Perovskite solar cell and its manufacturing method

Abstract

To provide an easy-to-manufacture perovskite solar cell and a perovskite solar cell that is less susceptible to the layers below.SOLUTION: A method for manufacturing a solar cell having a first flexible substrate 3, a first electrode 5, a photoelectric conversion layer 7, 9, 11 having a perovskite layer, a second electrode 13, and a second flexible substrate 15 in this order, includes the steps of preparing a first film including the first flexible substrate 3 and the first electrode 5 and a second film including the second electrode 13 and the second flexible substrate 15, and pasting the first and second films together.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a perovskite solar cell and a method for manufacturing the same. [Background technology]

[0002] JP 2019-55916 A describes a perovskite solar cell and a manufacturing method thereof. A perovskite solar cell has a layered structure including a surface substrate, a surface electrode, a perovskite layer, a back electrode, and a back electrode. The manufacturing method involves forming each layer in order. However, forming layers in order to obtain a layered structure has problems such as the upper layer being easily affected by the lower layer, and the time-consuming patterning and etching of each layer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-55916 Summary of the Invention [Problem to be solved by the invention]

[0004] One of the objects of the present invention is to provide a perovskite solar cell that is easy to manufacture and that is less affected by the layers below. [Means for solving the problem]

[0005] The above problem can basically be solved by preparing two films and combining them to create a solar cell. [Effects of the Invention]

[0006] According to the present invention, it is possible to provide a perovskite solar cell that not only has good initial characteristics but also has high durability. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a conceptual diagram showing the basic configuration of a solar cell. [Figure 2] FIG. 2 is a flowchart illustrating an example of a method for manufacturing a solar cell. [Figure 3] FIG. 3 is a conceptual diagram showing the first film and the second film. [Figure 4] FIG. 4 is a conceptual diagram showing a first film having a first connection electrode and a second film having a second connection electrode. [Figure 5] FIG. 5 is a conceptual diagram showing a second film having a second connection electrode. [Figure 6] FIG. 6 is a flowchart showing the process in which the hole transport layer and the electron transport layer are formed in the reverse order from that shown in FIG. [Figure 7] FIG. 7 is a flow chart showing an example of manufacturing a solar cell using a first film having a hole transport layer and a second film having an electron transport layer and a perovskite layer. [Figure 8] FIG. 8 is a conceptual diagram showing the first film and the second film obtained according to the flowchart of FIG. [Figure 9] FIG. 9 is a conceptual diagram showing a first film and a second film each having a perovskite precursor layer. [Figure 10] FIG. 10 is a conceptual diagram showing a first film and a second film each having a perovskite layer. DETAILED DESCRIPTION OF THE INVENTION

[0008] The following describes embodiments of the present invention with reference to the drawings. The present invention is not limited to the embodiments described below, and includes appropriate modifications of the embodiments below within the scope obvious to those skilled in the art.

[0009] About solar cells The first invention relates to a solar cell. Figure 1 is a conceptual diagram showing the basic configuration of a solar cell. As shown in Figure 1, this solar cell 1 has, in this order, a first flexible substrate 3, a first electrode 5, photoelectric conversion layers 7, 9, and 11 having a perovskite layer, a second electrode 13, and a second flexible substrate 15. The photoelectric conversion layers 7, 9, and 11 may each have a hole transport layer 7, a perovskite layer 9, and an electron transport layer 11.

[0010] flexible substrate3,15 As the flexible substrate 3, 15, a known substrate used in organic solar cells, organic EL elements, etc. can be used as appropriate. Specific examples of substrates include glass, ceramics, and resin films. Specific examples of resin films include ionomer films, polyethylene films, polyethylene terephthalate films, polyethylene naphthalate films, polyvinyl chloride films, polyvinylidene chloride films, polyvinyl alcohol films, polypropylene films, polyester films, polycarbonate films, polystyrene films, polyacrylonitrile films, ethylene-vinyl acetate copolymer films, ethylene-vinyl alcohol copolymer films, ethylene-methacrylic acid copolymer films, and nylon films. These films may be formed singly or as a mixture of two or more types. These films may also be laminated. Substrates having at least one type of film, selected from metal films, semiconductor films, conductive films, and insulating films, formed on part or all of their surfaces can also be used.

[0011] Examples of metals include one or more metals selected from gallium, iron, indium, aluminum, vanadium, titanium, chromium, rhodium, nickel, cobalt, zinc, magnesium, calcium, silicon, yttrium, strontium, and barium. Examples of materials constituting the semiconductor film include simple elements such as silicon and germanium, compounds containing elements from Groups 3 to 5 and Groups 13 to 15 of the periodic table, metal oxides, metal sulfides, metal selenides, and metal nitrides, which may be contained alone or in combination with two or more of these. Examples of materials constituting the conductive film include tin-doped indium oxide (ITO), fluorine-doped indium oxide (FTO), zinc oxide (ZnO), aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO), tin oxide (SnO2), titanium oxide (TiO2), indium oxide (In2O3), and tungsten oxide (WO3), which may be contained alone or in combination with two or more of these. Examples of materials constituting the insulating film include aluminum oxide (Al2O3), silicon oxide (SiO2), silicon nitride (Si3N4), and silicon oxynitride (Si4O5N3).

[0012] Examples of the shape of the substrate include a plate-like shape such as a flat plate or a disk, a fiber-like shape, a rod-like shape, a column-like shape, a rectangular column-like shape, a cylindrical shape, a spiral shape, a spherical shape, a ring-like shape, and a porous structure. Of these, a plate-like substrate is preferred. For example, the thickness of the substrate is preferably 0.1 μm to 100 mm, and more preferably 1 μm to 10 mm.

[0013] First electrode 5, second electrode 13 The electrodes are layers that support the electron transport layer and have the function of extracting electrons from the perovskite layer (light absorption layer). The electrodes are formed on the substrate 3 and include a first electrode 5a and a second electrode 5b that are spaced apart. Spaced apart means that they are not in physical contact and that the first electrode 5a and the second electrode 5b are not short-circuited. The electrodes are preferably transparent electrodes or metal electrodes.

[0014] Examples of transparent electrodes include carbon, metals, and conductive metal oxides. Examples of carbon include carbon black, carbon nanotubes, and graphene, while examples of metals include gold, silver, copper, aluminum, nickel, indium, and titanium. Examples of oxide semiconductors include tin-doped indium oxide (ITO) films, impurity-doped indium oxide (In2O3) films, impurity-doped zinc oxide (ZnO) films, and fluorine-doped tin dioxide (FTO) films, as well as laminated films formed by laminating these. A metal electrode refers to an electrode containing a metal. Examples of metal electrodes include gold, silver, and copper. A metal electrode may not only be a metal, but may also have a tin-doped indium oxide (ITO) film, impurity-doped indium oxide (In2O3) film, impurity-doped zinc oxide (ZnO) film, or fluorine-doped tin dioxide (FTO) film, or a laminated film formed by laminating these on the surface of the metal. These films may function, for example, as a diffusion barrier layer. There are no particular restrictions on the thickness of these electrodes, and it is usually preferable to adjust the thickness so that the sheet resistance is 5 to 15 Ω / □ (per unit area). The electrodes can be obtained by known film formation methods depending on the material to be formed.

[0015] The first electrode may also have a structure that allows light to pass through, such as a mesh or stripe. Furthermore, a metal lead wire may be used in combination with the first electrode to reduce electrical resistance. Examples of metal lead wires include aluminum, silver, gold, and titanium.

[0016] Electron transport layer 11 The electron transport layer 11 is formed to increase the active surface area of ​​the perovskite layer (light absorption layer), improve photoelectric conversion efficiency, and facilitate electron collection. The electron transport layer may be a flat layer made of an organic semiconductor material such as a fullerene derivative. The electron transport layer may also be a layer containing a metal oxide such as titanium oxide (TiO2) (including mesoporous TiO2), tin oxide (SnO2), or zinc oxide (ZnO). The thickness of the electron transport layer is not particularly limited, and is preferably approximately 10 to 300 nm, more preferably approximately 10 to 250 nm, from the viewpoint of efficiently collecting electrons from the perovskite layer (light absorption layer). The electron transport layer 11 may contain or be made of an n-type metal oxide semiconductor. In particular, when a solar cell is manufactured by bonding a first film and a second film as in the present invention, the electron transport layer 11 preferably contains an n-type metal oxide semiconductor.

[0017] Hole transport layer 7 The hole transport layer 7 is a layer having the function of transporting charges. The hole transport layer 7 is a layer formed on the perovskite layer 9. For example, a conductor, a semiconductor, an organic hole transport material, etc. can be used for the hole transport layer. This material can function as a hole transport material that receives holes from the perovskite layer (light absorption layer) and transports the holes. The hole transport layer is formed on the perovskite layer (light absorption layer). Examples of the conductor and semiconductor include compound semiconductors containing monovalent copper, such as CuI, CuSCN, CuInSe2, and CuS; and compounds containing metals other than copper, such as GaP, NiO, CoO, FeO, Bi2O3, MoO2, and Cr2O3. Among these, semiconductors containing monovalent copper are preferred, and CuI and CuSCN are more preferred, from the viewpoint of more efficiently receiving only holes and achieving higher hole mobility. 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; and polyaniline derivatives. Among these, triphenylamine derivatives and fluorene derivatives are preferred, with PTAA and Spiro-OMeTAD being more preferred, from the viewpoint of more efficiently receiving only holes and achieving higher hole mobility. However, when a solar cell is manufactured by bonding a first film and a second film, as in the present invention, the hole transport layer preferably contains a polythiophene derivative.

[0018] 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], or 4-isopropyl-4'-methyldiphenyliodonium tetrakis(pentafluorophenyl)borate. The hole transport layer may also contain a basic compound such as t-butylpyridine (TBP), 2-picoline, or 2,6-lutidine. The contents of the oxidizing agent and basic compound may be the amounts conventionally used. The thickness of the hole transport layer is preferably, for example, 10 to 1000 nm, more preferably 100 to 500 nm, from the viewpoint of more efficiently receiving only holes and obtaining higher hole mobility.

[0019] Perovskite layer 9 The perovskite layer (light absorption layer: photoactive layer) 9 in the perovskite solar cell is a layer that absorbs light and transfers excited electrons and holes, thereby performing photoelectric conversion. The perovskite layer uses a compound represented by the general formula (ABX3), which may be a perovskite crystal or a perovskite complex. Examples of A include organic amino compounds such as methylamine, ethylamine, n-butylamine, di-n-butylamine, di-n-hexylamine, trimethylamine, triethylamine, methyl-n-hexylamine, methyldiethylamine, tri-n-hexylamine, tri-t-butylamine, imidazole, pyrrole, aziridine, carbazole, formamidine, guanidine, aniline, pyridine, 4-t-butylpyridine, phenethylamine, and 5-aminovaleric acid, and monovalent cations formed from cesium, potassium, rubidium, etc., and A may be used alone or as a mixture of two or more types. B may be a divalent cation such as lead or tin, which may be used alone or in combination. A small amount of a trivalent cation such as indium or antimony may also be mixed. X may be a halogen atom such as chlorine, bromine or iodine, or an anion source, and may be used alone or in combination of two or more.

[0020] The perovskite layer (light absorbing layer) contains a perovskite material or a perovskite complex. From the viewpoint of the balance between light absorption efficiency and the diffusion length of electrons and holes, and the absorption efficiency of light reflected by the electrode, the thickness of the perovskite layer (light absorbing layer) is preferably, for example, 50 to 1000 nm, and more preferably 200 to 800 nm. The thickness of the perovskite layer (light absorbing layer) of the present invention may be measured using a cross-sectional scanning electron microscope (cross-sectional SEM). Furthermore, the flatness of the perovskite layer (light absorption layer) of the present invention is preferably such that the difference in height within a horizontal area of ​​500 nm x 500 nm on the surface as measured by a scanning electron microscope is 50 nm or less (-25 nm to +25 nm), and more preferably 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.

[0021] The photoelectric conversion layers 7, 9, and 11 may have, in this order, a hole transport layer 7, a perovskite layer 9, and an electron transport layer 11. In this case, the electron transport layer 11 or the second electrode 13 preferably contains a conductive polymer containing poly-3,4-ethylenedioxythiophene:poly-4-styrenesulfonate.

[0022] Alternatively, the photoelectric conversion layers 7, 9, and 11 may have, in this order, an electron transport layer 11, a perovskite layer 9, and a hole transport layer 7. In this case, the electron transport layer 11 preferably contains SnO2 or TiO2.

[0023] FIG. 2 is a flowchart illustrating an example of a method for manufacturing a solar cell. As shown in FIG. 2, this method includes the step of preparing a first film 21 including a first flexible substrate 3 and a first electrode 5. In parallel with this, the method includes the step of preparing a second film 23 including a second electrode 13 and a second flexible substrate 15. The step of forming electrodes on a flexible substrate is publicly known. Either or both of the first film 21 and the second film 23 may further have photoelectric conversion layers 7, 9, 11 and connecting electrodes 25, 27. Methods for providing these are also publicly known. Electrodes may be formed on the flexible substrate by sputtering. Electrodes may also be formed on the flexible substrate using a conductive paste.

[0024] Connection electrodes 25, 27 The connection electrode is an electrode for establishing electrical continuity between the first electrode 5 and the second electrode 13 .

[0025] An example of the process for preparing a first film 21 including a first flexible substrate 3 and a first electrode 5 is shown in steps 201 to 202 in FIG. 2. A substrate with a rear surface pattern electrode is prepared (S201). The electrode may be used as a connection electrode. Next, a connection electrode is formed in contact with the rear surface pattern electrode (S202). The second film 21 obtained in this manner is as shown in FIG. 3. FIG. 3 is a conceptual diagram showing the first film and the second film. Methods for forming electrodes on a flexible substrate and forming a photoelectric conversion layer on the electrodes are well known.

[0026] A process of preparing a substrate with a rear pattern electrode (S201) An electrode is formed on a substrate. The electrode may include a first electrode and a second electrode that are spaced apart. Methods for forming electrodes on a substrate are known. Examples of known methods include etching using a resist pattern and patterning using a laser.

[0027] A step (S202) of forming a connection electrode in contact with the rear surface pattern electrode. The connection electrodes can be formed by screen printing, for example, or by evaporating metal using a mask.

[0028] An example of the process for preparing a second film 23 including a second electrode 13 and a second flexible substrate 15 is shown in steps 101 to 105 in FIG. 2. A substrate with a surface patterned electrode is prepared (S101). Next, an electron transport layer is formed (S102). Next, a perovskite layer is formed (S103). Next, a hole transport layer is formed (S104). After that, the photoactive layer (photoelectric conversion layer) is patterned. The second film 23 obtained in this manner is as shown in FIG. 3.

[0029] A step of preparing a substrate with a surface pattern electrode (S101) An electrode is formed on a substrate. The electrode may include a first electrode and a second electrode that are spaced apart. Methods for forming electrodes on a substrate are known. Examples of known methods include etching using a resist pattern and patterning using a laser.

[0030] Step of forming an electron transport layer (S102) The electron transport layer can be obtained using a known film-forming method suited to the material to be formed. For example, it can be produced by applying a 3 to 15 mass % (particularly 5 to 10 mass %) aqueous dispersion of tin oxide microparticles onto the electrode. Known or commercially available tin oxide microparticle aqueous dispersions can be used. The preferred application method is spin coating. The application can be carried out at, for example, about 15 to 30°C. After the electrode and electron transport layer are formed on the substrate, etching using a resist pattern or patterning using a laser may be performed.

[0031] Step of forming a perovskite layer (S103) An example of a process for forming a perovskite layer includes, in this order, a process of applying a solution containing a perovskite compound to a substrate, a process of applying a poor solvent to the substrate, and a process of annealing the substrate. Spin coating, dip coating, screen printing, roll coating, die coating, transfer printing, spraying, or slit coating may be used to apply the solution to the substrate. Among these, spin coating is preferred. Spin coating is a method in which the solution is applied to the substrate by rotating the substrate while dripping the solution. Alternatively, the substrate carrying the solution may be rotated, and the solution may be further applied to the substrate. The rotation speed may be set to a maximum speed of 1,000 to 10,000 rpm for 30 seconds to 5 minutes, 2 to 15 seconds to reach the maximum speed, and 2 to 15 seconds to stop from the maximum speed.

[0032] Next, the step of applying a poor solvent to the substrate will be described. A poor solvent is a solvent that can dissolve a solute but does not have a high solubility for the solute. Examples of poor solvents include substituted aliphatic hydrocarbons such as dichloromethane and chloroform; aromatic hydrocarbons such as toluene and benzene; substituted aromatic hydrocarbons such as chlorobenzene, orthodichlorobenzene, and nitrobenzene; ethers such as acetic acid, diethyl ether, and tetrahydrofuran (THF); alcohols such as methanol, ethanol, isopropanol, butanol, and octanol; long-chain hydrocarbons (especially C4-10 hydrocarbons) such as hexane; and acetonitrile. These poor solvents can be used alone or in combination. Among these, chlorobenzene or toluene is preferred.

[0033] Next, the process of annealing the substrate will be described. Annealing refers to a process of heating the substrate, etc. The annealing process is preferably carried out promptly after the poor solvent has been dripped or after the substrate has stopped moving after spin coating has finished. As will be shown in the examples described later, the annealing process preferably includes a step of gradually heating the substrate in a closed system containing solvent vapor. In the closed system, it is preferable that vapor of the solvent contained in the solution containing the Sn-based perovskite compound is present, and it is preferable that the solvent in the closed system is at saturated vapor pressure or a partial pressure of 90% or more of the saturated vapor pressure.

[0034] Step of forming a hole transport layer (S104) The hole transport layer can be formed by any known method. For example, a solution containing an organic hole transport material is preferably applied (by spin coating, inkjet, die coater, etc.) to the perovskite layer (light absorption layer) in a dry atmosphere, and then heated at 30 to 150°C (particularly 50 to 100°C) to form the hole transport layer 11. The element material 21 can be obtained by forming the hole transport layer.

[0035] Thereafter, the first film 21 and the second film 23 are bonded together (S301). This makes it possible to obtain the solar cell shown in Fig. 1. The first film 21 and the second film 23 may be laminated together by applying pressure to them. Heat may be applied during this process.

[0036] The first film 21 may further include photoelectric conversion layers 7, 9, and 11. That is, the first film 25 may include the photoelectric conversion layers 7, 9, and 11 in addition to the second electrode 13 and the second flexible substrate 15.

[0037] Figure 4 is a conceptual diagram showing a first film having a first connection electrode and a second film having a second connection electrode. A solar cell is obtained by bonding the two films shown in Figure 4 together. Conduction is established between the first electrode 5 and the second electrode 13 of this solar cell via the first connection electrode portion 25 and the second connection electrode portion 27. In this way, the two films may each have a connection electrode.

[0038] Fig. 5 is a conceptual diagram showing a second film having a second connection electrode. A solar cell is obtained by bonding the two films shown in Fig. 5 together. Conduction is established between the first electrode 5 and the second electrode 13 of this solar cell via the second connection electrode portion 27. In this way, the second film 23 may be a film in which each of the two films has a connection electrode.

[0039] 6 is a flowchart showing the process in which the order of forming the hole transport layer and the electron transport layer is reversed from that of FIG. 2. In this way, the order of the hole transport layer and the electron transport layer may be reversed from that of FIG.

[0040] In the above method, the first film 21 may have a part of the photoelectric conversion layer, and the second film 23 may have the remainder of the photoelectric conversion layer. Then, after the first film 21 and the second film 23 are bonded together, the photoelectric conversion layer is completed.

[0041] FIG. 7 is a flowchart showing an example of manufacturing a solar cell using a first film having a hole transport layer and a second film having an electron transport layer and a perovskite layer. An overview of the first film and second film obtained according to the flowchart of FIG. 7 is shown in FIG. 8. FIG. 8 is a conceptual diagram showing the first film and second film obtained according to the flowchart of FIG. 7. As shown in FIG. 8, in this example, the first film 21 has a hole transport layer 7, and the second film 23 has an electron transport layer 11 and a perovskite layer 9. In this example, after the first film and the second film are bonded together, the photoelectric conversion layers 7, 9, and 11 are completed.

[0042] In the above method, the first film 21 may further have a first perovskite precursor layer 31, and the second film 23 may further have a second perovskite precursor layer 33. Fig. 9 is a conceptual diagram showing that the first film and the second film each have a perovskite precursor layer. In this case, the first perovskite precursor layer 31 and the second perovskite precursor layer 33 form the perovskite layer 9 after the first film 21 and the second film 23 are bonded together.

[0043] Perovskite precursor layer The perovskite precursor layer refers to a layer that becomes a perovskite layer by undergoing a predetermined treatment. For example, the first perovskite precursor layer 31 and the second perovskite precursor layer 33 may have a composition that contains elements that constitute a perovskite layer when their respective compositions are combined, and that forms the perovskite layer 9 when the first film 21 and the second film 23 are bonded together. Perovskite precursors are known, for example, as described in JP 2019-055916 A. The perovskite precursor layer may contain a known perovskite precursor as appropriate. For example, the complex may be a compound represented by the formula (AM n1 X m1 ) and complexes containing (1) 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)pyrimidinone (abbreviated as "DMTHP"), (2) sulfolane (tetrahydrothiophene 1,1-oxide: abbreviated as "SU"), (3) tetramethylene sulfoxide (abbreviated as "TS"), or (4) N,N-dimethylacetamide (abbreviated as "DMA") are precursors of perovskites. A is a methylammonium cation (CH3NH3 + ), formamidinium cation (NH2CHNH2 + ), or cesium cation (Cs + ) and M is Pb 2+ ,Ge 2+ , or Sn 2+ and X is F - ,Cl - ,Br - , or I - and n1 is 0.8 to 1.2, m1 is 2.8 to 3.2. When the film containing the complex is heated, the molecules (L) separate and a perovskite compound is formed. For example, the perovskite layer 9 can be obtained by heating the first film 21 and the second film 23 after they are bonded together.

[0044] In the above method, the first film 21 may further have a first perovskite layer 37, and the second film 23 may further have a second perovskite layer 39, with the first perovskite layer 37 and the second perovskite layer 39 combined to form a perovskite layer. FIG. 10 is a conceptual diagram showing a first film and a second film each having a perovskite layer. For example, a first perovskite layer is formed on the surface of the first film 21. Then, a second perovskite layer having the same composition as the first perovskite layer is formed on the surface of the second film 23. When these two films are pressed together, for example, perovskite layers having the same composition are welded together to form a single perovskite layer. In this way, the two films can be easily pressed together.

[0045] In the above method, the first electrode 5 and the second electrode 13 may be connected so as to be electrically conductive via a first connection electrode portion 25 provided on the first electrode 5 in a region between the first electrode 5 and the second electrode 13 where the photoelectric conversion layers 7, 9, 11 are not present. The first connection electrode portion 25 may have a protruding shape. If the first connection electrode portion 25 has a protruding shape, even if a thin layer is formed on the second electrode 13, it is preferable because the first connection electrode portion 25 can penetrate the thin layer and ensure electrical conductivity with the second electrode 13.

[0046] In this example, for example, a second electrode (surface electrode) 13 is provided on a second flexible substrate 15, and photoelectric conversion layers 7, 9, and 11 are provided on the surface electrode 13. However, in this example, the photoelectric conversion layers 7, 9, and 11 are not provided on the entire surface of the surface electrode 13, but there is a region on the surface of the surface electrode 13 where the photoelectric conversion layers 7, 9, and 11 are not present (this region is referred to as region A). On the other hand, a first electrode (back electrode) 5 is provided on the first flexible substrate 3. The first flexible substrate 3 and the second flexible substrate 15 have corresponding shapes and are bonded together to form a solar cell. A connection electrode portion 25 is present on the back electrode 5 in a region corresponding to region A. Then, after the first flexible substrate 3 and the second flexible substrate 15 are bonded together, the first connection electrode portion 25 comes into contact with the surface electrode 13. As a result, the first electrode 5 and the second electrode 13 are electrically connected via the first connection electrode portion 25 .

[0047] The solar cell manufactured as described above has the following configuration: In other words, this solar cell comprises, in this order, a first flexible substrate 3, a first electrode 5 which is a transparent electrode, photoelectric conversion layers 7, 9, 11 having a perovskite layer 9, a second electrode 13, and a second flexible substrate 15. The first electrode 5 and the second electrode 13 are connected so as to be conductive via a first connection electrode portion 25 provided on the first electrode 5 in a region between the first electrode 5 and the second electrode 13 where the photoelectric conversion layers 7, 9, 11 are not present.

[0048] 1, this solar cell has, for example, a region between the first flexible substrate 3 and the second flexible substrate 15 where the photoelectric conversion layers 7, 9, 11 are not present. In particular, this solar cell preferably has a region between the first flexible substrate 3 and the second flexible substrate 15 where the hole transport layer 7 and the perovskite layer 9 are not present.

[0049] As shown in Fig. 1, this solar cell is preferably one in which the hole transport layer 7 covers the perovskite layer 9. Alternatively, the hole transport layer 7 may be wider than the perovskite layer 9. When the first film 21 and the second film are bonded together, the hole transport layer 7 becomes the adhesive surface with the first electrode. By covering the perovskite layer 9 with the hole transport layer 7 that forms this adhesive surface, the hole transport layer 7 protects the perovskite layer 9 from oxygen and moisture, improving durability.

[0050] In the above method, the first electrode 5 and the second electrode 13 may be connected to each other so as to be conductive via a second connection electrode portion 27 provided on the second electrode 13 in a region (region A) between the first electrode 5 and the second electrode 13 where the photoelectric conversion layers 7, 9, and 11 are not present. In this case, the second connection electrode portion 27 may be provided in region A, and the second connection electrode portion 27 may come into contact with the first electrode (rear electrode) 5 after the first flexible substrate 3 and the second flexible substrate 15 are bonded together. On the other hand, the first connection electrode portion 25 may be present on the rear electrode 5 in a region corresponding to region A. In this case, the second connection electrode portion 27 may come into contact with the first connection electrode portion 25 after the first flexible substrate 3 and the second flexible substrate 15 are bonded together. In any case, in this way, the first electrode 5 and the second electrode 13 are electrically connected via the second connecting electrode portion 27 (or the second connecting electrode portion 27 and the first connecting electrode portion 25).

[0051] The solar cell manufactured in this manner has the following configuration: This solar cell comprises, in this order, a first flexible substrate 3, a first electrode 5 which is a transparent electrode, photoelectric conversion layers 7, 9, 11 having a perovskite layer 9, a second electrode 13, and a second flexible substrate 15. The first electrode 5 and the second electrode 13 are connected so as to be conductive via a second connection electrode portion 27 provided on the second electrode 13 in a region between the first electrode 5 and the second electrode 13 where the photoelectric conversion layers 7, 9, 11 are not present. [Example]

[0052] The solar cells were fabricated using the following equipment and tools. PTFE filter: Agilent Technologies, 5190-5266, 0.45 μm ITO / PEN film: Oike & Co., Itd., CX13G-125N-U0, 16 Ω / □ Laminator: Nishinbo Mechatronics Inc., PVL0202S reagent SnO2 aqueous dispersion: Alfer Acer, 044592 PEDOT:PSS dispersion: Heraeus, Clevios P ​​VP. Al 4083. PbI2:Tokyo Chemical Industry Co., Ltd., L0279 FAI:Tokyo Chemical Industry Co., Ltd., F1263 MABr:Tokyo Chemical Industry Co., Ltd., M2589 MACl:Tokyo Chemical Industry Co., Ltd., M0138 Super dehydrated DMF: Kanto Chemical Co., Inc., 11339-85 Ultra-dehydrated DMSO: Wako Pure Chemical Industries, Ltd., 049-07213 Ultra-dehydrated acetone: Wako Pure Chemical Industries, Ltd., 013-00356

[0053] A PEN film with ITO as a transparent electrode was plasma-treated, and water-soluble SnO2 was applied as an electron transport layer and water-soluble PEDOT:PSS as a hole transport layer. The SnO2 layer was obtained by dropping 300 μL of a 15% SnO2 aqueous dispersion diluted 1:1 with pure water onto the substrate, spin-coating (ramp 2 s, 3000 rpm for 20 s), and heating at 150 °C for 30 min. The PEDOT:PSS layer was also obtained by dropping 300 μL of the PEDOT:PSS dispersion onto the substrate and spin-coating (ramp 1 s, 500 rpm for 9 s, ramp 1 s, 4000 rpm for 30 s), followed by heating at 140 °C for 30 min. The SnO2 and PEDOT:PSS films were deposited under atmospheric pressure. All subsequent processes were carried out in a glove box (N2 gas, H2O < 0.1 ppm, O2<0.1 ppm).

[0054] PbI2 (1798 mg, 3.9 mmol) was dissolved in an ultra-dehydrated DMF / DMSO mixture (2.85 mL / 0.15 mL) in a glove box. The mixture was stirred at 70 °C for 30 min and filtered through a PTFE filter to prepare a 1.3 M PbI2 solution. The PbI2 solution (200 μL) was spin-coated onto a substrate coated with SnO2 and PEDOT:PSS (ramp 2 s, 1500 rpm for 30 s), followed by heating at 70 °C for 1 min to obtain a PbI2 layer. Parts of the SnO2, PEDOT:PSS, and PbI2 layers were removed using an acetone:DMSO (10:1) solution, and Cu tape was attached as an extraction electrode.

[0055] The film substrate and sealant used for immobilization were larger than the substrate coated with SnO2 and PEDOT:PSS. The sealant was placed on the film substrate and heated at 120 °C for 10 minutes, after which the substrate coated with SnO2 and PEDOT:PSS was placed on top and fixed.

[0056] FAI (60 mg, 0.35 mmol), MABr (6.0 mg, 0.05 mmol), and MACl (6.0 mg, 0.09 mmol) were dissolved in ultra-dehydrated i-PrOH (10 mL). The mixture was stirred at 40 °C for 30 min and filtered through a PTFE filter to prepare an organic cation solution. 50 μL of the organic cation solution was dropped onto each substrate, and the substrates were quickly stacked. The substrates were transferred to a laminator set at 150 °C and pressed under reduced pressure for 10 min to form a perovskite layer. Bonded solar cells were fabricated using this process. Measurement of the cross-sectional area of ​​the resulting solar cell revealed that the PEDOT:PSS layer had a larger area than the perovskite layer. This is presumably due to the expansion of the soft PEDOT:PSS film caused by the pressure during bonding.

[0057] The solar cell characteristics were evaluated under 1 sun in air. When light was incident from the SnO2 layer side, the open circuit voltage was 0.70 V and the short circuit current density was 17.8 mA / cm. 2 The fill factor was 0.64 and the conversion efficiency was 8.0%. When light was incident from the PEDOT:PSS layer side, the open-circuit voltage was 0.58 V and the short-circuit current density was 15.4 mA / cm. 2 The shape factor was 0.61 and the conversion efficiency was 5.45%.

[0058] Furthermore, the solar cell characteristics were evaluated after 100 hours of continuous irradiation at the above 1 Sun light durability test. The results showed that when light was incident from the SnO2 layer side, the open circuit voltage was 0.67 V, the short circuit current density was 16.1 mA / cm2, the fill factor was 0.63, and the conversion efficiency was 6.8%, which was significantly higher than the characteristics before the durability test. The retention rate was 85%.

[0059] [Comparative Example 1] A device was fabricated using the same process as in Example 1 up to the formation of the perovskite layer, and a PEDOT:PSS layer was formed on top of it. The electrode thus obtained and an ITO / PEN film were attached in the same manner as in Example 1 to fabricate a cell. The solar cell characteristics of this cell were measured under atmospheric conditions at 1 sun. When light was incident from the SnO2 layer side, the open-circuit voltage was 0.41 V and the short-circuit current density was 10.3 mA / cm. 2 The form factor was 0.33 and the conversion efficiency was 1.4%. When light was incident from the PEDOT:PSS layer side, the open-circuit voltage was 0.33 V and the short-circuit current density was 7.6 mA / cm. 2 The form factor was 0.33 and the conversion efficiency was 0.8%. Compared to Example 1, it is clear that the solar cell performance is inferior.

[0060] Furthermore, the solar cell characteristics were evaluated after 100 hours of continuous irradiation at 1 Sun as the light durability. As a result, the characteristics when light was incident from the SnO2 layer side were an open circuit voltage of 0.16 V and a short circuit current density of 6.8 mA / cm. 2 The form factor was 0.31 and the conversion efficiency was 0.3%, which was compared with the characteristics before the durability test. The retention rate was 37.5%, which is clearly lower than that in Example 1.

[0061] As is clear from the above, it is clear that the solar cell of the present invention not only exhibits high initial characteristics but also has high light durability. [Example]

[0062] A 50 μm thick PET film is used for the first and second flexible substrates, and a 150 nm thick ITO film is first deposited on the electrodes on top of it to form a pattern. To facilitate subsequent processes, the flexible substrate is sometimes attached to a glass substrate. First, a water-soluble SnO2 solvent is spin-coated onto the first flexible substrate, and then dried by heating at about 150°C. On top of that, a perovskite solution is spin-coated, dried, and then a hole layer is spin-coated and dried again. For the hole layer, a solution of Spiro-MeOTAD and LiTFSi dissolved in chlorobenzene is used. If necessary, parts of the hole layer and perovskite layer are removed. This was done using laser processing, but another method is reactive ion etching (RIE) using a metal mask.

[0063] On the other hand, silver paste was printed by screen printing in the desired locations on the second flexible substrate for electrical connection between the first and second substrates. The concentration and thickness were adjusted so that the finished thickness would be about 5 to 20 μm. To bond the films together, align the two films and apply pressure with a roller. The pressure applied depends on the size of the roller, but we applied a pressure of about 0.1 kg / cm. When bonding the films together, spraying chlorobenzene onto the second flexible substrate before bonding them together softens the surface of the hole layer slightly, which allowed for more effective bonding. Furthermore, heating the roller to a constant temperature of about 70°C allowed for more effective bonding.

[0064] The film is not limited to PET, but can be any flexible film. It is also preferable to use a flexible film with a barrier layer formed in advance to prevent moisture permeation. In addition to silver paste, other connection materials include carbon paste, copper paste, nickel paste, and carbon nanotubes. [Example]

[0065] A 50 μm thick PET film is used for the first and second flexible substrates, and a 150 nm thick ITO film is formed on the electrodes on top of it in advance to form a pattern (similar to Example 2).The flexible substrate may be attached to a glass substrate to make subsequent processes easier. First, a water-soluble SnO2 solvent is spin-coated onto the first flexible substrate, and then dried by heating at about 150°C. Then, a perovskite solution is spin-coated on top of that and dried. If necessary, parts of the hole layer and perovskite layer are removed. Methods for removal include laser processing and reactive ion etching (RIE) using a metal mask.

[0066] On the other hand, silver paste is printed in the desired locations on the second flexible substrate using screen printing or similar methods to electrically connect the first and second substrates. The finished thickness is adjusted to about 5 to 20 μm. After that, the hole layer is applied in the desired pattern using the inkjet method. Because of the unevenness caused by the electrical connection material, application using the spin coating method is not necessarily suitable.

[0067] To bond the films together, it is advisable to align the positions of both films beforehand and apply pressure with a roller. The pressure applied depends on the roller size, but we applied a pressure of about 0.1 kg / cm. When bonding the films together, spraying chlorobenzene onto the first flexible substrate before bonding them together in order to soften the surface of the hole layer allowed for more effective bonding. Furthermore, heating the roller to a constant temperature of about 70°C allowed for more effective bonding. (The materials used were the same as in Example 2.)

[0068] In the above examples, spin coating was mainly used for application, but each layer may also be formed by an inkjet method. In this case, connection electrodes are also formed on the first flexible substrate in advance, making it possible to easily and stably reduce the resistance of the connection electrodes. The connection electrodes formed on the first flexible substrate may be formed by depositing a metal thin film of a single metal such as Pt, Au, Cu, Ag, Ni, or Ti, or an alloy of these metals, on ITO by vapor deposition or the like, or by using a metal paste of these metals. [Example]

[0069] For example, a 50 μm thick PET film is used for the first and second flexible substrates, and a 150 nm thick ITO film is first deposited on the electrodes on top of it to form a pattern. To facilitate subsequent processes, the flexible substrate may be attached to a glass substrate. After SnO2 was applied by spin coating onto the ITO on the first flexible substrate, a metal mask was set and a film was formed by sputtering to attach connecting Cu / Pt to a portion of it. A perovskite layer and a hole layer were then applied on top of that in the same manner as in Example 2. When forming connecting electrodes with a thin film, spin coating does not result in significant unevenness in the coating thickness, but when forming by screen printing, the unevenness in the film thickness becomes significant due to the large step differences. In that case, the occurrence of unevenness in film thickness can be suppressed by applying the coating using the inkjet method. On the other hand, the process of the second flexible substrate and the bonding can be the same as in Example 2. [Industrial Applicability]

[0070] This invention can be used in fields such as solar cells. [Explanation of symbols]

[0071] 1. Solar cells 3. First flexible substrate 5 First electrode 7 Electron transport layer 9 Perovskite Layer 11 Hole transport layer 13 Second electrode 15 Second flexible substrate 21 First Film 23 Second Film 31 First perovskite precursor layer 33 Second perovskite precursor layer 37 First perovskite layer 39 Second Perovskite Layer

Claims

1. A method for manufacturing a solar cell having, in this order, a first flexible substrate (3), a first electrode (5), a photoelectric conversion layer (7, 9, 11) having a perovskite layer, a second electrode (13), and a second flexible substrate (15), comprising: A first film (21) including a first flexible substrate (3) and a first electrode (5); Providing a second film (23) including a second electrode (13) and a second flexible substrate (15); A method for manufacturing a solar cell, comprising a step of bonding a first film (21) and a second film (23), The first film (21) has a first connection electrode portion (25) having a protruding shape provided on the first electrode (5), The first electrode (5) and the second electrode (13) are In a region between the first electrode (5) and the second electrode (13) where the photoelectric conversion layer (7, 9, 11) is not present, It is connected so as to be electrically conductive via the first connection electrode portion (25), The second electrode (13) has a first portion and a second portion adjacent to each other across a region where the photoelectric conversion layer (7, 9, 11) is not present on the surface of the second film (23), and the surface of the first portion of the second electrode (13) facing the second portion of the second electrode (13) is covered with the perovskite layer (9). How solar cells are manufactured.

2. 2. A method for producing a solar cell according to claim 1, wherein the first film (21) further comprises a first perovskite precursor layer (31) and the second film (23) further comprises a second perovskite precursor layer (33).

3. 2. A method for producing a solar cell according to claim 1, wherein the first film (21) further comprises a first perovskite layer (37) and the second film (23) further comprises a second perovskite layer (39), the first perovskite layer (37) and the second perovskite layer (39) constituting the perovskite layer.

4. 2. A method for manufacturing a solar cell according to claim 1, further comprising the step of forming a second electrode (13) on a second flexible substrate (15) by sputtering or using a conductive paste to form a second electrode (13) on the second flexible substrate (15) to obtain a second film (23).

5. A method for producing the solar cell according to claim 1, comprising: In the step of bonding the first film (21) and the second film (23), A method for manufacturing a solar cell, in which a first connection electrode portion (25) penetrates a thin layer formed on a second electrode (13), thereby ensuring electrical continuity between a first electrode (5) and a second electrode (13).

6. A method for manufacturing a solar cell having, in this order, a first flexible substrate (3), a first electrode (5), a photoelectric conversion layer (7, 9, 11) having a perovskite layer (9), a second electrode (13), and a second flexible substrate (15), comprising: A first film (21) including a first flexible substrate (3) and a first electrode (5); Providing a second film (23) including a second electrode (13) and a second flexible substrate (15); A method for manufacturing a solar cell, comprising a step of bonding a first film (21) and a second film (23), The second film (23) has a second connection electrode portion (27) having a protruding shape provided on the second electrode (13), The first electrode (5) and the second electrode (13) are In a region between the first electrode (5) and the second electrode (13) where the photoelectric conversion layer (7, 9, 11) is not present, It is connected so as to be electrically conductive via the second connection electrode portion (27), The second electrode (13) has a first portion and a second portion adjacent to each other on the surface of the second film (23) with a region in which the photoelectric conversion layer (7, 9, 11) is not present therebetween, and the surface of the first portion facing the second portion of the second electrode (13) is covered with the perovskite layer (9). How solar cells are manufactured.

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