JP2000322932A - Gel electrolyte, photoelectric transfer element, and photoelectric chemical battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide good durability by containing reaction products of compound having a plurality of nitrogen containing heterocyclic groups and compound containing a plurality of electrophilic substituted groups. SOLUTION: Reaction products of compound having nitrogen containing heterocyclic groups represented by two or more formulas I and compound having electrophilic substituted groups represented by two or more formulas II are preferably formed by reacting them in a solvent dissolving salt. In the formulas I, Z is a nitrogen containing heterocyclic group, L is an organic group, p1 is the number of nitrogen containing heterocyclic groups bonded to the organic group L and integer of 2-8. In the formulas II, Y is an electrophilic substituted group, L' is an organic group, p2 is the number of electrophilic substituted groups bonded to the organic group L' and integer of 2-8. As the nitrogen containing heterocyclic group, at least one kind selected from a group comprising a pyridine ring, an imidazole ring, a thiazole ring, an oxazole ring, a thothiazole ring, a morpholine ring, a piperidine ring, and a piperazine ring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gel electrolyte suitable for use in electrochemical devices such as batteries, capacitors, sensors, display devices, recording devices, and the like, and to a photovoltaic device using this gel electrolyte and a semiconductor photosensitive agent. The present invention relates to a conversion element and a photoelectrochemical cell.

[0002]

2. Description of the Related Art Conventionally, liquid electrolytes have been used as electrolytes for electrochemical devices such as batteries, capacitors, sensors, display devices, and recording devices. However, the liquid electrolyte sometimes leaks during long-term use or storage, and thus lacks reliability.

[0003] For example, Nature (Vol. 353, pp. 737-740, 1
991) and U.S. Pat. No. 4,492,721 disclose a photoelectric conversion element using semiconductor particles sensitized with a dye (hereinafter, referred to as "dye-sensitized photoelectric conversion element") and a photoelectrochemical cell using the same. However, also in these, since the liquid electrolyte is used for the charge transport layer, there is a concern that the electrolyte solution leaks or depletes due to long-term use, which significantly lowers the photoelectric conversion efficiency or stops functioning as an element.

In order to overcome such disadvantages, an international patent
No. 93/20565 proposes a photoelectric conversion element using a solid electrolyte, and JP-A-7-2881142, Solid State Ionic
s, 89, 263 (1986) and JP-A-9-27352 propose a photoelectric conversion element solidified using a crosslinked polyethylene oxide-based polymer solid electrolyte. However, it has been found that the photoelectric conversion elements using these solid electrolytes have not only an insufficient level of photoelectric conversion characteristics, particularly a short-circuit current density, but also an insufficient level of durability.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a gel electrolyte having excellent durability which can solve the problems of the conventional liquid electrolyte and solid electrolyte.
Another object of the present invention is to provide a photoelectric conversion element having excellent photoelectric conversion characteristics and durability due to the use of the gel electrolyte, and a photoelectrochemical cell having such a photoelectric conversion element.

[0006]

DISCLOSURE OF THE INVENTION In view of the above object, as a result of intensive studies, it has been found that a compound having two or more nitrogen-containing heterocyclic
The present inventors have found that a gel electrolyte having excellent durability can be obtained by using a reaction product with a compound having one or more electrophilic substituents, and reached the present invention.

That is, the gel electrolyte of the present invention is characterized by containing a reaction product of a compound having two or more nitrogen-containing heterocyclic groups and a compound having two or more electrophilic substituents.

The photoelectric conversion element of the present invention is characterized in that a conductive support, a photosensitive layer, a charge transfer layer and a counter electrode are laminated in this order, and the charge transfer layer contains the above-mentioned gel electrolyte.

Further, a photoelectrochemical cell of the present invention is characterized by having the above-mentioned photoelectric conversion element.

In the present invention, a gel electrolyte, a photoelectric conversion element and a photoelectrochemical cell having more excellent durability can be obtained by satisfying the following conditions. (1) The compound having two or more nitrogen-containing heterocyclic groups is represented by the following formula (I):

Embedded image (Where Z represents a nitrogen-containing heterocyclic group, L represents an organic group, p ₁ represents the number of nitrogen-containing heterocyclic groups bonded to the organic group L, and is an integer of 2 to 8). Are preferred. (2) In the formula (I), the nitrogen-containing heterocyclic group Z is a pyridine ring,
It is preferably at least one selected from the group consisting of an imidazole ring, a thiazole ring, an oxazole ring, a triazole ring, a morpholine ring, a piperidine ring and a piperazine ring. Also, p ₁ is preferably an integer of 2 to 4. (3) The compound having two or more electrophilic substituents has the following formula (II):

Embedded image (However, Y represents an electrophilic substituent, L ′ represents an organic group, p ₂ represents the number of electrophilic substituents bonded to the organic group L ′, and is an integer of 2 to 8.) Those represented are preferred. (4) In the formula (II), the electrophilic substituent Y is preferably at least one selected from the group consisting of a halogen atom, an acyloxy group and a sulfonyloxy group. Further, p ₂ is preferably an integer of ₂ to 4. (5) a reaction product of a compound having two or more nitrogen-containing heterocyclic groups and a compound having two or more electrophilic substituents,
It is preferably obtained by reacting in a solvent in which a salt is dissolved. (6) In the above photoelectric conversion element, the charge transfer layer is (1)
It is preferable to include the gel electrolyte according to any one of (1) to (5). (7) In the above photoelectric conversion element, it is preferable that the photosensitive layer is composed of semiconductor fine particles sensitized by a dye and a gel electrolyte filled in voids between the dye-sensitized semiconductor fine particles. As the semiconductor fine particles, titanium dioxide fine particles are preferable. The dye is preferably a metal complex dye, a phthalocyanine dye or a polymethine dye.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The photoelectric conversion element and the photoelectrochemical cell of the present invention are a reaction product of a compound having two or more nitrogen-containing heterocyclic groups and a compound having two or more electrophilic substituents. Is characterized in that a gelled electrolyte is used as a matrix. Thereby, excellent photoelectric conversion characteristics,
Further, a photoelectric conversion element and a photoelectrochemical cell in which deterioration of characteristics over time is prevented can be obtained. On the other hand, when a conventional liquid electrolyte using a solvent such as acetonitrile is used, deterioration of characteristics over time becomes remarkable, and photoelectric conversion characteristics deteriorate. Even if a gel electrolyte is used, a compound different from that of the present invention (for example, a crosslinked polyethylene oxide-based polymer solid electrolyte described in JP-A-9-27352) not only has poor photoelectric conversion characteristics, but also has a property with time. Deterioration is also large.

[1] Gel Electrolyte The gel electrolyte of the present invention comprises a reaction between (A) a compound having two or more nitrogen-containing heterocyclic groups and (B) a compound having two or more electrophilic substituents. Is obtained by Hereinafter, these compounds and reaction conditions will be described in detail.

(A) Compound Having Two or More Nitrogen-Containing Heterocyclic Groups The nitrogen-containing heterocyclic group means a substituent that can be quaternarily alkylated by an electrophile. Preferred compounds containing a nitrogen-containing heterocyclic group include the following formula (I):

Embedded image (However, Z represents a nitrogen-containing heterocyclic group, L represents an organic group, p ₁ represents the number of the nitrogen-containing heterocyclic group bonded to the organic group L, and is an integer of 2 to 8.) And the compounds represented.

The nitrogen-containing heterocyclic ring in the nitrogen-containing heterocyclic group represented by Z may be an unsaturated ring or a saturated ring, and may have an atom other than a nitrogen atom. As an unsaturated heterocyclic ring,
For example, a pyridine ring, an imidazole ring, a thiazole ring, an oxazole ring, a triazole ring and the like can be mentioned. Examples of the saturated heterocycle include a morpholine ring, a piperidine ring, and a piperazine ring. Preferred nitrogen-containing heterocycles are unsaturated heterocycles, more preferably pyridine rings or imidazole rings. These are preferably unsubstituted, but may be substituted with an alkyl group such as a methyl group.

The organic group L is not particularly limited as long as it has a bond to which 2 to 8 nitrogen-containing heterocyclic groups Z can bind. The organic group L is called divalent to octavalent according to the number of bonds. In each case where the organic group L is divalent to octavalent, preferred structures are as follows.

When L is a divalent organic group, any divalent organic group having at least one atom selected from the group consisting of C, O, N and S can be used.
Arylene _{group, -CR 111 = CR 112 -,} - CR 111 = N -, - N = N -, - N
(O) = N -, - CO -, - O -, - S -, - NR 12 1 -, - (C≡C) 1 ~ 3 - or constituted by a combination of these organic groups (units), an organic group (e.g., -COO -, - COS -, - CONR 121 -, - COC
_{H 2 -, - OCH 2 -} , - OCH 2 CH 2 -, - O (CH 2) 3 ~ 12 -, - CH 2 NR
_{121 -, - CR 111 = CR} 121 -CO -, - OCOO- , etc.), or preferably one having a plurality of these organic groups units. Of these, more preferred are an alkylene group, an arylene group, and -C
O- or an organic group containing an oxyalkylene group (constituted by an alkylene group and -O-), an organic group containing an oxyalkylene group is particularly preferred, and an organic group containing -OCH ₂ CH _2- is most preferred. . However, R ₁₁₁ , R ₁₁₂ and R ₁₂₁ each represent a hydrogen atom or an alkyl group.

When L is a trivalent organic group, the following basic structure:

Embedded image (Wherein R ₁₀ is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms), or a trivalent organic group represented by a combination of any of them and the above-described divalent organic group. Are preferred.

When L is a tetravalent organic group, the following basic structure:

Embedded image Or a combination of any of them and one or more of the above-mentioned divalent organic groups, a combination of two of the above-mentioned trivalent organic groups, or two of the above-mentioned trivalent organic groups and An organic group composed of a combination of two or more divalent organic groups is preferred.

When L is a 5- to 8-valent organic group,
An organic group having a configuration in which a valent organic group and / or a tetravalent organic group is combined, or an organic group having a configuration in which a divalent organic group is added thereto can be used.

The nitrogen-containing heterocyclic group Z bonded to the organic group L
The number p ₁ may be any integer as long as it is an integer of 2 or more, but is generally preferably 2 to 8, more preferably 2, 3 or 4. When p ₁ is less than 2, the reaction product with the compound having an electrophilic substituent does not become a polymer, and when p ₁ exceeds 8, the mobility of carrier ions in the gel electrolyte is undesirably reduced.

The organic group L may have a substituent, and examples of preferred substituents include the following. (a) a substituted or unsubstituted alkyl group (which may be linear or branched) preferably has 1 to 24 carbon atoms, and the substituent capable of bonding to the alkyl group includes a halogen atom, a cyano group, an alkoxy group , An alkoxycarbonyl group, an aryl group, a heterocyclic group and the like. Preferred specific examples of such a substituted or unsubstituted alkyl group include, for example, methyl, ethyl,
i-propyl, butyl, t-butyl, octyl, 2-ethylhexyl, trifluoromethyl, cyanomethyl, benzyl, 3- (1-octylpyridinium-4-yl) propyl, 3
-(1-butyl-3-methylpyridinium-4-yl) propyl, 2-methoxyethyl, propoxyethyl, ethoxycarbonylmethyl and the like. (b) A substituted or unsubstituted alkenyl group (which may be linear or branched) preferably has 2 to 24 carbon atoms, such as a vinyl group and an allyl group. (c) Aryl group which may be substituted or condensed, preferably has 6 to 24 carbon atoms, and the substituent capable of bonding to the aryl group is preferably a halogen atom, a cyano group, an alkyl group or the like. Preferred specific examples of such a substituted or unsubstituted aryl group include, for example, phenyl, 4-methylphenyl, 3-cyanophenyl, 2-chlorophenyl,
2-naphthyl and the like. (d) Heterocyclic group which may be substituted or condensed In the case of a nitrogen-containing heterocyclic group, the nitrogen in the ring may be quaternized. The substituent having preferably 2 to 24 carbon atoms and capable of bonding to the heterocyclic group is preferably a halogen atom, a cyano group, an alkyl group or the like. Preferred specific examples of such a substituted or unsubstituted heterocyclic group include, for example, 4-pyridyl,
2-pyridyl, 1-octylpyridinium-4-yl, 2-pyrimidyl, 2-imidazolyl, 2-thiazolyl and the like. (e) Alkoxy group Preferably, it has 1 to 24 carbon atoms, and the substituent capable of bonding to the alkoxy group is preferably a halogen atom, a cyano group, an alkyl group, or the like. Preferred specific examples of such a substituted or unsubstituted alkoxy group include, for example, methoxy,
Ethoxy, butoxy, octyloxy and the like can be mentioned. (f) Acyloxy group Preferably it has 1 to 24 carbon atoms, for example, acetyloxy, benzoyloxy and the like. (g) Substituted or unsubstituted alkoxycarbonyl group preferably has 2 to 24 carbon atoms, and as the substituent capable of bonding to the alkoxycarbonyl group, a halogen atom, a cyano group, an alkyl group, or the like is preferable. Preferred specific examples of such a substituted or unsubstituted alkoxycarbonyl group include methoxycarbonyl, ethoxycarbonyl and the like. (h) Others A cyano group, a halogen (eg, chlorine, bromine) and the like can be mentioned.

Preferred specific examples of the compound having a nitrogen-containing heterocyclic group are shown below, but the present invention is not limited thereto.

[0023]

Embedded image

[0024]

Embedded image

[0025]

Embedded image

[0026]

Embedded image

(B) Compound Having Two or More Electrophilic Substituents A compound having two or more electrophilic substituents is a bifunctional or more functional alkylating agent capable of quaternary alkylating a nitrogen-containing heterocycle. And the electrophilic substituent is not particularly limited as long as it can be a leaving group at the time of alkylation. Preferred compounds having an electrophilic substituent include compounds represented by the following formula (I
I):

Embedded image (However, Y represents an electrophilic substituent, L ′ represents an organic group, and p ₂ represents the number of the electrophilic substituent bonded to the organic group L ′, and is an integer of 2 to 8. )).

Examples of Y include a halogen atom (chlorine, bromine, iodine) and a substituted or unsubstituted acyloxy group (substituents are preferably a halogen atom, an alkyl group, etc.
Specific examples include acetoxy, trifluoroacetyloxy, trichloroacetyloxy and the like. ), A sulfonyloxy group (eg, methylsulfonyloxy, tolylsulfonyloxy, trifluoromethylsulfonyloxy, etc.), and the like, with a halogen atom being preferred and iodine being particularly preferred.

L ′ and p ₂ in the formula (II) are
It may be the same as those described in L and p ₁ of (I).

Preferred specific examples of the compound having two or more electron-withdrawing substituents are shown below, but the present invention is not limited thereto.

[0031]

Embedded image

[0032]

Embedded image

[0033]

Embedded image

(C) Gelation Reaction In the combination of the compound represented by the formula (I) and the compound represented by the formula (II), at least one of p ₁ and p ₂ is preferably 3 or more. p ₁ and p ₂ of both unfavorably difficult to gelation is less than 3.

The gelation reaction is preferably carried out in the presence of a salt in addition to the compound having two or more nitrogen-containing heterocyclic groups and the compound having two or more electrophilic substituents. In the gel electrolyte of the present invention, a salt is essential as an electrolyte. A salt can be added after gelation, but this is not preferred because it becomes difficult to uniformly disperse the salt in the gel.

The salts include (a) I ₂ and iodide (LiI, Na
A metal iodide such as I, KI, CsI, CaI ₂ or a quaternary ammonium compound such as tetraalkylammonium iodide, pyridinium iodide, imidazolium iodide, etc.), and (b) Br ₂ bromide combination of (LiBr, NaBr, KBr, CsBr , CaBr 2 , etc. of a metal bromide or tetraalkylammonium bromide, bromine salts of quaternary ammonium compounds such as pyridinium bromide), (c) ferrocyanate - ferricyanide Metal complexes such as acid salts and ferrocene-ferricinium ions, (d) sulfur compounds such as sodium polysulfide and alkylthiol-alkyl disulfide, (e) viologen dyes, hydroquinone-quinone, and the like can be used.
Among them, I ₂ and LiI or pyridinium iodide, electrolyte obtained by combining the iodine salt of imidazolium iodide quaternary ammonium compounds such as id are preferred. The above salts may be used as a mixture.

The compound having two or more nitrogen-containing heterocyclic groups and the compound and salt having two or more electrophilic substituents are dissolved in a common solvent to form an electrolyte solution. Also EP
718288, WO95 / 18456, J. Electrochem. Soc., Vol.143,
No. 10, 3099 (1996), Inorg.Chem., 35, 1168-1178 (1
When a salt in a molten state at room temperature (molten salt) described in 996) is used, a solvent need not be used.

As the solvent, it is preferable to use a compound which can exhibit excellent ionic conductivity because it has a low viscosity and a high ion mobility, or has a high dielectric constant and a high effective carrier concentration, or both. desirable. Examples of such solvents include, for example, the following.

(A) Carbonates Esters such as ethylene carbonate, propylene carbonate, vinylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate and dipropyl carbonate are preferred.

(B) Lactones For example, γ-butyrolactone, γ-valerolactone, γ-
Caprylolactone, crotlactone, γ-caprolactone, δ-valerolactone and the like are preferred.

(C) Ethers For example, ethyl ether, 1,2-dimethoxyethane, diethoxyethane, trimethoxymethane, ethylene glycol dimethyl ether, polyethylene glycol dimethyl ether, 1,3-dioxolan, 1,4-dioxane and the like are preferable.

(D) Alcohols For example, methanol, ethanol, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, polyethylene glycol monoalkyl ether, polypropylene glycol monoalkyl ether and the like are preferable.

(E) Glycols For example, ethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol, glycerin and the like are preferable.

(F) Tetrahydrofurans For example, tetrahydrofuran, 2-methyltetrahydrofuran and the like are preferable.

(G) Nitriles: For example, acetonitrile, glutarodinitrile, propionitrile, methoxyacetonitrile, benzonitrile and the like are preferable.

(H) Carboxylic esters Esters such as methyl formate, methyl acetate, ethyl acetate and methyl propionate are preferred.

(I) Phosphoric acid triesters For example, trimethyl phosphate, triethyl phosphate and the like are preferable.

(J) Heterocyclic compounds For example, N-methylpyrrolidone, 4-methyl-1,3-dioxane, 2-methyl-1,3-dioxolan, 3-methyl-2-oxazolidinone, 1,3-propanesal Ton, sulfolane and the like are preferred.

(K) Other aprotic organic solvents such as dimethyl sulfoxide, formamide, N, N-dimethylformamide, nitromethane, etc.
Water and the like are preferred.

Among these, carbonate-based, nitrile-based and heterocyclic compound-based solvents are preferred. These solvents may be used as a mixture of two or more as necessary.

The concentration of the compound having a nitrogen-containing heterocyclic group in the electrolyte solution is preferably 0.1 to 1 mol / L,
~ 0.6 mol / L is more preferred. If the compound having a nitrogen-containing heterocyclic group is less than 0.1 mol / L, the gel strength is insufficient,
On the other hand, if it exceeds 1 mol / L, the mobility of carriers is undesirably reduced. The compound having a nitrogen-containing heterocyclic group may be used alone or in combination of two or more.

The amount of the compound having an electrophilic substituent in the electrolyte solution is set so that the molar ratio of the electrophilic substituent to the reactive nitrogen atom in the compound having a nitrogen-containing heterocycle is 0.01 to 2. It is more preferable to make it be 0.05 to 1.5. The compound having an electrophilic substituent may be used alone or in combination of two or more.

The concentration of the salt in the electrolyte solution is 0.05 to 2 mol / L.
And more preferably 0.1 to 1.5 mol / L. In addition, iodine (bromine in the case of a bromine salt) may be added to the electrolyte of the present invention to generate a redox couple in advance. In this case, the preferred concentration of iodine or bromine is 0.01 to 0.3 mol / L. It is.

The gel electrolyte layer is formed by forming a layer comprising a solution of the gel electrolyte of the present invention on the electrode by a casting method, a coating method, an immersion method, an impregnation method, a permeation method, etc., and then gelling by a heating reaction. , Can be manufactured.

When the electrolyte layer is formed by a coating method, a uniform electrolyte solution to which an additive such as a coating property improving agent such as a leveling agent is added is coated by a spin coating method, a dip coating method, an air knife coating method, a curtain coating method. Roller coating method, wire bar coating method, gravure coating method, extrusion coating method using a hopper described in U.S. Patent No. 2,681,294, or U.S. Patent No. 2,761,418
No. 3,508,947 and No. 2,276,791 are applied by a method such as the multi-layer simultaneous coating method, and then heated to gel. The heating temperature is appropriately selected depending on the heat resistance temperature of the dye, etc., but is preferably from 10 ° C to 200 ° C, more preferably from 30 ° C to 150 ° C. The heating time depends on the heating temperature and the like, but may be about 5 minutes to 72 hours.

When iodine or the like is introduced into the electrolyte in order to generate a redox couple, it is added to the above-mentioned electrolyte solution, and after the formation of the electrolyte layer, it is placed in a closed container together with the iodine and diffused into the electrolyte. A method or the like can be adopted. In addition, iodine or the like can be introduced into the electrolyte layer when the photoelectric conversion element is assembled by a method of applying or vapor-depositing a counter electrode described later.

[2] Photoelectric Conversion Element The photoelectric conversion element of the present invention is obtained by laminating a conductive support, a photosensitive layer, a charge transfer layer containing the aforementioned gel electrolyte, and a counter electrode in this order. Preferably, as shown in FIG. 1, a conductive support 10, a photosensitive layer 20, a charge transfer layer 30, and a counter electrode 40 are laminated in this order, and the conductive support layer 10 is composed of a base material 11 and a conductive layer 12. The photosensitive layer 20 is composed of the semiconductor fine particles 21 sensitized by the dye 22 and the gel electrolyte 30 filled in the space between the semiconductor fine particles 21. Further, as shown in FIG. 2, a substrate 41 on which a conductive layer 42 is formed may be used as the counter electrode 40. At the boundaries of the respective layers (for example, the boundary between the conductive layer 12 and the photosensitive layer 20 of the conductive support, the boundary between the photosensitive layer 20 and the charge transfer layer 30, the boundary between the charge transfer layer 30 and the counter electrode 40, etc.) May be mutually diffused and mixed. The composition and structure of each layer will be described below in detail.

(I) Charge Transfer Layer The charge transfer layer is a layer having a function of replenishing oxidized dyes in the photosensitive layer with electrons. Although the gel electrolyte of the present invention is used for the charge transfer layer, a solid electrolyte or a hole transport material can be used in combination.

In order to form the charge transfer layer, an electrolyte solution may be applied on the photosensitive layer by a casting method, a coating method, an immersion method, an impregnation method, or the like, and then gelled by a heating reaction in the same manner as described above. According to a preferred embodiment, as shown in FIG. 1, a solution containing more electrolyte than the amount that completely fills the voids in the photosensitive layer 20 is applied, so that the resulting gel electrolyte layer is substantially a conductive support. Counter electrode 40 from boundary with conductive layer 12
It can be said that it exists between the borders. Here, assuming that the gel electrolyte layer existing between the boundary with the photosensitive layer 20 containing the dye-sensitized semiconductor and the boundary with the counter electrode 40 is the charge transfer layer 30,
The thickness is preferably from 0.001 to 200 μm, more preferably from 0.1 to 100 μm. If the charge transfer layer 30 is thinner than 0.001 μm, the semiconductor fine particles 21 in the photosensitive layer may come into contact with the counter electrode 40. If the charge transfer layer 30 is thicker than 200 μm, the charge transfer distance becomes too large, and the resistance of the element increases. The thickness (substantially equal to the thickness of the gel electrolyte) of the photosensitive layer 20 and the charge transfer layer 30 is preferably 0.1 to 300 μm, more preferably 1 to 130 μm.

(II) Photosensitive Layer The photosensitive layer is a layer having a semiconductor, and has a role of absorbing electrons and separating charges by generating light to generate electrons and holes. As shown in FIG. 1, the photosensitive layer is preferably a layer 20 having a structure in which a gel electrolyte is filled in voids of a layer of semiconductor fine particles 21 sensitized by the dye 22 (the dye 22 is adsorbed and carried). In the case of FIG. 1, the incident light excites the dyes 22 and the like, and the high-energy electrons in the excited dyes 22 and the like generate semiconductor fine particles.
Passed through the conduction band of 21 and further diffused into the conductive support 10
To reach. At this time, molecules such as the dye 22 are oxidized. In the photoelectrochemical cell, the electrons in the conductive support 10 return to an oxidant such as the dye 22 through the counter electrode 40 and the charge transfer layer while working in an external circuit, and the dye 22 is regenerated. Semiconductor fine particles and dyes that can be preferably used for the photosensitive layer will be described in detail below.

(A) Semiconductor fine particles Semiconductor fine particles act as a negative electrode of a photoelectrochemical cell.
The dye-sensitized semiconductor fine particles are so-called photoconductors,
It plays a role of absorbing light to separate charges and generate electrons and holes. In the dye-sensitized semiconductor fine particles, light absorption and the resulting generation of electrons and holes mainly occur in the dye, and the semiconductor fine particles have a role of receiving and transmitting the electrons.

Examples of the semiconductor fine particles include simple semiconductors such as silicon and germanium, III-V compound semiconductors, metal chalcogenides (eg, oxides, sulfides, selenides, etc.), and compounds having a perovskite structure (eg, titanate) Strontium, calcium titanate, sodium titanate, barium titanate, potassium niobate, etc.) 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 and silver. , Antimony, bismuth sulfide, cadmium, lead selenide,
And cadmium telluride. Other compound semiconductors include phosphides such as zinc, gallium, indium and cadmium, gallium arsenide, copper-indium-selenide, copper-indium-sulfide and the like.

Preferred specific examples of the semiconductor used in the present invention
Is Si, TiO_Two, SnO_Two, Fe_TwoO_Three, WO_Three, ZnO, Nb_TwoO_Five, CdS, Z
nS, PbS, Bi_TwoS_Three, CdSe, CdTe, GaP, InP, GaAs, CuIn
S_Two, CuInSe_TwoAnd more preferably TiO_Two, ZnO, Sn
O_Two, Fe_TwoO_Three, WO_Three, Nb_TwoO_Five, CdS, PbS, CdSe, InP, GaA
s, CuInS_Two, CuInSe_TwoAnd particularly preferably, TiO_TwoAlso
Is Nb _TwoO_FiveAnd most preferably TiO_TwoIt is.

The semiconductor used in the present invention may be single crystal or polycrystal. From the viewpoint of conversion efficiency, a single crystal is preferable,
Polycrystal is preferred from the viewpoints of production cost, securing of raw materials, energy payback time and the like.

The particle size of the semiconductor fine particles is generally on the order of nm to μm, but the average particle size of the primary particles obtained from the diameter when the projected area is converted into a circle is preferably from 5 to 200 nm, and from 8 to 200 nm. 100 nm is more preferred. The average particle size of the semiconductor fine particles (secondary particles) in the dispersion is preferably 0.01 to 100 μm.

Two or more types of fine particles having different particle size distributions may be mixed. In this case, the average size of the small particles is 5 nm.
It is preferred that: For the purpose of improving the light capture rate by scattering incident light, semiconductor particles having a large particle size, for example, about 300 nm may be mixed.

As a method for producing semiconductor fine particles, Sakuhana Shizuo's "Sol-Gel Method Science" Agne Shofusha (1998), Technical Information Association "Sol-Gel Method for Thin Film Coating" (1995 ), Tadao Sugimoto, "Synthesis of Monodisperse Particles and Size Morphology Control by New Synthetic Gel-Sol Method", "Materia", Vol. 35, No. 9, 1012-
The gel-sol method described on page 1018 (1996) is preferred. Further, a method of producing an oxide by high-temperature hydrolysis of a chloride in an oxyhydrogen salt developed by Degussa is also preferable.

When the semiconductor fine particles are titanium oxide, any of the above-mentioned sol-gel method, gel-sol method, and high-temperature hydrolysis method in chloride oxyhydrogen salt are preferred. Applied Technology "Gihodo Publishing (1997)
The sulfuric acid method and the chlorine method described in (1) can also be used. Furthermore, as a sol-gel method, Barb et al., Journal of American Ceramic Society, No. 80
Vol. 12, No. 3, pp. 3157-3171 (1997),
"Chemical Materials", Burnside, 10th
Vol. 9, No. 9, pages 2419 to 2425 are also preferable.

In order to coat the semiconductor fine particles on the conductive support, in addition to the method of applying a dispersion or colloid solution of the semiconductor fine particles on the conductive support, the above-mentioned sol-gel method or the like is used. Can also. In consideration of mass production of photoelectric conversion elements, physical properties of semiconductor fine particle liquid, flexibility of a conductive support, and the like, a wet film forming method is relatively advantageous. As a wet film forming method, a coating method and a printing method are typical.

As a method of preparing a dispersion of semiconductor fine particles, in addition to the above-mentioned sol-gel method, a method of grinding in a mortar, a method of dispersing while pulverizing using a mill, or a method of preparing a solvent when synthesizing a semiconductor. A method of precipitating fine particles in the solution and using it as it is, may be mentioned.

Examples of the dispersion medium include water and various organic solvents (eg, methanol, ethanol, isopropyl alcohol, dichloromethane, acetone, acetonitrile, ethyl acetate, etc.). At the time of dispersion, a polymer, a surfactant, an acid, a chelating agent, or the like may be used as a dispersing aid, if necessary.

The application method includes a roller method and a dip method as an application system, an air knife method and a blade method as a metering system, and a method in which application and metering can be performed in the same part.
No. 589, the wire bar method disclosed in U.S. Pat.
The slide hopper method, extrusion method, curtain method and the like described in JP-A Nos. 94, 2761419 and 2761791 are preferable. As a general-purpose machine, a spin method or a spray method is also preferable. As the wet printing method, intaglio printing, rubber printing, screen printing and the like are preferable, including three major printing methods of letterpress, offset and gravure. From these, a preferable film forming method is selected according to the liquid viscosity and the wet thickness.

The viscosity of the dispersion of semiconductor fine particles is greatly affected by the type and dispersibility of the semiconductor fine particles, the type of solvent used, and additives such as a surfactant and a binder. For a high viscosity liquid (for example, 0.01 to 500 Poise), an extrusion method, a casting method, a screen printing method, or the like is preferable. For a low-viscosity liquid (for example, 0.1 Poise or less), a slide hopper method, a wire bar method, or a spin method is preferable, and a uniform film can be formed. If a certain amount of coating is used, application by the extrusion method is possible even in the case of a low-viscosity liquid. Thus, the viscosity of the coating solution, the amount of coating, the support,
A wet film forming method may be appropriately selected according to the coating speed and the like.

The layer of semiconductor fine particles is not limited to a single layer, but a multi-layer coating of a dispersion of semiconductor fine particles having different particle diameters, or a coating layer containing semiconductor fine particles of different types (or different binders and additives) may be formed in multiple layers. It can also be applied. Multilayer coating is effective even when the film thickness is insufficient by one coating. The extrusion method or slide hopper method is suitable for multi-layer coating. In the case of multi-layer coating, multi-layer coating may be performed at the same time, or several to dozens of times may be sequentially applied. Furthermore, a screen printing method can also be preferably used in the case of successive coating.

In general, as the thickness of the semiconductor fine particle layer (same as the thickness of the photosensitive layer) becomes larger, the amount of dye carried per unit projected area increases, so that the light capture rate increases, but the diffusion distance of generated electrons increases. Therefore, the loss due to charge recombination also increases. Therefore, the preferred thickness of the semiconductor fine particle layer is
It is 0.1-100 μm. When used in a photoelectrochemical cell, the thickness of the semiconductor fine particle layer is preferably 1 to 30 μm, and 2 to 25 μm.
Is more preferred. The coating amount per support 1 m ² of the semiconductor fine particles is preferably 0.5~400g, 5~100g is more preferable.

After coating the semiconductor fine particles on the conductive support, the semiconductor fine particles are brought into electronic contact with each other,
Heat treatment is preferably performed to improve the strength of the coating film and the adhesion to the support. A preferred heating temperature range is from 40 ° C to less than 700 ° C, more preferably from 100 ° C to 600 ° C. The heating time is about 10 minutes to 10 hours. When a support having a low melting point or softening point such as a polymer film is used, high-temperature treatment is not preferable because it causes deterioration of the support. Further, it is preferable that the temperature of the shell is as low as possible from the viewpoint of cost. The lowering of the temperature can be attained by the above-mentioned combined use of small semiconductor particles of 5 nm or less, heat treatment in the presence of a mineral acid, and the like.

For the purpose of increasing the surface area of the semiconductor fine particles after the heat treatment, increasing the purity in the vicinity of the semiconductor fine particles, and increasing the efficiency of electron injection from the dye to the semiconductor particles, for example, chemical plating using an aqueous solution of titanium tetrachloride or trichloride. Electrochemical plating using an aqueous solution may be performed.

The semiconductor fine particles preferably have a large surface area so that many dyes can be adsorbed. Therefore, the surface area in a state where the layer of semiconductor fine particles is coated on the support is preferably 10 times or more the projected area,
Further, it is preferably 100 times or more. The upper limit is not particularly limited, but is usually about 1000 times.

(B) Dye The dye used in the photosensitive layer is preferably a metal complex dye, a phthalocyanine dye or a methine dye. Two or more dyes can be mixed in order to widen the wavelength range of photoelectric conversion as much as possible and to increase the conversion efficiency. The dyes to be mixed and their proportions can be selected so as to match the wavelength range and intensity distribution of the desired light source. These dyes are suitable for interlocking to the surface of the semiconductor particles.
group). Preferred linking groups include a COOH group, a SO ₃ H group, a cyano group, a —P (O) (OH) ₂ group, a —O
P (O) (OH) ₂ groups or chelating groups having π conductivity such as oximes, dioximes, hydroxyquinolines, salicylates and α-ketoenolates. Among them, a COOH group, -P (O) (OH) ₂ group, and -OP (O) (OH) ₂ group are particularly preferable. These groups may form a salt with an alkali metal or the like, or may form an intramolecular salt. In the case of a polymethine dye, if the methine chain contains an acidic group as in the case of forming a squarylium ring or a croconium ring, this portion may be used as a bonding group.

The dyes preferably used in the photosensitive layer will be specifically described below. If the dye is a metal complex dye, a ruthenium complex dye are preferred, and the following formula (III): (A ₁₎ dyes represented by _{p RuB a B b B c (} III) are preferred. However, p is 0-2, preferably 2. Ru represents ruthenium. A ₁
Is at least one ligand selected from the group consisting of Cl, SCN, H ₂ O, Br, I, CN, NCO and SeCN. B _a , B _b , and B _c are each independently at least one organic ligand selected from the group consisting of B-1 to B-8 below,
They may be the same or different.

[0082]

Embedded image

Here, _Ra is a hydrogen atom, a halogen atom,
Represents a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted aralkyl group having 7 to 12 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 12 carbon atoms. The alkyl part of the alkyl group and the aralkyl group may be linear or branched, and the aryl group and the aryl part of the aralkyl group may be monocyclic or polycyclic (condensed ring, ring assembly).

Examples of the ruthenium complex dyes include, for example, US Pat. Nos. 4,492,721, 4,845,537, 5,084,365 and 5,350,644.
And complex dyes described in JP-A Nos. 5463057 and 5525440 and JP-A-7-249790.

Preferred specific examples of the metal complex dye are shown below, but the present invention is not limited thereto.

[0086]

Embedded image

[0087]

Embedded image

[0088]

Embedded image

When the dye is a methine dye, the following formula (I
Dyes represented by formula (V), formula (V), formula (VI) or formula (VII) are preferred.

(1) Dye represented by formula (IV)

Embedded image However, each hydrogen atom is R _b and R _f, an alkyl group, an aryl group or a heterocyclic group, R _c to R _e each represent a hydrogen atom or a substituent. R _{b to} R _f may combine with each other to form a ring. X ₁₁ and X ₁₂ each represent nitrogen, oxygen, sulfur, selenium, or tellurium. n ₁₁ and n ₁₃ are each 0
2 represents an integer, and n ₁₂ represents an integer of 1 to 6. Formula (IV)
The compound represented by may have a counter ion depending on the charge of the whole molecule.

The above alkyl group, aryl group and heterocyclic group may have a substituent. The alkyl group may be linear or branched, and the aryl group and the heterocyclic group may be monocyclic or polycyclic (condensed ring, ring assembly). The ring formed by R _{b to} R _f may have a substituent, and may be a single ring or a condensed ring.

(2) Dye represented by formula (V)

Embedded image However, Z _a represents a non-metallic atomic group necessary for forming a nitrogen-containing heterocyclic ring. R _g is an alkyl group or an aryl group. Q _a represents a methine group or a polymethine group necessary for the compound represented by the formula (V) to form a methine dye. X ₁₃
Represents a charge-balancing counter ion, n ₁₄ represents the equivalent of a charge-balancing counter ion X ₁₃ required to neutralize the charge of the molecule,
Number 10

[0093] nitrogen-containing heterocyclic ring formed by the Z _a may have a substituent, may be a condensed ring may be a single ring. The alkyl group and the aryl group may have a substituent, the alkyl group may be linear or branched, and the aryl group may be monocyclic or polycyclic (condensed ring, ring assembly).
May be.

Among the dyes represented by the formula (V), the following formula
Dyes represented by (Va) to (Vd) are preferred.

Embedded image However, R _{11 to} R ₁₅ , R _{21 to} R ₂₄ , R _{31 to} R ₃₃ , and R _{41 to} R ₄₃ each independently represent a hydrogen atom, an alkyl group, an aryl group or a heterocyclic group, and Y ₁₁ , Y ₁₂ , Y ₂₁ , Y
₂₂ , Y _{31 to} Y ₃₅ and Y _{41 to} Y ₄₆ each independently represent oxygen, sulfur, selenium, tellurium, —CR ₁₆ R ₁₇ — or —N
R ₁₈ - represents a. R _{16 to} R ₁₈ each independently represent a hydrogen atom,
Represents an alkyl group, an aryl group or a heterocyclic group. Y ₂₃ is
O-, S-, Se-, Te- or -NR ₁₈ - represents a.

V₁₁, V₁₂, V_{twenty one}, V_{twenty two}, V₃₁And V₄₁
Each independently represents a substituent, and n ₁₅, N₃₁And n₄₁
Each independently represents an integer of 1 to 6. Formulas (V-a) to (V-d)
Is a counter ion depending on the charge of the whole molecule.
May be provided.

The above-mentioned alkyl group, aryl group and heterocyclic group may have a substituent, the alkyl group may be linear or branched, and the aryl group and heterocyclic group may be monocyclic or polycyclic ( Condensed ring, ring assembly).

Specific examples of the above polymethine dyes include:
Organi by M. Okawara, T. Kitao, T. Hirasima, M. Matuoka
c It is described in detail in Colorants (Elsevier) and the like.

(3) Dye represented by formula (VI)

Embedded image However, Q _b represents an atomic group necessary to complete a nitrogen-containing heterocyclic ring of 5- or 6-membered, Q _b may be a condensed ring, and may have a substituent.

Preferred examples of the nitrogen-containing heterocyclic ring completed by Q _b include a benzothiazole nucleus, a benzoxazole nucleus, a benzoselenazole nucleus, a benzotellurazole nucleus,
2-quinoline nucleus, 4-quinoline nucleus, benzimidazole nucleus,
Thiazoline nucleus, indolenine nucleus, oxadiazole nucleus,
A thiazole nucleus, an imidazole nucleus, more preferably a benzothiazole nucleus, a benzoxazole nucleus,
Benzimidazole nucleus, benzoselenazole nucleus, 2-quinoline nucleus, 4-quinoline nucleus, indolenine nucleus, particularly preferably benzothiazole nucleus, benzoxazole nucleus,
They are a 2-quinoline nucleus, a 4-quinoline nucleus and an indolenine nucleus.
Examples of the substituent on the nitrogen-containing hetero ring include a carboxylic acid group, a phosphonic acid group, a sulfonic acid group, and a halogen atom (F, Cl, B
r, I), a cyano group, an alkoxy group (e.g., methoxy, ethoxy, methoxyethoxy), an aryloxy group (e.g., phenoxy), an alkyl group (methyl, ethyl, cyclopropyl, cyclohexyl, trifluoromethyl, methoxyethyl, allyl, Benzyl, etc.), alkylthio groups (methylthio, ethylthio, etc.), alkenyl groups (vinyl, 1-propenyl, etc.), aryl groups and heterocyclic groups (phenyl, thienyl, toluyl, chlorophenyl, etc.).

Z _b is an atomic group necessary for completing a 3- to 9-membered ring, and is constituted by an atom selected from a carbon atom, an oxygen atom, a nitrogen atom, a sulfur atom and a hydrogen atom.
Preferably the ring completed by Z _b is a ring skeleton is formed by 4-6 carbons, more preferably those represented by the following (a) to (e), most preferably
(A).

[0101]

Embedded image

L ₁ , L ₂ , L ₃ , L ₄ and L ₅ each independently represent a methine group which may have a substituent. As the substituent, a substituted or unsubstituted alkyl group (preferably having 1 to 12 carbon atoms, more preferably 1 to 7 carbon atoms, such as methyl, ethyl, propyl, isopropyl,
A cyclopropyl, butyl, 2-carboxyethyl, benzyl, etc.) or substituted or unsubstituted aryl group (preferably having 6 to 10 carbon atoms, more preferably 6 to 8 carbon atoms, such as phenyl, toluyl, chlorophenyl, o-
Carboxyphenyl, etc.), a heterocyclic group (eg, pyridyl,
Thienyl, furanyl, pyridyl, barbituric acid, etc.),
A halogen atom (eg, chlorine, bromine), an alkoxy group (eg, methoxy, ethoxy, etc.), an amino group (preferably having 1 to 12 carbon atoms, more preferably 6 to 12 carbon atoms, such as diphenylamino, methylphenylamino, -Acetylpiperazin-1-yl etc.), oxo group and the like. These substituents on the methine group may be linked to each other to form a ring such as a cyclopentene ring, a cyclohexene ring, a squarylium ring, or a ring with an auxochrome. N ₅₁ representing the number of -L2 = L3- is an integer of 0 to 4, preferably 0 to 3. Also represents the number of -L4 = L5-
n ₅₂ is 0 or 1.

R ₅ represents a substituent. Preferred substituents are an aromatic group (which may have a substituent) or an aliphatic group (which may have a substituent), and the aromatic group preferably has 1 to 16 carbon atoms, more preferably Is 5-6. The carbon number of the aliphatic group is preferably 1 to 10, more preferably 1 to
6. As the unsubstituted aliphatic group and aromatic group,
Examples include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, a phenyl group, and a naphthyl group.

W ₁ represents a counter ion when a counter ion is required to neutralize the charge. Whether a dye is a cation or anion, or has a net ionic charge, depends on its auxochrome and substituents. When the substituent has a dissociable group, it may dissociate and have a negative charge,
Also in this case, the charge of the whole molecule is neutralized by W ₁ .
Typical cations are inorganic or organic ammonium ions (eg, tetraalkylammonium ions, pyridinium ions, etc.) and alkali metal ions, while the anions may be either inorganic or organic anions, eg, Halogen anion (eg, fluoride ion, chloride ion, bromide ion, iodide ion, etc.), substituted arylsulfonate ion (eg, p-toluenesulfonate ion, p-chlorobenzenesulfonate ion, etc.), aryldisulfonate ion (eg, For example, 1,3-benzenedisulfonate ion, 1,5-naphthalenedisulfonic acid ion, 2,6-naphthalenedisulfonic acid ion, etc., alkyl sulfate ion (eg, methyl sulfate ion, etc.), sulfate ion, thiocyanate ion, perchlorine Acid ion, tetrafluoroborate ion, Citrate ion, acetate ion,
Trifluoromethanesulfonic acid ion and the like can be mentioned.

Further, as the charge-balancing counter ion, an ionic polymer or another dye having a charge opposite to that of the dye may be used, or a metal complex such as bisbenzene-1,2-dithiolatonickel (III) may be used. Ions may be used.

(4) Dye represented by formula (VII)

Embedded image

Wherein D is at least a tetrafunctional or more aromatic
X represents a group₁, X_TwoAre sulfur and selenium, respectively
Or CR₆₃R₆₄(However, R₆₃And R₆₄Is water
A hydrogen atom or an alkyl group. ) And the same
May be different, preferably a sulfur atom or CR₆₃R
₆₄And more preferably CR₆₃R₆₄It is. Also R ₆₁
And R₆₂Represents an alkyl group or an aromatic group, respectively.
Then P₁And P_TwoIndependently form polymethine dyes
Represents the group of non-metallic atoms required to form. W_TwoMedium charge
It represents a counter ion when a counter ion is necessary for summing.

Examples of the aromatic group D having at least four or more functional groups include those derived from aromatic hydrocarbons such as benzene, naphthalene, anthracene and phenanthrene, anthraquinone, carbazole, pyridine, quinoline, thiophene, furan and xanthene. And those derived from aromatic heterocycles such as thianthrene, and these may have a substituent other than the linking portion. The aromatic group represented by D is preferably a derivative group of an aromatic hydrocarbon,
More preferably, it is a derivative group of benzene or naphthalene.

P ₁ and P ₂ each independently represent a group of nonmetallic atoms necessary to form a polymethine dye. Although any methine dye can be formed by P ₁ and P ₂ , preferred examples include a cyanine dye, a merocyanine dye, a rhodocyanine dye, a trinuclear merocyanine dye, an allopolar dye, a hemicyanine dye, and a styryl dye. Cyanine dyes include those in which the substituent on the methine chain forming the dye forms a squarylium ring or a croconium ring. For more information on these dyes, see FM Harmer, Heterocyclic Compounds-Cyanine and Cyanine Soybeans and Related Compounds.
Dyes and Related Compounds), John Willie
John Wiley & Sons, New York, London, 1964, D.M.
M. Sturmer), Heterocyclic Compounds-Special Topi in Heterocyclic Compounds
cs in Heterocyclic Chemistry), Chapter 18, Section 14, 4
It is described on pages 82 to 515 and the like. Cyanine dyes, merocyanine dyes and rhodocyanine dyes are described in U.S. Pat.
No. 5,340,694, pages 21 to 22, (XI), (XII) and (XIII) are preferred. Further, those having a squarylium ring in at least one methine chain portion of the polymethine dye formed by P ₁ and P ₂ are preferable,
Those having both are more preferred.

R ₆₁ and R ₆₂ are an aromatic group or an aliphatic group, and these may have a substituent. The number of carbon atoms in the aromatic group is preferably 5 to 16, more preferably 5 to 16.
~ 6. The number of carbon atoms of the aliphatic group is preferably 1 to 1.
0, more preferably 1 to 6. Examples of the unsubstituted aliphatic group and aromatic group include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, a phenyl group, and a naphthyl group.

It is preferable that at least one of R ₆₁ , R ₆₂ , P ₁ and P ₂ has an acidic group. Here, the acidic group is a substituent having a dissociable proton, and examples thereof include a carboxylic acid group, a phosphonic acid group, a sulfonic acid group, and a boric acid group, and a carboxylic acid group is preferable. Further, such an acidic group may be in a form of dissociating by releasing a proton. W ₂ has the same meaning as W _{1 in} formula (VI).

Preferred specific examples of the polymethine dyes represented by the formulas (IV) to (VII) are shown below, but the present invention is not limited thereto.

[0113]

Embedded image

[0114]

Embedded image

[0115]

Embedded image

[0116]

Embedded image

[0117]

Embedded image

[0118]

Embedded image

[0119]

Embedded image

[0120]

Embedded image

[0121]

Embedded image

[0122]

Embedded image

[0123]

Embedded image

[0124]

Embedded image

[0125]

Embedded image

[0126]

Embedded image

[0127]

Embedded image

[0128]

Embedded image

[0129]

Embedded image

[0130]

Embedded image

[0131]

Embedded image

[0132]

Embedded image

[0133]

Embedded image

The compounds represented by the formulas (IV) and (V) are described in "Heterocyclic Compounds-Cyanine Soybeans &Co.," by FM Harmer.
Related Compounds (Heterocyclic Compounds
-Cyanine Dyes and Related Compounds), John Wiley & Sons, Inc.- New York, London, 1964, DMSturmer, `` Heterocyclic Compounds-Special Topics in Heterocyclic Compounds-Special
Topics in Heterocyclic Chemistry), Chapters 18, 14
Verse, pp. 482-515, John Willy and Sons
(John Wiley & Sons)-New York, London, 197
7th year, `` Rodd's Chemistry of Carbon Compound
s) '', 2nd.Ed.vol.IV, partB, 1977, Chapter 15, Chapter 369-
P. 422, Elsevier Science Publishing Company In
c.) It can be synthesized based on the method described in New York, UK Patent No. 1,077,611, etc.

The compound represented by the formula (VI) is
The compound can be synthesized with reference to the description of nd Pigments, Vol. 21, pages 227 to 234 and the like. The compound represented by the formula (VII) is described in Ukrainskii Khimicheskii Zhurnal, No. 40
Vol. 3, No. 253-258, Dyes and Pigments, No. 21
Pp. 227-234 and the references cited in these documents.

(C) Adsorption of Dye on Semiconductor Fine Particles The dye is adsorbed on the semiconductor fine particles by immersing a conductive support having a well-dried semiconductor fine particle layer in a dye solution or by dissolving the dye solution in a semiconductor solution. A method of applying to the fine particle layer can be used. In the former case, a dipping method, a dipping method, a roller method, an air knife method, or the like can be used. In the case of the immersion method, the complex dye may be adsorbed at room temperature or may be heated and refluxed as described in JP-A-7-249790. The latter coating method includes a wire bar method, a slide hopper method, an extrusion method, a curtain method, a spin method, a spray method, and the like, and a printing method includes letterpress, offset, gravure, screen printing, and the like. The solvent can be appropriately selected according to the solubility of the dye. For example, alcohols (methanol, ethanol, t-butanol, benzyl alcohol, etc.), nitriles (acetonitrile, propionitrile, 3-methoxypropionitrile, etc.), nitromethane, halogenated hydrocarbons (dichloromethane, dichloroethane, chloroform, chlorobenzene) ), Ethers (diethyl ether, tetrahydrofuran, etc.), dimethyl sulfoxide,
Amides (N, N-dimethylformamide, N, N-dimethylacetamide, etc.), N-methylpyrrolidone, 1,3-dimethylimidazolidinone, 3-methyloxazolidinone, esters (ethyl acetate, butyl acetate, etc.) , Carbonates (diethyl carbonate, ethylene carbonate, propylene carbonate, etc.), ketones (acetone, 2-butanone, cyclohexanone, etc.), hydrocarbons (hexane, petroleum ether, benzene, toluene, etc.) and mixed solvents thereof. Can be

As for the viscosity of the solution of the dye, a high-viscosity liquid (for example, 0.01 to 500
For se), various printing methods other than the extrusion method are suitable, and for low-viscosity liquids (for example, 0.1 Poise or less), the slide hopper method, the wire bar method, or the spin method are suitable. It is possible.

As described above, the viscosity of the coating solution of the dye, the coating amount,
The method for adsorbing the dye may be appropriately selected according to the conductive support, the coating speed, and the like. The time required for dye adsorption after coating should be as short as possible in consideration of mass production.

Since the presence of unadsorbed dye causes disturbance of device performance, it is preferable to remove the dye by washing immediately after adsorption. Using a wet cleaning tank, polar solvents such as acetonitrile,
It is preferable to perform washing with an organic solvent such as an alcohol solvent. Further, in order to increase the adsorption amount of the dye, it is preferable to perform a heat treatment before the adsorption. After the heat treatment, do not return to room temperature to avoid water adsorbing on the surface of the semiconductor fine particles.
Preferably, the dye is adsorbed quickly between 40 and 80 ° C.

The total amount of the dye used is preferably from 0.01 to 100 mmol per unit surface area (1 m ² ) of the conductive support. The amount of dye adsorbed on the semiconductor fine particles is 1
It is preferably 0.01 to 1 mmol per g. By using such a dye adsorption amount, a sufficient sensitizing effect in a semiconductor can be obtained. On the other hand, if the amount of the dye is too small, the sensitizing effect becomes insufficient, and if the amount of the dye is too large, the dye not adhering to the semiconductor floats, which causes a reduction in the sensitizing effect.

For the purpose of reducing the interaction between dyes such as association, a colorless compound may be co-adsorbed on the semiconductor fine particles. Examples of the hydrophobic compound to be co-adsorbed include a steroid compound having a carboxyl group (for example, chenodeoxycholic acid). Further, an ultraviolet absorber can be used in combination.

For the purpose of accelerating the removal of excess dye, the surface of the semiconductor fine particles may be treated with an amine after adsorbing the dye. Preferred amines are pyridine,
4-tert-butylpyridine, polyvinylpyridine and the like. When these are liquids, they may be used as they are, or may be used after being dissolved in an organic solvent.

(III) Conductive Support The conductive support may be a conductive support such as metal or a conductive layer 12 containing a conductive agent on the photosensitive layer side as shown in FIG. A glass or plastic substrate 11 can be used. In the latter case, preferred conductive agents include metals (eg, platinum, gold, silver, copper, aluminum, rhodium, indium, etc.), carbon, or conductive metal oxides (indium-tin composite oxide, tin oxide doped with fluorine). And the like). Conductive layer
The thickness of 12 is preferably about 0.02 to 10 μm.

The lower the surface resistance of the conductive support, the better. A preferred range of the surface resistance is 100 Ω / □ or less, more preferably 40 Ω / □ or less. The lower limit of the surface resistance is not particularly limited, but is usually about 0.1Ω / □.

When light is irradiated from the conductive support side, it is preferable that the conductive support is substantially transparent electrochemically. Substantially transparent means that light transmittance is 10
% Or more, preferably 50% or more, particularly preferably 70% or more. As the transparent conductive support, it is preferable that a transparent conductive layer made of a conductive metal oxide is formed on the surface of a transparent substrate such as glass or plastic by coating or vapor deposition. Of these, conductive glass in which a conductive layer made of tin dioxide doped with fluorine is deposited on a transparent substrate made of low-cost soda-lime float glass is preferable. For a low-cost and flexible photoelectric conversion element or solar cell, a transparent polymer film provided with a conductive layer is preferably used. For the transparent polymer film, tetraacetyl cellulose (TA
C), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), syndioctatic polysterene (SPS), polyphenylene sulfide (PPS), polycarbonate (PC), polyarylate (PAr), polysulfone (PSF), polyester sulfone (PES), polyetherimide (PEI), cyclic polyolefin, brominated phenoxy, and the like. In order to ensure sufficient transparency, the amount of the conductive metal oxide applied is preferably 0.01 to 100 g per 1 m ² of a glass or plastic support.

It is preferable to use a metal lead for the purpose of lowering the resistance of the transparent conductive support. The material of the metal lead is preferably a metal such as aluminum, copper, silver, gold, platinum, and nickel, and particularly preferably aluminum and silver. The metal lead is preferably provided on a transparent substrate by vapor deposition, sputtering, or the like, and a transparent conductive layer made of tin oxide doped with fluorine or an ITO film is preferably provided thereon. It is also preferable to provide a metal lead on the transparent conductive layer after providing the transparent conductive layer on the transparent substrate. The decrease in the amount of incident light due to the installation of the metal leads is within 10%, more preferably 1 to 5%.

(IV) Counter electrode When the photoelectric conversion element is a photoelectrochemical cell, the counter electrode functions as a positive electrode of the photoelectrochemical cell. As the counter electrode, a substrate having a conductive layer can be used as in the case of the conductive support. However, the substrate is not necessarily required if a metal plate having sufficient strength and sealing property is used. As the conductive material used for the counter electrode, a metal (for example, platinum,
Gold, silver, copper, aluminum, rhodium, indium, etc.), carbon, or conductive metal oxide (indium-tin composite oxide, tin oxide doped with fluorine, etc.)
Is mentioned. An example of a preferred counter electrode is a metal or conductive metal oxide thin film applied or deposited on glass or plastic. The thickness of the counter electrode is not particularly limited,
3 nm to 10 μm is preferred. When the conductive layer is made of metal, its thickness is preferably 5 μm or less, more preferably in the range of 5 nm to 3 μm.

Since light may be emitted from one or both of the conductive support and the counter electrode, in order for light to reach the photosensitive layer, at least one of the conductive support and the counter electrode is substantially transparent. I just want it. From the viewpoint of improving power generation efficiency,
It is preferable that the conductive support is made transparent and light is incident from the conductive support side. In this case, the counter electrode preferably has a property of reflecting light. As such a counter electrode, glass or plastic on which a metal or a conductive oxide is deposited, or a metal thin film can be used.

The procedure for providing the counter electrode is as follows: (a) when the charge transfer layer is formed and then provided thereon; and (b) when the counter electrode is disposed on the layer of the dye-sensitized semiconductor fine particles via a spacer. Then, the space is filled with an electrolyte solution and crosslinked. In the case of (a), a conductive material is applied directly on the charge transfer layer, plated or deposited (PVD, CVD), or
The conductive layer side of a substrate having a conductive layer is attached. Also (b)
In the case of, a counter electrode is assembled and fixed via a spacer on the dye-sensitized semiconductor fine particle layer, the open end of the obtained assembly is immersed in an electrolyte solution, and the dye-sensitized semiconductor The electrolyte solution is permeated into the space between the fine particle layer and the counter electrode, and then crosslinked by heating.

(V) Other Layers A functional layer such as a protective layer or an antireflection film may be provided on one or both of the conductive support serving as an electrode and the counter electrode. When such a functional layer is formed in multiple layers, a simultaneous multilayer coating method or a sequential coating method can be used, but from the viewpoint of productivity, the simultaneous multilayer coating method is preferable. In the simultaneous multi-layer coating method, a slide hopper method or an extrusion method is suitable in consideration of productivity and uniformity of a coating film. In forming these functional layers, an evaporation method, a sticking method, or the like can be used depending on the material.

[3] Photoelectrochemical Battery The photoelectrochemical battery of the present invention is one in which the above-mentioned photoelectric conversion element is made to work in an external circuit. It is preferable that the side surface of the photoelectrochemical cell is sealed with a polymer, an adhesive, or the like in order to prevent deterioration of components and volatilization of the contents. The external circuit itself connected to the conductive support and the counter electrode via a lead may be a known one.

[0152]

The present invention will be described in more detail with reference to the following examples and comparative examples, but the present invention is not limited to the examples.

1. Preparation of Titanium Dioxide Dispersion 15 g of titanium dioxide fine particles (Degussa P-25, manufactured by Nippon Aerosil Co., Ltd.), 45 g of water and a dispersant (Aldrich, Triron X- 100) 1 g and 30 g of zirconia beads (manufactured by Nikkato) having a diameter of 0.5 mm are put in, and 1500 rpm using a sand grinder mill (manufactured by Imex).
For 2 hours. The zirconia beads were separated by filtration from the obtained dispersion. The average particle size of the titanium dioxide fine particles in the obtained dispersion was 2.5 μm. The particle size is MALVERN
It was measured by a master sizer manufactured by the company.

[0154] 2. TiO with adsorbed dye_TwoFine particle layer (electrode
Production of A) 20 mm x 20 mm conductor coated with tin oxide doped with fluorine
Electrical glass plate (Asahi Glass Co., Ltd., TCO glass-U, surface
Resistance: about 30Ω / □) and prepare both ends (ends) on the conductive layer side.
3mm width part) with adhesive tape for spacer
After that, apply the above dispersion using a glass rod on the conductive layer
did. After application of the dispersion, the adhesive tape was peeled off, and
Air dried for days. Next, this semiconductor coated glass plate is
(Yamato Scientific Co., Ltd. muffle furnace FP-32), 450
Baking for 30 minutes at ° C. Take out the semiconductor coated glass plate and cool
After rejection, the dye solution shown in Table 1 in ethanol (concentration: 3)
× 10 ^-Fourmol / L) for 3 hours. Semiconductor with dye adsorbed
Body-coated glass plate in 4-tert-butylpyridine for 15 minutes
After that, it was washed with ethanol and dried naturally. This
Dye-sensitized TiO thus obtained_TwoFine particle layer thickness is 10μm
And TiO_Two20g / m application amount of fine particles^TwoMet. Also color
The adsorption amount of element is 0.1 to 10 mmol / m depending on the type. ^TwoRange of
It was in the enclosure.

[0155] 3. Preparation of photoelectrochemical cell Using the solvents shown in Table 1, 0.5 mol / L of electrolyte salt was used.
Iodine salt of 1-methyl-3-hexylimidazolium and
A solution containing 0.05 mol / L iodine was prepared. Compound A (1-1) having two or more nitrogen-containing heterocyclic groups and compound B (2-10) having an electrophilic substituent at a molar concentration shown in Table 1 were mixed with this solution, and the mixture was mixed uniformly. An electrolyte solution was used.

On the other hand, on the dye-sensitized TiO ₂ fine particle layer formed on the conductive glass plate, a platinum thin film side of a glass plate on which platinum is vapor-deposited via a spacer is placed, and the conductive glass plate is placed. And a platinum-deposited glass plate were fixed. The open end of the obtained assembly was immersed in the above electrolyte solution, and the electrolyte solution was permeated into the dye-sensitized TiO ₂ fine particle layer by capillary action. Next, the mixture was heated at 80 ° C. for 30 minutes to perform a crosslinking reaction, thereby gelling the electrolyte. In this manner, as shown in FIG. 2, the dye-sensitized Ti is placed on the conductive layer 12 of the conductive glass plate 10.
A photoelectrochemical cell (Sample No. 1) of the present invention was obtained in which the O ₂ fine particle layer 20, the gel electrolyte layer 30, and the counter electrode composed of the platinum thin film 42 and the glass plate 41 were sequentially laminated.

By repeating the above steps except that the combination of the composition of the dye and the electrolyte was changed as shown in Table 1, the photoelectrochemical cell (sample) of the present invention having different photosensitive layers 20 and / or charge transfer layers 30 was obtained. Nos. 2-29) were obtained.

[0158]

[Table 1] Note: (1) The symbols of the dyes are the same as those described in the dye column in [2] (II) (B) above. (2) The symbol of the compound A is the same as that described in the column of the compound having two or more nitrogen-containing heterocyclic groups in the above [1] (A). (3) The symbol of compound B is the same as that described in the column of compound for two or more electrophilic substituents in the above [1] (B). (4) Solvent AN: acetonitrile. PC: propylene carbonate. DME: dimethoxyethane. NMO: 3-methyl-2-oxazolidinone.

4. Preparation of Comparative Photoelectrochemical Cells A and B (1) Comparative Photoelectrochemical Battery A An electrode A (20 mm × 20 mm) composed of a TiO ₂ fine particle layer dye-sensitized with the dye R-1 as described above was used. They were superposed on a platinum-evaporated glass plate of the same size via a spacer. Next, an electrolytic solution (a mixture of acetonitrile and 3-methyl-2-oxazolidinone in a volume ratio of 90/10, i.e., 0.05 mol / L of iodine and 0.5 mol of lithium iodide was used as a solvent in the gap between the two glass plates by using a capillary phenomenon. / L solution) to make photoelectrochemical cell A for comparison.

(2) Photoelectrochemical cell B for comparison (JP-A-9-273)
Electrolyte described in No. 52) Electrolyte was applied and impregnated on electrode A (20 mm × 20 mm) composed of a TiO ₂ fine particle layer dye-sensitized with dye R-1 as described above. The electrolyte was hexaethylene glycol methacrylate (manufactured by NOF CORPORATION).
1 g of Blemmer PE-350) and 1 g of ethylene glycol
And 20 mg of 2-hydroxy-2-methyl-1-phenyl-propan-1-one (manufactured by Ciba-Geigy Japan, Darocure 1173) as a polymerization initiator, and lithium iodide was added to the mixture.
It was obtained by dissolving 500 mg and degassing in vacuum for 10 minutes. Next, by placing the porous TiO ₂ layer impregnated with the mixed solution under reduced pressure to remove bubbles in the porous TiO ₂ layer and to promote the penetration of the monomer, the polymer was polymerized by irradiation with ultraviolet light to polymerize. a uniform gel compounds was filled into a porous TiO ₂ layer in the fine pores. The thus obtained product was exposed to an iodine atmosphere for 30 minutes to diffuse iodine into the polymer compound, and then laminated with a platinum-deposited glass plate.
I got

5. Measurement of photoelectric conversion efficiency A 500 W xenon lamp (Ushio Inc.)
Simulated sunlight containing no ultraviolet light was obtained by passing through an M1.5 filter (manufactured by Oriel) and a sharp cut filter (Kenko L-42). The light intensity was adjusted to 60 mW / cm ² .

The above-described conductive glass plate 10 of the photoelectrochemical cell
And alligator clips are connected to the platinum-deposited glass plate 40, and each alligator clip is connected to a current-voltage measuring device (Keithley).
SMU238). This was irradiated with simulated sunlight from the conductive glass plate 10 side, and the generated electricity was measured by a current / voltage measuring device. The calculated open-circuit voltage (Voc), short-circuit current density (Jsc), form factor (FF), conversion efficiency (η), and short-circuit current density and short-circuit current density during continuous irradiation for 240 hours Table 2 summarizes the reduction rates.

[0163]

[Table 2]

From the results in Table 2, it can be seen that the comparative photoelectrochemical cell A
In comparison with the photoelectrochemical cell of the present invention, it can be seen that the photoelectric conversion characteristics are less deteriorated. Also, a photoelectrochemical battery B for comparison
In comparison, it can be seen that the photoelectrochemical cell of the present invention has a high short-circuit current density and is excellent in photoelectric conversion characteristics.

[0165]

As described in detail above, the gel electrolyte of the present invention obtained by reacting a compound having two or more nitrogen-containing heterocyclic groups with a compound having two or more electrophilic substituents is used. This makes it possible to obtain a photoelectric conversion element and a photoelectrochemical cell having excellent photoelectric conversion characteristics and preventing deterioration of the characteristics over time.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view illustrating a structure of a photoelectric conversion device according to a preferred embodiment of the present invention.

FIG. 2 is a partial cross-sectional view illustrating a structure of a photoelectrochemical cell according to another preferred embodiment of the present invention.

[Explanation of symbols]

 10 conductive support 11 substrate 12 conductive layer 20 photosensitive layer 21 fine semiconductor particles 22 dye 30 gel electrolyte layer 40 counter electrode 41 ..Substrate 42 ... Conductive layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) // H01L 31/04

Claims (11)

[Claims] 1. A gel electrolyte comprising a reaction product of a compound having two or more nitrogen-containing heterocyclic groups and a compound having two or more electrophilic substituents. 2. The gel electrolyte according to claim 1, wherein
The compound having two or more nitrogen-containing heterocyclic groups is represented by the following formula:
(I): (However, Z represents a nitrogen-containing heterocyclic group, L represents an organic group, p ₁ represents the number of the nitrogen-containing heterocyclic group bonded to the organic group L, and is an integer of 2 to 8.) A gel electrolyte characterized by being represented. 3. The gel electrolyte according to claim 1, wherein the nitrogen-containing heterocyclic group is a nitrogen-containing unsaturated 5- to 6-membered ring. 4. The gel electrolyte according to claim 1, wherein the nitrogen-containing heterocyclic group is a pyridine ring or an imidazole ring. 5. The gel electrolyte according to claim 1, wherein the compound having two or more electrophilic substituents has the following formula (II): (However, Y represents an electrophilic substituent, L ′ represents an organic group, and p ₂ represents the number of the electrophilic substituent bonded to the organic group L ′, and is an integer of 2 to 8. A gel electrolyte characterized by being represented by: 6. The gel electrolyte according to claim 1, wherein the electrophilic substituent is at least one selected from the group consisting of a halogen atom, an acyloxy group and a sulfonyloxy group. Gel electrolyte. 7. The gel electrolyte according to claim 1, wherein the compound having two or more nitrogen-containing heterocyclic groups and the compound having two or more electrophilic substituents are salted. A gel electrolyte obtained by reacting in a dissolved solvent. 8. A photoelectric conversion element laminated in the order of a conductive support, a photosensitive layer, a charge transfer layer and a counter electrode, wherein the charge transfer layer contains the gel electrolyte according to any one of claims 1 to 7. Characteristic photoelectric conversion element. 9. The photoelectric conversion device according to claim 8, wherein the photosensitive layer contains semiconductor fine particles sensitized by a dye. 10. The photoelectric conversion device according to claim 8, wherein the photosensitive layer is composed of semiconductor fine particles and the gel electrolyte filled in a space between the semiconductor fine particles. element. A photoelectrochemical cell comprising the photoelectric conversion element according to any one of claims 8 to 10.