JP2013149526A - Photoelectric conversion element and dye-sensitized solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoelectric conversion element excellent in photoelectric conversion efficiency, and a dye-sensitized solar cell.SOLUTION: The photoelectric conversion element comprises a photoelectric conversion layer in which a dye compound of chemical formula (I) is adsorbed to a semiconductor layer. In the formula (I), R is any of -CF, -CN, -OCH, and -SCH.

Description

  The present invention relates to a photoelectric conversion element and a dye-sensitized solar cell.

  As an energy source to replace fossil fuels, solar cells that convert sunlight into electric power have attracted 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 production cost of the silicon substrate is high. The latter thin-film silicon solar cell has a problem that the manufacturing cost increases because it is necessary to use various semiconductor manufacturing gases and complicated apparatuses. For this reason, although efforts have been made to reduce the cost per power generation output by increasing the efficiency of photoelectric conversion in any of the solar cells, the above problem has not been solved.

  As a new type of solar cell, a dye-sensitized solar cell including a photoelectric conversion element applying photoinduced electron transfer of a metal complex has been proposed (for example, Patent Document 1). This dye-sensitized solar cell includes an electrode (first electrode) having a photoelectric conversion layer configured by adsorbing a dye compound to a semiconductor layer, a second electrode serving as a counter electrode of the first electrode, and a liquid electrolyte. And a carrier transport layer. When such a dye-sensitized solar cell is irradiated with light, electrons are generated in the photoelectric conversion layer, the generated electrons move to the second electrode through the external electric circuit, and the electrons moved to the second electrode It is carried by the ions in the liquid electrolyte and returns to the photoelectric conversion layer. Electrical energy is extracted by such a series of electron flows.

Since the semiconductor material (for example, TiO ₂ ) used for the photoelectric conversion layer has a large band gap energy, the semiconductor material alone can use only the ultraviolet component of sunlight. Therefore, the photoelectric conversion layer contains a dye compound, and photoelectric conversion using visible light of sunlight can be realized by the sensitizing action of the dye compound.

  In such a dye-sensitized solar cell, it is known that the photoelectric conversion efficiency greatly depends on the dye compound. As the dye compound, for example, a dye compound called “N3” represented by the following chemical formula (XI) or a dye compound called “N719” represented by the following chemical formula (XII) is known. Note that TBA in the following chemical formula (XII) represents tetrabutylammonium.

Japanese Patent Laid-Open No. 01-220380

In dye-sensitized solar cells, further improvement in photoelectric conversion efficiency is required.
This invention is made | formed in view of this point, The objective is to provide the photoelectric conversion element and dye-sensitized solar cell excellent in photoelectric conversion efficiency.

The photoelectric conversion element according to the present invention includes a photoelectric conversion layer configured by adsorbing a dye compound represented by the following chemical formula (I) to a semiconductor layer. In the following chemical formula (I), R is any of —CF ₃ , —CN, —OCH ₃ , and —SCH ₃ .

  The dye-sensitized solar cell according to the present invention is a first electrode including a photoelectric conversion layer configured by adsorbing the dye compound represented by the chemical formula (I) to a semiconductor layer, and a counter electrode of the first electrode. A second electrode; and a carrier transport layer provided between the first electrode and the second electrode.

  In the photoelectric conversion element and the dye-sensitized solar cell according to the present invention, the photoelectric conversion efficiency can be further improved.

It is sectional drawing which shows an example of a structure of the dye-sensitized solar cell of this invention.

  Hereinafter, the photoelectric conversion element and the dye-sensitized solar cell 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.

<Photoelectric conversion element>
The photoelectric conversion element of the present invention has a photoelectric conversion layer constituted by adsorbing a dye compound to a semiconductor layer, and the dye compound is represented by the above chemical formula (I). In the above chemical formula (I), R is any one of —CF ₃ , —CN, —OCH ₃ , and —SCH ₃ . The dye compound represented by the chemical formula (I) contributes to the provision of a photoelectric conversion element excellent in photoelectric conversion efficiency. Therefore, in this invention, the photoelectric conversion efficiency of a photoelectric conversion element can be improved.

[Configuration of semiconductor layer]
The semiconductor layer used for the photoelectric conversion layer of the photoelectric conversion element of this invention consists of semiconductor materials. Examples of the form of the semiconductor layer include a layer containing a particulate semiconductor material and a film shape (porous semiconductor layer) in which a large number of micropores are formed. Preferably there is. Thereby, the adsorption amount of the dye compound and the like can be sufficiently ensured.

From the viewpoint of sufficiently securing the adsorption amount of the coloring compound, the specific surface area of the semiconductor layer is preferably about 10 to 200 m ² / g. Here, the specific surface area of the semiconductor layer is determined by a BET method which is a gas adsorption method.

The semiconductor material constituting the semiconductor layer is not particularly limited as long as it is generally used for a photoelectric conversion material. Examples of such materials include titanium oxide, zinc oxide, tin oxide, iron oxide, niobium oxide, cerium oxide, tungsten oxide, nickel oxide, zirconium oxide, strontium titanate, cadmium sulfide, lead sulfide, zinc sulfide, and phosphorus. And compounds such as indium phosphide, copper-indium sulfide (CuInS ₂ ), CuAlO ₂ , or SrCu ₂ O ₂ . These compounds may be used alone, or these compounds may be used in combination. Among these compounds, it is preferable to use titanium oxide, zinc oxide, tin oxide, or niobium oxide. In terms of photoelectric conversion efficiency, stability, and safety, it is more preferable to use titanium oxide.

  In the present invention, when titanium oxide is used as a material constituting the semiconductor layer, the titanium oxide is oxidized in various narrow sense such as anatase type titanium oxide, rutile type titanium oxide, amorphous titanium oxide, metatitanic acid, or orthotitanic acid. It may be titanium, titanium hydroxide, or hydrous titanium oxide. These 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. In particular, in terms of improving the sensitizing action of the dye compound, the content of anatase-type titanium oxide in the semiconductor layer is preferably high, for example 80% or more.

  The semiconductor material constituting the semiconductor layer is preferably a polycrystalline sintered body made of fine particles (the fine particles are made of a semiconductor material) from the viewpoints of stability, ease of crystal growth, and reduction in manufacturing cost. .

  The average particle size of the semiconductor material is not particularly limited, but is preferably set appropriately in consideration that the light scattering property of the photoelectric conversion layer can be adjusted by the average particle size of the semiconductor material, for example, about 1 to 500 nm. Preferably there is. The semiconductor layer may be made of a semiconductor material having the same average particle diameter, or may be configured by mixing a semiconductor material having a relatively large average particle diameter and a semiconductor material having a relatively small average particle diameter. good. In the present specification, the average particle diameter is a value measured by SEM observation.

  When the semiconductor layer includes a semiconductor material having a relatively large average particle size and a semiconductor material having a relatively small average particle size, the semiconductor layer is composed of a layer made of a semiconductor material having a relatively large average particle size and an average particle size. It is preferable that a layer made of a semiconductor material having a relatively small diameter is laminated. A layer made of a semiconductor material having a relatively large average particle diameter is excellent in light scattering properties, and thus scatters incident light and contributes to an improvement in light capture rate. On the other hand, a layer made of a semiconductor material having a relatively small average particle size increases the adsorption point of the dye compound, and thus contributes to an increase in the adsorption amount of the dye compound. In terms of an increase in the amount of the dye compound adsorbed, it is preferable to use a semiconductor material having a relatively small average particle diameter as a semiconductor material having an excellent action of adsorbing the dye compound. In addition, in terms of maximum utilization of incident light inside the dye-sensitized solar cell, a layer made of a semiconductor material having a relatively small average particle size (low scattering layer) and a semiconductor having a relatively large average particle size It is preferable that a layer made of a material (high scattering layer) is provided in order from the light incident side.

  The semiconductor material having a relatively small average particle diameter preferably has an average particle diameter of 5 nm to 50 nm, and preferably has an average particle diameter of 10 nm to 30 nm. Thereby, since an effective surface area sufficiently large with respect to the projected area can be obtained, an effect that incident light can be converted into electric energy with high yield can be obtained. Further, the semiconductor material having a relatively large average particle diameter preferably has an average particle diameter that is 10 times or more the average particle diameter of the semiconductor material having a relatively small average particle diameter, and more preferably 100 nm to 500 nm. Having an average particle size.

  Although the film thickness of a semiconductor layer is not specifically limited, From a viewpoint of photoelectric conversion efficiency, it is preferable that it is about 0.5-50 micrometers. The width of the semiconductor layer is not particularly limited, but is preferably about 1 to 20 mm.

[Method of forming semiconductor layer]
In the present invention, the semiconductor layer is preferably formed on a conductive support, for example. The formation method of a semiconductor layer is not specifically limited, It is preferable that it is either of following (1)-(4). The following (1) is preferably used in that a thick semiconductor layer can be formed at low cost. (1) A paste containing particles made of a semiconductor material is applied on a conductive support by a screen printing method or an inkjet method. (2) A semiconductor layer is formed on the conductive support by a CVD method or a MOCVD method using a desired source gas. (3) PVD method, vapor deposition method, or A semiconductor layer is formed on the conductive support by sputtering or the like. (4) A semiconductor layer is formed on the conductive support by a sol-gel method or a method using an electrochemical oxidation-reduction reaction.

A method for forming a semiconductor layer in the case where titanium oxide is used as a semiconductor material is described below.
First, 125 mL of titanium isopropoxide (manufactured by Kishida Chemical Co., Ltd.) is dropped into 750 mL of a 0.1 M aqueous nitric acid solution (manufactured by Kishida Chemical Co., Ltd.) and hydrolyzed, and then heated at 80 ° C. for 8 hours. Thereby, a sol liquid is prepared. The obtained sol solution is heated at 230 ° C. for 11 hours in a titanium autoclave to grow titanium oxide particles, subjected to ultrasonic dispersion for 30 minutes, and contains titanium oxide particles having an average particle size (average primary particle size) of 15 nm. Prepare a colloidal solution. To the obtained colloid solution, ethanol twice the volume of the colloid solution is added, and this is centrifuged at a rotational speed of 5000 rpm. Thereby, titanium oxide particles are obtained.

  Next, the obtained titanium oxide particles are washed. Thereafter, the titanium oxide particles are mixed with ethyl cellulose and terpineol dissolved in absolute ethanol and stirred. Thereby, the titanium oxide particles are dispersed. Thereafter, the mixed solution is heated under vacuum to evaporate ethanol to obtain a titanium oxide paste. As the final composition, for example, each concentration is adjusted so that the titanium oxide solid concentration is 20 wt%, the ethyl cellulose concentration is 10 wt%, and the terpineol concentration is 64 wt%.

  Here, as the solvent used for preparing the titanium oxide paste, in addition to the above, a glyme solvent such as ethylene glycol monomethyl ether, an alcohol solvent such as isopropyl alcohol, a mixed solvent such as isopropyl alcohol / toluene, or water is used. Can be mentioned. These solvents can also be used when preparing a paste containing semiconductor particles other than titanium oxide.

  Next, a titanium oxide paste is applied on the conductive layer by the above method, dried, and fired. Thereby, a semiconductor layer made of titanium oxide is obtained. Here, drying conditions and firing conditions, for example, conditions such as temperature, time, or atmosphere, are appropriately adjusted depending on the material of the support or the semiconductor material to be used. Firing is preferably performed, for example, in an air atmosphere or an oxygen gas atmosphere within a range of about 50 to 800 ° C. (preferably within a range of 50 to 550 ° C.) for about 10 seconds to 12 hours. Moreover, each of drying and baking may be performed once at a single temperature, or may be performed twice or more at different temperatures.

[Dye compound]
The dye compound represented by the chemical formula (I) is, for example, a bis (4,4′-dicboxy-2,2′-bipyridine) 2- (4-trifluoromethylphenyl) pyridine ruthenium (II) represented by the following chemical formula (II). It may be a TBA salt of the following chemical formula (II). Hereinafter, an example of a method for synthesizing these dye compounds will be described.

[Bis (4,4′-dicarboxy-2,2′-bipyridine] Synthesis Method of 2- (4-trifluoromethylphenyl) pyridine Ruthenium (II)]
The dye compound represented by the chemical formula (II) is synthesized using cis-dichroro-bis (4,4′-dicboxy-2,2′-bipyridine) Ruthenium represented by the following chemical formula (III). Is preferred. Below, after showing the synthesis | combining method of the compound represented by following Chemical formula (III), the synthesis | combining method of the compound represented by the said Chemical formula (II) using the compound represented by the following Chemical formula (III) is shown.

1. cis-dichloro-bis (4,4'-dicboxy-2,2'-bipyridine) Synthesis of Ruthenium -4,4'-dicboxylic Acid, 3.14 g (5.1 mmol) of Dichroro (p-cymene) -ruthenium (II) dimer, and 240 mL of dimethylformamide were added at 1.70 ° C. under a nitrogen atmosphere. Stir for 5 hours. After cooling the reaction vessel (three-necked flask) with air, the reaction solution is filtered, and the obtained filtrate is concentrated under reduced pressure at 90 ° C. Thereby, the target crude product is obtained.

  200 mL of acetone is added to the resulting crude product. The precipitated components are collected by suction filtration, washed with acetone, and then vacuum dried. As a result, 6.61 g (yield 98%) of cis-dichroro-bis (4,4′-dicarboxy-2,2′-bipyridine) Ruthenium is obtained.

The present inventors have measured the ¹ H-NMR spectrum and IR absorption spectrum of the compound obtained by the above method and confirmed that the target compound has been obtained. The measurement result of ¹ H-NMR spectrum is as follows.

Chemical shifts of peaks appearing in ¹ H-NMR spectrum (solvent: d6-DMSO) σ: 10.08 ppm (hydrogen on pyridine ring, 2H), 9.03 ppm (hydrogen on pyridine ring, 2H), 8.86 ppm (pyridine) Ring hydrogen, 2H), 8.21 ppm (hydrogen on pyridine ring, 2H), 7.73 ppm (hydrogen on pyridine ring, 2H), 7.47 ppm (hydrogen on pyridine ring, 2H).

2. bis (4,4′-dicarboxy-2,2′-bipyridine) Synthesis of 2- (4-trifluoromethyl) pyridine Ruthenium (II) In a 500 mL three-necked flask, 1.32 g (2.00 mmol) of cis-Dichloro-bis ( 4,4′-dicarboxy-2,2′-bipyridine) Ruthenium (a compound obtained according to the above synthesis method), 0.92 g (4.1 mmol) of 2- [4- (Trifluoromethyl) phenyl] pyridine, Add 250 mL of ethylene glycol and stir at 170 ° C. for 1.5 hours under nitrogen atmosphere. After cooling the resulting reaction solution to room temperature, 8.8 mL of 37% tetrabutylammonium hydroxide-methanol solution is added to the reaction solution, and the mixture is stirred at 170 ° C. for 7 hours under a nitrogen atmosphere. The reaction vessel is air-cooled and the reaction solution is filtered. The obtained filtrate is concentrated under reduced pressure at 90 ° C. and 2 mmHg, and then the solvent is distilled off. 100 mL of distilled water is added to the residue after the solvent is distilled off and stirred, and then a 0.5N aqueous nitric acid solution is further added to adjust the pH of the solution to 1.8. This solution is allowed to stand at room temperature for 12 hours, and the precipitated crystals are collected by suction filtration. The obtained crystals are washed with distilled water and ethyl acetate and then vacuum-dried. This gives 1.11 g of crude crystals.

  The resulting crude crystals are purified with a Sephadex (registered trademark) column. Specifically, first, components that flow out are removed using distilled water as an eluent, and then components that flow out are collected using a 1N sodium hydroxide aqueous solution as an eluent. The separated component is distilled off under reduced pressure to remove the solvent, and the residue is dissolved in 60 mL of distilled water. The pH of the solution is adjusted to 1.8 by adding a 0.5N aqueous nitric acid solution to the solution in which the residue is dissolved. This solution is allowed to stand at room temperature for 12 hours, and the precipitated crystals are collected by suction filtration. The collected crystals are washed with distilled water and then vacuum-dried. Thereby, 0.51 g of the target product (crystal) is obtained.

The present inventors measured the ¹ H-NMR spectrum, ¹⁹ F-NMR spectrum, and IR absorption spectrum of the compound obtained by the above method and conducted LC-MS to obtain the desired compound. Make sure that The measurement results of ¹ H-NMR spectrum, ¹⁹ F-NMR spectrum, and IR absorption spectrum are as shown below.

Chemical shift of peak appearing in ¹ H-NMR spectrum (solvent: d4-MeOH-MeONa) σ: 9.02 ppm (hydrogen on aromatic ring, 1H), 8.95 ppm (hydrogen on aromatic ring, 1H), 8.92 ppm (Hydrogen on aromatic ring, 1H), 8.89 ppm (hydrogen on aromatic ring, 1H), 8.19 ppm (hydrogen on aromatic ring, 1H), 8.04 ppm (hydrogen on aromatic ring, 1H), 8.00 ppm (aromatic Ring hydrogen, 1H), 7.86 ppm (hydrogen on aromatic ring, 2H), 7.78 ppm (hydrogen on aromatic ring, 3H), 7.71 ppm (hydrogen on aromatic ring, 1H), 7.67 ppm (on aromatic ring) Hydrogen, 1H), 7.63 ppm (hydrogen on aromatic ring, 2H), 7.13 ppm (hydrogen on aromatic ring, 1H), 7.05 ppm (hydrogen on aromatic ring, 1H), 6.66 ppm (hydrogen on aromatic ring, 1H).

Chemical shift σ of peak appearing in ¹⁹ F-NMR spectrum (solvent: d4-MeOH-MeONa): -64.3 ppm.

Peak wave numbers of peaks appearing in the IR absorption spectrum (measured by the KBr tablet method): 3090 cm ⁻¹ , 2879 cm ⁻¹ , 2821 cm ⁻¹ , 1941 cm ⁻¹ , 1716 cm ⁻¹ , 1604 cm ⁻¹ , 1540 cm ⁻¹ , 1471 cm ⁻¹ , ^{1405cm -1, 1375cm -1, 1317cm -1} , 1255cm -1, 1230cm -1, 1159cm -1, 1116cm -1, 1072cm -1, 1006cm -1, 894cm -1, 769cm -1, 682cm -1.

[Method for producing TBA (tetrabutylammonium) salt of Bis (4,4′-dicboxy-2,2′-bipyridine) 2- (4-trifluoromethylphenyl) pyridine Ruthenium (II)]
To the synthesized 240 mg (0.30 mmol) of bis (4,4′-dicarboxy-2,2′-bipyridine) 2- (4-trifluoromethylphenyl) pyridine Ruthenium (II), 50 mL of methanol was added and 3.8 mL ( 1.50 mol) of 10% tetrabutylammonium hydroxide-methanol solution is further added to obtain a uniform solution. The solution is adjusted to pH 3.8 by adding a 0.5N aqueous nitric acid solution and then stored at 5 ° C. for 12 hours. The crystals thus precipitated are collected by suction filtration, and the collected crystals are washed with distilled water and diethyl ether and then vacuum dried. Thereby, 236 mg of the target product (crystal) is obtained.

The present inventors conducted ¹ H-NMR spectrum and ¹⁹ F-NMR spectrum on the compound obtained by the above method, and confirmed that the target compound was obtained. The analysis results are as shown below.

Chemical shift of peak appearing in ¹ H-NMR spectrum (solvent: d4-MeOH-MeONa) σ: 9.07 ppm (hydrogen on aromatic ring, 1H), 8.99 ppm (hydrogen on aromatic ring, 1H), 8.96 ppm (Hydrogen on aromatic ring, 1H), 8.94 ppm (hydrogen on aromatic ring, 1H), 8.21 ppm (hydrogen on aromatic ring, 1H), 8.10 ppm (hydrogen on aromatic ring, 1H), 8.02 ppm (aromatic Ring hydrogen, 1H), 7.96-7.90 ppm (hydrogen on aromatic ring, 4H), 7.81 ppm (hydrogen on aromatic ring, 1H), 7.78 ppm (hydrogen on aromatic ring, 1H), 7.73 ppm (Hydrogen on aromatic ring, 1H), 7.69 ppm (hydrogen on aromatic ring, 1H), 7.60 ppm (hydrogen on aromatic ring, 1H), 7.14 ppm (hydrogen on aromatic ring, 1H), 7.08 ppm (aromatic Hydrogen on the ring, 1H), 6.62 ppm (hydrogen on aromatic ring, 1H), 3.23 ppm (N—CH ₂ —CH ₂ —CH ₂ —CH ₃ , 8H), 1.67 ppm (N—CH ₂ —CH ₂ —CH ₂ —CH ₃₎ 8H), 1.42 ppm (N—CH ₂ —CH ₂ —CH ₂ —CH ₃ , 8H), 1.02 ppm (N—CH ₂ —CH ₂ —CH ₂ —CH ₃ , 12H).

Chemical shift σ of peak appearing in ¹⁹ F-NMR spectrum (solvent: d4-MeOH-MeONa): −64.5 ppm.

The amount of the dye compound adsorbed on the semiconductor layer is preferably 1 × 10 ⁻⁸ mol / cm ² or more and 1 × 10 ⁻⁶ mol / cm ² or less, preferably 5 × 10 ⁻⁸ mol / cm ² or more and 5 × 10 ^−. More preferably, it is ⁷ mol / cm ² . If the amount of the dye compound adsorbed to the semiconductor layer is less than 1 × 10 ⁻⁸ mol / cm ² , the photoelectric conversion efficiency may be reduced. On the other hand, if the amount of the dye compound adsorbed to the semiconductor layer exceeds 1 × 10 ⁻⁶ mol / cm ² , the open circuit voltage may be reduced.

  As a method of adsorbing such a dye compound to the semiconductor layer, for example, a method of immersing the semiconductor layer in a solution (dye solution) in which the dye compound is dissolved may be mentioned. At this time, it is preferable to heat the dye solution in terms of sufficiently allowing the dye solution to penetrate into the semiconductor layer. Here, the solvent of the dye solution is not particularly limited as long as it is a solvent capable of dissolving the dye compound represented by the above chemical formula (I). For example, alcohols such as ethanol, acetone and the like can be used. Ketones, ethers such as diethyl ether or tetrahydrofuran, nitrogen compounds such as acetonitrile, halogenated aliphatic hydrocarbons such as chloroform, aliphatic hydrocarbons such as hexane, aromatic hydrocarbons such as benzene, esters such as ethyl acetate Or water can be used. Further, these solvents may be mixed and used.

<Dye-sensitized solar cell>
FIG. 1 is a cross-sectional view showing an example of the configuration of the dye-sensitized solar cell of the present invention. The dye-sensitized solar cell shown in FIG. 1 has carrier transport provided between the first electrode 112, the second electrode 111 that is a counter electrode of the first electrode 112, and the first electrode 112 and the second electrode 111. Layer 107. Here, the first electrode 112 includes the photoelectric conversion layer 104 in the present invention. Therefore, in the dye-sensitized solar cell shown in FIG. 1, the photoelectric conversion efficiency can be further improved. In the dye-sensitized solar cell illustrated in FIG. 1, the catalyst layer 105 is preferably provided between the carrier transport layer 107 and the second electrode 111, and the photoelectric conversion layer 104 and the carrier transport layer 107 in the first electrode 112. Is preferably surrounded by the sealing member 103.

[First electrode]
The first electrode 112 is preferably configured, for example, by forming the photoelectric conversion layer 104 on the conductive support 110. As the conductive support 110 used in the present invention, for example, a structure in which the conductive layer 102 is formed on the surface of the insulating substrate 100 can be used.

  The insulating substrate 100 is preferably made of a light-transmitting material because it needs light-transmitting properties at the portion that becomes the light receiving surface of the dye-sensitized solar cell. For example, the insulating substrate 100 may be a glass substrate such as soda glass, fused silica glass, or crystal quartz glass, or may be a heat resistant resin plate such as a flexible film. However, even when the insulating substrate 100 is used as a light receiving surface, it substantially transmits light having a wavelength having effective sensitivity to at least the dye compound (the transmittance of the light is, for example, 80% or more, 90% or more is preferable, and it is not always necessary to have transparency to light of all wavelengths.

  Examples of the material constituting the flexible film (hereinafter also referred to as “film”) include tetraacetyl cellulose (TAC), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polycarbonate (PC), and polyarylate (PA). ), Polyetherimide (PEI), phenoxy resin, or polytetrafluoroethylene (PTFE).

  When forming another layer on the insulating substrate 100 with heating, for example, when forming a semiconductor layer on the insulating substrate 100 with heating at about 250 ° C., among the materials constituting the film, 250 is used. It is particularly preferable to use polytetrafluoroethylene having a heat resistance of at least ° C.

  When the produced dye-sensitized solar cell is attached to another structure, the insulating substrate 100 can be used. In other words, the peripheral portion of the insulating substrate 100 such as a glass substrate can be easily attached to another support using a metal processed component and a screw.

  The thickness of the insulating substrate 100 is not particularly limited, but is preferably about 0.05 to 5 mm, and more preferably about 0.2 to 5 mm in consideration of light transmittance and the like.

  The material constituting the conductive layer 102 is not particularly limited as long as it is a material that can generally be used for the conductive layer of a dye-sensitized solar cell and can exhibit the effects of the present invention. However, the conductive layer 102 is preferably made of a light-transmitting material because it needs light transmission when it becomes the light-receiving surface of the dye-sensitized solar cell. For example, the conductive layer 102 is preferably made of indium tin composite oxide (ITO), fluorine-doped tin oxide (FTO), zinc oxide (ZnO), or the like. However, like the insulating substrate 100, the conductive layer 102 substantially transmits light having a wavelength having effective sensitivity to at least the dye compound even when used as a light receiving surface (transmittance of the light). Is, for example, 80% or more, preferably 90% or more), and may not necessarily be transparent to light of all wavelengths.

  The thickness of the conductive layer 102 is not particularly limited, but is preferably about 0.02 to 5 μm. The film resistance of the conductive layer 102 is preferably as low as possible, and is preferably 40 Ω / sq or less.

  A metal lead can be used to reduce the resistance of the conductive layer 102. For example, the conductive layer 102 may be formed on the insulating substrate 101 on which the metal lead wires are formed by sputtering, vapor deposition, screen printing, or the like. After the conductive layer 102 is formed on the insulating substrate 100, A metal lead wire may be formed on the conductive layer 102. The material of the metal lead wire is preferably platinum, gold, silver, copper, aluminum, nickel, or titanium. However, when the metal lead wire is made of a material corroded by the carrier transport layer 107 described later, silicon oxide is included. It is preferable to protect the metal lead wire with a glass material or the like. Note that if the metal lead wire is too thick, the amount of incident light from the light receiving surface may be reduced, and thus the thickness of the metal lead wire is preferably about 0.1 to 4 mm.

  A method for forming the conductive layer 102 over the insulating substrate 101 is not particularly limited, and for example, a sputtering method or a spray method is preferable.

[Second electrode]
The second electrode 111 used in the present invention may be configured, for example, by forming the conductive layer 106 on the insulating substrate 101 or may be composed of only the conductive layer 106. The conductive layer 106 is preferably made of a conductive material, and may be made of an n-type semiconductor material or a p-type semiconductor material, for example, gold, platinum, silver, copper, aluminum, indium, titanium, tantalum, or tungsten. A transparent conductive film made of SnO ₂ , ITO, CuI, ZnO, or the like may be used.

  When the conductive layer 106 is formed on the insulating substrate 101 to form the second electrode 111, the second electrode 111 has a conductive layer formed on the surface of the insulating substrate 101 made of glass, plastic, a transparent polymer sheet, or the like. In other words, the electrode is preferably configured similarly to the conductive support 110 of the first electrode 112. At this time, the insulating substrate 101 is preferably configured similarly to the insulating substrate 100 in the first electrode 112.

[Carrier transport layer]
In the present invention, the “carrier transport layer” is inside the sealing member 103 and sandwiched between the first electrode 112 (specifically, the photoelectric conversion layer 104 in the first electrode 112) and the second electrode 111. A carrier transport material is injected into the formed region. Therefore, at least the photoelectric conversion layer 104 is filled with a carrier transport material.

  The carrier transport material is preferably a conductive material capable of transporting ions, and is preferably a liquid electrolyte, a solid electrolyte, a gel electrolyte, a molten salt gel electrolyte, or the like.

  The liquid electrolyte is not particularly limited as long as it is a liquid substance containing a redox species, and can generally be used in a battery or a solar battery. Specifically, the liquid electrolyte includes a redox species and a solvent capable of dissolving the redox species, a redox species and a molten salt capable of dissolving the redox species, or a redox species. What consists of the said solvent and the said molten salt etc. can be mentioned.

Examples of the redox species include I ⁻ / I ³⁻ , Br ²⁻ / Br ^{3 −} , Fe ²⁺ / Fe ³⁺ , or quinone / hydroquinone. Specifically, the redox species include metal iodide such as lithium iodide (LiI), sodium iodide (NaI), potassium iodide (KI), or calcium iodide (CaI ₂ ) and iodine (I ₂ ). It may be a combination. The redox species includes tetraalkylammonium iodide (TEAI), tetrapropylammonium iodide (TPAI), tetrabutylammonium iodide (TBAI), or tetraalkylammonium iodide (THAI) and iodine. It may be a combination. The redox species may be a combination of bromide with a metal bromide such as lithium bromide (LiBr), sodium bromide (NaBr), potassium bromide (KBr), or calcium bromide (CaBr ₂ ). Among these, a combination of LiI and I ₂ is particularly preferable.

  Examples of the solvent capable of dissolving the redox species include carbonate solvents such as propylene carbonate, nitrile solvents such as acetonitrile, alcohols such as ethanol, water, and aprotic polar substances. Among these, carbonate compounds or nitrile compounds are particularly preferable. Two or more kinds of these solvents can be mixed and used.

  The electrolyte concentration in the liquid electrolyte is preferably in the range of 0.001 to 1.5 mol / L, particularly preferably in the range of 0.01 to 0.7 mol / L.

  The solid electrolyte is a conductive material that can transport electrons, holes, or ions, and can be used as an electrolyte of a dye-sensitized solar cell, and preferably has no fluidity. Specifically, a solid electrolyte includes 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, iodine Examples thereof include p-type semiconductors such as copper halide and copper thiocyanate, or electrolytes obtained by solidifying liquid electrolytes containing molten salts with fine particles.

  The gel electrolyte is usually composed of an electrolyte and a gelling agent. The electrolyte may be, for example, the liquid electrolyte or the solid electrolyte. Examples of the gelling agent include polymer gels such as cross-linked polyacrylic resin derivatives, cross-linked polyacrylonitrile derivatives, polyalkylene oxide derivatives, silicone resins, or polymers having a nitrogen-containing heterocyclic quaternary compound salt structure in the side chain. And the like.

  The molten salt gel electrolyte is usually composed of the gel electrolyte as described above and a room temperature molten salt. Examples of the room temperature molten salt include nitrogen-containing heterocyclic quaternary ammonium salts such as pyridinium salts and imidazolium salts.

  The above electrolyte (specifically, a liquid electrolyte, a solid electrolyte, a gel electrolyte, or a molten salt gel electrolyte) may contain the following additives as necessary. The additive may be a nitrogen-containing aromatic compound such as t-butylpyridine (TBP), dimethylpropylimidazole iodide (DMPII), methylpropylimidazole iodide (MPII), ethylmethylimidazole iodide ( It may be an imidazole salt such as EMII), ethylimidazole iodide (EII), or hexylmethylimidazole iodide (HMII).

[Catalyst layer]
The catalyst layer 105 is provided between the carrier transport layer 107 and the conductive layer 106 in the second electrode 111. The material constituting the catalyst layer 105 is preferably a material capable of activating the redox reaction of the carrier transport layer 107, and may be, for example, platinum (work function: 6.35 eV), carbon black, Carbon materials (work function 4.7 ev) such as graphite, glass carbon, amorphous carbon, hard carbon, soft carbon, carbon whisker, carbon nanotube, or fullerene may be used.

  Examples of a method for forming the catalyst layer 105 made of platinum include a method in which a platinum layer is formed on the conductive layer 106 of the second electrode 111 by a PVC method, a vapor deposition method, a sputtering method, or the like. As a method for forming the catalyst layer 105 made of carbon, there is a method in which a paste obtained by dispersing carbon in a solvent is applied onto the conductive layer 106 by a coating method such as a screen printing method.

[Sealing member]
The sealing member 103 is provided to prevent water and the like from entering the inside of the dye-sensitized solar cell. When the carrier transport layer 107 is made of a liquid electrolyte, the sealing member 103 is used to prevent evaporation of the liquid electrolyte. Provided. Further, the sealing member 103 also plays a role of absorbing impact or stress due to falling objects on the dye-sensitized solar cell, and a role of absorbing deflection acting on the insulating substrates 100 and 101 due to long-term use. .

  The sealing member 103 is preferably made of silicone resin, epoxy resin, polyisobutylene resin, hot melt resin, glass frit, or the like. Two or more kinds of these materials may be mixed to form the sealing member 103, or two or more layers made of a single material may be laminated to form the sealing member 103. good.

  In the case where a nitrile solvent or a carbonate solvent is used as a solvent for the redox electrolyte in the carrier transport layer 107, the sealing member 103 includes a silicone resin, a hot melt resin (for example, an ionomer resin), and a polyisobutylene resin. Or glass frit.

  When the sealing member 103 is made of silicone resin, epoxy resin, or glass frit, the sealing member 103 can be formed hollow by using a dispenser. When the sealing member 103 is made of a hot melt resin, the sealing member 103 can be formed in a hollow shape by opening a patterned hole in a sheet made of the hot melt resin. The hollow portion formed in this manner is a region where the photoelectric conversion layer 104 and the carrier transport layer 107 are formed.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.

<Example 1>
The dye-sensitized solar cell shown in FIG. 1 was produced. Specifically, as a conductive support 110, a glass substrate (made by Nippon Sheet Glass Co., Ltd., trade name “SnO ₂ film attached” is formed by forming a conductive layer 102 made of SnO ₂ film on an insulating substrate 100 made of glass. Glass ") was used. Using a screen printing machine (LS-150, manufactured by Neurong Seimitsu Kogyo Co., Ltd.), a commercially available titanium oxide paste (manufactured by Solaronix, trade name “Ti-Nanoxide T” is formed at a predetermined position of the conductive layer 102 of the conductive support 110. / SP "). The conductive support 110 coated with the titanium oxide paste was baked in the air at 500 ° C. for 40 minutes using a baking furnace (KDF P-100 manufactured by Denken). As a result, a semiconductor layer made of titanium oxide and having a thickness of 8 μm was obtained. Using a screen printer, a commercially available titanium oxide paste (manufactured by Solaronix, trade name “Ti-Nanoxide D / SP”) is applied on the obtained semiconductor layer, and the titanium oxide paste is applied using the above baking furnace. The conductive support 110 newly coated with was fired at 500 ° C. for 40 minutes in air. As a result, a semiconductor layer made of titanium oxide and having a thickness of 12 μm was formed.

The dye compound represented by the above chemical formula (I) (R is CF ₃ ) was dissolved at a concentration of 0.3 mmol / L in a solvent in which acetonitrile and n-butanol were mixed at a volume ratio of 1: 1. The semiconductor layer was immersed in the dye solution thus obtained and left at room temperature for 24 hours. Thereby, the said pigment | dye compound was adsorb | sucked to the semiconductor layer, and the photoelectric converting layer 104 was obtained. Thereafter, the insulating substrate 100 was washed with ethanol and dried at about 35 ° C. for about 1 minute.

As the second electrode 111, a glass substrate (made by Nippon Sheet Glass Co., Ltd., trade name “SnO ₂ film-attached glass”) in which the conductive layer 106 made of SnO ₂ film is formed on the insulating substrate 101 made of glass was used. . Using a vapor deposition machine (EVD500A manufactured by Anelva), platinum was vapor-deposited at a predetermined position of the conductive layer 106 of the second electrode 111 at a vapor deposition rate of 0.1 nm / sec. As a result, a catalyst layer 105 having a thickness of 50 nm was formed on the conductive layer 106. Thereafter, two electrolyte inlets were formed at predetermined positions of the second electrode 111 (not shown).

  Using a screen printing machine (LS-150 manufactured by Neurong Seimitsu Kogyo), an ultraviolet curable resin (manufactured by Three Bond, product number “31X-101”) is provided on the outer periphery of the photoelectric conversion layer 104 so as not to contact the photoelectric conversion layer 104. Was applied. The second electrode 111 was bonded to the upper part of the applied ultraviolet curable resin so that the catalyst layer 105 was positioned on the ultraviolet curable resin side with respect to the insulating substrate 101. Then, the ultraviolet curable resin is cured using an ultraviolet lamp (HR10001N-4 manufactured by Sen Special Light Source Co., Ltd.), and the photoelectric conversion layer 104 is included through the ultraviolet curable resin (sealing member 103). 112 and the second electrode 111 were bonded.

Thereafter, the electrolytic solution was injected from the electrolytic solution inlet formed in the second electrode 111 by the capillary effect. As an electrolytic solution, LiI (manufactured by Aldrich Chemical Company) was dissolved in acetonitrile (manufactured by Aldrich Chemical Company) so that the concentration was 0.1 mol / L, and I ₂ (manufactured by Aldrich Chemical Company) was prepared so that the concentration became 0.05 mol / L. Dissolve Aldrich Chemical Company, dissolve TBP (Aldrich Chemical Company) to a concentration of 0.5 mol / L, and dissolve DMPII (Shikoku Chemicals) to a concentration of 0.6 mol / L Were used. After injection of the electrolytic solution, an ultraviolet curable resin (product number “31X-101” manufactured by ThreeBond Co., Ltd.) is applied to the electrolytic solution injection port, and the ultraviolet curable resin is used by using an ultraviolet lamp (HR10001N-4 of Sen Special Light Source Co., Ltd.). Was cured. Thereby, the dye-sensitized solar cell of Example 1 was produced.

The obtained dye-sensitized solar cell is irradiated with light of 1 kW / m ² intensity (AM1.5 solar simulator), and short circuit current (Jsc), open circuit voltage (Voc), fill factor (FF) and photoelectric Conversion efficiency (η) was measured.

<Example 2>
A dye-sensitized solar cell of Example 2 was produced in the same manner as in Example 1 except that the dye compound was a compound represented by the chemical formula (I) (R is CN). According to the same method as in Example 1, the short-circuit current (Jsc), open-circuit voltage (Voc), fill factor (FF), and photoelectric conversion efficiency (η) of the obtained dye-sensitized solar cell were measured.

<Example 3>
A dye-sensitized solar cell of Example 3 was produced in the same manner as in Example 1 except that the dye compound was a compound represented by the chemical formula (I) (R is OCH ₃ ). According to the same method as in Example 1, the short-circuit current (Jsc), open-circuit voltage (Voc), fill factor (FF), and photoelectric conversion efficiency (η) of the obtained dye-sensitized solar cell were measured.

<Example 4>
A dye-sensitized solar cell of Example 4 was produced in the same manner as in Example 1 except that the dye compound was a compound represented by the chemical formula (I) (R is SCH ₃ ). According to the same method as in Example 1, the short-circuit current (Jsc), open-circuit voltage (Voc), fill factor (FF), and photoelectric conversion efficiency (η) of the obtained dye-sensitized solar cell were measured.

<Comparative Example 1>
A dye-sensitized solar cell of Comparative Example 1 was produced in the same manner as in Example 1 except that the dye compound was a compound represented by the chemical formula (XI). According to the same method as in Example 1, the short-circuit current (Jsc), open-circuit voltage (Voc), fill factor (FF), and photoelectric conversion efficiency (η) of the obtained dye-sensitized solar cell were measured.

  The measurement results are shown in Table 1.

  As shown in Table 1, in the dye-sensitized solar cells (Examples 1 to 4) using the dye compound represented by the chemical formula (I), the dye sensitization using the dye compound represented by the chemical formula (XI) is used. It was found that Jsc was larger, Voc was higher, and η was higher than the solar cell (Comparative Example 1). The reason is considered that the dye compound represented by the chemical formula (I) contributes to the improvement of the photoelectric conversion efficiency of the photoelectric conversion element as compared with the dye compound represented by the chemical formula (XI).

  100, 101 Insulating substrate, 102, 106 Conductive layer, 103 Sealing member, 104 Photoelectric conversion layer, 105 Catalyst layer, 107 Carrier transport layer, 110 Conductive support, 111 Second electrode, 112 First electrode.

Claims (2)

A photoelectric conversion element comprising a photoelectric conversion layer constituted by adsorbing a dye compound represented by the following chemical formula (I) to a semiconductor layer.

In the above chemical formula (I), R is any one of —CF ₃ , —CN, —OCH ₃ , and —SCH ₃ . A first electrode including a photoelectric conversion layer constituted by adsorbing a dye compound represented by the following chemical formula (I) to a semiconductor layer;
A second electrode as a counter electrode of the first electrode;
A dye-sensitized solar cell comprising a carrier transport layer provided between the first electrode and the second electrode.

In the above chemical formula (I), R is any one of —CF ₃ , —CN, —OCH ₃ , and —SCH ₃ .

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