Method for manufacturing solar cell

Abstract

The present invention addresses the problem of providing a method for manufacturing a solar cell which eliminates the need for cutting when manufacturing a perovskite-type solar cell and which is capable of manufacturing a high-quality solar cell in which there are no instances of contamination caused by cutting chips, damage to an electrode layer as caused by the cutting, or other adverse events. The present invention overcomes the problem by using a method for manufacturing a solar cell having a first electrode layer (14), a functional layer having a perovskite layer (18), and an upper layer (24) in the stated order and furthermore having wall parts (28, 30) penetrating the functional layer, wherein wall parts (28, 30) are formed before forming the upper layer (24).

Description

Solar cell manufacturing method

[0001] The present invention relates to a method for manufacturing a perovskite solar cell.

[0002] Perovskite solar cells are known, which have a perovskite layer containing a perovskite compound as a photoelectric conversion layer. Perovskite solar cells are expected to have a high photoelectric conversion rate, and can be manufactured by a coating method (printing), which significantly reduces manufacturing costs. Furthermore, perovskite solar cells can also be made flexible, enabling a variety of applications that are difficult with solar cells using inorganic semiconductors.

[0003] An example of a perovskite solar cell is conceptually shown in Figure 5. The solar cell 100 shown in Figure 5 has, from the bottom in the figure, a substrate 102, a patterned first electrode layer 104, an electron transport layer (ETL layer) 106, a perovskite layer 108, a hole transport layer (HTL layer) 110, a second electrode layer 112, and an insulating layer 114.

[0004] 5, the solar cell 100 has an insulating wall 118 that penetrates from the second electrode layer 112 to the electron transport layer 106, from the insulating layer 114 to the first electrode layer 104, and is made of the same material as the insulating layer 114. The solar cell 100 also has a current-carrying wall 120 that penetrates from the hole transport layer 110 to the electron transport layer 106, from the second electrode layer 112 to the first electrode layer 104, and is made of the same material as the second electrode layer 112. In the solar cell 100, the insulating wall 118 forms individual solar cell units. In addition, in the solar cell 100, the current-carrying walls 120 connect the solar cell units in series.

[0005] Here, the insulating wall 118 and the current-carrying wall 120 are formed by cutting each layer as described in Patent Document 1. An example of this is conceptually shown in FIG.

[0006] In manufacturing this solar cell 100, a laminate is prepared in which a first electrode layer 104 patterned according to each solar cell is formed on the surface of a substrate 102. As shown in the first row of Figure 6 (top row of Figure 6), an electron transport layer 106, a perovskite layer 108, and a hole transport layer 110 are formed on the first electrode layer 104 of this laminate by, for example, a coating method. During the formation of the electron transport layer 106, the spaces between each solar cell of the patterned first electrode layer 104 are filled with the material forming the electron transport layer 106.

[0007] Next, as shown in the second row of Fig. 6 , cutting is performed so as to penetrate from the hole transport layer 110 to the electron transport layer 106, forming a groove 120a that extends from the upper surface of the hole transport layer 110 in the figure to the first electrode layer 104. Next, a second electrode layer 112 is formed on the hole transport layer 110 by, for example, a coating method. At this time, the material for forming the second electrode layer 112 is also filled into the groove 120a. As a result, a current-carrying wall 120 made of the same material as the second electrode layer 112 is formed, as shown in the third row of Fig. 6 .

[0008] Next, as shown in the fourth row of FIG. 6 (the lower row of FIG. 6 ), cutting is performed so as to penetrate from the second electrode layer 112 to the electron transport layer 106, forming a groove 118a that extends from the upper surface of the second electrode layer 112 in the drawing to the first electrode layer 104. Finally, an insulating layer 114 is formed on the second electrode layer 112, for example, by a coating method. At this time, the material for forming the insulating layer 114 is also filled into the groove 118a. As a result, an insulating wall 118 made of the same material as the insulating layer 114 is formed, as shown in FIG. 5 , and the solar cell 100 is fabricated.

[0009] Japanese Patent Application Laid-Open No. 2018-170476

[0010] As described above, both the insulating wall 118 and the current-carrying wall 120 are formed by cutting the perovskite layer 108 or the like to form a groove, and then filling this groove with the material for forming each layer when forming the second electrode layer 112 and the insulating layer 114.

[0011] As shown in Patent Document 1, this cutting is performed by laser cutting, mechanical cutting, or the like. The generation of cutting debris is unavoidable during cutting. Therefore, the cutting debris adheres to and contaminates other layers, degrading the performance of each layer and ultimately the performance of the solar cell. Furthermore, the electron transport layer 106, perovskite layer 108, and hole transport layer 110 are very thin, having a total thickness of approximately 1 μm. Therefore, when cutting to form the grooves, the first electrode layer 104 may also be cut, potentially resulting in damage to the first electrode layer 104.

[0012] An object of the present invention is to solve these problems of the conventional technology and to provide a method for manufacturing solar cells that eliminates the need for cutting, which has been essential in the manufacture of perovskite solar cells, and that prevents contamination from cutting debris and damage to the electrode layer due to cutting, thereby enabling the manufacture of high-quality solar cells.

[0013] To achieve these objects, the present invention has the following configurations. [1] A method for manufacturing a solar cell comprising a first electrode layer, a functional layer having at least a perovskite layer, and an upper layer having one or more layers stacked in this order, and further comprising a wall portion penetrating the functional layer in the stacking direction of the first electrode layer, the functional layer, and the upper layer, wherein the wall portion is formed before forming the upper layer. [2] A method for manufacturing a solar cell according to [1], wherein at least one of a second electrode layer and an insulating layer is formed as the upper layer. [3] A method for manufacturing a solar cell according to [1] or [2], wherein the wall portion is formed before forming the functional layer, and then the upper layer is formed. [4] A method for manufacturing a solar cell according to [1] or [2], wherein the functional layer and the wall portion are formed in parallel, and then the upper layer is formed. [5] A method for manufacturing a solar cell according to [1] or [2], wherein one or more layers other than a perovskite layer are formed as the functional layer, wherein the first layer of the functional layer and the wall portion are formed in parallel, and then the remaining layers of the functional layer are formed, and then the upper layer is formed. [6] The method for manufacturing a solar cell according to any one of [1] to [5], wherein the material for forming at least one of the wall portions is the same as the material for forming at least one of the upper layers. [7] The method for manufacturing a solar cell according to any one of [2] to [6], wherein the wall portions are formed from at least one of the same material as the second electrode layer and the same material as the insulating layer. [8] The method for manufacturing a solar cell according to any one of [1] to [7], wherein the functional layer is formed from at least one of an electron transport layer and a hole transport layer in addition to a perovskite layer. [9] The method for manufacturing a solar cell according to any one of [1] to [8], wherein the functional layer, the wall portions, and the upper layer are formed on a substrate having a first electrode layer.

[10] The method for manufacturing a solar cell according to [9], wherein the functional layer, the wall portions, and the upper layer are formed while the substrate is being transported.

[0014] According to the present invention, it is possible to manufacture high-quality perovskite solar cells without the need for cutting, without contamination from cutting debris, and without damage to the electrode layer due to cutting.

[0015] Fig. 1 is a diagram conceptually showing an example of a solar cell manufactured by the solar cell manufacturing method of the present invention. Fig. 2 is a conceptual diagram for explaining thermal transfer. Fig. 3 is a conceptual diagram for explaining an example of a solar cell manufacturing method of the present invention. Fig. 4 is a conceptual diagram for explaining another example of a solar cell manufacturing method of the present invention. Fig. 5 is a diagram conceptually showing an example of a solar cell manufactured by a conventional solar cell manufacturing method. Fig. 6 is a conceptual diagram for explaining a conventional solar cell manufacturing method.

[0016] The solar cell manufacturing method of the present invention will be described in detail below with reference to preferred embodiments shown in the accompanying drawings. The following drawings are conceptual diagrams for explaining the present invention. Therefore, the shape, size, thickness, and positional relationships of each component, such as their placement and spacing, do not necessarily correspond to the actual ones. For example, in FIG. 1 , as with many drawings showing the layer structure of a perovskite solar cell, the thickness of the wall portion, i.e., the horizontal size in the drawing, and the height of the wall portion, i.e., the vertical size in the drawing, are different to make the structure easier to understand. In actuality, the wall portion has a thickness of approximately several millimeters and a height of approximately 1 μm, for example. That is, the thickness and height of the wall portion are reversed in FIG. 1 .

[0017] Furthermore, the following description is based on a representative embodiment of the present invention, but the present invention is not limited to such an embodiment. In the present invention, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits.

[0018] An example of a solar cell manufactured by the manufacturing method of the present invention is conceptually shown in Figure 1. As shown in Figure 1, a solar cell 10 has, from the bottom in the figure, a substrate 12, a first electrode layer 14, an electron transport layer (ETL layer) 16, a perovskite layer 18, a hole transport layer (HTL layer) 20, a second electrode layer 24, and an insulating layer 26. The first electrode layer 14 is patterned according to the individual solar cell, and wall portions made of the same material as the electron transport layer 16 are formed in the gaps between the individual solar cell cells.

[0019] The solar cell 10 also has an insulating wall 28 and a current-carrying wall 30 as wall portions. Specifically, the solar cell 10 has an insulating wall 28 that penetrates through the second electrode layer 24 to the electron transport layer 16 and reaches from the insulating layer 26 to the first electrode layer 14. The solar cell 10 also has a current-carrying wall 30 that penetrates through the hole transport layer 20 to the electron transport layer 16 and reaches from the second electrode layer 24 to the first electrode layer 14. In the solar cell 10, the insulating walls 28 form individual solar cells. In addition, in the solar cell 10, the current-carrying walls 30 connect the solar cells in series.

[0020] In the illustrated solar cell 10, the functional layer of the present invention is formed by the electron transport layer 16, the perovskite layer 18, and the hole transport layer 20. In the illustrated solar cell 10, the upper layer of the present invention is formed by the second electrode layer 24 and the insulating layer 26. Note that, in the present invention, the term "upper" in the upper layer is a convenient term used to distinguish the upper layer from other layers and has no technical meaning. In other words, in the present invention, the term "upper" in the upper layer is unrelated to the actual up-and-down direction (top-to-bottom). Therefore, there is no problem with the solar cell 10 manufactured by the manufacturing method of the present invention, even if the upper layer is positioned at the lowest top-to-bottom position during use.

[0021] The components of the solar cell 10 will be described below.

[0022] <<Substrate>> The substrate 12 is a support that supports the first electrode layer 14, the functional layer, and the upper layer. Therefore, various substrates used in known solar cells can be used as the substrate 12, as long as they can support the first electrode layer 14, the functional layer, and the upper layer.

[0023] Since the solar cell 10 manufactured by the manufacturing method of the present invention is a perovskite solar cell, it is preferable that it has flexibility. In consideration of this, it is preferable that the substrate 12 has flexibility. That is, various known sheet-like materials (films, plate-like materials) that have the necessary flexibility and can support each layer formed on one surface can be used as the substrate 12. In the present invention, "flexible" means that after being bent from a flat (planar) state, it can be returned to a flat state without deformation, breakage, damage, etc. In the present invention, "flexible" specifically means that it is preferably capable of being bent to a curvature radius of 2 cm or less, and more preferably to a curvature radius of 1 cm or less.

[0024] Examples of such flexible substrates include plastic films, metal foils such as aluminum foil, flexible glass, and sheets made of fibrous materials. Examples of materials for forming the plastic films used for the substrate include thermoplastic resins such as polyester resins, methacrylic resins, resins made of methacrylic acid-maleic acid copolymers, polystyrene resins, fluororesins, polyimide resins, fluorinated polyimide resins, polyamide resins, polyamideimide resins, polyetherimide resins, cellulose acylate resins, polyurethane resins, polyether ether ketone resins, polycarbonate resins, alicyclic polyolefin resins, polyarylate resins, polyethersulfone resins, polysulfone resins, resins made of cycloolefin copolymers, fluorene ring-modified polycarbonate resins, alicyclic ring-modified polycarbonate resins, fluorene ring-modified polyester resins, and acryloyl compounds.

[0025] Furthermore, the substrate 12 is preferably transparent to light (visible light). Specifically, the substrate 12 preferably has a light transmittance of 80% or more for light in the wavelength range of 400 to 800 nm. The light transmittance is more preferably 85% or more, and even more preferably 90% or more. This also applies to the electrode layer described below. The light transmittance can be calculated by the method described in JIS-K7105, that is, by measuring the total light transmittance and the amount of scattered light using an integrating sphere light transmittance measuring device and subtracting the diffuse transmittance from the total light transmittance.

[0026] The thickness of the substrate 12 may be set appropriately depending on the material used and the required flexibility, so that the substrate 12 can support other layers and ensure the required flexibility.

[0027] <<First Electrode Layer and Second Electrode Layer>> The first electrode layer 14 and the second electrode layer 24 can also be made of various electrodes used in known solar cells. In the following description, when there is no need to distinguish between the first electrode layer 14 and the second electrode layer 24, they are collectively referred to as "electrode layers." In the solar cell 10, the first electrode layer 14 is used to extract power generated in the functional layers (electron transport layer 16, perovskite layer 18, and hole transport layer 20) to the outside. As described above, the first electrode layer 14 is patterned. On the other hand, the second electrode layer 24 functions as a positive electrode in the solar cell 10. At least one of the first electrode layer 14 and the second electrode layer 24 is transparent to light. Here, if the substrate 12 is transparent to light, it is preferable that the first electrode layer 14 is also transparent to light.

[0028] The material for forming the electrode layer is not limited, and various known materials used as electrodes in solar cells can be used. The material for forming the first electrode layer 14 and the material for forming the second electrode layer 24 may be the same or different. Examples of materials for forming the electrode layer include metals, metal oxides, conductive polymers, and mixtures thereof. Examples of metals include magnesium (Mg), aluminum (Al), calcium (Ca), titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), strontium (Sr), silver (Ag), indium (In), tin (Sn), barium (Ba), bismuth (Bi), and alloys thereof, as well as carbon. These may be used as fine particles (nanoparticles). Examples of metal oxides include transparent conductive oxides (TCOs) such as tin oxide, fluorine-doped tin oxide (FTO), zinc oxide, antimony-doped zinc oxide (AZO), indium oxide, indium tin oxide (ITO), indium zinc oxide (IZO), and indium tungsten oxide (IWO). Examples of conductive polymers include polythiophene, polypyrrole, polyaniline, polyphenylene vinylene, polyphenylene, polyacetylene, polyquinoxaline, polyoxadiazole, and polybenzothiadiazole, as well as polymer compounds having multiple conductive skeletons. There are no limitations on the thickness of the electrode layer. For example, a thickness of 0.01 to 30 μm is preferred. The electrode layer may have a single-layer structure or a multilayer structure.

[0029] <<Electron Transport Layer>> In the solar cell 10 shown in the figure, the functional layers are composed of an electron transport layer 16, a perovskite layer 18, and a hole transport layer 20. In the solar cell 10, the electron transport layer 16 is provided on the surface of the first electrode layer 14. The electron transport layer 16 has the function of transporting electrons generated in the perovskite layer 18 to the first electrode layer 14. The electron transport layer 16 is formed of an electron transport material that can perform the function of transporting electrons. The electron transport material is not particularly limited, but an organic material (organic electron transport material) is preferred. Examples of organic electron transport materials include fullerene compounds such as [6,6]-phenyl-C61-butylic acid methyl ester (PC61BM), perylene compounds such as perylene tetracarboxylic diimide (PTCDI), and low-molecular-weight or high-molecular-weight compounds such as tetracyanoquinodimethane (TCNQ). The thickness of the electron transport layer 16 is not particularly limited, but is preferably 0.001 to 10 μm, and more preferably 0.01 to 1 μm.

[0030] <<Perovskite Layer>> The solar cell manufactured by the manufacturing method of the present invention is a perovskite solar cell. In the illustrated solar cell 10, a perovskite layer 18 is provided on the surface of the electron transport layer 16. The perovskite layer 18 has a photoelectric conversion function and obtains electric power from incident light. In the present invention, the perovskite layer 18 is a perovskite photosensitive layer and therefore includes a perovskite compound. The perovskite compound is a compound having a perovskite crystal structure. The compound having a perovskite crystal structure is not particularly limited. For the perovskite layer 18, for example, perovskite compounds described in International Publication No. 2019 / 053967, Japanese Patent Application Laid-Open No. 2017-17166, Japanese Patent Application Laid-Open No. 2015-191916, etc. can be used. There are no particular limitations on the thickness of the perovskite layer 18, but it is preferably 0.001 to 100 μm, more preferably 0.01 to 10 μm, and even more preferably 0.01 to 5 μm.

[0031] <<Hole Transport Layer>> In the solar cell 10 shown in Figure 1, a hole transport layer 20 is provided on the surface of the perovskite layer 18. The hole transport layer has the function of replenishing electrons to the oxidant of the perovskite layer 18, and is preferably a solid layer (solid hole transport layer). The hole transport material forming the hole transport layer 20 may be either a liquid material or a solid material, and is not particularly limited. Examples of hole transport materials include inorganic materials such as CuI and CuNCS, and organic hole transport materials described in paragraphs

[0209] to

[0212] of JP 2001-291534 A. Examples of organic hole transport materials include conductive polymers such as polythiophene, polyaniline, polypyrrole, and polysilane; spiro compounds in which two rings share a central atom such as C or Si and form a tetrahedral structure; aromatic amine compounds such as triarylamine; triphenylene compounds; and nitrogen-containing heterocyclic compounds or liquid crystalline cyano compounds. The hole transport material is preferably a solution-coatable organic hole transport material that becomes a solid. Specific examples of such hole transport materials include 2,2',7,7'-tetrakis-(N,N-di-p-methoxyphenylamino)-9,9'-spirobifluorene (also known as spiro-MeOTAD), poly(3-hexylthiophene-2,5-diyl), 4-(diethylamino)benzaldehyde diphenylhydrazone, and polyethylenedioxythiophene (PEDOT). Materials used for hole transport layers described in International Publication No. 2019 / 053967, JP 2017-17166 A, and JP 2015-191916 A can also be used as the hole transport material forming the hole transport layer 20. There are no particular restrictions on the thickness of the hole transport layer 20, and it is preferably 50 μm or less, more preferably 1 nm to 10 μm, even more preferably 5 nm to 5 μm, and particularly preferably 10 nm to 1 μm.

[0032] <<Insulating Layer>> In the solar cell 10 shown in FIG. 1 , an insulating layer 26 is provided on the surface of the second electrode layer 24. In the solar cell 10 shown in the figure, the second electrode layer 24 and the insulating layer 26 constitute the upper layer of the present invention. The insulating layer 26 acts as a protective layer for the solar cell 10. The insulating layer 26 also acts as a sealing layer that prevents moisture from penetrating into the solar cell, thereby preventing moisture-induced deterioration of the perovskite layer 18 and the like, and improving the durability of the solar cell. There are no limitations on the material from which the insulating layer 26 can be formed, and various insulating materials can be used. In consideration of the above-mentioned effects, resins are preferred as materials for forming the insulating layer 26, and examples thereof include thermoplastic resins, thermosetting resins, and photocurable resins. Specific examples of thermoplastic resins include polyimide, polytetrafluoroethylene (PTFE), polyolefin elastomer (POE), cycloolefin resin (COP), butyl rubber, polyester, polyurethane, polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyvinyl alcohol, polyvinyl acetate, ABS resin, polybutadiene, polyamide, polycarbonate, and polyisobutylene. Examples of thermosetting resins include silicone resin, phenolic resin, epoxy resin, acrylic resin, melamine resin, and urea resin. Examples of photocurable resins include acrylic resin, epoxy resin, allyl phthalate resin, vinyl resin, and ene-thiol resin. Materials primarily composed of rubber can also be used for the insulating layer 26. If necessary, fine particles of TiO 2 , ZrO 2 , WO 3 , Nb 2 O 5 , Ta 2 O 5 , BaTiO 3 , and the like may be added to the insulating layer 26 as inorganic fillers. There are no particular limitations on the thickness of the insulating layer 26, but it is preferably 0.1 to 300 μm, more preferably 0.2 to 100 μm, and even more preferably 0.5 to 50 μm.

[0033] <<Insulating Wall>> The solar cell 10 has an insulating wall 28 that penetrates through the second electrode layer 24 to the electron transport layer 16 and extends from the insulating layer 26 to the first electrode layer 14. In the solar cell 10, the insulating wall 28 forms (separates) individual solar cell cells. The material for forming the insulating wall 28 is not limited, and various known insulating materials can be used. Specifically, examples include the same materials as those for the insulating layer 26 described above. In the solar cell 10 manufactured by the manufacturing method of the present invention, the material for forming the insulating layer 26 and the material for forming the insulating wall 28 may be the same or different. However, from the standpoint of compatibility, such as adhesion between the insulating layer 26 and the insulating wall 28, it is preferable that the insulating layer 26 and the insulating wall 28 be made of the same material. The thickness of the insulating wall 28 (the horizontal dimension in the figure) is not limited, but is preferably 0.3 to 20 mm, more preferably 1 to 10 mm. The height of the insulating wall 28 (the vertical dimension in the figure) is essentially equal to the thickness of the functional layer and the second electrode layer 24.

[0034] <<Conductive Walls>> The solar cell 10 has a conductive wall 30 that penetrates through the hole transport layer 20 to the electron transport layer 16 and extends from the second electrode layer 24 to the first electrode layer 14. The solar cell 10 has a conductive wall 30 that extends to each of the insulating layers 24 and 16. The second electrode 24 and the first electrode 14 are connected by the conductive wall 30. The material for the conductive wall 30 is not limited, and various known conductive materials can be used. Specific examples include materials similar to those used for the electrode layers described above. In the solar cell 10 manufactured by the manufacturing method of the present invention, the material for the second electrode layer 24 and the material for the conductive wall 30 may be the same or different. However, from the standpoint of compatibility, such as adhesion, between the second electrode layer 24 and the conductive wall 30, it is preferable that the second electrode layer 24 and the conductive wall 30 be made of the same material. The thickness of the insulating wall 28 (the horizontal dimension in the drawing) is not limited, but is preferably 0.3 to 20 mm, and more preferably 1 to 10 mm. The height of the current-carrying wall 30 (the vertical dimension in the drawing) is basically equal to the thickness of the functional layer.

[0035] Solar cells manufactured by the manufacturing method of the present invention are essentially similar to known solar cells, except that they do not have the cutting debris that occurs in solar cells manufactured by conventional manufacturing methods and do not have damage to the first electrode layer 14 due to cutting. Therefore, solar cells manufactured by the manufacturing method of the present invention are not limited to the solar cell 10 having the configuration shown in FIG. 1 . That is, the manufacturing method of a solar cell of the present invention can be used to manufacture solar cells with various known configurations. For example, a solar cell manufactured by the manufacturing method of the present invention may have only a second electrode layer 24 as the upper layer and a second substrate on the surface of the upper layer. Alternatively, the solar cell may have only an insulating layer 26 as the upper layer. Furthermore, the functional layer may not have the electron transport layer 16 and / or the hole transport layer 20 as long as it has a perovskite layer 18. Furthermore, the positions of the hole transport layer 20 and the electron transport layer 16 in the functional layer may be reversed. Furthermore, the functional layer may have an intermediate layer, etc., to facilitate carrier exchange between holes and the electrodes, in addition to the electron transport layer 16, perovskite layer 18, and hole transport layer 20.

[0036] In the solar cell manufacturing method of the present invention, there are no limitations on the methods for forming the various layers described above, as well as the insulating walls 28 and the current-carrying walls 30. Various known methods can be used depending on the materials used to form the layers and walls. Examples include gas-phase reaction methods such as vacuum deposition, sputtering, and CVD, electrochemical deposition, coating (printing), and 2P (photopolymerization). Among these, coating methods are preferred. There are also no limitations on the coating method; known coating methods such as die coating, inkjet coating, air knife coating, curtain coating, roller coating, wire bar coating, gravure coating, slide coating, and stripe coating can be used. Among these, stripe coating, particularly stripe coating using a slot die coater, is preferred.

[0037] Depending on the materials used to form the layers and walls, thermal transfer may also be suitable. The thermal transfer method (photothermal transfer method) will now be described with reference to the conceptual diagram of FIG.

[0038] In the thermal transfer method, for example, a laminate having a forming material layer 40, a photothermal conversion layer 42, and a substrate 46, in this order, is prepared. The forming material layer 40 is a layer formed from the material of the layer to be formed. The photothermal conversion layer 42 is a known photothermal conversion layer that absorbs light and generates heat, such as a layer containing an infrared absorbing pigment or a layer made of carbon black. This laminate is placed with the forming material layer 40 on the forming surface S, as shown in the upper part of Figure 2. For example, when forming the insulating layer 26 using the thermal transfer method, the forming material layer 40 is a layer made from the material of the insulating layer 26, and the forming surface S is the surface of the second electrode layer 24. Next, as shown in the middle part of Figure 2, laser light L is irradiated onto the substrate 46 to heat the area where the layer will be formed. This softens the forming material of the heated portion and adheres it to the forming surface S. Thereafter, as shown in the lower part of Figure 2, the laminate is peeled off from the forming surface S, thereby thermally transferring the area that will become the forming material layer to the forming surface S. For example, a material for forming the insulating layer 26 is thermally transferred onto the second electrode layer 24, which is the forming surface S. The formation of the layer and wall portion by thermal transfer is not limited to a method based on photothermal conversion using laser light or the like, and thermal transfer may be performed by directly heating the base material 46 using a heater or the like, without using a photothermal conversion layer.

[0039] The method for manufacturing a solar cell of the present invention includes a first electrode layer, a functional layer having a perovskite layer, and an upper layer stacked in this order, and further includes a wall portion penetrating the functional layer in the stacking direction of the first electrode layer, the functional layer, and the upper layer, in which the wall portion is formed before forming the upper layer. As described above, the solar cell 10 shown in FIG. 1 includes an electron transport layer 16, a perovskite layer 18, and a hole transport layer 20 as functional layers, and a second electrode layer 24 and an insulating layer 26 as upper layers. The solar cell 10 also includes an insulating wall 28 that penetrates from the second electrode layer 24 to the electron transport layer 16 and extends from the insulating layer 26 to the first electrode layer 14. The solar cell 10 also includes a current-carrying wall 30 that penetrates from the hole transport layer 20 to the electron transport layer 16 and extends from the second electrode layer 24 to the first electrode layer 14.

[0040] An example of a first embodiment of the method for manufacturing a solar cell of the present invention will now be described with reference to the conceptual diagram of Fig. 3. The first embodiment of the method for manufacturing a solar cell of the present invention is a manufacturing method in which a wall portion is formed first, then a functional layer is formed, and finally an upper layer is formed.

[0041] First, a laminate is prepared in which a patterned first electrode layer 14 is formed on the surface of a substrate 12. This laminate may be one produced in an upstream step of the manufacturing method of the present invention described below, or one that is separately prepared and used. This also applies to the second and third aspects of the manufacturing method of a solar cell of the present invention described below.

[0042] In this manufacturing method, first, as shown in the upper part of Fig. 3, insulating walls 28 and current-carrying walls 30 are formed on the surface of the first electrode layer 14 of this laminate according to the pattern of the first electrode layer 14, i.e., according to the individual solar cell. Note that, as in Fig. 1, the relationship between thickness and height of the insulating walls 28 and current-carrying walls 30 is reversed in Fig. 3 as well, and as described above, the wall thickness (the horizontal dimension in the figure) is actually about several millimeters, and the height (the vertical dimension in the figure) is about 1 µm.

[0043] Next, an electron transport layer 16 is formed on the surface of the first electrode layer 14. At this time, the material for forming the electron transport layer 16 fills the gaps corresponding to the pattern of the first electrode layer 14. This fills the gaps of the pattern of the first electrode layer 14, i.e., the gaps between the individual solar cell cells of the first electrode layer 14 in the solar cell. Next, a perovskite layer 18 and a hole transport layer 20 are formed in sequence to form a three-layer functional layer as shown in the middle of Figure 3. Note that the three functional layers may be formed simultaneously using so-called multi-layer coating. This also applies to the formation of the upper layer and to the second and third aspects of the solar cell manufacturing method of the present invention described below. After the functional layer is formed, a second electrode layer 24 is then formed on the surface of the hole transport layer 20 as shown in the bottom of Figure 3. Finally, an insulating layer 26 is formed on the surface of the second electrode layer 24 to form the upper layer, thereby producing the solar cell 10 as shown in Figure 1. As described above, the materials forming the second electrode layer 24 and the current-carrying wall 30, and the materials forming the insulating layer 26 and the insulating wall 28 may be the same or different.

[0044] In the first embodiment of the method for manufacturing a solar cell of the present invention described above, the wall portion is formed first, then the functional layer is formed, and finally the upper layer is formed. In contrast, in the second embodiment of the method for manufacturing a solar cell of the present invention, the wall portion and the functional layer are formed in parallel, and finally the upper layer is formed. An example of the second embodiment of the method for manufacturing a solar cell of the present invention will be described below with reference to the conceptual diagram of Figure 4. Note that Figure 4 shows only the left side of the solar cell 10 shown in Figure 1.

[0045] As in the first embodiment of the solar cell manufacturing method of the present invention described above, a laminate is prepared in which a patterned first electrode layer 14 is formed on the surface of a substrate 12, as shown in the first row (upper row) of Fig. 4. Next, as shown in the second row of Fig. 4, an electron transport layer 16 is formed on the surface of the first electrode layer 14 of this laminate in accordance with the pattern of the first electrode layer 14, i.e., the individual solar cell cells, and simultaneously, an insulating wall 28 and a current-carrying wall 30 are formed up to the height of the electron transport layer 16. Note that, as in the above example, at this time, the pattern of the first electrode layer 14, i.e., the gaps between the individual solar cell cells in the solar cell, are filled with the material forming the electron transport layer 16.

[0046] Next, as shown in the third row of Fig. 4, a perovskite layer 18 is formed on the surface of the electron transport layer 16, and in parallel, an insulating wall 28 and a current-carrying wall 30 are formed up to the height of the perovskite layer 18. Next, as shown in the fourth row of Fig. 4, a hole transport layer 20 is formed on the surface of the perovskite layer 18, and in parallel, an insulating wall 28 and a current-carrying wall 30 are formed up to the height of the hole transport layer 20. In this way, a functional layer having a three-layer configuration of the electron transport layer 16, perovskite layer 18, and hole transport layer 20 is formed.

[0047] After the functional layer is formed, as shown in the fifth row (bottom row) of Fig. 4, the second electrode layer 24 is formed, and in parallel, the insulating wall 28 is formed up to the height of the second electrode layer 24. Finally, the insulating layer 26 is formed on the surface of the second electrode layer 24 to prepare an upper layer, thereby producing the solar cell 10 as shown in Fig. 1. As mentioned above, the materials for forming the second electrode layer 24 and the current-carrying wall 30, and the materials for forming the insulating layer 26 and the insulating wall 28 may be the same or different.

[0048] In this second embodiment of the solar cell manufacturing method of the present invention, the formation of each layer and the formation of the wall portion up to the height of the layer to be formed may be performed simultaneously. Alternatively, in the second embodiment of the solar cell manufacturing method of the present invention, the formation of each layer and the formation of the wall portion up to the height of the layer to be formed may be performed at different times, for example, by forming the layer first. However, in consideration of production efficiency, it is preferable to simultaneously form each layer and the wall portion up to the height of the layer to be formed, for example, by using stripe coating using the slot die coater described above. This also applies to the third embodiment of the solar cell manufacturing method of the present invention described below.

[0049] In a first embodiment of the method for manufacturing a solar cell of the present invention, the wall portion is formed first, and then the functional layer is formed. In a second embodiment of the method for manufacturing a solar cell of the present invention, the functional layer and the wall portion are formed in parallel. In contrast, in a third embodiment of the method for manufacturing a solar cell of the present invention, the bottom layer of the functional layer, i.e., the surface layer of the first electrode layer 14, and the wall portion are formed simultaneously, and then the remaining functional layers are formed.

[0050] That is, in the third embodiment of the method for manufacturing a solar cell of the present invention, when manufacturing a solar cell 10, the insulating wall 28 and the current-carrying wall 30 are formed in parallel with the formation of the electron transport layer 16 on the surface of the first electrode layer 14, in the same manner as in the first embodiment. That is, in this manufacturing method, the insulating wall 28 and the current-carrying wall 30 are completed at this stage. Thereafter, the perovskite layer 18 is formed on the surface of the electron transport layer 16, and then the hole transport layer 20 is formed on the surface of the perovskite layer 18, thereby forming a three-layer functional layer. Thereafter, the second electrode layer 24 and the insulating layer 26 are formed in the same manner as in the first embodiment, thereby manufacturing a solar cell as shown in FIG. 1 .

[0051] As described above, in conventional solar cell manufacturing methods, after forming a functional layer, the functional layer is cut to form grooves, and then a second electrode layer is formed on the surface of the functional layer, thereby simultaneously forming a conductive wall. Furthermore, the functional layer and the second electrode layer are then cut to form grooves, and then an insulating layer is formed, thereby simultaneously forming an insulating wall. Therefore, in conventional manufacturing methods, the performance of each layer is inevitably reduced due to the adhesion of cutting debris, and there is also a high possibility that the first electrode layer will be damaged during cutting.

[0052] In contrast, in the solar cell manufacturing method of the present invention, in which the upper layer is formed after the functional layer, insulating wall 28, and current-carrying wall 30 (wall portion) are formed, there is no need to cut the functional layer, etc. Therefore, the solar cell manufacturing method of the present invention can manufacture high-quality solar cells that are prevented from being contaminated by cutting debris and from being damaged by cutting the electrode layer, etc.

[0053] In the method for manufacturing a solar cell of the present invention, it is preferable to form the functional layer, the wall portion, and the upper layer while transporting a laminate having a first electrode layer 14 on the surface of the substrate 12. That is, in the method for manufacturing a solar cell of the present invention, it is preferable to manufacture the solar cell by so-called roll-to-roll (RtoR) using the flexibility of perovskite solar cells.

[0054] For example, in the first embodiment of the manufacturing method of the present invention described above, it is preferable to first form the insulating wall 28 and the current-carrying wall 30 while transporting the laminate in a direction perpendicular to the plane of the paper in FIG. 3 , then, while similarly transporting the laminate, sequentially form the electron transport layer 16, the perovskite layer 18, and the hole transport layer 20 to form a functional layer, and further, while similarly transporting the laminate, sequentially form the second electrode layer 24 and the insulating layer 26, thereby manufacturing a solar cell as shown in FIG. 1 .

[0055] In the second embodiment of the method for producing a solar cell of the present invention, it is preferable to first form the electron transport layer 16 while transporting the laminate in a direction perpendicular to the plane of the paper in FIG. 4 , and then form the insulating walls 28 and the current-carrying walls 30 to the same height as the electron transport layer 16; then, while transporting the laminate in a similar manner, form the perovskite layer 18 while also forming the insulating walls 28 and the current-carrying walls 30 to the same height as the perovskite layer 18; then, while transporting the laminate in a similar manner, form the hole transport layer 20 while also forming the insulating walls 28 and the current-carrying walls 30 to the same height as the hole transport layer 20; then, while transporting the laminate in a similar manner, form the second electrode layer 24 while also forming the current-carrying walls 30 to the same height as the second electrode layer 24; and further, while transporting the laminate in a similar manner, form the insulating layer 26 to form an upper layer, thereby producing the solar cell 10 as shown in FIG. 1 .

[0056] In the solar cell manufacturing method of the present invention, even when such roll-to-roll process is used, the various forming methods described above, including the thermal transfer method, can be used to form each layer and wall portion. Among them, when roll-to-roll process is used in the present invention, the coating method is preferably used, and in particular, stripe coating using a slot die coater is preferably used.

[0057] In the manufacturing method of a solar cell of the present invention using such roll-to-roll process, the formation of each layer and wall portion may be performed continuously, or the laminate may be wound up after each layer or multiple layers are formed. However, considering productivity and the like, it is preferable to continuously transport the laminate while continuously performing the processes up to the formation of the insulating layer 26. As an example, in the second embodiment of the manufacturing method of a solar cell of the present invention, it is preferable to manufacture the solar cell 10 by continuously transporting the laminate while five slot die coaters are lined up in the transport direction of the laminate and continuously transporting the laminate, thereby continuously forming the electron transport layer 16, the insulating wall 28, and the current-carrying wall 30, the perovskite layer 18, the insulating wall 28, and the current-carrying wall 30, the hole transport layer 20, the insulating wall 28, and the current-carrying wall 30, the second electrode layer 24, the insulating wall 28, and the insulating layer 26.

[0058] Furthermore, when the manufacturing method of the present invention is carried out by stripe coating using a slot die coater, intermittent stripe coating may be carried out to provide gaps in the transport direction, thereby forming a large number of separated solar cells.

[0059] Although the method for manufacturing a solar cell of the present invention has been described in detail above, the present invention is not limited to the above example, and various improvements and modifications may be made without departing from the spirit and scope of the present invention. For example, in the first embodiment of the manufacturing method of the present invention described above, the insulating walls 28 and the current-carrying walls 30 are first formed, then the functional layer is formed, and finally the upper layer is formed. However, in the present invention, the functional layer may be first formed so as to leave grooves for forming the insulating walls 28 and the current-carrying walls 30, and then the insulating walls 28 and the current-carrying walls 30 are formed, and finally the upper layer is formed.

[0060] The present invention can be suitably used in the manufacture of perovskite solar cells.

[0061] 10, 100 Solar cell 12, 102 Substrate 14, 104 First electrode layer 16, 106 Electron transport layer 18, 108 Perovskite layer 20, 110 Hole transport layer 24, 112 Second electrode layer 26, 114 Insulating layer 28, 118 Insulating wall 30, 120 Current-carrying wall 118a, 120a Groove

Claims

1. A method for manufacturing a solar cell comprising a first electrode layer, a functional layer having at least a perovskite layer, and an upper layer having one or more layers stacked in this order, and further comprising a wall portion penetrating the functional layer in the stacking direction of the first electrode layer, the functional layer, and the upper layer, wherein the wall portion is formed before the upper layer is formed.

2. The method for manufacturing a solar cell according to claim 1, wherein at least one of a second electrode layer and an insulating layer is formed as the upper layer.

3. The method for manufacturing a solar cell according to claim 1 or 2, wherein the wall portion is formed, then the functional layer is formed, and then the upper layer is formed.

4. The method for manufacturing a solar cell according to claim 1 or 2, wherein the functional layer and the wall portion are formed in parallel, and then the upper layer is formed.

5. A method for manufacturing a solar cell according to claim 1 or 2, wherein the functional layer is formed to have one or more layers other than the perovskite layer, and the formation of a first layer of the functional layer and the formation of the wall portion are carried out in parallel, followed by the formation of the remaining layers of the functional layer, and then the formation of the upper layer.

6. The method for manufacturing a solar cell according to claim 1 or 2, wherein the material forming at least one of the wall portions is the same material as the material forming at least one of the upper layers.

7. The method for manufacturing a solar cell according to claim 2, wherein at least one of the wall portions is formed from the same material as the second electrode layer and the insulating layer.

8. The method for producing a solar cell according to claim 1 or 2, wherein at least one of an electron transport layer and a hole transport layer is formed as the functional layer in addition to the perovskite layer.

9. The method for manufacturing a solar cell according to claim 1 or 2, wherein the functional layer, the wall portion, and the upper layer are formed on a substrate having the first electrode layer.

10. The method for manufacturing a solar cell according to claim 9, wherein the functional layer, the wall portion, and the upper layer are formed while the substrate is being transported.

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