Solar cell manufacturing methods

Abstract

Provided is a method for manufacturing a perovskite solar cell capable of improving the power generation efficiency of a solar cell. 【Solution means】ABX3 (where 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). A method for manufacturing a solar cell having a photoelectric conversion layer containing a perovskite compound represented by the formula is provided. The precursor solution used in the manufacturing method contains A, B, X 1 , and X 2 in a molar ratio of 1:(1 + 0.5a):3:a. 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 less than or equal to 0.21.

Description

[Technical Field]

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

[0002] One type of solar cell known is the perovskite solar cell, in which the main component of the photoelectric conversion layer is a perovskite compound.

[0003] Patent Document 1 contains the formula ABX 3-y X' y A process for producing a perovskite compound represented by the formula (wherein 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 between 0.05 and 2.95) is described. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Patent No. 6263186 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] Perovskite solar cells are desirable to have 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. [Means for solving the problem]

[0006] The forms of this disclosure include the following: [Aspect 1] The following formula (1) ABX3(1) (In the formula, A is Cs + CH3NH3 +and HC(NH2)2 + represents at least one cation selected from the group consisting of B is Pb 2+ and Sn 2+ represents at least one divalent cation selected from the group consisting of X represents at least one anion selected from the group consisting of halide anions) A method for manufacturing a solar cell having a photoelectric conversion layer containing a perovskite compound represented by Applying a precursor solution to a coating surface to form a coating, Annealing the coating to form the photoelectric conversion layer, including The precursor solution contains A, B, X 1 , and X 2 in a molar ratio of 1:(1 + 0.5a):3:a, X 1 represents at least one anion selected from the group consisting of halide anions, X 2 represents Cl - , a represents a real number greater than 0 and less than or equal to 0.21. [Aspect 2] X 1 is Br - and I - represents at least one anion selected from the group consisting of, the method according to aspect 1. [Aspect 3] The precursor solution contains A, B 1 , B 2 , X 1 , and X 2 in a molar ratio of 1:1:0.5a:3:a, B 1 is Pb 2+ and Sn 2+ represents at least one divalent cation selected from the group consisting of, B 2 is Pb 2+ represents, the method according to aspect 1 or 2. [Aspect 4] At least one compound represented by the following formula (2), at least one compound represented by the following formula (3a), and at least one compound represented by the following formula (4a) AX 1 (2) B 1 X 1 2(3a) B 2 X 2 2(4a) The method according to embodiment 3, further comprising dissolving in a solvent to prepare the precursor solution. [Aspect 5] The method according to any one of embodiments 1 to 4, wherein a represents a real number between 0.03 and 0.16. [Effects of the Invention]

[0007] The manufacturing method disclosed herein can improve the power generation efficiency of perovskite solar cells. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic cross-sectional view showing an example of a solar cell structure. [Figure 2] This is a schematic diagram showing a perovskite crystal structure. [Figure 3] This is a flowchart showing the method for manufacturing a solar cell according to the embodiment. [Figure 4] This graph shows the relationship between the normalized power generation efficiency and the value a of solar cells produced in Examples 1-4 and Comparative Examples 1 and 2, using a precursor solution containing Cs+, HC(NH2)2+, CH3NH3+, Pb2+, I-, Br-, and Cl- in a molar ratio of 0.05:0.79:0.16:(1+0.5a):2.55:0.45:a. [Figure 5] This graph shows the relationship between the normalized power generation efficiency and the value a of solar cells produced in Example 5 and Comparative Examples 3 and 4, using a precursor solution containing Cs+, HC(NH2)2+, Pb2+, I-, and Cl- in a molar ratio of 0.17:0.83:(1+0.5a):3:a. [Figure 6]This graph shows the relationship between the ratio of the perovskite (100) diffraction peak intensity and the ITO (222) diffraction peak intensity and the value a. [Modes for carrying out the invention]

[0009] Embodiments will be described below with reference to the drawings as appropriate. In the drawings referenced in the following description, the dimensional ratios and shapes of each component may be exaggerated for illustrative purposes and may differ from the actual dimensional ratios and shapes. In this application, "on top of" includes both "directly on top of" and "indirectly on top of" unless otherwise specified in the context. The upper and lower limits of the numerical ranges described in this application may be used individually or in any combination.

[0010] I. Solar cells First, we will describe a perovskite solar cell (hereinafter also simply referred to as "solar cell") manufactured by the manufacturing method according to the embodiment described later. Figure 1 is a schematic cross-sectional view showing an example of the structure of a solar cell.

[0011] As shown in Figure 1, in one embodiment, the solar cell C has 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 in this order.

[0012] (a) Photoelectric conversion layer 4 The photoelectric conversion layer 4 is located between the first carrier transport layer 3a and the second carrier transport layer 3b. When the photoelectric conversion layer 4 receives light, it generates charge carriers. 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.

[0013] 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 carrier transport layer 3a or the second carrier transport layer 3b, which are hole transport layers. 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 carrier transport layer 3a or the second carrier transport layer 3b, which are electron transport layers.

[0014] The photoelectric conversion layer 4 contains a perovskite compound. The photoelectric conversion layer 4 may contain a perovskite compound as its main component. The perovskite compound content 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.

[0015] Generally, perovskite compounds are represented by the following formula (1) ABX3(1) (In the formula, A represents a monovalent cation, B represents a divalent cation, and X represents a monovalent anion.) It is represented as follows.

[0016] Perovskite compounds have a perovskite-type crystal structure. Figure 2 is a schematic diagram showing a perovskite-type crystal structure. As shown in Figure 2, the perovskite-type crystal structure has a cubic unit cell, with A at each vertex of the cubic crystal, B at the body center, and X at each face center. The fact that a compound has a perovskite-type crystal structure can be confirmed, for example, by X-ray diffraction (XRD) analysis.

[0017] In one embodiment, in formula (1), A is a cesium cation (Cs + ), methylammonium (MA) cation (CH3NH3 + ), and formamidinium (FA) cation (HC(NH2)2 + B represents at least one cation selected from the group consisting of ), where B is a lead(II) cation (Pb 2+) and tin(II) cation (Sn 2+ Represents at least one divalent cation selected from the group consisting of ), preferably Pb 2+ X represents at least one anion selected from the group consisting of halide anions, preferably a fluoride anion (F - ), chloride anion (Cl - ), bromide anion (Br - ) and iodide anions (I - Represents at least one anion selected from the group consisting of ), especially Cl - , Br - and I - Represents at least one anion selected from the group consisting of [the specified elements].

[0018] (b) First carrier transport layer 3a and second carrier transport layer 3b The first carrier transport layer 3a accepts charge carriers generated in the photoelectric conversion layer 4 and transports these charge carriers to the first electrode layer 2a. If the first carrier transport layer 3a is a hole transport layer, it transports holes to the first electrode layer 2a. If the first carrier transport layer 3a is an electron transport layer, it transports electrons to the first electrode layer 2a.

[0019] The second carrier transport layer 3b accepts charge carriers generated in the photoelectric conversion layer 4 and transports these charge carriers to the second electrode layer 2b. If the second carrier transport layer 3b is a hole transport layer, it transports holes to the second electrode layer 2b. If the second carrier transport layer 3b is an electron transport layer, it transports electrons to the second electrode layer 2b.

[0020] The hole transport layer transports holes generated by photoelectric conversion in the photoelectric conversion layer 4 to the first electrode layer 2a or the second electrode layer 2b. As the material for the hole transport layer, known organic or inorganic materials suitable for use in hole transport layers can be used.

[0021] Examples of organic materials that can be used as materials for the hole transport layer include 2,2',7,7'-tetrakis-(N,N-di-4-methoxyphenylamino)-9,9'-spirobifluorene (Spiro-OMeTAD), polyethylenedioxythiophene:polystyrene sulfonic acid (PEDOT:PSS), and poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA).

[0022] Examples of inorganic materials that can be used as materials for hole transport layers include nickel oxide and copper oxide.

[0023] 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. As the material for the electron transport layer, known organic or inorganic materials suitable for electron transport layers can be used.

[0024] Examples of organic materials that can be used as materials for electron transport layers include fullerene compounds, phenanthroline derivatives (e.g., bathocuproine), and polyethyleneimines. Examples of fullerene compounds include fullerenes (e.g., C60 fullerene, C70 fullerene) and derivatives of fullerenes with substituents (e.g., [6,6]-phenyl-C 61 -Methyl butyrate (also known as PCBM or

[60] PCBM), [6,6]-phenyl-C 71 - Methyl butyrate (also known as PCBM or

[70] PCBM) is an example.

[0025] Examples of inorganic materials that can be used as materials for electron transport layers include titanium oxide, tin oxide, and zinc oxide.

[0026] 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 has a substrate 1, a cathode, an electron transport layer, a photoelectric conversion layer 4, a hole transport layer, and an anode in this order. In this embodiment, the material of the hole transport layer may be Spiro-OMeTAD, PTAA, or nickel oxide. In this embodiment, the material of the electron transport layer may be fullerene, PCBM, bathocuproine, polyethyleneimines, titanium oxide, or tin oxide.

[0027] 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 comprises a substrate 1, an anode, a hole transport layer, a photoelectric conversion layer 4, an electron transport layer, and a cathode in this order. In this embodiment, the material of the hole transport layer may be PEDOT:PSS, PTAA, or nickel oxide. In this embodiment, the material of the electron transport layer may be fullerene, PCBM, bathocuproine, or polyethyleneimines.

[0028] (c) First electrode layer 2a and second electrode layer 2b The first electrode layer 2a is the electrode in contact with the first carrier transport layer 3a. The second electrode layer 2b is the electrode in contact with the second carrier transport layer 3b.

[0029] As the materials for the first electrode layer 2a and the second electrode layer 2b, known materials usable for electrodes of a solar cell C can be used. Examples of materials usable 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), and fluorine-doped tin oxide (FTO), and carbon nanotubes. The materials for the first electrode layer 2a and the second electrode layer 2b may be ITO, IZO, or FTO. When light is incident on the solar cell C through the surface of the substrate 1, the first electrode layer 2a may be transparent, and the second electrode layer 2b may be transparent or opaque. When light is incident on the solar cell C through the surface of the second electrode layer 2b, the first electrode layer 2a may be transparent or opaque, and the second electrode layer 2b may be transparent.

[0030] (d) Substrate 1 The substrate 1 supports 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.

[0031] The substrate 1 may be in the form of a plate or a film. 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 cycloolefin polymer, and metallic materials such as stainless steel and silicon.

[0032] The substrate 1 may be transparent or opaque. A transparent substrate is used when light is incident on the solar cell C through the surface of the substrate 1. Examples of transparent substrates include substrates made of glass, polyethylene terephthalate, polyethylene naphthalate, polyimide, polyamide, polyamideimide, or cycloolefin polymer. An opaque substrate can be used when light is incident on the solar cell C through the surface of the second electrode layer 2b.

[0033] II. Manufacturing Methods for Solar Cells Next, a method for manufacturing a solar cell according to the embodiment will be described. As shown in Figure 3, the method for manufacturing a solar cell according to the embodiment includes applying a precursor solution to a coating surface to form a coating (S1) and annealing the coating to form a photoelectric conversion layer (S2).

[0034] 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 in that order before coating a precursor solution, and optionally further including forming a second carrier transport layer and a second electrode layer on the photoelectric conversion layer in that order 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 in the same manner as in conventional photoelectric conversion elements. Therefore, a detailed explanation of the methods for forming these layers is omitted.

[0035] (a) Application of precursor solution (S1) A precursor solution is applied to the coating surface to form a coating. The coating surface may be the surface of the first carrier transport layer. If the solar cell does not have a first carrier transport layer, the coating surface may 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 may be the surface of those other layers. In other words, the coating surface is appropriately selected according to the configuration of the solar cell being manufactured.

[0036] The precursor solution contains a solute which is a precursor of the perovskite compound represented by formula (1) above. The precursor solution is A, B, X 1 , and X 2 It contains in a molar ratio of 1:(1+0.5a):3:a, where A is Cs + CH3NH3 + , and HC(NH2)2 + It represents at least one cation selected from the group consisting of, where B is Pb 2+ and Sn 2+ It represents at least one divalent cation selected from the group consisting of X1 X represents at least one anion selected from the group consisting of halide anions, 2 is Cl - This represents a real number greater than 0 and less than or equal to 0.21. In one embodiment, X 1 Br - and I - It represents at least one anion selected from the group consisting of . In one embodiment, B is Pb 2+ This represents a real number between 0.03 and 0.21, between 0.03 and 0.16, or between 0.06 and 0.16. Note that X in equation (1) is X 1 or X 2 It originates from at least one of the following.

[0037] In one embodiment, the precursor solution is A, B 1 B 2 , X 1 , and X 2 It contains in a molar ratio of 1:1:0.5a:3:a. However, B 1 Pb 2+ and Sn 2+ Represents at least one divalent cation selected from the group consisting of, B 2 is Pb 2+ Represents A, X 1 , X 2 , a is as defined above. In this embodiment, B in formula (1) is B 1 or B 2 It originates from at least one of the following.

[0038] In one embodiment, the precursor solution comprises at least one compound represented by the following formula (2), at least one compound represented by the following formula (3), and at least one compound represented by the following formula (4). AX 1 (2) BX 1 2(3) BX 2 2(4) (In the formula, A, B, X 1 , and X 2 (As defined above) It can be prepared by dissolving it in a suitable solvent.

[0039] In one embodiment, the precursor solution is, for example, at least one compound represented by formula (2) below, at least one compound represented by formula (3a) below, and at least one compound represented by formula (4a) below. AX 1 (2) B 1 X 1 2(3a) B 2 X 2 2(4a) (In the formula, A, B 1 B 2 , X 1 , and X 2 (As defined above) It can be prepared by dissolving it in a suitable solvent.

[0040] The solvent in the precursor solution may be a polar solvent from the viewpoint of solute solubility. Alternatively, the solvent in the precursor solution may be an aprotic solvent from the viewpoint of solute stability. Examples of solvents that can be used as the solvent for the precursor solution include N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), γ-butyrolactone, and mixed solvents containing one or more of these.

[0041] The precursor solution may be applied by any coating method that can form a uniform coating. Examples of applicable coating methods include spin coating, inkjet coating, spray coating, blade coating, and die coating.

[0042] The application of the precursor solution may be carried out in a dry air atmosphere, and more particularly in an inert gas atmosphere, from the viewpoint of the stability of the precursor solution. The inert gas may be any gas that does not react with the solute of the precursor solution. Examples of inert gases include nitrogen and argon.

[0043] A poor solvent may be applied to the coating. In the poor solvent, the solute, which is the precursor of the perovskite compound, has a lower solubility than the solubility of the precursor solution in the solvent. The poor solvent may be a solvent that substantially does not dissolve the precursor of the perovskite compound. The solubility of the precursor of the perovskite compound at 25°C in the poor solvent (the maximum amount of solute that can be dissolved in 100g of solvent) may be, for example, less than 1g per 100g of solvent or less than 0.5g per 100g of solvent.

[0044] Examples of poor solvents include substituted aliphatic hydrocarbons such as dichloromethane and chloroform; aromatic compounds such as toluene, benzene, chlorobenzene, and tetralin; ethers such as diethyl ether and tetrahydrofuran (THF); alcohols having 3 or more carbon atoms; hydrocarbons having 4 to 10 carbon atoms; and organic solvents such as acetic acid. These solvents may be used individually or in combination of two or more. In this application, aromatic compounds include compounds that partially contain an aromatic ring. In one embodiment, the poor solvent is chlorobenzene.

[0045] Applying a poor solvent to the coating promotes the formation of crystal nuclei of the perovskite compound in the coating. These nuclei then grow through subsequent annealing, forming grains of the perovskite compound.

[0046] Poor solvent coating may be performed by any coating method that allows for uniform coating. Examples of applicable coating methods include spin coating, inkjet coating, spray coating, blade coating, and die coating.

[0047] The coating of the poor solvent may be carried out in a dry air atmosphere, and more particularly in an inert gas atmosphere, from the viewpoint of the stability of the precursor solution. The inert gas may be any gas that does not react with the solute in the precursor solution. Examples of inert gases include nitrogen and argon.

[0048] (b) Annealing (S2) The coating is annealed. Annealing may be performed by heating the coating at a temperature of, for example, 70°C to 200°C. Annealing causes the coating to crystallize, forming a perovskite compound having a perovskite-type crystalline structure. This forms a photoelectric conversion layer.

[0049] The manufacturing method according to the embodiment may further include drying the coating to remove the solvent in the coating before annealing the coating. Drying may be carried out by any drying method such as heating the coating, blowing a dry gas onto the coating, or placing the coating in a reduced-pressure environment. Drying and annealing of the coating may be carried out in a single step.

[0050] Although embodiments of this disclosure have been described in detail above, this disclosure is not limited to the embodiments described above, and various design modifications can be made without departing from the technical scope described in the claims. [Examples]

[0051] The present disclosure will be further described below with reference to examples. However, the scope of the present disclosure is not limited to these examples.

[0052] 1. Manufacturing of solar cells Comparative Example 1 A glass substrate (hereinafter referred to as "substrate" as appropriate) with an indium tin oxide (ITO) film patterned by photolithography on its surface was prepared. The surface of the ITO film was treated with UV ozone for 10 minutes. Poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) was dissolved in dehydrated chlorobenzene to prepare a 4.5 mg / mL PTAA chlorobenzene solution. This solution was filtered and coated onto the ITO film by spin coating at 2000 rpm. The substrate was then placed on a hot plate and annealed at 100°C. This formed a hole transport layer on the ITO film.

[0053] 46.95 mg of cesium iodide (CsI), 64.74 mg of methylammonium bromide (MABr), 490.97 mg of formamidinium iodide (FAI), 192.32 mg of lead(II) bromide (PbBr2), and 1424.46 mg of lead(II) iodide (PbI2) were dissolved in a mixed solvent of 2.4 mL of dimethylformamide (DMF) and 0.6 mL of dimethyl sulfoxide (DMSO) to prepare a precursor solution. The precursor solution contained Cs + , HC(NH2)2 + , CH3NH3 + , Pb 2+ , I - , and Br - in a molar ratio of 0.05:0.79:0.16:1:2.55:0.45. That is, the precursor solution contained cation A consisting of Cs + , HC(NH2)2 + , and CH3NH3 + , cation B which is Pb 2+ , and anion X consisting of I - and Br - in a molar ratio of 1:1:3. 1

[0054] The precursor solution was filtered with a filter and applied by spin coating at 4000 rpm onto the hole transport layer to form a coating. Chlorobenzene was dropped onto the coating during rotation. Then, the substrate was placed on a hot plate and the coating was annealed at 120 °C. Thereby, a photoelectric conversion layer was formed on the hole transport layer.

[0055] [6,6]-Phenyl-C 61 -methyl ester of butyric acid (PCBM) was dissolved in dehydrated 2-propanol to prepare a 2-propanol solution of PCBM with a concentration of 25 mg / mL. This solution was filtered with a filter and applied by spin coating at 1500 rpm onto the photoelectric conversion layer. Thereby, an electron transport layer was formed on the photoelectric conversion layer.

[0056] A 100 nm thick patterned silver layer was formed on the electron transport layer by vacuum deposition using a metal mask. This resulted in the creation of a solar cell.

[0057] Examples 1-4 and Comparative Example 2 In addition to the same amounts of CsI, MABr, FAI, PbBr2, and PbI2 as in Comparative Example 1, the amount of lead(II) chloride (PbCl2) listed in Table 1 was dissolved in the same amount of DMF and DMSO mixed solvent as in Comparative Example 1 to prepare a precursor solution. The precursor solution was Cs + , HC(NH2)2 + CH3NH3 + Pb 2+ , I - , Br - , and Cl - It contained Cs in a molar ratio of 0.05:0.79:0.16:(1+0.5a):2.55:0.45:a (the value a is listed in Table 1). That is, the precursor solution contained Cs + , HC(NH2)2 + , and CH3NH3 + A cation A consisting of Pb 2+ Cation B is I - and Br - Anion X 1 And, Cl - Anion X 2 It contained in a molar ratio of 1:(1+0.5a):3:a.

[0058] A solar cell was manufactured in the same manner as in Comparative Example 1, except that this precursor solution was used.

[0059] Comparative Example 3 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. + , HC(NH2)2 + Pb 2+ , and I - It contained Cs in a molar ratio of 0.17:0.83:1:3. That is, the precursor solution was Cs +and HC(NH2)2 + A cation A consisting of Pb 2+ Cation B is I - Anion X 1 It contained them in a molar ratio of 1:1:3.

[0060] A solar cell was manufactured in the same manner as in Comparative Example 1, except that this precursor solution was used.

[0061] Example 5 and Comparative Example 4 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 the same amount of DMF and DMSO mixed solvent as in Comparative Example 3 to prepare a precursor solution. The precursor solution was Cs + , HC(NH2)2 + Pb 2+ , I - , and Cl - It contained Cs in a molar ratio of 0.17:0.83:(1+0.5a):3:a (the value a is listed in Table 2). That is, the precursor solution contained Cs + and HC(NH2)2 + A cation A consisting of Pb 2+ Cation B is I - Anion X 1 And, Cl - Anion X 2 It contained in a molar ratio of 1:(1+0.5a):3:a.

[0062] A solar cell was manufactured in the same manner as in Comparative Example 1, except that this precursor solution was used.

[0063] 2. Measurement of power generation efficiency A light-shielding mask with an opening smaller than the effective power generation area was installed on the effective power generation area of ​​the solar cell. A solar simulator was used to simulate sunlight (1 SUN, 1000 W / m²) on the solar cell. 2While irradiating with ), the voltage was swept back and forth between -0.2V and 1.2V using a source meter, and the current value at each voltage was measured. The power generation efficiency of the solar cells was calculated from the measured values. Table 1 shows the power generation efficiency of the solar cells of Examples 1 to 4 and Comparative Examples 1 and 2, normalized by 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 to 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 Example 5 and Comparative Examples 3 and 4, normalized by the power generation efficiency of the solar cell of Comparative Example 3 (i.e., the power generation efficiency of the solar cells of Example 5 and Comparative Examples 3 and 4 divided by the power generation efficiency of the solar cell of Comparative Example 3).

[0064] Furthermore, the relationship between the normalized power generation efficiency of the solar cell and the value a in the precursor solution is shown in the graphs in Figures 4 and 5. Figure 4 shows the normalized power generation efficiency of the solar cells of Examples 1-4 and Comparative Examples 1 and 2, while Figure 5 shows the normalized power generation efficiency of the solar cells of Example 5 and Comparative Examples 3 and 4.

[0065] As can be seen from Tables 1 and 2, and Figures 4 and 5, power generation efficiency improved when the value of a was greater than 0 and less than or equal to 0.21.

[0066] [Table 1]

[0067] [Table 2]

[0068] 3. Structural evaluation of the photoelectric conversion layer 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 showed peaks of a perovskite-type crystal structure. Figure 6 shows a graph plotting the ratio of the perovskite (100) peak intensity (peak area) to the ITO (222) peak intensity against the value a. Within the range of a from 0.03 to 0.16, the larger the value a, the greater the perovskite peak intensity. According to the simulation results described in Minjin Kim et al., “Methylammonium Chloride Induces Intermediate Phase Stabilization for Efficient Perovskite Solar Cells”, Joule, Volume 3, Issue 9, 2179-2192, 2019, Cl - Perovskite compound crystals containing Cl - It is thermodynamically more stable than perovskite compound crystals that do not contain Cl. Therefore, when the value of a is in the range of 0.03 to 0.16, the precursor solution is Cl - It is thought that the higher the content of (i.e., the larger the value of a), the better the crystallinity of the perovskite compound in the photoelectric conversion layer, which in turn increased the peak intensity of the perovskite. In Comparative Example 4, where the value of a was 0.31, the peak intensity of PbI2 was significantly higher, while the peak intensity of the perovskite was relatively lower.

[0069] Furthermore, photoelectric conversion layers prepared using the same method as in Examples 1-4 and Comparative Examples 1 and 2 were observed using a scanning electron microscope (SEM). In Comparative Example 2, where the value a was 0.31, it was confirmed that there were many film defects such as pinholes or pits in the photoelectric conversion layer. It was also confirmed that the larger the value a, the larger the grain size of the photoelectric conversion layer and the greater the presence of PbCl2 on the surface.

[0070] Based on these results, when the value a is greater than 0 and less than or equal to 0.21, it is thought that the power generation efficiency of the solar cell was improved due to the high crystallinity of the perovskite compound in the photoelectric conversion layer. When the value a is greater than 0.21, it is thought that the power generation efficiency of the solar cell was low because the photoelectric conversion layer had many film defects and contained a large amount of PbCl2. [Explanation of Symbols]

[0071] 1: Circuit board 2a: First electrode layer 2b: Second electrode layer 3a: First carrier transport layer 3b: Second carrier transport layer 4: Photoelectric conversion layer C: Solar battery

Claims

1. The following formula (1) ABX ３ (1) (In the formula, A is Cs ＋ ,CH ３ NH ３ ＋ , and HC(NH ２ ) ２ ＋ Represents at least one cation selected from the group consisting of, B represents at least one divalent cation selected from the group consisting of Pb ２＋ and Sn ２＋ and represents X represents at least one anion selected from the group consisting of halide anions. A method for manufacturing a solar cell having a photoelectric conversion layer containing a perovskite compound represented by, The process involves applying a precursor solution to the surface to form a coating, The coating is annealed to form the photoelectric conversion layer, Includes, The aforementioned precursor solution is A, B, X １ , and X ２ It contains in a molar ratio of 1:(1+0.5a):3:a, X １ This represents at least one anion selected from the group consisting of halide anions. X ２ Cl － This represents, a is a method for representing a real number greater than or equal to 0.

21.

2. X １ ga Br － and I － The method according to claim 1, which represents at least one anion selected from the group consisting of the following.

3. The aforementioned precursor solution is A, B １ , B ２ , X １ , and X ２ It contains in a molar ratio of 1:1:0.5a:3:a, B １ Pb ２＋ and Sn ２＋ Represents at least one divalent cation selected from the group consisting of, B ２ Pb ２＋ The method according to claim 1 or 2, which represents the representation.

4. At least one compound represented by the following formula (2), at least one compound represented by the following formula (3a), and at least one compound represented by the following formula (4a). AX １ (2) B １ X １ ２ (3a) B ２ X ２ ２ (4a) The method according to claim 3, further comprising dissolving in a solvent to prepare the precursor solution.

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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