JP6748167B2 - Electrode for solar cell, dye-sensitized solar cell, and manufacturing method thereof - Google Patents

Description

The present invention relates to a solar cell electrode, a dye-sensitized solar cell, and a method for producing these.

As a dye-sensitized solar cell (DSC), there is a so-called Gretzel solar cell (see Non-Patent Document 1). The Gretzel-type DSC has a photoelectrode, a counter electrode facing the photoelectrode, and a charge transfer body located between the two electrodes. In DSC, when a sensitizing dye adsorbed on the surface of a photoelectrode is irradiated with light, electrons are generated.
The generated electrons move from the sensitizing dye to the photoelectrode, the conductive film, and the external circuit, and become an electric current.
The electron-releasing sensitizing dye is reduced by the redox couple in the charge transfer material. The oxidized redox couple is regenerated into a reductant by the catalyst layer formed on the counter electrode.

In the prior art, a platinum layer is used as a catalyst layer. This is because platinum shows a high catalytic ability for the redox reaction, and platinum is excellent in stability and conductivity.

"Nature", Volume 353, p. 737-740, 1991

However, the photoelectric conversion efficiency of the conventional DSC is not yet satisfactory.
Then, this invention aims at the electrode for solar cells which can further improve the photoelectric conversion efficiency of DSC.

The present invention has the following aspects.
[1] A conductive layer and a catalyst layer that is located on the conductive layer and forms a surface,
The catalyst layer contains a conductive material having a resistivity of 1.0×10 ⁻⁴ Ωcm or less,
A sheet resistance value of the catalyst layer is 120 Ω/□ or more, an electrode for a solar cell.
[2] The solar cell electrode according to [1], wherein the catalyst layer has a catalyst activity value of −0.31 V (Ag/Ag ⁺ ) or more, which is obtained under the following measurement conditions.
<Method of measuring catalytic activity value>
In the three-electrode method, an opposite electrode was used as a working electrode, a platinum wire was used as a counter electrode, Ag/Ag ⁺ was used as a reference electrode, and an acetonitrile solution containing 1 mmol/L of iodine, 10 mmol/L of lithium iodide and 100 mmol/L of lithium perchlorate was prepared. The reduction current value is measured by cyclic voltammetry measurement under the conditions of a measurement solvent, a sweep speed of 50 mV/sec or less, and a sweep voltage width of −1 to 1 V, and the voltage at which the reduction current value reaches a peak is defined as the catalyst activity value.
[3] The catalyst layer according to [1] or [2], which contains a platinum group metal, and the platinum group metal content is 70 to 100 mass% with respect to the total mass of the catalyst layer. Electrode for solar cell.
[4] The solar cell electrode according to any one of [1] to [3], wherein the conductive layer is made of an oxide semiconductor.
[5] The solar cell electrode according to any one of [1] to [4] is used as a counter electrode, and is provided between the photoelectrode facing the catalyst layer of the counter electrode, and between the counter electrode and the photoelectrode. A dye-sensitized solar cell having a charge carrier located therein.

[6] The method for manufacturing the solar cell electrode according to any one of [1] to [4], wherein the catalyst layer is formed on the conductive layer by sputtering or vapor deposition. Method.
[7] The solar cell electrode is obtained by the method for manufacturing a solar cell electrode according to [6], and the obtained solar cell electrode is used as a counter electrode, and a photoelectrode facing the catalyst layer of the counter electrode. And a charge transfer body is provided between the photoelectrode and the counter electrode.

According to the DSC of the present invention, the photoelectric conversion efficiency can be further increased.

1 is a cross-sectional view of a dye-sensitized solar cell according to an embodiment of the present invention.

(Dye-sensitized solar cell)
The dye-sensitized solar cell (DSC) of the present invention has a photoelectrode, a counter electrode, and a charge transfer body.
Hereinafter, the solar cell electrode of the present invention and the dye-sensitized solar cell (DSC) using the same will be described with reference to an example.

The DSC 1 in FIG. 1 includes a photoelectrode 10, a counter electrode 20, a charge transfer body 30, and a sealing material 40. The photoelectrode 10 and the counter electrode 20 face each other. The charge transfer body 30 is located between the photoelectrode 10 and the counter electrode 20. The sealing material 40 seals the charge transfer body 30. The charge transfer body 30 is in contact with both the photoelectrode 10 and the counter electrode 20.

At least one of the photoelectrode 10 and the counter electrode 20 is light transmissive. The light-transmitting photoelectrode 10 or the counter electrode 20 forms a light incident surface. In this paper, the light transmittance of the photoelectrode 10 or the counter electrode 20 means that light is transmitted to the extent that the DSC 1 can generate electricity.

The counter electrode 20 of the present embodiment is the solar cell electrode of the present invention.
The counter electrode 20 includes a counter electrode support 22, a counter electrode conductive layer 24, and a catalyst layer 26. The counter electrode conductive layer 24 is located on the counter electrode support 22. The catalyst layer 26 is located on the counter electrode conductive layer 24. That is, the counter electrode support 22, the counter electrode conductive layer 24, and the catalyst layer 26 are located in this order.
The counter electrode conductive layer 24 has an exposed portion 28 outside the sealing material 40. The exposed portion 28 is exposed to the outside of the DSC 1.

The counter electrode support 22 is a glass plate, a resin plate, a film or a sheet (the resin plate, the film and the sheet may be collectively referred to as a resin plate or the like), a metal foil or the like. When the counter electrode 20 forms the light incident surface, the counter electrode support 22 has a light transmissive property. In this case, a so-called transparent base material is preferable as the counter electrode support 22.

When the counter electrode support 22 is a glass plate, the material is soda lime glass, quartz glass, borosilicate glass, Vycor glass, alkali-free glass, blue plate glass, white plate glass, or the like.

When the counter electrode support 22 is a resin plate or the like, the material is polyacrylic, polycarbonate, polyester, polyimide, polystyrene, polyvinyl chloride, polyamide or the like.
The material of the counter electrode support 22 is preferably a resin, more preferably polyethylene terephthalate (PET) or polyethylene naphthalate (PEN). If the counter electrode support 22 is made of resin, the DSC 1 can be made thin and lightweight. In addition, if the counter electrode support 22 is made of resin, it is easy to give flexibility to the DSC 1.

The thickness T20 of the counter electrode 20 is preferably 100 μm to 6 mm, for example. If the thickness T20 is not less than the above lower limit, the strength of the counter electrode 20 can be increased. If the thickness T20 is equal to or less than the upper limit value, the DSC 1 can be further reduced in weight.

The counter electrode support 22 may be a rigid support or a flexible support having flexibility.
The thickness T22 of the counter electrode support 22 is not particularly limited, and is preferably 10 μm to 5 mm, for example. The thickness T22 of the counter electrode support 22 is an average of 10 arbitrary points measured by a contact-type micrometer.

The counter electrode conductive layer 24 is not particularly limited as long as it has conductivity. The counter electrode conductive layer 24 is a conventionally known conductive layer for DSC.

The material of the counter electrode conductive layer 24 is a metal such as gold, platinum, silver, copper, chromium, tungsten, aluminum, magnesium, titanium, nickel, manganese, zinc, iron and alloys thereof; fluorine-doped tin oxide (FTO), Sodium, sodium-potassium alloy, lithium, magnesium, aluminum, magnesium-silver mixture, magnesium-indium mixture, aluminum-lithium alloy, Al/Al ₂ O ₃ mixture, Al/LiF mixture, CuI, indium tin oxide (ITO). , SnO ₂ , aluminum zinc oxide (AZO), indium zinc oxide (IZO), gallium zinc oxide (GZO) and other conductive transparent inorganic materials, conductive transparent polymers, carbon and the like. These materials may be used alone or in combination of two or more.
When the material of the counter electrode conductive layer 24 is a metal, an oxide film is formed between the counter electrode conductive layer 24 and the catalyst layer 26. When the oxide film is formed, the electrical resistance (interface resistance) at the interface between the counter electrode conductive layer 24 and the catalyst layer 26 increases. Therefore, as a material of the counter electrode conductive layer 24, a conductive oxide semiconductor is preferable.
When a conductive oxide semiconductor is used for the counter electrode conductive layer 24, the interface resistance can be reduced even if the contact area between the counter electrode conductive layer 24 and the catalyst layer 26 is small.
As the conductive oxide semiconductor, FTO, ITO, AZO, IZO and GZO are preferable.

The thickness T24 of the counter electrode conductive layer 24 is appropriately determined in consideration of the material of the counter electrode conductive layer 24.
When the counter electrode conductive layer 24 is a conductive oxide semiconductor or metal, the thickness T24 of the counter electrode conductive layer 24 is preferably 10 to 50 nm. When the thickness T24 of the counter electrode conductive layer 24 is equal to or more than the above lower limit, it is easy to prevent the loss. If the thickness T24 of the counter electrode conductive layer 24 is equal to or less than the above upper limit, it is easy to increase the light transmittance.
When the counter electrode conductive layer 24 is carbon or a conductive transparent polymer, the thickness T24 of the counter electrode conductive layer 24 is preferably 100 to 500 μm. When the thickness T24 of the counter electrode conductive layer 24 is not less than the lower limit value, it is easy to prevent the loss. When the thickness T24 of the counter electrode conductive layer 24 is not more than the above upper limit value, the light transmittance can be further enhanced.
The method of measuring the thickness T24 of the counter electrode conductive layer 24 is, for example, the following method. The total thickness T23 of the counter electrode conductive layer 24 and the counter electrode support 22 is measured with a micrometer. The thickness T23 is measured at 10 arbitrary points, and the average value is defined as ave(T23). The thickness T22 of the counter electrode support 22 is measured with a micrometer. The thickness T22 at any 10 points is measured, and the average value is defined as ave(T22). The thickness T24 of the counter electrode conductive layer 24 is defined as ave(T23)−ave(T22).

The sheet resistance value of the counter electrode conductive layer 24 is preferably 120Ω/□ or less, more preferably 100Ω/□ or less, and further preferably 50Ω/□ or less. When the sheet resistance value is equal to or less than the upper limit value, the conductivity of the counter electrode conductive layer 24 can be increased. Further, if the sheet resistance value exceeds the upper limit value, the photoelectric conversion efficiency decreases due to the electric resistance.

The catalyst layer 26 is a layer containing a conductive substance having a resistivity of 1.0×10 ⁻⁴ Ωcm or less.
The catalyst layer 26 does not sufficiently exhibit conductivity derived from a conductive substance in the plane direction of the catalyst layer 26. Therefore, the sheet resistance value of the catalyst layer 26 is 120Ω/□ or more. The reason why the catalyst layer 26 exhibits such in-plane conductivity is not clear, but it is presumed as follows.
For example, when the catalyst layer 26 is formed with a conductive material in an amount smaller than that of the conventional catalyst layer, the catalyst layer 26 exhibits the above-mentioned conductivity, and thus it can be inferred that the catalyst layer 26 is uneven. That is, two or more films (conductive films) of a conductive substance having an arbitrary size are formed, these conductive films are separated from each other, and the counter electrode conductive layer 24 is exposed between the conductive films. Therefore, the catalyst layer 26, which is an assembly of conductive films that are separated from each other, does not sufficiently exhibit conductivity derived from the conductive substance in the surface direction of the surface 21.
Further, alternatively, since the conductive substances of the catalyst layer 26 are scattered to the extent that they do not conduct each other, the catalyst layer 26 does not sufficiently exhibit the conductivity derived from the conductive substance in the plane direction.

The conductive substance is, for example, a metal, a metal compound, a carbon material, or the like.
The conductive metal is, for example, platinum, titanium, gold, silver, copper, aluminum, cobalt, iron, magnesium, nickel, zinc or the like.
Examples of the conductive metal compound include titanium oxide, tin oxide, zinc oxide, gallium oxide, indium oxide, aluminum oxide, chromium oxide, cobalt oxide, copper oxide, iron oxide, titanium carbide, vanadium carbide, tungsten carbide, and titanium nitride. , Vanadium nitride, chromium nitride, niobium nitride, zirconium nitride, tantalum nitride, hafnium nitride, silicon nitride, gallium nitride, lithium nitride and the like.
The carbon material is, for example, carbon black, carbon nanotube, carbon fiber, activated carbon, graphite or the like.
The conductive substance is preferably a conductive metal, more preferably a platinum group metal (platinum, ruthenium, rhodium, palladium, osmium, iridium), titanium, gold or silver, more preferably a platinum group metal, and platinum is Particularly preferred.
These conductive substances may be used alone or in combination of two or more.

The content of the conductive material with respect to the total mass of the catalyst layer 26 is, for example, preferably 70 to 100% by mass, more preferably 80 to 100% by mass, and further preferably 90 to 100% by mass. When the content of the conductive substance is at least the above lower limit, the catalyst activity required for the catalyst layer 26 can be easily obtained.

The thickness T26 of the catalyst layer 26 is, for example, preferably 0.01 to 10 nm, more preferably 0.1 to 10 nm, and further preferably 0.1 to 5 nm. When the thickness T26 of the catalyst layer 26 is within the above range, the catalytic activity is further enhanced.
The thickness T26 of the catalyst layer 26 can be measured with an atomic force microscope, an electron microscope, a contact type film thickness meter, or the like.

The sheet resistance value of the catalyst layer 26 is preferably 120 to 1000 Ω/□, and more preferably 120 to 400 Ω/□. When the sheet resistance value of the catalyst layer 26 is within the above range, the catalytic activity of the catalyst layer 26 can be increased and the photoelectric conversion efficiency of the DSC 1 can be further increased. That is, in the plane direction of the surface 21, when the conductivity derived from the conductive material of the catalyst layer 26 is difficult to be exerted, the catalytic activity of the catalyst layer 26 is enhanced, and the photoelectric conversion efficiency of the DSC 1 can be further enhanced.
The reason why the catalyst activity can be enhanced when the sheet resistance value of the catalyst layer 26 is within the above range is not clear, but is presumed as follows.
Since the conventional catalyst layer is sufficiently thick, the surface is smooth. As described above, in the catalyst layer 26 of the present embodiment, the conductive films are separated from each other or the conductive substance is dispersed to the extent that the conductive material is not conductive. Therefore, it is considered that the surface 21 of the catalyst layer 26 has a higher specific surface area and higher catalytic activity than the conventional catalyst layer.

The following method can be exemplified as a method for measuring the sheet resistance value of the catalyst layer 26.
A base material having no conductivity (an insulating base material such as a glass base material) is prepared. When the catalyst layer 26 is formed, a sample is prepared by forming the catalyst layer on the insulating base material. The sheet resistance value of this sample is measured using a resistance measuring device.
Further, as another measuring method, the sheet resistance value of the electrode substrate (without the catalyst layer 26) on which the counter electrode conductive layer 24 is located on the counter electrode support 22 and the sheet resistance value of the counter electrode 20 are used as a catalyst. A method of calculating the sheet resistance value of the layer 26 can be exemplified.
Alternatively, after the sheet resistance value of the counter electrode 20 is measured, only the catalyst layer 26 is eluted or peeled off, and then the sheet resistance value of the counter electrode conductive layer 24 is measured to calculate the sheet resistance value of the catalyst layer 26. It can be illustrated.

The counter electrode 20 has catalytic activity due to the catalyst layer 26.
For example, the catalytic activity of the counter electrode 20 is preferably −0.31V or higher, more preferably −0.3V or higher, and even more preferably −0.29V or higher. When the catalytic activity is at least the above lower limit value, the photoelectric conversion efficiency of DSC1 can be further improved.
The catalytic activity is measured by the three-electrode method. The counter electrode is the working electrode, the platinum wire is the counter electrode, Ag/Ag ⁺ is the reference electrode, and the reduction current is measured by cyclic voltammetry (CV) under the conditions of a sweep speed of 50 mV/sec or less and a sweep voltage width of -1 to 1 V Find the value. The voltage at which the obtained reduction current value has a peak is taken as the catalyst activity value. The measurement solvent used for CV measurement is an acetonitrile solution containing iodine 1 mmol/L, lithium iodide 10 mmol/L, and lithium perchlorate 100 mmol/L.
The catalytic activity can be adjusted by a combination of the thickness of the catalyst layer 26, the type of conductive substance, the content of the conductive substance contained in the catalyst layer 26, and the like.

The photoelectrode 10 has a photoelectrode support 12, a photoelectrode conductive layer 14, and an inorganic semiconductor layer 16. The photoelectrode conductive layer 14 is located on the photoelectrode support 12. The inorganic semiconductor layer 16 is located on the photoelectrode conductive layer 14. That is, the photoelectrode support 12, the photoelectrode conductive layer 14, and the inorganic semiconductor layer 16 are located in this order.
The photoelectrode 10 and the counter electrode 20 face each other with the inorganic semiconductor layer 16 and the counter electrode conductive layer 24 facing each other.
The inorganic semiconductor layer 16 is in contact with the charge transfer body 30. The inorganic semiconductor layer 16 covers a part of the photoelectrode conductive layer 14. A part of the photoelectrode conductive layer 14 is in contact with the charge transfer body 30 outside the inorganic semiconductor layer 16.
The photoelectrode conductive layer 14 has an exposed portion 18 outside the sealing material 40. The exposed portion 18 is exposed to the outside of the DSC 1.

As with the thickness T20 of the counter electrode 20, the thickness T10 of the photoelectrode 10 is preferably 100 μm to 6 mm. The thickness T10 and the thickness T20 may be the same or different.

The material of the photoelectrode support 12 is, like the material of the counter electrode support 22, a glass plate, a resin plate, a film or sheet, a metal foil, or the like. When the photoelectrode 10 forms a light incident surface, the photoelectrode support 12 is light transmissive. In this case, a so-called transparent support is preferable as the photoelectrode support 12. The material of the photoelectrode support 12 may be the same as or different from the material of the counter electrode support 22.
Like the thickness T12 of the counter electrode support 22, the thickness T12 of the photoelectrode support 12 is preferably 10 μm to 5 mm. The thickness T12 of the photoelectrode support 12 may be the same as or different from that of the counter electrode support 22.

Like the material of the counter electrode conductive layer 24, the material of the photoelectrode conductive layer 14 is a metal, a conductive transparent inorganic material, a conductive transparent polymer, or the like. The photoelectrode conductive layer 14 and the counter electrode conductive layer 24 may be the same or different. When the photoelectrode 10 forms a light incident surface, the photoelectrode conductive layer 14 is light transmissive. In this case, the photoelectrode conductive layer 14 is preferably a so-called transparent conductive layer.
The thickness T14 of the photoelectrode conductive layer 14 is the same as the thickness T24 of the counter electrode conductive layer 24. The thickness T14 of the photoelectrode conductive layer 14 may be the same as or different from the thickness T24 of the counter electrode conductive layer 24.
The thickness T14 of the photoelectrode conductive layer 14 can be measured in the same manner as the thickness T24 of the counter electrode conductive layer 24.

The inorganic semiconductor layer 16 may be a semiconductor material capable of adsorbing a sensitizing dye. Examples of the semiconductor material include oxides of titanium oxide, zinc oxide, indium oxide, tin oxide, gallium oxide, tin sulfide, indium sulfide, zinc sulfide, cuprous oxide, molybdenum trioxide, vanadium pentoxide, and tungsten oxide. And the like, copper (I) thiocyanate, copper iodide, molybdenum disulfide, molybdenum diselenide, copper (I) sulfide, and the like.

The inorganic semiconductor layer 16 may be a dense layer or a porous layer. The inorganic semiconductor layer 16 is preferably a porous layer from the viewpoint of further improving the photoelectric conversion efficiency of the DSC 1. Furthermore, the inorganic semiconductor layer 16 is more preferably a porous layer in which fine particles are joined by sintering or physical collision by a powder spraying method.

The average particle size of the fine particles forming the inorganic semiconductor layer 16 is not particularly limited and is, for example, 10 to 500 nm. When the average particle diameter of the fine particles is within the above range, it is easy to increase the specific surface area of the inorganic semiconductor layer 16 and appropriately increase the utilization rate of incident light.
The average particle diameter of the fine particles is, for example, the peak value of the volume average diameter distribution obtained by measurement with a laser diffraction type particle size distribution measuring device. Further, for example, the average particle size of the fine particles is the average value of the major axis of any 10 fine particles. The major axis of the fine particles is a value obtained by SEM observation.

The specific surface area of the inorganic semiconductor layer 16 is preferably ^{10~200m 2 / g, 50~100m 2 /} g are preferred. When the specific surface area is at least the above lower limit, the amount of the sensitizing dye supported can be increased. When the specific surface area is not more than the above upper limit value, the strength of the inorganic semiconductor layer 16 can be increased. The specific surface area of the inorganic semiconductor layer 16 is a value obtained by the gas adsorption method.

The thickness T16 of the inorganic semiconductor layer 16 is, for example, preferably 1 to 40 μm, more preferably 3 to 30 μm, and further preferably 5 to 25 μm. When the thickness T16 of the inorganic semiconductor layer 16 is equal to or more than the above lower limit value, more light can be captured and power generation amount can be increased. If the thickness T16 of the inorganic semiconductor layer 16 is not more than the above upper limit value, it is easy to support the sensitizing dye on the inorganic semiconductor layer 16. In addition, if the thickness T16 of the inorganic semiconductor layer 16 is equal to or less than the above upper limit, the flexibility of the inorganic semiconductor layer 16 is likely to increase. Therefore, when the DSC 1 has flexibility, the inorganic semiconductor layer 16 is less likely to be damaged when the DSC 1 is bent.
The method of measuring the thickness T16 of the inorganic semiconductor layer 16 is, for example, the following method. The thickness T10 of the photoelectrode 10 is measured with a micrometer. The thickness T10 at any 10 points is measured, and the average value is defined as ave(T10). The total thickness T13 of the photoelectrode support 12 and the photoelectrode conductive layer 14 is measured with a micrometer. The thickness T13 at arbitrary 10 points is measured, and the average value thereof is defined as ave(T13). The thickness T16 of the inorganic semiconductor layer 16 is ave(T10)-ave(T13).

Sensitizing dyes include cis-di(thiocyanato)-bis(2,2'-bipyridyl-4,4'-dicarboxylic acid)ruthenium(II) (hereinafter sometimes referred to as N3), cis-di(thiocyanato)-. Bis-TBA salt of bis(2,2'-bipyridyl-4,4'-dicarboxylic acid)ruthenium(II) (hereinafter sometimes referred to as N719), cis-di(thiocyanato)-bis(2,2'- Bipyridyl-4,4'-dicarboxylic acid) ruthenium(II) tetra-TBA salt (hereinafter sometimes referred to as N712), tri(thiocyanato)-(4,4',4''-tricarboxy-2,2 ':6',2''-terpyridine)ruthenium tris-tetrabutylammonium salt (hereinafter sometimes referred to as N749), cis-di(thiocyanato)-(2,2'-bipyridyl-4,4'-dicarboxylic acid) Acid) (4,4′-bis(5′-hexylthio-5-(2,2′-bithienyl))bipyridyl)ruthenium(II) mono-tetrabutylammonium salt (hereinafter sometimes referred to as black dye), etc. Ruthenium dyes; various organics such as coumarin, polyene, cyanine, hemicyanine, thiophene, indoline, xanthene, carbazole, perylene, porphyrin, phthalocyanine, merocyanine, catechol and squarylium Dye: A donor-acceptor composite dye or the like in which these dyes are combined. Among them, the sensitizing dye preferably contains at least one of N3, N719 and N712, and more preferably at least one of N3, N719 and N712.
These sensitizing dyes may be used alone or in combination of two or more.

The amount of the sensitizing dye supported on the inorganic semiconductor layer 16 can be determined in consideration of the type of the sensitizing dye, the power generation capacity required for the DSC 1, and the like. The amount of the sensitizing dye carried on the inorganic semiconductor layer 16 is preferably 0.4×10 ^{−2 to} 2.0×10 ⁻² mmol/cm ³ , and 0.6×10 ^{−2 to} 1.2×10 ^−2. More preferred is mmol/cm ³ . When the amount of the sensitizing dye carried is at least the above lower limit, the photoelectric conversion efficiency of DSC1 can be further improved. When the amount of the sensitizing dye carried is within the above range, the inorganic semiconductor layer 16 carrying the dye transports an appropriate amount of carriers, and the photoelectric conversion efficiency can be further enhanced. When the amount of the sensitizing dye carried is equal to or more than the above lower limit, the amount of carriers generated with respect to the amount of incident light increases, and the photoelectric conversion efficiency further increases. When the amount of the sensitizing dye carried is equal to or less than the above upper limit, the amount of the sensitizing dye adsorbed on the semiconductor surface becomes a proper amount, carrier transportation becomes good, and photoelectric conversion efficiency can be further enhanced.
The volume of the inorganic semiconductor layer 16 is a value obtained by multiplying the area calculated by measuring the length and width with a caliper or a ruler and the thickness T16 measured by the above method.

The charge transfer body 30 is an electrolytic solution, a gel electrolytic solution, or a hole transporter. The charge transfer body 30 of this embodiment is in contact with the inorganic semiconductor layer 16, the photoelectrode conductive layer 14, and the counter electrode conductive layer 24. The charge transfer body 30 has a redox pair capable of supplying electrons to the sensitizing dye.

The electrolytic solution has a redox couple capable of reducing the sensitizing dye and a solvent (particularly sometimes referred to as “electrolytic solution solvent”). The gel electrolyte is a gel electrolyte. In the method for producing the gel electrolyte solution, for example, a gelling agent or a thickening agent is added to the electrolyte solution to form a gel or solid state. If necessary, the solvent of the gel charge carrier is removed. The gel electrolyte charge transfer body 30 can enhance the durability of the DSC 1.
The solid hole transporter is a P-type semiconductor capable of reducing the sensitizing dye. The charge carrier 30 of the solid hole transporter can enhance the durability of the DSC 1.

The electrolytic solution solvent is a non-aqueous solvent, an ionic liquid, or the like. The non-aqueous solvent is acetonitrile, propionitrile, gamma butyrolactone or the like. The ionic liquid is dimethylpropylimidazolium iodide, butylmethylimidazolium iodide, or the like.

A redox couple is a combination of a supporting electrolyte and halogen molecules.
The supporting electrolytes include metal iodides such as lithium iodide, sodium iodide and potassium iodide, iodides such as tetraalkylammonium iodide, pyridinium iodide, iodide salts such as imidazolium iodide; sodium bromide, bromide. Examples thereof include metal bromides such as potassium, bromine compounds such as bromine salts such as tetraalkylammonium bromide, pyridinium bromide and imidazolium bromide.
Halogen molecules are iodine molecules, bromine molecules and the like.
As the combination of the supporting electrolyte and the halogen molecule, the combination of iodide and iodine molecule and the combination of bromine compound and bromine molecule are preferable.

The content of the supporting electrolyte with respect to the total volume of the charge transfer body 30 can be determined in consideration of the type of the supporting electrolyte and the like. The content of the supporting electrolyte with respect to the total volume of the charge transfer body 30 is, for example, preferably 0.01 to 10 mmol/L, more preferably 0.05 to 5 mmol/L.
The content of halogen molecules with respect to the total volume of the charge transfer body 30 can be determined in consideration of the content of the supporting electrolyte and the like. The content of halogen molecules with respect to the total volume of the charge transfer body 30 is preferably 0.001 to 0.2 mmol/L.

The charge transfer body 30 may include an acidic additive and a basic additive. Examples of the basic additive include pyridine, t-butylpyridine, pyrazole, and 3,5-dimethylpyrazole. Examples of the acidic additive include potassium iodide, tributyl borate and the like. Since the charge transfer body 30 contains the above-mentioned additive, it is easy to prevent a reverse electron transfer reaction.

The sealing material 40 is located between the photoelectrode 10 and the counter electrode 20. The sealing material 40 surrounds an arbitrary region in plan view and seals the charge transfer body 30.
The encapsulant 40 may be a conventionally known encapsulant such as a photocurable resin or a thermosetting resin as long as it can seal the charge transfer body 30.
The thickness T40 of the sealing material 40 can be determined in consideration of the thickness T16 of the inorganic semiconductor layer 16. The thickness T40 is, for example, preferably 5 to 200 μm, more preferably 10 to 150 μm, still more preferably 15 to 100 μm.

(Production method)
The method for manufacturing an electrode for a solar cell of the present invention has a step of forming a catalyst layer on the conductive layer.
The method for producing a DSC of the present invention includes a step of providing a photoelectrode facing the catalyst layer of the counter electrode and providing a charge transfer body between the photoelectrode and the counter electrode.
Hereinafter, an example of a method for manufacturing a solar cell electrode and a DSC will be described by taking the DSC 1 of FIG. 1 as an example.
The manufacturing method of DSC1 of this example has an electrode manufacturing process and an assembly process.

<Electrode manufacturing process>
The electrode manufacturing process of this embodiment is a method of manufacturing the counter electrode 20.
Hereinafter, the electrode manufacturing process will be described.
The electrode manufacturing process of this example is a process of providing a catalyst layer on the electrode substrate. The electrode substrate has a conductive layer on one surface of the support.
The electrode substrate may be a commercially available electrode or an electrode substrate manufactured by the following method.
The counter electrode conductive layer 24 is formed on one surface of the counter electrode support 22. The method of forming the counter electrode conductive layer 24 is a known method such as a sputtering method or a printing method.

Next, the catalyst layer 26 is formed on the counter electrode conductive layer 24. As a method for forming the catalyst layer 26, a conventionally known method for forming a catalyst layer can be exemplified. As a method for forming the catalyst layer 26, for example, a sputtering method, a vapor deposition method, etc. can be exemplified, and a sputtering method is preferable. With the sputtering method, the thickness of the catalyst layer 26 can be easily adjusted. In addition, if the sputtering method is used, it is easy to form the catalyst layer 26 in spots.
In the method for forming a catalyst layer 26, the amount of conductive material to the electrode substrate is preferably ^{0.1~50g / m 2, 0.1~10g / m} 2 is more preferable.
The counter electrode 20 is obtained through the above electrode manufacturing steps.

<Assembly process>
The assembly step is a step of incorporating the counter electrode 20 to obtain the DSC 1.
The assembly process includes, for example, an operation of providing the photoelectrode 10 facing the counter electrode 20 (electrode arrangement operation) and an operation of providing the charge transfer body 30 between the photoelectrode 10 and the counter electrode 20 (sealing operation). Have.

The electrode arrangement operation is an operation in which the inorganic semiconductor layer 16 and the counter electrode conductive layer 24 are opposed to each other and the photoelectrode 10 and the counter electrode 20 are opposed to each other with a space therebetween.
The photoelectrode 10 can be manufactured by, for example, a method of providing the inorganic semiconductor layer 16 on the electrode substrate.
The electrode substrate may be a commercially available electrode or an electrode substrate manufactured by the following method.

The photoelectrode conductive layer 14 is formed on one surface of the photoelectrode support 12 to form an electrode substrate. The method for forming the photoelectrode conductive layer 14 is a known method such as a sputtering method or a printing method.

The inorganic semiconductor layer 16 is formed on the photoelectrode conductive layer 14 of the electrode substrate. The method of forming the inorganic semiconductor layer 16 includes a method of spraying particles of a semiconductor material onto the photoelectrode conductive layer 14. A method of spraying particles of a semiconductor material to form the inorganic semiconductor layer 16 is an aerosol deposition method or the like. Further, for example, a method of forming the inorganic semiconductor layer 16 is a method of applying a paste containing a semiconductor material on the photoelectrode conductive layer 14, and firing the applied paste to form the inorganic semiconductor layer 16.

A solution containing a sensitizing dye (hereinafter sometimes referred to as "dye solution") is prepared.
The solvent in which the sensitizing dye is dispersed is, for example, alcohol, nitrile, ether, ester, ketone, hydrocarbon, halogenated hydrocarbon or the like.
The alcohol is methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, t-butyl alcohol, ethylene glycol or the like.
Nitriles include acetonitrile, propionitrile and the like.
The ether is dimethyl ether, diethyl ether, ethyl methyl ether, tetrahydrofuran or the like.
Esters are ethyl acetate, propyl acetate, butyl acetate and the like.
The ketone is acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, or the like.
Hydrocarbons are pentane, hexane, heptane, octane, cyclohexane, toluene, xylene and the like.
The halogenated hydrocarbon is methylene chloride, chloroform and the like.
These dispersion media may be used alone or in combination of two or more.

The dye solution is brought into contact with the inorganic semiconductor layer 16. The dye solution in contact with the inorganic semiconductor layer 16 penetrates into the surface or inside of the inorganic semiconductor layer 16. After the desired amount of the dye solution has penetrated into the inorganic semiconductor layer 16, the dye solution dispersion medium is removed and the sensitizing dye is carried on the inorganic semiconductor layer 16. In this way, the photoelectrode 10 is obtained.

The method of bringing the dye solution into contact with the inorganic semiconductor layer 16 includes a method of applying the dye solution to the inorganic semiconductor layer 16 (coating method), a method of spraying the dye solution onto the inorganic semiconductor layer 16 (spraying method), and an inorganic semiconductor layer 16 A method of immersing the electrode substrate having it in a dye solution (immersion method) and the like.

The sealing operation is an operation of providing the charge transfer body 30 between the photoelectrode 10 and the counter electrode 20. For the sealing operation, for example, the sealing material 40 is provided on the surface of the photoelectrode 10 on which the inorganic semiconductor layer 16 is located. Next, the charge transfer body 30 is arranged in the region surrounded by the sealing material 40. The region surrounded by the sealing material 40 is covered with the counter electrode 20, and the sealing material 40 is cured to seal the charge transfer body 30. At this time, the distance between the photoelectrode 10 and the counter electrode 20 can be adjusted by changing the thickness of the sealing material 40.
If necessary, take-out wiring is connected to the exposed portion 18 and the exposed portion 28.

As described above, since the DSC of this embodiment has the specific counter electrode, the photoelectric conversion efficiency can be further increased.

The invention is not limited to the embodiments described above.
The above-described embodiment has one region (cell) surrounded by the sealing material. The present invention is not limited to this, and may form a DSC unit in which two or more DSCs 1 are connected in parallel or in series.
For example, when two or more DSCs 1 are connected in series, the exposed portion 18 of one DSC 1 and the exposed portion 28 of the other DSC 1 are electrically connected. As a method of connecting the exposed portion 18 and the exposed portion 28, for example, a method of connecting both exposed portions with a conductive material containing conductive particles and an adhesive, a method of connecting both exposed portions with a conductive wire, and the like are known. A method can be illustrated.

In the embodiment described above, the photoelectrode 10 has a photoelectrode support 12. The present invention is not limited to this, and the photoelectrode 10 may not have the photoelectrode support 12.
In the above-described embodiment, the counter electrode 20 has the counter electrode support 22. The present invention is not limited to this, and the counter electrode 20 may not have the counter electrode support 22.

In the above-described embodiment, a part of the photoelectrode conductive layer 14 is in contact with the charge transfer body 30 outside the inorganic semiconductor layer 16. The present invention is not limited to this, and the inorganic semiconductor layer 16 may cover the entire surface of the photoelectrode conductive layer 14 in the region where the charge transfer body 30 is present.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to these Examples.

(Examples 1-4, Comparative Examples 1-2)
A porous paste was applied onto the FTO film by a screen printing method on a glass substrate having a surface resistance of 40 Ω provided with a photoelectrode conductive layer (FTO film) to obtain a paste applied body. The porous paste is a paste composed of 19% by mass of titanium oxide particles (average particle size 14 nm), 9% by mass of ethyl cellulose, and 72% by mass of terpineol. The area coated with the porous paste had an area of 4 mm×4 mm. The paste application body was baked at 500° C. for 30 minutes in an air atmosphere to obtain a photoelectrode precursor having a porous layer (film thickness 10 μm) on the photoelectrode conductive film.
The sensitizing dye N719 was dissolved in a 1:1 (volume basis) mixed solution of acetonitrile and tert-butanol to obtain a dye solution having a concentration of 0.3 mmol/L. The photoelectrode precursor was immersed in the dye solution for 20 hours. Then, the photoelectrode precursor was washed with acetonitrile. The photoelectrode was produced by the above operation.

An injection hole for injecting an electrolytic solution was formed in an electrode substrate having a counter electrode conductive layer (FTO film) formed on a counter electrode support. On the FTO film of this electrode substrate, a catalyst layer having a thickness shown in Table 1 was formed with a conductive substance shown in Table 1 by a sputtering method to obtain a counter electrode of each example. Further, a film was simultaneously formed on the electrode substrate at the same time as the formation of the counter electrode to prepare a sample for sheet resistance measurement.
The sheet resistance value and the catalyst activity value of the sample for measuring the sheet resistance value of each example were measured, and the results are shown in Table 1.

Iodine and 1,3-dimethyl-2-propylimidazolium iodide were dissolved in γ-butyrolactone to prepare an electrolytic solution. The concentration of iodine in the electrolytic solution was 0.05 mol/L. The concentration of 1,3-dimethyl-2-propylimidazolium iodide in the electrolytic solution was 1.0 mol/L.

A thermosetting encapsulant composition was arranged on the periphery of the inorganic semiconductor layer in the photoelectrode, and the inorganic semiconductor layer was surrounded by the encapsulant composition. The catalyst layer was opposed to the inorganic semiconductor layer, and the counter electrode was placed on the encapsulant composition. Then, the encapsulant composition was heated and cured to obtain an encapsulant having a thickness of 50 μm. The electrolytic solution was injected into the inside through an injection hole formed in the counter electrode. The injection hole was sealed to obtain the DSC of each example (assembly process).
The photoelectric conversion efficiency of each DSC was measured, and the results are shown in Table 1.

(Measuring method)
<Sheet resistance value>
The sheet resistance value of the sample for sheet resistance measurement of each example was measured with a 4-terminal measuring device (model number: Loresta GP MCP-T610, manufactured by Mitsubishi Chemical Analytech Co., Ltd.). The sheet resistance value of the counter electrode conductive layer is a value measured before forming the catalyst layer. The sheet resistance value of the counter electrode is a value measured after forming the catalyst layer. The sheet resistance value of the catalyst layer was calculated by the following equation (1).

Sheet resistance value of catalyst layer (Ω/□)=(sheet resistance value of counter electrode conductive layer)/{(sheet resistance value of counter electrode conductive layer/sheet resistance value of counter electrode)-1} (1)

<Catalytic activity>
The catalyst activity value was measured for the sheet resistance measurement sample of each example. It can be evaluated that the higher the voltage value, the higher the catalytic activity.

<Photoelectric conversion efficiency>
With respect to the DSC of each example, a solar simulator (model number: XES-301S, manufactured by Sanei Denki Seisakusho Co., Ltd.) was used to measure the photoelectric conversion efficiency under irradiation with pseudo sunlight having a light intensity of 100 mW/cm ² .

As shown in Table 1, in Examples 1 to 3 to which the present invention was applied, the photoelectric conversion efficiency was higher than in Comparative Examples 1 and 2.
From these results, it was confirmed that the photoelectric conversion efficiency can be further increased by applying the present invention.

DESCRIPTION OF SYMBOLS 1 Dye-sensitized solar cell, 10 photoelectrodes, 12 photoelectrode supports, 14 photoelectrode conductive layers, 16 inorganic semiconductor layers, 20 counter electrodes, 22 counter electrode supports, 24 counter electrode conductive layers, 26 catalyst layers, 30 Charge transfer body, 40 sealing material

Claims (7)

A conductive layer and a catalyst layer which is located on the conductive layer and forms a surface,
The catalyst layer contains a conductive material having a resistivity of 1.0×10 ⁻⁴ Ωcm or less,
A sheet resistance value of the catalyst layer is 120 Ω/□ or more, an electrode for a solar cell. The solar cell electrode according to claim 1, wherein the catalyst layer has a catalytic activity value of −0.31 V (Ag/Ag ⁺ ) or more, which is determined by the following measurement conditions.
<Method of measuring catalytic activity value>
In the three-electrode method, an opposite electrode was used as a working electrode, a platinum wire was used as a counter electrode, Ag/Ag ⁺ was used as a reference electrode, and an acetonitrile solution containing 1 mmol/L of iodine, 10 mmol/L of lithium iodide and 100 mmol/L of lithium perchlorate was prepared. The reduction current value is measured by cyclic voltammetry measurement under the conditions of a measurement solvent, a sweep speed of 50 mV/sec or less, and a sweep voltage width of −1 to 1 V, and the voltage at which the reduction current value reaches a peak is defined as the catalyst activity value. The solar cell electrode according to claim 1 or 2, wherein the catalyst layer is formed in spots or is scattered to such an extent that the conductive substances are not electrically connected to each other . The solar cell electrode according to claim 1, wherein the conductive layer is made of an oxide semiconductor. The solar cell electrode according to any one of claims 1 to 4 is used as a counter electrode, a photoelectrode facing the catalyst layer of the counter electrode, and a charge located between the counter electrode and the photoelectrode. A dye-sensitized solar cell having a moving body. It is a manufacturing method of the electrode for solar cells as described in any one of Claims 1-4, Comprising: The manufacturing method of the electrode for solar cells which forms the said catalyst layer on the said conductive layer by sputtering or vapor deposition. The solar cell electrode is obtained by the method for manufacturing a solar cell electrode according to claim 6, the obtained solar cell electrode is used as a counter electrode, and a photoelectrode facing the catalyst layer of the counter electrode is provided. A method of manufacturing a dye-sensitized solar cell, wherein a charge transfer body is provided between the photoelectrode and the counter electrode.

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