Method for manufacturing solar battery cell, method for manufacturing solar battery module, solar battery cell, and solar battery module

Abstract

This method for manufacturing a solar battery cell (100) comprises: a step for forming a hole transport layer (20) on a first electrode (10); a step for forming a light absorption layer (30) including a perovskite layer on the hole transport layer (20); a step for forming a hybrid electron transport layer (40) on the light absorption layer (30); and a step for forming a second electrode (50) on the hybrid electron transport layer (40), wherein in the step for forming the hybrid electron transport layer (40), a solution containing an inorganic substance is added to a solution containing an organic substance. A solar battery cell (100) comprises a first electrode (10), a hole transport layer (20), a light absorption layer (30) including a perovskite layer, a hybrid electron transport layer (40), and a second electrode (50), wherein the hybrid electron transport layer (40) contains an organic substance and an inorganic substance.

Description

Manufacturing method of solar cell, manufacturing method of solar cell module, solar cell and solar cell module

[0001] The present disclosure relates to a method for manufacturing a solar cell and a solar module having a light absorption layer including a perovskite layer, and to the solar cell and solar module.

[0002] Solar cells having a light absorbing layer containing a perovskite layer have been disclosed.

[0003] For example, Patent Document 1 discloses an inverted thick-film two-dimensional hybrid perovskite solar cell that is insensitive to film thickness.

[0004] Special Publication No. 2021-523552

[0005] However, a problem with solar cells with a light-absorbing layer containing a perovskite layer is the difference in the energy level of the conduction band between the light-absorbing layer and the electron transport layer, which has a lower energy level at the conduction band than the light-absorbing layer. This results in a decrease in carrier extraction efficiency due to defect level trapping in the inorganic material layer, resulting in a decrease in conversion efficiency (photoelectric conversion efficiency). Meanwhile, in terms of durability, the penetration of water molecules into the light-absorbing layer decomposes the perovskite structure and causes large amounts of PbI to precipitate, reducing durability.

[0006] Therefore, the present disclosure provides a method for manufacturing a solar cell and a solar module, which can improve conversion efficiency and durability, as well as a solar cell and a solar module.

[0007] A method for manufacturing a solar cell according to one aspect of the present disclosure includes the steps of forming a hole transport layer on a first electrode, forming a light absorbing layer including a perovskite layer on the hole transport layer, forming a hybrid electron transport layer on the light absorbing layer, and forming a second electrode on the hybrid electron transport layer, wherein the step of forming the hybrid electron transport layer includes adding a solution containing an inorganic substance to a solution containing an organic substance.

[0008] A method for manufacturing a solar cell module according to one aspect of the present disclosure is characterized in that solar cells manufactured by a method for manufacturing a solar cell are integrated and modularized.

[0009] A solar cell according to one aspect of the present disclosure includes a first electrode, a hole transport layer formed on the first electrode, a light absorbing layer formed on the hole transport layer and including a perovskite layer, a hybrid electron transport layer formed on the light absorbing layer, and a second electrode formed on the hybrid electron transport layer, wherein the hybrid electron transport layer contains an organic material and an inorganic material.

[0010] A solar cell module according to one aspect of the present disclosure is a solar cell module in which solar cells are integrated and modularized, and is characterized in that the first electrode is a transparent conductive substrate.

[0011] According to the present disclosure, it is possible to improve the conversion efficiency and durability of solar cells.

[0012] FIG. 1 is a schematic cross-sectional view of a solar cell according to the present embodiment. FIG. 2 is a cross-sectional view showing a light absorbing layer and a hybrid electron transport layer in the solar cell shown in FIG. 1. FIG. 3 is a graph showing energy levels in the inorganic and organic layers of the light absorbing layer and the hybrid electron transport layer. FIG. 4 is an explanatory diagram for explaining the energy level of the lower end of the conduction band and the energy level of the upper end of the valence band. FIG. 5 is a schematic cross-sectional view of a solar cell module including a solar cell according to the present embodiment. FIG. 6A is a schematic cross-sectional view of a solar cell module including a solar cell (variation 1) according to the present embodiment. FIG. 6B is a schematic cross-sectional view of a solar cell module including a solar cell (variation 2) according to the present embodiment. FIG. 7 is a diagram superimposing a schematic cross-sectional view of one solar cell included in the solar cell module shown in FIG. 5 and an equivalent circuit of the solar cell. FIG. 8 is an equivalent circuit of the solar cell module. FIG. 9 is a process diagram showing an example of a manufacturing process for a solar cell according to the present embodiment. FIG. 10 is an explanatory diagram for explaining an example of a manufacturing process for forming a light absorbing layer by applying and drying a perovskite compound solution.

[0013] Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. Note that the present embodiments described below do not unnecessarily limit the content of the present disclosure as defined in the claims, and not all of the configurations described in the present embodiments are necessarily essential to the solutions of the present disclosure. Furthermore, for illustrative purposes, the light incident side is expressed as the lower side and the side opposite the light incident side as the upper side. However, this is for convenience and does not affect the installation direction or the recommended installation direction. The present disclosure can be applied even if the top and bottom are reversed as long as there is no contradiction. In other words, the present disclosure is valid even if the light incident side and the side opposite the light incident side are reversed as long as there is no contradiction. In the following description, unless otherwise specified, identical components are generally designated by the same reference numerals, and their names and functions are also the same. Therefore, in such cases, detailed descriptions thereof will not be repeated.

[0014] First Embodiment 1. Solar Cell Fig. 1 is a schematic cross-sectional view of a solar cell 100 according to this embodiment. As shown in Fig. 1, the solar cell 100 according to this embodiment includes a hole transport layer 20, a light absorbing layer 30 containing a perovskite compound, and a hybrid electron transport layer 40, which are arranged in this order. In this example, the solar cell 100 includes a first electrode 10, a hole transport layer 20 formed on the first electrode 10, a light absorbing layer 30 formed on the hole transport layer 20, a hybrid electron transport layer 40 formed on the light absorbing layer 30, and a second electrode 50 formed on the hybrid electron transport layer 40. The first electrode 10 is in contact with the hole transport layer 20, the hole transport layer 20 is in contact with the light absorbing layer 30, the light absorbing layer 30 is in contact with the hybrid electron transport layer 40, and the hybrid electron transport layer 40 is in contact with the second electrode 50. Each component is described in detail below. In the present embodiment, the first electrode 10 is in contact with the hole transport layer 20, the hole transport layer 20 is in contact with the light absorbing layer 30, the light absorbing layer 30 is in contact with the hybrid electron transport layer 40, and the hybrid electron transport layer 40 is in contact with the second electrode 50. However, this does not exclude the case where they are not in contact with each other and another layer is interposed between them.

[0015] [First Electrode] For example, a transparent conductive substrate can be used for the first electrode 10. The first electrode 10 includes a transparent substrate 11 and a transparent conductive film 12, as shown in FIG.

[0016] (Transparent Substrate) The transparent substrate 11 is the substrate of the solar cell 100 and is the same as or includes the base or substrate. It is made of a transparent material. The transparent substrate 11 is disposed on the light-receiving side of the solar cell 100. Furthermore, during the manufacturing process of the solar cell 100, the hole transport layer 20, the light absorption layer 30, and the like are laminated on the first electrode 10. Note that "transparent" means that it transmits light, but does not exclude materials that reflect or absorb light even slightly. It is sufficient that it is disposed on the light-receiving side of the solar cell and can transmit light appropriately, and can be considered synonymous with being disposed on the light-receiving side of the solar cell. Therefore, being disposed on at least the light-receiving side can be considered transparent. In other words, a transparent substrate means a substrate disposed on the light-receiving side of the solar cell.

[0017] Examples of materials for the transparent substrate 11 include transparent glass (more specifically, soda lime glass, alkali-free glass, etc.) and transparent resins such as heat-resistant organic films.

[0018] When the material of the transparent substrate 11 is a transparent resin such as an organic film, the solar cell 100 may have a barrier layer on the transparent substrate 11. In this way, it is possible to prevent moisture and the like from penetrating into the light absorbing layer 30.

[0019] The transparent substrate 11 on the light-receiving surface side has a thickness of approximately 300 μm to 1500 μm. This reduces the risk of moisture and the like penetrating the light-absorbing layer 30 and reducing the conversion efficiency and durability of the solar cell 100. On the other hand, layers such as the second electrode 50 on the non-light-receiving surface side of the light-absorbing layer 30 are thin, at 50 μm to less than 300 μm, and therefore there is a high risk of moisture and the like penetrating the light-absorbing layer 30 and reducing the conversion efficiency and durability of the solar cell 100.

[0020] Therefore, the solar cell 100 according to this embodiment includes the hybrid electron transport layer 40. This effectively prevents a decrease in the conversion efficiency and durability of the solar cell 100, and improves the conversion efficiency and durability, as will be described later.

[0021] (Transparent Conductive Film) The transparent conductive film 12 corresponds to the anode of the solar cell 100. Examples of materials constituting the transparent conductive film 12 include transparent conductive materials (particularly, transparent conductive oxides (TCOs)) and non-transparent conductive materials. Examples of transparent conductive materials include copper iodide (CuI), 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 term "film" does not specify thickness or width, and includes patterned or island-shaped films and films with portions of different thicknesses. A film is preferably a member with a substantially uniform thickness.

[0022] [Hole Transport Layer] The hole transport layer 20 has a function of transporting holes generated in the light absorption layer 30. A layer having a function of blocking electrons generated in the light absorption layer 30 is preferable. The material constituting the hole transport layer 20 is a material having an energy level (Eebc) at the bottom of the conduction electron band that is 0.5 eV or more higher (Eebc≧Eopc+0.5 eV) than the energy level (Eopc) at the bottom of the conduction electron band of the perovskite compound 7. Specific examples of hole transport materials constituting the hole transport layer 20 include organic hole transport materials and inorganic hole transport materials. Examples of organic hole transport materials include Spiro-MeOTAD [chemical name: 2,2′,7,7′-Tetrakis-(N,N-di-4-methoxyphenylamino)-9,9′-spirobifluorene], chemical formula: C 81 H 68 N4O8, PTAA Chemical name: (Poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine]) Chemical formula: [C6H4N(C6H2(CH3)3)C6H4] n) and the like. Examples of inorganic hole transport materials include carbon nanotubes, cuprous oxide (CuO), zinc sulfide (ZnS), nickel oxide (NiO), and copper thiocyanate (CuSCN), among which CuO, ZnS, or NiO are preferably used. Examples of carbon nanotubes include multi-walled carbon nanotubes (MWCNT) and single-walled carbon nanotubes (SWCNT). As long as a solar cell has a photoelectric conversion function, it is self-evident that the hole transport layer has a hole transport function as long as it is located on the hole transport side of the perovskite layer, and confirmation is not required. In other words, the hole transport layer refers to a layer that is located on the hole transport side of the perovskite compound. Note that the term "layer" does not specify thickness or width, and includes patterned or island-shaped layers and layers with portions of different thicknesses. The layer is preferably a member with a substantially uniform thickness.

[0023] [Light-Absorbing Layer] The light-absorbing layer 30 is a layer that absorbs light and generates electrons and holes, and contains a perovskite compound. The thickness of the light-absorbing layer 30 is preferably 500 nm or more and 2 μm or less, and more preferably 700 nm or more and 800 nm or less.

[0024] The perovskite compound contained in the light-absorbing layer 30 is preferably composed of a compound (perovskite compound) represented by the general formula: ABX3 (1). However, while the composition ratio of each element is preferably 1:1:3, it is not necessarily 1:1:3. The content of each element may vary as appropriate, and each constituent element does not necessarily have to be a single type. As long as the light-absorbing layer has photoelectric conversion function, the degree of freedom in the composition as described above is maintained. In general formula (1), A is an organic molecule (including an organic group or an organic cation), an inorganic atom or molecule (including an inorganic group or an 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 a chalcogen anion). In general formula (1), the three Xs may be the same or different from each other.

[0025] When contained in a light absorbing layer, a perovskite compound can absorb light and convert it into electricity, and this fact should be taken into consideration. That is, a perovskite compound can be confirmed by, for example, detecting organic molecules, metal atoms, and halogen atoms. Furthermore, a perovskite compound can be confirmed by detecting elements corresponding to A, B, and X, as long 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, carbon, nitrogen, hydrogen, a metal element, and a halogen element or chalcogen element can be detected. Alternatively, a perovskite compound can be confirmed by detecting A, B, and X, for example, by detecting inorganic atoms, a metal atom, and a halogen atom. Furthermore, a perovskite compound can be confirmed by detecting elements corresponding to A, B, and X, as long as the light absorbing layer has a photoelectric conversion function. For example, cesium or rubidium is suitable as the inorganic atom, and therefore, cesium or rubidium, a metal element, and a halogen or chalcogen can be detected. Furthermore, the fact that the light absorbing layer 30 is a perovskite compound does not necessarily mean that it has a crystalline structure, since it is a natural consequence that the light absorbing layer must have a crystalline structure in order to have a photoelectric conversion function.The light absorbing layer 30 may contain compounds other than perovskite compounds.

[0026] The light-absorbing layer 30 may contain an organic-inorganic hybrid compound. An organic-inorganic hybrid compound refers to a compound containing an inorganic material and an organic material. Solar cells using perovskite compounds, which are organic-inorganic hybrid compounds, are also called organic-inorganic hybrid solar cells. "Organic" typically refers to a material composed of multiple carbon atoms. Note that graphite, graphene, carbon nanowires, carbon nanofibers, carbon nanotubes, and carbon materials such as carbon and carbon black that function as electrodes are not considered organic. In other words, organic refers to materials that contain multiple carbon atoms as one of their constituent elements, excluding carbon materials such as graphite. "Inorganic" refers to materials that are not organic. In other words, organic-inorganic hybrid compounds include materials that contain multiple carbon atoms as one of their constituent elements, but also materials that do not contain multiple carbon atoms as constituent elements, such as metal atoms, halogen atoms, or chalcogen atoms.

[0027] In general formula (1), examples of the organic molecule represented by A include alkylamine, alkylammonium, and nitrogen-containing heterocyclic compounds. In the perovskite compound (1), the organic molecule represented by A may be only one type of organic molecule, or may be two or more types of organic molecules.

[0028] 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.

[0029] The alkylammonium is an ionized product of the alkylamine. Examples of the alkylammonium include methylammonium (CHNH), 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.

[0030] Examples of the nitrogen-containing heterocyclic compound include imidazole, azole, pyrrole, aziridine, azirine, azetidine, azeto, azole, imidazoline, and carbazole. The nitrogen-containing heterocyclic compound may be an ionized compound. As the nitrogen-containing heterocyclic compound that is an ionized compound, it is preferable to use phenethylammonium.

[0031] 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.

[0032] In general formula (1), examples of the metal atom 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 the perovskite compound, the metal atom represented by B may be only one type of metal atom, or may be two or more types of metal atoms. From the viewpoint of improving the light absorption properties and charge generation properties of the perovskite compound, the metal atom represented by B is preferably a lead atom.

[0033] In general formula (1), examples of the halogen atom represented by X include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. In the 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. Specifically, of the three Xs, it is preferable that at least one X represents an iodine atom, and it is more preferable that all three Xs represent iodine atoms.

[0034] As the perovskite compound, it is preferable to use a compound represented by the general formula "CH3NH3PbX3 (wherein X represents a halogen atom)," and it is more preferable to use CH3NH3PbI3. By using a compound represented by the general formula "CH3NH3PbX3" (particularly CH3NH3PbI3) as the perovskite compound, it is possible to more efficiently generate conduction electrons and holes in the perovskite compound, and as a result, it is possible to further improve the conversion efficiency of the solar cell 100.

[0035] The perovskite layer contains a perovskite material having an energy level of the valence band maximum (VBM) in the range of −5.1 eV to −5.7 eV and an energy level of the conduction band minimum (CBM) in the range of −3.5 eV to −4.0 eV. Such a perovskite layer can be suitably used in the solar cell 100 according to the present embodiment. Here, the energy levels of the valence band maximum and the conduction band minimum are negative because the vacuum level is set to 0 and energy levels below this vacuum level are expressed as negative values. However, in actual measurements, electron affinity and ionization energy are measured. Therefore, the absolute value of the difference between the vacuum level and the energy level of the bottom of the conduction band can be rephrased as the electron affinity (or its absolute value), and the absolute value of the difference between the vacuum level and the energy level of the top of the valence band can be rephrased as the ionization potential (or its absolute value). Here, the energy levels of the bottom of the conduction band and the top of the valence band are generally expressed as deep and shallow to indicate whether they are high or low. When referring to the energy level of the bottom of the conduction band or the energy level of the top of the valence band, "deep" means that the corresponding electron affinity or ionization energy is large or far from the vacuum level, and when referring to the energy level of the bottom of the conduction band or the energy level of the top of the valence band, "shallow" means that the corresponding electron affinity or ionization energy is small or close to the vacuum level.

[0036] [Hybrid Electron Transport Layer] The hybrid electron transport layer 40 has the function of transporting electrons generated in the perovskite layer (hereinafter sometimes referred to as the perovskite compound) contained in the light absorbing layer 30. It is preferable that the hybrid electron transport layer 40 has the function of blocking holes generated in the perovskite compound. The hybrid electron transport layer 40 preferably contains a material that easily moves electrons generated in the perovskite compound to the second electrode 50. As long as the solar cell has a photoelectric conversion function, it is self-evident that the electron transport layer has the function of electron transport as long as it is located on the electron transport side of the perovskite layer, and no confirmation is required. In other words, the electron transport layer means one that is located on the electron transport side of the perovskite compound.

[0037] As shown in FIG. 1 , the hybrid electron transport layer 40 contains an organic material 41 and an inorganic material 42. Here, "hybrid" refers to the inclusion of both organic and inorganic materials. This prevents moisture, oxygen, and the like from penetrating into the light absorbing layer 30 from the second electrode 50 side, thereby improving the conversion efficiency and durability of the solar cell 100. Note that "organic" or "organic material" typically refers to a material composed of multiple carbon atoms. Note that graphite, graphene, carbon nanowires, carbon nanofibers, carbon nanotubes, and carbon materials such as carbon and carbon black that function as electrodes are not specifically considered organic or organic materials. In other words, organic or organic materials refer to materials that contain multiple carbon atoms as one of their constituent elements, excluding carbon materials such as graphite. "Inorganic" or "inorganic material" refers to materials that are not organic. In other words, a hybrid electron transport layer refers to an electron transport layer that contains multiple carbon atoms as one of its constituent elements, but also contains materials that do not contain multiple carbon atoms as constituent elements, such as metal atoms, halogen atoms, chalcogen atoms, or metal chalcogenides.

[0038] Fig. 2 is a cross-sectional view showing the light absorbing layer 30 and the hybrid electron transport layer 40 in the solar cell 100 shown in Fig. 1. The particles of the inorganic material 42 are generally denser and have a higher density than the particles of the organic material 41. Therefore, as shown in Fig. 2, it is possible to further prevent moisture, oxygen, and the like from penetrating into the light absorbing layer 30 from the second electrode 50 side, thereby improving the conversion efficiency and durability of the solar cell 100.

[0039] The organic material 41 preferably contains an organic n-type material (an electron transport material of the organic material 41). This can increase the electron extraction efficiency, improve the fill factor (FF) characteristics, and suppress recombination. This can also reduce the risk of moisture intrusion, further improving the conversion efficiency and durability of the solar cell 100.

[0040] Furthermore, it is preferable that the organic n-type material contains one or more selected from the group consisting of PCBM, BCP, and C60. In this way, a protective layer is formed on the light absorbing layer 30 when the electron transport layer is formed, which further reduces the risk of moisture penetration, and therefore the conversion efficiency and durability of the solar cell 100 can be further improved.

[0041] The inorganic material 42 preferably contains n-type inorganic oxide particles (electron transport material of the inorganic material 42). This can increase the electron extraction efficiency, improve the fill factor (FF) characteristics, and suppress recombination. This can also reduce the risk of moisture intrusion, further improving the conversion efficiency and durability of the solar cell 100.

[0042] 3 is a graph showing energy levels in the light absorbing layer 30, the inorganic material 42 layer, and the organic material 41 layer of the hybrid electron transport layer 40. The recombination effect of electrons and holes is one of the causes of a decrease in the open circuit voltage of the solar cell 100. Suppressing the recombination effect improves the open circuit voltage and improves the device performance.

[0043] The solar cell 100 according to this embodiment includes an organic n-type material and inorganic oxide n-type particles. When the energy level of the conduction band minimum of the perovskite layer is Ec1, the energy level of the conduction band minimum of the inorganic oxide n-type particles is Ec2, and the energy level of the conduction band minimum of the organic n-type material is Ec3, the relationship |Ec1| < |Ec2| < |Ec3| can be satisfied. As a result, as shown in FIG. 3 , the energy levels of the conduction band minimums of the inorganic oxide n-type particle layer and the light absorbing layer 30 can be smoothly connected, improving electron extraction efficiency. Therefore, the energy levels facilitate electron shift, forming a smoother energy level than conventional organic films, thereby improving electron transport efficiency. Specifically, as shown in FIG. 3 , the light absorbing layer 30 (PVK) first absorbs light energy and generates electrons and holes. Also, when the electron energy level moves from -3.9 to -4.17 (PVK to PC 61 When the energy moves from -3.9 to -4.1 (moving from PVK to ZnO), the energy absorbed by the light absorbing layer 30 (PVK) is lower than the energy consumed when the energy moves from -3.9 to -4.17. Therefore, the number of electrons that move increases, and the organic material 41 (PC) of the hybrid electron transport layer 40 61 More electrons flow into the B-M layer, thus smoothing out the energy levels.

[0044] Furthermore, since the solar cell 100 according to the present embodiment includes an organic n-type material and inorganic oxide n-type particles, when the energy level of the upper end of the valence band of the perovskite layer is Ev1, the energy level of the upper end of the valence band of the inorganic oxide n-type particles is Ev2, and the energy level of the upper end of the valence band of the organic n-type material is Ev3, the relationship |Ev1|<|Ev2|<|Ev3| does not hold, i.e., the relationship |Ev1|≧|Ev2| or |Ev2|≧|Ev3| can be satisfied. This makes it difficult for holes to shift in the energy levels, and when the relationship |Ev1|≧|Ev2| is satisfied, holes generated in the light absorbing layer 30 can be efficiently blocked. Furthermore, when the relationship |Ev2|≧|Ev3| is satisfied, holes generated in the light absorbing layer 30 can be even more efficiently blocked, as shown in FIG. 3 .

[0045] Furthermore, the n-type inorganic oxide particles preferably contain one or more selected from the group consisting of zinc oxide (ZnO), copper oxide (CuO), and tin oxide (SnO2). In this way, a protective layer is formed on the light absorbing layer 30 when the electron transport layer is formed, which further reduces the risk of moisture penetration and therefore improves the conversion efficiency and durability of the solar cell 100.

[0046] FIG. 4 is an explanatory diagram illustrating the energy level of the conduction band minimum and the energy level of the valence band maximum. As shown in FIG. 4, the inorganic oxide n-type particles preferably have an energy level of the conduction band minimum that is the same as or deeper than that of the light absorbing layer 30. This allows for a smooth transition between the energy levels of the conduction band minimum of the inorganic material 42 layer (inorganic electron transport layer) of the hybrid electron transport layer 40 and the light absorbing layer 30, thereby improving the electron extraction efficiency. Furthermore, by having an energy level of the conduction band minimum of the inorganic material 42 layer of the hybrid electron transport layer 40 that is deeper than that of the light absorbing layer 30, the electron transport efficiency can be improved.

[0047] 4, the organic n-type material preferably has the same energy level at the bottom of the conduction band as the inorganic oxide n-type particles or deeper than the inorganic oxide n-type particles. This allows for a smooth transition between the energy levels at the bottom of the conduction band of the inorganic material 42 layer (inorganic electron transport layer) and the organic material 41 layer (organic electron transport layer), improving the electron extraction efficiency. Furthermore, by having a deeper energy level at the bottom of the conduction band of the organic material 41 layer than the inorganic material 42 layer, the electron transport efficiency can be improved.

[0048] The thickness of the hybrid electron transport layer 40 is preferably 80 nm to 200 nm. If the thickness of the hybrid electron transport layer 40 is less than 80 nm, the risk of moisture penetration may increase. On the other hand, if the thickness is more than 200 nm, the risk of moisture penetration decreases, but the electrical resistance may increase.

[0049] Furthermore, if the organic material 41 contains an organic n-type material and the inorganic material 42 contains inorganic oxide n-type particles, a protective layer is formed on the light absorption layer 30 when the electron transport layer is formed, which further reduces the risk of moisture penetration and further improves the conversion efficiency and durability of the solar cell 100.

[0050] As shown in FIGS. 1 and 2, the hybrid electron transport layer 40 preferably has an inorganic material 42 formed on the lower side, which is on the light absorption layer 30 side. In this way, holes generated in the perovskite compound can be efficiently blocked. The inorganic material 42 of the hybrid electron transport layer 40 has a higher density than the organic material 41. The solution density of the organic material 41 of the hybrid electron transport layer 40 is 5 mg / cm. 3 ~70 mg / cm 3 For example, when the organic substance 41 is PC 61 For BM, the density is 5 mg / cm 3 ~30 mg / cm 3 and organic matter 41 is PC 71 In the case of BM, the density is 20 mg / cm 3 ~70 mg / cm 3 On the other hand, the density of the inorganic material 42 of the hybrid electron transport layer 40 is 1 g / cm 3~10g / cm 3 For example, when the inorganic material 42 is ZnO, the density is 5.61 g / cm 3 is.

[0051] As shown in FIGS. 1 and 2, the inorganic material 42 of the hybrid electron transport layer 40 may be unevenly distributed in the organic material 41 .

[0052] As shown in FIGS. 1 and 2 , a layer of inorganic material 42 is preferably formed near the lower end of the hybrid electron transport layer 40. This prevents moisture from entering, thereby improving the conversion efficiency and durability of the solar cell 100. Furthermore, the amount of inorganic material 42 near the upper end of the hybrid electron transport layer 40 is preferably smaller than that near the lower end. This further prevents moisture from entering, thereby improving the conversion efficiency and durability of the solar cell 100. Furthermore, it is preferable that no inorganic material 42 be formed near the upper end of the hybrid electron transport layer 40. This further prevents moisture from entering, thereby improving the conversion efficiency and durability of the solar cell 100. Here, "near" refers to a range of 20 nm. Furthermore, "no inorganic material is provided" can be determined as "no inorganic material is provided" if no inorganic material is observed within a 200 nm wide range in a direction perpendicular to the stacking direction when cross-sectional observation is performed using an apparatus such as energy dispersive X-ray spectroscopy (SEM-EDX).

[0053] Furthermore, the film thickness of the inorganic material 42 is preferably 50 nm to 100 nm. This allows the inorganic oxide n-type particles to be unevenly precipitated on the light absorbing layer 30 side when the hybrid electron transport layer 40 is coated and dried, thereby effectively preventing moisture penetration and improving the conversion efficiency and durability of the solar cell 100. If the film thickness of the inorganic material 42 is less than 50 nm, the risk of moisture penetration may increase. On the other hand, if it is thicker than 100 nm, the risk of moisture penetration is reduced, but the overall thickness of the cell may increase, which may result in increased electrical resistance and reduced charge conductivity.

[0054] Furthermore, the average particle size of the inorganic substance 42 is preferably 10 nm to 50 nm. Here, the average particle size of the inorganic substance 42 is defined as the average particle size of 20 adjacent inorganic substances 42 in a 400 nm-wide cross-sectional observation image obtained by cross-sectional observation, or as many as possible for the inorganic substance 42 to be observed in the cross-sectional observation image, whichever is smaller. Furthermore, the particle size can be defined as the diameter of a circle having an area equivalent to the cross-sectional area of ​​the inorganic substance 42 in the cross-sectional observation image. Inorganic substances 42 having an average particle size of less than 10 nm are expensive and therefore increase costs. Furthermore, inorganic substances 42 having an average particle size of less than 10 nm may be at a greater risk of moisture penetration. On the other hand, inorganic substances 42 having an average particle size of more than 50 nm are difficult to fabricate with a thickness of 50 nm to 100 nm, which is the preferred thickness of the inorganic substance 42 described above.

[0055] Preferably, the inorganic material 42 contains n-type inorganic oxide particles with a close-packed structure. This makes the crystals of the inorganic material 42 denser, reducing the risk of moisture intrusion and improving the conversion efficiency and durability of the solar cell 100. The inorganic material 42 is not limited to being dense, but may also be porous. "Dense" refers to materials such as dense, compact, and compacted, and includes the same or equivalent terms. "Porous" refers to materials such as porous, porous, and mesoporous, and includes the same or equivalent terms. "Porous" refers to materials that can contain materials other than those constituting the pores in the voids. "Dense" refers to materials with extremely small voids. In other words, a dense material refers to a material in which the maximum void width is less than 5 nm when observed through a cross-section by SEM. Unless otherwise stated, in this disclosure, SEM observations can be performed on cross-sectional SEM images with a width of 400 nm, and confirmation is sufficient. For example, if the maximum width of the voids in a single 400 nm-wide cross-sectional SEM image is less than 5 nm, the layer or the layer itself can be said to be dense. Preferably, a dense material means one that cannot contain anything other than those constituting the dense material in the voids, or one that does not have any portions where anything other than those constituting the dense material is continuously present throughout the thickness of the dense material portion. In other words, if a dense material cannot be confirmed by the maximum width of the voids, it is sufficient that observation by SEM or EDX shows that there are no portions where anything other than those constituting the dense material exists throughout the thickness of the inorganic material. In the present disclosure, unless otherwise contradictory, SEM observation can be performed by observing and confirming a 400 nm-wide cross-sectional SEM (or EDX) image. For example, if there are no portions where anything other than those constituting the dense material exists throughout the thickness of the inorganic material in observation by SEM or EDX of a single 400 nm-wide cross-section, the inorganic material can be said to be dense. It should be noted that the definition of a dense material as one having extremely small voids takes precedence, and in cases where this cannot be confirmed, the above preferred definition can be applied.

[0056] [Second Electrode] The second electrode 50 corresponds to the cathode of the solar cell 100. Examples of materials constituting the second electrode 50 include metals, transparent conductive inorganic materials, conductive particles, and conductive polymers (particularly, transparent conductive polymers). Examples of metals include nickel (Ni), gold (Au), silver (Ag), platinum (Pt), and palladium (Pd). Examples of transparent conductive inorganic materials include copper iodide (CuI), indium tin oxide (ITO), tin oxide (SnO), fluorine-doped tin oxide (FTO), aluminum-doped zinc oxide (AZO), indium zinc oxide (IZO), and gallium-doped zinc oxide (GZO). Examples of conductive particles include silver nanowires and carbon nanofibers. Examples of transparent conductive polymers include polymers containing poly(3,4-ethylenedioxythiophene) and polystyrene sulfonic acid (PEDOT / PSS). Furthermore, a carbon material such as graphite can also be used for the second electrode 50. It is desirable to provide each of the electrode (first electrode or second electrode) and the hole transport layer or electron transport layer, but it is not necessary that all of them be provided, and it is acceptable for any of them to be omitted as long as the solar cell 100 has a photoelectric conversion function.

[0057] In order to efficiently apply a built-in potential to the light absorption layer 30, it is desirable that the material of the second electrode 50 be a metal having a work function Φ≧5.0 eV. This results in a structure in which holes are extracted from the transparent conductive film 12 on the transparent substrate 11 side and electrons are extracted from the second electrode 50 side, and a smooth flow of electrons can be achieved at the interface between the hybrid electron transport layer 40 on the electron extraction side and the second electrode 50, thereby realizing a highly efficient solar cell 100.

[0058] As described above, according to this embodiment, the conversion efficiency and durability of the solar cell 100 can be improved.

[0059] Second Embodiment 2. Solar Cell Module and Manufacturing Method of Solar Cell Module Fig. 5 is a schematic cross-sectional view of a solar cell module 1000 (series-connected solar cell) including solar cell 100 according to this embodiment. As shown in Fig. 5, the solar cell module 1000 according to this embodiment is produced by integrating the above-described solar cell 100. As described above, by forming the hybrid electron transport layer 40 in the solar cell 100, the conversion efficiency and durability of the solar cell 100 can be improved.

[0060] 5 , the solar cell module 1000 according to the present embodiment includes a transparent substrate 11, a transparent conductive film 12 provided on the transparent substrate 11, a hole transport layer 20 provided on the transparent conductive film 12, a light absorbing layer 30 provided on the hole transport layer 20, a hybrid electron transport layer 40 provided on the light absorbing layer 30, a second electrode 50 provided on the hybrid electron transport layer 40, a second barrier layer 62 provided on the second electrode 50, and a back substrate 64 provided on the second barrier layer 62. The solar cell module 1000 shown in FIG. 5 is a solar cell module 1000 in which the transparent substrate 11 is transparent glass.

[0061] 6A and 6B are schematic cross-sectional views of a solar cell module 1100 including a solar cell 100 (variations 1 and 2) according to the present embodiment, in which the transparent substrate 11 is made of a transparent resin such as an organic film. As shown in FIGS. 6A and 6B , the solar cell module 1100 according to the present embodiment includes a transparent substrate 11, a first barrier layer 61 provided on the transparent substrate 11, a transparent conductive film 12 provided on the first barrier layer 61, a hole transport layer 20 provided on the transparent conductive film 12, a light absorbing layer 30 provided on the hole transport layer 20, a hybrid electron transport layer 40 provided on the light absorbing layer 30, a second electrode 50 provided on the hybrid electron transport layer 40, a second barrier layer 62 provided on the second electrode 50, a third barrier layer 63 provided on the second barrier layer 62, and a back substrate 64 provided on the third barrier layer 63. The first barrier layer 61 is a layer of a material with high gas barrier properties. The second barrier layer 62 is a dense inorganic material layer, and the third barrier layer 63 is a layer made of a material with high gas barrier properties.

[0062] 6A and 6B, the second barrier layer 62 is provided so as to cover the sides of the hybrid electron transport layer 40 and the second electrode 50, and so as to cover the upper part of the second electrode 50. The second barrier layer 62 covers the upper surface and side surfaces of each of the solar cell 100-100.

[0063] 5 , 6A, and 6B , the hybrid electron transport layer 40 covers the top and sides of the light absorbing layer 30. The second electrode 50 covers the top and one side of the hybrid electron transport layer 40. The second electrode 50 extends from the top to the side of the hybrid electron transport layer 40 and connects to the top of the transparent conductive film 12 of the adjacent solar cell 100, thus connecting the adjacent solar cell 100 in series.

[0064] The solar cell modules 1000, 1100 of the present embodiment include a plurality of solar cells 100-100, a first terminal 71, and a second terminal 72, and the plurality of solar cells 100-100 are connected in series. Of the plurality of solar cells 100-100 connected in series, the solar cell 100 at one end is connected to the first terminal 71, and the solar cell 100 at the other end is connected to the second terminal 72. There is no particular limitation on the number of solar cells 100-100 connected in series, as long as there is a plurality.

[0065] The transparent substrate 11 is the substrate of the solar cell modules 1000 and 1100. The transparent substrate 11 may be a glass substrate as shown in Fig. 5 or a transparent organic film as shown in Figs. 6A and 6B. This allows light to enter the interior of the solar cell 100. When the transparent substrate 11 is a flexible organic film, the solar cell module 1100 becomes a flexible solar cell module.

[0066] Specific examples of the material for the organic film that becomes the transparent substrate 11 include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), polyetherimide (PEI), polytetrafluoroethylene (PTFE), 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 that becomes the transparent substrate 11 is preferably 50 μm to 100 μm.

[0067] When the transparent substrate 11 is a transparent organic film, a first barrier layer 61 may be provided on one of the +Y-direction major surfaces of the transparent substrate 11, as shown in FIGS. 6A and 6B . The first barrier layer 61 is a layer made of a material with high gas barrier properties. This prevents internal deterioration of the solar cell 100 due to moisture and oxygen in the air. The first barrier layer 61 is also a layer made of an insulating material. This prevents leakage current. The film thickness of the first barrier layer 61 can be several tens of nanometers to 100 nanometers. This allows the first barrier layer 61 to have light-transmitting properties. Furthermore, the solar cell 100 and the solar cell module 1100 can have flexibility. Specific examples of materials for the first barrier layer 61 include silicon oxide and aluminum oxide. As long as the first barrier layer 61 has gas barrier properties, insulating properties, and light-transmitting properties, other oxides and insulators can also be used as the material for the first barrier layer 61. The first barrier layer 61 can be formed mainly by sputtering or vacuum deposition, for example.

[0068] The transparent conductive film 12 is provided on the transparent substrate 11 (on the first barrier layer 61 in the example shown in FIGS. 6A and 6B ) and constitutes a first electrode 10 for extracting current generated by photovoltaic power of the solar cell 100. The transparent conductive film 12 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). The sheet resistance of the transparent conductive film 12 is preferably 10 Ω / sq or less, and the light transmittance of the transparent conductive film 12 is preferably 30% or more. Examples of methods for forming the transparent conductive film 12 include sputtering and vacuum deposition.

[0069] When a plurality of solar cells 100 are provided on the transparent substrate 11, the transparent conductive film 12 formed on the transparent substrate 11 is divided for each solar cell 100. For example, the solar cell modules 1000 and 1100 shown in FIGS. 5, 6A, and 6B include five solar cells 100, and therefore the transparent conductive film 12 is divided into five transparent conductive films 12. The groove O separating two adjacent transparent conductive films 12 may be filled with a light absorbing layer 30 or the like. The transparent conductive film 12 spans the two adjacent solar cells 100, 100. That is, as shown in FIGS. 5, 6A, and 6B, a hole transport layer 20 is formed on one transparent conductive film 12, and a light absorbing layer 30 is formed on the other transparent conductive film 12.

[0070] A first terminal 71 of the solar cell module 1000, 1100 is provided on the light-receiving surface side of the transparent substrate 11, and a portion of the first terminal 71 penetrates the transparent substrate 11 (the first barrier layer 61 in the example shown in FIGS. 6A and 6B ) and is in contact with or electrically connected to the transparent conductive film 12 at one end of the series-connected solar cell 100. This first terminal 71 can be used to extract current generated by the photovoltaic power of the solar cell module 1000, 1100. An example of a material for the first terminal 71 is a SnZn-based solder paste. Other conductive pastes and materials for the second electrode 50 can also be used as long as they meet the requirements.

[0071] After the transparent conductive film 12 is formed on the transparent substrate 11, an incision (L1) is made in the transparent conductive film 12 by laser scribing in order to separate and form the solar cell 100 on the transparent substrate 11. The wavelength of the laser used is preferably in the infrared region. The incision (L1) is made in the transparent conductive film 12, thereby forming the transparent conductive film 12 having the incision. No incision is made in the transparent substrate 11 (first barrier layer 61 in the example shown in Figures 6A and 6B). For example, a perovskite compound can be formed on the transparent substrate 11 and the transparent conductive film 12 in which the incision (L1) has been made by laser scribing, to form the light absorbing layer 30.

[0072] Examples of organic solvents (contained in the coating liquid) used in the coating method for forming the light absorbing layer 30 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; fluorine-based 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-based solvents such as ethylene glycol and diethylene glycol monomethyl ether. These can be used alone or as a mixed solvent. These solvents may contain water. Among these solvents, non-halogen organic solvents are preferably used from the viewpoint of consideration for the global environment.

[0073] In addition to this, the coating liquid may contain additives such as an antioxidant, a viscoelasticity modifier, a preservative, a curing catalyst, etc. The coating method is not particularly limited, but it is preferable to use, for example, a dip coating method, a spray coating method, a slide hopper coating method, or the like.

[0074] After the light absorbing layer 30 is formed, a cut (L2) is made in a part of the light absorbing layer 30 by laser scribing in order to connect the transparent conductive film 12 of one of two adjacent solar cell 100 to the hybrid electron transport layer 40 and second electrode 50 of the other solar cell 100. The wavelength of the laser used is preferably in the visible light region. For example, the light absorbing layer 30 is formed by making the cut (L2) in the light absorbing layer 30. This laser scribing removes the light absorbing layer 30, but does not remove the transparent conductive film 12 (the first barrier layer 61 in the example shown in FIGS. 6A and 6B ).

[0075] Thereafter, the hybrid electron transport layer 40 is formed, and the second electrode 50 is formed.

[0076] The second electrode 50 is provided on the hybrid electron transport layer 40 and is intended to extract current generated by the photovoltaic power of the light absorbing layer 30 of the solar cell 100. The second electrode 50 is, for example, a metal film with a work function of 5 eV or more. When the second electrode 50 is made of a metal with a deep work function (5 eV or more), a bending of the band structure occurs at the interface between the light absorbing layer 30 and the second electrode 50, which allows for a smooth flow of electrons. The film thickness of the second electrode 50 is preferably 50 nm to 150 nm. The light absorbing layer 30 or the second electrode 50 can be formed by, for example, a sputtering deposition method or a vacuum deposition method.

[0077] After the second electrode 50 is formed, a cut (L3) is made in a portion of the hybrid electron transport layer 40 and the second electrode 50 by laser scribing to form a series connection circuit of adjacent solar cell 100 on the transparent substrate 11. Furthermore, in order to make the second barrier layer 62 function as a varistor, a cut (L3) may be made in the hole transport layer 20, the light absorption layer 30, the hybrid electron transport layer 40, and the second electrode 50. The wavelength of the laser used is preferably in the ultraviolet region. For example, the cut (L3) is made in the hybrid electron transport layer 40 and the second electrode 50, and the hybrid electron transport layer 40 and the second electrode 50 are formed. Furthermore, a cut for forming a varistor can be made. If the portion with the cut (L3) functions as a varistor, the cut can be omitted.

[0078] The second barrier layer 62 is a dense inorganic material layer and is provided so as to cover the side portions of the light absorbing layer 30. The second barrier layer 62 can also be provided so as to cover the entire periphery of the light absorbing layer 30. The second barrier layer 62 can also be provided so as to cover the upper surface of the second electrode 50. The second barrier layer 62 can prevent moisture (such as water vapor) from penetrating the light absorbing layer 30, thereby preventing deterioration of the solar cell 100. Furthermore, because the second barrier layer 62 is a dense inorganic material layer, it is possible to prevent the barrier function of the second barrier layer 62 from being reduced by ultraviolet rays, temperature changes, and the like. The barrier properties against water vapor can also be improved by completely coating the light absorbing layer 30 with the second barrier layer 62, the transparent conductive film 12, the transparent substrate 11, and the like.

[0079] The second barrier layer 62 may also be made of a material that exhibits varistor characteristics. The second barrier layer 62 can be provided so as to be connected to the transparent conductive film 12 and the second electrode 50, so that the second barrier layer 62 and the light absorbing layer 30 are connected in parallel. The varistor characteristics are voltage-current characteristics (current nonlinearity) in which current suddenly begins to flow at a certain constant voltage. There are no particular restrictions on the material that exhibits varistor characteristics, as long as it is a material that can be used in a varistor element.

[0080] The thickness of the second barrier layer 62 can be, for example, 30 nm or more and 100 nm or less. The second barrier layer 62 is formed on the second electrode 50 after laser scribing. The second barrier layer 62 can be formed so as to fill the notch (L3). This allows the periphery and upper surface of the light absorbing layer 30 to be covered with the second barrier layer 62. The second barrier layer 62 can be formed so as to fill the notch. This allows the second barrier layer 62 to be connected to the transparent conductive film 12 and the second electrode 50 so that the second barrier layer 62 and the light absorbing layer 30 are connected in parallel.

[0081] By connecting a part of the second barrier layer 62 in parallel to the light absorption layer 30 as a varistor element structure, it is possible to realize a solar cell 100 that is integrally provided with a bypass diode (varistor of the second barrier layer 62). This makes it possible to prevent a decrease in power generation efficiency due to shadows on the solar cell module 1100 at low cost.

[0082] The second barrier layer 62 may contain, for example, zinc oxide (ZnO) as a main material, and may contain, as additive materials, silicon oxide, aluminum oxide, titanium oxide, etc. The varistor characteristics (I=KVα, K: element-specific constant, α: voltage nonlinearity coefficient) of the second barrier layer 62 between the transparent conductive film 12 and the second electrode 50 are preferably such that α=20 to 60 and the bending point voltage is 2 V or higher.

[0083] The rear substrate 64 is a substrate disposed on the non-light-receiving side, and the light absorbing layer 30 is located between the transparent substrate 11 and the rear substrate 64. The rear substrate 64 may be a substrate of the solar cell modules 1000 and 1100. The rear substrate 64 may be a glass substrate, a transparent organic film, or an opaque organic film.

[0084] When the rear substrate 64 is an organic film, a third barrier layer 63 may be provided on one of the main surfaces of the rear substrate 64, as shown in Figures 6A and 6B. The third barrier layer 63 is a layer made of a material with high gas barrier properties. This makes it possible to prevent deterioration inside the solar cell 100 due to moisture, oxygen, and the like in the air. The third barrier layer 63 is also a layer made of an insulating material. This makes it possible to suppress the flow of leakage current. The film thickness of the third barrier layer 63 can be several tens of nanometers to 100 nanometers. Specific examples of materials for the third barrier layer 63 include silicon oxide and aluminum oxide.

[0085] A second terminal 72 of the solar cell module 1000, 1100 is formed on the organic film that serves as the rear substrate 64, and a portion of the second terminal 72 penetrates the organic film (rear substrate 64) (the third barrier layer 63 in the example shown in FIGS. 6A and 6B ) and is in contact with the second electrode 50 at the other end of the series-connected solar cell 100 or is connected via the second barrier layer 62. The first terminal 71 and the second terminal 72 can be used to extract current generated by photovoltaic power of the solar cell module 1000, 1100. An example of a material for the second terminal 72 is a SnZn-based solder paste. Other conductive pastes and materials for the second electrode 50 can also be used as long as they meet the requirements.

[0086] After forming the second barrier layer 62 (and further forming a third barrier layer 63 on the second barrier layer 62) on the second electrode 50, a back substrate 64 on which a second terminal 72 has been formed is attached to the second barrier layer 62 (third barrier layer 63) via a laminate sheet, followed by heat lamination to complete the solar cell module 1000, 1100 in which a plurality of solar cell cells 100 are connected in series. Holes are drilled in the laminate sheet sandwiched between the second barrier layer 62 and the back substrate 64 (third barrier layer 63) at the locations where the second terminals 72 will be located. This ensures good connection between the second terminals 72 and the second barrier layer 62 during lamination. This forms a varistor between the second electrode 50 and the second terminal 72. Because a high voltage is applied between the second electrode 50 and the second terminal 72 during power generation, the varistor characteristics do not impede current extraction. Alternatively, the second electrode 50 and the second terminal 72 may be in contact with each other.

[0087] The laminate sheet may be a general laminate material, and is preferably a resin film that has high waterproof properties and can be laminated at a temperature of 130° C. or less.

[0088] Fig. 7 is a diagram in which a schematic cross-sectional view of one solar cell 100 included in the solar cell module 1000 shown in Fig. 5 is superimposed on an equivalent circuit of the solar cell 100, and Fig. 8 is an equivalent circuit of the solar cell module 1000. As shown in Figs. 7 and 8, the hole transport layer 20, the light absorption layer 30, and the hybrid electron transport layer 40 can be represented by a current source 82 and a diode 83. In addition, the varistor 81 is connected to the transparent conductive film 12 and the second electrode 50 so as to be connected in parallel with the light absorption layer 30.

[0089] 9 is a process diagram showing an example of a manufacturing process for a solar cell 100 according to this embodiment. As shown in FIG. 9 , the manufacturing method for the solar cell 100 according to this embodiment includes the steps of: forming a hole transport layer 20 on a transparent conductive substrate (first electrode 10) (S1); forming a light absorbing layer 30 including a perovskite layer on the hole transport layer 20 (S2); forming a hybrid electron transport layer 40 on the light absorbing layer 30 (S3); and forming a second electrode 50 on the hybrid electron transport layer 40 (S4).

[0090] In the case of other structures in which an electron transport layer is formed on a first electrode and a light-absorbing layer is formed on the electron transport layer, for example, an electron transport layer coating liquid (electron transport layer solution) is prepared, and the electron transport layer coating liquid is applied by spin coating to a glass substrate on which a fluorine-doped SnO2 conductive film has been vapor-deposited, forming a coating layer, and the coating layer is heated at 350°C to 450°C for approximately 15 minutes to form an electron transport layer on the transparent conductive substrate. In contrast, in the case of the present embodiment in which a hole transport layer 20 is formed on a first electrode 10 and a light-absorbing layer 30 is formed on the hole transport layer 20, for example, a hole transport layer coating liquid (hole transport layer solution) is prepared on a glass substrate on which a fluorine-doped SnO2 conductive film has been vapor-deposited, and the hole transport layer coating liquid is applied by sputtering to form a coating layer, and the coating layer is heated at 150°C to 100°C or less for approximately 10 minutes to form the hole transport layer 20 on the transparent conductive substrate (10). In this way, in this structure, the film can be formed at a lower temperature than in other structures in which an electron transport layer and a light absorption layer are formed in that order on the first electrode, and the solar cell 100 can be manufactured with accordingly less energy.

[0091] Then, the light absorbing layer 30 including a perovskite layer is formed on the hole transport layer 20 (S2).

[0092] 10 is an explanatory diagram illustrating an example of a manufacturing process for applying and drying a perovskite compound solution to form the light absorbing layer 30. In Fig. 10, A indicates a solution containing an inorganic substance 42, B indicates a solution containing an organic substance 41, and C indicates a solution obtained by adding a solution containing an inorganic substance 42 to a solution containing an organic substance 41.

[0093] The light absorbing layer forming step (S2) in the method for manufacturing the solar cell 100 includes a step of forming a coating film by applying a coating liquid containing a perovskite compound onto the hole transport layer 20 provided on the transparent conductive substrate (10), and a drying step of drying the coating film thus formed.

[0094] The coating method for applying the coating liquid onto the hole transport layer 20 is not particularly limited, but can be screen printing, dip coating, inkjet printing, slit die coating, or the like. The coating environment is preferably maintained in a low-humidity environment, and may be sealed with an inert gas such as nitrogen gas. A laminate of the transparent substrate 11, transparent conductive film 12, and hole transport layer 20 may be arranged so that the transparent conductive substrate (10) is located on the ground side (-Y) and the hole transport layer 20 is located on the top side (+Y), and the coating liquid may be applied onto the hole transport layer 20 from the top side of the laminate. This prevents dripping from the slit die. Furthermore, the coffee ring effect can be suppressed during the drying step.

[0095] In the drying process, the solvent contained in the coating film evaporates, which increases the concentration of the perovskite compound in the coating film, and crystallization of the perovskite compound progresses from the hole transport layer 20 side.

[0096] Next, the hybrid electron transport layer 40 is formed on the light absorbing layer 30 (S3). The coating method used in the step of forming the hybrid electron transport layer 40 on the light absorbing layer 30 is not particularly limited, but examples include dip coating, spray coating, and slide hopper coating. As the organic solvent (contained in the coating liquid) used in the coating method for forming the hybrid electron transport layer 40, chlorobenzene, dichlorobenzene, etc. can be used.

[0097] In the step of forming the hybrid electron transport layer 40, a solution containing an inorganic material 42 is added to a solution containing an organic material 41. The inorganic material 42 (inorganic filler) is a material that is similar to the electron transport material (PC) of the organic material 41. 61 BM, PC 71 The inorganic material 42 is dispersed in the coating liquid (BM, etc.). The weight ratio of the inorganic material 42 is preferably 5 wt % to 20 wt %. The coating liquid may also contain additives such as antioxidants, viscoelasticity modifiers, preservatives, and curing catalysts. The weight ratio of the inorganic material 42 in the hybrid electron transport layer 40 after drying may be 5 wt % to 20 wt %. The density of the inorganic material 42 to be added is preferably higher than the density of the solution containing the organic material 41.

[0098] In this way, in the step of forming the hybrid electron transport layer 40, the solution containing the inorganic material 42 is added to the solution containing the organic material 41, and thus the hybrid electron transport layer 40 can be formed by a single addition.

[0099] Then, the second electrode 50 is formed on the hybrid electron transport layer 40 (S4). For example, a gold vapor deposition film is formed as a cathode by vacuum deposition, thereby obtaining the solar cell 100 of this embodiment. The second electrode 50 used is as described above.

[0100] As described above, according to the method for manufacturing the solar cell 100 of this embodiment, the solution containing the inorganic material 42 is added to the solution containing the organic material 41, so that the hybrid electron transport layer 40 can be formed in a single process. Therefore, the solar cell 100 with improved conversion efficiency and durability can be easily manufactured, and the conventional process can be simplified.

[0101] Below, examples 1 to 11 of the solar cell and the method for manufacturing the solar cell according to the present embodiment will be specifically described together with comparative example 1, but the present disclosure is not limited to the examples described here.

[0102] (Example 1) (1) Transparent conductive substrate A glass substrate (thickness: 50 nm ± 20 nm) on which a fluorine-doped SnO2 conductive film was vapor-deposited was prepared and cut into a size of 25 mm × 25 mm. The substrate was subjected to ultrasonic cleaning with ethanol for 15 minutes, dried with nitrogen gas, and then irradiated with UV light for 30 minutes to obtain a transparent conductive substrate.

[0103] (2) Hole Transport Layer First, 2.2 mg of PTAA (manufactured by Tokyo Chemical Industry Co., Ltd.) is heated and dissolved in 1 ml of chlorobenzene (manufactured by Tokyo Chemical Industry Co., Ltd.) to prepare a hole transport layer coating solution. Next, the hole transport layer coating solution is applied by spin coating to the transparent conductive substrate prepared in "(1) Transparent Conductive Substrate" to prepare a coating layer, and the coating layer is heated at 100°C for 10 minutes to form a PTAA hole transport layer with a thickness of 20 nm to 100 nm.

[0104] (3) Light-Absorbing Layer (Perovskite Light-Absorbing Layer) First, 18.3 mg of CsI (Cesium Iodide) (manufactured by Tokyo Chemical Industry Co., Ltd.), 22.7 mg of MABr (Methylamine Hydrobromide, chemical formula: CHNHBr) (manufactured by Tokyo Chemical Industry Co., Ltd.), 25.7 mg of PbBr (manufactured by Tokyo Chemical Industry Co., Ltd.), 596.2 mg of PbI (manufactured by Tokyo Chemical Industry Co., Ltd.), and 187.5 mg of FAI (Formamidine Hydroiodide, chemical formula: CHNHI) (manufactured by Tokyo Chemical Industry Co., Ltd.) were dissolved by heating in a mixed solution of 0.8 ml of DMF (N,N-Dimethylformamide, chemical formula: CHNO) (manufactured by Tokyo Chemical Industry Co., Ltd.) and 0.24 ml of DMSO (manufactured by Tokyo Chemical Industry Co., Ltd.). 0.85 MA 0.15 PbI 2.75 Br 0.25 A coating solution is prepared. This coating solution is applied by spin coating onto the PTAA hole transport layer prepared in "(2) Hole transport layer," and chlorobenzene is added dropwise during the spinning process to prepare a coating film. The coating layer is heated at 150°C for 10 minutes to form a perovskite light absorbing layer with a thickness of 500 nm to 1000 nm.

[0105] (4) Hybrid electron transport layer (organic-inorganic hybrid electron transport layer) First, PC was used as an organic n-type material. 61 BM (“6,6”-phenyl-C 61 20 mg of 2,4-dichloro-1,4-butylic acid methyl ester (manufactured by Tokyo Chemical Industry Co., Ltd.) and 4 mg of ZnO (average particle size 10 nm) (EM Japan Co., Ltd.) as inorganic oxide n-type particles were dissolved in 1 ml of chlorobenzene (manufactured by Tokyo Chemical Industry Co., Ltd.) by heating to prepare an electron transport layer coating solution containing organic and inorganic materials. This coating solution was applied by spin coating to the perovskite light-absorbing layer prepared in "(3) Light-absorbing layer (perovskite light-absorbing layer)" to prepare a coating layer, and the coating layer was heated at 100°C for 10 minutes to form an organic-inorganic hybrid electron transport layer with a thickness of 80 nm to 200 nm. The thickness of the n-type inorganic layer (inorganic material) of the light-absorbing layer with uneven deposition was set to 40 nm to 100 nm.

[0106] (5) Second Electrode (Cathode) On the hybrid electron transport layer prepared in "(4) Hybrid Electron Transport Layer", a gold vapor-deposited film having an area of ​​3 mm × 20 mm and a thickness of 80 nm was formed as a cathode by vacuum deposition to obtain the solar cell of Example 1.

[0107] Example 2 A solar cell of Example 2 is obtained in the same manner as in Example 1, except that CuO oxide (average particle size: 10 nm) is used in place of ZnO in the hybrid electron transport layer.

[0108] Example 3 A solar cell of Example 3 is obtained in the same manner as in Example 1, except that the oxide SnO2 (average particle size 30 nm) is used in place of ZnO in the hybrid electron transport layer.

[0109] Example 4 A solar cell of Example 4 is obtained in the same manner as in Example 1, except that the oxide TiO2 (average particle size 30 nm) is used in place of ZnO in the hybrid electron transport layer.

[0110] Example 5 FA in perovskite light absorbing layer 0.85 MA 0.15 PbI 2.75 Br 0.25 A solar cell of Example 5 is obtained in the same manner as in Example 1, except that MAPbI3 (chemical formula: CH3NH3PbI3) is used instead of .

[0111] Example 6 A solar cell of Example 6 is obtained in the same manner as in Example 1, except that oxide Cu2O (average particle size 800 nm) is used in place of ZnO in the hybrid electron transport layer.

[0112] Example 7 A solar cell of Example 7 is obtained in the same manner as in Example 1, except that the oxide SnO2 (average particle size 800 nm) is used in place of ZnO in the hybrid electron transport layer.

[0113] Example 8 A solar cell of Example 8 is obtained in the same manner as in Example 1, except that the oxide NiO (average particle size 10 nm) is used in place of ZnO in the hybrid electron transport layer.

[0114] Example 9 A solar cell of Example 9 is obtained in the same manner as in Example 1, except that ZnO oxide (average particle size 300 nm) is used in place of ZnO in the hybrid electron transport layer.

[0115] Example 10: FA in perovskite light absorbing layer 0.85 MA 0.15 PbI 2.75 Br 0.25 A solar cell of Example 10 is obtained in the same manner as in Example 1, except that MASn3I3 is used instead of .

[0116] Example 11 FA in perovskite light absorbing layer 0.85 MA 0.15 PbI 2.75 Br 0.25 Instead of MASn 0.5 Pb 0.5 A solar cell of Example 11 is obtained in the same manner as in Example 1 except that I3 is used.

[0117] Comparative Example 1 On the other hand, a solar cell of Comparative Example 1 is obtained in the same manner as in Example 1, except that the hybrid electron transport layer is replaced with an electron transport layer made only of an organic n-type material without using ZnO.

[0118] The results of Examples 1 to 11 and Comparative Example 1 are shown in Table 1. In Table 1, Ec1 indicates the energy level of the lower end of the conduction band of the perovskite layer, and Ev1 indicates the energy level of the upper end of the valence band of the perovskite layer. Ec2 indicates the energy level of the lower end of the conduction band of the inorganic oxide n-type particles, and Ev2 indicates the energy level of the upper end of the valence band of the inorganic oxide n-type particles. Ec3 indicates the energy level of the lower end of the conduction band of the organic n-type material, and Ev3 indicates the energy level of the upper end of the valence band of the organic n-type material.

[0119]

[0120] Incidentally, a perovskite layer having an energy level at the top of the valence band in the range of −5.1 eV to −5.7 eV and an energy level at the bottom of the conduction band in the range of −3.5 eV to −4.0 eV can be suitably used in the solar cell 100 according to this embodiment.

[0121] Therefore, in the "Evaluation" column of Table 1, if the energy level of the upper end of the valence band of the perovskite layer is within the range of -5.1 eV to -5.7 eV, it is marked as "○", and if it is outside the range, it is marked as "△". Also, if the energy level of the lower end of the conduction band of the perovskite layer is within the range of -3.5 eV to -4.0 eV, it is marked as "○", and if it is outside the range, it is marked as "△".

[0122] Furthermore, inorganic oxide n-type particles having an average particle size in the range of 10 nm to 50 nm can ensure a desirable inorganic film thickness while effectively preventing moisture penetration. Therefore, in the "Evaluation" section of Table 1, inorganic oxide n-type particles having an average particle size in the range of 10 nm to 50 nm are marked with "○", and those outside the range are marked with "△".

[0123] Furthermore, a solar cell that satisfies the relational expression |Ec1|<|Ec2|<|Ec3| allows the energy level to easily shift electrons, forming a smoother energy level than conventional organic films, thereby improving the electron transport efficiency.

[0124] Therefore, in the "Evaluation" column of Table 1, if the relational expression |Ec1|<|Ec2|<|Ec3| is satisfied, it is marked as "◯", and if not, it is marked as "Δ".

[0125] Furthermore, solar cells that deviate from the relationship |Ev1|<|Ev2|<|Ev3|, i.e., that satisfy the relationship |Ev1|≧|Ev2| or |Ev2|≧|Ev3|, can make it difficult for the energy level to shift holes, and can efficiently block holes generated in the light absorption layer 30.

[0126] Therefore, in the "Evaluation" section of Table 1, if the relational expression |Ev1|<|Ev2|<|Ev3| is satisfied, it is marked as "△", and if this is not the case, i.e., if the relational expression |Ev1|≧|Ev2| or |Ev2|≧|Ev3| is satisfied, it is marked as "○".

[0127] In the "Overall Evaluation" of Table 1, if all the evaluations are "○", it is marked as "◎", and if any evaluations are "△", it is marked as "○".

[0128] As shown in Table 1, solar cells forming hybrid electron transport layers using inorganic materials such as ZnO, CuO, SnO2, TiO2, and NiO exhibit very excellent conversion efficiency and durability in Examples 1 to 3 and 5, which are rated as "◎". Also, Examples 4 and 6-11, which are rated as "◯", exhibit excellent conversion efficiency and durability. In contrast, the solar cell of Comparative Example 1 uses the same electron transport layer as conventional solar cells, so no improvement in conversion efficiency or durability is observed.

[0129] In particular, solar cells in which the average particle size of the inorganic material is 10 nm to 50 nm tend to show excellent results.

[0130] As described above, it is possible to provide a solar cell, a method for manufacturing a solar cell, a solar cell module, and a method for manufacturing a solar cell module, which have improved conversion efficiency and durability. Furthermore, the solar cell, solar cell, solar cell module, and method for manufacturing a solar cell module according to the present embodiment can be suitably used and applied to large-area solar power generation systems (mega solar) and power sources for small portable devices.

[0131] Although each embodiment and each example of the present disclosure have been described in detail above, it will be readily apparent to those skilled in the art that many modifications are possible without substantially departing from the novel features and effects of the present disclosure. Therefore, all such modifications are intended to be included within the scope of the present disclosure.

[0132] For example, a term described at least once in the specification or drawings together with a different term having a broader or equivalent meaning can be replaced with that different term anywhere in the specification or drawings. Furthermore, the configurations and operations of the solar cell, the method for manufacturing the solar cell, and the solar cell module and the method for manufacturing the solar cell module are not limited to those described in the embodiments and examples of the present disclosure, and various modifications are possible.

[0133] This application claims priority from Japanese Patent Application No. 2023-137860, filed on August 28, 2023, the entire contents of which are incorporated herein by reference.

[0134] The present disclosure relates to a solar cell and a solar cell module having a light absorption layer including a perovskite layer, and is particularly applicable to applications for improving the conversion efficiency and durability of solar cells.

[0135] 7 Perovskite compound 10 First electrode 11 Transparent substrate 12 Transparent conductive film 20 Hole transport layer 30 Light absorption layer 40 Hybrid electron transport layer 41 Organic material 42 Inorganic material 50 Second electrode 61 First barrier layer 62 Second barrier layer 63 Third barrier layer 64 Rear substrate 71 First terminal 72 Second terminal 81 Varistor 82 Current source 83 Diode 100 Solar cell 1000 Solar cell module 1100 Solar cell module

Claims

1. A step of forming a hole transport layer on the first electrode, A step of forming a light-absorbing layer including a perovskite layer on the hole transport layer, The process of forming a hybrid electron transport layer on the aforementioned light absorption layer, The process of forming a second electrode on the hybrid electron transport layer, Includes, The process of forming the hybrid electron transport layer involves adding an inorganic solution to an organic solution, A method for manufacturing a solar cell, characterized in that the density of the added inorganic substance is higher than the density of the solution containing the organic substance.

2. A step of forming a hole transport layer on the first electrode, A step of forming a light-absorbing layer including a perovskite layer on the hole transport layer, The process of forming a hybrid electron transport layer on the aforementioned light absorption layer, The process of forming a second electrode on the hybrid electron transport layer, Includes, The process of forming the hybrid electron transport layer involves adding an inorganic solution to an organic solution, A method for manufacturing a solar cell, characterized in that the inorganic layer is formed near the lower end of the hybrid electron transport layer.

3. The method for manufacturing a solar cell according to claim 2, characterized in that the density of the added inorganic substance is higher than the density of the solution containing the organic substance.

4. The method for manufacturing a solar cell according to claim 1 or 2, characterized in that the perovskite layer comprises a perovskite material having an energy level at the upper end of the valence band in the range of -5.1 eV to -5.7 eV and an energy level at the lower end of the conduction band in the range of -3.5 eV to -4.0 eV.

5. The aforementioned perovskite layer is of the general formula ABX ３ Composed of, A is an organic molecule or an organic-inorganic mixed molecule, B is a metal atom, and X is a halogen atom, as described in claim 1 or 2, for the purpose of manufacturing a solar cell.

6. The thickness of the hybrid electron transport layer is 80 nm to 200 nm. The aforementioned organic material includes an organic n-type material, The method for manufacturing a solar cell according to claim 1 or 2, characterized in that the inorganic material includes inorganic oxide n-type particles.

7. The method for manufacturing a solar cell according to claim 2, characterized in that the amount of inorganic material near the upper end of the hybrid electron transport layer is less than that near the lower end.

8. The method for manufacturing a solar cell according to claim 7, characterized in that the inorganic material is not provided near the upper end of the hybrid electron transport layer.

9. The thickness of the inorganic layer is 50 nm to 100 nm. The method for manufacturing a solar cell according to claim 2, characterized in that the inorganic material includes densely packed inorganic oxide n-type particles.

10. The aforementioned organic material includes an organic n-type material, The method for manufacturing a solar cell according to claim 1 or 2, characterized in that the organic n-type material includes one or more selected from the group consisting of PCBM, BCP, and C60.

11. The inorganic material includes inorganic oxide n-type particles, The inorganic oxide n-type particles are ZnO, CuO, and SnO ２ It includes one or more species selected from the group consisting of, The method for manufacturing a solar cell according to claim 1 or 2, characterized in that the inorganic oxide n-type particles have the same or a deeper energy level at the lower end of the conduction band as the light-absorbing layer.

12. The aforementioned organic material includes an organic n-type material, The inorganic material includes inorganic oxide n-type particles, The method for manufacturing a solar cell according to claim 1 or 2, characterized in that the organic n-type material has the same or a deeper energy level at the lower end of the conduction band as the inorganic oxide n-type particles.

13. The method for manufacturing a solar cell according to claim 1 or 2, characterized in that the average particle size of the inorganic material is 10 nm to 50 nm.

14. 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 claim 2.

15. The hole transport layer, the light absorption layer, and the hybrid electron transport layer are arranged in this order. The aforementioned hybrid electron transport layer includes organic and inorganic materials, A solar cell characterized in that the inorganic material is formed near the lower end of the hybrid electron transport layer.

16. The solar cell according to claim 15, characterized in that the light-absorbing layer comprises a perovskite compound.

17. The solar cell according to claim 16, characterized in that the perovskite compound includes a perovskite material having an energy level at the upper end of the valence band in the range of -5.1 eV to -5.7 eV and an energy level at the lower end of the conduction band in the range of -3.5 eV to -4.0 eV.

18. The perovskite compound is of the general formula ABX ３ Composed of, The solar cell according to claim 16, characterized in that A is an organic molecule or an organic-inorganic mixed molecule, B is a metal atom, and X is a halogen atom.

19. The thickness of the hybrid electron transport layer is 80 nm to 200 nm. The aforementioned organic material includes an organic n-type material, The solar cell according to claim 15, characterized in that the inorganic material includes inorganic oxide n-type particles.

20. The solar cell according to claim 15, characterized in that the amount of inorganic material near the upper end of the hybrid electron transport layer is less than that near the lower end.

21. The solar cell according to claim 20, characterized in that the inorganic material is not provided near the upper end of the hybrid electron transport layer.

22. The film thickness of the inorganic material is 50 nm to 100 nm. The solar cell according to claim 15, characterized in that the inorganic material includes densely packed inorganic oxide n-type particles.

23. The aforementioned organic material includes an organic n-type material, The solar cell according to claim 15, characterized in that the organic n-type material includes one or more selected from the group consisting of PCBM, BCP, and C60.

24. The inorganic material includes inorganic oxide n-type particles, The inorganic oxide n-type particles are ZnO, CuO, and SnO ２ It includes one or more species selected from the group consisting of, The solar cell according to claim 15, characterized in that the inorganic oxide n-type particles have the same or deeper energy levels at the lower end of the conduction band as the light-absorbing layer.

25. The aforementioned organic material includes an organic n-type material, The inorganic material includes inorganic oxide n-type particles, The solar cell according to claim 15, characterized in that the organic n-type material has the same or a deeper energy level at the lower end of the conduction band as the inorganic oxide n-type particles.

26. The solar cell according to claim 15, characterized in that the average particle size of the inorganic material is 10 nm to 50 nm.

27. A solar cell module comprising solar cells as described in any one of claims 15 to 26, The solar cell module is characterized in that the first electrode is a transparent conductive substrate.