Photoelectric conversion element and method for manufacturing the same

Abstract

The present invention provides a photoelectric conversion element in which spherical particles, which act as spacer particles to maintain a constant distance between a porous semiconductor layer and a counter electrode substrate, are uniformly distributed, and a method for manufacturing the same. [Solution] A paste 40' containing spherical particles 1 is used to arrange the spherical particles 1 between a porous semiconductor layer 30 and a counter electrode substrate 20. The photoelectric conversion element A manufactured in this manner comprises an electrode substrate 10, a counter electrode substrate 20, an electrolyte medium 50 enclosed in the region between the electrode substrate 10 and the counter electrode substrate 20, and a porous semiconductor layer 30 provided on the electrolyte medium 50 side of the electrode substrate 10 and supporting a sensitizing dye. Multiple spherical particles 1 are arranged between the porous semiconductor layer 30 and the counter electrode substrate 20, and a spherical particle fixing layer 40 is provided on the porous semiconductor layer 30 or on the counter electrode substrate 20 between them. At least a portion of each of the multiple spherical particles 1 exists embedded in the spherical particle fixing layer 40.

Description

Technical Field

[0001] The present disclosure relates to a photoelectric conversion element and a method for manufacturing the same.

Background Art

[0002] As solar cells for converting sunlight into electric power, solar cells using a crystalline silicon substrate and thin-film silicon solar cells are known. Solar cells using a crystalline silicon substrate use a silicon substrate, and thin-film silicon solar cells use various semiconductor manufacturing gases and apparatuses, etc., so the manufacturing cost of both tends to increase.

[0003] On the other hand, a dye-sensitized solar cell that applies the photoinduced electron transfer of a metal complex has been proposed without using a silicon substrate or the like that causes an increase in manufacturing cost. This type of dye-sensitized solar cell functions as a photoelectric conversion element that sensitizes oxide semiconductor fine particles with a sensitizing dye (a photosensitizing dye, hereinafter simply referred to as a dye) that absorbs incident light such as sunlight and converts light energy into electric power. In a dye-sensitized solar cell, when light is irradiated, electrons that have moved to one electrode pass through an external electric circuit and are then carried to ions in an electrolyte via the other opposing electrode and return to the photoelectric conversion layer (a semiconductor layer supporting a sensitizing dye), whereby electrical energy is extracted.

[0004] Patent Document 1 discloses that, in a dye-sensitized solar cell in which an electrode substrate provided with a semiconductor layer supporting a sensitizing dye and its counter electrode substrate are arranged with an electrolyte medium layer interposed therebetween, in order to keep the thickness of the electrolyte medium layer uniform, spacer particles (hereinafter referred to as spacer particles) are dispersed and arranged in the electrolyte medium layer. Further, in order to arrange the spacer particles in this way, it is disclosed that the spacer particles are sprayed (sprayed) and adhered wet or dry to the electrode substrate side or the counter electrode substrate side before bonding the two substrates.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2000-299138 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] As described in Patent Document 1, by arranging spacer particles to maintain a constant distance (substrate gap) between the electrode substrate and the counter electrode substrate, stress on the sealing portion between the two substrates caused by springback and the like can be reduced, thereby improving the reliability of the photoelectric conversion element.

[0007] However, implementing a method of scattering spacer particles on either the electrode substrate or the counter electrode substrate before bonding the two substrates (hereinafter referred to as the scattering method) requires preparing the necessary equipment and adding the scattering step to the manufacturing process of the photoelectric conversion element, which increases the time and cost involved in manufacturing.

[0008] Furthermore, in the manufacturing process of photoelectric conversion elements, when an electrolyte medium is dropped onto a substrate after spacer particles have been scattered, the force of the electrolyte medium flow during dropping causes the scattered spacer particles to move to the periphery of the electrolyte medium droplets, resulting in a large variation in the number of spacer particles per unit area within the scattered surface. In other words, there is a problem that the distribution of spacer particles within the scattered surface becomes uneven. In addition, because spacer particles are scattered across the entire substrate, spacer particles may adhere to areas other than the inside of the photoelectric conversion element (cell), which not only consumes extra spacer particles but may also affect the sealing performance of the photoelectric conversion element.

[0009] The contents of this disclosure were discovered in view of the above circumstances, and the main purpose of this disclosure is to provide a photoelectric conversion element in which spherical particles, which serve as spacer particles to maintain a constant distance between a porous semiconductor layer and a counter electrode substrate, are uniformly distributed, and a method for manufacturing the same. [Means for solving the problem]

[0010] To solve the above problems, the photoelectric conversion element disclosed herein is: An electrode substrate having a first conductive layer, A counter electrode substrate having a second conductive layer, An electrolyte medium sealed in the region between the electrode substrate and the counter electrode substrate, A sealing wall is disposed between the electrode substrate and the counter electrode substrate, and seals the electrolyte medium within the region. A photoelectric conversion element comprising a porous semiconductor layer on the electrolyte medium side of the electrode substrate, on which a sensitizing dye is supported, A plurality of spherical particles are arranged between the porous semiconductor layer and the counter electrode substrate, and a spherical particle fixing layer is provided on the porous semiconductor layer or on the counter electrode substrate between them. The plurality of spherical particles are characterized in that at least a portion of each exists embedded in the spherical particle fixing layer.

[0011] In the above-described photoelectric conversion element, the spherical particle stationary layer may include a porous organic solid.

[0012] Furthermore, in the above-described photoelectric conversion element, the organic solid may contain a steroid compound having a carboxyl group.

[0013] Furthermore, in the above-described photoelectric conversion element, the sealing wall may be configured to include spacer particles.

[0014] Furthermore, in the above-described photoelectric conversion element, the particle diameter of the spherical particles may be smaller than the distance between the electrode substrate and the counter electrode substrate in the region where the sealing wall is located.

[0015] To solve the above problems, the first method for manufacturing a photoelectric conversion element according to the present disclosure is: A paste coating step involves applying a paste containing spherical particles and a sensitizing dye onto the porous semiconductor layer of an electrode substrate, which has a porous semiconductor layer before the sensitizing dye is supported on it. A sealing material application process in which a sealing material is applied in a frame shape onto the counter electrode substrate, A dropping step in which an electrolyte medium is dropped onto the counter electrode substrate within the frame of the sealing material, A bonding step in which the electrode substrate having undergone the paste coating step and the counter electrode substrate having undergone the dropping step are bonded together via the sealing material, The process includes a curing step in which the sealing material is cured after the bonding step to form a sealing wall that seals the electrolyte medium in the region between the electrode substrate and the counter electrode substrate, After the bonding process, the sensitizing dye contained in the paste penetrates into and is adsorbed into the porous semiconductor layer, thereby enabling the porous semiconductor layer to support the sensitizing dye.

[0016] To solve the above problems, the second method for manufacturing a photoelectric conversion element according to the present disclosure is: A sealing material coating step is performed on an electrode substrate having a porous semiconductor layer before the sensitizing dye is supported, by applying a sealing material in a frame shape surrounding the porous semiconductor layer. A dropping step in which an electrolyte medium is dropped onto the electrode substrate within the frame of the sealing material, A paste coating step involves applying a paste containing spherical particles and a sensitizing dye onto a counter electrode substrate. A bonding step is performed to bond the electrode substrate that has undergone the dropping step and the counter electrode substrate that has undergone the paste coating step, using the sealing material as a means of bonding. The process includes a curing step in which the sealing material is cured after the bonding step to form a sealing wall that seals the electrolyte medium in the region between the electrode substrate and the counter electrode substrate, After the bonding step, the sensitizing dye contained in the paste penetrates and is adsorbed into the porous semiconductor layer via the electrolyte medium, thereby enabling the porous semiconductor layer to support the sensitizing dye.

[0017] To solve the above problems, the third method for manufacturing a photoelectric conversion element disclosed herein is: A paste coating step involves applying a paste containing spherical particles onto the porous semiconductor layer of an electrode substrate, which has a porous semiconductor layer before a sensitizing dye is supported on it. A sealant application step of applying a sealant in a frame shape on a counter electrode substrate; A dropping step of dropping an electrolyte medium containing a sensitizing dye on the counter electrode substrate within the frame of the sealant; A bonding step of bonding the electrode substrate that has undergone the paste application step and the counter electrode substrate that has undergone the dropping step through the sealant; A curing step of forming a sealing wall that seals the electrolyte medium in a region between the electrode substrate and the counter electrode substrate by curing the sealant after the bonding step, and includes: After the bonding step, the porous semiconductor layer supports the sensitizing dye by the sensitizing dye contained in the electrolyte medium penetrating and adsorbing into the porous semiconductor layer.

[0018] In order to solve the above problems, a fourth manufacturing method of the photoelectric conversion element of the present disclosure is: A dye solution immersion step of immersing an electrode substrate provided with a porous semiconductor layer before supporting a sensitizing dye in a solution containing a sensitizing dye to support the sensitizing dye on the porous semiconductor layer; A paste application step of applying a paste containing spherical particles on the porous semiconductor layer that has undergone the dye solution immersion step; A sealant application step of applying a sealant in a frame shape on a counter electrode substrate; [ [[ID=二十一]] A dropping step of dropping an electrolyte medium on the counter electrode substrate within the frame of the sealant;<XX000099>A bonding step of bonding the electrode substrate that has undergone the paste application step and the counter electrode substrate that has undergone the dropping step through the sealant; A curing step of forming a sealing wall that seals the electrolyte medium in a region between the electrode substrate and the counter electrode substrate by curing the sealant after the bonding step, and is characterized by including:

[0019] In the above first to fourth manufacturing methods, the paste used in the paste application step may have a configuration including a steroid compound having a carboxyl group and a nitrogen-containing heterocyclic compound.

[0020] Furthermore, in the first to fourth manufacturing methods described above, the sealing material used in the sealing material application step may contain spacer particles. [Effects of the Invention]

[0021] The photoelectric conversion element disclosed herein exhibits excellent effects, such as the uniform distribution of spherical particles that act as spacer particles to maintain a constant distance between the porous semiconductor layer and the counter electrode substrate. Furthermore, the method for manufacturing the photoelectric conversion element disclosed herein exhibits excellent effects, such as the ability to manufacture a photoelectric conversion element with such uniformly distributed spherical particles in a simple manner. [Brief explanation of the drawing]

[0022] [Figure 1] This is a schematic cross-sectional view showing a photoelectric conversion element according to the first embodiment. [Figure 2] This is a schematic cross-sectional view showing the internal void structure of the spherical particle fixed layer of the photoelectric conversion element in Figure 1, magnified for clarity. [Figure 3] This is a process diagram showing a method for manufacturing a photoelectric conversion element according to the first embodiment. [Figure 4] This is a schematic cross-sectional view showing the internal structure of a paste portion applied to a porous semiconductor layer, magnified for clarity. [Figure 5] This is a schematic cross-sectional view showing one step in the manufacturing method of a photoelectric conversion element according to the first embodiment. [Figure 6] This is a schematic cross-sectional view showing the process after Figure 5. [Figure 7] This is a process diagram showing a method for manufacturing a photoelectric conversion element according to the second embodiment. [Figure 8] This is a schematic cross-sectional view showing one step in the manufacturing method of a photoelectric conversion element according to the second embodiment. [Figure 9] This is a schematic cross-sectional view showing the subsequent process in Figure 8. [Figure 10] This is a process diagram showing a method for manufacturing a photoelectric conversion element according to the third embodiment. [Figure 11] This is a process diagram showing a method for manufacturing a photoelectric conversion element according to the fourth embodiment. [Figure 12] This is a schematic cross-sectional view showing a paste containing spherical particles but without a sensitizing dye applied to a porous semiconductor layer. [Figure 13] This is a process diagram showing a method for manufacturing a photoelectric conversion element as a comparative example. [Figure 14] This is a process diagram showing a method for manufacturing a photoelectric conversion element as a comparative example. [Figure 15] This is a schematic cross-sectional view of a photoelectric conversion element as a comparative example. [Modes for carrying out the invention]

[0023] Hereinafter, a photoelectric conversion element and its manufacturing method according to the embodiments of this disclosure will be described with reference to the drawings. The cross-sectional views in Figures 1 to 15 are all cross-sectional views obtained when the photoelectric conversion element (or the substrate in the manufacturing process thereof) is cut along the thickness direction of the electrode substrate or counter electrode substrate (i.e., the stacking direction of the electrode substrate and the counter electrode substrate). In addition, common reference numerals are used for components common to each embodiment to omit redundant explanations. Furthermore, in the following, "porous semiconductor layer 30 supporting the sensitizing dye" will also be simply referred to as "porous semiconductor layer 30," and "porous semiconductor layer 30' before supporting the sensitizing dye" will also be simply referred to as "porous semiconductor layer 30'." Furthermore, to the extent that it does not impair the effects relating to this disclosure, "spherical" and "cylindrical" in this disclosure are concepts that also include "approximately spherical" and "approximately cylindrical," respectively. Here, approximately spherical means not only a sphere but also a shape similar to a sphere, and approximately cylindrical means not only a cylinder but also a shape similar to a cylinder.

[0024] A photoelectric conversion element according to the embodiment of the present disclosure comprises an electrode substrate having a first conductive layer, a counter electrode substrate having a second conductive layer, an electrolyte medium enclosed in a region between the electrode substrate and the counter electrode substrate, a sealing wall disposed between the electrode substrate and the counter electrode substrate to seal the electrolyte medium within the region, and a porous semiconductor layer supporting a sensitizing dye. The porous semiconductor layer is provided on the side of the electrode substrate where the electrolyte medium is located.

[0025] Furthermore, in the photoelectric conversion element according to the embodiment of this disclosure, a plurality of spherical particles are arranged between the porous semiconductor layer and the counter electrode substrate, and a spherical particle immobilization layer is provided on the porous semiconductor layer or on the counter electrode substrate between them. In the following, a method for manufacturing a photoelectric conversion element in which the spherical particle immobilization layer is provided on the porous semiconductor layer will be described as a first embodiment, and a method for manufacturing a photoelectric conversion element in which the spherical particle immobilization layer is provided on the counter electrode substrate will be described as a second embodiment. In addition, a method for manufacturing a photoelectric conversion element in which the sensitizing dye is supported on the porous semiconductor layer differs from that of the first and second embodiments will be described as a third and fourth embodiment.

[0026] In the photoelectric conversion elements according to the first to fourth embodiments, the electrode substrate has at least a first conductive layer and a porous semiconductor layer supporting a sensitizing dye, and therefore functions as a photoelectrode. The counter electrode substrate has at least a second conductive layer and functions as a counter electrode to the photoelectrode. The counter electrode substrate may further have a catalyst layer, and the second conductive layer may also serve as the catalyst layer.

[0027] <First Embodiment> Figure 1 is a schematic cross-sectional view showing a photoelectric conversion element A according to the first embodiment. As shown in Figure 1, the photoelectric conversion element A has a configuration that includes an electrode substrate 10, a counter electrode substrate 20, and an electrolyte medium 50 filled between the two substrates.

[0028] The electrode substrate 10 includes a first substrate 11, which is a base substrate (support substrate), and a first conductive layer 12 provided on the surface of the first substrate 11 facing the electrolyte medium 50. The counter electrode substrate 20 includes a second substrate 21, which is a base substrate, and a second conductive layer 22 provided on the surface of the second substrate 21 facing the electrolyte medium 50. A catalyst layer 23 is further provided on the surface of the second conductive layer 22 facing the electrolyte medium 50. A porous semiconductor layer 30 supporting a sensitizing dye is provided on the surface of the electrode substrate 10 that is in contact with the electrolyte medium 50.

[0029] Multiple spherical particles 1 are arranged between the porous semiconductor layer 30 and the counter electrode substrate 20. The presence of the spherical particles 1 in this position allows them to function as spacers, maintaining a constant distance between the porous semiconductor layer 30 and the counter electrode substrate 20.

[0030] Furthermore, a spherical particle immobilization layer 40 is provided on the side of the porous semiconductor layer 30 closest to the counter electrode substrate 20 (the side opposite the electrode substrate 10), and at least a portion of the spherical particles 1 are embedded in the spherical particle immobilization layer 40. This embedded state of the spherical particles 1 in the spherical particle immobilization layer 40 restricts their movement on the porous semiconductor layer 30. In the photoelectric conversion element A, the spherical particles 1 are arranged to be uniformly distributed on the porous semiconductor layer 30, thereby maintaining a uniform substrate gap over a wide area. This is expected to improve solar cell characteristics, stabilize solar cell characteristics, and enhance reliability when used as a large-area dye-sensitized solar cell. In this disclosure, "immobilization" in "spherical particle immobilization layer" means that, as described above, the movement of the spherical particles 1 is suppressed by their embedding in the spherical particle immobilization layer 40, and does not require that the spherical particles 1 remain completely motionless.

[0031] The spherical particles 1 are preferably made of a material that does not dissolve or react with the electrolyte medium 50 and is non-conductive. Examples include fine particles made of resin, glass, etc., or inorganic fine particles such as silica, alumina, and zirconia. The spherical particles 1 preferably have sufficient rigidity to not deform under the pressure applied when bonding the electrode substrate 10 and the counter electrode substrate 20, but particles that deform slightly under the pressure applied during bonding may also be used.

[0032] The spherical particles 1 preferably have a uniform diameter (the particle diameter is nearly uniform) in order to maintain a constant distance between the porous semiconductor layer 30 and the counter electrode substrate 20. Here, uniform diameter means that the coefficient of variation (CV value), which indicates the monodispersity of the particles, is 10% or less. The coefficient of variation of the particles used as spherical particles 1 is more preferably 7% or less. As a method for measuring the coefficient of variation, one method is to take an image of the particles with a camera connected to an optical microscope and analyze the image. The particle diameter of the spherical particles 1 is preferably, for example, 10 μm or more and 40 μm or less. If the particle diameter is above the lower limit, it becomes thick enough to ensure the fluidity of the electrolyte medium 50 while suppressing short circuits due to contact between the porous semiconductor layer 30 and the counter electrode substrate 20. On the other hand, if the particle diameter exceeds the upper limit, the ion migration distance between the positive electrode (counter electrode substrate) and the negative electrode (electrode substrate) is long, so the internal resistance increases under high illumination, which may reduce the photoelectric conversion characteristics.

[0033] Figure 2 is a schematic, enlarged cross-sectional view showing a portion of the spherical particle immobilization layer 40 of the photoelectric conversion element A in Figure 1. As shown in Figure 2, the spherical particle immobilization layer 40 has a structure that includes an organic solid substrate 41 and voids 42, that is, it is a layer composed of a porous organic solid substrate 41 with numerous pores.

[0034] The spherical particle fixed layer 40 is a portion of the paste component of the paste 40' applied to the porous semiconductor layer 30 during the manufacturing of the photoelectric conversion element A. Therefore, the manufacturing method of the photoelectric conversion element A will be explained with reference to Figures 3 to 6.

[0035] Figure 3 is a process diagram showing the manufacturing method of the photoelectric conversion element A according to the first embodiment, and Figures 4 to 6 are schematic cross-sectional views showing the manufacturing process of the photoelectric conversion element A.

[0036] As shown in Figure 3, the method for manufacturing the photoelectric conversion element A according to the first embodiment includes a paste coating step S12 in which a paste 40' containing spherical particles 1 and a sensitizing dye is applied to the porous semiconductor layer 30' of an electrode substrate 10 having a porous semiconductor layer 30' before the sensitizing dye is supported; a drying step S13 in which the applied paste 40' is dried; a sealant coating step S15 in which a sealant is applied to the counter electrode substrate 20 in a frame shape; a dropping step S16 in which an electrolyte medium 50 is dropped onto the counter electrode substrate 20 within the frame of the sealant; a bonding step S17 in which the electrode substrate 10 that has gone through the drying step S13 and the counter electrode substrate 20 that has gone through the dropping step S16 are bonded together via the sealant; and a curing step S18 in which the sealant is cured after the bonding step S17 to form a sealing wall 60 that seals the electrolyte medium 50 in the region between the electrode substrate 10 and the counter electrode substrate 20. If the order of these steps can be changed, they may be carried out in a different order or in parallel.

[0037] Step S11 shown in Figure 3 is a step of preparing an electrode substrate 10 having a porous semiconductor layer 30' before the sensitizing dye is supported on it. The electrode substrate 10 has a first conductive layer 12 provided on a first substrate 11 which is a base substrate. The first substrate 11 is a non-conductive sheet-like member that has light transmittance (transparency) that allows light irradiated onto the light-receiving surface to reach it, and is a transparent substrate formed from, for example, glass, transparent resin, or silicon.

[0038] The first conductive layer 12 is made of a light-transmitting material similar to the first substrate 11 and is electrically conductive. For the material of the first conductive layer 12, at least one selected from the group consisting of indium tin composite oxide (ITO), tin oxide (SnO2), fluorine-doped tin oxide (FTO), and zinc oxide (ZnO) can be used. The average thickness of the first conductive layer 12 is preferably, for example, 0.02 μm or more and 5.0 μm or less.

[0039] The porous semiconductor layer 30' has a semiconductor material and can take various shapes, such as bulk, particulate, or a layer with numerous micropores, but it is preferable that it has a porous structure capable of supporting a dye. The semiconductor material constituting the porous semiconductor layer 30 can be at least one selected from the group consisting of titanium oxide, zinc oxide, tin oxide, iron oxide, niobium oxide, cerium oxide, tungsten oxide, barium titanate, strontium titanate, cadmium sulfide, lead sulfide, zinc sulfide, indium phosphide, copper-indium sulfide (CuInS2), CuAlO2, and SrCu2O2.

[0040] Of these, titanium dioxide is preferably used for the porous semiconductor layer 30'. As titanium dioxide, various types of titanium dioxide such as anatase-type titanium dioxide, rutile-type titanium dioxide, amorphous titanium dioxide, metatitaniumic acid, orthotitaniumic acid, titanium hydroxide, or hydrated titanium dioxide can be used alone or in mixtures. Furthermore, fine particles of titanium dioxide can be used as the material for the porous semiconductor layer 30'.

[0041] The semiconductor crystal system may be either single crystal or polycrystalline, but polycrystalline is preferred from the viewpoint of stability, ease of crystal growth, and manufacturing cost, and it is preferable to use polycrystalline nanoscale or microscale semiconductor nanoparticles. Titanium dioxide nanoparticles can be manufactured, for example, by liquid-phase methods such as hydrothermal synthesis or sulfuric acid synthesis, or by gas-phase methods.

[0042] As semiconductor nanoparticles, a mixture of two or more nanoparticles of the same or different semiconductor compounds with varying particle sizes may be used. Larger semiconductor nanoparticles contribute to improving the light capture rate by scattering incident light, while smaller semiconductor nanoparticles can increase the amount of dye adsorbed by increasing the number of adsorption sites. The average thickness of the porous semiconductor layer 30' is preferably, for example, 0.1 μm or more and 100.0 μm or less.

[0043] Figure 4 is a schematic cross-sectional view showing the internal structure of the paste 40' after it has been applied to the porous semiconductor layer 30' before the sensitizing dye is supported in the paste application step S12. In Figure 4, the spherical particles 1 are not shown in order to schematically show the internal structure of the paste 40' on a larger scale. Figure 5 is a schematic cross-sectional view showing one step of the manufacturing method of the photoelectric conversion element according to the first embodiment, and below it is shown the electrode substrate 10 after the paste 40' has been applied to the porous semiconductor layer 30' in the paste application step S12.

[0044] In the paste application step S12, the spherical particles 1 are placed on the porous semiconductor layer 30' by applying paste 40'. Therefore, unlike the scattering method described above, the problem of spherical particles 1 being scattered in locations other than on the porous semiconductor layer 30' does not occur. As shown in Figure 5, it is possible to place the spherical particles 1 only in the desired locations, and no excess spherical particles 1 are consumed. Furthermore, since paste 40' containing dispersed spherical particles 1 is prepared and applied to the porous semiconductor layer 30', the spherical particles 1 are arranged to be uniformly distributed on the porous semiconductor layer 30'.

[0045] Screen printing is preferred as the application method for paste 40'. In a method in which a solution containing a sensitizing dye (hereinafter referred to as the dye solution) is dropped onto a porous semiconductor layer to support the sensitizing dye, the penetration and adsorption of the dye into the porous semiconductor layer begins immediately at the time the dye solution is dropped. In contrast, in the paste application step S12 of the first embodiment, the penetration and adsorption of the dye into the porous semiconductor layer 30' does not occur immediately at the time the paste 40' is printed (applied), making it possible to adsorb the dye evenly onto the porous semiconductor layer 30' in a subsequent process.

[0046] The average thickness to which the paste 40' is applied is preferably about half the particle diameter of the spherical particles 1. In other words, in the photoelectric conversion element A, it is preferable that the spherical particles 1 exist in a state in which they are partially embedded in the spherical particle fixing layer 40. Specifically, the average thickness to which the paste 40' is applied (the average thickness of the spherical particle fixing layer 40) is preferably 20 μm or less, and more preferably 5 μm or more and 20 μm or less. An average thickness above the above lower limit is sufficient to provide the function of restricting the movement of the spherical particles 1 and the function of supporting the dye on the porous semiconductor layer 30'. On the other hand, if the average thickness exceeds the above upper limit, the diffusion of ions between the positive electrode (counter electrode substrate) and the negative electrode (electrode substrate) is inhibited, so the internal resistance may increase under high light intensity, potentially degrading the photoelectric conversion characteristics.

[0047] The paste 40' is a mixture containing spherical particles 1, a sensitizing dye, a component 41' that is poorly soluble or insoluble in the electrolyte medium 50 (hereinafter simply referred to as "poorly soluble component 41'"), a component 42' that is readily soluble in the electrolyte medium 50 (hereinafter simply referred to as "easily soluble component 42'"), and a solvent. The poorly soluble component 41' only needs to be poorly soluble to the extent that a portion remains as the organic solid substrate 41 in Figure 2, and the easily soluble component 42' only needs to be readily soluble to the extent that the void portion 42 in Figure 2 is formed.

[0048] Because the paste 40' is composed of these components, at least a portion of the poorly soluble component 41' remains undissolved in the electrolyte medium 50, remaining as the organic solid substrate 41 in Figure 2. In addition, the readily soluble component 42' dissolves in the electrolyte medium 50 to become part of the carrier transport material, and a void 42 in Figure 2 is formed in the region where the readily soluble component 42' was present before dissolution.

[0049] The type of solvent used in paste 40' is not particularly limited, but the same solvent as that exemplified later can be used as the solvent for the electrolyte medium 50 (electrolyte).

[0050] As the dye to be added to the paste 40' (in other words, the dye to be supported on the porous semiconductor layer 30), one or more types of various organic dyes and metal complex dyes having absorption in the visible light region or the infrared light region can be selectively used. As the organic dye, for example, at least one selected from the group consisting of azo dyes, quinone dyes, quinone imine dyes, quinacridone dyes, squarylium dyes, cyanine dyes, merocyanine dyes, triphenylmethane dyes, xanthene dyes, porphyrin dyes, perylene dyes, indigo dyes, and naphthalocyanine dyes can be used.

[0051] Metal complex dyes are formed by the coordination bonding of a metal to a molecule. Examples of molecules include porphyrin dyes, phthalocyanine dyes, naphthalocyanine dyes, bipyridine dyes, or terpyridine dyes. The metal can be at least one selected from the group including, for example, Cu, Ni, Fe, Co, V, Sn, Si, Ti, Ge, Cr, Zn, Ru, Mg, Al, Pb, Mn, In, Mo, Y, Zr, Nb, Sb, La, W, Pt, TA, Ir, Pd, Os, Ga, Tb, Eu, Rb, Bi, Se, As, Sc, Ag, Cd, Hf, Re, Au, Ac, Tc, Te, and Rh. It is preferable to use metal complex dyes in which a metal is coordinated to a phthalocyanine dye, bipyridine dye, or terpyridine dye, and particularly preferable to use ruthenium-bipyridine complex dyes.

[0052] In the embodiments of this disclosure, a steroid compound having a carboxyl group is used as the poorly soluble component 41' added to the paste 40', and a nitrogen-containing heterocyclic compound is used as the readily soluble component 42'. The substances used as the poorly soluble component 41' and readily soluble component 42' are not limited to these, but steroid compounds having a carboxyl group have been used as flocculation inhibitors in dye solutions in conventional photoelectric conversion elements (dye-sensitized solar cells), and nitrogen-containing heterocyclic compounds have been used as additives to electrolyte media (electrolytes) in conventional photoelectric conversion elements. Therefore, their long-term stability and safety when used as materials for photoelectric conversion elements have been confirmed. For this reason, they are suitable for use as the poorly soluble component 41' and readily soluble component 42', respectively.

[0053] Examples of steroid compounds containing a carboxyl group in paste 40' include cholic acid, lithocholic acid, deoxycholic acid, chenodeoxycholic acid, and ursodeoxycholic acid. These compounds may be used individually or in combination of two or more.

[0054] As the nitrogen-containing heterocyclic compound in paste 40', for example, those used in the art as additives to electrolyte media 50 can be used. Examples of such nitrogen-containing heterocyclic compounds include pyridine, pyrazole, imidazole, pyrrole, purine, and their derivatives.

[0055] Among these, pyrazoles or pyrazole derivatives are particularly preferred. Examples of pyrazole derivatives include 1-methylpyrazole, 3-methylpyrazole, 3,5-dimethylpyrazole, 3,5-diisopropylpyrazole, 3-amino-5-methylpyrazole, and 4-iodo-3,5-dimethylpyrazole.

[0056] Examples of amines of heterocyclic aromatic compounds include 4-tert-butylpyridine. Examples of salts of amines of heterocyclic aromatic compounds include imidazole salts such as dimethylpropylimidazole iodide (DMPII), methylpropylimidazole iodide (MPII), ethylmethylimidazole iodide (EMII), ethylimidazole iodide (EII), and hexylmethylimidazole iodide (HMII).

[0057] These compounds, exemplified as nitrogen-containing heterocyclic compounds, may be used individually or in combination of two or more.

[0058] The preferred ratio of the sensitizing dye in paste 40' is such that, where X moles are the amount of sensitizing dye and Y moles are the amount of the carboxyl-group-containing steroid compound, the molar ratio Y / X is between 10 and 100. By using paste 40' containing the sensitizing dye in such a ratio, the sensitizing dye can be efficiently penetrated into the porous semiconductor layer 30'.

[0059] In drying step S13, the paste 40' applied in paste application step S12 is dried. The drying method is not particularly limited, but examples include vacuum drying or heat drying of the electrode substrate 10. As the paste 40' dries and hardens, the spherical particles 1 are fixed in a state in which at least a portion of them are embedded in the paste 40', making it possible to maintain a state in which the spherical particles 1 are uniformly distributed on the porous semiconductor layer 30'.

[0060] Next, the process relating to the counter electrode substrate 20 will be described. Step S14 shown in Figure 3 is the process of preparing the counter electrode substrate 20. The counter electrode substrate 20 is made of a second substrate 21, which is a non-conductive sheet-like material with light transmission, and a second conductive layer 22 (counter electrode conductive layer) that is both light-transmitting and conductive. The second substrate 21 and the second conductive layer 22 of the counter electrode substrate 20 can have the same configuration as the first substrate 11 and the first conductive layer 12 that constitute the electrode substrate 10. Note that since the counter electrode substrate 20 is on the opposite side from the light-receiving surface, it may have a configuration that does not transmit light. That is, the counter electrode substrate 20 may be made of a second substrate 21, which is a sheet-like material that does not transmit light, and a second conductive layer 22 that does not transmit light.

[0061] A catalyst layer 23 is further laminated on the second conductive layer 22. The catalyst layer 23 contains catalytic particles. The catalytic particles are not particularly limited, but can be selected from metal particles, carbon particles, conductive polymers, etc., and may contain multiple types of these. The method of laminating the catalyst layer 23 is not particularly limited, but can be done by screen printing, vapor deposition, sputtering, etc.

[0062] In the sealing material application process S15, the sealing material is applied in a frame shape onto the counter electrode substrate 20. In the subsequent curing process S18, the sealing material is cured to form the sealing wall 60 of the photoelectric conversion element A shown in Figure 1.

[0063] As shown in Figure 1, the sealing wall 60 has a structure that includes the cured adhesive material 61 and spacer particles 62. In other words, the sealing material applied in the sealing material application process S15 has a structure in which spacer particles 62 are added to the adhesive material 61 before curing. Because spacer particles 62 are present in the sealing wall 60 in this way, the distance (substrate gap) between the electrode substrate 10 and the counter electrode substrate 20 is kept constant even within the sealing wall 60. As described above, since the distance between the porous semiconductor layer 30 and the counter electrode substrate 20 is kept constant by the spherical particles 1, the photoelectric conversion element A has a highly reliable structure in which the substrate gap is kept constant over its entire surface.

[0064] The adhesive material 61 can be any material in which spacer particles 62 can be dispersed and which can encapsulate the electrolyte medium 50. Photocurable resins, thermosetting resins, etc., can be used. For example, when using an ultraviolet-curable resin, the adhesive material 61 is cured by irradiating it with ultraviolet light in curing step S18. This forms a sealing wall 60 composed of the cured adhesive material 61 and the spacer particles 62.

[0065] The material and shape of the spacer particles 62 are not particularly limited as long as they can function as spacers. Examples of materials for the spacer particles 62 include fine particles made of resin, glass, etc., and inorganic fine particles such as silica. Examples of shapes for the spacer particles 62 include spherical and cylindrical shapes. When the spacer particles 62 are cylindrical particles, the distance between the electrode substrate 10 and the counter electrode substrate 20 is determined based on the diameter of the cylindrical base of the cylindrical particle. This is because when a sealing material containing cylindrical particles is applied to the first conductive layer 12 and the counter electrode substrate 20 is bonded on top of it, the cylindrical particles are arranged so that the height direction of their cylinders is parallel to the surface of the first conductive layer 12.

[0066] In this case, by making the particle diameter of the spherical particle 1 smaller than the distance between the electrode substrate 10 and the counter electrode substrate 20 in the region where the sealing wall 60 is located, the distance between the electrode substrate 10 and the counter electrode substrate 20 in the region where the sealing wall 60 is located can be brought closer to the distance between the electrode substrate 10 and the counter electrode substrate 20 in the region where the porous semiconductor layer 30 is located. For example, if the shape of the spacer particle 62 is spherical, by making the particle diameter of the spherical particle 1 smaller than the particle diameter of the spacer particle 62, a structure in which the substrate gap is kept constant over the entire surface can be realized. Also, if the shape of the spacer particle 62 is cylindrical, by making the particle diameter of the spherical particle 1 smaller than the diameter of the cylindrical base of the spacer particle 62, a structure in which the substrate gap is kept constant over the entire surface can be realized.

[0067] Figure 5 is a schematic cross-sectional view showing one step of the manufacturing method of a photoelectric conversion element according to the first embodiment, and above it, the counter electrode substrate 20 after the electrolyte medium 50 has been dropped in the dropping step S16 is schematically shown. Figure 6 is a schematic cross-sectional view showing the process in which the paste 40' and the porous semiconductor layer 30' are immersed in the electrolyte medium 50 by bonding the electrode substrate 10 that has gone through the drying step S13 and the counter electrode substrate 20 that has gone through the dropping step S16 in the bonding step S17. In Figures 5 and 6, the sealant applied in the sealant application step S15 is not shown, but the sealant is applied to a position corresponding to the sealing wall 60 in the photoelectric conversion element A in Figure 1.

[0068] In the dropping step S16, the electrolyte medium 50 is dropped onto the counter electrode substrate 20 within the frame of the sealant applied in the sealant application step S15. The electrolyte medium 50 is typically an electrolyte solution. The electrolyte solution is a liquid containing an oxidation-reduction pair, and can be a liquid composed of an oxidation-reduction pair and a solvent capable of dissolving it, a liquid composed of an oxidation-reduction pair and a molten salt capable of dissolving it, a liquid composed of an oxidation-reduction pair, a solvent capable of dissolving it and a molten salt, etc.

[0069] Examples of redox pairs include combinations of metal iodides such as LiI, NaI, KI, and CaI2 with iodine; combinations of metal bromides such as LiBr, NaBr, KBr, and CaBr2 with bromine; combinations of salts containing iodide ions with iodine; and combinations of salts containing bromide ions with bromine. Among these, combinations of LiI and iodine, and combinations of salts containing iodide ions with iodine are preferred. Two or more of these redox pairs can be used in combination.

[0070] The solvent for the electrolyte is preferably a solvent containing at least one selected from the group consisting of, for example, a carbonate compound such as propylene carbonate, a nitrile compound such as acetonitrile, an alcohol such as ethanol, a cyclic ester such as γ-butyrolactone or ε-caprolactone, a cyclic amide such as 1-methyl-2-pyrrolidone, water, and a non-proton polar substance. It is even more preferable to use cyclic esters or cyclic amides alone or in combination as the solvent.

[0071] The electrolyte medium 50 may optionally contain additives such as nitrogen-containing heterocyclic compounds. Examples of nitrogen-containing heterocyclic compounds include pyridine, pyrazole, imidazole, pyrrole, purine, and their derivatives.

[0072] Among these, pyrazoles or pyrazole derivatives are particularly preferred. Examples of pyrazole derivatives include 1-methylpyrazole, 3-methylpyrazole, 3,5-dimethylpyrazole, 3,5-diisopropylpyrazole, 3-amino-5-methylpyrazole, and 4-iodo-3,5-dimethylpyrazole.

[0073] Examples of amines of heterocyclic aromatic compounds include 4-tert-butylpyridine. Examples of salts of amines of heterocyclic aromatic compounds include imidazole salts such as dimethylpropylimidazole iodide (DMPII), methylpropylimidazole iodide (MPII), ethylmethylimidazole iodide (EMII), ethylimidazole iodide (EII), and hexylmethylimidazole iodide (HMII).

[0074] These compounds, exemplified as additives, may be used individually or in combination of two or more.

[0075] Next, in the bonding step S17, the electrode substrate 10, which has undergone the drying step S13, and the counter electrode substrate 20, which has undergone the dropping step S16, are bonded together via a sealing material. Furthermore, in the curing step S18, the sealing material is cured to form a sealing wall 60. As a result, as shown in Figure 1, the electrolyte medium 50 is sealed in the region between the electrode substrate 10 and the counter electrode substrate 20.

[0076] As shown in Figure 6, when the electrode substrate 10 and the counter electrode substrate 20 are bonded together in bonding step S17, spherical particles 1 are present between the porous semiconductor layer 30' and the counter electrode substrate 20, so the spherical particles 1 function as spacers between the porous semiconductor layer 30' and the counter electrode substrate 20. Therefore, it is possible to maintain an appropriate distance between the porous semiconductor layer 30' and the counter electrode substrate 20 in bonding step S17, and consequently, it is possible to manufacture a photoelectric conversion element with a highly reliable structure in which the substrate gap is kept constant over the entire surface.

[0077] Furthermore, as shown in Figure 6, when the electrode substrate 10 and the counter electrode substrate 20 are bonded together in the bonding step S17, and the paste 40' and the porous semiconductor layer 30' are immersed in the electrolyte medium 50, the easily soluble components 42' contained in the paste 40' dissolve in the electrolyte medium 50, and the sensitizing dye contained in the paste 40' penetrates into the porous semiconductor layer 30'. Note that the progress of sensitizing dye penetration shown in Figures 5 and 6 is schematic, and in reality, the penetration of the sensitizing dye into the porous semiconductor layer 30' may begin from the drying step S13, in which the applied paste 40' is dried.

[0078] The permeated sensitizing dye is adsorbed onto the porous semiconductor layer 30', forming a porous semiconductor layer 30 supporting the sensitizing dye. Through this mechanism, after the lamination process S17, the sensitizing dye diffuses uniformly and is adsorbed onto the porous semiconductor layer 30', making it possible to obtain a porous semiconductor layer 30 with a high concentration of uniformly adsorbed sensitizing dye.

[0079] <Second Embodiment> Figure 7 is a process diagram showing a method for manufacturing a photoelectric conversion element according to the second embodiment, and Figures 8 and 9 are schematic cross-sectional views showing the manufacturing process of the photoelectric conversion element.

[0080] As shown in Figure 7, the method for manufacturing a photoelectric conversion element according to the second embodiment includes a sealing material coating step S22 in which a sealing material is applied in a frame shape on an electrode substrate 10, a dropping step S23 in which an electrolyte medium 50 is dropped onto the electrode substrate 10 within the frame of the sealing material, a paste coating step S25 in which a paste 40' containing spherical particles 1 and a sensitizing dye is applied to a counter electrode substrate 20, a drying step S26 in which the applied paste 40' is dried, a bonding step S27 in which the electrode substrate 10 that has gone through the dropping step S23 and the counter electrode substrate 20 that has gone through the drying step S26 are bonded together via the sealing material, and a curing step S28 in which the sealing material is cured after the bonding step S27 to form a sealing wall 60 that seals the electrolyte medium 50 in the region between the electrode substrate 10 and the counter electrode substrate 20. Steps S21 and S24 shown in Figure 7 are steps for preparing both substrates and are the same as steps S11 and S14 according to the first embodiment. Those of these steps whose order can be changed may be performed in a different order or in parallel. The differences between these steps and those of the first embodiment will now be explained.

[0081] In the sealing material application step S22, the sealing material is applied to the first conductive layer 12 of the electrode substrate 10 in a frame shape surrounding the porous semiconductor layer 30'. Then, in the dropping step S23, the electrolyte medium 50 is dropped onto the electrode substrate 10 within the frame of the sealing material.

[0082] Figure 8 is a schematic cross-sectional view showing the state in which the electrolyte medium 50 is dropped onto the porous semiconductor layer 30' provided on the electrode substrate 10 in the dropping step S23, and the paste 40' is applied onto the catalyst layer 23 of the counter electrode substrate 20 in the paste coating step S25. Figure 9 is a schematic cross-sectional view showing the process in which the electrode substrate 10 after the dropping step S23 and the counter electrode substrate 20 after the drying step S26 are bonded together in the bonding step S27, in which the spherical particles 1 function as spacers between the porous semiconductor layer 30' and the counter electrode substrate 20, and in which the paste 40' is immersed in the electrolyte medium 50 as a result of this bonding.

[0083] Thus, in the method for manufacturing the photoelectric conversion element according to the second embodiment, the paste 40' is applied to the counter electrode substrate 20 side. Therefore, the photoelectric conversion element according to the second embodiment is a photoelectric conversion element in which the spherical particle fixed layer 40 is provided on the counter electrode substrate 20 (on the electrolyte medium 50 side of the counter electrode substrate 20). By applying the paste 40' to the counter electrode substrate 20 side, the electrolyte medium 50 can be dropped onto the electrode substrate 10 side (porous semiconductor layer 30' side), so that the electrolyte medium 50 can be pre-permeated into the pores of the porous semiconductor layer 30', and the generation of vacuum bubbles after bonding the two substrates in bonding step S27 can be suppressed.

[0084] As shown in Figures 8 and 9, when the electrode substrate 10 and the counter electrode substrate 20 are bonded together in bonding step S27, spherical particles 1 are present between the porous semiconductor layer 30' and the counter electrode substrate 20, so the spherical particles 1 function as spacers between the porous semiconductor layer 30' and the counter electrode substrate 20. Therefore, it is possible to maintain an appropriate distance between the porous semiconductor layer 30' and the counter electrode substrate 20 in bonding step S27, and consequently, it is possible to manufacture a photoelectric conversion element with a highly reliable structure in which the substrate gap is kept constant over the entire surface.

[0085] Furthermore, as shown in Figure 9, when the electrode substrate 10 and the counter electrode substrate 20 are bonded together in the bonding step S27, and the paste 40' and the porous semiconductor layer 30' are immersed in the electrolyte medium 50, the easily soluble components 42' contained in the paste 40' dissolve in the electrolyte medium 50, and the sensitizing dye contained in the paste 40' also moves into the electrolyte medium 50'. In addition, the sensitizing dye penetrates into the porous semiconductor layer 30', and the penetrated sensitizing dye is adsorbed onto the porous semiconductor layer 30', forming a porous semiconductor layer 30 supporting the sensitizing dye. Through this mechanism, the sensitizing dye diffuses uniformly after the bonding step S27 and is adsorbed onto the porous semiconductor layer 30', so a porous semiconductor layer 30 with a high concentration of uniformly adsorbed sensitizing dye can be obtained.

[0086] <Third and Fourth Embodiments> In the first and second embodiments described above, a method for manufacturing a photoelectric conversion element was described in which a sensitizing dye is supported on a porous semiconductor layer 30' using a paste 40' containing spherical particles 1 and a sensitizing dye. In the third and fourth embodiments, a method for manufacturing a photoelectric conversion element in which a sensitizing dye is supported on a porous semiconductor layer 30' using a different method will be described.

[0087] In the manufacturing method of the photoelectric conversion element according to the third and fourth embodiments, a paste 40a' containing spherical particles 1 but not containing a sensitizing dye is used. The spherical particle fixed layer 40 in the photoelectric conversion element according to the third and fourth embodiments is a portion of the paste component of the paste 40a' applied to the porous semiconductor layer 30 during its manufacture that remains.

[0088] Figure 10 is a process diagram showing a method for manufacturing a photoelectric conversion element according to the third embodiment, and Figure 11 is a process diagram showing a method for manufacturing a photoelectric conversion element according to the fourth embodiment. Figure 12 is a schematic cross-sectional view showing the paste 40a' applied to the porous semiconductor layer 30.

[0089] As shown in Figure 10, the method for manufacturing a photoelectric conversion element according to the third embodiment includes a paste coating step S32 in which a paste 40a' containing spherical particles 1 is applied to the porous semiconductor layer 30' of an electrode substrate 10 having a porous semiconductor layer 30' before the sensitizing dye is supported; a drying step S33 in which the applied paste 40a' is dried; a sealant coating step S35 in which a sealant is applied to the counter electrode substrate 20 in a frame shape; a dropping step S36 in which an electrolyte medium 50 containing a sensitizing dye is dropped onto the counter electrode substrate 20 within the frame of the sealant; a bonding step S37 in which the electrode substrate 10 that has gone through the drying step S33 and the counter electrode substrate 20 that has gone through the dropping step S36 are bonded together via the sealant; and a curing step S38 in which the sealant is cured after the bonding step S37 to form a sealing wall 60 that seals the electrolyte medium 50 containing a sensitizing dye in the region between the electrode substrate 10 and the counter electrode substrate 20. Steps S31 and S34 shown in Figure 10 are steps for preparing both substrates, and are the same as steps S11 and S14 in the first embodiment, respectively. Among these steps, those whose order can be changed may be performed in a different order or in parallel. The differences between these steps and those in the first embodiment will now be explained.

[0090] The paste application step S32 can be carried out in the same manner as the paste application step S12 according to the first embodiment, except that paste 40a' is used instead of paste 40'. Paste 40a' can be used with the same component composition as paste 40', except that it does not contain spherical particles 1.

[0091] The dropping step S36 is a step in which an electrolyte medium 50 containing a sensitizing dye (the electrolyte medium 50 described in the first embodiment with a sensitizing dye added) is dropped into the frame of the sealant applied to the counter electrode substrate 20 in the sealant application step S35. In the bonding step S37, the electrode substrate 10 that has gone through the drying step S33 and the counter electrode substrate 20 that has gone through the dropping step S36 are bonded together, and when the porous semiconductor layer 30' is immersed in the electrolyte medium 50 containing the sensitizing dye, the sensitizing dye penetrates into the porous semiconductor layer 30', and the penetrated sensitizing dye is adsorbed onto the porous semiconductor layer 30', forming a porous semiconductor layer 30 supporting the sensitizing dye.

[0092] Other steps can be carried out in the same manner as in the first embodiment, and in the bonding step S37, spherical particles 1 are present between the porous semiconductor layer 30' and the counter electrode substrate 20, and the spherical particles 1 function as spacers between the porous semiconductor layer 30' and the counter electrode substrate 20, just as in the first embodiment.

[0093] As shown in Figure 11, the manufacturing method of the photoelectric conversion element according to the fourth embodiment includes a dye solution immersion step S42 in which an electrode substrate 10 having a porous semiconductor layer 30' before the sensitizing dye is supported is immersed in a dye solution to obtain a porous semiconductor layer 30 supported by the sensitizing dye; a drying step S43 in which the electrode substrate 10 immersed in the dye solution is dried; a paste coating step S44 in which a paste 40a' containing spherical particles 1 is applied to the porous semiconductor layer 30 after drying; and a drying step S44 in which the applied paste 40a' is dried. The process includes: 45, a sealing material application step S47 in which a sealing material is applied in a frame shape onto the counter electrode substrate 20; a dropping step S48 in which an electrolyte medium 50 is dropped onto the counter electrode substrate 20 within the frame of the sealing material; a bonding step S49 in which the electrode substrate 10 that has undergone the drying step S45 and the counter electrode substrate 20 that has undergone the dropping step S48 are bonded together via the sealing material; and a curing step S50 in which the sealing material is cured after the bonding step S49 to form a sealing wall 60 that seals the electrolyte medium 50 in the region between the electrode substrate 10 and the counter electrode substrate 20. Steps S41 and S46 shown in Figure 11 are steps for preparing both substrates and are the same as steps S11 and S14 in the first embodiment, respectively. Among these steps, those in which the order can be changed may be performed in a different order or in parallel. The differences between these steps and those in the first embodiment will be explained below.

[0094] In the dye solution immersion step S42, the electrode substrate 10, which has a porous semiconductor layer 30' before the sensitizing dye is supported, is immersed in the dye solution to obtain a porous semiconductor layer 30 on which the sensitizing dye is supported. That is, in the first embodiment, the sensitizing dye was supported on the porous semiconductor layer 30' using a paste 40' containing the sensitizing dye, whereas in the fourth embodiment, the sensitizing dye is supported on the porous semiconductor layer 30' by immersing the electrode substrate 10 in the dye solution.

[0095] In drying step S43, the electrode substrate 10 immersed in the dye solution is dried. The drying method is not particularly limited, but examples include vacuum drying or heat drying of the electrode substrate 10.

[0096] The paste coating step S44 is a step of coating the porous semiconductor layer 30 with a paste 40a' containing spherical particles 1, as shown in Figure 12. It can be carried out in the same manner as the paste coating step S12 according to the first embodiment, except that paste 40a' is used instead of paste 40'. Paste 40a' can be used with the same component composition as paste 40', except that it does not contain spherical particles 1.

[0097] Other steps can be carried out in the same manner as in the first embodiment, and in the bonding step S37, spherical particles 1 are present between the porous semiconductor layer 30 and the counter electrode substrate 20, and the spherical particles 1 function as spacers between the porous semiconductor layer 30 and the counter electrode substrate 20, just as in the first embodiment.

[0098] <Comparative Example> Finally, as a comparative example, we will illustrate the case in which spacer particles are placed between the porous semiconductor layer and the counter electrode substrate by a scattering method, and explain the challenges in that case. Figures 13 and 14 are process diagrams showing the manufacturing method of a photoelectric conversion element as a comparative example, and Figure 15 is a schematic cross-sectional view showing a photoelectric conversion element as a comparative example.

[0099] The comparative example photoelectric conversion element B shown in Figure 15 is an example of a photoelectric conversion element in which spacer particles are arranged by a scattering method. Photoelectric conversion element B comprises an electrode substrate 110 having a first substrate 111 and a first conductive layer 112, a counter electrode substrate 120 having a second substrate 121, a second conductive layer 122 and a catalyst layer 123, an electrolyte medium 150 enclosed in the region between the electrode substrate 110 and the counter electrode substrate 120, a sealing wall 160 that seals the electrolyte medium 150 within the region, and a porous semiconductor layer 130 provided on the electrode substrate 110. Spacer particles 101 are arranged between the porous semiconductor layer 130 and the counter electrode substrate 120. However, there is no layer to fix the spacer particles 101, and the structural stability is inferior to that of photoelectric conversion element A shown in Figure 1. Furthermore, there are the following problems due to its manufacturing process.

[0100] The manufacturing method of the comparative example shown in Figure 13 consists of a dye solution immersion step S102 in which an electrode substrate having a porous semiconductor layer before the sensitizing dye is supported is immersed in a dye solution to obtain a porous semiconductor layer supporting the sensitizing dye; a drying step S103 in which the electrode substrate immersed in the dye solution is dried; a spacer particle scattering step S104 in which spacer particles are scattered on the porous semiconductor layer after drying; a sealant application step S105 in which a sealant is applied to the electrode substrate in a frame shape so as to surround the porous semiconductor layer; a dropping step S106 in which an electrolyte medium is dropped onto the electrode substrate within the frame of the sealant; a bonding step S108 in which the electrode substrate 10 and the counter electrode substrate 20 that have gone through the drying step S106 are bonded together via the sealant; and a curing step S109 in which the sealant is cured after the bonding step S108 to form a sealing wall that seals the electrolyte medium in the region between the electrode substrate and the counter electrode substrate. Steps S101 and S107 shown in Figure 13 are steps for preparing both substrates.

[0101] The manufacturing method of the comparative example shown in Figure 14 consists of a paste coating step S202 in which a paste containing a sensitizing dye is applied to the porous semiconductor layer of an electrode substrate having a porous semiconductor layer before the sensitizing dye is supported; a drying step S203 in which the applied paste is dried; a spacer particle scattering step S205 in which spacer particles are scattered on the counter electrode substrate; a sealant coating step S206 in which a sealant is applied in a frame shape on the counter electrode substrate after the spacer particles have been scattered; a dropping step S207 in which an electrolyte medium is dropped onto the counter electrode substrate within the frame of the sealant; a bonding step S208 in which the electrode substrate that has gone through the drying step S203 and the counter electrode substrate that has gone through the dropping step S207 are bonded together via the sealant; and a curing step S209 in which the sealant is cured after the bonding step S208 to form a sealing wall that seals the electrolyte medium in the region between the electrode substrate and the counter electrode substrate. Steps S201 and S204 shown in Figure 14 are steps for preparing both substrates.

[0102] In the comparative examples shown in Figures 13 and 14, spacer particles are placed on the porous semiconductor layer by spacer particle dispersal steps S104 and S205. Therefore, it is necessary to prepare equipment for dispersing the spacer particles before carrying out these steps. Typically, these steps are carried out by dispersing the spacer particles to cover a wider area than the substrate area to be dispersed, and then placing the substrate near the center of the dispersal surface, thereby minimizing unevenness in the amount of particles dispersed on the substrate. However, this results in the problem of a large amount of spacer particles not being dispersed on the substrate.

[0103] In addition, even with measures taken to suppress unevenness in the amount of particles dispersed on the substrate, differences in the dispersion density of spacer particles occur between the center and the outer edges of the substrate. Furthermore, in the comparison example in Figure 13, the electrolyte medium is dropped onto the electrode substrate after the spacer particles have been dispersed, while in the comparison example in Figure 14, the electrolyte medium is dropped onto the counter electrode substrate after the spacer particles have been dispersed. When the electrolyte medium is dropped onto a substrate after the spacer particles have been dispersed, the force of the electrolyte medium flow during dropping causes the dispersed spacer particles to move around the electrolyte medium droplets, resulting in an uneven distribution of spacer particles within the dispersed surface. In other words, variations occur in the gap between substrates within the photoelectric conversion element, which leads to a decrease in performance. This problem is particularly pronounced in large-area dye-sensitized solar cell modules, where the performance variation between panels becomes large when multiple panels are manufactured by cutting from a large-area substrate using multi-sided cutting.

[0104] Furthermore, since the spacer particle scattering process S104 and S205 involves scattering spacer particles across the entire substrate before the sealing material application process S105 and S206 is carried out, this could potentially affect the sealing performance of the photoelectric conversion element. Therefore, before performing the sealing material application process S105 and S206, it is necessary to wipe off any spacer particles present in the areas where the sealing material should be applied. In other words, the addition of the spacer particle scattering process leads to an increase in the overall complexity of the photoelectric conversion element manufacturing process.

[0105] Furthermore, the embodiments disclosed herein are illustrative in all respects and do not constitute a limiting interpretation. Therefore, the technical scope of this disclosure is not construed solely by the embodiments described above, but is defined based on the claims. This includes all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0106] 1. Spherical particle (spacer particle) 10 Electrode substrate 11. First circuit board 12 First conductive layer 20 Counter electrode substrate 21 Second board 22. Second conductive layer (counter electrode conductive layer) 23 Catalyst layer 30 Porous semiconductor layer supporting sensitizing dye 30′ Porous semiconductor layer before supporting the sensitizing dye 40. Spherical particle immobilization layer (porous organic solid layer) 41 Organic solid base material 42 Cavity 40′ Paste containing sensitizing dye and spherical particles 41′ poorly soluble components 42′ Easily soluble components 40a' Paste containing spherical particles 50 Electrolyte medium 60 Sealing wall 61 (After curing) adhesive material 62 Spacer particles for sealing walls A Photoelectric conversion element

Claims

1. An electrode substrate having a first conductive layer, A counter electrode substrate having a second conductive layer, An electrolyte medium sealed in the region between the electrode substrate and the counter electrode substrate, A sealing wall is disposed between the electrode substrate and the counter electrode substrate, and seals the electrolyte medium within the region. A photoelectric conversion element comprising a porous semiconductor layer on the electrolyte medium side of the electrode substrate, on which a sensitizing dye is supported, A plurality of spherical particles are arranged between the porous semiconductor layer and the counter electrode substrate, and a spherical particle fixing layer is provided on the porous semiconductor layer or on the counter electrode substrate between them. A photoelectric conversion element characterized in that a plurality of the spherical particles exist in a state in which at least a portion of each is embedded in the spherical particle fixing layer.

2. A photoelectric conversion element according to claim 1, The photoelectric conversion element is characterized in that the spherical particle immobilization layer contains a porous organic solid.

3. A photoelectric conversion element according to claim 2, The photoelectric conversion element is characterized in that the organic solid contains a steroid compound having a carboxyl group.

4. A photoelectric conversion element according to claim 1, The photoelectric conversion element is characterized in that the sealing wall contains spacer particles.

5. A photoelectric conversion element according to claim 4, A photoelectric conversion element characterized in that the particle diameter of the spherical particles is smaller than the distance between the electrode substrate and the counter electrode substrate in the region where the sealing wall is arranged.

6. A method for manufacturing a photoelectric conversion element according to claim 1, A paste coating step involves applying a paste containing spherical particles and a sensitizing dye onto the porous semiconductor layer of an electrode substrate, which has a porous semiconductor layer before the sensitizing dye is supported on it. A sealing material application process in which a sealing material is applied in a frame shape onto the counter electrode substrate, A dropping step in which an electrolyte medium is dropped onto the counter electrode substrate within the frame of the sealing material, A bonding step in which the electrode substrate having undergone the paste coating step and the counter electrode substrate having undergone the dropping step are bonded together via the sealing material, The process includes a curing step in which the sealing material is cured after the bonding step to form a sealing wall that seals the electrolyte medium in the region between the electrode substrate and the counter electrode substrate, A method for manufacturing a photoelectric conversion element, characterized in that, after the bonding step, the sensitizing dye contained in the paste penetrates into and is adsorbed into the porous semiconductor layer, so that the porous semiconductor layer supports the sensitizing dye.

7. A method for manufacturing a photoelectric conversion element according to claim 1, A sealing material coating step is performed on an electrode substrate having a porous semiconductor layer before the sensitizing dye is supported, by applying a sealing material in a frame shape surrounding the porous semiconductor layer. A dropping step in which an electrolyte medium is dropped onto the electrode substrate within the frame of the sealing material, A paste coating step involves applying a paste containing spherical particles and a sensitizing dye onto a counter electrode substrate. A bonding step is performed to bond the electrode substrate that has undergone the dropping step and the counter electrode substrate that has undergone the paste coating step, using the sealing material as a means of bonding. The process includes a curing step in which the sealing material is cured after the bonding step to form a sealing wall that seals the electrolyte medium in the region between the electrode substrate and the counter electrode substrate, A method for manufacturing a photoelectric conversion element, characterized in that, after the bonding step, the sensitizing dye contained in the paste penetrates into the porous semiconductor layer via the electrolyte medium and is adsorbed, so that the porous semiconductor layer supports the sensitizing dye.

8. A method for manufacturing a photoelectric conversion element according to claim 1, A paste coating step involves applying a paste containing spherical particles onto the porous semiconductor layer of an electrode substrate, which has a porous semiconductor layer before a sensitizing dye is supported on it. A sealing material application process in which a sealing material is applied in a frame shape onto the counter electrode substrate, A dropping step in which an electrolyte medium containing a sensitizing dye is dropped onto the counter electrode substrate within the frame of the sealing material, A bonding step in which the electrode substrate having undergone the paste coating step and the counter electrode substrate having undergone the dropping step are bonded together via the sealing material, The process includes a curing step in which the sealing material is cured after the bonding step to form a sealing wall that seals the electrolyte medium in the region between the electrode substrate and the counter electrode substrate, A method for manufacturing a photoelectric conversion element, characterized in that, after the bonding step, the sensitizing dye contained in the electrolyte medium penetrates into the porous semiconductor layer and is adsorbed, so that the porous semiconductor layer supports the sensitizing dye.

9. A method for manufacturing a photoelectric conversion element according to claim 1, A dye solution immersion step involves immersing an electrode substrate having a porous semiconductor layer before the sensitizing dye is supported in a solution containing the sensitizing dye, thereby supporting the sensitizing dye on the porous semiconductor layer. A paste coating step is performed on the porous semiconductor layer that has undergone the dye solution immersion step, by applying a paste containing spherical particles. A sealing material application process in which a sealing material is applied in a frame shape onto the counter electrode substrate, A dropping step in which an electrolyte medium is dropped onto the counter electrode substrate within the frame of the sealing material, A bonding step in which the electrode substrate having undergone the paste coating step and the counter electrode substrate having undergone the dropping step are bonded together via the sealing material, A method for manufacturing a photoelectric conversion element, comprising a curing step of curing the sealing material after the bonding step to form a sealing wall that seals the electrolyte medium in the region between the electrode substrate and the counter electrode substrate.

10. A method for manufacturing a photoelectric conversion element according to any one of claims 6 to 9, A method for manufacturing a photoelectric conversion element, characterized in that the paste used in the paste coating step contains a steroid compound having a carboxyl group and a nitrogen-containing heterocyclic compound.

11. A method for manufacturing a photoelectric conversion element according to any one of claims 6 to 9, A method for manufacturing a photoelectric conversion element, characterized in that the sealing material used in the sealing material coating step contains spacer particles.

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