Photoelectric conversion element module and method for manufacturing the same

Abstract

The photoelectric conversion element module (1) of the present application has a plurality of photoelectric conversion elements (15) formed on a light-transmissive substrate (3). The photoelectric conversion elements (15) are formed by sequentially stacking, from the light-transmissive substrate (3) side, a transparent conductive film (4), a first charge transport layer (5), a power generation layer (6), and a second charge transport layer (7). The second charge transport layer (7) is composed of a porous film containing a carbon material. In two adjacent photoelectric conversion elements (15), the second charge transport layer (7) of one photoelectric conversion element is electrically connected to the transparent conductive film (4) of the other photoelectric conversion element via a first conductive adhesive layer (9), a current collecting electrode (11), and a second conductive adhesive layer (14).

Description

Technical Field

[0001] This invention relates to a photoelectric conversion element module and its manufacturing method. Background Technology

[0002] Solar cells, as photoelectric conversion devices that convert light energy into electrical energy, have attracted much attention. Solar cells come in various types, such as perovskite solar cells that use perovskite compounds as the power-generating layer.

[0003] Furthermore, from the viewpoint of increasing the amount of electrical energy obtained, a photoelectric conversion element module is used, which is formed by connecting multiple of the aforementioned solar cells and other photoelectric conversion elements.

[0004] Here, in the photoelectric conversion element module, it is necessary to prevent the degradation of characteristics and short circuits between electrodes.

[0005] For example, Patent Document 1 discloses that in a solar cell module, by placing the separator portions of adjacent solar cells opposite each other with a gap between them, it is less likely to cause degradation of characteristics and short circuits between electrodes.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent document 1: Japanese Patent Application Publication No. 2017-152509. Summary of the Invention

[0009] The problem the invention aims to solve

[0010] However, although there are publicly disclosed examples of photoelectric conversion devices with high photoelectric conversion efficiency in the prior art, there is still room for improvement in durability.

[0011] Therefore, the purpose of this invention is to provide a photoelectric conversion element module with high photoelectric conversion efficiency and excellent durability.

[0012] Solution for solving the problem

[0013] The inventors conducted in-depth research with the aim of solving the above-mentioned problems. Then, the inventors discovered that if the photoelectric conversion element module has multiple photoelectric conversion elements on a transparent substrate, wherein each photoelectric conversion element is formed by sequentially stacking a transparent conductive film, a first charge transport layer, a power generation layer, and a second charge transport layer, and the second charge transport layer is composed of a porous film containing carbon material, and in two adjacent photoelectric conversion elements, the second charge transport layer of one photoelectric conversion element is electrically connected to the transparent conductive film of the other photoelectric conversion element via a first conductive adhesive layer, a current collector electrode, and a second conductive adhesive layer, then the photoelectric conversion efficiency is high and the durability is excellent, thus completing the present invention.

[0014] That is, the object of the present invention is to advantageously solve the above-mentioned problems. The photoelectric conversion element module of the present invention has a plurality of photoelectric conversion elements formed on a light-transmitting substrate. The photoelectric conversion element is formed by sequentially stacking a transparent conductive film, a first charge transport layer, a power generation layer, and a second charge transport layer from the light-transmitting substrate side. The second charge transport layer is composed of a porous film containing carbon material. In two adjacent photoelectric conversion elements, the second charge transport layer of one photoelectric conversion element is electrically connected to the transparent conductive film of the other photoelectric conversion element via a first conductive adhesive layer, a current collector electrode, and a second conductive adhesive layer. In this way, the photoelectric conversion element module has multiple photoelectric conversion elements on a light-transmitting substrate. The photoelectric conversion element is formed by sequentially stacking a transparent conductive film, a first charge transport layer, a power generation layer, and a second charge transport layer. The second charge transport layer is composed of a porous film containing carbon material. In two adjacent photoelectric conversion elements, the second charge transport layer of one photoelectric conversion element is electrically connected to the transparent conductive film of the other photoelectric conversion element through a first conductive adhesive layer, a current collector electrode, and a second conductive adhesive layer. This photoelectric conversion element module has high photoelectric conversion efficiency and excellent durability.

[0015] In addition, in this invention, a "porous membrane" is a membrane with multiple fine pores.

[0016] Here, in the photoelectric conversion element module of the present invention, preferably, the carbon material comprises carbon nanotubes. If the carbon material comprises carbon nanotubes, the photoelectric conversion efficiency of the photoelectric conversion element module can be further improved.

[0017] Furthermore, in the photoelectric conversion element module of the present invention, preferably, the carbon nanotubes contain a single layer of carbon nanotubes. If the carbon nanotubes contain a single layer of carbon nanotubes, the second charge transport layer can be endowed with excellent function as a hole transport layer, and the photoelectric conversion efficiency of the photoelectric conversion element module can be further improved.

[0018] Furthermore, in the photoelectric conversion element module of the present invention, preferably, the first conductive adhesive layer comprises first conductive particles, wherein the first conductive particles comprise at least one of carbon material and metal oxide. If the first conductive adhesive layer comprises first conductive particles, wherein the first conductive particles comprise at least one of carbon material and metal oxide, the durability of the photoelectric conversion element module can be further improved.

[0019] Furthermore, in the photoelectric conversion element module of the present invention, preferably, the first conductive adhesive layer comprises first conductive microparticles, and at least a portion of the first conductive microparticles is embedded in the second charge transport layer. If at least a portion of the first conductive microparticles contained in the first conductive adhesive layer is embedded in the second charge transport layer, the photoelectric conversion efficiency of the photoelectric conversion element module can be further improved.

[0020] Furthermore, in the photoelectric conversion element module of the present invention, preferably, the first conductive adhesive layer contains first conductive particles, the second conductive adhesive layer contains second conductive particles, and the average particle size of the second conductive particles is larger than the average particle size of the first conductive particles. If the average particle size of the second conductive particles contained in the second conductive adhesive layer is larger than the average particle size of the first conductive particles contained in the first conductive adhesive layer, the photoelectric conversion efficiency of the photoelectric conversion element module can be further improved.

[0021] Furthermore, in this invention, the "average particle size" of the particles can be obtained by measuring the particle size of 100 randomly selected particles using an electron microscope and calculating their average value.

[0022] Furthermore, in the photoelectric conversion element module of the present invention, preferably, the power generation layer comprises a perovskite compound. If the power generation layer comprises a perovskite compound, the photoelectric conversion efficiency of the photoelectric conversion element module can be further improved.

[0023] Furthermore, the present invention aims to advantageously solve the aforementioned problems. The method for manufacturing a photoelectric conversion element module according to the present invention includes a step of connecting two adjacent photoelectric conversion elements among a plurality of photoelectric conversion elements formed on a transparent substrate. The photoelectric conversion element is characterized in that it is formed by sequentially stacking a transparent conductive film, a first charge transport layer, a power generation layer, and a second charge transport layer from the transparent substrate side. The second charge transport layer is composed of a porous film containing carbon material. In the two adjacent photoelectric conversion elements, the second charge transport layer of one photoelectric conversion element is electrically connected to the transparent conductive film of the other photoelectric conversion element via a first conductive adhesive layer, a current collector electrode, and a second conductive adhesive layer. According to the method for manufacturing a photoelectric conversion element module of the present invention, a photoelectric conversion element module with high photoelectric conversion efficiency and excellent durability can be manufactured.

[0024] Invention Effects

[0025] According to the present invention, a photoelectric conversion element module with high photoelectric conversion efficiency and excellent durability can be provided. Attached Figure Description

[0026] Figure 1This is a schematic cross-sectional view illustrating the structure of a photoelectric conversion element module according to an embodiment of the present invention. Detailed Implementation

[0027] The photoelectric conversion element module of the present invention is not particularly limited, and can be, for example, a solar cell module such as an organic thin-film solar cell or a perovskite solar cell.

[0028] The following is for reference Figure 1 An embodiment of the photoelectric conversion element module of the present invention will be described in detail.

[0029] (Photoelectric conversion element module)

[0030] Figure 1 This is a schematic cross-sectional view illustrating the structure of a photoelectric conversion element module according to an embodiment of the present invention. The photoelectric conversion element module 1 has a plurality of photoelectric conversion elements 15 on a light-transmitting substrate 3. Figure 1 As shown, the photoelectric conversion element module 1 has two adjacent photoelectric conversion elements 15 on the light-transmitting substrate 3.

[0031] The photoelectric conversion element 15 is formed by sequentially stacking a transparent conductive film 4, a first charge transport layer 5, a power generation layer 6, and a second charge transport layer 7 from the side of the light-transmitting substrate 3. Here, the second charge transport layer 7 is composed of a porous film containing carbon material. In the second charge transport layer 7, a first conductive adhesive layer 9 is also formed on the side opposite to the side where the power generation layer 6 is formed. Furthermore, in the first conductive adhesive layer 9, the side opposite to the side where the second charge transport layer 7 is formed is connected to the current collector electrode 11. Therefore, the second charge transport layer 7 of the photoelectric conversion element 15 and the current collector electrode 11 are electrically connected via the first conductive adhesive layer 9. In addition, the current collector electrode 11 is formed on the substrate 12. In this specification, the component on the substrate 12 where the current collector electrode 11 is formed is sometimes referred to as the "current collector electrode substrate 10".

[0032] Moreover, in two adjacent photoelectric conversion elements 15, one ( Figure 1 The second charge transport layer 7 of the photoelectric conversion element 15 (left side) and another ( Figure 1 (On the right side of the image) The transparent conductive film 4 of the photoelectric conversion element 15 is electrically connected via the first conductive adhesive layer 9, the current collector electrode 11, and the second conductive adhesive layer 14.

[0033] Here, in Figure 1 In, as mentioned above, one ( Figure 1 The left-hand collector electrode 11 is electrically connected to the second charge transport layer 7 of a photoelectric conversion element 15 via a first conductive adhesive layer 9. Furthermore, this one collector electrode 11 connects to the other (…). Figure 1(The photoelectric conversion element 15 extends to the right side of the image). Furthermore, a transparent conductive film 4 of another photoelectric conversion element 15 extends towards one photoelectric conversion element 15. Moreover, a second conductive adhesive layer 14 is formed between the portion of a current collector 11 extending towards the other photoelectric conversion element 15 and the portion of the transparent conductive film 4 of the other photoelectric conversion element 15 extending towards the one photoelectric conversion element 15. Therefore, one current collector 11 and the transparent conductive film 4 of the other photoelectric conversion element 15 are electrically connected via the second conductive adhesive layer 14. Thus, on the light-transmitting substrate 3, among two adjacent photoelectric conversion elements 15, the second charge transport layer 7 of one photoelectric conversion element 15 and the transparent conductive film 4 of the other photoelectric conversion element 15 are electrically connected via a first conductive adhesive layer 9, a current collector 11, and a second conductive adhesive layer 14.

[0034] Furthermore, the first conductive adhesive layer 9 contains first conductive particles 8. Moreover, in Figure 1 In the first conductive particle 8, both the second charge transport layer 7 and the collector electrode 11 are in contact. Alternatively, in the photoelectric conversion element module 1, within the range where the desired effects of the present invention can be achieved, the first conductive particle 8 may be present only in contact with one of the second charge transport layer 7 and the collector electrode 11, or it may be present not in contact with either the second charge transport layer 7 or the collector electrode 11.

[0035] Furthermore, the second conductive adhesive layer 14 contains second conductive particles 13. Figure 1 In this configuration, the second conductive particle 13 contacts both the current collector electrode 11 and the transparent conductive film 4 of the other photoelectric conversion element 15. Alternatively, within the photoelectric conversion element module 1, to achieve the desired effects of the present invention, there may be a second conductive particle 13 that contacts only one of the current collector electrode 11 and the transparent conductive film 4 of the other photoelectric conversion element 15, or there may be a second conductive particle 13 that does not contact either the current collector electrode 11 or the transparent conductive film 4 of the other photoelectric conversion element 15. Furthermore, multiple second conductive particles 13 may be connected in series, with one end of the second conductive particle 13 contacting the current collector electrode 11 and the other end contacting the transparent conductive film 4 of the other photoelectric conversion element 15, thereby forming a conductive path from the current collector electrode 11 to the transparent conductive film 4.

[0036] In addition, Figure 1 In this process, the transparent conductive film 4 of one photoelectric conversion element 15 is not in contact with the transparent conductive film 4 of another photoelectric conversion element 15.

[0037] In addition, Figure 1 In this configuration, one collector electrode 11 is not in contact with the other collector electrode 11.

[0038] In addition, although in Figure 1 A portion was omitted, but one ( Figure 1 The transparent conductive film 4 of the photoelectric conversion element 15 (left side) can be electrically connected to the second charge transport layer 7 of other photoelectric conversion elements 15 via the second conductive adhesive layer 14, the current collector electrode 11, and the first conductive adhesive layer 9. Furthermore, similarly, another ( Figure 1 (On the right side of the image) The second charge transport layer 7 of the photoelectric conversion element 15 is electrically connected to the transparent conductive film 4 of the other photoelectric conversion elements 15 via the first conductive adhesive layer 9, the current collector electrode 11, and the second conductive adhesive layer 14.

[0039] Furthermore, in the photoelectric conversion element module 1, among any two adjacent photoelectric conversion elements 15, the second charge transport layer 7 of one photoelectric conversion element 15 and the transparent conductive film 4 of the other photoelectric conversion element 15 can be electrically connected via a first conductive adhesive layer 9, a current collector electrode 11, and a second conductive adhesive layer 14. For example, when the photoelectric conversion element module 1 has three or more photoelectric conversion elements 15, at least two of the three or more photoelectric conversion elements 15 can be electrically connected by the method specified above. However, from the viewpoint of further improving photoelectric conversion efficiency, it is preferable that all electrical connections between the photoelectric conversion elements 15 in the photoelectric conversion element module 1 are made by the method specified above.

[0040] The components constituting the photoelectric conversion element module 1 will be described in turn below.

[0041] <Transparent substrate 3>

[0042] The light-transmitting substrate 3 forms the base of the photoelectric conversion element module 1. There is no particular limitation on the light-transmitting substrate 3, and examples include substrates made of glass or synthetic resin, films made of synthetic resin, etc.

[0043] Examples of glass that constitutes the light-transmitting substrate 3 include glass made of inorganic materials such as soda glass.

[0044] Furthermore, examples of synthetic resins constituting the light-transmitting substrate 3 include polyacrylic acid resin, polycarbonate resin, polyester resin, polyimide resin, polystyrene resin, polyvinyl chloride resin, polyamide resin, and polycyclic olefin resin. Among these, from the viewpoint of obtaining a thin, lightweight, and flexible photoelectric conversion element module 1, polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) are particularly preferred as synthetic resins.

[0045] The thickness of the light-transmitting substrate 3 is not particularly limited, as long as it is thick enough to maintain the shape of the substrate. For example, the thickness of the light-transmitting substrate 3 can be 0.1 mm or more and 10 mm or less.

[0046] <Photoelectric Conversion Element 15>

[0047] The photoelectric conversion element module 1 has a plurality of photoelectric conversion elements 15 formed on a light-transmitting substrate 3. Moreover, the photoelectric conversion elements 15 are stacked sequentially from the light-transmitting substrate 3 side, including a transparent conductive film 4, a first charge transport layer 5, a power generation layer 6, and a second charge transport layer 7.

[0048] <<Transparent Conductive Film 4>>

[0049] The transparent conductive film 4 is a film made of metal oxide formed on the surface of the light-transmitting substrate 3. By providing the transparent conductive film 4, conductivity can be imparted to the surface of the light-transmitting substrate 3. In addition, in this specification, the component on which the transparent conductive film 4 is formed on the surface of the light-transmitting substrate 3 is sometimes referred to as "transparent conductive substrate 2".

[0050] Examples of metal oxides constituting the transparent conductive film 4 include fluorine-doped tin oxide (FTO), tin oxide (SnO), indium oxide (In₂O₃), tin-doped indium oxide (ITO), zinc oxide (ZnO), indium oxide / zinc oxide (IZO), and gallium oxide / zinc oxide (GZO). It should be noted that... Figure 1 The transparent conductive films of the multiple photoelectric conversion elements 15 in the photoelectric conversion element module 1 shown can be made of the same metal oxide or of different metal oxides.

[0051] The thickness of the transparent conductive film 4 is not particularly limited as long as it can provide the desired conductivity to the light-transmitting substrate 3. For example, it can be set to be above 1 nm and below 1 μm.

[0052] <<First Charge Transport Layer 5>>

[0053] The first charge transport layer 5 can be a layer made of p-type semiconductor (hole transport layer) or an n-type semiconductor (electron transport layer). It is necessary that one of the first charge transport layer 5 and the second charge transport layer 7 is made of p-type semiconductor and the other is made of n-type semiconductor. For example, when the second charge transport layer 7 is made of p-type semiconductor, the first charge transport layer 5 is made of n-type semiconductor. In this invention, since the second charge transport layer 7 is made of a porous film containing carbon material, the first charge transport layer 5 preferably has light transmittance regardless of whether it is made of p-type or n-type semiconductor.

[0054] For example, when the first charge transport layer 5 is an electron transport layer composed of an n-type semiconductor, the structure of the first charge transport layer 5 is not particularly limited. It can be a single layer composed of an n-type semiconductor, or it can be composed of two layers: a substrate layer and a porous semiconductor layer. The substrate layer and the porous semiconductor layer when the first charge transport layer 5 is composed of two layers will be described in detail below.

[0055] <Basal layer>

[0056] The substrate layer is arbitrarily positioned. By setting the substrate layer, direct contact between the light-transmitting substrate 3, the transparent conductive film 4, and the porous semiconductor layer described later is prevented. This prevents the loss of electromotive force, thereby further improving the photoelectric conversion efficiency of the photoelectric conversion element module 1.

[0057] The substrate layer, for example, is made of an n-type semiconductor and can be either a porous film or a non-porous dense film. However, from the viewpoint of sufficiently preventing the transparent substrate 3 and the transparent conductive film 4 from contacting the porous semiconductor layer, the substrate layer is preferably a non-porous dense film. It should be noted that the thickness of the substrate layer is not particularly limited, and can be, for example, 1 nm or more and 500 nm or less. Furthermore, the substrate layer may optionally contain an insulating material other than an n-type semiconductor in a proportion that does not impair the properties of the n-type semiconductor used as the substrate layer.

[0058] <Porous Semiconductor Layer>

[0059] The porous semiconductor layer is a porous layer. By including the porous semiconductor layer in the first charge transport layer 5, the photoelectric conversion efficiency of the photoelectric conversion element module 1 can be further improved.

[0060] The porous semiconductor layer preferably comprises metal oxides and / or organic compounds, more preferably comprises microparticles composed of metal oxides and / or organic compounds, and even more preferably is formed by microparticles composed of metal oxides and / or organic compounds.

[0061] Here, the metal oxide used to form the porous semiconductor layer is not particularly limited as long as it functions as an n-type semiconductor; titanium oxide (TiO2) is an example.

[0062] In addition, examples of organic compounds that form porous semiconductor layers include fullerene derivatives such as methyl phenyl C61 butyrate (PCBM).

[0063] Furthermore, the average particle size of the metal oxide and / or organic compound particles used in the porous semiconductor layer is preferably 2 nm or more and 80 nm or less, more preferably 30 nm or less. If the average particle size is small, the resistance of the porous semiconductor layer can be reduced.

[0064] The thickness of the porous semiconductor layer is not particularly limited, but it is usually above 5nm, preferably above 10nm, usually below 500nm, and preferably below 150nm.

[0065] <<Power Generation Layer 6>>

[0066] The power generation layer 6 is a layer made of a material that generates an electromotive force by absorbing light. From the viewpoint of further improving the photoelectric conversion efficiency of the photoelectric conversion element module 1, it is preferable to have a layer containing a perovskite compound, and more preferably a layer made of a perovskite compound (perovskite layer).

[0067] Here, the perovskite compound constituting the power generation layer 6 is not particularly limited, and a known perovskite compound can be used. Specifically, as a perovskite compound, examples such as CH3NH3PbI3, CH3NH3PbBr3, (CH3(CH2)nCHCH3NH3)2PbI4 [n=5~8], (C6H5C2H4NH3)2PbBr4, etc., can be used.

[0068] The thickness of the power generation layer 6 is not particularly limited, but is preferably 100 nm or more, more preferably 200 nm or more, and preferably 1 μm or less, more preferably 800 nm or less. By setting the thickness of the power generation layer 6 to 100 nm or more, the electromotive force of the power generation layer 6 can be increased.

[0069] <Bonding Layer>

[0070] In addition, although Figure 1 Although not shown, the photoelectric conversion element 15 may have a bonding layer at least in a portion between the power generation layer 6 and the second charge transport layer 7. The bonding layer is made of an organic material A and has a different composition and properties than the power generation layer 6 and the second charge transport layer 7. Here, gaps can be formed between the power generation layer 6 and the second charge transport layer 7 due to the unevenness of the surface of the power generation layer 6 and the porous film constituting the second charge transport layer 7. These gaps can be filled by providing a bonding layer between the power generation layer 6 and the second charge transport layer 7. Furthermore, by having a bonding layer in the photoelectric conversion element 15, charge transfer between the power generation layer 6 and the second charge transport layer 7 can be effectively performed, thus further improving the photoelectric conversion efficiency of the photoelectric conversion element module 1.

[0071] Examples of organic materials A constituting the bonding layer include polymethyl methacrylate (PMMA), which exhibits adhesive properties, and 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamino)-9,9'-spirodifluorene (Spiro-MeOTAD), which exhibits semiconductor properties. Furthermore, it can also be formed by mixing these various materials.

[0072] The thickness of the bonding layer is not particularly limited as long as it can fill the gap formed between the power generation layer 6 and the second charge transport layer 7, and can be appropriately set according to the shape of the surface of the power generation layer 6 and the second charge transport layer 7.

[0073] <<Second Charge Transport Layer 7>>

[0074] The second charge transport layer 7 can be a layer made of p-type semiconductor (hole transport layer) or an n-type semiconductor (electron transport layer), but one of the first charge transport layer 5 and the second charge transport layer 7 must be made of p-type semiconductor and the other of n-type semiconductor. For example, when the first charge transport layer 5 is made of n-type semiconductor, the second charge transport layer 7 must be made of p-type semiconductor.

[0075] [Porous membranes containing carbon materials]

[0076] Furthermore, the second charge transport layer 7 is composed of a porous membrane containing carbon material. The method for forming the porous membrane containing carbon material can be any method that allows it to be formed at a predetermined location; it can be formed by methods such as bonding a self-supporting membrane or coating methods based on printing. However, from the viewpoint of obtaining a preferred membrane thickness and suppressing short circuits, it is preferable that the porous membrane containing carbon material is a self-supporting membrane formed by bonding it.

[0077] Here, when a metal material is used as the second charge transport layer 7, corrosion occurs because the metal material in the second charge transport layer 7 reacts with components in the perovskite compound, such as iodide ions, contained in the power generation layer 6, thus reducing the durability of the photoelectric conversion element module 1. Furthermore, when an organic semiconductor material is used as the second charge transport layer 7, the durability of the photoelectric conversion element module 1 is reduced due to the insufficient stability of the organic semiconductor material. In contrast, since carbon materials do not corrode due to the reaction with the aforementioned perovskite compounds and exhibit excellent stability, using a film containing carbon material as the second charge transport layer 7 can improve the durability of the photoelectric conversion element module 1.

[0078] Furthermore, by using a porous membrane as the second charge transport layer 7, the electrical connection between the photoelectric conversion elements 15 can be stabilized, thereby improving the photoelectric conversion efficiency of the photoelectric conversion element module 1. The reason why using a porous membrane as the second charge transport layer 7 can stabilize the electrical connection between the photoelectric conversion elements 15 and improve the photoelectric conversion efficiency of the photoelectric conversion element module 1 is as follows.

[0079] First, the thickness of each layer, such as the second charge transport layer 7 constituting the photoelectric conversion element 15, sometimes varies. Furthermore, the particle size of the first conductive particles 8 contained in the first conductive adhesive layer 9 may also vary.

[0080] Furthermore, when using a non-porous membrane as the second charge transport layer 7, when bonding a light-transmitting substrate 3, on which multiple photoelectric conversion elements 15 are formed, to a current collector substrate 10 to manufacture the photoelectric conversion element module 1, the non-porous membrane lacks sufficient flexibility to absorb deviations in the layers and deviations in the particle size of the conductive particles 8. Therefore, sometimes a portion of the first conductive particles 8 fails to contact the second charge transport layer 7 and / or the current collector 11. In this case, the electrical connection between the photoelectric conversion elements 15 becomes unstable, resulting in increased internal resistance and decreased photoelectric conversion efficiency of the photoelectric conversion element module 1.

[0081] In contrast, when using a porous membrane as the second charge transport layer 7, when bonding a transparent substrate 3, on which multiple photoelectric conversion elements 15 are formed, to a current collector substrate 10 to manufacture the photoelectric conversion element module 1, the porous membrane possesses excellent flexibility. Therefore, by deforming its shape or moderately crushing it, it can absorb deviations in each layer and particle size deviations in the conductive particles 8. This ensures good contact between the first conductive particles 8 and the second charge transport layer 7 and the current collector 11. Consequently, the electrical connection between the photoelectric conversion elements 15 can be stabilized, thus improving the photoelectric conversion efficiency of the photoelectric conversion element module 1.

[0082] For the reasons mentioned above, when using a porous membrane containing carbon material as the second charge transport layer 7, a photoelectric conversion element module with high photoelectric conversion efficiency and excellent durability can be obtained.

[0083] Furthermore, when using a porous membrane as the second charge transport layer 7, during the fabrication of a photoelectric conversion element module 1 by bonding a light-transmitting substrate 3, on which multiple photoelectric conversion elements 15 are formed, to a current collector substrate 10, the first conductive adhesive layer adjacent to the porous membrane (second charge transport layer 7) before curing enters the porous membrane. This prevents the first conductive adhesive layer before curing from expanding under pressure and reaching another photoelectric conversion element, thus preventing short circuits.

[0084] Here, from the viewpoint of further stabilizing the electrical connection and improving the photoelectric conversion efficiency of the photoelectric conversion element module 1 by imparting excellent flexibility to the porous membrane, fibrous carbon materials are preferred as the carbon material contained in the porous membrane, fibrous carbon nanostructures are more preferred, carbon nanotubes (hereinafter sometimes simply referred to as "CNTs") are even more preferred, and monolayer carbon nanotubes are particularly preferred. In particular, when a porous membrane containing monolayer CNTs exhibiting semiconductor properties is used as the carbon material, the second charge transport layer 7 can be endowed with excellent function as a hole transport layer.

[0085] -Single-layer CNT-

[0086] The monolayer of CNTs that the porous membrane can contain preferably has the following properties.

[0087] --(3σ / Av)--

[0088] The ratio of the standard deviation (σ) of the diameter multiplied by 3 (3σ) of the monolayer CNTs contained in the porous membrane to the average diameter (Av) (3σ / Av) is preferably greater than 0.20, more preferably greater than 0.25, even more preferably greater than 0.50, and preferably less than 0.60. If 3σ / Av is greater than 0.20 and less than 0.60, then even if the amount of monolayer CNTs contained in the porous membrane is small, the second charge transport layer 7 can be given sufficient function as a hole transport layer.

[0089] --Average diameter (Av) of a single layer of CNTs--

[0090] The average diameter (Av) of the monolayer CNT is preferably 0.5 nm or more, more preferably 1 nm or more, and more preferably 15 nm or less, more preferably 10 nm or less. If the average diameter (Av) of the monolayer CNT is 0.5 nm or more, the aggregation of the monolayer CNT can be suppressed, and the dispersion of the monolayer CNT in the second charge transport layer 7 can be improved.

[0091] In addition, the average diameter (Av) of a single-layer CNT, and the ratio of the standard deviation of the diameter (σ) multiplied by 3 (3σ) to the average diameter (Av) (3σ / Av) can be obtained by measuring the diameter and length of 100 randomly selected single-layer CNTs using a scanning electron microscope or a transmission electron microscope.

[0092] --t-curve--

[0093] The monolayer CNT preferably exhibits a convex shape as shown by the t-curve obtained from the adsorption isotherm. More preferably, the monolayer CNT is one without CNT opening treatment. Using a monolayer CNT with a convex shape as shown by the t-curve obtained from the adsorption isotherm enables the acquisition of a second charge transport layer 7 with excellent strength.

[0094] In addition, the inflection point of the t-curve of monolayer CNT is preferably in the range of 0.2≤t(nm)≤1.5, more preferably in the range of 0.45≤t(nm)≤1.5, and even more preferably in the range of 0.55≤t(nm)≤1.0.

[0095] The determination of adsorption isotherms, the preparation of t-curves, and the analysis of t-curves for monolayer CNTs can be performed using, for example, a commercially available measuring device, “BELSORP-mini” (manufactured by Bayer Corporation, Japan).

[0096] Furthermore, monolayer CNTs preferably exhibit a radial breathing mode (RBM) peak when evaluated using Raman spectroscopy. Additionally, fibrous carbon nanostructures composed of three or more layers of carbon nanotubes do not show an RBM in their Raman spectra.

[0097] Furthermore, monolayer CNTs preferably have a G / D ratio (G / D ratio) of 0.5 or higher and 5.0 or lower in the Raman spectrum.

[0098] Monolayer CNTs with the above-mentioned properties can be synthesized by chemical vapor deposition (CVD) by supplying a raw material compound and a carrier gas to a substrate having a catalyst layer for CNT manufacturing on its surface. In this method (super-growth method; see International Publication No. 2006 / 011655), the catalyst layer is formed on the substrate surface using a wet process, thereby enabling efficient manufacturing.

[0099] From the perspective of easily obtaining porous membranes with large membrane thickness, monolayer CNTs obtained by super-growth method (sometimes called "SGCNTs") are preferred as monolayer CNTs.

[0100] -Proportion of carbon materials-

[0101] The porous membrane may contain carbon materials such as the aforementioned single-layer CNT, but it is preferred to be a porous membrane made of carbon materials.

[0102] Here, the proportion of carbon materials such as monolayer CNTs in the porous membrane is not particularly limited, but is preferably 50% by mass or more, more preferably 75% by mass or more, and even more preferably 90% by mass or more.

[0103] -Other ingredients-

[0104] Furthermore, the porous membrane may also contain components other than carbon materials, within the range that allows for the desired effects of the present invention. For example, metal oxide particles that are non-corrosive to the constituent materials used to enhance conductivity can be cited.

[0105] -Film thickness-

[0106] When no pressure is applied in the thickness direction, the thickness of the porous membrane is preferably 10 μm or more, more preferably 15 μm or more, even more preferably 20 μm or more, and preferably 200 μm or less, more preferably 150 μm or less, and even more preferably 80 μm or less. If the thickness of the porous membrane is above or below the aforementioned lower limit when no pressure is applied in the thickness direction, the electrical connection between the photoelectric conversion elements 15 can be further stabilized by effectively absorbing the deviations of the aforementioned layers and the particle size deviations of the conductive particles 8, thereby further improving the photoelectric conversion efficiency of the photoelectric conversion element module 1. On the other hand, if the thickness of the porous membrane is below or below the aforementioned upper limit when no pressure is applied in the thickness direction, it is easier to form a second charge transport layer 7 composed of a porous membrane, which is therefore preferred. In addition, when the thickness of the porous membrane is above or above the aforementioned upper limit when no pressure is applied in the thickness direction, the processes of formation, processing, and installation become complex or difficult, which is therefore not preferred.

[0107] In addition, the thickness of the porous membrane can be measured using the methods described in the embodiments of this specification.

[0108] In addition, as mentioned above, porous membranes are flexible, so when pressure is applied in the thickness direction, the membrane thickness decreases.

[0109] For example, when the porous membrane is pressurized at 0.05 Pa in the thickness direction, the reduction in membrane thickness is preferably 1 μm or more, more preferably 2 μm or more, and preferably less than half the thickness of the porous membrane before pressurization in the thickness direction. If the reduction in membrane thickness when the porous membrane is pressurized at 0.05 Pa is greater than or equal to the aforementioned lower limit, the porous membrane exhibits excellent flexibility. Therefore, by effectively absorbing the deviations of the aforementioned layers and the particle size deviations of the conductive particles 8, the electrical connection between the photoelectric conversion elements 15 is further stabilized, and the photoelectric conversion efficiency of the photoelectric conversion element module 1 can be further improved. On the other hand, if the reduction in membrane thickness when the porous membrane is pressurized at 0.05 Pa is less than or equal to the aforementioned upper limit, the self-support of the porous membrane can be well maintained.

[0110] Furthermore, the reduction in membrane thickness when the porous membrane is pressurized at 0.05 Pa can be measured using the method described in the examples of this specification.

[0111] -density-

[0112] Furthermore, the density of the porous membrane is preferably 0.4 g / cm³ when no pressure is applied in the thickness direction. 3 The above, preferably 0.6 g / cm³ 3 The above, and preferably 1.5 g / cm³ 3 The preferred value is 1.2 g / cm³. 3The following applies. If the density of the porous membrane is above the lower limit mentioned above, the self-support of the porous membrane can be well maintained. On the other hand, if the density of the porous membrane is below the upper limit mentioned above, the porous membrane has excellent flexibility. Therefore, by effectively absorbing the deviations of the above layers and the particle size deviations of the conductive particles 8, the electrical connection between the photoelectric conversion elements 15 can be further stabilized, and the photoelectric conversion efficiency of the photoelectric conversion element module 1 can be further improved.

[0113] In addition, the density of the porous membrane can be determined according to the method described in the embodiments of this specification.

[0114] - Method for manufacturing porous membranes containing carbon materials -

[0115] There is no particular limitation on the method for manufacturing porous membranes containing carbon materials. For example, a method can be employed that includes the following steps: removing the solvent from a dispersion of fibrous carbon nanostructures containing monolayer CNTs (as carbon materials), a dispersant, and a solvent, and then forming a porous membrane (film formation step). Furthermore, the method for manufacturing porous membranes containing carbon materials can also include, prior to the film formation step, a step of dispersing a coarse dispersion containing fibrous carbon nanostructures containing monolayer CNTs, a dispersant, and a solvent to prepare a fibrous carbon nanostructure dispersion (dispersion preparation step).

[0116] --Dispersion Preparation Process--

[0117] In the dispersion preparation process, although there are no particular limitations, it is preferable to supply a coarse dispersion containing fibrous carbon nanostructures including monolayer CNTs, a dispersant, and a solvent to a dispersion treatment that can achieve cavitation or fragmentation effects, as described in detail later, to disperse the fibrous carbon nanostructures containing monolayer CNTs and prepare a fibrous carbon nanostructure dispersion. In this way, by performing a dispersion treatment that can achieve cavitation or fragmentation effects, a fibrous carbon nanostructure dispersion in which the fibrous carbon nanostructures containing monolayer CNTs are well dispersed can be obtained. Furthermore, if a porous membrane is fabricated using fibrous carbon nanostructures with well-dispersed monolayer CNTs, the monolayer CNTs can be uniformly dispersed, resulting in a porous membrane with excellent electrical conductivity, thermal conductivity, and mechanical properties. Additionally, the fibrous carbon nanostructure dispersion used for fabricating porous membranes can be prepared by dispersing the fibrous carbon nanostructures containing monolayer CNTs in a solvent using known dispersion treatments other than those described above.

[0118] The fibrous carbon nanostructures used to prepare the fibrous carbon nanostructure dispersion need to contain at least a single layer of CNTs, for example, a mixture of single-layer CNTs and other fibrous carbon nanostructures (such as multilayer CNTs).

[0119] Here, in the fibrous carbon nanostructure dispersion, the content ratio of monolayer CNTs and fibrous carbon nanostructures other than monolayer CNTs can be set to, for example, a mass ratio (monolayer CNTs / fibrous carbon nanostructures other than monolayer CNTs) of 50 / 50 to 75 / 25.

[0120] =Dispersant=

[0121] The dispersant used to prepare the fibrous carbon nanostructure dispersion is not particularly limited as long as it can disperse fibrous carbon nanostructures containing at least a monolayer of CNTs, and is soluble in the solvent used to prepare the fibrous carbon nanostructure dispersion. For example, surfactants, synthetic polymers, or natural polymers can be used as such dispersants.

[0122] Examples of surfactants include sodium dodecyl sulfonate, sodium deoxycholate, sodium cholate, and sodium dodecylbenzene sulfonate.

[0123] In addition, examples of synthetic polymers include: polyether glycol, polyester glycol, polycarbonate glycol, polyvinyl alcohol, partially saponified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, acetal-modified polyvinyl alcohol, butyral-modified polyvinyl alcohol, silanol-modified polyvinyl alcohol, ethylene-vinyl alcohol copolymer, ethylene-vinyl alcohol-vinyl acetate copolymer resin, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, acrylic resin, epoxy resin, modified epoxy resin, phenoxy resin, modified phenoxy resin, phenoxy ether resin, phenoxy ester resin, fluorinated resin, melamine resin, alkyd resin, phenolic resin, polyacrylamide, polyacrylic acid, polystyrene sulfonic acid, polyethylene glycol, polyvinylpyrrolidone, etc.

[0124] In addition, examples of natural macromolecules include: starch, pullulan, dextran, dextrin, guar gum, xanthan gum, amylose, amylopectin, alginic acid, gum arabic, carrageenan, chondroitin sulfate, hyaluronic acid, gel polysaccharides, chitin, chitosan, cellulose, and their salts or derivatives. Derivatives refer to existing known compounds such as esters and ethers.

[0125] These dispersants can be used in one or in combination of two or more. Among them, surfactants are preferred as dispersants because of the excellent dispersibility of fibrous carbon nanostructures containing monolayer CNTs, and sodium deoxycholate is more preferred.

[0126] =Solvent=

[0127] The solvent used for dispersions of fibrous carbon nanostructures is not particularly limited, and examples include: alcohols such as water, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, tert-butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, and pentyl alcohol; ketones such as acetone, methyl ethyl ketone, and cyclohexanone; esters such as ethyl acetate and butyl acetate; and diethyl ether, diethyl ester, etc. Ethers such as alkanes and tetrahydrofurans; polar organic solvents such as N,N-dimethylformamide and N-methylpyrrolidone; aromatic hydrocarbons such as toluene, xylene, chlorobenzene, o-dichlorobenzene, and p-dichlorobenzene. These can be used individually or in combination with two or more.

[0128] Then, in the dispersion preparation process, it is preferable to perform a dispersion treatment that can achieve, for example, the cavitation effect or the fragmentation effect shown below.

[0129] =Dispersion treatment that can achieve cavitation effect=

[0130] The dispersion treatment to achieve cavitation effect utilizes the shock wave generated by the collapse of vacuum bubbles in water when high energy is imparted to the liquid. This dispersion method can effectively disperse monolayer CNTs.

[0131] Here, specific examples of dispersion treatments that can achieve cavitation effects include ultrasonic dispersion, jet mill dispersion, and high-shear stirring dispersion. Such dispersion treatments can be performed individually or in combination. More specifically, for example, ultrasonic homogenizers, jet mills, and high-shear stirring devices are preferred. These devices can be any existing known equipment.

[0132] When using an ultrasonic homogenizer to disperse monolayer CNTs, the coarse dispersion can be irradiated with ultrasound. The irradiation time can be appropriately set by factors such as the amount of monolayer CNTs, preferably 3 minutes or more, more preferably 30 minutes or more, and preferably 5 hours or less, more preferably 2 hours or less. Furthermore, the output power is preferably 20W or more and 500W or less, more preferably 100W or more and 500W or less, and the temperature is preferably 15°C or more and 50°C or less.

[0133] Furthermore, when using a jet mill, the number of treatments can be appropriately set based on the amount of CNTs in a single layer, for example, preferably 2 or more, more preferably 5 or more, and preferably 100 or less, more preferably 50 or less. Additionally, for example, the pressure is preferably 20 MPa or more and 250 MPa or less, and the temperature is preferably 15°C or more and 50°C or less.

[0134] Furthermore, when using a high-shear agitator, the coarse dispersion can be agitated and sheared using the agitator. The faster the rotation speed, the better. For example, the operating time (the time the machine rotates) is preferably 3 minutes or more and 4 hours or less, the circumferential speed is preferably 5 m / s or more and 50 m / s or less, and the temperature is preferably 15°C or more and 50°C or less.

[0135] Furthermore, the dispersion treatment that achieves the aforementioned cavitation effect is preferably performed at a temperature below 50°C. This is because it suppresses concentration changes caused by solvent evaporation.

[0136] =Dispersion processing that can achieve a breaking effect=

[0137] Dispersion treatment that achieves a fragmentation effect can, of course, uniformly disperse monolayer CNTs in the solvent. Compared with the dispersion treatment that achieves a cavitation effect, it is more advantageous in suppressing the damage to monolayer CNTs caused by the shock wave when bubbles disappear.

[0138] In this dispersion process that achieves a breaking effect, shear force is applied to the coarse dispersion to break and disperse the aggregates of fibrous carbon nanostructures containing monolayer CNTs. By applying back pressure to the coarse dispersion and cooling it as needed, the monolayer CNTs can be uniformly dispersed in the solvent while suppressing the generation of bubbles.

[0139] In addition, when loading back pressure on coarse dispersion liquid, the back pressure can be reduced to atmospheric pressure all at once, but it is preferable to reduce the pressure in multiple stages.

[0140] --Film Forming Process--

[0141] In the film-forming process, the solvent is removed from the aforementioned fibrous carbon nanostructure dispersion to form a porous membrane. Specifically, in the film-forming process, the solvent is removed from the fibrous carbon nanostructure dispersion using, for example, any one of the methods (A) and (B) described below to form the porous membrane.

[0142] (A) A method of coating a fibrous carbon nanostructure dispersion onto a film-forming substrate and then drying the coated fibrous carbon nanostructure dispersion.

[0143] (B) A method for filtering a dispersion of fibrous carbon nanostructures using a porous film-forming substrate and drying the resulting filter.

[0144] =Film-forming substrate=

[0145] Here, there are no particular limitations on the film-forming substrate, and any known substrate can be used.

[0146] Specifically, resin substrates and glass substrates can be used as film-forming substrates for coating the fibrous carbon nanostructure dispersion in method (A) above. Here, as resin substrates, examples include substrates formed from polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polytetrafluoroethylene (PTFE), polyimide, polyphenylene sulfide, aromatic polyamide, polypropylene, polyethylene, polylactic acid, polyvinyl chloride, polycarbonate, polymethyl methacrylate, alicyclic acrylic resins, cyclic olefin resins, triacetyl cellulose, etc. Furthermore, as glass substrates, substrates formed from ordinary soda glass can be used.

[0147] Furthermore, porous sheets formed from filter paper, cellulose, nitrocellulose, alumina, etc., can be used as film-forming substrates for filtering the fibrous carbon nanostructure dispersion in the above method (B).

[0148] =Apply=

[0149] In method (A) above, known coating methods can be used as the method for coating a fibrous carbon nanostructure dispersion onto a film-forming substrate. Specifically, as coating methods, dip coating, roller coating, gravure printing coating, knife coating, air knife coating, roller-knife coating, mold coating, screen printing, spraying, gravure offset spraying, etc., can be used.

[0150] =Filtering=

[0151] In method (B) above, known filtration methods can be used as a method for filtering a dispersion of fibrous carbon nanostructures using a film-forming substrate. Specifically, natural filtration, reduced pressure filtration, pressurized filtration, centrifugal filtration, etc., can be used as filtration methods.

[0152] =Drying=

[0153] As a method for drying the fibrous carbon nanostructure dispersion coated on the film-forming substrate in method (A) above, or the filter obtained in method (B) above, known drying methods can be used. Examples of drying methods include hot air drying, vacuum drying, hot roller drying, and infrared irradiation. The drying temperature is not particularly limited, typically ranging from room temperature to 200°C, and the drying time is not particularly limited, typically ranging from 0.1 to 150 minutes.

[0154] --Post-processing of porous membranes--

[0155] Here, the porous membrane formed as described above typically contains components included in a dispersion of fibrous carbon nanostructures, such as monolayer CNTs, fibrous carbon nanostructures other than monolayer CNTs, and a dispersant, in the same proportion as the fibrous carbon nanostructures. Therefore, in the method for manufacturing a porous membrane, the porous membrane formed in the film-forming process can optionally be washed to remove the dispersant from the porous membrane. Removing the dispersant from the porous membrane can further improve its properties, such as conductivity.

[0156] Furthermore, the porous membrane can be cleaned by contacting the dispersant with a solvent that can dissolve it, causing the dispersant in the porous membrane to dissolve in the solvent. The solvent used to dissolve the dispersant in the porous membrane is not particularly limited; any solvent suitable for use as a dispersion of fibrous carbon nanostructures can be used, preferably the same solvent used for the dispersion of fibrous carbon nanostructures. Furthermore, the contact between the porous membrane and the solvent can be achieved by immersing the porous membrane in the solvent or by coating the porous membrane with the solvent. After cleaning, the porous membrane can be dried using known methods.

[0157] Furthermore, during the manufacture of porous membranes, the porous membrane formed in the film-forming process can be subjected to pressing processing to further increase its density, and the porosity can be adjusted as needed. From the viewpoint of suppressing damage to monolayer CNTs or the reduction in properties due to damage, the pressing pressure during pressing processing is preferably less than 3 MPa, and more preferably no pressing processing is performed.

[0158] <First conductive adhesive layer 9>

[0159] The first conductive adhesive layer 9 is a layer that is conductive and has the function of bonding the second charge transport layer 7 to the collector electrode 11.

[0160] In the photoelectric conversion element module 1, assuming that there is no first conductive adhesive layer between the second charge transport layer 7 and the collector electrode 11, and the second charge transport layer 7 and the collector electrode 11 are directly bonded, the second charge transport layer contains carbon material as described above, so the surface is uneven. Therefore, the contact between the second charge transport layer 7 and the collector electrode 11 becomes insufficient, the electrical connection becomes unstable, and thus the photoelectric conversion efficiency of the photoelectric conversion element module 1 decreases.

[0161] In contrast, in the photoelectric conversion element module 1, by placing the first conductive adhesive layer 9 between the second charge transport layer 7 and the collector electrode 11, the electrical connection between the second charge transport layer 7 and the collector electrode 11 can be stabilized, thereby improving the photoelectric conversion efficiency of the photoelectric conversion element module 1.

[0162] The first conductive adhesive layer 9 can be formed, for example, by applying a conductive adhesive composition A containing an adhesive material and first conductive particles 8 to a predetermined location to form a coating film, and subjecting it to treatments such as light irradiation, heating, and standing as needed to cure the adhesive material. Furthermore, the formed first conductive adhesive layer 9 comprises a cured adhesive material and the first conductive particles 8.

[0163] As an adhesive material, there are no particular limitations as long as the material is cured by some method. For example, light-curing resins such as acrylic resins, thermosetting resins, and two-component reactive adhesives consisting of a main agent and a curing agent can be used.

[0164] <<First Conductive Particle 8>>

[0165] The first conductive particles 8 contained in the first conductive adhesive layer 9 are the material that bears the electrical connection between the second charge transport layer 7 and the current collector electrode 11.

[0166] Here, each particle of the first conductive microparticle 8 is preferably in contact with both the second charge transport layer 7 and the current collector electrode 11. By having each particle of the first conductive microparticle 8 in contact with both the second charge transport layer 7 and the current collector electrode 11, the electrical connection can be further stabilized, thereby further improving the photoelectric conversion efficiency of the photoelectric conversion element module 1.

[0167] In addition, in the photoelectric conversion element module 1, within the range that can achieve the desired effect of the present invention, there may be a first conductive particle 8 that is in contact with only one of the second charge transport layer 7 and the collector electrode 11, or there may be a first conductive particle 8 that is not in contact with either the second charge transport layer 7 or the collector electrode 11.

[0168] In addition, although Figure 1 Although not shown in the diagram, the second charge transport layer 7 is composed of a porous membrane containing carbon material and is flexible. Therefore, it is preferable that at least a portion of the first conductive particles 8 is embedded in the second charge transport layer 7. If at least a portion of the first conductive particles 8 is embedded in the second charge transport layer 7, the electrical connection can be further stabilized, thereby further improving the photoelectric conversion efficiency of the photoelectric conversion element module 1. Furthermore, when at least a portion of the first conductive particles 8 is embedded in the second charge transport layer 7, it can be that a portion of the particles of the first conductive particles 8 exists inside the second charge transport layer 7 while another portion exists outside the second charge transport layer 7, or it can be that the entire particle of the first conductive particles 8 is completely embedded inside the second charge transport layer 7. Moreover, the state in which at least a portion of the first conductive particles 8 is embedded in the second charge transport layer 7 can be confirmed by observing the cross-section of the photoelectric conversion element module 1 using a scanning electron microscope or the like.

[0169] The first conductive particle 8 is not particularly limited and can be particles of metals such as Ag, Au, Cu, Al, In, Sn, Bi, Pb and their oxides, conductive carbon particles such as carbon black, and particles formed by covering the surface of organic compound particles such as resin particles and inorganic compound particles with conductive substances such as Ag, Au, Cu and their oxides, such as Au / Ni alloy particles.

[0170] Resin particles covered with metal may corrode as described above, which may cause durability problems. Therefore, from the viewpoint of suppressing corrosion caused by iodide ions of the perovskite compound contained in the power generation layer 6 and further improving the durability of the photoelectric conversion element module 1, particles containing at least one of carbon material and metal oxide are preferably used as the first conductive particles 8.

[0171] Here, the average particle size of the first conductive particles 8 is preferably 20 nm or more, more preferably 30 nm or more, further preferably 50 nm or more, even more preferably 100 nm or more, even more preferably 120 nm or more, and preferably 2000 nm or less, more preferably 1000 nm or less, and even more preferably 500 nm or less. If the average particle size of the first conductive particles 8 is above the aforementioned lower limit, the electrical connection can be further stabilized by the good contact between the first conductive particles 8 and the second charge transport layer 7 and the current collector electrode 11, thereby further improving the photoelectric conversion efficiency of the photoelectric conversion element module 1. On the other hand, if the average particle size of the first conductive particles 8 is below the aforementioned upper limit, the second charge transport layer 7 (porous membrane) can be prevented from being excessively crushed by the first conductive particles 8, thus maintaining the characteristics of the photoelectric conversion element module 1 well.

[0172] In addition, the average particle size of the first conductive particles 8 is preferably greater than the surface roughness Rz of the second charge transport layer 7.

[0173] Furthermore, the content ratio of the first conductive particles 8 in the first conductive adhesive layer 9 is preferably 6% by mass or more, more preferably 8% by mass or more, even more preferably 10% by mass or more, and preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less. If the content ratio of the first conductive particles 8 in the first conductive adhesive layer 9 is at or above the aforementioned lower limit, the electrical connection between the second charge transport layer 7 and the current collector electrode 11 via the first conductive particles 8 is further stabilized, and the photoelectric conversion efficiency of the photoelectric conversion element module 1 can be further improved. On the other hand, if the content ratio of the first conductive particles 8 in the first conductive adhesive layer 9 is at or below the aforementioned upper limit, the electrical connection is further stabilized by ensuring good adhesion between the second charge transport layer 7 and the current collector electrode 11, and the photoelectric conversion efficiency of the photoelectric conversion element module 1 can be further improved.

[0174] <Collector 11>

[0175] The current collector 11 is a conductive film formed on the substrate 12. By providing the current collector 11, conductivity can be imparted to the surface of the substrate 12. As for the conductive film forming the current collector 11, there is no particular limitation as long as it is a conductive film such as a metal film or a film made of metal oxide, but from the viewpoint of ease of patterning using laser scribing or the like, a film made of metal oxide is preferred.

[0176] As the metal oxide constituting the current collector 11, the metal oxide described as constituting the transparent conductive film 4 can be used.

[0177] Furthermore, the film thickness of the current collector 11 is not particularly limited as long as it is thick enough to impart the desired conductivity to the substrate 12, and can be, for example, 1 nm or more and 1 μm or less.

[0178] <Substrate 12>

[0179] The substrate 12 is not particularly limited, and examples include a substrate made of glass or synthetic resin, or a film made of synthetic resin. In addition, glass and synthetic resin, which are used as materials constituting the light-transmitting substrate 3, can be used as glass and synthetic resin.

[0180] Furthermore, the thickness of the substrate 12 is not particularly limited, as long as it is thick enough to maintain the shape of the substrate. The thickness of the substrate 12 can be, for example, 0.1 mm or more and 10 mm or less.

[0181] <Second conductive adhesive layer 14>

[0182] The second conductive adhesive layer 14 is conductive. Furthermore, the second conductive adhesive layer 14 is formed between two adjacent photoelectric conversion elements 15 on the light-transmitting substrate 3, and will be disposed in a ( Figure 1 The collector electrode 11 on the left side of the photoelectric conversion element 15 is directed to the other ( Figure 1The portion extending from the right side of the photoelectric conversion element 15 is connected to the portion extending from the transparent conductive film 4 of the other photoelectric conversion element 15 towards the photoelectric conversion element 15. Therefore, via the second conductive adhesive layer 14, the current collector 11 disposed on the side of one photoelectric conversion element 15 is electrically connected to the transparent conductive film 4 of the other photoelectric conversion element 15. Thus, while maintaining good transparency of the space between two adjacent photoelectric conversion elements 15, two adjacent photoelectric conversion elements 15 on the substrate 3 can be electrically connected. Furthermore, when two adjacent photoelectric conversion elements 15 are connected to each other via the second conductive adhesive layer 14, since it is not necessary to provide a partition made of an insulator between two adjacent photoelectric conversion elements 15, the space between two adjacent photoelectric conversion elements 15 can be narrowed. Therefore, by increasing the number of photoelectric conversion elements per unit area, the photoelectric conversion element module 1 can be highly integrated.

[0183] The second conductive adhesive layer 14 can be formed, for example, by applying a conductive adhesive composition B containing adhesive material and second conductive particles 13 to a predetermined location to form a coating film, and then subjecting it to treatments such as light irradiation, heating, and standing as needed to cure the adhesive material. Furthermore, the formed second conductive adhesive layer 14 includes a cured adhesive material and the second conductive particles 13.

[0184] As an adhesive material, there are no particular limitations as long as the material is cured by some method. For example, light-curing resins such as acrylic resins, thermosetting resins, and two-component reactive adhesives consisting of a main agent and a curing agent can be used.

[0185] <<Second Conductive Particle 13>>

[0186] The second conductive particles 13 contained in the second conductive adhesive layer 14 are materials that provide electrical connection between the current collector 11 disposed on one side of a photoelectric conversion element 15 and the transparent conductive film 4 of the other photoelectric conversion element 15.

[0187] The second conductive particle 13 preferably contacts both the current collector 11 disposed on one side of the photoelectric conversion element 15 and the transparent conductive film 4 disposed on the other side of the photoelectric conversion element 15. By having the second conductive particle 13 contact both the current collector 11 disposed on one side of the photoelectric conversion element 15 and the transparent conductive film 4 disposed on the other side of the photoelectric conversion element 15, the electrical connection can be further stabilized, thereby further improving the photoelectric conversion efficiency of the photoelectric conversion element module 1.

[0188] Furthermore, in the photoelectric conversion element module 1, within the range where the desired effects of the present invention can be achieved, there may be a second conductive particle 13 that contacts only one of the transparent conductive films 4 of the current collector 11 and the other photoelectric conversion element 15, or there may be a second conductive particle 13 that does not contact either the transparent conductive film 4 of the current collector 11 or the other photoelectric conversion element 15. Moreover, multiple second conductive particles 13 are connected in series, with one end of the second conductive particle 13 contacting one current collector 11 and the other end contacting the transparent conductive film 4 of the other photoelectric conversion element 15, thereby forming a conductive path from the current collector 11 to the transparent conductive film 4.

[0189] The second conductive particle 13 is not particularly limited and can be made of particles of metals such as Ag, Au, Cu, Al, In, Sn, Bi, Pb and their oxides, conductive carbon particles such as carbon black, and particles formed by covering the surface of organic compound particles such as resin particles and inorganic compound particles with conductive substances such as Ag, Au, Cu and their oxides, such as Au / Ni alloy particles.

[0190] Furthermore, the representative shape of the second conductive particle 13 is preferably a sphere, such as an oblate spheroid or a perfect sphere. It is particularly preferred to be a perfect sphere or an oblate spheroid that is infinitely close to a perfect sphere. If the representative shape of the second conductive particle 13 is a perfect sphere or an oblate spheroid that is infinitely close to a perfect sphere, the manufacturing efficiency of the photoelectric conversion element module 1 can be improved.

[0191] The maximum size R of the second conductive particle 13 can be, for example, 10 μm or more and 30 μm or less.

[0192] It should be noted that the maximum size R of the second conductive particle 13 is the arithmetic mean of the major axis lengths obtained by observing 100 particles of the second conductive particle 13 under a microscope.

[0193] The average particle size of the second conductive particle 13 is preferably larger than the average particle size of the first conductive particle 8. If the average particle size of the second conductive particle 13 is larger than the average particle size of the first conductive particle 8, then as described above, it is easier for the first conductive particle 8 to contact both the second charge transport layer 7 and the current collector electrode 11, and it is easier for the second conductive particle 13 to contact both the current collector electrode 11 and the transparent conductive film 4. Therefore, the electrical connection can be further stabilized, and the photoelectric conversion efficiency of the photoelectric conversion element module 1 can be further improved.

[0194] Furthermore, the first charge transport layer 5, the power generation layer 6, the porous membrane for the second charge transport layer 7, the first conductive particle 8, and the second conductive particle 13 preferably satisfy the relationship represented by the following formula (I).

[0195] (Thickness of the first charge transport layer 5) + (Thickness of the power generation layer 6) + (Thickness of the porous membrane used for the second charge transport layer 7) + (Average particle size of the first conductive particles 8) > (Average particle size of the second conductive particles 13) ... (I)

[0196] In addition, in the above formula (I), "the thickness of the porous membrane used for the second charge transport layer 7" refers to the thickness of the porous membrane in the thickness direction without pressure.

[0197] Furthermore, when the first charge transport layer 5, the power generation layer 6, the porous membrane for the second charge transport layer 7, the first conductive particle 8, and the second conductive particle 13 satisfy the relationship represented by the above formula (I), when the light-transmitting substrate 3 on which multiple photoelectric conversion elements 15 are formed is bonded to the current collector electrode substrate 10 to manufacture the photoelectric conversion element module 1, by deforming or moderately crushing the porous membrane, the first conductive particle 8 can be brought into contact with both the second charge transport layer 7 and the current collector electrode 11, and the second conductive particle 13 can be brought into contact with both the current collector electrode 11 and the transparent conductive film 4. Therefore, the electrical connection can be further stabilized, and the photoelectric conversion efficiency of the photoelectric conversion element module 1 can be further improved.

[0198] Furthermore, when an auxiliary electrode capable of electrical connection is formed on at least one side of the thickness direction of the second conductive adhesive layer 14, the first charge transport layer 5, the power generation layer 6, the porous membrane for the second charge transport layer 7, the first conductive particle 8, the second conductive particle 13, and the auxiliary electrode preferably satisfy the relationship represented by the following formula (II) instead of the above formula (I).

[0199] (Thickness of the first charge transport layer 5) + (Thickness of the power generation layer 6) + (Thickness of the porous membrane used for the second charge transport layer 7) + (Average particle size of the first conductive particles 8) > (Average particle size of the second conductive particles 13) + (Thickness of the auxiliary electrode) ... (II)

[0200] Furthermore, in equation (II) above, "the thickness of the porous membrane used for the second charge transport layer 7" refers to the thickness of the porous membrane when no pressure is applied in the thickness direction. Additionally, "the thickness of the auxiliary electrodes" in equation (II) above refers to the sum of the thicknesses of the auxiliary electrodes. For example, when auxiliary electrodes are formed on both sides of the thickness direction of the second conductive adhesive layer 14, "the thickness of the auxiliary electrodes" in equation (II) above refers to the sum of the thicknesses of the auxiliary electrodes formed on both sides of the thickness direction of the second conductive adhesive layer 14.

[0201] Furthermore, the average particle size of the second conductive particles 13 is preferably 10 μm or more, more preferably 15 μm or more, even more preferably 20 μm or more, and preferably 200 μm or less, more preferably 150 μm or less, and even more preferably 80 μm or less. If the average particle size of the second conductive particles 13 is at or above the aforementioned lower limit, the second conductive particles 13 can easily contact the current collector electrode 11 and the transparent conductive film 4, thereby further stabilizing the electrical connection and further improving the photoelectric conversion efficiency of the photoelectric conversion element module 1. On the other hand, if the average particle size of the second conductive particles 13 is at or below the aforementioned upper limit, the relationship represented by the above formula (I) or (II) can be easily satisfied, thereby further stabilizing the electrical connection and further improving the photoelectric conversion efficiency of the photoelectric conversion element module 1.

[0202] The aforementioned photoelectric conversion element module 1 exhibits high photoelectric conversion efficiency and excellent durability. Furthermore, as long as the photoelectric conversion element module of the present invention comprises a photoelectric conversion element formed by sequentially stacking a transparent conductive film, a first charge transport layer, a power generation layer, and a second charge transport layer composed of a porous film containing carbon material on a transparent substrate, and in two adjacent photoelectric conversion elements, the second charge transport layer of one photoelectric conversion element is electrically connected to the transparent conductive film of the other photoelectric conversion element via a first conductive adhesive layer, a current collector electrode, and a second conductive adhesive layer, then, within the scope of achieving the desired effects of the present invention, other components besides the aforementioned constituent parts may also be included.

[0203] (Manufacturing method of photoelectric conversion element module)

[0204] Next, refer to again Figure 1 The manufacturing method of the photoelectric conversion element module of the present invention will be described. The manufacturing method of the photoelectric conversion element module of the present invention requires a connection step to connect two adjacent photoelectric conversion elements among a plurality of photoelectric conversion elements formed on a light-transmitting substrate, and may optionally include steps other than the connection step. Hereinafter, as an example of the manufacturing method of the photoelectric conversion element module of the present invention, the manufacturing method of photoelectric conversion element module 1 will be specifically described.

[0205] <Preparation of Transparent Substrate 3>

[0206] In the manufacturing method of photoelectric conversion element module 1, firstly, a light-transmitting substrate 3 is prepared. As the light-transmitting substrate 3, the light-transmitting substrates mentioned in the "photoelectric conversion element module" section can be used.

[0207] <Formation of transparent conductive film 4>

[0208] Next, a transparent conductive film is formed on the light-transmitting substrate 3. The method for forming the transparent conductive film 4 is not particularly limited; for example, known methods such as sputtering or vapor deposition can be used. Alternatively, by using a commercially available light-transmitting substrate on which a transparent conductive film is formed, the formation of the transparent conductive film 4 can be omitted.

[0209] Here, in order to form photoelectric conversion elements 15 in a desired number and configuration in the manufactured photoelectric conversion element module 1, a plurality of transparent conductive films 4 are formed on the light-transmitting substrate 3 in a desired pattern. For example, by etching the transparent conductive films 4 formed on the entire surface of the light-transmitting substrate 3, a portion of the transparent conductive films can be removed, and a plurality of transparent conductive films 4 formed in the desired pattern can be obtained.

[0210] <Formation of the first charge transport layer 5>

[0211] Then, a first charge transport layer 5 is formed on the transparent conductive film 4. For example, the first charge transport layer 5 is obtained by forming a substrate layer on the transparent conductive film 4 and then forming a porous semiconductor layer.

[0212] [Formation of the basal layer]

[0213] There is no particular limitation on the method of forming the substrate layer. For example, it can be formed by spraying a solution containing a material that forms an n-type semiconductor onto the transparent conductive film 4.

[0214] Examples of solution spraying methods include: spray pyrolysis, aerosol deposition, electrostatic spraying, and cold spraying.

[0215] [Formation of porous semiconductor layers]

[0216] There are no particular limitations on the method for forming porous semiconductor layers. For example, they can be formed by applying a solution containing an n-type semiconductor precursor onto a substrate layer by spin coating and drying.

[0217] Here, examples of precursors for n-type semiconductors include titanium tetrachloride (TiCl4), peroxytitanic acid (PTA), ethyl titanate, and isopropyl titanate (TTIP) and other titanium alcohol esters; and metal alkanols such as zinc alkanol, alkoxysilane, zirconium alkanol, and di(acetylacetonyl)titanate diisopropyl.

[0218] Furthermore, there are no particular limitations on the solvent used as a solution for a precursor containing an n-type semiconductor, and alcoholic solutions such as ethanol can be used.

[0219] Furthermore, there are no particular limitations on the temperature and time for drying the solution applied to the substrate; these can be adjusted appropriately based on the type of n-type precursor and solvent used.

[0220] <Formation of Power Generation Layer 6>

[0221] Then, a power generation layer 6 is formed on the first charge transport layer 5. The method for forming the power generation layer 6 includes vacuum evaporation, coating, etc., but is not particularly limited. For example, it can be formed by coating a precursor-containing solution containing a perovskite compound precursor onto the first charge transport layer 5 and then sintering. Examples of perovskite compound precursors include lead iodide (PbI2) and methylammonium iodide (CH3NH3I). Furthermore, the solvent contained in the precursor-containing solution is not particularly limited, and examples include N,N-dimethylformamide and dimethyl sulfoxide. After coating with these solutions, unsuitable solvents can also be used to promote the precipitation of the perovskite compound.

[0222] Furthermore, the term "undesirable solvent" in this specification refers to a solvent in which the perovskite compound remains substantially unchanged during the manufacturing process. If, during the manufacturing process, no visual alteration such as turbidity of the film is observed in the perovskite compound, it can be said that the perovskite compound remains substantially unchanged.

[0223] Here, the concentration of the precursor of the perovskite compound in the precursor solution can be set to an appropriate concentration based on the solubility of the materials constituting the perovskite compound, and can be, for example, around 0.5M to 1.5M.

[0224] Furthermore, there are no particular limitations on the method of applying the precursor solution to the first charge transport layer 5, and known coating methods such as spin coating, spray coating, bar coating, and inkjet coating can be used.

[0225] <Formation of the second charge transport layer 7>

[0226] After forming the power generation layer 6, a second charge transport layer 7 is formed on the power generation layer 6. Alternatively, the second charge transport layer 7 can be formed on the power generation layer 6 via a bonding layer, if necessary. For example, the porous membrane is stacked on the power generation layer 6 while at least one of the bonding surfaces of the power generation layer 6 and the porous membrane containing carbon material is kept in solvent X or solution P. This allows for the easy fabrication of a photoelectric conversion element module 1 with high photoelectric conversion efficiency.

[0227] In addition, as a porous membrane, the porous membrane containing carbon material described in the item "Photoelectric Conversion Element Module" can be used.

[0228] Examples of undesirable solvents as solvent X include chlorobenzene, toluene, and anisole. Using these undesirable solvents, in the case where, for example, the power generation layer 6 is a perovskite layer composed of a perovskite compound, a porous membrane containing carbon material can be well adhered to the power generation layer 6.

[0229] Furthermore, when the second charge transport layer 7 is formed on the power generation layer 6 via the bonding layer, solution P is used instead of solvent X.

[0230] As the solution P mentioned above, an example is an organic material solution obtained by dissolving the organic material A constituting the bonding layer in a poor solvent.

[0231] Furthermore, if a porous membrane impregnated with the aforementioned solvent X or solution P is used, the solvent X or solution P can be well retained at the interface between the power generation layer 6 and at least one of the porous membrane.

[0232] Here, a porous membrane impregnated with solvent X or solution P can be obtained, for example, by immersing the porous membrane in the aforementioned solvent X or solution P and then pulling it up. In this case, the immersion time is not particularly limited and can be appropriately set according to the type of solvent or solution used.

[0233] Furthermore, the method for forming the bonding layer is not particularly limited. However, from the viewpoint of efficiently manufacturing the photoelectric conversion element module 1, it is preferable to immerse the porous membrane in an organic material solution containing organic material A (such as PMMA as described above), which is dissolved in a poor solvent, then pull it up, heat it, and dry it to form a bonding layer on the porous membrane. The porous membrane is then adhered to the power generation layer 6 via the bonding layer. At this time, the immersion time, heating temperature, and drying time are not particularly limited and can be appropriately set according to the type of organic material solution used. To prevent residual effects, a poor solvent is preferably used to dissolve the organic material A constituting the bonding layer. However, as long as it can be dried to a degree that does not cause changes to the power generation layer 6, it is not limited to a poor solvent, and various solvents can be used.

[0234] Furthermore, it is preferable to heat-press the porous membrane stacked on the power generation layer 6. This allows for the formation of a photoelectric conversion element 15 with excellent overall integrity. The heating temperature is not particularly limited and can be, for example, around 100°C. Furthermore, the pressure during heating and pressing is not particularly limited and can be, for example, 0.05 MPa. Furthermore, the pressing time is not particularly limited and can be, for example, 30 seconds. In addition, during heating and pressing, to promote the removal of solvent contained in the porous membrane, it is preferable to press in a manner that ensures a solvent evaporation path. Specifically, to ensure a solvent evaporation path, it is preferable to heat-press via a porous component such as a thick cloth, porous rubber, porous metal, or porous ceramic.

[0235] Through the above operations, a plurality of photoelectric elements 15 are formed on the light-transmitting substrate. In addition, each photoelectric conversion element 15 is formed by sequentially stacking a transparent conductive film 4, a first charge transport layer 5, a power generation layer 6, and a second charge transport layer 7 from the side of the light-transmitting substrate 3. The second charge transport layer is composed of a porous film containing carbon material.

[0236] <Connection of photoelectric conversion element 15>

[0237] Then, two adjacent photoelectric conversion elements 15 among the plurality of photoelectric conversion elements 15 formed on the light-transmitting substrate 3 are connected.

[0238] First, the conductive adhesive composition A for forming the first conductive adhesive layer 9 and the conductive adhesive composition B for forming the second conductive adhesive layer 14 are respectively applied to predetermined positions on a light-transmitting substrate on which multiple photoelectric conversion elements are formed. It should be noted that the application of conductive adhesive composition A and conductive adhesive composition B can be performed using, for example, a dispensing machine.

[0239] Next, a light-transmitting substrate 3, on which multiple photoelectric conversion elements 15 are formed and conductive adhesive compositions A and B are coated at predetermined positions, is bonded to a current collector substrate 10 at predetermined positions. Furthermore, similar to the method described above for forming a transparent conductive film 4 on the light-transmitting substrate 3, the current collector substrate 10 can be fabricated by forming a current collector electrode 11 on the substrate 12. Moreover, the bonding of the light-transmitting substrate 3 and the current collector substrate 10 can be performed using a vacuum bonding apparatus under reduced pressure.

[0240] Subsequently, as needed, light irradiation, heating, and static treatment are performed to cure the adhesive materials contained in the conductive adhesive compositions A and B, thereby forming a first conductive adhesive layer 9 and a second conductive adhesive layer 14.

[0241] Then, through the above operations, a photoelectric conversion element module 1 can be obtained, which has a plurality of photoelectric conversion elements 15 on a light-transmitting substrate 3, and adjacent photoelectric conversion elements 15 are electrically connected. In the photoelectric conversion element module 1, the second charge transport layer 7 of one of the two adjacent photoelectric conversion elements 15 is connected to the current collector electrode 11 via a first conductive adhesive layer 9. In addition, the current collector electrode 11 extends toward the other photoelectric conversion element 15. Furthermore, the transparent conductive film 4 of the other photoelectric conversion element 15 extends toward one photoelectric conversion element 15. Moreover, the portion of the current collector electrode 11 extending toward the other photoelectric conversion element 15 is connected to the portion of the transparent conductive film 4 of the other photoelectric conversion element 15 extending toward one photoelectric conversion element 15 via a second conductive adhesive layer 14. Thus, in two adjacent photoelectric conversion elements 15, the second charge transport layer 7 of one photoelectric conversion element 15 and the transparent conductive film 4 of the other photoelectric conversion element 15 are electrically connected via the first conductive adhesive layer 9, the current collector electrode 11, and the second conductive adhesive layer 14.

[0242] Based on the manufacturing method described above, it is possible to manufacture efficiently. Figure 1The photoelectric conversion element module 1 shown is illustrated. Furthermore, the manufacturing method of the photoelectric conversion element module of the present invention is not limited to the above method; other steps besides those described above may be included as long as the desired effects of the present invention can be obtained.

[0243] Example

[0244] The present invention will now be described in detail based on embodiments, but the present invention is not limited to these embodiments.

[0245] Furthermore, the photoelectric conversion element modules manufactured through the various embodiments and comparative examples are all modules consisting of two photoelectric conversion elements connected in series (i.e., 2 connected in series), but the number of series connections can be appropriately selected according to the application.

[0246] Furthermore, the thickness of the porous membranes manufactured in the examples and comparative examples, the reduction in membrane thickness under pressure in the thickness direction, and the battery performance and performance retention of the photoelectric conversion element modules were determined using the following methods.

[0247] <Film thickness of porous membranes and reduction of film thickness under pressure in the thickness direction>

[0248] The thickness of the CNT membrane, a porous membrane containing carbon material, in the unpressurized state in the thickness direction, was measured using a thickness gauge while the membrane was sandwiched between two glass substrates.

[0249] Furthermore, the thickness of the CNT membrane, which is a porous membrane containing carbon material, was measured using a press at a temperature of 25°C with a pressure of 0.05 Pa in the thickness direction. The difference between the membrane thickness and the thickness under non-pressurized conditions was used to determine the reduction in membrane thickness under 0.05 Pa pressure in the thickness direction.

[0250] <Battery Performance>

[0251] As the light source, a simulated sunlight illumination device (PEC-L11 type, manufactured by Peccell Technologies Inc.) was used, which mounted an AM1.5G filter on a 150W xenon lamp light source. The light source was adjusted to 1 sun [AM1.5G, 100mW / cm²]. 2 (JISC8912 Level A)).

[0252] The photoelectric conversion element modules manufactured in each embodiment and comparative example were connected to a source meter (Type 2400 source meter, manufactured by Keithley Corporation) to measure the following current and voltage characteristics.

[0253] Under 1sun light, the output current was measured while the bias voltage was varied from -0.2V to 2.0V in 0.02V increments. The output current was measured by accumulating the values ​​after 0.1 seconds to 0.2 seconds after each voltage change.

[0254] Based on the above measurements of current and voltage characteristics, the short-circuit current density (mA / cm²) is calculated. 2 ), open-circuit voltage (V), form factor, and photoelectric conversion efficiency (%).

[0255] <Performance retention rate>

[0256] Using the photoelectric conversion element modules manufactured in the various embodiments and comparative examples, initial battery performance was evaluated using the method described above. Next, the photoelectric conversion element module was placed in a reliability test chamber (Yamato Scientific IH thermo-humidifier) ​​maintained at 45°C and 90% RH for 1000 hours in a dark, unpowered state. Then, using the photoelectric conversion element module after the reliability test, battery performance was evaluated using the method described above.

[0257] Then, using the conversion efficiency E1 (%) measured in the initial battery performance evaluation of the photoelectric conversion element module and the conversion efficiency E2 (%) measured in the battery performance evaluation after the reliability test, the performance retention rate (%) is calculated according to the following formula.

[0258] Performance retention rate (%) = (E2 / E1) × 100

[0259] A higher performance retention rate indicates better durability of the photoelectric conversion element module.

[0260] (Example 1)

[0261] Fabrication of a light-transmitting substrate with a transparent conductive film

[0262] A conductive glass substrate (manufactured by Sigma-Aldrich, thickness: 2.2 mm) with a fluorine-doped tin oxide (FTO) film (thickness: 600 nm) formed on its surface as a transparent conductive film was used. A portion of the FTO film was removed by etching. This resulted in a light-transmitting substrate (hereinafter referred to as "transparent conductive substrate") with the transparent conductive film (FTO film) patterned as two modules connected in series.

[0263] <Formation of the first charge transport layer>

[0264] A solution of di(acetylacetonate)diisopropyl titanate dissolved in isopropanol (manufactured by Sigma-Aldrich) is sprayed onto the surface of a transparent conductive film (FTO film) on a transparent conductive substrate using a spray thermal decomposition method. At this time, a base layer is formed at predetermined positions by setting a narrow strip of glass. Thus, in the transparent conductive film (FTO film) patterned as two connected modules, a base layer (a dense TiO2 layer, 30 nm thick) composed of titanium dioxide is further formed in the portion other than the portion in contact with the second conductive adhesive layer described later. Next, a solution of titanium dioxide slurry (manufactured by Sigma-Aldrich) diluted with ethanol was prepared. The resulting solution was then applied to the surface of the substrate by spin coating and dried on a hot plate at 120°C for 10 minutes. The coating film protruding from the substrate when viewed from above was wiped off, and then heat-treated at 450°C for 30 minutes to form a porous semiconductor layer composed of titanium dioxide (TiO2) (TiO2 porous layer, thickness 120 nm, average particle size of TiO2 particles: 20 nm), thus obtaining the first charge transport layer.

[0265] <Formation of the Geothermal Layer>

[0266] As a solution containing a perovskite compound precursor (1), an N,N-dimethylformamide (DMF) solution containing 1.0 M lead iodide (PbI2) and 1.0 M methylammonium iodide (CH3NH3I) was prepared. The resulting solution (1) was spin-coated onto the surface of the first charge transport layer while chlorobenzene was added dropwise, and then sintered at 100 °C for 10 minutes to form a perovskite layer (thickness: 450 nm) serving as the power generation layer. Subsequently, by removing the perovskite layer protruding from the surface of the first charge transport layer in top view, a power generation layer forming substrate with a pattern of two modules connected in series was obtained.

[0267] Fabrication of porous membranes containing carbon materials (CNT membranes)

[0268] A porous membrane (CNT membrane) containing a single layer of CNTs as carbon material was fabricated in the following order.

[0269] In 500 ml of an aqueous solution containing 2% sodium deoxycholate (DOC) as a dispersant, 1.0 g of carbon nanotubes (Zeon Corporation, Japan, product name "ZEONANO SG101", monolayer CNT (SGCNT), average diameter (Av): 3.5 nm, G / D ratio: 2.1, t-curve of unopened treatment bulging upwards) containing fibrous carbon nanostructures was added to obtain a coarse dispersion containing DOC as a dispersant. This coarse dispersion was then filled into a high-pressure homogenizer (Meriya Corporation, Japan, product name "BERYU SYSTEM PRO") equipped with a multi-stage pressure control device (multi-stage pressure reducer) that applies back pressure during dispersion, and dispersed at a pressure of 100 MPa. Specifically, while applying back pressure, shear force was applied to the coarse dispersion to disperse the fibrous carbon nanostructures containing monolayer CNTs, resulting in a dispersion of fibrous carbon nanostructures containing monolayer CNTs. In addition, the dispersion process is carried out for 10 minutes while the dispersion flowing out of the high-pressure homogenizer is sent back to the high-pressure homogenizer.

[0270] 50 g of the prepared fibrous carbon nanostructure dispersion containing monolayer CNTs was added to a 200 mL beaker, and 50 g of distilled water was added to prepare a solution diluted 2 times. Filtration was performed using a pressure-reducing filtration device equipped with a membrane filter at 0.09 MPa. After filtration, the CNT membrane formed on the membrane filter was washed by passing isopropanol and water separately through the pressure-reducing filtration device, followed by air circulation for 15 minutes. Next, the CNT membrane / membrane filter was peeled off from the membrane filter by immersing the prepared CNT membrane / membrane filter in ethanol, yielding a CNT membrane (A) as a porous membrane containing carbon material.

[0271] The resulting CNT membrane (A) is the same size as the membrane filter, exhibits excellent film-forming properties, and maintains its state even after being peeled from the filter, demonstrating excellent self-support. Furthermore, the membrane density of the resulting CNT membrane (A) was determined based on the volume and weight calculated from the membrane thickness measured by a contact height difference meter, and the result was a density of 0.85 g / cm³. 3 Furthermore, measurements were performed according to the above method, and the thickness of the CNT membrane (A), a porous membrane containing carbon material, was 20 μm without pressure in the thickness direction, and the reduction in thickness was 2 μm when pressure was applied at 0.05 Pa in the thickness direction.

[0272] <Formation of the Second Charge Transport Layer>

[0273] A CNT film (A) cut to a specified size was immersed in chlorobenzene for 10 seconds, and then the CNT film (A) was pulled out of the chlorobenzene to obtain a CNT film (1) impregnated with chlorobenzene. Then, a substrate layer CNT film (1) was formed by stacking the CNT film (1) on a hot plate heated to 100°C, and the resulting laminate was pressed (heat-pressed) from the CNT film (1) side with a pressure of 0.05 Pa in the thickness direction to form a second charge transport layer. Thus, two adjacent photoelectric conversion elements were formed on the light-transmitting substrate.

[0274] Manufacturing of Photoelectric Conversion Component Modules

[0275] A conductive adhesive composition A for forming a first conductive adhesive layer was prepared by adding up to 10% by mass of carbon black (average particle size: 120 nm) as the first conductive microparticle to an acrylic resin "TB3035B" (manufactured by Tri-Bond Corporation) as the adhesive material, and mixing it uniformly by a self-rotation-revolution mixer.

[0276] Next, "Micropearl AU" (a conductive microparticle with a gold-plated surface, representative shape: spherical, maximum size: 20 μm, average particle size: 20 μm) manufactured by Sekisui Chemicals Co., Ltd., was added to the acrylic resin "TB3035B" (manufactured by Sanken Co.) as the adhesive material, up to 13.5% by mass, and uniformly mixed by a rotary mixer to prepare conductive adhesive composition B for forming the second conductive adhesive layer.

[0277] Furthermore, using the same method as the above-mentioned transparent conductive substrate fabrication, a current collector substrate was fabricated in which the current collector electrodes are patterned as modules connected in series in two series on the substrate.

[0278] Then, using a dispensing machine, conductive adhesive composition A and conductive adhesive composition B are applied to designated positions on the transparent substrate where the photoelectric conversion elements are formed. Using a vacuum bonding device under reduced voltage, the current collector substrate is bonded to the designated positions. Afterwards, irradiation with a metal halide lamp forms a first conductive adhesive layer containing first conductive particles and a second conductive adhesive layer containing second conductive particles. This yields a photoelectric conversion element module formed by connecting two adjacent photoelectric conversion elements in series.

[0279] Furthermore, in the obtained photoelectric conversion element module, the second charge transport layer of one of the two adjacent photoelectric conversion elements is connected to the current collector electrode via a first conductive adhesive layer. Moreover, the portion of the current collector electrode extending towards the other photoelectric conversion element is connected via the second conductive adhesive layer to the portion of the transparent conductive film of the other photoelectric conversion element extending towards one photoelectric conversion element 15. Therefore, the second charge transport layer of one photoelectric conversion element and the transparent conductive film of the other photoelectric conversion element are electrically connected via the first conductive adhesive layer, the current collector electrode, and the second conductive adhesive layer.

[0280] The obtained photoelectric conversion element module was used to determine the battery performance and performance retention rate. The results are shown in Table 1.

[0281] Furthermore, by observing the cross-section of the photoelectric conversion element module using a scanning electron microscope, it can be confirmed that at least a portion of the first conductive particles 8 are embedded in the second charge transport layer 7.

[0282] (Example 2)

[0283] In the fabrication of the photoelectric conversion element module of Example 1, indium tin oxide (ITO) microparticles (average particle size: 30 nm) were used instead of carbon black (average particle size: 120 nm) as the first conductive microparticles. Otherwise, the photoelectric conversion element module was fabricated in the same manner as in Example 1. The resulting photoelectric conversion element module was used for measurements in the same manner as in Example 1. The results are shown in Table 1.

[0284] (Example 3)

[0285] In the fabrication of the photoelectric conversion element module of Example 1, a Ti layer serving as an auxiliary electrode was formed by sputtering using a mask in the portion where the second conductive adhesive layer is formed. Otherwise, the photoelectric conversion element module was fabricated in the same manner as in Example 1. The obtained photoelectric conversion element module was then measured in the same manner as in Example 1. The results are shown in Table 1.

[0286] (Comparative Example 1)

[0287] In the manufacture of the photoelectric conversion element module of Example 1, conductive adhesive composition A was not applied to a specified position on the light-transmitting substrate where the photoelectric conversion element is formed. Otherwise, the photoelectric conversion element module was manufactured in the same manner as in Example 1. Therefore, the first conductive adhesive layer is absent in the photoelectric conversion element of the obtained photoelectric conversion element module, and the second charge transport layer is directly bonded to the current collector electrode. Measurements were performed using the obtained photoelectric conversion element module in the same manner as in Example 1. The results are shown in Table 1.

[0288] (Comparative Example 2)

[0289] In the formation of the second charge transport layer in Example 1, a composite material film (film thickness: 150 nm) prepared by the method described below was used instead of the CNT film (A) which is a porous film containing carbon material. Furthermore, in the manufacture of the photoelectric conversion element module in Example 1, "Micropearl AU" (conductive microparticles with gold plating on the surface, representative shape: spherical, maximum size: 3 μm, average particle size: 3 μm) manufactured by Sekisui Chemicals Co., Ltd. was used instead of carbon black (average particle size: 120 nm) as the first conductive microparticle. Moreover, the average particle size (maximum size) of "Micropearl AU" (conductive microparticles with gold plating on the surface, representative shape: spherical) manufactured by Sekisui Chemicals Co., Ltd., used as the second conductive microparticle, was changed from 20 μm to 4 μm. Otherwise, the photoelectric conversion element module was manufactured in the same manner as in Example 1. Measurements were performed using the obtained photoelectric conversion element module in the same manner as in Example 1. The results are shown in Table 1.

[0290] <Fabrication of Composite Membranes>

[0291] A composite membrane was formed by forming a Spiro-MOTAD layer and an Au layer using the method described in non-patent literature (Energy Environ.Sci.,2018,11,952-959).

[0292] [Table 1]

[0293]

[0294] In Table 1:

[0295] "FTO" indicates fluorine-doped tin oxide.

[0296] "ITO" indicates indium tin oxide.

[0297] “MAPbI3” represents CH3NH3PbI3.

[0298] As shown in Table 1, the photoelectric conversion element modules of Examples 1 to 3, which are formed by stacking multiple transparent conductive films, a first charge transport layer, a power generation layer, and a second charge transport layer composed of a porous film containing carbon material on a light-transmitting substrate, and in two adjacent photoelectric conversion elements, the second charge transport layer of one photoelectric conversion element and the transparent conductive film of the other photoelectric conversion element are electrically connected via a first conductive adhesive layer, a current collector electrode, and a second conductive adhesive layer, have high photoelectric conversion efficiency and excellent durability.

[0299] On the other hand, it can be seen that the photoelectric conversion efficiency of the photoelectric conversion element module of Comparative Example 1, which does not use the first conductive adhesive layer, is poor.

[0300] Furthermore, it is known that the photoelectric conversion element module of Comparative Example 2, which uses a material other than a porous membrane containing carbon material as the second charge transport layer, has poor durability.

[0301] Industrial utilization potential

[0302] According to the present invention, a photoelectric conversion element module with high photoelectric conversion efficiency and excellent durability can be provided.

[0303] Explanation of reference numerals in the attached figures

[0304] 1: Photoelectric conversion element module

[0305] 2: Transparent conductive substrate

[0306] 3: Transparent substrate

[0307] 4: Transparent conductive film

[0308] 5: First charge transport layer

[0309] 6: Power Generation Layer

[0310] 7: Second charge transport layer

[0311] 8: First conductive particle

[0312] 9: First conductive adhesive layer

[0313] 10: Current collector electrode substrate

[0314] 11: Collector electrode

[0315] 12: Substrate

[0316] 13: Second conductive particles

[0317] 14: Second conductive adhesive layer

[0318] 15: Photoelectric conversion element

Claims

1. A photoelectric conversion element module having a plurality of photoelectric conversion elements formed on a light-transmitting substrate, The photoelectric conversion element is formed by sequentially stacking a transparent conductive film, a first charge transport layer, a power generation layer, and a second charge transport layer, starting from the light-transmitting substrate side. The second charge transport layer is composed of a porous membrane containing carbon material. In two adjacent photoelectric conversion elements, the second charge transport layer of one photoelectric conversion element is electrically connected to the transparent conductive film of the other photoelectric conversion element via a first conductive adhesive layer, a current collector electrode, and a second conductive adhesive layer. The first conductive adhesive layer includes first conductive microparticles, at least a portion of which are embedded in the second charge transport layer.

2. The photoelectric conversion element module according to claim 1, wherein, The carbon material includes carbon nanotubes.

3. The photoelectric conversion element module according to claim 2, wherein, The carbon nanotubes contain a single layer of carbon nanotubes.

4. The photoelectric conversion element module according to any one of claims 1 to 3, wherein, The first conductive adhesive layer contains first conductive microparticles. The first conductive microparticles comprise at least one of carbon materials and metal oxides.

5. The photoelectric conversion element module according to any one of claims 1 to 3, wherein, The first conductive adhesive layer contains first conductive microparticles. The second conductive adhesive layer contains second conductive microparticles. The average particle size of the second conductive particle is greater than the average particle size of the first conductive particle.

6. The photoelectric conversion element module according to any one of claims 1 to 3, wherein, The power generation layer contains perovskite compounds.

7. A method for manufacturing a photoelectric conversion element module, comprising a step of connecting two adjacent photoelectric conversion elements among a plurality of photoelectric conversion elements formed on a light-transmitting substrate. The photoelectric conversion element is formed by sequentially stacking a transparent conductive film, a first charge transport layer, a power generation layer, and a second charge transport layer, starting from the light-transmitting substrate side. The second charge transport layer is composed of a porous membrane containing carbon material. In two adjacent photoelectric conversion elements, the second charge transport layer of one photoelectric conversion element is electrically connected to the transparent conductive film of the other photoelectric conversion element via a first conductive adhesive layer, a current collector electrode, and a second conductive adhesive layer. The first conductive adhesive layer includes first conductive microparticles, at least a portion of which are embedded in the second charge transport layer.

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