Photoelectric conversion element and method for manufacturing the same

Abstract

To provide a photoelectric conversion element comprising a porous semiconductor layer on which a coloring agent is adsorbed uniformly at high concentration, and a method for manufacturing the same.SOLUTION: A porous semiconductor layer is caused to carry a coloring agent by using a paste containing a sensitizing dye. A photoelectric conversion element A manufactured in that way comprises: a first electrode (electrode substrate 10); a second electrode (counter substrate 20) that is a counter electrode to the first electrode; an electrolyte medium 50 that is filled into a region between the first electrode and the second electrode; a sealing wall 60 that seals the electrolyte medium 50 in the region; and a porous semiconductor layer 30 that is provided on a side of the electrolyte medium 50 on the first electrode, and carries the sensitizing dye. A porous organic solid layer 40 is present between the porous semiconductor layer 30 and the second electrode.SELECTED DRAWING: Figure 1

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 that convert sunlight into electricity, solar cells using crystalline silicon substrates and thin-film silicon solar cells are known. Solar cells using crystalline silicon substrates use silicon substrates, and thin-film silicon solar cells use various semiconductor manufacturing gases and equipment, etc., and in both cases, the manufacturing cost tends to increase.

[0003] On the other hand, a dye-sensitized solar cell that applies photoinduced electron transfer of a metal complex has also 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 (hereinafter also simply referred to as a dye) that absorbs incident light such as sunlight and converts light energy into electricity. In a dye-sensitized solar cell, when light is irradiated, electrons that have moved to one electrode pass through an external electric circuit and then are carried to ions in an electrolyte solution via the other opposite electrode and return to the photoelectric conversion layer, whereby electrical energy is extracted.

[0004] As a method for manufacturing a dye-sensitized solar cell, there is a method in which a substrate having a porous semiconductor layer is immersed in a dye solution and left standing for a long time to support (adsorb) the dye on the porous semiconductor layer. However, this type of immersion method has problems such as taking several hours for dye adsorption and a large consumption of the dye solution, resulting in waste. In response to such problems, for example, in Patent Document 1, a process of dropwise applying a dye solution from a nozzle to a substrate having a porous semiconductor layer is performed, and then a solvent removal process of evaporating and removing the solvent from the dye solution on the porous semiconductor layer and a rinsing process of washing away and removing excess dye adhering to the surface of the porous semiconductor layer are performed to support the dye on the porous semiconductor layer.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2013-12404 [Summary of the Invention] [Problems to be Solved by the Invention]

[0006] However, in the dropping method as described in Patent Document 1, there is a problem that unevenness occurs in the adsorption of the dye to the porous semiconductor layer. This will be described with reference to FIG. 14.

[0007] FIG. 14 is a cross-sectional view schematically illustrating a conventional dropping method (dot coating), in which a transparent conductive layer 120 and a porous semiconductor layer 300 are laminated in this order on a transparent substrate 110, and droplets 400 of a dye solution are dropped onto the porous semiconductor layer 300. When the droplets 400 are dropped onto the porous semiconductor layer 300, although the adsorption of the dye starts immediately after dropping, since the molecular size of the dye is large, the penetration of the dye into the porous semiconductor layer 300 first proceeds in the vertical direction (the thickness direction of the porous semiconductor layer 300). Then, the dye penetrates and spreads from the dropped portion to the surroundings (horizontal direction), and the dye is adsorbed. Therefore, when the porous semiconductor layer 300 carrying the dye by the dropping method is viewed from the light-receiving surface side (the lower side in FIG. 14), there is a difference in dye concentration between the portion where the droplets 400 are dropped and the surroundings, and consequently, there is a problem that the photoelectric conversion efficiency and the appearance quality are deteriorated. Further, there is a concern that this problem will be aggravated when the concentration of the dye adsorbed on the porous semiconductor layer 300 is increased.

[0008] The content of the present disclosure has been found in view of such circumstances, and the main object of the present disclosure is to provide a photoelectric conversion element including a porous semiconductor layer in which a dye is adsorbed uniformly at a high concentration and a method for manufacturing the same. [Means for Solving the Problems]

[0009] To solve the above problems, the photoelectric conversion element of the present disclosure includes a first electrode, a second electrode that is an opposite electrode to the first electrode, an electrolyte medium encapsulated in a region between the first electrode and the second electrode, a sealing wall that seals the electrolyte medium within the region, and a porous semiconductor layer provided on the electrolyte medium side of the first electrode and carrying a sensitizing dye. The photoelectric conversion element is characterized in that an organic solid layer that is porous exists between the porous semiconductor layer and the second electrode.

[0010] In the above photoelectric conversion element, the organic solid layer may have a configuration including a steroid compound having a carboxyl group.

[0011] Also, in the above photoelectric conversion element, the average thickness of the organic solid layer is preferably 10 μm or more and 20 μm or less.

[0012] Also, in the above photoelectric conversion element, the organic solid layer preferably contains particles having a length of 1 μm or more in the thickness direction of the organic solid layer.

[0013] Also, in the above photoelectric conversion element, the planar arrangement of the organic solid layer may be a pattern-like arrangement.

[0014] To solve the above problems, the first manufacturing method of the photoelectric conversion element of the present disclosure is as follows. A paste coating step of applying a paste containing a sensitizing dye onto the porous semiconductor layer of a first substrate including the first electrode and the porous semiconductor layer before carrying the sensitizing dye. A sealant coating step of applying a sealant in a frame shape onto a second substrate including the second electrode. A dropping step of dropping an electrolyte medium onto the second electrode within the frame of the sealant. A bonding step of bonding the first substrate that has undergone the paste coating step and the second substrate that has undergone the dropping step via the sealant. A curing step of forming a sealing wall for sealing the electrolyte medium in a region between the first electrode and the second electrode by curing the sealing material after the bonding step is included. After the bonding step, the porous semiconductor layer supports the sensitizing dye by the sensitizing dye contained in the paste penetrating and being adsorbed into the porous semiconductor layer.

[0015] To solve the above problems, a second manufacturing method of the photoelectric conversion element of the present disclosure is as follows. A paste application step of applying a paste containing a sensitizing dye onto the second electrode provided on the second substrate. A sealing material application step of applying a sealing material in a frame shape surrounding the porous semiconductor layer onto a first substrate provided with the first electrode and the porous semiconductor layer before supporting the sensitizing dye. A dropping step of dropping an electrolyte medium onto the first substrate within the frame of the sealing material. A bonding step of bonding the first substrate that has undergone the dropping step and the second substrate that has undergone the paste application step via the sealing material. A curing step of forming a sealing wall for sealing the electrolyte medium in a region between the first electrode and the second electrode by curing the sealing material after the bonding step is included. After the bonding step, the sensitizing dye contained in the paste penetrates and is adsorbed into the porous semiconductor layer through the electrolyte medium, whereby the sensitizing dye is supported by the porous semiconductor layer.

[0016] In the above manufacturing method of the photoelectric conversion element, in the paste application step, the paste containing the sensitizing dye may be applied in a pattern onto the porous semiconductor layer before supporting the sensitizing dye by screen printing.

[0017] Also, in the above manufacturing method of the photoelectric conversion element, 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.

[0018] In the method for manufacturing the above-described photoelectric conversion element, when the amount of substance of the sensitizing dye contained in the paste used in the paste application step is X mol and the amount of substance of the steroid compound is Y mol, the molar ratio Y / X is preferably 10 or more and 100 or less.

Advantages of the Invention

[0019] According to the present disclosure, it is possible to provide a photoelectric conversion element including a porous semiconductor layer in which a dye is adsorbed without unevenness at a high concentration and a method for manufacturing the same.

Brief Description of the Drawings

[0020]

Figure 1

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Figure 14

Embodiments for Carrying Out the Invention

[0021] Hereinafter, an optoelectronic conversion element and a method for manufacturing the same according to embodiments of the present disclosure will be described with reference to the drawings. Note that common reference numerals are assigned to common components in each embodiment to omit redundant descriptions. Further, hereinafter, the “porous semiconductor layer 30 supporting a sensitizing dye” is also simply referred to as the “porous semiconductor layer 30”, the “porous semiconductor layer 30′ before supporting the sensitizing dye” is also simply referred to as the “porous semiconductor layer 30′”, the “organic solid layer 40 that is porous” is also simply referred to as the “organic solid layer 40”, and the “paste 40′ containing a sensitizing dye” is also simply referred to as the “paste 40′”.

[0022] The optoelectronic conversion element according to an embodiment of the present disclosure includes a first electrode, a second electrode serving as a counter electrode to the first electrode, an electrolyte medium encapsulated in a region between the first electrode and the second electrode, a sealing wall for sealing the electrolyte medium in the region, and a porous semiconductor layer provided on the electrolyte medium side of the first electrode and supporting a sensitizing dye.

[0023] Furthermore, in the optoelectronic conversion element according to an embodiment of the present disclosure, an organic solid layer that is porous exists between the porous semiconductor layer and the second electrode. Hereinafter, as a first embodiment, an optoelectronic conversion element in which the organic solid layer is provided on the porous semiconductor layer will be described, and as a second embodiment, an optoelectronic conversion element in which the organic solid layer is provided on a catalyst layer included in the second electrode will be described. Also, as a third embodiment, an optoelectronic conversion element in which the planar arrangement of the organic solid layer is in a pattern will be described.

[0024] In the photoelectric conversion element according to the first to third embodiments, the first electrode is an electrode substrate including at least a transparent conductive layer and a porous semiconductor layer. The porous semiconductor layer carries a sensitizing dye which is a photosensitive dye. This first electrode is also referred to as a photoelectrode. Further, the second electrode is an electrode that functions as a counter electrode to the photoelectrode which is the first electrode. The second electrode is also referred to as a counter electrode, and has at least a counter electrode conductive layer, and may further have a catalyst layer. Further, this counter electrode conductive layer may also serve as a catalyst layer.

[0025] <First Embodiment> FIG. 1 is a cross-sectional view schematically showing a photoelectric conversion element A according to the first embodiment. As shown in FIG. 1, the photoelectric conversion element A includes a pair of substrates (first substrate 11, second substrate 21), an electrolyte medium 50 between these substrates, a transparent conductive layer 12 provided on the electrolyte medium 50 side in the first substrate 11, a porous semiconductor layer 30 carrying a sensitizing dye provided on the electrolyte medium 50 side in the transparent conductive layer 12, an organic solid layer 40 which is porous and provided on the opposite side of the transparent conductive layer 12 in the porous semiconductor layer 30, and a counter electrode conductive layer 22 provided on the electrolyte medium 50 side in the second substrate 21.

[0026] FIG. 2 is a cross-sectional view schematically showing an enlarged portion of the organic solid layer 40 included in the photoelectric conversion element A of FIG. 1. As shown in FIG. 2, the organic solid layer 40 has a structure including an organic solid base material 41 and void portions 42, that is, it is a layer composed of a porous organic solid base material 41 with a large number of pores.

[0027] The organic solid layer 40 is a residue of some components of the "paste 40' containing a dye" used to carry the dye on the porous semiconductor layer 30 in the manufacture of the photoelectric conversion element A. Therefore, the manufacturing method of the photoelectric conversion element A will be described with reference to FIGS. 3 to 6.

[0028] FIG. 3 is a process diagram showing the manufacturing method of the photoelectric conversion element A according to the first embodiment, and FIGS. 4 to 6 are cross-sectional views schematically showing the manufacturing process of the photoelectric conversion element A.

[0029] As shown in FIG. 3, the method for manufacturing a photoelectric conversion element A according to the first embodiment includes a paste coating step S12 of applying a paste 40' containing a sensitizing dye onto a porous semiconductor layer 30' of an electrode substrate 10 having the porous semiconductor layer 30' before carrying the sensitizing dye, a drying step S13 of drying the applied paste 40', a sealant coating step S15 of applying a sealant in a frame shape onto a counter substrate 20, a dropping step S16 of dropping an electrolyte medium 50 onto the counter substrate 20 within the frame of the sealant, a bonding step S17 of bonding the electrode substrate 10 that has undergone the drying step S13 and the counter substrate 20 that has undergone the dropping step S16 via the sealant, and a curing step S18 of forming a sealing wall 60 that seals the electrolyte medium 50 in the region between the electrode substrate 10 and the counter substrate 20 by curing the sealant after the bonding step S17. Among these steps, for those where the order can be interchanged, the order can be interchanged or they can be performed in parallel.

[0030] Step S11 shown in FIG. 3 is a step of preparing an electrode substrate 10 having a porous semiconductor layer 30' before carrying the sensitizing dye. The electrode substrate 10 including a first substrate 11 has a transparent conductive layer 12 provided on this first substrate 11. The first substrate 11 is a non-conductive sheet-like member having translucency (light transmissibility) that enables light irradiated on the light receiving surface to reach, and is, for example, a transparent substrate formed of glass, a transparent resin, silicon, or the like.

[0031] The transparent conductive layer 12 is made of a material having translucency similar to that of the first substrate 11 and has conductivity. As the material of the transparent conductive layer 12, for example, 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 transparent conductive layer 12 is preferably, for example, 0.02 μm or more and 5.0 μm or less.

[0032] The porous semiconductor layer 30' has a semiconductor material, and its shape can be various shapes such as bulk, particulate, and layer shape having a large number of micropores, etc., but it is preferably a porous structure capable of supporting a dye. As the semiconductor material constituting the porous semiconductor layer 30, for example, 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 can be used.

[0033] Among these, it is preferable to use titanium oxide for the porous semiconductor layer 30'. As the titanium oxide, for example, various titanium oxides such as anatase type titanium oxide, rutile type titanium oxide, amorphous titanium oxide, metatitanic acid, and orthotitanic acid, titanium hydroxide or hydrous titanium hydroxide, etc. can be used alone or in combination. Further, fine particles of titanium oxide can be used as the material of the porous semiconductor layer 30'.

[0034] The crystal system of the semiconductor may be either single crystal or polycrystal, but from the viewpoints of stability, ease of crystal growth, and manufacturing cost, etc., it is preferably polycrystal, and it is preferable to use polycrystalline semiconductor fine particles on the nano-scale or micro-scale. The fine particles of titanium oxide can be produced, for example, by a liquid phase method such as a hydrothermal synthesis method or a sulfuric acid method, or a gas phase method.

[0035] As the semiconductor fine particles, those obtained by mixing fine particles of two or more particle diameters composed of the same or different semiconductor compounds may be used. The semiconductor fine particles with a large particle diameter contribute to the improvement of the light trapping rate by scattering the incident light, and the semiconductor fine particles with a small particle diameter can increase the adsorption amount of the dye by increasing the adsorption points. The average thickness of the porous semiconductor layer 30' is preferably, for example, 0.1 μm or more and 100.0 μm or less.

[0036] FIG. 4 is a cross-sectional view schematically showing a state in which a paste 40' containing a sensitizing dye is applied onto a porous semiconductor layer 30' before carrying the sensitizing dye in the paste application step S12. As a method for applying the paste 40', a screen printing method is preferable. In the paste application step S12 in the embodiment of the present disclosure, as compared with the conventional dropping method in which the penetration and adsorption of the dye into the porous semiconductor layer start immediately when the dye solution is dropped, the penetration and adsorption of the dye into the porous semiconductor layer 30' do not occur immediately when the paste 40' is printed (applied). Therefore, it is possible to adsorb the dye uniformly onto the porous semiconductor layer 30' in the subsequent process.

[0037] The paste 40' is a mixture containing a sensitizing dye, a component 41' (hereinafter also simply referred to as "poorly soluble component 41'") that is poorly soluble or insoluble in the electrolyte medium 50, a component 42' (hereinafter also simply referred to as "easily soluble component 42'") that is easily soluble in the electrolyte medium 50, and a solvent. The poorly soluble component 41' only needs to have a degree of poor solubility such that a part thereof remains as the organic solid substrate 41 in FIG. 2, and the easily soluble component 42' only needs to have a degree of easy solubility such that the void portion 42 in FIG. 2 is formed.

[0038] Since the paste 40' is composed of such components, the poorly soluble component 41' remains as the organic solid substrate 41 in FIG. 2 without at least a part thereof being dissolved in the electrolyte medium 50. Further, the easily soluble component 42' is dissolved in the electrolyte medium 50 to become a part of the carrier transport material, and the void portion 42 in FIG. 2 is formed in the region where the easily soluble component 42' existed before dissolution.

[0039] The type of the solvent used for the paste 40' is not particularly limited, but the same solvent as that exemplified later as the solvent of the electrolyte medium 50 (electrolyte solution) can be used.

[0040] 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 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, quinoneimine 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.

[0041] The metal complex dye is formed by the coordination bond of a metal to a molecule. The molecule is, for example, a porphyrin dye, a phthalocyanine dye, a naphthalocyanine dye, a bipyridine dye, or a terpyridine dye. The metal can be, for example, at least one selected from the group including 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. As the metal complex dye, it is preferable to use a phthalocyanine dye, a bipyridine dye, or a terpyridine dye coordinated with a metal, and it is particularly preferable to use a ruthenium-bipyridine complex dye.

[0042] In an embodiment of the present 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 the readily soluble component 42' are not limited to these, but the steroid compound having a carboxyl group has been used as an aggregation inhibitor or the like in a dye solution in a conventional method for manufacturing a photoelectric conversion element (dye-sensitized solar cell), and the nitrogen-containing heterocyclic compound has been used as an additive or the like to an electrolyte medium (electrolyte solution) in a conventional photoelectric conversion element. Therefore, the long-term stability and safety when used as a material for a photoelectric conversion element have been confirmed. Therefore, they are each suitable for use as the poorly soluble component 41' and the readily soluble component 42'.

[0043] Examples of the steroid compound having a carboxyl group in the paste 40' include cholic acid, lithocholic acid, deoxycholic acid, chenodeoxycholic acid, and ursodeoxycholic acid. These compounds may be used alone or in combination of two or more kinds.

[0044] As the nitrogen-containing heterocyclic compound in the paste 40', for example, those used in the art as an additive to the electrolyte medium 50 can be used. Examples of such nitrogen-containing heterocyclic compounds include pyridine, pyrazole, imidazole, pyrrole, purine, and their derivatives.

[0045] Among these, it is particularly preferable to use pyrazole and pyrazole derivatives. Examples of pyrazole and pyrazole derivatives include 1-methylpyrazole, 3-methylpyrazole, 3,5-dimethylpyrazole, 3,5-diisopropylpyrazole, 3-amino-5-methylpyrazole, 4-iodo-3,5-dimethylpyrazole, and the like.

[0046] Examples of the amine of the heterocyclic aromatic compound include, for example, 4-tert-butylpyridine. Examples of the salt of the amine of the heterocyclic aromatic compound include imidazole salts such as dimethylpropylimidazolium iodide (DMPII), methylpropylimidazolium iodide (MPII), ethylmethylimidazolium iodide (EMII), ethylimidazolium iodide (EII), and hexylmethylimidazolium iodide (HMII).

[0047] These compounds exemplified as the nitrogen-containing heterocyclic compounds may be used alone or in combination of two or more.

[0048] FIG. 13 is a photograph taken with a scanning electron microscope (SEM) of a cross-section of the porous semiconductor layer 30' after applying the paste 40' in the paste application step S12. D shown in FIG. 13 corresponds to the thickness of the paste 40', in other words, corresponds to the thickness of the organic solid layer 40 of the photoelectric conversion element A shown in FIG. 1.

[0049] The average thickness of the paste 40' (organic solid layer 40) is preferably 20 μm or less, and more preferably 10 μm or more and 20 μm or less. When the average thickness is equal to or greater than the above lower limit, it has a sufficient thickness to exhibit the function of supporting the dye on the porous semiconductor layer 30'. On the other hand, when the average thickness exceeds the above upper limit, the diffusion of ions between the positive electrode (second electrode) and the negative electrode (first electrode) is inhibited, so there is a risk that almost no electrons will flow under high illuminance.

[0050] As observed by SEM as shown in FIG. 13, the paste 40' is composed of a large number of particles, and d shown in FIG. 13 corresponds to the length of the particles in the thickness direction of the paste 40'. That is, the organic solid layer 40 of the photoelectric conversion element A shown in FIG. 1 is also composed of a large number of particles, and d corresponds to the length of the particles in the thickness direction of the organic solid layer 40. The paste 40' (organic solid layer 40) preferably contains particles having a length d of 1 μm or more in the thickness direction.

[0051] Regarding the composition of the paste 40', when the amount of substance of the sensitizing dye in the paste 40' is X mol and the amount of substance of the steroid compound having a carboxyl group is Y mol, it is preferable that the molar ratio Y / X is 10 or more and 100 or less. By using the paste 40' having such a composition, the sensitizing dye can be efficiently infiltrated into the porous semiconductor layer 30'.

[0052] In the drying step S13, the paste 40' applied in the paste coating step S12 is dried. The drying method is not particularly limited, and examples thereof include vacuum drying or heat drying of the electrode substrate 10.

[0053] Next, the steps related to the counter substrate 20 (second electrode) side will be described. The step S14 shown in FIG. 3 is a step of preparing the counter substrate 20. The counter substrate 20 includes a second substrate 21, which is a translucent non-conductive sheet-like member, and a counter electrode conductive layer 22, which has translucency and conductivity. The second substrate 21 and the counter electrode conductive layer 22 of the counter substrate 20 can have the same configuration as the first substrate 11 and the transparent conductive layer 12 that constitute the electrode substrate 10.

[0054] A catalyst layer 23 is further laminated on the counter electrode conductive layer 22. The catalyst layer 23 contains particles having a catalytic action. The particles having a catalytic action are not particularly limited and can be selected from metal particles, carbon particles, conductive polymers, etc., and a plurality of these types may be included. The lamination method of the catalyst layer 23 is not particularly limited and can be performed by a screen printing method, a vapor deposition method, a sputtering method, etc.

[0055] In the sealant application step S15, a sealant is applied in a frame shape on the counter substrate 20. The sealant cured in the subsequent curing step S18 is the sealing wall 60 provided in the photoelectric conversion element A of FIG. 1. The sealant may be any material that can seal the electrolyte medium 50, and a photocurable resin, a thermosetting resin, etc. can be used. For example, when an ultraviolet curable resin is used, the sealant is cured by irradiating ultraviolet rays in the curing step S18.

[0056] FIG. 5 is a cross-sectional view schematically showing a state in which the electrolyte medium 50 is dropped onto the counter substrate 20 in the dropping step S16, and FIG. 6 is a cross-sectional view schematically showing a 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 undergone the drying step S13 and the counter substrate 20 that has undergone the dropping step S17 in the bonding step S17. In FIGS. 5 and 6, although the sealing material applied in the sealing material application step S15 is not shown, the sealing material is applied at a position corresponding to the sealing wall 60 in the photoelectric conversion element A of FIG. 1.

[0057] In the dropping step S16, the electrolyte medium 50 is dropped onto the counter substrate 20 within the frame of the sealing material applied in the sealing material application step S15. The electrolyte medium 50 is typically an electrolytic solution (electrolyte solution). The electrolytic solution is a liquid containing a redox couple, and can be a liquid composed of a redox couple and a solvent capable of dissolving it, a liquid composed of a redox couple and a molten salt capable of dissolving it, a liquid composed of a redox couple and a solvent and a molten salt capable of dissolving it, etc.

[0058] Examples of the redox couple include combinations of metal iodides such as LiI, NaI, KI, CaI2 and iodine, combinations of metal bromides such as LiBr, NaBr, KBr, CaBr2 and bromine, combinations of salts containing iodide ions and iodine, and combinations of salts containing bromide ions and bromine. Among these, combinations of LiI and iodine, and combinations of salts containing iodide ions and iodine are preferred. These redox couples can be used in combination of two or more.

[0059] The solvent of the electrolytic solution is preferably a solvent containing at least one selected from the group consisting of carbonate compounds such as propylene carbonate, nitrile compounds such as acetonitrile, alcohols such as ethanol, cyclic esters such as γ-butyrolactone, ε-caprolactone, cyclic amides such as 1-methyl-2-pyrrolidone, water, and aprotic polar substances. It is more preferable to use cyclic esters or cyclic amides alone or in combination as the solvent.

[0060] The electrolyte medium 50 may contain additives such as nitrogen-containing heterocyclic compounds as required. Examples of the nitrogen-containing heterocyclic compounds include pyridine, pyrazole, imidazole, pyrrole, purine, and their derivatives.

[0061] Among these, it is particularly preferable to use pyrazole and pyrazole derivatives. Examples of pyrazole and pyrazole derivatives include 1-methylpyrazole, 3-methylpyrazole, 3,5-dimethylpyrazole, 3,5-diisopropylpyrazole, 3-amino-5-methylpyrazole, 4-iodo-3,5-dimethylpyrazole, and the like.

[0062] Examples of the amine of the heterocyclic aromatic compound include 4-tert-butylpyridine. Examples of the salt of the amine of the heterocyclic aromatic compound include imidazole salts such as dimethylpropylimidazole iodide (DMPII), methylpropylimidazole iodide (MPII), ethylmethylimidazole iodide (EMII), ethylimidazole iodide (EII), hexylmethylimidazole iodide (HMII), and the like.

[0063] These compounds exemplified as additives may be used alone or in combination of two or more.

[0064] Next, in the bonding step S17, the electrode substrate 10 that has undergone the drying step S13 and the counter substrate 20 that has undergone the dropping step S16 are bonded together via a sealing material. Further, in the curing step S18, the sealing material is cured to form a sealing wall 60. Thereby, as shown in FIG. 1, the electrolyte medium 50 is sealed in the region between the electrode substrate 10 and the counter substrate 20.

[0065] As shown in FIG. 6, when the electrode substrate 10 and the counter 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 readily soluble component 42' contained in the paste 40' dissolves 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 the penetration of the sensitizing dye shown in FIGS. 5 and 6 is schematic, and actually, the penetration of the sensitizing dye into the porous semiconductor layer 30' may progress even at the stage of the drying step S13 of drying the applied paste 40'.

[0066] The penetrated sensitizing dye is adsorbed on the porous semiconductor layer 30', and the porous semiconductor layer 30 carrying the sensitizing dye is formed. Due to such a mechanism, after the bonding step S17, the sensitizing dye diffuses uniformly and is adsorbed on the porous semiconductor layer 30', so that a photoelectric conversion element including a porous semiconductor layer in which the dye is adsorbed at a high concentration without unevenness can be realized.

[0067] <Second Embodiment> FIG. 7 is a process diagram showing a method for manufacturing a photoelectric conversion element according to the second embodiment, and FIGS. 8 and 9 are cross-sectional views schematically showing the manufacturing process of the photoelectric conversion element.

[0068] As shown in FIG. 7, the method for manufacturing a photoelectric conversion element according to the second embodiment includes a sealant application step S22 of applying a sealant in a frame shape on the electrode substrate 10, a dropping step S23 of dropping an electrolyte medium 50 onto the electrode substrate 10 within the frame of the sealant, a paste application step S25 of applying a paste 40' containing a sensitizing dye on the counter substrate 20, a drying step S26 of drying the applied paste 40', a bonding step S27 of bonding the electrode substrate 10 that has undergone the dropping step S23 and the counter substrate 20 that has undergone the drying step S26 via the sealant, and a curing step S28 of curing the sealant 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 substrate 20. Steps S21 and S24 shown in FIG. 7 are steps of preparing both substrates, and are the same as steps S11 and S14 according to the first embodiment, respectively. Among these steps, for those whose order can be interchanged, the order can be interchanged or they can be performed in parallel. Among these steps, the differences from the first embodiment will be described.

[0069] In the sealant application step S22, a sealant is applied in a frame shape on the transparent conductive layer 12 of the electrode substrate 10 so as to surround the porous semiconductor layer 30'. Thereafter, in the dropping step S23, the electrolyte medium 50 is dropped onto the electrode substrate 10 within the frame of the sealant.

[0070] FIG. 8 is a cross-sectional view schematically showing a 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 substrate 20 in the paste application step S25. FIG. 9 is a cross-sectional view schematically showing a process in which the paste 40' is immersed in the electrolyte medium 50 by bonding the electrode substrate 10 that has undergone the dropping step S23 and the counter substrate 20 that has undergone the drying step S26 in the bonding step S27.

[0071] Thus, in the method for manufacturing a photoelectric conversion element according to the second embodiment, the paste 40' is applied to the counter substrate 20 side. Therefore, the photoelectric conversion element according to the second embodiment is a photoelectric conversion element having a structure in which the organic solid layer 40 is provided on the counter substrate 20 (on the electrolyte medium 50 side of the counter substrate 20).

[0072] As shown in FIG. 9, in the bonding step S27, when the electrode substrate 10 and the counter substrate 20 are bonded together and the paste 40' and the porous semiconductor layer 30' are immersed in the electrolyte medium 50, the readily soluble component 42' contained in the paste 40' dissolves in the electrolyte medium 50, and the sensitizing dye contained in the paste 40' also moves into the electrolyte medium 50'. Further, the sensitizing dye penetrates into the porous semiconductor layer 30', and the penetrated sensitizing dye is adsorbed on the porous semiconductor layer 30', forming a porous semiconductor layer 30 supporting the sensitizing dye. By such a mechanism, after the bonding step S27, the sensitizing dye diffuses uniformly and is adsorbed on the porous semiconductor layer 30', so that a photoelectric conversion element including a porous semiconductor layer having the dye adsorbed at a high concentration without unevenness can be realized.

[0073] <Third Embodiment> In the method for manufacturing a photoelectric conversion element according to the third embodiment, in the paste application step S12 according to the first embodiment, the paste 40' containing the sensitizing dye is printed (applied) in a pattern on the porous semiconductor layer 30' by screen printing. In other words, the planar arrangement of the organic solid layer 40 in the photoelectric conversion element of the third embodiment is a pattern arrangement.

[0074] FIG. 10 is a plan view illustrating the printing pattern (application pattern) of the paste 40' in the third embodiment. FIG. 10(a) is solid printing in which the printing target is filled without gaps, and printing is performed in this way in the first embodiment. On the other hand, in the photoelectric conversion element according to the third embodiment printed in a stripe pattern as shown in FIG. 10(b) or a lattice pattern as shown in FIG. 10(c), there are portions where the paste 40' is not printed at regular intervals on the printing target.

[0075] FIG. 11 is a cross-sectional view schematically showing a step of a method for manufacturing a photoelectric conversion element according to a third embodiment, and FIG. 12 is a cross-sectional view schematically showing a subsequent step of FIG. 11. FIGS. 11 and 12 are the same as FIGS. 5 and 6 according to the first embodiment, respectively, except that the paste 40' is printed in a pattern.

[0076] As shown in FIG. 12, in the third embodiment, in the bonding step S17, when the electrode substrate 10 and the counter substrate 20 are bonded together and the paste 40' is immersed in the electrolyte medium 50, the electrolyte medium 50 also enters the gaps between the pastes 40' printed in a pattern (regions where the paste 40' is not printed on the porous semiconductor layer 30'), increasing the contact area between the paste 40' and the electrolyte medium 50. Therefore, the diffusion rate of the sensitizing dye contained in the paste 40' increases, and consequently, the adsorption rate of the sensitizing dye to the porous semiconductor layer 30' increases.

[0077] Also, the organic solid layer 40 as a residue of the paste 40' somewhat inhibits the diffusion of ions between the positive electrode (second electrode) and the negative electrode (first electrode). However, in the third embodiment, the planar arrangement of the organic solid layer 40 is a pattern arrangement, reducing this inhibition. Therefore, the photoelectric conversion element according to the third embodiment exhibits a high current value even under high illuminance.

[0078] In the method for manufacturing a photoelectric conversion element according to the third embodiment, compared with the first embodiment, since the printing area (coating area) of the paste 40' on the porous semiconductor layer 30' decreases, it is preferable to use a paste 40' with a higher concentration of the sensitizing dye than in the first embodiment.

[0079] It should be noted that all the embodiments disclosed this time are illustrative in all respects and do not serve as a basis for a restrictive interpretation. Therefore, the technical scope of the present disclosure is not interpreted only by the above-described embodiments, but is defined based on the description in the claims. Also, all modifications within the meaning and scope equivalent to the claims are included.

[0080] For example, as a third embodiment, an embodiment in which the paste 40' is printed in a pattern in the paste application step S12 according to the first embodiment is illustrated. However, the paste 40' may be printed in a pattern in the paste application step S25 according to the second embodiment.

Explanation of Signs

[0081] 10 Electrode substrate 11 First substrate 12 Transparent conductive layer 20 Counter substrate 21 Second substrate 22 Counter electrode conductive layer 23 Catalyst layer 30 Porous semiconductor layer carrying a sensitizing dye 30' Porous semiconductor layer before carrying a sensitizing dye 40 Porous organic solid layer 41 Organic solid base material 42 Void portion 40' Paste containing a sensitizing dye 41' Insoluble component 42' Soluble component 50 Electrolyte medium 60 Sealing wall A Photoelectric conversion element D Thickness of the organic solid layer 40 (paste 40') d Length of particles in the thickness direction of the organic solid layer 40 (paste 40')

Claims

1. a first electrode, a second electrode that is the counter electrode of the first electrode, an electrolyte medium encapsulated in a region between the first electrode and the second electrode, a sealing wall that seals the electrolyte medium within the region, a porous semiconductor layer provided on the electrolyte medium side of the first electrode and carrying a sensitizing dye, and a photoelectric conversion element comprising: A photoelectric conversion element, characterized in that an organic solid layer that is porous exists between the porous semiconductor layer and the second electrode.

2. The photoelectric conversion element according to claim 1, wherein the organic solid layer contains a steroid compound having a carboxyl group.

3. The photoelectric conversion element according to claim 1 or claim 2, wherein an average thickness of the organic solid layer is 10 μm or more and 20 μm or less.

4. The photoelectric conversion element according to claim 1 or claim 2, wherein the organic solid layer contains particles having a length of 1 μm or more in the thickness direction of the organic solid layer.

5. The photoelectric conversion element according to claim 1 or claim 2, wherein a planar arrangement of the organic solid layer is a pattern-like arrangement.

6. A method for manufacturing the photoelectric conversion element according to claim 1, a paste application step of applying a paste containing a sensitizing dye onto the porous semiconductor layer of a first substrate including the first electrode and the porous semiconductor layer before carrying the sensitizing dye, a sealing material application step of applying a sealing material in a frame shape onto a second substrate including the second electrode, A dropping step of dropping an electrolyte medium onto the second electrode within the frame of the sealing material; A bonding step of bonding the first substrate that has undergone the paste coating step and the second substrate that has undergone the dropping step via the sealing material; A curing step of forming a sealing wall that seals the electrolyte medium in the region between the first electrode and the second electrode by curing the sealing material after the bonding step, and includes; A method for manufacturing a photoelectric conversion element, characterized in that after the bonding step, a sensitizing dye contained in the paste penetrates and is adsorbed onto 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 6, wherein In the paste coating step, a paste containing a sensitizing dye is pattern-coated onto the porous semiconductor layer before supporting the sensitizing dye by screen printing. A method for manufacturing a photoelectric conversion element characterized by this.

8. A method for manufacturing a photoelectric conversion element according to claim 1, wherein A paste coating step of applying a paste containing a sensitizing dye onto the second electrode provided on the second substrate; A sealing material coating step of applying a sealing material in a frame shape surrounding the porous semiconductor layer onto a first substrate including the first electrode and the porous semiconductor layer before supporting the sensitizing dye; A dropping step of dropping an electrolyte medium onto the first substrate within the frame of the sealing material; A bonding step of bonding the first substrate that has undergone the dropping step and the second substrate that has undergone the paste coating step via the sealing material; A curing step of forming a sealing wall that seals the electrolyte medium in the region between the first electrode and the second electrode by curing the sealing material after the bonding step, and includes; A method for manufacturing a photoelectric conversion element, characterized in that after the bonding step, a sensitizing dye contained in the paste penetrates and is adsorbed onto the porous semiconductor layer through the electrolyte medium, so that the sensitizing dye is supported by the porous semiconductor layer. Claim 9 A method for manufacturing a photoelectric conversion element according to any one of Claims 6 to 8, wherein the paste used in the paste application step contains a steroid compound having a carboxyl group and a nitrogen-containing heterocyclic compound. A method for manufacturing a photoelectric conversion element characterized by this. Claim 10 A method for manufacturing a photoelectric conversion element according to Claim 9, wherein when the amount of substance of the sensitizing dye contained in the paste used in the paste application step is X mol and the amount of substance of the steroid compound is Y mol, the molar ratio Y / X is 10 or more and 100 or less. A method for manufacturing a photoelectric conversion element characterized by this.

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