Solar cell and its manufacturing method

Abstract

To provide halogenated lead-based perovskite having high water resistance and use thereof.SOLUTION: Halogenated lead-based perovskite is provided in which a component of an aqueous solution of halogenated hydroacid of a π-conjugated polymer or an oligomer having an alkylamine or an alkylamino group remains.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a lead halide-based perovskite, and more particularly to a lead halide-based perovskite with high water resistance and its uses. [Background technology]

[0002] Lead halide perovskites have been attracting attention in recent years as new materials with promising applications, particularly as optical device materials. For example, when lead halide perovskites are used in solar cells as optical device materials, excellent conversion efficiencies of over 25% have been reported, and they are attracting attention as next-generation solar cell materials that combine excellent cell properties with low cost.

[0003] To further improve the properties, lead halide-based perovskites are being actively investigated.

[0004] A conventional lead halide-based perovskite is obtained by a method of producing a layer of a crystalline A / M / X material, the method comprising disposing a precursor composition on a substrate, the precursor composition comprising: (a) a first precursor compound including a first cation (M) that is a metal cation or a semimetal cation; and (b) a solvent, the solvent comprising: (i) acetonitrile, propionitrile, acetone, or a mixture thereof; and (ii) an alkylamine, the crystalline A / M / X material being obtained by a method of producing a layer of a crystalline A / M / X material comprising: (ii) a compound of formula AX; (iii) acetonitrile, propionitrile, acetone, or a mixture thereof; and (iv) an alkylamine. A NH2 (in the formula, R A is C 1-8 A composition containing an alkylamine (wherein the alkyl group is an alkyl group) is known (see Patent Document 1).

[0005] In addition, conventional lead halide perovskites are modified with a matrix and organic amphiphilic molecules M, and the chemical formula is M z A y BX z+y+2 M z Ay BX z+y+2 Perovskite-based photoelectric functional materials are known (see Patent Document 2).

[0006] [Patent Document 1] Special Publication No. 2019-516232 [Patent Document 2] Special Publication No. 2016-531414 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0007] However, lead halide perovskites are generally unstable in the presence of moisture, and easily react with water, causing degradation, posing a challenge to their practical application.

[0008] That is, conventional lead halide perovskites include those that require a variety of raw materials and organic solvents, as in Patent Document 1, and those that chemically modify the organic amphiphilic molecule M to improve luminescence properties, as in Patent Document 2. However, lead halides (e.g., lead iodide (PBI2)) react with even trace amounts of water contained in the solvent to form hydrates, making it difficult to actually form high-quality perovskite thin films.

[0009] Furthermore, due to their instability to moisture, conventional lead halide perovskites have been produced in non-aqueous systems by one-step or two-step reactions (two-step methods) using organic solvents, as in Patent Documents 1 and 2, which require complicated and rigorous operations.

[0010] In particular, when attempting to fabricate solar cells using conventional lead halide-based perovskites, fabrication in a glove box is essential, as it thoroughly removes moisture from the air and eliminates factors that cause moisture degradation. That is, fabrication of conventional lead halide-based perovskites requires the use of a dehydrated solvent in a glove box. Furthermore, not only the fabrication of the conventional lead halide-based perovskites, but also the formation of the hole transport layer and the fabrication of the anode electrode are carried out in a glove box to minimize exposure to the atmosphere. These complicated operations tend to result in unstable quality and increase manufacturing costs.

[0011] The present invention has been made to solve the above-mentioned problems, and aims to provide a lead halide-based perovskite having particularly high water resistance and uses thereof. Another aim is to provide, as an example of the use thereof, a photoelectric conversion element comprising the lead halide-based perovskite. Another aim is to provide a solar cell comprising the photoelectric conversion element. [Means for solving the problem]

[0012] The present inventors have conducted extensive research into lead halide perovskites with novel properties and have discovered a novel lead halide perovskite with high water resistance. They have also discovered that photoelectric conversion elements and solar cells can be easily obtained using this lead halide perovskite, leading to the completion of the present invention.

[0013] Thus, the present invention provides a lead halide-based perovskite containing residual components of an aromatic amine hydrohalide aqueous solution or an alkylamine hydrohalide aqueous solution, as well as a photoelectric conversion element and a solar cell using the lead halide-based perovskite. [Brief explanation of the drawings]

[0014] [Figure 1]1 is a photographic image showing lead bromide before and after a saturated aqueous solution of methylamine hydrobromide is added dropwise to a lead halide-based perovskite according to Example 1 of the present invention. [Figure 2] 1 shows the measurement results of the reflectance spectrum of a lead halide perovskite according to Example 1 of the present invention. [Figure 3] 1 shows the results of X-ray diffraction measurement of lead halide perovskite according to Example 1 of the present invention. [Figure 4] 1 shows the measurement results of the time dependence of the (100) plane diffraction peak of a lead halide-based perovskite according to Example 1 of the present invention. [Figure 5] 1 is a photographic image showing the water resistance of a lead halide-based perovskite according to Example 1 of the present invention. [Figure 6] 10 is a photographic image showing lead iodide before and after a saturated aqueous solution of methylamine hydroiodide is added dropwise to a lead halide-based perovskite according to Example 2 of the present invention. [Figure 7] 1 shows the measurement results of the reflectance spectrum of a lead halide perovskite according to Example 2 of the present invention. [Figure 8] 1 shows the results of X-ray diffraction measurement of lead halide perovskite according to Example 2 of the present invention. [Figure 9] 1 is a photographic image showing the water resistance of a lead halide-based perovskite according to Example 2 of the present invention. [Figure 10] 1A is an explanatory diagram showing the configuration of a solar cell according to Example 3 of the present invention, and FIG. 1B is a photographic image of the solar cell. [Figure 11] 10 shows the measurement results of photoelectric conversion characteristics of a solar cell according to Example 3 of the present invention.

[0015] (First embodiment) The lead halide perovskite according to the first embodiment of the present invention contains residual components of an aqueous solution of a hydrohalide salt of an alkylamine or a π-conjugated polymer or oligomer having an alkylamino group.

[0016] The lead halide perovskite according to this embodiment is represented by (CH3NH3)PbX3 (X is at least one kind of halogen atom), and may be in a layered form or in a powder form.

[0017] The presence of components of a hydrohalide aqueous solution of a π-conjugated polymer or oligomer having an alkylamine or alkylamino group remaining on the lead halide-based perovskite means that the components of the hydrohalide aqueous solution remain attached to the surface of the lead halide-based perovskite. The components of the hydrohalide aqueous solution may remain on the surface of the lead halide-based perovskite in a dry state, or in a wet state with moisture derived from the aqueous solution remaining.

[0018] The alkylamine constituting this aqueous hydrohalide salt solution may have a linear or branched alkyl chain and is not particularly limited, but a lower alkyl group can be used, for example, a lower alkyl group having about 1 to 15 carbon atoms, which can be selected from the group consisting of methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, isopropylamine, diethylamine, dibutylamine, diisopropylmethylamine, triethylamine, and tributylamine.

[0019] The alkylamino group contained in the π-conjugated polymer or oligomer constituting this hydrohalide aqueous solution may have a linear or branched alkyl chain and is not particularly limited. A lower alkyl group can be used, for example, a lower alkyl group having about 1 to 15 carbon atoms, which can be selected from the group consisting of a substituted or unsubstituted methylamino group, ethylamino group, propylamino group, butylamino group, pentylamino group, hexylamino group, isopropylamino group, diethylamino group, dibutylamino group, diisopropylmethylamino group, triethylamino group, and tributylamino group.

[0020] The π-conjugated polymer or oligomer having an alkylamino group, which constitutes this hydrohalide aqueous solution, can be selected from the group consisting of polypyrrole, polyimidazole, polypyridine, polydithiophene, or polythiophene, all of which have an alkylamino group. The oligomer has a relatively small number of monomers, for example, about 2 to 10 monomers, such as a dimer, trimer, or tetramer.

[0021] Among these, from the viewpoint of ease of handling, polymers of thiophene and polymers of thiophene derivatives having an alkylamino group, and polymers of pyrrole and polymers of pyrrole derivatives having an alkylamino group are preferred.

[0022] Examples of pyrrole derivatives having an alkylamino group include 1-methylpyrrole, 2-methylpyrrole, 3-methylpyrrole, 2-bromo-3-methylpyrrole, 1-ethylpyrrole, 2-ethylpyrrole, 3-ethylpyrrole, 1-propylpyrrole, 2-propylpyrrole, 3-propylpyrrole, 1-butylpyrrole, 2-butylpyrrole, 3-butylpyrrole, 1-pentylpyrrole, 2-pentylpyrrole, 3-pentylpyrrole, 1-hexylpyrrole, 2-hexylpyrrole, 3-hexylpyrrole, 3,4-dimethylpyrrole, and 3,4-dibutylpyrrole, all of which have an alkylamino group.

[0023] For example, examples of π-conjugated polymers or oligomers having an alkylamino group containing a pyrrole derivative include π-conjugated polymers or oligomers represented by the following general formula:

[0024] [ka]

[0025] In the above formula, n and m are natural numbers. The carbon number m is not particularly limited, but can be, for example, 1 to 15, and the alkyl chain may be linear or branched.

[0026] For example, the following π-conjugated polymers or oligomers may be mentioned:

[0027] [ka]

[0028] In each of the above chemical formulas, n is a natural number.

[0029] Furthermore, examples of thiophene derivatives having an alkylamino group include 2-methylthiophene, 3-methylthiophene, 2-bromo-3-methylthiophene, 2-ethylthiophene, 3-ethylthiophene, 2-propylthiophene, 3-propylthiophene, 2-butylthiophene, 3-butylthiophene, 2-pentylthiophene, 3-pentylthiophene, 2-hexylthiophene, 3-hexylthiophene, 3,4-dimethylthiophene, and 3,4-dibutylthiophene, each of which has an alkylamino group.

[0030] For example, examples of π-conjugated polymers or oligomers having an alkylamino group containing a thiophene derivative include π-conjugated polymers or oligomers in which an alkylamino group is added to a repeating unit of a π-conjugated polymer or oligomer, such as those represented by the following general formula:

[0031] [ka]

[0032] In the above general formula, n, m, and l are natural numbers. The carbon numbers l and m are not particularly limited, but can be, for example, 1 to 15, and the alkyl chain may be linear or branched.

[0033] For example, the following π-conjugated polymers or oligomers may be mentioned:

[0034] [ka]

[0035] [ka]

[0036] In each of the above chemical formulas, n is a natural number.

[0037] In addition to the above-described π-conjugated polymers or oligomers in which an alkylamino group is added to the repeating unit, those in which an alkylamino group is added to each thiophene ring can also be used. For example, π-conjugated polymers or oligomers represented by the following general formula can be mentioned. [ka]

[0038] In the above formula, n and l are natural numbers. The carbon number l is not particularly limited, but can be, for example, 1 to 15, and the alkyl chain may be linear or branched.

[0039] For example, the following π-conjugated polymers or oligomers may be mentioned:

[0040] [ka]

[0041] [ka]

[0042] In each of the above chemical formulas, n is a natural number.

[0043] In this way, by using a π-conjugated polymer or oligomer having an alkylamine or alkylamino group, it becomes possible to provide light absorption and carrier transport properties, and also to stabilize the perovskite layer by the alkylamino group.

[0044] Examples of halogens constituting this hydrohalide aqueous solution include bromine, chlorine, and iodine. Bromine is preferred as a constituent element in terms of high stability, and for example, an aqueous solution of methylamine hydrobromide (CHNHBr) or ethylamine hydrobromide (CHNHBr) can be used. Furthermore, iodine is preferred as a constituent element in terms of the balance between achieving a high open-circuit voltage (Voc) when used in solar cells and covering a wide absorption edge range up to the visible light region, and for example, an aqueous solution of methylamine hydroiodide (CHNHI) or ethylamine hydroiodide (CHNHI) can be used.

[0045] (Manufacturing method) The lead halide perovskite can be produced by immersing lead halide in an aqueous solution of a hydrohalide salt of a π-conjugated polymer or oligomer having an alkylamine or alkylamino group.

[0046] The lead halide used as the raw material is not particularly limited, but lead bromide (PbBr2) or lead iodide (PbI2) can be used, and the form of the lead halide may be powder or thin film depending on the application.

[0047] The concentration of the hydrohalide aqueous solution is not particularly limited, but from the viewpoint of increasing durability against water, it is preferably at least 0.1 M or more, and more preferably 0.1 M or more and not more than the saturated concentration.

[0048] In this way, a lead halide perovskite is obtained in which the components of the aqueous solution of the hydrohalide salt of the π-conjugated polymer or oligomer having an alkylamine or alkylamino group remain.

[0049] The obtained lead halide perovskite can be used to obtain a photoelectric conversion element.

[0050] A solar cell can be manufactured using a photoelectric conversion element that uses this lead halide perovskite. In particular, this lead halide perovskite can be used to manufacture a solar cell in the presence of water (aqueous solution system) due to the remaining components of an aqueous solution of a hydrohalide salt of a π-conjugated polymer or oligomer having an alkylamine or alkylamino group.

[0051] Thus, by using the lead halide-based perovskite according to this embodiment, it is possible to obtain a solar cell in the presence of water (aqueous system), which was previously impossible. Although the mechanism behind this excellent property has not yet been elucidated in detail, it is presumed that as the concentration of the hydrohalide salt aqueous solution increases, a driving force is generated that suppresses the progress of dissolution of the lead halide-based perovskite in water.

[0052] (Second embodiment) In a second embodiment of the present invention, a different lead halide perovskite is produced by ion exchange using the lead halide perovskite according to the first embodiment.

[0053] By utilizing the fact that lead bromide-based perovskite is converted to lead iodide-based perovskite when reacted with an electrolyte solution, solar cells can be manufactured by combining a lead bromide-based perovskite thin film (e.g., (CH3NH3)PbBr3) with an aqueous solution of methylamine hydroiodide (CH3NH3I).

[0054] Thus, by using the lead halide-based perovskite according to this embodiment, it is possible to obtain a solar cell in the presence of water (aqueous system) through reaction with an electrolyte solution, which was previously impossible. Although the mechanism behind this excellent property has not yet been elucidated in detail, it is presumed that as the concentration of the hydrohalide salt aqueous solution increases, a driving force is generated that suppresses the progress of dissolution of the lead halide-based perovskite in water.

[0055] Examples will be given below to illustrate the features of the present invention more specifically, but the present invention is not limited to the following examples.

[0056] Example 1 (1) Dripping of saturated aqueous solution of methylamine hydrobromide A saturated aqueous solution of methylamine hydrobromide (CH3NH3Br) was added dropwise to lead bromide (manufactured by Kojundo Chemical Laboratory) at room temperature. This methylamine hydrobromide (CH3NH3Br) was synthesized by reacting methylamine (manufactured by Tokyo Chemical Industry Co., Ltd.) with hydrobromide. As shown in Figure 1, methylammonium lead bromide (CH3NH3)PbBr3 was obtained as orange crystals from the white lead bromide (PbBr2).

[0057] (1-1) Reflection spectrum The obtained crystal was analyzed using a reflectance spectrum measuring device (Ocean Optics S2000), and the results are shown in Figure 2. The results in Figure 2 confirm that the reflectance of the obtained crystal, methylammonium lead bromide (CH3NH3)PbBr3 (shown as MAPbBr3 in the figure), at wavelengths shorter than the band gap was significantly reduced.

[0058] (1-2) X-ray diffraction The obtained crystals were analyzed using an X-ray diffractometer (Shimadzu XRD-7000S), and the results are shown in Figure 3. From the results in Figure 3, diffraction peaks due to the lead bromide-based perovskite structure were observed in the diffraction peaks of the obtained crystals, methylammonium lead bromide (CH3NH3)PbBr3 (shown as MAPbBr3 in the figure).

[0059] From the above measurement results, it was confirmed that the obtained methylammonium lead bromide (CH3NH3)PbBr3 has indeed formed a lead bromide-based perovskite structure.

[0060] (1-3)Time dependence of (100) plane diffraction peak Furthermore, the time dependence was analyzed by detecting the change over time in the (100) plane diffraction peak using the above-mentioned X-ray diffractometer, and the results are shown in Figure 4. The results in Figure 4 confirm that the perovskite structure was almost completely formed within one minute after the dropwise addition of the methylamine hydrobromide (CH3NH3Br) aqueous solution.

[0061] (1-4) Water resistance The obtained lead bromide-based perovskite, methylammonium lead bromide (CH3NH3)PbBr3, was immersed in a 0.1M methylamine hydrobromide aqueous solution and pure water, and the results are shown in Figure 5. The results in Figure 5 confirmed that the lead bromide-based perovskite, methylammonium lead bromide (CH3NH3)PbBr3, formed a hydrate in pure water, as shown in the following reaction formula (X is a bromine atom).

[0062] [ka]

[0063] It was confirmed that methylammonium lead bromide (CH3NH3)PbBr3, a lead bromide-based perovskite, does not dissolve in a 0.1M aqueous solution of methylamine hydrobromide, as shown in the following reaction equation (X is a bromine atom). Similarly, it was confirmed that methylammonium lead bromide (CH3NH3)PbBr3 does not form a hydrate in an aqueous solution of methylamine hydrobromide at a concentration of 0.1M or higher.

[0064] [ka]

[0065] Example 2 A saturated aqueous solution of methylamine hydroiodide (CH3NH3I) was added dropwise to lead iodide, resulting in lead iodide perovskite, a lead halide perovskite. (2) Dripping of saturated aqueous solution of methylamine hydroiodide A saturated aqueous solution of methylamine hydroiodide (CH3NH3I) was added dropwise to lead iodide (PbI2) (manufactured by Kojundo Chemical Laboratory) at room temperature. This methylamine hydroiodide (CH3NH3I) was synthesized by reacting methylamine (manufactured by Tokyo Chemical Industry Co., Ltd.) with hydroiodide. As shown in Figure 6, methylammonium lead iodide (CH3NH3)PbI3 was obtained as black crystals from the yellow lead iodide (PbI2).

[0066] (2-1) Reflection spectrum The obtained crystal was analyzed using a reflectance spectrum measuring device (Ocean Optics S2000), and the results are shown in Figure 7. The results in Figure 7 confirm that the reflectance of the obtained crystal, methylammonium lead iodide (CH3NH3)PbI3 (shown as MAPbI3 in the figure), on the shorter wavelength side than the band gap was significantly reduced.

[0067] (2-2) X-ray diffraction The obtained crystals were analyzed using an X-ray diffractometer (Shimadzu XRD-7000S), and the results are shown in Figure 8. From the results in Figure 8, diffraction peaks due to the lead iodide-based perovskite structure were observed in the diffraction peaks of the obtained crystals, methylammonium lead iodide (CH3NH3)PbI3 (shown as MAPbI3 in the figure).

[0068] The above measurement results confirmed that a lead iodide perovskite structure was indeed formed in the obtained methylammonium lead iodide (CH3NH3)PbI3.

[0069] (2-3) Water resistance The obtained lead bromide-based perovskite, methylammonium lead iodide (CH3NH3)PbI3, was immersed in a 0.1M methylamine hydroiodide aqueous solution and pure water, and the results are shown in Figure 9. The results in Figure 9 confirmed that the lead iodide-based perovskite, methylammonium lead iodide (CH3NH3)PbI3, formed a hydrate in pure water, as shown in the following reaction formula (X is an iodine atom):

[0070] [ka]

[0071] It has been confirmed that methylammonium lead iodide (CH3NH3)PbI3, a lead iodide-based perovskite, does not form a hydrate in a 0.1 M methylamine hydroiodide aqueous solution, as shown in the following reaction formula (X is an iodine atom). Similarly, it has also been confirmed that methylammonium lead iodide (CH3NH3)PbI3 does not form a hydrate in a methylamine hydroiodide aqueous solution with a concentration of 0.1 M or higher. In Example 3 described below, it has been confirmed that hydrates do not form in a saturated methylamine hydroiodide aqueous solution with a concentration of 0.1 M or higher.

[0072] [ka]

[0073] Example 3 (3) Fabrication of solar cells A solar cell was fabricated using methylammonium lead bromide (CH3NH3)PbBr3, which is the lead bromide-based perovskite obtained in Example 1, and a saturated aqueous solution of methylamine hydroiodide (CH3NH3I) as an electrolyte solution.

[0074] As shown in Figure 10(a), the solar cell was fabricated with a layered structure consisting of a Pt (cathode) and an ITO (anode) sandwiched between them, from the Pt (cathode) side, an electrolyte solution consisting of a 50 mM saturated aqueous solution of methylamine hydroiodide (CH3NH3I), a perovskite layer (light absorption layer) consisting of methylammonium lead bromide (CH3NH3)PbBr3, a lead bromide-based perovskite, and a TiO2 compact layer, with a glass substrate underneath the ITO (anode). The TiO2 compact layer was fabricated by spin-coating a thin film of an isopropanol solution of titanium diisopropoxide bisacetylacetonate (titanium complex) onto the substrate and heat-treating it at 120°C or higher.

[0075] Methylammonium lead bromide (CH3NH3)PbBr3 deposited as a perovskite layer (light absorption layer) underwent ion exchange between bromide ions and iodide ions in a saturated aqueous solution of methylamine hydroiodide (CH3NH3I), which was an electrolyte solution, and was converted into methylammonium lead iodide (CH3NH3)PbI3, a lead iodide-based perovskite. This was confirmed by reflection spectroscopy and X-ray diffraction, as in Example 2 above.

[0076] [ka]

[0077] Furthermore, as shown in Figure 10(b), it was confirmed that after immersion in a saturated aqueous solution of methylamine hydroiodide (CH3NH3I), an electrolyte solution, methylammonium lead bromide (CH3NH3)PbBr3 indeed exhibited the black color characteristic of methylammonium lead iodide (CH3NH3)PbI3, a lead iodide-based perovskite.

[0078] (3-1) Photoelectric conversion characteristics The photoelectric conversion characteristics of the fabricated solar cell were measured using measuring equipment (Ushio Inc. Solar Simulator X500 and Agilent Inc. Semiconductor Analyzer B1500A), and the results are shown in Figure 11. The measurement conditions were a voltage (open circuit voltage) (Voc) of 1.32 V at which the external current becomes 0 A, and a current (short circuit current) (Jsc) at which the external voltage becomes 0 V, of 1.25 mA. The results in Figure 11 confirmed that photoelectric conversion characteristics can be obtained with a solar cell efficiency η = V·I / P, confirming the potential for practical application of perovskite solar cells fabricated in an aqueous solution system from methylammonium lead bromide (CH3NH3)PbBr3.

Claims

1. The perovskite layer is composed of an alkylammonium lead bromide and an electrolyte solution of alkylammonium iodide, and the alkylammonium lead iodide is formed by ion exchange between the bromide ions and iodide ions contained in the alkylammonium lead bromide and the alkylammonium iodide, and contains the alkylammonium lead iodide as a lead halide-based perovskite. Solar cell.

2. The solar cell according to claim 1 , The alkyl group constituting the alkylammonium is selected from the group consisting of a substituted or unsubstituted methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, an isopropyl group, a diethyl group, a dibutyl group, a diisopropylmethyl group, a triethyl group, and a tributyl group. Solar cell.

3. The solar cell according to claim 1 or 2, Methylammonium lead bromide ((CH ３ NH ３ ) PbBr ３ ) and a perovskite layer consisting of methylammonium iodide (CH ３ NH ３ and an electrolyte solution consisting of methylammonium lead bromide and methylammonium iodide ((CH ３ NH ３ ) PbI ３ ) as a lead halide-based perovskite Solar cell.

4. A perovskite layer made of alkylammonium lead bromide and an electrolyte solution made of alkylammonium iodide are subjected to ion exchange between bromide ions and iodide ions contained in the alkylammonium lead bromide and the alkylammonium iodide, thereby obtaining alkylammonium lead iodide, which is a lead halide-based perovskite, in the perovskite layer, while the electrolyte solution remains. How solar cells are manufactured.

5. The method for manufacturing a solar cell according to claim 4, The alkyl group constituting the alkylammonium is selected from the group consisting of a substituted or unsubstituted methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, an isopropyl group, a diethyl group, a dibutyl group, a diisopropylmethyl group, a triethyl group, and a tributyl group. How solar cells are manufactured.

6. The method for manufacturing a solar cell according to claim 4 or 5, Methylammonium lead bromide ((CH ３ NH ３ ) PbBr ３ ) and a perovskite layer consisting of methylammonium iodide (CH ３ NH ３ Ion exchange occurs between bromide ions and iodide ions contained in the methylammonium lead bromide and the methylammonium iodide constituting the electrolyte solution consisting of lead halide perovskite, methylammonium lead iodide (CH ３ NH ３ PbI ３ ) is obtained in the perovskite layer, and the electrolyte solution remains. How solar cells are manufactured.

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