JP7069687B2 - Photoelectric conversion element and solar cell - Google Patents

Description

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

In recent years, the importance of solar cells as an alternative energy to fossil fuels and as a measure against global warming has increased. However, the current solar cells represented by silicon-based solar cells are currently expensive and are a factor that hinders their widespread use.

Therefore, research and development of various low-cost solar cells are underway, and among them, the dye-sensitized solar cell announced by Gratzel et al. Of Swiss Federal Institute of Technology is expected to be put into practical use (for example, patent). See Document 1, Non-Patent Documents 1 and 2). The structure of this solar cell consists of a porous metal oxide semiconductor provided on a transparent conductive glass substrate, a sensitizing dye adsorbed on the surface thereof, an electrolyte having a redox pair, and a counter electrode. Gratzel et al. Remarkably improved the photoelectric conversion efficiency by making a metal oxide semiconductor electrode such as titanium oxide porous to increase the surface area and adsorbing a ruthenium complex as a dye by a single molecule.

However, the ruthenium complex used in the sensitizing dye is a rare metal and has resource limitations. Therefore, there is a demand for the development of organic dyes that are less resource-constrained. As the sensitizing dyes that have already been proposed, xanthene dyes such as eosin Y (see Non-Patent Document 3), porphyrin dyes (see Non-Patent Document 4), cyanine dyes (see Patent Document 2), and melanin dyes (see Patent Document 2). Document 3), xanthene dye (see Non-Patent Document 5), polyene dye (see Non-Patent Document 6), porphyrin dye (see Non-Patent Document 7), phthalocyanine dye (see Non-Patent Document 8), and the like have been reported. ..

However, xanthene-based dyes such as eosin Y and perylene-based dyes have an absorption wavelength region of only about 600 nm, and have a drawback of low conversion efficiency. Since cyanine dyes, merocyanine dyes, polyene dyes, coumarin dyes, etc. have many conjugated double bonds, cis-trans isomerization by light irradiation is likely to occur, and the durability is very low. Porphyrin-based dyes and phthalocyanine-based dyes have low solubility and low adsorption power to titanium oxide, and are easily desorbed from titanium oxide. Also, it is difficult for phthalocyanine dyes to adapt their energy levels to titanium oxide.

Therefore, in recent years, a sensitizing dye using a heterocycle called an indoline ring has attracted attention (see, for example, Non-Patent Documents 9 and 10). The dye into which the indoline ring is introduced has a particularly high molar extinction coefficient, and can obtain a high conversion efficiency comparable to that of a ruthenium complex.
However, it has been reported that these dyes have low durability because they have been developed only for the purpose of obtaining high efficiency (see, for example, Non-Patent Document 11). Therefore, in recent years, indoline dyes that do not use the Rhodanine ring or cyanoacetic acid have been reported (see, for example, Non-Patent Document 12).

On the other hand, the dye-sensitized solar cell contains iodine and a volatile solvent, and has problems such as a decrease in power generation efficiency due to deterioration of the iodine redox system and volatilization or leakage of an electrolytic solution. To compensate for this shortcoming, those using an inorganic semiconductor (see, for example, Non-Patent Documents 13 and 14) and those using a low molecular weight organic hole transport material (see, for example, Patent Document 4, Non-Patent Documents 15 and 16). , Those using a conductive polymer (see, for example, Patent Document 5 and Non-Patent Document 17) have been reported. However, since inorganic or organic semiconductors have higher resistance than iodine redox, there is a drawback that efficiency is reduced.

Therefore, studies have been made to reduce the film thickness of the porous titanium oxide to about 2 μm and shorten the transport distance to the counter electrode of the inorganic or organic semiconductor (see, for example, Non-Patent Document 18).
However, as a result of the decrease in the film thickness of the porous titanium oxide, the amount of adsorbed sensitizing dye also decreases. Therefore, the conversion efficiency should be improved by using an indoline dye having a higher molar extinction coefficient than the ruthenium complex. Has been reported (see, for example, Non-Patent Document 19).
However, the current situation is that satisfactory durability has not been obtained.

In addition, depending on the type of sensitizing dye, a strong interaction may occur on the adsorbed titanium oxide, resulting in a decrease in efficiency. It has been reported that high efficiency can be obtained by dissolving in the same solvent, allowing a co-adsorbent to exist between the sensitizing dyes, and reducing the interaction between the sensitizing dyes (for example, Non-Patent Document 20). reference). As the co-adsorbent, a cholic acid derivative having a steroid skeleton (see, for example, Non-Patent Document 21), an alkylphosphonic acid (see, for example, Non-Patent Document 22) and the like are known.

However, the cholic acid derivative has a carboxylic acid bonded to an alkyl group and has a different acidity from the carboxylic acid of the sensitizing dye. Alkylphosphonic acid is also significantly different in acidity from the sensitizing dye. Since the adsorption speed to titanium oxide differs depending on the acidity, the ratio of the sensitizing dye and the co-adsorbent will change significantly if the dye solution is used several times. For example, when a carboxylic acid sensitizing dye and a phosphonic acid co-adsorbent are used, the phosphonic acid co-adsorbent is significantly reduced, and after several uses, the sensitizing dye becomes a solution with a high proportion and increases. The interaction of sensitizers increases, and as a result, only elements with low characteristics can be obtained.

Therefore, a method of controlling the dye solution by measuring the concentrations of the sensitizing dye and the co-adsorbent in the dye solution after adsorbing the dye and adding the insufficient amount can be considered.
However, since the co-adsorbents used so far, such as coli acid derivatives and alkylphosphonic acids, do not have an absorption spectrum at 254 nm, a simple method such as high performance liquid chromatography (hereinafter referred to as HPLC) can be used. It was difficult to quantify the concentration.

Therefore, a method of mixing and adsorbing two types of sensitizing dyes has been reported (see, for example, Non-Patent Document 23). Considering that one sensitizing dye is a co-adsorbent having an absorption spectrum at 254 nm, it is possible to control the dye solution by HPLC.
However, since the dye used here is also a dye having low durability, it has not reached the purpose of obtaining an element having high durability.

An object of the present invention is to provide a photoelectric conversion element having high efficiency and high long-term stability.

In order to solve the above problems, the present invention is a photoelectric conversion element having a first electrode, an electron transport layer formed on the first electrode, a charge transfer layer, and a second electrode. The electron transport layer is characterized by containing an electron transporting compound carrying a compound represented by the following general formula (4) and a compound represented by the following general formula (2).

(In the formula, X ₁ And X ₂ Represents an oxygen atom or a sulfur atom, and R ₂ Represents an alkyl group, an aryl group or a heterocyclic group, and R ₃ Represents an acidic group, each of which may be the same or different, R ₆ And R ₇ Represents an alkyl group or an aryl group, and R ₆ And R ₇ May be combined to form a cyclic structure, or may be independent non-annular structures. )

(In the formula, R ₄ represents an aryl group or a heterocyclic group, and R ₅ represents an alkyl group, an alkoxy group, an alkenyl group, an alkylthio group or an aryl ether group.)

According to the present invention, it is possible to provide a photoelectric conversion element having high efficiency and high long-term stability.

It is sectional drawing for explaining the structure of an example of the photoelectric conversion element which concerns on this invention. It is sectional drawing for explaining the structure of another example of the photoelectric conversion element which concerns on this invention. It is sectional drawing for explaining the structure of another example of the photoelectric conversion element which concerns on this invention. It is sectional drawing (A) for demonstrating the structure of another example of the photoelectric conversion element which concerns on this invention, and the main part schematic diagram (B) of a light receiving part. It is an example of the HPLC measurement figure of the dye solution used in Example 1. It is an example of the HPLC measurement figure of the dye solution used in the comparative example 5.

Hereinafter, the photoelectric conversion element and the solar cell according to the present invention will be described with reference to the drawings. It should be noted that the present invention is not limited to the embodiments shown below, and can be modified within the range conceivable by those skilled in the art, such as other embodiments, additions, modifications, and deletions. However, as long as the action and effect of the present invention are exhibited, it is included in the scope of the present invention.

The present invention is a photoelectric conversion element having a first electrode, an electron transport layer formed on the first electrode, a charge transfer layer, and a second electrode, and the electron transport layer is generally described below. It is characterized by containing an electron transporting compound carrying a compound represented by the formula (1) and a compound represented by the following general formula (2).

(In the formula, X ₁ and X ₂ represent an oxygen atom, a sulfur atom or a selenium atom, R ₁ represents a methine group, R ₂ represents an alkyl group, an aryl group or a heterocyclic group, and R ₃ is the same but different. It represents an acidic group which may be present, m represents 1 or 2, and Z1 and Z2 represent groups forming a cyclic structure.)

(In the formula, R ₄ represents an aryl group or a heterocyclic group, and R ₅ represents an alkyl group, an alkoxy group, an alkenyl group, an alkylthio group or an aryl ether group.)

FIG. 1 shows the configuration of the photoelectric conversion element according to the present embodiment. FIG. 1 is a schematic cross-sectional view of the photoelectric conversion element of the present embodiment.
In FIG. 1, the first electrode 2 is provided on the substrate 1 and the electron transport layers 4 are sequentially laminated. The electron transport layer 4 contains an electron transport compound 11 carrying a sensitizing dye 5 and a co-adsorbent 6, and has a configuration in which a charge transfer layer 7 is sandwiched between the electron transport layer 4 and the second electrode 8. Further, the first electrode 2 and the second electrode 8 may take out electricity by using the lead lines 9 and 10.

As another embodiment, FIG. 2 shows a configuration in which the blocking layer 3 is provided between the first electrode 2 and the electron transport layer 4. FIG. 2 is a schematic cross-sectional view of the photoelectric conversion element as in FIG. 1. The description of the same items as those shown in FIG. 1 will be omitted.

As yet another embodiment, FIG. 3 shows a configuration in which the absorption wavelength control layer 12 is provided on the first electrode 2 on the side opposite to the electron transport layer 4. FIG. 3 is a schematic cross-sectional view of the photoelectric conversion element as in FIG. 1. The description of the same items as those shown in FIG. 1 will be omitted. Further, although the blocking layer 3 is shown in FIG. 3, the blocking layer 3 and the absorption wavelength control layer 12 do not have to exist at the same time and may exist separately.

As yet another embodiment, FIG. 4 shows a configuration in the case of a frame structure. FIG. 4A is a schematic cross-sectional view, and FIG. 4B is a schematic view of a main part of the light receiving portion. The description of the same items as those shown in FIG. 1 will be omitted.

<First electrode>
As the first electrode 2 of the present embodiment, an electrode material may be provided on the substrate 1 to separate the substrate 1 and the first electrode 2, or the substrate 1 and the electrode may be integrated.
The first electrode 2 of the present embodiment is preferably a conductive substance that is transparent to visible light, and a known photoelectric conversion element or a known one used for a liquid crystal panel or the like can be used. For example, indium tin oxide (hereinafter referred to as ITO), fluorine-doped tin oxide (hereinafter referred to as FTO), antimony-doped tin oxide (hereinafter referred to as ATO), indium zinc oxide, niobium titanium oxide. , Graphene and the like, and these may be used individually or in combination of two or more.
The thickness of the first electrode 2 is preferably 5 nm to 100 μm, more preferably 50 nm to 10 μm.

Further, in order to maintain a certain degree of hardness, the first electrode 2 may be provided on a substrate 1 made of a material transparent to visible light, and the substrate 1 may be, for example, glass, a transparent plastic plate, or a transparent plastic film. , Inorganic transparent crystals and the like are used.

Known examples in which the electrode and the substrate are integrated include, for example, FTO-coated glass, ITO-coated glass, zinc oxide: aluminum-coated glass, FTO-coated transparent plastic film, ITO-coated transparent plastic film, and the like.

Further, a transparent electrode in which tin oxide or indium oxide is doped with cations or anions having different valences, or a metal electrode having a structure capable of transmitting light such as a mesh or a stripe is provided on a substrate such as a glass substrate. good. These may be alone, mixed with two or more kinds, or laminated.

Further, for the purpose of lowering the resistance, a metal lead wire or the like may be used in combination. Examples of the material of the metal lead wire include metals such as aluminum, copper, silver, gold, platinum, and nickel. The metal lead wire may be installed on a substrate by thin film deposition, sputtering, crimping or the like, and ITO or FTO may be provided on the metal lead wire.

<Blocking layer>
The photoelectric conversion element of the present embodiment may be provided with a blocking layer 3 between the first electrode 2 described above and the electron transport layer 4 described below. The blocking layer 3 can be, for example, a thin film made of a semiconductor. For example, a dense thin film is formed on the first electrode 2, and an electron transport layer 4 is further laminated on the thin film to form a laminated structure.

The blocking layer 3 is formed for the purpose of preventing electronic contact between the first electrode 2 and the charge transfer layer 7. Therefore, pinholes, cracks, and the like may be formed as long as the first electrode 2 and the charge transfer layer 7 do not physically contact each other.
The film thickness of the blocking layer 3 is not particularly limited, but is preferably 10 nm to 1 μm, more preferably 20 nm to 700 nm.

The blocking layer 3 is not particularly limited, and known ones can be used. Specific examples thereof include elemental semiconductors such as silicon and germanium, compound semiconductors typified by metallic chalcogenides, and compounds having a perovskite structure.

Metallic chalcogenides include titanium, tin, zinc, iron, tungsten, zirconium, hafnium, strontium, indium, cerium, ittrium, lantern, vanadium, niobium, or tantalum oxide, cadmium, zinc, lead, silver, antimony, bismuth. Examples include sulfide, cadmium, lead selenium, and cadmium telluride.

As other compound semiconductors, phosphoride such as zinc, gallium, indium and cadmium, gallium arsenic, copper-indium-selenium, copper-indium-sulfide and the like are preferable.
Further, as the compound having a perovskite structure, strontium titanate, calcium titanate, sodium titanate, barium titanate, potassium niobate and the like are preferable.

Of these, oxide semiconductors are preferable, and titanium oxide, zinc oxide, tin oxide, and niobium oxide are particularly preferable, and they may be used alone or in admixture of two or more. The crystal type of these semiconductors is not particularly limited, and may be single crystal, polycrystal, or amorphous.

<Electron transport layer>
The electron transport layer 4 of the present embodiment is formed on the first electrode 2 or the blocking layer 3, and is composed of a compound represented by the general formula (1) and a compound represented by the general formula (2). It contains the carried electron-transporting compound 11 (also referred to as electron-transporting particles or the like). The electron transport layer 4 is, for example, porous, but may be a single layer or a multilayer. In the case of multiple layers, dispersions of semiconductor fine particles having different particle sizes can be applied in multiple layers, or different types of semiconductors, resins, and coating layers having different compositions of additives can be applied in multiple layers. Multilayer coating is an effective means when the film thickness is insufficient with one coating.

Generally, as the film thickness of the electron transport layer 4 increases, the amount of supported sensitizing dye per unit projected area also increases, so that the light capture rate increases, but the diffusion distance of the injected electrons also increases, so the charge is regenerated. The loss due to bonding also increases. Therefore, the film thickness of the electron transport layer 4 can be changed as appropriate, but it is preferably 100 nm to 100 μm.

<< Electron-transporting compound >>
The electron transporting compound 11 in the electron transporting layer 4 is not particularly limited, and known compounds can be used. Specific examples thereof include elemental semiconductors such as silicon and germanium, compound semiconductors typified by metallic chalcogenides, and compounds having a perovskite structure.

Metallic chalcogenides include titanium, tin, zinc, iron, tungsten, zirconium, hafnium, strontium, indium, cerium, ittrium, lantern, vanadium, niobium, or tantalum oxide, cadmium, zinc, lead, silver, antimony, bismuth. Examples include sulfide, cadmium, lead selenium, and cadmium telluride.

As other compound semiconductors, phosphoride such as zinc, gallium, indium and cadmium, gallium arsenic, copper-indium-selenium, copper-indium-sulfide and the like are preferable.
Further, as the compound having a perovskite structure, strontium titanate, calcium titanate, sodium titanate, barium titanate, potassium niobate and the like are preferable.

Among these, oxide semiconductors, particularly n-type oxide semiconductors, are preferable, and titanium oxide, zinc oxide, tin oxide, and niobide oxide are particularly preferable. These may be used alone or in a mixture of two or more kinds. The crystal type of these semiconductors is not particularly limited, and may be single crystal, polycrystal, or amorphous.

The particle size of the electron-transporting compound used in the electron-transporting layer 4 is not particularly limited, but the average particle size of the primary particles is preferably 1 to 100 nm, more preferably 5 to 50 nm.

It is also possible to improve efficiency by the effect of mixing or laminating semiconductor fine particles having a larger average particle size to scatter incident light. In this case, the average particle size of the semiconductor is preferably 50 to 500 nm.

The method for producing the electron transport layer 4 is not particularly limited and can be appropriately changed. Examples thereof include a method of forming a thin film in a vacuum such as sputtering and a wet film forming method. In consideration of manufacturing cost and the like, a wet film forming method is particularly preferable, and a method of preparing a paste in which a powder of semiconductor fine particles or a sol is dispersed and applying the paste on the first electrode 2 is preferable.

When this wet film forming method is used, the coating method is not particularly limited and can be carried out according to a known method. For example, dip method, spray method, wire bar method, spin coating method, roller coating method, blade coating method, gravure coating method, and various wet printing methods such as letterpress, offset, gravure, intaglio, rubber plate, screen printing, etc. Method can be used.

When a dispersion liquid is prepared by mechanical grinding or using a mill, it is formed by at least semiconductor fine particles alone or a mixture of semiconductor fine particles and a resin dispersed in water or an organic solvent.

The resin used at this time includes polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, acrylic acid ester, and methacrylic acid ester, silicon resin, phenoxy resin, polysulfone resin, polyvinyl butyral resin, and polyvinylformal resin. Examples thereof include polyester resin, cellulose ester resin, cellulose ether resin, urethane resin, phenol resin, epoxy resin, polycarbonate resin, polyarylate resin, polyamide resin, and polyimide resin.

As the solvent for dispersing the electron-transporting particles of the electron-transporting layer 4, an alcohol-based solvent such as water, methanol, ethanol, isopropyl alcohol, α-terpineol, a ketone solvent such as acetone, methyl ethyl ketone, or methyl isobutyl ketone, and ethyl formate , Ethyl acetate, or ester solvent such as n-butyl acetate, ether solvent such as diethyl ether, dimethoxyethane, tetrahydrofuran, dioxolane, or dioxane, N, N-dimethylformamide, N, N-dimethylacetamide, or N- Amid solvents such as methyl-2-pyrrolidone, dichloromethane, chloroform, bromoform, methyl iodide, dichloroethane, trichloroethane, trichloroethylene, chlorobenzene, o-dichlorobenzene, fluorobenzene, bromobenzene, iodobenzene, 1-chloronaphthalene and the like. Halogenated hydrocarbon solvent, n-pentane, n-hexane, n-octane, 1,5-hexadiene, cyclohexane, methylcyclohexane, cyclohexadiene, benzene, toluene, o-xylene, m-xylene, p-xylene, ethylbenzene , Or a hydrocarbon solvent such as benzene. These can be used alone or as a mixed solvent of two or more kinds.

The dispersion liquid of the electron-transporting particles of the electron-transporting layer 4, or the paste of the particles obtained by the sol-gel method or the like, is an acid such as hydrochloric acid, nitric acid, acetic acid, or polyoxyethylene (10) in order to prevent reaggregation of the particles. ) A surfactant such as octylphenyl ether and a chelating agent such as acetylacetone, 2-aminoethanol and ethylenediamine can be added.

It is also an effective means to add a thickener for the purpose of improving the film-forming property.
Examples of the thickener added at this time include polymers such as polyethylene glycol and polyvinyl alcohol, and thickeners such as ethyl cellulose.

After the electron transporting particles of the electron transporting layer 4 are applied, the particles are electronically contacted with each other, and in order to improve the film strength and the adhesion to the substrate, firing, microwave irradiation, electron beam irradiation, or laser It is preferable to irradiate with light. These processes may be performed individually or in combination of two or more types.

In the case of firing, the range of the firing temperature is not particularly limited, but if the temperature is raised too high, the resistance of the substrate may increase or the substrate may melt, so 30 to 700 ° C. is preferable, and 100 to 600 ° C. is more preferable. Further, the firing time is not particularly limited, but 10 minutes to 10 hours is preferable.

After firing, for the purpose of increasing the surface area of the particles and increasing the efficiency of electron injection from the sensitizing dye into the particles of the electron transport layer, for example, chemical plating using an aqueous solution of titanium tetrachloride or a mixed solution with an organic solvent or trichloride An electrochemical plating treatment using an aqueous titanium solution may be performed.
The microwave irradiation may be performed from the electron transport layer forming side or from the back side. The irradiation time is not particularly limited, but it is preferably performed within 1 hour.

The film in which the electron-transporting particles of the electron-transporting layer 4 having a diameter of several tens of nm are laminated by sintering or the like forms a porous state. This nanoporous structure has a very high surface area, which can be expressed using the roughness factor. This roughness factor is a numerical value representing the actual area inside the porous medium with respect to the area of the semiconductor fine particles coated on the substrate. Therefore, the larger the roughness factor is, the more preferable it is, but in view of the relationship with the film thickness of the electron transport layer 4, 20 or more is preferable in this embodiment.

<< Sensitive Dye >>
In the electron transport layer 4 of the present embodiment, the sensitizing dye is adsorbed on the surface of the electron transport compound 11 in order to further improve the conversion efficiency. As the sensitizing dye in this embodiment, a compound represented by the following general formula (1) is used.

(In the formula, X ₁ and X ₂ represent an oxygen atom, a sulfur atom or a selenium atom, R ₁ represents a methine group, R ₂ represents an alkyl group, an aryl group or a heterocyclic group, and R ₃ is the same but different. It represents an acidic group which may be present, m represents 1 or 2, and Z1 and Z2 represent groups forming a cyclic structure.)

In the general formula (1), X ₁ and X ₂ represent an oxygen atom, a sulfur atom or a selenium atom.
Further, R ₁ represents a methine group and may have a substituent. Specific examples of the substituent include an aryl group such as a phenyl group and a naphthyl group, a heterocycle such as a thienyl group and a frill group, and the like.

R ₂ represents an alkyl group, an aryl group or a heterocyclic group, and may have a substituent.
Examples of the alkyl group include a methyl group, an ethyl group, a 2-propyl group, a 2-ethylhexyl group and the like.
Examples of the aryl group include those mentioned above.
Examples of the heterocyclic group include those mentioned above.
Examples of the substituent of R ₂ include an alkyl group, an alkoxy group, an aryl group, and a heterocycle, all of which can be mentioned above.

R ₃ represents an acidic group which may be the same or different, and m represents 1 or 2. Examples of the acidic group include carboxylic acid, sulfonic acid, phosphonic acid, boric acid, and phenols. The acidic group preferably binds to an electron transporting compound.

Z1 and Z2 represent groups forming a cyclic structure and may have a substituent.
Examples of Z1 include condensed hydrocarbon compounds such as a benzene ring and a naphthalene ring, and a heterocycle such as a thiophene ring and a furan ring, each of which may have a substituent. Specific examples of the substituent include the above-mentioned alkyl group, methoxy group, ethoxy group, alkoxy group such as 2-isopropoxy group and the like.
Examples of Z2 include, but are not limited to, (A-1) to (A-22) shown below. Here, the structure including the benzene ring and the nitrogen atom bonded to the benzene ring is exemplified.

The compound represented by the general formula (1) is preferably a compound represented by the following general formula (3) or the following general formula (4).

(In the formula, X ₁ and X ₂ represent an oxygen atom or a sulfur atom, R ₂ represents an alkyl group, an aryl group or a heterocyclic group, R ₃ represents an acidic group, and R ₆ and R ₇ represent an alkyl group or an alkyl group. Representing an aryl group, R ₆ and R ₇ may be bonded to form a cyclic structure, or they may be independent non-cyclic structures.)

(In the formula, X ₁ and X ₂ represent an oxygen atom or a sulfur atom, R ₂ represents an alkyl group, an aryl group or a heterocyclic group, and R ₃ represents an acidic group, which may be the same or different. R ₆ and R ₇ represent an alkyl group or an aryl group, and R ₆ and R ₇ may be bonded to form a cyclic structure, or may be independent non-cyclic structures.)

In addition, R ₂ , R ₆ and R ₇ may have a substituent.

Specific examples of the compound represented by the general formula (1) include, but are not limited to, (B-1) to (B-38) shown below.

The sensitizing dye in the present embodiment may be used alone or in a mixture of two or more kinds. Examples of the sensitizing dye that may be mixed and used with the compound represented by the general formula (1) include JP-A-7-500630, JP-A-10-233238, JP-A-2000-26487, and Japanese Patent Laid-Open No. 7-500630. Metal complex compounds described in JP-A-2000-323191, JP-A-2001-59062, etc., JP-A-10-93118, JP-A-2002-164809, JP-A-2004-95450, J. Phys. The coumarin compound described in Chem. C, 7224, Vol. 111 (2007) and the like, the polyene compound described in JP-A-2004-95450, Chem. Commun., 4887 (2007) and the like, JP-A-2003-264010. JP-A-2004-63274, JP-A-2004-115636, JP-A-2004-200068, JP-A-2004-235052, J. Am. Chem. Soc., 12218, Vol.126 (2004) , Chem. Commun., 3036 (2003), Angew. Chem. Int. Ed., 1923, Vol. 47 (2008), etc. 2006), J. Am. Chem. Soc., 14256, Vol.128 (2006) and the like, thiophene compounds, JP-A-11-86916, JP-A-11-214730, JP-A-2000-106224. , JP-A-2001-76773, Cyanine dyes described in JP-A-2003-7359, JP-A-11-214731, JP-A-11-238905, JP-A-2001-52766, JP-A-2001. -76775, Japanese Patent Application Laid-Open No. 2003-7360, etc. Described in JP-A-10-92477, JP-A-11-273754, JP-A-11-273755, JP-A-2003-31273, etc. 9-arylxanthene compounds, triarylmethane compounds described in JP-A-10-93118, JP-A-2003-31273, etc., JP-A-9-199744, JP-A-10-233238, JP-A-11- No. 204821, JP-A-11-265738, J. Phys. Chem., 2342, Vol.91 (1987), J. Phys. Chem. B, 62 72, Vol.97 (1993), Electroanal. Chem., 31, Vol.537 (2002), JP-A-2006-032260, J. Porphyrins Phthalocyanines, 230, Vol.3 (1999), Angelw. Chem. Int Phthalocyanine compounds, porphyrin compounds and the like described in Ed., 373, Vol.46 (2007), Langmuir, 5436, Vol.24 (2008) and the like can be mentioned.

As a method of adsorbing the sensitizing dye on the electron transport layer 4, for example, a method of immersing the electron transport particles of the electron transport layer 4 in the sensitizing dye solution or the dispersion liquid, or a method of immersing the solution or the dispersion liquid in the electron transport layer 4. A method of applying and adsorbing can be used.

In the former case, the dipping method, dip method, roller method, air knife method, etc. can be used, and in the latter case, the wire bar method, slide hopper method, extrusion method, curtain method, spin method, spray method, etc. can be used. Can be used.
Further, it may be adsorbed in a supercritical fluid using carbon dioxide or the like.

When adsorbing the sensitizing dye, a condensing agent may be used in combination.
The condensing agent has a catalytic action that seems to physically or chemically bind the sensitizing dye and the electron-transporting particles of the electron-transporting layer 4 to the surface of the inorganic substance, or acts stoichiometrically to achieve a chemical equilibrium. It may be any of those that move in an advantageous manner.
Further, a thiol or a hydroxy compound may be added as a condensation aid.

The solvent for dissolving or dispersing the sensitizing dye is an alcohol solvent such as water, methanol, ethanol, or isopropyl alcohol, a ketone solvent such as acetone, methyl ethyl ketone, or methyl isobutyl ketone, ethyl formate, ethyl acetate, or n acetate. -Ester solvent such as butyl, ether solvent such as diethyl ether, dimethoxyethane, tetrahydrofuran, dioxolan, or dioxane, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, etc. Halogen-based solvents such as amide-based solvents, dichloromethane, chloroform, bromoform, methyl iodide, dichloroethane, trichloroethane, trichloroethylene, chlorobenzene, o-dichlorobenzene, fluorobenzene, bromobenzene, iodobenzene, or 1-chloronaphthalene, Carbohydrates such as n-pentane, n-hexane, n-octane, 1,5-hexadiene, cyclohexane, methylcyclohexane, cyclohexadiene, benzene, toluene, o-xylene, m-xylene, p-xylene, ethylbenzene, or cumene. Examples thereof include system solvents, and these can be used alone or as a mixture of two or more kinds.

The content of the compound represented by the general formula (1) can be appropriately changed, but is preferably 0.00001 to 0.01 parts by mass with respect to 100 parts by mass of the solvent.

Further, the electron-transporting compound 11 in the present embodiment carries a compound represented by the following general formula (2). The compound represented by the following general formula (2) has an action as a co-adsorbent (aggregate dissociator) that suppresses the interaction between the compounds of the sensitizing dye.

(In the formula, R ₄ represents an aryl group or a heterocyclic group, and R ₅ represents an alkyl group, an alkoxy group, an alkenyl group, an alkylthio group or an aryl ether group.)

In addition, R ₄ and R ₅ may have a substituent.

The compound represented by the general formula (2) is preferably a compound represented by the following general formula (5).

(In the formula, R ₈ represents an alkyl group, an alkenyl group or an aryl group, and n represents an integer of 1 to 3).

_In addition, R8 may have a substituent.

Specific examples of the compound represented by the general formula (2) include, but are not limited to, (C-01) to (C-55) shown below.

The amount of the compound represented by the general formula (2) to be added is preferably 0.01 to 500 parts by mass, preferably 0.1 to 100 parts by mass with respect to 1 part by mass of the compound represented by the general formula (1). Is more preferable.

Using these, the temperature at which the sensitizing dye and the co-adsorbent are adsorbed on the electron-transporting compound is preferably −50 ° C. or higher and 200 ° C. or lower.

Further, this adsorption may be carried out by allowing it to stand still or stirring it. Examples of the method for stirring include, but are not limited to, a stirrer, a ball mill, a paint conditioner, a sand mill, an attritor, a disperser, and ultrasonic dispersion.

The adsorption time can be appropriately changed, but is preferably 5 seconds or more and 1000 hours or less, more preferably 10 seconds or more and 500 hours or less, and further preferably 1 minute or more and 150 hours. Adsorption is preferably performed in a dark place.

In addition, a method of first adsorbing the sensitizing dye and then adsorbing the co-adsorbent, a method of first adsorbing the co-adsorbent and then adsorbing the sensitizing dye, or using the same solvent as the sensitizing dye and the co-adsorbent. Any method of dissolving and adsorbing at the same time may be used.

In the present embodiment, the combination of the sensitizing dye represented by the general formula (1) and the co-adsorbent represented by the general formula (2) can be easily detected by HPLC, and thus is dissolved in the dye solution. The concentration of the sensitizing dye and the co-adsorbent can be easily measured, and the method of managing the dye solution becomes easy.

<Charge transfer layer>
The charge transfer layer 7 in the present embodiment contains, for example, an electrolytic solution in which a redox pair is dissolved in an organic solvent, a gel electrolyte in which a liquid in which a redox pair is dissolved in an organic solvent is impregnated in a polymer matrix, and a redox pair. A molten salt, a solid electrolyte, an inorganic hole transport material, an organic hole transport material, or the like can be used.

The electrolytic solution is preferably composed of an electrolyte, a solvent, and an additive. Preferred electrolytes are metal iodide-iodine combinations such as lithium iodide, sodium iodide, potassium iodide, cesium iodide, calcium iodide, tetraalkylammonium iodide, pyridinium iodide, imidazolium iodide and the like 4 Iodine salt-iodine combination of grade ammonium compound, metal bromide such as lithium bromide, sodium bromide, potassium bromide, cesium bromide, calcium bromide-bromine combination, tetraalkylammonium bromide, pyridinium bromide, etc. Bromine salt-bromine combination of ammonium compound, metal complex such as ferrocyanate-ferricate, ferrosen-ferricinium ion, sulfur compound such as polysodium sulfide, alkylthiol-alkyldisulfide, viologen dye, hydroquinone-quinone , Metal complexes such as cobalt, nitroxidoradic compounds and the like. The above-mentioned electrolytes may be a single combination or a mixture. Further, when an ionic liquid such as imidazolinium iodide is used, it is not necessary to use a solvent in particular.

The electrolyte concentration in the electrolytic solution is preferably 0.05 to 20 M, more preferably 0.1 to 15 M. As the solvent used for the electrolytic solution, a carbonate solvent such as ethylene carbonate and propylene carbonate, a heterocyclic compound such as 3-methyl-2-oxazolidinone, an ether solvent such as dioxane, diethyl ether and ethylene glycol dialkyl ether, methanol and ethanol. , Alcohol-based solvents such as polypropylene glycol monoalkyl ether, nitrile-based solvents such as acetonitrile and benzonitrile, aprotonic polar solvents such as dimethylsulfoxide and sulfolane, and the like, and t-butylpyridine, 2-picolin, 2, A basic compound such as 6-lutidine may be used in combination.

In the present embodiment, the electrolyte can also be gelled by a method such as addition of a polymer, addition of an oil gelling agent, polymerization containing polyfunctional monomers, or a cross-linking reaction of the polymer. Preferred polymers for gelling by adding a polymer include polyacrylonitrile and polyvinylidene fluoride. Preferred gelling agents for gelling by adding an oil gelling agent include dibenzylden-D-sorbitol, cholesterol derivatives, amino acid derivatives, alkylamide derivatives of trans- (1R, 2R) -1,2-cyclohexanediamine, and alkylurea. Derivatives, N-octyl-D-gluconamide benzoate, double-headed amino acid derivatives, quaternary ammonium derivatives and the like can be mentioned.

Preferred monomers for polymerization with a polyfunctional monomer include divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate and the like. be able to. Furthermore, esters and amides derived from acrylic acids such as acrylamide and methyl acrylate and α-alkyl acrylic acid, esters derived from maleic acid and fumaric acid such as dimethyl maleate and diethyl fumarate, butadiene and cyclo Dienes such as pentadiene, aromatic vinyl compounds such as styrene, p-chlorostyrene and sodium styrene sulfonate, vinyl esters, acrylonitrile, methacrylonitrile, vinyl compounds having a nitrogen-containing heterocycle, and vinyl having a quaternary ammonium salt. It may contain a monofunctional monomer such as a compound, N-vinylformamide, vinylstyrene, vinylidenefluoride, vinylalkyl ethers, N-phenylmaleimide and the like.

The polyfunctional monomer in the total amount of the monomer is preferably 0.5 to 70% by mass, more preferably 1.0 to 50% by mass.

The above-mentioned monomers can be polymerized by radical polymerization. The gel electrolyte monomer that can be used in this embodiment can be radically polymerized by heating, light, electron beam or electrochemically. The polymerization initiators used when the crosslinked polymer is formed by heating are 2,2'-azobisisobutyronitrile, 2,2'-azobis (2,4-dimethylvaleronitrile), dimethyl-2. , 2'-Azobis (2-methylpropionate) and other azo-based initiators, benzoylper oxide and other peroxide-based initiators are preferable. The amount of these polymerization initiators added is preferably 0.01 to 20% by mass, more preferably 0.1 to 10% by mass, based on the total amount of the monomers.

When the electrolyte is gelled by the cross-linking reaction of the polymer, it is desirable to use a polymer containing a reactive group necessary for the cross-linking reaction and a cross-linking agent in combination. Preferred examples of the crossable reactive group include nitrogen-containing heterocycles such as pyridine, imidazole, thiazole, oxazole, triazole, morpholine, piperidine and piperazine, and preferred cross-linking agents are alkyl halides and halogens. Examples thereof include bifunctional or higher functional reagents capable of electrophoretic reaction with nitrogen atoms such as chemical aralkyl, sulfonic acid ester, acid anhydride, acid chloride, and isocyanate.

<< Inorganic hole transport layer >>
It is also possible to use an inorganic solid compound as the charge transfer layer 7 to form an inorganic hole transport layer. When an inorganic solid compound is used instead of the electrolyte, copper iodide, copper thiocyanide, or the like can be introduced into the electrode by a method such as a casting method, a coating method, a spin coating method, a dipping method, or electrolytic plating.

<< Organic Hall Transport Layer >>
Further, in the present embodiment, an organic charge transporting substance may be used instead of the electrolyte to form an organic hole transporting layer. The organic hole transport layer in the present embodiment may be a single layer structure made of a single material or a laminated structure made of a plurality of compounds. In the case of a laminated structure, it is preferable to use a polymer material for the organic hole transport material layer near the second electrode 8. This is because the surface of the porous electron transport layer can be further smoothed and the photoelectric conversion characteristics can be improved by using a polymer material having excellent film forming properties. In addition, since it is difficult for the polymer to penetrate into the porous electron transport layer, it is also excellent in covering the surface of the porous electron transport layer, and is also effective in preventing short circuits when providing electrodes. Therefore, it is possible to obtain higher performance.

A known organic hole transport compound can be used as the organic hole transport material used in the single layer structure used as a single layer, and specific examples thereof are shown in Japanese Patent Publication No. 34-5466 and the like. Oxadiazol compounds, triphenylmethane compounds shown in Japanese Patent Publication No. 45-555, pyrazoline compounds shown in Japanese Patent Publication No. 52-4188, etc., shown in Japanese Patent Publication No. 55-42380, etc. Hydrazone compounds, oxadiazole compounds shown in JP-A-56-123544, tetraarylbenzidine compounds shown in JP-A-54-58445, JP-A-58-65440. Alternatively, the stillben compound shown in JP-A-60-98437, the spiro-type compound shown in JP-A-11-513522, and the like can be mentioned. Of these, tetraarylbenzidine compounds and spiro-type compounds are particularly preferable.

As the organic hole transport material used in this embodiment, a compound represented by the following general formula (6) is preferable.

(In the formula, R ₉ to R ₁₂ independently represent the same or different amino groups.)

R ₉ to R ₁₂ may have a substituent. Examples of R ₉ to R ₁₂ include a dimethylamino group, a diphenylamino group, a naphthyl-4-tolylamino group and the like.

Specific examples of the compound represented by the general formula (6) include, but are not limited to, (D-1) to (D-20) shown below.

Further, various additives may be added to the organic hole transport compound shown above.
Additives include iodine, lithium iodide, sodium iodide, potassium iodide, cesium iodide, calcium iodide, copper iodide, iron iodide, silver iodide and other metal iodides, tetraalkylammonium iodide, Quorary ammonium salts such as pyridinium iodide, metallic bromide such as lithium bromide, sodium bromide, potassium bromide, cesium bromide, calcium bromide, tetraalkylammonium bromide, pyridinium bromide and other quaternary ammonium compounds. Metal chlorides such as bromine salt, copper chloride and silver chloride, metal acetates such as copper acetate, silver acetate and palladium acetate, metal sulfates such as copper sulfate and zinc sulfate, ferrocyanate-ferricyanate and ferrocene. -Metal complex such as ferricinium ion, sulfur compound such as polysodium sulfide, alkylthiol-alkyldisulfide, viologen dye, hydroquinone, etc., 1,2-dimethyl-3-n-propylimidazolinium salt iodide, 1 iodide -Methyl-3-n-hexyl midazolinium salt, 1,2-dimethyl-3-ethylimidazolium trifluoromethanesulfonate, 1-methyl-3-butylimidazolium nonafluorobutylsulfonate, 1-methyl -3-Ethylimidazolium Bis (trifluoromethyl) sulfonylimide and the like ionic liquids according to Inorg. Chem. 35 (1996) 1168, pyridine, 4-t-butylpyridine, basic compounds such as benzimidazole, lithium trifluo. Examples thereof include lithium compounds such as lomethanesulfonylimide and lithium diisopropylimide.

Further, for the purpose of improving the conductivity, an oxidizing agent for converting a part of the organic hole transport compound into a radical cation may be added. Examples of the oxidizing agent include tris (4-bromophenyl) aminium hexachloroantimonate, hexafluoroantimonate silver, nitrosonium tetrafluoroborate, silver nitrate, cobalt complex, copper complex and the like. It is not necessary that all the organic hole transport materials are oxidized by the addition of this oxidizing agent, and only a part thereof needs to be oxidized. Further, the added oxidizing agent may or may not be taken out of the system after being added.

When the hole transport layer is formed by using an inorganic or organic hole transport compound, the hole transport layer is directly formed on the electron transport layer 4 having the sensitizing dye on the surface. The method for producing these solid hole transport layers is not particularly limited, and examples thereof include a method of forming a thin film in vacuum such as vacuum deposition and a wet film forming method. In consideration of manufacturing cost and the like, the wet film forming method is particularly preferable, and the method of coating on the electron transport layer is preferable.

When the wet film forming method is used, the coating method is not particularly limited and can be carried out according to a known method. For example, dip method, spray method, wire bar method, spin coating method, roller coating method, blade coating method, gravure coating method, and various wet printing methods such as letterpress, offset, gravure, intaglio, rubber plate, screen printing, etc. Method can be used.

Further, the film may be formed in a supercritical fluid or a subcritical fluid.
As a supercritical fluid, it exists as a non-aggregating high-density fluid in a temperature / pressure region exceeding the limit (critical point) where gas and liquid can coexist, does not aggregate even when compressed, and has a critical temperature or higher and a critical pressure. The fluid is not particularly limited as long as it is in the above state, and can be appropriately selected depending on the intended purpose, but a fluid having a low critical temperature is preferable.

This supercritical fluid includes, for example, carbon monoxide, carbon dioxide, ammonia, nitrogen, water, methanol, ethanol, ercoal solvents such as n-butanol, ethane, propane, 2,3-dimethylbutane, benzene, toluene and the like. Hydrocarbon-based solvents, halogen-based solvents such as methylene chloride and chlorotrifluoromethane, and ether-based solvents such as dimethyl ether are suitable. Among these, carbon dioxide is particularly preferable because it has a critical pressure of 7.3 MPa and a critical temperature of 31 ° C., so that a supercritical state can be easily created, and it is nonflammable and easy to handle.
Further, these fluids may be used alone or in a mixture of two or more kinds.

The subcritical fluid is not particularly limited as long as it exists as a high-pressure liquid in the temperature and pressure regions near the critical point, and can be appropriately selected depending on the intended purpose.
The above-mentioned compounds listed as supercritical fluids can also be suitably used as subcritical fluids.

The critical temperature and critical pressure of the supercritical fluid are not particularly limited and can be appropriately selected depending on the intended purpose. However, the critical temperature is preferably -273 ° C or higher and 300 ° C or lower, and 0 ° C or higher and 200 ° C or lower. preferable.

Further, in addition to the above-mentioned supercritical fluid and subcritical fluid, an organic solvent or an entrainer can be used in combination. By adding an organic solvent and an entrainer, the solubility in a supercritical fluid can be adjusted more easily.

Such an organic solvent is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a ketone solvent such as acetone, methyl ethyl ketone, or methyl isobutyl ketone, ethyl formate, ethyl acetate, or n acetate. -Ester solvent such as butyl, ether solvent such as diisopropyl ether, dimethoxyethane, tetrahydrofuran, dioxorane, or dioxane, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, etc. Halogen-based solvents such as amide-based solvents, dichloromethane, chloroform, bromoform, methyl iodide, dichloroethane, trichloroethane, trichloroethylene, chlorobenzene, o-dichlorobenzene, fluorobenzene, bromobenzene, iodobenzene, or 1-chloronaphthalene, Carbohydrates such as n-pentane, n-hexane, n-octane, 1,5-hexadiene, cyclohexane, methylcyclohexane, cyclohexadiene, benzene, toluene, o-xylene, m-xylene, p-xylene, ethylbenzene, or cumene. Examples include system solvents.

In the present embodiment, the hole transport material may be provided on the electron transport layer 4 provided with the electron transport compound having the sensitizing dye on the surface, and then the press treatment step may be performed. It is believed that this press treatment will improve the efficiency because the hole transport material will be in closer contact with the porous electrode. The press processing method is not particularly limited, and examples thereof include a press molding method using a flat plate as typified by an IR tablet shaper, and a roll press method using a roller or the like. The pressure is preferably 10 kgf / cm ² or more, and more preferably 30 kgf / cm ² or more. The press processing time is not particularly limited, but it is preferably performed within 1 hour. Further, heat may be applied during the pressing process.

Further, during the above-mentioned pressing process, a mold release material may be sandwiched between the pressing machine and the electrode. As the release material, polytetrafluoroethylene, polychlorotrifluoroethylene, tetrafluoride ethylene hexafluoride propylene copolymer, perfluoroalkoxyfluororesin, polyvinylidene fluoride, ethylene tetrafluoride ethylene copolymer, ethylene chloro Examples thereof include ethylene trifluoride copolymers and fluororesins such as polyvinyl fluoride.

After performing the above press processing step and before providing the second electrode 8, a metal oxide may be provided between the organic hole transport compound and the second electrode 8. Examples of this metal oxide include molybdenum oxide, tungsten oxide, vanadium oxide, nickel oxide and the like, and molybdenum oxide is particularly preferable.

The method of providing these metal oxides on the hole transport material is not particularly limited, and examples thereof include a method of forming a thin film in vacuum such as sputtering and vacuum vapor deposition, and a wet film forming method.
In the wet film forming method, a method of preparing a paste in which a metal oxide powder or a sol is dispersed and applying the paste on the hole transport layer is preferable.

When this wet film forming method is used, the coating method is not particularly limited and can be carried out according to a known method. For example, dip method, spray method, wire bar method, spin coating method, roller coating method, blade coating method, gravure coating method, and various wet printing methods such as letterpress, offset, gravure, intaglio, rubber plate, screen printing, etc. Method can be used.
The film thickness of the charge transfer layer 7 can be appropriately changed, but is preferably 0.1 to 50 nm, more preferably 1 to 10 nm.

<Second electrode>
In the present embodiment, there are roughly two methods for forming the charge transfer layer 7. One is a method in which the second electrode 8 is first bonded on the electron transport layer 4 having a sensitizing dye, and a liquid charge transfer layer is sandwiched between the gaps, and the other is a method of directly charging the electron transport layer 4. This is a method of imparting the moving layer 7. In the latter case, the second electrode 8 will be newly added thereafter.

In the former case, examples of the method of sandwiching the charge transfer layer 7 include a normal pressure process that utilizes a capillary phenomenon due to immersion and the like, and a vacuum process that replaces the gas phase with a liquid phase at a pressure lower than the normal pressure. In the latter case, in the wet charge transfer layer 7, it is necessary to apply the second electrode 8 in an undried state to prevent liquid leakage at the edge portion. Further, in the case of a gel electrolytic solution, there is also a method of applying it in a wet manner and solidifying it by a method such as polymerization. In that case, the second electrode 8 may be applied after drying and immobilization.

As a method for applying a solution of an organic charge transport material or a gel electrolyte in addition to the electrolytic solution, the dipping method, the roller method, the dip method, the air knife method, and the extrusion method are used in the same manner as the method of applying the semiconductor fine particle-containing layer and the dye. , Slide hopper method, wire bar method, spin method, spray method, casting method, various printing methods and the like.

As the second electrode 8, a substrate having conductivity similar to that of the first electrode 2 described above can be usually used, but the substrate is not always necessary as long as the structure is such that the strength and the sealing property are sufficiently maintained. not.
Specific examples of the material used for the second electrode include metals such as platinum, gold, silver, copper, aluminum, rhodium and indium, and conductive metal oxides such as carbon, ITO and FTO. The thickness of the second electrode 8 is not particularly limited and can be appropriately changed.

When an inorganic hole transport material or an organic hole transport material is used for the charge transfer layer 7, the second electrode 8 is newly applied after the solid hole transport layer is formed or on the above-mentioned metal oxide. As the second electrode 8, the same one as the above-mentioned first electrode 2 can be usually used, and a support is not always necessary in a configuration in which the strength and the sealing property are sufficiently maintained. Specific examples of the second electrode 8 material include metals such as platinum, gold, silver, copper and aluminum, carbon-based compounds such as graphite, fullerene and carbon nanotubes, conductive metal oxides such as ITO and FTO, polythiophene and polyaniline. Such as conductive polymers.

The film thickness of the second electrode 8 is not particularly limited, and may be used alone or in a mixture of two or more kinds. The coating of the second electrode 8 can be appropriately formed on the hole transport layer by a method such as coating, laminating, vapor deposition, CVD, or bonding, depending on the type of material used and the type of hole transport layer.

In order to operate as a photoelectric conversion element, it is preferable that at least one of the first electrode 2 and the second electrode 8 is substantially transparent. In the photoelectric conversion element of the present embodiment, the method in which the first electrode 2 side is transparent and sunlight is incident from the first electrode 2 side is preferable. In this case, it is preferable to use a material that reflects light on the second electrode 8 side, and a metal, glass, plastic, or a metal thin film on which a conductive oxide is vapor-deposited is preferable. It is also an effective means to provide an antireflection layer on the incident side of sunlight.

<Absorption wavelength control layer>
The photoelectric conversion element of the present invention may have an absorption wavelength control layer 12. By controlling the light incident on the inside of the electrode by the absorption wavelength control layer 12, high power generation performance can be maintained for a long period of time. As shown in FIG. 3, the absorption wavelength control layer 12 is provided on the first electrode 2 and on the opposite side of the electron transport layer 4. Although the blocking layer 3 is shown in FIG. 3, the blocking layer 3 and the absorption wavelength control layer 12 may exist at the same time or may exist separately.

As the absorption wavelength control layer 12, for example, a wavelength cut film, a filter, or the like can be used. Further, the absorption wavelength control layer 12 preferably has a total light transmittance of 90% or more and an ultraviolet light cut rate of 99% or more with a wavelength of 385 nm or less.

By providing the absorption wavelength control layer 12, light in the near-ultraviolet light region (250 to 350 nm) having a low contribution to photoelectric conversion is excluded, and the visible light region (350 to 800 nm) having a high contribution to photoelectric conversion is excluded. ) Can be selectively taken into the electrode. This makes it possible to prevent photodegradation of organic materials such as sensitizing dyes and electrolytes.

In the present embodiment, as the method for forming the absorption wavelength control layer, for example, two methods can be mentioned. One is a method in which a wavelength cut film having an adhesive layer in advance is directly attached to the surface of a substrate (or electrode) on the side where light is incident. The other is a method of attaching a wavelength cut film or filter having no adhesive layer to the surface of the substrate (or electrode) via an adhesive.

In the former case, after the wavelength cut film is attached, the wavelength cut film is brought into close contact with the surface of the substrate by a roller, a press or the like.
In the latter case, a wavelength cut film or filter is attached to the surface of the substrate by using a photocurable resin that cures in a region not included in the wavelength cut region, a two-component mixed curing resin that does not require light for curing, or the like. Glue. The resin used for adhesion is preferably a resin having a high total light transmittance after curing.

<Frame structure>
In the present invention, a frame structure via a pin header can be formed as an electrode terminal extraction portion of the photoelectric conversion element.
For example, in the case of a transparent conductive film formed on a glass surface, poor connection of electrode terminals may occur due to high smoothness and difficulty in soldering. On the other hand, when the frame structure is formed, the connectivity of the electrode terminals of the photoelectric conversion element can be improved, and high conversion efficiency can be maintained for a longer period of time.

In the present embodiment, a frame structure is formed by connecting the first electrode 2 and the pin header. Two methods for connecting the first electrode 2 and the pin header include, for example, a structure in which the pin header itself has a force for sandwiching the glass substrate and a structure in which the pin header and the transparent conductive film are brought into close contact with each other by external stress.

In the former case, it is preferable to have a sufficient connection length in order to have a pinching force. Specific connection components include, for example, a clip terminal (537-0.7 manufactured by WAKO).
In the latter case, the transparent conductive film and the pin header are connected by a physical stress via an elastic member such as a rubber connector. Specific examples thereof include a method of fixing with a resin frame such as polycarbonate by screwing or ultrasonic welding while maintaining physical stress. As the ultrasonic welding method, ultrasonic bonding conditions capable of resin welding, which are practically used in the field of automobiles and the like, can be applied.

An example of the frame structure is shown in FIG. FIG. 4A is a schematic cross-sectional view in the case of a frame structure, and FIG. 4B is a schematic diagram of a main part of a light receiving portion. As shown, the photoelectric conversion element 20 is sealed with the cover glass 22 by the sealing resin 24. Here, the take-out electrode 23 is formed and sealed. Further, the polycarbonate resin 27, the carbon rubber 25, and the metal pin 26 are configured as shown in the figure to form a frame structure. Reference numeral 21 in FIG. 4 may be the substrate 1 or the first electrode 2.

<Use>
The photoelectric conversion element of this embodiment can be applied to a solar cell, a power supply device using a solar cell, or the like. As an application example, any device that uses a conventional solar cell or a power supply device using the conventional solar cell can be used. For example, it may be used for a solar cell for an electronic desk computer or a wristwatch, and as an example of utilizing the features of the photoelectric conversion element of the present embodiment, a power supply device such as a mobile phone, an electronic personal organizer, or an electronic paper can be mentioned. It can also be used as an auxiliary power source to prolong the continuous use time of rechargeable or dry battery type electric appliances.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to the following Examples. Hereinafter, Reference Example 1 is referred to as Reference Example 1A, and Examples 1 to 31, 36 to 39 are referred to as Reference Examples 1 to 31, 36 to 39 not included in the present invention.

(Example 1)
<Preparation of electron transport layer 4>
A solution containing 2 ml of titanium tetra-n-propoxide, 4 ml of acetic acid, 1 ml of ion-exchanged water, and 40 ml of 2-propanol was spin-coated on an FTO glass substrate (first electrode 2), dried at room temperature, and then 450 in the air. It was baked at ° C for 30 minutes. Using the same solution again, it was applied on the first electrode 2 by spin coating so as to have a film thickness of 100 nm, and fired in air at 450 ° C. for 30 minutes to form the blocking layer 3.

A bead mill treatment was carried out with 3.0 g of titanium oxide (P-25 manufactured by Nippon Aerodil Co., Ltd.) and 0.3 g of acetylacetone together with 5.5 g of water and 1.2 g of ethanol for 12 hours to obtain a dispersion liquid. A surfactant (polyoxyethylene octylphenyl ether manufactured by Wako Pure Chemical Industries, Ltd.) (0.3 g) and polyethylene glycol (# 20,000) (1.2 g) were added to the obtained dispersion to prepare a paste. This paste was applied onto the blocking layer 3 to a thickness of 2.0 μm, dried at room temperature, and then fired in air at 500 ° C. for 30 minutes to form a porous titanium oxide semiconductor electrode.

A 2-ethoxyethanol solution (dye solution) of the sensitizing dye shown by the exemplary compound (B-5) adjusted to 0.5 mM and the exemplary compound (C-12) adjusted to 1.0 mM of the titanium oxide semiconductor electrode. ), And allowed to stand in a dark place for 1 hour at room temperature to adsorb the sensitizing dye to prepare an electron transport layer 4.

<Manufacturing and evaluation of photoelectric conversion element>
The solution obtained by dissolving the exemplary compound (D-7) (0.1 M), trifluoromethanesulfonylimide lithium (27 mM), and 4-t-butyl pyridine (0.11 M) in chlorobenzene on the electron transport layer 4. Was formed by spin coating and air-dried. As a result, the charge transfer layer 7 was formed. Silver was vacuum-deposited on this by about 100 nm to form a second electrode 8, and a photoelectric conversion element was manufactured.

The obtained photoelectric conversion element was irradiated with pseudo-sunlight generated from a solar simulator (AM1.5, 100 mW / cm ² ) from the first electrode 2 side to evaluate the solar cell characteristics. As a result, the open circuit voltage was 0.91 V, the short circuit current density was 6.70 mA / cm ² , the shape factor was 0.64, and the conversion efficiency was 3.90%.

(Examples 2 to 8)
A photoelectric conversion element was produced and evaluated in the same manner as in Example 1 except that the exemplary compound (C-12) in Example 1 was changed to the exemplary compound shown in Table 1. The results are shown in Table 1.

Comparing Examples 1 to 8, all have good conversion efficiencies, but as a co-adsorbent, an alkoxy group was introduced into a hydrocarbon-based aromatic ring such as C-12, 13, 16, 22, or 28. The compound showed particularly excellent performance, and the one in which the alkyl group was introduced into the thiophene ring and the hydrocarbon-based aromatic ring in which the phenoxy group having an alkyl group was introduced showed the next excellent performance.

(Examples 9 to 16)
Next, a durability test was performed on the obtained photoelectric conversion element. As a durability test, the outer periphery of the photoelectric conversion element produced in Examples 1 to 8 was sealed with an epoxy resin and glass, placed in an oven heated to 60 ° C. for 100 hours, and then the characteristics of the photoelectric conversion element were evaluated. Is. The results are shown in Table 2. In each case, the ratio after the durability test to the initial value is 95% or more (in other words, the reduction rate is within 95%), and it can be seen that the products have good durability.

(Comparative Examples 1 to 9)
A photoelectric conversion element was prepared and evaluated in the same manner as in Example 1 except that the exemplary compound (C-12) in Example 1 was changed to the co-adsorbent shown in Table 3. The results are shown in Table 3.

Comparing Examples 1 to 8 with Comparative Examples 1 to 3, even if the same benzoic acid derivative is used, a substance having a strong electron donating property at the p-position (4-dimethylaminobenzoic acid) or an electron aspiration strong at the p-position is absorbed. It can be seen that the performance is inferior in those having sex (4-cyanobenzoic acid, 4-bromobenzoic acid). It is considered that this is because the acidity of the carboxylic acid of each compound is different and has some influence.

Further, from Comparative Examples 4 and 5, it was found that cholic acid and chenodeoxycholic acid show relatively good performance in the initial conversion efficiency. However, since these compounds do not absorb UV, it is difficult to manage the solution using HPLC or the like. If the solution in which these compounds are dissolved is continued to be used, the dye can be quantified, but the co-adsorbent There is a problem that is difficult to quantify.

From Comparative Examples 6 to 8, it can be seen that the initial performance of phosphonic acid and sulfonic acid is very poor. It is considered that this reason is also because the acidity of the phosphonic acid or the sulfonic acid is too strong as compared with the carboxylic acid in the above-mentioned example as described above.

From Comparative Example 9, it can be seen that the 3-phenylpropionic acid having an alkyl group and a benzene ring has an alkyl group bonded to the carboxylic acid, so that the acidity of the carboxylic acid is also different, and as a result, the characteristics are deteriorated.

(Comparative Examples 10 to 18)
The outer periphery of the photoelectric conversion element produced in Comparative Examples 1 to 9 was sealed with an epoxy resin and glass, and placed in an oven heated to 60 ° C. for 100 hours. The obtained photoelectric conversion element was subjected to the same durability test as in Example 9. The results are shown in Table 4. In each case, the ratio after the durability test to the initial value is 60% or less, and it can be seen that the durability is lower than that of the above examples.

(Comparative Example 19)
A photoelectric conversion element was produced and evaluated in the same manner as in Example 1 except that the sensitizing dye represented by the exemplary compound (B-5) in Example 1 was changed to the following compound (E-1). As a result, the open circuit voltage was 0.90 V, the short circuit current density was 6.81 mA / cm ² , the shape factor was 0.62, and the conversion efficiency was 3.80%.

Next, the outer circumference of the obtained photoelectric conversion element was sealed with an epoxy resin and glass, and placed in an oven heated to 60 ° C. for 100 hours. The obtained photoelectric conversion element was subjected to the same durability test as in Example 9. As a result, the performance of open circuit voltage 0.68V, short circuit current density 3.17mA / cm ² , shape factor 0.51 and conversion efficiency 1.10% was obtained. The ratio after the durability test to the initial value is 28.9%, and it can be seen that the durability is inferior to the above-mentioned example. The results obtained are shown in Table 5.

(Comparative Example 20)
A photoelectric conversion element was produced and evaluated in the same manner as in Example 1 except that the sensitizing dye represented by the exemplary compound (B-5) in Example 1 was changed to the following compound (E-2). As a result, the open circuit voltage was 0.93 V, the short circuit current density was 4.89 mA / cm ² , the shape factor was 0.63, and the conversion efficiency was 2.87%, which were relatively good values.

Next, the outer circumference of the obtained photoelectric conversion element was sealed with an epoxy resin and glass, and placed in an oven heated to 60 ° C. for 100 hours. The obtained photoelectric conversion element was subjected to the same durability test as in Example 9. As a result, the performance of open circuit voltage 0.77V, short circuit current density 3.44mA / cm ² , shape factor 0.59, and conversion efficiency 1.56% was obtained. The ratio (decrease rate) after the durability test to the initial value is 54.3%, and it can be seen that the durability is inferior to that of the above examples. The results obtained are shown in Table 5.

(Comparative Example 21)
A photoelectric conversion element was produced and evaluated in the same manner as in Example 1 except that the sensitizing dye represented by the exemplary compound (B-5) in Example 1 was changed to the following compound (E-3). As a result, the open circuit voltage was 0.77 V, the short circuit current density was 2.59 mA / cm ² , the shape factor was 0.60, and the conversion efficiency was 1.20%, which were lower than those in the above embodiment.

Next, the outer circumference of the obtained photoelectric conversion element was sealed with an epoxy resin and glass, and placed in an oven heated to 60 ° C. for 100 hours. The obtained photoelectric conversion element was subjected to the same durability test as in Example 9. As a result, the performance of open circuit voltage 0.62V, short circuit current density 3.07mA / cm ² , shape factor 0.51 and conversion efficiency 0.97% was obtained. The ratio (decrease rate) after the durability test to the initial value is 80.8%, and it can be seen that the durability is relatively good. However, with this combination, the initial conversion efficiency is low, and it can be seen that the above embodiment is superior. The results obtained are shown in Table 5.

(Comparative Example 22)
A photoelectric conversion element was produced and evaluated in the same manner as in Example 1 except that the exemplary compound (C-12) in Example 1 was changed to the compound (E-2). As a result, the open circuit voltage was 0.87 V, the short circuit current density was 4.55 mA / cm ² , the shape factor was 0.60, and the conversion efficiency was 2.38%, which were lower than those of Example 1. Although the sensitizing dye (E-2) was used as a substitute for the co-adsorbent, the effect as that of the co-adsorbent in the above example was not obtained, and the characteristics were low. The results obtained are shown in Table 5.

In Comparative Examples 19 to 21 in Table 5, the upper row shows the initial value, and the lower row shows the value after the durability test.
From Comparative Examples 19 to 21, it can be seen that even if the exemplified compound (C-12) is used, it is inferior in the durability test if the sensitizing dye is different.

(Example 17)
The dye solution used in Example 1 was measured by HPLC. The HPLC conditions are as follows.
HPLC: LC-2010A manufactured by Shimadzu Corporation
Column: GL Science Intersil ODS-3
Eluent: THF / water = 65/35
Detection wavelength: 254 nm
The obtained results are shown in FIG. From FIG. 5, the sensitizing dye had a peak at about 6.8 minutes, and the co-adsorbent had a peak at about 5.3 minutes, and any compound could be detected.

(Comparative Example 23)
The dye solution used in Comparative Example 5 was measured by HPLC. The HPLC conditions are the same as in Example 17. The results are shown in FIG. From FIG. 6, the sensitizing dye was detected in about 6.9 minutes, but chenodeoxycholic acid, which is a co-adsorbent, could not be detected.

As described above, from Example 17 and Comparative Example 23, it is clear that the concentration can be easily controlled by HPLC measurement in the present invention.

(Example 18)
The co-adsorbent shown in the exemplary compound (C-12) adjusted to 1.0 mM in Example 1 was changed to the exemplary compound (C-12) adjusted to 0.5 mM in the same manner as in Example 1. A photoelectric conversion element was manufactured and evaluated. As a result, the open circuit voltage was 0.90 V, the short circuit current density was 6.44 mA / cm ² , the shape factor was 0.64, and the conversion efficiency was 3.71%, which were good values. The results obtained are shown in Table 6.

(Example 19)
The co-adsorbent shown in the exemplary compound (C-12) adjusted to 1.0 mM in Example 1 was changed to the exemplary compound (C-12) adjusted to 1.5 mM in the same manner as in Example 1. A photoelectric conversion element was manufactured and evaluated. As a result, the open circuit voltage was 0.90 V, the short circuit current density was 6.91 mA / cm ² , the shape factor was 0.64, and the conversion efficiency was 3.98%. The results obtained are shown in Table 6.

(Example 20)
The co-adsorbent shown in the exemplary compound (C-12) adjusted to 1.0 mM in Example 1 was changed to the exemplary compound (C-12) adjusted to 3.0 mM in the same manner as in Example 1. A photoelectric conversion element was manufactured and evaluated. As a result, the open circuit voltage was 0.89 V, the short circuit current density was 6.02 mA / cm ² , the shape factor was 0.63, and the conversion efficiency was 3.38%, which were good values. The results obtained are shown in Table 6.

(Example 21)
A photoelectric conversion element was prepared and evaluated in the same manner as in Example 1 except that 2-ethoxyethanol in Example 1 was changed to 3-methoxypropionitrile. As a result, the open circuit voltage was 0.91 V, the short circuit current density was 7.02 mA / cm ² , the shape factor was 0.63, and the conversion efficiency was 4.02%. The results obtained are shown in Table 6.

(Example 22)
A photoelectric conversion element was prepared and evaluated in the same manner as in Example 1 except that 2-ethoxyethanol in Example 1 was changed to a mixed solution of 2-methoxyethanol and 3-methoxypropionitrile in a volume ratio of 1: 1. bottom. As a result, the open circuit voltage was 0.90 V, the short circuit current density was 6.79 mA / cm ² , the shape factor was 0.64, and the conversion efficiency was 3.91%, which were good values. The results obtained are shown in Table 6.

(Example 23)
A photoelectric conversion element was prepared and evaluated in the same manner as in Example 1 except that 2-ethoxyethanol in Example 1 was changed to a mixed solution of t-butanol and acetonitrile in a volume ratio of 1: 1. As a result, the open circuit voltage was 0.90 V, the short circuit current density was 6.71 mA / cm ² , the shape factor was 0.63, and the conversion efficiency was 3.80%, which were good values. The results obtained are shown in Table 6.

(Example 24)
A photoelectric conversion element was prepared and evaluated in the same manner as in Example 1 except that 2-ethoxyethanol in Example 1 was changed to diethylene glycol dimethyl ether. As a result, the open circuit voltage was 0.88 V, the short circuit current density was 6.99 mA / cm ² , the shape factor was 0.62, and the conversion efficiency was 3.81%, which were good values. The results obtained are shown in Table 6.

(Example 25)
The conditions for adsorbing the sensitizing dye by standing in a dark place for 1 hour at room temperature in Example 1 were set in an oven heated to 60 ° C. for 15 minutes in a dark place to adsorb the sensitizing dye. A photoelectric conversion element was produced and evaluated in the same manner as in Example 1 except that the conditions were changed. As a result, the open circuit voltage was 0.90 V, the short circuit current density was 6.80 mA / cm ² , the shape factor was 0.64, and the conversion efficiency was 3.92%, which were good values. The results obtained are shown in Table 6.

(Example 26)
Except for changing the condition in Example 1 in which the sensitizing dye is adsorbed by standing in a dark place for 1 hour at room temperature, the condition is changed to a condition in which the sensitizing dye is adsorbed by standing in a dark place for 2 hours at room temperature. Made a photoelectric conversion element in the same manner as in Example 1 and evaluated it. As a result, the open circuit voltage was 0.91 V, the short circuit current density was 6.70 mA / cm ² , the shape factor was 0.64, and the conversion efficiency was 3.90%. The results obtained are shown in Table 6.

(Example 27)
A photoelectric conversion element was produced and evaluated in the same manner as in Example 1 except that the exemplary compound (D-7) in Example 1 was changed to the following compound (E-4). As a result, the open circuit voltage was 0.91 V, the short circuit current density was 6.20 mA / cm ² , the shape factor was 0.61, and the conversion efficiency was 3.44%, which were slightly lower than those of Example 1, but had good values. Indicated.
Next, the outer circumference of the photoelectric conversion element was sealed with an epoxy resin and glass, and placed in an oven heated to 60 ° C. for 100 hours. As a result, the performance of open circuit voltage 0.91V, short circuit current density 6.06mA / cm ² , shape factor 0.61 and conversion efficiency 3.36% was obtained. This value shows that the rate of decrease after the durability test is 97.7% of the initial value, and that the durability is good. The results obtained are shown in Table 6.

From Examples 1 and 18 to 20, the concentration of the co-adsorbent for the sensitizing dye adjusted to 0.5 mM has very good characteristics within the range of 0.5 mM to 1.5 mM. It can be seen that when 3.0 mM is used, the characteristics are slightly lower than those of 0.5 to 1.5 mM, but the characteristics are good.

From Examples 1 and 21 to 24, it can be seen that the organic solvent used in the present invention has good characteristics even when various solvents are used.

From Examples 1, 25 and 26, it can be seen that the temperature and time at which the dye is adsorbed in the present invention have good characteristics even when various conditions are used.

(Examples 28 to 31)
A photoelectric conversion element was produced in the same manner as in Example 1 except that the sensitizing dye shown in the exemplary compound (B-5) adjusted to 0.5 mM in Example 1 was changed to the sensitizing dye shown in Table 7. And evaluated. The results are shown in Table 7.

Comparing Examples 1 and Examples 28 to 31, all have good conversion efficiencies, but the sensitizing dyes are the exemplary compound (B-6) and the exemplary compound as opposed to the exemplary compound (B-5). It can be seen that (B-21) is almost the same, and the conversion efficiency of the exemplary compound (B-13) and the exemplary compound (B-19) is slightly lower.

(Example 32)
A photoelectric conversion element was produced and evaluated in the same manner as in Example 1 except that the exemplary compound (B-5) in Example 1 was changed to the exemplary compound (B-37). As a result, the open circuit voltage was 0.95 V, the short circuit current density was 6.85 mA / cm ² , the shape factor was 0.67, and the conversion efficiency was 4.36%, which were good values.

(Example 33)
The outer circumference of the photoelectric conversion element produced in Example 32 was sealed with an epoxy resin and glass, and placed in an oven heated to 60 ° C. for 100 hours. As a result, the open circuit voltage was 0.93 V, the short circuit current density was 6.92 mA / cm ² , the shape factor was 0.66, and the conversion efficiency was 4.24%. The conversion efficiency after the durability test is 97% of the initial value, and it can be seen that the product has good durability.

(Example 34)
A photoelectric conversion element was produced and evaluated in the same manner as in Example 1 except that the exemplary compound (B-5) in Example 1 was changed to the exemplary compound (B-38). As a result, the open circuit voltage was 0.94 V, the short circuit current density was 6.92 mA / cm ² , the shape factor was 0.66, and the conversion efficiency was 4.29%.

(Example 35)
The outer periphery of the photoelectric conversion element produced in Example 34 was sealed with an epoxy resin and glass, and placed in an oven heated to 60 ° C. for 100 hours. As a result, the open circuit voltage was 0.92 V, the short circuit current density was 7.15 mA / cm ² , the shape factor was 0.65, and the conversion efficiency was 4.27%, which were good values. The conversion efficiency after the durability test is 99% of the initial value, and it can be seen that the product has good durability.

(Comparative Example 24)
A photoelectric conversion element was produced and evaluated in the same manner as in Example 32 except that the exemplary compound (C-12) in Example 32 was changed to the above compound (E-2). As a result, the open circuit voltage was 0.88 V, the short circuit current density was 4.35 mA / cm ² , the shape factor was 0.59, and the conversion efficiency was 2.25%, which were lower than those of Example 32. Although the sensitizing dye (E-2) was used as a substitute for the co-adsorbent, the effect as that of the co-adsorbent of the present invention was not obtained, and the characteristics were low.

(Comparative Example 25)
A photoelectric conversion element was produced and evaluated in the same manner as in Example 34 except that the exemplary compound (C-12) in Example 34 was changed to the above compound (E-2). As a result, the open circuit voltage was 0.89 V, the short circuit current density was 4.43 mA / cm ² , the shape factor was 0.58, and the conversion efficiency was 2.28%, which were lower efficiencies as compared with Example 34. Although the sensitizing dye (E-2) was used as a substitute for the co-adsorbent, the effect as that of the co-adsorbent of the present invention was not obtained, and the characteristics were low.

(Example 36, Reference Example 1)
A UV cut film (Japan) on the FTO glass substrate of the photoelectric conversion element produced in Example 9 as an absorption wavelength control layer 12 having a total light transmittance of 90% and cutting 99% of light in the ultraviolet region having a wavelength of 385 nm or less. UV50) manufactured by Rika Paper Co., Ltd. was attached as shown in FIG. 3, and the characteristic values under a white LED 200lux environment were compared and evaluated with Example 9. After that, the pseudo-sunlight generated from the solar simulator (AM1.5, 100 mW / cm ² ) was continuously irradiated for 150 hours from the working electrode side, and the characteristic values under the white LED 200lux environment were compared again with and without the UV cut film. ..
As a result, in the case of the presence of the UV cut film (Example 36), the output decreased by 1.76% even after continuous irradiation with pseudo-sunlight for 150 hours, showing a good value. On the other hand, in the case without the UV cut film (Reference Example 1), the output decreased by -68.82% after 150 hours of continuous irradiation with pseudo-sunlight. From this, it can be seen that the UV cut film is effective for maintaining the characteristic value under the white LED 200lux environment.

(Example 37)
In this embodiment, the frame structure shown in FIG. 4 is formed for the photoelectric conversion element manufactured in Example 36. The photoelectric conversion element produced in Example 36 was sealed with a cover glass 22 using an acrylic curable resin (TB-3035B, manufactured by ThreeBond Co., Ltd.) as the sealing resin 24. Here, the take-out electrode 23 is formed and sealed. Further, for the sealed sample, a frame structure composed of a polycarbonate resin 27, a carbon rubber 25, and a metal pin 26 was formed, and the characteristics under a white LED 500lux environment were evaluated. The frame structure was made by using an ultrasonic welding device (2000Xdt, manufactured by Branson) for an upper housing and a lower housing made of polycarbonate resin. The welding conditions were collapse: 0.15 mm, amplitude: 40%, cylinder pressure: 200 kPa, and trigger pressure: 22 N.
As a result, the open circuit voltage was 0.85 V, the short circuit current density was 41.3 μA / cm ² , the shape factor was 0.76, and the output power was 26.68 μW / cm ² .

(Example 38)
A photoelectric conversion element was produced and evaluated in the same manner as in Example 1 except that titanium oxide (P-25 manufactured by Aerodil Japan Co., Ltd.) in Example 1 was changed to zinc oxide (manufactured by CI Kasei Co., Ltd.). As a result, the open circuit voltage was 0.80 V, the short circuit current density was 5.40 mA / cm ² , the shape factor was 0.63, and the conversion efficiency was 2.72%. Although it was not as good as the one using titanium oxide of Example 1, it showed good characteristics.

(Example 39)
A photoelectric conversion element was produced and evaluated in the same manner as in Example 1 except that titanium oxide (P-25 manufactured by Nippon Aerodil Co., Ltd.) in Example 1 was changed to tin oxide (manufactured by CI Kasei Co., Ltd.). As a result, the open circuit voltage was 0.77 V, the short circuit current density was 5.90 mA / cm ² , the shape factor was 0.66, and the conversion efficiency was 3.00%. Although it was not as good as the one using titanium oxide of Example 1, it showed good characteristics.

As is clear above, it can be seen that the combination of the sensitizing dye of the present invention and the co-adsorbent has good conversion efficiency and high durability. Further, since any combination of the sensitizing dye and the co-adsorbent of the present invention can be easily detected by HPLC, it is clear that the method of managing the dye solution becomes easy.

1 Substrate 2 1st electrode 3 Blocking layer 4 Electron transport layer 5 Sensitive dye 6 Co-adsorbent 7 Charge transfer layer 8 2nd electrode 9, 10 Lead line 11 Electron transport compound 12 Absorption wavelength control layer 20 Photoelectric conversion element 21 No. 1 Substrate 22 Cover glass 23 Extraction electrode 24 Encapsulating resin 25 Carbon rubber 26 Metal pin 27 Polycarbonate resin

Japanese Unexamined Patent Publication No. 1-220380 Japanese Unexamined Patent Publication No. 11-86916 Japanese Unexamined Patent Publication No. 11-238905 Japanese Unexamined Patent Publication No. 11-144773 Japanese Unexamined Patent Publication No. 2000-106223

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Claims (9)

A photoelectric conversion element having a first electrode, an electron transport layer formed on the first electrode, a charge transfer layer, and a second electrode.
The electron transport layer is a photoelectric conversion element comprising an electron transporting compound carrying a compound represented by the following general formula (4) and a compound represented by the following general formula (2).

(In the formula, X ₁ and X ₂ represent an oxygen atom or a sulfur atom, R ₂ represents an alkyl group, an aryl group or a heterocyclic group, and R ₃ represents an acidic group, which may be the same or different. R ₆ and R ₇ represent an alkyl group or an aryl group, and R ₆ and R ₇ may be bonded to form a cyclic structure, or may be independent non-cyclic structures.)

(In the formula, R ₄ represents an aryl group or a heterocyclic group, and R ₅ represents an alkyl group, an alkoxy group, an alkenyl group, an alkylthio group or an aryl ether group.) The photoelectric conversion element according to claim 1 , wherein the general formula (2) is represented by the following general formula (5).

(In the formula, R ₈ represents an alkyl group, an alkenyl group or an aryl group, and n represents an integer of 1 to 3). The photoelectric conversion element according to claim 1 or 2 , wherein a blocking layer is provided between the first electrode and the electron transport layer. The photoelectric conversion element according to any one of claims 1 to 3 , wherein the electron transporting compound is an oxide semiconductor. The photoelectric conversion element according to claim 4 , wherein the oxide semiconductor is selected from at least one of titanium oxide, zinc oxide, tin oxide and niobium oxide. The photoelectric conversion element according to any one of claims 1 to 5 , wherein the charge transfer layer contains an organic hole transport material or an inorganic hole transport material. The photoelectric conversion element according to claim 6 , wherein the organic hole transport material is a compound represented by the following general formula (6).

(In the formula, R ₉ to R ₁₂ independently represent the same or different amino groups.) The absorption wavelength control layer is provided on the first electrode and on the opposite side of the electron transport layer.
The photoelectric conversion element according to any one of claims 1 to 7 , wherein the absorption wavelength control layer has a total light transmittance of 90% or more and an ultraviolet light cut rate of 99% or more having a wavelength of 385 nm or less. A solar cell comprising the photoelectric conversion element according to any one of claims 1 to 8 .

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