JP4285671B2 - Photoelectric conversion device, photoelectrochemical cell, and metal complex dye - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a metal complex dye having a high light absorption ability even in a long wavelength region, a photoelectric conversion element using semiconductor fine particles sensitized with the metal complex dye, and a photoelectrochemical cell comprising the same.
[0002]
[Prior art]
Solar cells made of single crystal silicon, polycrystalline silicon, amorphous silicon, or compounds such as cadmium telluride and indium copper selenide have been put into practical use or have been the subject of major research and development as solar cells used for photovoltaic power generation. However, in widespread use in household power sources and the like, there are problems such as high manufacturing costs, difficulty in securing raw materials, and long energy payback time, which need to be overcome. On the other hand, many solar cells using organic materials have been proposed for the purpose of increasing the area and reducing the price, but generally have a problem that conversion efficiency is low and durability is poor.
[0003]
Under such circumstances, porous titanium dioxide spectrally sensitized with a ruthenium complex dye in Nature (Vol. 353, 737-740, 1991), and US Pat. No. 4,927,721, WO 94/04497, etc. Wet photoelectric conversion elements and solar cells using a thin film as a working electrode, and materials and manufacturing techniques for producing the same have been proposed. The first advantage of this wet type photoelectric conversion element is that an inexpensive oxide semiconductor such as titanium dioxide can be used without being purified to a high purity, so that an inexpensive photoelectric conversion element can be provided. Is that the absorption of the dye used is broad, so that light in almost all wavelength regions of visible light can be converted into electricity.
[0004]
However, a known ruthenium complex dye absorbs visible light, but hardly absorbs infrared light having a wavelength longer than 700 nm, and thus has a problem of low photoelectric conversion ability in the infrared region. Therefore, in order to further increase the conversion efficiency, it is desired to develop a dye having absorption ability in a wide wavelength range from visible light to infrared region and exhibiting high photoelectric conversion ability.
[0005]
[Problems to be solved by the invention]
An object of the present invention is to use a metal complex dye having a high light absorption ability not only in the visible light region but also in the infrared region and capable of efficiently sensitizing semiconductor fine particles, and such a metal complex dye. It is providing the photoelectric conversion element which has high photoelectric conversion efficiency by this, and the photoelectrochemical cell which consists of it.
[0006]
[Means for Solving the Problems]
As a result of diligent research in view of the above-mentioned purpose, a specific ligand capable of bidentate coordination with a nitrogen atom with respect to a metal atom and, if necessary, a non-metal atom necessary to complete a 5- or 6-membered ring A metal complex dye formed by coordinating a ligand having bidentate or tridentate coordination with a nitrogen atom and a monodentate or bidentate ligand coordinated with a thiocyanate group or the like is excellent also in a long wavelength region It has been discovered that the semiconductor fine particles having a high light absorption ability and the semiconductor fine particles sensitized by such a metal complex dye exhibit high photoelectric conversion efficiency suitable as a photoelectric conversion element and can be a good photoelectrochemical cell. I came up with it.
[0007]
That is, the photoelectric conversion element of the present invention has the following general formula (I):
M (LL₁) m1 (LL₂) m2 (X) m3 ・ CI ・ ・ ・ （I）
(However, M represents a metal atom, LL₁Is the following general formula (II):
[Chemical 6]
(However, R₁And R₂Each independently represents a carboxyl group, a sulfonic acid group, a hydroxyl group, a hydroxamic acid group, a phosphoryl group or a phosphonyl group;_ThreeAnd R_FourEach independently represents a substituent, a1 and a2 each independently represent an integer of 0 to 4,the sum of a1 and a2 is 1-4,b1 represents an integer of 0 to 3, and b2 represents an integer of 0 to 5. R when a1 is 2 or more₁May be the same or different, and when a2 is 2 or more, R₂May be the same or different, and when b1 is 2 or more, R_ThreeMay be the same or different and may be connected to each other to form a ring. When b2 is 2 or more, R_FourMay be the same or different and may be connected to each other to form a ring. R when b1 and b2 are both 1 or more_ThreeAnd R_FourMay be linked to form a ring. ) Represents a bidentate ligand represented by₂Is the following general formula (III):
[Chemical 7]
(Wherein Za, Zb and Zc each independently represents a group of non-metallic atoms capable of forming a 5- or 6-membered ring, and c represents 0 or 1). X represents an acyloxy group, an acylthio group, a thioacyloxy group, a thioacylthio group, an acylaminooxy group, a thiocarbamate group, a dithiocarbamate group, a thiocarbonate group, a dithiocarbonate group, a trithiocarbonate group, an acyl group, A monodentate or bidentate ligand coordinated by a group selected from the group consisting of thiocyanate group, isothiocyanate group, cyanate group, isocyanate group, cyano group, alkylthio group, arylthio group, alkoxy group and aryloxy group, Or halogen atom, carbonyl, dialkyl ketone, 1,3-diketone, carbonamide, thiocarbonamide Represents thiourea or 1 locus or bidentate consisting isothiourea ligand, m1 represents an integer of 1 to 3, when m1 is 2 or 3 LL₁May be the same or different, m2 represents an integer from 0 to 2, and when m2 is 2, LL₂May be the same or different, m3 represents an integer of 0 to 3, and when m3 is 2 or 3, X may be the same or different, X may be linked together, and CI is a charge Represents a counter ion when a counter ion is required to neutralize the. And a semiconductor fine particle sensitized by a metal complex dye represented by the formula:
[0008]
Moreover, the photoelectrochemical cell of the present invention is characterized by using the above photoelectric conversion element.
[0009]
By satisfying the following conditions, the present invention also provides a photoelectric conversion element and a photoelectrochemical cell including semiconductor fine particles sensitized with a metal complex dye having a more excellent light absorption ability in a long wavelength region.
[0010]
(1) M in the general formula (I) is preferably Ru, Fe, Os, Cu, W, Cr, Mo, Ni, Pd, Pt, Co, Ir, Rh, Re, Mn or Zn. Fe, Os or Cu is more preferable, and Ru is particularly preferable.
[0012]
(3) a1 in the general formula (II) preferably represents 0 or 1, and a2 preferably represents 1 or 2.
[0013]
(4) R in general formula (II)₁And R₂Are preferably each independently a carboxyl group or a phosphonyl group.
[0014]
(5) b1 in the general formula (II) is preferably an integer of 0 to 2, and b2 is preferably an integer of 1 to 4.
[0015]
(6) The sum of b1 and b2 in the general formula (II) is an integer of 1 to 6, R_ThreeAnd R_FourAre preferably each independently an alkyl group, alkenyl group, alkynyl group, cycloalkyl group, hydroxyl group, alkoxy group, aryloxy group, amino group or acylamino group.
[0016]
(7) The 5- or 6-membered ring formed by Za, Zb and Zc in the general formula (III) is preferably a pyridine ring or an imidazole ring. These rings may be monocyclic or condensed.
[0017]
(8) c in the general formula (III) is preferably 0. Ie LL₂Is preferably a bidentate ligand.
[0018]
(9) In general formula (I), m1 is preferably 1 or 2, m2 is 0 or 1, and m3 is preferably an integer of 0 to 2. Particularly when m1 is 1, m2 is 1 and m3 is 1. Alternatively, it is preferably 2. When m1 is 2, m2 is preferably 0 and m3 is preferably 1 or 2.
[0019]
(10) LL in general formula (I)₂Are the following general formulas (IV-1) to (IV-8):
[Chemical 8]
(However, R₁₁~ R₁₈Each independently represents a carboxyl group, a sulfonic acid group, a hydroxyl group, a hydroxamic acid group, a phosphoryl group or a phosphonyl group;₁₉~ R₂₆Each independently represents a substituent, R₂₇~ R₃₁Each independently represents hydrogen, an alkyl group, an alkenyl group or an aryl group, and R₁₁~ R₂₆May be bonded to any position on the ring, d1 to d8, d13, d14 and d16 each independently represents an integer of 0 to 4, d9 to d12 and d15 each independently represents an integer of 0 to 6; R, when d1 to d8 are 2 or more₁₁~ R₁₈May be the same or different, and when d9 to d16 are 2 or more, R₁₉~ R₂₆May be the same or different and may be connected to each other to form a ring. And is more preferably represented by the general formula (IV-1), (IV-2), (IV-4) or (IV-6). -1) or (IV-2) is particularly preferred.
[0020]
(11) R in the general formulas (IV-1) to (IV-8)₁₁~ R₁₈Are preferably each independently a carboxyl group or a phosphonyl group.
[0021]
(12) R in the general formulas (IV-1) to (IV-8)₁₉~ R₂₆Each independently represents an alkyl group, alkenyl group, cycloalkyl group, aryl group, heterocyclic group, alkoxy group, aryloxy group, acyloxy group, alkoxycarbonyl group, carbamoyl group, acylamino group, amino group, acyl group, sulfonamide group , A cyano group or a halogen atom is preferred.
[0022]
(13) The semiconductor fine particles are preferably titanium oxide fine particles.
[0023]
In the metal complex dye according to a preferred embodiment of the present invention, M in the general formula (I) is Ru,
LL₁Is a bidentate ligand represented by the above general formula (II),
LL₂Is a bidentate or tridentate ligand represented by any one of the general formulas (IV-1) to (IV-8),
X is an acyloxy group, acylthio group, thioacyloxy group, thioacylthio group, acylaminooxy group, thiocarbamate group, dithiocarbamate group, thiocarbonate group, dithiocarbonate group, trithiocarbonate group, acyl group, thiocyanate group, A monodentate or bidentate ligand coordinated by a group selected from the group consisting of an isothiocyanate group, a cyanate group, an isocyanate group, a cyano group, an alkylthio group, an arylthio group, an alkoxy group and an aryloxy group, or a halogen atom Represents a monodentate or bidentate ligand consisting of carbonyl, dialkyl ketone, 1,3-diketone, carbonamide, thiocarbonamide, thiourea or isothiourea,
m1 is 1 or 2, and when m1 is 2, LL₁Can be the same or different,
m2 is 0 or 1,
m3 represents an integer of 0 to 2, and when m3 is 2, X may be the same or different, and X may be linked together,
m2 and m3 are not 0 at the same time,
CI is a counter ion when a counter ion is required to neutralize the charge.
[0024]
In the metal complex dye according to this preferred embodimentIn general formula (II)The sum of b1 and b2 is an integer of 1 to 6, and R3 and R4 are each independently an alkyl group, alkenyl group, alkynyl group, cycloalkyl group, hydroxyl group, alkoxy group, aryloxy group, amino group or acylamino group. Preferably there is.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
[1] Metal complex dye
The metal complex dye used for the photoelectric conversion element of the present invention has the following general formula (I):
M (LL₁)_m1(LL₂)_m2(X)_m3・ CI (I)
It is represented by Each component will be described in detail below.
[0026]
(A) Metal atom M
M represents a metal atom. M is preferably a metal capable of tetracoordination or hexacoordination, and more preferably Ru, Fe, Os, Cu, W, Cr, Mo, Ni, Pd, Pt, Co, Ir, Rh, Re, Mn Or Zn, particularly preferably Ru, Fe, Os or Cu, and most preferably Ru.
[0027]
(B) Ligand LL₁
LL₁Represents a bidentate ligand. LL₁M1 representing the number of is an integer of 1 to 3, preferably 1 or 2, and more preferably 2. LL when m1 is 2 or 3₁May be the same or different.
[0028]
Ligand LL₁Is the following general formula (II):
[Chemical 9]
It is represented by
[0029]
R in general formula (II)₁And R₂Are each independently a carboxyl group, a sulfonic acid group, a hydroxyl group, or a hydroxamic acid group (preferably having 1 to 20 carbon atoms such as -CONHOH, -CONCH_ThreeOH, etc.), phosphoryl group (eg -OP (O) (OH)₂Etc.) and phosphonyl groups (eg -P (O) (OH)₂Etc.), preferably a carboxyl group, a phosphoryl group or a phosphonyl group, more preferably a carboxyl group or a phosphonyl group, and most preferably a carboxyl group.
[0030]
R in general formula (II)_ThreeAnd R_FourEach independently represents a substituent, preferably an alkyl group (preferably having 1 to 20 carbon atoms, such as methyl, ethyl, isopropyl, t-butyl, pentyl, heptyl, 1-ethylpentyl, Benzyl group, 2-ethoxyethyl group, 1-carboxymethyl group, etc.)
An alkenyl group (preferably having 2 to 20 carbon atoms, such as vinyl, allyl, oleyl, etc.),
An alkynyl group (preferably having 2 to 20 carbon atoms, such as an ethynyl group, a butadiynyl group, a phenylethynyl group, etc.),
A cycloalkyl group (preferably having 3 to 20 carbon atoms, such as a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a 4-methylcyclohexyl group, etc.),
Hydroxyl group,
An aryl group (preferably having 6 to 26 carbon atoms, such as a phenyl group, 1-naphthyl group, 4-methoxyphenyl group, 2-chlorophenyl group, 3-methylphenyl group, etc.),
A heterocyclic group (preferably having 2 to 20 carbon atoms, such as 4-pyridyl group, 1-imidazolyl group, 2-benzimidazolyl group, 2-thiazolyl group, 2-oxazolyl group),
An alkoxy group (preferably having 1 to 20 carbon atoms, such as methoxy group, ethoxy group, isopropyloxy group, benzyloxy group, etc.),
Aryloxy groups (preferably having 6 to 26 carbon atoms, such as phenoxy group, 1-naphthyloxy group, 3-methylphenoxy group, 4-methoxyphenoxy group, etc.),
An alkoxycarbonyl group (preferably having 2 to 20 carbon atoms, such as an ethoxycarbonyl group, 2-ethylhexyloxycarbonyl group, etc.),
An amino group (preferably having 0 to 20 carbon atoms, such as an amino group, N, N-dimethylamino group, N, N-diethylamino group, N-ethylamino group, anilino group, etc.),
An acyl group (preferably having 1 to 20 carbon atoms, such as an acetyl group or a benzoyl group),
A sulfonamide group (preferably having 0 to 20 carbon atoms, such as N, N-dimethylsulfonamide group, N-phenylsulfonamide group, etc.),
An acyloxy group (preferably having 1 to 20 carbon atoms, such as acetyloxy group, benzoyloxy group, etc.),
A carbamoyl group (preferably having 1 to 20 carbon atoms, such as N, N-dimethylcarbamoyl group, N-phenylcarbamoyl group),
An acylamino group (preferably having 1 to 20 carbon atoms, such as an acetylamino group, a benzoylamino group, etc.),
A cyano group, or
A halogen atom (for example, fluorine atom, chlorine atom, bromine atom, iodine atom, etc.);
[0031]
In general formula (II), R_ThreeAnd R_FourIs more preferably an alkyl group, alkenyl group, alkynyl group, cycloalkyl group, hydroxyl group, alkoxy group, aryloxy group, amino group or acylamino group, more preferably an alkyl group, alkenyl group, alkoxy group, amino group or An acylamino group, particularly preferably an alkyl group, an alkoxy group or an amino group.
[0032]
LL₁When includes an alkyl group, an alkenyl group or the like, they may be linear or branched and may be substituted or unsubstituted. LL₁When includes an aryl group, a heterocyclic group and the like, they may be monocyclic or condensed, and may be substituted or unsubstituted.
[0033]
A1 and a2 in the general formula (II) each independently represent an integer of 0 to 4, and when a1 is 2 or more, R₁May be the same or different, and when a2 is 2 or more, R₂May be the same or different. R₁May be substituted on any carbon atom on the pyridine ring, R₂May be substituted at any carbon atom on the quinoline ring. Preferably a1 represents the integer of 0-2, More preferably, it represents 0 or 1. a2 is preferably 1 or 2. The sum of a1 and a2 is preferably 1 to 4, more preferably 1 or 2.
[0034]
B1 in the general formula (II) represents an integer of 0 to 3, and b2 represents an integer of 0 to 5. R when b1 is 2 or more_ThreeMay be the same or different and may be linked to each other to form a ring. When b2 is 2 or more, R_FourMay be the same or different and may be linked together to form a ring. R when b1 and b2 are both 1 or more_ThreeAnd R_FourMay be linked to form a ring, and the formed ring is preferably a benzene ring, a cyclohexane ring or a cyclopentane ring. R_ThreeMay be substituted on any carbon atom on the pyridine ring, R_FourMay be substituted on any carbon on the quinoline ring.
[0035]
b1 preferably represents an integer of 0 to 2, and more preferably 0 or 1. B2 preferably represents an integer of 1 to 4, more preferably 1 or 2. The sum of b1 and b2 is preferably from 1 to 6, and more preferably from 1 to 3.
[0036]
LL in the general formula (I) of the present invention₁Specific examples of these are shown below, but the present invention is not limited thereto.
[0037]
[Chemical Formula 10]
[0038]
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[0039]
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[0040]
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[0041]
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[0042]
(C) Ligand LL₂
LL₂Represents a bidentate or tridentate ligand. LL₂M2 representing the number of is an integer of 0 to 2, preferably 0 or 1. LL when m2 is 2₂May be the same or different.
[0043]
Ligand LL₂Is represented by the following general formula (III):
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It is represented by
[0044]
Za, Zb and Zc in the general formula (III) each independently represent a nonmetallic atom group capable of forming a 5- or 6-membered ring, and the formed 5- or 6-membered ring may be substituted or unsubstituted. These may be monocyclic or condensed. Za, Zb and Zc are preferably composed of a carbon atom, a hydrogen atom, a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom and / or a halogen atom, and preferably form an aromatic ring. In the case of a 5-membered ring, an imidazole ring, an oxazole ring, a thiazole ring or a triazole ring is preferably formed. In the case of a 6-membered ring, a pyridine ring, a pyrimidine ring, a pyridazine ring or a pyrazine ring is preferably formed. Among these, it is more preferable to form an imidazole ring or a pyridine ring.
[0045]
C in the general formula (III) represents 0 or 1. c is preferably 0, ie LL₂Is preferably a bidentate ligand.
[0046]
Ligand LL₂Are the following general formulas (IV-1) to (IV-8):
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Is preferably represented by any of the following.
[0047]
R in the general formulas (IV-1) to (IV-8)₁₁~ R₁₈Are each independently a carboxyl group, a sulfonic acid group, a hydroxyl group, or a hydroxamic acid group (preferably having 1 to 20 carbon atoms such as -CONHOH, -CONCH_ThreeOH, etc.), phosphoryl group (eg -OP (O) (OH)₂Etc.) and phosphonyl groups (eg -P (O) (OH)₂Etc.), preferably a carboxyl group, a phosphoryl group or a phosphonyl group, more preferably a carboxyl group or a phosphonyl group, and most preferably a carboxyl group.
[0048]
R in the general formulas (IV-1) to (IV-8)₁₉~ R₂₆Each independently represents a substituent, preferably an alkyl group, alkenyl group, cycloalkyl group, aryl group, heterocyclic group, alkoxy group, aryloxy group, acyloxy group, alkoxycarbonyl group, carbamoyl group, acylamino group, amino group , Acyl group, sulfonamide group, cyano group or halogen atom (above, preferred examples are the above R_ThreeAnd R_FourAnd more preferably an alkyl group, an alkenyl group, an aryl group, a heterocyclic group, an alkoxy group, an alkoxycarbonyl group, an acylamino group, an amino group or a halogen atom, particularly preferably an alkyl group or an alkenyl group. , An alkoxy group, an alkoxycarbonyl group, an acylamino group or an amino group.
[0049]
R in the general formulas (IV-1) to (IV-8)₂₇~ R₃₁Each independently represents hydrogen, an alkyl group, an alkenyl group or an aryl group (above, preferred examples are R_ThreeAnd R_FourIt is preferably an alkyl group substituted with an alkyl group or a carboxyl group. LL₂When includes an alkyl group, an alkenyl group or the like, they may be linear or branched and may be substituted or unsubstituted. LL₂When includes an aryl group, a heterocyclic group and the like, they may be monocyclic or condensed, and may be substituted or unsubstituted.
[0050]
R in the general formulas (IV-1) to (IV-8)₁₁~ R₂₆May be bonded to any position on the ring, d1 to d6 each independently represents an integer of 0 to 4, preferably 0 to 2, and d7 and d8 each independently represents an integer of 0 to 4. Represents an integer, preferably an integer of 0 to 3. d9 to d12 and d15 each independently represent an integer of 0 to 6, d13, d14 and d16 each independently represent an integer of 0 to 4, and d9 to d16 preferably represent an integer of 0 to 3.
[0051]
R when d1 to d8 is 2 or more₁₁~ R₁₈May be the same or different, and when d9 to d16 are 2 or more, R₁₉~ R₂₆May be the same or different and may be connected to each other to form a ring. Especially when d10 is 2 or more, R_TenIt is preferable that they are connected to each other on a pyridine ring to further form a pyridine ring.
[0052]
Ligand LL₂Is more preferably represented by the general formula (IV-1), (IV-2), (IV-4) or (IV-6), according to the general formula (IV-1) or (IV-2) It is particularly preferred that
[0053]
Ligand LL of the present invention₂Specific examples of these are shown below, but the present invention is not limited thereto.
[0054]
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[0055]
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[0056]
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[0057]
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[0058]
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[0059]
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[0060]
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[0061]
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[0062]
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[0063]
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[0064]
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[0065]
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[0066]
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[0067]
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[0068]
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[0069]
(D) Ligand X
In general formula (I), X represents a monodentate or bidentate ligand, m3 representing the number of ligands X represents an integer of 0 to 3, preferably 0 to 2, and more preferably. 1 or 2. In particular, when X is a monodentate ligand, m3 is preferably 2. When X is a bidentate ligand, m3 is preferably 1. When m3 is 2 or 3, X may be the same or different, and X may be linked together.
[0070]
Ligand X is
An acyloxy group (preferably having 1 to 20 carbon atoms such as acetyloxy group, benzoyloxy group, salicylic acid group, glycyl group, N, N-dimethylglycyl group, oxalylene group (—OC (O) C (O) O— )etc),
An acylthio group (preferably having 1 to 20 carbon atoms, such as an acetylthio group or a benzoylthio group),
A thioacyloxy group (preferably having 1 to 20 carbon atoms, such as a thioacetyloxy group (CH_ThreeC (S) O-)),
Thioacylthio group (preferably having 1 to 20 carbon atoms, such as thioacetylthio group (CH_ThreeC (S) S-), thiobenzoylthio group (PhC (S) S-) etc.),
An acylaminooxy group (preferably having 1 to 20 carbon atoms such as N-methylbenzoylaminooxy group (PhC (O) N (CH_Three) O-), acetylaminooxy group (CH_ThreeC (O) NHO-)),
A thiocarbamate group (preferably having 1 to 20 carbon atoms such as N, N-diethylthiocarbamate group),
Dithiocarbamate group (preferably having 1 to 20 carbon atoms, such as N-phenyldithiocarbamate group, N, N-dimethyldithiocarbamate group, N, N-diethyldithiocarbamate group, N, N-dibenzyldithiocarbamate group, etc.) ,
A thiocarbonate group (preferably having 1 to 20 carbon atoms, such as an ethylthiocarbonate group),
Dithiocarbonate groups (preferably having 1 to 20 carbon atoms, eg ethyl dithiocarbonate groups (C₂H_FiveOC (S) S-))
A trithiocarbonate group (preferably having 1 to 20 carbon atoms such as an ethyltrithiocarbonate group (C₂H_FiveSC (S) S-) etc.),
An acyl group (preferably having 1 to 20 carbon atoms, such as an acetyl group or a benzoyl group),
Thiocyanate group,
An isothiocyanate group,
Cyanate groups,
Isocyanate groups,
A cyano group,
An alkylthio group (preferably having 1 to 20 carbon atoms, such as methanethio group, ethylenedithio group, etc.),
An arylthio group (preferably having 6 to 20 carbon atoms such as benzenethio group, 1,2-phenylenedithio group, etc.),
An alkoxy group (preferably having 1 to 20 carbon atoms, such as a methoxy group) and
A monodentate or bidentate ligand coordinated with a group selected from the group consisting of aryloxy groups (preferably having 6 to 20 carbon atoms, such as phenoxy group, quinoline-8-hydroxyl group, etc.), or
A halogen atom (preferably a chlorine atom, a bromine atom or an iodine atom),
Carbonyl (... CO),
Dialkyl ketones (preferably having 3 to 20 carbon atoms such as acetone ((CH_Three)₂CO ...) (... represents a coordination bond)),
1,3-diketone (preferably having 3 to 20 carbon atoms such as acetylacetone (CH_ThreeC (O-) CH = C (O…) CH_Three), Trifluoroacetylacetone (CF_ThreeC (O-) CH = C (O…) CH_Three), Dipivaloylmethane (t-C_FourH₉C (O-) CH = C (O…) -t-C_FourH₉), Dibenzoylmethane (PhC (O-) CH = C (O ...) Ph), 3-chloroacetylacetone (CH_ThreeC (O-) CCl = C (O…) CH_Three)etc)
Carbonamide (preferably having 1 to 20 carbon atoms, eg CH_ThreeN = C (CH_Three) O-, -OC (= NH) -C (= NH) O- etc.),
Thiocarbonamide (preferably having 1 to 20 carbon atoms, eg CH_ThreeN = C (CH_Three) S-etc),
Thiourea (preferably having 1 to 20 carbon atoms, eg NH₂-C (S…) NH₂,… N (CH_Three)₂-C (S ...) N (CH_Three)₂Etc.), or
Isothiourea (preferably having 1 to 20 carbon atoms, eg NH = C (S-) NH₂,… N (CH_Three) = C (S-) NHCH_ThreeEtc.).
[0071]
The ligand X is preferably an acyloxy group, a thioacylthio group, an acylaminooxy group, a dithiocarbamate group, a dithiocarbonate group, a trithiocarbonate group, a thiocyanate group, an isothiocyanate group, a cyanate group, an isocyanate group, a cyano group, an alkylthio group. A ligand coordinated by a group selected from the group consisting of a group, an arylthio group, an alkoxy group and an aryloxy group, or a ligand consisting of a halogen atom, carbonyl, 1,3-diketone or thiourea, more preferably Is a ligand coordinated by a group selected from the group consisting of acyloxy group, acylaminooxy group, dithiocarbamate group, thiocyanate group, isothiocyanate group, cyanate group, isocyanate group, cyano group and arylthio group, or halogen atom 1,3-diketone Is a ligand composed of thiourea, more preferably a ligand coordinated with a group selected from the group consisting of a dithiocarbamate group, a thiocyanate group, an isothiocyanate group, a cyanate group and an isocyanate group, or a halogen atom or 1 , 3-diketones, particularly preferably ligands coordinated with a group selected from the group consisting of dithiocarbamate groups, thiocyanate groups and isothiocyanate groups, or ligands composed of 1,3-diketones. It is a rank. In addition, when the ligand X contains an alkyl group, an alkenyl group, an alkynyl group, an alkylene group or the like, these may be linear or branched, and may be substituted or unsubstituted. Moreover, when an aryl group, a heterocyclic group, a cycloalkyl group and the like are included, they may be substituted or unsubstituted, and may be monocyclic or condensed.
[0072]
In the general formula (I), when X is a bidentate ligand, X is an acyloxy group, an acylthio group, a thioacyloxy group, a thioacylthio group, an acylaminooxy group, a thiocarbamate group, a dithiocarbamate group, a thiocarbonate group, A ligand coordinated by a group selected from the group consisting of dithiocarbonate groups, trithiocarbonate groups, acyl groups, alkylthio groups, arylthio groups, alkoxy groups and aryloxy groups, or 1,3-diketones, A ligand consisting of amide, thiocarbonamide or thiourea is preferred. When X is a monodentate ligand, X is a ligand coordinated with a group selected from the group consisting of a thiocyanate group, an isothiocyanate group, a cyanate group, an isocyanate group, a cyano group, an alkylthio group, and an arylthio group, or A ligand comprising a halogen atom, carbonyl, 1,3-diketone or thiourea is preferred.
[0073]
Specific examples of the ligand X of the present invention are shown below, but the present invention is not limited thereto. The structural formula shown here is just one of the many possible resonance structures, and the distinction between covalent bonds (represented by-) and coordinate bonds (represented by ...) is also formal. It does not represent a distinction.
[0074]
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[0075]
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[0076]
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[0077]
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[0078]
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[0079]
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[0080]
When M in the general formula (I) is a metal that prefers 4-coordination, such as Cu, Pd, and Pt, m1 is preferably 1 or 2 and m2 is preferably 0. In this case, when m1 is 1, m3 is preferably 1 or 2, and when m1 is 2, m3 is preferably 0.
When M is a metal that prefers 6-coordination, m1 is preferably 1 or 2, and more preferably 2. In this case, when m1 is 1, m2 is preferably 1 or 2, and more preferably 1. Here, when m2 is 1, m3 is preferably 1 or 2, and when m2 is 2, m3 is preferably 0. When m1 is 2, m2 is preferably 0 or 1, and more preferably 0. Here, when m2 is 0, m3 is preferably 1 or 2, and when m2 is 1, m3 is preferably 0. When m1 is 3, both m2 and m3 are preferably 0.
[0081]
(E) Counter ion CI
CI in the general formula (I) represents a counter ion when a counter ion is required to neutralize the charge. Whether the dye is a cation or an anion or has a net ionic charge depends on the metal, ligand and substituent in the dye. When the substituent has a dissociable group, it may be dissociated to have a negative charge, and in this case as well, the charge of the entire molecule is neutralized by CI.
[0082]
Typical positive counterions are inorganic or organic ammonium ions (eg tetraalkylammonium ions, pyridinium ions, etc.), alkali metal ions and protons. On the other hand, the negative counter ion may be either an inorganic anion or an organic anion, such as a halogen anion (for example, fluoride ion, chloride ion, bromide ion, iodide ion, etc.), substituted arylsulfonate ion (for example, p-toluenesulfonate ion, p-chlorobenzenesulfonate ion, etc.), aryl disulfonate ion (eg 1,3-benzenedisulfonate ion, 1,5-naphthalenedisulfonate ion, 2,6-naphthalenedisulfonate ion, etc.) Alkyl sulfate ions (eg methyl sulfate ions), sulfate ions, thiocyanate ions, perchlorate ions, tetrafluoroborate ions, hexafluorophosphate ions, picrate ions, acetate ions, trifluoromethanesulfonate ions, etc. It is done. Furthermore, an ionic polymer or another dye having a charge opposite to that of the dye may be used as the charge balance counter ion, or a metal complex ion (for example, bisbenzene-1,2-dithiolatonickel (III)) can be used. It is.
[0083]
(F) Bonding group
The dye represented by the general formula (I) has at least one suitable interlocking group for the surface of the semiconductor fine particles, preferably 1 to 6, and more preferably 1 to 4. . Preferred linking groups include a carboxyl group, a sulfonic acid group, a hydroxyl group, a hydroxamic acid group (eg, —CONHOH), a phosphoryl group (eg, —OP (O) (OH)₂Etc.), phosphonyl groups (eg -P (O) (OH)₂Etc.) acidic group (substituent having a dissociative proton).
[0084]
The acidic group is LL in the general formula (I)₁Has at least one, but LL₂It is preferable to have at least one or more.
[0085]
(G) Specific examples of metal complex dyes
Among the metal complex dyes, particularly preferred are the following general formula (V):
Ru (LL₁)_m1(LL₂)_m2(X)_m3・ CI ・ ・ ・ (V)
(However, LL₁Represents a bidentate ligand represented by the general formula (II),
LL₂Represents a bidentate or tridentate ligand represented by any one of the general formulas (IV-1) to (IV-8),
X is an acyloxy group, acylthio group, thioacyloxy group, thioacylthio group, acylaminooxy group, thiocarbamate group, dithiocarbamate group, thiocarbonate group, dithiocarbonate group, trithiocarbonate group, acyl group, thiocyanate group, A monodentate or bidentate ligand coordinated by a group selected from the group consisting of an isothiocyanate group, a cyanate group, an isocyanate group, a cyano group, an alkylthio group, an arylthio group, an alkoxy group and an aryloxy group, or a halogen atom Represents a monodentate or bidentate ligand consisting of carbonyl, dialkyl ketone, 1,3-diketone, carbonamide, thiocarbonamide, thiourea or isothiourea,
m1 is 1 or 2, and when m1 is 2, LL₁Can be the same or different,
m2 is 0 or 1,
m3 represents an integer of 0 to 2, and when m3 is 2, X may be the same or different, and X may be linked together,
m2 and m3 are not 0 at the same time,
CI represents a counter ion when a counter ion is required to neutralize the charge. Is a ruthenium complex dye represented by
[0086]
Specific examples of the metal complex dye of the present invention are shown below, but the present invention is not limited thereto.
[0087]
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[0088]
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[0089]
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[0090]
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[0091]
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[0092]
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[0093]
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[0094]
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[0095]
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[0096]
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[0097]
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[0098]
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[0099]
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[0100]
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[0101]
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[0102]
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[0103]
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[0104]
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[0105]
The synthesis of the metal complex dye represented by the general formula (I) of the present invention is described in Chem. Phys. Lett., 85, 309 (1982), Chem. Phys. Lett., 71, 220 (1980), J. Am. Chem. Soc., 115, 6382 (1993) and the like and methods cited in the literature can be referred to. Each ligand can be synthesized with reference to methods described in literatures such as Synth. Commun., 27, 2165 (1997) and Aust. J. Chem., 25, 1631 (1972).
[0106]
[2] Photoelectric conversion element
The photoelectric conversion element of the present invention has semiconductor fine particles sensitized with the metal complex dye in the photosensitive layer. Preferably, as shown in FIG. 1, a semiconductor fine particle in which a conductive layer 10, a photosensitive layer 20, a charge transfer layer 30 and a counter electrode conductive layer 40 are laminated in this order, and the photosensitive layer 20 is sensitized by the metal complex dye 22 of the present invention. 21 and a charge transport material 23 filled in a gap between the semiconductor fine particles 21. The charge transport material 23 is composed of the same components as the material used for the charge transfer layer 30. 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. Hereinafter, 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.
[0107]
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 metal complex dye 22 excites the dye 22 and the like, and the light in the excited dye 22 and the like is high. The energy 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.
[0108]
(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.
[0109]
In the case of (1), a conductive layer having sufficient strength as metal and having conductivity is used.
[0110]
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 are metals (eg, platinum, gold, silver, copper, aluminum, rhodium, indium, etc.), carbon, or conductive metal oxides (indium-tin composite oxide, tin oxide doped with fluorine, etc.) Is mentioned. The thickness of the conductive layer is preferably about 0.02 to 10 μm.
[0111]
The lower the surface resistance of the conductive support, the better. The range of 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 / □.
[0112]
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, preferably 50% or more, and particularly preferably 70% or more.
[0113]
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. In particular, 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), syndioctane polysterene (SPS), polyphenylene sulfide (PPS), polycarbonate (PC), and polyarylate. (PAr), polysulfone (PSF), polyester sulfone (PES), polyetherimide (PEI), cyclic polyolefin, brominated phenoxy and the like. In order to ensure sufficient transparency, the amount of conductive metal oxide applied is 1 m of glass or plastic support.²The amount is preferably 0.01 to 100 g.
[0114]
It is preferable to use a metal lead for the purpose of reducing the resistance of the transparent conductive support. The material of the metal lead is preferably a metal such as aluminum, copper, silver, gold, platinum, nickel, and particularly preferably aluminum and silver. The metal lead is preferably installed on a transparent substrate by vapor deposition, sputtering, or the like, and a transparent conductive layer made of tin oxide doped with fluorine or an ITO film is preferably provided thereon. 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 the metal lead is preferably within 10%, more preferably 1 to 5%.
[0115]
(B) Photosensitive layer
In the photosensitive layer containing the semiconductor fine particles sensitized by the metal complex dye of the present invention, the semiconductor fine particles act as a so-called photoconductor, absorb light and perform charge separation to generate electrons and holes. In the dye-sensitized semiconductor fine particles, light absorption and generation of electrons and holes thereby occur mainly in the dye, and the semiconductor fine particles play a role of receiving and transmitting the electrons.
[0116]
(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.), or compounds having a perovskite structure (eg strontium titanate, titanium). Calcium oxide, sodium titanate, barium titanate, potassium niobate, etc.) can be used.
[0117]
Preferred metal chalcogenides include titanium, tin, zinc, iron, tungsten, zirconium, hafnium, strontium, indium, cerium, yttrium, lanthanum, vanadium, niobium or tantalum oxide, cadmium, zinc, lead, silver, antimony or bismuth. Sulfide, cadmium or lead selenide, cadmium telluride and the like. Examples of other compound semiconductors include phosphides such as zinc, gallium, indium, and cadmium, gallium-arsenic or copper-indium selenides, and copper-indium sulfides.
[0118]
Preferred specific examples of the semiconductor used in the present invention include Si and TiO.₂, SnO₂, Fe₂O_Three, WO_Three, ZnO, Nb₂O_Five, CdS, ZnS, PbS, Bi₂S_Three, CdSe, CdTe, GaP, InP, GaAs, CuInS₂, CuInSe₂More preferably, TiO₂, ZnO, SnO₂, Fe₂O_Three, WO_Three, Nb₂O_Five, CdS, PbS, CdSe, InP, GaAs, CuInS₂Or CuInSe₂And particularly preferably TiO₂Or Nb₂O_FiveAnd most preferably TiO₂It is.
[0119]
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 viewpoints of manufacturing cost, securing raw materials, energy payback time, and the like.
[0120]
The particle size of the semiconductor fine particles is generally on the order of nm to μm, but the average particle size of the primary particles obtained from the diameter when the projected area is converted into a circle is preferably 5 to 200 nm, more preferably 8 to 100 nm. preferable. The average particle size of the semiconductor fine particles (secondary particles) in the dispersion is preferably 0.01 to 100 μm.
[0121]
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 diameter, for example, about 300 nm may be mixed.
[0122]
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's "Synthesis of monodisperse particles by the new synthesis gel-sol method and size morphology control", Materia, Vol. 35, No. 9, pp. 1012-1018 (1996) Etc. are preferred. Also preferred is a method developed by Degussa to produce an oxide by high-temperature hydrolysis of chloride in an oxyhydrogen salt.
[0123]
When the semiconductor fine particles are titanium oxide, the above sol-gel method, gel-sol method, and high-temperature hydrolysis method in oxyhydrogen salt of chloride are preferred, but Kiyoshi Manabu's “Titanium oxide properties and applied technology” The sulfuric acid method and the chlorine method described in Gihodo Publishing (1997) can also be used. Further, as the sol-gel method, the method described in Journal of American Ceramic Society of Barb et al., Vol. 80, No. 12, pp. 3157-3171 (1997), and Chemical Materials of Burnside et al. , Vol. 9, No. 9, pages 2419-2425 are also preferred.
[0124]
(2) Semiconductor fine particle layer
In order to apply the semiconductor fine particles on the conductive support, in addition to the method of applying a dispersion or colloidal solution of the semiconductor fine particles on the conductive support, the above-described sol-gel method or the like can also be used. In consideration of mass production of photoelectric conversion elements, physical properties of semiconductor fine particle liquid, flexibility of conductive support, etc., a wet film forming method is relatively advantageous. As a wet film forming method, a coating method and a printing method are typical.
[0125]
In addition to the sol-gel method described above, a method for producing a dispersion of semiconductor fine particles includes a method of grinding with a mortar, a method of dispersing while grinding using a mill, or a fine particle in a solvent when synthesizing a semiconductor. The method of depositing and using as it is is mentioned.
[0126]
Examples of the dispersion medium include water or various organic solvents (for example, methanol, ethanol, isopropyl alcohol, dichloromethane, acetone, acetonitrile, ethyl acetate, and the like). During dispersion, a polymer, surfactant, acid, chelating agent, or the like may be used as a dispersion aid as necessary.
[0127]
The application method is disclosed in Japanese Patent Publication No. 58-4589 as a roller method, a dip method as an application system, an air knife method, a blade method, etc. as a metering system, and the application and metering can be made the same part. The wire bar method, the slide hopper method, the extrusion method, the curtain method and the like described in US Pat. Nos. 2681294, 2761419, 2761791 and the like are preferable. 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 are preferred, including the three major printing methods of letterpress, offset and gravure. From these, a preferred film forming method is selected according to the liquid viscosity and the wet thickness.
[0128]
The viscosity of the dispersion of semiconductor fine particles greatly depends on the type and dispersibility of the semiconductor fine particles, the type of solvent used, and additives such as surfactants and binders. For a high viscosity liquid (for example, 0.01 to 500 Poise), an extrusion method, a casting method, a screen printing method, or the like is preferable. For low-viscosity liquids (for example, 0.1 Poise or less), the slide hopper method, wire bar method, or spin method is preferable, and a uniform film can be obtained. If there is a certain amount of coating, coating by the extrusion method is possible even in the case of a low viscosity liquid. 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.
[0129]
The semiconductor fine particle layer is not limited to a single layer, but a multi-layer coating of a dispersion of semiconductor fine particles having different particle diameters, or a multi-layer coating of a coating layer containing different types of semiconductor fine particles (or different binders and additives) You can also Multi-layer coating is also effective when the film thickness is insufficient with a single coating. For multilayer coating, an extrusion method or a slide hopper method is suitable. In the case of applying multiple layers, the multiple layers may be applied at the same time, or may be successively applied several times to several dozen times. Further, screen printing can be preferably used as long as it is sequentially overcoated.
[0130]
In general, as the thickness of the semiconductor fine particle layer (same as the thickness of the photosensitive layer) increases, the amount of supported dye increases per unit projected area, and thus the light capture rate increases. Loss due to coupling also increases. Therefore, the preferable thickness of the semiconductor fine particle layer is 0.1 to 100 μm. 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. Semiconductor fine particle support 1m²The hit application amount is preferably 0.5 to 400 g, more preferably 5 to 100 g.
[0131]
After the semiconductor fine particles are applied on the conductive support, the semiconductor fine particles are preferably brought into contact with each other electronically, and heat treatment is preferably performed in order to improve the coating strength and the adhesion to the support. A preferable heating temperature range is 40 ° C. or higher and lower than 700 ° C., and more preferably 100 ° C. or higher and 600 ° C. or lower. The heating time is about 10 minutes to 10 hours. When using a support having a low melting point or softening point such as a polymer film, high temperature treatment is not preferable because it causes deterioration of the support. Moreover, it is preferable that it is as low as possible also from a viewpoint of cost. The temperature can be lowered by using a combination of small semiconductor fine particles of 5 nm or less as described above, heat treatment in the presence of a mineral acid, or the like.
[0132]
In order to increase the surface area of the semiconductor fine particles after heat treatment, increase the purity near the semiconductor fine particles, and increase the efficiency of electron injection from the dye to the semiconductor particles, for example, chemical plating using a titanium tetrachloride aqueous solution or a titanium trichloride aqueous solution is used. The electrochemical plating process used may be performed.
[0133]
The semiconductor fine particles preferably have a large surface area so that many dyes can be adsorbed. For this reason, the surface area of the semiconductor fine particle layer 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.
[0134]
(3) Adsorption of metal complex dye on semiconductor fine particles
In order to adsorb the metal complex dye to the semiconductor fine particles, a method of immersing a conductive support having a well-dried semiconductor fine particle layer in a solution of the metal complex dye or applying a solution of the metal complex dye to the semiconductor fine particle layer. Can be used. In the former case, an immersion method, a dip method, a roller method, an air knife method or the like can be used. In the immersion method, the adsorption of the metal complex dye may be performed at room temperature, or may be performed by heating and refluxing as described in JP-A-7-249790. Examples of the latter application method include a wire bar method, a slide hopper method, an extrusion method, a curtain method, a spin method, a spray method, and the like. Printing methods include letterpress, offset, gravure, and screen printing. The solvent can be appropriately selected according to the solubility of the metal complex dye. For example, alcohols (methanol, ethanol, t-butanol, benzyl alcohol, etc.), nitriles (acetonitrile, propionitrile, 3-methoxypropionitrile, etc.), nitromethane, halogenated hydrocarbons (dichloromethane, dichloroethane, chloroform, chlorobenzene) Etc.), ethers (diethyl ether, tetrahydrofuran, etc.), dimethyl sulfoxide, amides (N, N-dimethylformamide, N, N-dimethylacetamide, etc.), N-methylpyrrolidone, 1,3-dimethylimidazolidinone , 3-methyloxazolidinone, esters (ethyl acetate, butyl acetate, etc.), carbonates (diethyl carbonate, ethylene carbonate, propylene carbonate, etc.), ketones (acetone, 2-butanone, cyclohexanone, etc.), hydrocarbons (hexane) , Petroleum ether, ben Zen, toluene, etc.), water, and mixed solvents thereof.
[0135]
As for the viscosity of the solution of the metal complex dye, as in the formation of the semiconductor fine particle layer, various printing methods other than the extrusion method are suitable for the high viscosity liquid (for example, 0.01 to 500 Poise), and the low viscosity liquid (for example, The slide hopper method, wire bar method, or spin method is suitable for 0.1 Poise or less), and any of them can form a uniform film.
[0136]
Thus, the dye adsorption method may be appropriately selected according to the viscosity of the metal complex dye coating solution, the coating amount, the conductive support, the coating speed, and the like. The time required for the dye adsorption after coating is preferably as short as possible when mass production is considered.
[0137]
Since the presence of the unadsorbed metal complex dye becomes a disturbance of device performance, it is preferably removed by washing immediately after the adsorption. It is preferable to use a wet cleaning tank and perform cleaning with 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 avoid water adsorbing on the surface of the semiconductor fine particles after the heat treatment, it is preferable to quickly adsorb the dye between 40 to 80 ° C. without returning to normal temperature.
[0138]
The total amount of metal complex dye used is the unit surface area of the conductive support (1 m²) Is preferably from 0.01 to 100 mmol. The amount of the dye adsorbed on the semiconductor fine particles is preferably 0.01 to 1 mmol per 1 g of the semiconductor fine particles. By using such an amount of adsorption of the metal complex dye, a sensitization effect in a semiconductor can be sufficiently obtained. On the other hand, if the amount of the dye is too small, the sensitizing effect becomes insufficient, and if the amount of the dye is too large, the dye not attached to the semiconductor floats, which causes a reduction in the sensitizing effect.
[0139]
Two or more kinds of dyes can be mixed in order to make the wavelength range of photoelectric conversion as wide as possible and increase the conversion efficiency. In this case, it is preferable to select the dye to be mixed and the ratio thereof so as to match the wavelength range and intensity distribution of the light source. Specifically, two or more metal complex dyes of the present invention can be used in combination, or a metal complex dye of the present invention and a conventional metal complex dye and / or a polymethine dye can be used in combination.
[0140]
For the purpose of reducing the interaction between metal complex dyes such as association, a colorless compound may be co-adsorbed on the semiconductor fine particles. Examples of the hydrophobic compound to be co-adsorbed include steroid compounds having a carboxyl group (for example, chenodeoxycholic acid). An ultraviolet absorber can also be used in combination.
[0141]
For the purpose of promoting the removal of excess metal complex dye, the surface of the semiconductor fine particles may be treated with amines after adsorbing the metal complex 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.
[0142]
(C) Charge transfer layer
The charge transfer layer is a layer having a function of replenishing electrons to the oxidized metal complex dye. Typical materials that can be used for the charge transfer layer include a liquid (electrolyte) in which a redox couple is dissolved in an organic solvent, a so-called gel electrolyte in which a polymer matrix is impregnated with a liquid in which a redox couple is dissolved in an organic solvent, and oxidation. Examples thereof include a molten salt containing a reducing pair. Furthermore, a solid electrolyte or a hole transport material can also be used.
[0143]
The electrolytic solution used in the present invention preferably comprises an electrolyte, a solvent and an additive. As electrolyte, (a) I₂And iodide (LiI, NaI, KI, CsI, CaI₂(B) Br in combination with a metal iodide such as tetraalkylammonium iodide, pyridinium iodide, quaternary ammonium compounds such as imidazolium iodide, etc.₂And bromide (LiBr, NaBr, KBr, CsBr, CaBr₂(C) Metal complexes such as ferrocyanate-ferricyanate and ferrocene-ferricinium ions, etc., in combination with metal bromides such as tetrabromonium bromide, pyridinium bromide, and the like. (D) Sulfur compounds such as sodium polysulfide and alkylthiol-alkyldisulfides, (e) viologen dyes, hydroquinone-quinones and the like can be used. Above all, I₂An electrolyte in which LiI, a pyridinium iodide, an iodine salt of a quaternary ammonium compound such as imidazolium iodide is combined is preferable. The above electrolytes may be used as a mixture. The electrolyte was melted at room temperature as described in EP718288, WO95 / 18456, J. Electrochem. Soc., Vol.143, No. 10, 3099 (1996), Inorg. Chem., 35, 1168-1178 (1996). The salt (molten salt) can also be used. When using a molten salt as an electrolyte, the solvent may not be used.
[0144]
The preferable electrolyte concentration is 0.1 to 15M, more preferably 0.2 to 10M. Further, when iodine is added to the electrolyte, a preferable concentration of iodine is 0.01 to 0.5M.
[0145]
As the electrolyte solvent, it is desirable to use a compound that can exhibit excellent ionic conductivity because it has low viscosity and high ion mobility, or has a high dielectric constant and high effective carrier concentration, or both. . Examples of such solvents include the following.
[0146]
(A) Carbonates
For example, ethylene carbonate, propylene carbonate, vinylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, dipropyl carbonate and the like are preferable.
[0147]
(B) Lactones
For example, γ-butyrolactone, γ-valerolactone, γ-caprolactone, crotolactone, γ-caprolactone, δ-valerolactone and the like are preferable.
[0148]
(C) Ethers
For example, ethyl ether, 1,2-dimethoxyethane, diethoxyethane, trimethoxymethane, ethylene glycol dimethyl ether, polyethylene glycol dimethyl ether, 1,3-dioxolane, 1,4-dioxane and the like are preferable.
[0149]
(D) Alcohols
For example, methanol, ethanol, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, polyethylene glycol monoalkyl ether, polypropylene glycol monoalkyl ether and the like are preferable.
[0150]
(E) Glycols
For example, ethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol, glycerin and the like are preferable.
[0151]
(F) Glycol ethers
For example, ethylene glycol dialkyl ether, propylene glycol dialkyl ether, polyethylene glycol dialkyl ether, polypropylene glycol dialkyl ether and the like are preferable.
[0152]
(G) Tetrahydrofurans
For example, tetrahydrofuran, 2-methyltetrahydrofuran and the like are preferable.
[0153]
(H) Nitriles
For example, acetonitrile, glutarodinitrile, propionitrile, methoxyacetonitrile, benzonitrile and the like are preferable.
[0154]
(I) Carboxylic acid esters
For example, methyl formate, methyl acetate, ethyl acetate, methyl propionate and the like are preferable.
[0155]
(J) Phosphoric acid triesters
For example, trimethyl phosphate and triethyl phosphate are preferable.
[0156]
(K) Heterocyclic compounds
For example, N-methylpyrrolidone, 4-methyl-1,3-dioxane, 2-methyl-1,3-dioxolane, 3-methyl-2-oxazolidinone, 1,3-propane sultone, sulfolane and the like are preferable.
[0157]
(L) Other
Preferred are aprotic organic solvents such as dimethyl sulfoxide, formamide, N, N-dimethylformamide, nitromethane, and water.
[0158]
Of these, carbonate-based solvents, nitrile-based solvents, and heterocyclic compound-based solvents are preferable. These solvents may be used as a mixture of two or more if necessary.
[0159]
In the present invention, bases such as t-butylpyridine, 2-picoline, 2,6-lutidine and the like described in J. Am. Ceram. Soc., 80 (12), 3157-3171 (1997) Sexual compounds can also be added. A preferable concentration range when adding a basic compound is 0.05 to 2M.
[0160]
The electrolyte can be used after being gelled (solidified) by a method such as addition of a polymer or an oil gelling agent, polymerization of coexisting polyfunctional monomers, or a crosslinking reaction with the polymer. In the case of gelation by addition of a polymer, compounds described in “Polymer Electrolyte Reviews-1,2” (JR MacCaLLum and CA Vincent, ELSEIVER APPLIED SCIENCE) can be used, but in particular, polyacrylonitrile, polyfluoride. It is preferred to use vinylidene chloride. In the case of gelation by adding an oil gelling agent, J. Chem. Soc. Japan, Ind. Chem. Sec., 46, 779 (1943), J. Am. Chem. Soc., 111, 5542 (1989), J. Chem. Soc., Chem. Commun., 1993, 390, Angew. Chem. Int. Ed. Engl., 35, 1949 (1996), Chem. Lett., 1996, 885, J. Chem. Soc., Compounds described in Chem. Commun., 545 (1997) and the like can be used. Of these, preferred compounds are those having an amide structure in the molecular structure.
[0161]
When a gel electrolyte is formed by polymerization of polyfunctional monomers coexisting with the electrolyte, a solution is prepared from the polyfunctional monomers, polymerization initiator, electrolyte and solvent, and cast, coating, dipping, impregnation, etc. It is coated on the dye-sensitized semiconductor fine particle layer (photosensitive layer 20) by a method. As shown in FIG. 1, a method is preferred in which a gap between the dye-sensitized semiconductor fine particles 21 is filled with a sol-like electrolyte, a sol-like electrolyte layer is formed on the photosensitive layer 20, and then gelled by radical polymerization. .
[0162]
The polyfunctional monomer is preferably a compound having two or more ethylenically unsaturated groups, such as divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol. Ethylene glycol diacrylate, triethylene glycol dimethacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate and the like are preferable.
[0163]
The gel electrolyte may contain a monofunctional monomer in addition to the polyfunctional monomer. Examples of the monofunctional monomer include esters or amides derived from acrylic acid or α-alkyl acrylic acid (for example, methacrylic acid) (for example, N-isopropylacrylamide, acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, Derived from acrylamidopropyltrimethylammonium chloride, methyl acrylate, hydroxyethyl acrylate, N-propyl acrylate, N-butyl acrylate, 2-methoxyethyl acrylate, cyclohexyl acrylate, etc.), vinyl esters (eg vinyl acetate), maleic acid or fumaric acid Esters (eg dimethyl maleate, dibutyl maleate, diethyl fumarate, etc.), organic acid salts (eg sodium salt of maleic acid, fumaric acid or p-styrene sulfonic acid) ), Nitriles (acrylonitrile, methacrylonitrile, etc.), dienes (eg, butadiene, cyclopentadiene, isoprene, etc.), aromatic vinyl compounds (eg, styrene, p-chlorostyrene, sodium styrenesulfonate, etc.), nitrogen-containing complex Vinyl compounds having a ring, vinyl compounds having a quaternary ammonium salt, N-vinylformamide, N-vinyl-N-methylformamide, vinyl sulfonic acid, sodium vinyl sulfonate, vinylidene fluoride, vinylidene chloride, vinyl alkyl ether (For example, methyl vinyl ether), olefins (ethylene, propylene, 1-butene, isobutene, etc.), N-phenylmaleimide and the like are preferable. The ratio of the polyfunctional monomer to the total amount of the monomer is preferably 0.5 to 70% by weight, and more preferably 1.0 to 50% by weight.
[0164]
The above-mentioned monomers for gel electrolytes include “Experimental Methods for Polymer Synthesis” written by Takayuki Otsu and Masaaki Kinoshita (Chemical Doujin), “Lecture Polymerization Reaction Theory 1 Radical Polymerization (I)” (Chemical Doujinshi), etc. Can be polymerized by radical polymerization, which is a general polymer synthesis method described in 1). The radical polymerization of the gel electrolyte monomer can be carried out by heating, light, ultraviolet light, electron beam, or the like, or electrochemically, but it is particularly preferable to carry out radical polymerization by heating.
[0165]
When the crosslinked polymer is formed by heating, preferred polymerization initiators include, for example, 2,2′-azobis (isobutyronitrile), 2,2′-azobis (dimethylvaleronitrile), dimethyl 2,2′-azobis ( Azo initiators such as 2-methylpropionate) and peroxide initiators such as benzoyl peroxide. A preferable addition amount of the polymerization initiator is 0.01 to 20% by weight, more preferably 0.1 to 10% by weight, based on the total amount of monomers.
[0166]
The weight composition range of the monomers in the gel electrolyte is preferably 0.5 to 70% by weight, more preferably 1.0 to 50% by weight.
[0167]
When gelling an electrolyte by a polymer crosslinking reaction, it is desirable to use a polymer having a crosslinkable reactive group and a crosslinking agent in combination. Preferred crosslinkable reactive groups are nitrogen-containing heterocycles (eg, pyridine ring, imidazole ring, thiazole ring, oxazole ring, triazole ring, morpholine ring, piperidine ring, piperazine ring, etc.), and preferred crosslinkers are attached to the nitrogen atom. On the other hand, it is a bifunctional or higher functional reagent (for example, alkyl halide, halogenated aralkyl, sulfonate ester, acid anhydride, acid chloride, isocyanate, etc.) capable of electrophilic reaction.
[0168]
Organic and / or inorganic hole transport materials can also be used in place of the electrolyte. Examples of the organic hole transport material that can be preferably used in the present invention include the following.
[0169]
(A) Aromatic amines
N, N'-diphenyl-N, N'-bis (4-methoxyphenyl)-(1,1'-biphenyl) -4,4'-diamine (J. Hagen et al., Synthetic Metal, 89, 2153- 220, (1997)), 2,2 ', 7,7'-tetrakis (N, N-di-p-methoxyphenylamine) 9,9'-spirobifluorene (Nature, Vol.395, 8 Oct. 1998) , pp.583-585 and WO97 / 10617), an aromatic diamine compound in which a tertiary aromatic amine unit of 1,1-bis [4- (di-p-tolylamino) phenyl] cyclohexane is linked (Japanese Patent Laid-Open No. Sho 59- 194393), 4,4'-bis [(N-1-naphthyl) -N-phenylamino] biphenyl, which contains two or more tertiary amines and two or more condensed aromatic rings are nitrogen atoms Aromatic amines bonded to benzene (JP-A-5-34681), derivatives of triphenylbenzene having a starburst structure (US Pat. No. 4,923,774, JP-A-4-308688), N, N′-diphenyl -N, N'-bis (3-methylphenyl)-(1,1'-biphe ) Aromatic diamines such as 4,4′-diamine (US Pat. No. 4,764,625), α, α, α ′, α′-tetramethyl-α, α′-bis [4- (di-p-tolylamino) ) Phenyl] -p-xylene (Japanese Patent Laid-Open No. 3-269084), p-phenylenediamine derivative, triphenylamine derivative whose whole molecule is sterically asymmetric (Japanese Patent Laid-Open No. 4-129271), aromatic diamino group to pyrenyl group Are substituted compounds (Japanese Patent Laid-Open No. 4-175395), aromatic diamines having tertiary aromatic amine units linked with ethylene groups (Japanese Patent Laid-Open No. 4-264189), aromatic diamines having a styryl structure (Japanese Patent Laid-Open No. -290851), a benzylphenyl compound (JP-A-4-364153), a tertiary amine linked by a fluorene group (JP-A-554753), a triamine compound (JP-A-5-239455), bis (di Pyridylamino) biphenyl (JP-A-5-320634), N, N, N-triphenylamine derivatives (JP-A-6-1972) , Aromatic diamine (JP-A-7-138562) having a Fenokizajin structure, diaminophenyl phenanthridine derivatives (Japanese Patent Laid-Open No. 7-252474) or the like.
[0170]
(B) Oligothiophene compound
α-octylthiophene and α, ω-dihexyl-α-octylthiophene (Adv. Mater., Vol. 9, No. 7, 5578 (1997)), hexadodecyl dodecithiophene (Angew. Chem. Int. Ed. Engl , 34, No.3, 303-307 (1995)), 2,8-dihexylanthra [2,3-b: 6,7-b '] dithiophene (JACS, Vol.120, No.4, 664〜 672 (1998)).
[0171]
(C) Conductive polymer
Polypyrrole (K. Murakoshi et al., Chem. Lett., 1997, p.471), and polyacetylene and its derivatives, poly (p-phenylene) and its derivatives, poly (p-phenylenevinylene) and its derivatives, polythieny Lembinylene and its derivatives, polythiophene and its derivatives, polyaniline and its derivatives, and polytoluidine and its derivatives, etc. ("Handbook of Organic Conductive Molecules and Polymers", Vol.1-4 (by NALWA, published by WILEY) ing).
[0172]
In organic hole transport materials, tris (4-bromophenyl) aminium hexachloro is used to control the dopant level as described in Nature, Vol. 395, 8 Oct. 583-585 (1998). Li [(CF to add a compound containing a cation radical such as antimonate or to control the potential of the oxide semiconductor surface (compensation of the space charge layer)_ThreeSO₂)₂A salt such as N] may be added.
[0173]
The organic hole transport material can be introduced into the electrode by a technique such as a vacuum deposition method, a casting method, a coating method, a spin coating method, a dipping method, an electrolytic polymerization method, or a photoelectrolytic polymerization method. When a hole transport material is used instead of an electrolytic solution, a titanium dioxide thin film is used by a technique such as spray pyrolysis described in Electorochim. Acta, 40, 643 to 652 (1995) to prevent short circuit. The layer is preferably applied as an undercoat layer.
[0174]
When an inorganic solid compound is used instead of the electrolyte, copper iodide (p-CuI) (J. Phys. D: Appl. Phys., 31, 1492-1496 (1998)), copper thiocyanide (Thin Solid Films, 261 (1995), 307-310, J. Appl. Phys., 80 (8), 15 October 1996, 4749-4754, Chem. Mater., 1998, 10, 1501-1509, SemiCond. Sci. Technol., 10 , 1689-1693) can be introduced into the electrode by techniques such as casting, coating, spin coating, dipping, and electrolytic plating.
[0175]
The following two methods can be used to form the charge transfer layer. One is that a counter electrode is bonded to a dye-sensitized semiconductor fine particle layer via a spacer, and the open end of both is immersed in an electrolyte solution, so that the inside of the semiconductor fine particle layer and between the semiconductor fine particle layer and the counter electrode are In this method, the electrolyte solution is infiltrated into the gap. The other is a method of applying an electrolyte solution to the semiconductor fine particle layer so that the electrolyte solution penetrates into the semiconductor fine particle layer, forming a charge transfer layer on the semiconductor fine particle layer, and finally providing a counter electrode.
[0176]
In the former case, as a method of infiltrating the electrolyte solution into the gap between the semiconductor fine particle layer and the counter electrode, the atmospheric pressure method using capillary action and the upper open end of the semiconductor fine particle layer and the counter electrode (the one not immersed in the electrolyte solution) There is a decompression method that sucks up from the open end.
[0177]
In the latter case, a counter electrode is applied to the wet charge transfer layer without being dried, and measures for preventing liquid leakage at the edge portion are taken. In the case of a gel electrolyte, the counter electrode may be provided after being applied wet and solidified by a method such as polymerization, or may be solidified after providing the counter electrode. As a method of forming a layer of a wet organic hole transport material or a gel electrolyte in addition to the electrolytic solution, as in the case of the formation of a semiconductor fine particle layer and dye adsorption, a dipping method, a roller method, a dip method, an air knife method, The extrusion method, slide hopper method, wire bar method, spin method, spray method, casting method, various printing methods, etc. can be used. In the case of a solid electrolyte or a solid hole transport material, a charge transfer layer may be formed by a dry film forming process such as a vacuum deposition method or a CVD method, and then a counter electrode may be provided.
[0178]
In the case of an electrolyte solution or a wet hole transport material that cannot be solidified, it is preferable to seal the edge portion immediately after coating. In the case of a hole transport material that can be solidified, a hole transport layer is formed by wet application. After the film is formed, it is preferably solidified by a method such as photopolymerization or thermal radical polymerization. As described above, the film application method may be appropriately selected depending on the properties of the electrolytic solution and the process conditions.
[0179]
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.
[0180]
(D) Counter electrode
The counter electrode acts as a positive electrode of the photoelectrochemical cell when the photoelectric conversion element is a photoelectrochemical cell. Similar to the conductive support described above, the counter electrode may have a single-layer structure of a counter electrode conductive layer made of a conductive material, or may be composed of a counter electrode conductive layer and a support substrate. As a conductive material used for the counter electrode conductive layer, metals (for example, platinum, gold, silver, copper, aluminum, rhodium, indium, etc.), carbon, conductive metal oxide (indium-tin composite oxide, tin oxide doped with fluorine) Etc.). Examples of a preferable support substrate for the counter electrode are glass and plastic, and the above conductive material is applied or vapor-deposited thereon. The thickness of the counter electrode conductive layer is not particularly limited, but is preferably 3 nm to 10 μm. When the counter electrode conductive layer is made of metal, the thickness is preferably 5 μm or less, and more preferably in the range of 5 nm to 3 μm.
[0181]
Since light may be irradiated from either 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 may be substantially transparent. . From the viewpoint of improving the power generation efficiency, it is preferable to make the conductive support transparent so that light is incident from the conductive support side. In this case, the counter electrode preferably has a property of reflecting light. As such a counter electrode, glass or plastic on which a metal or a conductive oxide is deposited, or a metal thin film can be used.
[0182]
The procedure for providing the counter electrode support is as follows: (b) after forming the charge transfer layer and (b) after disposing the counter electrode on the dye-sensitized semiconductor fine particle layer via a spacer. There are two ways to fill the gap with the electrolyte solution. 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 having the conductive layer is attached. In the case of (b), the counter electrode is assembled and fixed on the dye-sensitized semiconductor fine particle layer via a spacer, and the open end of the obtained assembly is immersed in an electrolyte solution, utilizing capillary action or reduced pressure. The electrolyte solution is infiltrated into the gap between the dye-sensitized semiconductor fine particle layer and the counter electrode. At this time, when the electrolyte is a polymer electrolyte, it is crosslinked by heating or the like as necessary. Further, as in the case of the conductive support, it is preferable to use a metal lead for the purpose of reducing the resistance of the counter electrode, particularly when the counter electrode is 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 those for the conductive support.
[0183]
(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, but the simultaneous multilayer coating method is preferable from the viewpoint of productivity. In the simultaneous multilayer coating method, the slide hopper method and the extrusion method are suitable in view of productivity and coating film uniformity. For forming these functional layers, an evaporation method, a bonding method, or the like can be used depending on the material.
[0184]
(F) Specific example of internal structure of photoelectric conversion element
As described above, 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 9 illustrate the internal structure of a photoelectric conversion element that can be preferably applied to the present invention.
[0185]
In FIG. 2, a photosensitive layer 20 and a charge transfer layer 30 are interposed between a transparent conductive layer 10a and a transparent counter electrode conductive layer 40a, and light is incident from both sides. In FIG. 3, a part of the metal lead 11 is provided on the transparent substrate 50a, the transparent conductive layer 10a is further provided, the undercoat layer 60, the photosensitive layer 20, the charge transfer layer 30 and the counter electrode conductive layer 40 are provided in this order and further supported. A substrate 50 is disposed, and light is incident from the conductive layer side. In FIG. 4, 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 metal lead 11 is provided in part. The provided transparent substrate 50a is disposed with the metal lead 11 side inward, and has a structure in which light enters from the counter electrode side. In FIG. 5, the metal lead 11 is provided on each of the two transparent substrates 50a, and the undercoat layer 60, the photosensitive layer 20, and the charge transfer layer 30 are interposed between the transparent conductive layer 10a or the transparent counter electrode conductive layer 40a. In this structure, light enters from both sides. 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 electrode conductive layer 40 are provided, and a support substrate 50 is disposed thereon. In this structure, light enters from the conductive layer side. In FIG. 7, the conductive layer 10 is provided on the support substrate 50, the photosensitive layer 20 is provided via the undercoat layer 60, the charge transfer layer 30 and the transparent counter electrode conductive layer 40a are provided, and the transparent substrate 50a is disposed thereon. In this structure, light is incident from the counter electrode side. 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 substrate 50a is provided thereon. It is arranged and has a structure in which light enters from both sides. In FIG. 9, a conductive layer 10 is provided on a support substrate 50, a photosensitive layer 20 is provided via an undercoat layer 60, a solid charge transfer layer 30 is further provided, and a partially counter electrode conductive layer 40 or a metal lead 11 is provided thereon. It has a structure in which light is incident from the counter electrode side.
[0186]
[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.
[0187]
[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.
[0188]
The dye-sensitized solar cell of the present invention can basically have the same module structure as a conventional solar cell module. The solar cell module generally has a structure in which cells are formed on a support substrate such as metal or ceramic, and the cell is covered with a filling resin or protective glass, 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 for the support substrate, configure a cell thereon, and take in light from the transparent support substrate side. Specifically, a module structure called a super straight type, a substrate type, and a potting type, a substrate integrated module structure used in an amorphous silicon solar cell, and the like are known. The module structure of the dye-sensitized solar cell of the present invention can be appropriately selected depending on the purpose of use, the place of use and the environment.
[0189]
In a typical super straight type or substrate type module, cells are arranged at regular intervals between support substrates that are transparent on one or both sides and treated with antireflection, and adjacent cells are connected by metal leads or flexible wiring. The current collector electrode is connected to the outer edge portion, and the generated power is taken out to the outside. Various types of plastic materials such as ethylene vinyl acetate (EVA) may be used between the substrate and the cell in the form of a film or a filling resin depending on the purpose in order to protect the cell and improve the current collection efficiency. Also, when used in places where there is no need to cover the surface with a hard material, such as where there is little impact from the outside, the surface protective layer is made of a transparent plastic film, or the protective function is achieved by curing the filling resin. It is possible to eliminate the supporting substrate on one side. The periphery of the support substrate is fixed in a sandwich shape with a metal frame in order to ensure internal sealing and module rigidity, and a sealing material is hermetically sealed between the support substrate and the frame. Further, if a flexible material is used for the cell itself, the support substrate, the filling material, and the sealing material, a solar cell can be formed on the curved surface.
[0190]
Super straight type solar cell module, for example, while transporting the front substrate sent out from the substrate supply device by a belt conveyor etc., the cell is placed on it together with the lead wire for sealing material-cell connection, the back surface sealing material, etc. After sequentially laminating, a back substrate or a back cover can be placed and a frame can be set on the outer edge.
[0191]
On the other hand, in the case of the substrate type, while the supporting substrate sent from the substrate supply device is conveyed by a belt conveyor or the like, the cells are sequentially laminated together with the inter-cell connection lead wires, the sealing material, etc. It can be made by placing and setting a frame on the peripheral edge.
[0192]
FIG. 10 shows an example of a structure in which the photoelectric conversion element of the present invention is integrated into a substrate. FIG. 10 has a transparent conductive layer 10a on one surface of a transparent substrate 50a, and further a dye adsorbing TiO₂A cell having a photosensitive layer 20, containing a solid charge transfer layer 30, and a metal counter electrode conductive layer 40 is modularized, and the antireflection layer 70 is provided on the other surface of the substrate 50a. . In the case of such a structure, 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.
[0193]
In the case of the module having the structure shown in FIG. 10, selective plating, selective etching, CVD, PVD, etc. so that a transparent conductive layer, a photosensitive layer, a charge transfer layer, a counter electrode, etc. are arranged on a substrate at three-dimensional intervals. Desired by patterning using semiconductor process technology, laser scribing after pattern coating or wide coating, plasma CVM (described in Solar Energy Materials and Solar Cells, 48, p373-381), grinding, etc. A modular structure can be obtained.
[0194]
Other members and processes will be described in detail below.
[0195]
Sealing materials include liquid EVA (ethylene vinyl acetate), film-like EVA, and vinylidene fluoride depending on the purpose such as weather resistance, electrical insulation, light collection efficiency, and cell protection (impact resistance). Various materials such as a mixture of a polymer 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 can be mixed in the sealing material to increase strength and light transmittance.
[0196]
When the sealing material is fixed on the cell, a method suitable for the physical properties of the material is used. In the case of film-like materials, various methods such as heat adhesion after roll pressurization, heat adhesion after vacuum pressurization, etc., in the case of liquid or paste-like materials, various methods such as roll coat, bar coat, spray coat, screen printing, etc. are possible. is there.
[0197]
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.
[0198]
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.
[0199]
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.
[0200]
In order to increase power generation efficiency, it is most important to capture light into the module without loss. However, light that has passed through the photoelectric conversion layer and reached the inside is reflected and returned efficiently to the photoelectric conversion layer side. It is also important. As a method for increasing the light reflectivity, the support substrate surface is mirror-polished and then Ag or Al 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.
[0201]
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 and connection by a conductive flexible sheet are generally used, but a method of electrically connecting and fixing cells using a conductive adhesive tape or a conductive adhesive at the same time, conductive There is also a method of applying a pattern to the desired position of the hot melt.
[0202]
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.
[0203]
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.
[0204]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to them.
[0205]
1. Synthesis of metal complex dyes
Hereinafter, methods for synthesizing the metal complex dyes D-8, D-75, D-1, D-71, D-3, and D-73 of the present invention will be described.
[0206]
Embedded image
[0207]
Embedded image
[0208]
Embedded image
[0209]
(A) Synthesis of D-8
An aqueous solution prepared by dissolving 24.6 g (0.2 mol) of p-anisidine 1 and 20 ml of concentrated hydrochloric acid in 150 ml of water, and 39.7 g (0.24 mol) of chloral hydrate 2 and 250 g of sodium sulfate in 850 ml of water. In addition, an aqueous solution in which 49.7 g (0.71 mol) of hydroxylamine hydrochloride was dissolved in 600 ml of water was added, and the mixture was refluxed for 10 minutes. The aqueous solution was cooled, and the crystals were separated by filtration and washed with water to obtain 33.7 g of brown crystals of oxime 3 (yield 87%).
[0210]
17.5 g (90 mmol) of oxime 3 was dissolved in 100 ml of 90% sulfuric acid and heated and stirred at 80 ° C. for 10 minutes. After cooling, the mixture was poured into 2 liters of water and stirred, and the resulting crystals were collected by filtration and washed with water to obtain 5.0 g of methoxyisatin 4 crystals (yield 31%).
[0211]
To a mixture of 1.95 g (11 mmol) of methoxyisatin 4 and 1.21 g (10 mmol) of acetylpyridine 5, 5.5 g of NaOH 33% aqueous solution was dropped at 5 ° C., and the mixture was stirred at 5 ° C. for 1 hour and at 60 ° C. for 1 hour. . To this was added 10 ml of ice water, and the mixture was filtered and washed with ice water and acetone to obtain 1.12 g of crystals of pyridylquinoline 6 (yield 31%).
[0212]
0.60 g (2 mmol) of pyridylquinoline 6 and 0.26 g (1 mmol) of ruthenium chloride trihydrate were dissolved in 15 ml of dry N, N-dimethylformamide and refluxed in the dark for 8 hours under a nitrogen atmosphere. After concentration under reduced pressure, it was dispersed in acetonitrile and filtered to obtain 0.77 g of ruthenium complex 7 crystals (yield 99%).
[0213]
0.143 g (0.2 mmol) of ruthenium complex 7 and sodium thiocyanate 0.18 g (2.2 mmol) were dissolved in a mixed solvent of N, N-dimethylformamide 10 ml / water 3 ml and refluxed in the dark for 6 hours under a nitrogen atmosphere. . After concentration under reduced pressure, dissolve in water, add dilute nitric acid to precipitate crystals, filter, wash with water, and purify with Sephadex column LH-20 (developing solvent: methanol) to obtain 0.072 g of metal complex dye D-8. Obtained (yield 50%). The structure was confirmed by NMR spectrum.
[0214]
(B) Synthesis of D-75
0.12 g (0.2 mmol) of ruthenium complex 8 synthesized according to the method described in J. Chem. Soc., Dalton, 1973, 204 and 0.032 g (2.4 mmol) of sodium thiocyanate were added to 30 ml of N, N-dimethylformamide. The mixture was dissolved in a mixed solvent of 10 ml of water and refluxed in the dark for 2 hours under a nitrogen atmosphere. To this, 0.06 g (0.2 mmol) of pyridylquinoline 6 was added and refluxed for 6 hours, and further 15 ml of triethylamine was added and refluxed for 6 hours. Concentrate the reaction solution, dissolve in methanol and purify with Sephadex column LH-20 (developing solvent: methanol), concentrate and dissolve in water, add dilute nitric acid to precipitate crystals, filter and separate 0.060 g of metal Complex dye D-75 was obtained (yield 41%). The structure was confirmed by NMR spectrum.
[0215]
(C) Synthesis of D-1 and D-71
Pyridylquinoline 10 was synthesized in the same manner as the synthesis of pyridylquinoline 6 except that an equimolar amount of commercially available isatin 9 was used instead of methoxyisatin 4. Using this pyridylquinoline 10 in place of pyridylquinoline 6, metal complex dyes D-1 and D-71 were respectively synthesized in the same manner as the synthesis of D-8 and D-75. The structure was confirmed by NMR spectrum.
[0216]
(D) Synthesis of D-3 and D-73
Metal complex dyes D-3 and D-73 were respectively synthesized in the same manner as the synthesis of D-1 and D-71 except that 1/2 mole of sodium dithiocarbamate 11 was used instead of sodium thiocyanate. The structure was confirmed by NMR spectrum.
[0217]
(E) Synthesis of other dyes
Other metal complex dyes used in the following examples can be synthesized in the same manner as in the above synthesis examples by appropriately combining specific examples of each ligand. Each ligand can be easily obtained as a commercial product, or a literature such as Synth. Commun., 27, 2165 (1997), Aust. J. Chem., 25, 1631 (1972) or the like. Can be synthesized with reference to the cited references.
[0218]
2. Absorption spectrum measurement
Absorption spectra in methanol were measured for D-1, D-3, D-8, D-71, D-73, D-75 and Comparative Dye 1. Table 1 shows the absorption maximum wavelength and the long wavelength end.
[0219]
[Table 1]
[0220]
As is clear from Table 1, the absorption maximum wavelength of the metal complex dye of the present invention was longer and broader than that of the comparative dye 1. Therefore, it is very preferable to use the metal complex dye of the present invention for a photoelectrochemical cell because it can be spectrally sensitized to a longer wavelength light and converted into a photocurrent.
[0221]
3. Preparation of titanium dioxide dispersion
Inside a Teflon-coated stainless steel container with an inner volume of 200 ml, titanium dioxide (Nippon Aerosil Co., Ltd., Degussa P-25) 15 g, water 45 g, dispersant (Aldrich Triton X-100) 1 g, diameter 0.5 mm 30 g of zirconia beads (made by Nikkato Co., Ltd.) was added, and dispersion treatment was performed at 1500 rpm for 2 hours using a sand grinder mill (made by Imex Corporation). 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.
[0222]
4). TiO with adsorbed dye₂Electrode 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 above dispersion (semiconductor fine particle coating amount 20 g / m²). 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, methanol solutions of the metal complex dye and comparative dye 1 of the present invention (both 3 × 10^-Fourmol / l) for 15 hours. TiO dyed₂The electrode was immersed in 4-t-butylpyridine for 15 minutes, then washed with ethanol and air dried. The resulting photosensitive layer had a thickness of 10 μm.
[0223]
5). Production 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, using a capillary phenomenon in the gap between the two glasses, an electrolytic solution (3-methoxypropionitrile as electrolyte with 1-methyl-3-hexylimidazolium iodine salt (0.65 mol / l) and iodine (0.05 mol / l) l) and soak in TiO₂This was introduced into an electrode to obtain a photoelectrochemical cell. According to the present example, a conductive support layer (conducting a conductive layer 10a on a glass transparent substrate 50a), dye-sensitized TiO, as shown in FIG.₂A photoelectrochemical cell in which the photosensitive layer 20, the charge transfer layer 30 made of the above electrolyte, 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 sealant. .
[0224]
6). Measurement of photoelectric conversion wavelength and photoelectric conversion efficiency
The photoelectric conversion efficiency at 800 nm of the obtained photoelectric conversion element was measured by an IPCE (Incident Photon to Current Conversion Efficiency) measuring apparatus manufactured by Optel. Table 2 shows the photoelectric conversion efficiency of the photoelectrochemical cell using each metal complex dye.
[0225]
[Table 2]
[0226]
From Table 2, it can be seen that the comparative dye does not exhibit photoelectric conversion ability with respect to light of 800 nm, whereas the metal complex dye of the present invention exhibits good photoelectric conversion ability. Thus, all of the dyes of the present invention have high photoelectric conversion ability not only in the visible light but also in the infrared region.
[0227]
【The invention's effect】
As described above in detail, since the metal complex dye of the present invention has a good light absorption ability in a wide wavelength range from visible light to infrared, a photoelectric conversion element including semiconductor fine particles adsorbing such metal complex dye is It has high photoelectric conversion characteristics from visible light to infrared region. 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 a structure of a preferable photoelectric conversion element of the present invention.
FIG. 10 is a partial cross-sectional view showing an example of the structure of a substrate integrated solar cell module using the metal complex dye 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 ... Metal complex dye
23 ... Charge transport material
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 (4)

The following general formula (I):
M (LL ₁ ) _m1 (LL ₂ ) _m2 (X) _m3 · CI (I)
(However, M represents Ru, and LL ₁ represents the following general formula (II):
(However, R ₁ and R ₂ each independently represent a carboxyl group, R ₃ and R ₄ each independently represent a substituent, and at least one substituent of R ₄ is an alkoxy group or an amino group, And a2 each independently represents an integer of 0 to 4, the sum of a1 and a2 is 1 to 4, b1 represents an integer of 0 to 3, b2 represents an integer of 1 to 5. b1 is 2 or more. R ₃ may be the same or different and may be connected to each other to form a ring, and when b2 is 2 or more, R ₄ may be the same or different to form a ring by connecting to each other. When b1 and b2 are both 1 or more, R ₃ and R ₄ may be linked to form a ring.), LL ₂ represents the following general formula (IV-1) :
(However, R ₁₁ represents a carboxyl group, a sulfonic acid group, a hydroxyl group, a hydroxamic acid group, a phosphoryl group or a phosphonyl group, R ₁₉ represents a substituent, and R ₁₁ and R ₁₉ bind to any position on the ring. D1 represents an integer of 0 to 4, d9 represents an integer of 0 to 6, and when d1 is 2 or more, R ₁₁ may be the same or different, and when d9 is 2 or more, R ₁₉ May be the same or different and may be linked to each other to form a ring.) Represents a bidentate ligand represented by: X represents an acyloxy group, an acylthio group, a thioacyloxy group, a thioacylthio group , Acylaminooxy group, thiocarbamate group, dithiocarbamate group, thiocarbonate group, dithiocarbonate group, trithiocarbonate group, acyl group, thiocyanate group, isothiocyanate group, cyanate group, A monodentate or bidentate ligand coordinated by a group selected from the group consisting of a cyanate group, a cyano group, an alkylthio group, an arylthio group, an alkoxy group and an aryloxy group, or a halogen atom, carbonyl, dialkyl ketone, 1 Represents a monodentate or bidentate ligand consisting of 1,3-diketone, carbonamide, thiocarbonamide, thiourea or isothiourea, m1 represents an integer of _{1 to} 3, and when m1 is 2 or 3, LL ₁ is the same But may be different, m2 represents an integer of 0 to 2, m2 is or different and is LL ₂ when two identical, m3 represents an integer of 0 to 3, when m3 is 2 or 3 X may be the same or different, and X may be linked to each other, and CI represents a counter ion when a counter ion is necessary to neutralize the charge. A photoelectric conversion element comprising semiconductor fine particles sensitized by a metal complex dye represented by the formula: The photoelectric conversion element according to claim 1 , wherein the semiconductor fine particles are titanium oxide fine particles. A photoelectrochemical cell using the photoelectric conversion element according to claim 1 . The following general formula (I):
M (LL ₁ ) _m1 (LL ₂ ) _m2 (X) _m3 · CI (I)
(However, M is Ru, and LL ₁ is represented by the following general formula (II):
(However, R ₁ and R ₂ each independently represent a carboxyl group, R ₃ and R ₄ each independently represent a substituent, and at least one substituent of R ₄ is an alkoxy group or an amino group, And a2 each independently represents an integer of 0 to 4, the sum of a1 and a2 is 1 to 4, b1 represents an integer of 0 to 3, b2 represents an integer of 1 to 5. b1 is 2 or more. R ₃ may be the same or different and may be connected to each other to form a ring, and when b2 is 2 or more, R ₄ may be the same or different to form a ring by connecting to each other. When b1 and b2 are both 1 or more, R ₃ and R ₄ may be linked to form a ring.), LL ₂ represents the following general formula (IV-1) :
(However, R ₁₁ represents a carboxyl group, a sulfonic acid group, a hydroxyl group, a hydroxamic acid group, a phosphoryl group or a phosphonyl group, R ₁₉ represents a substituent, and R ₁₁ and R ₁₉ bind to any position on the ring. D1 represents an integer of 0 to 4, d9 represents an integer of 0 to 6, and when d1 is 2 or more, R ₁₁ may be the same or different, and when d9 is 2 or more, R ₁₉ May be the same or different and may be linked to each other to form a ring.) Represents a bidentate ligand represented by: X represents an acyloxy group, an acylthio group, a thioacyloxy group, a thioacylthio group , Acylaminooxy group, thiocarbamate group, dithiocarbamate group, thiocarbonate group, dithiocarbonate group, trithiocarbonate group, acyl group, thiocyanate group, isothiocyanate group, cyanate group, A monodentate or bidentate ligand coordinated by a group selected from the group consisting of a cyanate group, a cyano group, an alkylthio group, an arylthio group, an alkoxy group and an aryloxy group, or a halogen atom, carbonyl, dialkyl ketone, 1 Represents a monodentate or bidentate ligand consisting of 1,3-diketone, carbonamide, thiocarbonamide, thiourea or isothiourea, m1 is 1 or 2, and when m1 is 2, LL ₁ is the same or different M2 is 0 or 1, m3 represents an integer of 0 to 2, and when m3 is 2, X may be the same or different, and X may be connected to each other, m2 and m3 Are not simultaneously 0, and CI represents a counter ion when a counter ion is required to neutralize the charge. The metal complex pigment | dye characterized by these.