JP2013125705A - Photoelectric conversion element and solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a full-solid dye-sensitized photoelectric conversion element and a solar cell that are excellent in photoelectric conversion efficiency and stability of a photoelectric conversion function.SOLUTION: A photoelectric conversion element has on a substrate 1: a first electrode 2; a photoelectric conversion layer 6 containing a semiconductor 5 and a sensitization dye 4; a solid hole transport layer 7; and a second electrode 8. The sensitization dye is represented by the general formula (1A) or the general formula (1B). The solid hole transport layer contains a compound represented by the general formula (2) or a polymer formed by polymerizing a multimer of the compound.

Description

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

  In recent years, solar energy has attracted attention as an energy source due to environmental problems and the like, and a method of converting into electric energy that is an easy-to-use energy form by utilizing light and heat of solar energy has been put into practical use. . Among them, a typical method is to convert sunlight into electric energy, and a photoelectric conversion element is used for this method. As photoelectric conversion elements, photoelectric conversion elements using inorganic materials such as single crystal silicon, polycrystalline silicon, amorphous silicon, cadmium telluride and indium copper selenide are widely used, and are widely used for so-called solar cells. Yes. However, since a solar cell using a photoelectric conversion element using these inorganic materials has a multi-layer pn junction structure in which silicon used as a material needs to be a high-purity product that has undergone an advanced purification process, There are problems such as complicated manufacturing processes, a large number of processes, and high manufacturing costs.

  On the other hand, research on photoelectric conversion elements using organic materials as simpler elements is also underway. For example, as described in Non-Patent Document 1, a pn junction type organic photoelectric conversion element in which a perylene tetracarboxylic acid derivative that is an n type organic dye and copper phthalocyanine that is a p type organic dye are bonded is reported. Has been. In an organic photoelectric conversion element, in order to improve the short exciton diffusion length and the thinness of the space charge layer, which are considered to be weak points, the area of the pn junction simply laminating the organic thin film is greatly increased. Attempts to ensure a sufficient number of organic dyes involved in the separation are producing results.

  In addition, for example, as described in Non-Patent Document 2, a pn junction portion is dramatically increased by combining an n-type electron conductive organic material and a p-type hole conductive polymer in a film. Thus, there is a method of performing charge separation throughout the film. In 1995, Heeger et al. Proposed a photoelectric conversion element in which a conjugated polymer as a p-type conductive polymer and fullerene as an electron conductive material were mixed.

  These photoelectric conversion elements have gradually improved their characteristics, but have not yet reached a point where they behave stably with high conversion efficiency.

  However, in 1991, Gratzel made porous titanium oxide as a compilation of enormous and detailed experiments on the sensitized photocurrent of the dye adsorbed on titanium oxide, and the area of charge separation (number of molecules contributing to charge separation). By sufficiently ensuring the above, a photoelectric conversion element having a stable operation and high conversion efficiency was successfully produced (see, for example, Non-Patent Document 3).

  In this photoelectric conversion element, the dye adsorbed on the surface of the porous titanium oxide is photoexcited, electrons are injected from the dye into the titanium oxide to become dye cations, and the dye receives electrons from the counter electrode through the hole transport layer. As the hole transport layer, an electrolytic solution in which an electrolyte containing iodine is dissolved in an organic solvent is used. This photoelectric conversion element, combined with the stability of titanium oxide, has excellent reproducibility, greatly expanding the base of research and development. This photoelectric conversion element is called a dye-sensitized solar cell and has received great expectation and attention. In this method, it is not necessary to purify an inexpensive metal compound semiconductor such as titanium oxide to a high purity, an inexpensive semiconductor can be used, and usable light extends over a wide visible light range. , It has the advantage that sunlight with a large amount of visible light components can be effectively converted into electricity.

  However, since a ruthenium complex having a resource limitation is used as the dye of the photoelectric conversion layer, there is a problem that it is necessary to use an expensive ruthenium complex or the stability over time is not sufficient. In addition, as a further problem, since dye-sensitized solar cells operate using an electrolyte as described above, a separate mechanism is required to prevent the electrolyte and iodine from being retained, discharged, or dissipated. Had a point.

  In order to avoid such an elution problem of the electrolytic solution, development of an all-solid dye-sensitized solar cell is also progressing. For example, those using the amorphous organic hole transfer agent described in Non-Patent Document 4 and those using copper iodide as the hole transfer agent described in Non-Patent Document 5 are known. However, since these hole transfer agents have low conductivity, they have not yet provided sufficient photoelectric conversion efficiency.

  Furthermore, polythiophene-based materials are typical examples of hole transfer agents with relatively high conductivity, and all-solid dye-sensitized solar cells using polyethylenedioxythiophene (PEDOT) as a hole transfer agent have been reported. (For example, refer to Patent Document 1 and Non-Patent Document 6).

  On the other hand, in order to reduce the cost of solar cells, development of dye-sensitized solar cells using organic dyes instead of ruthenium complexes is also underway. For example, a methine-based organic dye having a thiophene skeleton (Patent Document 2), an organic dye having a polythiophene skeleton having a repetition number of 5 or more (Patent Document 3), and the like have been reported.

JP 2003-317814 A International Publication No. 04/082061 Pamphlet JP 2005-135656 A

C. W. Tang: Applied Physics Letters, 48, 183 (1986) G. Yu, J .; Gao, J .; C. Humelen, F.M. Wudl and A.W. J. et al. Heeger: Science, 270, 1789 (1996). B. O'Regan and M.M. Gratzel: Nature, 353, 737 (1991) U. Bach, D.D. Lupo, P.M. Comte, J.A. E. Moser, F.A. Weissortel, J. et al. Salbeck, H.M. Spreitzer and M.M. Gratzel, Nature, 395, 583 (1998) G. R. A. Kumara, S .; Kaneko, M .; kuya, A .; Konno and K.K. Tennakone: Key Engineering Materials, 119, 228 (2002) J. et al. Xia, N.A. Masaki, M .; Lira-Cantu, Y.M. Kim, K.K. Jiang and S.J. Yanagida: Journal of the American Chemical Society, 130, 1258 (2008)

  However, a photoelectric conversion element using a solid hole transport layer has a problem that a short circuit current is small. Even when organic dyes such as those described in Patent Document 2 and Patent Document 3 are used, there is a problem in that the short-circuit current is small and durability is reduced due to energy loss in the photoelectric conversion process. It was.

  The present invention has been made in view of the above problems, and an object thereof is to provide an all-solid-state dye-sensitized photoelectric conversion element and a solar cell that are excellent in photoelectric conversion efficiency and stability (durability) of a photoelectric conversion function. And

  As a result of intensive studies to improve the above problems, the present inventors have found that the above problems can be solved by combining a novel organic dye having a specific structure with a PEDOT substituent having a specific structure. The headline and the present invention were completed.

That is, the above object of the present invention is a photoelectric conversion element having a first electrode, a photoelectric conversion layer containing a semiconductor and a sensitizing dye, a solid hole transport layer, and a second electrode on a substrate.
The sensitizing dye is represented by the following general formula (1A) or general formula (1B):

In the general formula (1A),
Ar ₁ is a monovalent aromatic group having a heteroaromatic ring-containing group as a substituent, and a carbon atom adjacent to the heteroatom in the heteroaromatic ring is bonded to a non-hydrogen atom;
Ar ₂ and Ar ₃ are each independently a divalent aromatic group;
At this time, at least two of Ar _{1 to} Ar ₃ may be bonded to each other to form a ring structure;
Z ₂ and Z ₃ are an organic group having an acidic group or an acidic ring structure, and an electron-withdrawing group or an electron-withdrawing ring structure;
In the general formula (1B),
Ar ₄ and Ar ₅ are each independently a substituted or unsubstituted monovalent aromatic group, and at this time, at least one of Ar ₄ and Ar _{5 has} a heteroaromatic ring-containing group as a substituent A monovalent aromatic group, the carbon atom adjacent to the heteroatom in the heteroaromatic ring is bonded to a non-hydrogen atom;
Ar ₆ is a divalent aromatic group;
At this time, at least two of Ar _{4 to} Ar ₆ may be bonded to each other to form a ring structure;
Z ₆ is an organic group having an acidic group or an acidic ring structure, and an electron-withdrawing group or electron-withdrawing ring structure;
The solid hole transport layer is represented by the following general formula (2):

In the general formula (2),
X ₁ and X ₂ are each independently a hydrogen atom, an optionally substituted linear or branched alkyl group having 1 to 24 carbon atoms, or an optionally substituted carbon number. A linear or branched alkenyl group having 2 to 24, an aryl group having 6 to 24 carbon atoms which may have a substituent, -OR ₁ , -SR ₂ , -SeR ₃ , or -TeR ₄ ; R _{1 to} R ₄ are each independently a hydrogen atom or a linear or branched alkyl group having 1 to 24 carbon atoms which may have a substituent, wherein X ₁ and X ₂ are , May combine with each other to form a ring structure,
In X ₁ , X ₂ , and R _{1 to} R ₄ , the substituent is a halogen atom, a substituted or unsubstituted linear or branched alkyl group having 1 to 24 carbon atoms, and a straight chain having 2 to 24 carbon atoms. Chain or branched alkenyl group, C1-C18 hydroxyalkyl group, C1-C18 alkoxy group, C1-C24 acyl group, C6-C24 aryl group, C2-C24 Selected from the group consisting of:
It achieves by the photoelectric conversion element containing the polymer formed by superposing | polymerizing the compound represented by these, or the multimer of the said compound.

  According to the present invention, a photoelectric conversion element and a solar cell excellent in photoelectric conversion efficiency and stability of a photoelectric conversion function can be provided.

It is a schematic cross section which shows an example of the photoelectric conversion element of this invention.

  The present invention provides a photoelectric conversion element having a first electrode, a photoelectric conversion layer containing a semiconductor and a sensitizing dye, a solid hole transport layer, and a second electrode on a substrate. The solid hole transport layer represented by the formula (1A) or the general formula (1B) contains a compound formed by polymerizing the compound represented by the general formula (2) or a multimer of the compound. A photoelectric conversion element is provided. That is, the present invention is characterized by using a novel dye having the above specific structure as a sensitizing dye and using a polymer having a specific repeating unit in the solid hole transport layer.

  The photoelectric conversion element using the conventional solid hole transport layer has a problem that the short-circuit current is small as compared with the case where the electrolytic solution containing iodine is used. In these devices, the quantum yield at each wavelength is lower than that in the case of the electrolyte solution, and it is considered that there is a problem in charge transfer at the interface between the dye and the hole transport layer or inside the hole transport layer. . Considering that a PEDOT substitution product having high electrical conductivity is used for the hole transport layer, it is presumed that there is a problem in contact at the interface between the dye and the hole transport layer. If the contact between the dye and the hole transport layer is insufficient, the photoelectric conversion process will cause reverse electron transfer due to the interaction of the semiconductor such as titanium oxide with the dye in the photoelectric conversion process. I think that.

The inventors of the present application introduced a heterocyclic structure on the side of the sensitizing dye in contact with the hole transport layer, that is, on the side opposite to the adsorption group (acidic group) of the sensitizing dye, and this is converted to PEDOT having a specific structure. Combined with a solid hole transport layer containing a polymer having a substitution product as a repeating unit, the interfacial contact between the dye and the hole transport layer is improved, leading to an improvement in quantum yield and an increase in photocurrent. I found. Specifically, a compound represented by the general formula (1A) or the general formula (1B) is used as the dye. In these compounds, Ar ₁ , Ar ₄ , Ar ₅ on the side opposite to the adsorption group (Z ₂ , Z ₃ , Z ₆ ) has a heteroaromatic ring structure as a substituent. By introducing such a heteroaromatic ring structure, a portion having a high π electron density is present in a planar form in the sensitizing dye, so that the π electron of the PEDOT oligomer skeleton having a high flatness as a solid hole transport material. As the contact with the cloud is improved and the charge transfer between the dye and the hole transport layer occurs with high probability, the quantum yield and the short-circuit current increase. In addition, by improving the interfacial contact between the dye and the hole transport layer, the charge transfer speed between molecules increases, and the time that exists as an unstable intermediate accompanying photoexcitation is shortened, thereby suppressing reverse electron transfer. As a result, the durability of the photoelectric conversion element can be improved. Therefore, according to the present invention, there are provided a photoelectric conversion element and a solar cell that are superior in photoelectric conversion efficiency and stability (durability) of a photoelectric conversion function as compared with a conventional photoelectric conversion element using a solid hole transport layer. it can.

  Hereinafter, the present invention will be described in detail.

(Photoelectric conversion element)
The photoelectric conversion element of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view schematically showing a photoelectric conversion element according to an embodiment of the present invention. As shown in FIG. 1, the photoelectric conversion element 10 has a configuration in which a substrate 1, a first electrode 2, a barrier layer 3, a photoelectric conversion layer 6, a hole transport layer 7, and a second electrode 8 are sequentially stacked. . Here, the photoelectric conversion layer 6 contains the semiconductor 5 and the sensitizing dye 4. As shown in FIG. 1, it is preferable to have a barrier layer 3 between the first electrode 2 and the photoelectric conversion layer 6 for the purpose of preventing short circuit and sealing. In FIG. 1, sunlight enters from the direction of the arrow 9 at the bottom of the figure, but the present invention is not limited to this form, and sunlight may enter from the top of the figure.

  Next, a preferred embodiment of the method for producing a photoelectric conversion element of the present invention will be described. First, after forming the barrier layer 3 on the substrate 1 on which the first electrode 2 is formed, a semiconductor layer made of the semiconductor 5 is formed on the barrier layer 3, and the sensitizing dye 4 is adsorbed on the semiconductor surface. The photoelectric conversion layer 6 is formed. Thereafter, the solid hole transport layer 7 is formed on the photoelectric conversion layer 6. At this time, the solid hole transport layer 7 penetrates into and exists on the photoelectric conversion layer 6 composed of the semiconductor 5 carrying the sensitizing dye 4. Then, the second electrode 8 is formed on the solid hole transport layer 7. Terminals can be attached to the first electrode 2 and the second electrode 8 to extract current.

  Hereinafter, each member of the photoelectric conversion element of the present invention will be described.

(substrate)
The substrate is provided on the light incident direction side, and from the viewpoint of photoelectric conversion efficiency of the photoelectric conversion element, the light transmittance is preferably 10% or more, more preferably 50% or more, and particularly 80% to 100%. % Is preferred.

  The light transmittance is in the visible light wavelength range measured by a method in accordance with “Testing method of total light transmittance of plastic-transparent material” of JIS K 7361-1: 1997 (corresponding to ISO 13468-1: 1996). The total light transmittance.

  The material, shape, structure, thickness, hardness and the like of the substrate can be appropriately selected from known ones, but preferably have high light transmittance as described above.

  Examples of the substrate include polyester resin films such as polyethylene terephthalate (PET), polyethylene naphthalate, and modified polyester, polyolefins such as polyethylene (PE) resin film, polypropylene (PP) resin film, polystyrene resin film, and cyclic olefin resin. Resin films, vinyl resin films such as polyvinyl chloride and polyvinylidene chloride, polyvinyl acetal resin films such as polyvinyl butyral (PVB), polyether ether ketone (PEEK) resin films, polysulfone (PSF) resin films, polyether sal Hong (PES) resin film, polycarbonate (PC) resin film, polyamide resin film, polyimide resin film, acrylic resin film, triacetyl cellulose Loin (TAC) resin film, and the like. Among these, a resin film having a transmittance of 80% or more at a visible wavelength (400 to 700 nm) can be particularly preferably applied. More preferably, from the viewpoint of transparency, heat resistance, ease of handling, strength and cost, a biaxially stretched polyethylene terephthalate film, a biaxially stretched polyethylene naphthalate film, a polyethersulfone film, and a polycarbonate film are biaxially stretched. More preferably, it is a polyethylene terephthalate film or a biaxially stretched polyethylene naphthalate film. In addition to these resin films, an inorganic glass film may be used as the substrate.

  These substrates can be subjected to a surface treatment or an easy-adhesion layer in order to ensure wettability and adhesion of the coating solution.

  A conventionally well-known technique can be used about a surface treatment or an easily bonding layer. For example, the surface treatment includes surface activation treatment such as corona discharge treatment, flame treatment, ultraviolet treatment, high frequency treatment, glow discharge treatment, active plasma treatment, and laser treatment.

  Examples of the easy adhesion layer include polyester, polyamide, polyurethane, vinyl copolymer, butadiene copolymer, acrylic copolymer, vinylidene copolymer, and epoxy copolymer.

  The thickness of the substrate is preferably 0.1 to 100 mm, and more preferably 0.5 to 10 mm.

(First electrode)
The first electrode is disposed between the substrate and the photoelectric conversion layer. Here, the first electrode is provided on one surface which is opposite to the light incident direction of the substrate. As the first electrode, those having a light transmittance of 80% or more, more preferably 90% or more (upper limit: 100%) are preferably used. The light transmittance is the same as that described in the description of the substrate.

The material for forming the first electrode is not particularly limited, and a known material can be used. For example, metals such as platinum, gold, silver, copper, aluminum, rhodium, indium; and SnO ₂ , CdO, ZnO, CTO (CdSnO ₃ , Cd ₂ SnO ₄ , CdSnO ₄ ), In ₂ O ₃ , CdIn ₂ of O ₄ or the like, and these metal oxides and the like. Among these, silver is preferably used as the metal, and a grid-patterned film having openings or a film in which fine particles or nanowires are dispersed and applied is preferably used in order to impart light transmittance. The metal oxide is preferably a composite (dope) material in which one or more selected from Sn, Sb, F and Al are added to the above metal oxide. More preferably, conductive metal oxides such as In ₂ O ₃ (ITO) doped with Sn, SnO ₂ doped with Sb, and SnO ₂ (FTO) doped with F are preferably used. Is most preferred. The amount of the material forming the first electrode applied to the substrate is not particularly limited, but is preferably about 1 to 100 g per 1 m ^{2 of} the substrate.

  In the present specification, the one having the first electrode on the substrate is also referred to as “conductive support”.

  Although it does not restrict | limit especially as a film thickness of an electroconductive support body, The range of 0.1 mm-5 mm is preferable. The surface resistance of the conductive support is preferably 500Ω / □ (Ω / square) or less, and more preferably 10Ω / □ or less. The lower limit of the surface resistance of the conductive support is preferably as low as possible and need not be specified, but it is sufficient if it is 0.01Ω / □ or more. The preferable range of the light transmittance of the conductive support is the same as the preferable range of the light transmittance of the substrate.

(Barrier layer)
The photoelectric conversion element of the present invention is provided with a barrier layer as necessary from the viewpoint of preventing a short circuit that is a recombination between the holes generated by light reception and injected into the hole transport layer and the electrons of the first electrode. Further, it may be included. The barrier layer can be disposed in a film shape (layer shape) between the first electrode and a photoelectric conversion layer described later.

The constituent material of the barrier layer is not particularly limited. For example, zinc, niobium, tin, titanium, vanadium, indium, tungsten, tantalum, zirconium, molybdenum, manganese, iron, copper, nickel, iridium, rhodium, chromium, ruthenium. Or oxides thereof; perovskites such as strontium titanate, calcium titanate, barium titanate, magnesium titanate, strontium niobate, or complex oxides or oxide mixtures thereof; CdS, CdSe, TiC, Si ₃ N ₄ , One or a combination of two or more of various metal compounds such as SiC and BN.

  In particular, when the solid hole transport layer is a p-type semiconductor, when a metal is used for the barrier layer, it is preferable to use a material having a work function smaller than that of the solid hole transport layer and having a Schottky contact. . In the case where a metal oxide is used for the barrier layer, it is necessary to use one that is in ohmic contact with the transparent conductive layer and whose conduction band energy level is lower than that of the semiconductor layer (photoelectric conversion layer). preferable. At this time, the efficiency of electron transfer from the semiconductor layer (photoelectric conversion layer) to the barrier layer can be improved by selecting an oxide. Among these, those having electrical conductivity equivalent to that of the semiconductor layer (photoelectric conversion layer) are preferable, and those mainly composed of titanium oxide are more preferable.

  The barrier layer and the photoelectric conversion layer are preferably porous. In this case, the porosity of the barrier layer is preferably smaller than the porosity of the semiconductor layer (photoelectric conversion layer). Specifically, when the porosity of the barrier layer is C [%] and the porosity of the semiconductor layer is D [%], D / C is preferably about 1.1 or more, for example. More preferably, it is about 5 or more, more preferably about 10 or more. Here, since it is preferable that the upper limit of D / C is as large as possible, it is not necessary to specify in particular, but it is usually about 1000 or less. Thereby, a barrier layer and a semiconductor layer can exhibit those functions more suitably, respectively.

  More specifically, the porosity C of the barrier layer is, for example, preferably about 20% or less, more preferably about 5% or less, and further preferably about 2% or less. That is, the barrier layer is preferably a dense layer. Thereby, the said effect can be improved more. Here, since the lower limit of the porosity C of the barrier layer is preferably as small as possible, it does not need to be specified in particular.

  The average thickness (film thickness) of the barrier layer is, for example, preferably about 0.01 to 10 μm, and more preferably about 0.03 to 0.5 μm. Thereby, the short circuit prevention effect can be further improved.

(Photoelectric conversion layer)
The photoelectric conversion layer has a function of converting light energy into electric energy using the photovoltaic effect. In the present invention, the photoelectric conversion layer essentially contains a semiconductor and a sensitizing dye. More specifically, the photoelectric conversion layer is composed of a semiconductor layer containing a semiconductor carrying a sensitizing dye.

(Sensitizing dye)
The sensitizing dye has a function of generating an electromotive force by being photoexcited during light irradiation. The sensitizing dye is supported on the semiconductor by a semiconductor sensitizing process as described later. In this invention, the compound represented by the following general formula (1A) or general formula (1B) is included as a sensitizing dye.

In the general formula (1A), Ar ₁ represents a monovalent aromatic group having a heteroaromatic ring-containing group as a substituent. The carbon atom adjacent to the hetero atom in the heteroaromatic ring is bonded to a non-hydrogen atom. In the general formula (1A), Ar ₂ and Ar ₃ represent a divalent aromatic group. Ar ₂ and Ar ₃ may be the same or different. Note that at least two of Ar _{1 to} Ar ₃ may be bonded to each other to form a ring structure. In the general formula (1A), Z ₂ and Z ₃ represent an organic residue having an acidic group or an acidic ring structure, and an electron-withdrawing group or an electron-withdrawing ring structure.

In the general formula (1B), Ar ₄ and Ar ₅ represent a substituted or unsubstituted monovalent aromatic group. At this time, at least one of Ar ₄ and Ar ₅ is a monovalent aromatic group having a heteroaromatic ring-containing group as a substituent, and a carbon atom adjacent to the heteroatom in the heteroaromatic ring is bonded to a non-hydrogen atom. doing. Ar ₄ and Ar ₅ may be the same or different. In the general formula (1B), Ar ₆ represents a divalent aromatic group. Note that at least two of Ar _{4 to} Ar ₆ may be bonded to each other to form a ring structure. In the general formula (1B), Z ₆ represents an acidic group or an organic residue having an acidic ring structure and an electron-withdrawing group or electron-withdrawing ring structure.

Here, the monovalent aromatic group as Ar ₁ , Ar ₄ , and Ar ₅ and the divalent aromatic group as Ar ₂ , Ar ₃ , and Ar ₆ are not particularly limited. Specifically, benzene, styrene, naphthalene, anthracene, phenanthrene, pyrrole, furan, pyran, thiophene, pyridine, pyrazine, pyrimidine, pyridazine, triazine, imidazole, imidazolone, pyrazole, pyrazolone, pyrazoline, oxazole, isoxazole, thiazole, benzofuran , Isobenzofuran, benzothiophene, benzimidazole, benzoxazole, benzisoxazole, benzothiazole, indole, isoindole, fluorene, phthalazine, quinazoline, carbazole, carboline, diazacarboline (any carbon atom of carboline is nitrogen Substituted by atoms), coumarin, rhodanine, dithieno [3,2-b: 2 ′, 3′-d] thiophene (shown by the following chemical formula 4-1) Compound), 4H-cyclopenta [2,1-b: 3,4-b ′] dithiophene (compound represented by the following chemical formula 4-2), 4,5,6,7-tetrahydro-2-benzothiophene, etc. It is derived from the aromatic ring compound.

  A plurality of these aromatic ring compounds may be used in combination. In this case, a plurality of aromatic rings may be directly bonded or may be bonded via a divalent linear substituent (for example, an alkylene group, vinylene group, arylene group, alkenylene group, etc.). For example, biphenyl, terphenyl, phenylthiophene, diphenylthiophene, diphenylstyrene, bithiophene, phenylbithiophene, phenylterthiophene, phenyldithienothiophene, stilbene, 4-phenylmethylene-2,5-cyclohexadiene, triphenylethene (e.g. 1,1,2-triphenylethene), phenylpyridine (eg, 4-phenylpyridine), styrylthiophene (eg, 2-styrylthiophene), 2- (9H-fluoren-2-yl) thiophene, 2-phenyl Benzo [b] thiophene, (1,1-diphenyl-4-phenyl) -1,3-butadiene, 1,4-diphenyl-1,3-dibutadiene, 4- (phenylmethylene) -2,5-cyclohexadiene There are groups derived from it.

  These aromatic ring compounds may have a substituent. Examples of the substituent in this case include a halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom), each substituted or unsubstituted linear or branched alkyl group having 1 to 24 carbon atoms (for example, , Methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, tert-pentyl group, neopentyl group, 1 , 2-dimethylpropyl group, n-hexyl group, isohexyl group, 1,3-dimethylbutyl group, 1-isopropylpropyl group, 1,2-dimethylbutyl group, n-heptyl group, 1,4-dimethylpentyl group, 3-ethylpentyl group, 2-methyl-1-isopropylpropyl group, 1-ethyl-3-methylbutyl group, n-octyl group, 2-ethyl Ruhexyl group, 3-methyl-1-isopropylbutyl group, 2-methyl-1-isopropyl group, 1-t-butyl-2-methylpropyl group, n-nonyl group, 3,5,5-trimethylhexyl group, n -Decyl group, isodecyl group, n-undecyl group, 1-methyldecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group Group, n-nonadecyl group, n-eicosyl group, n-heneicosyl group, n-docosyl group, n-tricosyl group, n-tetracosyl group, etc.), linear or branched alkenyl group having 2 to 24 carbon atoms (for example, , Vinyl group, 1-propenyl group, 2-propenyl group, isopropenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 1-pen Nyl group, 2-pentenyl group, 3-pentenyl group, 1-hexenyl group, 2-hexenyl group, 3-hexenyl group, 1-heptenyl group, 2-heptenyl group, 5-heptenyl group, 1-octenyl group, 3- Octenyl group, 5-octenyl group, etc.), C1-C18 hydroxyalkyl group (for example, hydroxymethyl group, hydroxyethyl group), C1-C18 alkoxy group (for example, methoxy group, ethoxy group, propoxy) Group, isopropoxy group, butoxy group, pentyloxy group, hexyloxy group, 2-ethylhexyloxy group, octyloxy group, nonyloxy group, decyloxy group, undecyloxy group, dodecyloxy group, tridecyloxy group, tetradecyloxy group Group, pentadecyloxy group, hexadecyloxy group, heptadecyloxy group , Octadecyloxy group, etc.), C1-C24 acyl group (for example, formyl group, acetyl group, propionyl group, butyryl group, isobutyryl group, valeryl group, isovaleryl group, 2-methylvaleryl group, 3-methylvaleryl group, 4 -Methylvaleryl group, t-butylacetyl group, pivaloyl group, caproyl group, 2-ethylhexanoyl group, 2-methylhexanoyl group, heptanoyl group, octanoyl group, benzoyl group, etc.), aryl group having 6 to 24 carbon atoms ( For example, phenyl group, naphthyl group, biphenyl group, fluorenyl group, anthryl group, pyrenyl group, azulenyl group, acenaphthylenyl group, terphenyl group, phenanthryl group, etc.), amino group (for example, dimethylamino group, diethylamino group, diphenylamino group) Etc.). In the above, the same substituent is not substituted. That is, a substituted alkyl group is not substituted with an alkyl group.

At least one of Ar ₁ in the general formula (1A) and Ar ₄ and Ar _{5 in} the general formula (1B) has a heteroaromatic ring-containing group as a substituent. That is, at least one hydrogen atom in the aromatic ring compound of Ar ₁ , Ar ₄ , Ar ₅ is substituted with a heteroaromatic ring-containing group. “Heteroaromatic ring-containing group” refers to a monovalent aromatic group containing at least one heteroaromatic ring, and “heteroaromatic ring” refers to an aromatic ring containing at least one heteroatom. The heteroaromatic ring-containing group as such a substituent is not particularly limited. For example, thiophene, pyrrole, furan, pyran, pyridine, pyrazine, pyrimidine, pyridazine, triazine, imidazole, imidazolone, pyrazole, pyrazolone, pyrazoline, oxazole, isoxazole, thiazole, benzofuran, isobenzofuran, benzothiophene, benzimidazole, benzoxazole, Benzisoxazole, benzothiazole, indole, isoindole, phthalazine, quinazoline, carbazole, carboline, diazacarboline, coumarin, rhodanine, dithieno [3,2-b: 2 ′, 3′-d] thiophene, 4H-cyclopenta It is derived from a heteroaromatic ring such as [2,1-b: 3,4-b ′] dithiophene.

  A heteroaromatic ring-containing group may be used in combination of a plurality of these heteroaromatic rings. In this case, a plurality of heteroaromatic rings may be directly bonded, or a divalent aromatic hydrocarbon group such as a phenylene group or biphenylene, or a divalent group such as an alkylene group, a vinylene group, an arylene group, or an alkenylene group. You may couple | bond together through a coupling group. Preferably, from the viewpoint of improving molecular contact with the hole transport material, a group containing an aromatic ring containing a sulfur atom as a heteroatom, more preferably a group containing a thiophene ring as a heteroaromatic ring (thiophene) Ring-containing group).

The hydrogen atom in the heteroaromatic ring and the linking group is, for example, a halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom), each substituted or unsubstituted, straight or branched chain having 1 to 24 carbon atoms Alkyl group (for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, tert-pentyl group, Neopentyl group, 1,2-dimethylpropyl group, n-hexyl group, isohexyl group, 1,3-dimethylbutyl group, 1-isopropylpropyl group, 1,2-dimethylbutyl group, n-heptyl group, 1,4- Dimethylpentyl group, 3-ethylpentyl group, 2-methyl-1-isopropylpropyl group, 1-ethyl-3-methylbutyl group, n-o Tyl group, 2-ethylhexyl group, 3-methyl-1-isopropylbutyl group, 2-methyl-1-isopropyl group, 1-t-butyl-2-methylpropyl group, n-nonyl group, 3,5,5- Trimethylhexyl, n-decyl, isodecyl, n-undecyl, 1-methyldecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl Group, n-octadecyl group, n-nonadecyl group, n-eicosyl group, n-heneicosyl group, n-docosyl group, n-tricosyl group, n-tetracosyl group, etc.), alkenyl group having 2 to 24 carbon atoms (for example, Vinyl group, 1-propenyl group, 2-propenyl group, isopropenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 1-pentenyl Group, 2-pentenyl group, 3-pentenyl group, 1-hexenyl group, 2-hexenyl group, 3-hexenyl group, 1-heptenyl group, 2-heptenyl group, 5-heptenyl group, 1-octenyl group, 3-octenyl group Group, 5-octenyl group, etc.), C1-C18 hydroxyalkyl group (e.g., hydroxymethyl group, hydroxyethyl group, etc.), C1-C18 alkoxy group (e.g., methoxy group, ethoxy group, ethoxy) Group, propoxy group, isopropoxy group, butoxy group, pentyloxy group, hexyloxy group, 2-ethylhexyloxy group, octyloxy group, etc.),
C1-C24 acyl group (for example, formyl group, acetyl group, propionyl group, butyryl group, isobutyryl group, valeryl group, isovaleryl group, 2-methylvaleryl group, 3-methylvaleryl group, 4-methylvaleryl group, t-butyl Acetyl group, pivaloyl group, caproyl group, 2-ethylhexanoyl group, 2-methylhexanoyl group, heptanoyl group, octanoyl group, benzoyl group, etc.), aryl group having 6 to 24 carbon atoms (for example, phenyl group, naphthyl group) , Biphenyl group, fluorenyl group, anthryl group, pyrenyl group, azulenyl group, acenaphthylenyl group, terphenyl group, phenanthryl group, etc.), amino group (for example, dimethylamino group, diethylamino group, diphenylamino group, etc.), -SR ₁₁ , -SeR _12, -TeR ₁₃ (However, ₁₁ to R ₁₃ each independently have a hydrogen atom or a substituent a straight-chain or branched alkyl group which may 1 to 24 carbon atoms) may be substituted by like. In the above, the same substituent is not substituted. That is, a substituted alkyl group is not substituted with an alkyl group. Further, when two or more hydrogen atoms of the heteroaromatic ring and the linking group are substituted, these may be bonded to each other to form a ring structure.

  In the present invention, the carbon atom (α-position carbon) adjacent to the heteroatom in the heteroaromatic ring in the heteroaromatic ring-containing group is bonded to a non-hydrogen atom. Here, when there is one heteroatom in the heteroaromatic ring, the carbon atom adjacent to the heteroatom (α-position carbon) refers to the carbon atom adjacent to the heteroatom, and the heteroatom in the heteroaromatic ring is 2 When there are two or more and a sulfur atom is included, it refers only to the carbon atom on both sides of the sulfur atom, and when there are two or more heteroatoms in the heteroaromatic ring and does not contain a sulfur atom Refers to the carbon atoms on either side of all heteroatoms in a heteroaromatic ring.

  Specifically, when there is one heteroatom in the heteroaromatic ring, the carbon atoms on both sides of the heteroatom are bonded to a non-hydrogen atom. Examples of the heteroaromatic ring containing one heteroatom include the following. In the following structure, Y is a monovalent or divalent group other than a hydrogen atom, and the carbon atom bonded to Y is the α-position carbon.

  When there are two or more heteroatoms in the heteroaromatic ring and a sulfur atom is contained, both carbon atoms adjacent to the sulfur atom are bonded to a non-hydrogen atom, and adjacent to a heteroatom other than the sulfur atom. The carbon atom of may be bonded to a hydrogen atom. Of course, the carbon atom adjacent to the heteroatom other than the sulfur atom may be bonded to a non-hydrogen atom. For example, examples of the heteroaromatic ring containing two or more heteroatoms and at least one of the heteroatoms is a sulfur atom include the following. In the following structure, Y is a monovalent or divalent group other than a hydrogen atom, and the carbon atom bonded to Y is the α-position carbon.

  When there are two or more heteroatoms in the heteroaromatic ring and no sulfur atom is contained, all the carbon atoms adjacent to the heteroatoms in each heteroaromatic ring are bonded to non-hydrogen atoms. Yes. For example, examples of the heteroaromatic ring containing two or more heteroatoms and none of which are sulfur atoms include the following. In the following structure, Y is a monovalent or divalent group other than a hydrogen atom, and the carbon atom bonded to Y is the α-position carbon.

  When a plurality of α-position carbons are present in the heteroaromatic ring, the plurality of Y may be the same or different.

Since the hydrogen atom at the α-position of the heteroaromatic ring has a high charge density and is highly reactive, when the α-position carbon in the heteroaromatic ring is bonded to the hydrogen atom, electrolytic polymerization of the hole transport layer described later In this case, the hydrogen atom becomes the polymerization starting point, and the sensitizing dye reacts with the monomer (hole transport material) of the hole transport layer to form a σ bond between them, thereby transporting the hole. There is a possibility that the π-conjugated system of the layers may be directly connected by the σ bond. In such a case, charge transfer in the reverse direction, that is, electron transfer from the sensitizing dye to the hole transport layer is likely to occur, resulting in a decrease in durability. In the present invention, by having a structure in which all α-position carbons in the heteroaromatic ring are bonded to non-hydrogen atoms, the reaction between the sensitizing dye and the hole transporting material can be prevented, thereby improving the durability of the photoelectric conversion element. Can be improved. In the case of having a plurality of heteroatoms that do not contain sulfur atoms, the α hydrogens of all these heteroatoms maintain the reactivity, so it is necessary to replace all the α hydrogens with substituents and block the reaction. is there. On the other hand, if the heterocycle contains a sulfur atom and there are multiple heteroatoms, the reactivity of α-hydrogen of other heteroatoms other than sulfur is greatly reduced due to the influence of sulfur. Since the reaction hardly occurs, the reaction can be suppressed by substituting only α hydrogen of sulfur.
Preferably, at least one of Ar ₁ in the general formula (1A) and Ar ₄ and Ar _{5 in} the general formula (1B) has a structure represented by the following general formula (3).

In the general formula (3), Ar ₇ is a divalent aromatic group, Ar ₈ is a divalent heteroaromatic ring-containing group, Y ₈ is a monovalent group other than a hydrogen atom, and m is It is an integer of 1-10.

  The PEDOT substitution product as the hole transport material represented by the general formula (2) has a planar structure in which thiophene groups (3,4-ethylenedioxythiophene group and the like) are linearly arranged. A π electron cloud spreads parallel to the. The charge transfer between the dye molecule and the hole transport layer is mainly performed through the contact portion of the π electron cloud, and the heteroaromatic compound is formed at the end of the sensitizing dye as shown in the general formula (3). When the ring has a structure in which one or more rings are arranged in a straight line, the contact between the heteroaromatic ring and the π-electron cloud of the hole transport layer (the face-to-face between the heteroaromatic ring and the hole transport material) (π-π interaction) is improved. Thereby, photoelectric conversion efficiency and durability can be further improved.

The divalent aromatic group as Ar ₇ is not particularly limited, and examples thereof include the same divalent aromatic groups as Ar ₂ , Ar ₃ , and Ar ₆ described above. Among these, a divalent aromatic hydrocarbon group is preferable. Specifically, a phenylene group, a phenyl vinyl group (a divalent group derived from styrene), a fluorenylene group, a biphenylene group, a naphthanylene group, an anthracenylene group, and the like are preferable. These aromatic hydrocarbon groups may have a substituent, and the substituent is the same as the substituent exemplified for the aromatic ring compound.

Examples of the heteroaromatic ring of the divalent heteroaromatic ring-containing group as Ar ₈ include thiophene, pyrrole, furan, pyran, pyridine, pyrazine, pyrimidine, pyridazine, triazine, imidazole, imidazolone, pyrazole, pyrazolone, pyrazoline oxazole. , Isoxazole, thiazole, benzofuran, isobenzofuran, benzothiophene, benzimidazole, benzoxazole, benzisoxazole, benzothiazole, indole, phthalazine, quinazoline, carbazole, carboline, diazacarboline, coumarin, rhodanine, dithieno [3,2 -B: 2 ', 3'-d] thiophene, 4H-cyclopenta [2,1-b: 3,4-b'] dithiophene and the like. In particular, the π electron cloud of the heteroaromatic ring (Ar ₈ ) structure portion of the dye and the π electron cloud of the PEDOT substitution material as the hole transport material have the same type of wave function contrast. Since it is preferable in terms of increase, a thiophene ring-containing group is preferable. In a preferred embodiment, Ar ₈ has the following structure:

In the above, X ₃ and X ₄ are each a hydrogen atom, a linear or branched alkyl group having 1 to 24 carbon atoms, a linear or branched alkenyl group having 2 to 24 carbon atoms, or an aryl having 6 to 24 carbon atoms. Represents a group, —OR ₅ , —SR ₆ , —SeR ₇ , or —TeR ₈ . X ₃ and X ₄ may be the same or different. R _{5 to} R ₈ each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 24 carbon atoms. Here, X ₃ and X ₄ may be bonded to each other to form a ring structure.

The linear or branched alkyl group having 1 to 24 carbon atoms as X ₃ , X ₄ and R _{5 to} R ₈ is not particularly limited, and examples thereof include a methyl group, an ethyl group, an n-propyl group, and an isopropyl group. , N-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, tert-pentyl group, neopentyl group, 1,2-dimethylpropyl group, n-hexyl group, isohexyl group 1,3-dimethylbutyl group, 1-isopropylpropyl group, 1,2-dimethylbutyl group, n-heptyl group, 1,4-dimethylpentyl group, 3-ethylpentyl group, 2-methyl-1-isopropylpropyl Group, 1-ethyl-3-methylbutyl group, n-octyl group, 2-ethylhexyl group, 3-methyl-1-isopropylbutyl group, 2-methyl -1-isopropyl group, 1-t-butyl-2-methylpropyl group, n-nonyl group, 3,5,5-trimethylhexyl group, n-decyl group, isodecyl group, n-undecyl group, 1-methyldecyl group N-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group, n-eicosyl group, n-heneicosyl group , N-docosyl group, n-tricosyl group, n-tetracosyl group and the like.

The linear or branched alkenyl group having 2 to 24 carbon atoms as X ₃ and X ₄ is not particularly limited, and examples thereof include a vinyl group, a 1-propenyl group, a 2-propenyl group (allyl group), and an isopropenyl group. 1-butenyl group, 2-butenyl group, 3-butenyl group, 1-pentenyl group, 2-pentenyl group, 3-pentenyl group, 1-hexenyl group, 2-hexenyl group, 3-hexenyl group, 1-heptenyl group 2-heptenyl group, 5-heptenyl group, 1-octenyl group, 3-octenyl group, 5-octenyl group and the like.

The aryl group having 6 to 24 carbon atoms as X ₃ and X ₄ is not particularly limited. For example, phenyl group, naphthyl group, biphenyl group, fluorenyl group, anthryl group, pyrenyl group, azulenyl group, acenaphthylenyl group, terphenyl Group, phenanthryl group and the like. Among these, a phenyl group, a biphenyl group, and a fluorenyl group are mentioned.

In X ₃ , X ₄ and R _{5 to} R ₈ , "a linear or branched alkyl group having 1 to 24 carbon atoms", "an alkenyl group having 2 to 24 carbon atoms", "an aryl group having 6 to 24 carbon atoms" At least one of the hydrogen atoms in "may be substituted with a substituent. These specific groups are the same as those exemplified as the substituent for the heteroaromatic ring and the linking group.

Preferred examples of the divalent heteroaromatic ring-containing group as Ar ₈ represented above are given below.

  Among these, a divalent group derived from 3,4-ethylenedioxythiophene (a group represented by 8-1 above) is particularly preferable. In such a case, in addition to the face-to-face π-π interaction between the dye and the hole transport material, the side-to-side between the heteroaromatic ring in the dye and the hole transport material. Intermolecular contact due to the π-π interaction occurs, and the photoelectric conversion efficiency and durability can be further improved.

In a more preferred embodiment, the divalent heteroaromatic ring-containing group as Ar ₈ is derived from a heteroaromatic ring-containing monomer forming a hole transport layer, and particularly preferably Ar ₈ is 3 , 4-ethylenedioxythiophene-derived divalent group, and the hole transport layer contains a polymer having a repeating unit derived from 3,4-ethylenedioxythiophene.

Said m is an integer of 1-10, Preferably it is an integer of 1-4 from a soluble viewpoint. When m is 2 or more, a plurality of different Ar ₈ may be combined.

Y ₈ is not particularly limited, but may be a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, an iodine atom), a substituted or unsubstituted linear or branched alkyl group having 1 to 24 carbon atoms (for example, , Methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, tert-pentyl group, neopentyl group, 1 , 2-dimethylpropyl group, n-hexyl group, isohexyl group, 1,3-dimethylbutyl group, 1-isopropylpropyl group, 1,2-dimethylbutyl group, n-heptyl group, 1,4-dimethylpentyl group, 3-ethylpentyl group, 2-methyl-1-isopropylpropyl group, 1-ethyl-3-methylbutyl group, n-octyl group, 2 -Ethylhexyl group, 3-methyl-1-isopropylbutyl group, 2-methyl-1-isopropyl group, 1-t-butyl-2-methylpropyl group, n-nonyl group, 3,5,5-trimethylhexyl group, n-decyl group, isodecyl group, n-undecyl group, 1-methyldecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n- Octadecyl group, n-nonadecyl group, n-eicosyl group, n-heneicosyl group, n-docosyl group, n-tricosyl group, n-tetracosyl group, etc.), linear or branched alkenyl group having 2 to 24 carbon atoms ( For example, vinyl group, 1-propenyl group, 2-propenyl group, isopropenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 1- Nthenyl group, 2-pentenyl group, 3-pentenyl group, 1-hexenyl group, 2-hexenyl group, 3-hexenyl group, 1-heptenyl group, 2-heptenyl group, 5-heptenyl group, 1-octenyl group, 3- Octenyl group, 5-octenyl group, etc.), C1-C18 hydroxyalkyl groups (e.g., hydroxymethyl group, hydroxyethyl group, etc.), C1-C18 alkoxy groups (e.g., methoxy group, ethoxy group, propoxy) Group, isopropoxy group, butoxy group, pentyloxy group, hexyloxy group, 2-ethylhexyloxy group, octyloxy group, nonyloxy group, decyloxy group, undecyloxy group, dodecyloxy group, tridecyloxy group, tetradecyloxy group Group, pentadecyloxy group, hexadecyloxy group, heptadecyl group Ci-group, octadecyloxy group, etc.), C1-C24 acyl group (for example, formyl group, acetyl group, propionyl group, butyryl group, isobutyryl group, valeryl group, isovaleryl group, 2-methylvaleryl group, 3-methylvaleryl group) 4-methylvaleryl group, t-butylacetyl group, pivaloyl group, caproyl group, 2-ethylhexanoyl group, 2-methylhexanoyl group, heptanoyl group, octanoyl group, benzoyl group)), aryl having 6 to 24 carbon atoms Groups (eg, phenyl, naphthyl, biphenyl, fluorenyl, anthryl, pyrenyl, azulenyl, acenaphthylenyl, terphenyl, phenanthryl, etc.), amino groups (eg, dimethylamino, diethylamino, diphenyl) Amino group) and the like.

Among them, from the viewpoint of solubility, preferably, a halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom), each substituted or unsubstituted, straight-chain or branched alkyl group having 1 to 18 carbon atoms. More preferably a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, an iodine atom) or a linear or branched alkyl group having 1 to 6 carbon atoms, and particularly preferably a chlorine atom or a fluorine atom. If Y ₈ is a chlorine atom or a fluorine atom, smaller than the van der Waals radius half the π electrons of the thickness of the PEDOT substituents as a hole transporting material of these atoms (1.7 Å). Therefore, the steric hindrance is eliminated when the heteroaromatic ring (Ar ₈ ) structure portion of the dye and the π electron cloud of the PEDOT substitution product as the hole transport material are arranged in parallel. Thereby, the intermolecular contact property by side-to-side π-π interaction between the dye and the hole transport material can be improved, and the photoelectric conversion efficiency and durability can be further improved.

Z ₂ , Z ₃ or Z ₆ is an organic group having an acidic group or an acidic ring structure, and an electron-withdrawing group or an electron-withdrawing ring structure. In the general formula (1A), Z ₂ and Z ₃ may have the same structure or different structures.

Examples of the acidic group in Z ₂ , Z ₃ or Z ₆ include a carboxyl group, a sulfo group (—SO ₃ H), a sulfino group, a sulfinyl group, a phosphonic acid group [—PO (OH) ₂ ], a phosphoryl group, and a phosphinyl group. , Phosphono group, thiol group, hydroxy group, phosphonyl group, and sulfonyl group; and salts thereof. Among these, as the acidic group, a carboxyl group, a sulfo group, a phosphonic acid group, and a hydroxy group are preferable, and a carboxyl group, a sulfo group, and a phosphonic acid group are more preferable. The acidic group moiety may be a metal salt or an organic cation salt.

Examples of the ring structure showing acidity in Z ₂ , Z ₃ or Z ₆ include barbituric acid, uric acid, uracil, thymine and the like.

Examples of the electron withdrawing group in Z ₂ , Z ₃ or Z ₆ include cyano group, nitro group, fluoro group, chloro group, bromo group, iodo group, perfluoroalkyl group (for example, trifluoromethyl group), alkylsulfonyl Group, arylsulfonyl group, perfluoroalkylsulfonyl group, perfluoroarylsulfonyl group and the like. Of these, a cyano group, a nitro group, a chloro group, and a fluoro group are preferable, and a cyano group and a nitro group are more preferable.

Examples of the electron-withdrawing ring structure in Z ₂ , Z ₃ and Z ₆ include rhodanine ring, dirhodanine ring, imidazolone ring, pyrazolone ring, pyrazoline ring, quinone ring, pyran ring, pyrazine ring, pyrimidine ring, imidazole ring, indole ring Benzothiazole ring, benzimidazole ring, benzoxazole ring and the like. Among these, a rhodanine ring, a dirhodanine ring, an imidazolone ring, a pyrazoline ring, a thiadiazole ring, and a quinone ring are preferable, and a rhodanine ring, a dirhodanine ring, an imidazolone ring, and a pyrazoline ring are more preferable.

These Z ₂ , Z ₃ or Z ₆ can effectively inject photoelectrons into a semiconductor (especially an oxide semiconductor).

Z ₂ , Z ₃ or Z ₆ preferably has a cyano group and a carboxyl group. By having a cyano group and a carboxyl group, the adsorptive power is improved and the elimination of the dye can be effectively prevented. That is, in one embodiment of the present invention, Z ₂ or Z ₃ in the general formula (1A) and Z _{6 in the} general formula (1B) have the following structure.

In the above, R ₁₁ represents a hydrogen atom, a halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom), a linear or branched alkyl group having 1 to 24 carbon atoms (for example, a methyl group, an ethyl group, n -Propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, tert-pentyl group, neopentyl group, 1,2-dimethylpropyl group, n -Hexyl group, isohexyl group, 1,3-dimethylbutyl group, 1-isopropylpropyl group, 1,2-dimethylbutyl group, n-heptyl group, 1,4-dimethylpentyl group, 3-ethylpentyl group, 2- Methyl-1-isopropylpropyl group, 1-ethyl-3-methylbutyl group, n-octyl group, 2-ethylhexyl group, 3-methyl- 1-isopropylbutyl group, 2-methyl-1-isopropyl group, 1-t-butyl-2-methylpropyl group, n-nonyl group, 3,5,5-trimethylhexyl group, n-decyl group, isodecyl group, n-undecyl group, 1-methyldecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group, n-eicosyl group, n-heneicosyl group, n-docosyl group, n-tricosyl group, n-tetracosyl group, etc., aryl group having 6 to 24 carbon atoms (for example, phenyl group, naphthyl group, biphenyl group, fluorenyl group, Anthryl group, pyrenyl group, azulenyl group, acenaphthylenyl group, terphenyl group, phenanthryl group, etc.), having 7 to 24 carbon atoms Aralkyl groups (for example, benzyl group, phenylethyl group, phenylpropyl group, naphthylmethyl group, naltylethyl group, etc.), C1-C18 alkoxy groups (for example, methoxy group, ethoxy group, propoxy group, isopropoxy group, butoxy) Group, pentyloxy group, hexyloxy group, 2-ethylhexyloxy group, octyloxy group, nonyloxy group, decyloxy group, undecyloxy group, dodecyloxy group, tridecyloxy group, tetradecyloxy group, pentadecyloxy group, A hexadecyloxy group, a heptadecyloxy group, an octadecyloxy group), or a cyano group. R ₁₁ is preferably a hydrogen atom or a methyl group.

In Z ₂ , Z ₃ or Z ₆ , the acidic group and the electron-withdrawing group or electron-withdrawing ring structure may have an aromatic group or a substituent that may have a substituent. Bonded via a straight or branched hydrocarbon group having 1 to 32 carbon atoms, or an atom such as an oxygen atom (O), a sulfur atom (S), a selenium atom (Se), or a tellurium atom (Te). May be. Alternatively, Z ₂ , Z ₃ and Z ₆ may have a charge, particularly a positive charge, in which case Cl ⁻ , Br ⁻ , I ⁻ , ClO ₄ ⁻ , OH ⁻ , NO ³⁻ , SO ₄ ^{2. -} it may have a counter ion of _H 2 ^{PO 4-like.} The aromatic group which may have a substituent and the linear or branched hydrocarbon group having 1 to 32 carbon atoms which may have a substituent are the same as those described above.

Hereinafter, preferred structures of Z ₂ and Z ₃ in the general formula (1A) and Z _{6 in} (1B) will be exemplified.

  Moreover, the especially preferable example of the sensitizing dye which concerns on this invention is shown below. In the following examples, sensitizing dyes are defined by the following symbols.

  The method for synthesizing the compound represented by the general formula (1A) or (1B) is not particularly limited. Below, preferable embodiment of the manufacturing method of the said compound (D-1) is described, for example. The present invention is not limited to the following preferred embodiments, and other similar methods or other known methods can be applied.

[Synthesis of Compound (D-1)]
(Synthesis of Compound a)

1.129 g (4.00 mmol) of bis-EDOT was dissolved in 40 mL of DMF (dehydrated) under nitrogen. A solution prepared by dissolving 587 mg (4.40 mmol) of NCS in 20 mL of DMF (dehydrated) was added dropwise while keeping the temperature at 10 ° C. or lower in an ice bath. While heating in an oil bath, the temperature of the reaction system was kept at 50 to 60 ° C. and heating was continued for 2 hours. While cooling with ice, 100 mL of water was added dropwise to the reaction system, and the precipitated powder was suction filtered and washed with a small amount of methanol. 1.155 g (crude yield 91%) of white brown powder was obtained, and it was judged from the TLC spot and NMR spectrum that the mixture was monochloro (compound a): dichloro isomer = 6: 1.
¹ H-NMR (CDCl ₃ ): 4.22-4.24 (m, 2H), 4.29-4.33 (m, 6H), 6.27 (s, 1H).

  (Synthesis of Compound b)

1.146 g of the bis-EDOT monochloro isomer / dichloro isomer mixture (3.62 mmol as the monochloro isomer (compound a))) was dissolved in 50 mL of tetrahydrofuran (THF) (with dehydration and stabilizer) under nitrogen. After adding 0.55 mL (7.1 mmol) of DMF (dehydrated) and cooling with ice, a solution obtained by diluting 0.40 mL (4.3 mmol) of phosphoryl chloride in 15 mL of THF (dehydrated) was added dropwise. It heated at 65 degreeC for 1 hour, and after cooling, it added and hydrolyzed sodium acetate aqueous solution (1N). The precipitated solid was filtered by suction and washed with water and ethanol. After vacuum drying, 1.146 g (crude yield 90%) of tan powder (compound b) was obtained.
_{^{1 H-NMR (DMSO-d}} 6): 4.31-4.38 (m, 8H), 9.82 (s, 1H).

  (Synthesis of Compound c)

Under a nitrogen atmosphere, 2.418 g (9.99 mmol) of 3-methyl-4-bromobenzoic acid was suspended in 110 mL of diethyl ether. LiAlH ₄ 1.56 g (41 mmol) was gradually added and stirred at 25 ° C. for 1 hour. The reaction system was ice-cooled and saturated aqueous ammonium chloride solution was added dropwise. Suction filtration was performed with a Kiriyama funnel previously spread with diatomaceous earth, and the precipitate was washed with ethyl acetate, and the filtrate was collected. The organic layer was washed with water, dried over Na ₂ SO ₄ , filtered and concentrated under reduced pressure to obtain a light brown oily substance. By developing a silica gel column using a mixed solvent system of heptane: ethyl acetate (90: 10 → 65: 35), 1.891 g (yield 94%) of the target product (compound c) was obtained as a pale yellow oily substance.
¹ H-NMR (CDCl ₃ ): 1.66 (t, 1H), 2.40 (s, 3H), 4.64 (d, 2H), 7.04 (d 1H), 7.24 (s, 1H), 7.50 (d, 1H).

  (Synthesis of Compound d)

Under a nitrogen atmosphere, 1.89 g (9.41 mmol) of 3-methyl-4-bromobenzyl alcohol (compound c) was dissolved in 55 mL of diethyl ether. A solution prepared by diluting 0.62 mL (6.5 mmol) of PBr _{3 with} 5 mL of diethyl ether was added dropwise, and the mixture was stirred at 25 ° C. for 1 hour. The reaction mixture was poured into 50 mL of ice water, the aqueous layer was extracted twice with diethyl ether, and the organic layer was collected. The organic layer was washed with an aqueous sodium bicarbonate solution followed by an aqueous sodium chloride solution. After drying over Na ₂ SO _{4 and} concentrating under reduced pressure, 2.018 g (yield 81%) of the desired product (compound d) was obtained as a pale yellow oily substance. It used for next step reaction, without refine | purifying.
¹ H-NMR (CDCl ₃ ): 2.39 (s, 3H), 4.41 (s, 2H), 7.07 (d, 1H), 7.26 (s, 1H), 7.49 (d , 1H).

  (Synthesis of Compound e)

Under a nitrogen atmosphere, 2.0 mL (12 mmol) of triethyl phosphite was added dropwise to 2.018 g (7.65 mmol) of the starting bromo compound (compound d). The reaction was stopped when heated at 100 ° C. for 6 hours, and unreacted phosphite was distilled off under reduced pressure (5 mmHg) using a rotary pump while heating in an oil bath at 80 ° C. 2.474 g (crude yield 101%) of the target product (compound e) was obtained as a pale yellow oily substance. It used for next step reaction, without refine | purifying.
¹ H-NMR (CDCl ₃ ): 1.26 (t, 6H), 2.37 (s, 3H), 3.09-3.14 (d, 2H), 4.02 (q, 4H), 6 .98 (d, 1H), 7.17 (s, 1H), 7.45 (d, 1H).

  (Synthesis of Compound f)

Under a nitrogen atmosphere, 524 mg (1.50 mmol) of the starting formyl compound (compound b) was suspended in 20 mL of DMF (dehydrated). A solution of 522 mg (1.62 mmol) of raw material phosphite (compound e) in 20 mL of DMF (dehydrated) was added. The system was cooled in an ice bath and 186 mg (1.66 mmol) of potassium t-butoxy was added. After stirring at 25 ° C. for 1 hour, 50 mL each of water and ethyl acetate were added and stirred, and the organic layer was washed with water. After drying Na ₂ SO ₄ , filtration and concentration under reduced pressure were performed, and 593 mg (yield 77%) of a tan powder (compound f) was obtained by reprecipitation with heptane. The mixture was estimated to be a mixture of trans and cis isomers (trans: cis = 5: 1) from the NMR spectrum, but was used for the next reaction without separation.
¹ H-NMR (CDCl ₃ ): 2.39 (s, 3H), 4.30-4.36 (m, 8H), 6.28 (d, 1H, cis), 6.72 (d, 1H, trans), 7.11-7.15 (m, 1H + 1H), 7.29 (s, 1H), 7.45 (d, 1H).

  (Synthesis of Compound g)

Under a nitrogen atmosphere, 1.688 g (4.01 mmol) of bis (p-iodophenyl) amine was dissolved in 10 mL of THF (dehydrated). 2.18 g (10.0 mmol) of di-tert-butyl dicarbonate and 98 mg (0.80 mmol) of 4-dimethylaminopyridine were added, and the mixture was heated to reflux for 2 hours. The reaction mixture was concentrated under reduced pressure, a small amount of methanol was added, and the precipitated white powder was collected by suction filtration to obtain 1.927 g (yield 92%) of the desired product (compound g).
¹ H-NMR (CDCl ₃ ): 1.47 (s, 9H), 6.93 (d, 4H), 7.62 (d, 4H).

  (Synthesis of Compound h)

Put 229 mg (0.198 mmol) of tetrakis (triphenylphosphine) palladium, 1.045 g (2.01 mmol) of Boc-substituted diiodo compound (compound g), and 1.45 mL (4.88 mmol) of thiopheneboronic acid derivative in a four-necked flask. And vacuum nitrogen substitution. After 20 mL of DME (dehydrated) and 15 mL of THF (dehydrated) were added and dissolved, an aqueous solution of cesium carbonate (2N, 10 mL) sufficiently deaerated with nitrogen bubbling was added dropwise. After heating at 60 ° C. for 3 hours, ethyl acetate and water were added to the reaction product, and the organic layer was washed successively with water, dried over Na ₂ SO ₄ , filtered, and concentrated under reduced pressure. The silica gel column was developed using a mixed solvent system of heptane: ethyl acetate (100: 0 → 90: 10) to obtain 1.188 g (crude yield 96%) of a pale yellow oily substance (compound h).
¹ H-NMR (CDCl ₃ ): 0.88 (t, 6H), 1.26-1.37 (br, 12H), 1.47 (s, 9H), 1.65 (m, 4H), 2 .60 (t, 4H), 6.85 (s, 2H), 7.11 (s, 2H), 7.21 (d, 4H), 7.52 (d, 4H).

  (Synthesis of Compound i)

Under a nitrogen atmosphere, 733 mg (1.19 mmol) of the Boc body (compound h) was dissolved in 30 mL of THF, and 8 mL of concentrated hydrochloric acid was added. The mixture was heated to reflux for 1.5 hours, neutralized with triethylamine, ethyl acetate was added, and the organic layer was washed successively with water, dried over Na ₂ SO ₄ , filtered, and concentrated under reduced pressure. Reprecipitation with a small amount of methanol and suction filtration gave 441 mg (74%) of the desired product (compound i) as a white powder.
¹ H-NMR (CDCl ₃ ): 0.89 (t, 6H), 1.33 (br, 12H), 1.64 (m, 4H), 2.60 (t, 4H), 6.80 (s) , 2H), 7.06 (s, 6H), 7.50 (d, 4H).

  (Synthesis of Compound j)

Palladium acetate 6.6 mg (0.029 mmol) and (t-Bu) ₃ P 80 μL (50% toluene solution, 0.17 mmol) were heated at 60 ° C. under nitrogen to obtain a pale yellow oily substance. 154 mg (0.301 mmol) of raw material bromo compound (compound f), 136 mg (0.270 mmol) of raw material secondary amine (compound i) and 10 mL of toluene (dehydrated) were added, followed by 55 mg (0.57 mmol) of t-BuONa. Added. After heating at 100 ° C. for 5 hours and cooling, water and diatomaceous earth were added, and suction filtration, washing with water, MgSO ₄ drying, and vacuum concentration were sequentially performed. Development of a silica gel column using a heptane: ethyl acetate mixed solvent system (100: 0 → 80: 20) gave 153 mg (yield 61%) of the desired product (compound j) as a yellow powder.
¹ H-NMR (CDCl ₃ ): 0.89 (t, 6H), 1.26 to 1.33 (br, 12H), 1.63 (m, 4H), 2.03 (s, 3H), 2 .59 (t, 4H), 4.20-4.38 (m, 8H), 6.80 (s + s + d, 2H + 1H), 6.92 (d + d, 1H + 1H), 6.98 (d, 4H), 7. 06-7.17 (m, 4H), 7.28-7.33 (s + d, 1H + 1H), 7.43 (d, 4H).

  (Synthesis of Compound k)

141 mg (0.151 mmol) of the raw material bis-EDOT-TPA derivative (compound j) was dissolved in 5 mL of THF (dehydrated) under nitrogen. 50 μL (0.65 mmol) of DMF (dehydrated) was added, and after ice cooling, 41 μL (0.45 mmol) of phosphoryl chloride was added. The mixture was heated at 60 ° C. for 2 hours, followed by hydrolysis by adding an aqueous sodium acetate solution (6%). Thereafter, chloroform was added, and the organic layer was washed with water, dried over Na ₂ SO ₄ , filtered, and concentrated under reduced pressure. By developing a silica gel column using a mixed solvent system of heptane: chloroform (70: 30 → 0: 100), 77 mg (yield 52%) of red powder (compound k) was obtained.
¹ H-NMR (CDCl ₃ ): 0.89 (t, 6H), 1.26 to 1.33 (br, 12H), 1.63 (m, 4H), 2.03 (s, 3H), 2 .60 (t, 4H), 4.20-4.38 (m, 8H), 6.80 (d, 1H), 6.92 (d + d, 1H + 1H), 6.98 (d, 4H), 7. 06-7.17 (m, 4H), 7.28-7.33 (s + d, 1H + 1H), 7.44 (d, 4H), 9.90 (s, 2H).

  (Synthesis of Compound D-1)

The raw material diformyl compound (compound k) 77 mg (0.078 mmol), cyanoacetic acid 20 mg (0.23 mmol) and piperidine 20 mg (0.23 mmol) were dissolved in 5 mL of chloroform under nitrogen, and heated under reflux for 6 hours. Water was added to the reaction solution to cause precipitation, and silica gel column development using a mixed solvent of ethyl acetate: methanol = 9: 1 gave 66 mg (yield 75%) of compound D-1 as a dark red powder.
¹ H-NMR (CDCl ₃ ): 0.89 (t, 6H), 1.26 to 1.33 (br, 12H), 1.66 (m, 4H), 2.05 (s, 3H), 2 .82 (t, 4H), 4.20-4.38 (m, 8H), 6.80 (d, 1H), 6.92 (d + d, 1H + 1H), 6.98 (d, 4H), 7. 07-7.20 (m, 4H), 7.28-7.33 (s + d, 1H + 1H), 7.47 (d, 4H), 8.37 (s, 2H).

(semiconductor)
As a semiconductor used for the semiconductor layer, silicon, germanium, a compound having a group 3 to group 5, group 13 to group 15 element of a periodic table (also referred to as an element periodic table), metal Chalcogenides (for example, oxides, sulfides, selenides, etc.), metal nitrides, and the like can be used. Preferred metal chalcogenides include titanium, tin, zinc, iron, tungsten, zirconium, hafnium, strontium, indium, cerium, yttrium, lanthanum, vanadium, niobium, or tantalum oxide, cadmium, zinc, lead, silver, antimony or Bismuth sulfide, cadmium or lead selenide, cadmium telluride and the like. Examples of other compound semiconductors include phosphides such as zinc, gallium, indium and cadmium, gallium-arsenic or copper-indium selenide, copper-indium sulfide, titanium nitride, and the like.

Specific examples include TiO ₂ , SnO ₂ , Fe ₂ O ₃ , WO ₃ , ZnO, Nb ₂ O ₅ , CdS, ZnS, PbS, Bi ₂ S ₃ , CdSe, CdTe, GaP, InP, GaAs, CuInS ₂ , CuInSe _{2, Ti} 3 _{N 4} and the like. Of these, TiO ₂ , ZnO, SnO ₂ , Fe ₂ O ₃ , WO ₃ , Nb ₂ O ₅ , CdS, and PbS are preferably used, and TiO ₂ or Nb ₂ O is more preferably used. ₅ is but particularly preferably used is among others a TiO ₂ (titanium oxide).

The semiconductor used for the semiconductor layer may be used alone or in combination of two or more semiconductors. For example, one or several kinds of the above-described metal oxides or metal sulfides can be used in combination, or a titanium oxide semiconductor mixed with 20% by mass of titanium nitride (Ti ₃ N ₄ ) can be used. Good. Alternatively, as a semiconductor, J.A. Chem. Soc. Chem. Commun. 15 (1999), it may be used in the form of a zinc oxide / tin oxide composite. In addition, when adding components other than a metal oxide or a metal sulfide as a semiconductor, it is preferable that mass ratio with respect to the metal oxide or metal sulfide semiconductor of an additional component is 30% or less.

  The shape of the semiconductor used for the semiconductor layer is not particularly limited, and may have any shape such as a spherical shape, a columnar shape, or a tubular shape. Further, the size of the semiconductor used for the semiconductor layer is not particularly limited. For example, when the semiconductor used for the semiconductor layer is spherical, the average particle size of the semiconductor is preferably 1 to 5000 nm, and more preferably 2 to 100 nm. The “average particle size” of the semiconductor used for the semiconductor layer is an average particle size (primary average particle size) of primary particle diameters when 100 or more samples are observed with an electron microscope.

  Further, the semiconductor according to the present invention may be surface-treated using an organic base. Examples of the organic base include diarylamine, triarylamine, pyridine, 4-t-butylpyridine, polyvinylpyridine, quinoline, piperidine, and amidine, among which pyridine, 4-t-butylpyridine, and polyvinylpyridine are preferable. . In this case, the semiconductor surface treatment method is not particularly limited, and a known method can be applied as it is or after being appropriately modified. For example, by preparing a solution (organic base solution) dissolved in an organic solvent as it is when the organic base is liquid, and by immersing the semiconductor according to the present invention in the liquid organic base or organic base solution. The surface treatment of the semiconductor can be performed.

(Method for producing photoelectric conversion layer)
Next, a method for manufacturing a photoelectric conversion layer (semiconductor layer) will be described. When the semiconductor of the semiconductor layer is in the form of particles, (1) a method of producing a semiconductor layer by applying or spraying a semiconductor dispersion or colloid solution (semiconductor-containing coating solution) on a conductive support; (2) semiconductor For example, a method (sol-gel method) in which a precursor of fine particles is applied on a conductive support, followed by hydrolysis with moisture (for example, moisture in the air) and then condensation can be used. The method (1) is preferred. In the case where the semiconductor according to the present invention is in a film form and is not held on the conductive support, it is preferable to produce a semiconductor layer by bonding the semiconductor onto the conductive support.

  As a preferable embodiment of the method for manufacturing the semiconductor layer, a method of forming the semiconductor layer by baking using fine particles of semiconductor on the conductive support can be given.

  When the semiconductor according to the present invention is produced by firing, the semiconductor sensitization (adsorption, filling in a porous layer, etc.) treatment with a dye is preferably performed after firing. It is particularly preferable to perform the compound adsorption treatment quickly after the firing and before the water is adsorbed to the semiconductor.

  Hereinafter, a method for forming a semiconductor layer preferably used in the present invention by firing using semiconductor fine powder will be described in detail.

(Preparation of semiconductor-containing coating solution)
First, a coating solution (semiconductor-containing coating solution) containing a semiconductor, preferably a fine powder of semiconductor, is prepared. The finer the primary particle diameter of the semiconductor fine powder, the better. The primary particle diameter is preferably 1 to 5000 nm, more preferably 2 to 100 nm. The coating liquid containing the semiconductor fine powder can be prepared by dispersing the semiconductor fine powder in a solvent.

  The semiconductor fine powder dispersed in the solvent is dispersed in the form of primary particles. The solvent is not particularly limited as long as it can disperse the semiconductor fine powder. Examples of the solvent include water, an organic solvent, and a mixed solution of water and an organic solvent. Examples of organic solvents include alcohols such as methanol, ethanol, and isopropanol, ketones such as methyl ethyl ketone, acetone, and acetyl acetone, hydrocarbons such as hexane and cyclohexane, cellulose derivatives such as acetyl cellulose, nitrocellulose, acetylbutyl cellulose, ethyl cellulose, and methyl cellulose. Is used. If necessary, a surfactant, an acid (such as acetic acid and nitric acid), a viscosity modifier (such as a polyhydric alcohol such as polyethylene glycol), and a chelating agent (such as acetylacetone) can be added to the coating solution. The range of the semiconductor fine powder concentration in the solvent is preferably 0.1 to 70% by mass, and more preferably 0.1 to 30% by mass.

(Application of semiconductor-containing coating solution and baking treatment of the formed semiconductor layer)
The semiconductor-containing coating solution obtained as described above is applied or sprayed onto a conductive support, dried, etc., and then baked in air or an inert gas to give a semiconductor on the conductive support. A layer (also referred to as a semiconductor film) is formed. Here, the coating method is not particularly limited, and examples thereof include known methods such as a doctor blade method, a squeegee method, a spin coating method, and a screen printing method.

  The film obtained by applying and drying a semiconductor-containing coating solution on a conductive support is composed of an aggregate of semiconductor fine particles, and the particle size of the fine particles corresponds to the primary particle size of the semiconductor fine powder used. Is.

  A semiconductor layer (semiconductor fine particle layer) formed on a conductive layer such as a conductive support in this way generally has a weak bonding force with the conductive support or a bonding strength between fine particles, and a mechanical strength. Too weak. For this reason, the semiconductor layer (semiconductor fine particle layer) is baked in order to increase the mechanical strength and form a semiconductor layer that is strongly fixed to the substrate.

  The semiconductor layer may have any structure, but is preferably a porous structure film (also referred to as a porous layer having voids). When the semiconductor layer is a porous structure film, it is preferable that components such as a hole transport material of the solid hole transport layer are also present in the voids. Here, the porosity (D) of the semiconductor layer is not particularly limited, but is preferably 1 to 90% by volume, more preferably 10 to 80% by volume, and particularly preferably 20 to 70% by volume. The porosity of the semiconductor layer means a porosity that is penetrable in the thickness direction of the dielectric, and can be measured using a commercially available device such as a mercury porosimeter (Shimadzu pore sizer 9220 type).

  The thickness of the semiconductor layer that is a fired product film having a porous structure is not particularly limited, but is preferably at least 10 nm or more, and more preferably 500 nm to 30 μm. If it is such a range, it can become a semiconductor layer excellent in characteristics, such as permeability and conversion efficiency. The semiconductor layer may be a single layer formed of semiconductor fine particles having the same average particle diameter, or a multilayer film (layered structure) composed of semiconductor layers containing semiconductor fine particles having different average particle diameters and types. Also good.

  The firing conditions are not particularly limited. From the viewpoint of appropriately preparing the actual surface area of the fired film during the firing treatment and obtaining a fired film having the above porosity, the firing temperature is preferably lower than 1000 ° C, more preferably in the range of 100 to 800 ° C. Especially preferably, it is the range of 300-800 degreeC. In addition, when the substrate is made of plastic or the like and is inferior in heat resistance, the fine particles and the fine particle-substrate can be fixed by pressurization without performing a baking process at 200 ° C. or higher, or the substrate can be formed by microwaves. Only the semiconductor layer can be heat-treated without heating. From the above viewpoint, the firing time is preferably 10 seconds to 12 hours, more preferably 1 to 240 minutes, and particularly preferably 10 to 120 minutes. Also, the firing atmosphere is not particularly limited, but usually the firing step is performed in air or in an inert gas (for example, argon, helium, nitrogen, etc.) atmosphere. The firing may be performed only once at a single temperature, or may be repeated twice or more by changing the temperature or time.

  The ratio of the actual surface area to the apparent surface area can be controlled by the particle size, specific surface area and firing temperature of the semiconductor fine particles. In addition, after heat treatment, in order to increase the efficiency of electron injection from the dye to the semiconductor particles by increasing the surface area of the semiconductor particles or increasing the purity in the vicinity of the semiconductor particles, Plating or electrochemical plating using a titanium trichloride aqueous solution may be performed.

(Sensitivity of semiconductor layer)
The total supported amount of the dye of the present invention per 1 m ^{2 of the} semiconductor layer is not particularly limited, but is preferably in the range of 0.01 to 100 mmol, more preferably 0.1 to 50 mmol, and particularly preferably 0.5. ~ 20 mmol.

  When performing the sensitization treatment, sensitizing dyes may be used alone or in combination, and other compounds (for example, US Pat. No. 4,684,537, US Pat. No. 4,927). No. 721, No. 5,084,365, No. 5,350,644, No. 5,463,057, No. 5,525,440, JP-A-7- 249790, JP-A 2000-150007, etc.) can also be used as a mixture.

  In particular, when the use of the photoelectric conversion element of the present invention is a solar cell to be described later, two or more types of dyes having different absorption wavelengths are used so that the wavelength range of photoelectric conversion can be made as wide as possible to effectively use sunlight. It is preferable to use a mixture.

  The method for supporting the sensitizing dye on the semiconductor is not particularly limited, and a known method can be applied in the same manner or appropriately modified. For example, in order to support a sensitizing dye on a semiconductor, a method in which a sensitizing dye is dissolved in an appropriate solvent and a well-dried semiconductor layer is immersed in the solution for a long time is generally used. Here, when a sensitizing treatment is carried out by using a plurality of sensitizing dyes in combination or other dyes in combination, a mixed solution of each dye may be prepared and used. A separate solution can be prepared and immersed in each solution in order. In addition, when preparing different solutions for each sensitizing dye and immersing them in each solution in order, the order in which the sensitizing dye and the like are included in the semiconductor may be whatever. Alternatively, it may be produced by mixing semiconductor fine particles adsorbing the dye alone.

  In the case of a semiconductor with a high porosity, it is preferable to complete the adsorption treatment of a sensitizing dye or the like before water is adsorbed on the semiconductor layer or inside the semiconductor layer by moisture, water vapor or the like.

  The semiconductor sensitization treatment is performed by dissolving the sensitizing dye in an appropriate solvent as described above and immersing the substrate obtained by firing the semiconductor in the solution. In that case, it is preferable that a substrate on which a semiconductor layer (also referred to as a semiconductor film) is formed by baking be subjected to pressure reduction treatment or heat treatment in advance to remove bubbles in the film. Such treatment allows the sensitizing dye to enter deep inside the semiconductor layer (semiconductor thin film), which is particularly preferable when the semiconductor layer (semiconductor thin film) is a porous structure film.

  The solvent used for dissolving the sensitizing dye is not particularly limited as long as it can dissolve the sensitizing dye and does not dissolve the semiconductor or react with the semiconductor. However, in order to prevent moisture and gas dissolved in the solvent from entering the semiconductor film and hindering sensitizing treatment such as adsorption of a sensitizing dye, it is preferable to deaerate and purify in advance. Solvents preferably used in dissolving the sensitizing dye include nitrile solvents such as acetonitrile, alcohol solvents such as methanol, ethanol, n-propanol, isopropanol and t-butyl alcohol, ketone solvents such as acetone and methyl ethyl ketone, diethyl Examples thereof include ether solvents such as ether, diisopropyl ether, tetrahydrofuran and 1,4-dioxane, and halogenated hydrocarbon solvents such as methylene chloride and 1,1,2-trichloroethane. These solvents may be used alone or in combination of two or more. Among these, acetonitrile, methanol, ethanol, n-propanol, isopropanol, t-butyl alcohol, acetone, methyl ethyl ketone, tetrahydrofuran and methylene chloride, and mixed solvents thereof such as acetonitrile / methanol mixed solvent, acetonitrile / ethanol mixed solvent, A mixed solvent of acetonitrile / t-butyl alcohol is preferred.

(Tensing temperature and time)
The conditions for the sensitization process are not particularly limited. For example, it is preferable that the time for immersing the semiconductor-baked substrate in a solution containing a sensitizing dye penetrates deeply into the semiconductor layer (semiconductor film) to sufficiently advance adsorption and the like to sufficiently sensitize the semiconductor. In addition, from the viewpoint of suppressing degradation of the dye produced by decomposition of the dye in the solution and preventing the adsorption of the dye, the sensitizing treatment temperature is preferably 0 to 80 ° C, more preferably 20 to 60 ° C. . From the same viewpoint, the sensitizing treatment time is preferably 15 minutes to 20 hours, more preferably 3 to 24 hours. In particular, it is preferable to perform the sensitizing treatment at room temperature (25 ° C.) for 2 to 48 hours, particularly 3 to 24 hours. This effect is particularly remarkable when the semiconductor layer is a porous structure film. However, the immersion time is a value under the condition of 25 ° C., and is not limited to the above when the temperature condition is changed. Moreover, you may perform a sensitizing process under reduced pressure or a vacuum from a viewpoint of shortening adsorption time or making it adsorb | suck to the deep part of a porous electrode.

  In soaking, the solution containing the dye of the present invention may be heated to a temperature that does not boil as long as the dye does not decompose. A preferable temperature range is 5 to 100 ° C., more preferably 25 to 80 ° C., but this is not the case when the solvent boils in the temperature range as described above.

(Solid hole transport layer)
The solid hole transport layer has a function of supplying electrons to the sensitizing dye oxidized by photoexcitation and reducing it, and transporting holes injected at the interface with the sensitizing dye to the second electrode.

  The solid hole transport layer contains a compound (conductive polymer) formed by polymerizing a compound represented by the following general formula (2) or a multimer of the compound. Hereinafter, the polymer is also referred to as “polymer”.

In the general formula (2), X ₁ and X ₂ are a hydrogen atom, a linear or branched alkyl group having 1 to 24 carbon atoms, a linear or branched alkenyl group having 2 to 24 carbon atoms, and a carbon number. It represents a 6-24 aryl group, —OR ₁ , —SR ₂ , —SeR ₃ , or —TeR ₄ . X ₁ and X ₂ may be the same or different. R _{1 to} R ₄ each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 24 carbon atoms. Here, X ₁ and X ₂ may be bonded to each other to form a ring structure.

The linear or branched alkyl group having 1 to 24 carbon atoms as X ₁ , X ₂ and R _{1 to} R ₄ is not particularly limited, and examples thereof include a methyl group, an ethyl group, an n-propyl group, and an isopropyl group. , N-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, tert-pentyl group, neopentyl group, 1,2-dimethylpropyl group, n-hexyl group, isohexyl group 1,3-dimethylbutyl group, 1-isopropylpropyl group, 1,2-dimethylbutyl group, n-heptyl group, 1,4-dimethylpentyl group, 3-ethylpentyl group, 2-methyl-1-isopropylpropyl Group, 1-ethyl-3-methylbutyl group, n-octyl group, 2-ethylhexyl group, 3-methyl-1-isopropylbutyl group, 2-methyl -1-isopropyl group, 1-t-butyl-2-methylpropyl group, n-nonyl group, 3,5,5-trimethylhexyl group, n-decyl group, isodecyl group, n-undecyl group, 1-methyldecyl group N-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group, n-eicosyl group, n-heneicosyl group , N-docosyl group, n-tricosyl group, n-tetracosyl group and the like.

Among these, X ₁ and X _2, preferably a linear or branched alkyl group having 6 to 18 carbon atoms, more preferably straight chain alkyl group having 6 to 18 carbon atoms. When the polymer has a long chain (for example, having 6 to 18 carbon atoms) alkyl group, the alkyl group acts as a functional group that inhibits self-aggregation and can suppress the formation of a self-aggregated structure. Is estimated to be improved.

As the R ₁ to R _4, preferably a linear or branched alkyl group having 1 to 5 carbon atoms, preferably an alkyl group having a straight chain of 1 to 5 carbon atoms.

The linear or branched alkenyl group having 2 to 24 carbon atoms as X ₁ and X ₂ is not particularly limited, and examples thereof include a vinyl group, a 1-propenyl group, a 2-propenyl group (allyl group), and isopropenyl. Group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 1-pentenyl group, 2-pentenyl group, 3-pentenyl group, 1-hexenyl group, 2-hexenyl group, 3-hexenyl group, 1-heptenyl group Group, 2-heptenyl group, 5-heptenyl group, 1-octenyl group, 3-octenyl group, 5-octenyl group and the like.

The aryl group having 6 to 24 carbon atoms as X ₁ and X ₂ is not particularly limited, and examples thereof include a phenyl group, a naphthyl group, a biphenyl group, a fluorenyl group, an anthryl group, a pyrenyl group, an azulenyl group, an acenaphthylenyl group, a ter Examples thereof include a phenyl group and a phenanthryl group. Among these, a phenyl group, a biphenyl group, and a fluorenyl group are preferable, and a phenyl group and a fluorenyl group are more preferable.

In X ₁ , X ₂ and R _{1 to} R ₄ , “a linear or branched alkyl group having 1 to 24 carbon atoms”, “a linear or branched alkenyl group having 2 to 24 carbon atoms”, “carbon number” At least one hydrogen atom in the “6 to 24 aryl group” may be substituted with a substituent.

In X ₁ , X ₂ , and R _{1 to} R ₄ , the substituent is a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, an iodine atom), each substituted or unsubstituted, a straight chain having 1 to 24 carbon atoms or Branched alkyl group (for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, tert- Pentyl group, neopentyl group, 1,2-dimethylpropyl group, n-hexyl group, isohexyl group, 1,3-dimethylbutyl group, 1-isopropylpropyl group, 1,2-dimethylbutyl group, n-heptyl group, 1 , 4-dimethylpentyl group, 3-ethylpentyl group, 2-methyl-1-isopropylpropyl group, 1-ethyl-3-methylbutyl group, n-o Cutyl group, 2-ethylhexyl group, 3-methyl-1-isopropylbutyl group, 2-methyl-1-isopropyl group, 1-t-butyl-2-methylpropyl group, n-nonyl group, 3,5,5- Trimethylhexyl, n-decyl, isodecyl, n-undecyl, 1-methyldecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl Group, n-octadecyl group, n-nonadecyl group, n-eicosyl group, n-heneicosyl group, n-docosyl group, n-tricosyl group, n-tetracosyl group, etc.), C 2-24 linear or branched Alkenyl groups (for example, vinyl group, 1-propenyl group, 2-propenyl group, isopropenyl group, 1-butenyl group, 2-butenyl group, 3-butyl group) Nyl group, 1-pentenyl group, 2-pentenyl group, 3-pentenyl group, 1-hexenyl group, 2-hexenyl group, 3-hexenyl group, 1-heptenyl group, 2-heptenyl group, 5-heptenyl group, 1- Octenyl group, 3-octenyl group, 5-octenyl group, etc.), C1-C18 hydroxyalkyl group (e.g., hydroxymethyl group, hydroxyethyl group, etc.), C1-C18 alkoxy group (e.g., methoxy group) , Ethoxy group, propoxy group, isopropoxy group, butoxy group, pentyloxy group, hexyloxy group, 2-ethylhexyloxy group, octyloxy group, nonyloxy group, decyloxy group, undecyloxy group, dodecyloxy group, tridecyloxy group Group, tetradecyloxy group, pentadecyloxy group, hexadecyloxy group Heptadecyloxy group, octadecyloxy group, etc.), C1-C24 acyl group (for example, formyl group, acetyl group, propionyl group, butyryl group, isobutyryl group, valeryl group, isovaleryl group, 2-methylvaleryl group, 3- Methyl valeryl group, 4-methyl valeryl group, t-butylacetyl group, pivaloyl group, caproyl group, 2-ethylhexanoyl group, 2-methylhexanoyl group, heptanoyl group, octanoyl group, benzoyl group), carbon number 6-24 Aryl groups (for example, phenyl group, naphthyl group, biphenyl group, fluorenyl group, anthryl group, pyrenyl group, azulenyl group, acenaphthylenyl group, terphenyl group, phenanthryl group), heteroaryl groups having 2 to 24 carbon atoms (for example, Pyrrolidinyl group, piperidinyl group, Perazinyl group, morpholino group, thiomorpholino group, homopiperidinyl group, chromanyl group, isochromanyl group, chromenyl group, pyrrolyl group, furanyl group, thienyl group, pyrazolyl group, imidazolyl group, furanyl group, oxazolyl group, isoxazolyl group, thiazolyl group, Isothiazolyl group, pyridyl group, pyridazinyl group, pyrimidinyl group, pyrazinyl group, pyranyl group, indolyl group, isoindolyl group, indazolyl group, purinyl group, indolizinyl group, quinolinyl group, isoquinolinyl group, quinazolinyl group, pteridinyl group, quinoxidinyl group, benzoxazinyl group , Carbazolyl group, phenazinyl group, phenothiazinyl group, phenanthridinyl group, etc.) and amino groups (eg, dimethylamino group, diethylamino group, diphenylamino) Etc.), it is selected from the group consisting of. In the above, the same substituent is not substituted. That is, a substituted alkyl group is not substituted with an alkyl group.

The substituent for X ₁ , X ₂ , and R _{1 to} R ₄ is preferably a linear alkyl group having 6 to 18 carbon atoms, and more preferably an n-octyl group.

  Preferable examples of the compound represented by the general formula (2) include the following compounds (H1-1) to (H1-7). However, the present invention is not limited to these. In the following examples, the polymer constituting the solid hole transport layer is defined by the following symbols.

  The terminal of the polymer is not particularly limited and is appropriately defined depending on the type of raw material (monomer, dimer, multimer, etc.) used, and is usually a hydrogen atom. Here, the polymer used in the present invention may be formed only from the compound represented by the above general formula (2), or the compound represented by the above general formula (2) and other single quantities. It may be formed from the body. Preferably, it is formed only from the compound represented by the general formula (2). In this case, the polymer may be formed only from a single type of compound represented by the general formula (2), or may be formed from a plurality of types of compounds represented by the general formula (2). It may be.

  Moreover, as another monomer, if it does not inhibit the characteristic of the polymer which concerns on this invention, it will not restrict | limit, A well-known monomer can be used. Specific examples include monomers such as pyrrole derivatives or furan derivatives and thiadiazole, and monomers having a π-conjugated structure. Here, the “π conjugate structure” represents a structure in which multiple bonds are alternately connected to single bonds. The content of the other monomer is not particularly limited as long as it does not hinder the properties of the polymer, but when the total monomer constituting the polymer is 100 moles, it is preferably about 0 to 90 moles. More preferably, it is about 0-50 mol.

  The polymer used in the present invention is a polymerization catalyst that contains one or more compounds represented by the general formula (2) or a multimer of these compounds, if necessary, together with other monomers. It can be obtained by polymerization or copolymerization in the presence of a metal complex.

  Here, the compound (monomer) illustrated above can be used as a compound represented by the said General formula (2). In addition to the above, multimerized compounds (oligomerized compounds; hereinafter collectively referred to as “multimers”) such as dimers or trimers of the compound represented by the general formula (2). Can be used for the above polymerization or copolymerization.

  For example, dimers (H2-1) to (H2-7) of the compounds (H1-1) to (H1-7) can be preferably used.

  Thus, it is preferable to use a multimer such as a dimer because the oxidation potential at the time of polymer formation is reduced and the synthesis rate of the polymer is shortened as compared with the case of using a monomer. The oligomerized compounds of these monomers are described in, for example, J. Org. R. Reynolds et. al. , Adv. Mater. , 11, 1379 (1999) or a method obtained by appropriately modifying the method. In addition, the monomer dimer is described in T.W. M.M. Swager et. al. , Journal of the American Chemical Society, 119, 12568 (1997), or a method obtained by appropriately modifying the method.

  Below, the preferable example of the manufacturing method of 3, 4- ethylenedioxythiophene (PEDOT) dimer (H2-1) which is a dimer of the monomer (H1-1) of the said polymer is described, for example. . However, the present invention is not limited to the following preferred examples, and other similar methods or other known methods can be applied.

[Synthesis of 3,4-ethylenedioxythiophene (PEDOT) dimer]
To a 1000 mL glass three-necked flask equipped with a stirrer, a thermometer, and a reflux condenser, 750 mL of anhydrous tetrahydrofuran and 25 g (0.15 mol) of 3,4-ethylenedioxythiophene were added and stirred under a nitrogen stream. While cooling in an acetone / dry ice bath, the internal temperature is -70 ° C. Thereafter, 113 mL (0.18 mol) of a 1.6 mol / L n-butyllithium hexane solution is dropped into the reaction system with a syringe over 5 minutes. After 25 minutes, 23.5 g (0.17 mol) of anhydrous copper chloride is added and allowed to react with stirring for about 3 hours. The reaction solution was added to 10 L of water, the product was filtered, dried, and purified by silica gel chromatography (mobile phase: methylene chloride) to obtain 17.9 g of PEDOT dimer (yield: about 72%). Obtained as white crystals.

(Polymer polymerization method)
The polymerization method is not particularly limited, and for example, a known polymerization method such as the method described in JP-A No. 2000-106223 can be applied. Specifically, a chemical polymerization method using a polymerization catalyst, an electropolymerization method in which at least a working electrode and a counter electrode are provided and a reaction is performed by applying a voltage between both electrodes, light irradiation alone or a polymerization catalyst, heating, electrolysis, etc. The combined photopolymerization method etc. are mentioned. Among these, a polymerization method using an electrolytic polymerization method is preferable, and a photopolymerization method combining an electrolytic polymerization method and light irradiation is more preferable. By using a combination of an electropolymerization method and a photopolymerization method of polymerizing by irradiating light, a polymer layer can be densely formed on the titanium oxide surface.

  When a polymer is obtained by an electrolytic polymerization method, the synthesis of the polymer directly leads to the formation of the solid hole transport layer. That is, the following electrolytic polymerization method is performed. Generally, a mixture comprising a monomer constituting the polymer according to the present invention, a supporting electrolyte (acceptor doping agent), a solvent, and, if necessary, an additive is used.

  The monomer represented by the general formula (2) or a multimer of the monomer and, if necessary, other monomers are dissolved in an appropriate solvent, and a supporting electrolyte (acceptor doping agent) is added thereto. Thus, an electrolytic polymerization solution is prepared.

  Here, the solvent is not particularly limited as long as it can dissolve the supporting electrolyte and the monomer or multimer thereof, but it is preferable to use an organic solvent having a relatively wide potential window. Specifically, polar solvents such as tetrahydrofuran (THF), butylene oxide, chloroform, cyclohexanone, chlorobenzene, acetone, various alcohols, dimethylformamide (DMF), acetonitrile, dimethoxyethane, dimethyl sulfoxide, hexamethylphosphoric triamide, And organic solvents such as aprotic solvents such as propylene carbonate, dichloromethane, o-dichlorobenzene, and methylene chloride. Alternatively, water or other organic solvents may be added to the above solvent as necessary to use as a mixed solvent. Moreover, the said solvent may be used independently or may be used with the form of a 2 or more types of mixture.

As the supporting electrolyte, those capable of ionization are used, and are not limited to specific ones, but those having high solubility in a solvent and being less susceptible to oxidation and reduction are preferably used. Specifically, lithium perchlorate (LiClO _4), lithium tetrafluoroborate, tetrabutylammonium _{perchlorate, Li [(CF 3 SO 2} ) 2 N], (n-C 4 H 9) 4 NBF 4 _{, (n-C 4 H 9} ) 4 NPF 4, p- toluenesulfonate, salts such as dodecylbenzene sulfonate may be preferably mentioned. Alternatively, a polymer electrolyte described in JP-A-2000-106223 (for example, PA-1 to PA-10 in the same publication) may be used as a supporting electrolyte, and the supporting electrolyte is used alone. Or may be used in the form of a mixture of two or more.

  The supporting electrolyte (acceptor doping agent) may be applied to the resulting polymerized film after the monomer or multimer electrolytic polymerization. The coating method is not particularly limited, but the supporting electrolyte (acceptor doping agent) may be dissolved in the solvent exemplified above, and the polymer film may be immersed in this solution. This is preferable because the conductivity of the hole transport layer is increased.

Next, the substrate on which the first electrode (transparent conductive film), the barrier layer, and the photoelectric conversion layer are formed is immersed in this electrolytic polymerization solution, and the photoelectric conversion layer 6 is used as a working electrode and a platinum wire or a platinum plate is used as a counter electrode. In addition, it is performed by direct current electrolysis using Ag / AgCl, Ag / AgNO ₃ or the like as a reference electrode. The concentration of the monomer or its multimer in the electrolytic polymerization solution is not particularly limited, but is preferably about 0.1 to 1000 mmol / L, more preferably about 1 to 100 mmol / L, and more preferably 5 to 20 mmol / L. The degree is particularly preferred. In addition, the supporting electrolyte concentration is preferably about 0.01 to 10 mol / L, and more preferably about 0.1 to 2 mol / L. As the applied current density, I am more desirable is preferably in the range of ^{0.01μA / cm 2 ~1000μA / cm 2} , in particular in the range of ^{1μA / cm 2 ~500μA / cm 2} . The holding voltage is preferably −0.5 to + 0.2V, and more preferably −0.3 to 0.0V. The temperature range of the electrolytic polymerization solution is suitably a range in which the solvent does not solidify or bump, and is generally -30 ° C to 80 ° C.

Moreover, you may use combining the photopolymerization method which irradiates light and polymerizes the said electrolytic polymerization. The wavelength of the irradiated light is preferably 380 to 1200 nm, more preferably 430 to 800 nm, and a xenon lamp is suitable as the light source. Moreover, it is preferable that it is 5-50 mW / cm < ² >, and, as for the intensity | strength of light, it is more preferable that it is 20-40 mW / cm < ² >. By performing electrolytic polymerization while irradiating light in this way, it is not necessary to apply a high potential, so that the dye can be polymerized without deteriorating. According to this method, a polymer layer can be densely formed on the surface of the photoelectric conversion layer (semiconductor layer).

  Note that conditions such as electrolysis voltage, electrolysis current, electrolysis time, and temperature depend on the materials used, and can be appropriately selected according to the required film thickness.

  Ascertaining the degree of polymerization of a polymer is difficult with a polymer obtained by electrolytic polymerization, but the solvent solubility of the solid hole transport layer formed after polymerization is greatly reduced. The solid hole transport layer can be immersed in tetrahydrofuran (THF), which is a solvent capable of dissolving the monomer of the compound of the general formula (2) or a multimer of the compound, and the solubility can be determined.

  Specifically, 10 mg of the compound (polymer) is taken into a 25 ml sample bottle, 10 ml of THF is added, and ultrasonic waves (25 kHz, 150 W, ultrasonic industry, COLLECTOR CURRENT 1.5A, made by ultrasonic industry 150) are added. When the compound dissolved is less than 5 mg when irradiated for 1 minute, it is defined as polymerized.

  Preferably, the solubility when the solid hole transport layer is immersed in tetrahydrofuran (THF) is 0.1 to 3 mg.

  On the other hand, when chemical polymerization is performed using a polymerization catalyst, for example, the monomer represented by the general formula (2) or a multimer thereof can be polymerized using the following polymerization catalyst. .

  The polymerization catalyst is not particularly limited, and examples thereof include iron (III) chloride (iron (III) chloride), iron (III) tris-p-toluenesulfonate (iron (III) tris-p-toluenesulfate), p-dodecyl. Iron (III) benzenesulfonate (iron (III) p-dedodecylbenzenesulfonate), iron (III) methanesulfonate (iron (III) methanesulfonate), iron (III) p-ethylbenzenesulfonate (iron (III) p-ethylbenzenesulfonate) And iron (III) naphthalene sulfonate (iron (III) naphthalenesulfonate) and hydrates thereof.

  In addition to the polymerization catalyst, a polymerization rate modifier may be used for chemical polymerization. Here, the polymerization rate adjusting agent used in the chemical polymerization is not particularly limited, but there is a weak complexing agent for trivalent iron ions in the polymerization catalyst as long as the polymerization rate is reduced so that a film can be formed. There is no particular limitation. For example, when the polymerization catalyst is iron (III) chloride and its hydrate, aromatic oxysulfonic acid such as 5-sulfosalicylic acid can be used. In addition, the polymerization catalyst is iron (III) tris-p-toluenesulfonate, iron (III) p-dodecylbenzenesulfonate, iron (III) methanesulfonate, iron (III) p-ethylbenzenesulfonate, iron naphthalenesulfonate. Examples of (III) and hydrates thereof include imidazole.

  After the polymer is synthesized, it may be contained in a coating solution containing the polymer and supplied onto the photoelectric conversion layer, but the polymer is polymerized on the photoelectric conversion layer to form a solid hole transport layer. Is a preferred embodiment. That is, it is preferable to perform polymerization of monomers or their multimers on the photoelectric conversion layer.

  In this case, in order to synthesize a polymer by polymerization, a monomer of the above general formula (2) or a multimer thereof, a supporting electrolyte or a polymerization catalyst, a polymerization rate adjusting agent, other additives, and a solvent are added. A solution for forming a solid hole transport layer is used. In the solid hole transport layer forming solution, the total concentration of the above components is the amount of the polymerization catalyst, the polymerization rate adjusting agent, and other additives such as the monomer of the general formula (2) used or its multimer. The mass concentration (solid content concentration) is generally in the range of 1 to 50% by mass, although it varies depending on each type, the amount ratio, conditions for the coating method and the desired film thickness after polymerization.

  After the solid hole transport layer forming solution is applied onto the photoelectric conversion layer by a coating method, or while the photoelectric reaction layer is immersed in the solid hole transport layer forming solution, a polymerization reaction is performed.

  The conditions for the polymerization reaction include the monomers of the above general formula (2) or the multimers thereof, the types of the polymerization catalyst, and the polymerization rate regulator, the amount ratio, the concentration, and the liquid in the applied stage. Although it varies depending on the thickness of the film and the desired polymerization rate, suitable polymerization conditions are preferably a range of heating temperature in the case of heating in air of 25 to 120 ° C. and a heating time of 1 minute to 24 hours.

  When the solid hole transport layer is formed by coating, the solvent of the solid hole transport layer forming solution is not particularly limited, but tetrahydrofuran (THF), butylene oxide, chloroform, cyclohexanone, chlorobenzene, acetone, various alcohols And polar solvents such as dimethylformamide (DMF), acetonitrile, dimethoxyethane, dimethyl sulfoxide, and organic solvents such as aprotic solvents such as hexamethylphosphoric triamide. Moreover, the said solvent may be used independently or may be used with the form of a 2 or more types of mixture.

  The coating method is not particularly limited, and a known coating method can be used similarly or appropriately modified. Specifically, dipping, dripping, doctor blade, spin coating, brush coating, spray coating, roll coater, air knife coating, curtain coating, wire bar coating, gravure coating, and an extension using a hopper described in US Pat. No. 2,681,294 Various coating methods such as a rouge coating and a multilayer simultaneous coating method described in U.S. Pat. Nos. 2,761,418, 3,508,947, and 2,761791 can be used. Further, the coating may be repeated by repeating such coating operation. The number of coatings in this case is not particularly limited, and can be appropriately selected according to the desired thickness of the solid hole transport layer.

Examples of the additive that can be added to the solid hole transport layer include N (PhBr) _3, SbCl ₆ , NOPF ₆ , SbCl ₅ , I ₂ , Br ₂ , HClO ₄ , (n-C ₄ H ₉ ) ₄ ClO. ₄ , trifluoroacetic acid, 4-dodecylbenzenesulfonic acid, 1-naphthalenesulfonic acid, FeCl ₃ , AuCl ₃ , NOSbF ₆ , AsF ₅ , NOBF ₄ , LiBF ₄ H 1-3 [PMo ₁₂ O ₄₀ ], 7, 7, Various additives such as acceptor doping agents such as 8,8-tetracyanoquinodimethane (TCNQ), binder resins that do not easily trap holes, and coating property improving agents such as leveling agents can be used. The above additives may be used alone or in the form of a mixture of two or more.

  The content of the compound represented by the general formula (2) in the solid hole transport layer or a polymer formed by polymerizing a multimer of the compound is not particularly limited. Considering the hole transport characteristics and the ability to suppress / prevent the disappearance of excitons generated near the interface of the photoelectric conversion layer, the content is preferably 50 to 100% by mass, more preferably 90 to It is preferable that it is 100 mass%.

  In order to increase the conductivity of the solid hole transport layer, the polymer is preferably hole doped. In this case, the hole doping amount is not particularly limited, but is preferably 0.15 to 0.66 (pieces) per compound of the general formula (2).

  In the electropolymerization, holes are doped by oxidizing a polymer having a structure derived from the compound represented by the general formula (2) by applying an electric field.

  In order to reduce the oxidized sensitizing dye in the photoelectric conversion layer, the polymer used in the present invention is preferably smaller than the ionization potential of the dye-adsorbing electrode. The preferred range of the ionization potential of the polymer is not particularly limited and varies depending on the sensitizing dye to be used. However, when the polymer is doped, it is preferably 4.5 eV or more and 5.5 eV or less, and more preferably 4.7 eV or more. It is preferable that it is 5.3 eV or less.

  In addition, when the visible light absorptance is low, light loss due to absorption is small and deterioration due to light can be suppressed. Therefore, a preferable solid hole transport layer preferably has an absorbance of 1.0 or less. Further, when the polymerization degree of the polymer is increased, the absorbance is slightly increased, and in order to obtain a polymerization degree having a preferable hole transporting ability, a charge transport layer having a polymerization degree exhibiting an absorbance of 0.2 or more is preferable. . Therefore, the polymer according to the present invention preferably has an absorbance at 400 to 700 nm (an average value of absorbance in a wavelength region of 400 to 700 nm) of 0.2 to 1.0.

In the present specification, the absorbance of the solid hole transport layer (polymer) is defined by using the difference in absorbance of the working electrode before and after electrolytic polymerization. In this case, the absorbance is the absorbance in the wavelength region of 400 to 700 nm. Mean value. Absorbance is measured using a spectrophotometer (JASCO V-530). As a working electrode, a titanium oxide thin film having an effective area of 10 × 20 mm ² formed on an FTO conductive glass substrate was adsorbed with a dye, immersed in a solution having the same composition as the electrolytic polymerization solution described above, and the counter electrode was a platinum wire, The reference electrode is Ag / Ag ⁺ (AgNO ₃ 0.01M), the holding voltage is −0.16 V, while irradiating light from the semiconductor layer direction (using a xenon lamp, light intensity 22 mW / cm ² , wavelength of 430 nm or less) (Cut) A voltage is maintained for 30 minutes, and a polymer having a repeating unit of the general formula (1) or (2) is formed on the working electrode and measured. In order to correct the influence of the variation in film thickness, the film thickness of the sample is measured, and a value divided by the film thickness (μm) is used. The film thickness is measured by Dektak 3030 (manufactured by SLOAN TECHNOLOGY Co.).

(Second electrode)
The second electrode is disposed adjacent to the solid hole transport layer and may be composed of any conductive material. Even an insulating material can be used if a conductive material layer is provided on the side facing the solid hole transport layer. The second electrode preferably has good contact with the solid hole transport layer. The second electrode preferably has a small work function difference from the solid hole transport layer and is chemically stable. Such a material is not particularly limited, but is a metal thin film such as gold, silver, copper, aluminum, platinum, rhodium, magnesium, indium, carbon, carbon black, a conductive polymer, a conductive metal oxide (indium -Organic conductors such as tin composite oxide, tin oxide doped with fluorine, and the like. The thickness of the second electrode is not particularly limited, but is preferably 10 to 1000 nm. The surface resistance of the second electrode is not particularly limited, but is preferably low. Specifically, the range of the surface resistance of the second electrode is preferably 80Ω / □ or less, more preferably 20Ω / □ or less. It is. The lower limit of the surface resistance of the second electrode is preferably as low as possible and need not be specified in particular.

  The formation method in particular of a 2nd electrode is not restrict | limited, A well-known method is applicable. For example, a method such as vapor deposition (including vacuum vapor deposition), sputtering, coating, screen printing, or the like is preferably used.

  In the photoelectric conversion element configured as described above, when light is irradiated from the outside of the substrate, the sensitizing dye carried on the semiconductor layer of the photoelectric conversion layer inside the element is excited to emit electrons. The excited electrons are injected into the semiconductor and move to the first electrode through the barrier layer. The electrons that have moved to the first electrode move to the second electrode through an external circuit and are supplied to the hole transport layer. The oxidized sensitizing dye (by releasing electrons) receives electrons from the hole transport layer and returns to the ground state. By repeating such a cycle, light is converted into electricity.

(Solar cell)
The photoelectric conversion element of this invention can be used especially suitably for a solar cell. Therefore, this invention also provides the solar cell which has the said photoelectric conversion element.

  The solar cell of the present invention comprises the photoelectric conversion element of the present invention, has a structure in which optimal design and circuit design are performed for sunlight, and optimal photoelectric conversion is performed when sunlight is used as a light source. Have. That is, the semiconductor is dye-sensitized and can be irradiated with sunlight. When constituting the solar cell of the present invention, the photoelectric conversion layer, the solid hole transport layer and the second electrode are preferably housed in a case and sealed, or the whole is resin-sealed.

  When the solar cell of the present invention is irradiated with sunlight or an electromagnetic wave equivalent to sunlight, the sensitizing dye supported on the semiconductor is excited by absorbing the irradiated light or electromagnetic wave. The electrons generated by the excitation move to the semiconductor, and then move to the second electrode via the conductive support and the external load, and are supplied to the hole transport material of the solid hole transport layer. On the other hand, the sensitizing dye that has moved electrons to the semiconductor is an oxidant, but is reduced by the supply of electrons from the second electrode via the polymer of the solid hole transport layer, thereby reducing the original. At the same time, the polymer of the solid hole transport layer is oxidized and returned to the state where it can be reduced again by the electrons supplied from the second electrode. In this way, electrons flow, and a solar cell using the photoelectric conversion element of the present invention can be configured.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these.

[Example 1: Production of photoelectric conversion element SC-1]
Commercially available fluorine-doped tin oxide (FTO) conductive glass substrate having a surface resistance of 9Ω / □ (FTO coating amount: 7 g / m ² substrate, first electrode thickness: 0.9 μm, conductive support thickness: 1. 1 mm) was used as a conductive support. This was washed in 15 minutes while irradiating the detergent with an alkaline detergent (Kikato Chemical Co., Ltd. Shikaclean LX-3) / ultra pure water = 10/90. Thereafter, it was washed with ultrapure water. The washing with the washing liquid and the washing with ultrapure water were repeated three times. Thereafter, UV / ozone cleaning was performed for 15 minutes using a synthetic quartz glass ultraviolet lamp.

  As a barrier layer, TC100 (manufactured by Matsumoto Kosho): titanium diisopropoxybis (acetylacetonate) was applied to this cleaning substrate (conductive support) by a spin coating method. After heating and drying at 80 ° C. for 10 minutes, baking was performed at 450 ° C. for 10 minutes to obtain a barrier layer (porosity C: 1.0%) having a film thickness of 100 nm.

  On top of this, a titanium oxide paste (particle size 18 nm) was applied by a doctor blade method. After heating at 120 ° C. for 5 minutes to dry the paste, baking was performed at 500 ° C. for 30 minutes to obtain a porous titanium oxide layer (semiconductor layer; porosity D: 50% by volume) having a thickness of 4.5 μm. .

Sensitizing dye (D-1) and 10 equivalents of chenodeoxycholic acid relative to the sensitizing dye are dissolved in a mixed solvent of acetonitrile: t-butyl alcohol = 1: 1, and the sensitizing dye concentration is 3 × 10 ⁻⁴ mol / L. A solution of was prepared. The FTO substrate (conductive support) carrying the porous titanium oxide layer (semiconductor layer) is immersed in this solution at room temperature (25 ° C.) for 3 hours to perform sensitizing dye adsorption treatment. A photoelectric conversion layer was obtained by supporting a sensitizing dye on the semiconductor. Thereby, a photoelectric conversion electrode was obtained. At this time, the total amount of the sensitizing dye of the present invention per 1 m ² of the semiconductor layer was 2 mmol.

The semiconductor electrode contains a monomer corresponding to the general formula (2): a dimer of H1-1 (H2-1) at a ratio of 0.01 (mol / l), and Li [(CF ₃ SO ₂ ) ₂ N] was immersed in 0.1 acetonitrile in a proportion of (mole / l) solution (electrolytic polymerization solution). At this time, the temperature of the electrolytic polymerization solution was adjusted to 25 ° C. The working electrode was the semiconductor electrode, the counter electrode was a platinum wire, the reference electrode was Ag / Ag ⁺ (AgNO ₃ 0.01M), and the holding voltage was −0.16V. The current density at the start of electrolysis was a current density of 2 .mu.A / cm ² at the end was 100 .mu.A / cm ^2. While irradiating light from the semiconductor layer direction (using a xenon lamp, light intensity of 22 mW / cm ² , cutting a wavelength of 430 nm or less), the voltage was maintained for 30 minutes to form a hole transport layer on the surface of the semiconductor electrode. The obtained semiconductor electrode / hole transport layer was washed with acetonitrile and dried.

  The hole transport layer obtained here is a polymer film that is insoluble in the solvent.

Then, to an acetonitrile solution containing Li [(CF ₃ SO ₂ ) ₂ N] at a ratio of 15 × 10 ⁻³ (mol / l) and 4-tert-butylpyridine at a ratio of 50 × 10 ⁻³ (mol / l). Soaked for 10 minutes.

  Thereafter, the semiconductor electrode / hole transport layer was naturally dried, and then 60 nm of gold was further deposited by vacuum deposition to produce a second electrode, thereby obtaining a photoelectric conversion element SC-1.

[Examples 2-12, Comparative Examples 1-3: Production of Photoelectric Conversion Elements SC-2-15]
In the production of the photoelectric conversion element SC-1 in Example 1, Example 1 except that the monomers forming the polymer constituting the sensitizing dye and / or the solid hole transport layer were changed to those shown in Table 1. Photoelectric conversion elements SC-2 to 15 were produced in the same manner as described in 1. In this example, all the polymers constituting the solid hole transport layer were synthesized using monomer dimers (H2-1 to H2-4).

[Comparative Example 4: Production of photoelectric conversion element SC-16]
In preparation of photoelectric conversion element SC-1 in Example 1, it described in Example 1 except having formed the solid hole transport layer by the spin coating method using the compound (HR-1) of Table 1. In the same manner as in the method, a photoelectric conversion element SC-16 was produced.

  Further, compounds D-R1, D-R2, DR-3 and HR-1 in Table 1 below are shown below.

[Evaluation of photoelectric conversion element]
Using a solar simulator (manufactured by Eihiro Seiki), photoelectric conversion characteristics were measured under the condition that a 5 x 5 mm ² mask was applied to the oxide semiconductor electrode (photoelectric conversion electrode) under irradiation of a xenon lamp with an intensity of 100 mW / cm ^2. It was.

  That is, for the photoelectric conversion elements SC-1 to SC-16, current-voltage characteristics were measured at room temperature (25 ° C.) using an IV tester, and the short-circuit current (Jsc), open-circuit voltage (Voc), and shape were measured. The factor (FF) was determined, and the photoelectric conversion efficiency (η (%)) was determined from these factors. The photoelectric conversion efficiency (η (%)) of the photoelectric conversion element was calculated based on the following formula (A).

Here, P is the incident light intensity [mW / cm ⁻² ], Voc is the open circuit voltage [V], Jsc is the short circuit current density [mA · cm ⁻² ], F. Indicates a form factor.

  Table 1 shows the results. Unless otherwise noted, the measured values are values at 25 ° C. However, the short-circuit current value at 0 ° C. was also measured and separately shown in Table 1.

  Considering that the charge transfer between the dye molecule and the solid hole transport layer is thermally activated, the ratio of the short-circuit current value at 25 ° C. to the short-circuit current value at 0 ° C. (short-circuit current at 25 ° C. Value / short-circuit current value at 0 ° C.) corresponds to a small activation energy that becomes a barrier to charge transfer. Therefore, it is considered that the intermolecular contact property is further improved as the short-circuit current ratio is larger.

(Measurement of photoelectric conversion efficiency after light degradation test)
Further, as a deterioration operation, the photoelectric conversion elements SC-1 to SC-16 were heated at 80 ° C. for 2 hours, and then irradiated with light with a xenon lamp having an intensity of 100 mW / cm ² for 120 minutes, and the photoelectric conversion efficiency after degradation (η (%)) )

  Table 1 shows the result of characteristic evaluation of each photoelectric conversion element.

  From Table 1, the photoelectric conversion element (SC-) of this invention which has the sensitizing dye which concerns on this invention, the solid hole transport layer containing the polymer of the PEDOT substitution product which has a specific structure, and the sensitizing dye which concerns on this invention 1 to 12) have high photoelectric conversion efficiency and excellent stability.

  On the other hand, the photoelectric conversion element (SC-13-16) of the comparative example comprised by the sensitizing dye and / or hole transport layer which remove | deviate from the range of this invention is the photoelectric element (SC-1-12) of an Example. Compared with the photoelectric conversion efficiency, the stability is also inferior.

In contrast, the sensitizing dye according to the present invention has a partial structure including a heteroaromatic ring, and all the carbon atoms (α-position carbon) adjacent to the heteroatom in the heteroaromatic ring are non-hydrogen atoms. Since it is bonded, it is advantageous for intermolecular contact between the dye molecule and the solid hole transport layer, and it is considered that the short circuit current and the conversion efficiency are increased. In addition, since the charge transfer speed between molecules increases due to the improvement of intermolecular contact, it is considered that the durability has been improved as the time existing as an unstable intermediate accompanying photoexcitation is shortened.
In particular, the photoelectric conversion elements (SC-1 to 10) having the heterocyclic structure represented by the general formula (3) at the end of the dye molecule are more excellent in photoelectricity than the other cases (SC-11 and 12). The conversion efficiency and durability are shown, and it is considered that the intermolecular contact between the dye and the solid hole transport material is further improved.

Further, when the heterocyclic substituent Y ₈ in the general formula (3) is a chlorine atom or a fluorine atom (SC-1 to 9), it shows much more excellent photoelectric conversion efficiency and durability, and the dye It is presumed that the steric hindrance between the molecule and the solid hole transport layer is small, so that it is advantageous to the intermolecular contact between the dye molecule and the solid hole transport layer.

Further, when the heterocycle (Ar ₈ ) is a thiophene ring-containing group, particularly a 3,4-ethylenedioxythiophene group, the short-circuit current ratio at 25 ° C. and 0 ° C. (= short-circuit current value at 25 ° C./0° C. The short-circuit current value) is large, and the intermolecular contact is considered to be further improved.

  From the above results, due to the effect of the combination of the sensitizing dye of the present invention and the solid hole transport layer containing a thiophene polymer, the contact property and charge transfer process between the dye molecule and the solid hole transport layer are improved. It can be estimated that the conversion efficiency and durability of the photoelectric conversion element have been improved.

1 substrate,
2 first electrode,
3 barrier layers,
4 Sensitizing dyes,
5 Semiconductor,
6 photoelectric conversion layer,
7 solid hole transport layer,
8 Second electrode,
9 Incident direction of sunlight,
10 Photoelectric conversion element.

Claims (8)

In a photoelectric conversion element having a first electrode, a photoelectric conversion layer containing a semiconductor and a sensitizing dye, a solid hole transport layer, and a second electrode on the substrate,
The sensitizing dye is represented by the following general formula (1A) or general formula (1B):
In the general formula (1A),
Ar ₁ is a monovalent aromatic group having a heteroaromatic ring-containing group as a substituent, and a carbon atom adjacent to the heteroatom in the heteroaromatic ring is bonded to a non-hydrogen atom;
Ar ₂ and Ar ₃ are each independently a divalent aromatic group;
At this time, at least two of Ar _{1 to} Ar ₃ may be bonded to each other to form a ring structure;
Z ₂ and Z ₃ are an organic residue having an acidic group or an acidic ring structure, and an electron-withdrawing group or electron-withdrawing ring structure;
In the general formula (1B),
Ar ₄ and Ar ₅ are each independently a substituted or unsubstituted monovalent aromatic group, and at this time, at least one of Ar ₄ and Ar _{5 has} a heteroaromatic ring-containing group as a substituent A monovalent aromatic group, the carbon atom adjacent to the heteroatom in the heteroaromatic ring is bonded to a non-hydrogen atom;
Ar ₆ is a divalent aromatic group;
At this time, at least two of Ar _{4 to} Ar ₆ may be bonded to each other to form a ring structure;
Z ₆ is an organic group having an acidic group or an acidic ring structure, and an electron-withdrawing group or electron-withdrawing ring structure;
The solid hole transport layer is represented by the following general formula (2):
In the general formula (2),
X ₁ and X ₂ are each independently a hydrogen atom, an optionally substituted linear or branched alkyl group having 1 to 24 carbon atoms, or an optionally substituted carbon number. A linear or branched alkenyl group having 2 to 24, an aryl group having 6 to 24 carbon atoms which may have a substituent, -OR ₁ , -SR ₂ , -SeR ₃ , or -TeR ₄ ; R _{1 to} R ₄ are each independently a hydrogen atom or a linear or branched alkyl group having 1 to 24 carbon atoms which may have a substituent, wherein X ₁ and X ₂ are , May combine with each other to form a ring structure,
In X ₁ , X ₂ , and R _{1 to} R ₄ , the substituent is a halogen atom, a substituted or unsubstituted linear or branched alkyl group having 1 to 24 carbon atoms, and a straight chain having 2 to 24 carbon atoms. Chain or branched alkenyl group, C1-C18 hydroxyalkyl group, C1-C18 alkoxy group, C1-C24 acyl group, C6-C24 aryl group, C2-C24 Selected from the group consisting of:
The photoelectric conversion element containing the polymer formed by superposing | polymerizing the compound represented by these, or the multimer of the said compound. Ar ₁ in the general formula (1A) or Ar ₄ in the general formula (1B) is represented by the following general formula (3):
In the general formula (3),
Ar ₇ is a divalent aromatic group;
Ar ₈ is a divalent heteroaromatic ring-containing group;
Y ₈ is a monovalent group other than a hydrogen atom;
m is an integer from 1 to 10;
The photoelectric conversion element of Claim 1 represented by these. The photoelectric conversion element according to claim 2, wherein Ar ₈ in the general formula (3) is a thiophene ring-containing group. The photoelectric conversion element according to claim 2 or 3, wherein Y ₈ in the general formula (3) is a chlorine atom or a fluorine atom. The photoelectric conversion element according to claim 2, wherein Ar ₈ is a divalent group derived from 3,4-ethylenedioxythiophene in the general formula (3). Z ₃ in the general formula (1A) or Z ₆ in the general formula (1B) has the following structure:
In the above, R ₁₁ is a hydrogen atom, a halogen atom, a linear or branched alkyl group having 1 to 24 carbon atoms, an aryl group having 6 to 24 carbon atoms, an aralkyl group having 7 to 24 carbon atoms, or 1 to 1 carbon atoms. 18 alkoxy groups or cyano groups,
The photoelectric conversion element of any one of Claims 1-5 represented by these.   The photoelectric conversion element according to claim 1, wherein the semiconductor is titanium oxide.   A solar cell provided with the photoelectric conversion element of any one of Claims 1-7.