JP7623697B2 - Perovskite Solar Cells - Google Patents

Description

This invention relates to perovskite solar cells.

Perovskite solar cells are vulnerable to water, and creating a device structure that prevents water from entering the device is a challenge. WO2018/052032 describes a structure in which the entire side of the organic insulating layer that covers the entire perovskite solar cell is sealed. In this device, water is likely to penetrate through the organic insulating layer provided between the flexible substrate made of metal foil and the transparent electrode (40), so the organic insulating layer is sealed with a barrier layer. However, the problem of water penetrating through the interface between the barrier layer and the transparent electrode (40) has not been resolved.

WO2018/052032 publication

One of the aims of this invention is to provide a highly durable perovskite solar cell.

The above problems can basically be solved by providing a sealant layer that extends to the back surface of the substrate.
The present invention relates to a solar cell 1 .
The solar cell 1 is
A support 11 having a first surface and a second surface;
A solar cell element 4 provided on a first surface of a support 11;
An adhesive layer 13 that covers the entire solar cell element 4;
a sealant layer 14 that covers the entire adhesive layer 13;
Includes.
If the distance from the end of the adhesive layer 13 to the end of the support 11 is d ₁ ,
It is preferable that _d1 is 0.5 mm or more and 2 cm or less.
The sealant layer 14 is preferably a layer constituted by a single sealant film.

The solar cell element 4 is
An electrode 40;
A photoelectric conversion layer 47 containing a perovskite compound;
and a back electrode 49, in this order.

The sealant layer 14 is
A main body 12 for covering an adhesive layer 13 portion on the solar cell element 4;
a first end region 15 that is continuous with the main body portion 12 and extends to an end of the first surface;
The second end region 17 is continuous with the first end region 15 and continues to the second surface (exists on the second surface). If the distance from the end of the support 11 to the point where the end of the second end region 17 exists is _d2 , then _d2 is preferably 0.2 mm or more and 1 cm or less.

The sealant layer 14 is
a first partial sealant layer 14a including a main body portion 12;
The second partial sealant layer 14 b may cover the end of the first partial sealant layer 14 a and constitute a region including the second end region 17 .

This invention makes it possible to provide a highly durable perovskite solar cell that can prevent water intrusion.

FIG. 1 is a conceptual diagram showing an example of a cross-sectional view of a solar cell. FIG. 2 is a conceptual diagram showing an example of a cross-sectional view of a solar cell. FIG. 3 is a conceptual diagram showing an example of a cross-sectional view of a solar cell. FIG. 4 is a conceptual diagram showing an example of a cross-sectional view of a solar cell. FIG. 5 is a conceptual diagram showing an example of a cross-sectional view of a solar cell. FIG. 6 is a conceptual diagram showing an example of the structure of a perovskite solar cell element (normal type). FIG. 7 is a conceptual diagram showing an example of the structure of a perovskite solar cell element (inverted type). FIG. 8 is a conceptual diagram showing an example of the back surface (second surface) of a solar cell.

Below, the embodiments for carrying out the present invention will be explained using the drawings. The present invention is not limited to the embodiments described below, but also includes appropriate modifications of the embodiments below within the scope that would be obvious to a person skilled in the art.

Below, the embodiments for carrying out the present invention will be explained using the drawings. The present invention is not limited to the embodiments described below, but also includes appropriate modifications of the embodiments below within the scope that would be obvious to a person skilled in the art.

Solar Cell The first invention relates to a solar cell. Figures 1 to 5 are conceptual diagrams showing cross-sections of a solar cell. As shown in Figures 1 to 5, this solar cell 1 has a first support 11, a (perovskite) solar cell element 4, an adhesive layer 13, and a sealant layer 14. The sealant layer 14 has a main body portion 12 of the sealant layer covering the adhesive layer 13 on the solar cell element 4, a first end region 15, and a second end region 17. It is preferable that the main body portion of the sealant layer and each end region are continuously connected.

The example shown in Figure 1 will be described. In this example, the adhesive layer 13 is a single layer. The adhesive layer 13 covers the solar cell element 4 and extends beyond the end of the solar cell element 4 on the first surface of the support 11. In this way, the adhesive layer 13 seals the solar cell element 4. The sealant layer 14 covers the entire adhesive layer 13. The sealant layer 14 extends not only to the first surface of the support, but also to the second surface (rear surface). In this example, the sealant layer 14 is composed of a single film.

The example shown in FIG. 2 will be described. In this example, the sealant layer 14 includes a first partial sealant layer 14a and a second partial sealant layer 14b. The first partial sealant layer 14a is a layer that constitutes the portion of the sealant layer 14 that includes the main body portion 12. The second partial sealant layer 14b covers the end portion 18 of the first partial sealant layer 14a and constitutes a region that includes the second end portion region 17. In this example, the end portion region 18, which will be described later, is present at the end portion of the first partial sealant layer 14a.

The example of FIG. 3 will be described. In this example, the adhesive layer 13 (first adhesive layer 13a) covers the solar cell element 4. The first partial sealant layer 14a is present so as to cover the upper region of the first adhesive layer 13a (and the solar cell element 4). In this example, the first partial sealant layer 14a covers the side surface of the first adhesive layer 13a and the solar cell element 4. In this way, the first partial sealant layer 14a functions as a sealant. Meanwhile, the second adhesive layer 13b bonds the first partial sealant layer 14a and the second partial sealant layer 14b, and also bonds the surface portion of the support 11 (where the first partial sealant layer 14a does not exist) to the second partial sealant layer 14b. The end of the second adhesive layer 13b and the end of the second partial sealant layer 14b on the back surface (second surface) of the support 11 may be in the same position. Either the end of the second adhesive layer 13b or the end of the second partial sealant layer 14b on the back surface (second surface) of the support 11 may be present first. In any case, it is preferable that either or both of the end of the second adhesive layer 13b and the end of the second partial sealant layer 14b on the back surface (second surface) of the support 11 are treated in the same manner as the end region 18 described below, and are in the same condition.

The example in Figure 4 will be described. Unlike the example in Figure 3, this example does not cover the first partial sealant layer 14a and the side surface of the first adhesive layer 13a and the solar cell element 4. Each element will be described below.

The example in Figure 5 will be described. In this example, the adhesive layer in the example in Figure 1 extends to the back surface (second surface) of the support 11.

Support 11
As the support 11, a known substrate for an organic solar cell or an organic EL element can be appropriately used. Examples of the substrate include glass, a plastic plate, a plastic film, and an inorganic crystal. In addition, a substrate having at least one film selected from a metal film, a semiconductor film, a conductive film, and an insulating film formed on a part or all of the surface of the substrate can also be preferably used. In particular, in order to reduce the thickness and weight, the support is preferably a flexible substrate.

Solar cell element 4
The solar cell element means an element having a function of generating electricity by receiving light such as sunlight. The solar cell element is preferably one having a shape in which a perovskite layer (light absorption layer/photoelectric conversion layer) is sandwiched between an electron transport layer and a hole transport layer. The perovskite layer is preferably a perovskite layer made of an organic-inorganic hybrid compound. As shown in FIG. 6, the solar cell element 4 may have a normal structure in which an electron transport layer 46, a perovskite layer 47, a hole transport layer 48, and a back electrode 49 are formed from the transparent electrode 40 side. Also, as shown in FIG. 7, the solar cell element 4 may have either an inverted structure in which a hole transport layer 48, a perovskite layer 47, an electron transport layer 46, and a back electrode 49 are formed from the transparent electrode 40 side.

Electrode 40
The electrode is preferably a transparent electrode for transmitting light. The transparent electrode is a support for the electron transport layer and has a function of extracting electrons from the perovskite layer (light absorption layer/photoelectric conversion layer). The electrode is formed on the support 11. The transparent electrode is formed from a conductor, and specific examples thereof include a tin-doped indium oxide (ITO) film, an impurity-doped indium oxide (In ₂ O ₃ ) film, an impurity-doped zinc oxide (ZnO) film, a fluorine-doped tin dioxide (FTO) film, a laminated film formed by laminating these, gold, silver, copper, aluminum, tungsten, titanium, chromium, nickel, cobalt, etc. These may be used alone or in a mixture of two or more types, and may be a single layer or a laminate. These films may function as, for example, a diffusion prevention layer. There is no particular limit to the thickness of these electrodes, and it is usually preferable to adjust the sheet resistance to 5 to 15 Ω/□ (per unit area). The electrodes can be obtained by a known film-forming method according to the material to be formed. In addition, these electrodes may be formed in a film shape or a lattice shape such as a mesh shape. A known method is used to form the electrodes on the support, and vacuum film formation such as vacuum deposition or sputtering is preferable. In addition, the transparent electrodes may be patterned, and examples of the method include a method of immersing in a laser or etching solution, and a method of patterning using a mask during vacuum film formation, and any method may be used in the present invention.

Electron transport layer 46
The electron transport layer 46 is preferably an electron transporting semiconductor, and examples of the semiconductor include oxides of titanium, tin, zinc, iron, tungsten, zirconium, indium, cerium, yttrium, aluminum, magnesium, vanadium, and niobium, and metal chalcogenides such as cadmium, zinc, lead, silver, antimony, and bismuth sulfides, cadmium and lead selenides, and cadmium telluride. Among these, oxides are particularly preferred. Among these, zinc oxide, tin oxide, and titanium oxide are particularly preferred. The electron transport layer may be a single layer or a multilayer. In the case of a multilayer, the layer may be porous, with semiconductor particles of different particle sizes coated in multiple layers. In the case of a porous layer, the particle size of the semiconductor particles is preferably 3 to 100 nm, and more preferably 5 to 70 nm. The film thickness is preferably 5 to 1000 nm, and more preferably 10 to 500 nm.

There are no particular limitations on the method for forming the electron transport layer. It can be either vacuum film formation such as sputtering or ion plating, or wet film formation such as sol-gel.

Hole transport layer 48
The hole transport layer 48 is a layer having a function of transporting charges. For example, a conductor, a semiconductor, an organic hole transport material, etc. can be used for the hole transport layer. The material can function as a hole transport material that receives holes from the perovskite layer (light absorbing layer) and transports the holes. Examples of the conductor and semiconductor include compound semiconductors containing monovalent copper such as CuI, CuInSe ₂ , and CuS; and compounds containing metals other than copper such as GaP, NiO, CoO, FeO, Bi ₂ O ₃ , MoO ₂ , and Cr ₂ O _3. Among them, from the viewpoint of more efficiently receiving only holes and obtaining higher hole mobility, a semiconductor containing monovalent copper is preferable, and CuI is more preferable. Examples of organic hole transport materials include polythiophene derivatives such as poly-3-hexylthiophene (P3HT) and polyethylenedioxythiophene (PEDOT); fluorene derivatives such as 2,2',7,7'-tetrakis-(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (Spiro-OMeTAD); carbazole derivatives such as polyvinylcarbazole; triphenylamine derivatives such as poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA); diphenylamine derivatives; polysilane derivatives; polyaniline derivatives, etc. Among these, from the viewpoint of more efficiently receiving only holes and obtaining higher hole mobility, triphenylamine derivatives, fluorene derivatives, etc. are preferred, and PTAA, Spiro-OMeTAD, etc. are more preferred.

In order to further improve the hole transport properties, the hole transport layer may contain an oxidizing agent such as lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), silver bis(trifluoromethylsulfonyl)imide, trifluoromethylsulfonyloxysilver, NOSbF6, SbCl5, SbF5, tris(2-(1H-pyrazol-1-yl)-4-tert-butylpyridine)cobalt(III)tri[bis(trifluoromethane)sulfonimide]. In addition, the hole transport layer may contain a basic compound such as t-butylpyridine (TBP), 2-picoline, 2,6-lutidine. The content of the oxidizing agent and basic compound may be the amount that has been conventionally used. The thickness of the hole transport layer is preferably, for example, 50 to 800 nm, more preferably 100 to 600 nm, from the viewpoint of more efficiently receiving only holes and obtaining higher hole mobility. The method of forming the hole transport layer is not particularly limited, and may be performed according to a known method. Examples include wet film formation methods such as dipping, spraying, spin coating, and blade coating, and vacuum film formation methods such as sputtering.

Perovskite layer (light absorption layer/photoelectric conversion layer) 47
The perovskite layer (light absorption layer/photoelectric conversion layer) 47 is a layer that absorbs light and transfers excited electrons and holes to perform photoelectric conversion. The perovskite compound in the present invention is preferably a composite material of an organic compound and an inorganic compound. The perovskite compound preferably exhibits a layered perovskite structure in which layers of metal halide and layers of aligned organic cation molecules are alternately stacked, and is represented by the following general formula (1).
XαYβMγ ... General formula (1)
In the above general formula (1), X is a halogen atom, Y is an alkylamine compound, M is at least one metal ion selected from lead, tin, indium, antimony, and bismuth, the ratio of α:β:γ is 3:1:1, and β and γ are integers greater than 1. X can be a halogen atom such as chlorine, bromine, or iodine, which can be used alone or as a mixture. Y can be an alkylamine compound such as methylamine, ethylamine, n-butylamine, or formamidine.

The flatness of the perovskite layer is preferably such that the height difference is 50 nm or less (-25 nm to +25 nm) in a range of 500 nm x 500 nm in the horizontal direction of the surface as measured by a scanning electron microscope, and more preferably the height difference is 40 nm or less (-20 nm to +20 nm). This makes it easier to balance the light absorption efficiency and the exciton diffusion length, and further improves the absorption efficiency of light reflected by the electrode.

Examples of methods for forming a perovskite layer include a one-step precipitation method in which a solution in which metal halides and alkylamine halides are dissolved or dispersed in a solvent is applied to the electron transport layer or hole transport layer and dried, or a two-step precipitation method in which a solvent in which metal halides are dissolved or dispersed is applied to the electron transport layer or hole transport layer, dried, and then immersed in a solution in which alkylamine halides are dissolved in the solvent to form a perovskite layer. In the one-step precipitation method, it is also possible to promote crystallization all at once by adding a solvent that does not dissolve the perovskite compound before complete application.

After forming the perovskite compound layer, a solution in which an amine halide compound is dissolved may be applied onto the perovskite layer. Examples of the amine halide compound used in this case include phenylethylamine bromide, phenylethylamine iodide, n-hexyltrimethylamine bromide, n-octadecylamine iodide, and 5-ammonium valerate iodide. They may be used alone or in combination of two or more types.

Rear electrode 49
Examples of the back electrode 49 include metals such as platinum, gold, silver, copper, aluminum, rhodium, nickel, cobalt, iron, palladium, and indium, carbon-based compounds such as graphite, graphene, and carbon nanotubes, conductive metal oxides such as ITO, indium-doped zinc oxide (IZO), and antimony-doped tin oxide (ATO), and conductive polymers such as polythiophene and polyaniline, and these may be used alone or in combination of two or more. The back electrode may be a transparent electrode. The thickness of the back electrode is not particularly limited, and the back electrode may be a single film of the above-mentioned materials or a mixture or laminate of two or more of them. The back electrode can be formed by applying, laminating, vacuum deposition, CVD, laminating, or other methods on the hole transport layer depending on the type of material used and the type of hole transport layer.

Adhesive layer 13
The adhesive layer is a layer that covers the solar cell element 4. The adhesive layer may cover the entire solar cell element or may cover a part of the solar cell element. The adhesive layer is a layer disposed between the support and the sealant layer (main body). The adhesive layer is used to bond the support and the sealant layer, as well as to bond the solar cell element on the support and the sealant layer. However, when the adhesive layer covers the entire solar cell element, it also has the function of sealing the solar cell element. There is no particular restriction on the material of the adhesive, and it can be appropriately selected according to the purpose. For example, a cured product of an acrylic resin or an epoxy resin can be used.
As the cured acrylic resin, any known material can be used as long as it is a cured monomer or oligomer having an acrylic group in the molecule, and as the cured epoxy resin, any known material can be used as long as it is a cured monomer or oligomer having an epoxy group in the molecule.

Epoxy resins include water-dispersed, solvent-free, solid, heat-cured, mixed with curing agent, and UV-cured. Of these, heat-cured and UV-cured are preferred, and UV-cured is more preferred. Even UV-cured resins can be heated, and it is preferred to heat them even after UV-cured. Specific examples of epoxy resins include bisphenol A, bisphenol F, novolac, cyclic aliphatic, long-chain aliphatic, glycidylamine, glycidyl ether, and glycidyl ester types, which may be used alone or in combination of two or more. It is also preferred to mix a curing agent or various additives with the epoxy resin as necessary. Epoxy resin compositions that are already available on the market can be used in the present invention. Among these, there are also epoxy resin compositions that have been developed and are available on the market for use in solar cells and organic EL elements, which can be used particularly effectively in the present invention. Examples of commercially available epoxy resin compositions include TB3118, TB3114, TB3124, TB3125F (manufactured by ThreeBond Co., Ltd.), World Rock5910, World Rock5920, World Rock8723 (manufactured by Kyoritsu Chemical Industries Co., Ltd.), and WB90US(P) (manufactured by MORESCO Co., Ltd.).

The curing agent is not particularly limited and can be appropriately selected according to the purpose. Examples of the curing agent include amine-based, acid anhydride-based, polyamide-based, and other curing agents. Examples of the amine-based curing agent include aliphatic polyamines such as diethylenetriamine and triethylenetetramine, and aromatic polyamines such as metaphenylenediamine, diaminodiphenylmethane, and diaminodiphenylsulfone. Examples of the acid anhydride-based curing agent include phthalic anhydride, tetrahydrophthalic anhydride and hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, pyromellitic anhydride, HET anhydride, and dodecenyl succinic anhydride. Examples of other curing agents include imidazoles and polymercaptan. These may be used alone or in combination of two or more.

The additives are not particularly limited and can be appropriately selected according to the purpose. Examples of the additives include a filler, a gap agent, a polymerization initiator, a drying agent (moisture absorbent), a hardening accelerator, a coupling agent, a flexibilizer, a colorant, a flame retardant assistant, an antioxidant, and an organic solvent. Among these, a filler, a gap agent, a hardening accelerator, a polymerization initiator, and a drying agent (moisture absorbent) are preferred, and a filler and a polymerization initiator are more preferred. By including a filler as an additive, it is possible to suppress the intrusion of moisture and oxygen, and further to obtain effects such as a reduction in volumetric shrinkage during hardening, a reduction in the amount of outgassing during hardening or heating, an improvement in mechanical strength, and control of thermal conductivity and fluidity. Therefore, including a filler as an additive is very effective in maintaining a stable output in various environments. The additive may be added to the sealant layer or the end region.

In addition, when it comes to the output characteristics and durability of solar cell elements, the effects of not only the intrusion of moisture and oxygen, but also the outgassing that occurs when the sealing material hardens or is heated cannot be ignored. In particular, the outgassing that occurs when heated has a significant effect on output characteristics when stored in a high-temperature environment. By incorporating a filler, gap agent, or desiccant into the adhesive layer or sealant layer, these themselves can suppress the intrusion of moisture and oxygen, and by reducing the amount of adhesive or sealant used, the effect of reducing outgassing can be obtained. Incorporating a filler, gap agent, or desiccant into the adhesive layer or sealant layer is effective not only during hardening, but also when storing solar cell elements in a high-temperature environment.

The filler is not particularly limited and can be selected appropriately depending on the purpose. Examples include crystalline or amorphous silica, silicate minerals such as talc, and inorganic fillers such as alumina, aluminum nitride, silicon nitride, calcium silicate, and calcium carbonate. Among these, hydrotalcite is particularly preferred. These may be used alone or in combination of two or more types.

The average primary particle size of the filler is preferably 0.1 μm or more and 10 μm or less, and more preferably 1 μm or more and 5 μm or less. If the average primary particle size of the filler is within the above preferred range, the effect of suppressing the intrusion of moisture and oxygen can be sufficiently obtained, the viscosity becomes appropriate, and the adhesion and degassing properties with the substrate are improved, and it is also effective in controlling the width of the sealant layer and in workability.

The content of the filler is preferably 10 parts by weight or more and 90 parts by weight or less, and more preferably 20 parts by weight or more and 70 parts by weight or less, relative to the total (100 parts by weight) of the adhesive layer, etc. When the content of the filler is within the above preferred range, the effect of suppressing the intrusion of moisture and oxygen is sufficiently obtained, the viscosity is appropriate, and the adhesion and workability are also good.

The gap agent is also called a gap control agent or a spacer agent. By including a gap agent as an additive, it becomes possible to control the gap of the sealant layer. For example, when an adhesive layer is applied on a first substrate or a first electrode, and a second substrate is placed on the adhesive layer to perform sealing, the gap of the sealant layer is aligned to the size of the gap agent because the adhesive layer or the sealant layer contains a gap agent, so that the gap of the sealant layer can be easily controlled.
The gap agent is not particularly limited as long as it is granular, has a uniform particle size, and has high solvent resistance and heat resistance, and can be appropriately selected according to the purpose. As the gap agent, one that has high affinity with the epoxy resin and has a spherical particle shape is preferable. Specifically, glass beads, silica fine particles, organic resin fine particles, etc. are preferable. These may be used alone or in combination of two or more types.
The particle size of the gap agent can be selected according to the gap in the end region of the sealant layer to be set, but is preferably 1 μm to 100 μm, more preferably 5 μm to 50 μm.

The polymerization initiator is not particularly limited as long as it initiates polymerization using heat or light, and can be appropriately selected depending on the purpose. Examples of the polymerization initiator include a thermal polymerization initiator and a photopolymerization initiator.
Thermal polymerization initiators are compounds that generate active species such as radicals and cations when heated, and include azo compounds such as 2,2'-azobisbutyronitrile (AIBN) and peroxides such as benzoyl peroxide (BPO). As thermal cationic polymerization initiators, benzenesulfonate esters, alkylsulfonium salts, etc. are used.
On the other hand, in the case of epoxy resin, a photo-cationic polymerization initiator is preferably used as the photo-polymerization initiator. When the photo-cationic polymerization initiator is mixed with the epoxy resin and irradiated with light, the photo-cationic polymerization initiator decomposes to generate acid, which then causes the epoxy resin to polymerize and the curing reaction proceeds. The photo-cationic polymerization initiator has the effects of causing little volumetric shrinkage during curing, not being inhibited by oxygen, and having high storage stability.

Examples of photo-induced cationic polymerization initiators include aromatic diazonium salts, aromatic iodonium salts, aromatic sulfonium salts, methacerone compounds, and silanol aluminum complexes. In addition, photo-induced acid generators that generate acid when irradiated with light can also be used as polymerization initiators. Photo-induced acid generators act as acids that initiate cationic polymerization, and examples of such agents include onium salts, such as ionic sulfonium salts and iodonium salts, which are composed of a cationic portion and an anionic portion. These agents may be used alone or in combination of two or more types.

The amount of polymerization initiator added may vary depending on the material used, but is preferably 0.5 parts by mass to 10 parts by mass, and more preferably 1 part by mass to 5 parts by mass, relative to the entire sealing member (100 parts by mass). By adding an amount within the above preferred range, curing proceeds properly, the amount of uncured material remaining can be reduced, and excessive outgassing can be prevented.

A desiccant (also called a moisture absorbent) is a material that has the function of physically or chemically adsorbing or absorbing moisture. By including it in the sealing material, it is possible to further increase the moisture resistance and reduce the effects of outgassing.
The desiccant is not particularly limited and may be appropriately selected depending on the purpose, but particulate desiccants are preferred, such as inorganic water-absorbing materials such as calcium oxide, barium oxide, magnesium oxide, magnesium sulfate, sodium sulfate, calcium chloride, silica gel, molecular sieves, and zeolite. Among these, zeolite, which has a high moisture absorption capacity, is preferred. These may be used alone or in combination of two or more types.

A curing accelerator (also called a curing catalyst) is a material that accelerates the curing speed and is mainly used for thermosetting epoxy resins.
The curing accelerator is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include tertiary amines or tertiary amine salts such as DBU (1,8-diazabicyclo(5,4,0)-undecene-7) and DBN (1,5-diazabicyclo(4,3,0)-nonene-5), imidazoles such as 1-cyanoethyl-2-ethyl-4-methylimidazole and 2-ethyl-4-methylimidazole, phosphines or phosphonium salts such as triphenylphosphine and tetraphenylphosphonium tetraphenylborate, etc. These may be used alone or in combination of two or more kinds.

The coupling agent is not particularly limited as long as it is a material that has the effect of increasing molecular bonding strength, and can be appropriately selected according to the purpose. For example, silane coupling agents can be mentioned. Specific examples include silane coupling agents such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, N-(2-aminoethyl)3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)3-aminopropylmethyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, vinyltrimethoxysilane, N-(2-(vinylbenzylamino)ethyl)3-aminopropyltrimethoxysilane hydrochloride, and 3-methacryloxypropyltrimethoxysilane. These may be used alone or in combination of two or more kinds.

In the present invention, a sheet-type adhesive can be used.
The sheet-like adhesive is a sheet on which a resin layer is formed in advance, and the sheet can be made of glass or a film with high gas barrier properties. The sheet may also be made of resin only. The sheet-like adhesive can be attached to a sealing film. It is also possible to create a structure with a hollow portion on the sealing film before attaching it to the device.

For example, in the solar cell shown in FIG. 1 or FIG. 2, the distance (first distance) between the end of the solar cell element and the end of the adhesive layer is preferably 0.5 mm or more and 2 cm or less. The end of the solar cell element means the outer part of the solar cell element. For example, when the solar cell element is rectangular, the part on the edge of the rectangle constitutes the end of the solar cell element. The end of the adhesive layer means the outermost edge of the adhesive layer. This first end-to-end distance means the closest one between the edge of the solar cell element and the end of the adhesive layer (the edge on the opposite side to the solar cell element). The first distance is preferably 1 mm or more, and more preferably 2 mm or more. However, the first distance may be adjusted appropriately depending on the size of the solar cell element. When the solar cell element is rectangular and the length of the long side is l, the first distance may be 0.01 l or more and 0.5 l or less, or 0.05 l or more and 0.2 l or less.

Next, assuming that the distance from the end of the adhesive layer 13 to the end of the support 11 is d ₁ , d ₁ is preferably 0.5 mm or more and 2 cm or less, preferably 1 mm or more, and may be 2 mm or more. d ₁ may be 0.01 l or more and 0.5 l or less, or may be 0.05 l or more and 0.2 l or less. When there are multiple adhesive layers, it is preferable that d ₁ is the above value for any one or more of the adhesive layers. In addition, when the adhesive layer 13 exists only on the front surface (first surface) of the support 11, the distance from the end of the area where the adhesive layer 13 exists to the end of the support 11 is d _1. On the other hand, as in the example shown in FIG. 5, when the adhesive layer 13 exists up to the back surface (second surface) of the support 11, the width (length) of the area where the adhesive layer 13 exists on the back surface is d ₁ .

Sealant layer (main body) 14
The sealant layer (main body) is formed to cover the adhesive layer and means a layer for preventing water and the like from entering the solar cell element. In order to distinguish it from the end region, it is also referred to as the sealant layer or the main body in this specification. The sealant layer is preferably one that covers the solar cell element and the adhesive layer. The sealant layer is disposed, for example, facing the support so as to sandwich the solar cell element including the photoelectric conversion layer and the electrode. The sealant layer may be composed of a sealant film. The shape, structure, size, and type (material) of the sealant layer are not particularly limited and can be appropriately selected according to the purpose. The sealant layer may be in the form of a thin film or a film.

The material constituting the sealant layer may be the same as the material of the adhesive layer. Other examples of the material of the sealant layer include a resin substrate having a barrier layer formed on the surface thereof to prevent the passage of moisture and oxygen, and the barrier layer may be formed on one or both sides of the substrate. In the latter case, the material of the resin substrate is not particularly limited, and examples thereof include polyolefin-based resins such as homopolymers or copolymers of ethylene, propylene, butene, etc.; amorphous polyolefin-based resins such as cyclic polyolefins; polyester-based resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN); polyamide-based resins such as nylon 6, nylon 66, nylon 12, and copolymer nylon; ethylene-vinyl acetate copolymer partial hydrolyzate (EVOH), polyimide-based resins, polyetherimide-based resins, polysulfone-based resins, polyethersulfone-based resins, polyetheretherketone-based resins, polycarbonate-based resins, polyvinyl butyral-based resins, polyarylate-based resins, fluororesins, acrylic resins, and biodegradable resins. Among these, polyester resins are preferred from the viewpoint of film properties such as heat resistance and transparency, and polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) are particularly preferred. The resin substrate may be made of one type of resin material or two or more types of resin materials.

The resin substrate may contain other materials, such as inorganic fillers, to improve the durability of the solar cell module. There are no particular limitations on the inorganic fillers, but examples include silica, mica, talc, clay, bentonite, montmorillonite, kaolinite, wollastonite, calcium carbonate, titanium oxide, alumina, barium sulfate, potassium titanate, and glass fiber. The inorganic fillers mixed into the resin substrate may be one type, or two or more types.

The barrier layer is composed mainly of metal oxides, metals, mixtures formed from polymers and metal alkoxides, and examples of such materials include aluminum oxide, silicon oxide, and aluminum. Examples of polymers include polyvinyl alcohol, polyvinylpyrrolidone, and methyl cellulose. Examples of metal alkoxides include tetraethoxysilane, triisopropoxyaluminum, 3-glycidoxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-isocyanatopropyltriethoxysilane.

The barrier layer may be transparent or opaque. The barrier layer may be a single layer made of a combination of the above materials, or may be a laminated structure of multiple layers. The barrier layer may be formed by any known method, including vacuum film formation such as sputtering, dipping, roll coating, screen printing, spraying, gravure printing, and other coating methods. The thickness of the main body of the sealant layer may be within the range generally used in this technology. For example, it may be set appropriately within the range of 0.05 to 1 mm.

The sealant layer preferably covers the entire adhesive layer, and is preferably larger than the adhesive layer in order to prevent the intrusion of water and oxygen.
In the example of FIG. 2, the distance (second distance) between the end of the adhesive layer 13 and the end region of the first sealant layer 14a is preferably 0.2 mm or more and 1 cm or less. The end of the adhesive layer is as described above. The end region of the sealant layer means a high-density region present at the outermost edge of the sealant layer. The distance between the end of the adhesive layer and the end region of the sealant layer means the distance at which the distance between the end of the adhesive layer and the end region of the sealant layer is the smallest. The second distance is preferably 0.5 mm or more, more preferably 1 mm or more. In addition, although the upper limit varies depending on the size and use of the solar cell, if it is too large, the solar cell (device) itself will become too large, or the parts other than the solar cell element will become too large and will be wasted, so 1 cm or less is preferable, 5 mm or less is preferable, and 4 mm or less is more preferable.

End region 18
The end region 18 means, for example, a region provided in the end region of the sealant layer 14, the first partial sealant layer 14a, or the second partial sealant layer 14b, and has a higher density than the main body of the sealant layer. The end region is provided to more firmly isolate the outer periphery of the sealant layer from water and oxygen. It is preferable that the end region is formed integrally with the sealant layer. The shape of the end region is not particularly limited. It is preferable that the shape of the end region is a shape obtained by compressing the main body.

The width of the end region (first width) is preferably 0.5 mm or more and 1.5 cm or less. The first width is preferably 1 mm or more, more preferably 1.5 mm or more, so as to prevent the intrusion of moisture and oxygen and to adhere closely to the sealant body so as not to peel off. In addition, if the solar cell (device) becomes too large, or if parts other than the solar cell element become too large, it will be wasted, so the width is preferably 1.5 cm or less, more preferably 1 cm or less, and more preferably 5 mm or less.

Furthermore, it is preferable that the end regions are made opaque, since this makes them easier to distinguish from the sealant layer (main body). Methods for making them opaque in this manner are not particularly limited, but include a method in which a filler usable in the adhesive layer or sealant layer (main body) is contained, or a method in which a known pigment or dye is contained. The cross-sectional shape of the end regions may be a flat shape parallel to the support. The thickness of the end regions may be less than or equal to the thickness of the sealant layer.

The end region can be formed, for example, by applying pressure to the end of the sealant layer (a portion other than the main body portion and located on the outer periphery) to crush the sealant layer. The pressure applied to the end region of the sealant layer is preferably 0.1 MPa to 10 MPa, and may be 1 MPa to 5 MPa. In the end pressure application step, the sealant layer is preferably compressed so that the thickness of the end region is 55% to 90% of the thickness before the end pressure application step, and may be compressed so that the thickness is 60% to 80%.

If the distance from the end of the support 11 to the point where the end of the second end region 17 exists is _d2 , _d2 is preferably 0.2 mm or more and 1 cm or less, preferably 1 mm or more, and may be 2 mm or more. _d1 may be 0.01 l or more and 0.5 l or less, or 0.05 l or more and 0.2 l or less. _d2 can also be said to be the width (width of the folded part) of the sealant layer 14 on the back surface (second surface) of the support 11. This width may be the same or different between the part on the long side of the support and the part on the short side of the support. In the example of FIG. 8, this width ( _d2 ) is the same between the part on the long side of the support and the part on the short side of the support.

Figure 8 is a conceptual diagram showing an example of the back surface (second surface) of a solar cell. Figure 8(a) shows an example of a sealant layer on the short side of the support that is overlaid on top of the sealant layer on the long side of the support and then pressed together. Figure 8(b) shows an example of a sealant layer on the long side of the support that is overlaid on top of the sealant layer on the short side of the support and then pressed together. Figure 8(c) shows an example of a sealant layer that has been processed so that the overlapping area is small (preferably, so that there is no overlapping area) when the sealant layer on the long side of the support and the sealant layer on the short side of the support are overlaid, and then the sealant layer is folded back on the back surface (second surface) of the support.

Solar cells are publicly known. Thus, a person skilled in the art can manufacture the solar cells described in this specification by referring to the above description and appropriately adopting publicly known methods. In addition, the methods of using solar cells are publicly known.

A glass substrate with ITO (25mm x 24.5mm, Geomatec) was ultrasonically cleaned for 15 minutes each with 2-propanol, acetone, Semicoclean 56 (cleaning solution for displays, product name, product of Furuuchi Chemical Co., Ltd.), water, and 2-propanol, in that order, and then plasma treated. Next, 300μL of water-soluble _SnO2 colloidal solution (a 15% _SnO2 colloidal solution diluted 1:1 with pure water and passed through a PTFE filter) was dropped onto the substrate as an electron transport layer, and a film was formed using spin coating (3000 rpm, 20 seconds), and then heated and dried at 150°C for 30 minutes. The substrate was moved to a glove box, and a perovskite precursor solution was prepared by dissolving CsI, MABr (methylammonium bromide, CH ₃ N.HBr), PbBr ₂ , PbI ₂ , and FAI (formamidine hydroiodide, CH ₄ N _2.HI ) in a mixed solvent of DMF and DMSO (volume ratio 10:3) to prepare a solution with a concentration of 1.05 M. After filtering the solution using a PTFE filter, 190 μL was applied and spin-coated (slope 1 second, 1000 rpm, 10 seconds, further slope 5 seconds, 3000 rpm, 20 seconds) on the substrate on which the electron transport layer was formed, during which 300 μL of chlorobenzene was dropped. The device obtained was then heated at 150° C. for 10 minutes. Next, a solution of 72.3 mg of hole transport material Spiro-OMeTAD, 13.5 mg of [tris(2-(1H-pyrazol-1-yl)-4-tert-butylpyridine)cobalt(III)tris(bis(trifluoromethylsulfonyl)imide)] (FK209, Fujifilm Wako Pure Chemical Industries, Ltd.), 28.8 μL of 4-t-butylpyridine, and 9.1 mg of LiTFSI in 1 mL of chlorobenzene was stirred for 30 minutes, filtered with a PTFE filter, and 90 μL was spin-coated onto the perovskite layer (4000 rpm with a slope of 4 seconds, 30 seconds, then stopped at a slope of 4 seconds), and then heated and dried at 70° C. for 30 minutes. Finally, 80 nm of gold was formed by vacuum deposition to obtain a perovskite solar cell element.

1.0 g of hydrotalcite and Epoch epoxy resin (E-01-001 base: 4.0 g, hardener: 2.0 g) were mixed as an adhesive and applied to the perovskite solar cell element by spin coating (1000 rpm, 120 seconds), and unnecessary parts were removed with acetone. Next, an aluminum oxide vapor-deposited PET film (product name: Barialox, Toray Industries, Inc.) cut to a size larger than the area to which the adhesive was applied was attached, and heated at 80°C for 1 hour.

The outer periphery of the film cut out to a larger size was folded along the support to produce a solar cell device as shown in Fig. 6A. At this time, d1 was 2.0 mm and d2 was 1.2 mm. The film was folded in the order shown in Fig. 8(a), and the overlapping portion was placed on a hot plate and heated at 80°C for 1 hour.
The solar cell characteristics of this solar cell device were measured using a solar simulator (Bunkoukeiki Co., Ltd. SM-250PV, light intensity: 100 mW/cm ² ), and the results were an open circuit voltage of 1.08 V, a short circuit current density of 22.0 mA/cm ² , a form factor of 0.74, and a conversion efficiency of 17.6%.
Next, the solar cell device was placed in a thermo-hygroscopic test chamber at 60° C. and 90% RH to carry out a durability test. After 500 hours, the retention rate of the initial characteristics was 93%.
[Experimental Example 1]

A solar cell device was fabricated in the same manner as in Example 1, except that the outer periphery of the film in Example 1 was not folded, and the solar cell characteristics were evaluated. As a result, the open circuit voltage was 1.10 V, the short circuit current density was 22.0 mA/ ^cm2 , the form factor was 0.72, and the conversion efficiency was 17.4%, and performance equivalent to that of Example 1 was confirmed. Next, a durability test was conducted in a constant temperature and humidity chamber in the same manner as in Example 1, and the retention rate after 500 hours was measured, resulting in 42%, which clearly demonstrated that the device structure of the present invention has excellent durability.

An adhesive layer (first layer) of the same size as the portion on which the perovskite solar cell element in Example 1 was formed was then formed on top of it with a sealant layer (first layer), and the entire top of that was again covered with the same adhesive to form an adhesive layer (second layer), and the top of that was then covered with the same sealant layer as the first layer (second layer).
The outer periphery of this second layer was subjected to thermocompression bonding in the same manner as in Example 1 to produce a solar cell device as shown in Fig. 3. As a result, d1 was 1.8 mm and d2 was 0.4 mm.
When the solar cell characteristics of this device were measured, an open circuit voltage of 1.08 V, a short circuit current density of 22.1 mA/ ^cm2 , a form factor of 0.72, and a conversion efficiency of 17.2% were obtained. Next, a durability test was conducted in a constant temperature and humidity chamber in the same manner as in Example 1, and the retention rate after 500 hours was measured, resulting in 92%, demonstrating that the device structure of the present invention has excellent durability.

On the perovskite solar cell element in Example 1, an adhesive layer (first layer) of the same size as the portion where the element was formed was formed, and a sealant layer (first layer) was formed on top of that, and an adhesive layer (second layer) was formed so as to cover the entire top of that again with the same adhesive, and the top of that was further covered with a sealant layer the same as the first layer (second layer).
The outer periphery of this second layer film was subjected to thermocompression bonding in the same manner as in Example 1 to produce a solar cell device as shown in Fig. 4. As a result, d1 was 4.1 mm and d2 was 0.9 mm.
When the solar cell characteristics of this device were measured, an open circuit voltage of 1.11 V, a short circuit current density of 22.2 mA/ ^cm2 , a form factor of 0.72, and a conversion efficiency of 17.7% were obtained. Next, a durability test was conducted in a constant temperature and humidity chamber in the same manner as in Example 1, and the retention rate after 500 hours was measured, resulting in 95%, demonstrating that the device structure of the present invention has excellent durability.
[Experimental Example 2]

A solar cell device was fabricated in the same manner as in Example 2, except that pressure was not applied to the outer periphery of the film in Example 2, and the solar cell characteristics were evaluated. As a result, the open circuit voltage was 1.09 V, the short circuit current density was 22.0 mA/ ^cm2 , the form factor was 0.72, and the conversion efficiency was 17.3%, and performance equivalent to that of Example 2 was confirmed. Next, a durability test was conducted in a constant temperature and humidity chamber in the same manner as in Example 1, and the retention rate after 500 hours was measured, resulting in 51%, and it was clear that the device structure of the present invention has excellent durability.
[Experimental Example 3]

A solar cell device was fabricated in the same manner as in Example 3, except that the outer periphery of the film in Example 3 was not pressurized, and the solar cell characteristics were evaluated. As a result, the open circuit voltage was 1.10 V, the short circuit current density was 22.0 mA/ ^cm2 , the form factor was 0.71, and the conversion efficiency was 17.2%, and performance equivalent to that of Example 3 was confirmed. Next, a durability test was conducted in a constant temperature and humidity chamber in the same manner as in Example 1, and the retention rate after 500 hours was measured, resulting in 48%, which clearly demonstrated that the device structure of the present invention has excellent durability.

Claims (5)

A support (11) having a first surface and a second surface;
A solar cell element (4) provided on the first surface of the support (11);
An adhesive layer (13) that covers the entire solar cell element (4);
A sealant layer (14) that covers the entire adhesive layer (13);
Including,
The solar cell element (4) is
An electrode (40);
A photoelectric conversion layer (47) containing a perovskite compound;
a back electrode (49), in that order;
The sealant layer (14) is
A main body portion (12) that covers the adhesive layer (13) portion on the solar cell element (4);
a first end region (15) that is continuous with the main body portion (12) and extends to an end of the first surface;
and a second end region (17) that is continuous with the first end region (15) and extends to the second surface.
A solar cell (1) , comprising:
The sealant layer (14) is
A first partial sealant layer (14a) including the main body portion (12);
a second partial sealant layer (14b) covering an end portion of the first partial sealant layer (14a) and constituting an area including the second end area (17);
Solar cell . The solar cell according to claim 1 ,
If the distance from the end of the adhesive layer (13) to the end of the support (11) is d ₁ ,
A solar cell, wherein d ₁ is 0.5 mm or more and 2 cm or less. The solar cell according to claim 1 ,
If the distance from the end of the support (11) to the point where the end of the second end region (17) exists is _d2 ,
A solar cell, wherein _d2 is 0.2 mm or more and 1 cm or less. The solar cell according to claim 1 ,
The distance from the end of the adhesive layer (13) to the end of the support (11) is d ₁ ,
If the distance from the end of the support (11) to the point where the end of the second end region (17) exists is _d2 ,
A solar cell, wherein d ₁ /d ₂ is 0.5 or more and 10 or less. The solar cell according to claim 1 ,
The sealant layer (14) is a layer constituted by one sealant film.
Solar cell.

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