WO2014057942A1 - Photoelectric conversion element and process for producing same, and photoelectric conversion module - Google Patents

Abstract

A photoelectric conversion element which comprises a supporting substrate (1) and, disposed thereon in the following order, a conductive layer (2), a photoelectric conversion layer (3), and a counter electrode (12) and in which a carrier transport material has been packed at least in the space between the photoelectric conversion layer (3) and the counter electrode (12). The photoelectric conversion layer (3) has been configured by using a solution for colorant adsorption having a water content of 600 ppm or higher to adsorb the colorant onto a porous semiconductor layer constituted of a semiconductor material. The adsorption amount of the colorant in the photoelectric conversion layer (3) is 3.5×10^-8 mol/cm² or more.

Description

PHOTOELECTRIC CONVERSION ELEMENT, ITS MANUFACTURING METHOD, AND PHOTOELECTRIC CONVERSION MODULE

The present invention relates to a photoelectric conversion element, a manufacturing method thereof, and a photoelectric conversion module.

As an alternative energy source to fossil fuels, solar cells that can convert solar energy into electrical energy are attracting attention. Currently, solar cells using crystalline silicon substrates, thin-film silicon solar cells, and the like have been put into practical use. However, the former solar cell has a problem that the manufacturing cost of the silicon substrate is high. The latter thin film silicon solar cell has a problem that the manufacturing cost is high because it is manufactured using various semiconductor manufacturing gases and complicated apparatuses. Although efforts have been made to reduce the cost per power generation output by increasing the efficiency of photoelectric conversion in any solar cell, this problem has not yet been solved.

As a new type of solar cell, a wet solar cell using photoinduced electron transfer in a metal complex has been proposed (for example, Patent Document 1 (Japanese Patent Laid-Open No. 1-220380)). The wet solar cell described in Patent Document 1 is manufactured according to the following method. Electrodes are formed on the surfaces of the two glass substrates, the two glass substrates are arranged so that the formed electrodes are inside, and the photoelectric conversion layer and the electrolytic solution are sandwiched between the two glass substrates. The photoelectric conversion layer is a semiconductor layer having an absorption spectrum in the visible light region by adsorbing a photosensitizing dye to a metal oxide such as titanium oxide. Such a wet solar cell is also called a dye-sensitized solar cell.

When light enters such a wet solar cell, electrons are generated in the photoelectric conversion layer, and the electrons generated in the photoelectric conversion layer reach one electrode through the photoelectric conversion layer. The electrons that have reached one electrode move to the other electrode through an external electric circuit that connects the electrodes, and are supplied to the electrolyte. Electrons supplied to the electrolytic solution are carried by ions in the electrolytic solution and return to the photoelectric conversion layer. Electric energy can be taken out by such a series of electron flows.

In general, when moisture enters a wet solar cell, desorption of the dye occurs, and as a result, the wet solar cell may be deteriorated. Patent Document 2 (Japanese Patent Application Laid-Open No. 2012-79606) discloses a powder hygroscopic agent by providing a hygroscopic porous film in a region between electrodes and filled with an electrolytic solution, or in place of the hygroscopic porous film. It is described that by using an electrolytic solution in which is dispersed, it is possible to prevent deterioration of a wet solar cell due to intrusion of moisture.

Japanese Patent Laid-Open No. 1-220380 JP 2012-79606 A

For the purpose of suppressing moisture intrusion into the wet solar cell, it is conceivable to use a dehydrated solvent as a solvent for dissolving the dye in the step of adsorbing the dye on the porous semiconductor layer. However, in this case, there is a problem that it is difficult to manufacture a wet solar cell excellent in photoelectric conversion efficiency.

This invention is made | formed in view of this point, The place made into the objective provides the photoelectric conversion element which was able to suppress the penetration | invasion of the water | moisture content to a photoelectric conversion element, and was excellent in photoelectric conversion efficiency, and its manufacturing method. That is. Moreover, it is providing the photoelectric conversion module provided with such a photoelectric conversion element.

In the photoelectric conversion element of the present invention, the conductive layer, the photoelectric conversion layer, and the counter electrode are sequentially provided on the support substrate, and the carrier transport material is filled at least between the photoelectric conversion layer and the counter electrode. The photoelectric conversion layer is configured such that a dye is adsorbed to a porous semiconductor layer made of a semiconductor material using a dye adsorption solution containing a water content of 600 ppm or more. The adsorption amount of the dye in the photoelectric conversion layer is 3.5 × 10 ⁻⁸ mol / cm ² or more.

The dye is preferably a metal complex having a terpyridyl group. The solvent contained in the dye adsorption solution is preferably an organic solvent, and more preferably a mixed solvent containing one or more nitrile compounds and one or more alcohols.

The porous semiconductor layer preferably includes at least a layer made of a semiconductor material having an average particle diameter of 10 nm or more and 30 nm or less, and the pore diameter of the porous semiconductor layer is preferably 15 nm or more. The semiconductor material is preferably made of a metal oxide, and the metal oxide preferably contains at least titanium oxide.

The method for producing a photoelectric conversion element includes at least a step of preparing a dye adsorption solution in which a dye is dissolved, and a step of adsorbing the dye contained in the dye adsorption solution to the porous semiconductor layer. The prepared dye adsorption solution contains a water content of 600 ppm or more. The amount of the dye adsorbed on the porous semiconductor layer is 3.5 × 10 ⁻⁸ mol / cm ² or more. The step of preparing the dye adsorption solution preferably includes a step of dissolving the dye in a mixed solvent containing one or more nitrile compounds and one or more alcohols.

In the photoelectric conversion module of the present invention, two or more photoelectric conversion elements are connected in series. At least one of the two or more photoelectric conversion elements is the photoelectric conversion element of the present invention. Among the adjacent photoelectric conversion elements, the counter electrode conductive layer of one photoelectric conversion element and the conductive layer of the other photoelectric conversion element are electrically connected.

In the present invention, it is possible to provide a photoelectric conversion element with suppressed moisture intrusion and excellent photoelectric conversion efficiency, and to provide a photoelectric conversion module with suppressed moisture intrusion and excellent photoelectric conversion efficiency.

It is sectional drawing which shows an example of a structure of the photoelectric conversion element of this invention. It is a flowchart which shows an example of the manufacturing method of the photoelectric conversion element of this invention. It is a graph which shows the relationship between the moisture content of the solution for pigment | dye adsorption, and photoelectric conversion efficiency. It is a graph which shows the relationship between the moisture content of the solution for pigment | dye adsorption, and the adsorption amount of the pigment | dye in a photoelectric converting layer. It is sectional drawing which shows an example of a structure of the photoelectric conversion module of this invention.

Hereinafter, the photoelectric conversion element, the manufacturing method thereof, and the photoelectric conversion module of the present invention will be described with reference to the drawings. In the drawings of the present invention, the same reference numerals represent the same or corresponding parts. In addition, dimensional relationships such as length, width, thickness, and depth are changed as appropriate for clarity and simplification of the drawings, and do not represent actual dimensional relationships.

In the following embodiments, an example of the photoelectric conversion element of the present invention is shown, and various embodiments can be implemented within the scope of the present invention.

[Configuration of photoelectric conversion element]
FIG. 1 is a cross-sectional view showing an example of the configuration of the photoelectric conversion element of the present invention. In the photoelectric conversion element shown in FIG. 1, a conductive layer 2, a photoelectric conversion layer 3, and a counter electrode 12 are sequentially provided on a support substrate 1, and a carrier transport material is filled between the photoelectric conversion layer 3 and the counter electrode 12. Thus, the charge transport layer 10 is formed. In the counter electrode 12, the counter electrode conductive layer 7 and the catalyst layer 6 are preferably formed on the cover body 8 in order, and the catalyst layer 6 is preferably opposed to the photoelectric conversion layer 3. The photoelectric conversion layer 3 and the charge transport layer 10 are preferably sealed with a sealing portion 9. Hereinafter, each component in the photoelectric conversion element shown in FIG. 1 will be described.

<Support substrate>
The support substrate 1 constitutes at least a part of the light receiving surface of the photoelectric conversion element shown in FIG. Therefore, it is preferable that the part used as the light-receiving surface of a photoelectric conversion element among the support substrates 1 consists of a material which has a light transmittance. The light-transmitting material is at least a material that substantially transmits light having a wavelength that has an effective sensitivity to a dye described later (the light transmittance is, for example, 80% or more, preferably 90% or more). It is not always necessary to have transparency to light in all wavelength regions.

The support substrate 1 may be a glass substrate made of, for example, soda lime float glass, fused quartz glass, or crystal quartz glass, or may be a heat resistant resin substrate such as a flexible film. Examples of the flexible film (hereinafter referred to as “film”) include tetraacetyl cellulose (TAC), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polycarbonate (PC), polyarylate (PA), and polyether. A film made of imide (PEI), phenoxy resin, polytetrafluoroethylene (PTFE), or the like can be used.

When another layer is formed on the support substrate 1 with heating, for example, when the conductive layer 2 is formed on the support substrate 1 with heating at about 250 ° C., the support substrate 1 is made of polytetrafluoroethylene. It is preferable to use a film. Since the film made of polytetrafluoroethylene has a heat resistance of 250 ° C. or higher, thermal damage to the support substrate 1 can be suppressed even if the support substrate 1 is heated to about 250 ° C.

The thickness of the support substrate 1 is not particularly limited, but is preferably 0.2 mm or more and 5 mm or less. If the thickness of the support substrate 1 is 0.2 mm or more, the support substrate 1 tends to exhibit a function as a support substrate. If the thickness of the support substrate 1 is 5 mm or less, a decrease in the amount of light transmitted through the support substrate 1 is prevented, so that a decrease in photoelectric conversion efficiency of the photoelectric conversion element tends to be prevented.

The support substrate 1 can be used when the completed photoelectric conversion element is attached to another structure. In other words, the peripheral portion of the support substrate 1 made of a glass substrate or the like can be easily attached to another support substrate using a metal processed part and a screw.

<Conductive layer>
The conductive layer 2 constitutes at least a part of the light receiving surface of the photoelectric conversion element. Therefore, it is preferable that the part used as the light-receiving surface of a photoelectric conversion element among the conductive layers 2 consists of a material which has a light transmittance and electroconductivity. However, like the support substrate 1, the conductive layer 2 is a material that substantially transmits light having a wavelength that has an effective sensitivity to at least a dye described later (the light transmittance is, for example, 80% or more, preferably 90%). And the like, and it is not always necessary to have transparency to light in all wavelength regions.

Examples of the light-transmitting material used for the conductive layer 2 include indium tin composite oxide (ITO), fluorine-doped tin oxide (FTO), and zinc oxide (ZnO).

The thickness of the conductive layer 2 is not particularly limited, but is preferably 0.02 μm or more and 5 μm or less. If the thickness of the conductive layer 2 is 0.02 μm or more, since the resistance of the conductive layer 2 is reduced, the amount of current that can be taken out of the photoelectric conversion element increases. Therefore, the photoelectric conversion efficiency of the photoelectric conversion element tends to be improved. If the thickness of the conductive layer 2 is 5 μm or less, a decrease in the amount of light transmitted through the conductive layer 2 is prevented, so that the photoelectric conversion efficiency of the photoelectric conversion element tends to be maintained.

The surface resistivity (sheet resistance) of the conductive layer 2 is not particularly limited, but is preferably 40 Ω / sq or less. If the surface resistivity of the conductive layer 2 is 40 Ω / sq or less, the amount of current that can be extracted to the outside of the photoelectric conversion element increases, and thus the photoelectric conversion efficiency of the photoelectric conversion element tends to be improved.

The conductive layer 2 may be provided with a metal wire. When a metal wire is provided on the conductive layer 2, the resistance of the conductive layer 2 tends to decrease. As the metal wire, for example, a metal wire containing at least one metal selected from platinum, gold, silver, copper, aluminum, nickel, and titanium can be used. From the viewpoint of avoiding a decrease in the amount of incident light due to the metal wire provided on the conductive layer 2, the thickness of the metal wire is preferably about 0.1 to 4 mm, for example.

<Photoelectric conversion layer>
The photoelectric conversion layer 3 has a porous semiconductor layer made of a semiconductor material. The porous semiconductor layer is adsorbed with a dye and is preferably filled with a carrier transport material. The carrier transport material is as shown in <Charge transport layer> below.

<Porous semiconductor layer>
The form of the porous semiconductor layer is not particularly limited, and is a film-form porous semiconductor made of a semiconductor material in which a bulk material or a particulate semiconductor material made of a semiconductor material or a semiconductor material in which a large number of micropores are formed. Layers and the like can be used. Among them, as a form of the porous semiconductor layer, a film-like porous semiconductor layer made of a semiconductor material in which a large number of micropores are formed (hereinafter, simply referred to as “thin-film-like porous semiconductor layer”) Is preferably used. Thereby, since the light receiving area of the photoelectric conversion layer 3 increases, the photoelectric conversion efficiency of the photoelectric conversion element tends to be improved. In addition, thinning of the photoelectric conversion element tends to be promoted.

In order to improve the photoelectric conversion efficiency of the photoelectric conversion element, it is necessary to form the photoelectric conversion layer 3 in which more dye is adsorbed. For this reason, it is preferable to use a porous semiconductor layer having a large specific surface area. When using a thin-film-like porous semiconductor layer as the form of the porous semiconductor layer, the porous semiconductor layer preferably has a specific surface area of, for example, 10 m ² / g or more and 200 m ² / g or less. In addition, even when a layer containing a particulate semiconductor material is used as the form of the porous semiconductor layer, the specific surface area of the porous semiconductor layer is set in the above range from the viewpoint of securing the adsorption amount of the dye. It is preferable. In addition, the specific surface area of a porous semiconductor layer is calculated | required based on the BET method (JIS Z8830: 2001) etc. which are gas adsorption methods, for example.

The porosity of the porous semiconductor layer (ratio of the volume of voids formed in the porous semiconductor layer to the total volume of the porous semiconductor layer) is preferably 20% or more, more preferably 40% or more and 80%. It is as follows. When the porosity of the porous semiconductor layer is 20% or more, the carrier transport material tends to diffuse sufficiently inside the porous semiconductor layer. Note that the porosity of the porous semiconductor layer is obtained by calculation from the thickness of the porous semiconductor layer, the mass of the porous semiconductor layer, and the density of the semiconductor material.

Examples of the semiconductor material constituting the porous semiconductor layer (hereinafter simply referred to as “semiconductor material”) include titanium oxide, zinc oxide, tin oxide, iron oxide, niobium oxide, cerium oxide, tungsten oxide, nickel oxide or titanic acid. It may be a metal oxide such as strontium, or may be cadmium sulfide, lead sulfide, zinc sulfide, indium phosphide, copper indium sulfide (CuInS ₂ ), CuAlO ₂ or SrCu ₂ O ₂ . As a material constituting the porous semiconductor layer, one of the listed materials may be used alone, or two or more of the listed materials may be used in combination. Among these, the semiconductor material preferably includes at least one of titanium oxide, zinc oxide, tin oxide, and niobium oxide, and more preferably includes titanium oxide. When the porous semiconductor layer contains titanium oxide, the stability and safety of the porous semiconductor layer tend to be improved, and the photoelectric conversion efficiency of the photoelectric conversion element tends to be improved.

In the present specification, “titanium oxide” means, for example, not only various narrowly defined titanium oxides such as anatase type titanium oxide, rutile type titanium oxide, amorphous titanium oxide, metatitanic acid or orthotitanic acid, but also titanium hydroxide or Also included is a titanium compound (titanium oxide in a broad sense) containing oxygen such as hydrous titanium oxide. These titanium oxides may be used alone or in combination. Anatase-type titanium oxide and rutile-type titanium oxide can be in either form depending on the production method or thermal history, but anatase-type titanium oxide is common.

The form of the porous semiconductor layer may be either a single crystal or a polycrystalline sintered body, but is preferably a polycrystalline sintered body. If the porous semiconductor layer is made of a polycrystalline sintered body, the stability of the porous semiconductor layer tends to be improved. Further, since the crystal growth of the porous semiconductor layer becomes easy, the manufacturing cost of the photoelectric conversion element tends to be reduced.

The average particle size of the semiconductor material is not particularly limited. However, since the number of adsorption points of the dye can be adjusted by changing the average particle size of the semiconductor material, it is preferable to appropriately set the average particle size of the semiconductor material in consideration of this fact. Specifically, although it cannot be said unconditionally because of the formation conditions of the photoelectric conversion layer 3, the adsorption point of the dye increases as the average particle size of the semiconductor material decreases. Therefore, when the porous semiconductor layer includes a semiconductor material having a small average particle diameter, the photoelectric conversion layer 3 including the porous semiconductor layer increases the amount of dye adsorbed, and thus tends to improve the photoelectric conversion efficiency of the photoelectric conversion element. It is in. On the other hand, when the average particle size of the semiconductor material is increased, the light scattering property is improved. Therefore, when the porous semiconductor layer includes a semiconductor material having a large average particle diameter, the photoelectric conversion layer 3 including the porous semiconductor layer is excellent in light scattering properties, which contributes to an improvement in the light capture rate.

For example, when the porous semiconductor layer is made of a polycrystalline sintered body, the average particle size of the crystallites constituting the polycrystalline sintered body is preferably 5 nm or more and less than 50 nm, and preferably 10 nm or more and 30 nm or less. More preferred. Thereby, since an effective surface area sufficiently large with respect to the projected area can be obtained, the amount of dye adsorbed increases. Therefore, since a high short circuit current density is obtained, the photoelectric conversion efficiency tends to be improved. The average particle size of the crystallites is calculated by applying Scherrer's equation to the X-ray diffraction spectrum of the porous semiconductor layer obtained by X-ray diffraction measurement, for example.

In order to increase the adsorption amount of the dye, the porous semiconductor layer is preferably made of a semiconductor material having an average particle size of 5 nm or more and less than 50 nm, and more preferably a semiconductor having an average particle size of 10 nm or more and 30 nm or less. It consists of materials. However, when not only increasing the amount of dye adsorbed but also improving light scattering properties, the porous semiconductor layer preferably has a mean particle size of a layer made of a semiconductor material having an average particle size of 5 nm or more and less than 50 nm. A layer made of a semiconductor material having a mean particle size of 10 nm to 30 nm and a layer made of a semiconductor material having a mean particle size of 50 nm or more. is there.

In addition, since the amount of dye adsorbed is proportional to the size of the effective surface area of the photoelectric conversion layer 3, it also changes when the thickness of the photoelectric conversion layer 3 changes. However, the amount of water necessary for the dye adsorption solution (solution in which the dye is dissolved in a solvent) does not depend on the thickness of the photoelectric conversion layer 3.

Moreover, it is preferable that the pore diameter in a porous semiconductor layer is 15 nm or more. When the pore diameter in the porous semiconductor layer is less than 15 nm, the dye adsorption process described later is hindered, and the dye adsorption amount may decrease. As a result, it may be difficult to improve the photoelectric conversion efficiency of the photoelectric conversion element. However, if the pore diameter in the porous semiconductor layer is 15 nm or more, a decrease in the amount of dye adsorbed can be prevented, and the amount of dye adsorbed should be, for example, 3.5 × 10 ⁻⁸ mol / cm ² or more. Can do. Therefore, a photoelectric conversion element having excellent photoelectric conversion efficiency can be provided. The pore diameter in the porous semiconductor layer is determined in accordance with, for example, the BET method (JIS Z8830: 2001) which is a gas adsorption method.

When the porous semiconductor layer has a multilayer structure, the porous semiconductor layer preferably has a semiconductor layer made of semiconductor particles having an average particle size of 50 nm or more, and the semiconductor particles having an average particle size of 50 nm or more and 600 nm or less It is more preferable to have a semiconductor layer made of Thereby, since the optical path length in the photoelectric converting layer 3 becomes long, more light can be absorbed by the photoelectric converting layer 3.

The thickness of the photoelectric conversion layer 3 is not particularly limited, but is preferably 5 μm or more and 45 μm or less from the viewpoints of light transmittance and photoelectric conversion efficiency.

<Dye>
As the dye, for example, various metal complex dyes capable of absorbing light in at least one of the visible light region and the infrared light region may be used, or at least one region of the visible light region and the infrared light region. Various organic dyes that can absorb the light may be used.

Examples of the metal complex dye include 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, Rh, etc. At least one of dyes in which a ligand is coordinately bonded to the metal atom can be used. Examples of such metal complex dyes include porphyrin dyes, phthalocyanine dyes, naphthalocyanine dyes, ruthenium metal complex dyes, and the like.

As the metal complex dye, a phthalocyanine dye or a ruthenium metal complex dye is preferably used, more preferably a ruthenium metal complex dye, and particularly, a ruthenium series represented by the following chemical formulas (1) to (3). It is preferable to use a metal complex dye. When a phthalocyanine dye or a ruthenium metal complex dye is used as the metal complex dye, particularly when a ruthenium metal complex dye represented by the following chemical formulas (1) to (3) is used, this dye is in the near infrared region. Therefore, the photoelectric conversion efficiency of the photoelectric conversion element is increased. “TBA” in the following chemical formulas (2) to (3) represents tetrabutylammonium.

The metal complex dye used in the present invention is preferably a metal complex dye having a terpyridyl group. Thereby, higher photoelectric conversion efficiency can be obtained. It was confirmed that the effects of the present invention were obtained even when a metal complex dye having a bipyridyl group as represented by the above chemical formulas (1) and (2) was used. However, the present inventors have actually confirmed that the degree of effect obtained is greater when the metal complex dye having a terpyridyl group is used than when the metal complex dye having a bipyridyl group is used. ing.

Examples of the metal complex dye having a terpyridyl group include a compound represented by the above chemical formula (3) or a dye described in Japanese Patent No. 4485181 (Japanese Patent Laid-Open No. 2005-162718). The terpyridyl group also includes a terpyridyl group in which at least one hydrogen atom constituting the terpyridyl group is substituted with an atom or an atomic group other than a hydrogen atom (for example, COOH or COOTBA).

The dye described in Japanese Patent No. 4485181 contains ruthenium, osmium, iron, rhenium or technetium as a metal atom. This dye preferably contains one terpyridyl group and a halogen atom or an atomic group other than the terpyridyl group as a ligand. The terpyridyl group contained in this dye is preferably one in which at least one hydrogen atom in the para position with respect to the nitrogen atom constituting the terpyridyl group is substituted with an atomic group (for example, COOH or an alkyl group). The atomic group other than the terpyridyl group is preferably at least one of NCS ⁻ , CN ⁻ , NCO ⁻ and H ₂ O, for example.

In order to strongly adsorb the dye to the porous semiconductor layer, the dye contains carboxylic acid group, carboxylic acid anhydride group, alkoxy group, hydroxyl group, hydroxyalkyl group, sulfonic acid group, ester group, mercapto group in the molecule. Alternatively, it preferably has an interlock group such as a phosphonyl group, and more preferably has a carboxylic acid group or a carboxylic anhydride group. Here, the interlock group provides an electrical bond that facilitates the transfer of electrons between the excited state of the dye and the conduction band of the semiconductor material.

When the dye has a carboxylic acid group, the adsorptivity of the dye to the porous semiconductor layer is stabilized, so that electrons are likely to be efficiently injected from the dye into the porous semiconductor layer. Even when the dye has a carboxylic acid anhydride group instead of a carboxylic acid group, or when the dye has a carboxylic acid anhydride group together with a carboxylic acid group in the molecule, electrons from the dye to the porous semiconductor layer There is a tendency that the injection of is efficiently performed.

The dye is adsorbed to the porous semiconductor layer using a dye adsorption solution in which the dye is dissolved in a solvent. The amount of water contained in the dye adsorption solution is preferably 600 ppm or more, more preferably 2000 ppm or more, and further preferably 2000 ppm or more and 15000 ppm or less. In general, the dye is considered to be adsorbed to the porous semiconductor layer by a dehydration condensation reaction between a functional group of the dye and a hydroxyl group present on the surface of the semiconductor material. When the amount of water contained in the dye adsorption solution is 600 ppm or more, the dehydration condensation reaction is promoted, so that it is considered that more dye is adsorbed to the porous semiconductor layer. For example, the adsorption amount of the dye in the photoelectric conversion layer 3 is 3.5 × 10 ⁻⁸ mol / cm ² or more. Therefore, since a high short circuit current density tends to be obtained, the photoelectric conversion efficiency is improved. On the other hand, when the amount of water contained in the dye adsorption solution exceeds 15000 ppm, the photoelectric conversion efficiency starts to decrease. The reason for this is that if the amount of water contained in the dye adsorption solution exceeds 15000 ppm, the dye may be agglomerated and adsorbed on the porous semiconductor layer, thus reducing the open-circuit voltage and the fill factor. It is thought that it is because it invites. The amount of water contained in the dye adsorption solution is the ratio of the mass of H ₂ O contained in the dye adsorption solution to the mass of the dye adsorption solution, and is contained in the dye adsorption solution by, for example, the Karl Fischer method. It can be determined by measuring the mass of H ₂ O. Further, the amount of water contained in the dye adsorption solution is synonymous with the amount of water contained in the solvent of the dye adsorption solution.

As a method for adjusting the amount of water contained in the dye adsorption solution, for example, after measuring the amount of water in the solvent (dehydrated solvent) of the dye adsorption solution using a Karl Fischer moisture meter, Examples thereof include a method of adding H ₂ O to the dye adsorption solution or the solvent of the dye adsorption solution so that the contained moisture amount becomes an appropriate moisture amount.

As the solvent capable of dissolving the dye, for example, a carbonate compound such as propylene carbonate, a nitrile compound such as acetonitrile or methoxypropionitrile, an alcohol such as methanol, ethanol or t-butanol, or an aprotic polar substance is used. These anhydrous solvents are preferably used. As the solvent capable of dissolving the dye, these may be used alone or in combination of two or more. Among these, in the present invention, it is preferable to use a mixed solvent containing one or more nitrile compounds and one or more alcohols. For example, it is preferable to use a mixed solvent of acetonitrile and t-butanol, and it is more preferable to use a mixed solvent of anhydrous acetonitrile and anhydrous t-butanol. Thereby, the solubility of a pigment | dye increases and the permeability | transmittance of the pigment | dye to a porous semiconductor layer also increases. Therefore, since the amount of dye adsorbed on the porous semiconductor layer increases, a high short-circuit current density tends to be obtained. Therefore, the photoelectric conversion efficiency of the photoelectric conversion element can be improved. When using a mixed solvent containing one or more nitrile compounds and one or more alcohols as a solvent capable of dissolving the dye, (one or more nitrile compounds): (one or more alcohols) = 1 : 10 or more and 10: 1 or less (volume ratio), (one or more anhydrous nitrile compounds): (one or more anhydrous alcohols) = 1: 10 or more and 10: 1 or less (volume ratio) More preferably.

The density | concentration of the pigment | dye in the solution for pigment | dye adsorption can be suitably adjusted with the kind of pigment | dye and solvent to be used. However, in order to improve the function of adsorbing the dye to the porous semiconductor layer, the concentration of the dye in the dye adsorption solution is preferably as high as possible, for example, preferably 1 × 10 ⁻⁴ mol / L or more. .

In the present invention, the amount of dye adsorbed in the photoelectric conversion layer 3 is preferably 3.5 × 10 ⁻⁸ mol / cm ² or more, and more preferably 8.0 × 10 ⁻⁸ mol / cm ² or more. Preferably, it is 8.0 × 10 ⁻⁸ mol / cm ² or more and 1.0 × 10 ⁻⁶ mol / cm ² or less. If the amount of dye adsorbed in the photoelectric conversion layer 3 is less than 3.5 × 10 ⁻⁸ mol / cm ² , the amount of light absorbed by the photoelectric conversion layer 3 is decreased, and thus the short-circuit current density is decreased. There is. However, if the amount of dye adsorbed in the photoelectric conversion layer 3 is 3.5 × 10 ⁻⁸ mol / cm ² or more, the amount of light absorbed by the photoelectric conversion layer 3 increases, so that the short-circuit current density increases. The photoelectric conversion efficiency is improved. Moreover, when the adsorption amount of the dye in the photoelectric conversion layer 3 exceeds 1.0 × 10 ⁻⁶ mol / cm ² , the dye may be aggregated and adsorbed on the surface of the porous semiconductor layer. Then, electrons injected into the semiconductor material (semiconductor material constituting the porous semiconductor layer) through this dye may leak, which may cause a reduction in open circuit voltage. However, when the adsorption amount of the dye in the photoelectric conversion layer 3 is 3.5 × 10 ⁻⁸ mol / cm ² or more and 1.0 × 10 ⁻⁶ mol / cm ² or less, the dye is simply attached to the surface of the porous semiconductor layer. Since it is adsorbed by the layer, it is considered that the leakage of electrons can be prevented, and thus the open circuit voltage can be prevented from being lowered.

The amount of dye adsorbed in the photoelectric conversion layer 3 can be determined according to, for example, an absorptiometric method.

<Charge transport layer>
The carrier transport material is preferably a conductive material that can transport ions. As a suitable material for the carrier transport material, for example, a liquid electrolyte, a solid electrolyte, a gel electrolyte, a molten salt gel electrolyte, or the like can be used.

The liquid electrolyte is preferably a liquid containing redox species, and is not particularly limited as long as it can be generally used in a battery or a solar battery. Examples of the liquid electrolyte include those comprising a redox species and a solvent capable of dissolving the redox species, those comprising a redox species and a molten salt capable of dissolving the redox species, or the redox species and the above solvent. And the above-mentioned molten salt.

As the redox species, for example, at least one of I ⁻ / I ³⁻ , Br ²⁻ / Br ³⁻ , Fe ²⁺ / Fe ^3+, and quinone / hydroquinone can be used. Specifically, as the redox species, a combination of metal iodide and iodine (I ₂ ), a combination of a salt composed of iodide ions and iodine (I ₂ ), or a metal bromide and bromine (Br ₂ ). It is preferable to use a combination thereof. Photoelectric conversion elements using these redox species exhibit better IV curves than photoelectric conversion elements using, for example, cobalt complexes or ferrocene as redox species.

As the metal iodide, for example, at least one of lithium iodide (LiI), sodium iodide (NaI), potassium iodide (KI), and calcium iodide (CaI ₂ ) can be used.

As the salt composed of iodide ions, for example, at least one of ammonium salt and imidazolium salt can be used. As the ammonium salt, for example, at least one of tetraethylammonium iodide (TEAI), tetrapropylammonium iodide (TPAI), tetrabutylammonium iodide (TBAI), and tetrahexylammonium iodide (THAI) is used. Can do. Examples of the imidazolium salt include dimethylpropylimidazole iodide (DMPII), methylpropylimidazole iodide (MPII), ethylmethylimidazole iodide (EMII), ethylimidazole iodide (EII), and hexylmethylimidazole iodide (HMII). ) Can be used.

As the metal bromide, for example, at least one of lithium bromide (LiBr), sodium bromide (NaBr), potassium bromide (KBr), and calcium bromide (CaBr ₂ ) can be used.

As the redox species, several types can be used in combination, such as a combination of a metal iodide and iodide ion salt and iodine.

Examples of the solvent capable of dissolving the redox species include carbonate compounds such as propylene carbonate, nitrile compounds such as acetonitrile, alcohols such as ethanol, water, aprotic polar substances, and the like. As the solvent capable of dissolving the redox species, these may be used alone or in admixture of two or more. Among these, it is preferable to use a carbonate compound or a nitrile compound.

The solid electrolyte is preferably a conductive material that can transport electrons, holes, or ions, and can preferably be used as an electrolyte of a photoelectric conversion element and has no fluidity. Specifically, as the solid electrolyte, a hole transport material such as polycarbazole, an electron transport material such as tetranitrofluororenone, a conductive polymer such as polyroll, a polymer electrolyte obtained by solidifying a liquid electrolyte with a polymer compound, A p-type semiconductor such as copper iodide or copper thiocyanate, or an electrolyte obtained by solidifying a liquid electrolyte containing a molten salt with fine particles can be used.

The gel electrolyte is preferably composed of an electrolyte and a gelling agent. The mixing ratio of the electrolyte and the gelling agent is preferably adjusted as appropriate. As the electrolyte, for example, the liquid electrolyte or the solid electrolyte can be used.

Examples of gelling agents include polymers such as crosslinked polyacrylic resin derivatives, crosslinked polyacrylonitrile derivatives, polyalkylene oxide derivatives, silicone resins, or polymers having a nitrogen-containing heterocyclic quaternary compound salt structure in the side chain. A gelling agent or the like can be used.

The molten salt gel electrolyte is preferably composed of the gel electrolyte and a room temperature molten salt. As the room temperature molten salt, for example, quaternary ammonium salts of nitrogen-containing heterocyclic compounds such as pyridinium salts or imidazolium salts can be used.

The charge transport layer 10 may contain the following additives as required. As the additive, a nitrogen-containing aromatic compound such as t-butylpyridine (TBP) or an ionic organic compound such as guanidine thiocyanate may be used. As the additive, both of the aromatic compound containing nitrogen and an ionic organic compound such as guanidine thiocyanate can be used.

The concentration of the redox species in the carrier transport material is preferably selected as appropriate depending on the type of solvent and electrolyte that can dissolve the redox species, but is preferably 0.001 mol / L or more and 1.5 mol / L or less. Preferably, it is 0.01 mol / L or more and 0.7 mol / L or less. When the concentration of the redox species in the carrier transport material is within the above range, the redox species in the charge transport layer 10 tend to be efficiently transported.

<Catalyst layer>
As a material constituting the catalyst layer 6, for example, it is preferable to use at least one of platinum and carbon. When the catalyst layer 6 is made of carbon, the catalyst layer 6 is made of, for example, at least one of carbon black, graphite, glass carbon, amorphous carbon, hard carbon, soft carbon, carbon whisker, carbon nanotube, and fullerene. It is preferable.

The thickness of the catalyst layer 6 is not particularly limited, but is preferably about 0.5 nm to 1000 nm.

<Counter electrode conductive layer>
The counter electrode conductive layer 7 collects electrons and also functions as an electrode for electrically connecting adjacent photoelectric conversion elements when manufacturing photoelectric conversion modules by connecting photoelectric conversion elements in series.

As the material constituting the counter electrode conductive layer 7, a conductive material is preferably used. As the conductive material, for example, at least one of metal oxides such as ITO, FTO, and ZnO may be used, and the conductive material includes at least one metal such as titanium, tungsten, gold, silver, copper, and nickel. A conductive material may be used, or a conductive material containing at least one of the above metal oxides and at least one of the above metals may be used. Of these, titanium is preferably used as the conductive material. Thereby, the strength of the counter electrode conductive layer 7 is improved.

The thickness of the counter electrode conductive layer 7 is preferably set as appropriate according to the specific resistivity of the material of the counter electrode conductive layer 7. If the thickness of the counter electrode conductive layer 7 is too thin, the resistance of the counter electrode conductive layer 7 becomes high, and if the thickness of the counter electrode conductive layer 7 is too thick, the movement of the carrier transport material is hindered.

<Cover body>
The cover body 8 prevents the carrier transport material from volatilizing and prevents water and the like from entering the photoelectric conversion element.

The material constituting the cover body 8 is not particularly limited as long as it is a material that can generally be used for a solar cell and can exhibit the effects of the present invention. Examples of such a material include soda lime glass, lead glass, borosilicate glass, fused silica glass, and crystal quartz glass. Among them, it is preferable to use soda lime float glass as a material constituting the cover body 8.

<Sealing part>
The sealing portion 9 prevents the carrier transport material from volatilizing and prevents water and the like from entering the photoelectric conversion element. In addition, the sealing portion 9 absorbs stress (impact) that acts on the support substrate 1 and absorbs bending that acts on the support substrate 1 when the photoelectric conversion element is used for a long period of time.

The sealing portion 9 may be a single layer including at least one of a silicone resin, an epoxy resin, a polyisobutylene resin, a hot melt resin, and a glass frit. It may be a laminated body constructed. In the case where a hardly volatile solvent such as a nitrile solvent or a carbonate solvent is used as the solvent for the carrier transport material, the sealing portion 9 is made of a silicone resin, a hot melt resin (for example, an ionomer resin), or a polyisobutylene resin. And at least one of glass frit. Thereby, it exists in the tendency for the corrosion of the sealing part 9 with respect to carrier transport material to be suppressed.

[Production Method of Photoelectric Conversion Element]
FIG. 2 is a flowchart showing an example of a method for producing a photoelectric conversion element of the present invention. In the photoelectric conversion element manufacturing method shown in FIG. 2, in step S <b> 101, a transparent electrode substrate 11 in which the conductive layer 2 is formed on the support substrate 1 is prepared. For example, a commercially available transparent electrode substrate may be prepared, or the conductive layer 2 may be formed on the support substrate 1 by a method such as sputtering or thermal CVD.

Next, in step S <b> 102, a porous semiconductor layer is formed on the conductive layer 2. The method for forming the porous semiconductor layer is not particularly limited. For example, the porous semiconductor layer can be formed by any one of the following methods (i) to (iv). Among the following (i) to (iv), it is preferable to form the porous semiconductor layer by using the screen printing method shown in the following (i). Thereby, it exists in the tendency which can manufacture a comparatively thick porous semiconductor layer at low cost.
(I) A paste containing fine particles made of a semiconductor material is applied onto the conductive layer 2 by a screen printing method or an inkjet method, and then baked.
(Ii) A porous semiconductor layer is formed on the conductive layer 2 using a desired source gas by CVD or MOCVD.
(Iii) A porous semiconductor layer is formed on the conductive layer 2 by a PVD method (for example, a vapor deposition method or a sputtering method) using a solid material.
(Iv) A porous semiconductor layer is formed on the conductive layer 2 by a sol-gel method or a method using an electrochemical redox reaction.

In the case of forming a thin film-like porous semiconductor layer or a layer containing a particulate semiconductor material as the porous semiconductor layer, a porous semiconductor layer having a specific surface area of 10 m ² / g or more and 200 m ² / g or less may be formed. preferable. Thereby, since the photoelectric converting layer 3 in which more pigment | dye was hold | maintained can exist, it exists in the tendency for the photoelectric conversion efficiency of a photoelectric conversion element to improve.

Hereinafter, a method for forming a porous semiconductor layer using anatase-type titanium oxide as a semiconductor material will be specifically described.

First, 125 mL of titanium isopropoxide is dropped into 750 mL of a 0.1 mol / L nitric acid aqueous solution for hydrolysis, and heated at 80 ° C. for 8 hours. Thereby, a sol liquid is obtained.

Next, the obtained sol solution is heated at 230 ° C. for 11 hours in a titanium autoclave. Thereby, titanium oxide particles grow. Thereafter, ultrasonic dispersion is performed at room temperature for 30 minutes. Thereby, a colloidal solution containing titanium oxide particles having an average particle diameter (average primary particle diameter) of 15 nm is obtained.

Next, ethanol twice the volume of the colloidal solution is added to the obtained colloidal solution, and this is centrifuged at a rotational speed of 5000 rpm. By this centrifugation, the titanium oxide particles and the solvent are separated, and thus titanium oxide particles are obtained.

Next, after washing the obtained titanium oxide particles, the titanium oxide particles are added to a solution in which ethylcellulose and terpineol are dissolved in absolute ethanol and stirred. Thereby, the titanium oxide particles are dispersed in the solution.

Next, the solution in which the titanium oxide particles are dispersed is heated under vacuum to evaporate ethanol. Thereby, a titanium oxide paste is obtained. And as a final composition, a density | concentration is adjusted so that it may become titanium oxide solid concentration 20 mass%, ethyl cellulose 10 mass%, and terpineol 70 mass%, for example. Note that the above-mentioned final composition is illustrative and is not limited to this.

As a solvent used for preparing a paste containing (suspended) titanium oxide particles, in addition to the above, for example, a glyme solvent such as ethylene glycol monomethyl ether, an alcohol solvent such as isopropyl alcohol, isopropyl alcohol A mixed solvent such as a mixed solution of toluene and toluene, or water can be used.

Next, the obtained titanium oxide paste is screen-printed on the conductive layer 2 and then dried and fired. Thereby, a porous semiconductor layer is formed. Here, it is preferable that the drying conditions and the firing conditions (temperature, time, atmosphere, etc.) of the titanium oxide paste are adjusted according to the types of the material of the support substrate 1 and the semiconductor material, respectively. The titanium oxide paste is preferably baked, for example, in an air atmosphere or an inert gas atmosphere within a range of about 50 to 800 ° C. for about 10 seconds to 12 hours. The drying and firing of the titanium oxide paste may be performed once at a single temperature, for example, or may be performed twice or more at different temperatures. The specific surface area of the porous semiconductor layer made of titanium oxide produced under the above conditions is in the range of 10 m ² / g to 200 m ² / g.

The average particle diameter of the semiconductor particles constituting the porous semiconductor layer is not particularly limited, but it is preferable that the average particle diameter is uniform to some extent as in the case of commercially available semiconductor material powders in that incident light is effectively used for photoelectric conversion. In this way, a porous semiconductor layer is formed.

Next, in step S103, a dye adsorption solution is prepared. For example, it is preferable to prepare the dye adsorption solution described in <Dye> above. In this step S103, as described in <Dye> above, after measuring the water content of the solvent (dehydrated solvent) of the dye adsorption solution using a Karl Fischer moisture meter, the amount of water contained in the dye adsorption solution It is preferable to add H ₂ O to the dye adsorbing solution or the solvent of the dye adsorbing solution so that the water content becomes the target amount of water. In this step S103, a colorless hydrophobic compound may be co-adsorbed for the purpose of reducing the interaction between the dyes such as association. Examples of the hydrophobic compound to be co-adsorbed include a steroid compound having a carboxyl group.

Next, in step S104, the dye contained in the dye adsorption solution is adsorbed on the porous semiconductor layer. For example, it is preferable to immerse the transparent electrode substrate 11 on which the porous semiconductor layer is formed in the dye adsorption solution. This dye adsorption solution is prepared in the above step S103, and the water content in the dye adsorption solution is 600 ppm or more. As a result, more dye is adsorbed on the porous semiconductor layer. For example, the amount of dye adsorbed on the porous semiconductor layer can be 3.5 × 10 ⁻⁸ mol / cm ² or more. Therefore, a photoelectric conversion element with a high short-circuit current density can be manufactured, and a photoelectric conversion element excellent in photoelectric conversion efficiency can be provided. In addition, it is preferable that the immersion conditions in process S104 are adjusted suitably.

Next, in step S105, the counter electrode 12 is formed. For example, the counter electrode conductive layer 7 is preferably formed on the cover body 8 by a method such as a sputtering method or a thermal CVD method. When the catalyst layer 6 made of platinum is formed, the catalyst layer 6 may be formed on the counter electrode conductive layer 7 by a PVD method such as vapor deposition or sputtering, or thermal decomposition or electrodeposition of chloroplatinic acid. Thus, the catalyst layer 6 may be formed on the counter electrode conductive layer 7. When the catalyst layer 6 made of a carbon material such as carbon black, ketjen black, carbon nanotube or fullerene is formed, the carbon dispersed in an arbitrary solvent and formed into a paste is formed on the counter electrode conductive layer 7 by a screen printing method or the like. It is preferable to apply to.

Next, in step S106, the carrier transport material is filled. For example, the sealing portion 9 is disposed so as to surround the periphery of the porous semiconductor layer formed on the transparent electrode substrate 11. The transparent electrode substrate 11 and the counter electrode 12 are arranged so that the porous semiconductor layer formed on the transparent electrode substrate 11 and the catalyst layer 6 of the counter electrode 12 face each other, and the transparent electrode substrate 11 and the counter electrode 12 are connected to the sealing portion 9. To fix. Thereafter, a carrier transport material is injected into a region surrounded by the sealing portion 9 from a hole formed in advance in the transparent electrode substrate 11 or the counter electrode 12, and then the hole is closed. Thereby, the photoelectric conversion element shown in FIG. 1 is manufactured.

FIG. 3 is a graph showing the relationship between the water content of the dye adsorption solution prepared in step S103 and the photoelectric conversion efficiency. In FIG. 3, the result at the time of using the metal complex represented by the said Chemical formula (3) is shown. For the photoelectric conversion efficiency, a black mask having an opening area of 0.22 cm ² is provided on the light receiving surface of the photoelectric conversion element, and light with an intensity of 1 kW / m ² is applied to the photoelectric conversion element (AM1.5 solar simulator). ). Here, the vertical axis in FIG. 3 represents a value normalized based on the photoelectric conversion efficiency when the water content of the dye adsorption solution is 620 ppm.

FIG. 4 is a graph showing the relationship (experimental result) between the moisture content of the dye adsorption solution prepared in step S103 and the adsorption amount of the dye adsorbed on the porous semiconductor layer. In FIG. 4, the result at the time of using the metal complex represented by the said Chemical formula (3) is shown. The amount of dye adsorbed represented on the vertical axis in FIG. 4 was determined according to the spectrophotometric method.

As shown in FIG. 3, when the water content of the dye adsorption solution was less than 600 ppm, the photoelectric conversion efficiency rapidly decreased. In this case, the adsorption amount of the dye in the photoelectric conversion layer 3 was less than 3.5 × 10 ⁻⁸ mol / cm ² . On the other hand, when the water content of the dye adsorption solution was 600 ppm or more, the dye adsorption amount in the photoelectric conversion layer 3 increased rapidly. The reason for this is that when the water content of the dye adsorption solution is 600 ppm or more, the dehydration condensation reaction between the functional group of the dye and the hydroxyl group present on the surface of the semiconductor material is promoted, so that more dye is porous. This is presumably because it is adsorbed by the conductive semiconductor layer.

[Photoelectric conversion module]
FIG. 5 is a cross-sectional view showing an example of the configuration of the photoelectric conversion module of the present invention. In the photoelectric conversion module illustrated in FIG. 5, two or more photoelectric conversion elements are connected in series, and the photoelectric conversion elements included in the photoelectric conversion module are the photoelectric conversion elements illustrated in FIG. 1. Of the adjacent photoelectric conversion elements, the counter electrode conductive layer 7 of one photoelectric conversion element and the conductive layer 2 of the other photoelectric conversion element are electrically connected. As described above, since the photoelectric conversion module illustrated in FIG. 5 includes the photoelectric conversion element illustrated in FIG. 1, moisture intrusion is suppressed, and a photoelectric conversion module excellent in photoelectric conversion efficiency can be provided.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. In the following, unless otherwise specified, the thickness of each layer was measured using a step gauge (manufactured by Tokyo Seimitsu Co., Ltd., model number: E-VS-S28A).

<Example 1>
First, a transparent electrode substrate 11 (made by Nippon Sheet Glass Co., Ltd., trade name “SnO ₂ film-attached glass plate”) having a width of 30 mm × length of 30 mm × thickness of 1 mm was prepared. In the transparent electrode substrate 11, the conductive layer 2 made of tin oxide (FTO) doped with fluorine was formed on the support substrate 1 made of glass.

Next, a commercially available titanium oxide paste (manufactured by Solaronix, trade name) using a screen plate having a pattern of width 5 mm × length 5 mm and a screen printer (manufactured by Neurong Seimitsu Kogyo Co., Ltd., model number: LS-150) : D / SP) was applied on the conductive layer 2 and leveled at room temperature for 1 hour. The obtained coating film was dried in an oven set at 80 ° C. for 20 minutes and then baked in air for 60 minutes using a baking furnace (model number: KDF P-100, manufactured by Denken Co., Ltd.) set at 500 ° C. The porous semiconductor layer having a thickness of about 14 μm was obtained by repeatedly applying the titanium oxide paste, drying it, and firing it.

The X-ray diffraction spectrum of the obtained porous semiconductor layer was measured using an X-ray diffractometer (manufactured by Shimadzu Corporation, model number “XD-D1”). When the average particle diameter of the titanium oxide particles was determined by applying the Scherrer equation to the measured X-ray diffraction spectrum, the average particle diameter was 20 nm. Moreover, when the pore diameter in the porous semiconductor layer was measured according to the BET method (JIS Z8830: 2001) which is a gas adsorption method, the pore diameter was 30 nm.

Next, a dye adsorption solution was prepared. Specifically, a mixed solvent of anhydrous acetonitrile and anhydrous t-butanol having a volume ratio of 1: 1 was prepared. The amount of water contained in the mixed solvent prepared using a Karl Fischer moisture meter (manufactured by Hiranuma Sangyo Co., Ltd., model number: AQ-2100) was 46 ppm. Therefore, H ₂ O was added to the mixed solvent so that the amount of water contained in the mixed solvent was 620 ppm. The dye represented by the above chemical formula (3) (manufactured by Solaronix, trade name: Ruthenizer 620-1H1TBA) was dissolved in the solvent of the dye adsorption solution thus prepared. The concentration of the dye in the obtained solution for dye adsorption was 3 × 10 ⁻⁴ mol / L.

Next, the transparent electrode substrate 11 on which the porous semiconductor layer was formed was immersed in the prepared dye adsorption solution at room temperature for 24 hours. Thereafter, it was washed with ethanol and dried at about 60 ° C. for about 5 minutes. As a result, the dye contained in the dye adsorption solution was adsorbed on the porous semiconductor layer.

Next, separately from the transparent electrode substrate 11, another glass plate with SnO ₂ film manufactured by Nippon Sheet Glass Co., Ltd. was prepared. A platinum film (catalyst layer 6) having a thickness of about 7 nm was formed on the SnO ₂ film by sputtering. Thereby, the counter electrode 12 was formed.

Next, the transparent electrode substrate 11 and the counter electrode 12 are formed using a heat-sealing film (DuPont, trade name: Binnel (registered trademark)) cut into a shape surrounding the periphery of the porous semiconductor layer on which the dye is adsorbed. And pasted together. The transparent electrode substrate 11 and the counter electrode 12 were pressure bonded by heating in an oven set at about 130 ° C. for 10 minutes.

Next, an electrolytic solution (carrier transport material) was injected from a hole formed in the counter electrode 12 in advance, and then the hole was sealed using an ultraviolet curable resin (manufactured by ThreeBond, model number: 31X-101). Thereby, the electrolyte solution was filled between the porous semiconductor layer on which the dye was adsorbed and the catalyst layer 6, and the photoelectric conversion element of Example 1 was manufactured.

The electrolytic solution was prepared as follows. Methylpropylimidazole iodide (Shikoku Kasei Kogyo Co., Ltd., redox species) is dissolved in acetonitrile as a solvent so that the concentration becomes 0.6 mol / L, and I ₂ is adjusted so that the concentration becomes 0.05 mol / L. (Kishida Chemical Co., Ltd., redox species) was dissolved. Further, t-butylpyridine (additive) was dissolved in the solvent so that the concentration was 0.5 mol / L, and LiI (additive) was dissolved so that the concentration was 0.1 mol / L.

<Example 2>
A photoelectric conversion element of Example 2 was produced according to the method described in Example 1 except that the dye adsorption solution was prepared using a solvent whose water content was adjusted to 1247 ppm.

<Example 3>
The photoelectric conversion element of Example 3 was manufactured according to the method described in Example 1 except that the dye adsorption solution was prepared using a solvent whose water content was adjusted to 2000 ppm.

<Example 4>
A photoelectric conversion element of Example 4 was produced according to the method described in Example 1 except that the dye adsorption solution was prepared using a solvent whose water content was adjusted to 3129 ppm.

<Example 5>
A photoelectric conversion element of Example 5 was produced according to the method described in Example 1 except that the dye adsorption solution was prepared using a solvent whose water content was adjusted to 6398 ppm.

<Example 6>
A photoelectric conversion element of Example 6 was produced according to the method described in Example 1 except that the dye adsorption solution was prepared using a solvent whose water content was adjusted to 12712 ppm.

<Comparative Example 1>
The photoelectric conversion device of Comparative Example 1 was prepared according to the method described in Example 1 except that the dye adsorption solution was prepared without adding H ₂ O to a mixed solvent of anhydrous acetonitrile and anhydrous t-butanol. Manufactured. That is, the amount of water contained in the dye adsorption solution in Comparative Example 1 was 46 ppm.

<Comparative Example 2>
A photoelectric conversion element of Comparative Example 2 was produced according to the method described in Example 1 except that the dye adsorption solution was prepared using a solvent having a moisture content adjusted to 287 ppm.

<Comparative Example 3>
According to the method described in Example 1 above, except that the transparent electrode substrate 11 on which the porous semiconductor layer was formed was immersed in a dye adsorption solution adjusted to a moisture content of 287 ppm at room temperature for 120 hours. The photoelectric conversion element of Comparative Example 3 was produced.

<Evaluation>
For the photoelectric conversion elements of Examples 1 to 6 and Comparative Examples 1 to 3, the short circuit current density Jsc, the open circuit voltage Voc, the fill factor FF, and the photoelectric conversion efficiency η were measured. The photoelectric conversion efficiency was measured according to the following method. First, Ag paste (trade name: Dotite, manufactured by Fujikura Kasei Co., Ltd.) was applied as a collecting electrode part to the photoelectric conversion elements of Examples 1 to 6 and Comparative Examples 1 to 3 by a known method. Next, a black mask having an opening area of 0.22 cm ² was placed on the light receiving surface of the photoelectric conversion element. Photoelectric conversion efficiency was measured by irradiating the photoelectric conversion element with light having an intensity of 1 kW / m ² (AM1.5 solar simulator). The results are shown in Table 1.

In Table 1, “water content” is the water content contained in the dye adsorption solution and is synonymous with the water content contained in the solvent of the dye adsorption solution. “Dye adsorption amount” was determined according to the spectrophotometric method. The short-circuit current density Jsc, the open circuit voltage Voc, the fill factor FF, and the photoelectric conversion efficiency η in Table 1 are values normalized based on the results of Example 1.

As shown in Table 1, in Examples 1 to 6 where the amount of water contained in the dye adsorption solution is 600 ppm or more, compared to Comparative Examples 1 to 3 where the amount of water contained in the dye adsorption solution is less than 600 ppm. The amount of dye adsorbed on the porous semiconductor layer was large, a high short-circuit current density was obtained, and the photoelectric conversion efficiency was high. The reason for this is that if the amount of water contained in the dye adsorption solution is 600 ppm or more, the dehydration condensation reaction between the functional group of the dye and the hydroxyl group present on the surface of the semiconductor material is promoted. Is considered to be adsorbed by the porous semiconductor layer. Further, as shown in Comparative Example 3, when the water content of the dye adsorption solution is less than 600 ppm, the transparent electrode substrate 11 on which the porous semiconductor layer is formed is immersed in the dye adsorption solution for a sufficiently long time. Even so, the adsorption amount of the dye could not be 3.5 × 10 ⁻⁸ mol / cm ² or more.

<Example 7>
In Example 7, the photoelectric conversion module shown in FIG. 5 was manufactured.

First, a transparent electrode substrate 11 (manufactured by Nippon Sheet Glass Co., Ltd., trade name “SnO ₂ film-attached glass”, length 60 mm × width 37 mm) having a conductive layer 2 formed on the surface was prepared. A scribe line 13 was formed in parallel with the vertical direction on the SnO ₂ film on the surface of the transparent electrode substrate 11 by laser scribing. Thereby, the conductive layer 2 was divided. A total of three scribe lines 13 were formed on the glass substrate (support substrate 1), and the width of the formed scribe line 13 was 30 μm.

Next, a layer composed of a porous semiconductor was formed according to the method described in Example 1 above. Three such layers having a thickness of 21 μm, a width of 5 mm, and a length of 50 mm were formed on the glass substrate.

Using a screen printer, a paste containing zirconia particles (average particle size of 50 nm) was applied on each of the layers composed of the porous semiconductor. Thereafter, baking was performed at 500 ° C. for 60 minutes. As a result, the porous insulating layer 14 having a distance (thickness) of 7 μm from the upper surface of each layer composed of the porous semiconductor to the flat portion was formed.

Subsequently, Pt is deposited on each of the porous insulating layers 14 at a deposition rate of 4 Å / s using a mask on which a predetermined pattern is formed and a deposition apparatus (model number: ei-5, manufactured by ULVAC). It was. Thereby, the catalyst layer 6 was obtained. The size (shape) of the catalyst layer 6 and the position of the catalyst layer 6 in the lateral direction of the transparent electrode substrate 11 were the same as the layer made of the porous semiconductor. Further, Ti was vapor-deposited on each of the catalyst layers 6 at a vapor deposition rate of 5 Å / s using a mask on which a predetermined pattern was formed and a vapor deposition apparatus (model number: ei-5, manufactured by Aruba). Thereby, the counter electrode conductive layer 7 was obtained.

The transparent electrode substrate 11 on which the three laminates were formed was immersed in the dye adsorption solution prepared in Example 1 at room temperature for 70 hours. Thereby, the pigment | dye was adsorb | sucked to the layer comprised with a porous semiconductor, and the photoelectric converting layer 4 was formed.

Subsequently, using a dispenser (ULTRASAVER manufactured by EFD), an ultraviolet curable resin (3035B manufactured by ThreeBond Co., Ltd.) was applied between the adjacent stacked bodies and outside the stacked bodies at both ends. A glass substrate (cover body 8) having a length of 60 mm and a width of 30 mm was bonded, and then irradiated with ultraviolet rays using an ultraviolet lamp (NOVACURE manufactured by EFD). Thereby, the ultraviolet curable resin was hardened and the sealing part 9 was formed.

Thereafter, the electrolyte solution (carrier transport material) of Example 1 was injected from the electrolyte solution injection hole provided in advance in the glass substrate. Thereby, the charge transport layer was formed. Thereafter, an ultraviolet curable resin was applied to the electrolyte solution injection hole, and then the ultraviolet curable resin was irradiated with ultraviolet rays. The current collecting electrode 15 was formed by applying an Ag paste (trade name: Dotite, manufactured by Fujikura Kasei Co., Ltd.) on a glass substrate. Thereby, the photoelectric conversion module of the present Example was obtained.

<Example 8>
A photoelectric conversion module of Example 8 was produced according to the method described in Example 7 except that the dye adsorption solution was prepared using a solvent whose water content was adjusted to 2000 ppm.

<Comparative example 4>
A photoelectric conversion module of Comparative Example 4 was produced according to the method described in Example 7 except that it was immersed in the dye adsorption solution used in Comparative Example 1.

<Evaluation>
On the light receiving surfaces of the photoelectric conversion modules of Examples 7 to 8 and Comparative Example 4, a black mask having an opening area of 13 cm ² was placed. The solar cell was irradiated with light having an intensity of 1 kW / m ² (AM1.5 solar simulator), and the photoelectric conversion efficiency was measured. The results are shown in Table 2.

In Table 2, “water content” is the water content contained in the dye adsorption solution, and is synonymous with the water content contained in the solvent of the dye adsorption solution. “Dye adsorption amount” was determined according to the spectrophotometric method. The short-circuit current density Jsc, the open circuit voltage Voc, the fill factor FF, and the photoelectric conversion efficiency η in Table 2 are values normalized based on the results of Example 7. As shown in Table 2, the same results as in Table 1 were obtained for the photoelectric module.

It should be considered that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 support substrate, 2 conductive layer, 3 photoelectric conversion layer, 6 catalyst layer, 7 counter electrode conductive layer, 8 cover body, 9 sealing portion, 10 charge transport layer, 11 transparent electrode substrate, 12 counter electrode, 13 scribe line, 14 porous Insulating layer, 15 current collecting electrode.

Claims (11)

1. A conductive layer, a photoelectric conversion layer, and a counter electrode are sequentially provided on a support substrate, and a photoelectric conversion element in which a carrier transport material is filled at least between the photoelectric conversion layer and the counter electrode,
   The photoelectric conversion layer is configured by adsorbing a dye to a porous semiconductor layer made of a semiconductor material using a dye adsorbing solution containing a water content of 600 ppm or more,
   The photoelectric conversion element whose adsorption amount of the said pigment | dye in the said photoelectric converting layer is 3.5x10 < ^-8 > mol / cm < ² > or more.
2. The photoelectric conversion element according to claim 1, wherein the dye is a metal complex having a terpyridyl group.
3. The photoelectric conversion element according to claim 1 or 2, wherein the solvent contained in the dye adsorption solution is an organic solvent.
4. The photoelectric conversion device according to claim 3, wherein the solvent contained in the dye adsorption solution is a mixed solvent containing one or more nitrile compounds and one or more alcohols.
5. 5. The photoelectric conversion element according to claim 1, wherein the porous semiconductor layer includes at least a layer made of a semiconductor material having an average particle diameter of 10 nm or more and 30 nm or less.
6. The photoelectric conversion element according to any one of claims 1 to 5, wherein a pore diameter in the porous semiconductor layer is 15 nm or more.
7. The photoelectric conversion element according to any one of claims 1 to 6, wherein the semiconductor material is made of a metal oxide.
8. The photoelectric conversion element according to claim 7, wherein the metal oxide includes at least titanium oxide.
9. A step of preparing a dye adsorption solution in which the dye is dissolved;
   And at least a step of adsorbing the dye contained in the dye adsorption solution to a porous semiconductor layer,
   The prepared dye adsorption solution contains a water content of 600 ppm or more,
   The method for producing a photoelectric conversion element, wherein the amount of the dye adsorbed on the porous semiconductor layer is 3.5 × 10 ⁻⁸ mol / cm ² or more.
10. The method for producing a photoelectric conversion element according to claim 9, wherein the step of preparing the dye adsorption solution includes a step of dissolving the dye in a mixed solvent containing one or more nitrile compounds and one or more alcohols. .
11. A photoelectric conversion module in which two or more photoelectric conversion elements are connected in series,
    At least one of the two or more photoelectric conversion elements is the photoelectric conversion element according to any one of claims 1 to 8,
    A photoelectric conversion module in which the counter conductive layer of one of the photoelectric conversion elements and the conductive layer of the other photoelectric conversion element of the adjacent photoelectric conversion elements are electrically connected.

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