JP4620224B2 - Electrolyte composition - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrolyte composition excellent in durability and charge transporting ability, a photoelectric conversion element using such an electrolyte composition, and a photoelectrochemical cell comprising the same. Furthermore, this invention relates to the novel imidazolium compound and pyridinium compound which can be used for this electrolyte composition.
[0002]
[Prior art]
Conventionally, a liquid electrolyte obtained by dissolving an electrolyte salt in a solvent has been used as an electrolyte for electrochemical elements such as batteries, capacitors, sensors, display elements, and recording elements. However, in an electrochemical element using such a liquid electrolyte, liquid leakage may occur during long-term use or storage, resulting in lack of reliability.
[0003]
Nature, Vol. 353, pp. 737-740, 1991, U.S. Pat. No. 4927721, etc. disclose a photoelectric conversion element using a fine particle semiconductor sensitized with a dye and a photoelectrochemical cell using the same. In these cases, since the liquid electrolyte is used for the charge transfer layer, the electrolytic solution leaks or is depleted during long-term use or storage, and the photoelectric conversion efficiency may be significantly reduced or the device may not function. Is concerned.
[0004]
Under such circumstances, International Patent No. 93/20565 disclosed a photoelectric conversion element using a solid electrolyte. The Journal of Chemical Society of Japan, page 7,484 (1997), Japanese Patent Application Laid-Open No. 7-2881142, Solid State Ionics, 89,263 (1986) and Japanese Patent Application Laid-Open No. 9-27352 are solids using a crosslinked polyethylene oxide polymer compound. A photoelectric conversion element including an electrolyte was proposed. However, photoelectric conversion elements using these solid electrolytes have insufficient photoelectric conversion characteristics, particularly short-circuit current density, and in addition, durability is not sufficient.
[0005]
In addition, a method using a pyridinium salt, an imidazolium salt, a triazolium salt, or the like as an electrolyte in order to prevent leakage and depletion of the electrolyte and improve the durability of the photoelectric conversion element is disclosed (WO 95/18456, JP-A-8-259543, Electrochemistry, Vol. 65, No. 11, p. 923 (1997)). These salts are in a molten state at room temperature and are called room temperature molten salts. According to this method, since a solvent for dissolving an electrolyte such as water or an organic solvent is unnecessary or a small amount is required, the durability of the battery is improved. However, photoelectric conversion elements using these room temperature molten salts have poor photoelectric conversion efficiency.
[0006]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to provide an electrolyte composition excellent in durability and charge transporting ability, a photoelectric conversion element exhibiting excellent durability and photoelectric conversion characteristics due to the use of this electrolyte composition, and a light comprising such a photoelectric conversion element. It is to provide an electrochemical cell. Another object of the present invention is to provide novel imidazolium compounds and pyridinium compounds that can be used in electrolyte compositions.
[0007]
[Means for Solving the Problems]
As a result of diligent research in view of the above object, the present inventors have found that an electrolyte composition using a compound having a substituent containing a repeating substituted or unsubstituted ethyleneoxy group at a specific position has excellent durability and charge. The present inventors have found that it has a transport ability and have arrived at the present invention.
[0008]
That is, the electrolyte composition of the present invention has the following general formula (1):
[Chemical formula 5]
(However, R is-(CR₁R₂-CR_ThreeR_Four-O)_n-Bond (R₁~ R_FourEach independently represents a hydrogen atom or an alkyl group, and n represents an integer of 2 to 20. Q represents an atomic group that can form a 5- or 6-membered aromatic cation with a nitrogen atom, and may have a substituent,^-Represents an anion. It contains the compound represented by this. The electrolyte composition of the present invention can be suitably used for a photoelectrochemical cell.
[0009]
The photoelectric conversion element of the present invention has a conductive layer, a photosensitive layer, a charge transfer layer and a counter electrode, wherein the charge transfer layer contains the electrolyte composition of the present invention, and has excellent durability and photoelectric conversion. Show properties.
[0010]
Furthermore, the photoelectrochemical cell of the present invention comprises the above-described photoelectric conversion element of the present invention.
[0011]
In the electrolyte composition, photoelectric conversion element, and photoelectrochemical cell of the present invention, excellent durability, charge transport ability, and photoelectric conversion characteristics can be obtained by satisfying the following conditions.
[0012]
(1) Q is-(CR₁R₂-CR_ThreeR_Four-O)_n-Bond (R₁~ R_FourEach independently represents a hydrogen atom or an alkyl group, and n represents an integer of 2 to 20. ) Is preferable.
[0013]
(2) Q is preferably composed of one or more atoms selected from the group consisting of carbon atom, hydrogen atom, nitrogen atom, oxygen atom and sulfur atom.
[0014]
(3) The 5- or 6-membered ring formed by Q is particularly preferably an imidazole ring or a pyridine ring.
[0015]
(4) The compound represented by the general formula (1) is further represented by the following general formula (2) or (3):
[Chemical 6]
(However, R_FiveIs-(CR₁R₂-CR_ThreeR_Four-O)_n-Bond (R₁~ R_FourEach independently represents a hydrogen atom or an alkyl group, and n represents an integer of 2 to 20. ) Represents a substituent containing R)₆~ R_TenEach independently represents a hydrogen atom or a substituent, and X^-Represents an anion, R_Five~ R_TenTwo or more of them may be connected to each other to form a ring structure. ) Is preferred.
[0016]
(5) n is preferably an integer of 2 to 6.
[0017]
(6) -CR in the compound represented by the general formula (1)₁R₂-CR_ThreeR_Four-O-bond (R₁~ R_FourEach independently represents a hydrogen atom or an alkyl group. ) Is preferably 4-6.
[0018]
(7) X^-Is I^-, N^-(CF_ThreeSO₂)₂, BF_Four ^-, R_a-COO^-(R_aRepresents a hydrogen atom, an alkyl group, a perfluoroalkyl group or an aryl group. ), R_b-SO_Three ^-(R_bRepresents an alkyl group, a perfluoroalkyl group or an aryl group. ) Or SCN^-Preferably, I^-It is more preferable that
[0019]
(8) The electrolyte composition preferably contains an iodine salt in addition to the compound represented by the general formula (1). The cation of the iodine salt is preferably a 5- or 6-membered nitrogen-containing aromatic cation.
[0020]
(9) When the compound represented by the general formula (1) is an iodine salt, the electrolyte composition is further N^-(CF_ThreeSO₂)₂, BF_Four ^-, R_a-COO^-(R_aRepresents a hydrogen atom, an alkyl group, a perfluoroalkyl group or an aryl group. ), R_b-SO_Three ^-(R_bRepresents an alkyl group, a perfluoroalkyl group or an aryl group. ) And SCN^-It is preferable to contain a salt containing an anion selected from the group consisting of The cation of this salt is preferably a 5- or 6-membered nitrogen-containing aromatic cation.
[0021]
(10) The electrolyte composition preferably contains iodine.
[0022]
(11) The solvent content of the electrolyte composition is particularly preferably 10% by mass or less.
[0023]
(12) The photosensitive layer of the photoelectric conversion element preferably contains a fine particle semiconductor sensitized with a dye. The fine particle semiconductor is preferably composed of metal chalcogenide fine particles, and the metal chalcogenide fine particles preferably include titanium oxide fine particles. The dye is preferably a metal complex dye and / or a methine dye.
[0024]
In the electrolyte composition of the present invention, the following general formula (4):
[Chemical 7]
(However, R₄₀₁Represents a substituent and R₄₀₂~ R₄₀₅Each independently represents a hydrogen atom or a substituent, and R₄₀₁And R₄₀₂~ R₄₀₅At least one of each-(CR₁R₂-CR_ThreeR_Four-O)_n-Bond (R₁~ R_FourEach independently represents a hydrogen atom or an alkyl group, and n represents an integer of 2 to 20. ) And X_Four ^-Is I^-, Cl^-, Br^-, N^-(CF_ThreeSO₂)₂, N^-(CF_ThreeCF₂SO₂)₂, C^-(CF_ThreeSO₂)_Three, BF_Four ^-, BPh_Four ^-, PF₆ ^-, ClO_Four ^-, R_a-COO^-(R_aRepresents a hydrogen atom, an alkyl group, a perfluoroalkyl group or an aryl group. ), R_b-SO_Three ^-(R_bRepresents an alkyl group, a perfluoroalkyl group or an aryl group. ) Or SCN^-Represents R₄₀₁~ R₄₀₅Two or more of them may be connected to each other to form a ring structure. ) A novel imidazolium compound represented by the following general formula (5):
[Chemical 8]
(However, R₅₀₁Represents a substituent and R₅₀₂~ R₅₀₆Each independently represents a hydrogen atom or a substituent, and R₅₀₁And R₅₀₂~ R₅₀₆At least one of each-(CR₁R₂-CR_ThreeR_Four-O)_n-Bond (R₁~ R_FourEach independently represents a hydrogen atom or an alkyl group, and n represents an integer of 2 to 20. ) And X_Five ^-Is I^-, Cl^-, Br^-, N^-(CF_ThreeSO₂)₂, N^-(CF_ThreeCF₂SO₂)₂, C^-(CF_ThreeSO₂)_Three, BF_Four ^-, BPh_Four ^-, PF₆ ^-, ClO_Four ^-, R_a-COO^-(R_aRepresents a hydrogen atom, an alkyl group, a perfluoroalkyl group or an aryl group. ), R_b-SO_Three ^-(R_bRepresents an alkyl group, a perfluoroalkyl group or an aryl group. ) Or SCN^-Represents R₅₀₁~ R₅₀₆Two or more of them may be connected to each other to form a ring structure. A novel pyridinium compound represented by (2) can be preferably used.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
[1] Electrolyte composition
The electrolyte composition of the present invention can be used for a reaction solvent such as a chemical reaction, metal plating, a CCD (charge coupled device) camera, various photoelectric conversion devices, batteries, etc., and used for a lithium secondary battery or a photoelectrochemical battery. It is preferable to use it for a photoelectrochemical cell using a semiconductor. Hereinafter, each component of the electrolyte composition of the present invention will be described in detail.
[0026]
(A) Molten salt
The electrolyte composition of the present invention has the following general formula (1):
[Chemical 9]
The compound represented by these is contained. The compound represented by the general formula (1) is a low melting point salt, so-called molten salt. The melting point of the compound represented by the general formula (1) is preferably 100 ° C. or lower, more preferably 80 ° C. or lower, and particularly preferably 60 ° C. or lower. This compound includes a compound which is liquid at room temperature (around 25 ° C.), so-called room temperature molten salt.
[0027]
The compound represented by the general formula (1) can often be used as an electrolyte with almost no solvent, and can often be used alone as an electrolyte. Even if it is solid at room temperature, it can be made liquid by adding a small amount of a solvent, an additive or the like, and can be used as an electrolyte. Also, without adding anything, a method of dissolving by heating and permeating on the electrode, a method of permeating on the electrode using a low boiling point solvent (methanol, acetonitrile, methylene chloride, etc.), and then removing the solvent by heating It is possible to incorporate in a photoelectric conversion element by such as.
[0028]
In general formula (1), R is-(CR₁R₂-CR_ThreeR_Four-O)_n-Represents a substituent containing a bond. Where R₁~ R_FourEach independently represents a hydrogen atom or an alkyl group, and the alkyl group preferably has 1 to 4 carbon atoms. R₁~ R_FourAre each independently preferably a hydrogen atom or a methyl group, more preferably a hydrogen atom. N represents an integer of 2 to 20, preferably an integer of 2 to 6, and particularly preferably an integer of 2 to 4. When n is 1, the open-circuit voltage when used in a photoelectric conversion element is low, and when it is 21 or more, the ion transport ability (current density) is greatly reduced, which is not preferable. R may be linear, branched, or cyclic.
[0029]
As described above, the compound represented by the general formula (1) contained in the electrolyte composition of the present invention has a substituent containing a repeating substituted or unsubstituted ethyleneoxy group at a specific position. Repeated methyleneoxy groups are difficult to synthesize. In addition, when a substituent containing an alkyleneoxy group having a trimethyleneoxy group or higher methylene group is introduced into the compound represented by the general formula (1), the ion transport ability of the electrolyte composition is greatly reduced. When used in a photoelectric conversion element, the photoelectric conversion efficiency deteriorates, which is not preferable.
[0030]
In the general formula (1), Q represents an atomic group capable of forming a 5- or 6-membered aromatic cation with a nitrogen atom. Q may have a substituent, and this substituent is-(CR₁R₂-CR_ThreeR_Four-O)_n-Preferably it contains a bond. Where R₁~ R_FourEach independently represents a hydrogen atom or an alkyl group, and n represents an integer of 2 to 20. R₁~ R_FourAnd a preferred embodiment of n includes-(CR₁R₂-CR_ThreeR_Four-O)_n-Same as for binding. Note that the compound represented by the general formula (1) has a plurality of-(CR₁R₂-CR_ThreeR_Four-O)_n-If including bonds, their R₁~ R_FourAnd n may be the same or different.
[0031]
Q is preferably composed of one or more atoms selected from the group consisting of carbon atom, hydrogen atom, nitrogen atom, oxygen atom and sulfur atom.
[0032]
The 5-membered ring formed by Q is preferably an oxazole ring, thiazole ring, imidazole ring, pyrazole ring, isoxazole ring, thiadiazole ring, oxadiazole ring or triazole ring, and is an oxazole ring, thiazole ring or imidazole ring. Is more preferable, and an imidazole ring is particularly preferable. The 6-membered ring formed by Q is preferably a pyridine ring, a pyrimidine ring, a pyridazine ring, a pyrazine ring or a triazine ring, and particularly preferably a pyridine ring.
[0033]
As mentioned above, the substituent on Q is-(CR₁R₂-CR_ThreeR_Four-O)_n-Preferably it contains a bond. In addition, examples of preferable substituents on Q include alkoxy groups (methoxy group, ethoxy group, etc.), cyano groups, alkoxycarbonyl groups (ethoxycarbonyl group, methoxyethoxycarbonyl group, etc.), carbonate ester groups (ethoxycarbonyloxy group, etc.) ), Amide group (acetylamino group, benzoylamino group, etc.), carbamoyl group (N, N-dimethylcarbamoyl group, N-phenylcarbamoyl group, etc.), phosphonyl group (diethylphosphonyl group, etc.), heterocyclic group (pyridyl group) Imidazolyl group, furanyl group, oxazolidinonyl group, etc.), aryloxy group (phenoxy group etc.), alkylthio group (methylthio group, ethylthio group etc.), acyl group (acetyl group, propionyl group, benzoyl group etc.), sulfonyl group (Methanesulfonyl group, benzenesulfonyl group, etc.), acyloxy Group (acetoxy group, benzoyloxy group etc.), sulfonyloxy group (methanesulfonyloxy group, toluenesulfonyloxy group etc.), aryl group (phenyl group, toluyl group etc.), aryloxy group (phenoxy group etc.), alkenyl group (vinyl) Group, 1-propenyl group, etc.), alkyl group (methyl group, ethyl group, propyl group, isopropyl group, cyclopropyl group, butyl group, 2-carboxyethyl group, benzyl group, etc.) and the like. Among these, an alkoxy group, a cyano group, a carbonate ester group, an amide group, a carbamoyl group, a phosphonyl group, a heterocyclic group, an acyl group, a sulfonyl group, an acyloxy group, a sulfonyloxy group, and an alkyl group are more preferable. Particularly preferred are groups, carbonate groups, phosphonyl groups, heterocyclic groups and alkyl groups.
[0034]
In general formula (1), X^-Represents an anion. X^-Examples of halide ions (I^-, Cl^-, Br^-Etc.), N^-(CF_ThreeSO₂)₂, N^-(CF_ThreeCF₂SO₂)₂, C^-(CF_ThreeSO₂)_Three, BF_Four ^-, BPh_Four ^-, PF₆ ^-, ClO_Four ^-, R_a-COO^-, R_b-SO_Three ^-, SCN^-Etc. X^-Is I^-, N^-(CF_ThreeSO₂)₂, BF_Four ^-, R_a-COO^-, R_b-SO_Three ^-Or SCN^-Preferably, I^-It is more preferable that That is, the compound represented by the general formula (1) is more preferably an iodine salt.
[0035]
R above_aIs a hydrogen atom, a substituted or unsubstituted alkyl group (preferably having 1 to 10 carbon atoms, which may be linear or branched, or cyclic, such as methyl group, ethylpropyl Group, butyl group, isopropyl group, pentyl group, hexyl group, octyl group, 2-ethylhexyl group, t-octyl group, decyl group, cyclohexyl group, cyclopentyl group and the like), perfluoroalkyl group (preferably having 1 to 1 carbon atoms) 10 represents, for example, a trifluoromethyl group, a pentafluoroethyl group, a heptafluoropropyl group, or the like, or a substituted or unsubstituted aryl group (preferably having 6 to 12 carbon atoms, such as a phenyl group, a tolyl group, a naphthyl group, or the like). . R_aIs more preferably an alkyl group having 1 to 10 carbon atoms or a perfluoroalkyl group, and particularly preferably a perfluoroalkyl group having 1 to 10 carbon atoms.
[0036]
R_aIn the case where is an alkyl group or an aryl group having a substituent, preferred examples of the substituent include the same as the examples of the substituent on Q. In addition, halogen atoms (fluorine, chlorine, bromine, iodine, etc.) are also preferred. More preferably, it is an alkoxy group or a halogen atom.
[0037]
R above_bIs a substituted or unsubstituted alkyl group, a perfluoroalkyl group, or a substituted or unsubstituted aryl group (above preferred examples are the above R_aThe same). R_bIs more preferably an alkyl group having 1 to 7 carbon atoms, and particularly preferably an alkyl group having 1 to 5 carbon atoms.
[0038]
R_bIn the case where is an alkyl group or an aryl group having a substituent, preferred examples of the substituent include the same as the examples of the substituent on Q. Of these, an alkoxy group is more preferable.
[0039]
R_a-COO^-And R_b-SO_Three ^-R_aOr R_bA multimer may be formed via In the case of forming a multimer, a 2- to 4-mer is preferable, and a dimer is more preferable.
[0040]
The compound represented by the general formula (1) is further represented by the general formula (2) or (3):
Embedded image
Is preferably represented by:
[0041]
In general formulas (2) and (3), R_FiveIs synonymous with R in the general formula (1), and a preferred embodiment is also the same as R. R₆~ R_TenEach independently represents a hydrogen atom or a substituent, and R₆~ R_TenPreferred examples of when is a substituent include those similar to the examples of the substituent on Q. R in general formula (2)₆~ R₉At least one of R and R in the general formula (3)₆~ R_TenAt least one of each-(CR₁R₂-CR_ThreeR_Four-O)_n-Preferably it contains a bond. R_Five~ R_TenTwo or more of them may be connected to each other to form a ring structure. This ring is preferably a 5- to 7-membered ring, more preferably a 5- or 6-membered ring. X^-Represents an anion, and a preferred example is X in the general formula (1).^-It is similar to that.
[0042]
-CR in the compound represented by the general formula (1)₁R₂-CR_ThreeR_Four-O-bond (R₁~ R_FourEach independently represents a hydrogen atom or an alkyl group. ) Is preferably 4-6.
[0043]
The compound represented by the general formula (1) may form a multimer via R or Q. The multimer to be formed is preferably a 2- to 4-mer, and more preferably a dimer.
[0044]
In the electrolyte composition of the present invention, the following general formula (4):
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Or a novel imidazolium compound represented by the following general formula (5):
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The novel pyridinium compound represented by can be preferably used.
[0045]
In general formula (4), R₄₀₁Represents a substituent and R₄₀₂~ R₄₀₅Each independently represents a hydrogen atom or a substituent, and R₄₀₁And R₄₀₂~ R₄₀₅At least one of each-(CR₁R₂-CR_ThreeR_Four-O)_n-Bond (R₁~ R_FourEach independently represents a hydrogen atom or an alkyl group, and n represents an integer of 2 to 20. )including. X_Four ^-Is I^-, Cl^-, Br^-, N^-(CF_ThreeSO₂)₂, N^-(CF_ThreeCF₂SO₂)₂, C^-(CF_ThreeSO₂)_Three, BF_Four ^-, BPh_Four ^-, PF₆ ^-, ClO_Four ^-, R_a-COO^-(R_aRepresents a hydrogen atom, an alkyl group, a perfluoroalkyl group or an aryl group. ), R_b-SO_Three ^-(R_bRepresents an alkyl group, a perfluoroalkyl group or an aryl group. ) Or SCN^-Represents. R₄₀₁~ R₄₀₅Two or more of them may be connected to each other to form a ring structure.
[0046]
In general formula (5), R₅₀₁Represents a substituent and R₅₀₂~ R₅₀₆Each independently represents a hydrogen atom or a substituent, and R₅₀₁And R₅₀₂~ R₅₀₆At least one of each-(CR₁R₂-CR_ThreeR_Four-O)_n-Bond (R₁~ R_FourEach independently represents a hydrogen atom or an alkyl group, and n represents an integer of 2 to 20. )including. X_Five ^-Is I^-, Cl^-, Br^-, N^-(CF_ThreeSO₂)₂, N^-(CF_ThreeCF₂SO₂)₂, C^-(CF_ThreeSO₂)_Three, BF_Four ^-, BPh_Four ^-, PF₆ ^-, ClO_Four ^-, R_a-COO^-(R_aRepresents a hydrogen atom, an alkyl group, a perfluoroalkyl group or an aryl group. ), R_b-SO_Three ^-(R_bRepresents an alkyl group, a perfluoroalkyl group or an aryl group. ) Or SCN^-Represents. R₅₀₁~ R₅₀₆Two or more of them may be connected to each other to form a ring structure.
[0047]
When the compound represented by the general formula (4) or (5) is used in the electrolyte composition, R₄₀₁And R₅₀₁A preferred embodiment of is the same as R in the general formula (1), and R₄₀₂~ R₄₀₅And R₅₀₂~ R₅₀₆Preferred examples of when is a substituent include those similar to the examples of the substituent on Q. R₄₀₁~ R₄₀₅2 or more of these, or R₅₀₁~ R₅₀₆Of these, the ring structure formed by linking two or more of them is preferably a 5- to 7-membered ring structure, more preferably a 5- or 6-membered ring structure.
[0048]
Specific examples of the compound represented by the general formula (1) contained in the electrolyte composition of the present invention are shown below, but the present invention is not limited thereto.
[0049]
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[0050]
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[0051]
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[0052]
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[0053]
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[0054]
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[0055]
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[0056]
When the electrolyte composition of the present invention is used for a photoelectric conversion element, the electrolyte composition preferably contains an iodine salt in addition to the compound represented by the general formula (1). The cation of the iodine salt is preferably a 5- or 6-membered nitrogen-containing aromatic cation. In particular, when the compound represented by the general formula (1) is not an iodine salt, WO 95/18456, JP-A-8-259543, Electrochemistry, Vol. 65, No. 11, page 923 (1997), etc. The known iodine salts such as pyridinium salts, imidazolium salts and triazolium salts described are preferably used in combination.
[0057]
Preferred iodine salts used in combination with the compound represented by the general formula (1) include the following general formulas (Y-a), (Y-b) and (Y-c):
Embedded image
The thing represented by either of these is mentioned.
[0058]
Q in general formula (Y-a)_y1Represents an atomic group capable of forming a 5- or 6-membered aromatic cation with a nitrogen atom. Q_y1Is preferably composed of at least one atom selected from the group consisting of carbon atom, hydrogen atom, nitrogen atom, oxygen atom and sulfur atom.
[0059]
Q_y1Is preferably an oxazole ring, thiazole ring, imidazole ring, pyrazole ring, isoxazole ring, thiadiazole ring, oxadiazole ring or triazole ring, preferably an oxazole ring, thiazole ring or imidazole ring. Is more preferable, and an oxazole ring or an imidazole ring is particularly preferable. The 6-membered ring formed by Q is preferably a pyridine ring, pyrimidine ring, pyridazine ring, pyrazine ring or triazine ring, and more preferably a pyridine ring.
[0060]
In general formula (Y-b), A_y1Represents a nitrogen atom or a phosphorus atom.
[0061]
R in general formulas (Y-a), (Y-b) and (Y-c)_y1~ R_y6Each independently represents a substituted or unsubstituted alkyl group (preferably having 1 to 24 carbon atoms, which may be linear or branched, or cyclic, such as a methyl group or an ethyl group Propyl group, isopropyl group, pentyl group, hexyl group, octyl group, 2-ethylhexyl group, t-octyl group, decyl group, dodecyl group, tetradecyl group, 2-hexyldecyl group, octadecyl group, cyclohexyl group, cyclopentyl group, etc. ), Or a substituted or unsubstituted alkenyl group (preferably having 2 to 24 carbon atoms, which may be linear or branched, such as vinyl group, allyl group, etc.), more preferably carbon An alkyl group having 2 to 18 atoms or an alkenyl group having 2 to 18 carbon atoms is preferable, and an alkyl group having 2 to 6 carbon atoms is particularly preferable. However, R in the general formula (Y-b)_y1~ R_y4Three or more of them are not simultaneously alkenyl groups.
[0062]
R in general formula (Y-b)_y1~ R_y4Two or more of them connected to each other_y1A non-aromatic ring containing may be formed. In addition, R in the general formula (Y-c)_y1~ R_y6Two or more of them may be connected to each other to form a ring structure.
[0063]
Q in general formulas (Y-a), (Y-b) and (Y-c)_y1And R_y1~ R_y6May have a substituent, and examples of preferable substituents include a halogen atom (F, Cl, Br, I, etc.), a cyano group, an alkoxy group (methoxy group, ethoxy group, etc.), an aryloxy group (phenoxy group). Etc.), alkylthio group (methylthio group, ethylthio group etc.), alkoxycarbonyl group (ethoxycarbonyl group etc.), carbonate group (ethoxycarbonyloxy group etc.), acyl group (acetyl group, propionyl group, benzoyl group etc.), sulfonyl Groups (methanesulfonyl group, benzenesulfonyl group, etc.), acyloxy groups (acetoxy group, benzoyloxy group, etc.), sulfonyloxy groups (methanesulfonyloxy group, toluenesulfonyloxy group, etc.), phosphonyl groups (diethylphosphonyl group, etc.), Amide group (acetylamino group, benzoylamino group, etc.), carbamoy Group (N, N-dimethylcarbamoyl group, etc.), alkyl group (methyl group, ethyl group, propyl group, isopropyl group, cyclopropyl group, butyl group, 2-carboxyethyl group, benzyl group, etc.), aryl group (phenyl group) , Toluyl group, etc.), heterocyclic groups (pyridyl group, imidazolyl group, furanyl group, etc.), alkenyl groups (vinyl group, 1-propenyl group, etc.) and the like.
[0064]
The iodine salt represented by the general formula (Y-a), (Y-b) or (Y-c) is Q_y1Or R_y1~ R_y6A multimer may be formed via
[0065]
When the compound represented by the general formula (1) is an iodine salt, the electrolyte composition may further contain a salt other than the iodine salt. This salt is N^-(CF_ThreeSO₂)₂, BF_Four ^-, R above_a-COO^-And R_b-SO_Three ^-And SCN^-A salt containing an anion selected from the group consisting of Above all, R_a-COO^-, R_b-SO_Three ^-Or SCN^-Is more preferable. The cation of this salt is preferably a 5- or 6-membered nitrogen-containing aromatic cation, and a preferred embodiment thereof is the same as the cation moiety of the salt represented by the general formula (Ya). In this case, it is very preferable that the aromatic cation has an ethyleneoxy group. Of course, this salt may be contained in the compound represented by the general formula (1). That is, it is also preferred to use a compound represented by the general formula (1) containing iodide ion and a compound represented by the general formula (1) containing other anions.
[0066]
When the compound represented by the general formula (1) and another salt are used in combination, the content of the compound represented by the general formula (1) is preferably 10% by mass or more based on the entire electrolyte composition. 20 to 95% by mass is more preferable. Moreover, it is preferable that content of an iodine salt is 10 mass% or more with respect to the whole electrolyte composition, and it is more preferable that it is 50-95 mass%.
[0067]
Preferable specific examples of salts other than iodine salt used together when the compound represented by the general formula (1) is an iodine salt are shown below.
[0068]
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[0069]
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[0070]
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[0071]
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[0072]
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[0073]
(B) Iodine
When using the electrolyte composition of this invention for a photoelectric conversion element, it is preferable that electrolyte composition contains an iodine. In such a case, the iodine content is preferably 0.1 to 20% by mass, and more preferably 0.5 to 5% by mass with respect to the entire electrolyte composition.
[0074]
(C) Solvent
The electrolyte composition of the present invention may contain a solvent. The solvent content of the electrolyte composition is preferably 50% by mass or less of the entire composition, more preferably 30% by mass or less, and particularly preferably 10% by mass or less.
[0075]
As the solvent, a solvent having a low viscosity and high ion mobility, a high dielectric constant and capable of increasing the effective carrier concentration, or both is preferable because it can exhibit excellent ion conductivity. Examples of such solvents include carbonate compounds (ethylene carbonate, propylene carbonate, etc.), heterocyclic compounds (3-methyl-2-oxazolidinone, etc.), ether compounds (dioxane, diethyl ether, etc.), chain ethers (ethylene glycol dialkyl ether, Propylene glycol dialkyl ether, polyethylene glycol dialkyl ether, polypropylene glycol dialkyl ether, etc.), alcohols (methanol, ethanol, ethylene glycol monoalkyl ether, propylene glycol monoalkyl ether, polyethylene glycol monoalkyl ether, polypropylene glycol monoalkyl ether, etc.), Polyhydric alcohols (ethylene glycol, propylene glycol, polyethylene glycol Polypropylene glycol, glycerin, etc.), nitrile compounds (acetonitrile, glutarodinitrile, methoxyacetonitrile, propionitrile, benzonitrile, biscyanoethyl ether, etc.), esters (carboxylic esters, phosphate esters, phosphonates, etc.), non- Examples include protic polar solvents (dimethyl sulfoxide (DMSO), sulfolane, etc.), water, and the like. These solvents may be used as a mixture of two or more.
[0076]
(D) Other
The electrolyte composition of the present invention may be used after gelation (solidification) by a technique such as addition of a polymer, addition of an oil gelling agent, polymerization of polyfunctional monomers, cross-linking reaction of the polymer, or the like.
[0077]
In the case of gelation by adding a polymer, compounds described in Polymer Electrolyte Reviews-1 and 2 (JR MacCallum and CA Vincent co-edit, ELSEVIER APPLIED SCIENCE) may be added, and polyacrylonitrile or polyvinylidene fluoride may be used. preferable.
[0078]
When gelation is performed by adding an oil gelling agent, J. Chem. Soc. Japan, Ind. Chem. Soc., 46779 (1943), J. Am. Chem. Soc., 111, 5542 (1989), J. Chem. Soc., Chem. Commun., 390 (1993), Angew Chem. Int. Ed. Engl., 35, 1949 (1996), Chem. Lett., 885, (1996), J. Chem. Soc., Chem. Commun., 545, (1997), etc. A compound can be used, and a compound having an amide structure is preferably used.
[0079]
When gelling the electrolyte composition by polymerization of polyfunctional monomers, prepare a solution from the polyfunctional monomers, polymerization initiator, electrolyte and solvent, and use methods such as casting, coating, dipping, and impregnation. A method in which a sol-like electrolyte layer is formed on an electrode carrying a dye and then gelled by radical polymerization of a polyfunctional monomer is preferred. The polyfunctional monomers are preferably compounds having two or more ethylenically unsaturated groups, such as divinylbenzene, ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol diacrylate, triethylene glycol Ethylene glycol dimethacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate and the like are preferable.
[0080]
The gel electrolyte may be formed by polymerization of a mixture containing a monofunctional monomer in addition to the above polyfunctional monomers. Monofunctional monomers include acrylic acid or α-alkyl acrylic acid (acrylic acid, methacrylic acid, itaconic acid, etc.) or esters or amides thereof (methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n- Butyl acrylate, i-butyl acrylate, t-butyl acrylate, n-pentyl acrylate, 3-pentyl acrylate, t-pentyl acrylate, n-hexyl acrylate, 2,2-dimethylbutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate 4-methyl-2-propylpentyl acrylate, cetyl acrylate, n-octadecyl acrylate, cyclohexyl acrylate, cyclopentyl acrylate, benzyl acrylate, hydroxyethyl acrylate, 2-hydroxy Propyl acrylate, 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, 2-methoxyethoxyethyl acrylate, phenoxyethyl acrylate, 3-methoxybutyl acrylate, ethyl carbitol acrylate, 2-methyl-2-nitropropyl acrylate, 2,2 , 2-trifluoroethyl acrylate, octafluoropentyl acrylate, heptadecafluorodecyl acrylate, methyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, t-pentyl methacrylate, n-octadecyl methacrylate, benzyl methacrylate, Hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-methoxyethyl methacrylate, 2-ethoxyethyl methacrylate, 2-methoxy Ethoxyethyl methacrylate, dimethylaminoethyl methacrylate, 2,2,2-trifluoroethyl methacrylate, tetrafluoropropyl methacrylate, hexafluoropropyl methacrylate, heptadecafluorodecyl methacrylate, ethylene glycol ethyl carbonate methacrylate, 2-isobornyl methacrylate, 2 -Norbornylmethyl methacrylate, 5-norbornen-2-ylmethyl methacrylate, 3-methyl-2-norbornylmethyl methacrylate, acrylamide, Ni-propylacrylamide, Nn-butylacrylamide, Nt-butylacrylamide, N, N-dimethyl Acrylamide, N-methylolacrylamide, diacetoneacrylamide, 2-acrylamido-2-methylpropanesulfonic acid, acrylamidopropyltrimethyl Ammonium chloride, methacrylamide, N-methylmethacrylamide, N-methylolmethacrylamide, etc.), vinyl esters (vinyl acetate, etc.), maleic acid or fumaric acid or esters derived therefrom (dimethyl maleate, dibutyl maleate) , Diethyl fumarate, etc.), sodium salt of p-styrenesulfonic acid, acrylonitrile, methacrylonitrile, dienes (butadiene, cyclopentadiene, isoprene, etc.), aromatic vinyl compounds (styrene, p-chlorostyrene, t-butylstyrene) , Α-methylstyrene, sodium styrenesulfonate, etc.), N-vinylformamide, N-vinyl-N-methylformamide, N-vinylacetamide, N-vinyl-N-methylacetamide, vinylsulfonic acid, sodium vinylsulfonate, Allyl sulfone Sodium acid, sodium methacryl sulfonate, vinylidene fluoride, vinylidene chloride, vinyl alkyl ethers (such as methyl vinyl ether), ethylene, propylene, butene, isobutene, N-phenylmaleimide and the like can be used.
[0081]
The weight composition of the polyfunctional monomer in the total amount of monomers is preferably 0.5 to 70% by mass, and more preferably 1.0 to 50% by mass.
[0082]
The above-mentioned monomers are commonly used in Takayuki Otsu and Masaaki Kinoshita, "Experimental Methods for Polymer Synthesis" (Chemical Doujin) and Takatsu Otsu "Lecture Polymerization Reaction Theory 1 Radical Polymerization (I)" (Chemical Doujin). Polymerization can be performed by radical polymerization which is a polymer synthesis method. The monomer for gel electrolyte used in the present invention can be radically polymerized by heating, light or electron beam, or electrochemically, and is particularly preferably radically polymerized by heating. In this case, preferably used polymerization initiators are 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), dimethyl 2,2′-azobis (2-methylpropyl). Pionate), azo initiators such as dimethyl 2,2′-azobisisobutyrate, peroxide initiators such as lauryl peroxide, benzoyl peroxide, t-butyl peroctoate, and the like. A preferable addition amount of the polymerization initiator is 0.01 to 20% by mass, and more preferably 0.1 to 10% by mass with respect to the total amount of monomers.
[0083]
The weight composition range of the monomer in the gel electrolyte is preferably 0.5 to 70% by mass. More preferably, it is 1.0-50 mass%.
[0084]
When the electrolyte composition is gelled by a polymer crosslinking reaction, it is preferable to add a polymer having a reactive group capable of crosslinking to the composition and a crosslinking agent. Preferred reactive groups are nitrogen-containing heterocycles such as pyridine ring, imidazole ring, thiazole ring, oxazole ring, triazole ring, morpholine ring, piperidine ring, piperazine ring, and the preferred crosslinking agent is a functional group capable of nucleophilic attack by the nitrogen atom. Is a compound (electrophile) having two or more of, for example, a bifunctional or higher functional alkyl halide, halogenated aralkyl, sulfonic acid ester, acid anhydride, acid chloride, isocyanate and the like.
[0085]
The electrolyte composition of the present invention includes metal iodide (LiI, NaI, KI, CsI, CaI₂Etc.), metal bromides (LiBr, NaBr, KBr, CsBr, CaBr)₂Quaternary ammonium bromide (tetraalkylammonium bromide, pyridinium bromide, etc.), metal complexes (ferrocyanate-ferricyanate, ferrocene-ferricinium ion, etc.), sulfur compounds (sodium polysulfide, alkylthiol- Alkyl disulfide etc.), viologen dye, hydroquinone-quinone, etc. may be added. These may be used as a mixture.
[0086]
In the present invention, basic compounds such as t-butylpyridine, 2-picoline, 2,6-lutidine and the like described in J. Am. Ceram. Soc., 80, (12), 3157-3171 (1997) are used. It may be added. A preferable concentration range when adding a basic compound is 0.05 to 2M.
[0087]
[2] photoelectric conversion element
The photoelectric conversion element of the present invention has a conductive layer, a photosensitive layer, a charge transfer layer, and a counter electrode, and the charge transfer layer contains the electrolyte composition of the present invention. Preferably, as shown in FIG. 1, a conductive layer 10, a photosensitive layer 20, a charge transfer layer 30, and a counter electrode conductive layer 40 are stacked in this order, and the photosensitive layer 20 is sensitized with a dye 22 and the semiconductor fine particles 21. And an electrolyte 23 filled in a gap between the two. The electrolyte 23 is composed of the same components as the material used for the charge transfer layer 30. Further, in order to give strength to the photoelectric conversion element, the substrate 50 may be provided on the conductive layer 10 side and / or the counter electrode conductive layer 40 side. In the present invention, the layer composed of the conductive layer 10 and the optionally provided substrate 50 is referred to as “conductive support”, and the layer composed of the counter electrode conductive layer 40 and the optionally provided substrate 50 is referred to as “counter electrode”. A photoelectrochemical cell is one in which this photoelectric conversion element is connected to an external circuit for work. Note that the conductive layer 10, the counter electrode conductive layer 40, and the substrate 50 in FIG. 1 may be the transparent conductive layer 10a, the transparent counter electrode conductive layer 40a, and the transparent substrate 50a, respectively.
[0088]
In the photoelectric conversion element of the present invention shown in FIG. 1, the light incident on the photosensitive layer 20 containing the semiconductor fine particles 21 sensitized by the dye 22 excites the dye 22 and the like, and the high energy in the excited dye 22 and the like. Electrons are transferred to the conduction band of the semiconductor fine particles 21 and further reach the conductive layer 10 by diffusion. At this time, the molecule such as the dye 22 is an oxidant. In the photoelectrochemical cell, electrons in the conductive layer 10 return to an oxidant such as the dye 22 through the counter electrode conductive layer 40 and the charge transfer layer 30 while working in an external circuit, and the dye 22 is regenerated. The photosensitive layer 20 functions as a negative electrode. At the boundary of each layer (for example, the boundary between the conductive layer 10 and the photosensitive layer 20, 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 conductive layer 40, etc.) They may be diffusively mixed with each other. Each layer will be described in detail below.
[0089]
(A) Conductive support
The conductive support is composed of (1) a single layer of a conductive layer or (2) two layers of a conductive layer and a substrate. If a conductive layer that can maintain sufficient strength and sealing properties is used, a substrate is not always necessary.
[0090]
In the case of (1), a conductive layer having sufficient strength as metal and having conductivity is used.
[0091]
In the case of (2), a substrate having a conductive layer containing a conductive agent on the photosensitive layer side can be used. Preferred conductive agents include metals (eg, platinum, gold, silver, copper, aluminum, rhodium, indium, etc.), carbon, conductive metal oxides (indium-tin composite oxide, tin oxide doped with fluorine, etc.), etc. Is mentioned. The thickness of the conductive layer is preferably about 0.02 to 10 μm.
[0092]
The lower the surface resistance of the conductive support, the better. The surface resistance is preferably 100Ω / □ or less, more preferably 40Ω / □ or less. The lower limit of the surface resistance is not particularly limited, but is usually about 0.1Ω / □.
[0093]
When irradiating light from the conductive support side, the conductive support is preferably substantially transparent. Substantially transparent means that the light transmittance is 10% or more. The light transmittance is preferably 50% or more, and more preferably 70% or more.
[0094]
The transparent conductive support is preferably formed by applying or vapor-depositing a transparent conductive layer made of a conductive metal oxide on the surface of a transparent substrate such as glass or plastic. Among 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. In order to obtain a flexible photoelectric conversion element or solar cell at low cost, it is preferable to use a transparent polymer film provided with a conductive layer. Transparent polymer film materials include tetraacetylcellulose (TAC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), syndioctaic polystyrene (SPS), polyphenylene sulfide (PPS), polycarbonate (PC), polyarylate ( PAr), polysulfone (PSF), polyestersulfone (PES), polyetherimide (PEI), cyclic polyolefin, brominated phenoxy and the like can be used. In order to ensure sufficient transparency, the amount of conductive metal oxide applied is 1 m of glass or plastic support.²The amount is preferably 0.01 to 100 g.
[0095]
It is preferable to use a metal lead for the purpose of reducing the resistance of the transparent conductive support. The metal lead is preferably made of a metal material such as aluminum, copper, silver, gold, platinum, or nickel. Of these, aluminum and silver are particularly preferable. It is preferable to install a metal lead on a transparent substrate by vapor deposition, sputtering, or the like, and to provide a transparent conductive layer made of tin oxide doped with fluorine, an ITO film, or the like. Moreover, it is also preferable to install 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 a metal lead is preferably suppressed to within 10%, more preferably 1 to 5%.
[0096]
(B) Photosensitive layer
In the photoelectric conversion element of the present invention, the photosensitive layer preferably contains a fine particle semiconductor sensitized with a dye. The semiconductor acts as a so-called photoconductor, absorbs light, separates charges, and generates electrons and holes. In the dye-sensitized semiconductor fine particles, light absorption and the generation of electrons and holes thereby occur mainly in the dye, and the semiconductor fine particles play a role of receiving and transmitting these electrons.
[0097]
(1) Semiconductor fine particles
Semiconductor fine particles include simple semiconductors such as silicon and germanium, III-V compound semiconductors, metal chalcogenides (eg oxides, sulfides, selenides, etc.), compounds having a perovskite structure (eg strontium titanate, calcium titanate, Sodium titanate, barium titanate, potassium niobate, etc.) can be used. The fine particle semiconductor used in the present invention is preferably composed of metal chalcogenide fine particles.
[0098]
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. Examples thereof include sulfide, cadmium or lead selenide, and cadmium telluride. Examples of other compound semiconductors include phosphides such as zinc, gallium, indium, and cadmium, gallium-arsenic or copper-indium selenides, and copper-indium sulfides.
[0099]
The semiconductor used in the present invention is preferably Si, TiO₂, SnO₂, Fe₂O_Three, WO_Three, ZnO, Nb₂O_Five, CdS, ZnS, PbS, Bi₂S_Three, CdSe, CdTe, GaP, InP, GaAs, CuInS₂Or CuInSe₂And more preferably TiO₂, SnO₂, Fe₂O_Three, WO_Three, ZnO, Nb₂O_Five, CdS, PbS, CdSe, InP, GaAs, CuInS₂Or CuInSe₂And particularly preferably TiO₂Or Nb₂O_FiveAnd most preferably TiO₂It is.
[0100]
The semiconductor used in the present invention may be single crystal or polycrystalline. Single crystals are preferable from the viewpoint of conversion efficiency, but polycrystals are preferable from the viewpoint of manufacturing cost, securing raw materials and energy payback time.
[0101]
The particle size of the semiconductor fine particles is generally on the order of nm to μm. In the present invention, the average primary particle diameter determined from the diameter when the projected area of the fine particles is converted into a circle is preferably 5 to 200 nm, and more preferably 8 to 100 nm. Moreover, it is preferable that the average particle diameter of the semiconductor fine particles (secondary particles) in the dispersion prepared for application on the conductive support is 0.01 to 100 μm.
[0102]
Two or more kinds of fine particles having different particle size distributions may be mixed. In this case, the average size of the small particles is preferably 5 nm or less. 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.
[0103]
Semiconductor fine particles are prepared by Sakuo Sakuo's "Sol-gel Method Science" Agne Jofusha (1998), Technical Information Association "Sol-gel Method Thin Film Coating Technology" (1995), etc. The sol-gel method described, Tadao Sugimoto, “Synthesis and size control of monodisperse particles by the new synthetic gel-sol method”, Materia, Vol. 35, No. 9, 1012-1018 (1996) Etc. are preferred. Further, a method of producing an oxide by hydrolyzing a chloride developed by Degussa in an oxyhydrogen salt can be preferably applied.
[0104]
When the semiconductor fine particles are titanium oxide, any of the above sol-gel method, gel-sol method, and high-temperature hydrolysis method in oxyhydrogen salt of chloride can be preferably used. "Sulfuric acid method and chlorine method described in Gihodo Publishing (1997) may be used. In addition, Barb et al., Journal of American Ceramic Society, Vol. 80, No. 12, pp. 3157-3171 (1997), Burnside et al., Chemical Materials, Vol. 10, No. 9, The method described in pages 2419 to 2425 is also preferable.
[0105]
(2) Semiconductor fine particle layer
When the semiconductor fine particles are coated on the conductive support, the above-described sol-gel method or the like can be used in addition to the method of coating the dispersion or colloidal solution of the semiconductor fine particles on the conductive support. In consideration of mass production of photoelectric conversion elements, physical properties of the semiconductor fine particle dispersion or colloid solution, flexibility of the conductive support, etc., the wet film forming method is relatively preferable. As the wet film forming method, a coating method and a printing method are typical.
[0106]
As a method for preparing a dispersion of semiconductor fine particles, the above-described sol-gel method, a method of grinding with a mortar, a method of dispersing while pulverizing using a mill, a fine particle precipitated in a solvent when synthesizing a semiconductor is used as it is. The method to use etc. are mentioned.
[0107]
As the dispersion medium, water or various organic solvents (for example, methanol, ethanol, isopropyl alcohol, dichloromethane, acetone, acetonitrile, ethyl acetate, etc.) can be used. When dispersing, a polymer, a surfactant, an acid, a chelating agent, etc. may be used as necessary as a dispersion aid.
[0108]
As preferable coating methods, application methods such as a roller method and a dip method, metering systems such as an air knife method and a blade method, a wire bar method described in Japanese Patent Publication No. 58-4589, US Pat. Nos. 2681294 and 2761419 And the method of making the metering the same part as the application such as the slide hopper method, the extrusion method, the curtain method, etc. Moreover, a spin method and a spray method are also preferable as a general purpose machine. As the wet printing method, intaglio, rubber plate, screen printing and the like can be preferably used, including the three major printing methods of letterpress, offset and gravure. A preferable film forming method may be selected from the above methods according to the liquid viscosity and the wet thickness.
[0109]
The viscosity of the semiconductor fine particle dispersion greatly depends on the type and dispersibility of the semiconductor fine particles, the type of solvent used, and additives such as surfactants and binders. In the case of a high-viscosity liquid (for example, 0.01 to 500 Poise), it is preferable to use an extrusion method, a casting method, a screen printing method, or the like. For low-viscosity liquids (for example, 0.1 Poise or less), it is preferable to use a slide hopper method, a wire bar method, or a spin method from the viewpoint of film uniformity. In addition, even if it is a low-viscosity liquid if there exists a certain amount of application | coating, the application | coating by the extrusion method is possible. Thus, a wet film forming method may be selected as appropriate according to the viscosity of the coating solution, the coating amount, the support, the coating speed, and the like.
[0110]
The semiconductor fine particle layer is not limited to a single layer, and a multilayer coating of semiconductor fine particle dispersions having different particle diameters, or a multilayer coating of layers containing different types of semiconductor fine particles (or different binders, additives, etc.) it can. Multi-layer coating is effective even when the film thickness is insufficient with a single coating. The extrusion method or slide hopper method is suitable for multilayer coating. In the case of multi-layer coating, a large number of layers may be coated at the same time, or may be sequentially overcoated several times to dozens of times. In the case of sequential overcoating, a screen printing method can also be preferably used.
[0111]
In general, the thicker the semiconductor fine particle layer (the same as the photosensitive layer thickness), the higher the amount of dye supported per unit projected area and the higher the light capture rate, but the longer the diffusion distance of the generated electrons, the higher the charge. Loss due to recombination also increases. Therefore, the preferred thickness of the semiconductor fine particle layer is 0.1 to 100 μm. In particular, when used in a photoelectrochemical cell, the thickness of the semiconductor fine particle layer is preferably 1 to 30 μm, and more preferably 2 to 25 μm. Support 1m²The amount of the applied semiconductor fine particles is preferably 0.5 to 400 g, more preferably 5 to 100 g.
[0112]
After applying the semiconductor fine particles to the conductive support, it is preferable to heat-treat the semiconductor fine particles to bring them into electronic contact with each other and improve the coating strength and the adhesion to the support. The heating temperature is preferably 40 ° C. or higher and lower than 700 ° C., more preferably 100 ° C. or higher and 600 ° C. or lower. The heating time may be about 10 minutes to 10 hours. When using a support having a low melting point or softening point such as a polymer film, heat treatment at a high temperature is not preferable because it causes deterioration of the support. Also, from the viewpoint of cost reduction, it is preferable to perform the heat treatment at as low a temperature as possible. The heat treatment temperature can be lowered by using the above-described semiconductor fine particles having a particle diameter of 5 nm or less in combination or by performing the heat treatment in the presence of a mineral acid.
[0113]
In order to increase the surface area of the semiconductor fine particles after the heat treatment, or to increase the electron injection efficiency from the dye to the semiconductor fine particles by increasing the purity near the semiconductor fine particles, for example, chemical plating treatment using titanium tetrachloride aqueous solution or titanium trichloride You may perform the electrochemical plating process using aqueous solution.
[0114]
The semiconductor fine particles preferably have a large surface area so that many dyes can be adsorbed. The surface area of the semiconductor fine particles coated on the support is preferably 10 times or more, more preferably 100 times or more the projected area. The upper limit is not particularly limited, but is usually about 1000 times.
[0115]
(3) Dye
The dye used in the photosensitive layer is preferably a metal complex dye, a phthalocyanine-based dye and / or a methine dye, and more preferably a metal complex dye and / or a methine dye. In order to widen the wavelength range of photoelectric conversion as much as possible and increase the conversion efficiency, two or more kinds of dyes may be mixed and used. Moreover, what is necessary is just to select the pigment | dye to mix and the mixing ratio according to the wavelength range and intensity distribution of a light source.
[0116]
The dye used in the present invention preferably has an appropriate interlocking group for the surface of the semiconductor fine particles. Preferred linking groups include -COOH group and -SO_ThreeH group, cyano group, -P (O) (OH)₂Group, -OP (O) (OH)₂Groups and chelating groups with π conductivity such as oximes, dioximes, hydroxyquinolines, salicylates and α-ketoenolates. -COOH group, -P (O) (OH)₂Group and -OP (O) (OH)₂The group is particularly preferred. These bonding groups may form a salt with an alkali metal or the like, or may form an internal salt. In the methine dye, if the methine chain contains an acidic group as in the case where the methine chain forms a squarylium ring or a croconium ring, this part may be used as a linking group.
[0117]
Hereinafter, preferred dyes used in the photosensitive layer will be specifically described.
[0118]
(a) Metal complex dye
The metal atom of the metal complex dye used in the present invention is preferably ruthenium Ru. As the ruthenium complex dye, for example, those described in U.S. Pat. Nos. 4,972,721, 4,684,537, 5,844,365, 5,350,644, 5,630,57, 5,525,440, and JP-A-7-249790 can be used.
[0119]
The ruthenium complex dye used in the present invention has the following general formula (I):
(A₁)_pRu (B-a) (B-b) (B-c) (I)
Is preferably represented by: In general formula (I), A₁Is Cl, SCN, H₂Represents a ligand selected from the group consisting of O, Br, I, CN, NCO and SeCN. p is an integer of 0 to 2, preferably 2. Ba, Bb, and Bc each independently represents an organic ligand selected from compounds represented by the following formulas B-1 to B-8.
Embedded image
However, R₁₁Is a hydrogen atom, a halogen atom, 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 group having 6 to 12 carbon atoms Represents an aryl group. The alkyl part of the alkyl group and aralkyl group may be linear or branched, and the aryl part of the aryl group and aralkyl group may be monocyclic or polycyclic (fused ring, ring assembly). B-a, B-b and B-c may be the same or different.
[0120]
Specific examples of preferable metal complex dyes used in the present invention are shown below, but the present invention is not limited thereto.
[0121]
Embedded image
[0122]
Embedded image
[0123]
Embedded image
[0124]
(b) Methine dye
Preferred methine dyes for use in the photosensitive layer in the invention include dyes represented by the following general formula (II), (III), (IV) or (V).
[0125]
1. Dye represented by general formula (II)
Embedded image
In general formula (II), R_{twenty one}And R_{twenty five}Each independently represents a hydrogen atom, an alkyl group, an aryl group or a heterocyclic group, and R_{twenty two}~ R_{twenty four}Each independently represents a hydrogen atom or a substituent, and R_{twenty one}~ R_{twenty five}May combine with each other to form a ring, and L₁₁And L₁₂Each independently represents a nitrogen atom, an oxygen atom, a sulfur atom, a selenium atom or a tellurium atom, n1 and n3 each independently represent an integer of 0 to 2, and n2 represents an integer of 1 to 6. The dye may have a counter ion depending on the charge of the whole molecule.
[0126]
The 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 (fused ring, ring assembly). Also R_{twenty one}~ R_{twenty five}The rings formed by bonding to each other may have a substituent, and may be a single ring or a condensed ring.
[0127]
2. Dye represented by general formula (III)
Embedded image
In general formula (III), Z_aRepresents a group of non-metallic atoms necessary to form a nitrogen-containing heterocycle, and R₃₁Represents an alkyl group or an aryl group. Q_aRepresents a methine group or polymethine group necessary for the compound represented by the general formula (III) to function as a methine dye. This dye is Q_aA multimer may be formed via X_ThreeRepresents a counter ion and X_ThreeN4 representing the number of is an integer of 0-10.
[0128]
Z above_aThe nitrogen-containing heterocycle formed by may have a substituent and may be a single ring or a condensed ring. Also R₃₁The alkyl group and aryl group represented by may have a substituent, the alkyl group may be linear or branched, and the aryl group may be monocyclic or polycyclic (fused ring, ring assembly).
[0129]
Among the dyes represented by the general formula (III), the following general formulas (III-a) to (III-d):
Embedded image
(However, R₄₁~ R₄₅, R₅₁~ R₅₄, R₆₁~ R₆₃And R₇₁~ R₇₃Each independently represents a hydrogen atom, an alkyl group, an aryl group or a heterocyclic group;_{twenty one}, L_{twenty two}, L₃₁, L₃₂, L₄₁~ L₄₅And L₅₁~ L₅₆Each independently represents an oxygen atom, a sulfur atom, a selenium atom, a tellurium atom, -CR'R "-or -NR '-(R' and R '' represent a hydrogen atom, an alkyl group, an aryl group or a heterocyclic group. Each may be the same or different.)₃₃Is O^-, S^-, Se^-, Te^-Or N^-R ′ (R ′ represents a hydrogen atom, an alkyl group, an aryl group or a heterocyclic group). Y₁₁, Y₁₂, Y_{twenty one}, Y_{twenty two}, Y₃₁And Y₄₁Each independently represents a substituent, and n5, n6 and n7 each independently represents an integer of 1 to 6. ) Is more preferable.
[0130]
The dye represented by any one of the general formulas (III-a) to (III-d) may have a counter ion according to the charge of the whole molecule. The alkyl group, aryl group and heterocyclic group of this dye may have a substituent. The alkyl group may be linear or branched. The aryl group and heterocyclic group may be monocyclic or polycyclic (condensed). Ring, ring assembly).
[0131]
Specific examples of polymethine dyes represented by the general formula (III) are described in detail in Organic Colorants (Elsevier) by M. Okawara, T. Kitao, T. Hirashima, M. Matsuoka, and the like.
[0132]
3. Dye represented by general formula (IV)
Embedded image
In general formula (IV), Q_bRepresents an atomic group necessary for forming a 5- or 6-membered nitrogen-containing heterocycle, and Z_bRepresents an atomic group necessary for forming a 3- to 9-membered ring, and L₆₁~ L₆₅Each independently represents a substituted or unsubstituted methine group. n8 is an integer of 0 to 4, preferably an integer of 0 to 3. n9 is 0 or 1. R₈₁Represents a substituent and X_FourRepresents a counter ion when a counter ion is required to neutralize the charge.
[0133]
Q_bThe nitrogen-containing heterocycle formed by may be condensed or may have a substituent. This ring is preferably a benzothiazole ring, benzoxazole ring, benzoselenazole ring, benzotelrazole ring, 2-quinoline ring, 4-quinoline ring, benzimidazole ring, thiazoline ring, indolenine ring, oxadiazole ring, thiazole Ring or imidazole ring, more preferably benzothiazole ring, benzoxazole ring, benzoselenazole ring, 2-quinoline ring, 4-quinoline ring, benzimidazole ring or indolenine ring, particularly preferably benzothiazole ring, A benzoxazole ring, a 2-quinoline ring, a 4-quinoline ring or an indolenine ring;
[0134]
Q_bExamples of the substituent of the nitrogen-containing heterocycle formed by carboxy group, phosphonyl group, sulfonyl group, halogen atom (F, Cl, Br, I, etc.), cyano group, alkoxy group (methoxy group, ethoxy group) Methoxyethoxy group), aryloxy group (phenoxy group etc.), alkyl group (methyl group, ethyl group, cyclopropyl group, cyclohexyl group, trifluoromethyl group, methoxyethyl group, allyl group, benzyl etc.), alkylthio And groups (methylthio group, ethylthio group, etc.), alkenyl groups (vinyl group, 1-propenyl group, etc.), aryl groups, heterocyclic groups (phenyl group, thienyl group, toluyl group, chlorophenyl group, etc.) and the like.
[0135]
Z_bIs preferably composed of a carbon atom, an oxygen atom, a nitrogen atom, a sulfur atom and / or a hydrogen atom. Z_bThe ring formed by is preferably a ring having a skeleton formed by 4 to 6 carbons, and more preferably the following (a) to (e):
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And (a) is most preferred.
[0136]
L₆₁~ L₆₅When has a substituent, this substituent may be a substituted or unsubstituted alkyl group (preferably having 1 to 12 carbon atoms, more preferably 1 to 7 carbon atoms, such as methyl group, ethyl group, propyl group). Group, isopropyl group, cyclopropyl group, butyl group, 2-carboxyethyl group, benzyl group, etc.), substituted or unsubstituted aryl group (preferably having 6, 8 or 10 carbon atoms, more preferably 6 or 6 carbon atoms) 8, for example, phenyl group, toluyl group, chlorophenyl group, o-carboxyphenyl group, etc., heterocyclic group (pyridyl group, thienyl group, furanyl group, barbituric acid, etc.), halogen atom (chlorine atom, bromine atom, etc.) ), Alkoxy groups (methoxy group, ethoxy group, etc.), amino groups (preferably having 1 to 12 carbon atoms, more preferably 6 to 12 carbon atoms, such as diphenyl Amino group, methylphenylamino group, 4-acetyl-piperazin-1-yl group etc.), an oxo group, and the like. These substituents may be connected to each other to form a cyclopentene ring, a cyclohexene ring, a squarylium ring, or the like, or may form a ring with an auxiliary color group.
[0137]
Substituent R₈₁Is preferably an aliphatic group (which may have a substituent) or an aromatic group (which may have a substituent). R is an aliphatic group₈₁The number of carbon atoms is preferably 1 to 10, more preferably 1 to 6. R if it is an aromatic group₈₁The number of carbon atoms is preferably 1-16, more preferably 5-6. 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.
[0138]
Whether a dye is a cation or an anion or has a net ionic charge depends on its auxiliary chromophore and substituent, and the charge of the whole molecule is counterion X_FourNeutralized by Counter ion X_FourTypical cations are inorganic or organic ammonium ions (tetraalkyl ammonium ions, pyridinium ions, etc.) and alkali metal ions. On the other hand, the anion used as a counter ion may be either an inorganic anion or an organic anion, halide ion (fluoride ion, chloride ion, bromide ion, iodide ion, etc.), substituted aryl sulfonate ion (P-toluenesulfonate ion, p-chlorobenzenesulfonate ion, etc.), aryl disulfonate ion (1,3-benzenedisulfonate ion, 1,5-naphthalenedisulfonate ion, 2,6-naphthalenedisulfonate ion, etc.) Alkyl sulfate ions (such as methyl sulfate ions), sulfate ions, thiocyanate ions, perchlorate ions, tetrafluoroborate ions, picrate ions, acetate ions, trifluoromethanesulfonate ions, and the like can be used.
[0139]
Furthermore, an ionic polymer or other dye having a charge opposite to that of the dye may be used as the charge balance counter ion, or a metal complex ion such as bisbenzene-1,2-dithiolatonickel (III) may be used. May be.
[0140]
4). Dye represented by general formula (V)
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Q in general formula (V)_cRepresents a tetravalent aromatic group, L₇₁And L₇₂Each independently represents a sulfur atom, a selenium atom or —CR′R ″ — (R ′ and R ″ each independently represents a hydrogen atom or an alkyl group, and may be the same or different). They may be different, preferably a sulfur atom or —CR′R ″ —, more preferably —CR′R ″ —. R₉₁And R₉₂Each independently represents an alkyl group or an aromatic group, Y₅₁And Y₅₂Each independently represents a group of nonmetallic atoms necessary to form a methine dye. X_FiveRepresents a counter ion.
[0141]
Q_cExamples of these include aromatic hydrocarbons such as benzene, naphthalene, anthracene and phenanthrene, and tetravalent aromatics derived from aromatic heterocycles such as anthraquinone, carbazole, pyridine, quinoline, thiophene, furan, xanthene and thianthrene. Groups. This aromatic group may have a substituent. Q_cIs preferably a group derived from an aromatic hydrocarbon, more preferably a group derived from benzene or naphthalene.
[0142]
Y₅₁And Y₅₂It is possible to form any methine dye, but it is preferable to form a cyanine dye, merocyanine dye, rhodacyanine dye, trinuclear merocyanine dye, allopolar dye, hemicyanine dye, styryl dye, and the like. Cyanine dyes include those in which a substituent on the methine chain forming the dye forms a squalium ring or a croconium ring. For more information on these dyes, see FM Harmer, “Heterocyclic Compounds—Cyanine Dyes and Related Compounds”, John Wiley & Sons, New York, London, 1964, DM Sturmer, “Heterocyclic Compounds—Special Topics in Heterocyclic Chemistry,” Chapter 18, Section 14, 482-515, etc. As the cyanine dye, merocyanine dye and rhodacyanine dye used in the present invention, those described in US Pat. No. 5,340,694, (XI), (XII) and (XIII) on pages 21-22 are preferable. The dye represented by the general formula (V) preferably has a squarylium ring in one of its methine chain moieties, and more preferably has a squarylium ring in both methine chain moieties.
[0143]
R₉₁And R₉₂Is an aromatic group or an aliphatic group, and may have a substituent. The number of carbon atoms in the case of an aromatic group is preferably 5 to 16, more preferably 5 to 6. The number of carbon atoms in the case of an aliphatic group is preferably 1 to 10, more preferably 1 to 6. R₉₁And R₉₂Examples of when is an unsubstituted aliphatic group or aromatic group include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, a phenyl group, and a naphthyl group.
[0144]
R₉₁, R₉₂, Y₅₁And Y₅₂At least one of them preferably has an acidic group. Here, the acidic group is a substituent having a dissociable proton, such as a carboxylic acid group, a phosphonic acid group, a sulfonic acid group, or a boric acid group. Among these, a carboxylic acid group is preferable. The proton on the acidic group may be dissociated.
[0145]
Specific examples (1) to (43) and S-1 to S-42 of methine dyes represented by the above general formulas (II) to (V) are shown below, but the present invention is not limited thereto. Absent.
[0146]
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[0147]
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[0148]
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[0149]
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[0150]
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[0151]
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[0152]
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[0153]
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[0154]
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[0155]
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[0156]
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[0157]
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[0158]
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[0159]
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[0160]
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[0161]
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[0162]
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[0163]
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[0164]
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[0165]
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[0166]
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[0167]
The dyes represented by the above general formula (II) or (III) are “Heterocyclic Compounds—Cyanine Dyes and Related Compounds” by FM Harmer, John Wiley & Sons, New York, London, 1964, “Heterocyclic Compounds” by DM Sturmer. -Special Topics in Heterocyclic Chemistry ", Chapter 18, Section 14, 482-515, John Wiley & Sons, New York, London, 1977," Rodd's Chemistry of Carbon Compounds ", 2nd. Ed., Vol. IV, part B, Chapter 15, pages 369 to 422, Elsevier Science Publishing Company Inc., New York, 1977, British Patent No. 1,077,611, and the like.
[0168]
The dye represented by the general formula (IV) can be synthesized with reference to the description of Dyes and Pigments, Vol. 21, pages 227 to 234, and the like. The dyes represented by the general formula (V) are Ukrainskii Khimicheskii Zhurnal, Vol. 40, No. 3, pp. 253-258, Dyes and Pigments, Vol. 21, pp. 227-234, and references cited therein. Can be synthesized with reference to
[0169]
(4) Adsorption of dye to semiconductor fine particles
In order to adsorb the dye to the semiconductor fine particles, a method of immersing a conductive support having a well-dried semiconductor fine particle layer in a dye solution or a method of applying a dye solution to the semiconductor fine particle layer can be used. In the former method, an immersion method, a dip method, a roller method, an air knife method, or the like can be used. In the case of the immersion method, the dye adsorption may be performed at room temperature, or may be performed by heating and refluxing as described in JP-A-7-249790. In the latter method, a coating method such as a wire bar method, a slide hopper method, an extrusion method, a curtain method, a spin method, or a spray method, or a printing method such as letterpress, offset, gravure, or screen printing can be used.
[0170]
The solvent used in the dye solution can be appropriately selected according to the solubility of the dye, such as alcohols (methanol, ethanol, t-butanol, benzyl alcohol, etc.), nitriles (acetonitrile, propionitrile, 3-methoxypropionitrile). ), Nitromethane, halogenated hydrocarbons (dichloromethane, dichloroethane, chloroform, chlorobenzene, etc.), ethers (diethyl ether, tetrahydrofuran, etc.), dimethyl sulfoxide, amides (N, N-dimethylformamide, N, N-dimethylaceta) ), 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, siku Lohexanone etc.), hydrocarbons (hexane, petroleum ether, benzene, toluene etc.), mixed solvents thereof and the like can be used.
[0171]
As with the formation of the semiconductor fine particle layer, in order to form a uniform film, it is appropriate to use an extrusion method or various printing methods when the dye solution is a high-viscosity liquid (for example, 0.01 to 500 Poise). In the case of a low-viscosity liquid (for example, 0.1 Poise or less), it is appropriate to use a slide hopper method, a wire bar method, or a spin method.
[0172]
As described above, the dye adsorption method may be appropriately selected according to the viscosity of the dye solution, the coating amount, the material of the conductive support, the coating speed, and the like. From the viewpoint of mass production, it is preferable to shorten the time required for dye adsorption after coating as much as possible.
[0173]
Since the presence of unadsorbed dye causes disturbance in device performance, it is preferable to remove it by washing immediately after adsorption. The washing is preferably performed in a wet washing tank using a polar solvent such as acetonitrile or an organic solvent such as an alcohol solvent. In order to increase the adsorption amount of the dye, it is preferable to perform a heat treatment before the adsorption. In order to suppress the adsorption of water on the surface of the semiconductor fine particles after the heat treatment, it is preferable to quickly adsorb the dye at 40 to 80 ° C. without returning to normal temperature.
[0174]
The total amount of dye used is the unit surface area of the conductive support (1 m²) Is preferably 0.01 to 100 mmol. Further, the adsorption amount of the dye to the semiconductor fine particles is preferably 0.01 to 1 mmol per 1 g of the semiconductor fine particles in order to obtain a sufficient sensitizing effect. If the amount of the dye adsorbed is too small, the sensitizing effect is insufficient, and if it is too much, the dye tends to float, which causes a reduction in the sensitizing effect.
[0175]
In order to increase the wavelength range of photoelectric conversion as much as possible and increase the conversion efficiency, two or more kinds of dyes may be mixed and used. In this case, it is preferable to select a dye to be mixed and a mixing ratio thereof according to the wavelength range and intensity distribution of the light source.
[0176]
For the purpose of reducing the interaction between dyes such as association, a colorless hydrophobic compound may be co-adsorbed on the semiconductor fine particles. Examples of the hydrophobic compound to be co-adsorbed include steroid compounds having a carboxyl group (for example, chenodeoxycholic acid). Moreover, you may use a ultraviolet absorber together.
[0177]
For the purpose of promoting the removal of excess dye, the surface of the semiconductor fine particles may be treated with amines after adsorbing the dye. Preferable amines include pyridine, 4-t-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.
[0178]
(C) Charge transfer layer
The charge transfer layer is a layer having a function of replenishing electrons to the oxidant of the dye. Although the electrolyte composition of the present invention is used for the charge transfer layer, a solid electrolyte or a hole transport material can be used in combination.
[0179]
In order to form a charge transfer layer comprising the electrolyte composition of the present invention, a solution of the electrolyte composition is applied on the photosensitive layer by a casting method, a coating method, a dipping method, an impregnation method, etc., and then a heating reaction is performed as necessary. It is preferable to crosslink by.
[0180]
When a charge transfer layer is formed by a coating method, an additive such as a coating property improver (leveling agent, etc.) is added to a solution of an electrolyte composition containing a molten salt, and this is applied to a spin coating method, a dip coating method, Air knife coating method, curtain coating method, roller coating method, wire bar coating method, gravure coating method, extrusion coating method using a hopper described in U.S. Pat.No. 2,681,294, U.S. Pat. Nos. 2,761,418, 3,508,947 and 2,767,791 It may be applied by a method such as a multilayer simultaneous application method described in No. 1, and then heated as necessary. The heating temperature for heating may be appropriately selected depending on the heat-resistant temperature of the dye, but is usually preferably 10 to 150 ° C, more preferably 10 to 100 ° C. Although the heating time depends on the heating temperature and the like, it is about 5 minutes to 72 hours.
[0181]
According to a preferred embodiment, a greater amount of electrolyte composition solution is applied than completely fills the voids in the photosensitive layer 20, so that the resulting electrolyte layer is substantially conductive on the conductive support as shown in FIG. It exists between the boundary with the layer 10 and the boundary with the counter electrode conductive layer 40. Here, when the 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 0.001 to 200 μm. 0.1 to 100 μm is more preferable, and 0.1 to 50 μm is particularly preferable. 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 conductive layer 40. If the charge transfer layer 30 is thicker than 200 μm, the charge transfer distance becomes too long and the resistance of the device increases. The thickness of the photosensitive layer 20 + charge transfer layer 30 (which is substantially equal to the thickness of the layer made of the electrolyte composition) is preferably 0.1 to 300 μm, more preferably 1 to 130 μm, Particularly preferred is 75 μm.
[0182]
When introducing iodine or the like into the electrolyte composition to generate a redox couple, the method of adding to the electrolyte solution described above, or placing the support on which the charge transfer layer is formed together with iodine or the like in a sealed container, A technique for diffusing the film can be used. It is also possible to introduce or deposit iodine or the like on the counter electrode into the charge transfer layer when the photoelectric conversion element is assembled.
[0183]
The water content in the charge transfer layer is preferably 10,000 ppm or less, more preferably 2,000 ppm or less, and particularly preferably 100 ppm or less.
[0184]
(D) Counter electrode
The counter electrode functions as a positive electrode when the photoelectric conversion element is a photoelectrochemical cell. Similarly to the conductive support, the counter electrode may be composed of only a counter electrode conductive layer made of a conductive material, or may be composed of a counter electrode conductive layer and a support substrate. Examples of the conductive material used for the counter conductive layer include metals (for example, platinum, gold, silver, copper, aluminum, rhodium, indium, etc.), carbon, and conductive metal oxides (indium-tin composite oxide, tin oxide with fluorine). Doped ones can be used. The support substrate used for the counter electrode is preferably a glass substrate or a plastic substrate, and the conductive material is applied or deposited on the substrate. The thickness of the counter electrode conductive layer is not particularly limited, but is preferably 3 nm to 10 μm. In particular, when the counter electrode conductive layer is made of metal, the thickness is preferably 5 μm or less, more preferably 5 nm to 3 μm.
[0185]
Since light may be irradiated from either 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. Good. From the viewpoint of improving power generation efficiency, it is preferable that the conductive support is 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 material, glass or plastic on which metal or conductive oxide is deposited, a metal thin film, or the like can be used.
[0186]
As a procedure for providing the counter electrode, (b) when the charge transfer layer is formed and then provided thereon, and (b) the counter electrode is disposed on the semiconductor fine particle layer via a spacer, and the gap is filled with the electrolyte solution. There are two cases. In the case of (a), a conductive material is directly applied, plated or vapor deposited (PVD, CVD) on the charge transfer layer, or the conductive layer side of the substrate provided with the conductive layer is attached. In the case of (b), the counter electrode is assembled and fixed on the semiconductor fine particle layer via a spacer, the open end of the obtained assembly is immersed in the electrolyte solution, and the semiconductor fine particle layer is utilized by capillary action or reduced pressure. The electrolyte is infiltrated into the gap between the electrode and the counter electrode. As in the case of the conductive support, it is preferable to use a metal lead for the purpose of reducing the resistance, particularly when the counter electrode is substantially transparent. The preferable metal lead material and installation method, the reduction in the amount of incident light due to the metal lead installation, and the like are the same as in the case of the conductive support.
[0187]
(E) Other layers
A functional layer such as a protective layer or an antireflection layer may be provided on one or both of the conductive support and the counter electrode acting as an electrode. When such a functional layer is formed in multiple layers, a simultaneous multilayer coating method or a sequential coating method can be used. From the viewpoint of productivity, the simultaneous multilayer coating method is preferable. In the simultaneous multilayer coating method, a slide hopper method and an extrusion method are preferable from the viewpoint of productivity and coating film uniformity. For the formation of the functional layer, a vapor deposition method, a bonding method, or the like can be used according to the material of the conductive support or the counter electrode.
[0188]
Further, in order to prevent a short circuit between the counter electrode and the conductive support, a dense semiconductor thin film layer may be previously applied as an undercoat layer between the conductive support and the photosensitive layer. The material of the undercoat layer is preferably TiO₂, SnO₂, Fe₂O_Three, WO_Three, ZnO and / or Nb₂O_FiveAnd more preferably TiO₂It is. The undercoat layer can be applied by the spray pyrolysis method described in Electrochimi. Acta, 40, 643-652 (1995). The thickness of the undercoat layer is preferably 5 to 1000 nm, and more preferably 10 to 500 nm.
[0189]
(F) Specific example of internal structure of photoelectric conversion element
The internal structure of the photoelectric conversion element can take various forms depending on the purpose. If roughly divided into two, a structure that allows light to enter from both sides and a structure that allows only one side are possible. 2 to 8 illustrate the internal structure of a photoelectric conversion element that can be preferably applied to the present invention.
[0190]
The structure shown in FIG. 2 is a structure in which the photosensitive layer 20 and the charge transfer layer 30 are interposed between the transparent conductive layer 10a and the transparent counter electrode conductive layer 40a, and light enters from both sides. In the structure shown in FIG. 3, the metal lead 11 is partially provided on the transparent substrate 50a, the transparent conductive layer 10a is provided thereon, and the undercoat layer 60, the photosensitive layer 20, the charge transfer layer 30, and the counter electrode conductive layer 40 are arranged in this order. Further, a support substrate 50 is arranged, and light is incident from the conductive layer side. In the structure shown in FIG. 4, a conductive layer 10 is further provided on a support substrate 50, a photosensitive layer 20 is provided via an undercoat layer 60, a charge transfer layer 30 and a transparent counter electrode conductive layer 40a are provided, and a part thereof is provided. The transparent substrate 50a provided with the metal lead 11 is disposed with the metal lead 11 side inward, and has a structure in which light enters from the counter electrode side. In the structure shown in FIG. 5, a transparent conductive layer 10a and a transparent counter electrode conductive layer 40a are provided on two transparent substrates 50a each provided with a part of metal leads 11, and an undercoat layer 60, a photosensitive layer 20, and a charge are provided between them. The movable layer 30 is interposed, and light is incident from both sides. In the structure shown in FIG. 6, a transparent conductive layer 10a is provided on a transparent substrate 50a, a photosensitive layer 20 is provided via an undercoat layer 60, a charge transfer layer 30 and a counter conductive layer 40 are provided, and a support substrate is provided thereon. 50 is a structure in which light is incident from the conductive layer side. In the structure shown in FIG. 7, a conductive layer 10 is provided on a support substrate 50, a photosensitive layer 20 is provided via an undercoat layer 60, a charge transfer layer 30 and a transparent counter electrode conductive layer 40a are provided, and a transparent substrate is provided thereon. 50a is arranged, and light is incident from the counter electrode side. In the structure shown in FIG. 8, a transparent conductive layer 10a is provided on a transparent substrate 50a, a photosensitive layer 20 is provided via an undercoat layer 60, a charge transfer layer 30 and a transparent counter electrode conductive layer 40a are provided, and a transparent layer is provided thereon. The substrate 50a is disposed, and light is incident from both sides.
[0191]
[3] Photoelectrochemical cell
The photoelectrochemical cell of the present invention is one in which the photoelectric conversion element is caused to work in an external circuit. In order to prevent deterioration of components and volatilization of the contents of the photoelectrochemical cell, it is preferable to seal the side surface with a polymer or an adhesive. The external circuit itself connected to the conductive support and the counter electrode via a lead may be a known one.
[0192]
[4] Dye-sensitized solar cell
When the photoelectric conversion element of the present invention is applied to a so-called solar battery, the structure inside the cell is basically the same as the structure of the photoelectric conversion element described above. Hereinafter, a module structure of a solar cell using the photoelectric conversion element of the present invention will be described.
[0193]
The dye-sensitized solar cell of the present invention can basically have the same module structure as a conventional solar cell module. A solar cell module generally has a structure in which cells are formed on a support substrate such as metal or ceramic and covered with a filling resin, protective glass or the like, and light is taken in from the opposite side of the support substrate. It is also possible to use a transparent material such as tempered glass as the material of the support substrate, form a cell thereon, and take in light from the transparent support substrate side. Specifically, a super straight type, substrate type or potting type module structure, a substrate integrated module structure used in an amorphous silicon solar cell, and the like are known. Also in the dye-sensitized solar cell using the photoelectric conversion element of the present invention, the module structure can be appropriately selected depending on the purpose of use, the place of use, and the environment.
[0194]
In a typical super straight type or substrate type module, cells are arranged at regular intervals between a pair of support substrates, one or both of which are transparent, and adjacent cells are connected by metal leads or flexible wiring. . Current collecting electrodes are arranged on the outer edge portion, and electric power is taken out from there. Various plastic materials such as ethylene vinyl acetate (EVA) may be interposed between the substrate and the cell in the form of a film or a filling resin for the purpose of protecting the cell and improving the current collection efficiency. In addition, when used in a place where the surface does not need to be covered with a hard material, such as a place where there is little impact from the outside, the support substrate on one side may not be installed. In this case, it is preferable that the surface protective layer is made of a transparent plastic film, or that the protective function is imparted by curing the filling resin. In order to ensure the internal sealing performance and the rigidity of the module, it is preferable that the periphery of the support substrate is fixed in a sandwich shape with a metal frame, and the support substrate and the frame are hermetically sealed with a sealing material. In addition, when a flexible material is used as a material for the support substrate, a filling material, and a sealing material, a solar cell can be formed on a curved surface.
[0195]
Super straight type solar cell module, for example, while transporting the front substrate sent out from the substrate supply device with a belt conveyor, etc., the cells are sequentially placed together with the sealing material-cell connecting lead wire, the back surface sealing material, etc. After the lamination, the back substrate or the back cover can be placed and the frame can be set on the outer edge.
[0196]
On the other hand, the substrate type solar cell module, while carrying the support substrate sent out from the substrate supply device by a belt conveyor or the like, after sequentially stacking the cells together with inter-cell connection leads, sealing material, etc. A front cover can be put on and a frame can be set on the periphery.
[0197]
An example of a substrate integrated module using the photoelectric conversion element of the present invention is shown in FIG. In the structure shown in FIG. 9, a transparent conductive layer 10a is placed on one surface of a transparent substrate 50a, and a dye-adsorbing TiO is placed on the transparent conductive layer 10a.₂A cell including a photosensitive layer 20, containing a charge transfer layer 30, and a counter electrode conductive layer 40 is modularized. An antireflection layer 70 is provided on the other surface of the substrate 50a. In the structure shown in FIG. 9, it is preferable to increase the area ratio of the photosensitive layer 20 (area ratio when viewed from the side of the substrate 50a that is the light incident surface) in order to increase the utilization efficiency of incident light.
[0198]
The module having the structure shown in FIG. 9 is a semiconductor such as selective plating, selective etching, CVD, and PVD so that a transparent conductive layer, a photosensitive layer, a charge transfer layer, a counter electrode, and the like are arranged three-dimensionally at regular intervals on a substrate. It can be obtained by patterning using process techniques, laser scribing after pattern coating or wide coating, or mechanical methods such as plasma CVM (described in Solar Energy Materials and Solar Cells, 48, p373-381) or grinding. it can. Hereinafter, other members and processes will be described in detail.
[0199]
Sealing materials include liquid EVA (ethylene vinyl acetate), film-like EVA, and vinylidene fluoride depending on purposes such as weather resistance, electrical insulation, light collection efficiency, and cell protection (impact resistance). Various materials such as a mixture of a copolymer and an acrylic resin can be used. It is preferable to use a sealing material having high weather resistance and moisture resistance between the outer edge of the module and the frame surrounding the periphery. Moreover, a transparent filler may be mixed in the sealing material to increase the strength and light transmittance.
[0200]
When fixing the sealing material on the cell, a method suitable for the physical properties of the material is used. In the case of a film-like material, it may be fixed by heat contact after roll pressurization, heat contact after vacuum pressurization, or the like. In the case of a liquid or paste-like material, various methods such as roll coating, bar coating, spray coating, and screen printing can be used.
[0201]
When a flexible material such as PET or PEN is used as the support substrate, a roll-shaped support is drawn out to form a cell thereon, and then a sealing layer can be continuously laminated by the above method. High productivity can be obtained.
[0202]
In order to increase the power generation efficiency, the surface of the substrate (generally tempered glass) on the light intake side of the module is subjected to antireflection treatment. Examples of the antireflection treatment method include a method of laminating an antireflection film and a method of coating an antireflection layer.
[0203]
In addition, it is possible to increase the utilization efficiency of incident light by processing the surface of the cell by a method such as grooving or texturing.
[0204]
In order to increase the power generation efficiency, it is most important to capture the light into the module without loss, but it is also important to reflect the light that has passed through the photosensitive layer and reached the inner side and efficiently return it to the photosensitive layer side. It is. As a method for increasing the light reflectivity, the support substrate surface is mirror-polished, and then Ag or Al or the like is vapor-deposited or plated. An alloy layer such as Al-Mg or Al-Ti is used as a reflective layer on the bottom layer of the cell There are a method of providing, a method of forming a texture structure in the lowermost layer by annealing, and the like.
[0205]
In order to increase the power generation efficiency, it is important to reduce the inter-cell connection resistance in order to suppress the internal voltage drop. As a method for connecting cells, wire bonding or conductive flexible sheet connection is generally used. However, a method of electrically connecting and fixing cells using a conductive adhesive tape or a conductive adhesive, and conductivity. A method of applying a hot melt pattern at a desired position can also be used.
[0206]
In the case of a solar cell using a flexible support such as a polymer film, cells are sequentially formed by the above-mentioned method while feeding out a roll-shaped support, cut into a desired size, and the periphery is flexible and moisture-proof. The battery body can be produced by sealing with a material. A module structure called “SCAF” described in Solar Energy Materials and Solar Cells, 48, p383-391 can also be used. Furthermore, a solar cell using a flexible support can be used by being bonded and fixed to a curved glass or the like.
[0207]
As described above in detail, solar cells having various shapes and functions can be manufactured in accordance with the purpose of use and usage environment.
[0208]
【Example】
Hereinafter, the present invention will be described in more detail with reference to specific examples, but the present invention is not limited thereto.
[0209]
1. Synthesis example of compound represented by general formula (1)
A compound represented by the general formula (1) of the present invention was synthesized using the following compounds a to h. The structure of the synthesized compound is¹Confirmed by 1 H-NMR. The water content of the synthesized compound was measured by the Karl Fischer method, and the viscosity was measured using a B-type viscometer (manufactured by Tokimec Co., Ltd.).
[0210]
Embedded image
[0211]
(A) Synthesis of 2-a
5.3 g (0.028 mol) of compound a and 7.32 g (0.03 mol) of compound b were dissolved in 12 ml of ethyl acetate and reacted for 24 hours with heating under reflux. Next, under heating under reduced pressure, ethyl acetate and excess compound b were distilled off to obtain 12 g of 2-a. The water content of the obtained 2-a was 0.1%, and the viscosity at 25 ° C. was η = 832 cp.
[0212]
(B) Synthesis of 2-b
10.0 g (0.023 mol) 2-a and 6.60 g (0.023 mol) N-lithiotrifluoromethanesulfonimide were added to 50 ml water and stirred at room temperature for 30 minutes. Next, the reaction solution was extracted with methylene chloride, concentrated, and dried at 80 ° C. under the conditions of 1 mmHg for 5 hours to obtain 8 g of 2-b as an oil. The water content of the obtained 2-b was 0.1%, and the viscosity at 25 ° C. was η = 219 cp.
[0213]
Synthesis of (C) 2-c
4.28 g (0.01 mol) 2-a and 1.95 g (0.01 mol) silver tetrafluoroborate were mixed in 25 ml water. Next, the precipitate was removed by filtration through Celite, and the water was concentrated and dried at 80 ° C. under the conditions of 1 mmHg for 5 hours to obtain 2.8 g of 2-c as an oily substance. The obtained 2-c had a water content of 0.1% and a viscosity at 25 ° C. of η = 507 cp.
[0214]
Synthesis of (D) 16-a
7.9 g (0.1 mol) of pyridine and 24.4 g (0.1 mol) of compound b were dissolved in 50 ml of ethyl acetate and allowed to react for 12 hours with heating under reflux. Next, the volatile component was distilled off under reduced pressure to obtain 30 g of 16-a. The obtained 16-a had a water content of 0.8% and a viscosity at 25 ° C. of η = 1070 cp.
[0215]
Synthesis of (E) 16-b
3.23 g (0.01 mol) of 16-a and 2.87 g (0.01 mol) of N-lithiotrifluoromethanesulfonimide were added to 20 ml of water and stirred at room temperature for 30 minutes. Next, the reaction solution was extracted with methylene chloride, and concentrated and dried to obtain 3.4 g of 16-b as an oil. The obtained 16-b had a water content of 0.8% and a viscosity at 25 ° C. of η = 366 cp.
[0216]
Synthesis of (F) 16-c
3.23 g (0.01 mol) 16-a and 1.95 g (0.01 mol) silver tetrafluoroborate were mixed in 25 ml water. Next, the precipitate was removed by filtration using a filter paper, the water was concentrated, and dried at 80 ° C. under the conditions of 1 mmHg for 5 hours to obtain 2.5 g of 16-c. The resulting compound had a water content of 1.5% and a viscosity at 25 ° C. of η = 852 cp.
[0217]
Synthesis of (G) 35-a
7.8 g of compound c and 3.0 g of paraformaldehyde were mixed and heated at 160 ° C. for 2 hours. This was purified by silica gel column chromatography (eluent: methylene chloride / methanol = 9/1) to obtain 5.3 g of compound d. Next, 0.96 g of 65% oily sodium hydride was suspended in 10 ml of toluene, and a solution of 5.3 g of compound d dissolved in 20 ml of THF was added dropwise to this suspension at 0 ° C. After the dropwise addition, the reaction solution was returned to room temperature, a solution prepared by dissolving 4.75 g of compound e in 20 ml of THF was added, and the mixture was heated to reflux for 3 hours. After completion of the reaction, the solvent was distilled off under reduced pressure, and the residue was purified by silica gel column chromatography (eluent: methylene chloride / methanol = 9/1) to obtain 3.25 g of compound f. Subsequently, 3.25 g of compound f and 2.44 g of compound b were dissolved in 10 ml of ethyl acetate and reacted for 8 hours while heating under reflux. After evaporating the solvent under reduced pressure, the residue was purified by silica gel column chromatography (eluent: methylene chloride / methanol = 9/1) and dried at 100 ° C. under 1 mmHg for 5 hours to obtain 5.0 g of 35-a. . The obtained 35-a had a water content of 0.5% and a viscosity at 25 ° C. of η = 446 cp.
[0218]
Synthesis of (H) 35-b
1.46 g of 35-a and 0.66 g of N-lithiotrifluoromethanesulfonimide were added to 50 ml of water and stirred at room temperature for 30 minutes. Next, the reaction solution is extracted with methylene chloride, concentrated, and the residue is purified by silica gel column chromatography (eluent: methylene chloride / methanol = 9/1) and dried at 80 ° C. and 1 mmHg for 6 hours. 1 g of 35-b was obtained as an oil. The obtained 35-b had a water content of 0.4% and a viscosity at 25 ° C. of η = 240 cp.
[0219]
Synthesis of (I) 35-c
3.17 g of 35-a and 0.98 g of silver tetrafluoroborate were mixed in 25 ml of water. Next, the precipitate is filtered using Celite, the water is concentrated, and the residue is purified by silica gel column chromatography (eluent: methylene chloride / methanol = 9/1), and the conditions are 6 hours at 80 ° C. and 1 mmHg. Drying gave 1.5 g of 35-c as an oil. The obtained 35-c had a water content of 1.2% and a viscosity at 25 ° C. of η = 365 cp.
[0220]
Synthesis of (J) 34-a
7 g of 65% oily sodium hydride was suspended in 10 ml of DMF, and a solution of 20 g of 3-pyridinemethanol in 20 ml of DMF was added dropwise to this solution at 0 ° C. After the dropwise addition, the reaction solution was returned to room temperature, a solution of 36 g of compound e dissolved in 20 ml of DMF was added, and the mixture was heated to reflux for 3 hours. After completion of the reaction, the solvent was distilled off under reduced pressure, and the residue was purified using a silica gel column (eluent: methylene chloride / methanol = 9/1) to obtain 16.8 g of compound h. Next, 2.44 g of compound g and 3.25 g of compound h were dissolved in 10 ml of ethyl acetate and reacted for 8 hours under heating and reflux. After the solvent was distilled off under reduced pressure, the residue was purified using a silica gel column (eluent: methylene chloride / methanol = 9/1) and dried at 100 ° C. under 1 mmHg for 5 hours to obtain 5.0 g of 34-a. It was. The obtained 34-a had a water content of 1.3% and a viscosity at 25 ° C. of η = 1400 cp.
[0221]
Synthesis of (K) 34-b
1.22 g of 34-a and 0.66 g of N-lithiotrifluoromethanesulfonimide were added to 50 ml of water and stirred at room temperature for 30 minutes. The reaction solution was extracted with methylene chloride, concentrated, and the residue was purified by silica gel column chromatography (eluent: methylene chloride / methanol = 9/1) and dried at 80 ° C. under 1 mmHg for 6 hours. 1 g of 34-b was obtained as an oil. The obtained 34-b had a water content of 0.5% and a viscosity at 25 ° C. of η = 222 cp.
[0222]
Synthesis of (L) 34-c
2.66 g of 34-a and 0.98 g of silver tetrafluoroborate were mixed in 25 ml of water. Next, the precipitate is filtered using Celite, the water is concentrated, and the residue is purified by silica gel column chromatography (eluent: methylene chloride / methanol = 9/1), and the conditions are 6 hours at 80 ° C. and 1 mmHg. Drying gave 2.2 g of 34-c as an oil. The obtained 34-c had a water content of 0.8% and a viscosity at 25 ° C. of η = 735 cp.
[0223]
(M) Other compounds represented by general formula (1)
Other than the above, the compound represented by the general formula (1) can be easily synthesized in the same manner as the above compound.
[0224]
2. Production of photoelectrochemical cell
(A) Preparation of titanium dioxide dispersion
Inside a Teflon-coated stainless steel container with a volume of 200 ml, titanium dioxide fine particles (Nippon Aerosil Co., Ltd., Degussa P-25) 15 g, water 45 g, dispersant (Aldrich Triton X-100) 1 g, diameter 0.5 30 g of zirconia beads having a size of mm (made by Nikkato Co., Ltd.) were added, and dispersion treatment was performed at 1500 rpm for 2 hours using a sand grinder mill (made by Imex). Zirconia beads were removed from the obtained dispersion by filtration. The average particle diameter of the titanium dioxide fine particles in the obtained dispersion was 2.5 μm. The particle size was measured with a master sizer manufactured by MALVERN.
[0225]
(B) Dye-adsorbed TiO₂Electrode fabrication
A glass rod is placed on the conductive surface side of the conductive glass with a tin oxide layer doped with fluorine (TCO glass-U made by Asahi Glass Co., Ltd. cut to a size of 20mm x 20mm, surface resistance approx. 30Ω / □) Used to apply the dispersion. The coating amount of semiconductor fine particles is 20g / m²It was. At that time, adhesive tape was stretched on a part of the conductive surface side (3 mm from the end) to form a spacer, and glass was lined up so that the adhesive tape came to both ends, and 8 sheets were applied at a time. After application, the adhesive tape was peeled off and air-dried at room temperature for 1 day. Next, this glass was put into an electric furnace (muffle furnace FP-32 type manufactured by Yamato Scientific Co., Ltd.) and baked at 450 ° C. for 30 minutes, and TiO₂An electrode was obtained. After this electrode was taken out and cooled, an ethanol solution of the dyes shown in Tables 1 and 2 (3 × 10^-Fourmol / l) for 3 hours. TiO dyed₂The electrode was immersed in 4-t-butylpyridine for 15 minutes, then washed with ethanol and air dried. The thickness of the obtained photosensitive layer was as shown in Tables 1 and 2. The coating amount of the dye is appropriately 0.1 to 10 mmol / m depending on the kind of the dye.²Selected from a range of
[0226]
(C) Creation of photoelectrochemical cell
Dye-sensitized TiO prepared as described above₂An electrode substrate (20 mm × 20 mm) was overlapped with platinum-deposited glass of the same size. Next, the electrolyte composition is soaked in the gap between the two glasses by utilizing capillary action, and the electrolyte is made of TiO.₂Introduced into the electrode, as shown in FIG. 1, a conductive support layer made of conductive glass (with a conductive layer 10a formed on a transparent glass substrate 50a), dye-sensitized TiO₂A photoelectrochemical cell in which the photosensitive layer 20, the charge transfer layer 30, the counter electrode conductive layer 40 made of platinum, and the transparent substrate 50a made of glass were sequentially laminated and sealed with an epoxy-based sealant was produced. However, if the electrolyte composition has a high viscosity and it is difficult to impregnate the electrolyte composition by utilizing capillary action, the electrolyte composition is heated to 50 ° C.₂After coating on the electrode, the electrode was placed under reduced pressure, and the electrolyte composition was sufficiently infiltrated and the air in the electrode was released. Then, a platinum-deposited glass (counter electrode) was superposed to produce a photoelectrochemical cell in the same manner.
[0227]
The above-described steps were performed by changing the electrolyte composition and the dye, and photoelectrochemical cells of Examples 1 to 49 and Comparative Examples 1 to 11 were produced. Tables 1 and 2 show the composition of the electrolyte composition used for each photoelectrochemical cell, the thickness of the photosensitive layer, and the dye used. In Tables 1 and 2, BCE represents biscyanoethyl ether. The structures of compounds Y-1 to Y-6 used in Examples and Comparative Examples are shown below.
[0228]
[Table 1]
[0229]
[Table 2]
[0230]
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[0231]
3. Measurement of photoelectric conversion efficiency
Example 1 twenty three And Comparative Examples 1-5
Simulated sunlight containing no ultraviolet rays was generated by passing light from a 500 W xenon lamp (manufactured by Ushio Electric Co., Ltd.) through an AM1.5 filter (manufactured by Oriel) and a sharp cut filter (Kenko L-42). The intensity of this light is 70mW / cm²Met. This simulated sunlight was irradiated to the photoelectrochemical cells of Examples 1 to 23 and Comparative Examples 1 to 5 at 50 ° C., and the generated electricity was measured with a current-voltage measuring device (Keutley SMU238 type). The open-circuit voltage (Voc), short-circuit current density (Jsc), form factor (FF), conversion efficiency (η), and reduction rate of the short-circuit current density after 72 hours of dark storage were calculated for each photoelectrochemical cell. Table 3 shows.
[0232]
[Table 3]
[0233]
From Table 3, in the photoelectrochemical cell (Comparative Examples 1 to 3 and Examples 1 and 2) containing a large amount of organic solvent in the electrolyte, the deterioration after storage in the dark place is remarkable. In the chemical battery, it can be seen that the conversion efficiency and durability are improved as compared with the photoelectrochemical cells of Comparative Examples 1 and 3 using only the conventional imidazolium salt. Moreover, in order to suppress the fall rate of a short circuit current density within 10%, it is preferable that the solvent content of an electrolyte composition shall be 10 mass% or less, and it is more preferable not to use a solvent. Further, in the photoelectrochemical cells of Comparative Examples 4 and 5 using only the existing imidazolium salt, the open circuit voltage is low, which causes low photoelectric conversion efficiency, whereas the present invention of Examples 3 to 19 It can be seen that the photoelectrochemical cell has a high open-circuit voltage, and the conversion efficiency is improved accordingly. Further, when the photosensitive layer is thinned, a decrease in short-circuit current density is observed (Example 9: 6.5 μm, Example 20: 4.8 μm, Example 21: 3.3 μm), but a dye having a high light absorption rate is combined. It can be seen from the results of Examples 22 and 23 that the photoelectric conversion efficiency is improved.
[0234]
Example twenty four ~ 49 And Comparative Examples 6 to 11
Simulated sunlight intensity 85mW / cm²In the same manner as in the photoelectrochemical cells of Examples 1 to 23 and Comparative Examples 1 to 5 except that the photoelectrochemical cells were irradiated at 70 ° C., Examples 24 to 49 and Comparative Example 6 The open-circuit voltage (Voc), short-circuit current density (Jsc), form factor (FF), conversion efficiency (η), and reduction rate of short-circuit current density after 72 hours of dark storage were determined for the photoelectrochemical cells of ˜11. The results are shown in Table 4.
[0235]
[Table 4]
[0236]
As can be seen from Table 4, although the photoelectrochemical cell containing an organic solvent in the electrolyte is significantly deteriorated after storage in the dark, only the conventional imidazolium salt was used in the photoelectrochemical cells of the present invention of Examples 24-29. It turns out that conversion efficiency and durability are improved compared with the photoelectrochemical cell of Comparative Examples 6-9. Moreover, in order to suppress the fall rate of a short circuit current density within 10%, it is preferable that the solvent content of an electrolyte composition shall be 10 mass% or less, and it is more preferable not to use a solvent. In the photoelectrochemical cell that does not contain a solvent, the open-circuit voltage is low in the photoelectrochemical cells of Comparative Examples 10 and 11 using only the existing imidazolium salt, whereas this causes low photoelectric conversion efficiency. In the photoelectrochemical cells of the present invention of Examples 30 to 46, it can be seen that the open circuit voltage is high and the conversion efficiency is improved accordingly. Further, when the photosensitive layer is made thinner, a decrease in short-circuit current density is observed (Example 30: 6.5 μm, Example 47: 4.8 μm, Example 48: 3.3 μm), but a dye having a high light absorption rate is combined. As can be seen from the results of Example 49, the photoelectric conversion efficiency is improved.
[0237]
【The invention's effect】
As described above in detail, the electrolyte composition of the present invention is excellent in durability and charge transport ability, and the photoelectric conversion element of the present invention using this electrolyte composition has excellent photoelectric conversion characteristics, and over time. There is little characteristic deterioration. A photoelectrochemical cell comprising such a photoelectric conversion element is extremely effective as a solar cell.
[Brief description of the drawings]
FIG. 1 is a partial cross-sectional view showing the structure of a preferred photoelectric conversion element of the present invention.
FIG. 2 is a partial cross-sectional view showing the structure of a preferred photoelectric conversion element of the present invention.
FIG. 3 is a partial cross-sectional view showing the structure of a preferred photoelectric conversion element of the present invention.
FIG. 4 is a partial cross-sectional view showing the structure of a preferred photoelectric conversion element of the present invention.
FIG. 5 is a partial cross-sectional view showing the structure of a preferred photoelectric conversion element of the present invention.
FIG. 6 is a partial cross-sectional view showing the structure of a preferred photoelectric conversion element of the present invention.
FIG. 7 is a partial cross-sectional view showing the structure of a preferred photoelectric conversion element of the present invention.
FIG. 8 is a partial cross-sectional view showing the structure of a preferred photoelectric conversion element of the present invention.
FIG. 9 is a partial cross-sectional view showing an example of the structure of a substrate integrated solar cell module using the photoelectric conversion element of the present invention.
[Explanation of symbols]
10 ... conductive layer
10a ・ ・ ・ Transparent conductive layer
11 ... Metal lead
20 ... Photosensitive layer
21 ... Semiconductor fine particles
22 ... Dye
23 ... Electrolyte
30 ... Charge transfer layer
40 ... Counterelectrode conductive layer
40a ・ ・ ・ Transparent counter electrode conductive layer
50 ... Board
50a ・ ・ ・ Transparent substrate
60 ... Undercoat layer
70 ・ ・ ・ Antireflection layer

Claims (12)

The following general formula (2):
Wherein R ₅ represents a substituent containing a — (CH ₂ —CH ₂ —O) _n — bond (n represents an integer of 2 to 20), and R _{6 to} R ₉ are each independently — (CH ₂ -CH ₂ -O) _n -bond (n represents an integer of 2 to 20), hydrogen atom, alkoxy group, cyano group, carbonate group, amide group, carbamoyl group, phosphonyl group, complex A cyclic group, an acyl group, a sulfonyl group, an acyloxy group, a sulfonyloxy group or an alkyl group, X ⁻ represents an anion, and two or more of R _{5 to} R ₉ may be linked together to form a ring structure. Well, R _{5 to} R ₉ do not contain a cation.) An electrolyte composition for use in a photoelectric conversion element, comprising a compound represented by: The following general formula (3):
Wherein R ₅ represents a substituent containing a — (CH ₂ —CH ₂ —O) _n — bond (n represents an integer of 2 to 20), and R _{6 to} R ₁₀ are each independently — (CH ₂ -CH ₂ -O) _n -bond (wherein n represents an integer of 2 to 20), hydrogen atom, alkoxy group, cyano group, carbonate group, amide group, carbamoyl group, phosphonyl group, complex A cyclic group, an acyl group, a sulfonyl group, an acyloxy group, a sulfonyloxy group or an alkyl group, X ⁻ represents an anion, and two or more of R _{5 to} R ₁₀ may be linked to each other to form a ring structure. Well, R _{5 to} R ₁₀ do not contain a cation.) An electrolyte composition for use in a photoelectric conversion element, comprising a compound represented by: 2. The electrolyte composition according to claim 1, wherein at least one of R _{6 to} R _{9 includes} a — (CH ₂ —CH ₂ —O) _n — bond (n represents an integer of 2 to 20). However, it may be the same as or different from R ₅ )). The electrolyte composition according to claim 2, wherein at least one of R _{6 to} R _{10 includes} a — (CH ₂ —CH ₂ —O) _n — bond (n represents an integer of 2 to 20). However, it may be the same as or different from R ₅ )).  The electrolyte composition according to any one of claims 1 to 4, wherein the n is an integer of 2 to 6. 6. The electrolyte composition according to claim 1, wherein the total number of —CH ₂ —CH ₂ —O— bonds in the compound represented by the general formula (2) or (3) is 4 to 6. An electrolyte composition comprising: 7. The electrolyte composition according to claim 1, wherein the substituent containing the — (CH ₂ —CH ₂ —O) _n — bond (n represents an integer of 2 to 20) is — (CH ₂ -CH ₂ -O) _n -CH ₃ ,-(CH ₂ -CH ₂ -O) _n -CH ₂ CH ₃ , or-(CH ₂ -CH ₂ -O) _n -CH ₂ CH ₂ CN (each N represents an integer of 2 to 20 in the substituent. The electrolyte composition according to claim 1, wherein the X ⁻ is I ⁻ , N ⁻ (CF ₃ SO ₂ ) ₂ , BF ₄ ⁻ , Ra—COO ⁻ (Ra is a hydrogen atom, an alkyl group, An electrolyte composition characterized by being a perfluoroalkyl group or an aryl group), Rb—SO ₃ ⁻ (Rb represents an alkyl group, a perfluoroalkyl group or an aryl group) or SCN ^— . 9. The electrolyte composition according to claim 8, wherein the X ⁻ is I ⁻ . In the electrolyte composition according to any one of claims 1 to 9, in addition to the compound represented by the general formula (2) or (3), the following general formulas (Ya), (Yb), and (Yc):
(In general formula (Ya), Q _y1 is an oxazole ring, thiazole ring, imidazole ring, pyrazole ring, isoxazole ring, thiadiazole ring, oxadiazole ring, triazole ring, pyridine ring, pyrimidine ring, pyridazine ring together with a nitrogen atom , Represents a pyrazine ring or a triazine ring, and in general formula (Yb), A _y1 represents a nitrogen atom or a phosphorus atom, and R _{y1 to} R _y6 in general formulas (Ya), (Yb) and (Yc) are each independently A substituted or unsubstituted alkyl group or a substituted or unsubstituted alkenyl group represents an iodine salt represented by any one of the following.  11. The electrolyte composition according to claim 10, wherein the cation of the iodine salt is a 5- or 6-membered nitrogen-containing aromatic cation.  12. The electrolyte composition according to any one of claims 1 to 11, wherein the solvent content is 10% by mass or less of the whole.