JP2007131767A - Optically functional material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photoelectric conversion sensitizing pigment which does not use exhaustible raw materials such as ruthenium, and is useful for stable pigment sensitization type photoelectric conversion cells having high solar energy conversion efficiency. <P>SOLUTION: This optically functional material represented by the general formula (1) [R<SP>1</SP>and R<SP>2</SP>are each independently a 6 to 30C alkyl; R<SP>3</SP>to R<SP>8</SP>are each independently H or a 1 to 2C alkyl; R<SP>3</SP>and R<SP>4</SP>, R<SP>5</SP>and R<SP>6</SP>, and R<SP>7</SP>and R<SP>8</SP>may each independently together form a ring; R<SP>9</SP>is a functional group represented by the general formula (2); X<SP>1</SP>is O, S or N which may be substituted with an alkyl] is disclosed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical functional material. The optical functional material can be used as a photoelectric conversion material, a light emitting material, a light absorbing material, or the like. The present invention also relates to a photoelectric conversion material using this optical functional material, a photoelectric conversion electrode, and a photoelectric conversion cell using the same.

  For solar power generation, single crystal silicon solar cells, polycrystalline silicon solar cells, amorphous silicon solar cells, and compound solar cells such as cadmium telluride and indium copper selenide have been put into practical use or are subject to research and development. It is necessary to overcome problems such as manufacturing cost, securing raw materials, and long energy payback time. On the other hand, many solar cells using organic materials aimed at increasing the area and cost have been proposed, but there is a problem that conversion efficiency is low and durability is poor.

  Under such circumstances, a photoelectric conversion electrode and a photoelectric conversion cell using a semiconductor microporous material sensitized with a dye, and a material and a manufacturing technique for producing the photoelectric conversion electrode have been disclosed (Non-patent Document 1 and Patents). Reference 1). The disclosed battery is a dye-sensitized photoelectric conversion cell comprising a titanium oxide porous thin layer spectrally sensitized with a ruthenium complex dye, an electrolyte layer mainly composed of iodine, and a counter electrode. The first advantage of this method is that an inexpensive oxide semiconductor such as titanium oxide is used, so that an inexpensive photoelectric conversion element can be provided. The second advantage is that the ruthenium complex dye used is widely absorbed in the visible light range. Therefore, relatively high conversion efficiency can be obtained.

One of the problems of such a dye-sensitized photoelectric conversion cell is that ruthenium is used as a raw material for the dye. Ruthenium has a Clarke number of 0.01 ppm, which is comparable to platinum and palladium, and is only present on the earth. Furthermore, the price of the ruthenium complex dye becomes expensive, which hinders mass diffusion of photoelectric conversion cells.

  Recently, non-ruthenium complex dyes have been actively studied as sensitizing dyes in dye-sensitized solar cells. Examples thereof include phenylxanthene dyes, phthalocyanine dyes, coumarin dyes, cyanine dyes, porphyrin dyes, azo dyes, and the like. These organic dyes are expected to have high photoelectric conversion efficiency because they have a large extinction coefficient and a large degree of freedom in molecular design as compared with ruthenium complexes. However, there are no good organic sensitizing dyes because the light absorption region of the dye is clogged or charge injection into titanium oxide is inefficient.

  In order to solve these problems, it has been disclosed that a sensitizing dye having a substituted acrylic acid moiety has a relatively high conversion efficiency as a sensitizing dye characterized by an adsorption terminal with titanium oxide (Patent Document). 2 and 3). A characteristic feature of these sensitizing dyes is that the carbon atom to which the carboxylic acid group at the end of acrylic acid is bonded simultaneously has an electron-withdrawing substituent typified by a cyano group, thereby increasing the electron withdrawing effect at the end of acrylic acid. There is in point. A sensitizing dye is bonded to the surface of an inorganic oxide semiconductor such as titanium oxide with a terminal carboxylic acid group, and excited electrons generated by light absorption of the sensitizing dye are injected into the inorganic oxide side through the carboxylic acid group. However, the electron injecting effect at this part is strengthened, so that the electron injecting effect is promoted, thereby realizing high conversion efficiency. As a typical example, a sensitizing dye combining a coumarin skeleton and an acrylic acid terminal having a cyano group achieves a high conversion efficiency of 5% or more (see Non-Patent Document 2). In addition, a high conversion efficiency of 5% or more is achieved even with a sensitizing dye in which a similar acrylic acid terminal is introduced into a chromophore in which a polyene structure and an amino group are combined (see Non-Patent Document 3).

  However, the absorption wavelength region such as coumarin skeleton is closer to the shorter wavelength side in the visible light region, so if you try to make the wavelength longer based on this skeleton, the long double bond site (polyene structure) Etc. will be introduced. Long-chain double bond sites have low durability properties such as being easily oxidized to active oxygen or the like and having low thermal stability. For the same reason, it is expected that the sensitizing dye having a polyene structure described in Non-Patent Document 3 also has a problem in durability. In addition, cyanine dyes that function as sensitizing dyes are examples of dyes that have long-chain double bond sites and have low durability.

  It does not rely on the introduction of weakly durable sites such as long-chain double bond sites, has a highly durable skeletal structure, and does not use inexpensive, depleting raw materials, and has high conversion efficiency characteristics. There has been a demand for a sensitizing dye capable of providing a photoelectric conversion cell.

Nature (Vol. 353, 737-740, 1991) Chem. Commun. (569-570, 2001) Chem. Communi. (Pp. 252-253, 2003) US Pat. No. 4,927,721 JP 2002-164089 A WO 02/11213 pamphlet

  An object of the present invention is to provide a sensitizing dye for a dye-sensitized photoelectric conversion cell that does not use a depleting raw material such as ruthenium, has a highly durable skeleton structure, is inexpensive and has high conversion efficiency performance. It is. Furthermore, a photoelectric conversion material in which this sensitizing dye is connected to the surface of the inorganic semiconductor porous body, a photoelectric conversion electrode formed by laminating the photoelectric conversion material on the conductive surface of a transparent substrate having a conductive surface, and a photoelectric conversion electrode Is to provide a photoelectric conversion cell in which a conductive counter electrode is combined through an electrolyte layer.

  As a result of intensive studies to solve the above problems, the present inventor connects a specific sensitizing dye to the surface of an inorganic oxide semiconductor layered on a transparent conductive substrate to produce a good photoelectric conversion cell. In particular, the present invention has been achieved.

That is, the present invention relates to an optical functional material represented by the following general formula (1).
General formula (1)

(In the formula (1), ^{R 1} and ^{R 2} each independently represent an alkyl group having 6 to 30 carbon atoms.
R ^{3 to} R ⁸ each independently represents a hydrogen atom or an alkyl group having 1 to 2 carbon atoms, and R ³ and R ⁴ , R ⁵ and R ⁶ , R ⁷ and R ⁸ are each independently A ring may be formed integrally.
R ⁹ represents a functional group represented by the following general formula (2).
X ¹ represents an oxygen atom, a sulfur atom, or a nitrogen atom that may be substituted with an alkyl group. )

General formula (2)

(In the formula (2), R ¹⁰ represents a bond, and k represents an integer of 0 to 2.
R ¹¹ and R ¹² each independently or integrally represent an electron withdrawing group.
X ² represents an oxygen atom, a sulfur atom, or a nitrogen atom that may be substituted with an alkyl group. )

The present invention also relates to the optical functional material according to claim ¹ , wherein R ¹ and R ² are 1,1,4,4-tetramethylbutyl groups.

The present invention also relates to the optical functional material according to claim 1 or 2, wherein R ¹¹ is a cyano group, and R ¹² is an acidic functional group or a derivative thereof which is an electron withdrawing group.

  The present invention also relates to a sensitizing dye for photoelectric conversion comprising the optical functional material.

  The present invention further relates to the above sensitizing dye comprising a sensitizing dye other than that represented by the general formula (1).

  Moreover, this invention relates to the photoelectric conversion material formed by connecting the said sensitizing dye and an inorganic semiconductor porous body.

  Moreover, this invention relates to the photoelectric conversion electrode formed by laminating | stacking the said photoelectric conversion material on a transparent electrode.

  The present invention also relates to a photoelectric conversion cell comprising the photoelectric conversion electrode, an electrolyte layer, and a conductive counter electrode.

  In the present invention, it was possible to provide a photoelectric conversion cell using a sensitizing dye of the general formula (1) and having a high photoelectric conversion efficiency with a material that is not depleted. Further, by combining the sensitizing dye of the general formula (1) and the combined sensitizing dye, the photoelectric conversion function can be expressed in a wider wavelength range with respect to sunlight than using each dye alone, and a highly efficient photoelectric conversion material A photoelectric conversion electrode and a photoelectric conversion cell could be prepared. Furthermore, since the dye does not have a polyene structure, deterioration during battery production can be prevented, and high effects on the long-term stability of the battery can be expected because light deterioration and heat deterioration are unlikely to occur.

Hereinafter, the present invention will be described in detail. First, the optical functional material of the present invention is a compound represented by the general formula (1).
In the present invention, the optical functional material newly absorbs light to newly enhance a sensitizing effect, heat generation effect, coloring effect, fading effect, phosphorescent effect, phase change effect, photoelectric conversion effect, photomagnetic effect, photocatalytic effect, and light modulation effect. In addition, it refers to a material that exhibits functions such as an optical recording effect and a radical generation effect, or conversely, a material having a light emitting function that receives these effects. Examples of the photofunctional material include a photoelectric conversion material, a light emitting material, an optical recording material, an image forming material, a photochromic material, an electroluminescent material, a photoconductive material, a dichroic material, a radical generating material, an acid generating material, and a base generating material. , Phosphorescent material, nonlinear optical material, second harmonic generation material, third harmonic generation material, photosensitive material, light absorption material, near infrared absorption material, photochemical hole burning material, optical sensing material, optical marking material, photochemistry It can be widely used for therapeutic sensitizing materials, optical phase change recording materials, photosintered recording materials, magneto-optical recording materials, photodynamic therapy dyes, photocatalytic water-decomposing sensitizing dyes, and photoelectric conversion sensitizing dyes. .

  In the present specification, since the optical functional material represented by the general formula (1) is mainly used as a sensitizing dye for photoelectric conversion, this material is mainly referred to as a sensitizing dye for photoelectric conversion or a sensitizing dye. It does not deny a wide range of applications.

  The operation mechanism of the dye-sensitized solar cell is a process in which electrons are injected from the excited sensitizing dye into the conduction band of an inorganic semiconductor such as titanium oxide after the sensitizing dye that has absorbed sunlight is photoexcited. It consists of reduction by injecting electrons from a redox system such as iodine into a sensitizing dye that is oxidized by injecting electrons into the inorganic semiconductor.

  Therefore, as a function necessary for the sensitizing dye for photoelectric conversion, the dye has a wide absorption region and can efficiently absorb sunlight, and can efficiently inject charges into an inorganic semiconductor such as titanium oxide. Can be mentioned.

  Since the sensitizing dye of the general formula (1) has a specific structure, the absorption region of the sensitizing dye can be adjusted and broadened with these sites. Conventional sensitizing dyes broaden the absorption region of the dye mainly using cyanine dyes or a polyene structure as described in Chem. Comm., Pages 252-253, 2003. When this method is used, the polyene structure is susceptible to oxidation by active oxygen and is liable to undergo photodegradation. There is also concern that the thermal stability is low. In the sensitizing dye of the general formula (1), the double bond site always has a structure sandwiched between arylenes or heteroarylenes and does not take a polyene structure, so that it can be expected that such problems can be solved.

Further, the sensitizing dye of the general formula (1) has an acidic functional group or a derivative thereof at the terminal and can be bonded to an inorganic semiconductor surface such as titanium oxide via an ester bond or the like. Electron injection into inorganic semiconductors such as these occurs efficiently.
Moreover, by taking the structure of the general formula (2), first, the acidic functional group and the electron-withdrawing group are located on the same carbon, so that this site becomes a very strong acceptor, and secondly, this strong acceptor. Is bonded to the skeleton of the general formula (1) through a double bond, so that excited electrons are injected into an inorganic semiconductor such as titanium oxide through the π-conjugated system very efficiently. Such an effect can be achieved only by taking the structure of the general formula (2).

  In addition, since the skeleton of the general formula (1) has a diphenylamino group, a donor acceptor system is constructed with a portion having an organic functional group having a donor property and an acidic functional group, and an absorption region. It can be expected to increase the efficiency of electron injection into an inorganic semiconductor such as titanium oxide with a wider area.

  Further, the chemical structure of the general formula (1) has a structure in which an acceptor site and a donor site are separated by a double bond and connected by a π-conjugated system. In this structure, electrons are localized on the donor side in the ground state, and electrons are localized on the acceptor side in the excited state. Can be carried out effectively.

  That is, it can be said that the structure of the general formula (1) is a structure that can achieve high photoelectric conversion efficiency and high stability.

  Next, each functional group in the general formula (1) will be described.

Examples of the alkyl group represented by R ¹ and R ^{2 in} the general formula (1) include linear, branched and cyclic hydrocarbon groups which may have a substituent having 1 to 30 carbon atoms. In particular, a 1,1,4,4-tetramethylbutyl group is mentioned. Since this alkyl group has solubility and stability and is a bulky substituent, it has a high effect of preventing stacking between molecules, and can achieve high performance as a sensitizing dye.

R ^{3 to} R ⁸ each independently represents a hydrogen atom, a methyl group, or an ethyl group, and R ³ and R ⁴ , R ⁵ and R ⁶ , and R ⁷ and R ⁸ are each independently integrated. May be a —CH ₂ — group, —CH ₂ —CH ₂ — group, or —CH═CH— group to form a ring.
X ¹ represents —O—, —S—, —NH—, —NR—, and R, which is an alkyl group substituted with a nitrogen atom, is a straight chain that may have a substituent having 1 to 30 carbon atoms, Examples thereof include branched and cyclic hydrocarbon groups. )

  Although there is no restriction | limiting in particular as an acidic functional group, Preferably a carboxylic acid group, a phosphonic acid group, a sulfonic acid group, a phosphinic acid group, a hydroxy group, a hydroxamic acid group, a boronic acid group, a squaric acid group etc. are mention | raise | lifted. These acidic functional groups may be derivatives thereof. The derivative is not particularly limited, and examples thereof include esters, amides, and salts having cations as counter ions.

  The functional group that forms an ester with an acidic functional group is not particularly limited as long as it forms an ester with the above acidic group, but examples include an alkyl group, an aryl group, an alkoxyalkyl group, an acyl group, Examples thereof include an alkylsilyl group and an arylsilyl group.

  Among the functional groups that form an ester with an acidic functional group, preferred are alkyl groups having 1-20 carbon atoms such as methyl, ethyl, isopropyl, and t-butyl, phenyl, tolyl, and benzyl. Group, phenacyl group, methoxymethyl group, tetrahydropyranyl group, tetrahydrofuranyl group, trimethylsilyl group, t-butyldimethylsilyl group, phenyldimethylsilyl group and the like.

  The functional group that forms an amide with an acidic functional group is not particularly limited as long as it forms an amide with the above acidic functional group. Examples include dimethylamino group, diethylamino group, diisopropylamino group, diphenyl. Examples thereof include an amino group, a pyrrolidinyl group, a piperidinyl group, a 7-nitroindolyl group, and an 8-nitrotetrahydroquinolyl group.

  The cation for forming a salt with an acidic functional group is not particularly limited as long as it is a cation that forms a salt with the above acidic group. For example, metal ions such as lithium, sodium, potassium, magnesium, and calcium And quaternary ammonium ions such as tetrabutylammonium, pyridinium, and imidazolium.

  In addition, when the sensitizing dye for photoelectric conversion of the present invention is used by adsorbing to an inorganic semiconductor such as titanium oxide, the acidic functional group is preferably a quaternary ammonium salt or a free acidic functional group, Even if it is other than these, it can be used without any problem. For example, when the acidic functional group is an ester, it can be adsorbed while being hydrolyzed in the system using an appropriate catalyst or the like when the ester is adsorbed to an inorganic semiconductor.

R ¹¹ and R ¹² each independently or integrally represent an electron withdrawing group. Preferably, R ¹¹ is an electron-withdrawing group such as a cyano group, and R ¹² is an electron-withdrawing group that is an acidic functional group or a derivative thereof.
The electron-withdrawing group in the present invention represents a functional group having a Hammett's substituent constant σ of greater than 0. These functional groups are not particularly limited, but include the above-mentioned acidic functional group, cyano group, carboxyl group. Group, nitro group, acyl group, alkyloxycarbonyl group, aryloxycarbonyl group, alkylsulfonyl group, arylsulfonyl group, amide group which may have a substituent, perfluoroalkyl group, perfluoroalkylthio group, perfluoroalkylcarbonyl group, Examples thereof include a sulfonamide group, a 4-cyanophenyl group and a halogen atom which may have a substituent.

  Among the above electron-withdrawing groups, examples of the acyl group, alkyloxycarbonyl group, aryloxycarbonyl group, amide group which may have a substituent, and halogen atom include a chlorine atom, a bromine atom and an iodine atom.

  Examples of the alkylsulfonyl group include a mesyl group, an ethylsulfonyl group, and a propylsulfonyl group.

  Examples of the arylsulfonyl group include a benzenesulfonyl group and a toluenesulfonyl group.

  Examples of the perfluoroalkyl group include a trifluoromethyl group and a pentafluoroethyl group.

  Examples of the perfluoroalkylthio group include a trifluoromethylthio group and a pentafluoroethylthio group.

  Examples of the perfluoroalkylcarbonyl group include a trifluoroacetyl group and a pentafluoroethylcarbonyl group.

  Examples of the sulfonamide group that may have a substituent include a sulfonamide group, a dimethylaminosulfonyl group, a diethylaminosulfonyl group, and a diphenylaminosulfonyl group.

  Of the electron-withdrawing groups listed above, preferred are a cyano group, a sulfonyl group, and a perfluoroalkylcarbonyl group.

  Now, since the compound of the present invention has a double bond, it can take various structural isomers such as a cis isomer and a trans isomer, but is not particularly limited, and any of them can be used well as a sensitizing dye for photoelectric conversion. can do. Further, the same can be said when a substituent or the like has a double bond.

  Table (1) shows representative examples of compounds that can be used as the sensitizing dye for photoelectric conversion of the present invention, but the present invention is not limited to these.

  Moreover, the compound represented by General formula (1) is compoundable by the method as shown, for example to Formula (3).

Formula (3)

  In the formula (3), piperidine, ammonium acetate or the like can be used as the catalyst, but is not particularly limited thereto. For example, a catalyst described in Organic Reactions Volume 15 Chapter 2 can be used.

  Moreover, as a solvent in Formula (3), ethanol, tetrahydrofuran, etc. can be used, However It does not specifically limit, The solvent as described in Organic Reactions Volume15 Chapter2 can be used.

  Furthermore, when the reaction is difficult to proceed, it may be effective to perform the reaction without using a solvent.

  Moreover, although reaction temperature may be room temperature normally, it can also be made to react by heating as needed.

When an acidic functional group or a derivative thereof is synthesized, the reaction easily proceeds if an ester derivative of an acidic functional group is used. For example, when it is desired to synthesize a carboxylic acid as an acidic functional group, the ester derivative is first synthesized and hydrolyzed under suitable conditions to obtain the desired compound in high yield.

  By the way, the sensitizing dye for photoelectric conversion used in the present invention is used in combination with other sensitizing dyes in order to supplement sunlight absorption in a region that cannot be covered by the sensitizing dye represented by the general formula (1). I can do things. Other sensitizing dyes here include azo dyes, quinacridone dyes, diketopyrrolopyrrole dyes, squarylium dyes, cyanine dyes, merocyanine dyes, triphenylmethane dyes, xanthene dyes, porphyrin dyes, Examples thereof include chlorophyll dyes, ruthenium complex dyes, indigo dyes, perylene dyes, dioxazine dyes, anthraquinone dyes, phthalocyanine dyes, naphthalocyanine dyes, and derivatives thereof. It is desirable that these sensitizing dyes have a functional group that can be linked to the surface of the porous inorganic semiconductor body in the structure. The reason is that the excited electrons of the photoexcited dye can be quickly transmitted to the conduction band of the inorganic semiconductor porous body. The functional group mentioned here includes the above-mentioned acidic functional group, etc., and a sensitizing dye is connected to the surface of the inorganic semiconductor porous body, and the excited electrons of the dye are rapidly transferred to the conduction band of the inorganic semiconductor porous body. The substituent is not limited to this as long as it has a role of communicating.

  Hereinafter, materials other than the sensitizing dye for photoelectric conversion used in the present invention will be described.

(Inorganic oxide)
The photoelectric conversion sensitizing dye used in the present invention forms a photoelectric conversion material in which the inorganic semiconductor porous body is sensitized by connecting to the surface of the inorganic semiconductor porous body through a linking group. Inorganic semiconductors generally have a photoelectric conversion function for light in a part of the region, but this surface is connected to a sensitizing dye to photoelectric conversion to the visible light and / or near infrared light region. Is possible. As the material of the inorganic semiconductor porous body, an inorganic oxide is mainly used, but the inorganic semiconductor porous body having a photoelectric conversion function by connecting a sensitizing dye is not limited thereto. Examples of inorganic semiconductors include silicon, germanium, III-V group semiconductors, and metal chalcogenides. Examples of the inorganic oxide semiconductor porous material used in the present invention include titanium oxide, tin oxide, tungsten oxide, zinc oxide, indium oxide, niobium oxide, iron oxide, nickel oxide, cobalt oxide, strontium oxide, tantalum oxide, and antimony oxide. , Lanthanoid oxides, yttrium oxides, vanadium oxides, and other porous materials, but these surfaces can be combined with a sensitizing dye to enable photoelectric conversion to the visible light and / or near infrared light region. If it becomes, it will not restrict to this. In order for the surface of the inorganic oxide semiconductor porous body to be sensitized by the sensitizing dye, it is desirable that the conduction band of the inorganic oxide be present at a position where electrons are easily received from the photoexcitation order of the sensitizing dye. For this reason, titanium oxide, tin oxide, zinc oxide, niobium oxide, etc. are particularly used among the inorganic oxide semiconductor porous bodies. Further, titanium oxide is particularly used from the viewpoint of price and environmental hygiene. In the present invention, one or more kinds can be selected and combined from the inorganic oxide semiconductor porous body.

(Porous inorganic oxide)
The inorganic semiconductor porous body has a large surface area by making it porous for the purpose of linking a large amount of sensitizing dye to the surface and thus having a highly efficient photoelectric conversion capability. As a porous method, a method of sintering inorganic oxide particles such as titanium oxide having a particle diameter of several to several tens of nanometers and then sintering the paste is widely known. If it is a method to obtain, it will not restrict to this.

(Photoelectric conversion electrode)
The photoelectric conversion material used in this invention forms a photoelectric conversion electrode by laminating | stacking on the conductive surface of the transparent base material which has an electroconductive surface.

(Conductive surface)
The conductive surface used is not particularly limited as long as it is a conductive material that absorbs less light from the visible to the near infrared region of sunlight, but ITO (indium-tin oxide) or tin oxide (fluorine or the like is doped) Metal oxides having good electrical conductivity such as zinc oxide are preferable.

(Transparent substrate)
The transparent substrate to be used is not particularly limited as long as it is a material that absorbs less light in the visible to near infrared region of sunlight. Glass substrates such as quartz, ordinary glass, BK7, lead glass, polyethylene terephthalate, polyethylene naphthalate, polyimide, polyester, polyethylene, polycarbonate, polyvinyl butyrate, polypropylene, tetraacetylcellulose, syndioctane polystyrene, polyphenylene sulfide, polyarylate Resin base materials such as polysulfone, polyester sulfone, polyetherimide, cyclic polyolefin, brominated phenoxy, and vinyl chloride can be used.

(Lamination method)
As a method of laminating the photoelectric conversion material used in the present invention on the conductive surface of a transparent substrate having a conductive surface, the inorganic oxide semiconductor is coated with inorganic oxide particles pasted on the conductive surface and then dried or sintered. A porous body is formed and immersed in a solution in which the sensitizing dye is dissolved together with the transparent base material, so that the sensitizing dye is made porous by utilizing the affinity between the inorganic porous surface and the sensitizing dye coupler. A method of bonding to a material surface is common, but is not limited to this method. In order to paste the inorganic oxide particles, the inorganic oxide particles are dispersed in water or a suitable organic solvent. Since it is important to make a paste with good dispersibility in order to laminate as an inorganic porous surface with a uniform and large surface area, an acid such as nitric acid or acetylacetone, or a dispersant such as polyethylene glycol or Triton X-100 is used as necessary. Mix into paste components and paste using a paint shaker or the like. As a method for applying the paste to the conductive surface of the transparent substrate, an application method using a spin coater, a screen printing method, an application method using a squeegee, a dipping method, a spraying method, a roller method, or the like is used. After the applied inorganic oxide paste is dried or baked, volatile components in the paste are removed, and an inorganic oxide semiconductor porous body is formed on the conductive surface of the transparent substrate. As a drying or firing condition, for example, a method of applying a thermal energy of about 30 minutes to 1 hour at a temperature of 400 ° C. to 500 ° C. is generally used. If it is the drying or baking method which can obtain a favorable electromotive force at the time of irradiation, it will not restrict to this.

In order to make a solution in which a sensitizing dye is dissolved, alcohol solvents such as ethanolbenzyl alcohol, nitrile solvents such as acetonitrile and propionitrile, halogen solvents such as chloroform, dichloromethane and chlorobenzene, diethyl ether, Ether solvents such as tetrahydrofuran, ester solvents such as ethyl acetate and succinbutyl, ketone solvents such as acetone, methyl ethyl ketone and cyclohexanone, carbonate solvents such as diethyl carbonate and propylene carbonate, hexane, octane, benzene and toluene A carbohydrate-based solvent, dimethylformamide, dimethylacetamide, dimethylsulfoxide, 1,3-dimethylimidazolinone, N-methylpyrrolidone, water and the like can be used, but are not limited thereto.

  The thickness of the inorganic oxide semiconductor porous body formed on the conductive surface of the transparent substrate is desirably 0.5 μm or more and 200 μm or less. When the film thickness is less than this range, effective conversion efficiency cannot be obtained. If the film thickness is greater than this range, it will be difficult to create such as cracking and peeling during film formation, and the distance between the surface of the inorganic oxide semiconductor porous body and the conductive surface will increase, so the generated charge will be effective on the conductive surface. Therefore, it becomes difficult to obtain good conversion efficiency.

(Photoelectric conversion cell)
The photoelectric conversion electrode used in the present invention forms a photoelectric conversion cell by combining a conductive counter electrode through an electrolyte layer.

(Electrolyte layer)
The electrolyte layer used in the present invention is preferably composed of an electrolyte, a medium, and an additive. The electrolyte of the present invention comprises I ₂ and iodide (for example, LiI, NaI, KI, CsI, Mg
A mixture of I ₂ , CaI ₂ , CuI, tetraalkylammonium iodide, pyridinium iodide, imidazolium iodide, etc., a mixture of Br ₂ and bromide (eg LiBr, etc.), Inorganic Chemistry 1996, 35, 1168-1178. The molten salt described can be used, but not limited thereto. Among these, an electrolyte in which LiI, pyridinium iodide, imidazolium iodide, or the like is mixed as a combination of I ₂ and iodide is preferable in the present invention, but is not limited to this combination.
The preferable electrolyte concentration is 0.01 M to 0.5 M in the medium I ₂ and 0.1 M to 15 M in the iodide mixture.

  The medium used for the electrolyte layer in the present invention is desirably a compound that can exhibit good ionic conductivity. Solution media include ether compounds such as dioxane and diethyl ether, chain ethers such as ethylene glycol dialkyl ether, propylene glycol dialkyl ether, polyethylene glycol dialkyl ether, and polypropylene glycol dialkyl ether, methanol, ethanol, and ethylene glycol monoalkyl. Alcohols such as ether, propylene glycol monoalkyl ether, polyethylene glycol monoalkyl ether, polypropylene glycol monoalkyl ether, polyhydric alcohols such as ethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol, glycerin, acetonitrile, glutarodinitrile, Methoxyacetonitrile, propioni Lil, nitrile compounds such as benzonitrile, ethylene carbonate, carbonate compounds such as propylene carbonate, 3-methyl-2-oxazolidinone heterocyclic compounds such as dimethyl sulfoxide, can be used aprotic polar substances such as sulfolane, water, and the like.

  In addition, a polymer can be included for the purpose of using a solid (including gel) medium. In this case, a polymer such as polyacrylonitrile or polyvinylidene fluoride is added to the solution-like medium, or a polyfunctional monomer having an ethylenically unsaturated group is polymerized in the solution-like medium to make the medium solid. To do.

As the electrolyte layer, an electrolyte that does not require a CuI or CuSCN medium, and Nature, Vol. 395, 8 Oct. Use of a hole transport material such as 2,2 ', 7,7'-tetrakis (N, N-di-p-methoxyphenylamine) -9,9'-spirobifluorene described in 1998, p583-585. Can do.

  The electrolyte layer used in the present invention may contain an additive that functions to improve the electrical output of the photoelectric conversion cell or improve the durability. Examples of additives that improve electrical output include 4-t-butylpyridine, 2-picoline, and 2,6-lutidine. MgI etc. are mention | raise | lifted as an additive which improves durability.

(Conductive counter electrode)
The conductive counter electrode used in the present invention functions as a positive electrode of the photoelectric conversion cell. Specific examples of conductive materials used for the counter electrode include metals (for example, platinum, gold, silver, copper, aluminum, rhodium, indium, etc.), metal oxides (ITO (indium-tin oxide), tin oxide (fluorine, etc.)). Including doped materials), zinc oxide), or carbon. The thickness of the counter electrode is not particularly limited, but is preferably 5 nm or more and 10 μm or less.

(How to assemble)
A photoelectric conversion cell is formed by combining the photoelectric conversion electrode and the conductive counter electrode through an electrolyte layer. In order to prevent leakage and volatilization of the electrolyte layer as necessary, sealing is performed around the photoelectric conversion cell. For sealing, a thermoplastic resin, a photocurable resin, glass frit, or the like can be used as a sealing material. The photoelectric conversion cell is made by connecting small-area photoelectric conversion cells as necessary. The electromotive voltage can be increased by combining the photoelectric conversion cells in series.

  Examples will be specifically shown below, but the present invention is not limited to the following examples. In addition, unless otherwise indicated, a number represents a weight standard.

  As a method for evaluating a sensitizing dye for photoelectric conversion, a method for assembling a photoelectric conversion cell using a sensitizing dye and measuring the conversion efficiency of the photoelectric conversion cell, with reference to FIG. 1 showing a test sample of the photoelectric conversion cell explain.

Transparent electrode The glass substrate 3 with a fluorine dope type tin oxide layer (transparent electrode layer) (Asahi Glass Co., Ltd. type U-TCO) was used.

Conductive counter electrode A conductive counter electrode in which a platinum layer (platinum electrode layer) (thickness 150 nm) was laminated by sputtering on the conductive layer of a glass substrate 3 with fluorine-doped tin oxide layer (type U-TCO, manufactured by Asahi Glass Co., Ltd.) 4 was used.

Preparation of Titanium Oxide Paste The following formulation was mixed with zirconia beads and dispersed using a paint shaker to obtain a titanium oxide paste (“part” represents part by weight).
Titanium oxide (Nippon Aerosil Co., Ltd., P25 particle size 21 nm) 6 parts Water (adjusted to pH 2 by adding nitric acid) 14 parts Acetylacetone 0.6 parts Surfactant (ICN Triton X-100) 0.04 parts PEG- # 500, 000 0.3 parts

Preparation of porous titanium oxide layer A 60μm thick mending tape is applied to the conductive surface (transparent electrode layer 3) of the transparent electrode, and a mask is made by removing the 1cm square tape. After dropping several drops, excess paste was removed with a squeegee. After air drying, all the masks were removed and baked in an oven at 450 ° C. for 1 hour to obtain a titanium oxide electrode having a titanium oxide porous layer having an effective area of 1 cm ² .

Adsorption of sensitizing dye The sensitizing dye for photoelectric conversion is dissolved in tetrahydrofuran: acetonitrile = 1: 1 (volume ratio) (concentration 0.6 mmol / L), insoluble matter is removed with a membrane filter, and the above-mentioned oxidation solution is added to this dye solution. The titanium electrode was immersed and left at room temperature for 24 hours. The immersion time was set so that the conversion efficiency was maximized by actually creating a cell and obtaining the conversion efficiency.
The colored electrode surface was washed with the solvent and alcohol used for dissolution, then immersed in a 2 mol% alcohol solution of 4-t-butylpyridine for 30 minutes, and then dried to form a porous titanium oxide adsorbed with a sensitizing dye. A photoelectric conversion electrode having the layer 1 was obtained.

Preparation of electrolyte solution An electrolyte solution having the following formulation was prepared. Methoxyacetonitrile was used as the solvent.
LiI 0.1M
I ₂ 0.05M
4-t-butylpyridine 0.5M
1-propyl-2,3-dimethylimidazolium iodide 0.6M

Assembly of Photoelectric Conversion Cell As shown in FIG. 1, a test sample of the photoelectric conversion cell was assembled. That is, the transparent electrode (the glass substrate 3 with fluorine-doped tin oxide layer) on which the titanium oxide porous layer 1 on which the sensitizing dye for photoelectric conversion is adsorbed as described above is formed, and the fluorine-doped tin oxide layer The conductive counter electrode 4 in which a platinum layer is laminated on the conductive layer of the attached glass substrate is fixed with a spacer 6 made of resin film (“High Milan” film (25 μm thickness) made by Mitsui DuPont Polychemical Co., Ltd.) interposed therebetween, The electrolyte solution layer 2 was formed by injecting the electrolyte solution into the gap. Conductive wires 7 for measuring conversion efficiency were fixed to the glass substrate 3 and the platinum counter electrode layer, respectively.

Measurement method of conversion efficiency A solar simulator (# 8116) manufactured by ORIEL is combined with an air mass filter, adjusted to a light amount of 100 mW / cm ² with a light meter to obtain a measurement light source, and irradiating a test sample of a photoelectric conversion cell with light irradiation The IV curve characteristics were measured using a KEITHLEY MODEL 2400 source meter. The conversion efficiency η was calculated by the following equation using Voc (open circuit voltage value), Isc (short circuit current value), and ff (fill factor value) obtained from the IV curve characteristic measurement.

Example 1-7
Using the compounds listed in Table 1 as sensitizing dyes, the cells were assembled and evaluated.

  The results obtained are summarized in Table 2.

^a)光電変換電極を作成し、これを蛍光灯下３０００ｌｕｘの条件で２４時間照射した後、セルを組み立て、変換効率を測定し、光暴露保存安定性を調べた。
^b)光暴露を行なわない光電変換電極を封止して、１００時間擬似太陽光を照射した場合の光電変換効率。

^a) A photoelectric conversion electrode was prepared and irradiated for 24 hours under the condition of 3000 lux under a fluorescent lamp. Then, a cell was assembled, the conversion efficiency was measured, and the light exposure storage stability was examined.
^b) Photoelectric conversion efficiency when a photoelectric conversion electrode that is not exposed to light is sealed and irradiated with simulated sunlight for 100 hours.

FIG. 1 represents a photoelectric conversion cell test sample.

Explanation of symbols

1. Titanium oxide porous layer (photosensitive sensitizing dye already adsorbed)
2. 2. Electrolyte solution layer Transparent electrode layer (fluorine-doped tin oxide)
4). 4. Pt electrode layer 5. Glass substrate 6. Resin film spacer Conversion efficiency measurement lead

Claims (8)

An optical functional material represented by the following general formula (1).
General formula (1)

(In the formula (1), ^{R 1} and ^{R 2} each independently represent an alkyl group having 6 to 30 carbon atoms.
R ^{3 to} R ⁸ each independently represents a hydrogen atom or an alkyl group having 1 to 2 carbon atoms, and R ³ and R ⁴ , R ⁵ and R ⁶ , R ⁷ and R ⁸ are each independently A ring may be formed integrally.
R ⁹ represents a functional group represented by the following general formula (2).
X ¹ represents an oxygen atom, a sulfur atom, or a nitrogen atom that may be substituted with an alkyl group. )
General formula (2)

(In the formula (2), R ¹⁰ represents a bond, and k represents an integer of 0 to 2.
R ¹¹ and R ¹² each independently or integrally represent an electron withdrawing group.
X ² represents an oxygen atom, a sulfur atom, or a nitrogen atom that may be substituted with an alkyl group. ) The optical functional material according to claim 1, wherein R ¹ and R ² are 1,1,4,4-tetramethylbutyl groups. The optical functional material according to claim 1, wherein R ¹¹ is a cyano group, and R ¹² is an acidic functional group or a derivative thereof that is an electron-withdrawing group. A sensitizing dye for photoelectric exchange, comprising the optical functional material according to claim 1. The sensitizing dye according to claim 4, further comprising a sensitizing dye other than that represented by the general formula (1). A photoelectric conversion material obtained by linking the sensitizing dye according to claim 4 or 5 and an inorganic semiconductor porous body. A photoelectric conversion electrode obtained by stacking the photoelectric conversion material according to claim 6 on a transparent electrode. A photoelectric conversion cell comprising the photoelectric conversion material according to claim 7, an electrolyte layer, and a conductive counter electrode.

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