Method for manufacturing solar cells and solar modules, as well as solar cells and solar modules

Abstract

The present invention provides a method for manufacturing solar cells and solar modules that can improve durability and conversion efficiency, as well as solar cells and solar modules. [Solution] A method for manufacturing a solar cell 10 includes the steps of forming an electron transport layer 3 on a first electrode 2, forming a perovskite compound light absorption layer 4 on the electron transport layer 3, forming a hole transport layer 5 on the light absorption layer 4, and forming a second electrode 6 on the hole transport layer 5. The step of forming the hole transport layer 5 and / or the step of forming the electron transport layer 3 includes a buffer layer formation step of forming buffer layers 31 and 51 between the hole transport layer 5 and the light absorption layer 4, and / or between the electron transport layer 3 and the light absorption layer 4. The buffer layer formation step involves adding a solution containing a polyamino acid obtained by polymerizing amino acids having charged side chains of reactive functional groups.

Description

Technical Field

[0001] The present disclosure relates to a solar cell and a solar cell module including a light absorption layer of a perovskite compound, and methods for manufacturing the same.

Background Art

[0002] Conventionally, a solar cell has been disclosed in which a specific organic compound is applied to a charge transport layer between an electrode and a light absorption layer having a perovskite crystal structure.

[0003] For example, Patent Document 1 discloses a perovskite film layer capable of effectively improving the efficiency of a perovskite light-emitting device, which is composed of a layer of perovskite crystal particles that are discontinuous and irregularly distributed, and a low-refractive-index organic insulating layer embedded between the perovskite crystal particles, and includes a multilayer thin film modified with an amino acid-based organic substance or a polyamine-based organic substance in a charge transport layer that binds or reacts with the organic insulating layer.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the amino acid-based organic materials and polyamine-based organic materials disclosed in Patent Document 1 were insufficient to exhibit and maintain stable performance as a charge transport layer. Specifically, in the case of amino acid-based organic materials, the amino groups are used during the formation of the charge transport layer, making it impossible to increase the amine accumulation necessary for stable performance as a charge transport layer. Furthermore, although the functional groups of amino acids are used to bond with each other, the bonding occurs at the amino acid level, making it difficult to obtain sufficient density as a thin film structure to prevent the penetration of water molecules into the light absorption layer. In the case of polyamine-based organic materials, although efforts have been made to improve the density of the charge transport layer itself through polymerization, the polymer is based on allylamine as the unit, and amine accumulation necessary for stable performance as a charge transport layer has not been considered.

[0006] Therefore, this disclosure provides a solar cell and solar cell module that can improve durability as a charge transport layer and exhibit stable performance. [Means for solving the problem]

[0007] A method for manufacturing a solar cell according to one aspect of the present disclosure includes the steps of: forming an electron transport layer on a first electrode; forming a light-absorbing layer of a perovskite compound on the electron transport layer; forming a hole transport layer on the light-absorbing layer; and forming a second electrode on the hole transport layer; or the method includes the steps of: forming a hole transport layer on a second electrode; forming a light-absorbing layer of a perovskite compound on the hole transport layer; forming an electron transport layer on the light-absorbing layer; and forming a first electrode on the electron transport layer, wherein the step of forming the hole transport layer and / or the step of forming the electron transport layer comprises a buffer layer forming step of forming a buffer layer between the hole transport layer and the light-absorbing layer and / or between the electron transport layer and the light-absorbing layer, and the buffer layer forming step is characterized by adding a solution containing a polyamino acid obtained by polymerizing an amino acid having a charged side chain of a reactive functional group.

[0008] A method for manufacturing a solar cell according to one aspect of the present disclosure includes the steps of forming an electron transport layer on a first electrode, forming a light-absorbing layer of a perovskite compound on the electron transport layer, forming a hole transport layer on the light-absorbing layer, and forming a second electrode on the hole transport layer, or the steps of forming a hole transport layer on a second electrode, forming a light-absorbing layer of a perovskite compound on the hole transport layer, forming an electron transport layer on the light-absorbing layer, and forming a first electrode on the electron transport layer, wherein the step of forming the hole transport layer and / or the step of forming the electron transport layer is characterized by adding a solution containing a polyamino acid obtained by polymerizing amino acids having charged side chains of reactive functional groups.

[0009] A method for manufacturing a solar cell module according to one aspect of this disclosure is characterized by integrating and modularizing solar cells manufactured by a method for manufacturing solar cells.

[0010] A solar cell according to one aspect of this disclosure has a charge transport layer, which is made up of a hole transport layer or an electron transport layer, between the electrode and the light-absorbing layer of the perovskite compound. (1) A buffer layer between the light absorption layer and the charge transport layer, or (2) The composition of the charge transport layer is as follows: The present invention is characterized by containing an organic compound having a polymer structure of an amino acid having at least one charged side chain of a reactive functional group.

[0011] A solar cell module according to one aspect of this disclosure is characterized in that solar cells are integrated and modularized. [Effects of the Invention]

[0012] According to this disclosure, it is possible to improve the durability of solar cells. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is a schematic cross-sectional view of a solar cell according to the first embodiment of this product. [Figure 2] Figure 2 is a schematic cross-sectional view of a solar cell according to the second embodiment of the present implementation. [Figure 3] Figure 3 is a schematic cross-sectional view of a solar cell according to the third embodiment of the present implementation. [Figure 4] Figure 4 is a schematic cross-sectional view of a solar cell according to the fourth embodiment of the present implementation. [Figure 5] Figure 5 is a schematic cross-sectional view of a solar cell according to the fifth embodiment of the present implementation. [Figure 6] Figure 6 is a schematic cross-sectional view of a solar cell according to the sixth embodiment of the present implementation. [Figure 7] Figure 7 is a schematic cross-sectional view of a solar cell according to the seventh embodiment of the present implementation. [Figure 8] Figure 8 is a schematic cross-sectional view of a solar cell according to the eighth embodiment of the present implementation. [Figure 9] Figure 9 is a schematic cross-sectional view of a solar cell according to the ninth embodiment of the present implementation. [Figure 10] Figure 10 is a schematic cross-sectional view of a solar cell according to the tenth embodiment of the present implementation. [Figure 11] Figure 11 is a schematic cross-sectional view of a solar cell according to the eleventh embodiment of the present implementation. [Figure 12] Figure 12 is a schematic cross-sectional view of a solar cell according to the twelfth embodiment of the present implementation. [Figure 13] Figure 13 is a schematic cross-sectional view of a solar cell according to the thirteenth embodiment of the present implementation. [Figure 14] Figure 14 is a schematic cross-sectional view of a solar cell according to the fourteenth embodiment of the present implementation. [Figure 15] Figure 15 is a schematic cross-sectional view of a solar cell according to the fifteenth embodiment of the present implementation. [Figure 16] Figure 16 is a schematic cross-sectional view of a solar cell according to the sixteenth embodiment of the present implementation. [Figure 17] Figure 17 is a schematic cross-sectional view of a solar cell module including the solar cell according to the present embodiment. [Figure 18]Figure 18 is a schematic cross-sectional view of a solar cell module equipped with a solar cell according to this embodiment (modified example 1). [Figure 19] Figure 19 is a schematic cross-sectional view of a solar cell module equipped with a solar cell according to this embodiment (modified example 2). [Figure 20] Figure 20 is a diagram that superimposes a schematic cross-sectional view of one solar cell included in the solar cell module shown in Figure 17 with the equivalent circuit of the solar cell. [Figure 21] Figure 21 shows the equivalent circuit of a solar cell module. [Modes for carrying out the invention]

[0014] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the embodiments described below are not intended to unnecessarily limit the content of the present disclosure as described in the claims, and not all configurations described in these embodiments are necessarily essential as solutions of the present disclosure. Furthermore, for illustrative purposes, the light-receiving side is represented as the lower side and the side opposite the light-receiving side as the upper side; however, this is for convenience only and does not relate to the orientation of installation or the recommended orientation of installation. The invention can be applied even if the top and bottom are reversed, as long as there is no contradiction. In other words, the invention holds true as long as there is no contradiction in swapping the arrangement of the light-receiving side and the side opposite the light-receiving side. Also, in the case of a single-sided light-receiving solar cell, the light-receiving side refers directly to the side on which light enters the solar cell. However, in the case of a double-sided light-receiving solar cell, either one side can be considered the light-receiving side, and furthermore, if the configuration of the present disclosure exists when at least one side is considered the light-receiving side, it can be considered to fall within the technical scope of the present disclosure. In other words, even if one side does not have the configuration of the disclosure when considered as the light-receiving side, if the other side has the configuration of the disclosure when considered as the light-receiving side, it can be considered to fall within the technical scope of the disclosure. In the following description, unless otherwise specified, identical parts are given the same reference numerals, and their names and functions are also the same. Therefore, detailed descriptions of them will not be repeated.

[0015] 1. Solar cell <First Embodiment> Figure 1 is a schematic cross-sectional view of a solar cell 10 according to this embodiment. As shown in Figure 1, the solar cell 10 according to this embodiment includes a substrate 1. The solar cell 10 also includes a first electrode 2, an electron transport layer 3 formed on the first electrode 1, a light absorption layer 4 formed on the electron transport layer 3, a hole transport layer 5 formed on the light absorption layer 4 via a buffer layer 51, and a second electrode 6 formed on the hole transport layer 5. The first electrode 2 is in contact with the electron transport layer 3, the electron transport layer 3 is in contact with the light absorption layer 4, the light absorption layer 4 is in contact with the hole transport layer 5 via the buffer layer 51, and the hole transport layer 5 is in contact with the second electrode 6. Each component will be described in detail below. In this embodiment, the first electrode 2 is in contact with the electron transport layer 3, the electron transport layer 3 is in contact with the light absorption layer 4, the light absorption layer 4 is in contact with the hole transport layer 5 via the buffer layer 51, and the hole transport layer 5 is in contact with the second electrode 6. However, this does not exclude cases where the electrodes are not in contact with each other, or where other layers are interposed between them.

[0016] [Base] The substrate 1 is the substrate of the solar cell 10, and is the same as or includes a substrate or base material. In this embodiment, the case where it is made of a transparent material is described, but the side of the solar cell 10 opposite to the substrate side may be made of a transparent material, or both sides may be made of a transparent material. It is preferable that the substrate 1 is a transparent substrate. The substrate 1 is placed on the light-receiving side of the solar cell 10 (also called the light-receiving side, including the part into which light is incident, as is the case in this disclosure). The substrate 1 is also connected to the first electrode 2. Note that connection means physical direct contact. Furthermore, transparency or light transmittance means that light is transmitted, but this does not exclude anything that reflects or absorbs light even a little, and it is sufficient that it is provided on the light-receiving side of the solar cell 10 and transmits light appropriately, and can be considered synonymous with being provided on the light-receiving side of the solar cell 10, and therefore, it can be said to be transparent if it is provided at least on the light-receiving side of the solar cell 10. In other words, a transparent substrate means a substrate provided on the light-receiving side of the solar cell 10.

[0017] For example, the substrate 1 can be made of plastics such as PET or polyimide, or glass. By using a flexible substrate 1, the solar cell 10 itself can be made flexible.

[0018] If the substrate 1 is made of a transparent resin such as an organic film, the solar cell 10 may have a barrier layer (not shown) on the substrate 1. This prevents moisture and other substances from penetrating the light-absorbing layer 4. The barrier layer may be provided, for example, between the substrate 1 and the first electrode 2.

[0019] The substrate 1 may have a thickness of approximately 50 μm to 5000 μm.

[0020] [1st electrode] The first electrode 2 is a conductive material. For example, a transparent conductive film is used. 2 is a conductive film on the light-receiving surface side of the solar cell 10. Examples of materials constituting the first electrode 2 include transparent conductive materials (particularly transparent conductive oxides (TCO)) and opaque conductive materials. Examples of transparent conductive materials include indium tin oxide (ITO), tin oxide (SnO2), fluorine-doped tin oxide (FTO), aluminum-doped zinc oxide (AZO), indium zinc oxide (IZO), and gallium-doped zinc oxide (GZO). The film may be formed by known methods, such as sputtering, CVD, or vapor deposition. The film thickness of the first electrode 2 should be, for example, 30 nm to 1000 nm. A transparent conductive material is a material that, even if it has a certain thickness and its physical properties are opaque, can become transparent depending on the thickness of the material, and therefore can be used as a conductive film on the light-receiving surface side of the solar cell 10. Note that the term "layer" or "film" does not specify thickness or width, but also includes patterned or island-shaped layers or layers with different thicknesses. Furthermore, the layer or film preferably has a substantially constant thickness. Unless otherwise specified, "subject to" or "to a certain extent" means that variations within the range of manufacturing tolerances are acceptable, and preferentially, variations of plus 15% and minus 15% of that value are acceptable. Unless otherwise specified in this disclosure, confirmation of thickness, width, etc. is performed by cross-sectional observation. For example, observation by SEM is performed in a single 400nm wide cross-sectional SEM image, and it is sufficient if the thickness and width can be confirmed within that range; it is not necessary to confirm in all cross-sections. In other words, "subject to constant thickness" means that the thickness in a single 400nm wide cross-sectional SEM image falls within a range of plus 15% and minus 15% of the average thickness. The transparent conductive film does not necessarily have to be transparent. That is, if there is even a part of the solar cell 10 that is transparent, the photoelectric conversion function is guaranteed, and the conductive film does not necessarily have to be transparent.

[0021] The first electrode 2 is provided on the substrate 1 and connected to the electron transport layer 3.

[0022] [Electron transport layer] The electron transport layer 3 has the function of transporting electrons generated in the light absorption layer 4. For example, it transports electrons generated in the light absorption layer 4 to the first electrode 2. Furthermore, it is preferable that the electron transport layer 3 also has the function of blocking holes generated in the light absorption layer 4. The electron transport layer 3 naturally has this function as long as it is positioned between the first electrode 2 and the light absorption layer 4 of the solar cell 10, and as long as it is positioned between the first electrode 2 and the light absorption layer 4 and the solar cell 10 is functioning, it is not necessary to confirm this function. It is preferable that the electron transport layer 3 contains a material that facilitates the transfer of electrons generated in the light absorption layer 4 to the first electrode 2. Note that a hole blocking layer can also be used instead of the electron transport layer.

[0023] The electron transport layer 3 can be made of, for example, tin oxide, titanium oxide, zinc oxide, etc. The layer thickness can be, for example, 10 nm to 200 nm, but is not limited to this. It can be deposited by known methods. For example, sputtering, die coating, screen printing, etc. can be used.

[0024] [Light-absorbing layer] The light-absorbing layer 4 is a layer that absorbs light and generates electrons and holes. It is desirable that the light-absorbing layer 4 contains a perovskite compound. The thickness of the light-absorbing layer 4 is preferably 500 nm to 2 μm, and more preferably 400 nm to 600 nm. It should be noted that the light-absorbing layer 4 absorbs light and generates electrons and holes, as long as the solar cell functions as a solar cell; this is self-evident and does not require verification. As long as the material containing a light-absorbing component is present, it can be assumed that the light-absorbing layer 4 absorbs light and generates electrons and holes.

[0025] The perovskite compound contained in the light-absorbing layer 4 is preferably composed of a compound (perovskite compound) represented by the general formula: ABX3···(1). However, while the composition ratio of each is preferably 1:1:3, it is not necessarily 1:1:3, the content of each element may be adjusted as appropriate, and each constituent element does not need to be of only one type. As long as the light-absorbing layer has a photoelectric conversion function, it has the degree of freedom of composition as described. In general formula (1), A is an organic molecule (including an organic group or organic cation) or an inorganic atom or molecule (including an inorganic group or inorganic cation) or a combination thereof, B is a metal atom or molecule (including a metal cation), and X is a halogen atom or molecule or a chalcogen atom or molecule (including a halogen anion or chalcogen anion). In general formula (1), the three Xs may be the same or different from each other.

[0026] Perovskite compounds, by being contained in a light-absorbing layer, can absorb light and convert it into electricity, and this should be taken into consideration. In other words, it is sufficient to know that a compound is a perovskite compound if it contains, for example, organic molecules, metal atoms, and halogen atoms. Furthermore, it is sufficient to know that a compound is a perovskite compound if elements corresponding to A, B, and X are detected, insofar as the light-absorbing layer has a photoelectric conversion function. For example, molecules containing carbon, nitrogen, and hydrogen are suitable as organic molecules, and therefore, it is sufficient to know that carbon, nitrogen, hydrogen, metal elements, and halogen elements or chalcogen elements are detected. Alternatively, it is sufficient to know that a compound is a perovskite compound if it contains A, B, and X, for example, if it contains inorganic atoms, metal atoms, and halogen atoms. Furthermore, it is sufficient to know that a compound is a perovskite compound if elements corresponding to A, B, and X are detected, insofar as the light-absorbing layer has a photoelectric conversion function. For example, cesium or rubidium are suitable as inorganic atoms, and therefore, it is sufficient to know that cesium or rubidium, metal elements, and halogens or chalcogens are detected. Furthermore, the fact that it is a perovskite compound is based on the natural consequence that the light-absorbing layer 4 must have a crystalline structure in order to have a photoelectric conversion function; therefore, confirmation of the presence of a crystalline structure is not required. The light-absorbing layer 4 may contain materials other than perovskite compounds.

[0027] The light-absorbing layer 4 may contain an organic-inorganic hybrid compound. An organic-inorganic hybrid compound means a compound containing both an inorganic material and an organic material. A solar cell using a perovskite compound, which is an organic-inorganic hybrid compound, is also called an organic-inorganic hybrid solar cell. "Organic" typically refers to a material composed of multiple carbon atoms. However, carbon materials such as graphite, graphene, carbon nanowires, carbon nanofibers, carbon nanotubes, and carbon or carbon black that function as electrodes are not specifically considered organic. In other words, organic refers to anything that has multiple carbon atoms as one of its constituent elements, excluding the aforementioned carbon materials such as graphite. "Inorganic" means something that is not organic. In other words, an organic-inorganic hybrid compound means a material that contains multiple carbon atoms as one of its constituent elements, and also contains materials that do not have multiple carbon atoms as a constituent element, such as metal atoms, halogen atoms, or chalcogen atoms.

[0028] Examples of organic molecules represented by A in general formula (1) include alkylamines, alkylammonium compounds, and nitrogen-containing heterocyclic compounds. In perovskite compound (1), the organic molecule represented by A may be only one type of organic molecule, or it may be two or more types of organic molecules.

[0029] Examples of alkylamines include methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, dihexylamine, trimethylamine, triethylamine, tripropylamine, tributylamine, tripentylamine, trihexylamine, ethylmethylamine, methylpropylamine, butylmethylamine, methylpentylamine, hexylmethylamine, ethylpropylamine, and ethylbutylamine.

[0030] Alkylammonium compounds are ionized compounds of the alkylamines mentioned above. Examples of alkylammonium compounds include methylammonium (CH3NH3), ethylammonium, propylammonium, butylammonium, pentylammonium, hexylammonium, dimethylammonium, diethylammonium, dipropylammonium, dibutylammonium, dipentylammonium, dihexylammonium, trimethylammonium, triethylammonium, tripropylammonium, tributylammonium, tripentylammonium, trihexylammonium, ethylmethylammonium, methylpropylammonium, butylmethylammonium, methylpentylammonium, hexylmethylammonium, ethylpropylammonium, and ethylbutylammonium.

[0031] Examples of nitrogen-containing heterocyclic compounds include imidazole, azole, pyrrole, aziridine, azirine, azetidine, azeto, azole, imidazoline, and carbazole. The nitrogen-containing heterocyclic compound may also be an ionized compound. Phenethylammonium is preferred as the ionized nitrogen-containing heterocyclic compound.

[0032] In general formula (1), the organic molecule represented by A is preferably methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, methylammonium, ethylammonium, propylammonium, butylammonium, pentylammonium, hexylammonium, or phenethylammonium, more preferably methylamine, ethylamine, propylamine, methylammonium, ethylammonium, or propylammonium, and even more preferably methylammonium.

[0033] In general formula (1), examples of metal atoms represented by B include lead, tin, zinc, titanium, antimony, bismuth, nickel, iron, cobalt, silver, copper, gallium, germanium, magnesium, calcium, indium, aluminum, manganese, chromium, molybdenum, and europium. In perovskite compounds, the metal atom represented by B may be only one type of metal atom, or it may be two or more types of metal atoms. From the viewpoint of improving the light absorption characteristics and charge generation characteristics of perovskite compounds, the metal atom represented by B is preferably a lead atom.

[0034] In general formula (1), examples of halogen atoms represented by X include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms. In a perovskite compound, the halogen atom represented by X may be one type of halogen atom or two or more types of halogen atoms. From the viewpoint of narrowing the energy band gap of the perovskite compound, the halogen atom represented by X is preferably an iodine atom. More specifically, it is preferable that at least one of the three Xs represents an iodine atom, and more preferably that all three Xs represent iodine atoms.

[0035] As the perovskite compound, it is preferable to use a compound represented by the general formula "CH3NH3PbX3 (where X represents a halogen atom)", and more preferably to use CH3NH3PbI3. By using a compound represented by the general formula "CH3NH3PbX3" (especially CH3NH3PbI3) as the perovskite compound, conduction electrons and holes can be generated more efficiently in the perovskite compound, and as a result, the conversion efficiency of the solar cell 10 can be further improved.

[0036] Furthermore, the perovskite layer includes a perovskite material in which the energy level of the upper valence band (VBM) is in the range of -5.1 eV to -5.7 eV, and the energy level of the lower conduction band (CBM) is in the range of -3.5 eV to -4.0 eV. Such a perovskite layer can be suitably used in the solar cell 10 according to this embodiment. Here, the reason why the energy levels of the upper valence band and the lower conduction band are negative is that the vacuum level is set to 0 and the energy levels below the vacuum level are expressed as negative. However, in actual measurements, electron affinity and ionization energy will be measured. Therefore, the absolute value of the difference between the vacuum level and the energy level at the bottom of the conduction band can be rephrased as electron affinity (or its absolute value), and the absolute value of the difference between the vacuum level and the energy level at the top of the valence band can be rephrased as ionization potential (or its absolute value). Here, the energy levels at the bottom of the conduction band and the top of the valence band are generally expressed as deep and shallow to indicate upper and lower. "Deep" for the energy levels at the bottom of the conduction band and the top of the valence band means that the corresponding electron affinity or ionization energy is large or far from the vacuum level, and "shallow" for the energy levels at the bottom of the conduction band and the top of the valence band means that the corresponding electron affinity or ionization energy is small or close to the vacuum level.

[0037] [Hole transport layer] The hole transport layer 5 has the function of transporting holes generated in the light absorption layer 4. Here, for example, the hole transport layer 5 transports holes to the second electrode 6. Furthermore, it is preferable that the hole transport layer 5 also has the function of blocking electrons generated in the light absorption layer 4. The hole transport layer 5 naturally has the function of hole transport as long as it is positioned between the light absorption layer 4 and the second electrode 6 of the solar cell 10, and as long as it is positioned on the hole transport side and the solar cell 10 has the function of photoelectric conversion, it is not necessary to confirm the hole transport function. In other words, the hole transport layer 5 refers to the one positioned on the hole transport side of the light absorption layer 4.

[0038] As the hole transport layer 5, polymeric organic materials such as PTAA (Poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], poly[bis(4-phenyl)(2,4,6-triphenylmethyl)amine]), poly-TPD (Poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)-benzidine], N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)-benzidine), PEDOT:PSS (Poly(3,4-e-thylenedioxythiophene):poly(styrenesulfonate), poly(2,3-dihydrothieno-1,4-dioxin):poly(styrenesulfonate)) can be used, and spiro-OMeTAD(N 2 ,N 2 ,N 2 ′,N 2 ′,N 7 ,N 7 ,N 7 ′,N 7Low molecular weight organic materials such as '-octakis(4-methoxyphenyl)-9,9′-spirobi[9H-fluorene]-2,2′,7,7′-tetramine), 5-AVAI(5-Aminopentanoic Acid Hydroiodide Homopiperidinic Acid Hydroiodide), 5-aminopentanoic acid hydroiodide, 3-apy(3-aminopyridine), 3-aminopyridine, MeO-2PACz([2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid), 2PACz([2-(9H-carbazole-9-yl)ethyl]phosphonic acid), etc. can be used. The hole transport layer 5 can be formed by coating and drying a solution dissolved in a solvent to form a film. This solution may also contain polyamino acids for forming the buffer layer 51 described later. The thickness of the hole transport layer 5 can be, for example, 40 nm to 600 nm.

[0039] [ka]

[0040] Furthermore, in this embodiment, the hole transport layer 5 is provided between the light absorption layer 4 and the buffer layer 51 via a buffer layer 51. This buffer layer 51 is composed of polyamino acids obtained by polymerizing amino acids having charged side chains of reactive functional groups. As shown below, in this buffer layer 51, since the monomers are amino acids having charged side chains of reactive functional groups, the polyamino acids have peptide bonds equal to the number of polymerization units, with a pair of amino groups and carboxyl groups consumed during polymerization, and the number of reactive functional groups equal to the number of polymerization units remaining.

[0041] [ka]

[0042] In this case, the hole transport layer 5 is made by applying polyamino acids, which already have a polymer structure, to the buffer layer 51 that is in contact with the light absorption layer 4. This results in a denser structure, which suppresses the formation of gaps that allow water molecules and other substances to penetrate the light absorption layer 4, thereby improving durability. In addition, the performance is enhanced by the reactive functional groups provided on the charged side chains of the monomers. For example, when the reactive functional group is an amino group, amine accumulation, particularly the accumulation of primary amine amino groups, increases. It is already understood that high amine accumulation leads to higher photoelectric conversion efficiency, and when this is a primary amine amino group, the photoelectric conversion efficiency increases even further. Furthermore, when the reactive functional group is a carboxyl group or a hydroxyl group, these carboxyl groups and hydroxyl groups react with the hole transport layer 5 and the light absorption layer 4, resulting in increased adhesion between the buffer layer 51 and the hole transport layer 5 and the light absorption layer 4.

[0043] Polyamino acids polymerized from amino acids having charged side chains of reactive functional groups used in this buffer layer 51 include polyamino acids whose monomers are amino acids having polar, uncharged side chains such as asparagine, cysteine, glutamine, serine, and threonine; polyamino acids whose monomers are basic amino acids having charged side chains such as arginine, histidine, and lysine; polyamino acids whose monomers are acidic amino acids having charged side chains such as aspartic acid and glutamic acid; polyamino acids whose monomers are aliphatic amino acids having hydrophobic side chains such as glycine, alanine, isoleucine, leucine, methionine, and valine; polyamino acids whose monomers are aromatic amino acids having hydrophobic side chains such as phenylalanine, tryptophan, and tyrosine; and polyamino acids whose monomers are other amino acids such as proline.

[0044] [ka]

[0045] The molecular weight of this polyamino acid is 100,000 or less, preferably 1,000 to 100,000, and more preferably 2,000 to 5,000. Furthermore, any degree of polymerization of 2 or more is acceptable, and polymers with a degree of polymerization of up to approximately 500 are also acceptable. Alternatively, oligomers with a degree of polymerization of up to approximately 20 are also acceptable. These polyamino acids may also be combinations of multiple polyamino acids with different monomers having charged side chains of reactive functional groups, different degrees of polymerization, or different molecular weights.

[0046] In particular, when polyarginine and polylysine are used among these polyamino acids, the polymerization structure allows for a dense layer, and because they have amino groups as charged side chains, amine accumulation, especially the accumulation of primary amine amino groups, is high. As a result, the photoelectric conversion efficiency between the light-absorbing layer 4 and the second electrode 6 can be increased.

[0047] In the buffer layer 51, which is composed of this polyamino acid, or, as will be described later, in the hole transport layer 5, buffer layer 31, and electron transport layer 3, which are composed of this polyamino acid, the structural determination of the polyamino acid and the amino acid can be performed by combining the following analytical methods, which are listed as an example. Extraction of analysis sites A specific layer is separated from the solar cell 10 by methods such as cutting or peeling, and if possible, the separated solid material (powder) is subjected to further analysis by dissolving and removing only the excess components in a solvent. Method for detecting amino groups The amount of free residues is quantified by color reactions, fluorescence reactions, etc., with the test reagent. Method for distinguishing between polymer-derived and monomer-derived materials The presence or absence of polymeric regions can be confirmed using FT-IR, HPLC, LC / MS, NMR, etc. After hydrolysis of the polymer, the amino acid species can be identified by separation and analysis using chromatography.

[0048] [Second electrode] The second electrode 6 is conductive and may be a counter electrode on the non-light-receiving side or the side opposite the light-receiving surface of the solar cell 10, or it may be a transparent electrode that allows light to pass through, similar to the first electrode 1. When the second electrode 6 is used as a counter electrode, it is preferable that the second electrode 6 has the function of reflecting light. In this case, it is preferable that the second electrode 6 contains a metal or alloy that includes one or more selected from the group consisting of Au, Ag, Cu, and Al. The film thickness of the second electrode 6 may be, for example, 50 nm to 300 nm. However, the second electrode 6 does not necessarily need to have the function of reflecting light. When the second electrode 6 is a transparent electrode, the same material as the first electrode 1 described above may be used.

[0049] The second electrode 6 is connected to the hole transport layer 5.

[0050] As described above, the solar cell 10 according to the first embodiment comprises a first electrode 2, an electron transport layer 3 formed on the first electrode 1, a light absorption layer 4 formed on the electron transport layer 3, a hole transport layer 5 formed on the light absorption layer 4, and a second electrode 6 formed on the hole transport layer 5. The hole transport layer 5 is provided on the light absorption layer 4 via a buffer layer 51. This makes the buffer layer 51 at the boundary between the light absorption layer 4 and the hole transport layer 5 denser, suppressing the formation of gaps that allow water molecules and the like to penetrate the light absorption layer 4, thereby improving the durability between the light absorption layer 4 and the hole transport layer 5. Furthermore, the buffer layer 51 can improve the photoelectric conversion rate by the light absorption layer 4 or enhance the adhesion between the light absorption layer 4 and the hole transport layer 5 depending on the polyamino acid used, thereby improving performance.

[0051] <Second Embodiment> Figure 2 is a cross-sectional view of a solar cell 10 according to the second embodiment. The solar cell 10 according to the second embodiment differs from the solar cell 10 according to the first embodiment shown in Figure 1 in the configuration of the hole transport layer 5. Specifically, in the solar cell 10 according to the second embodiment, the hole transport layer 5 does not constitute a buffer layer 51, and the polyamino acids that constituted the buffer layer 51 are included in the entire hole transport layer 5 to constitute the hole transport layer 5.

[0052] According to the solar cell 10 of this second embodiment, the inclusion of polyamino acids makes the entire hole transport layer 5 denser, and the reactive functional groups provided on the charged side chains of the polyamino acids improve the photoelectric conversion efficiency of the light absorption layer 4 and improve the adhesion between the light absorption layer 4 and the hole transport layer 5.

[0053] <Third Embodiment> Figure 3 is a cross-sectional view of a solar cell 10 according to the third embodiment. The solar cell 10 according to the third embodiment has a so-called inverse junction planar structure, and is the same as the solar cell 10 according to the first embodiment shown in Figure 1, except for the inverse junction planar structure. It comprises a second electrode 6 provided on a substrate 1, a hole transport layer 5 provided on the second electrode 6, a light absorption layer 4 provided on the hole transport layer 5 via a buffer layer 51, an electron transport layer 3 provided on the light absorption layer 4, and a first electrode 2 provided on the electron transport layer 3. The same reference numerals are used for the same components and their descriptions are omitted.

[0054] <Fourth Embodiment> Figure 4 is a cross-sectional view of a solar cell 10 according to the fourth embodiment. The solar cell 10 according to the fourth embodiment has a so-called inverse junction planar structure, and is the same as the solar cell 10 according to the second embodiment shown in Figure 2, except for the inverse junction planar structure. It comprises a second electrode 6 provided on a substrate 1, a hole transport layer 5 provided on the second electrode 6, a light absorption layer 4 provided on the hole transport layer 5, an electron transport layer 3 provided on the light absorption layer 4, and a first electrode 2 provided on the electron transport layer 3. The same reference numerals are used for the same components and their descriptions are omitted.

[0055] <Fifth Embodiment> Figure 5 is a cross-sectional view of a solar cell 10 according to the fifth embodiment. The solar cell 10 according to the fifth embodiment is the same as the solar cell 10 according to the first embodiment shown in Figure 1, except for the configuration of the electron transport layer 3 and the hole transport layer 5. Here, only the differences will be explained, and other components will be given the same reference numerals and their explanations will be omitted. In the solar cell 10 according to the fifth embodiment, the electron transport layer 3, which is the other charge transport layer different from the hole transport layer 5, has a buffer layer 31, and is in contact with the light absorption layer 4 via this buffer layer 31. On the other hand, the hole transport layer 5 does not have a buffer layer 51.

[0056] The configuration of the electron transport layer 3 is the same as that of the electron transport layer 3 of the solar cell 10 according to the first embodiment shown in Figure 1. However, the electron transport layer 3 of the solar cell 10 according to the fifth embodiment has a buffer layer 31, which is in contact with the light absorption layer 4. This buffer layer 31 is composed of polyamino acids polymerized from amino acids having charged side chains of reactive functional groups, similar to the buffer layer 51 of the hole transport layer 5 of the solar cell 10 according to the first embodiment.

[0057] The hole transport layer 5 does not have a buffer layer 51, and the hole transport layer 5 is provided in contact with the light absorption layer 4.

[0058] According to the solar cell 10 of this fifth embodiment, the inclusion of polyamino acids makes the buffer layer 31 at the boundary between the light absorption layer 4 and the electron transport layer 3 denser, preventing the formation of gaps that allow water molecules and the like to penetrate the light absorption layer 4, thereby improving the durability between the light absorption layer 4 and the electron transport layer 3. Furthermore, the buffer layer 31 can improve the photoelectric conversion rate by the light absorption layer 4 and enhance the adhesion between the light absorption layer 4 and the electron transport layer 3 depending on the polyamino acids used, thereby improving performance.

[0059] <Sixth Embodiment> Figure 6 is a cross-sectional view of the solar cell 10 according to the sixth embodiment. The solar cell 10 according to the sixth embodiment differs from the solar cell 10 according to the fifth embodiment shown in Figure 5 in the configuration of the electron transport layer 3. Specifically, in the solar cell 10 according to the sixth embodiment, the electron transport layer 3 does not constitute a buffer layer 31, and the polyamino acids that constituted the buffer layer 31 are included in the entire electron transport layer 3 to form the electron transport layer 3.

[0060] According to the solar cell 10 of this second embodiment, the inclusion of polyamino acids makes the entire hole transport layer 5 denser, and the reactive functional groups provided on the charged side chains of the polyamino acids improve the photoelectric conversion efficiency of the light absorption layer 4 and improve the adhesion between the light absorption layer 4 and the hole transport layer 5.

[0061] <Seventh Embodiment> Figure 7 is a cross-sectional view of a solar cell 10 according to the seventh embodiment. The solar cell 10 according to the seventh embodiment has a so-called inverse junction planar structure, and is the same as the solar cell 10 according to the fifth embodiment shown in Figure 5, except for the inverse junction planar structure. It comprises a second electrode 6 provided on a substrate 1, a hole transport layer 5 provided on the second electrode 6, a light absorption layer 4 provided on the hole transport layer 5, an electron transport layer 3 provided on the light absorption layer 4, and a first electrode 2 provided on the electron transport layer 3. The same reference numerals are used for the same components and their descriptions are omitted.

[0062] <Eighth Embodiment> Figure 8 is a cross-sectional view of a solar cell 10 according to the eighth embodiment. The solar cell 10 according to the eighth embodiment has a so-called inverse junction planar structure, and is the same as the solar cell 10 according to the fifth embodiment shown in Figure 5, except for the inverse junction planar structure. It comprises a second electrode 6 provided on a substrate 1, a hole transport layer 5 provided on the second electrode 6, a light absorption layer 4 provided on the hole transport layer 5, an electron transport layer 3 provided on the light absorption layer 4, and a first electrode 2 provided on the electron transport layer 3. The same reference numerals are used for the same components and their descriptions are omitted.

[0063] <Ninth Embodiment> Figure 9 is a cross-sectional view of a solar cell 10 according to the ninth embodiment. The solar cell 10 according to the ninth embodiment is the same as the solar cell 10 according to the first embodiment shown in Figure 1, except for the configuration of the electron transport layer 3. Here, only the differences will be explained, and other components will be given the same reference numerals and their explanations will be omitted. In the solar cell 10 according to the ninth embodiment, the electron transport layer 3 is constructed by including polyamino acids in the electron transport layer 3, similar to the electron transport layer 3 shown in Figure 6.

[0064] <Tenth Embodiment> Figure 10 is a cross-sectional view of a solar cell 10 according to the 10th embodiment. The solar cell 10 according to the 10th embodiment is the same as the solar cell 10 according to the 2nd embodiment shown in Figure 2, except for the configuration of the electron transport layer 3. Here, only the differences will be explained, and other components will be given the same reference numerals and their explanations will be omitted. In the solar cell 10 according to the 10th embodiment, the electron transport layer 3 has a buffer layer 31, similar to the electron transport layer 3 shown in Figure 5, and is in contact with the light absorption layer 4 via this buffer layer 31.

[0065] <Embodiment 11> Figure 11 is a cross-sectional view of a solar cell 10 according to the 11th embodiment. The solar cell 10 according to the 11th embodiment has a so-called reverse junction planar structure, and is the same as the solar cell 10 according to the 9th embodiment shown in Figure 9, except for the reverse junction planar structure. The same reference numerals are used for the same components and their descriptions are omitted.

[0066] <Twelfth Embodiment> Figure 12 is a cross-sectional view of the solar cell 10 according to the 12th embodiment. The solar cell 10 according to the 12th embodiment has a so-called reverse junction planar structure, and is the same as the solar cell 10 according to the 10th embodiment shown in Figure 10, except for the reverse junction planar structure. The same reference numerals are used for the same components and their descriptions are omitted.

[0067] <13th Embodiment> Figure 13 is a cross-sectional view of a solar cell 10 according to the 13th embodiment. The solar cell 10 according to the 13th embodiment is the same as the solar cell 10 according to the 9th embodiment shown in Figure 9, except for the configuration of the electron transport layer 3. Here, only the differences will be explained, and other components will be given the same reference numerals and their explanations will be omitted. In the solar cell 10 according to the 13th embodiment, the electron transport layer 3 has a buffer layer 31, similar to the electron transport layer 3 shown in Figure 5, and is in contact with the light absorption layer 4 via this buffer layer 31.

[0068] <14th Embodiment> Figure 14 is a cross-sectional view of a solar cell 10 according to the 14th embodiment. The solar cell 10 according to the 14th embodiment is the same as the solar cell 10 according to the 10th embodiment shown in Figure 10, except for the configuration of the electron transport layer 3. Here, only the differences will be explained, and other components will be given the same reference numerals and their explanations will be omitted. In the solar cell 10 according to the 14th embodiment, the electron transport layer 3 is constructed by including polyamino acids throughout the electron transport layer 3, similar to the electron transport layer 3 shown in Figure 6.

[0069] <15th Embodiment> Figure 15 is a cross-sectional view of a solar cell 10 according to the 15th embodiment. The solar cell 10 according to the 15th embodiment has a so-called reverse junction planar structure, and is the same as the solar cell 10 according to the 13th embodiment shown in Figure 13, except for the reverse junction planar structure. The same reference numerals are used for the same components and their descriptions are omitted.

[0070] <Embodiment 16> Figure 16 is a cross-sectional view of a solar cell 10 according to the 16th embodiment. The solar cell 10 according to the 16th embodiment has a so-called reverse junction planar structure, and is the same as the solar cell 10 according to the 10th embodiment shown in Figure 14, except for the reverse junction planar structure. The same reference numerals are used for the same components and their descriptions are omitted.

[0071] 2. Method for manufacturing solar cells Using the solar cell 10 shown in Figure 1 as an example, a method for manufacturing each of the above-described solar cells 10 will be explained.

[0072] A method for manufacturing a solar cell 10 includes the steps of: forming an electron transport layer 3 on a first electrode 2; forming a light absorption layer 4 of a perovskite compound on the electron transport layer 3; forming a hole transport layer 5 on the light absorption layer 4 via a buffer layer 51; and forming a second electrode 6 on the hole transport layer 5.

[0073] The first electrode 2 is formed on the substrate 1 by sputtering, vacuum deposition, or the like. The electron transport layer 3 formed on the first electrode 2 is created by coating the first electrode 2 with a coating solution containing the constituent materials of the electron transport layer 3, and then heating and drying it to evaporate the solvent from the coating solution. In this case, the coating method of the coating solution is not limited to spin coating, immersion coating, inkjet printing, screen printing, slit die coating, etc., and a suitable coating method can be selected. The light-absorbing layer 4, formed on the electron transport layer 3, is also formed in the same way as the electron transport layer 3. A coating solution containing the constituent materials of the light-absorbing layer 4 is applied to the electron transport layer 3, and the solvent in the coating solution is evaporated by heating and drying to form the film. The coating method is not limited to the above, and a suitable coating method can be selected. Next, a hole transport layer 5 is formed on the light absorption layer 4. First, a solution containing the polyamino acids that make up the buffer layer 51 is applied to the light absorption layer 4, and the solvent in the coating solution is evaporated by heating to form the buffer layer 51. Then, a coating solution containing the constituent materials of the hole transport layer 5 is applied to the buffer layer 51, and the solvent in the coating solution is evaporated by heating to form the hole transport layer 5. Then, by forming a second electrode 6 on this hole transport layer 5 using sputtering, vacuum deposition, or the like, a solar cell 10 can be constructed. The above is an example of how the solar cell 10 of the first embodiment is configured, and is basically configured in the order in which it is stacked on the substrate 1.

[0074] In the case of the solar cell 10 of the second embodiment shown in Figure 2, where there is no buffer layer 51 and only a hole transport layer 5, the polyamino acids constituting the buffer layer 51 are mixed and dissolved in a coating solution containing the constituent materials of the hole transport layer 5, this is applied onto the light absorption layer 4, and the solvent in the coating solution is evaporated by heating to form the hole transport layer 5. The same procedure is followed when forming an electron transport layer 3 with a buffer layer 31 and an electron transport layer 3 without a buffer layer 31. When forming an electron transport layer 3 with a buffer layer 31, a solution containing the polyamino acids constituting the buffer layer 31 is applied onto the light absorption layer 4, and the solvent in the coating solution is evaporated by heating to form the buffer layer 31. Then, a coating solution containing the constituent materials of the electron transport layer 3 is applied onto the buffer layer 31, and the solvent in the coating solution is evaporated by heating to form the electron transport layer 3. When forming an electron transport layer 3 without a buffer layer 31, the polyamino acids constituting the buffer layer 31 are mixed and dissolved in a coating solution containing the constituent materials of the electron transport layer 3. This solution is then applied onto the light absorption layer 4, and the solvent in the coating solution is evaporated by heating to form the electron transport layer 3. When manufacturing the solar cell 10 of the 16th embodiment from the solar cell 10 of the second embodiment, it can be manufactured by going through each step in the same manner as described above.

[0075] 3. Solar cell module and method for manufacturing a solar cell module Figure 17 is a schematic cross-sectional view of a solar cell module 100 (series-connected solar cell) equipped with solar cell cells 10 according to this embodiment. As shown in Figure 17, the solar cell module 100 according to this embodiment is created by integrating the aforementioned solar cell cells 10. As described above, by forming buffer layers 31 and 51 containing polyamino acids, or electron transport layers 3 and hole transport layers 5 containing polyamino acids in the solar cell 10, the durability of the solar cell 10 can be improved and the conversion efficiency can be improved.

[0076] As shown in Figure 17, the solar cell module 100 according to this embodiment comprises a substrate 1, a first electrode 2 provided on the substrate 1, an electron transport layer 3 provided on the first electrode 2, a light absorption layer 4 provided on the electron transport layer 3, a hole transport layer 5 provided on the light absorption layer 4, a second electrode 6 provided on the hole transport layer 5, a second barrier layer 72 provided on the second electrode 6, and a back substrate 74 provided on the second barrier layer 72, with a buffer layer 51 provided between the light absorption layer 4 and the hole transport layer 5. The solar cell module 100 shown in Figure 17 is a solar cell module 100 in which the substrate 1 is transparent glass.

[0077] Figures 18 and 19 are schematic cross-sectional views of a solar cell module 110 equipped with a solar cell 10 (modifications 1 and 2) according to this embodiment, respectively, and represent a solar cell module in which the substrate 1 is a transparent resin such as an organic film. As shown in Figures 18 and 19, the solar cell module 110 according to this embodiment comprises a substrate 1, a first barrier layer 71 provided on the substrate 1, a first electrode 2 provided on the first barrier layer 71, an electron transport layer 3 provided on the first electrode 2, a light absorption layer 4 provided on the electron transport layer 3, a hole transport layer 5 provided on the light absorption layer 4, a second electrode 6 provided on the hole transport layer 5, a second barrier layer 72 provided on the second electrode 6, a third barrier layer 73 provided on the second barrier layer 72, and a back substrate 74 provided on the third barrier layer 73, with a buffer layer 51 provided between the light absorption layer 4 and the hole transport layer 5. The first barrier layer 71 is a layer of a material with high gas barrier properties. The second barrier layer 72 is a dense inorganic material layer. The third barrier layer 73 is a layer of a material with high gas barrier properties.

[0078] Furthermore, as shown in Figures 18 and 19, the second barrier layer 72 is provided so as to cover the hole transport layer 5 and the sides of the second electrode 6, and so as to cover the top of the second electrode 6. The second barrier layer 72 covers the top and sides of each solar cell 10-10.

[0079] Furthermore, as shown in Figures 17, 18, and 19, the hole transport layer 5 covers the top and sides of the light absorption layer 4. The second electrode 6 covers the top and one side of the hole transport layer 5. The second electrode 6 extends from the top to the side of the hole transport layer 5 and is connected to the top of the first electrode 2 of the adjacent solar cell 10, thereby connecting the adjacent solar cell 10 in series.

[0080] The solar cell modules 100 and 110 of this embodiment include a plurality of solar cells 10 to 10, a first terminal 81, and a second terminal 82, and the plurality of solar cells 10 to 10 are connected in series. Of the plurality of solar cells 10 to 10 connected in series, the solar cell 10 at one end is connected to the first terminal 81, and the solar cell 10 at the other end is connected to the second terminal 82. The number of solar cells 10 to 10 connected in series is not particularly limited as long as there are multiple cells.

[0081] Substrate 1 is the substrate for the solar cell modules 100 and 110. Substrate 1 may be a transparent glass substrate as shown in Figure 17, or a transparent organic film as shown in Figures 18 and 19. This allows light to be incident on the inside of the solar cell 10. If substrate 1 is a flexible organic film, the solar cell module 110 becomes a flexible solar cell module.

[0082] Examples of materials for the organic film that forms the base 1 include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), polyetherimide (PEI), polyamideimide (PAI), and polyethylene naphthalate (PEN), but other resins can also be used as long as they meet the requirements. The thickness of the organic film forming the base 1 is preferably 50 μm to 100 μm.

[0083] If the substrate 1 is a transparent organic film, a first barrier layer 71 may be provided on one of the main surfaces of the substrate 1 in the +Y direction, as shown in Figures 18 and 19. The first barrier layer 71 is a layer of material with high gas barrier properties. This prevents deterioration of the inside of the solar cell 10 due to moisture and oxygen in the air. The first barrier layer 71 is also a layer of insulating material. This suppresses the flow of leakage current. The thickness of the first barrier layer 71 can be several tens of nanometers to 100 nanometers. This allows the first barrier layer 71 to be light-transmitting. Furthermore, the solar cell 10 and solar cell module 110 can be flexible. Specific examples of materials for the first barrier layer 71 include silicon oxide and aluminum oxide. As long as the first barrier layer 71 has gas barrier properties, insulating properties, and light-transmitting properties, other oxidizing substances and insulators can also be used as materials for the first barrier layer 71. Examples of main film deposition methods for the first barrier layer 71 include sputter deposition and vacuum deposition.

[0084] The first electrode 2 is provided on the substrate 1 (on the first barrier layer 71 in the examples shown in Figures 18 and 19) and extracts the current generated by the photovoltaic power of the solar cell 10. The first electrode 2 is made of a conductive transparent material such as aluminum-doped zinc oxide (AZO), indium zinc oxide (IZO), gallium-doped zinc oxide (GZO), fluorine-doped tin oxide (FTO), or indium tin oxide (ITO). Preferably, the sheet resistance of the first electrode 2 is 10 Ω / sq or less, and the light transmittance of the first electrode 2 is 30% or more. Examples of methods for forming the first electrode 2 include sputter deposition and vacuum deposition.

[0085] When multiple solar cells 10 are provided on a substrate 1, the first electrode 2 formed on the substrate 1 is divided for each solar cell 10. For example, the solar cell modules 100 and 110 shown in Figures 17, 18, and 19 contain five solar cells 10, so the first electrode 2 is divided and five first electrodes 2 are formed. The groove O separating two adjacent first electrodes 2 may be filled with a light-absorbing layer 4 or the like. Note that the first electrode 2 spans two adjacent solar cells 10, 10. That is, as shown in Figures 17, 18, and 19, an electron transport layer 3 is formed on one first electrode 2 and a light-absorbing layer 4 is formed on the other first electrode 2.

[0086] The light-receiving side of the substrate 1 is provided with the first terminal 81 of the solar cell modules 100 and 110. A portion of the first terminal 81 penetrates the substrate 1 (the first barrier layer 71 in the example shown in Figures 18 and 19) and contacts or electrically connects to the first electrode 2 at one end of the series-connected solar cell 10. This first terminal 81 can be used to extract the current generated by the photovoltaic power of the solar cell modules 100 and 110. An example of a material for the first terminal 81 is a SnZn-based solder paste. Other conductive pastes and materials for the second electrode 6 can also be used as long as they meet the requirements.

[0087] After the first electrode 2 is formed on the transparent substrate 1, an incision (L1) is made in the first electrode 2 by laser scribing in order to separate and form the solar cell 10 on the substrate 1. The wavelength of the laser used is preferably in the infrared region. An incision (L1) is made in the first electrode 2, and the first electrode 2 with the incision is formed. No incision is made in the substrate 1 (first barrier layer 71 in the examples shown in Figures 18 and 19). For example, a perovskite compound can be formed on the substrate 1 and the first electrode 2 that have been cut with laser scribing (L1) to form a light absorption layer 4.

[0088] Examples of organic solvents (contained in the coating solution) used in the coating method for forming the light-absorbing layer 4 include: aromatic hydrocarbons such as toluene, xylene, mesitylene, tetralin, diphenylmethane, dimethoxybenzene, and dichlorobenzene; halogenated hydrocarbons such as dichloromethane, dichloroethane, and tetrachloropropane; ethers such as tetrahydrofuran (THF), dioxane, dibenzyl ether, dimethoxymethyl ether, and 1,2-dimethoxyethane; ketones such as methyl ethyl ketone, cyclohexanone, acetophenone, and isophorone; esters such as methyl benzoate, ethyl acetate, and butyl acetate; sulfur-containing solvents such as diphenyl sulfide; fluorinated solvents such as hexafluoroisopropanol; aprotic polar solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide; alcohols such as methanol, ethanol, and isopropanol; and glyme solvents such as ethylene glycol and diethylene glycol monomethyl ether. These can be used individually or as mixed solvents. These solvents may contain water. Among these solvents, non-halogenated organic solvents can be preferably used from the perspective of considering the global environment.

[0089] After the light absorption layer 4 is formed, a cut (L2) is made in a portion of the light absorption layer 4 by laser scribing in order to connect the first electrode 2 of one of the two adjacent solar cells 10 to the hole transport layer 5 and second electrode 6 of the other solar cell 10. The wavelength of the laser used is preferably in the visible light region. For example, a cut (L2) is made in the light absorption layer 4, and the light absorption layer 4 is formed. In this laser scribing, the light absorption layer 4 is removed, but the first electrode 2 (first barrier layer 71 in the example shown in Figures 18 and 19) is not removed.

[0090] Subsequently, a hole transport layer 5 is formed to create the second electrode 6.

[0091] The second electrode 6 is provided on the hole transport layer 5 and is intended to extract the current generated by the photovoltaic power of the light absorption layer 4 of the solar cell 10. The second electrode 6 is, for example, a metal film with a work function of 5 eV or more. By making the second electrode 6 out of a metal with a deep work function (5 eV or more), a band structure bend occurs at the interface between the light absorption layer 4 and the second electrode 6, which allows for a smooth flow of electrons. The film thickness of the second electrode 6 is preferably 50 nm to 150 nm. The light absorption layer 4 or the second electrode 6 can be formed by, for example, sputter deposition or vacuum deposition.

[0092] After the second electrode 6 is formed, cuts (L3) are made in a portion of the hole transport layer 5 and the second electrode 6 by laser scribing in order to form a series connection circuit of adjacent solar cells 10 on the substrate 1. Alternatively, cuts (L3) may be made in the electron transport layer 3, light absorption layer 4, hole transport layer 5, and second electrode 6 to allow the second barrier layer 72 to function as a varistor. The wavelength of the laser used is preferably in the ultraviolet region. For example, cuts (L3) are made in the hole transport layer 5 and the second electrode 6 to form the hole transport layer 5 and the second electrode 6. Cuts for forming a varistor can also be made. Note that if the portion with cuts (L3) functions as a varistor, the cuts can be omitted.

[0093] The second barrier layer 72 is a dense inorganic material layer and is provided to cover the sides of the light absorption layer 4. The second barrier layer 72 can also be provided to cover the entire periphery of the light absorption layer 4. Furthermore, the second barrier layer 72 can be provided to cover the upper surface of the second electrode 6. This second barrier layer 72 prevents moisture (such as water vapor) from entering the light absorption layer 4, thereby preventing degradation of the solar cell 10. Additionally, because the second barrier layer 72 is a dense inorganic material layer, it can prevent the barrier function of the second barrier layer 72 from degrading due to ultraviolet light, temperature changes, etc. Furthermore, completely coating the light absorption layer 4 with the second barrier layer 72, the first electrode 2, the substrate 1, etc., can also improve the barrier properties against water vapor.

[0094] Furthermore, the second barrier layer 72 may be composed of a material exhibiting varistor characteristics. The second barrier layer 72 can also be connected to the first electrode 2 and the second electrode 6 such that the second barrier layer 72 and the light absorption layer 4 are connected in parallel. A varistor characteristic is a voltage-current characteristic (current nonlinearity) in which current suddenly flows at a certain voltage. The material exhibiting varistor characteristics is not particularly limited as long as it is a material that can be used in a varistor element.

[0095] The thickness of the second barrier layer 72 can be, for example, 30 nm to 100 nm. The second barrier layer 72 is formed on the second electrode 6 after laser scribing. The second barrier layer 72 can also be formed to fill the notch (L3). This allows the periphery and top surface of the light absorption layer 4 to be covered with the second barrier layer 72. The second barrier layer 72 can also be formed to fill the notch. This allows the second barrier layer 72 to be connected to the first electrode 2 and the second electrode 6 such that the second barrier layer 72 and the light absorption layer 4 are connected in parallel.

[0096] By connecting a portion of the second barrier layer 72 in parallel with the light absorption layer 4 as a varistor element structure, a solar cell 10 integrated with a bypass diode (varistor of the second barrier layer 72) can be realized. This makes it possible to suppress the decrease in power generation efficiency due to shading on the solar cell module 110 at low cost.

[0097] The second barrier layer 72 may, for example, contain zinc oxide (ZnO) as its main material and may include silicon oxide, aluminum oxide, titanium oxide, etc. as additive materials. The varistor characteristics of the second barrier layer 72 between the first electrode 2 and the second electrode 6 (I=KVα, K: element intrinsic constant, α: voltage nonlinearity coefficient) are preferably such that α = 20 to 60 and the inflection point voltage is 2V or higher.

[0098] The back substrate 74 is a substrate positioned on the non-light-receiving side, and the light-absorbing layer 4 is located between the substrate 1 and the back substrate 74. The back substrate 74 may be the substrate of the solar cell modules 100 and 110. The back substrate 74 may be a glass substrate, a transparent organic film, or an opaque organic film.

[0099] If the back substrate 74 is an organic film, a third barrier layer 73 may be provided on one of the main surfaces of the back substrate 74, as shown in Figures 18 and 19. The third barrier layer 73 is a layer of material with high gas barrier properties. This prevents deterioration of the inside of the solar cell 10 due to moisture and oxygen in the air. The third barrier layer 73 is also a layer of insulating material. This suppresses the flow of leakage current. The thickness of the third barrier layer 73 can be several tens of nanometers to 100 nanometers. Specific examples of materials for the third barrier layer 73 include silicon oxide and aluminum oxide.

[0100] The organic film, which is the back substrate 74, has the second terminals 82 of the solar cell modules 100 and 110 formed on it. A portion of the second terminals 82 penetrates the organic film (back substrate 74) (the third barrier layer 73 in the example shown in Figures 18 and 19) and contacts or connects to the second electrode 6 at the other end of the series-connected solar cell 10 via the second barrier layer 72. The current generated by the photovoltaic power of the solar cell modules 100 and 110 can be extracted using the first terminal 81 and the second terminal 82. An example of a material for the second terminal 82 is a SnZn-based solder paste. Other conductive pastes and materials for the second electrode 6 can also be used as long as they meet the requirements.

[0101] After forming a second barrier layer 72 on the second electrode 6 (and a third barrier layer 73 on the second barrier layer 72), a back substrate 74 with the second terminal 82 formed on it is bonded to the second barrier layer 72 (third barrier layer 73) via a laminate sheet, and then heat-laminated to complete a solar cell module 100, 110 in which multiple solar cells 10 are connected in series. The laminate sheet sandwiched between the second barrier layer 72 and the back substrate 74 (third barrier layer 73) is perforated where the second terminal 82 is located. Therefore, the second terminal 82 and the second barrier layer 72 are well connected during lamination. This forms a varistor between the second electrode 6 and the second terminal 82. During power generation, a high voltage is applied between the second electrode 6 and the second terminal 82, and its varistor characteristics do not hinder current extraction. Alternatively, the second electrode 6 and the second terminal 82 may be brought into contact.

[0102] For the laminate sheet, any general laminating material is acceptable, but a resin film with a lamination temperature of 130°C or lower and high water resistance is preferable.

[0103] Figure 20 is a diagram showing a schematic cross-sectional view of one solar cell 10 included in the solar cell module 100 shown in Figure 17, superimposed with the equivalent circuit of the solar cell 10, and Figure 21 is the equivalent circuit of the solar cell module 100. As shown in Figures 20 and 21, the electron transport layer 3, the light absorption layer 4, and the hole transport layer 5 can be represented by a current source 92 and a diode 93. In addition, the varistor 91 is connected to the first electrode 2 and the second electrode 6 in parallel with the light absorption layer 4.

[0104] 4. Applications of solar cells and solar modules The solar cell 10 and solar cell modules 100 and 110 constructed in this manner can be used in a wide range of applications. In particular, when the substrate 1 is a flexible organic film, the solar cell module 110 becomes a flexible solar cell module, making it possible to apply it to curved surfaces. Moreover, it can be made lighter compared to the case where the substrate 1 is made of glass. Furthermore, the configuration of the electron transport layer 3, buffer layer 31, hole transport layer 5, and buffer layer 51 containing polyamino acids provides high durability, making it suitable for outdoor use.

[0105] This technology can be applied to the body surfaces and interiors of various transportation equipment such as trains, automobiles, ships, and aircraft, and used as part of the power supply for these vehicles. It can also be applied to the casings of various electrical appliances requiring power, and used as part of the power supply for these appliances. Furthermore, it can be applied to the surfaces of various outdoor structures such as buildings, apartments, warehouses, houses, elevated bridges, bridges, control towers, signs, and markers, and the resulting power can be used within these structures or transmitted for use elsewhere. Of course, it can also be used in solar power generation systems (mega-solar).

[0106] As mentioned above, each embodiment and example of this disclosure has been described in detail, but it will be readily apparent to those skilled in the art that many modifications are possible without substantially departing from the novelty and effects of this disclosure. Therefore, all such modifications are included within the scope of this disclosure.

[0107] For example, any term that appears at least once in the specification or drawings alongside a broader or synonymous term may be replaced with that different term anywhere in the specification or drawings. Furthermore, the configuration and operation of solar cells and methods for manufacturing solar cells, as well as solar modules and methods for manufacturing solar modules, are not limited to those described in the embodiments and examples of this disclosure, and various modifications are possible. [Note] (Aspect 1) A step of forming an electron transport layer on the first electrode, The steps include forming a light-absorbing layer of a perovskite compound on the electron transport layer, The steps include forming a hole transport layer on the light absorption layer, The step includes forming a second electrode on the hole transport layer, or A step of forming a hole transport layer on the second electrode, The steps include forming a light-absorbing layer of a perovskite compound on the hole transport layer, The process of forming an electron transport layer on the light absorption layer, The step includes forming a first electrode on the electron transport layer, A method for manufacturing a solar cell, wherein the step of forming the hole transport layer and / or the step of forming the electron transport layer comprises a buffer layer formation step of forming a buffer layer between the hole transport layer and the light absorption layer and / or between the electron transport layer and the light absorption layer, and the buffer layer formation step is characterized by adding a solution containing a polyamino acid obtained by polymerizing amino acids having charged side chains of reactive functional groups. (Aspect 2) A step of forming an electron transport layer on the first electrode, The steps include forming a light-absorbing layer of a perovskite compound on the electron transport layer, The steps include forming a hole transport layer on the light absorption layer, The step includes forming a second electrode on the hole transport layer, or A step of forming a hole transport layer on the second electrode, The steps include forming a light-absorbing layer of a perovskite compound on the hole transport layer, The process of forming an electron transport layer on the light absorption layer, The step includes forming a first electrode on the electron transport layer, A method for producing a solar cell, characterized in that the step of forming the hole transport layer and / or the step of forming the electron transport layer involves adding a solution containing a polyamino acid obtained by polymerizing amino acids having charged side chains of reactive functional groups. (Aspect 3) The method for producing a solar cell according to embodiment 1 or 2, wherein the polyamino acid is a polymer with a molecular weight of 1,000 to 1,000,000. (Aspect 4) The method for producing a solar cell according to embodiment 1 or 2, wherein the polyamino acid is a polymer with a molecular weight of 2000 to 5000. (Aspect 5) A method for producing a solar cell according to any one of embodiments 1 to 4, wherein the polyamino acid is polyarginine or polylysine. (Aspect 6) A method for manufacturing a solar cell module, characterized by integrating and modularizing solar cells manufactured by the method for manufacturing solar cells described in any one of embodiments 1 to 5. (Aspect 7) Between the electrode and the light-absorbing layer of the perovskite compound, there is a charge transport layer consisting of a hole transport layer or an electron transport layer. (1) A buffer layer between the light absorption layer and the charge transport layer, or (2) The composition of the charge transport layer is as follows: A solar cell characterized by containing an organic compound having a polymer structure of an amino acid having at least a charged side chain of a reactive functional group. (Pattern 8) The solar cell according to embodiment 7, wherein the amino acid of the organic compound is an amino acid having a basic charged side chain. (Aspect 9) The solar cell according to embodiment 7 or 8, wherein the organic compound is a polymer with a molecular weight of 1,000 to 1,000,000. (Aspect 10) The solar cell according to embodiment 7 or 8, wherein the organic compound is a polymer with a molecular weight of 2000 to 5000. (Aspect 11) The solar cell according to any one of embodiments 7 to 10, wherein the organic compound is polyarginine or polylysine. (Aspect 12) The solar cell according to any one of embodiments 7 to 11, wherein the charge transport layer is a hole transport layer. (Aspect 13) A solar cell module characterized by the integration and modularization of solar cells described in any one of embodiments 7 to 12. (Aspect 14) A transport device characterized by being equipped with a solar cell as described in any one of embodiments 7 to 12. (Aspect 15) An electrical appliance characterized by being equipped with a solar cell as described in any one of embodiments 7 to 12. (Aspect 16) A structure characterized by being equipped with a solar cell as described in any one of embodiments 7 to 12. [Explanation of Symbols]

[0108] 2 1st electrode 3 Electron transport layer (charge transport layer) 31 Buffer layer 31 4. Light-absorbing layer 5. Hole transport layer (charge transport layer) 51 Buffer layer 51 6 Second electrode 10 solar cells 100 solar modules 110 Solar Cell Modules

Claims

1. A step of forming an electron transport layer on the first electrode, The steps include forming a light-absorbing layer of a perovskite compound on the electron transport layer, The steps include forming a hole transport layer on the light absorption layer, The step includes forming a second electrode on the hole transport layer, or A step of forming a hole transport layer on the second electrode, The steps include forming a light-absorbing layer of a perovskite compound on the hole transport layer, The process of forming an electron transport layer on the light absorption layer, The step includes forming a first electrode on the electron transport layer, A method for manufacturing a solar cell, wherein the step of forming the hole transport layer and / or the step of forming the electron transport layer comprises a buffer layer formation step of forming a buffer layer between the hole transport layer and the light absorption layer and / or between the electron transport layer and the light absorption layer, and the buffer layer formation step is characterized by adding a solution containing a polyamino acid obtained by polymerizing amino acids having charged side chains of reactive functional groups.

2. A step of forming an electron transport layer on the first electrode, The steps include forming a light-absorbing layer of a perovskite compound on the electron transport layer, The steps include forming a hole transport layer on the light absorption layer, The step includes forming a second electrode on the hole transport layer, or A step of forming a hole transport layer on the second electrode, The steps include forming a light-absorbing layer of a perovskite compound on the hole transport layer, The process of forming an electron transport layer on the light absorption layer, The step includes forming a first electrode on the electron transport layer, A method for producing a solar cell, characterized in that the step of forming the hole transport layer and / or the step of forming the electron transport layer involves adding a solution containing a polyamino acid obtained by polymerizing amino acids having charged side chains of reactive functional groups.

3. The method for producing a solar cell according to claim 1 or 2, wherein the polyamino acid is a polymer with a molecular weight of 1,000 to 100,000.

4. The method for producing a solar cell according to claim 1 or 2, wherein the polyamino acid is a polymer with a molecular weight of 2,000 to 5,000.

5. The method for producing a solar cell according to claim 1 or 2, wherein the polyamino acid is polyarginine or polylysine.

6. A method for manufacturing a solar cell module, characterized by integrating and modularizing solar cells manufactured by the method for manufacturing solar cells described in claim 1 or 2.

7. Between the electrode and the light-absorbing layer of the perovskite compound, there is a charge transport layer consisting of a hole transport layer or an electron transport layer. (1) A buffer layer between the light absorption layer and the charge transport layer, or (2) As for the composition of the charge transport layer, A solar cell characterized by containing an organic compound having a polymer structure of an amino acid having at least a charged side chain of a reactive functional group.

8. The solar cell according to claim 7, wherein the amino acid of the organic compound is an amino acid having a basic charged side chain.

9. The solar cell according to claim 7 or 8, wherein the organic compound is a polymer having a molecular weight of 1,000 to 100,000.

10. The solar cell according to claim 7 or 8, wherein the organic compound is a polymer with a molecular weight of 2000 to 5000.

11. The solar cell according to claim 7 or 8, wherein the organic compound is polyarginine or polylysine.

12. The solar cell according to claim 7 or 8, wherein the charge transport layer is a hole transport layer.

13. A solar cell module characterized by the integration and modularization of the solar cells described in claim 7 or 8.

14. A transport device characterized by comprising the solar cell described in claim 7 or 8.

15. An electrical appliance characterized by comprising a solar cell according to claim 7 or 8.

16. A structure characterized by comprising the solar cell described in claim 7 or 8.

Images