Photoelectric conversion module and manufacturing method thereof

Abstract

A photoelectric conversion module (100) has a translucent substrate (1) and at least one photoelectric conversion element formed on the translucent substrate (1). Each of the at least one photoelectric conversion element is formed by laminating a transparent conductive film (2a), a first charge transport layer (3), a power generation layer (4), and a second charge transport layer (5) formed of a porous film containing a carbon material, in that order from the translucent substrate (1). A portion in the second charge transport layer (5) of the at least one photoelectric conversion element, said portion facing another transparent conductive film (2b) adjacent to the transparent conductive film (2a) of said photoelectric conversion element, is electrically connected to the other transparent conductive film (2b) via a conductive layer (7a) having a thickness larger than the thickness of the first charge transport layer (3) and the power generation layer (4) combined.

Description

[Technical Field]

[0001] The present invention relates to a photoelectric conversion module and a method for manufacturing the same. [Background technology]

[0002] Photoelectric conversion elements that convert light energy into electricity and can be used as solar cells are known (see, for example, Patent Document 1). There are various types of solar cells, such as perovskite solar cells that use a perovskite compound as a power generation layer. Photoelectric conversion elements are usually used in the form of a photoelectric conversion module having a light-transmitting substrate and one or more photoelectric conversion elements formed on the light-transmitting substrate (see, for example, Patent Documents 2 and 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6339037 [Patent Document 2] International Publication No. 2020 / 188777 [Patent Document 3] Patent No. 6646471 Summary of the Invention [Problem to be solved by the invention]

[0004] However, conventional photovoltaic conversion modules have room for improvement in terms of exhibiting excellent photovoltaic conversion efficiency and ease of manufacture.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a photoelectric conversion module that exhibits excellent photoelectric conversion efficiency and is easy to manufacture, and a method for manufacturing the same. [Means for solving the problem]

[0006] The photoelectric conversion module of the present invention includes a transparent substrate and one or more photoelectric conversion elements formed on the transparent substrate, each of the photoelectric conversion elements being formed by stacking, in order from the transparent substrate side, a transparent conductive film, a first charge transport layer, a power generation layer, and a second charge transport layer made of a porous film containing a carbon material, and a portion of the second charge transport layer of at least one of the photoelectric conversion elements facing another transparent conductive film adjacent to the transparent conductive film of the photoelectric conversion element is electrically connected to the other transparent conductive film via a conductive layer that is thicker than the combined thickness of the first charge transport layer and the power generation layer. This configuration allows the second charge transport layer of at least one photoelectric conversion element to be electrically connected to the other transparent conductive film while suppressing short circuits with a simple structure, thereby providing a photoelectric conversion module that exhibits excellent photoelectric conversion efficiency and is easy to manufacture.

[0007] In the present invention, the term "photoelectric conversion module" refers to a structure having a light-transmitting substrate and one or more photoelectric conversion elements formed on the light-transmitting substrate, and the photoelectric conversion module of the present invention includes not only those having a plurality of photoelectric conversion elements but also those having only one photoelectric conversion element. Furthermore, while photoelectric conversion modules usually have external extraction electrodes for extracting electric power to the outside and exterior materials for ensuring strength required for practical use, the photoelectric conversion module of the present invention also includes those that do not have these external extraction electrodes or exterior materials.

[0008] In the photoelectric conversion module of the present invention, the other transparent conductive film preferably constitutes an external extraction electrode. With this configuration, the second charge transport layer of at least one photoelectric conversion element can be electrically connected to the external extraction electrode while suppressing short circuits with a simple structure, thereby improving the photoelectric conversion efficiency and ease of manufacturing the photoelectric conversion module.

[0009] In the photoelectric conversion module of the present invention, it is preferable that the other transparent conductive film constitutes a part of the photoelectric conversion element. With such a configuration, it is possible to suppress short circuits with a simple structure and electrically connect the second charge transport layer of at least one photoelectric conversion element to the transparent conductive film of another photoelectric conversion element adjacent to the photoelectric conversion element, thereby improving the photoelectric conversion efficiency and ease of manufacturing of the photoelectric conversion module.

[0010] In the photovoltaic conversion module of the present invention, the carbon material preferably contains carbon nanotubes. With this configuration, the photovoltaic conversion efficiency of the photovoltaic conversion module can be increased.

[0011] In the photovoltaic conversion module of the present invention, the carbon nanotubes preferably include single-walled carbon nanotubes. With this configuration, the photovoltaic conversion efficiency of the photovoltaic conversion module can be increased.

[0012] In the photovoltaic conversion module of the present invention, the conductive layer preferably contains at least one of a carbon material, a metal, and a metal oxide. With this configuration, the photovoltaic conversion efficiency of the photovoltaic conversion module can be improved.

[0013] In the photoelectric conversion module of the present invention, the conductive layer is preferably formed within the plane of the second charge transport layer. With this configuration, the photoelectric conversion efficiency of the photoelectric conversion module can be improved.

[0014] In the photovoltaic conversion module of the present invention, the conductive layer is preferably formed from a conductive material and an insulating adhesive material. With this configuration, the photovoltaic conversion efficiency of the photovoltaic conversion module can be improved.

[0015] In the photovoltaic conversion module of the present invention, the power generation layer preferably contains a perovskite compound. With this configuration, the manufacturing cost of the photovoltaic conversion module can be reduced and the ease of manufacturing the photovoltaic conversion module can be improved.

[0016] Furthermore, the present invention provides a method for manufacturing a photoelectric conversion module having a translucent substrate and one or more photoelectric conversion elements formed on the translucent substrate, wherein each of the photoelectric conversion elements comprises, in order from the translucent substrate side, a transparent conductive film, a first charge transport layer, a power generation layer, and a second charge transport layer made of a porous film containing a carbon material, and the method includes a step of electrically connecting a portion of the second charge transport layer of at least one of the photoelectric conversion elements facing another transparent conductive film adjacent to the transparent conductive film of the photoelectric conversion element to the other transparent conductive film via a conductive layer that is thicker than the combined thickness of the first charge transport layer and the power generation layer. This configuration allows for a simple structure that suppresses short circuits while electrically connecting the second charge transport layer of at least one photoelectric conversion element to the other transparent conductive film, thereby facilitating the manufacture of a photoelectric conversion module that exhibits excellent photoelectric conversion efficiency. [Effects of the Invention]

[0017] According to the present invention, it is possible to provide a photoelectric conversion module that exhibits excellent photoelectric conversion efficiency and is easy to manufacture, and a method for manufacturing the same. [Brief explanation of the drawings]

[0018] [Figure 1A] 1 is a cross-sectional view showing a state during the manufacturing of a photovoltaic conversion module according to an embodiment of the present invention. [Figure 1B] 1B is a cross-sectional view showing a state when the disposition of a second charge transport layer is started from the state shown in FIG. 1A. FIG. [Figure 1C] 1C is a cross-sectional view showing the state after the formation of a second charge transport layer has been completed from the state shown in FIG. 1B. [Figure 2A] 1. FIG. 4 is a cross-sectional view showing a state during the manufacture of a modified example of the photovoltaic conversion module shown in FIG. [Figure 2B] 2B is a cross-sectional view showing the state when the disposition of a second charge transport layer is started from the state shown in FIG. 2A. FIG. [Figure 2C]2C is a cross-sectional view showing the state after the formation of the second charge transport layer has been completed from the state shown in FIG. 2B. [Figure 3A] 1 is a plan view showing an example of a connection structure between photoelectric conversion elements in a photoelectric conversion module. FIG. [Figure 3B] 10 is a plan view showing another example of a connection structure between photoelectric conversion elements in a photoelectric conversion module. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0019] The photovoltaic conversion module of the present invention is not particularly limited and can be used, for example, as a perovskite solar cell module. One embodiment of the photovoltaic conversion module of the present invention will be described in detail below with reference to the drawings.

[0020] (Photoelectric conversion module) FIG. 1C shows the configuration of a photovoltaic module 100 according to one embodiment of the present invention. FIGS. 1A and 1B show the photovoltaic module 100 in the middle of its manufacture. As shown in FIG. 1C, the photovoltaic module 100 includes a translucent substrate 1 and one or more photovoltaic elements 10 formed on the translucent substrate 1. Each photovoltaic element 10 includes, in order from the translucent substrate 1 side, a transparent conductive film 2, a first charge transport layer 3, a power generation layer 4, and a second charge transport layer 5 formed of a porous film containing a carbon material. Furthermore, a portion (hereinafter referred to as "opposing portion 5a") of the second charge transport layer 5 of at least one photovoltaic element 10 facing a transparent conductive film 2 (hereinafter referred to as "second transparent conductive film 2b") adjacent to the transparent conductive film 2 (hereinafter referred to as "first transparent conductive film 2a") of the photovoltaic element 10 is electrically connected to the second transparent conductive film 2b via a conductive layer 7 that is thicker than the combined thickness t of the first charge transport layer 3 and the power generation layer 4.

[0021] Here, the conductive layer 7 may be any material that can form an electrical connection, and may be formed from a carbon paste, a metal paste such as silver, or an adhesive containing conductive particles.

[0022] Forming an electrical connection via the conductive layer 7 thicker than the thickness t can prevent a short circuit from occurring between the second charge transport layer 5 and the first transparent conductive film 2a when the second charge transport layer 5 made of a porous film containing a carbon material is attached. That is, for example, if the facing portion 5a of the second charge transport layer 5 is directly attached to the second transparent conductive film 2b without the conductive layer 7, a short circuit is likely to occur between the second charge transport layer 5 and the first transparent conductive film 2a, but according to this embodiment, the occurrence of such a short circuit can be prevented.

[0023] Furthermore, according to this embodiment, the second charge transport layer 5 alone can function as both a hole transport layer and a current collecting electrode.

[0024] Therefore, according to this embodiment, the second charge transport layer 5 of at least one photoelectric conversion element 10 can be electrically connected to the second transparent conductive film 2b while suppressing short circuits with a simple structure, thereby providing a photoelectric conversion module 100 that exhibits excellent photoelectric conversion efficiency and is easy to manufacture.

[0025] Furthermore, although not particularly limited, the second transparent conductive film 2b constitutes the external extraction electrode 6 in this embodiment. Because the second charge transport layer 5 is made of a porous film, using it as the external extraction electrode is undesirable because moisture easily penetrates from the outside through the porous second charge transport layer 5. Therefore, as in this embodiment, it is preferable to form the external extraction electrode 6 using the second transparent conductive film 2b. This configuration allows the second charge transport layer 5 of at least one photoelectric conversion element 10 to be electrically connected to the external extraction electrode 6 while suppressing short circuits with a simple structure, thereby improving the photoelectric conversion efficiency and ease of manufacturing of the photoelectric conversion module 100. Furthermore, it facilitates achieving excellent sealing to suppress the penetration of moisture from the outside, thereby facilitating the realization of excellent reliability.

[0026] Furthermore, the second transparent conductive film 2b may constitute a part (i.e., the transparent conductive film 2) of another photoelectric conversion element (not shown) adjacent to the photoelectric conversion element 10 having the first transparent conductive film 2a. With such a configuration, it is possible to suppress short circuits with a simple structure and electrically connect the second charge transport layer 5 of at least one photoelectric conversion element 10 to the transparent conductive film 2 of the other photoelectric conversion element adjacent to the photoelectric conversion element 10, thereby improving the photoelectric conversion efficiency and ease of manufacturing of the photoelectric conversion module 100.

[0027] In this case, the conductive layer 7 may be provided between two adjacent photoelectric conversion elements 10 (or power generation layers 4), as shown in Fig. 3A, or may be provided at a position shifted from between two adjacent photoelectric conversion elements 10 (or power generation layers 4), as shown in Fig. 3B. In Figs. 3A and 3B, the two-dot chain lines indicate the gaps between adjacent transparent conductive films 2 (see Fig. 1C).

[0028] In this embodiment, as shown in Figures 3A and 3B, for example, the conductive layer 7 is preferably formed within the plane of the second charge transport layer 5. That is, when viewed from a direction perpendicular to the light-transmitting substrate 1, it is preferable that the entire conductive layer 7 overlaps the second charge transport layer 5. With this configuration, short circuits can be further suppressed, thereby increasing the photoelectric conversion efficiency of the photoelectric conversion module 100.

[0029] 2A to 2C, the photovoltaic conversion module 100 of this embodiment preferably has the conductive layer 7 formed of a conductive material 7a and an insulating adhesive material 7b. In this case, the gap between the first transparent conductive film 2a and the second transparent conductive film 2b and the exposed portion of the first transparent conductive film 2a can be at least partially covered with the insulating adhesive material 7b, thereby further suppressing short circuits and thereby increasing the photovoltaic conversion efficiency of the photovoltaic conversion module 100.

[0030] Furthermore, the conductive layer 7 of this embodiment or the conductive material 7a of the above-described modified example preferably contains at least one of a carbon material, a metal, and a metal oxide. With this configuration, the photoelectric conversion efficiency of the photoelectric conversion module 100 can be improved.

[0031] Each component of the photoelectric conversion element 10 will be described below.

[0032] <Transparent substrate 1> 1C, the light-transmitting substrate 1 constitutes the base of the photoelectric conversion module 100. The light-transmitting substrate 1 is not particularly limited, and examples thereof include a substrate made of glass or synthetic resin, and a film made of synthetic resin.

[0033] Examples of the glass that constitutes the light-transmitting substrate 1 include inorganic glass such as soda glass.

[0034] Examples of synthetic resins that can be used to form the light-transmitting substrate 1 include polyacrylic resin, polycarbonate resin, polyester resin, polyimide resin, polystyrene resin, polyvinyl chloride resin, polyamide resin, and polycycloolefin resin. Among these, from the viewpoint of obtaining a thin, lightweight, and flexible photoelectric conversion element 10, polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) are preferred synthetic resins.

[0035] The thickness of the light-transmitting substrate 1 is not particularly limited as long as it can maintain its shape as a substrate. The thickness of the light-transmitting substrate 1 can be, for example, 0.1 mm or more and 10 mm or less.

[0036] <Transparent conductive film 2> The transparent conductive film 2 is a film made of a metal oxide formed on the surface of the light-transmitting substrate 1. By providing the transparent conductive film 2, the surface of the light-transmitting substrate 1 can be made conductive.

[0037] Examples of metal oxides constituting the transparent conductive film 2 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), gallium oxide / zinc oxide (GZO), etc. The first transparent conductive film 2a and the second transparent conductive film 2b may be made of the same metal oxide or different metal oxides.

[0038] The thickness of the transparent conductive film 2 is not particularly limited as long as it is a thickness that can impart the desired conductivity to the light-transmitting substrate 1, and can be, for example, 1 nm or more and 1 μm or less.

[0039] <First charge transport layer 3> The first charge transport layer 3 is a layer that functions as a charge transport layer and is preferably made of an n-type semiconductor. The first charge transport layer 3 is preferably made of two layers, an underlayer and a porous semiconductor layer, but the first charge transport layer 3 may be a single layer made of an n-type semiconductor.

[0040] <Underlayer> The underlayer is a layer that is optionally provided between the light-transmitting substrate 1 and the porous semiconductor layer. By providing the underlayer, the light-transmitting substrate 1 and the transparent conductive film 2 are prevented from coming into direct contact with the porous semiconductor layer. This prevents loss of electromotive force, thereby improving the photoelectric conversion efficiency of the photoelectric conversion element 10.

[0041] The underlayer may be a porous film or a non-porous dense film, as long as it is made of, for example, an n-type semiconductor. However, from the viewpoint of sufficiently preventing contact between the light-transmitting substrate 1 and the transparent conductive film 2 and the porous semiconductor layer, the underlayer is preferably a non-porous dense film. The thickness of the underlayer is not particularly limited and can be, for example, 1 nm or more and 500 nm or less. Furthermore, the underlayer may optionally contain an insulating material other than an n-type semiconductor in a proportion that does not impair the properties of the underlayer as an n-type semiconductor.

[0042] <Porous semiconductor layer> The porous semiconductor layer is a porous layer. When the first charge transport layer 3 includes a porous semiconductor layer, the photoelectric conversion efficiency of the photoelectric conversion element 10 can be improved.

[0043] The thickness of the porous semiconductor layer is not particularly limited, but is usually 5 nm or more, preferably 10 nm or more, and usually 500 nm or less, preferably 100 nm or less. The porous semiconductor layer may be formed from one layer or multiple layers.

[0044] <Power generation layer 4> The power generation layer 4 is a layer made of a material that generates electromotive force by absorbing light, and is preferably a layer containing a perovskite compound, and more preferably a layer made of a perovskite compound (perovskite layer).

[0045] Here, the perovskite compound constituting the power generation layer 4 is not particularly limited, and known perovskite compounds can be used. Specifically, examples of perovskite compounds include CH3NH3PbI3, CH3NH3PbBr3, (CH3(CH2)nCHCH3N H3)2PbI4[n=5-8], (C6H5C2H4NH3)2PbBr4, etc. can be used.

[0046] The thickness of the power generation layer 4 is not particularly limited, but is preferably 100 nm or more, more preferably 200 nm or more, and is preferably 1 μm or less, more preferably 800 nm or less. By making the thickness of the power generation layer 4 100 nm or more, the electromotive force of the power generation layer 4 can be increased.

[0047] <Second charge transport layer 5> The second charge transport layer 5 is a layer made of a porous film containing a carbon material. The carbon material contained in the second charge transport layer 5 is not particularly limited, but preferably contains carbon nanotubes (hereinafter referred to as CNTs), and the CNTs contained in the second charge transport layer 5 preferably contain single-walled CNTs. With this configuration, the photoelectric conversion efficiency of the photoelectric conversion module 100 can be improved.

[0048] The second charge transport layer 5 is preferably a layer made of a porous free-standing sheet. This configuration improves the shape stability of the second charge transport layer 5, making it possible to easily increase the area of ​​the photoelectric conversion element 10. Furthermore, by including an ionic compound inside the porous free-standing sheet, the photoelectric conversion efficiency of the photoelectric conversion module 100 can be improved.

[0049] In this embodiment, the porous free-standing sheet refers to a sheet having a plurality of pores formed therein, which maintains its shape even without a support. That is, the porous free-standing sheet maintains its shape without tearing even when the porous free-standing sheet is immersed in a predetermined solution, pulled out, and then attached to an object to be attached. Furthermore, the porous free-standing sheet does not tear or deform even when, for example, chlorobenzene, which is a poor solvent for perovskite compounds, is dropped onto the sheet or when the porous free-standing sheet is handled using a jig for attaching the sheet. The porous free-standing sheet has a thickness of 1 μm to 200 μm, an area of ​​1 mm, and a thickness of 1 μm to 200 μm. 2 ~100c m 2 It is preferable that the sheet maintains its shape without a support at this size.

[0050] The porous free-standing sheet must contain at least single-walled CNTs, preferably a sheet made of single-walled CNTs, and more preferably a sheet made of buckypaper. The use of a porous free-standing sheet containing at least single-walled CNTs can impart to the second charge transport layer 5 the functions of an excellent hole transport layer and a collecting electrode.

[0051] <<Porous self-standing sheet>> The single-walled CNTs contained in the porous free-standing sheet preferably have the following properties.

[0052] -(3σ / Av)- The single-walled CNTs contained in the porous free-standing sheet preferably have a ratio (3σ / Av) of the standard deviation (σ) of diameters multiplied by 3 (3σ) to the average diameter (Av) of the single-walled CNTs 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, even if the amount of single-walled CNTs contained in the porous free-standing sheet is small, the second charge transport layer 5 can be provided with sufficient functions as a hole transport layer and a current collecting electrode.

[0053] The "average diameter (Av) of single-walled carbon nanotubes" and the "standard deviation of the diameters of single-walled carbon nanotubes (σ: standard deviation)" can be determined by measuring the diameters (outer diameters) of 100 randomly selected single-walled carbon nanotubes using a transmission electron microscope. The average diameter (Av) and standard deviation (σ) of single-walled carbon nanotubes may be adjusted by changing the manufacturing method or manufacturing conditions of the single-walled carbon nanotubes, or by combining multiple types of single-walled carbon nanotubes obtained by different manufacturing methods.

[0054] -Average diameter of single-walled CNTs (Av)- The average diameter (Av) of the single-walled CNTs is preferably 0.5 nm or more, more preferably 1 nm or more, and preferably 15 nm or less, and more preferably 10 nm or less. When the average diameter (Av) of the single-walled CNTs is 0.5 nm or more, aggregation of the single-walled CNTs can be suppressed, and the dispersibility of the single-walled CNTs in the second charge transport layer 5 can be improved. Furthermore, when the average diameter (Av) of the single-walled CNTs is 15 nm or less, the second charge transport layer 5 can fully function as a current collecting electrode.

[0055] -t-plot- The single-walled CNTs preferably have a convex t-plot obtained from the adsorption isotherm. Such single-walled CNTs are more preferably those that have not been subjected to an aperture treatment. The use of single-walled CNTs that have a convex t-plot obtained from the adsorption isotherm allows for the production of a second charge transport layer 5 with excellent strength.

[0056] The inflection point of the t-plot for single-walled CNTs is preferably in the range satisfying 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.

[0057] Measurement of the adsorption isotherm of single-walled CNT, creation of t-plots, and analysis of the t-plots can be performed using, for example, a commercially available measuring device, "BELSORP (registered trademark)-mini" (manufactured by BEL Japan Co., Ltd.).

[0058] Single-walled CNTs having the properties described above can be efficiently produced by, for example, a method in which raw material compounds and a carrier gas are supplied to a substrate having a catalyst layer for CNT production on its surface, and CNTs are synthesized by chemical vapor deposition (CVD) using a method in which the catalytic activity of the catalyst layer is dramatically improved by adding a trace amount of oxidizing agent (catalytic activator) to the system (super-growth method; see WO 2006 / 011655), and the catalyst layer is formed on the substrate surface using a wet process.

[0059] Among these, from the viewpoint of easily obtaining a porous free-standing sheet with a large thickness, it is preferable to use single-walled CNTs obtained by the super-growth method.

[0060] Furthermore, the porous free-standing sheet preferably contains, within the porous free-standing sheet, the material (e.g., perovskite compound) that constitutes the power generation layer 4, or a portion of the material (e.g., material that constitutes the perovskite compound) that constitutes the power generation layer 4. More specifically, the porous free-standing sheet preferably contains, within the multiple pores of the porous free-standing sheet, the material (e.g., perovskite compound) that constitutes the power generation layer 4, or a portion of the material (e.g., material that constitutes the perovskite compound) that constitutes the power generation layer.

[0061] The proportion of single-walled CNTs contained in the porous free-standing sheet is not particularly limited, but is preferably 50% by mass or more, and more preferably 75% by mass or more.

[0062] Furthermore, materials other than single-walled CNTs that may be optionally contained in the porous free-standing sheet include, for example, organic and inorganic materials as p-type semiconductors, and fibrous carbon nanostructures other than single-walled CNTs.

[0063] Examples of organic materials that can be contained in the porous free-standing sheet include 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamino)-9,9'-spirobifluorene (spiro-MeOTAD), poly(3-hexylthiophene) (P3HT), and polytriallylamine (PTAA).

[0064] Examples of inorganic materials that can be contained in the porous free-standing sheet include CuI, CuSCN, CuO, and Cu2O.

[0065] The thickness of the porous free-standing sheet is preferably 20 μm or more, more preferably 30 μm or more, and is preferably 200 μm or less, and more preferably 80 μm or less. If the thickness of the porous free-standing sheet is 20 μm or more and 200 μm or less, the second charge transport layer 5 can exhibit a more excellent function as a collecting electrode.

[0066] <<Method of manufacturing porous freestanding sheets>> The method for producing a porous free-standing sheet is not particularly limited, and for example, a method including a step of removing the solvent from a fibrous carbon nanostructure dispersion containing fibrous carbon nanostructures containing at least single-walled CNTs, a dispersant, and a solvent to form a porous free-standing sheet (film formation step) can be adopted. Furthermore, the method for producing a porous free-standing sheet may optionally include a step of dispersing a crude dispersion containing fibrous carbon nanostructures containing at least single-walled CNTs, a dispersant, and a solvent to prepare the fibrous carbon nanostructure dispersion (dispersion preparation step) before the film formation step.

[0067] -Dispersion liquid preparation process- In the dispersion preparation step, a crude dispersion containing at least single-walled CNT-containing fibrous carbon nanostructures, a dispersant, and a solvent is preferably subjected to a dispersion treatment that produces, but is not particularly limited to, a cavitation effect or a disintegration effect, as described below, to disperse the single-walled CNT-containing fibrous carbon nanostructures and prepare a fibrous carbon nanostructure dispersion. By performing a dispersion treatment that produces a cavitation effect or a disintegration effect in this manner, a fibrous carbon nanostructure dispersion in which the single-walled CNT-containing fibrous carbon nanostructures are well dispersed can be obtained. Furthermore, by producing a porous free-standing sheet using fibrous carbon nanostructures in which the single-walled CNTs are well dispersed, the single-walled CNTs can be uniformly dispersed, resulting in a porous free-standing sheet with excellent properties such as electrical conductivity, thermal conductivity, and mechanical properties. The fibrous carbon nanostructure dispersion used to produce the porous free-standing sheet may also be prepared by dispersing the single-walled CNT-containing fibrous carbon nanostructures in a solvent using a known dispersion treatment other than the above.

[0068] The fibrous carbon nanostructures used in preparing the fibrous carbon nanostructure dispersion may be any that contain at least single-walled CNTs, and may be, for example, a mixture of single-walled CNTs and fibrous carbon nanostructures other than single-walled CNTs (e.g., multi-walled CNTs).

[0069] Here, the content ratio of single-walled CNTs and fibrous carbon nanostructures other than single-walled CNTs in the fibrous carbon nanostructure dispersion can be, for example, 50 / 50 to 75 / 25 in mass ratio (single-walled CNTs / fibrous carbon nanostructures other than single-walled CNTs).

[0070] =Dispersant= The dispersant used in preparing the fibrous carbon nanostructure dispersion is not particularly limited as long as it can disperse at least the fibrous carbon nanostructures containing single-walled CNTs and can be dissolved in the solvent used in preparing the fibrous carbon nanostructure dispersion. Examples of such dispersants that can be used include surfactants, synthetic polymers, and natural polymers.

[0071] Examples of surfactants include sodium dodecyl sulfonate, sodium deoxycholate, sodium cholate, and sodium dodecylbenzenesulfonate.

[0072] Examples of synthetic polymers include polyether diols, polyester diols, polycarbonate diols, polyvinyl alcohol, partially saponified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, acetal group-modified polyvinyl alcohol, butyral group-modified polyvinyl alcohol, silanol group-modified polyvinyl alcohol, ethylene-vinyl alcohol copolymer, ethylene-vinyl alcohol-vinyl acetate copolymer resin, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, acrylic resins, epoxy resins, modified epoxy resins, phenoxy resins, modified phenoxy resins, phenoxy ether resins, phenoxy ester resins, fluorine-based resins, melamine resins, alkyd resins, phenolic resins, polyacrylamide, polyacrylic acid, polystyrene sulfonic acid, polyethylene glycol, and polyvinylpyrrolidone.

[0073] Further, examples of natural polymers include polysaccharides such as starch, pullulan, dextran, dextrin, guar gum, xanthan gum, amylose, amylopectin, alginic acid, gum arabic, carrageenan, chondroitin sulfate, hyaluronic acid, curdlan, chitin, chitosan, and cellulose, as well as salts or derivatives thereof, where derivatives refer to conventionally known compounds such as esters and ethers.

[0074] These dispersants can be used alone or in combination of two or more. Among them, surfactants are preferred as dispersants because they have excellent dispersibility for fibrous carbon nanostructures including single-walled CNTs, and sodium deoxycholate is more preferred.

[0075] =Solvent= The solvent for the fibrous carbon nanostructure dispersion is not particularly limited, and examples thereof include water, alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, t-butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, and amyl alcohol, ketones such as acetone, methyl ethyl ketone, and cyclohexanone, esters such as ethyl acetate and butyl acetate, ethers such as diethyl ether, dioxane, and tetrahydrofuran, amide-based polar organic solvents such as N,N-dimethylformamide and N-methylpyrrolidone, and aromatic hydrocarbons such as toluene, xylene, chlorobenzene, orthodichlorobenzene, and paradichlorobenzene. These solvents may be used alone or in combination of two or more.

[0076] In the dispersion liquid preparation step, it is preferable to carry out a dispersion treatment that can obtain, for example, the cavitation effect or the disintegration effect described below.

[0077] ~Dispersion processing that produces a cavitation effect~ Dispersion treatment that utilizes the cavitation effect is a dispersion method that utilizes shock waves generated by the bursting of vacuum bubbles generated in water when high energy is applied to the liquid. This dispersion method can be used to effectively disperse single-walled CNTs.

[0078] Specific examples of dispersion treatments that can achieve the cavitation effect include dispersion treatment using ultrasonic waves, dispersion treatment using a jet mill, and dispersion treatment using high-shear stirring. These dispersion treatments may be performed alone or in combination. More specifically, for example, ultrasonic homogenizers, jet mills, and high-shear stirring devices are preferably used. These devices may be conventionally known.

[0079] When using an ultrasonic homogenizer to disperse single-walled CNTs, the crude dispersion liquid is irradiated with ultrasonic waves using the ultrasonic homogenizer. The irradiation time can be appropriately set depending on the amount of single-walled CNTs, and is, for example, preferably 3 minutes or more, more preferably 30 minutes or more, and preferably 5 hours or less, more preferably 2 hours or less. Furthermore, for example, the output is preferably 20 W or more and 500 W or less, more preferably 100 W or more and 500 W or less, and the temperature is preferably 15 °C or more and 50 °C or less.

[0080] Furthermore, when a jet mill is used, the number of times of treatment may be appropriately set depending on the amount of single-walled CNTs, etc., and is, for example, preferably 2 times or more, more preferably 5 times or more, and preferably 100 times or less, more preferably 50 times or less. Furthermore, 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.

[0081] Furthermore, when high shear mixing is used, the coarse dispersion can be stirred and sheared using a high shear mixing device. The faster the rotation speed, the better. For example, the operating time (the time the machine is rotating) is preferably 3 minutes to 4 hours, the peripheral speed is preferably 5 m / s to 50 m / s, and the temperature is preferably 15°C to 50°C.

[0082] It is more preferable that the dispersion treatment that produces the above-mentioned cavitation effect is carried out at a temperature of 50° C. or less, because this suppresses changes in concentration due to evaporation of the solvent.

[0083] ~Dispersion processing that produces a crushing effect~ Dispersion treatments that produce a crushing effect are not only able to uniformly disperse single-walled CNTs in a solvent, but are also more advantageous than dispersion treatments that produce the cavitation effect described above in that they can suppress damage to single-walled CNTs caused by shock waves when bubbles disappear.

[0084] In the dispersion process that produces this disintegration effect, shear force is applied to the coarse dispersion to disintegrate and disperse the aggregates of fibrous carbon nanostructures containing single-walled CNTs, and then back pressure is applied to the coarse dispersion, and the coarse dispersion is cooled as necessary, thereby suppressing the generation of bubbles and uniformly dispersing the single-walled CNTs in the solvent.

[0085] When a back pressure is applied to the crude dispersion, the back pressure applied to the crude dispersion may be reduced to atmospheric pressure in one go, but it is preferable to reduce the pressure in multiple stages.

[0086] -Film forming process- In the film-forming step, the solvent is removed from the above-mentioned fibrous carbon nanostructure dispersion to form a porous free-standing sheet. Specifically, in the film-forming step, the solvent is removed from the fibrous carbon nanostructure dispersion to form a porous free-standing sheet, for example, by using either of the following methods (A) and (B). (A) A method in which a dispersion liquid of fibrous carbon nanostructures is applied to a film-forming substrate, and then the applied dispersion liquid of fibrous carbon nanostructures is dried. (B) A method in which a fibrous carbon nanostructure dispersion is filtered using a porous film-forming substrate, and the resulting filtrate is dried.

[0087] [Film forming base material] Here, the film-forming substrate is not particularly limited, and any known substrate can be used.

[0088] Specifically, in the above-mentioned method (A), examples of the film-forming substrate onto which the fibrous carbon nanostructure dispersion is applied include resin substrates, glass substrates, etc. Here, examples of the resin substrate include substrates made of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polytetrafluoroethylene (PTFE), polyimide, polyphenylene sulfide, aramid, polypropylene, polyethylene, polylactic acid, polyvinyl chloride, polycarbonate, polymethyl methacrylate, alicyclic acrylic resin, cycloolefin resin, triacetyl cellulose, etc. Furthermore, examples of the glass substrate include substrates made of ordinary soda glass.

[0089] In the above method (B), examples of the film-forming substrate for filtering the fibrous carbon nanostructure dispersion include filter paper and porous sheets made of cellulose, nitrocellulose, alumina, and the like.

[0090] [Coating] In the above method (A), the fibrous carbon nanostructure dispersion can be applied to the film-forming substrate by a known coating method, such as dipping, roll coating, gravure coating, knife coating, air knife coating, roll knife coating, die coating, screen printing, spray coating, or gravure offset.

[0091] [Filtration] In the above method (B), the fibrous carbon nanostructure dispersion can be filtered using a film-forming substrate by any known filtration method, such as natural filtration, reduced pressure filtration, pressure filtration, centrifugal filtration, etc.

[0092] [Drying] The fibrous carbon nanostructure dispersion applied to the film-forming substrate in the above method (A) or the filtered product obtained in the above method (B) can be dried by a known drying method. Examples of the drying method include hot air drying, vacuum drying, hot roll drying, and infrared irradiation. The drying temperature is not particularly limited, but is usually room temperature to 200°C, and the drying time is not particularly limited, but is usually 0.1 to 150 minutes.

[0093] <Post-treatment of porous freestanding sheets> Here, the porous free-standing sheet formed as described above typically contains the components contained in the fibrous carbon nanostructure dispersion, such as single-walled CNTs, fibrous carbon nanostructures other than single-walled CNTs, and dispersants, in the same proportions as in the fibrous carbon nanostructure dispersion. Therefore, in the method for producing a porous free-standing sheet, the porous free-standing sheet formed in the film formation step may optionally be washed to remove the dispersant from the porous free-standing sheet. Removing the dispersant from the porous free-standing sheet can further improve the properties of the porous free-standing sheet, such as its conductivity.

[0094] The porous free-standing sheet can be washed by contacting it with a solvent capable of dissolving the dispersant and dissolving the dispersant in the porous free-standing sheet into the solvent. The solvent capable of dissolving the dispersant in the porous free-standing sheet is not particularly limited, and the solvents described above that can be used as solvents for the fibrous carbon nanostructure dispersion can be used, preferably the same solvents as the fibrous carbon nanostructure dispersion. The contact between the porous free-standing sheet and the solvent can be achieved by immersing the porous free-standing sheet in the solvent or by applying the solvent to the porous free-standing sheet. After washing, the porous free-standing sheet can be dried using a known method.

[0095] Furthermore, when producing a porous free-standing sheet, the porous free-standing sheet formed in the film formation step may be optionally pressed to further increase the density, etc., to adjust the voids as needed. From the viewpoint of suppressing deterioration of properties due to damage or destruction of the single-walled CNTs, the pressing pressure during pressing is preferably less than 3 MPa, and it is more preferable not to perform pressing.

[0096] Furthermore, each photoelectric conversion element in the photoelectric conversion module of the present invention may further comprise other layers, etc., as long as the order of the above-mentioned components is maintained and the effect of the present invention is not impaired.

[0097] According to this embodiment, it is possible to provide a photoelectric conversion module 100 that exhibits excellent photoelectric conversion efficiency and is easy to manufacture. The photoelectric conversion module of the present invention is not limited to the above-described configuration, and may include components other than those described above, as long as the effects of the present invention are not impaired.

[0098] (Method of manufacturing a photoelectric conversion module) Next, one embodiment of the method for manufacturing a photovoltaic conversion module of the present invention will be described in detail with reference to the drawings. The method for manufacturing a photovoltaic conversion module according to this embodiment is a method for manufacturing the photovoltaic conversion module 100 according to one embodiment of the present invention described with reference to FIG. 1C.

[0099] As shown in Figures 1A to 1C, the manufacturing method of the photoelectric conversion module according to this embodiment includes a step (hereinafter referred to as the connecting step) of electrically connecting the opposing portion 5a of the second charge transport layer 5 of at least one photoelectric conversion element 10, which faces the second transparent conductive film 2b adjacent to the first transparent conductive film 2a of the photoelectric conversion element 10, to the second transparent conductive film 2b via a conductive layer 7 that is thicker than the combined thickness t of the first charge transport layer 3 and the power generation layer 4.

[0100] In the method for manufacturing a photoelectric conversion module according to this embodiment, the second transparent conductive film 2b forms the external extraction electrode 6, but this is not limiting, and the second transparent conductive film 2b may, for example, form part (i.e., the transparent conductive film 2) of another photoelectric conversion element (not shown) adjacent to the photoelectric conversion element 10 having the first transparent conductive film 2a, as described above. In this case, the conductive layer 7 may be arranged as shown in Fig. 3A or as shown in Fig. 3B, as described above.

[0101] The method for manufacturing a photovoltaic conversion module according to this embodiment can also be applied to the manufacturing of a photovoltaic conversion module 100 according to the modified example shown in FIGS. 2A to 2C.

[0102] The method for manufacturing the photovoltaic conversion module according to this embodiment will be described in more detail below. Note that the components of the photovoltaic conversion module 100 can be those listed in the "Photovoltaic Conversion Module" section.

[0103] <Preparation of Light-Transmitting Substrate 1> In the method for manufacturing a photoelectric conversion module according to this embodiment, first, a light-transmitting substrate 1 is prepared.

[0104] <Formation of transparent conductive film 2> Next, a transparent conductive film 2 is formed on the light-transmitting substrate 1. The method for forming the transparent conductive film 2 is not particularly limited, and known methods such as sputtering and vapor deposition can be used. Note that the formation of the transparent conductive film 2 may be omitted by using a commercially available light-transmitting substrate on the surface of which a transparent conductive film is formed.

[0105] <Formation of First Charge Transport Layer 3> Furthermore, a first charge transport layer 3 is formed on the transparent conductive film 2. The first charge transport layer 3 can be obtained, for example, by forming an underlayer on the transparent conductive film 2 and then forming a porous semiconductor layer thereon.

[0106] [Formation of Underlayer] The method for forming the underlayer is not particularly limited, and for example, the underlayer can be formed by spraying a solution containing a material for forming an n-type semiconductor onto the transparent conductive film 2.

[0107] Here, examples of methods for spraying the fine particles include spray pyrolysis, aerosol deposition, electrostatic spray, and cold spray.

[0108] [Formation of Porous Semiconductor Layer] The method for forming the porous semiconductor layer is not particularly limited, and for example, the porous semiconductor layer can be formed by applying a solution containing a precursor of an n-type semiconductor onto the underlayer by spin coating or the like, and then drying.

[0109] Here, examples of precursors for n-type semiconductors include titanium tetrachloride (TiCl4), peroxide, and the like. Examples include titanium alkoxides such as titanium alkoxide (PTA), titanium ethoxide, and titanium isopropoxide (TTIP); and metal alkoxides such as zinc alkoxide, alkoxysilane, zirconium alkoxide, and titanium diisopropoxide bis(acetylacetonate).

[0110] The solvent used for the solution containing the precursor of the n-type semiconductor is not particularly limited, and for example, an alcohol solution such as ethanol can be used.

[0111] Furthermore, the temperature and time for drying the solution applied onto the underlayer are not particularly limited, and may be adjusted appropriately depending on the type of n-type precursor and the type of solvent used.

[0112] <Formation of power generation layer 4> Then, the power generation layer 4 is formed on the first charge transport layer 3. The method for forming the power generation layer 4 includes, but is not limited to, vacuum deposition and coating methods. For example, the power generation layer 4 can be formed by coating a precursor-containing solution containing a precursor of a perovskite compound on the first charge transport layer 3 and baking it. Here, the precursor of the perovskite compound is, for example, lead iodide (PbI2 ), methylammonium iodide (CH3NH3I), etc. The solvent contained in the precursor-containing solution is not particularly limited, and for example, N,N-dimethylformamide, dimethyl sulfoxide, etc. can be used. After applying these solutions, it is also possible to promote the precipitation of the perovskite compound by using a poor solvent. In this specification, a poor solvent refers to a solvent in which the perovskite compound does not substantially change during the preparation process. If no external changes, such as cloudiness of the film, are observed by visual observation during the preparation process, it can be said that the perovskite compound does not substantially change.

[0113] Here, the concentration of the precursor of the perovskite compound in the precursor-containing solution may be appropriately selected depending on the solubility of the materials that make up the perovskite compound, and may be, for example, about 0.5M to 1.5M.

[0114] The method for applying the precursor-containing solution onto the first charge transport layer 3 is not particularly limited, and any known application method such as spin coating, spraying, or bar coating can be used.

[0115] <Connection process> After the power generation layer 4 is formed, a connection step is carried out as shown in Figures 1A to 1C. In the connection step, a second charge transport layer 5 prepared in advance is laminated on the power generation layer 4, and the opposing portion 5a of the second charge transport layer 5 is electrically connected to the second transparent conductive film 2b via a conductive layer 7 formed in advance. This will be explained in more detail below.

[0116] <<Formation of Conductive Layer 7>> Before the connecting step, a conductive layer 7 is formed on the second transparent conductive film 2b. The timing of forming the conductive layer 7 is not particularly limited as long as it is formed before the connecting step.

[0117] <<Preparation of Second Charge Transport Layer 5>> Before the connecting step, the second charge transport layer 5 is prepared. There are no particular limitations on the timing of preparing the second charge transport layer 5, as long as it is prepared before the connecting step.

[0118] <<Attachment of second charge transport layer 5>> After the power generation layer 4 and the conductive layer 7 are formed and the second charge transport layer 5 is prepared, the connection process can be carried out by attaching the second charge transport layer 5 to the upper surfaces of the power generation layer 4 and the conductive layer 7, as shown in Figures 1B to 1C.

[0119] The second charge transport layer 5 is attached by, for example, laminating the porous free-standing sheet on the power generation layer 4 while the bonding surface of at least one of the porous free-standing sheet constituting the second charge transport layer 5 and the power generation layer 4 retains a solvent (hereinafter referred to as solvent X). This allows the porous free-standing sheet to be efficiently attached to the power generation layer 4. Note that the "bonding surface" mentioned above refers to the surface on which the power generation layer 4 and the porous free-standing sheet face each other. Furthermore, as mentioned above, the conductive layer 7 can be attached to the conductive layer 7 by using a material formed from a paste of carbon or metal, or an adhesive containing conductive fine particles.

[0120] The solvent X is not particularly limited, and examples thereof include poor solvents such as chlorobenzene, toluene, anisole, etc. If these poor solvents are used, for example, when the power generation layer 4 is a perovskite layer made of a perovskite compound, the porous free-standing sheet can be successfully attached to the power generation layer 4.

[0121] Furthermore, by using a porous self-supporting sheet impregnated with the solvent X, the solvent X can be well retained on at least one of the bonding surfaces of the power-generating layer 4 and the porous self-supporting sheet.

[0122] Here, a porous free-standing sheet impregnated with solvent X can be obtained, for example, by immersing a porous free-standing sheet in solvent X and then removing it. In this case, the immersion time is not particularly limited and may be set appropriately depending on the type of solvent used, etc.

[0123] When the power generation layer 4 is a perovskite layer, the solvent X retained on at least one of the bonding surfaces of the power generation layer 4 and the porous free-standing sheet may dissolve at least one precursor of a perovskite compound. For example, a porous free-standing sheet impregnated with a solution obtained by dissolving at least one precursor of a perovskite compound in the solvent X can be used. By forming an interface where at least one precursor of a perovskite compound is present, charge can be efficiently transferred between the power generation layer 4 and the second charge transport layer 5 in the resulting photoelectric conversion element 10, resulting in improved photoelectric conversion efficiency.

[0124] The second charge transport layer 5 is preferably attached by hot pressing. This allows for efficient production of a photoelectric conversion module 100 with improved integrity of the photoelectric conversion element 10. The heating temperature is not particularly limited, but can be appropriately selected from room temperature to 200°C based on the boiling point of the solvent X and a temperature that has minimal effect on the perovskite layer. The pressing time is also not particularly limited, but is typically 1 second to 10 minutes. The pressure applied during hot pressing is not particularly limited as long as it does not affect the substrate or the formed film, and can be, for example, 0.01 to 0.5 MPa. To promote removal of the solvent component from the porous freestanding sheet, hot pressing is preferably performed in a manner that ensures a solvent evaporation path. Specifically, to ensure a solvent evaporation path, hot pressing is preferably performed via a porous member such as a thick wipe, porous rubber, porous metal, or porous ceramic.

[0125] According to the above-described manufacturing method, it is possible to easily manufacture a photoelectric conversion module 100 that exhibits excellent photoelectric conversion efficiency. Note that the manufacturing method of the photoelectric conversion element of the present invention is not limited to the above-described method, and may include steps other than those described above, as long as the effects of the present invention are not impaired. [Example]

[0126] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples.

[0127] Ten photoelectric conversion modules were produced for each example and comparative example, and cell performance, number of short circuits, and reliability were evaluated. The photoelectric conversion modules produced in each example and comparative example were photoelectric conversion modules having a light-transmitting substrate and one (Examples 1 and 2, Comparative Examples 1 and 2) or two (Example 3) photoelectric conversion elements formed on the light-transmitting substrate, but the number of photoelectric conversion elements electrically connected in series (hereinafter referred to as the number in series) can be selected appropriately depending on the application.

[0128] <Battery performance> A solar simulator (WXS-90S-L2, AM1.5GMM, manufactured by Wacom Electronics Co., Ltd.) was used as the light source. The light source was 1 sun [AM1.5G, 100 mW / cm 2 (JIS C The photoelectric conversion module was connected to a source meter (6244 type DC voltage / current source, manufactured by ADC) and the following current-voltage characteristics were measured.

[0129] Under 1 sun of light irradiation, the bias voltage was selected within a measurement range depending on the number of series connections, and the output current was measured while changing the voltage. The output current was measured by integrating the value from 0.5 seconds to 0.6 seconds after changing the voltage at each voltage step.

[0130] From the measurement results of the current-voltage characteristics above, the short-circuit current density (mA / cm 2 ), open circuit voltage (V), form factor, and photoelectric conversion efficiency (%) were calculated. Each characteristic in Table 1 shows the average value of the photoelectric conversion modules excluding short-circuited ones.

[0131] <Number of short circuits> The number of short circuits is the number of photoelectric conversion modules that had short circuits between photoelectric conversion elements among the ten photoelectric conversion modules produced. In the evaluation of the cell performance, modules with significantly low voltage (less than half the open-circuit voltage of the other photoelectric conversion modules) were considered to have short circuits.

[0132] <Reliability> The manufactured photovoltaic conversion module was stored in a thermo-hygrostat at 45°C and 90% RH for 300 hours, and the performance retention rate after storage relative to before storage was evaluated.

[0133] Example 1 <Preparation of a light-transmitting substrate having a transparent conductive film formed thereon> A conductive glass substrate (Sigma-Aldrich, thickness: 2.2 mm) was used, on the surface of which a fluorine-doped tin (FTO) film (thickness: 600 nm) was formed as a transparent conductive film. Then, a part of the FTO film was removed by etching, thereby obtaining a light-transmitting substrate (hereinafter referred to as a "transparent conductive substrate") in which the transparent conductive film (FTO film) was divided into two.

[0134] <Formation of First Charge Transport Layer> A solution of titanium diisopropoxide bis(acetylacetonate) in isopropanol (Sigma-Aldrich) was applied to the surface of the transparent conductive film (FTO film) on the transparent conductive substrate. was sprayed onto the substrate by spray pyrolysis. At this time, a rectangular glass plate was placed in place to form a base layer at a predetermined location. This resulted in the formation of a base layer made of titanium dioxide (a dense TiO2 layer, 30 nm thick). Next, titanium oxide paste (manufactured by Sigma-Aldrich) was applied. A solution diluted with ethanol was prepared, and the resulting solution was applied to the surface of the underlayer by spin coating. It was then dried on a hot plate at 120°C for 10 minutes. Any coating film that protruded beyond the underlayer in a planar view was wiped off, and the resulting solution was heat-treated at 450°C for 30 minutes to form a porous semiconductor layer made of titanium dioxide (TiO2) (TiO2 porous layer, thickness 120 nm, average particle diameter of TiO2 microparticles: 20 nm), thereby obtaining a first charge transport layer.

[0135] <Formation of power generation layer> A solution (1) containing a perovskite compound precursor was prepared by spin-coating a 1.0 M lead iodide (PbI2) solution and a 1.0 M methylammonium iodide (CH3NH3I) solution in N,N-dimethylformamide (DMF). The resulting solution (1) was applied to the surface of the first charge transport layer by spin coating while adding chlorobenzene dropwise. The resulting layer was then baked at 100°C for 10 minutes to form a perovskite layer (450 nm thick) as the power generation layer. The excess perovskite layer was then removed to obtain a power generation layer-formed substrate.

[0136] <Preparation of porous films containing carbon materials (CNT films)> A porous film containing single-walled CNTs as a carbon material (CNT film) was produced according to the following procedure.

[0137] A 2% by mass aqueous solution of sodium deoxycholate (DOC) was added to 500 mL of a solvent containing a dispersant. Single-walled CNTs (SGCNTs) (manufactured by Zeon Corporation, product name "ZEONANO SG101", average diameter (Av): 3.5 nm) were used as fibrous carbon nanostructures containing single-walled CNTs. 1.0 g of DOC (G / D ratio: 2.1, t-plot is upwardly convex with no opening) was added to obtain a crude dispersion containing DOC as a dispersant. This crude dispersion was filled into a high-pressure homogenizer (manufactured by Beryu Co., Ltd., product name "BERYU SYSTEM PRO") equipped with a multistage pressure control device (multistage pressure reducer) that applies back pressure during dispersion, and the crude dispersion was dispersed at a pressure of 100 MPa. Specifically, shear force was applied to the crude dispersion while applying back pressure to disperse fibrous carbon nanostructures containing single-walled CNTs, resulting in a dispersion of fibrous carbon nanostructures containing single-walled CNTs. The dispersion was carried out for 10 minutes while the dispersion flowing out of the high-pressure homogenizer was returned to the high-pressure homogenizer.

[0138] 50 g of the prepared fibrous carbon nanostructure dispersion containing single-walled CNTs was added to a 200 mL beaker, and 50 g of distilled water was added to dilute it two-fold. This was then filtered under 0.09 MPa using a vacuum filtration system equipped with a membrane filter. After filtration, the CNT film formed on the membrane filter was washed by passing isopropyl alcohol and water through the vacuum filtration system, and then air was passed through for 15 minutes. Next, the prepared CNT film / membrane filter was immersed in ethanol, and the CNT film was peeled off from the membrane filter to obtain CNT film (A) as a porous film containing carbon material.

[0139] The obtained CNT film (A) was the same size as the membrane filter, had excellent film-forming properties, and maintained its film state even after being peeled off from the filter, showing excellent self-supporting properties. The film density of the obtained CNT film (A) was measured using the volume and weight calculated from the film thickness using a contact-type step gauge, and the density was found to be 0.85 g / cm. 3 Furthermore, when measured according to the above-mentioned method, the CNT film (A) as a porous film containing a carbon material had a film thickness of 20 μm when not pressurized in the thickness direction.

[0140] <Formation of conductive layer> A conductive paste (Dotite manufactured by Fujikura Kasei Co., Ltd.) was applied to a predetermined portion on the surface of the transparent conductive film that would constitute the external extraction electrode, thereby forming a conductive layer.

[0141] <Formation of second charge transport layer> CNT film (A) cut to a predetermined size was immersed in toluene for 10 seconds, and then pulled out of the toluene to obtain CNT film (1) impregnated with chlorobenzene. The CNT film (1) was then laminated onto the power generation layer on the power generation layer-forming substrate, which had been heated on a hot plate at 100°C. The resulting laminate was pressed (heat-pressed) from the CNT film (1) side in the thickness direction at a pressure of 0.05 Pa to form a second charge transport layer. The thickness of the conductive layer at this time was 6 μm.

[0142] <Forming of exterior materials> A photovoltaic module was then formed by bonding a glass plate, which served as an exterior material to seal the photovoltaic element from the outside, to the transparent substrate. An adhesive (TB3035B manufactured by ThreeBond Co., Ltd.) was applied so that the portion of the transparent conductive film that constituted the external extraction electrodes protruded from the outside, and the exterior materials were then superimposed and cured with UV light to seal. Current was then collected from the photovoltaic element via the two external extraction electrodes composed of the separated transparent conductive films, and the cell performance and performance retention were measured. The results are shown in Table 1.

[0143] Example 2 A photoelectric conversion module was manufactured in the same manner as in Example 1, except that for the conductive layer of the photoelectric conversion module of Example 1, "Micropearl AU" manufactured by Sekisui Chemical Co., Ltd. (conductive fine particles with gold-plated surfaces, typical shape: spherical, volume average particle diameter: 10 μm) was added as conductive fine particles to "TB3035B" (manufactured by ThreeBond Co., Ltd.) as an acrylic resin serving as an adhesive material so as to be 13.5 mass %, and the mixture was uniformly mixed using a planetary mixer. The photoelectric conversion module obtained was used to perform measurements in the same manner as in Example 1. The results are shown in Table 1.

[0144] Example 3 <Preparation of a light-transmitting substrate having a transparent conductive film formed thereon> A conductive glass substrate (Sigma-Aldrich, thickness: 2.2 mm) was used, on the surface of which a fluorine-doped tin (FTO) film (thickness: 600 nm) was formed as a transparent conductive film. Then, a part of the FTO film was removed by etching, thereby obtaining a light-transmitting substrate (hereinafter referred to as a "transparent conductive substrate") in which the transparent conductive film (FTO film) was divided into three parts.

[0145] <Formation of First Charge Transport Layer> A solution of titanium diisopropoxide bis(acetylacetonate) in isopropanol (Sigma-Aldrich) was applied to the surface of the transparent conductive film (FTO film) on the transparent conductive substrate. The titanium dioxide paste (manufactured by Sigma-Aldrich) was then diluted with ethanol to prepare a solution, and the resulting solution was then sprayed onto the transparent conductive film by spray pyrolysis. At this time, a rectangular glass plate was placed to form an underlayer at a predetermined location on the surface of the two adjacent transparent conductive films. This resulted in the formation of an underlayer made of titanium dioxide (a dense TiO2 layer, 30 nm thick). Next, a solution was prepared by diluting titanium dioxide paste (manufactured by Sigma-Aldrich) with ethanol. The resulting solution was applied to the surface of each underlayer by spin coating, dried on a hot plate at 120°C for 10 minutes, and any coating film that protruded beyond the underlayer in a planar view was wiped off. After that, the solution was heat-treated at 450°C for 30 minutes to form a porous semiconductor layer made of titanium dioxide (TiO2) (TiO2 porous layer, thickness 120 nm, average particle diameter of TiO2 microparticles: 20 nm), and a first charge transport layer was obtained.

[0146] <Formation of power generation layer> A solution (1) containing a perovskite compound precursor was prepared by spin-coating a 1.0 M lead iodide (PbI2) and a 1.0 M methylammonium iodide (CH3NH3I). The resulting solution (1) was applied to the surface of each first charge transport layer using a spin coating method while adding chlorobenzene dropwise. The resulting layer was then baked at 100°C for 10 minutes to form a perovskite layer (450 nm thick) as the power generation layer. The excess perovskite layer was then removed to obtain a power generation layer-formed substrate.

[0147] Thereafter, the preparation of the porous film, the formation of the second charge transport layer on each power generation layer, and the formation of the exterior material were carried out in the same manner as in Example 1 to prepare a photoelectric conversion module. Using the obtained photoelectric conversion module, measurements were carried out in the same manner as in Example 1. The results are shown in Table 1.

[0148] (Comparative Example 1) A photoelectric conversion module was fabricated in the same manner as in Example 1, except that in Example 1, a second charge transport layer was formed without forming a conductive layer, and then a conductive paste was applied from above the second charge transport layer to connect it to the adjacent transparent conductive film, thereby connecting them in series. Measurements were carried out using the obtained photoelectric conversion module in the same manner as in Example 1. The results are shown in Table 1.

[0149] (Comparative Example 2) A photoelectric conversion module was produced in the same manner as in Example 1, except that the CNT film serving as the second charge transport layer was formed by extending it to the outside of the sealing portion (adhesive for adhering an exterior material). Measurements were carried out in the same manner as in Example 1 using the obtained photoelectric conversion module. The results are shown in Table 1.

[0150] [Table 1]

[0151] The results shown in Table 1 show that according to Examples 1 to 3, it is possible to manufacture a photoelectric conversion module that is less likely to cause short circuits and has excellent photoelectric conversion efficiency, and that excellent sealing from the outside can be achieved, thereby obtaining excellent reliability. [Industrial Applicability]

[0152] According to the present invention, it is possible to provide a photoelectric conversion module that exhibits excellent photoelectric conversion efficiency and is easy to manufacture, and a method for manufacturing the same. [Explanation of symbols]

[0153] 1 Translucent substrate 2. Transparent conductive film 2a First transparent conductive film 2b Second transparent conductive film 3 First charge transport layer 4 Power generation layer 5 Second charge transport layer 5a Opposing part 6 Extraction electrode 7 Conductive layer 7a Conductive material 7b Insulating adhesive material 10 Photoelectric conversion element 100 Photoelectric conversion module

Claims

1. A photoelectric conversion module having a light-transmitting substrate and one or more photoelectric conversion elements formed on the light-transmitting substrate, each of the photoelectric conversion elements is formed by laminating, in this order from the light-transmitting substrate side, a transparent conductive film, a first charge transport layer, a power generation layer, and a second charge transport layer made of a porous film containing a carbon material; a photoelectric conversion module in which a portion of the second charge transport layer of at least one of the photoelectric conversion elements that faces another transparent conductive film adjacent to the transparent conductive film of the photoelectric conversion element is electrically connected to the other transparent conductive film via a conductive layer that is thicker than the combined thickness of the first charge transport layer and the power generation layer.

2. The photovoltaic conversion module according to claim 1 , wherein the other transparent conductive film constitutes an external extraction electrode.

3. The photoelectric conversion module according to claim 1 , wherein the other transparent conductive film constitutes a part of the photoelectric conversion element.

4. 4. The photovoltaic conversion module according to claim 1, wherein the carbon material includes carbon nanotubes.

5. The photovoltaic conversion module according to claim 4 , wherein the carbon nanotubes include single-walled carbon nanotubes.

6. 6. The photovoltaic conversion module according to claim 1, wherein the conductive layer contains at least one of a carbon material, a metal, and a metal oxide.

7. A photoelectric conversion module described in any one of claims 1 to 6, wherein the conductive layer overlaps the second charge transport layer when viewed from a direction perpendicular to the translucent substrate.

8. 8. The photovoltaic conversion module according to claim 1, wherein the conductive layer is formed from a conductive material and an insulating adhesive material.

9. The photovoltaic conversion module according to any one of claims 1 to 8, wherein the power generation layer contains a perovskite compound.

10. A method for manufacturing a photoelectric conversion module having a light-transmitting substrate and one or more photoelectric conversion elements formed on the light-transmitting substrate, the method comprising: each of the photoelectric conversion elements is formed by laminating, in this order from the light-transmitting substrate side, a transparent conductive film, a first charge transport layer, a power generation layer, and a second charge transport layer made of a porous film containing a carbon material; A method for manufacturing a photoelectric conversion module, comprising a step of electrically connecting a portion of the second charge transport layer of at least one of the photoelectric conversion elements that faces another transparent conductive film adjacent to the transparent conductive film of the photoelectric conversion element to the other transparent conductive film via a conductive layer that is thicker than the combined thickness of the first charge transport layer and the power generation layer.

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