Photoelectric conversion element module

Abstract

To provide a photoelectric conversion device module by which a superior photoelectric conversion efficiency can be achieved easily.SOLUTION: A photoelectric conversion device module comprises: a plurality of photoelectric conversion devices 3 each having a conductive film 5, a first charge transport layer 6, a power generation layer 7 and a second charge transport layer 9 with a porous film containing at least carbon nanofiber in this order; and a connection part of conductive fine particles for connecting the photoelectric conversion devices in series. The conductive film, the first charge transport layer, the power generation layer and the porous film are provided separately from each other. The photoelectric conversion device module has, in two photoelectric conversion devices connected to each other, a conductive film extension part where the conductive film in one photoelectric conversion device extends toward the other photoelectric conversion device further than the first charge transport layer, power generation layer and porous film, and a porous film extension part where the porous film in the other photoelectric conversion device extends toward the one photoelectric conversion device further than the conductive film, first charge transport layer and power generation layer, in which the conductive film extension part and the porous film extension part are connected through the connection part.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a photoelectric conversion element module. [Background technology]

[0002] Known photoelectric conversion elements have a conductive film, a first charge transport layer, a power generation layer, and a second charge transport layer in this order (see, for example, Patent Document 1), and photoelectric conversion element modules have multiple photoelectric conversion elements (see, for example, Patent Documents 2 and 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6339037 [Patent Document 2] Patent No. 6030176 [Patent Document 3] Patent No. 6646471 Summary of the Invention [Problem to be solved by the invention]

[0004] However, conventional photoelectric conversion element modules have room for improvement in terms of photoelectric conversion efficiency.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a photoelectric conversion element module that can easily achieve excellent photoelectric conversion efficiency. [Means for solving the problem]

[0006] The photoelectric conversion element module of the present invention comprises a plurality of photoelectric conversion elements, each having a conductive film, a first charge transport layer, a power generation layer, and a second charge transport layer having a porous film made of at least a carbon nanofiber material, in this order, and one or more connectors containing conductive fine particles that connect two or more photoelectric conversion elements in series, and the conductive film, the first charge transport layer, the power generation layer, and the porous film are each separated from each other between each two of the interconnected photoelectric conversion elements in the two or more photoelectric conversion elements. a photoelectric conversion element module in which, in the two interconnected photoelectric conversion elements, the conductive film of one of the photoelectric conversion elements has a conductive film extension that extends further toward the other photoelectric conversion element than the first charge transport layer, the power generation layer, and the porous film, and the porous film of the other photoelectric conversion element has a porous film extension that extends further toward the one photoelectric conversion element than the conductive film, the first charge transport layer, and the power generation layer, and the conductive film extension and the porous film extension are connected via the connection part. With this configuration, the width of the connection part can be easily set narrow, corresponding to the spacing between the power generation layers of two or more photoelectric conversion elements, and therefore excellent photoelectric conversion efficiency can be easily achieved.

[0007] In the photoelectric conversion element module of the present invention, the porous film in the plurality of photoelectric conversion elements is preferably a porous free-standing sheet. With this configuration, the shape stability of the connection part is improved, making it easier to realize a narrow connection part.

[0008] In the present invention, the term "porous free-standing sheet" refers to a sheet having a plurality of pores formed therein, which maintains its shape even without a support. The porous free-standing sheet used in the present invention maintains its shape without tearing even when immersed in a predetermined solvent or solution, removed, and then attached to an object. Furthermore, the porous free-standing sheet used in the present invention 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 sheet is handled using a jig for attaching the sheet. Furthermore, the porous free-standing sheet used in the present invention preferably maintains its shape without a support, for example, when it has a thickness of 1 μm to 200 μm and is the size required for forming a photoelectric conversion element.

[0009] In the photoelectric conversion element module of the present invention, it is preferable that the porous free-standing sheet in the plurality of photoelectric conversion elements has a film thickness of 20 μm or more. With this configuration, the shape stability of the connection part is improved, making it easier to realize a narrow connection part.

[0010] Furthermore, in the photoelectric conversion element module of the present invention, in each of the two interconnected photoelectric conversion elements, the distance between the conductive film extension of one photoelectric conversion element and the conductive film, the first charge transport layer, and the power generation layer of the other photoelectric conversion element is preferably larger than the average particle size of the conductive fine particles. With this configuration, it is possible to suppress the occurrence of a short circuit via the conductive fine particles between the conductive film extension of one photoelectric conversion element and the conductive film, the first charge transport layer, and the power generation layer of the other photoelectric conversion element, making it easier to achieve excellent photoelectric conversion efficiency.

[0011] Here, the "average particle size" of the conductive fine particles refers to the catalog value of commercially available conductive fine particles or the value determined from an image observed with a digital microscope.

[0012] Furthermore, in the photoelectric conversion element module of the present invention, it is preferable that, in each of the two interconnected photoelectric conversion elements, the power generation layer of the other photoelectric conversion element covers the end of the conductive film on the side of the one photoelectric conversion element. With this configuration, it is possible to suppress the occurrence of a short circuit via conductive fine particles between the porous film and the conductive film in the other photoelectric conversion element, making it easier to achieve excellent photoelectric conversion efficiency.

[0013] In the photoelectric conversion element module of the present invention, it is preferable that the conductive fine particles in each of the connection portions contain at least one of a carbon material, a metal, and a metal oxide. With this configuration, it is possible to more easily realize a narrow connection portion.

[0014] In the photoelectric conversion element module of the present invention, each of the connecting portions is preferably made of at least the conductive fine particles and a resin. With this configuration, connecting portions with a narrow width can be more easily realized.

[0015] In the photoelectric conversion element module of the present invention, it is preferable that the power generation layer of each of the plurality of photoelectric conversion elements contains a perovskite compound. With this configuration, excellent photoelectric conversion efficiency can be more easily achieved.

[0016] Furthermore, the photoelectric conversion element module of the present invention is preferably manufactured by a method including: a first step of forming a structure including the conductive film, the first charge transport layer, and the power generation layer of the plurality of photoelectric conversion elements and a member for forming the one or more connectors; and a second step of laminating a porous film made of at least carbon nanofibers on the structure and then removing a portion of the porous film to form the porous film in the plurality of photoelectric conversion elements. With this configuration, connectors can be formed accurately and efficiently, making it easier to achieve narrow connectors.

[0017] In addition, in the method for manufacturing a photoelectric conversion element module of the present invention, the first step preferably includes a removal step of forming at least a conductive film body and then removing at least a part of the conductive film body to form at least the conductive films of the plurality of photoelectric conversion elements. With this configuration, narrow connection portions can be more easily realized.

[0018] In the method for manufacturing a photoelectric conversion element module of the present invention, the removing step preferably includes forming the conductive film, the first charge transport layer, and the power generation layer, and then removing portions of the conductive film, the first charge transport layer, and the power generation layer to form the conductive film, the first charge transport layer, and the power generation layer of the plurality of photoelectric conversion elements. With this configuration, in each of two interconnected photoelectric conversion elements, the end portions of the power generation layer, the first charge transport layer, and the conductive film of the other photoelectric conversion element on the side of one photoelectric conversion element can be easily aligned. This prevents short circuits between the porous film and the conductive film of the other photoelectric conversion element via conductive particles, and also makes it easier to achieve narrow connections. Since a conductive film extension must be formed, the first charge transport layer and the power generation layer are preferably patterned. However, the first charge transport layer and the power generation layer may be partially removed either before or after the removing step to form the conductive film extension. [Effects of the Invention]

[0019] According to the present invention, it is possible to provide a photoelectric conversion element module that can easily achieve excellent photoelectric conversion efficiency. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a cross-sectional view of a photoelectric conversion module having a photoelectric conversion element module according to one embodiment of the present invention. [Figure 2] FIG. 2 is an enlarged view of part A in FIG. [Figure 3] 10 is a cross-sectional view showing a structure in which a short circuit occurs between a porous film and a conductive film via conductive fine particles in a second photoelectric conversion element. FIG. [Figure 4]1. FIG. 4 is a cross-sectional view showing a modified example of the photoelectric conversion module shown in FIG. [Figure 5A] 2 is a cross-sectional view showing a state during a first step for manufacturing the photovoltaic conversion module shown in FIG. 1. FIG. [Figure 5B] FIG. 2 is a cross-sectional view showing the state at the end of the first step. [Figure 5C] FIG. 10 is a cross-sectional view showing a state during a second step. DETAILED DESCRIPTION OF THE INVENTION

[0021] The photoelectric conversion element module of the present invention is not particularly limited, and can be configured as, for example, a photoelectric conversion module as a perovskite solar cell module. Hereinafter, one embodiment of the photoelectric conversion element module of the present invention will be described in detail with reference to the drawings.

[0022] (Photoelectric conversion module 2) 1 and 2 show the configuration of a photoelectric conversion module 2 having a photoelectric conversion element module 1 according to one embodiment of the present invention. The photoelectric conversion element module 1 has a plurality of photoelectric conversion elements 3 and one or more connection parts 4. Each of the plurality of photoelectric conversion elements 3 has, in this order, a conductive film 5, a first charge transport layer 6, a power generation layer 7, and a second charge transport layer 9 having a porous film 8 made of at least carbon nanofibers. The one or more connection parts 4 contain conductive particles 10 and connect two or more photoelectric conversion elements 3 included in the plurality of photoelectric conversion elements 3 in series. As shown in FIG. 1, the photoelectric conversion module 2 preferably has a photoelectric conversion element module 1, a light-transmitting substrate 11, one or more extraction electrodes 12, and one or more extraction connection parts 13.

[0023] In two or more photoelectric conversion elements 3 connected in series by one or more connection parts 4, the conductive film 5, the first charge transport layer 6, the power generation layer 7 and the porous film 8 are each provided separately from each other between each two interconnected photoelectric conversion elements 3.

[0024] Furthermore, in each of the two interconnected photoelectric conversion elements 3 described above, (i) the conductive film 5 in one of the photoelectric conversion elements 3 (hereinafter also referred to as the first photoelectric conversion element 3a) has a conductive film extension 14 that extends further toward the other photoelectric conversion element 3 (hereinafter also referred to as the second photoelectric conversion element 3b) than the first charge transport layer 6, the power generation layer 7, and the porous film 8, (ii) the porous film 8 in the second photoelectric conversion element 3b has a porous film extension 15 that extends further toward the first photoelectric conversion element 3a than the conductive film 5, the first charge transport layer 6, and the power generation layer 7, and (iii) the conductive film extension 14 and the porous film extension 15 are connected via the connection part 4.

[0025] With this configuration, the width of the connection portion 4 (the width in the left-right direction in FIG. 1), which corresponds to the spacing between the power generation layers 7 of two or more photoelectric conversion elements 3, can be easily set narrow, making it easy to achieve excellent photoelectric conversion efficiency.

[0026] It is preferable that the porous film 8 is a porous free-standing sheet in the plurality of photoelectric conversion elements 3. With such a configuration, the shape stability of the connection part 4 is improved, and thus it is possible to more easily realize a connection part 4 with a narrow width.

[0027] The porous free-standing sheet preferably has a thickness of 20 μm or more in the plurality of photoelectric conversion elements 3. With this configuration, the shape stability of the connection parts 4 is improved, making it easier to achieve connection parts 4 with a narrow width.

[0028] 2, the distance W between the conductive film extension 14 of the first photoelectric conversion element 3a and the conductive film 5, first charge transport layer 6, and power generation layer 7 of the second photoelectric conversion element 3b is preferably larger than the average particle size D of the conductive particles 10. With this configuration, it is possible to suppress the occurrence of short circuits via the conductive particles 10 between the conductive film extension 14 of the first photoelectric conversion element 3a and the conductive film 5, first charge transport layer 6, and power generation layer 7 of the second photoelectric conversion element 3b, and therefore it is possible to more easily achieve excellent photoelectric conversion efficiency.

[0029] As shown in Figure 3, if the end of the conductive film 5 in the second photoelectric conversion element 3b on the side of the first photoelectric conversion element 3a protrudes further toward the first photoelectric conversion element 3a than the power generation layer 7, a short circuit may occur between the porous film 8 and the conductive film 5 in the second photoelectric conversion element 3b via the conductive microparticles 10, which may reduce the photoelectric conversion efficiency.

[0030] Therefore, in order to suppress the occurrence of such a short circuit, it is preferable to configure the second photoelectric conversion element 3b so that the power generation layer 7 covers the end of the conductive film 5 on the side of the first photoelectric conversion element 3a, as shown in Fig. 2. Alternatively, a similar short circuit suppression effect can be obtained by configuring the second photoelectric conversion element 3b so that the end of the power generation layer 7, first charge transport layer 6, and conductive film 5 on the side of the first photoelectric conversion element 3a are aligned, as shown in Fig. 4.

[0031] In each of the connection portions 4, the conductive particles 10 preferably contain at least one of a carbon material, a metal, and a metal oxide. With this configuration, it is possible to more easily realize a connection portion 4 with a narrow width.

[0032] Each connection part 4 is preferably made of at least conductive fine particles 10 and a resin as adhesive 16. Such a configuration makes it easier to realize a narrow connection part 4. The resin that constitutes each connection part 4 can be, for example, a photocurable resin or a thermosetting resin.

[0033] In the plurality of photoelectric conversion elements 3, the power generation layer 7 preferably contains a perovskite compound. With such a configuration, excellent photoelectric conversion efficiency can be more easily achieved.

[0034] The extraction electrode 12 is not particularly limited, but can have the same configuration as the conductive film 5 of the plurality of photoelectric conversion elements 3. The extraction connection part 13 is not particularly limited, but can have the same configuration as the connection part 4.

[0035] The method for manufacturing the photoelectric conversion element module 1 is not particularly limited, but preferably includes the following first and second steps. The first step, as shown in FIGS. 5A and 5B, is to form a structure 18 including the conductive film 5, first charge transport layer 6, and power generation layer 7 of a plurality of photoelectric conversion elements 3, and a member for forming one or more connectors 4 (hereinafter also referred to as a connector 17). The second step, as shown in FIG. 5C, is to laminate a porous film 19 made of at least carbon nanofibers on the structure 18, and then remove a portion of the porous film 19 to form the porous film 8 of the plurality of photoelectric conversion elements 3, as shown in FIG. 1. This manufacturing method allows the connectors 4 to be formed with high precision, making it easier to achieve connectors 4 with narrow widths.

[0036] In the first step, the structure 18 can be formed on the light-transmitting substrate 11. Before or after the formation of the structure 18, or simultaneously with the formation of the structure 18, the extraction electrode 12 and a member for forming the extraction connection part 13 (hereinafter also referred to as the extraction connection material 20) can be formed on the light-transmitting substrate 11.

[0037] The first step preferably includes a removal step of forming at least a conductive film body and then removing at least a part of the conductive film body to form at least the conductive film 5 of the plurality of photoelectric conversion elements 3. With this configuration, it is possible to more easily realize narrow connection portions 4.

[0038] The method for removing the material in the removing step and the second step is not particularly limited, and for example, scribing with a laser or a blade, etching, or the like can be used.

[0039] In the removal step, it is preferable to form the conductive film, the first charge transport layer, and the power generation layer, and then remove portions of the conductive film, the first charge transport layer, and the power generation layer to form the conductive film 5, the first charge transport layer 6, and the power generation layer 7 of the plurality of photoelectric conversion elements 3. With this configuration, as shown in Fig. 4, the end portions of the power generation layer 7, the first charge transport layer 6, and the conductive film 5 of the second photoelectric conversion element 3b on the side of the first photoelectric conversion element 3a can be easily aligned, thereby suppressing the occurrence of a short circuit via the conductive fine particles 10 between the porous film 8 and the conductive film 5 in the second photoelectric conversion element 3b and moreover making it easier to realize a narrow connection portion 4.

[0040] In the removal step, the conductive film body is formed and then a portion of the conductive film body is removed to form the conductive film 5 of the plurality of photoelectric conversion elements 3, and after the removal step, the first charge transport layer 6 and the power generation layer 7 of the plurality of photoelectric conversion elements 3 may be formed. In this case, it is preferable to form the power generation layer 7 of the second photoelectric conversion element 3b so that the power generation layer 7 of the second photoelectric conversion element 3b covers the end of the conductive film 5 on the side of the first photoelectric conversion element 3a.

[0041] The conductive film 5, the first charge transport layer 6, the power generation layer 7, and the second charge transport layer 9 may each be composed of multiple layers made of the same or different materials. Each of the multiple photoelectric conversion elements 3 may have additional layers other than the conductive film 5, the first charge transport layer 6, the power generation layer 7, and the second charge transport layer 9, as long as the effects of the present invention are not impaired. The photoelectric conversion element module 1 may also have additional members other than the above-mentioned members, as long as the effects of the present invention are not impaired. The first step and the second step may include steps other than those described above.

[0042] Next, each of the components that make up the photoelectric conversion element 3 will be described in more detail.

[0043] <Transparent substrate 11> The light-transmitting substrate 11 constitutes the base of the photoelectric conversion module 2. The light-transmitting substrate 11 is not particularly limited, and examples thereof include a substrate made of glass or synthetic resin, and a film made of synthetic resin.

[0044] Examples of the glass that constitutes the light-transmitting substrate 11 include inorganic glass such as soda glass.

[0045] Examples of synthetic resins that can be used to form the light-transmitting substrate 11 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 3, polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) are preferred synthetic resins.

[0046] The thickness of the light-transmitting substrate 11 is not particularly limited as long as it can maintain its shape as a substrate. The thickness of the light-transmitting substrate 11 can be, for example, 0.1 mm or more and 10 mm or less.

[0047] <Conductive film 5> The conductive film 5 is a conductive film that is provided on the surface of the light-transmitting substrate 11 and has light-transmitting properties. The conductive film 5 can be made of, for example, a metal oxide.

[0048] Examples of metal oxides that can be used to form the conductive film 5 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).

[0049] The thickness of the conductive film 5 is not particularly limited as long as it is a thickness that can impart the desired conductivity to the light-transmitting substrate 11, and can be, for example, 1 nm or more and 1 μm or less.

[0050] <First charge transport layer 6> The first charge transport layer 6 is a layer that functions as a charge transport layer and is preferably made of an n-type semiconductor. The first charge transport layer 6 is preferably made of two layers, an underlayer and a porous semiconductor layer, but the first charge transport layer 6 may also be a single layer made of an n-type semiconductor.

[0051] <<Underlayer>> The underlayer is a layer that is optionally provided between the conductive film 5 and the porous semiconductor layer. By providing the underlayer, the conductive film 5 is 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 3.

[0052] The underlayer may be, for example, a porous film 8 or a non-porous dense film as long as it is made of an n-type semiconductor. However, from the viewpoint of sufficiently preventing contact between the light-transmitting substrate 11 and the conductive film 5 and the porous semiconductor layer, the underlayer is preferably a non-porous dense film. The thickness of the underlayer is not particularly limited and may be, for example, 1 nm or more and 500 nm or less. The underlayer may also 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.

[0053] <<Porous semiconductor layer>> The porous semiconductor layer is a porous layer. When the first charge transport layer 6 includes a porous semiconductor layer, the photoelectric conversion efficiency of the photoelectric conversion element 3 can be improved.

[0054] 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.

[0055] <Power Generation Layer 7> The power generation layer 7 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).

[0056] The perovskite compound constituting the power generation layer 7 is not particularly limited, and known perovskite compounds can be used. Specifically, examples of perovskite compounds include CH3NH3PbI3, CH3NH3PbBr3, (CH3(CH2) n (CHCH3NH3)2PbI4[n=5-8], (C6H5C2H4NH3)2PbBr4, etc. can be used.

[0057] The thickness of the power generating layer 7 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 generating layer 7 100 nm or more, the electromotive force of the power generating layer 7 can be increased.

[0058] Alternatively, the power generation layer 7 may be formed by forming a porous insulating layer on the first charge transport layer 6 and then forming a perovskite compound therein. The thickness of the porous insulating layer is not particularly limited, but is preferably 500 nm or more and 5 μm or less. Zirconia or the like can be used as the material for the porous insulating layer.

[0059] <Second charge transport layer 9> The second charge transport layer 9 is a layer having at least a porous film 8 made of carbon nanofibers. The carbon nanofibers contained in the second charge transport layer 9 are not particularly limited, but preferably contain carbon nanotubes (hereinafter also referred to as CNTs), and the CNTs contained in the second charge transport layer 9 preferably contain single-walled CNTs. This configuration can improve the photoelectric conversion efficiency of the photoelectric conversion module 2.

[0060] The porous film 8 is preferably a porous free-standing sheet, and more preferably, the second charge transport layer 9 is a layer made of a porous free-standing sheet. With this configuration, the shape stability of the second charge transport layer 9 is improved, and it is possible to easily realize a large area for the photoelectric conversion element 3.

[0061] The porous free-standing sheet must contain at least single-walled CNTs, is preferably a sheet made of single-walled CNTs, and is 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 9 the functions of an excellent hole transport layer and a collecting electrode.

[0062] <<Porous self-standing sheet>> The single-walled CNTs contained in the porous free-standing sheet preferably have the following properties.

[0063] -(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 9 can be provided with sufficient functions as a hole transport layer and a current collecting electrode.

[0064] 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.

[0065] -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 9 can be improved. Furthermore, when the average diameter (Av) of the single-walled CNTs is 15 nm or less, the second charge transport layer 9 can fully function as a current collecting electrode.

[0066] -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 9 with excellent strength.

[0067] 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.

[0068] 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.).

[0069] 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.

[0070] 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.

[0071] Furthermore, the porous free-standing sheet preferably contains, within the porous free-standing sheet, the material (e.g., perovskite compound) that constitutes the power generating layer 7, or a portion of the material (e.g., material that constitutes the perovskite compound) that constitutes the power generating layer 7. 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 generating layer 7, or a portion of the material (e.g., material that constitutes the perovskite compound) that constitutes the power generating layer 7.

[0072] 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.

[0073] 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.

[0074] 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).

[0075] Examples of inorganic materials that can be contained in the porous free-standing sheet include CuI, CuSCN, CuO, and Cu2O.

[0076] 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, 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 9 can exhibit a more excellent function as a collecting electrode.

[0077] <<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.

[0078] -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.

[0079] 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).

[0080] 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).

[0081] =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.

[0082] Examples of surfactants include sodium dodecyl sulfonate, sodium deoxycholate, sodium cholate, and sodium dodecylbenzenesulfonate.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] =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.

[0087] 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.

[0088] ~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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] ~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.

[0095] 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.

[0096] 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.

[0097] -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.

[0098] [Film-forming base material] Here, the film-forming substrate is not particularly limited, and any known substrate can be used.

[0099] 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.

[0100] 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.

[0101] [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.

[0102] [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.

[0103] [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.

[0104] <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.

[0105] 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.

[0106] 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.

[0107] Next, the first and second steps for manufacturing the photoelectric conversion element module 1 will be described in more detail.

[0108] <1st process> <<Formation of Conductive Film 5>> The conductive film 5 of the plurality of photoelectric conversion elements 3 is formed on the light-transmitting substrate 11. The method for forming the conductive film 5 is not particularly limited, and known methods such as sputtering and vapor deposition can be used. The conductive film 5 of the plurality of photoelectric conversion elements 3 may be formed directly by forming the conductive film body only in the regions corresponding to the conductive film 5 of the plurality of photoelectric conversion elements 3 using a mask or the like. Alternatively, the conductive film body may be formed over the entire region including the regions corresponding to the conductive film 5 of the plurality of photoelectric conversion elements 3, and then a portion of the conductive film body may be removed to form the conductive film 5 of the plurality of photoelectric conversion elements 3. The conductive film 5, first charge transport layer 6, and power generation layer 7 of the plurality of photoelectric conversion elements 3 may be formed by forming a first charge transport layer and a power generation layer on the conductive film body, and then removing unnecessary portions all at once to form the conductive film 5, first charge transport layer 6, and power generation layer 7 of the plurality of photoelectric conversion elements 3.

[0109] <<Formation of First Charge Transport Layer 6>> Furthermore, a first charge transport layer 6 is formed on the conductive film 5. The first charge transport layer 6 can be obtained, for example, by forming an underlayer on the conductive film 5 and then forming a porous semiconductor layer thereon.

[0110] [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 conductive film 5.

[0111] Here, examples of methods for spraying the fine particles include spray pyrolysis, aerosol deposition, electrostatic spray, and cold spray.

[0112] [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.

[0113] Here, examples of precursors of n-type semiconductors include titanium alkoxides such as titanium tetrachloride (TiCl), peroxotitanic acid (PTA), titanium ethoxide, and titanium isopropoxide (TTIP); and metal alkoxides such as zinc alkoxide, alkoxysilane, zirconium alkoxide, and titanium diisopropoxide bis(acetylacetonate).

[0114] 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.

[0115] 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.

[0116] <<Formation of power generation layer 7>> Then, the power generation layer 7 is formed on the first charge transport layer 6. The power generation layer 7 can be formed by, but is not limited to, vacuum deposition or coating. For example, the power generation layer 7 can be formed by coating a precursor-containing solution containing a precursor of a perovskite compound on the first charge transport layer 6 and baking it. Examples of precursors of the perovskite compound include lead iodide (PbI) and methylammonium iodide (CHNHI). The solvent contained in the precursor-containing solution is also not limited to, and examples include N,N-dimethylformamide and dimethyl sulfoxide. After coating these solutions, a poor solvent can be used to promote precipitation of the perovskite compound. In this specification, a poor solvent refers to a solvent that does not substantially change the perovskite compound during the fabrication process. If no visible changes in the appearance of the perovskite compound, such as cloudiness of the film, are observed during the fabrication process, the perovskite compound can be said to be substantially unchanged.

[0117] 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.

[0118] The method for applying the precursor-containing solution onto the first charge transport layer 6 is not particularly limited, and known application methods such as spin coating, spraying, and bar coating can be used.

[0119] <<Arrangement of connecting material 17>> An uncured connecting material 17 is placed at a position corresponding to the connecting portion 4. At this time, an uncured take-out connecting material 20 can be placed at a position corresponding to the take-out connecting portion 13.

[0120] <Second process> In the second step, while laminating a previously prepared porous membrane 19 on the structure 18, the porous membrane 19 and the conductive membrane extension 14 are electrically connected via a previously formed connecting material 17, and the connecting material 17 is hardened in this state. At this time, the porous membrane 19 and the extraction electrode 12 are electrically connected via a previously formed extraction connecting material 20, and the extraction connecting material 20 can be hardened in this state. Then, unnecessary portions of the porous membrane 19 are removed to form the porous membranes 8 of the multiple photoelectric conversion elements 3. [Example]

[0121] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples.

[0122] Ten photoelectric conversion modules each of Samples 1 to 4 were fabricated, and the number of short circuits and photoelectric conversion efficiency were evaluated.

[0123] <Photoelectric conversion efficiency> The light source used was a solar simulator (WXS-90S-L2, AM1.5GMM, manufactured by Wacom Electronics Co., Ltd.). The light source was adjusted to 1 sun [AM1.5G, 100 mW / cm2 (JIS C8912 Class A)]. The fabricated 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.

[0124] 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.

[0125] From the results of measuring the current-voltage characteristics, the average value of the photoelectric conversion efficiency (%) was calculated, excluding the short-circuited ones.

[0126] <Number of short circuits> The number of short circuits is the number of photovoltaic conversion modules that had a short circuit in the second photovoltaic conversion element out of the ten photovoltaic conversion modules produced. In the evaluation of photovoltaic conversion efficiency (%), modules with significantly low voltage (less than half the open-circuit voltage of the other photovoltaic conversion modules) were considered to have a short circuit.

[0127] (Sample 1) <Preparation of a Light-Transmitting Substrate with a Conductive Film Formed> A conductive glass substrate (Sigma-Aldrich, thickness: 2.2 mm) was used, on whose surface a fluorine-doped tin (FTO) film (thickness: 600 nm) was formed as a conductive film, and part of the FTO film was removed by etching to obtain a transparent substrate (hereinafter referred to as a "transparent conductive substrate") with the conductive film (FTO film) divided into two.

[0128] <Formation of First Charge Transport Layer> A solution of titanium diisopropoxide bis(acetylacetonate) in isopropanol (Sigma-Aldrich) was sprayed onto the surface of the conductive film (FTO film) of a transparent conductive substrate by spray pyrolysis. A rectangular glass plate was then placed on the substrate to form an underlayer at the desired location. This resulted in a titanium dioxide underlayer (a dense TiO layer, 30 nm thick). Next, a solution of titanium oxide paste (Sigma-Aldrich) diluted with ethanol was prepared. The resulting solution was spin-coated onto the underlayer surface and dried on a hot plate at 120°C for 10 minutes. Any excess film beyond the underlayer was wiped off, followed by heat treatment at 450°C for 30 minutes to form a porous titanium dioxide (TiO porous layer, 120 nm thick, with an average particle size of TiO particles of 20 nm). This resulted in a first charge transport layer.

[0129] <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 solution 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 from the portion that would become the power generation layer, yielding a power generation layer-formed substrate. The power generation layer was formed so that it covered the edge of the conductive film on the first photoelectric conversion element side of the second photoelectric conversion element.

[0130] <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.

[0131] To 500 mL of a 2% by mass aqueous solution of sodium deoxycholate (DOC) as a dispersant, 1.0 g of single-walled carbon nanotubes (SGCNTs) (manufactured by Zeon Corporation, product name "ZEONANO SG101," average diameter (Av): 3.5 nm, G / D ratio: 2.1, t-plot with unopened openings is upwardly convex) was added to obtain a crude dispersion containing DOC as a dispersant. This crude dispersion was loaded 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 the fibrous carbon nanotubes containing single-walled CNTs, resulting in a dispersion of fibrous carbon nanotubes containing single-walled CNTs. The dispersion treatment was carried out for 10 minutes while the dispersion liquid flowing out of the high-pressure homogenizer was returned to the high-pressure homogenizer.

[0132] 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.

[0133] 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. 3Furthermore, 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.

[0134] <Formation of connecting material> To the adhesive material, acrylic resin "TB3035B" (manufactured by ThreeBond Co., Ltd.), conductive fine particles "Micropearl AU" (conductive fine particles with gold-plated surfaces, typical shape: spherical, volume average particle diameter: 10 μm) manufactured by Sekisui Chemical Co., Ltd. were added so as to make a concentration of 13.5 mass %, and the resulting connection material was mixed uniformly using a planetary mixer and placed in the designated area.

[0135] <Formation of second charge transport layer> CNT film (A) cut to a specified size was immersed in toluene for 10 seconds, and then pulled out of the toluene to obtain a CNT film (B) impregnated with chlorobenzene. The CNT film (B) 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 (B) side in the thickness direction at a pressure of 0.05 Pa, and a specified portion was removed to form a second charge transport layer. The width of the connection portion was 0.3 mm.

[0136] <Forming of exterior materials> A photoelectric conversion module was then formed by bonding a glass plate, which served as an exterior material to seal the photoelectric conversion element from the outside, to the transparent substrate. An adhesive (TB3035B manufactured by ThreeBond Co., Ltd.) was applied so that the portion of the conductive film that constituted the 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 photoelectric conversion element through two extraction electrodes composed of divided conductive films, and the photoelectric conversion efficiency was measured. The results are shown in Table 1.

[0137] (Sample 2) A photoelectric conversion module was manufactured in the same manner as Sample 1, except that the photoelectric conversion module structure for Sample 1 consisted of forming a conductive film, a first charge transport layer, and a power generation layer, and then removing portions of the conductive film, the first charge transport layer, and the power generation layer to form the conductive film, the first charge transport layer, and the power generation layer of a plurality of photoelectric conversion elements. The width of the connection portion in the obtained photoelectric conversion module was 0.25 mm. Measurements were performed using the obtained photoelectric conversion module in the same manner as Sample 1. The results are shown in Table 1.

[0138] (Sample 3) A photoelectric conversion module was manufactured in the same manner as Sample 1, except that the porous membranes of multiple photoelectric conversion elements were individually produced, stacked in a structure, and individually connected to a connecting material to form the porous membrane of the photoelectric conversion module of Sample 1. The width of the connection portion in the obtained photoelectric conversion module was 1.0 mm. Measurements were performed using the obtained photoelectric conversion module in the same manner as Sample 1. The results are shown in Table 1.

[0139] (Sample 4) As the structure of the photoelectric conversion module of Sample 1, a photoelectric conversion module was manufactured in the same manner as Sample 1, except that in the second photoelectric conversion element, the power generation layer was formed so that the end of the conductive film on the side of the first photoelectric conversion element protruded further toward the first photoelectric conversion element than the power generation layer. The width of the connection portion in the obtained photoelectric conversion module was 0.3 mm. Measurements were performed using the obtained photoelectric conversion module in the same manner as Sample 1. The results are shown in Table 1.

[0140] [Table 1] [Industrial Applicability]

[0141] According to the present invention, it is possible to provide a photoelectric conversion element module that can easily achieve excellent photoelectric conversion efficiency. [Explanation of symbols]

[0142] 1. Photoelectric conversion element module 2. Photoelectric conversion module 3 Photoelectric conversion element 3a First photoelectric conversion element 3b Second photoelectric conversion element 4 Connection 5 Conductive film 6 First charge transport layer 7 Power generation layer 8 Porous membrane 9 Second charge transport layer 10 Conductive particles 11 Translucent substrate 12 Extraction electrode 13 Extraction connection 14 Conductive film extension 15 Porous membrane extension 16 Adhesive 17 Connectors 18 Structure 19 Porous membrane body 20 Extraction connector W: Distance between the conductive film extension of the first photoelectric conversion element and the conductive film, first charge transport layer, and power generation layer of the second photoelectric conversion element D Average particle size of conductive particles

Claims

1. a plurality of photoelectric conversion elements, each of which has a conductive film, a first charge transport layer, a power generation layer, and a second charge transport layer having a porous film made of at least carbon nanofibers, in this order; and one or more connectors, each of which contains conductive fine particles and connects two or more photoelectric conversion elements included in the plurality of photoelectric conversion elements in series; the conductive film, the first charge transport layer, the power generation layer, and the porous film are provided separately from each other between each two interconnected photoelectric conversion elements in the two or more photoelectric conversion elements; In each of the two interconnected photoelectric conversion elements, the conductive film in one of the photoelectric conversion elements has a conductive film extension that extends toward the other of the photoelectric conversion elements beyond the first charge transport layer, the power generation layer, and the porous film; the porous film in the other photoelectric conversion element has a porous film extension portion that extends toward the one photoelectric conversion element relative to the conductive film, the first charge transport layer, and the power generation layer; the conductive membrane extension and the porous membrane extension are connected via the connection portion, A photoelectric conversion element module, wherein the distance between the conductive film extension of one of the photoelectric conversion elements and the conductive film, the first charge transport layer, and the power generation layer of the other of the photoelectric conversion elements is larger than the average particle size of the conductive fine particles.

2. The photoelectric conversion element module according to claim 1 , wherein the porous film in the plurality of photoelectric conversion elements is a porous free-standing sheet.

3. The photoelectric conversion element module according to claim 2 , wherein the porous free-standing sheet in each of the plurality of photoelectric conversion elements has a film thickness of 20 μm or more.

4. A photoelectric conversion element module according to any one of claims 1 to 3, wherein in each of the two interconnected photoelectric conversion elements, the power generation layer in the other photoelectric conversion element covers the end of the conductive film on the side of the one photoelectric conversion element.

5. 5. The photoelectric conversion element module according to claim 1, wherein the conductive fine particles in each of the connection portions contain at least one of a carbon material, a metal, and a metal oxide.

6. 6. The photoelectric conversion element module according to claim 1, wherein each of the connection portions is made of at least the conductive fine particles and a resin.

7. 7. The photoelectric conversion element module according to claim 1, wherein the power generation layer of the plurality of photoelectric conversion elements contains a perovskite compound.

8. A method for manufacturing a photoelectric conversion element module, comprising: The photoelectric conversion element module includes a plurality of photoelectric conversion elements, each of which has a conductive film, a first charge transport layer, a power generation layer, and a second charge transport layer having a porous film made of at least a carbon nanofiber material, in this order, and one or more connection parts containing conductive fine particles that connect two or more photoelectric conversion elements included in the plurality of photoelectric conversion elements in series, the conductive film, the first charge transport layer, the power generation layer, and the porous film are provided separately from each other between each two interconnected photoelectric conversion elements in the two or more photoelectric conversion elements; In each of the two interconnected photoelectric conversion elements, the conductive film in one of the photoelectric conversion elements has a conductive film extension that extends toward the other of the photoelectric conversion elements beyond the first charge transport layer, the power generation layer, and the porous film; the porous film in the other photoelectric conversion element has a porous film extension portion that extends toward the one photoelectric conversion element relative to the conductive film, the first charge transport layer, and the power generation layer; the conductive membrane extension and the porous membrane extension are connected via the connection portion, a first step of forming a structure including the conductive film, the first charge transport layer, and the power generation layer of the plurality of photoelectric conversion elements, and a member for forming the one or more connection portions; and a second step of laminating a porous film body made of at least carbon nanofibers on the structure, and then removing a portion of the porous film body to form the porous film in the plurality of photoelectric conversion elements.

9. The method according to claim 8, wherein the first step includes a removal step of forming at least the conductive film of the plurality of photoelectric conversion elements by removing at least a portion of the conductive film after forming at least the conductive film.

10. 10. The method according to claim 9, wherein in the removing step, after forming the conductive film body, the first charge transport layer body, and the power generation layer body, parts of the conductive film body, the first charge transport layer body, and the power generation layer body are removed to form the conductive film, the first charge transport layer, and the power generation layer of the plurality of photoelectric conversion elements.

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