JP4874454B2 - Photoelectric conversion element and photovoltaic cell - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a metal complex dye exhibiting a high molar extinction coefficient and having an excellent light absorption ability even in a long wavelength region, a photoelectric conversion element using semiconductor fine particles sensitized with such a metal complex dye, and a photovoltaic cell comprising the same. .
[0002]
[Prior art]
Solar cells made of compounds such as single crystal silicon, polycrystalline silicon, amorphous silicon, cadmium telluride, and indium copper selenide have been put into practical use or the main research and development targets for solar 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. 4927721, 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 it is possible to provide an inexpensive photoelectric conversion element because an inexpensive oxide semiconductor such as titanium dioxide can be used without purification, and the second advantage is 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, the known ruthenium complex dye has a problem in that although visible light can be almost entirely photoelectrically converted, infrared light having a wavelength longer than 700 nm is hardly absorbed, and thus the photoelectric conversion ability in the infrared region is low. Therefore, in order to further increase the conversion efficiency, it is desired to develop a dye that has absorption ability in a wide wavelength range from visible light to infrared region and exhibits high photoelectric conversion ability.
[0005]
In addition, when applying a photoelectric conversion element to a solar battery or the like, it is possible to use a pseudo-solid electrolyte such as a molten salt or a gel electrolyte, or a solid electrolyte such as a polymer electrolyte or an inorganic semiconductor as an electrolyte. To preferred. At that time, in order to increase the photoelectric conversion efficiency, it is preferable to reduce the resistance of the electrolyte by thinning the photoelectric conversion element as much as possible. However, when a known ruthenium complex dye is used, the light absorption rate is low because the molar absorption coefficient is low. This results in a decrease in photoelectric conversion efficiency. Therefore, development of a metal complex dye that exhibits a high molar extinction coefficient even when it is thinned is desired.
[0006]
[Problems to be solved by the invention]
An object of the present invention is to use a metal complex dye that exhibits a high molar extinction coefficient, has an excellent light absorption ability even in a long wavelength region, and can efficiently sensitize semiconductor fine particles, and such a metal complex dye. It is to provide a photoelectric conversion element that exhibits high photoelectric conversion efficiency even when a solid or quasi-solid electrolyte is used as well as a wet electrolyte, and is excellent in durability, and a photovoltaic cell comprising the photoelectric conversion element.
[0007]
[Means for Solving the Problems]
As a result of diligent research in view of the above object, the present inventors coordinated a specific ligand capable of bidentate or tridentate coordination with a nitrogen atom with respect to a metal atom, and further, with a nitrogen atom, if necessary, 2 By coordinating other ligands that can be coordinated with a bidentate or tridentate and / or a monodentate or bidentate ligand coordinated with a thiocyanate group or an isothiocyanate group, a high molar extinction coefficient is exhibited. It is possible to obtain a metal complex dye having an excellent light absorption ability even in a wavelength region, and a photoelectric conversion element using semiconductor fine particles sensitized by such a metal complex dye is not only a wet electrolyte but also a solid or quasi-solid electrolyte. Even when used, the present invention shows high photoelectric conversion efficiency and excellent durability, and has been found to be a good photovoltaic cell.
[0008]
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 8]
(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, R_FiveAnd R₆Each independently represents an aryl group or a heterocyclic group, L₁And L₂Each independently represents a conjugated chain composed of a substituted or unsubstituted ethenylene group and / or ethynylene group, a1 and a2 each independently represent an integer of 0 to 3, 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, b1 and b2 each independently represent an integer of 0 to 3, and when b1 is 2 or more, R1_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 connected to each other to form a ring. When b1 and b2 are both 1 or more, R_ThreeAnd R_FourMay be linked to form a ring, and n represents 0 or 1. A bidentate or tridentate ligand represented by
LL₂Is the following general formula (III):
[Chemical 9]
(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). And
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 or thiourea,
m1 represents an integer of 1 to 3, LL when m1 is 2 or more₁Can be the same or different,
m2 represents an integer from 0 to 2, and when m2 is 2, LL₂Can be the same or different,
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,
CI represents a counter ion when a counter ion is required to neutralize the charge. And a semiconductor fine particle sensitized by a metal complex dye represented by the formula:
[0009]
The photovoltaic cell of the present invention is characterized by using the above photoelectric conversion element.
[0010]
The present invention also provides a photoelectric conversion element and a photovoltaic cell comprising semiconductor fine particles sensitized with a metal complex dye having a higher molar extinction coefficient and having a further excellent light absorption ability even in a long wavelength region by satisfying the following conditions. It is done.
[0011]
(1) M in the general formula (I) is preferably a metal capable of tetracoordinate or hexacoordinate, and Ru, Fe, Os, Cu, W, Cr, Mo, Ni, Pd, Pt, Co Ir, Rh, Re, Mn or Zn is more preferable, Ru, Fe, Os or Cu is particularly preferable, and Ru is most preferable.
[0012]
(2) R in general formula (II)₁And R₂Are preferably each independently a carboxyl group or a phosphonyl group.
[0013]
(3) R in general formula (II)_ThreeAnd R_FourEach independently represents an alkyl group, alkenyl group, alkynyl group, cycloalkyl group, alkoxy group, aryloxy group, amino group, acylamino group, sulfonamide group, aryl group, heterocyclic group, cyano group, alkoxycarbonyl group, carbamoyl group And preferably an acyloxy group or a halogen atom.
[0014]
(4) R in general formula (II)_FiveAnd R₆Are preferably each independently an aryl group.
[0015]
(5) L in general formula (II)₁And L₂Are preferably each independently an ethenylene group, a butadienylene group, an ethynylene group or a butadienylene group.
[0016]
(6) a1 in the general formula (II) is preferably 0 or 1, and a2 is preferably an integer of 0-2. In particular, when n is 0, a2 is preferably 1 or 2, and when n is 1, a2 is preferably 0 or 1.
[0017]
(7) LL in general formula (I)₁Is preferably a bidentate ligand.
[0018]
(8) LL in general formula (I)₁Is the following general formula (IV-1) or (IV-2):
[Chemical Formula 10]
(However, R₁, R₂And R₇Each independently represents a carboxyl group, a sulfonic acid group, a hydroxyl group, a hydroxamic acid group, a phosphoryl group or a phosphonyl group;_Three, R_Four, R₈, R₁₅And R₁₆Each independently represents a substituent, R₁₁~ R₁₄Each independently represents hydrogen, an alkyl group, an alkenyl group or an aryl group, and R₁₁And R₁₂And R₁₃And R₁₄May be linked to each other to form a ring, and a1, a2 and a3 each independently represents an integer of 0 to 3, 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, and when a3 is 2 or more, R₇May be the same or different, b1 and b2 each independently represent an integer of 0 to 3, and when b1 is 2 or more, R1_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 to each other to form a ring, b3 represents an integer of 0 to 5, and when b3 is 2 or more, R3₈May be the same or different and may be linked together to form a ring. When b1 and b2 in general formula (IV-1) are both 1 or more, R_ThreeAnd R_FourMay be linked to form a ring, and when b1 and b3 in general formula (IV-2) are both 1 or more, R_ThreeAnd R₈May be linked to form a ring, and d1 and d2 each independently represents an integer of 0 to 4, and when d1 is 1 or more, R₁₅Is R₁₁And / or R₁₂To form a ring, and when d1 is 2 or more, R₁₅May be the same or different and may be connected to each other to form a ring. When d2 is 1 or more, R₁₆Is R₁₃And / or R₁₄To form a ring, and when d2 is 2 or more, R₁₆May be the same or different and may be linked to each other to form a ring, and n represents 0 or 1. And bidentate or tridentate ligands.
[0019]
(9) R in general formula (IV-2)₇Is preferably a carboxyl group or a phosphoryl group, and a3 is preferably 1 or 2.
[0020]
(10) R in general formula (IV-2)₈Is preferably an alkyl group, alkenyl group, alkynyl group, cycloalkyl group, alkoxy group, aryloxy group, amino group or acylamino group.
[0021]
(11) R in the general formulas (IV-1) and (IV-2)₁₁~ R₁₄Are preferably each independently an alkyl group or an aryl group.
[0022]
(12) R in the general formulas (IV-1) and (IV-2)₁₁~ R₁₄More preferably, each independently represents an alkyl group.
[0023]
(13) R in the general formulas (IV-1) and (IV-2)₁₁And / or R₁₂Is particularly preferably an alkyl group substituted by an alkoxy group.
[0024]
(14) The 5- or 6-membered ring formed by Za, Zb and Zc in the general formula (III) is preferably independently a pyridine ring or an imidazole ring. These rings may be monocyclic or condensed.
[0025]
(15) c in the general formula (III) is preferably 0. Ie LL₂Is preferably a bidentate ligand.
[0026]
(16) LL in general formula (I)₂Are the following general formulas (V-1) to (V-8):
Embedded image
(However, R_{twenty one}~ R₂₈Each independently represents a carboxyl group, a sulfonic acid group, a hydroxyl group, a hydroxamic acid group, a phosphoryl group or a phosphonyl group;₂₉~ R₃₆Each independently represents a substituent, R_{twenty one}~ R₃₆Can be attached to any position on the ring, R₃₇~ R₄₁Each independently represents hydrogen, an alkyl group, an alkenyl group or an aryl group, e1 to e8, e13, e14 and e16 each independently represents an integer of 0 to 4, and e9 to e12 and e15 each independently represents 0 to 6 When e1-e8 is 2 or more, R_{twenty one}~ R₂₈May be the same or different, and when e9 to e16 are 2 or more, R₂₉~ R₃₆May be the same or different, and may be connected to each other to form a ring. ), And more preferably represented by the general formula (V-1), (V-2), (V-4) or (V-6). -1) or (V-2) is particularly preferable, and the general formula (V-1) is most preferable.
[0027]
(17) R in general formulas (V-1) to (V-8)_{twenty one}~ R₂₈Are preferably each independently a carboxyl group or a phosphonyl group.
[0028]
(18) R in the general formulas (V-1) to (V-8)₂₉~ R₃₆Are each independently 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.
[0029]
(19) m1 in the general formula (I) is preferably 1 or 2, and more preferably 1.
[0030]
(20) When m1 in the general formula (I) is 1, m2 is preferably 1, and m3 is preferably 1 or 2.
[0031]
(21) When m1 in the general formula (I) is 2, m2 is preferably 0 and m3 is preferably 1 or 2.
[0032]
(22) The metal complex dye represented by the general formula (I) preferably has at least one of a carboxyl group, a sulfonic acid group, a hydroxyl group, a hydroxamic acid group, a phosphoryl group, and a phosphonyl group.
[0033]
(23) The semiconductor fine particles are preferably titanium oxide fine particles.
[0034]
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 or tridentate ligand represented by the general formula (II),
LL₂Is a bidentate or tridentate ligand represented by any of the above general formulas (V-1) to (V-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 or thiourea,
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.
[0035]
In the metal complex dye according to the above preferred embodiment, LL₁Is preferably represented by the general formula (IV-1) or (IV-2),₂Is preferably represented by the general formula (V-1). In the general formulas (IV-1) and (IV-2), R₁₁And / or R₁₂Is preferably an alkyl group substituted by an alkoxy group, m1 is 1, m2 is 1, and m3 is preferably 1 or 2. The metal complex dye preferably has at least one of a carboxyl group, a sulfonic acid group, a hydroxyl group, a hydroxamic acid group, a phosphoryl group, and a phosphonyl group.
[0036]
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)
Is represented by Each component will be described in detail below.
[0037]
(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.
[0038]
(B) Ligand LL₁
Ligand LL₁Is the following general formula (II):
Embedded image
Is a bidentate or tridentate ligand, preferably a bidentate ligand. Ligand LL₁M1 representing the number of is an integer of 1 to 3, preferably 1 or 2, and more preferably 1. When m1 is 2 or more, LL₁May be the same or different.
[0039]
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. R₁And R₂May be substituted on any carbon atom on the pyridine ring.
[0040]
R in general formula (II)_ThreeAnd R_FourEach independently represents a substituent, preferably an alkyl group (preferably having 1 to 20 carbon atoms, for example, 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.),
Alkynyl group (preferably having 2 to 20 carbon atoms, such as ethynyl group, butadiynyl group, 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.),
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 2-pyridyl group, 4-pyridyl group, 2-imidazolyl group, 2-benzoimidazolyl group, 2-thiazolyl group, 2-oxazolyl group, etc.),
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 amino group, N, N-dimethylamino group, N, N-diethylamino group, N-ethylamino group, anilino group, etc.),
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.), more preferably an alkyl group, alkenyl group, aryl group, heterocyclic group, alkoxy group, aryloxy group, alkoxycarbonyl group, amino group , An acylamino group, a cyano group or a halogen atom, particularly preferably an alkyl group, an alkenyl group, a heterocyclic group, an alkoxy group, an alkoxycarbonyl group, an amino group, an acylamino group or a cyano group.
[0041]
Ligand LL₁When includes an alkyl group, an alkenyl group, or the like, they may be linear or branched and may be substituted or unsubstituted. Ligand LL₁When includes an aryl group, a heterocyclic group, etc., they may be monocyclic or condensed and may be substituted or unsubstituted.
[0042]
In general formula (II), R_FiveAnd R₆Are each independently an aryl group (preferably having 6 to 30 carbon atoms, such as a phenyl group, substituted phenyl group, naphthyl group, substituted naphthyl group, etc.) or a heterocyclic group (preferably having 1 to 30 carbon atoms, such as 2-thienyl. Group, 2-pyrrolyl group, 2-imidazolyl group, 1-imidazolyl group, 4-pyridyl group, 3-indolyl group), preferably an aryl group, more preferably 1 to 3 electron-donating groups. An aryl group. The electron donating group is an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an alkoxy group, an aryloxy group, an amino group, an acylamino group (preferred examples are R_ThreeAnd R_FourOr a hydroxyl group, more preferably an alkyl group, an alkoxy group, an amino group or a hydroxyl group, and particularly preferably an amino group. The electron donating group is preferably substituted at the 4-position. R_FiveAnd R₆May be the same or different, but are preferably the same.
[0043]
In general formula (II), L₁And L₂Each independently represents a conjugated chain comprising a substituted or unsubstituted ethenylene group and / or an ethynylene group. When the ethenylene group has a substituent, the substituent is preferably an alkyl group, and more preferably a methyl group. L₁And L₂Each independently is preferably a conjugated chain having 2 to 6 carbon atoms, more preferably an ethenylene group, a butadienylene group, an ethynylene group, a butadienylene group, a methylethenylene group or a dimethylethenylene group, more preferably an ethenylene group Alternatively, a butadienylene group is particularly preferable, and an ethenylene group is most preferable. L₁And L₂May be the same or different, but are preferably the same. When the conjugated chain includes a carbon-carbon double bond, each double bond may be a trans isomer, a cis isomer, or a mixture thereof.
[0044]
In general formula (II), n is 0 or 1, and a1 and a2 each independently represent an integer of 0 to 3. 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. a1 is preferably 0 or 1, and a2 is preferably an integer of 0 to 2. In particular, when n is 0, a2 is preferably 1 or 2, and when n is 1, a2 is preferably 0 or 1. The sum of a1 and a2 is preferably an integer of 0-2.
[0045]
In general formula (II), b1 and b2 each independently represent an integer of 0 to 3, preferably an integer of 0 to 2. When b1 is 2 or more, R_ThreeMay be the same or different and may be linked together to form a ring. R when b2 is 2 or more_FourMay be the same or different and may be linked together to form a ring. When b1 and b2 are both 1 or more, R_ThreeAnd R_FourMay be linked to form a ring. Preferable examples of the ring to be formed include a benzene ring, a pyridine ring, a thiophene ring, a pyrrole ring, a cyclohexane ring, a cyclopentane ring and the like.
[0046]
In the general formula (II), when the sum of a1 and a2 is 1 or more, that is, the ligand LL₁Is preferably at least one of a carboxyl group, a sulfonic acid group, a hydroxyl group, a hydroxamic acid group, a phosphoryl group and a phosphonyl group, m1 in the general formula (I) is preferably 2 or 3. It is more preferable that
[0047]
Ligand LL₁Is preferably the following general formula (IV-1) or (IV-2):
Embedded image
It is represented by In general formulas (IV-1) and (IV-2), R₁~ R_Four, A1, a2, b1, b2 and n are as defined in general formula (II).
[0048]
In general formulas (IV-1) and (IV-2), R₇Represents a carboxyl group, a sulfonic acid group, a hydroxyl group, a hydroxamic acid group, a phosphoryl group or a phosphonyl group, preferably a carboxyl group or a phosphoryl group, more preferably a carboxyl group.
[0049]
In general formulas (IV-1) and (IV-2), R₈Represents a substituent, preferably an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an alkoxy group, an aryloxy group, an amino group or an acylamino group (preferably the above examples are R_ThreeAnd R_FourAnd the like, more preferably an alkyl group, an alkoxy group, an amino group or an acylamino group.
[0050]
In general formulas (IV-1) and (IV-2), R₁₁~ R₁₄Each independently represents hydrogen, an alkyl group, an alkenyl group or an aryl group._ThreeAnd R_FourAs well as an alkyl group or an aryl group, more preferably an alkyl group. R₁₁~ R₁₄When is an alkyl group, it may further have a substituent, and as the substituent, an alkoxy group, a cyano group, an alkoxycarbonyl group or a carbonamido group is preferable, and an alkoxy group is particularly preferable. R₁₁And R₁₂And R₁₃And R₁₄May be linked to each other to form a ring, and the ring formed is preferably a pyrrolidine ring, piperidine ring, piperazine ring, morpholine ring or the like.
[0051]
In general formulas (IV-1) and (IV-2), R₁₅And R₁₆Each independently represents a substituent, preferably an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an alkoxy group, an aryloxy group, an amino group, an acylamino group (above preferred examples are the above R_ThreeAnd R_FourOr a hydroxyl group, more preferably an alkyl group, an alkoxy group, an amino group, or an acylamino group.
[0052]
In general formula (IV-2), a3 represents an integer of 0 to 3, preferably an integer of 0 to 2. When n is 0, a3 is preferably 1 or 2, and when n is 1, a3 is preferably 0 or 1. R when a3 is 2 or more₇May be the same or different.
[0053]
In general formulas (IV-1) and (IV-2), d1 and d2 each independently represents an integer of 0 to 4. When d1 is 1 or more R₁₅Is R₁₁And / or R₁₂To form a ring, and the formed ring is preferably a piperidine ring or a pyrrolidine ring. R when d1 is 2 or more₁₅May be the same or different and may be linked together to form a ring. R when d2 is 1 or more₁₆Is R₁₃And / or R₁₄To form a ring, and the formed ring is preferably a piperidine ring or a pyrrolidine ring. R when d2 is 2 or more₁₆May be the same or different and may be linked together to form a ring.
[0054]
In general formula (IV-2), b3 represents an integer of 0 to 5, preferably an integer of 0 to 3. When n is 0, b3 is preferably an integer of 1 to 3. R when b3 is 2 or more₈May be the same or different and may be linked to each other to form a ring. When b1 and b3 in general formula (IV-2) are both 1 or more R_ThreeAnd R₈May be linked to form a ring. As the ring formed, a benzene ring, a cyclopentane ring and a cyclohexane ring are preferable.
[0055]
Ligand LL₁Specific examples of these are shown below, but the present invention is not limited thereto.
[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]
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[0070]
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[0071]
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[0072]
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[0073]
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[0074]
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[0075]
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[0076]
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[0077]
(C) Ligand LL₂
In general formula (I), LL₂Represents a bidentate or tridentate ligand. 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.
[0078]
Ligand LL₂Is represented by the following general formula (III):
Embedded image
Is represented by
[0079]
In the general formula (III), Za, Zb and Zc each independently represent a nonmetallic atom group capable of forming a 5- or 6-membered ring. The 5- or 6-membered ring formed may be substituted or unsubstituted, and 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. Of these, an imidazole ring and a pyridine ring are more preferable.
[0080]
In the general formula (III), c represents 0 or 1. c is preferably 0, ie LL₂Is preferably a bidentate ligand.
[0081]
Ligand LL₂Are the following general formulas (V-1) to (V-8):
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And is more preferably represented by the general formula (V-1), (V-2), (V-4) or (V-6). It is particularly preferably represented by 1) or (V-2), and most preferably represented by the general formula (V-1).
[0082]
In general formulas (V-1) to (V-8), R_{twenty one}~ R₂₈Are 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.
[0083]
In general formulas (V-1) to (V-8), R₂₉~ R₃₆Each independently represents a substituent, preferably an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group, a heterocyclic group, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, an amino group, an acyl group, a sulfonamide group, an acyloxy group. Group, carbamoyl group, acylamino group, cyano group or halogen atom (above preferred examples are the above R_ThreeAnd R_FourMore preferably an alkyl group, an alkenyl group, an aryl group, a heterocyclic group, an alkoxy group, an alkoxycarbonyl group, an amino group, an acylamino group or a halogen atom, particularly preferably an alkyl group or an alkenyl group. , An alkoxy group, an alkoxycarbonyl group, an amino group or an acylamino group.
[0084]
In general formulas (V-1) to (V-8), R₃₇~ R₄₁Each independently represents hydrogen, an alkyl group, an alkenyl group or an aryl group._ThreeAnd R_FourAs in the case of. Ligand 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. R₃₇~ R₄₁Are each independently preferably an alkyl group, more preferably an alkyl group having a carboxyl group.
[0085]
In general formulas (V-1) to (V-8), R_{twenty one}~ R₃₆May be bonded to any position on the ring. E1 to e6 each independently represents an integer of 0 to 4, preferably 0 to 2, and e7 and e8 each independently represents an integer of 0 to 4, preferably 0 to 3. e9 to e12 and e15 each independently represents an integer of 0 to 6, and e13, e14 and e16 each independently represents an integer of 0 to 4. e9 to e16 are each independently preferably an integer of 0 to 3.
[0086]
R when e1 to e8 is 2 or more_{twenty one}~ R₂₈May be the same or different, and when e9 to e16 are 2 or more, R₂₉~ R₃₆May be the same or different, and may be connected to each other to form a ring.
[0087]
Ligand LL₂Specific examples of these are shown below, but the present invention is not limited thereto.
[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]
(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 2, preferably 1 or 2. When X is a monodentate ligand, m3 is preferably 2. When X is a bidentate ligand, m3 is preferably 1. When m3 is 2, Xs may be the same or different, and Xs may be linked together.
[0104]
The ligand X is an acyloxy group (preferably having 1 to 20 carbon atoms, for example, acetyloxy group, benzoyloxy group, salicylic acid group, glycyloxy group, N, N-dimethylglycyloxy 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 by 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, an iodine atom, etc.),
Carbonyl (... CO),
Dialkyl ketones (preferably having 3 to 20 carbon atoms such as acetone ((CH_Three)₂CO ...))
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 (tC_FourH₉C (O ...) CH = C (O-) tC_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), or
Thiourea (preferably having 1 to 20 carbon atoms, eg NH (...) = C (S-) NH₂, CH_ThreeN (…) ＝ C (S−) NHCH_Three, (CH_Three)₂N-C (S ...) N (CH_Three)₂Etc.). "..." indicates a coordination bond.
[0105]
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, A ligand coordinated by a group selected from the group consisting of an alkylthio 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, 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 or arylthio group, or Halogen atom, 1,3-diketone Is a ligand comprising thiourea, particularly 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 A ligand consisting of 1,3-diketone, most preferably a ligand coordinated with a group selected from the group consisting of a dithiocarbamate group, a thiocyanate group and an isothiocyanate group, or a 1,3-diketone Is a ligand. 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, etc. are included, they may be substituted or unsubstituted, and may be monocyclic or condensed.
[0106]
When X is a bidentate ligand, X is an acyloxy group, acylthio group, thioacyloxy group, thioacylthio group, acylaminooxy group, thiocarbamate group, dithiocarbamate group, thiocarbonate group, dithiocarbonate group, trithio A ligand coordinated by a group selected from the group consisting of a carbonate group, an acyl group, an alkylthio group, an arylthio group, an alkoxy group and an aryloxy group, or a 1,3-diketone, carbonamide, thiocarbonamide, or thio A ligand composed of urea is preferable. When X is a monodentate ligand, X is a ligand coordinated by 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 composed of a halogen atom, carbonyl, dialkyl ketone, or thiourea is preferred.
[0107]
Specific examples of the ligand X are shown below, but the present invention is not limited thereto. The structural formula shown below is just one of the many possible resonance structures, and the distinction between a covalent bond (shown by-) and a coordination bond (shown by ...) is also formal. It does not represent an absolute distinction.
[0108]
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[0109]
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[0110]
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[0111]
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[0112]
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[0113]
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[0114]
When M in the general formula (I) is a metal such as Cu, Pd, Pt or the like that prefers 4-coordination, m2 is preferably 0 and m1 is preferably 1 or 2, and when m1 is 1, m3 is 1. Or, it is preferably 2. When m1 is 2, m3 is preferably 0. For metals that prefer hexacoordination, m1 is preferably 1 or 2, when m1 is 1, m2 is preferably 1 or 2, more preferably 1, and when m2 is 1, m3 is It is preferably 1 or 2, and when m2 is 2, m3 is preferably 0. When m1 is 2, m2 is preferably 0 or 1, more preferably 0. When m2 is 0, m3 is preferably an integer from 0 to 2, and when m2 is 1, m3 is 0. Preferably there is. When m1 is 3, both m2 and m3 are preferably 0. Among these, m1 is 1, m2 is 1, m3 is 1 or 2, and LL₂Is particularly preferably a bidentate or tridentate ligand represented by the general formula (V-1).
[0115]
(E) Counter ion CI
CI in the general formula (I) represents a counter ion when a counter ion is necessary 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.
[0116]
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 (eg, fluoride ion, chloride ion, bromide ion, iodide ion, etc.), a substituted arylsulfonate ion (eg, p -Toluenesulfonic acid ion, p-chlorobenzenesulfonic acid ion, etc.), aryl disulfonic acid ion (for example, 1,3-benzenedisulfonic acid ion, 1,5-naphthalenedisulfonic acid ion, 2,6-naphthalenedisulfonic acid ion, etc.), Alkyl sulfate ion (for example, methyl sulfate ion), sulfate ion, thiocyanate ion, perchlorate ion, tetrafluoroborate ion, hexafluorophosphate ion, picrate ion, acetate ion, trifluoromethanesulfonate ion, etc. . 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.
[0117]
(F) linking group
The metal complex dye represented by the general formula (I) preferably has at least one suitable interlocking group for the surface of the semiconductor fine particles, more preferably 1 to 6, more preferably 1 to 4 It is particularly preferable to have one. 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).
[0118]
(G) Specific examples of metal complex dyes
The metal complex dye preferably has at least one of a carboxyl group, a sulfonic acid group, a hydroxyl group, a hydroxamic acid group, a phosphoryl group, and a phosphonyl group. Of the metal complex dyes represented by the general formula (I) of the present invention, particularly preferred are the following general formulas (VI):
Ru (LL₁)_m1(LL₂)_m2(X)_m3・ CI (VI)
(However, LL₁Is a bidentate or tridentate ligand represented by the general formula (II), preferably a ligand represented by the general formula (IV-1) or (IV-2),
LL₂Is a bidentate or tridentate ligand represented by any of the above general formulas (V-1) to (V-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 or thiourea,
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 In the general formulas (IV-1) and (IV-2), R₁₁And / or R₁₂Is preferably an alkyl group substituted by an alkoxy group, m1 is 1, m2 is 1, and m3 is preferably 1 or 2.
[0119]
Specific examples of the metal complex dye used in the present invention are shown below, but the present invention is not limited thereto. In addition, when the metal complex pigment | dye in the following specific example contains the ligand which has a proton dissociative group, this ligand may dissociate as needed and may discharge | release a proton.
[0120]
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[0121]
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[0122]
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[0123]
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[0124]
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[0125]
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[0126]
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[0127]
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[0128]
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[0129]
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[0130]
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[0131]
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[0132]
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[0133]
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[0134]
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[0135]
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[0136]
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[0137]
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[0138]
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[0139]
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[0140]
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[0141]
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[0142]
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[0143]
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[0144]
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[0145]
The metal complex dyes represented by the general formula (I) of the present invention are described in J. Am. Chem. Soc., 121, 4047 (1999), Can. J. Chem., 75, 318 (1997), Inorg. Chem. , 27, 4007 (1988) etc. and the methods cited in the literature can be used as a reference.
[0146]
[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 photovoltaic 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.
[0147]
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 photovoltaic cell, the electrons in the conductive layer 10 return to the oxidant such as the dye 22 through the counter electrode conductive layer 40 and the charge transfer layer 30 while working in the 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.
[0148]
(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.
[0149]
In the case of (1), a conductive layer having sufficient strength as metal and having conductivity is used.
[0150]
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.
[0151]
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 / □.
[0152]
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.
[0153]
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 tetraacetyl cellulose (TAC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), syndioctaic polystyrene (SPS), polyphenylene sulfide (PPS), polycarbonate (PC), polyarylate ( PAr), polysulfone (PSF), polyester sulfone (PES), polyetherimide (PEI), cyclic polyolefin, brominated phenoxy and the like. In order to ensure sufficient transparency, the amount of conductive metal oxide applied is 1 m of glass or plastic support.²The amount is preferably 0.01 to 100 g.
[0154]
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%.
[0155]
(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.
[0156]
(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.
[0157]
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. Sulfides, cadmium or lead selenides, cadmium tellurides 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.
[0158]
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.
[0159]
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.
[0160]
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.
[0161]
Two or more kinds of fine particles having different particle size distributions may be mixed. In this case, the average size of the small particles is preferably 5 nm or less. For the purpose of improving the light capture rate by scattering incident light, semiconductor particles having a large particle size, for example, about 300 nm may be mixed.
[0162]
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.
[0163]
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 the chemistry of Burnside et al. The method described in Materials, Vol. 10, No. 9, pages 2419-2425 is also preferable.
[0164]
(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.
[0165]
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.
[0166]
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.
[0167]
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.
[0168]
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.
[0169]
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 sequentially applied several times to several dozen times. Further, screen printing can be preferably used as long as it is sequentially overcoated.
[0170]
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 photovoltaic cell, the thickness of the semiconductor fine particle layer is preferably 0.5 to 30 μm, more preferably 1 to 25 μm. Semiconductor fine particle support 1m²The hit application amount is preferably 0.1 to 200 g, more preferably 1 to 50 g.
[0171]
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.
[0172]
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.
[0173]
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.
[0174]
(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.
[0175]
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.
[0176]
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.
[0177]
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.
[0178]
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.
[0179]
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.
[0180]
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.
[0181]
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.
[0182]
(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.
[0183]
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 described in EP718288, WO95 / 18456, J. Electrochem. Soc., Vol.143, No. 10, 3099 (1996), Inorg. Chem., 35, 1168-1178 (1996), etc. A state salt (molten salt) can also be used. When using a molten salt as an electrolyte, the solvent may not be used.
[0184]
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.
[0185]
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 increases effective carrier concentration, or both. . Examples of such solvents include the following.
[0186]
(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.
[0187]
(b) Lactones
For example, γ-butyrolactone, γ-valerolactone, γ-caprolactone, crotolactone, γ-caprolactone, δ-valerolactone and the like are preferable.
[0188]
(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.
[0189]
(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.
[0190]
(e) Glycols
For example, ethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol, glycerin and the like are preferable.
[0191]
(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.
[0192]
(g) Tetrahydrofurans
For example, tetrahydrofuran, 2-methyltetrahydrofuran and the like are preferable.
[0193]
(h) Nitriles
For example, acetonitrile, glutarodinitrile, propionitrile, methoxyacetonitrile, benzonitrile and the like are preferable.
[0194]
(i) Carboxylic acid esters
For example, methyl formate, methyl acetate, ethyl acetate, methyl propionate and the like are preferable.
[0195]
(j) Phosphoric triesters
For example, trimethyl phosphate and triethyl phosphate are preferable.
[0196]
(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.
[0197]
(l) Other
Preferred are aprotic organic solvents such as dimethyl sulfoxide, formamide, N, N-dimethylformamide, nitromethane, and water.
[0198]
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.
[0199]
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.
[0200]
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 and polyfluoride are used. 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.
[0201]
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. .
[0202]
The polyfunctional monomer is preferably a compound having two or more ethylenically unsaturated groups, such as divinylbenzene, ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol diacrylate, Triethylene glycol dimethacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate and the like are preferable.
[0203]
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.
[0204]
The above-mentioned monomers for gel electrolytes include “Experimental Methods for Polymer Synthesis” by Takayuki Otsu and Masaaki Kinoshita (Chemical Doujin), “Lecture Polymerization Reaction Theory 1 Radical Polymerization (I)” by Takatsu Otsu (Chemical Doujin), 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.
[0205]
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.
[0206]
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.
[0207]
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.
[0208]
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.
[0209]
(a) Aromatic amines
N, N'-diphenyl-N, N'-bis (4-methoxyphenyl)-(1,1'-biphenyl) -4,4'-diamine (J. Hagen et al., Synthetic Metal, 89, 215- 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), aromatic diamine compounds in which tertiary aromatic amine units of 1,1-bis [4- (di-p-tolylamino) phenyl] cyclohexane are linked (JP-A-59) -194393) and 2,4'-bis [(N-1-naphthyl) -N-phenylamino] biphenyl containing two or more tertiary amines and two or more condensed aromatic rings are nitrogen Aromatic amine bonded to an atom (Japanese Patent Laid-Open No. 5-234681), a derivative of triphenylbenzene and an aromatic triamine having a starburst structure (US Pat. No. 4,923,774, Japanese Patent Laid-Open No. 4-308688), N, N′— Diphenyl-N, N'-bis (3-methylphenyl)-(1,1'-bif Nyl) -4,4′-diamine and other aromatic diamines (US Pat. No. 4764625), 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 diamines having a phenoxazine structure (JP-A-7-138562), diaminophenylphenanthridine derivatives (JP-A-7-252474) and the like.
[0210]
(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)).
[0211]
(c) Conductive polymer
Polypyrrole (K. Murakoshi et al., Chem. Lett., 1997, p. 471), polyacetylene and its derivatives, poly (p-phenylene) and its derivatives, poly (p-phenylene vinylene) and its derivatives, polythienylene Vinylene and its derivatives, polythiophene and its derivatives, polyaniline and its derivatives, polytoluidine and its derivatives, etc. (described in “Handbook of Organic Conductive Molecules and Polymers”, Vol. 1-4 (written by NALWA, published by WILEY)).
[0212]
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.
[0213]
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 electrolyte, a titanium dioxide thin film is used to prevent a short circuit by using a technique such as spray pyrolysis described in Electorochim. Acta, 40, 643-652 (1995). The layer is preferably applied as an undercoat layer.
[0214]
When inorganic solid compounds are used instead of electrolytes, copper iodide (p-CuI) (J. Phys. D: Appl. Phys., 31, 1492-1496 (1998)), copper thiocyanide (Thin Solid Films, 261, 307-310 (1995), J. Appl. Phys., 80 (8), 15 October 1996, 4749-4754, Chem. Mater., 10, 1501-1509, (1998), SemiCond. Sci. Technol. , 10, 1689-1693) can be introduced into the electrode by techniques such as casting, coating, spin coating, dipping, and electrolytic plating.
[0215]
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.
[0216]
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.
[0217]
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.
[0218]
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 process conditions.
[0219]
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.
[0220]
(D) Counter electrode
The counter electrode functions as a positive electrode of the photovoltaic cell when the photoelectric conversion element is a photovoltaic 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.
[0221]
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.
[0222]
The procedure for providing the counter electrode support is as follows: (a) when the charge transfer layer is formed and then provided thereon; and (b) after the counter electrode is disposed 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, and capillary action or reduced pressure is used. 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.
[0223]
(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.
[0224]
(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.
[0225]
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. FIG. 5 shows that an undercoat layer 60, a photosensitive layer 20, and a charge transfer layer 30 are provided between two transparent substrates 50a each having a metal lead 11 and a transparent conductive layer 10a or a 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.
[0226]
[3] Photocell
The photovoltaic cell of the present invention is one in which the photoelectric conversion element is caused to work in an external circuit. When the charge transfer layer is an ion conductive electrolyte, it is characterized as a type of photoelectrochemical cell. In order to prevent deterioration of components and volatilization of the contents of the photovoltaic 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.
[0227]
[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.
[0228]
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.
[0229]
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.
[0230]
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.
[0231]
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.
[0232]
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.
[0233]
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 by mechanical processing methods such as semiconductor processing technology, laser scribing after pattern coating or wide coating, plasma CVM (described in Solar Energy Materials and Solar Cells, 48, p 373-381), grinding, etc. The module structure can be obtained.
[0234]
Other members and processes will be described in detail below.
[0235]
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.
[0236]
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.
[0237]
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.
[0238]
In order to increase the power generation efficiency, an antireflection treatment may be applied to the surface of the substrate (generally tempered glass) on the light intake side of the module. Examples of the antireflection treatment method include a method of laminating an antireflection film and a method of coating an antireflection layer.
[0239]
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.
[0240]
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.
[0241]
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.
[0242]
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.
[0243]
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.
[0244]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to them.
[0245]
Example 1
Synthesis of metal complex dyes
Hereinafter, methods for synthesizing the metal complex dyes D-1, D-82, D-2, D-85, D-45 and D-92 represented by the general formula (I) will be described.
[0246]
Embedded image
[0247]
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[0248]
Embedded image
[0249]
[Chemical Formula 86]
[0250]
(A) Synthesis of D-1
8 ml (0.057 mol) of diisopropylamine was dissolved in 16 ml of dry tetrahydrofuran (THF), and 35.2 ml (0.056 mol) of n-butyllithium hexane solution (concentration: 1.6 mol / l) while maintaining the reaction solution at 0 ° C. in a nitrogen atmosphere. ) Was added dropwise and stirred at 0 ° C. for 20 minutes to prepare LDA. A solution prepared by dissolving 4.0 g (0.0217 mol) of 4,4′-dimethylbipyridine 1 in 80 ml of dry THF was added dropwise to the reaction solution while keeping the reaction solution at 0 ° C., and the mixture was stirred at 0 ° C. for 75 minutes. Next, a solution prepared by dissolving 7.64 g (0.0432 mol) of aldehyde 2 in 80 ml of dry THF was added dropwise while keeping the reaction solution at 0 ° C., and stirred at 0 ° C. for 75 minutes and at room temperature for 5 hours. 8 ml of methanol was added to the resulting solution, followed by 80 ml of water, and the precipitated crystals were collected by filtration, washed with water, and recrystallized from benzene to obtain 6.9 g of alcohol 3 crystals (yield 66%).
[0251]
6.76 g (14 mmol) of alcohol 3 was dissolved in 170 ml of 10% aqueous sulfuric acid solution and stirred at 90 ° C. for 2 hours. This aqueous solution was cooled, neutralized with an aqueous sodium hydroxide solution (concentration 1 mol / l), extracted three times with methylene chloride, and washed with water. The resulting methylene chloride solution was dried over magnesium sulfate, concentrated, dispersed in a methylene chloride-methanol mixed solvent, and filtered to obtain 5.3 g of yellow crystals of bis (dimethylaminostyryl) bipyridine 4 (yield 85%).
[0252]
0.97 g (2 mmol) of ruthenium complex 5 and 0.9 g of bis (dimethylaminostyryl) bipyridine 4 were dissolved in 20 ml of chloroform and refluxed for 4 hours. After concentration under reduced pressure, an acetone-diethyl ether mixture was added, and the resulting crystals were filtered off and washed with ether to obtain 1.54 g of ruthenium complex 6 (99% yield). The ruthenium complex 5 was synthesized with reference to the method described in J. Chem. Soc., Dalton, 1973, 204.
[0253]
0.155 g (0.2 mmol) of ruthenium complex 6 and 0.0324 g (0.4 mmol) of sodium thiocyanate were dissolved in a mixed solvent of 30 ml of DMF and 10 ml of water and refluxed for 2 hours in a dark place under a nitrogen atmosphere. Next, 0.045 g (0.2 mmol) of bipyridine-4,4′-dicarboxylic acid 7 was added to the reaction solution and refluxed for 6 hours. The obtained solution was concentrated, dispersed in methanol, and filtered to obtain 0.046 g of crystals of metal complex dye D-1 (yield 50%). The structure was confirmed by NMR spectrum.
[0254]
(B) Synthesis of D-82
0.1257 g (0.2 mmol) of the ruthenium complex 8 and 0.179 g of the bis (dimethylaminostyryl) bipyridine 4 obtained as described above were dissolved in a mixed solution of 10 ml of ethanol and 10 ml of water, and a dark atmosphere in a nitrogen atmosphere. At reflux for 10 hours. This solution was concentrated, dissolved in methanol, and purified with a Sephadex LH-20 column (developing solvent: methanol) to obtain 0.12 g of a metal complex dye D-82 (yield 46%). The structure was confirmed by NMR spectrum. The ruthenium complex 8 was synthesized with reference to the method described in J. Chem. Soc., Dalton, 1973, 204.
[0255]
(C) Synthesis of D-2
Alcohol 10 was synthesized in the same manner as the synthesis of alcohol 3 except that equimolar aldehyde 9 was used instead of aldehyde 2. A metal complex dye D-2 was synthesized in the same manner as the synthesis of the metal complex dye D-1 except that this alcohol 10 was used in place of the alcohol 3. The structure was confirmed by NMR spectrum.
[0256]
Synthesis of (D) D-85
A metal complex dye D-85 was synthesized in the same manner as in the synthesis of the metal complex dye D-82 except that alcohol 10 was used in place of the alcohol 3. The structure was confirmed by NMR spectrum.
[0257]
Synthesis of (E) D-45
6.76 g (50 mmol) of 2-acetyl-4-picoline 11, 6.76 g (50 mmol) of acetylaniline 12 and 0.5 ml of 20% aqueous sodium hydroxide solution were dissolved in 300 ml of ethanol and refluxed for 10 hours under a nitrogen atmosphere. The obtained solution was concentrated and purified by silica gel column chromatography (developing solvent: ethyl acetate / hexane = 1/4) to obtain 7.7 g of crystals of dimethylpyridylquinoline 13 (yield 66%). 2-acetyl-4-picoline 11 was synthesized by the method described in J. Am. Chem. Soc., 119, 5609 (1997).
[0258]
Alcohol 14 was synthesized in the same manner as in the synthesis of alcohol 3 except that equimolar dimethylpyridylquinoline 13 was used in place of 4,4′-dimethylbipyridine 1. A metal complex dye D-45 was synthesized in the same manner as in the synthesis of the metal complex dye D-1, except that this alcohol 14 was used in place of the alcohol 3. The structure was confirmed by NMR spectrum.
[0259]
(F) Synthesis of D-92
A metal complex dye D-92 was synthesized in the same manner as in the synthesis of the metal complex dye D-82 except that alcohol 14 was used instead of alcohol 3. The structure was confirmed by NMR spectrum.
[0260]
(G) Synthesis of other metal complex dyes
Other than the above, the metal complex dye represented by the general formula (I) can also be synthesized in the same manner as in the above synthesis examples by appropriately combining specific examples of each ligand. In addition, each ligand is easily available as a commercial product, or J. Am. Chem. Soc., 121, 4047 (1999), Can. J. Chem., 75, 318 (1997), Inorg Chem., 27, 4007 (1988) etc. or their cited references can be used as a reference.
[0261]
Example 2
Absorption spectrum measurement
The metal complex dyes D-1, D-2, D-45, D-82, D-85 and D-92 represented by the general formula (I) and Comparative dye 1 and Comparative dye 2 in methanol Absorption spectrum was measured. The measurement results of the maximum absorption wavelength are shown in Table 1.
[0262]
[Table 1]
[0263]
Table 1 shows that the maximum absorption wavelength of the metal complex dye represented by the general formula (I) of the present invention is longer and broader than those of the comparative dye 1 and the comparative dye 2. Therefore, it is very preferable to use a metal complex dye represented by the general formula (I) in a photovoltaic cell because it can be spectrally sensitized to a longer wavelength light and converted into a photocurrent. Furthermore, the molar extinction coefficients of the metal complex dyes D-1 and D-82 are 53000 and 56000, respectively, which are 3 to 4 times larger than those of the comparative dye 1 (molar extinction coefficient: 14000). Therefore, the photovoltaic cell using the metal complex dye represented by the general formula (I) is expected to be advantageous in terms of photoelectric conversion efficiency because of a small decrease in light absorption rate when the electrode is thinned.
[0264]
Example 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.
[0265]
Example 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 (amount of semiconductor fine particles applied: 3 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, the metal complex dye represented by the general formula (I) of the present invention and a methanol solution of each of the comparative dyes (both 3 × 10^-Fourmol / l) for 15 hours. In some cases, chenodeoxycholic acid is added to a methanol solution of the dye 4 × 10^-3It added so that it might become the concentration of mol / l. 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 1.8 μm.
[0266]
Example 5
Production of photovoltaic cells
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 TiO₂It was introduced into an electrode to obtain a photovoltaic cell. According to this example, as shown in FIG. 1, a conductive support layer made of conductive glass (with a conductive layer 10a formed on a glass transparent substrate 50a), dye-sensitized TiO₂A photovoltaic cell was produced 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.
[0267]
Example 6
Measurement of photoelectric conversion wavelength and photoelectric conversion efficiency in wet electrolyte system
The photoelectric conversion efficiency at 400 to 800 nm of the photovoltaic cell obtained as described above was measured by an IPCE (Incident Photon to Current Conversion Efficiency) measuring apparatus manufactured by Optel. Table 2 summarizes the photoelectric conversion efficiency (IPCE) at 800 nm and the maximum value (IPCE max) of the photoelectric conversion efficiency at 400 to 800 nm of the photovoltaic cell using each metal complex dye. IPCE measurement was performed at room temperature.
[0268]
[Table 2]
[0269]
From Table 2, since the comparative dye 1 does not have the ability to absorb light at 800 nm, the photovoltaic cell using the comparative dye 1 does not show the photoelectric conversion ability, whereas the metal represented by the general formula (I) of the present invention. It can be seen that any of the photovoltaic cells using the complex dye exhibits good photoelectric conversion efficiency, and in particular, by using a dye having an ethyleneoxy group, even more excellent photoelectric conversion efficiency can be obtained. Moreover, it was confirmed that photoelectric conversion efficiency improves by addition of chenodeoxycholic acid. Since the comparative dye 1 has a low molar extinction coefficient, the 1.8 μm electrode has low light absorption and low IPCE, whereas the metal complex dye of the present invention exhibits a high molar extinction coefficient. Shows high IPCE.
[0270]
Example 7
Measurement of photoelectric conversion efficiency in molten salt electrolyte system
Using the molten salt electrolyte (E-1 / E-2 = 7/3) composed of the following salts E-1 and E-2 as a charge transporting material, a photovoltaic cell was prepared in the same manner as in Example 5 and subjected to IPCE measurement. Except that the temperature was changed to 50 ° C., the maximum value (IPCE max) of the photoelectric conversion efficiency at 400 to 800 nm was measured in the same manner as in Example 6 above. Table 3 shows the measurement results.
[0271]
[Table 3]
[0272]
From Table 3, the photovoltaic cell using the metal complex dye represented by the general formula (I) of the present invention exhibits good photoelectric conversion efficiency even when a molten salt electrolyte is used, and the dye having an ethyleneoxy group is used. It can be seen that the photoelectric conversion efficiency of the used photovoltaic cell is particularly high.
[0273]
【The invention's effect】
As described above in detail, since the metal complex dye represented by the general formula (I) of the present invention has a good light absorption ability from the visible light to the infrared region, it contains semiconductor fine particles adsorbing such a metal complex dye. The photoelectric conversion element exhibits high photoelectric conversion characteristics in a wide wavelength range from visible light to infrared. A photovoltaic 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 (5)

The following general formula (I):
M (LL ₁ ) _m1 (LL ₂ ) _m2 (X) _m3・ CI ・ ・ ・ (I)
(Where M represents Ru ,
LL ₁ is represented by the following general formula (IV-1) or (IV-2):
(However, R ₁ , R ₂ and R ₇ represent a carboxyl group, R ₃ , R ₄ , R ₈ , R ₁₅ and R ₁₆ each independently represent a substituent, and R _{11 to} R ₁₄ each independently represent an alkyl group. Each of R ₁₁ and R ₁₂ and R ₁₃ and R ₁₄ may be linked to each other to form a ring; a1, a2 and a3 each independently represents an integer of 0 to 3; R ₁ may be the same or different when is 2 or more, R ₂ may be the same or different when a2 is 2 or more, R ₇ may be the same or different when a3 is 2 or more , b1 and b2 each independently represents an integer of 0 to 3, the R ₃ when b1 is 2 or more may be bonded to each other to form a ring may be the same or different, when b2 is 2 or more R ₄ may be the same or different and may be connected to each other to form a ring. B3 represents an integer of 0 to 5, and when b3 is 2 or more, R ₈ is the same. They may be the same or different from each other and may be connected to each other to form a ring. When b1 and b2 in general formula (IV-1) are both 1 or more, R ₃ and R ₄ are connected to form a ring. And when b1 and b3 in general formula (IV-2) are both 1 or more, R ₃ and R ₈ may be linked to form a ring, and d1 and d2 are each independently from 0 to 4 Represents an integer, and when d1 is 1 or more, R ₁₅ may be linked to R ₁₁ and / or R ₁₂ to form a ring, and when d1 is 2 or more, R ₁₅ may be the same or different and linked together. May form a ring, and when d2 is 1 or more, R ₁₆ may be linked to R ₁₃ and / or R ₁₄ to form a ring, and when d2 is 2 or more, R ₁₆ is the same or different. They may be linked to each other to form a ring, and n represents 0 or 1).
LL ₂ is represented by the following general formulas (V-1) to (V-8):
(However, R _{21 to} R ₂₈ each independently represents a carboxyl group or a phosphonyl group, R _{29 to} R ₃₆ each independently represents a substituent, and R _{21 to} R ₃₆ are bonded to any position on the ring. R _{37 to} R ₄₁ each independently represent hydrogen, an alkyl group, an alkenyl group or an aryl group, e1 to e8 each independently represents an integer of 0 to 4, and e13, e14 and e16 each independently represents 0. represents to 4 integer, an integer of e9~e12 and e15 are each independently 0 to 6, when e1~e8 is 2 or more, may be in R ₂₁ to R ₂₈ be the same or different, respectively, E9～ When e16 is 2 or more, R _{29 to} R ₃₆ may be the same or different and may be linked to each other to form a ring.) A bidentate or tridentate ligand represented by any one of And
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 or thiourea,
m1 represents an integer of 1 to 3, and when m1 is 2 or more, LL ₁ may be the same or different,
m2 represents an integer of 0 to 2, and when m2 is 2, LL ₂ may be the same or different,
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,
CI represents a counter ion when a counter ion is required to neutralize the charge. ) Is represented by the photoelectric conversion element, which comprises a sensitized semiconductor fine particles by either at least one Yusuke that metal complex dye of the carboxyl group and a phosphonyl group. The photoelectric conversion device according to claim 1 , wherein R ₁₁ and / or R ₁₂ in the general formulas (IV-1) and (IV-2) are alkyl groups substituted with alkoxy groups. Conversion element. 3. The photoelectric conversion device according to claim 1, wherein m1 in the general formula (I) is 1, m2 is 1, m3 is 1 or 2, and LL ₂ is the general formula (V-1 A photoelectric conversion element characterized by being a bidentate or tridentate ligand represented by: The photoelectric conversion element according to claim 1 , wherein the semiconductor fine particles are titanium oxide fine particles. A photovoltaic cell using the photoelectric conversion element according to claim 1 .