Method for manufacturing solar cell

Abstract

The present invention addresses the problem of providing a highly productive manufacturing method with which it is possible to manufacture a solar cell, the solar cell being sealed with two substrates. The problem is solved by having: a step for forming a first inorganic adhesive layer (26) that surrounds a first electrode (14), while conveying a flexible first substrate (12) on which the first electrode (14) is formed; a step for forming a second inorganic adhesive layer (28) that surrounds a second electrode (18), while conveying a flexible second substrate (16) on which the second electrode (18) and a perovskite-type photoelectric conversion layer (20) are formed; and a step for bonding the first substrate (12) and the second substrate (16) to each other by means of the first inorganic adhesive layer (26) and the second inorganic adhesive layer (28), while conveying the first substrate (12) and the second substrate (16).

Description

Solar cell manufacturing method

[0001] The present invention relates to a method for manufacturing a solar cell having a perovskite-type photoelectric conversion layer.

[0002] Perovskite solar cells are known that have a photoelectric conversion layer including a perovskite layer (perovskite-type photosensitive layer) containing a perovskite compound. The photosensitive layer that constitutes perovskite solar cells is known to deteriorate upon contact with moisture. Therefore, perovskite solar cells are sealed to prevent deterioration due to moisture.

[0003] For example, Patent Document 1 describes a method for sealing electronic elements such as organic electroluminescence elements and solar cells between an element substrate and a sealing substrate, which includes forming the electronic elements in an area surrounded by an annular joint on the bonding surface of the element substrate, forming through electrodes in the area surrounded by the annular joint to penetrate the element substrate or the sealing substrate and electrically connect the electronic elements to the outside of the sealing structure, forming an inorganic adhesive layer on at least one surface of the annular joint and a corresponding annular joint on the sealing substrate, and contacting and bonding the annular joint of the element substrate and the annular joint of the sealing substrate to each other, thereby sealing the electronic elements between the element substrate and the sealing substrate.

[0004] Japanese Patent Application Laid-Open No. 2014-123514

[0005] According to the method described in Patent Document 1, electronic elements such as organic electroluminescence elements and solar cells can be sealed between an element substrate and a sealing substrate to prevent the electronic elements from being deteriorated by moisture.

[0006] In the sealing method described in Patent Document 1, the area other than the annular junction, such as an organic electroluminescence element or a solar cell, is covered with a mask, and an inorganic adhesive layer is formed on the surface of the annular junction by a vacuum deposition method such as plasma chemical vapor deposition (CVD) or sputtering. Therefore, the sealing method described in Patent Document 1 requires batch processing for each electronic element. Alternatively, when continuously manufacturing multiple electronic elements, the elements must be repeatedly transported and stopped for processing. Therefore, this sealing method is disadvantageous in terms of productivity.

[0007] An object of the present invention is to solve the problems of the prior art and to provide a method for manufacturing solar cells that can produce solar cells sealed with two substrates with high productivity.

[0008] To achieve these objects, the present invention has the following configurations. [1] A method for manufacturing a solar cell, comprising: a first inorganic adhesive layer forming step of transporting a flexible first substrate having a first electrode formed on one surface thereof while forming a first inorganic adhesive layer around the first electrode; a second inorganic adhesive layer forming step of transporting a flexible second substrate having a second electrode and a perovskite-type photoelectric conversion layer formed on one surface thereof while forming a second inorganic adhesive layer around the second electrode; and a bonding step of bonding the first substrate and the second substrate together with the first inorganic adhesive layer and the second inorganic adhesive layer while transporting the first substrate and the second substrate. [2] The method for manufacturing a solar cell according to [1], wherein the first inorganic adhesive layer and the second inorganic adhesive layer are formed using atmospheric pressure plasma. [3] The method for manufacturing a solar cell according to [2], wherein the atmospheric pressure plasma is irradiation-type atmospheric pressure plasma. [4] The method for manufacturing a solar cell according to any one of [1] to [3], wherein an activation treatment is performed on at least one of the first inorganic adhesive layer and the second inorganic adhesive layer prior to the bonding step. [5] The method for manufacturing a solar cell according to [4], wherein the activation treatment is a treatment using atmospheric pressure plasma. [6] The method for manufacturing a solar cell according to [5], wherein the treatment using atmospheric pressure plasma is a treatment using irradiating atmospheric pressure plasma. [7] The method for manufacturing a solar cell according to any one of [1] to [6], wherein at least one of the first substrate and the second substrate has gas barrier properties. [8] The method for manufacturing a solar cell according to any one of [1] to [7], wherein the first substrate and the second substrate are long and are transported in the longitudinal direction. [9] The method for manufacturing a solar cell according to [8], wherein the first substrate has a plurality of first electrodes formed thereon in a longitudinal arrangement, and the second substrate has a plurality of second electrodes and a perovskite-type photoelectric conversion layer formed thereon in a longitudinal arrangement.

[0009] According to the present invention, a solar cell sealed with two substrates can be produced with high productivity.

[0010] Fig. 1 is a conceptual diagram for explaining an example of a method for manufacturing a solar cell of the present invention. Fig. 2 is a conceptual diagram showing an example of a solar cell manufactured by the method for manufacturing a solar cell of the present invention. Fig. 3 is a conceptual diagram for explaining the formation of a first inorganic adhesive layer. Fig. 4 is a conceptual diagram for explaining the formation of a second inorganic adhesive layer. Fig. 5 is a conceptual diagram for explaining an example of a method for forming a first inorganic adhesive layer. Fig. 6 is a cross-sectional diagram conceptually showing an example of an irradiation-type atmospheric pressure plasma source.

[0011] The solar cell manufacturing method of the present invention will be described in detail below. 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 including the numerical values ​​before and after "to" as the lower and upper limits. Furthermore, in the present invention, angles such as "angle," "parallel," and "orthogonal" include the error range generally accepted in the relevant technical field unless otherwise specified. Furthermore, all of the figures shown below are conceptual diagrams for explaining the present invention. Therefore, the shape, size, thickness, and positional relationships, such as the placement position and spacing, of each component in each figure do not necessarily correspond to those of an actual device.

[0012] Furthermore, in the present invention, the terms "first" and "second" in the first substrate and second substrate, and the first electrode and second electrode are used for convenience to distinguish between similar members, and have no technical meaning.

[0013] An example of a method for manufacturing a solar cell of the present invention is conceptually shown in Figure 1. In the following description, "a method for manufacturing a solar cell of the present invention" will also be simply referred to as "the manufacturing method of the present invention."

[0014] As shown in FIG. 1 , the manufacturing method of the present invention involves transporting a flexible first substrate 12 having a first electrode 14 formed on one surface, while a first adhesive layer forming means 38 forms a first inorganic adhesive layer 26 around the first electrode 14 (first inorganic adhesive layer forming step); transporting a second substrate 16 having a second electrode 18 and a perovskite-type photoelectric conversion layer 20 formed on one surface, while a second adhesive layer forming means 40 forms a second inorganic adhesive layer 28 around the second electrode 18 (second inorganic adhesive layer forming step); and transporting the first substrate 12 and the second substrate 16, while bonding the first substrate 12 and the second substrate 16 together using the first inorganic adhesive layer 26 and the second inorganic adhesive layer 28 (bonding step), thereby manufacturing a solar cell.

[0015] By such operations, the manufacturing method of the present invention produces, as an example, a solar cell 10 sealed with a first substrate 12, a second substrate 16, a first inorganic adhesive layer 26, and a second inorganic adhesive layer 28, as conceptually shown in Figure 2. In the illustrated example, the photoelectric conversion layer 20 has an electron transport layer 30, a perovskite layer 32, and a hole transport layer 34.

[0016] In the illustrated example, as a preferred embodiment, after the first inorganic adhesive layer 26 is formed, activation treatment of the first inorganic adhesive layer 26 is performed by a first treatment means 42 before bonding the first substrate 12 and the second substrate 16. Furthermore, in the illustrated example, as a preferred embodiment, after the second inorganic adhesive layer 28 is formed, activation treatment of the second inorganic adhesive layer 28 is performed by a second treatment means 44 before bonding the first substrate 12 and the second substrate 16.

[0017] As described above, the solar cell 10 manufactured by the manufacturing method shown in FIG. 1 has, from bottom to top, a second substrate 16, a second electrode 18, a photoelectric conversion layer 20, a first electrode 14, and a first substrate 12, as shown in FIG. 2 . The photoelectric conversion layer 20 also has, from bottom to top, an electron transport layer 30, a perovskite layer 32, and a hole transport layer 34. The solar cell manufactured by the manufacturing method of the present invention is not limited to the configuration shown in FIG. 2 . That is, in the solar cell manufactured by the manufacturing method of the present invention, various known perovskite-type photoelectric conversion layers having a perovskite layer can be used as the photoelectric conversion layer. Furthermore, the solar cell manufactured by the manufacturing method of the present invention may have, in addition to the photoelectric conversion layer, various known layers that are provided in solar cells having known perovskite-type photoelectric conversion layers. That is, the solar cell manufactured by the manufacturing method of the present invention can be various known perovskite-type solar cells as long as they have a perovskite-type photoelectric conversion layer. In the illustrated example, the first electrode 14 is formed on the surface of the first substrate 12, and the second electrode 18 is formed on the surface of the second substrate 16, but the present invention is not limited to this. That is, in the manufacturing method of the present invention, some layer may be provided between the substrate and the electrode, as necessary. For example, if the gas barrier property of the substrate is poor, a gas barrier layer may be provided between the substrate and the electrode. Furthermore, if sufficient adhesion between the substrate and the electrode cannot be obtained due to factors such as the forming materials, an easy-adhesion layer may be provided between the substrate and the electrode.

[0018] However, even when manufacturing a solar cell having such a configuration, in the manufacturing method of the present invention, the first electrode 14 is formed on the first substrate 12, and the second electrode and photoelectric conversion layer 20 are formed on the second substrate 16. By having such a configuration, the manufacturing method of the present invention can suppress deterioration of the perovskite layer 32 due to moisture or the like before sealing. Note that, if the solar cell manufactured by the manufacturing method of the present invention has any layer between the photoelectric conversion layer 20 and the first electrode 14, this layer may be provided on either the first substrate 12 side or the second substrate 16 side. Examples of such a layer include a blocking layer on the electron transport layer side and a blocking layer on the hole transport layer side.

[0019] [First Substrate and Second Substrate] In the manufacturing method of the present invention, the first substrate 12 and the second substrate 16 are flexible. In the following description, when there is no need to distinguish between the first substrate 12 and the second substrate 16, they will be collectively referred to simply as "substrates."

[0020] The substrate can be any known sheet-like material (film, plate-like material) as long as it has the necessary flexibility and can support the layers formed on one surface. In the present invention, "flexible" means that it can be bent from a flat (planar) state and then returned to a flat state without deformation, breakage, or damage. Specifically, it is preferable that the substrate can be bent to a curvature radius of 2 cm or less, and more preferably to a curvature radius of 1 cm or less.

[0021] 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.

[0022] The plastic film preferably has heat resistance. Specifically, the plastic film preferably has at least one of the following physical properties: a glass transition temperature (Tg) of 100°C or higher and a linear thermal expansion coefficient of 40 ppm / K or lower. The Tg and linear expansion coefficient of the plastic film may be measured by the method for measuring the transition temperature of plastics described in JIS (Japanese Industrial Standards)-K7121 and the test method for linear expansion coefficient by thermomechanical analysis of plastics described in JIS-K7197.

[0023] The Tg or linear expansion coefficient of the plastic film can be adjusted by additives, etc. Examples of such thermoplastic resins having excellent heat resistance include polyethylene naphthalate (PEN: 120°C), polycarbonate (PC: 140°C), alicyclic polyolefins (e.g., Zeonor 1600 (trade name) manufactured by Nippon Zeon Co., Ltd.: 160°C), polyarylate (PAr: 210°C), polyethersulfone (PES: 220°C), polysulfone (PSF: 190°C), cycloolefin copolymers (C Examples include fluorene ring-modified polycarbonate (BCF-PC: compound of JP-A 2000-227603: 225°C), alicyclic modified polycarbonate (IP-PC: compound of JP-A 2000-227603: 205°C), acryloyl compounds (compounds of JP-A 2002-80616: 300°C or higher), and polyimide. The temperatures in parentheses are all "Tg". Of these, polyethylene naphthalate is preferred.

[0024] In the present invention, at least one of the first substrate 12 and the second substrate 16 is transparent to light (visible light). Specifically, at least one of the first substrate 12 and the second substrate 16 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. 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.

[0025] In the present invention, it is preferable that at least one of the first substrate 12 and the second substrate 16 has gas barrier properties. More preferably, both the first substrate 12 and the second substrate 16 have gas barrier properties. Specifically, the water vapor transmission rate (WVTR) of at least one of the first substrate 12 and the second substrate 16 is 1×10 or less in an environment at a temperature of 25° C. and a relative humidity of 50%. -2 g / (m 2 day) or less, and 1 × 10 -4 g / (m 2 It is more preferable that the water vapor transmission rate is equal to or less than 1 / 2 day. The water vapor transmission rate may be measured by a known method such as the Mocon method or the calcium corrosion method. The calcium corrosion method is described in JP-A-2005-283561.

[0026] Examples of substrates having gas barrier properties include metal foil, flexible glass, and various known gas barrier films.

[0027] There is no limitation on the thickness of the substrate, and it may be set appropriately depending on the material used to form the substrate, so long as it can support the solar cell (laminate) and ensure the necessary flexibility and strength. The thickness of the substrate is, for example, 1 to 800 μm, and preferably 10 to 300 μm.

[0028] [First Electrode and Second Electrode] In the manufacturing method of the present invention, a first electrode 14 is formed on the surface of the first substrate 12, and a second electrode 18 is formed on the surface of the second substrate 16. In the following description, when there is no need to distinguish between the first electrode 14 and the second electrode 18, they will be collectively referred to simply as "electrodes."

[0029] In the solar cell 10, the second electrode 18 is used to extract the power generated in the perovskite layer 32 (perovskite-type photosensitive layer) to the outside. On the other hand, the first electrode 14 functions as a positive electrode in the solar cell 10. The structure of the first electrode 14 is preferably one that has a high current collection effect. In addition, the first electrode is preferably patterned according to the solar cell to be manufactured. Here, if the first substrate 12 or the second substrate 16 is transparent to light, the electrode formed on the transparent substrate side is also transparent to light. Note that if both the first substrate 12 and the second substrate 16 are transparent to light, the electrodes may be transparent to light only to the electrode on the light incident side, or both may be transparent to light.

[0030] The electrode material is not limited, and various known materials used as electrodes in known solar cells can be used. Examples of electrode materials include metals, metal oxides, conductive polymers, and mixtures thereof. Among these, conductive polymers are preferred due to their flexibility. 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), and bismuth (Bi), as well as alloys thereof. 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).

[0031] The conductive polymer is not particularly limited as long as it is a polymeric compound having conductivity. Therefore, the charge carriers (carriers) transported in the second electrode 18 may be either holes or electrons. Examples of conductive polymers include polythiophene, polypyrrole, polyaniline, polyphenylene vinylene, polyphenylene, polyacetylene, polyquinoxaline, polyoxadiazole, and polybenzothiadiazole, as well as polymeric compounds having multiple conductive skeletons. Among these, polythiophene is preferred, and polyethylene dioxythiophene and polythienothiophene are more preferred. These polythiophenes are typically partially oxidized to achieve conductivity. The electrical conductivity of conductive polymers can be adjusted by the degree of partial oxidation (doping amount), with higher doping amounts resulting in higher electrical conductivity. Polythiophene becomes cationic upon partial oxidation, requiring a counter anion to neutralize the charge. An example of such a polythiophene is polyethylene dioxythiophene (PEDOT-PSS) with polystyrene sulfonic acid as a counter ion. As the conductive polymer, for example, the conductive polymer described in JP-A-2015-191916 can be used.

[0032] The thickness of the electrode is not particularly limited, and is preferably 0.01 to 30 μm, for example. The layer structure of the electrode is also not limited, and may be a single layer structure or a laminated structure.

[0033] [Electron Transport Layer] As described above, the photoelectric conversion layer 20 has the electron transport layer 30, the perovskite layer 32, and the hole transport layer 34. In the solar cell 10 shown in FIG. 2 , the electron transport layer 30 is provided on the upper surface of the second electrode 18 in the drawing. The electron transport layer 30 has the function of transporting electrons generated in the perovskite layer 32 to the second electrode 18 (or the conductive substrate). The electron transport layer 30 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 is not particularly limited, but is preferably 0.001 to 10 μm, and more preferably 0.01 to 1 μm.

[0034] [Perovskite Layer] The solar cell 10 shown in FIG. 2 is a perovskite solar cell, and a perovskite layer 32 is provided on the upper surface of the electron transport layer 30 in the figure. The perovskite layer 32 has a photoelectric conversion function and obtains electric power from incident light. In the present invention, the perovskite layer 32 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 example, the perovskite compounds described in WO 2019 / 053967, JP 2017-17166, and JP 2015-191916 can be used in the perovskite layer 32. The method for forming the perovskite layer 32 is not particularly limited, and examples thereof include vacuum deposition, sputtering, gas phase reaction methods such as CVD, electrochemical deposition, and coating methods (printing). Among these, the coating method is a preferred example. Forming the perovskite layer 32 by a coating method allows for the easy formation of large-area solar cells. The coating method is not particularly limited, and examples thereof include spin coating and casting. The coating method enables the formation of the perovskite layer 32 by roll-to-roll processing. The film thickness of the perovskite layer 32 is not particularly limited, and is preferably 0.001 to 100 μm, more preferably 0.01 to 10 μm, and even more preferably 0.01 to 5 μm.

[0035] [Hole Transport Layer] In the solar cell 10 shown in Figure 1, a hole transport layer 34 is provided on the upper surface of the perovskite layer 32 in the figure. The hole transport layer has the function of replenishing electrons to the oxidant of the perovskite layer 32, and is preferably a solid layer (solid hole transport layer). The hole transport material forming the hole transport layer 34 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 for forming the hole transport layer 34. There are no particular restrictions on the film thickness of the hole transport layer 34, 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.

[0036] The electrodes and layers constituting the solar cell may be formed by any known method suited to the materials used, such as coating, printing, vapor deposition, or sheet attachment. The first electrode 14 may also be patterned by any known method suited to the materials used to form the first electrode 14.

[0037] The method for manufacturing a solar cell of the present invention will be described in detail below with reference to FIG. 1 and FIGS.

[0038] In a preferred embodiment, the manufacturing method of the present invention shown in FIG. 1 utilizes a so-called roll-to-roll process, in which a long substrate is transported in the longitudinal direction while undergoing various processes. Therefore, in the manufacturing method of the present invention, the substrate is continuously transported without stopping, and the following processes are performed to form an inorganic adhesive layer, activate the inorganic adhesive layer, and bond the first and second substrates together, thereby producing a solar cell as shown in FIG. 2 . In the following description, "roll-to-roll" is also referred to as "RtoR." However, the present invention is not limited to this process. A solar cell may be manufactured using a cut-sheet substrate while transporting the substrate using a known method, such as a belt conveyor and a pair of transport rollers, in a manner similar to the manufacturing method shown in FIG. 1 . In this case, a single substrate may be formed with multiple first electrodes 14 or multiple second electrodes 18 and a photoelectric conversion layer 20 arranged in the transport direction. In this case, similar to RtoR, the inorganic adhesive layer is formed without stopping the transport of the substrate, thereby producing a solar cell. However, in consideration of productivity, it is still preferable to use the RtoR method in the manufacturing method of the present invention.

[0039] As described above, a first electrode 14 is formed on one surface of the first substrate 12. In the illustrated example, a plurality of first electrodes 14 are arranged in the longitudinal direction on one surface of the elongated first substrate 12. As described above, the first electrodes 14 are preferably patterned according to the solar cell to be manufactured. The first electrodes 14 are preferably formed at equal intervals in the longitudinal direction on the first substrate 12. However, the present invention is not limited to this. As long as the intervals match the intervals at which second electrodes 18 and the like are formed on the second substrate 16 described below, at least some of the first electrodes 14 do not have to be formed at equal intervals, or all of the intervals may be different.

[0040] The long first substrate 12 on which the first electrodes 14 are formed is, for example, wound into a roll and supplied to the manufacturing method of the present invention as a first substrate roll 12R. Note that in the manufacturing method of the present invention, the method of supplying the long first substrate 12 on which the first electrodes 14 are formed is not limited to this method, and various known methods can be used.

[0041] On the other hand, a second electrode 18 is formed on one surface of the second substrate 16, and a photoelectric conversion layer 20 is formed by stacking on this second electrode 18. Like the first substrate 12, the second substrate 16 is also elongated, and a plurality of second electrodes 18, etc. are formed and arranged in the longitudinal direction. The formation intervals of the second electrodes 18, etc. formed on the second substrate 16 are equal to the formation intervals of the first electrodes 14 formed on the first substrate 12.

[0042] In this example, as an example, the second substrate 16 is pulled out from a roll around which the long second substrate 16 is wound, and while being transported in the longitudinal direction, the second electrode 18, the electron transport layer 30, the perovskite layer 32, and the hole transport layer 34 are sequentially formed, and then the long second substrate 16 on which the second electrode 18 and the photoelectric conversion layer 20 are formed is supplied to the manufacturing method of the present invention. Note that in the manufacturing method of the present invention, the method of supplying the long second substrate 16 on which the second electrode 18 and the photoelectric conversion layer 20 are formed is not limited to this method, and various known methods can be used.

[0043] 1 , the first substrate 12 having the first electrode 14 formed thereon is pulled out from the first substrate roll 12R, transported in the longitudinal direction, and has its transport path changed by the guide roller 46 before reaching the first adhesive layer forming means 38. In the following description, the first substrate 12 having the first electrode 14 formed thereon will also be simply referred to as the "first substrate 12." In the manufacturing method of the present invention, among the rollers (rollers) provided as transport means, the roller that contacts the formation surface of the components of the solar cell 10, such as the guide roller 46, may be a normal roller (straight roller), or may be a roller with a small diameter in the center, such as a stepped roller whose central diameter is smaller than the diameters at both ends, or an inverted crown roller (concave roller), so that the roller does not contact the components of the solar cell 10.

[0044] In the manufacturing method of the present invention, the first substrate 12 transported to the first adhesive layer forming means 38 is transported in the longitudinal direction, and a frame-shaped first inorganic adhesive layer 26 surrounding the first electrode 14 is formed on the first substrate 12 by the first adhesive layer forming means 38, as conceptually shown in Figure 3 (first inorganic adhesive layer forming process).

[0045] On the other hand, the second substrate 16 on which the second electrode 18 and the photoelectric conversion layer 20 are formed is transported in the longitudinal direction to reach a second adhesive layer forming means 40. In the following description, the second substrate 16 on which the second electrode 18 and the photoelectric conversion layer 20 are formed will also be simply referred to as the "second substrate 16." In the manufacturing method of the present invention, while the second substrate 16 transported to the second adhesive layer forming means 40 is transported in the longitudinal direction, a frame-shaped second inorganic adhesive layer 28 surrounding the second electrode 18 (the second electrode 18 and the photoelectric conversion layer 20) is formed on the second substrate 16 by the second adhesive layer forming means 40, as conceptually shown in FIG. 4 (second inorganic adhesive layer forming step). As will be described in detail later, in the manufacturing method of the present invention, the first substrate 12 and the second substrate 16 on which the first inorganic adhesive layer 26 and the second inorganic adhesive layer 28 have been formed are transported, and the first substrate 12 and the second substrate 16 are bonded together using the first inorganic adhesive layer 26 and the second inorganic adhesive layer 28, thereby sealing the solar cell (bonding process).

[0046] In the manufacturing method of the present invention, there are no limitations on the materials for forming the first inorganic adhesive layer 26 and the second inorganic adhesive layer 28, and various known inorganic compounds that can adhere (bond) by contact can be used. In the following description, when there is no need to distinguish between the first inorganic adhesive layer 26 and the second inorganic adhesive layer 28, they will be collectively referred to simply as "inorganic adhesive layers." Examples of materials for forming the inorganic adhesive layer include silicon oxides such as silicon oxide, silicon nitrides such as silicon nitride, silicon oxynitrides such as silicon oxynitride, and aluminum oxides such as aluminum oxide. Among these, silicon oxide, silicon nitride, and aluminum oxide are preferred examples.

[0047] There is no limitation on the width of the inorganic adhesive layer, i.e., the width of the frame of the inorganic adhesive layer surrounding the electrode, and the width may be appropriately set so as to obtain the necessary adhesive strength (adhesion strength, adhesion strength) depending on the material for forming the inorganic adhesive layer and the size (area) of the electrode, etc. The width of the inorganic adhesive layer is preferably 1 to 20 mm, and more preferably 2 to 10 mm.

[0048] The thickness of the inorganic adhesive layer may be appropriately set so that the total thickness of the first inorganic adhesive layer 26 and the second inorganic adhesive layer 28 allows the first electrode 14 to be in full contact with the photoelectric conversion layer 20 (hole transport layer 34) and also allows the first inorganic adhesive layer 26 to be in full contact with the second inorganic adhesive layer 28. That is, the thicknesses of the first inorganic adhesive layer 26 and the second inorganic adhesive layer 28 may be set so that the total thickness of the first inorganic adhesive layer 26 and the second inorganic adhesive layer 28 is equal to the total thickness of the first electrode 14, the photoelectric conversion layer 20, and the second electrode 18. As an example, as shown in FIG. 2 , a configuration is exemplified in which the thickness of the first inorganic adhesive layer 26 is equal to the thickness of the first electrode 14, and the thickness of the second inorganic adhesive layer 28 is equal to the total thickness of the second electrode 18 and the photoelectric conversion layer 20.

[0049] There are no limitations on the method for forming the inorganic adhesive layer, and any known method can be used depending on the material for forming the inorganic adhesive layer as long as it is a method that can form the inorganic adhesive layer while transporting the substrate. A preferred method for forming the inorganic adhesive layer is a method of forming (depositing) the inorganic adhesive layer using atmospheric pressure plasma. By forming the inorganic adhesive layer using atmospheric pressure plasma, the inorganic adhesive layer can be preferably formed while transporting the substrate.

[0050] Here, various known atmospheric pressure plasma film formation methods can be used to form the inorganic adhesive layer using atmospheric pressure plasma, such as a method using a parallel plate atmospheric pressure plasma source. Among these, a method using an irradiation type atmospheric pressure plasma source, in which plasma and film formation materials are discharged from a nozzle to form a film using atmospheric pressure plasma, is exemplified. By forming the inorganic adhesive layer using an irradiation type atmospheric pressure plasma source, it is possible to more suitably form the inorganic adhesive layer surrounding the electrode while transporting the substrate.

[0051] An example of such a plasma source is conceptually shown in Figure 6. The irradiation-type atmospheric pressure plasma source 50 shown in Figure 6 has a double-tube structure, and includes an inner tube 52, an outer tube 54, a ground electrode 56, a high-voltage electrode 58, and a power supply 60.

[0052] The inner tube 52 and the outer tube 54 are nozzles in the irradiation-type atmospheric pressure plasma source. The inner tube 52 and the outer tube 54 are made of a high-melting-point insulating material (dielectric material), such as a glass material such as quartz or a ceramic material such as alumina. The inner tube 52 and the outer tube 54 are both circular tubes, and the inner tube 52 is inserted into the outer tube 54 with their centerlines aligned. In the irradiation-type atmospheric pressure plasma source 50, the gap 62 between the inner tube 52 and the outer tube 54 serves as a supply path for plasma gas (plasma generating gas) PG and a flow path for the generated plasma P.

[0053] The ground electrode 56 and the high-voltage electrode 58 are both cylindrical electrodes with an inner diameter substantially equal to the outer diameter of the outer tube 54, and are disposed so as to pass through the outer tube 54. The ground electrode 56 and the high-voltage electrode 58 are disposed spaced apart in the direction of the center line of the outer tube 54, with the high-voltage electrode 58 on the plasma irradiation side. The ground electrode 56 is also grounded (earthed). The high-voltage electrode 58 is connected to a power source 60. The power source 60 is, for example, a high-frequency pulse power source, and applies a pulsed voltage of a predetermined frequency to the high-voltage electrode 58.

[0054] In the irradiation-type atmospheric pressure plasma source 50, plasma gas PG is supplied from a supply source (not shown) into the gap 62 between the inner tube 52 and the outer tube 54. At this time, when a pulsed voltage is applied from the power supply 60 to the high-voltage electrode 58, a discharge region DA is formed between the ground electrode 56 and the high-voltage electrode 58, and this discharge acts on the plasma gas PG flowing in the discharge region DA, generating plasma P. The generated plasma P flows further through the gap 62 due to the flow of the plasma gas PG, and is supplied to the surface of the substrate from the end of the double tube consisting of the inner tube 52 and the outer tube 54, i.e., the end of the nozzle.

[0055] Here, the irradiating atmospheric pressure plasma source 50 has a double-tube structure consisting of an inner tube 52 and an outer tube 54, and a source gas MG, which is a film-forming material, can be flowed inside the inner tube 52. That is, with the irradiating atmospheric pressure plasma source 50, the source gas MG can be supplied between the irradiating atmospheric pressure plasma source 50 and the substrate using the inner tube 52, together with the plasma P. Therefore, with the irradiating atmospheric pressure plasma source 50, the source gas MG can be excited and decomposed by the plasma P, and an inorganic adhesive layer can be formed by the source gas MG.

[0056] In the manufacturing method of the present invention, the irradiation-type atmospheric pressure plasma source is not limited to the example shown in FIG. 6 , and various known irradiation-type atmospheric pressure plasma sources that discharge plasma and film-forming materials from a nozzle to form a film using atmospheric pressure plasma can be used.

[0057] When forming an inorganic adhesive layer using atmospheric pressure plasma, there are no limitations on the plasma gas PG and the source gas MG, and known gases may be used depending on the inorganic adhesive layer to be formed. For example, when forming a silicon oxide layer as the inorganic adhesive layer, examples of the plasma gas PG include helium gas, and examples of the source gas MG include TEOS (tetraethoxysilane) and oxygen gas. Furthermore, when forming a silicon nitride layer as the inorganic adhesive layer, examples of the plasma gas PG include helium gas, and examples of the source gas MG include HMDS (hexamethyldisilazane) and nitrogen gas.

[0058] In the manufacturing method of the present invention, a method using spray coating can also be suitably used as a method for forming the inorganic adhesive layer. For example, the inorganic adhesive layer may be formed by dissolving polysilazane and a compound that will become the inorganic adhesive layer, such as an inorganic nanosheet, in an organic solvent to prepare a coating material, spraying the coating material in a frame shape surrounding the electrode with a sprayer, and then drying the coating material solution.

[0059] An example of forming an inorganic adhesive layer using an irradiation-type atmospheric pressure plasma source as shown in Fig. 6 may be performed as conceptually shown in Fig. 5. This formation method can also be used to form an inorganic adhesive layer by spray coating. While Fig. 5 shows an example in which a first inorganic adhesive layer 26 is formed to surround the first electrode 14, a second inorganic adhesive layer 28 that surrounds the second electrode 18 can also be formed in a similar manner.

[0060] 5 uses four irradiating atmospheric pressure plasma sources 50. In this method, one irradiating atmospheric pressure plasma source 50 corresponds to one side (one side of the frame) of the first inorganic adhesive layer 26 surrounding the first electrode 14, and the four irradiating atmospheric pressure plasma sources 50 are moved in synchronization with the transport of the first substrate 12 to form the first inorganic adhesive layer 26. In the following description, for convenience, the side of the first electrode 14 that is longer in the longitudinal direction of the first substrate 12 will also be simply referred to as the "side in the substrate longitudinal direction." Furthermore, the side of the first electrode 14 that is longer in the width direction of the first substrate 12 will also be simply referred to as the "side in the substrate width direction."

[0061] 5 , two irradiating atmospheric pressure plasma sources 50 are moved in the opposite direction to the transport direction of the first substrate 12 in synchronization with the transport of the first substrate 12 indicated by the arrows, so as to be parallel to the sides of the first electrode 14 in the substrate longitudinal direction. This forms two first inorganic adhesive layers 26 corresponding to the sides of the first electrode 14 in the substrate longitudinal direction. Furthermore, in synchronization with the transport of the first substrate 12 indicated by the arrows, the two irradiating atmospheric pressure plasma sources 50 are moved in the width direction (approximately the width direction) of the first substrate 12 in synchronization with the transport of the first substrate 12 indicated by the arrows, so as to be parallel to the sides of the first electrode 14 in the substrate width direction. Therefore, the irradiating atmospheric pressure plasma sources 50 corresponding to the sides in the substrate width direction move in a direction inclined toward the transport direction with respect to the width direction of the first substrate 12, depending on the transport speed of the first substrate 12. This forms two first inorganic adhesive layers 26 corresponding to the sides of the first electrode 14 in the substrate width direction. By the above operation, the first inorganic adhesive layer 26 surrounding the first electrode 14 can be formed while the first substrate 12 is being transported.

[0062] 1 , after the first inorganic adhesive layer 26 is formed, the first substrate 12 is preferably transported to a first processing means 42, where an activation treatment is performed on the first inorganic adhesive layer 26. On the other hand, after the second inorganic adhesive layer 28 is formed, the second substrate 16 is preferably transported to a second processing means 44, where an activation treatment is performed on the first inorganic adhesive layer 26. By performing the activation treatment on the first inorganic adhesive layer 26 and the second inorganic adhesive layer 28, the adhesive strength between the first inorganic adhesive layer 26 and the second inorganic adhesive layer 28 is strengthened, and the first substrate 12 and the second substrate 16 can be more suitably bonded to each other.

[0063] In the manufacturing method of the present invention, the activation treatment method for the inorganic adhesive layer is not limited, and various known methods can be used, such as a method of irradiating the inorganic adhesive layer with atmospheric pressure plasma, a method of colliding particles having kinetic energy with the inorganic adhesive layer using a particle beam source, and a method of irradiating the inorganic adhesive layer with ultraviolet light.

[0064] Among these, an activation treatment in which atmospheric pressure plasma is irradiated onto the inorganic adhesive layer to introduce functional groups that contribute to adhesion, such as "-OH groups," onto the surface of the inorganic adhesive layer is a preferred example. In particular, atmospheric pressure plasma irradiation using the above-mentioned irradiating atmospheric pressure plasma source is preferably used.

[0065] Activation of the inorganic adhesive layer by irradiation with atmospheric pressure plasma can be performed essentially in the same manner as formation of the inorganic adhesive layer, by using only plasma gas without using any raw material gas. For example, using the irradiation-type atmospheric pressure plasma source 50 shown in Fig. 6, activation of the first inorganic adhesive layer 26 can be performed by supplying only plasma gas PG without supplying raw material gas MG, and moving four irradiation-type atmospheric pressure plasma sources 50 along the sides of the first electrode 14 as shown in Fig. 5.

[0066] In the manufacturing method of the present invention, the activation treatment of the first inorganic adhesive layer 26 and the activation treatment of the second inorganic adhesive layer 28 are performed as preferred embodiments but are not essential. Therefore, in the manufacturing method of the present invention, the activation treatment of the first inorganic adhesive layer 26 and the second inorganic adhesive layer 28 does not have to be performed. Alternatively, the activation treatment may be performed on only one of the first inorganic adhesive layer 26 and the second inorganic adhesive layer 28. However, considering the adhesive strength between the first inorganic adhesive layer 26 and the second inorganic adhesive layer 28, it is preferable to perform the activation treatment on either the first inorganic adhesive layer 26 or the second inorganic adhesive layer 28, and it is more preferable to perform the activation treatment on both the first inorganic adhesive layer 26 and the second inorganic adhesive layer 28.

[0067] Furthermore, in the manufacturing method of the present invention, the activation treatment of the inorganic adhesive layer is preferably performed immediately before bonding the first substrate 12 and the second substrate 16. That is, in the manufacturing method of the present invention, it is preferable to bond the first substrate 12 and the second substrate 16 as quickly as possible after performing the activation treatment of the inorganic adhesive layer. Specifically, in the manufacturing method of the present invention, the bonding of the first substrate 12 and the second substrate 16 is preferably performed within 120 seconds, and more preferably within 60 seconds, after performing the activation treatment of the inorganic adhesive layer.

[0068] 1 , after the activation treatment is performed on the first inorganic adhesive layer 26 and the second inorganic adhesive layer 28, the first substrate 12 and the second substrate 16 are laminated together by a laminating roller pair 48 with the first inorganic adhesive layer 26 and the second inorganic adhesive layer 28 facing each other. Therefore, in the manufacturing method shown in FIG. 1 , the first substrate 12 and the second substrate 16 are conveyed synchronously by the laminating roller pair 48 so that the first inorganic adhesive layer 26 and the second inorganic adhesive layer 28 face each other.

[0069] By laminating the first substrate 12 and the second substrate 16, the first inorganic adhesive layer 26 of the first substrate 12 and the second inorganic adhesive layer 28 of the second substrate 16 are bonded together (bonding process), thereby manufacturing a solar cell 10 sealed with the first substrate 12 and the second substrate 16, as well as the first inorganic adhesive layer 26 and the second inorganic adhesive layer 28. The solar cell 10 manufactured in this manner is then provided to the next process, for example, after the first substrate 12 and the second substrate 16 are cut into individual solar cells.

[0070] As described above, in the manufacturing method of the present invention, an inorganic adhesive layer is formed on a substrate while the substrate is continuously transported. Preferably, in the manufacturing method of the present invention, an inorganic adhesive layer is formed on the substrate while the substrate is continuously transported by roll-to-roll. Preferably, while the substrate is continuously transported as is, an activation treatment of the inorganic adhesive layer is then performed as a preferred embodiment, and then the first substrate 12 and the second substrate 16 are bonded. That is, in the manufacturing method of the present invention, the inorganic adhesive layer is formed without stopping the substrate transport, as in the formation of an inorganic adhesive layer using a mask. Preferably, the activation treatment of the inorganic adhesive layer and the bonding of the first substrate 12 and the second substrate 16 are performed without stopping the substrate transport. Therefore, the manufacturing method of the present invention allows for high productivity production of solar cells 10 sealed with the first substrate 12 and the second substrate 16, and the first inorganic adhesive layer 26 and the second inorganic adhesive layer 28. Furthermore, in the manufacturing method of the present invention, the first substrate 12 and the second substrate are attached by bonding the first inorganic adhesive layer 26 and the second inorganic adhesive layer 28 that surround the electrode (photoelectric conversion layer 20). Therefore, in the manufactured solar cell 10, it is possible to prevent moisture and the like from penetrating into the perovskite layer 32 from the inorganic adhesive layer, and to suppress deterioration of the perovskite layer 32 due to moisture and the like.

[0071] In the manufacturing method of the present invention, if necessary, after the first substrate 12 and the second substrate 16 are bonded together, heating may be performed to improve the adhesive strength between the first inorganic adhesive layer 26 and the second inorganic adhesive layer 28. Furthermore, in the manufacturing method of the present invention, if necessary, after the first substrate 12 and the second substrate 16 are bonded together, pressure may be applied to improve the adhesive strength between the first inorganic adhesive layer 26 and the second inorganic adhesive layer 28. Alternatively, in the manufacturing method of the present invention, if necessary, after the first substrate 12 and the second substrate 16 are bonded together, heating and pressure may be applied to improve the adhesive strength between the first inorganic adhesive layer 26 and the second inorganic adhesive layer 28.

[0072] There are no limitations on the heating method, and known methods such as a method using a heating roller, a method using a heater, or a method using hot air can be used. There are also no limitations on the pressurizing method, and known methods such as a method using a pressure roller can be used. It is preferable that the heating, pressurizing, and heat-and-pressurizing be performed while the accumulated first substrate 12 and second substrate 16 are being transported. The heating, pressurizing, and heat-and-pressurizing may also be performed by a lamination roller pair 48.

[0073] There is no limitation on the heating temperature for improving adhesive strength, and it may be set appropriately depending on the material for forming the inorganic adhesive layer. The heating temperature is preferably 50 to 150°C, and more preferably 60 to 100°C. There is also no limitation on the pressure for applying pressure for improving adhesive strength, and it may be set appropriately depending on the material for forming the inorganic adhesive layer. The pressure for applying pressure is preferably 0.1 to 100 MPa, and more preferably 5 to 50 MPa.

[0074] The method for manufacturing a solar cell of the present invention has been described in detail above, but the present invention is not limited to the above examples, and various improvements and modifications may be made within the scope of the present invention.

[0075] The present invention can be suitably used for manufacturing solar cells by roll-to-roll or the like.

[0076] REFERENCE SIGNS LIST 10 Solar cell 12 First substrate 14 First electrode 16 Second substrate 18 Second electrode 20 Photoelectric conversion layer 26 First inorganic adhesive layer 28 Second inorganic adhesive layer 30 Electron transport layer 32 Perovskite layer 34 Hole transport layer 38 First adhesive layer forming means 40 Second adhesive layer forming means 42 First processing means 44 Second processing means 46 Guide roller 48 Pair of laminating rollers 50 Radiation type atmospheric pressure plasma source 52 Inner tube 54 Outer tube 56 Ground electrode 58 High voltage electrode 60 Power source P Plasma PG Plasma gas MG Raw material gas DA Discharge area

Claims

1. A method for manufacturing a solar cell, comprising: a first inorganic adhesive layer formation step of transporting a flexible first substrate having a first electrode formed on one surface side thereof, and forming a first inorganic adhesive layer around the first electrode; a second inorganic adhesive layer formation step of transporting a flexible second substrate having a second electrode and a perovskite-type photoelectric conversion layer formed on one surface side thereof, and forming a second inorganic adhesive layer around the second electrode; and a bonding step of transporting the first substrate and the second substrate, and bonding the first substrate and the second substrate together using the first inorganic adhesive layer and the second inorganic adhesive layer.

2. The method for manufacturing a solar cell according to claim 1, wherein the first inorganic adhesive layer and the second inorganic adhesive layer are formed using atmospheric pressure plasma.

3. The method for producing a solar cell according to claim 2, wherein the atmospheric pressure plasma is an irradiation type atmospheric pressure plasma.

4. The method for producing a solar cell according to claim 1 or 2, wherein prior to the bonding step, an activation treatment is performed on at least one of the first inorganic adhesive layer and the second inorganic adhesive layer.

5. The method for producing a solar cell according to claim 4, wherein the activation treatment is a treatment using atmospheric pressure plasma.

6. The method for producing a solar cell according to claim 5, wherein the treatment with atmospheric pressure plasma is a treatment with irradiative atmospheric pressure plasma.

7. The method for manufacturing a solar cell according to claim 1 or 2, wherein at least one of the first substrate and the second substrate has gas barrier properties.

8. The method for manufacturing a solar cell according to claim 1 or 2, wherein the first substrate and the second substrate are long and are transported in the longitudinal direction.

9. A method for manufacturing a solar cell as described in claim 8, wherein the first substrate has a plurality of the first electrodes arranged in the longitudinal direction, and the second substrate has a plurality of the second electrodes and the perovskite type photoelectric conversion layer arranged in the longitudinal direction.

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