Perovskite solar cells

Abstract

We provide a perovskite solar cell that enables high integration. [Solution] The perovskite solar cell 100 comprises a transparent conductive film 10 provided on a light-transmitting substrate 1, a plurality of solar cell elements 20 provided on the transparent conductive film 10, and carbon electrodes 30 laminated on each of the plurality of solar cell elements 20 and connected to the transparent conductive film 10 via the side surface of the solar cell element 20. A groove 70 is provided between two adjacent solar cell elements 20 and the carbon electrode 30 provided on the side surface of one solar cell element 20 and the other solar cell element 20. The carbon electrode 30 is composed of flake-shaped graphite particles, and the minimum width of the groove 70 is 6 times or more and 13 times or less the maximum outer dimension of the graphite particles.

Description

Technical Field

[0001] The present invention relates to perovskite solar cells.

Background Art

[0002] Conventionally, solar cells that convert solar light energy into electrical energy have been used. As a technology related to such solar cells, for example, there is one described in Patent Document 1 whose citation is shown below.

[0003] Patent Document 1 describes a method for manufacturing a photoelectric conversion device. The photoelectric conversion device manufactured by this manufacturing method includes a substrate and a plurality of photoelectric conversion cells arranged on the substrate. On the photoelectric conversion cell, a conductive paste is provided on a transparent electrode made of a metal oxide semiconductor or the like, and the adjacent photoelectric conversion cells and transparent electrodes are separated by groove portions.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the photoelectric conversion device manufactured by the manufacturing method described in Patent Document 1, the grooves are formed by mechanical scribing. On the other hand, high integration is desirable for perovskite solar cells from the viewpoint of power supply capacity. Therefore, it is conceivable to make the grooves smaller (narrower), but in the photoelectric conversion device manufactured by the manufacturing method described in Patent Document 1, a conductive paste is used on a transparent electrode made of a metal oxide semiconductor or the like, as described above. If a carbon electrode made of carbon, graphite, etc. is used in the conductive paste, the graphite particles are pushed aside by the blade of the mechanical scribe, making it easy to generate burrs and making it difficult to make the grooves smaller. For this reason, the technology described in Patent Document 1 has room for improvement in terms of achieving high integration.

[0006] Therefore, there is a need for perovskite solar cells that can be highly integrated. [Means for solving the problem]

[0007] The characteristic configuration of the perovskite solar cell according to the present invention is that it comprises a transparent conductive film provided on a light-transmitting substrate, a plurality of solar cell elements provided on the transparent conductive film, and carbon electrodes laminated on each of the plurality of solar cell elements and connected to the transparent conductive film via the side surface of the solar cell element, wherein a groove is provided between two adjacent solar cell elements among the plurality of solar cell elements, between one solar cell element and the carbon electrode provided on the side surface of the other solar cell element, the carbon electrode is composed of flake-shaped graphite particles, and the minimum width of the groove is 6 times or more and 13 times or less the maximum outer dimension of the graphite particles.

[0008] With this characteristic configuration, the graphite particles are small relative to the width of the groove, allowing the carbon electrodes to be separated along the grain boundaries when forming the groove. This reduces the amount of graphite particles pushed aside by the blades of the mechanical scribe, making it less likely for burrs to form. Furthermore, because the graphite particles are small relative to the width of the groove, even if burrs do form, their height will be low. Therefore, the ends of the groove are less likely to connect due to burrs, making it possible to integrate perovskite solar cells according to the size of the groove. [Brief explanation of the drawing]

[0009] [Figure 1] This is a plan view of a perovskite solar cell. [Figure 2] This is a lateral cross-sectional view of a perovskite solar cell. [Figure 3] This is a partial perspective view of a perovskite solar cell. [Figure 4] This is a lateral cross-sectional view of a perovskite solar cell. [Figure 5] This is a magnified view of the groove in a lateral cross-sectional view of a perovskite solar cell. [Figure 6] This is a diagram showing a comparative example. [Figure 7] This is a diagram showing a comparative example. [Modes for carrying out the invention]

[0010] The perovskite solar cell according to the present invention is configured to be more easily integrated on a substrate. The perovskite solar cell 100 of this embodiment will be described below. However, the perovskite solar cell 100 is not limited to the following embodiment and can be modified in various ways without departing from the spirit of the invention.

[0011] Figure 1 is a plan view of the perovskite solar cell 100. Figure 2 is a cross-sectional view taken along line II-II in Figure 1. Figure 3 is a partial perspective view of the perovskite solar cell 100. Generally, a perovskite solar cell 100 is constructed by connecting multiple cells 90 in series to increase the output voltage. However, in the perovskite solar cell 100 shown in Figures 1-3 below, for the sake of ease of understanding, we will explain using one of the multiple cells 90 that the perovskite solar cell 100 has as an example.

[0012] As shown in Figures 1-3, the perovskite solar cell 100 comprises a transparent conductive film 10, a solar cell element 20, and a carbon electrode 30.

[0013] The substrate 1 is light-transmitting and functions as a support for the perovskite solar cell 100. The substrate 1 is insulating; for example, a transparent glass substrate, a frosted translucent glass substrate, or a transparent resin substrate can be used. As shown in Figure 1, the substrate 1 is rectangular when viewed along the Z direction.

[0014] As shown in Figure 2, a transparent conductive film 10, which is conductive and transparent and used as a negative electrode, is provided on the substrate 1. The orientation of the perovskite solar cell 100 during use is not particularly limited, but below, the direction from the substrate 1 toward the transparent conductive film 10 will be referred to as the "Z1 direction," the opposite direction will be referred to as the "Z2 direction," and the Z1 and Z2 directions will be collectively referred to as the "Z direction." In addition, one of the directions perpendicular to the Z direction will be referred to as the "X direction," and the directions perpendicular to the Z direction and the X direction will be referred to as the "Y direction."

[0015] The transparent conductive film 10 is formed (deposited) on one surface (the surface in the Z1 direction) of the substrate 1 by chemical vapor deposition (CVD) or sputtering. In this embodiment, the transparent conductive film 10 is formed over the entire surface of one side of the substrate 1. The transparent conductive film 10 is composed of, for example, fluorine-doped tin oxide (FTO), tin oxide (TO), tin-doped indium oxide (ITO), zinc oxide (ZnO), aluminum-doped zinc oxide (AZO), etc. During the patterning process of the transparent conductive film 10, grooves 11 extending along the Y direction are formed on the transparent conductive film 10. Therefore, these grooves 11 divide the transparent conductive film 10 on the substrate 1 into a first transparent conductive film 10A and a second transparent conductive film 10B.

[0016] A solar cell element 20 is provided on the transparent conductive film 10 (on the Z1 direction). The solar cell element 20 converts light energy into electrical energy. The solar cell element 20 has an electron transport layer 21, a photoelectric conversion layer 22, and a hole transport layer 23, and the electron transport layer 21, photoelectric conversion layer 22, and hole transport layer 23 are arranged in this order along the Z1 direction. When the perovskite solar cell 100 is viewed along the Z direction, each of the electron transport layer 21, photoelectric conversion layer 22, hole transport layer 23, and carbon electrode 30 is rectangular in shape, and in this embodiment, when the perovskite solar cell 100 is viewed along the Z direction, the electron transport layer 21, photoelectric conversion layer 22, and hole transport layer 23 are configured to have the same outer shape as each other.

[0017] The electron transport layer 21 is disposed on the surface of the transparent conductive film 10 on the Z1 direction side. The electron transport layer 21 is formed using titanium dioxide (TiO2). Thereby, it becomes possible to secure a large surface area for laminating the perovskite layer used as the photoelectric conversion layer 22. The electron transport layer 21 allows electrons (free electrons) received from the photoelectric conversion layer 22 to pass through (transport electrons). In the present embodiment, the electron transport layer 21 includes an insulating layer 211 that enters the groove portion 11 described above. The insulating layer 211 divides the transparent conductive film 10 into two parts, the first transparent conductive film 10A and the second transparent conductive film 10B described above (in the example shown in FIG. 2, it is divided into two parts along the X direction). Electrons can move in the direction along the Z direction in the electron transport layer 21, but it is difficult for them to move in the directions orthogonal to the Z direction (X direction and Y direction), and the movement between the two sections of the transparent conductive film 10 is restricted. Note that the electron transport layer 21 may be referred to as a "blocking layer" because it restricts the movement of electrons.

[0018] Since the substrate 1, the transparent conductive film 10, and the electron transport layer 21 have light transmissivity, light such as sunlight and indoor light is guided to the photoelectric conversion layer 22 without being absorbed (or hardly absorbed) by the substrate 1, the transparent conductive film 10, and the electron transport layer 21.

[0019] The photoelectric conversion layer 22 absorbs light energy and converts it into electrical energy. Specifically, the photoelectric conversion layer 22 absorbs light, moves the excited electrons and holes, and performs photoelectric conversion. The photoelectric conversion layer 22 includes a perovskite layer composed of organic and inorganic perovskite compounds. Specifically, the perovskite layer is formed by reacting a compound composed of lead and halogen element X (PbX2, X = halogen element) with methylammonium iodide (CH3NH3I: hereinafter may be abbreviated as "MAI"). The photoelectric conversion layer 22 further includes a porous semiconductor oxide layer (for example, a porous titanium layer). After infiltrating and drying a solution containing lead and halogen element X (for example, a PbI2 N,N-dimethylformamide solution) inside the pores of this porous semiconductor oxide layer, and then immersing it in a mixed solution of MAI, crystals of a perovskite compound (when X = I, CH3NH3PbI3) that forms the perovskite layer are generated. The halogen element X can be, for example, iodine, bromine, chlorine, etc., and it is particularly preferable to use iodine with high morphological stability.

[0020] The hole transport layer 23 allows the holes received from the photoelectric conversion layer 22 to pass through (transport the holes). The hole transport layer 23 includes, for example, an organic compound such as chlorobenzene as a material. A carbon electrode 30 used as a positive electrode is disposed on the hole transport layer 23 (the surface on the Z1 direction side).

[0021] The carbon electrode 30 is laminated on the solar cell element 20. That is, the carbon electrode 30 is disposed on the surface of the solar cell element 20 on the Z1 side. In the present embodiment, the carbon electrode 30 is composed of including graphite particles. The carbon electrode 30 is formed by applying (coating) a paste containing graphite particles on the solar cell element 20 and drying or firing it.

[0022] As shown in Figures 2 and 3, the carbon electrode 30 is electrically connected to the transparent conductive film 10 (in this embodiment, the second transparent conductive film 10B) via each side of the solar cell element 20 along the Z direction from the Z1-direction side of the hole transport layer 23. For this reason, the carbon electrode 30 includes a connection portion 31 that is positioned on the Z1-direction side (a portion of the area) of the transparent conductive film 10 (second transparent conductive film 10B). That is, the carbon electrode 30 is electrically insulated from the first transparent conductive film 10A, which is used as one terminal (negative terminal) in a single cell 90, and is electrically connected to the second transparent conductive film 10B, which is used as the other terminal (positive terminal) in a single cell 90, via the connection portion 31.

[0023] A pair of busbars B are provided on the Z1-direction side of the transparent conductive film 10. Each pair of busbars B is arranged (stacked) on the Z1-direction side of the transparent conductive film 10 outside the solar cell element 20 in the X direction, as shown in Figure 1. Each pair of busbars B is positioned on a portion of the Z1-direction side of the transparent conductive film 10, spaced apart from the solar cell element 20. One of the pair of busbars B is positioned on the first transparent conductive film 10A, and the other of the pair of busbars B is positioned on the second transparent conductive film 10B. The pair of busbars B are made from materials such as elemental metals like gold, platinum, silver, and copper, their alloys, and oxide conductors such as FTO and ITO.

[0024] The coating layer 40 is insulating and is positioned on the Z1 direction side of the solar cell element 20 and the transparent conductive film 10 so as to cover the solar cell element 20. Specifically, the coating layer 40 is in contact with the Z1 direction side surface (a surface perpendicular to the Z direction), the X direction side (a surface perpendicular to the X direction), and the Y direction side (a surface perpendicular to the Y direction) of the carbon electrode 30 of the solar cell element 20. In addition, a part of the coating layer 40 is also positioned on a part of the Z1 direction side surface of the transparent conductive film 10. The coating layer 40 may be a film-like (sheet-like) member. The coating layer 40 may be, for example, a porous film, a mesh sheet, an embossed sheet, etc., and may contain materials such as resin (PPS: polyphenylene sulfide resin) or glass.

[0025] As shown in Figure 2, the perovskite solar cell 100 consists of a laminate 60 comprising a substrate 1, a transparent conductive film 10, a solar cell element 20, a carbon electrode 30, and a coating layer 40, which is sealed by a first sheet 51 and a second sheet 52 via a sealing layer 50.

[0026] The first sheet 51 is provided on one side of the laminate 60 in the lamination direction in which the transparent conductive film 10 and the solar cell element 20 are laminated. In this embodiment, the one side in the lamination direction corresponds to the Z2 direction. Therefore, the first sheet 51 is provided on the Z2 direction side of the substrate 1. Here, since light is incident on the perovskite solar cell 100 from the Z2 direction side as described above, it is preferable that the first sheet 51 be transparent.

[0027] The second sheet 52 is provided on the other side of the laminate 60 in the lamination direction. In this embodiment, the other side of the lamination direction corresponds to the Z1 direction. Therefore, the second sheet 52 is provided on the Z1 direction side of the laminate 60.

[0028] The sealing layer 50 is placed between one of the first sheet 51 and the second sheet 52 and the laminate 60. In this embodiment, as shown in Figure 2, the sealing layer 50 is placed between the second sheet 52 and the laminate 60, and the surface of the substrate 1 on the Z2 direction and the first sheet 51 are facing each other (in contact).

[0029] The sealing layer 50 is positioned to cover the laminate 60. As shown in Figure 2, the area of ​​the sealing layer 50 in a plan view is larger than the area of ​​the laminate 60. The sealing layer 50 adheres closely to the laminate 60 and protects the laminate 60 from external forces acting on the perovskite solar cell 100.

[0030] In the example shown in Figure 2, the sealing layer 50 is provided only between the second sheet 52 and the laminate 60, but the sealing layer 50 may also be provided between the first sheet 51 and the laminate 60.

[0031] Here, Figures 1-3 show an example where one cell 90 is provided on the substrate 1, but in reality, multiple cells 90 are provided on the substrate 1.

[0032] Figure 4 shows a perovskite solar cell 100 having multiple cells 90 (three in the example in Figure 4). For ease of understanding, the three cells 90 will be referred to as cell 91, cell 92, and cell 93 below.

[0033] As shown in Figure 4, grooves 11 are formed in a transparent conductive film 10 provided on a substrate 1. Multiple (three in the example of Figure 4) solar cell elements 20 are provided on this transparent conductive film 10. Furthermore, carbon electrodes 30 are laminated on each of the multiple solar cell elements 20. In the following, for ease of understanding, the three solar cell elements 20 will be referred to as solar cell element 20A, solar cell element 20B, and solar cell element 20C when distinguishing between them.

[0034] A groove 70 is provided between two adjacent solar cell elements 20 among the multiple solar cell elements 20, between one solar cell element 20 and the carbon electrode 30 provided on the side surface of the other solar cell element 20. The multiple solar cell elements 20 are solar cell elements 20A, 20B, and 20C. Two adjacent solar cell elements 20 correspond to solar cell elements 20A and 20B, and solar cell elements 20B and 20C. The carbon electrode 30 provided on the side surface of the solar cell element 20 corresponds to the connection portion 31.

[0035] Therefore, among the solar cell elements 20A, 20B, and 20C, a groove 70 is provided between the solar cell element 20B and the connecting portion 31 provided on the side surface of solar cell element 20A in solar cell elements 20A and solar cell element 20B, and a groove 70 is provided between the solar cell element 20C and the connecting portion 31 provided on the side surface of solar cell element 20B in solar cell elements 20B and 20C.

[0036] The carbon electrode 30 is composed of flake-shaped graphite particles. "Flake-shaped" means thin, plate-like (leaf-like). Therefore, flake-shaped graphite particles correspond to graphite consisting of thin, plate-like crystals. The carbon electrode 30 is formed by mixing such flake-shaped graphite particles with a conductive additive and a binder in a predetermined ratio.

[0037] In this embodiment, graphite particles with a maximum external dimension of 8 μm or less are used. The external dimension of the graphite particle refers to the maximum external dimension of the flaky graphite particle in a plan view. In particular, it is preferable that the maximum external dimension of the graphite particle be 5 μm or less, and even more preferably 4 μm or less.

[0038] The perovskite solar cell 100 is configured such that the minimum width of the groove 70 is at least 6 times and no more than 13 times the maximum outer dimensions of the graphite particles. As described above, in this embodiment, graphite particles with a maximum outer dimension of 8 μm or less are used. In this case, the minimum width of the groove 70 should be at least 48 μm and no more than 104 μm. With this configuration, even if burrs are generated on the carbon electrode 30 when the groove 70 is formed by mechanical scribing, the graphite particles contained in the carbon electrode 30 are caused by the blade of the mechanical scribe, but the burrs can be flattened by the pressurizing work in the subsequent sealing process where the sealing layer 50 is provided, preventing short circuits between two adjacent carbon electrodes 30 via the groove 70. In addition, since the width of the groove 70 can be secured, discharge across two adjacent carbon electrodes 30 can be prevented. Furthermore, by setting the minimum width of the groove 70 to 104 μm or less, the integration density of the perovskite solar cell 100 can be increased. Therefore, the range in which the perovskite solar cell 100 can be used can be broadened.

[0039] Furthermore, in this embodiment, the carbon electrode 30 has a density of 1.0 g / cm³. 3 The structure is as described above. As a result, the flaky graphite particles overlap each other, making it difficult for the graphite particles to fall off the wall surface of the groove 70 formed by the mechanical scribing process.

[0040] The carbon electrode 30 contains graphite particles oriented along the surface of the substrate 1 on which the transparent conductive film 10 is provided. Graphite particles are flaky graphite particles (hereinafter also referred to as flaky graphite). In this embodiment, the surface of the substrate 1 on which the transparent conductive film 10 is provided is the surface of the substrate 1 that aligns with the XY plane. The oriented state does not only mean that all graphite particles are parallel to the XY plane, but also that at least some of the graphite particles contained in the carbon electrode 30 are tilted with respect to the Z direction. In other words, the oriented state includes a state in which many of the graphite particles (for example, about 70%-90% of the graphite particles contained in the carbon electrode 30) are tilted with respect to the Z direction. In this embodiment, the carbon electrode 30 contains flaky graphite particles that are tilted with respect to the Z direction on the surface of the substrate 1 that aligns with the XY plane.

[0041] Figure 5 shows that the maximum external dimension of the flaky graphite is 4 μm or less, and the density is 1.0 g / cm³. 3 The above diagram shows an enlarged view of the groove 70 when the minimum width of the groove 70 is 50 μm or less. For ease of understanding, graphite particles are indicated with diagonal lines inside, and the conductive additive is filled in black. A binder is filled between the graphite particles and the conductive additive. In this case, as shown in Figure 5, the outer dimensions of the flake-like graphite are sufficiently small compared to the width of the mechanical scribe blade, so the groove 70 is easily formed along the grain boundaries, reducing the number of graphite particles pushed aside by the mechanical scribe blade and making it less likely for burrs to form. Also, even if burrs do form, they are short because the graphite particles are small. Therefore, as described above, two adjacent carbon electrodes 30 do not short-circuit through the groove 70. In addition, since the flake-like graphite is densely overlapping, the graphite particles are less likely to peel off (less likely to fall off). Therefore, it is possible to make it even less likely for burrs to form. In this way, the width of the groove 70 can be reduced, allowing for a higher density of cells 90.

[0042] Figure 6 shows a comparative example. Figure 6 shows an enlarged view of the groove 70 when carbon nanotubes with a length of about 15-20 μm are used and the minimum width of the groove 70 is about 200 μm. In this case, as shown in Figure 6(A), the outer dimensions of the flake graphite are large and the density is low, so the flake graphite does not overlap densely, and burrs are generated on the opening side of the groove 70. When pressure is applied to seal a cell 90 having carbon electrodes 30 in this state with the first sheet 51 and the second sheet 52 via the sealing layer 50, the burrs that were standing on the opening side of the groove 70 are pressed down, as shown in Figure 6(B). Therefore, two adjacent carbon electrodes 30 connect to each other via the groove 70 (short-circuiting both ends of the groove 70), or there is a possibility that they will connect. For this reason, the cell 90 cannot be highly integrated.

[0043] Furthermore, a comparative example is shown in Figure 7. Figure 7 shows an enlarged view of the groove 70 when the carbon electrode 30 is formed using spherical small-particle graphite. In this case, as shown in Figure 7(A), there are many grain boundaries of the small-particle graphite in the carbon electrode 30, but the area in which the small-particle graphite particles contact each other is small, so as shown in Figure 7(B), the small-particle graphite is likely to fall off near the groove 70, causing defects. Consequently, the cross-sectional area of ​​the carbon electrode 30 becomes smaller, and power loss increases.

[0044] By configuring it as described above, burrs are less likely to form in the groove 70, making it possible to highly integrate the cells 90. As a result, the width of the groove 70 can be reduced according to the outer dimensions of the flake graphite, making it possible to highly integrate the perovskite solar cell 100.

[0045] The perovskite solar cell 100, configured in this way, generates electricity as follows. When light such as sunlight or indoor light is incident from the side of the substrate 1 (the side in the Z2 direction), most of the light passes through the substrate 1 and the electron transport layer 21 and reaches the photoelectric conversion layer 22. When the photoelectric conversion layer 22 absorbs light energy, some of the electrons in the valence band of the photoelectric conversion layer 22 are excited to the conduction band, and holes are generated where the excited electrons were. To prevent the generated holes from recombining with electrons and causing the charge to disappear, the electrons are attracted to the electron transport layer 21 and then move to the transparent conductive film 10, and the holes are attracted to the hole transport layer 23 and then move to the carbon electrode 30. As a result, a potential difference is created between the transparent conductive film 10 and the carbon electrode 30, enabling the perovskite solar cell 100 to generate electricity. Although the electrons moving through the electron transport layer 21 move smoothly along the Z2 direction and reach the transparent conductive film 10, as described above, their movement in the direction perpendicular to the Z direction (X direction) is restricted by the insulating layer 211. In other words, the perovskite solar cell 100 is configured so that the transparent conductive film 10 and the carbon electrode 30 do not short-circuit with each other.

[0046] [Other Embodiments] Next, other embodiments of the perovskite solar cell 100 will be described.

[0047] In the above embodiment, it was explained that the maximum external dimension of the graphite particles is 8 μm or less. However, the maximum external dimension of the graphite particles may be greater than 8 μm.

[0048] In the above embodiment, the carbon electrode 30 has a density of 1.0 g / cm³. 3 The above explanation was given. However, the carbon electrode 30 has a density of 1.0 g / cm³. 3 It is acceptable to be less than [a certain value].

[0049] In the above embodiment, the carbon electrode 30 was described as containing graphite particles oriented along the surface of the substrate 1 on which the transparent conductive film 10 is provided. However, the carbon electrode 30 may also contain graphite particles that are not oriented along the surface of the substrate 1 on which the transparent conductive film 10 is provided.

[0050] [Summary of the above embodiment] The following is an overview of the perovskite solar cell 100 described above.

[0051] (1) The perovskite solar cell 100 comprises a transparent conductive film 10 provided on a light-transmitting substrate 1, a plurality of solar cell elements 20 provided on the transparent conductive film 10, and carbon electrodes 30 laminated on each of the plurality of solar cell elements 20 and connected to the transparent conductive film 10 via the side surface of the solar cell element 20, wherein a groove 70 is provided between two adjacent solar cell elements 20 and the carbon electrode 30 provided on the side surface of one solar cell element 20 and the other solar cell element 20, and the carbon electrode 30 is composed of flake-shaped graphite particles, and the minimum width of the groove 70 is 6 times or more and 13 times or less the maximum outer dimension of the graphite particles.

[0052] With this configuration, because the graphite particles are small relative to the width of the groove 70, the carbon electrodes 30 can be separated along the grain boundaries when forming the groove 70. This reduces the amount of graphite particles pushed aside by the blades of the mechanical scribe, making it less likely for burrs to form. Furthermore, because the graphite particles are small relative to the width of the groove 70, even if burrs do form, their height will be low. Therefore, the ends of the groove 70 are less likely to connect due to burrs, making it possible to integrate perovskite solar cells 100 according to the size of the groove 70.

[0053] (2) In the perovskite solar cell 100 described in (1), it is preferable that the maximum external dimension of the graphite particles is 8 μm or less.

[0054] This configuration allows for a reduction in the width of the groove 70, making it possible to further integrate the perovskite solar cell 100.

[0055] (3) In the perovskite solar cell 100 described in (1) or (2), the carbon electrode 30 has a density of 1.0 g / cm³. 3 The above is preferable.

[0056] With this configuration, since the graphite particles are densely overlapping, even in the separated cross-section of the carbon electrode 30 by mechanical scribing, the graphite particles overlap each other and are less likely to fall off.

[0057] In the perovskite solar cell 100 described in (4)(3), it is preferable that the carbon electrode 30 contains graphite particles oriented along the surface of the substrate 1 on which the transparent conductive film 10 is provided.

[0058] With this configuration, the flaky graphite particles are oriented along the surface of the substrate 1 on which the transparent conductive film 10 is provided, making it easier for the graphite particles to overlap. Therefore, even in the separated cross-section of the carbon electrode 30 by mechanical scribing, the graphite particles overlap each other and are less likely to fall off. [Industrial applicability]

[0059] The technology described herein can be used in perovskite solar cells. [Explanation of symbols]

[0060] 1: Substrate, 10: Transparent conductive film, 20: Solar cell element, 30: Carbon electrode, 70: Groove, 100: Perovskite solar cell

Claims

1. A transparent conductive film provided on a light-transmitting substrate, A plurality of solar cell elements provided on the transparent conductive film, The device comprises carbon electrodes stacked on each of the multiple solar cell elements and connected to the transparent conductive film via the side surface of the solar cell element, In a plurality of solar cell elements, a groove is provided between two adjacent solar cell elements and the carbon electrode provided on the side surface of one solar cell element and the other solar cell element. The carbon electrode is composed of flaky graphite particles, A perovskite solar cell in which the minimum width of the groove is 6 times or more and 13 times or less the maximum outer dimensions of the graphite particles.

2. The perovskite solar cell according to claim 1, wherein the maximum value of the outer dimensions of the graphite particles is 8 μm or less.

3. The carbon electrode has a density of 1.0 g / cm³. ３ The perovskite solar cell according to claim 1 or 2, as described above.

4. The perovskite solar cell according to claim 1 or 2, wherein the carbon electrode includes the graphite particles in a state in which they are oriented along the surface of the substrate on which the transparent conductive film is provided.

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