The metal film is preferably an open conductive layer rather than a solid film.Furthermore, the p-electrode 2 preferably includes dot-shaped, line-shaped, or mesh-shaped electrodes (one or more selected from the group consisting of metals, alloys, graphene, conductive nitrides, and conductive oxides) between the oxide transparent conductive film and the substrate 1, or between the oxide transparent conductive film and the p-type light absorption layer 3. The dot-shaped, line-shaped, or mesh-shaped metal preferably has an aperture ratio of 50% or more relative to the oxide transparent conductive film. The dot-shaped, line-shaped, or mesh-shaped metal is not particularly limited to Mo, Au, Cu, Ag, Al, Ta, or W. When a metal film is used for the p-electrode 2, it is preferable to have a film thickness of about 5 nm or less from the viewpoint of light transmittance. When a line-shaped or mesh-shaped metal film is used, light transmittance is ensured at the aperture, so this does not apply to the film thickness of the metal film.

[0016] It is preferable that a doped tin oxide film is provided on the outermost surface of the oxide transparent conductive film on the side facing the p-type light absorption layer 3, forming an ohmic bond with the p-type light absorption layer 3. It is preferable that at least a portion of the doped tin oxide film provided on the outermost surface of the p-type light absorption layer 3 of the oxide transparent conductive film is in direct contact with the p-type light absorption layer 3.

[0017] The p-type light absorption layer 3 is a p-type semiconductor layer. The p-type light absorption layer 3 is provided on the p-electrode 2. The p-type light absorption layer 3 may be in direct contact with the p-electrode 2, or other layers may be present as long as electrical contact with the p-electrode 2 is ensured. The p-electrode 2 is positioned between the p-type light absorption layer 3 and the substrate 1. The p-type light absorption layer 3 mainly consists of a cuprous oxide compound. The cuprous oxide compound preferably has a cuprite-type structure.

[0018] The thickness of the p-type light absorption layer 3 is preferably 500 nm or more and 10 μm or less, and more preferably 750 nm or more and 7.0 μm or less.

[0019] The p-type light-absorbing layer 3 is preferably a semiconductor layer mainly composed of a cuprous oxide compound. The p-type light-absorbing layer 3 is preferably composed of crystals of the cuprous oxide compound. The p-type light-absorbing layer 3 is preferably composed of polycrystalline cuprous oxide. The p-type light-absorbing layer 3 may contain trace amounts of one or more cuprous oxide impurities selected from the group consisting of copper (Cu), copper oxide (CuO), and copper hydroxide (Cu(OH)2) as partial impurities.

[0020] Cuprous oxide compounds preferably contain copper, oxygen, and optionally an element represented by M1. The element represented by M1 is preferably one or more selected from the group consisting of Li, Na, K, Al, Ga, In, C, Si, Ge, Sn, N, P, Sb, and Bi, more preferably Si and / or N, and even more preferably N. The element represented by M1 contains at least one or more selected from the group consisting of Li, Na, K, Al, Ga, In, C, Si, Ge, Sn, N, P, Sb, and Bi, and may optionally contain one or more selected from the group consisting of Cl, F, Br, I, Sn, Ag, Cs, Rb, Zn, Mg, B, Ti, Hf, Zr, and Ca. The element represented by M1 contains at least Si and / or N, and may further optionally contain one or more elements selected from the group consisting of Li, Na, K, Al, Ga, In, C, Ge, Sn, P, Sb, Bi, Cl, F, Br, I, Sn, Ag, Cs, Rb, Zn, Mg, B, Ti, Hf, Zr, and Ca. The element represented by M1 contains at least N, and may further optionally contain one or more elements selected from the group consisting of Li, Na, K, Al, Ga, In, C, Si, Ge, Sn, P, Sb, Bi, Cl, F, Br, I, Sn, Ag, Cs, Rb, Zn, Mg, B, Ti, Hf, Zr, and Ca.

[0021] By carrier doping the cuprous oxide compound of the p-type light-absorbing layer 3 with one or more elements selected from the group consisting of Li, Na, K, Al, Ga, In, C, Si, Ge, Sn, N, P, Sb, and Bi, the carrier concentration of the p-type light-absorbing layer 3 is increased. As the dopant to increase the carrier concentration of the p-type light-absorbing layer 3, N and / or Si are preferred, and N is more preferred.

[0022] When all elements except oxygen contained in the p-type light-absorbing layer 3 are considered to be 100%, the total amount of copper and the elements represented by M1 contained in the p-type light-absorbing layer 3 is preferably 95% or more and 100%, more preferably 98% or more and 100%, and even more preferably 99% or more and 100%.

[0023] When the copper element in the p-type light-absorbing layer 3 is set to 100%, the total amount of all elements excluding copper and oxygen in the p-type light-absorbing layer 3 is preferably 0.00001% or more and 0.1% or less, more preferably 0.00001% or more and 0.01% or less, and even more preferably 0.00001% or more and 0.001% or less. If the above composition ratio does not meet the above range, it may become difficult for the cuprous oxide compound to have a cuprite-type structure, the light transmittance of the p-type light-absorbing layer 3 may decrease, or the band gap may fall outside the preferred range. It is preferable that the above range be satisfied throughout the entire p-type light absorption layer 3, but it is preferable that the above range be satisfied within the range of at least 20% of the thickness of the p-type light absorption layer 3 (endpoint) from the interface between the p-type light absorption layer 3 and the p-electrode 2 (starting point) toward the interface of the p-type light absorption layer 3 opposite to the p-electrode 2 side, and / or at least 1 [μm] of depth (endpoint) from the interface between the p-type light absorption layer 3 and the p-electrode 2 (starting point) toward the interface of the p-type light absorption layer 3 opposite to the p-electrode 2 side.

[0024] When the copper element in the p-type light-absorbing layer 3 is considered to be 100%, the total amount of the element represented by M1 in the p-type light-absorbing layer 3 is preferably 0.00001% or more and 1% or less, more preferably 0.0001% or more and 0.1% or less, and even more preferably 0.0001% or more and 0.01% or less. If the above composition ratio does not satisfy the above range, it may become difficult for the cuprous oxide compound to have a cuprous ore-type structure, the light transmittance of the p-type light-absorbing layer 3 may decrease, or the band gap may fall outside the preferred range. It is preferable that the upper limit of the above range is satisfied for the entire p-type light-absorbing layer 3. It is preferable that the lower limit of the above range is satisfied by the entire p-type light absorbing layer 3, but it is preferable that the lower limit of the above range is satisfied within the range of at least 20% of the thickness of the p-type light absorbing layer 3 (endpoint) from the interface between the p-type light absorbing layer 3 and the p-electrode 2 (starting point) toward the interface of the p-type light absorbing layer 3 opposite to the p-electrode 2 side, and / or at least 1 [μm] of depth (endpoint) from the interface between the p-type light absorbing layer 3 and the p-electrode 2 (starting point) toward the interface of the p-type light absorbing layer 3 opposite to the p-electrode 2 side.

[0025] The number of oxygen atoms in the cuprous oxide compound is preferably between 0.48 and 0.56, with the number of copper atoms being 1. A high oxygen-to-copper ratio is undesirable because it increases the proportion of copper oxide in the cuprous oxide compound, narrowing the band gap and reducing the transparency of the p-type light-absorbing layer 3. A low oxygen-to-copper ratio is also undesirable because it increases the amount of copper in the cuprous oxide compound, reducing its transparency. Furthermore, if the oxygen-to-copper ratio does not meet the above range, it becomes difficult for the cuprous oxide compound to have a cuprite-type structure.

[0026] Preferably, 95 wt% to 100 wt% of the p-type light-absorbing layer 3 is a cuprous oxide compound; more preferably, 98 wt% to 100 wt% of the p-type light-absorbing layer 3 is a cuprous oxide compound; and even more preferably, 99 wt% to 100 wt% is a cuprous oxide compound. 100 wt% of the p-type light-absorbing layer 3 can be composed of a cuprous oxide compound.

[0027] It is preferable that the p-type light-absorbing layer 3 contains few other phases and has good crystallinity, as this increases the light transmittance of the p-type light-absorbing layer 3. The band gap of the p-type light-absorbing layer 3 can be adjusted by means such as including elements other than Cu and O in the p-type light-absorbing layer 3. The band gap of the p-type light-absorbing layer 3 is preferably 2.0 [eV] or more and 2.2 [eV] or less. With a band gap in this range, in a multi-junction solar cell in which a solar cell using Si as the light-absorbing layer is used as the bottom cell and a solar cell having the laminate 10 of the embodiment is used as the top cell, sunlight can be efficiently utilized in both the top cell and the bottom cell. It is preferable that the p-type light-absorbing layer 3 contains Sn and / or Sb.

[0028] The composition ratio of the p-type light-absorbing layer 3 described above is the overall composition ratio of the p-type light-absorbing layer 3. Furthermore, it is preferable that the compound composition ratio of the p-type light-absorbing layer 3 described above is satisfied throughout the p-type light-absorbing layer 3.

[0029] The grain size of the cuprous oxide compound is preferably 1.2 times or more the thickness of the p-type light-absorbing layer 3. A p-type light-absorbing layer 3 mainly composed of a large grain size cuprous oxide compound has good film quality, a high short-circuit current density (Jsc) when the laminate 10 is converted into a solar cell, and contributes to improved conversion efficiency when the laminate 10 is converted into a solar cell. Furthermore, even if the conversion efficiency does not significantly improve when the laminate 10 of the embodiment in which the grain size of the cuprous oxide compound is 1.2 times or more the thickness of the p-type light-absorbing layer 3 is converted into a solar cell, the improved crystallinity results in excellent light transmission of the laminate 10 and the solar cell, making it preferable for applications where light transmission is required, and also contributing to improved power generation at the bottom cell in multi-junction solar cells.

[0030] From the above viewpoint, the crystal grain size of the cuprous oxide compound is more preferably 1.2 times or more and 10 times or less (or 5 times or less) the thickness of the p-type light absorption layer 3, more preferably 1.5 times or more and 10.0 times or less (or 7.0 times or less), and even more preferably 2.0 times or more and 7.0 times or less.

[0031] The crystal grain size of the cuprous oxide compound can be confirmed, for example, by analyzing analysis spots A1 to A9 shown in Figure 2. D1 is the length in the width direction (X direction) of the laminate 10. D2 is the length in the depth direction (Y direction) of the laminate 10. For example, a scanning electron microscope (SEM) is used to obtain a surface image of the laminate 10. When analyzing a solar cell having the laminate 10, a surface image of the solar cell is obtained. It is preferable to identify the observation position from an image observed at a magnification of about 1000x and perform imaging to evaluate the grain size. The imaging magnification for evaluating the grain size should be between 100x and 20000x, and each side of each image (for example, each side of the imaging range of a rectangle) should be between 10 and 50 times the thickness of the p-type light absorption layer 3. In order to evaluate crystal sizes larger than the film thickness of the p-type light absorption layer 3, it is preferable that each image be a mosaic image obtained by combining (mosaicing) multiple raster images. From the crystals contained in the p-type light absorption layer 3 of the image, three crystals with the longest circumscribed diameters in the planar direction (perpendicular to the film thickness direction of the p-type light absorption layer 3) are selected (the crystal with the largest circumscribed diameter, the crystal with the second largest circumscribed diameter, and the crystal with the third largest circumscribed diameter). The circumscribed diameter is referred to as diameter. The diameters of the three selected crystals are determined (diameter of the crystal with the largest circumscribed diameter = d1, diameter of the crystal with the second largest circumscribed diameter = d2, diameter of the crystal with the third largest circumscribed diameter = d3). Then, the average value of the diameters of the three selected crystals ((d1+d2+d3) / 3) is calculated, and this average value is taken as the first grain size. The first grain size is determined in this way for all analysis spots, and it is evaluated whether the relationship between the crystal grain size and the thickness of the p-type light absorption layer 3 described above is satisfied with the first grain size of each analysis spot.

[0032] Figure 3 shows a schematic diagram of the surface of the p-type light-absorbing layer 3. The schematic diagram in Figure 3 is a part of the image of the analysis spot. The schematic diagram in Figure 3 is a schematic diagram that traces the grain boundaries of the actual SEM image. In Figure 3, the dashed lines are grain boundaries, and the single-dot short chain lines represent the circumcircle of one crystal. The circumcircle diameter d is the diameter of this circumcircle. The circumcircle diameter in Figure 3 is 14.5 [μm], which satisfies all of the following conditions: 1.2 times or more and 10 times or less (or 5 times or less), 1.5 times or more and 10.0 times or less (or 7.0 times or less), and 2.0 times or more and 7.0 times or less of the thickness of the p-type light-absorbing layer 3.

[0033] If, in five or more of the nine analysis spots, the first particle size of the cuprous oxide compound is 1.2 times or more the thickness of the p-type light absorption layer 3, then the diameter of the cuprous oxide compound is considered to be 1.2 times or more the thickness of the p-type light absorption layer 3. If, in five or more of the nine analysis spots, the first particle size of the cuprous oxide compound is 1.5 times or more the thickness of the p-type light absorption layer 3, then the diameter of the cuprous oxide compound is considered to be 1.5 times or more the thickness of the p-type light absorption layer 3.

[0034] If, in five or more of the nine analysis spots, the first particle size of the cuprous oxide compound is between 1.2 and 10 times (or 5 times or less) the thickness of the p-type light absorption layer 3, then the diameter of the cuprous oxide compound is considered to be between 1.2 and 10 times (or 5 times or less) the thickness of the p-type light absorption layer 3.

[0035] If, in five or more of the nine analysis spots, the first particle size of the cuprous oxide compound is between 1.5 and 10 times (or 7.0 times) the thickness of the p-type light absorption layer 3, then the diameter of the cuprous oxide compound is considered to be between 1.5 and 10 times (or 7.0 times) the thickness of the p-type light absorption layer 3.

[0036] If, in five or more of the nine analysis spots, the first particle size of the cuprous oxide compound is between 2.0 and 7.0 times the thickness of the p-type light absorption layer 3, then the diameter of the cuprous oxide compound is considered to be between 2.0 and 7.0 times the thickness of the p-type light absorption layer 3.

[0037] From the crystals contained in the p-type light absorption layer 3 obtained by analyzing each analysis spot, one crystal with the longest diameter in the planar direction (perpendicular to the film thickness direction of the p-type light absorption layer 3) is selected (the crystal with the largest circumscribed circle diameter). The diameter of the selected crystal (=d1) is defined as the second grain size.

[0038] From the above viewpoint, it is preferable that the p-type light-absorbing layer 3 contains cuprous oxide compound crystals with a particle size of 3.0 times or more the thickness of the p-type light-absorbing layer 3 (where d1 is 3.0 times or more the thickness of the p-type light-absorbing layer 3), more preferably that the p-type light-absorbing layer 3 contains cuprous oxide compound crystals with a particle size of 2.0 times or more and 12 times or less the thickness of the p-type light-absorbing layer 3 (where d1 is 2.0 times or more and 12 times or less the thickness of the p-type light-absorbing layer 3), and even more preferably that the p-type light-absorbing layer 3 contains cuprous oxide compound crystals with a particle size of 3.0 times or more and 12 times or less the thickness of the p-type light-absorbing layer 3 (where d1 is 3.0 times or more and 12 times or less the thickness of the p-type light-absorbing layer 3).

[0039] From the above viewpoint, it is preferable that the material contains cuprous oxide compound crystals with a particle size of 4.0 times or more the thickness of the p-type light absorption layer 3 (where d1 is 4.0 times or more the thickness of the p-type light absorption layer 3).

[0040] If, in one or more of the nine analysis spots, the second particle size of the cuprous oxide compound is 2.0 times or more the thickness of the p-type light absorption layer 3, then it is considered that cuprous oxide compound crystals with a diameter of 3.0 times or more the thickness of the p-type light absorption layer 3 are contained in the p-type light absorption layer 3.

[0041] If, in one or more of the nine analysis spots, the second particle size of the cuprous oxide compound is between 2.0 and 12 times the thickness of the p-type light absorption layer 3, then it is considered that cuprous oxide compound crystals with a diameter between 2.0 and 12 times the thickness of the p-type light absorption layer 3 are contained in the p-type light absorption layer 3.

[0042] If, in one or more of the nine analysis spots, the second particle size of the cuprous oxide compound is between 3.0 and 12 times the thickness of the p-type light absorption layer 3, then it is considered that cuprous oxide compound crystals with a diameter between 3.0 and 12 times the thickness of the p-type light absorption layer 3 are contained in the p-type light absorption layer 3.

[0043] The length of the thickest part of the p-type light-absorbing layer 3, as seen in the nine analysis spots, is determined in the thickness direction of the p-type light-absorbing layer 3 (the stacking direction of the p-type light-absorbing layer 3 and the p-electrode 2). The average of these nine lengths is then used as the thickness of the p-type light-absorbing layer 3.

[0044] Furthermore, it is preferable that particles with a crystal diameter of 1.5 times or more the thickness of the p-type light absorption layer 3 occupy 60% or more of the surface area of ​​the p-type light absorption layer 3. If, in five or more of the nine analysis spots, particles with a crystal diameter of 1.5 times or more the thickness of the p-type light absorption layer 3 occupy 60% or more of the surface area of ​​the p-type light absorption layer 3, it is considered that particles with a crystal diameter of 1.5 times or more the thickness of the p-type light absorption layer 3 occupy 60% or more of the surface area of ​​the p-type light absorption layer 3.

[0045] It is preferable that particles with a crystal diameter of 1.7 times or more the thickness of the p-type light-absorbing layer 3 occupy 50% or more of the surface area of ​​the p-type light-absorbing layer 3. If, in five or more of the nine analysis spots, particles with a crystal diameter of 1.7 times or more the thickness of the p-type light-absorbing layer 3 occupy 50% or more of the surface area of ​​the p-type light-absorbing layer 3, it is considered that particles with a crystal diameter of 1.7 times or more the thickness of the p-type light-absorbing layer 3 occupy 50% or more of the surface area of ​​the p-type light-absorbing layer 3.

[0046] The p-type light absorption layer 3 preferably has a p+ type (p-plus type) region on the p-electrode 2 side.

[0047] It is preferable that the p-type light absorption layer 3 has a p-type (p-minus type) region on the n-type layer side. It is preferable that the p-type light absorption layer 3 has a p-type (p-minus type) region on the n-type layer side and a p+ type (p-plus type) region on the p-electrode 2 side.

[0048] It is preferable that the cuprous oxide compound particles, which are at least 1.2 times the thickness of the p-type light absorption layer 3, are in direct contact with the surface of the p-electrode 2 facing the p-type light absorption layer 3. It is preferable that the cuprous oxide compound particles, which are at least 1.2 times the thickness of the p-type light absorption layer 3, are exposed on the surface of the p-type light absorption layer 3 opposite to the p-electrode 2 side. It is preferable that the cuprous oxide compound particles, which are at least 1.2 times the thickness of the p-type light absorption layer 3, are in direct contact with the surface of the p-electrode 2 facing the p-type light absorption layer 3 and are exposed on the surface of the p-type light absorption layer 3 opposite to the p-electrode 2 side.

[0049] Particles of the cuprous oxide compound with a crystal diameter of 1.5 times or more the thickness of the p-type light absorption layer 3 are preferably in direct contact with the surface of the p-electrode 2 facing the p-type light absorption layer 3. Particles of the cuprous oxide compound with a crystal diameter of 1.5 times or more the thickness of the p-type light absorption layer 3 are preferably exposed on the surface of the p-type light absorption layer 3 opposite to the p-electrode 2 side. Particles of the cuprous oxide compound with a crystal diameter of 1.5 times or more the thickness of the p-type light absorption layer 3 are preferably in direct contact with the surface of the p-electrode 2 facing the p-type light absorption layer 3 and exposed on the surface of the p-type light absorption layer 3 opposite to the p-electrode 2 side.

[0050] Particles of the cuprous oxide compound with a crystal diameter of 1.7 times or more the thickness of the p-type light absorption layer 3 are preferably in direct contact with the surface of the p-electrode 2 facing the p-type light absorption layer 3. Particles of the cuprous oxide compound with a crystal diameter of 1.7 times or more the thickness of the p-type light absorption layer 3 are preferably exposed on the surface of the p-type light absorption layer 3 opposite to the p-electrode 2 side. Particles of the cuprous oxide compound with a crystal diameter of 1.5 times or more the thickness of the p-type light absorption layer 3 are preferably in direct contact with the surface of the p-electrode 2 facing the p-type light absorption layer 3 and exposed on the surface of the p-type light absorption layer 3 opposite to the p-electrode 2 side.

[0051] It is preferable that cuprous oxide compound particles are present throughout the p-type light absorption layer 3, including on the p-electrode 2 side of the p-type light absorption layer 3, with a total thickness of 1.2 times or more than the thickness of the p-type light absorption layer 3.

[0052] It is preferable that there are no minute particles with a particle size of 100 nm or less (particles with a diameter of 1 / 10th or less of the film thickness) and / or voids with a diameter of 100 nm or less (particles with a diameter of 1 / 10th or less of the film thickness) at the interface between the cuprous oxide compound particles, which are 1.2 times or more the thickness of the p-type light absorption layer 3, and the p-electrode 2. It is preferable that 50% or more (preferably 70% or more, 90% or more) of the cuprous oxide compound particles, which are 1.2 times or more the thickness of the p-type light absorption layer 3, and the p-electrode 2 are in direct contact with the p-electrode 2 without the intervening of minute particles with a particle size of 100 nm or less (particles with a diameter of 1 / 10th or less of the film thickness) and / or voids with a diameter of 100 nm or less (particles with a diameter of 1 / 10th or less of the film thickness).

[0053] It is preferable that there are no minute particles with a particle size of 100 nm or less (particles with a diameter of 1 / 10th or less of the film thickness) and / or voids with a diameter of 100 nm or less (particles with a diameter of 1 / 10th or less of the film thickness) at the interface between the cuprous oxide compound particles, which are 1.5 times or more the thickness of the p-type light absorption layer 3, and the p-electrode 2. It is preferable that 50% or more (preferably 70% or more, 90% or more) of the cuprous oxide compound particles, which are 1.5 times or more the thickness of the p-type light absorption layer 3, and the p-electrode 2 are in direct contact with the p-electrode 2 without the intervening of minute particles with a particle size of 100 nm or less (particles with a diameter of 1 / 10th or less of the film thickness) and / or voids with a diameter of 100 nm or less (particles with a diameter of 1 / 10th or less of the film thickness).

[0054] It is preferable that there are no minute particles with a particle size of 100 nm or less (particles with a diameter of 1 / 10th or less of the film thickness) and / or voids with a diameter of 100 nm or less (particles with a diameter of 1 / 10th or less of the film thickness) at the interface between the cuprous oxide compound particles, which are 1.7 times or more the thickness of the p-type light absorption layer 3, and the p-electrode 2. It is preferable that 50% or more (preferably 70% or more, 90% or more) of the cuprous oxide compound particles, which are 1.7 times or more the thickness of the p-type light absorption layer 3, and the p-electrode 2 are in direct contact with the p-electrode 2 without the intervening of minute particles with a particle size of 100 nm or less (particles with a diameter of 1 / 10th or less of the film thickness) and / or voids with a diameter of 100 nm or less (particles with a diameter of 1 / 10th or less of the film thickness).

[0055] The p-type light absorption layer 3 is preferably composed of large-grained crystalline particles of a cuprous oxide compound, and it is preferable that there are no minute particles with a particle size of 100 nm or less (particles with a diameter of one-tenth or less of the film thickness) unevenly distributed on the p-electrode 2 side or elsewhere.

[0056] At a minimum, the element represented by M1 is contained within the range of at least 20% of the thickness of the p-type light absorption layer 3 (endpoint) from the interface between the p-type light absorption layer 3 and the p-electrode 2 (starting point) toward the interface of the p-type light absorption layer 3 opposite to the p-electrode 2 side, and / or at least 1 [μm] of depth (endpoint) from the interface between the p-type light absorption layer 3 and the p-electrode 2 (starting point) toward the interface of the p-type light absorption layer 3 opposite to the p-electrode 2 side, and the carrier concentration of the p-type light absorption layer 3 (average value of the entire p-type light absorption layer 3) is high, and the p-type light absorption layer 3 and If the particle size of the cuprous oxide compound in the entire p-type light-absorbing layer 3 is large, including the range from the interface with the p electrode 2 (starting point) toward the interface of the p-type light-absorbing layer 3 opposite to the p electrode 2 side (endpoint) to a depth of 20% or more of the thickness of the p-type light-absorbing layer 3, and / or the range from the interface between the p-type light-absorbing layer 3 and the p electrode 2 (starting point) toward the interface of the p-type light-absorbing layer 3 opposite to the p electrode 2 side (endpoint) to a depth of 1 [μm] or more (endpoint), then the Jsc and FF of the solar cell using the laminate 10 will improve, and this will also contribute to an improvement in conversion efficiency.

[0057] The average deviation of the surface roughness of the side of the p-type light absorption layer 3 opposite to the p-electrode 2 is preferably 50 nm or more. When the surface roughness of the side of the p-type light absorption layer 3 opposite to the p-electrode 2 is small, the side of the p-type light absorption layer 3 opposite to the p-electrode 2 has high flatness. When the surface roughness of the side of the p-type light absorption layer 3 opposite to the p-electrode 2 is large, the flatness is low. In other words, there are irregularities on the side of the p-type light absorption layer 3 opposite to the p-electrode 2. The presence of irregularities on the surface of the p-type light absorption layer 3 with good film quality (the light incident side when it is made into a solar cell) causes light to refract at the surface of the p-type light absorption layer 3, increasing the optical path length and contributing to an improvement in short-circuit current density. The side of the p-type light absorption layer 3 opposite to the p-electrode 2 is the side facing the n-electrode, which will be described later.

[0058] The average deviation of the surface roughness of the side of the p-type light absorption layer 3 opposite to the p-electrode 2 side is preferably 50 nm or more and 500 nm or less, and more preferably 55 nm or more and 300 nm or less.

[0059] The average deviation of surface roughness on the side of the p-type light absorption layer 3 opposite to the p-electrode 2 is the arithmetic mean roughness Ra, calculated using the contour curve method (JIS B0601:2013 ISO 4287:1997). The reference length is set to 20 to 50 times the thickness of the p-type light absorption layer 3 (e.g., 200 [μm]), and the surface height is obtained by measuring the portion containing the center of each analysis spot at 100 [nm] intervals. A roughness curve (cutoff values ​​λc (e.g., a value greater than or equal to the reference length but less than or equal to twice the reference length), λs (e.g., a value less than or equal to twice the measurement interval), λf (e.g., a value greater than the reference length) is obtained from the cross-sectional curve of the obtained surface height, and the roughness curve is obtained from the cutoff values ​​λc (e.g., a value greater than the reference length but less than or equal to twice the reference length), λs (e.g., a value greater than twice the reference length), and λf (e.g., a value greater than the reference length) is obtained from the cross-sectional curve of the obtained surface height (examples are λc = 400 [μm], λs = 20 [nm], and λf = 1 [mm], respectively), and the average surface of each roughness curve is obtained for analysis spots A1 to A9. The average deviation of the surface roughness on the side of the p-type light absorption layer 3 opposite to the p-electrode 2 is the average of the absolute values ​​of each surface height from the average surface. Surface roughness is preferably measured non-contact. Because surface roughness is measured non-contact, the same measurement can be performed even when the laminate 10 is made into a solar cell. Other average values ​​are also the average of the values ​​obtained at analysis spots A1 to A9.

[0060] The carrier concentration in the p-type light absorption layer 3 is 5.0 × 10⁻⁶. 14 [cm -3It is preferably as described above. When forming the p-type light absorption layer 3 by high-temperature sputtering, the crystals of the copper oxide compound grow to be larger than the film thickness of the p-type light absorption layer 3. It has been found that when the crystals of the copper oxide compound grow, the film quality improves, but when sputtering is started under high-temperature conditions, the carrier concentration tends to decrease. In the embodiment, by adopting the following film-forming method, it has been successful in achieving both an increase in the particle size of the copper oxide compound and a high carrier concentration (carrier doping). By increasing the carrier concentration with the large-particle-size copper oxide compound of the embodiment, it has been found from simulations performed by changing the carrier concentration for a solar cell provided with the p-type light absorption layer 3 having the large-particle-size copper oxide compound of the embodiment that the conversion efficiency of the high-efficiency solar cell can be further increased. Therefore, by maintaining the large particle size and increasing the carrier concentration, it contributes to the improvement of the performance of solar cells using the laminate and the like.

[0061] The carrier concentration of the p-type light absorption layer 3 is 8.0×\(10^{}\) 14 [cm\(^{}\)] -3 It is more preferably at least, and 9.0×\(10^{}\) 14 [cm\(^{}\)] -3 It is even more preferably at least, and 1.0×\(10^{}\) 15 [cm\(^{}\)] -3 It is even more preferably at least. When the carrier concentration is high, when the laminate 10 of the embodiment is used for a solar cell, it contributes to the improvement of the short-circuit current density. When the short-circuit current density is improved, the FF and conversion efficiency of the solar cell are improved.

[0062] As the carrier concentration of the p-type light absorption layer 3 becomes very high, adding impurities to the copper oxide compound may inhibit the crystal growth of the copper oxide compound. When the crystal growth is inhibited, even if the particle size of the copper oxide compound is large, it becomes several hundred [μm] or less. Since the crystals of the copper oxide compound in the p-type light absorption layer 3 are preferably large in particle size, the carrier concentration of the p-type light absorption layer 3 is preferably \(1.0×10^{}\) 18 [cm\(^{}\)] -3 or less, more preferably \(1.0×10^{}\) 17 [cm\(^{}\)] -3 or less, and even more preferably \(5.0×10^{}\) 16 [cm\(^{}\)] -3 or less.

[0063] The carrier concentration in the p-type light absorption layer 3 was calculated by measuring the Hall effect in an atmospheric environment at room temperature using the van der Pow method with an AC Hall effect measuring device manufactured by Toyo Technica Co., Ltd.

[0064] The mobility of the p-type light absorption layer 3 is 10 [cm²] 2 / (V·s) or more is preferred, and 30[cm 2 (V·s) or more is more preferable, 50[cm 2 [V·s] is even more preferable. The p-type light-absorbing layer 3 has a large particle size, low defects, and is virtually free of unintended impurities, resulting in high mobility, which contributes to improving Jsc when the laminate 10 is made into a solar cell.

[0065] The mobility of the p-type light absorption layer 3 was calculated by measuring the Hall effect in an atmospheric environment at room temperature using the van der Pow method with an AC Hall effect measuring device manufactured by Toyo Technica Co., Ltd.

[0066] Next, the method for manufacturing the laminate 10 will be described. Figure 4 shows a flowchart of the method for manufacturing the laminate 10. The method for manufacturing the laminate 10 includes a step (S01) of forming a layer mainly composed of a cuprous oxide compound on the p electrode 2 of a substrate on which an oxide transparent conductive film is formed, using a copper-based target. A vacuum step (S00) can be optionally performed before the film formation step (S01) of the layer mainly composed of the cuprous oxide compound. After the film formation step (S01) of the layer mainly composed of the cuprous oxide compound, a step (S02) can be optionally performed to oxidize the surface of the layer mainly composed of the cuprous oxide compound before the formation of the n-type layer 4.

[0067] The sputtering method can be RF sputtering, DC magnetron sputtering, DC pulsed sputtering, or a combination of RF magnetron sputtering and ion beam sputtering.

[0068] A copper-based target is a target with a copper purity of 99.99% or higher. A copper purity of 99.995% or higher is preferable, and 99.999% or higher is more preferable. By using high-purity copper as the target, a p-type light-absorbing layer 3 containing impurities as a p-type dopant can be obtained in a substantially single-phase Cu2O form. If the target contains elements included in the p-type light-absorbing layer 3 (e.g., Si), the copper purity does not have to be as specified, and a copper purity of 95% or higher is preferable, and 98% or higher is more preferable.

[0069] Figure 5 shows a schematic diagram of a manufacturing apparatus 20 on which a substrate is placed, as an example of an apparatus for manufacturing a laminate 10. The manufacturing apparatus 20 comprises a chamber 21, a substrate holder 22, a heating means 23, a target 24, an inert gas supply means 25, a reactive gas supply means 26, an exhaust means 27, and a power supply 28. Figure 5 shows a substrate on which a p electrode 2 is formed on a substrate 1 placed on the substrate holder 22.

[0070] Chamber 21 is a container that houses the substrate holder 22 of the manufacturing apparatus 20, etc. Chamber 21 is, for example, a vacuum chamber.

[0071] The substrate holder 22 is a component on which the substrate to be deposited is placed. A heating means 23 can be built into the substrate holder 22.

[0072] The heating means 23 can heat the substrate.

[0073] Target 24 is a copper-based target as described above.

[0074] The inert gas supply means 25 is a means for supplying an inert gas such as Ar into the chamber 21. If nitrogen gas is to be introduced into the chamber 21, the nitrogen gas may also be supplied into the chamber 21 by the inert gas supply means 25. The inert gas and nitrogen gas may also be supplied into the chamber 21 by the inert gas supply means 25 in separate piping.

[0075] The reactive gas supply means 26 is a means for supplying a reactive gas such as oxygen into the chamber 21. When introducing nitrogen gas into the chamber 21, the nitrogen gas may also be supplied into the chamber 21 by the reactive gas supply means 26. The oxygen gas and nitrogen gas may also be supplied into the chamber 21 by the reactive gas supply means 26 in separate piping.

[0076] The exhaust means 27 is a means for exhausting the gas inside the chamber 21 to the outside.

[0077] The power supply 28 is a means for applying voltage between the board holder 22 and the target 24.

[0078] The sputtering atmosphere is preferably an oxidizing atmosphere consisting of a mixture of an inert gas and oxygen gas. More preferably, the sputtering atmosphere consists of an inert gas and oxygen gas. Argon gas is preferred as the inert gas.

[0079] The element represented by M1 is introduced into the chamber 21 along with Cu and oxygen during sputtering. The alloy of Cu used for the Cu target 24 may contain the element represented by M1, or the Cu target 24 may contain a compound of the element represented by M1, or a cuprous oxide compound may be deposited using the Cu target 24 and the target 24 containing the element represented by M1. The gas containing the element represented by M1 may be mixed with an inert gas and an oxygen gas and included in the sputtering atmosphere. For example, Li, Na, K, Si, Ge, C, P, and Bi can each be included as compounds in the Cu target 24. For example, Al, Ga, In, Sn, and Sb can be alloyed with Cu and used as the sputtering target 24. For example, N is introduced into the sputtering chamber 21.

[0080] Sputtering is performed, for example, on a substrate in which a p-electrode 2 has been deposited on the substrate 1. Sputtering is performed on the surface of the p-electrode 2 to deposit a p-type light-absorbing layer 3 (a layer mainly composed of cuprous oxide compounds) on the p-electrode 2. Before sputtering, the substrate on which the p-electrode 2 is formed is placed in a chamber 21 on a substrate holder 22 and subjected to a 5.0 × 10⁻⁶ process. -3 It is preferable to perform a step (S00) to reduce the pressure to below [Pa]. The pressure reduction step (S00) may be performed in the sputtering chamber 21 or in a sub-chamber (not shown). Unlike sputtering, oxygen is not introduced in the pressure reduction step. The substrate 1 can be used as a substrate for a solar cell using a laminate 10. The p electrode 2 is formed, for example, by sputtering on the substrate 1.

[0081] Sputtering is performed in two temperature ranges. Sputtering in the low temperature range and sputtering in the high temperature range are performed consecutively. Performing sputtering consecutively means performing sputtering without stopping the reaction. In order to perform sputtering without stopping the reaction, the temperature range changes from the low temperature range to the high temperature range while Cu, oxygen, and the element represented by M1 are supplied to the substrate. For example, if the reaction is stopped when the temperature range changes, a p-type light absorption layer 3 will be obtained in which small-particle cuprous oxide compounds are formed on the p-electrode 2 side at the end of sputtering. In this embodiment, a p-type light absorption layer 3 that does not contain or contains few small-particle cuprous oxide compounds is preferred, therefore, it is preferable not to stop the supply of at least Cu and oxygen from the time the reaction gas is supplied and the sputtering reaction is started until the end of sputtering, including when the temperature range changes during sputtering, and it is more preferable not to stop the supply of Cu, oxygen, and the element represented by M1.

[0082] In sputtering at high temperatures, it is preferable that the element represented by M1 is present in the sputtering atmosphere, but it is also acceptable that the element represented by M1 is not present in the sputtering atmosphere.

[0083] Sputtering in the low temperature range will be described. When sputtering a layer mainly composed of cuprous oxide compounds in the low temperature range, the temperature of the substrate is 25°C to 600°C or lower, preferably 50°C or more lower than the maximum temperature in the high temperature range, more preferably 100°C or more lower than the maximum temperature in the high temperature range, and even more preferably 150°C or more lower than the maximum temperature in the high temperature range.

[0084] The sputtering time in the low temperature range is preferably 5% to 200% of the sputtering time in the high temperature range, preferably 5% to 100%, and preferably 5% to 50%. If the sputtering time in the low temperature range is short, the amount of element represented by M1 contained as an impurity in the p-type light absorption layer 3 will decrease. If the sputtering time in the low temperature range is relatively long, the crystal growth of the cuprous oxide compound may be insufficient, or the activation rate of the impurities may decrease.

[0085] For sputtering in the low temperature range, it is preferable for the temperature to rise continuously or intermittently. For example, suppose the starting temperature for the low temperature range is 100°C and the temperature rises continuously, and when it exceeds 600°C, it switches to sputtering in the high temperature range.

[0086] The average temperature of the substrate for sputtering in the low temperature range is preferably 100°C or more lower, preferably 200°C or more lower, and preferably 250°C or more lower than the average temperature of the substrate for sputtering in the high temperature range.

[0087] The minimum temperature of the substrate for sputtering in the low temperature range is preferably 550°C or lower, more preferably 500°C or lower, and even more preferably 450°C or lower.

[0088] The minimum temperature of the substrate for sputtering in the low-temperature range is preferably 50°C or higher, and more preferably 100°C or higher.

[0089] In sputtering in the low temperature range, it is preferable that the low temperature of the substrate allows for a greater number of impurities to be incorporated into the cuprous oxide compound. In sputtering in the high temperature range, crystal growth is easier, making it difficult for impurities to penetrate into the cuprous oxide compound, which is advantageous from the viewpoint of crystal growth, but disadvantageous from the viewpoint of adding impurities. If impurities are doped after forming a layer mainly composed of the cuprous oxide compound by impregnation, the distribution of impurities will be higher on the side opposite to the p electrode 2 side. From the viewpoint of improving conversion efficiency, it is preferable that the carrier concentration of the p-type light absorption layer 3 is higher overall or on the p electrode 2 side. Therefore, it is preferable to perform sputtering in the low temperature range on the p electrode 2 first, and then sputtering in the high temperature range.

[0090] Sputtering in the high-temperature range will be described. When sputtering a layer mainly composed of cuprous oxide compounds, the temperature of the substrate is preferably higher than 600°C and 1000°C or lower. Depending on the heat resistance of the substrate, the temperature of the substrate when sputtering a layer mainly composed of cuprous oxide compounds is preferably higher than 600°C and 850°C or lower. A temperature higher than 700°C and 850°C or lower is even more preferable because it allows for an even larger grain size of cuprous oxide. Even at temperatures below 600°C, a p-type light-absorbing layer 3 with transparency can be formed. However, for example, when the heating temperature during sputtering is 400°C, instead of using a suitable oxygen partial pressure (0.55xd[Pa] to 1.00xd[Pa] (deposition rate d[μm / min])), by adopting an oxygen partial pressure in the chamber 21 that takes the deposition rate into consideration as described below, an oxygen partial pressure with even better film quality can be formed.

[0091] From the viewpoint of improving film quality, the substrate temperature when sputtering a layer mainly composed of cuprous oxide compounds is more preferably 630°C to 850°C, and even more preferably 630°C to 800°C.

[0092] When the substrate temperature during sputtering is higher than 600°C but 700°C or lower, it is preferable because, for example, a general white glass substrate can be used for sputtering. When the substrate temperature during sputtering is higher than 700°C but 850°C or lower, it is preferable because, for example, a high heat-resistant white glass substrate can be used for sputtering, resulting in a higher quality film. When the substrate temperature during sputtering is higher than 850°C but 1000°C or lower, it is preferable because, for example, quartz glass can be used for sputtering, resulting in an even higher quality film.

[0093] From the perspective of depositing higher quality cuprous oxide compounds, when sputtering a layer mainly composed of cuprous oxide compounds (sputtering in the high temperature range and sputtering in the low temperature range), the oxygen partial pressure in the chamber is more preferably 0.20xd[Pa] or more and 0.50xd[Pa] or less, when the deposition rate is d[μm / min] (the unit of the deposition rate is ignored when calculating the product of the deposition rate and 0.20 to 0.50).

[0094] From the viewpoint of further improving the short-circuit current density, the oxygen partial pressure (for sputtering in the high-temperature range and sputtering in the low-temperature range) is more preferably 0.20·d to 0.45·d, and even more preferably 0.25xd [Pa] to 0.40xd [Pa], when the deposition rate is d [μm / min]. When increasing the average deviation, it is preferable to select a higher oxygen partial pressure within the above range.

[0095] The oxygen partial pressure in the chamber 21 during sputtering (sputtering in the high temperature range and sputtering in the low temperature range) is preferably between 0.01 [Pa] and 1.00 [Pa]. If the oxygen partial pressure is low, a different phase of Cu is likely to form. If the oxygen partial pressure is high, a different phase such as CuO is likely to form.

[0096] The total pressure inside the chamber 21 during sputtering (sputtering in the high temperature range and sputtering in the low temperature range) is typically between 0.1 [Pa] and 10 [Pa].

[0097] A slow deposition rate during sputtering (sputtering in the high-temperature range and sputtering in the low-temperature range) results in a longer film formation time, so a deposition rate of 0.03 [μm / min] or higher is preferable. A preferred deposition rate is 2.00 [μm / min] or lower. For example, when the film formation area is large, a fast deposition rate may reduce the homogeneity of the p-type light absorption layer 3. From the viewpoint of further improving film quality, a more preferable deposition rate is 1.00 [μm / min] or lower, and even more preferable is 0.50 [μm / min]. Considering practicality and film quality, a deposition rate of 0.04 [μm / min] or higher and 0.40 [μm / min] or lower is preferable.

[0098] An oxidation treatment may be performed after sputtering in a high temperature range. The oxidation treatment oxidizes an extremely thin area on the surface of the film deposited by sputtering. The oxidation conditions for the oxidation treatment are preferably one of the following conditions 1 to 4.

[0099] (Condition 1) In the oxidation treatment, the oxygen partial pressure is between 5,000 [Pa] and 200,000 [Pa], and the water vapor concentration is 9.4 × 10⁻⁶ -1 [g / m 3 ] 2.5 × 10 3 [g / m 3The processing temperature is 40°C to 150°C, and the processing time is 5 seconds to 150 minutes. The oxidation atmosphere (gas) contains oxygen. The oxidation atmosphere of the first, second, and fourth conditions may contain ozone at a concentration of 0.0% to 0.1% (maximum 1 Pa) of the oxygen partial pressure (or oxygen concentration). In addition to oxygen, the oxidation atmosphere may contain substances that are inevitably present in the atmosphere, such as carbon monoxide, carbon dioxide, hydrocarbons, and hydrogen. For example, substances that are inevitably present in the atmosphere, such as carbon monoxide, carbon dioxide, hydrocarbons, and hydrogen, are present in the oxidation atmosphere at a concentration of 5000 ppm or less. The oxidation atmosphere may further contain inert gases such as nitrogen and argon, or hydrogen. Since the oxidation atmosphere substantially contains no oxidizing reactive gases other than oxygen and ozone, no reactive gases other than oxygen and ozone are introduced into the chamber where the oxidation treatment is performed. Therefore, it is preferable to introduce only oxygen gas and optionally ozone and / or an inert gas into the chamber 21. The sum of the partial pressure of oxygen and the partial pressure of the inert gas as a percentage of the total pressure of the gas obtained by removing water vapor from the oxidation atmosphere (= ([partial pressure of oxygen] + [partial pressure of inert gas]) / (total pressure of the gas obtained by removing water vapor from the oxidation atmosphere)) is preferably 99.0% or more and 100% or less, and more preferably 99.3% or more and 100% or less (or 99.3% or more and 99.9% or less). Some preferred first conditions are listed below.

[0100] In the oxidation treatment, the water vapor concentration is 9.4 × 10⁻⁶ -1 [g / m 3 ] 2.5 × 10 3 [g / m 3The following conditions apply to oxidation treatment: Treatment time is 10 seconds or more but less than 5 minutes, treatment temperature is 40°C or more but less than 110°C, and oxygen partial pressure is 50,000 Pa or more but 100,000 Pa or less; Treatment time is 10 seconds or more but less than 5 minutes, treatment temperature is 110°C or more but 150°C or less, and oxygen partial pressure is 15,000 Pa or more but less than 50,000 Pa; Treatment time is 5 minutes or more but less than 10 minutes, treatment temperature is 40°C or more but less than 80°C, and oxygen partial pressure is 15,000 Pa or more but 10,000 Pa or more. The conditions are any of the following: less than 0[Pa], processing time of 10 minutes or more but less than 60 minutes, processing temperature of 40[°C] or more but less than 80[°C], and oxygen partial pressure of 15000[Pa] or more but 40000[Pa] or less; processing time of 60 minutes or more but less than 90 minutes, processing temperature of 40[°C] or more but 120[°C] or less, and oxygen partial pressure of 15000[Pa] or more but 35000[Pa] or less; or processing time of 90 minutes or more but 150 minutes or less, processing temperature of 40[°C] or more but 60[°C] or less, and oxygen partial pressure of 5000[Pa] or more but 21000[Pa] or less.

[0101] In the oxidation treatment, the oxygen partial pressure is 5000 [Pa] or more and 50000 [Pa] or less, the treatment temperature is 50 [°C] or more and 150 [°C] or less, the treatment time is 5 minutes or more and 60 minutes or less, and the water vapor concentration is 9.4 × 10⁻⁶ -1 [g / m 3 ] 2.5 × 10 1 [g / m 3 The following applies:

[0102] In the oxidation treatment, the treatment temperature is 75°C to 125°C, the oxygen partial pressure is 5000 Pa to 100000 Pa, the treatment time is 5 minutes to 45 minutes, and the water vapor concentration is 9.4 × 10⁻⁶ -1 [g / m 3 ] 2.5 × 10 1 [g / m 3 The following applies:

[0103] The processing temperature is between 80°C and 120°C, the oxygen partial pressure is between 5000 Pa and 100000 Pa, the processing time is between 10 minutes and 45 minutes, and the water vapor concentration is 9.4 × 10⁻⁶.-1 [g / m 3 ] 2.5 × 10 1 [g / m 3 ]

[0104] The conditions are one of the following: processing time of 10 seconds or more but less than 5 minutes, processing temperature of 110°C or more but less than 150°C, and oxygen partial pressure of 15,000 Pa or more but less than 50,000 Pa; processing time of 5 minutes or more but less than 10 minutes, processing temperature of 40°C or more but less than 80°C, and oxygen partial pressure of 15,000 Pa or more but less than 100,000 Pa; processing time of 10 minutes or more but less than 60 minutes, processing temperature of 40°C or more but less than 80°C, and oxygen partial pressure of 15,000 Pa or more but less than 40,000 Pa; or processing time of 90 minutes or more but less than 150 minutes, processing temperature of 40°C or more but less than 60°C, and oxygen partial pressure of 5,000 Pa or more but less than 21,000 Pa.

[0105] (Second condition) In the oxidation treatment, the oxygen partial pressure is 100 [Pa] or more and less than 5000 [Pa], the treatment temperature is 100°C or more and 300°C or less, and the treatment time is 1 second or more and 90 minutes or less. Several preferred second conditions are listed below.

[0106] In the oxidation treatment, the oxygen partial pressure is 100 [Pa] or more and less than 5000 [Pa], the treatment temperature is 125 [°C] or more and 250 [°C] or less, and the treatment time is 1 second or more and 90 minutes or less.

[0107] In the oxidation treatment, the oxygen partial pressure is between 300 [Pa] and 2000 [Pa], the treatment temperature is between 180 [°C] and 250 [°C], and the treatment time is between 5 seconds and 45 minutes.

[0108] In the oxidation treatment, the oxygen partial pressure is between 500 [Pa] and 2000 [Pa], the treatment temperature is between 180 [°C] and 250 [°C], and the treatment time is between 1 minute and 30 minutes.

[0109] In the oxidation treatment, the oxygen partial pressure is between 100 [Pa] and 2000 [Pa], the treatment temperature is between 250 [°C] and 300 [°C], and the treatment time is between 1 minute and less than 10 minutes.

[0110] In the oxidation treatment, the oxygen partial pressure is 1000 [Pa] or more and less than 5000 [Pa], the treatment temperature is 200 [°C] or more and less than 250 [°C], and the treatment time is 1 minute or more and less than 10 minutes.

[0111] In the oxidation treatment, the oxygen partial pressure is 1000 [Pa] or more and less than 5000 [Pa], the treatment temperature is 100 [°C] or more and 250 [°C] or less, and the treatment time is 10 minutes or more and 60 minutes or less.

[0112] In the oxidation treatment, the oxygen partial pressure is between 500 [Pa] and less than 5000 [Pa], the treatment temperature is between 100 [°C] and 175 [°C], and the treatment time is between 10 minutes and 30 minutes.

[0113] In the oxidation treatment, the oxygen partial pressure is between 300 [Pa] and 1500 [Pa], the treatment temperature is between 150 [°C] and 200 [°C], and the treatment time is between 10 minutes and 30 minutes.

[0114] In the oxidation treatment, the oxygen partial pressure is between 1000 [Pa] and less than 5000 [Pa], the treatment temperature is between 100 [°C] and 150 [°C], and the treatment time is between 60 minutes and 90 minutes.

[0115] (Third condition) In the oxidation treatment, the ozone partial pressure is between 5 [Pa] and 200 [Pa], the treatment temperature is between 273 [K] and 323 [K], and the treatment time is between 1 second and 60 minutes. Several preferred third conditions are listed below.

[0116] In the oxidation treatment, the ozone partial pressure is between 7 [Pa] and 100 [Pa], the treatment temperature is between 283 [K] and 308 [K], and the treatment time is between 1 minute and 30 minutes.

[0117] In the oxidation treatment, the ozone partial pressure is between 10 [Pa] and 50 [Pa], the treatment temperature is between 283 [K] and 308 [K], and the treatment time is between 1 minute and 10 minutes.

[0118] (Fourth condition) In the oxidation treatment, the treatment time is between 1 hour and 1600 hours, and the oxygen concentration is 5.0 × 10⁻⁶ -8 [g / L] or more 5.0×10 -5 The value is [g / L]. The preferred fourth condition is described below.

[0119] In the oxidation treatment, the treatment time is between 1 hour and 1600 hours, and the oxygen concentration is 5.0 × 10⁻⁶ -8 [g / L] or more 5.0×10 -5 [g / L], and the water vapor concentration is 5.0 × 10⁻⁶ -8 [g / L] or more 5.0×10 -5 The concentration is less than or equal to [g / L], and the temperature is between 0°C and 100°C.

[0120] Before and after the oxidation treatment, it is preferable to store the component on which a layer mainly composed of a cuprous oxide compound has been sputtered onto the substrate to prevent unintended oxidation reactions. After the oxidation treatment, it is preferable to store the oxidized component in an atmosphere where the oxygen partial pressure is 50 [Pa] or less and the temperature is 80 [°C] or less, more preferably 50 [°C] or less, or to continue with the deposition of the n-type layer 4 for solar cells. Before deposition of the n-type layer 4, for example, the oxidized component can be stored in an atmospheric atmosphere of 30 [°C] or less (the component temperature is the same, and so on) for 1 hour or less, preferably 30 minutes or less. Before the oxidation treatment, the component can be stored in an atmosphere where the oxygen partial pressure is 50 [Pa] or less and the temperature is 80 [°C] or less, more preferably 50 [°C] or less, or in an atmospheric atmosphere of 30 [°C] or less for 1 hour or less, preferably 30 minutes or less. These storage atmospheres may contain ozone at a concentration of 0.1% or less relative to the oxygen partial pressure.

[0121] In these storage atmospheres, the water vapor concentration (mass / volume) is 5.0 × 10⁻⁶. -8 [g / L] or more 5.0×10 -5 It is preferable that the concentration is [g / L] or less, and 5.0 × 10 -8 [g / L] or more 4.0×10 -5 [g / L] or less is more preferable.

[0122] It is preferable that these storage atmospheres do not contain plasma-generated gases.

[0123] When a component with a layer mainly composed of cuprous oxide compounds sputtered onto a substrate is cooled after sputtering or oxidation treatment, for example, when the oxygen partial pressure is 10 -6 [Pa] or more 10 4 [Pa] Below this level of atmosphere, -10 3 It is preferable to cool at a cooling rate of [K / min] or more and -0.1[K / min] or less. The temperature of the member on which the cuprous oxide compound layer is sputtered after cooling (or the temperature of the member after cooling) is preferably, for example, -80[°C] or more and 250[°C] or less.

[0124] The laminate 10 manufactured by this method has a transmittance of 50% or more for light with wavelengths between 700 nm and 1000 nm, and possesses excellent light transmission properties. The laminate 10 with excellent light transmission properties is suitable for use as a top cell in a multi-junction solar cell that can generate electricity with high efficiency even in light-transmitting solar cells and bottom cells.

[0125] (Second Embodiment) The second embodiment relates to a solar cell. Figure 6 shows a schematic cross-sectional view of the solar cell 100 of the second embodiment. As shown in Figure 6, the solar cell 100 according to this embodiment has a substrate 1, a first electrode p electrode 2, a p-type light absorption layer 3, an n-type layer 4, and a second electrode n electrode 5. Intermediate layers, not shown, may be included between the n-type layer 4 and the n electrode 5. Sunlight may be incident from either the n electrode 5 side or the p electrode 2 side, but it is more preferable for the light to be incident from the n electrode 5 side. Since the solar cell 100 of this embodiment is a transmissive solar cell, it is preferable to use it on the top cell side (light incident side) of a multi-junction solar cell. In Figure 6, the substrate 1 is provided on the opposite side of the p-type light absorption layer 3 of the p electrode 2, but the substrate 1 may also be provided on the opposite side of the n-type layer 4 of the n electrode 5. The following description will focus on the configuration shown in Figure 6, but the configuration in which the substrate 1 is provided on the n electrode 5 side is similar, except that the position of the substrate 1 is different. In the embodiment of the solar cell 100, light is incident from the n electrode 5 side toward the p electrode 2 side.

[0126] The solar cell 100 of this embodiment, when using transmissive electrodes for the p electrode 2 and n electrode 5, has high transmittance of light in the wavelength range of 700 nm to 1200 nm, and is a transmissive solar cell with a reddish (reddish-brown), yellowish, or orange color.

[0127] When elements from the n-type layer 4 diffuse into the p-type light-absorbing layer 3, and / or when elements from the p-type light-absorbing layer 3 diffuse into the n-type layer 4, a mixed region with a thickness of 20 nm or less may exist between the p-type light-absorbing layer 3 and the n-type layer 4 due to the diffusion of elements from both layers. In this mixed region, 90 atom% or less of the metal elements are those contained in the p-type light-absorbing layer 3, and 10 atom% or more of the metal elements in the mixed region are those contained in the n-type layer 4.

[0128] In cases where a mixed region exists, the p-type light-absorbing layer 3 may contain metals that are not included in the target 24 used to deposit the p-type light-absorbing layer 3, but are included in the n-type layer 4.

[0129] The n-type layer 4 is an n-type semiconductor layer. The n-type layer 4 is placed between the p-type light absorption layer 3 and the n-electrode 5. Preferably, the n-type layer 4 is provided on the p-type light absorption layer 3. The n-type layer 4 is deposited, for example, by the ALD method. An intermediate layer (not shown) may be provided between the p-type light absorption layer 3 and the n-type layer 4.

[0130] The n-type layer 4 located on the p-type light absorption layer 3 side preferably contains a compound (oxide) mainly composed of Ga. The n-type layer 4 may be a mixture of other oxides with a Ga-main component oxide, or a mixture of other elements with a Ga-main component oxide that has been doped with other elements, or a mixture of other oxides with a Ga-main component oxide that has been doped with other elements. The n-type layer 4 is a single layer or a multilayer. Of the metallic elements contained in the n-type layer 4 located on the p-type light absorption layer 3 side, it is preferable that Ga is 40 atomic percent or more, and more preferably 50 atomic percent or more. The metallic elements containing Ga in the n-type layer 4 may be tilted from the p-type light absorption layer 3 side to the n-electrode 5 side. If the n-type layer 4 is a multilayer semiconductor layer (for example, two layers), it is designated as the first n-type layer and the second n-type layer from the p-type light absorption layer 3 side. It is preferable that the element represented by M2 contained in the first n-type layer is less than the element represented by M2 contained in the second n-type layer. When the first n-type layer is a compound (oxide) mainly composed of Ga, the second n-type layer is preferably a compound (oxide) mainly composed of Zn containing Sn, etc.

[0131] The n-type layer 4 located on the p-type light absorption layer 3 side preferably contains an oxide containing the element represented by M2 and Ga. An oxide with Ga as the main component is, for example, an oxide containing the element represented by M2 and Ga. The n-type layer 4 located on the p-type light absorption layer 3 side preferably contains an oxide containing M2, which is one or more elements selected from the group consisting of H, Sn, Sb, Cu, Ag, Li, Na, K, Cs, Rb, Al, In, Zn, Mg, Si, Ge, N, B, Ti, Hf, Zr, Ca, Ce, La, Pr, and Nd, and Ga. The n-type layer 4 located on the p-type light absorption layer 3 side preferably contains 90 wt% to 100 wt% of an oxide containing M2 and Ga, which is one or more elements selected from the group consisting of H, Sn, Sb, Cu, Ag, Li, Na, K, Cs, Rb, Al, In, Zn, Mg, Si, Ge, N, B, Ti, Hf, Zr, Ca, Ce, La, Pr, and Nd. The Ga-based compound of the n-type layer 4 located on the p-type light absorption layer 3 side has an average composition of Ga h1 M2 i1 O j1 It is preferable that the oxide contains M2 and Ga, as represented by [formula]. It is preferable that h1, i1, and j2 satisfy 1.8 ≤ h1 ≤ 2.1, 0.0 ≤ i1 ≤ 0.2, and 2.9 ≤ j1 ≤ 3.1.

[0132] It is preferable that 90 wt% to 100 wt% of the n-type layer 4 located on the p-type light absorption layer 3 side is an oxide containing M2 and Ga. More preferably, 95 wt% to 100 wt% of the n-type layer 4 located on the p-type light absorption layer 3 side is an oxide containing M2 and Ga. Even more preferably, 98 wt% to 100 wt% of the n-type layer 4 located on the p-type light absorption layer 3 side is a compound represented by an oxide containing M2 and Ga. The Cu contained in the n-type layer 4 located on the p-type light absorption layer 3 side is not contained in the raw materials for forming the n-type layer 4, but rather the Cu contained in the p-type light absorption layer 3 has diffused into the n-type layer 4. If other elements are also used when forming the p-type light absorption layer 3, these elements may also diffuse into the n-type layer 4.

[0133] The thickness of the n-type layer 4 is typically between 3 nm and 100 nm. If the thickness of the n-type layer 4 is less than 3 nm, leakage current may occur if the coverage of the n-type layer 4 is poor, which may degrade the performance. If the coverage is good, the thickness is not limited to the above. If the thickness of the n-type layer 4 exceeds 50 nm, performance degradation may occur due to excessively high resistance of the n-type layer 4, or a decrease in short-circuit current may occur due to decreased transmittance. Therefore, the thickness of the n-type layer 4 is more preferably between 3 nm and 20 nm, and even more preferably between 5 nm and 20 nm.

[0134] The n electrode 5, being the electrode on the n-type layer 4 side that is light-transmitting to visible light, is preferably in direct contact with the n-type layer 4.

[0135] It is preferable to use an oxide transparent conductive film for the n electrode 5. The oxide transparent conductive film used for the n electrode 5 is preferably one or more semiconductor conductive films selected from the group consisting of indium tin oxide, aluminum-doped zinc oxide, boron-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide, titanium-doped indium oxide, indium gallium zinc oxide, and hydrogen-doped indium oxide. The dopant to the film, such as tin oxide, is not particularly limited as long as it is one or more selected from the group consisting of In, Si, Ge, Ti, Cu, Sb, Nb, Ta, W, Mo, F, and Cl. The n electrode 5 may include mesh or line-shaped electrodes to reduce the resistance of the oxide transparent conductive film. The mesh or line-shaped electrodes are not particularly limited, and may include Mo, Au, Cu, Ag, Al, Ta, and W. Graphene can also be used for the n electrode 5. Graphene is preferably laminated with silver nanowires.

[0136] The thickness of the n electrode 5 can be determined by cross-sectional observation with an electron microscope or by a step meter. There are no particular limitations, but it is typically between 30 nm and 2 μm.

[0137] The n electrode 5 is preferably formed by a method such as ALD or sputtering.

[0138] The solar cell 100 using the laminate 10 exhibits improved characteristics due to the high film quality of the p-type light-absorbing layer 3.

[0139] (Third embodiment) The third embodiment relates to a multi-junction solar cell. Figure 7 shows a conceptual cross-sectional view of the multi-junction solar cell of the third embodiment. The multi-junction solar cell 200 in Figure 7 has a solar cell (first solar cell) 100 of the second embodiment and a second solar cell 201 on the light incident side. The band gap of the light absorption layer of the second solar cell 201 is smaller than that of the p-type light absorption layer 3 of the solar cell 100 of the second embodiment. Note that the multi-junction solar cell 200 of the embodiment also includes solar cells formed by joining three or more solar cells.

[0140] Since the band gap of the p-type light-absorbing layer (cuprous oxide) 3 of the first solar cell 100 in the second embodiment is approximately 2.0 [eV] to 2.2 [eV], it is preferable that the band gap of the light-absorbing layer of the second solar cell 201 be 1.0 [eV] to 1.6 [eV]. The light-absorbing layer of the second solar cell 201 is preferably one or more compound semiconductor layers selected from the group consisting of CIGS-type and CdTe-type semiconductors with a high In content, crystalline silicon, and a perovskite-type compound.

[0141] (Fourth Embodiment) The fourth embodiment relates to a solar cell module. Figure 8 shows a perspective view of the solar cell module 300 of the fourth embodiment. The solar cell module 300 in Figure 8 is a solar cell module in which a first solar cell module 301 and a second solar cell module 302 are stacked. The first solar cell module 301 is on the light incident side and uses the solar cell 100 of the second embodiment. It is preferable to use the second solar cell 201 in the second solar cell module 302.

[0142] Figure 9 shows a cross-sectional view of the solar cell module 300. Figure 9 shows the structure of the first solar cell module 301 in detail, but does not show the structure of the second solar cell module 302. In the second solar cell module 302, the structure of the solar cell module is selected as appropriate depending on the light absorption layer of the solar cell used. The solar cell module 300 in Figure 9 includes multiple submodules 303 enclosed by dashed lines, in which multiple solar cells 100 are arranged horizontally and electrically connected in series by wiring 304. Multiple submodules 303 are electrically connected in parallel or in series. Adjacent submodules 303 are electrically connected by busbars 305.

[0143] Adjacent solar cells 100 are connected by wiring 304, with the upper n electrode 5 and the lower p electrode 2 being connected. The solar cell 100 of the fourth embodiment, like the solar cell 100 of the second embodiment, has a substrate 1, a p electrode 2, a p-type light-absorbing layer 3, an n-type layer 4, and an n electrode 5. It is preferable that both ends of the solar cell 100 in the submodule 303 are connected to a busbar 305, and the busbar 305 is configured to electrically connect multiple submodules 303 in parallel or series to adjust the output voltage with the second solar cell module 302. Note that the connection configuration of the solar cell 100 shown in the fourth embodiment is just one example, and the solar cell module can be configured with other connection configurations.

[0144] (Fifth embodiment) The fifth embodiment relates to a photovoltaic power generation system. The solar cell module of the fifth embodiment can be used as a generator to perform power generation in the photovoltaic power generation system of the fifth embodiment. The photovoltaic power generation system of the embodiment performs power generation using a solar cell module, and specifically includes a solar cell module that performs power generation, means for converting the generated electricity into power, and energy storage means for storing the generated electricity or a load for consuming the generated electricity. Figure 10 shows a configuration diagram of the photovoltaic power generation system 400 of the embodiment. The photovoltaic power generation system of Figure 10 includes a solar cell module 401 (300), a converter 402, a storage battery 403, and a load 404. Either the storage battery 403 or the load 404 may be omitted. The load 404 may also be configured to utilize the electrical energy stored in the storage battery 403. The converter 402 is a device that includes a circuit or element that performs power conversion such as voltage transformation or DC-AC conversion, such as a DC-DC converter, DC-AC converter, or AC-AC converter. The converter 402 can be configured in a way that is suitable for the generated voltage and the configuration of the battery 403 and load 404.

[0145] The solar cells in the light-receiving submodule 303 included in the solar cell module 401 generate electricity, and this electrical energy is converted by the converter 402 and stored in the battery 403 or consumed by the load 404. It is preferable to add a solar cell module 401 with a solar tracking drive device to keep the solar cell module 401 facing the sun, a light concentrator to concentrate sunlight, and devices to improve power generation efficiency.

[0146] The solar power generation system 400 is preferably used in real estate such as residences, commercial facilities, and factories, or in movable property such as vehicles, aircraft, and electronic equipment. By using the solar cells with excellent conversion efficiency of the embodiment in the solar cell module, an increase in power generation can be expected.

[0147] An example of the use of the solar power generation system 400 is shown in a vehicle. Figure 11 shows a conceptual diagram of the vehicle 500. The vehicle 500 in Figure 11 has a vehicle body 501, a solar cell module 502, a power converter 503, a storage battery 504, a motor 505, and tires (wheels) 506. The electricity generated by the solar cell module 502, which is installed on the top of the vehicle body 501, is converted by the power converter 503 and charged in the storage battery 504, or the electricity is consumed by a load such as the motor 505. The vehicle 500 can be moved by using the electricity supplied from the solar cell module 502 or the storage battery 504 to rotate the tires (wheels) 506 with the motor 505. The solar cell module 502 may not be a multi-junction type, but may consist only of a first solar cell module equipped with the solar cell 100 of the first embodiment. When a transparent solar cell module 502 is used, it is also preferable to use the solar cell module 502 as a power-generating window on the side of the vehicle body 501 in addition to the top of the vehicle body 501.

[0148] An example of the use of the solar power generation system 400 is shown as a flying object (drone). The flying object uses a solar cell module 401. The configuration of the flying object according to this embodiment will be briefly explained using the schematic diagram of the flying object 600 in Figure 12. The flying object 600 has a solar cell module 401, an airframe 601, a motor 602, a rotor 603, and a control unit 604. The solar cell module 401, motor 602, rotor 603, and control unit 604 are arranged on the airframe 601. The control unit 604 converts and adjusts the power output from the solar cell module 401. The motor 602 rotates the rotor 603 using the power output from the solar cell module 401. By using the flying object 600 with the configuration of this embodiment, a flying object that can fly using more power is provided.

[0149] The present invention will be described more specifically below based on examples, but the present invention is not limited to the following examples.

[0150] (Example A) (Example A, Comparative Example A) On a quartz glass substrate (substrate 1), ITO (In:Sn=80:20, film thickness 150 [nm]) and ATO (Sn:Sb=98:2, film thickness 100 [nm]) are deposited as p-electrodes 2 on the upper surface facing the glass. A 6.6 [μm] thick p-type light-absorbing layer 3 is formed on the ATO by sputtering in a nitrogen, oxygen, and argon gas atmosphere. The carrier concentration of the resulting laminate is measured, and the particle size is evaluated from the surface of the p-type light-absorbing layer 3 opposite to the p-electrode 2 side.

[0151] The surface of the p-type light absorption layer 3 opposite to the p-electrode 2 side is evaluated using a non-contact method. Then, the cross-section of the analysis spot is obtained and the particle size is evaluated.

[0152] If the particle size (first particle size) of the p-type light-absorbing layer 3 is 0.1 times or more but less than 0.5 times the film thickness, it is evaluated as D; if it is 0.5 times or more but 1.2 times or less the film thickness, it is evaluated as C; if it is greater than 1.2 times but less than 1.5 times the film thickness, it is evaluated as B; and if it is 1.5 times or more but 10.0 times or less the film thickness, it is evaluated as A.

[0153] The carrier concentration in the p-type light absorption layer 3 is 1.0 × 10⁻⁶ 15 [cm -3 If the value is greater than or equal to 1.0 × 10, it is evaluated as A. 15 [cm -3 ] Less than 8.0 × 10 14 [cm -3 The above is rated as B, and 8.0 × 10 14 [cm -3 ] Less than 5.0 × 10 14 [cm -3 The above is rated as C, and 5.0 × 10 14 [cm -3 Values ​​less than ] are evaluated as D.

[0154] The mobility of the p-type light absorption layer 3 is 20 [cm²]. 2 If it is greater than or equal to / (V·s), it is evaluated as A, and 20[cm 2 (V·s) Less than 10 [cm] 2 / (V·s)] or more is rated as B, and 10[cm 2 Values ​​less than / (V·s) are evaluated as C.

[0155] The manufacturing conditions for the laminates of Example A1 (Example A) and Comparative Examples A1 to A3 (Comparative Example A) are summarized in the table in Figure 13. A indicates the case where sputtering in the low temperature range and sputtering in the high temperature range are performed, B indicates the case where neither is performed, X indicates the case where N2 gas is introduced into the chamber 21 along with oxygen gas and argon during sputtering, and Y indicates the case where N2 gas is not introduced into the chamber 21 along with oxygen gas and argon during sputtering. Example A1 obtains a laminate by performing sputtering in the low temperature range followed by sputtering in the high temperature range. Comparative Example A1 obtains a laminate using the same process as Example A1, except that sputtering of the p-type light absorption layer 3 is performed in an atmosphere without N2 gas. Comparative Example A2 obtains a laminate using the same process as Example A1, except that sputtering is performed in the low temperature range but not in the high temperature range. Comparative Example A3 obtains a laminate using the same process as Example A1, except that sputtering is performed in a high temperature range instead of a low temperature range.

[0156] The results of Example A are shown in the table in Figure 14. In Example A1, where N2 gas was continuously introduced into the chamber 21 and sputtering was performed in the low temperature range and the high temperature range, the crystals grew and the carrier concentration was high. Figure 15 shows a cross-sectional SEM image of Example A1. As can be seen from the cross-section, it can be seen that crystals with a diameter significantly larger than the film thickness were formed. In Comparative Example A1, where sputtering was performed in the low temperature range and the high temperature range without introducing N2 gas into the chamber 21, the crystal growth was good, but the carrier concentration was lower than that of Example A. In addition, in Comparative Example A2, where sputtering in the high temperature range was not performed, the carrier concentration was high because N2 gas was introduced into the chamber 21 during sputtering in the low temperature range, but the crystal growth was insufficient. In addition, in Comparative Example A3, where sputtering in the low temperature range was not performed, N2 gas was introduced into the chamber 21 during sputtering in the high temperature range, but the carrier concentration was low. Furthermore, in Comparative Example A4, where sputtering in the low temperature range was not performed, N2 gas was not introduced into the chamber 21 during sputtering in the high temperature range, resulting in a low carrier concentration. From Example A, it can be seen that by performing sputtering in the low temperature range and sputtering in the high temperature range consecutively, and by introducing N2 gas into the chamber 21 at least during sputtering in the low temperature range, it is possible to achieve both crystal growth of the cuprous oxide compound and a high carrier concentration.

[0157] (Example B) In Example B, a solar cell of Reference Example B1 was obtained using a laminate equivalent to Comparative Example A4 as a reference example, and its power generation characteristics were evaluated. Simulations were performed by changing the carrier concentration of the characteristics obtained from the evaluation, and it was evaluated how the conversion efficiency of a solar cell having a large-particle p-type light-absorbing layer 3 improved with differences in carrier concentration.

[0158] (Reference example B1) On a quartz glass substrate 1, ITO (In:Sn=80:20, film thickness 150 [nm]) and ATO (Sn:Sb=98:2, film thickness 100 [nm]) are deposited on the upper surface of the side in contact with the glass as p-electrode 2. A 6 [μm] thick film is deposited on the ATO as a p-type light-absorbing layer 3 by sputtering in an oxygen and argon gas atmosphere. After the deposition of the p-type light-absorbing layer 3, a Ga2O3 film with a thickness of 11 [nm] is deposited as an n-type layer 4 (first n-layer). A ZnSnO (Zn:Sn=80:20) film with a thickness of 14 [nm] is deposited on the Ga2O3 as a second n-layer. Then, a transparent electrode 5 with a thickness of 40 [nm] and an Al content of 5% relative to Zn is deposited by ALD as n-electrode 5 to obtain solar cell 100. The first particle size of the cuprous oxide compound in the p-type light-absorbing layer 3 is 1.2 times or more the thickness of the p-type light-absorbing layer 3 (6 μm).

[0159] A solar simulator simulating an AM1.5G light source is used, and the light intensity is adjusted to achieve 1 sun using a reference Si cell under that light source. Measurements are taken under atmospheric pressure, and the temperature in the measurement room is 25°C. The voltage is swept, and the short-circuit current density Jsc (current divided by cell area) is measured. When the horizontal axis is voltage and the vertical axis is current density, the point where the curve intersects the horizontal axis is the open-circuit voltage Voc. On the measurement curve, the product of voltage and short-circuit current density is multiplied, and the points where they are maximum are Vmpp and Jmpp (maximum power points), respectively. Then the fill factor can be calculated from FF = (Vmpp * Jmpp) / (Voc * Jsc). The conversion efficiency can also be calculated from Eff. = Voc * Jsc * FF.

[0160] The characteristics of the obtained solar cell (conversion efficiency = 10.5%, carrier concentration in p-type light absorption layer 3 = 2.0 × 10) 14 Mobility = 100 [cm / (V·s)], carrier concentration in n-type layer 4 = 6.0 × 10⁻⁶ 16 [cm -3 Using ]) as a parameter, the carrier concentration of the p-type light absorption layer 3 is set to 5.0 × 10 14 (Example B1), 1.0 × 10 15 (Example B2), 5.0 × 10 15 (Example B3), 1.0 × 10 16 (Example B4), 5.0 × 1016 In place of Example B5, a simulation was performed to determine how much the conversion efficiency would change. The simulation was conducted using SCAPS (SCAPS-1D for thin film solar cells developed at ELIS, University of Gent) as the simulation software, assuming that the p-type light absorption layer 3 and the p-electrode 2 form an ohmic junction, and a simulation of a solar cell without the p-electrode 2 was performed.

[0161] The simulations showed that increasing the carrier concentration of the p-type light-absorbing layer 3 effectively improved both the front-flow transform (FF) and conversion efficiency of the solar cells in Examples B1 to B5 compared to Reference Example B1. Significant improvements in FF and conversion efficiency were observed up to Example B2, while Examples B3 and B4 showed more gradual improvements in FF and conversion efficiency compared to Example B2. The FF and conversion efficiency of Example B5 were not significantly different from Example B4. While changing parts of the base solar cell model altered the simulation results, similar results to Example B were obtained with other solar cell models. Simulations based on data from solar cells with large-particle p-type light-absorbing layers 3 indicate that using the laminate 10 of Example A1, which has a large-particle p-type light-absorbing layer 3 with a high carrier concentration, contributes to improving the conversion efficiency of the solar cell.

[0162] (Example C) (Example C1) As substrate 1, a quartz glass substrate is used, and on the side in contact with the glass, ITO (In:Sn=80:20, film thickness 150 [nm]) and ATO (Sn:Sb=98:2, film thickness 100 [nm]) are deposited as p-electrode 2. A 6.6 [μm] thick film is deposited on the ATO as a p-type light-absorbing layer 3 by sputtering in a nitrogen, oxygen, and argon gas atmosphere. Following sputtering in the low-temperature range, sputtering in the high-temperature range was performed while maintaining the supply of reaction gas, with a different temperature than in Example A1. The carrier concentration of the obtained laminate 10 is measured, and the particle size is evaluated from the surface of the p-type light-absorbing layer 3 opposite to the p-electrode 2 side.

[0163] (Example C2) A laminate 10 is obtained in the same manner as in Example C1, except that a p-type light-absorbing layer 3 is formed using a target mainly composed of Cu and further containing Si. The carrier concentration of the obtained laminate 10 is measured, and the particle size is evaluated from the surface of the p-type light-absorbing layer 3 opposite to the p-electrode 2 side.

[0164] (Comparative Example C1) A laminate 10 is obtained in the same manner as in Example C1, except that a 0.5 [μm] thick cuprous oxide compound film is deposited on ATO by sputtering in a low temperature range in a nitrogen, oxygen, and argon gas atmosphere, the reaction is stopped, and a 6 [μm] thick cuprous oxide compound film is deposited by sputtering in a high temperature range in an oxygen and argon gas atmosphere. The carrier concentration of the obtained laminate 10 is measured, and the particle size is evaluated from the surface of the p-type light absorption layer 3 opposite to the p-electrode 2 side.

[0165] In Example C, the carrier concentration and particle size are evaluated in the same manner as in Example A, and the presence or absence of small-particle cuprous oxide compounds is further evaluated. The cross-section of the laminate 10 is observed by SEM, and if there are no particles with a diameter of one-tenth or less of the film thickness on the p-electrode 2 side of the p-type light absorption layer 3, it is evaluated as X, and if there are particles with a diameter of one-tenth or less of the film thickness on the p-electrode 2 side of the p-type light absorption layer 3, it is evaluated as Y.

[0166] Figure 16 summarizes the evaluation of Example C. Although Examples C1 and C2 differ in that the impurities are nitrogen and silicon, both showed growth of cuprous oxide crystals and high carrier concentrations. In Comparative Example C1, the laminate 10 underwent both low-temperature and high-temperature sputtering, resulting in growth of cuprous oxide crystals and a high carrier concentration. However, small-particle cuprous oxide particles were formed on the p-electrode 2 side, and large-particle cuprous oxide particles were in direct contact with the p-electrode 2 via the small-particle cuprous oxide particles.

[0167] Although embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and in the implementation stage, the components can be modified and implemented without departing from the gist of the invention. Furthermore, various inventions can be formed by appropriately combining the multiple components disclosed in the above embodiments. For example, components from different embodiments may be appropriately combined, as in the modified examples.

[0168] In the specification, some elements are indicated only by their element symbols.

[0169] The following is a technical proposal for an embodiment. Technical proposal 1 A transparent substrate and A p electrode including an oxide transparent conductive film provided on the substrate, The p electrode has a p-type light-absorbing layer having a cuprous oxide compound, The crystal grain size of the cuprous oxide compound is 1.2 times or more the thickness of the p-type light absorption layer. The carrier concentration in the aforementioned p-type light absorption layer is 5.0 × 10⁻⁶ 14 [cm -3 That's all, The cuprous oxide compound comprises copper, oxygen, and optionally an element represented by M1. The laminate is characterized in that the element represented by M1 is one or more elements selected from the group consisting of Li, Na, K, Al, Ga, In, C, Si, Ge, Sn, N, P, Sb, and Bi. Technical proposal 2 The laminate according to Technical Proposal 1, wherein the element represented by M1 is Si and / or N. Technical proposal 3 The carrier concentration in the aforementioned p-type light absorption layer is 1.0 × 10⁻⁶ 18 [cm -3 The laminate described in Technical Proposal 1 or 2 below. Technical proposal 4 The laminate according to any one of the technical proposals 1 to 3, wherein the thickness of the p-type light-absorbing layer is 500 nm or more and 10 μm or less. Technical proposal 5 The mobility of the p-type light absorption layer is 10 [cm] 2A laminate described in any one of Technical Proposals 1 to 4, which is (V·s) or greater. Technical plan 6 The laminate according to any one of Technical Proposals 1 to 5, wherein when the copper element contained in the p-type light-absorbing layer is 100%, the total amount of the element represented by M1 contained in the p-type light-absorbing layer is 0.00001% or more and 1% or less. Technical proposal 7 The cuprous oxide compound is a laminate according to any one of the technical proposals 1 to 6, having a cuprous ore-type structure. Technical proposal 8 The laminate according to any one of Technical Proposals 1 to 7, wherein 95 [wt%] to 100 [wt%] of the p-type light-absorbing layer is the cuprous oxide compound. Technical proposal 9 A laminate described in any one of Technical Proposals 1 to 8, An n-type layer provided on the p-type light-absorbing layer of the laminate, An n-electrode provided on the n-type layer, A solar cell. Technical proposal 10 A multi-junction solar cell using the solar cell described in Technical Proposal 9. Technical proposal 11 A solar cell module using the solar cell described in Technical Proposal 9 or the multi-junction solar cell described in Technical Proposal 10. Technical proposal 12 A solar power generation system that generates electricity using the solar cell modules described in Technical Proposal 11. Technical proposal 13 The process includes a step of forming a layer mainly composed of a cuprous oxide compound on a p-electrode of a substrate on which an oxide transparent conductive film is formed, using a copper-based target by sputtering, The sputtering of the cuprous oxide compound layer is carried out by continuously performing sputtering in a low temperature range and sputtering in a high temperature range. The temperature of the substrate in the sputtering in the low temperature range is 25°C or higher and 600°C or lower, and is 50°C or higher lower than the highest temperature in the high temperature range. A method for manufacturing a laminate, wherein the temperature of the substrate during sputtering in the high-temperature range is higher than 600°C and 1000°C or lower. Technical proposal 14 A method for manufacturing a laminate according to Technical Proposal 13, wherein the sputtering time in the low temperature range is 5% or more and 200% or less of the sputtering time in the high temperature range. Technical proposal 15 A method for manufacturing a laminate according to technical proposal 13 or 14, wherein the average temperature of the substrate in the low-temperature range sputtering is 100°C or more lower than the average temperature of the sputtering in the high-temperature range. Technical proposal 16 A method for manufacturing a laminate according to any one of the technical proposals 13 to 15, wherein the minimum temperature of the substrate during sputtering in the low temperature range is 550°C or less. Technical proposal 17 A method for manufacturing a laminate according to any one of the technical proposals 13 to 16, wherein the minimum temperature of the substrate during sputtering in the low temperature range is 450°C or less. Technical proposal 18 A method for manufacturing a laminate according to any one of the technical proposals 13 to 17, wherein the supply of Cu, oxygen, and the element represented by M1 is not stopped from the start of the sputtering reaction until the end of the sputtering. Technical proposal 19 A method for manufacturing a laminate according to any one of Technical Proposals 13 to 18, wherein the partial pressure of oxygen in the sputtering chamber is 0.01 [Pa] or more and 0.10 [Pa] or less. Technical proposal 20 The temperature of the substrate during sputtering in the aforementioned high-temperature range is 630°C or higher and 850°C or lower. A method for manufacturing a laminate according to any one of the technical proposals 13 to 19, wherein the partial pressure of oxygen in the sputtering chamber is 0.25d or more and 0.40d or less. [Explanation of Symbols]

[0170] 10: Laminate 1: Circuit board 2 :p electrode 3: p-type light-absorbing layer 4:N-type layer 5 :n electrode 20: Manufacturing equipment 21: Chamber 22: Circuit board holder 23:Heating means 24: Target 25: Inert gas supply means 26: Reactive gas supply means 27: Exhaust means 28: Power supply 100: Solar cell 200: Multijunction solar cell 201:Second solar cell 300: Solar cell module 301: First solar cell module 302: Second solar cell module 303: Submodule 304: Wiring 305: Bus bar 400: Solar power generation system 401: Solar cell module 402: Converter 403: Storage Battery 404: Load 500: Vehicle 501: Vehicle body 502: Solar cell module 503: Power converter 504: Storage Battery 505: Motor 600: Flying object 601: Aircraft frame 602: Motor 603: Rotary blade 604: Control Unit

Claims

1. A transparent substrate and A p-electrode including an oxide transparent conductive film provided on the substrate, The p-electrode has a p-type light-absorbing layer having a cuprous oxide compound, The crystal grain size of the cuprous oxide compound is 1.2 times or more the thickness of the p-type light absorption layer. The carrier concentration in the aforementioned p-type light absorption layer is 5.0 × 10⁻⁶ １４ [cm －３ That's all, The cuprous oxide compound comprises copper, oxygen, and optionally an element represented by M1. The laminate is one or more elements selected from the group consisting of Li, Na, K, Al, Ga, In, C, Si, Ge, Sn, N, P, Sb, and Bi, represented by M1.

2. The laminate according to claim 1, wherein the element represented by M1 is Si and / or N.

3. The carrier concentration in the p-type light absorption layer is 1.0 × 10⁻⁶ １８ [cm －３ The laminate according to claim 1, wherein the laminate is as follows:

4. The laminate according to claim 1, wherein the thickness of the p-type light absorbing layer is 500 nm or more and 10 μm or less.

5. The mobility of the p-type light-absorbing layer is 10 [cm] ２ The laminate according to claim 1, wherein the ratio is 1 / (V・s) or greater.

6. The laminate according to claim 1, wherein when the copper element contained in the p-type light-absorbing layer is 100 [%], the total amount of the element represented by M1 contained in the p-type light-absorbing layer is 0.00001 [%] or more and 1 [%] or less.

7. The cuprous oxide compound is a laminate according to claim 1, having a cuprous ore-type structure.

8. The laminate according to claim 1, wherein 95 [wt%] to 100 [wt%] of the p-type light-absorbing layer is the cuprous oxide compound.

9. A laminate according to any one of claims 1 to 8, An n-type layer provided on the p-type light-absorbing layer of the laminate, An n electrode provided on the n-type layer, A solar cell.

10. A multi-junction solar cell using the solar cell described in claim 9.

11. A solar cell module using the solar cell described in claim 9.

12. A solar power generation system that generates electricity using the solar cell module described in claim 11.

13. The process includes a step of forming a layer mainly composed of a cuprous oxide compound on a p-electrode of a substrate on which an oxide transparent conductive film is formed, using a copper-based target, by sputtering. The sputtering of the cuprous oxide compound layer is carried out by continuously performing sputtering in a low temperature range and sputtering in a high temperature range. The temperature of the substrate in the sputtering in the low temperature range is 25°C or higher and 600°C or lower, and is 50°C or higher lower than the highest temperature in the high temperature range. A method for manufacturing a laminate, wherein the temperature of the substrate during sputtering in the high-temperature range is higher than 600°C and 1000°C or less.

14. The method for manufacturing a laminate according to claim 13, wherein the sputtering time in the low temperature range is 5% or more and 200% or less of the sputtering time in the high temperature range.

15. The method for manufacturing a laminate according to claim 13, wherein the average temperature of the substrate in the low temperature range sputtering is 100°C or more lower than the average temperature of the sputtering in the high temperature range.

16. The method for manufacturing a laminate according to claim 13, wherein the minimum temperature of the substrate during sputtering in the low temperature range is 550°C or less.

17. The method for manufacturing a laminate according to claim 13, wherein the lowest temperature of the substrate during sputtering in the low temperature range is 450°C or less.

18. A method for manufacturing a laminate according to any one of claims 13 to 17, wherein the supply of Cu, oxygen, and the element represented by M1 is not stopped from the start of the sputtering reaction until the end of the sputtering.

19. The method for manufacturing a laminate according to claim 18, wherein the partial pressure of oxygen in the sputtering chamber is 0.01 [Pa] or more and 0.10 [Pa] or less.

20. The temperature of the substrate during sputtering in the aforementioned high-temperature range is 630°C or higher and 850°C or lower. The method for manufacturing a laminate according to claim 18, wherein the partial pressure of oxygen in the sputtering chamber is 0.25d or more and 0.40d or less.

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