Method for manufacturing solar cell

Abstract

Provided is a method for manufacturing a perovskite solar cell capable of improving the power generation efficiency of a solar cell. Provided is a method for producing a solar cell having a photoelectric conversion layer containing a perovskite compound represented by ABX3 (in the formula, A represents at least one cation selected from the group consisting of Cs +, CH3NH3 +, and HC (NH2) 2 +, B represents at least one divalent cation selected from the group consisting of Pb2 + and Sn2 +, and X represents at least one anion selected from the group consisting of halide anions). The precursor solution used in the production method contains A, B, X1, and X2 at a molar ratio of 1: (1 + 0.5 a): 3: a, X1 represents at least one anion selected from halide anions, X2 represents Cl-, and a represents a real number greater than 0 but 0.21 or less.

Description

Technical Field

[0001] This invention relates to a method for manufacturing solar cells. Background Technology

[0002] As a type of solar cell, perovskite solar cells are known to have perovskite compounds as the main component of the photoelectric conversion layer.

[0003] Patent document 1 describes a method for manufacturing ABX. 3-y X' y The process of the perovskite compound shown in the formula (where A is an organic cation, B is a metal cation, X is a first halide anion, X' is a second halide anion different from the first halide anion, and y is 0.05 to 2.95) is as follows.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent No. 6263186

[0007] Perovskite solar cells are preferred for their high power generation efficiency. In view of this, this disclosure provides a method for manufacturing a perovskite solar cell that can improve the power generation efficiency of the perovskite solar cell. Summary of the Invention

[0008] The present invention includes:

[0009] [Method 1]

[0010] A method for manufacturing a solar cell, the solar cell having a photoelectric conversion layer containing a perovskite compound as shown in formula (1).

[0011] ABX3(1)

[0012] (In the formula, A represents the selection from Cs) + CH3NH3 + and HC(NH2)2 + At least one cation in, B represents a cation selected from Pb 2+ and Sn 2+ (The cation contains at least one divalent cation, where X represents at least one anion selected from halide anions.)

[0013] The manufacturing method includes:

[0014] The precursor solution is applied to the coating surface to form a coating layer, and

[0015] The photoelectric conversion layer is formed by annealing the coating.

[0016] The precursor solution contains A, B, and X in a molar ratio of 1:(1+0.5a):3:a. 1 and X 2 X 1 X represents at least one anion selected from halide anions. 2 Cl - , where a represents a real number greater than 0 and less than 0.21.

[0017] [Method 2]

[0018] According to the method described in method 1, X 1 Indicates selected from Br - and I - At least one anion in it.

[0019] [Method 3]

[0020] According to method 1 or 2, the precursor solution contains A and B in a molar ratio of 1:1:0.5a:3:a. 1 B 2 X 1 and X 2 B 1 Indicates that it is selected from Pb 2+ and Sn 2+ At least one divalent cation in, B 2 Pb 2+ .

[0021] [Method 4]

[0022] The method according to method 3 further includes: preparing the precursor solution by dissolving at least one compound of formula (2), at least one compound of formula (3a), and at least one compound of formula (4a) in a solvent.

[0023] AX 1 (2)

[0024] B 1 X 1 2 (3a)

[0025] B 2 X 2 2 (4a).

[0026] [Method 5]

[0027] According to any one of the methods 1 to 4, where a represents a real number from 0.03 to 0.16.

[0028] The manufacturing method disclosed herein can improve the power generation efficiency of perovskite solar cells. Attached Figure Description

[0029] Figure 1 This is a schematic cross-sectional view illustrating an example of the structure of a solar cell.

[0030] Figure 2 This is a schematic diagram representing the perovskite crystal structure.

[0031] Figure 3 This is a flowchart illustrating a method for manufacturing a solar cell according to an embodiment.

[0032] Figure 4 This indicates the presence of Cs in a molar ratio of 0.05:0.79:0.16:(1+0.5a):2.55:0.45:a. + HC(NH2)2 + CH3NH3 + Pb 2+ I - ,Br - and Cl - The graph shows the relationship between the normalized power generation efficiency and the a value of the solar cells of Examples 1 to 4 and Comparative Examples 1 and 2, which were prepared from the precursor solution.

[0033] Figure 5 This indicates the presence of Cs in a molar ratio of 0.17:0.83:(1+0.5a):3:a. + HC(NH2)2 + Pb 2+ I - and Cl - The graph shows the relationship between the normalized power generation efficiency and the a value of the solar cells of Example 5 and Comparative Examples 3 and 4, which were prepared from the precursor solution.

[0034] Figure 6 This is a graph showing the relationship between the ratio of the diffraction peak intensity of perovskite (100) to that of ITO (222) and the a value.

[0035] Symbol Explanation

[0036] 1:Substrate

[0037] 2a: First electrode layer

[0038] 2b: Second electrode layer

[0039] 3a: First carrier transport layer

[0040] 3b: Second carrier transport layer

[0041] 4: Photoelectric conversion layer

[0042] C: Solar cell Detailed Implementation

[0043] The embodiments will now be described with appropriate reference to the accompanying drawings. In the drawings referred to in the following description, the dimensions and shapes of the components are exaggerated for ease of explanation and may sometimes differ from the actual dimensions and shapes. In this application, the term "on" includes both "directly on" and "indirectly on" unless otherwise specified in the context. The upper and lower limits of the numerical ranges described in this application can be used individually or in any combination.

[0044] I. Solar Cells

[0045] First, a perovskite solar cell (hereinafter also referred to as "solar cell") manufactured by the manufacturing method of the embodiments described later will be explained. Figure 1 This is a schematic cross-sectional view illustrating an example of the structure of a solar cell.

[0046] like Figure 1 As shown, in one embodiment, the solar cell C sequentially comprises a substrate 1, a first electrode layer 2a, a first carrier transport layer 3a, a photoelectric conversion layer 4, a second carrier transport layer 3b, and a second electrode layer 2b.

[0047] (a) Photoelectric conversion layer 4

[0048] The photoelectric conversion layer 4 is located between the first carrier transport layer 3a and the second carrier transport layer 3b. The photoelectric conversion layer 4 generates charge carriers when receiving light. The charge carriers generated in the photoelectric conversion layer 4 move to either the first carrier transport layer 3a or the second carrier transport layer 3b.

[0049] Specifically, positive charge carriers, i.e., holes, generated in the photoelectric conversion layer 4 are transported to the first electrode layer 2a or the second electrode layer 2b via either the first charge carrier transport layer 3a or the second charge carrier transport layer 3b, which serves as the hole transport layer. Negative charge carriers, i.e., electrons, generated in the photoelectric conversion layer 4 are transported to the first electrode layer 2a or the second electrode layer 2b via either the first charge carrier transport layer 3a or the second charge carrier transport layer 3b, which serves as the electron transport layer.

[0050] The photoelectric conversion layer 4 contains a perovskite compound. The photoelectric conversion layer 4 may contain a perovskite compound as a main component. The content of the perovskite compound in the photoelectric conversion layer 4 may be 60% by weight or more, 80% by weight or more, 90% by weight or more, 95% by weight or more, or 100% by weight. The thickness of the photoelectric conversion layer 4 may be 100 nm to 1000 nm.

[0051] Generally, perovskite compounds are represented by the following formula (1).

[0052] ABX3(1)

[0053] (In the formula, A represents a monovalent cation, B represents a divalent cation, and X represents a monovalent anion.)

[0054] Perovskite compounds have a perovskite-type crystal structure. Figure 2 This is a schematic diagram representing the perovskite crystal structure. For example... Figure 2 As shown, the perovskite crystal structure has a cubic crystal system with A arranged at each vertex, B arranged at the body center, and X arranged at each face center. The perovskite crystal structure of the compound can be confirmed, for example, by X-ray diffraction (XRD) analysis.

[0055] In one embodiment, in formula (1), A represents a cesium cation (Cs). + ), Methylammonium (MA) cation (CH3NH3) + ) and formamidin (FA) cation (HC(NH2)2) + At least one cation from the group consisting of lead(II) cations (Pb). 2+ ) and tin(II) cations (Sn 2+ At least one divalent cation in the composition, preferably Pb 2+ X represents at least one anion selected from halide anions, preferably selected from fluoride anions (F... - ), chloride anion (Cl - ), bromide anion (Br) - ) and iodide anion (I - At least one anion from ), particularly representing anion selected from Cl. - ,Br - and I - At least one anion in it.

[0056] (b) First carrier transport layer 3a and second carrier transport layer 3b

[0057] The first carrier transport layer 3a receives charge carriers generated in the photoelectric conversion layer 4 and transports these charge carriers to the first electrode layer 2a. When the first carrier transport layer 3a is a hole transport layer, it transports holes to the first electrode layer 2a. When the first carrier transport layer 3a is an electron transport layer, it transports electrons to the first electrode layer 2a.

[0058] The second carrier transport layer 3b receives charge carriers generated in the photoelectric conversion layer 4 and transports these charge carriers to the second electrode layer 2b. When the second carrier transport layer 3b is a hole transport layer, it transports holes to the second electrode layer 2b. When the second carrier transport layer 3b is an electron transport layer, it transports electrons to the second electrode layer 2b.

[0059] The hole transport layer transports holes generated in the photoelectric conversion layer 4 to the first electrode layer 2a or the second electrode layer 2b via photoelectric conversion. Known organic or inorganic materials suitable for hole transport layers can be used as the material for the hole transport layer.

[0060] Examples of organic materials that can be used as hole transport layers include 2,2',7,7'-tetra-(N,N-di-4-methoxyphenylamino)-9,9'-spirodifluorene (Spiro-OMeTAD), polyethylenedioxythiophene:polystyrene sulfonic acid (PEDOT:PSS), and poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA).

[0061] Examples of inorganic materials that can be used as hole transport layers include nickel oxide and copper oxide.

[0062] The electron transport layer transports electrons generated by photoelectric conversion in the photoelectric conversion layer 4 to the first electrode layer 2a or the second electrode layer 2b. Known organic or inorganic materials suitable for electron transport layers can be used as the material for the electron transport layer.

[0063] Examples of organic materials that can be used as electron transport layers include fullerene compounds, phenanthroline derivatives (e.g., copper sulfate), and polyethyleneimines. Examples of fullerene compounds include fullerenes (e.g., C60 fullerenes, C70 fullerenes) and derivatives obtained by adding substituents to fullerenes (e.g., methyl [6,6]-phenyl-C61-butyrate (also known as PCBM or

[60] PCBM), methyl [6,6]-phenyl-C71-butyrate (also known as PCBM or

[70] PCBM)).

[0064] Examples of inorganic materials that can be used as electron transport layers include titanium oxide, tin oxide, and zinc oxide.

[0065] In one embodiment, the first carrier transport layer 3a is an electron transport layer, and the second carrier transport layer 3b is a hole transport layer. In this embodiment, the solar cell C sequentially comprises a substrate 1, a cathode, an electron transport layer, a photoelectric conversion layer 4, a hole transport layer, and an anode. In this embodiment, the hole transport layer can be made of Spiro-OMeTAD, PTAA, or nickel oxide. In this embodiment, the electron transport layer can be made of fullerene, PCBM, copper bath alloy, polyethyleneimine, titanium oxide, or tin oxide.

[0066] In another embodiment, the first carrier transport layer 3a is a hole transport layer, and the second carrier transport layer 3b is an electron transport layer. In this embodiment, the solar cell C sequentially comprises a substrate 1, an anode, a hole transport layer, a photoelectric conversion layer 4, an electron transport layer, and a cathode. In this embodiment, the material of the hole transport layer can be PEDOT:PSS, PTAA, or nickel oxide. In this embodiment, the material of the electron transport layer can be fullerene, PCBM, copper bath alloy, or polyethyleneimine.

[0067] (c) First electrode layer 2a and second electrode layer 2b

[0068] The first electrode layer 2a is an electrode that is in contact with the first carrier transport layer 3a. The second electrode layer 2b is an electrode that is in contact with the second carrier transport layer 3b.

[0069] The materials for the first electrode layer 2a and the second electrode layer 2b can be any known materials suitable for use as electrodes in the solar cell C. Examples of materials suitable for the first electrode layer 2a and the second electrode layer 2b include metallic materials such as aluminum (Al), silver (Ag), and gold (Au), transparent conductive materials such as indium tin oxide (ITO), indium zinc oxide (IZO), aluminum-doped zinc oxide (AZO), fluorine-doped tin oxide (FTO), and carbon nanotubes. The materials for the first electrode layer 2a and the second electrode layer 2b can be ITO, IZO, or FTO. When light passes through the surface of the substrate 1 and is incident on the solar cell C, the first electrode layer 2a can be transparent, and the second electrode layer 2b can be transparent or opaque. When light passes through the surface of the second electrode layer 2b and is incident on the solar cell C, the first electrode layer 2a can be transparent or opaque, and the second electrode layer 2b can be transparent.

[0070] (d) Substrate 1

[0071] The substrate 1 supports the first electrode layer 2a, the first carrier transport layer 3a, the photoelectric conversion layer 4, the second carrier transport layer 3b, and the second electrode layer 2b.

[0072] The substrate 1 can be plate-shaped or film-shaped. Examples of materials for the substrate 1 include inorganic materials such as glass, organic materials such as polyethylene, polyethylene terephthalate, polyethylene naphthalate, polyimide, polyamide, polyamide-imide, liquid crystal polymer, and cyclic olefin polymer, as well as metallic materials such as stainless steel and silicon.

[0073] The substrate 1 can be transparent or opaque. A transparent substrate is used when light passes through the surface of the substrate 1 and is incident on the solar cell C. Examples of transparent substrates include those made of glass, polyethylene terephthalate, polyethylene naphthalate, polyimide, polyamide, polyamide-imide, or cyclic olefin polymers. An opaque substrate can be used when light passes through the surface of the second electrode layer 2b and is incident on the solar cell C.

[0074] II. Manufacturing Method of Solar Cells

[0075] Next, the method for manufacturing the solar cell according to the embodiment will be described. For example... Figure 3 As shown, the method for manufacturing a solar cell according to the embodiment includes: coating a precursor solution onto a coating surface to form a coating layer (S1); and annealing the coating layer to form a photoelectric conversion layer (S2).

[0076] In one embodiment, the method for manufacturing a solar cell optionally further includes forming a laminate comprising a substrate, a first electrode layer, and a first carrier transport layer sequentially before coating the precursor solution; and optionally further includes forming a second carrier transport layer and a second electrode layer sequentially on the photoelectric conversion layer after forming the photoelectric conversion layer. In this embodiment, the precursor solution may be coated on the first carrier transport layer. The first electrode layer, the first carrier transport layer, the second carrier transport layer, and the second electrode layer can be formed using the same methods as in conventional photoelectric conversion elements. Therefore, a detailed description of the formation methods of these layers is omitted.

[0077] (a) Coating of the precursor solution (S1)

[0078] A precursor solution is coated onto a coating surface to form a coating layer. The coating surface can be the surface of the first carrier transport layer. Alternatively, if the solar cell does not have a first carrier transport layer, the coating surface can be the surface of the first electrode layer. If the solar cell has other layers between the photoelectric conversion layer and the first carrier transport layer, the coating surface can be the surface of those other layers. In other words, the coating surface is appropriately selected based on the configuration of the manufactured solar cell.

[0079] The precursor solution contains a solute that serves as a precursor to the perovskite compound represented by formula (1) above. The precursor solution contains A, B, and X in a molar ratio of 1:(1+0.5a):3:a.1 and X 2 Where A represents a selection from Cs + CH3NH3 + and HC(NH2)2 + At least one cation in, B represents a cation selected from Pb 2+ and Sn 2+ At least one divalent cation, X 1 X represents at least one anion selected from halide anions. 2 Cl - , where 'a' represents a real number greater than 0 and less than 0.21. In one implementation, X 1 Indicates selected from Br - and I - At least one anion in it. In one embodiment, B represents Pb. 2+ In one implementation, a represents a real number of 0.03–0.21, 0.03–0.16, or 0.06–0.16. Additionally, X in equation (1) comes from X... 1 or X 2 At least one of them.

[0080] In one embodiment, the precursor solution contains A and B in a molar ratio of 1:1:0.5a:3:a. 1 B 2 X 1 and X 2 Among them, B 1 Indicates that it is selected from Pb 2+ and Sn 2+ At least one divalent cation in B 2 Pb 2+ A, X 1 X 2 a is as defined above. It should be noted that in this embodiment, B in equation (1) comes from B. 1 Or B 2 At least one of them.

[0081] In one embodiment, the precursor solution can be prepared by dissolving at least one compound of formula (2), at least one compound of formula (3), and at least one compound of formula (4) in a suitable solvent.

[0082] AX 1 (2)

[0083] BX 1 2 (3)

[0084] BX 2 2(4)

[0085] (In the formula, A, B, X) 1 and X 2 As defined above.

[0086] In one embodiment, the precursor solution may be prepared, for example, by dissolving at least one compound of formula (2), at least one compound of formula (3a), and at least one compound of formula (4a) in a suitable solvent.

[0087] AX 1 (2)

[0088] B 1 X 1 2 (3a)

[0089] B 2 X 2 2(4a)

[0090] (In the formula, A and B) 1 B 2 X 1 and X 2 As defined above.

[0091] From the viewpoint of solubility of the solute, the solvent of the precursor solution can be a polar solvent. Furthermore, from the viewpoint of solute stability, the solvent of the precursor solution can be an aprotic solvent. Examples of solvents that can be used as precursor solutions include N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), γ-butyrolactone, and mixtures containing one or more of these.

[0092] The precursor solution can be coated using any coating method capable of forming a uniform coating. Examples of applicable coating methods include spin coating, inkjet coating, spray coating, doctor blade coating, and mold coating.

[0093] From the perspective of the stability of the precursor solution, the coating of the precursor solution can be carried out in a dry gas atmosphere, especially in an inert gas atmosphere. The inert gas can be any gas that does not react with the solute in the precursor solution. Examples of inert gases include nitrogen and argon.

[0094] Alternatively, a poor solvent can be applied to the coating. In a poor solvent, the solute serving as the precursor of the perovskite compound has a lower solubility than its solubility in the solvent of the precursor solution. The poor solvent can be one that substantially does not dissolve the precursor of the perovskite compound. The solubility of the precursor of the perovskite compound in the poor solvent at 25°C (the maximum amount of solute that can dissolve in 100g of solvent) can, for example, be less than 1g per 100g of solvent, or less than 0.5g per 100g of solvent.

[0095] Examples of unsuitable solvents include substituted aliphatic hydrocarbons such as dichloromethane and chloroform; aromatic compounds such as toluene, benzene, chlorobenzene, and tetrahydronaphthalene; ethers such as diethyl ether and tetrahydrofuran (THF); alcohols with 3 or more carbon atoms; hydrocarbons with 4 to 10 carbon atoms; and organic solvents such as acetic acid. These solvents can be used alone or in combination of two or more. It should be noted that in this application, aromatic compounds include compounds containing aromatic rings. In one embodiment, chlorobenzene is the unsuitable solvent.

[0096] If a poor solvent is applied to the coating, it promotes the formation of perovskite compound nuclei within the coating. These nuclei then grow into perovskite compound grains through subsequent annealing.

[0097] Coating with poor solvents can be performed using any coating method that can achieve uniform coating. Examples of applicable coating methods include spin coating, inkjet coating, spray coating, doctor blade coating, and mold coating.

[0098] From the perspective of the stability of the precursor solution, coating with a poor solvent can be carried out in a dry gas atmosphere, especially in an inert gas atmosphere. The inert gas can be any gas that does not react with the solute in the precursor solution. Examples of inert gases include nitrogen and argon.

[0099] (b) Annealing (S2)

[0100] The coating is annealed. Annealing can be performed by heating the coating at a temperature of, for example, 70°C to 200°C. Through annealing, the coating crystallizes to form a perovskite compound with a perovskite-type crystal structure. This forms a photoelectric conversion layer.

[0101] It should be noted that the manufacturing method of the embodiment may further include: drying the coating to remove solvent from the coating before annealing it. Drying can be carried out by any drying method such as heating the coating, blowing drying gas onto the coating, or placing the coating in a reduced pressure environment. The drying and annealing of the coating can also be performed in one step.

[0102] The embodiments of this disclosure have been described in detail above, but this disclosure is not limited to the above embodiments, and various design changes can be made within the scope of the technology described in the claims.

[0103] Example

[0104] The present disclosure will now be described in more detail through examples. However, the scope of the present disclosure is not limited to these examples.

[0105] 1. Manufacturing of solar cells

[0106] Comparative Example 1

[0107] A glass substrate (hereinafter appropriately referred to as the "substrate") with an indium tin oxide (ITO) film on its surface is prepared, wherein the ITO film is patterned by photolithography. The surface of the ITO film is subjected to UV ozone treatment for 10 minutes. Poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) is dissolved in dehydrated chlorobenzene to prepare a chlorobenzene solution of PTAA with a concentration of 4.5 mg / mL. The solution is filtered through a filter and then spin-coated onto the ITO film at 2000 rpm. Next, the substrate is placed on a hot plate and annealed at 100°C. A hole transport layer is thus formed on the ITO film.

[0108] A precursor solution was prepared by dissolving 46.95 mg of cesium iodide (CsI), 64.74 mg of ammonium methyl bromide (MABr), 490.97 mg of formamidinium hydroiodate (FAI), 192.32 mg of lead(II) bromide (PbBr2), and 1424.46 mg of lead(II) iodide (PbI2) in a mixed solvent of 2.4 mL of dimethylformamide (DMF) and 0.6 mL of dimethyl sulfoxide (DMSO). The precursor solution contained CsI in a molar ratio of 0.05:0.79:0.16:1:2.55:0.45. + HC(NH2)2 + CH3NH3 + Pb 2+ I - and Br - That is, the precursor solution contains Cs in a molar ratio of 1:1:3. + HC(NH2)2 + and CH3NH3 + The constituent cations A and Pb are Pb. 2+ Cation B, and I - and Br - The anion X constitutes 1 .

[0109] The precursor solution was filtered and then spin-coated onto the hole transport layer at 4000 rpm to form a coating. Chlorobenzene was added dropwise to the coating during spin-coating. Next, the substrate was placed on a hot plate and the coating was annealed at 120°C. This formed a photoelectric conversion layer on the hole transport layer.

[0110] [6,6]-phenyl-C 61 25 mg / mL methyl butyrate (PCBM) was dissolved in dehydrated 2-propanol to prepare a 2-propanol solution of PCBM. The solution was filtered and then spin-coated onto the photoelectric conversion layer at 1500 rpm. This formed an electron transport layer on the photoelectric conversion layer.

[0111] A patterned silver layer with a thickness of 100 nm was formed on the electron transport layer by vacuum evaporation using a metal mask. This yielded a solar cell.

[0112] Examples 1 to 4 and Comparative Example 2

[0113] In addition to the same amounts of CsI, MABr, FAI, PbBr2, and PbI2 as in Comparative Example 1, lead(II) chloride (PbCl2) in the amounts listed in Table 1 was dissolved in a mixed solvent of DMF and DMSO in the same amounts as in Comparative Example 1 to prepare a precursor solution. The precursor solution contained CsI in a molar ratio of 0.05:0.79:0.16:(1+0.5a):2.55:0.45:a (the value of a is listed in Table 1). + HC(NH2)2 + CH3NH3 + Pb 2+ I - ,Br - and Cl - That is, the precursor solution contains Cs in a molar ratio of 1:(1+0.5a):3:a. + HC(NH2)2 + and CH3NH3 + The constituent cations A and Pb are Pb. 2+ Cation B, from I - and Br - The anion X constitutes 1 and for Cl - anion X 2 .

[0114] A solar cell was manufactured in the same manner as in Comparative Example 1, except that the precursor solution was used.

[0115] Comparative Example 3

[0116] A precursor solution was prepared by dissolving 159.62 mg of CsI, 515.83 mg of FAI, and 1666.04 mg of PbI₂ in a mixed solvent of 2.4 mL of DMF and 0.6 mL of DMSO. The precursor solution contained CsI in a molar ratio of 0.17:0.83:1:3. + HC(NH2)2 + Pb 2+ and I - That is, the precursor solution contains Cs in a molar ratio of 1:1:3. + and HC(NH2)2 + The constituent cations A and Pb are Pb. 2+ The cation B, and I - anion X 1 .

[0117] A solar cell was manufactured in the same manner as in Comparative Example 1, except that the precursor solution was used.

[0118] Example 5 and Comparative Example 4

[0119] In addition to the same amounts of CsI, FAI, and PbI2 as in Comparative Example 3, the amount of PbCl2 listed in Table 2 was dissolved in a mixed solvent of DMF and DMSO, the same amount as in Comparative Example 3, to prepare a precursor solution. The precursor solution contained CsI in a molar ratio of 0.17:0.83:(1+0.5a):3:a (the value of a is listed in Table 2). + HC(NH2)2 + Pb 2+ I - and Cl - That is, the precursor solution contains Cs in a molar ratio of 1:(1+0.5a):3:a. + and HC(NH2)2 + The constituent cations A and Pb are Pb. 2+ The cation B is I - anion X 1 and for Cl - anion X 2 .

[0120] A solar cell was manufactured in the same manner as in Comparative Example 1, except that the precursor solution was used.

[0121] 2. Measurement of power generation efficiency

[0122] A light-shielding mask with an opening smaller than the effective power generation area of ​​the solar cell is placed on the solar cell. Simulated sunlight (1 SUN, 1000 W / m²) is applied to the solar cell using a solar simulator. 2While scanning the voltage between -0.2V and 1.2V using a source meter, the current value at each voltage was measured. The power generation efficiency of the solar cell was calculated from the measured values. Table 1 shows the power generation efficiency of the solar cells of Examples 1-4 and Comparative Examples 1 and 2, normalized to the power generation efficiency of the solar cell of Comparative Example 1 (i.e., the power generation efficiency of the solar cells of Examples 1-4 and Comparative Examples 1 and 2 divided by the power generation efficiency of the solar cell of Comparative Example 1). Table 2 shows the power generation efficiency of the solar cells of Examples 5 and Comparative Examples 3 and 4, normalized to the power generation efficiency of the solar cell of Comparative Example 3 (i.e., the power generation efficiency of the solar cells of Examples 5 and Comparative Examples 3 and 4 divided by the power generation efficiency of the solar cell of Comparative Example 3).

[0123] Furthermore, the relationship between the normalized power generation efficiency of the solar cell and the α value of the precursor solution is shown in... Figure 4 , Figure 5 The chart. Figure 4 This represents the normalized power generation efficiency of the solar cells in Examples 1-4 and Comparative Examples 1 and 2. Figure 5 The normalized power generation efficiency of the solar cells in Example 5 and Comparative Examples 3 and 4 is represented.

[0124] From Table 1, Table 2 and Figure 4 , Figure 5 It can be seen that the power generation efficiency increases when the value of a exceeds 0 and is below 0.21.

[0125] [Table 1]

[0126]

[0127] [Table 2]

[0128]

[0129] 3. Structural evaluation of the photoelectric conversion layer

[0130] Photoelectric conversion layers were fabricated using the same method as in Examples 1-4 and Comparative Examples 1 and 2, and X-ray diffraction (XRD) measurements were performed using θ-2θ scanning. All photoelectric conversion layers exhibited peaks of a perovskite-type crystal structure. Figure 6The figure shows a graph obtained by plotting the ratio of the peak intensity (peak area) of perovskite (100) to the peak intensity of ITO (222) relative to the a value. Within the range of a value of 0.03 to 0.16, the larger the a value, the greater the peak intensity of the perovskite. According to simulation results recorded in Minjin Kim et al., “Methylammonium Chloride Induces Intermediate Phase Stabilization for Efficient Perovskite Solar Cells,” Joule, Volume 3, Issue 9, 2179-2192, 2019, perovskite compound crystals containing Cl- and those without Cl-... - Compared to perovskite compound crystals, these are thermodynamically stable. Therefore, it is assumed that within the range of 0.03–0.16, the Cl- content of the precursor solution is relatively stable. - The higher the content of PbI2 (i.e., the larger the a value), the more crystallinity of the perovskite compound in the photoelectric conversion layer increases, thereby increasing the peak intensity of the perovskite. In Comparative Example 2, with an a value of 0.31, the peak intensity of PbI2 is significantly higher, while the peak intensity of the perovskite is relatively lower.

[0131] Furthermore, the photoelectric conversion layers fabricated using the same method as Examples 1-4 and Comparative Examples 1 and 2 were observed using a scanning electron microscope (SEM). In Comparative Example 2, with an a value of 0.31, numerous film defects resembling pinholes or pits were confirmed in the photoelectric conversion layer. Additionally, it was confirmed that the larger the a value, the larger the grain size of the photoelectric conversion layer, and the presence of a large amount of PbCl2 on the surface.

[0132] Based on the above results, it can be concluded that when the a value is greater than 0 and less than 0.21, the power generation efficiency of the solar cell is improved due to the high crystallinity of the perovskite compound in the photoelectric conversion layer. When the a value exceeds 0.21, the photoelectric conversion layer has a large number of film defects and contains a large amount of PbCl2, therefore the power generation efficiency of the solar cell is considered to be low.

Claims

1. A method for manufacturing a solar cell, the solar cell having a photoelectric conversion layer, the photoelectric conversion layer containing a perovskite compound represented by formula (1) below, ABX3(1) wherein A represents at least one cation selected from the group consisting of Cs + , CH3NH3 + , and HC(NH2)2 + , B represents at least one divalent cation selected from the group consisting of Pb 2+ and Sn 2+ , and X represents at least one anion selected from the group consisting of halide anions; The manufacturing method includes: The precursor solution is coated onto the coating surface to form a coating layer; and The photoelectric conversion layer is formed by annealing the coating. The precursor solution contains A, B, X, and Y in a molar ratio of 1 : (1 + 0.5a) : 3 : a 1 and X 2 , X 1 represents at least one anion selected from the group consisting of halide anions, X 2 represents Cl - , and a represents a real number greater than 0 and 0.21 or less.

2. The method according to claim 1, wherein, X 1 Indicates selected from Br - and I - At least one anion in it.

3. The method according to claim 1 or 2, wherein, The precursor solution contains A and B in a molar ratio of 1:1:0.5a:3:a. 1 B 2 X 1 and X 2 B 1 Indicates that it is selected from Pb 2+ and Sn 2+ At least one divalent cation in, B 2 Pb 2+ .

4. The method according to claim 3, wherein, The precursor solution is further prepared by dissolving at least one compound represented by formula (2), at least one compound represented by formula (3a), and at least one compound represented by formula (4a) in a solvent. AX 1 (2) B 1 X 1 2(3a) B 2 X 2 2(4a)。 5. The method according to claim 1 or 2, wherein, a represents a real number between 0.03 and 0.16.

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