JP4497395B2 - Method for producing photoelectric conversion element and photoelectric conversion element - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a photoelectric conversion element, and more particularly to a method for producing a photoelectric conversion element using semiconductor fine particles sensitized with a dye, a photoelectric conversion element produced by this method, and a photovoltaic cell using this photoelectric conversion element.
[0002]
[Prior art]
Photoelectric conversion elements are used in various photosensors, copiers, photovoltaic devices, and the like. Various systems such as those using metals, semiconductors, organic pigments and dyes, or combinations thereof have been put to practical use as photoelectric conversion elements.
[0003]
U.S. Pat. A photoelectric conversion element using a sensed semiconductor fine particle (hereinafter referred to as “dye-sensitized photoelectric conversion element”), a material for producing the photoelectric conversion element, and a manufacturing technique are disclosed. The advantage of this dye-sensitized photoelectric conversion element is that an inexpensive oxide semiconductor such as titanium dioxide can be used without being purified to a high purity, so that it can be produced at a relatively low cost. However, such a photoelectric conversion element does not necessarily have a sufficiently high conversion efficiency, and further improvement in conversion efficiency is desired.
[0004]
Japanese Patent Application Laid-Open No. 1-220380 describes that the conversion efficiency of a dye-sensitized photoelectric conversion element is improved by post-treating semiconductor fine particles adsorbed with a dye with t-butylpyridine. However, this photoelectric conversion element does not necessarily have a sufficiently high conversion efficiency.
[0005]
[Problems to be solved by the invention]
The objective of this invention is providing the preparation method of the dye-sensitized photoelectric conversion element which shows the outstanding conversion efficiency, the photoelectric conversion element created by this method, and the photovoltaic cell using this photoelectric conversion element.
[0006]
[Means for Solving the Problems]
The method for producing a photoelectric conversion element of the present invention is a method for producing a photoelectric conversion element having a layer of semiconductor fine particles adsorbed with a dye and a conductive support, and the semiconductor fine particles are represented by the following general formula (I) It is characterized by treating with a compound.
(A₁-L)_n1-A₂・ M (I)
In general formula (I), A₁IsN ^- Group havingRepresents A₂IsPyridyl group or imidazolyl groupWhere M is (A₁-L)_n1-A₂Represents a cation that neutralizes the negative charge of L, L represents a divalent linking group or a simple bond, and n1 represents an integer of 1 to 3.
[0007]
In the above general formula (I),A ₂ Is particularly preferably a pyridyl group.
[0008]
In the method for producing a photoelectric conversion element of the present invention, it is preferable to treat the semiconductor fine particles with a compound represented by the general formula (I) and a compound represented by the following general formula (II).
[Chemical 2]
In general formula (II), X isOxygen atomRepresents R¹And R²Each independently represents a hydrogen atom, aliphatic hydrocarbon group, aryl group, heterocyclic group, -OR^Four, -N (R^Five) (R⁶), -C (= O) R⁷, -C (= S) R⁸Or SO₂R⁹Y represents a hydrogen atom, an aliphatic hydrocarbon group, an aryl group, a heterocyclic group, -OR^Four, -N (R^Five) (R⁶) Or -SR^TenRepresents. R^ThreeRepresents a hydrogen atom, an aliphatic hydrocarbon group, a hydroxy group or an alkoxy group, and R^FourRepresents a hydrogen atom or an aliphatic hydrocarbon group, R^FiveAnd R⁶Is R¹And R²Is synonymous with R⁷, R⁸And R⁹Is synonymous with Y and R^TenIs R^FourIt is synonymous with.
[0009]
In the above general formula (II)Y-N (R^Five) (R⁶) Is particularly preferred. In addition, the compound represented by the general formula (II) is -Si (R¹¹) (R¹²) (R¹³It is particularly preferred to have a substituent represented by However, R¹¹, R¹²And R¹³Each independently represents a hydroxy group, an alkyloxy group, an isocyanate group, a halogen atom or an aliphatic hydrocarbon group;¹¹, R¹²And R¹³At least one of them is an alkyloxy group, an isocyanate group or a halogen atom.
[0010]
It is particularly preferable to treat the compound represented by the general formula (I) and / or the compound represented by the general formula (II) after adsorbing the dye to the semiconductor fine particles. The dye is particularly preferably a ruthenium complex dye.
[0011]
The photoelectric conversion element of the present invention is produced by the production method of the present invention, and the photovoltaic cell of the present invention comprises the photoelectric conversion element.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The method for producing a photoelectric conversion element of the present invention is a method for producing a photoelectric conversion element having a photosensitive layer and a conductive support, and the photosensitive layer comprises semiconductor fine particles adsorbed with a dye. In the method of the present invention, the conversion efficiency of the photoelectric conversion element is improved by treating the semiconductor fine particles with a compound represented by the general formula (I) described later. In the present invention, the semiconductor fine particles are preferably treated with a compound represented by the general formula (I) and a compound represented by the general formula (II) described later. Hereinafter, in the present invention, the compound represented by the general formula (I) is referred to as “compound (I)”, and the compound represented by the general formula (II) is referred to as “compound (II)”.
[0013]
[I] Compound (I)
The general formula (I) is shown below.
(A₁-L)_n1-A₂・ M (I)
[0014]
In general formula (I),A ₁ Is N ^- It is group which has.A₁Is more preferably RSO₂N^--, RSO₂N^-SO₂-, RCON^--, RCON^-CO- or RSO₂N^-CO-, particularly preferably RSO₂N^--That's it.
[0015]
R and R ′ each represent a hydrogen atom or a substituent, and may be the same or different from each other. Examples of the substituent include an aliphatic hydrocarbon group, an aryl group, a heterocyclic group, amino Group, hydroxy group, alkyloxy group and the like.
Specific examples of the aliphatic hydrocarbon group represented by R and R ′ include a linear or branched unsubstituted alkyl group having 1 to 18 carbon atoms (methyl group, ethyl group, i-propyl group, n-propyl group, n -Butyl, t-butyl, 2-pentyl, n-hexyl, n-octyl, t-octyl, 2-ethylhexyl, 1,5-dimethylhexyl, n-decyl, n-dodecyl Group, n-tetradecyl group, n-hexadecyl group, n-octadecyl group, etc.) linear or branched substituted alkyl group having 1 to 18 carbon atoms (trifluoromethyl group, trifluoroethyl group, tetrafluoroethyl group, penta Fluoroethyl group, perfluorobutyl group, methoxycarbonylmethyl group, n-butoxypropyl group, methoxyethoxyethyl group, polyethoxyethyl group, acetyloxyethyl group, methylthiopropyl group, 3- (N-ethylureido) propyl group ), C3-C18 substituted or unsubstituted cyclic alkyl group (cyclopropyl group, cyclopentyl group, cyclohexyl group, cyclooctyl group, adamantyl group, cyclododecyl group, etc.), C2-C16 alkenyl group (allyl) Group, 2-butenyl group, 3-pentenyl group, etc.), C2-C10 alkynyl group (propargyl group, 3-pentynyl group, etc.), C6-C16 aralkyl group (benzyl group, etc.) and the like. .
Specific examples of the aryl group represented by R and R ′ include a substituted or unsubstituted phenyl group having 6 to 20 carbon atoms (phenyl group, methylphenyl group, octylphenyl group, cyanophenyl group, ethoxycarbonylphenyl group, trifluoro Methylphenyl group, pentafluorophenyl group, methoxycarbonylphenyl group, butoxyphenyl group, etc.), substituted or unsubstituted naphthyl groups (naphthyl group, 4-sulfonaphthyl group, etc.) and the like.
Specific examples of the heterocyclic group represented by R and R ′ include a substituted or unsubstituted nitrogen-containing hetero 5-membered ring group, a substituted or unsubstituted nitrogen-containing hetero 6-membered ring group (such as a triazino group), a furyl group, and thiofuryl. Groups and the like.
Specific examples of the amino group represented by R and R ′ include a dimethylamino group.
Specific examples of the alkyloxy group represented by R and R ′ include an ethyloxy group and a methyloxy group.
Among these, R and R ′ are each preferably a substituted or unsubstituted alkyl group or a substituted or unsubstituted phenyl group, and particularly preferably an alkyl group substituted with at least one fluorine atom. .
[0016]
In general formula (I), A₂IsPyridyl group or imidazolyl groupRepresents.Of these, a pyridyl group is particularly preferable. A ₂ Is(A₁-L)_n1It may have a substituent other than-.
[0017]
In general formula (I), M is (A₁-L)_n1-A₂Represents a cation that neutralizes the negative charge. Examples of such cations include alkali metal cations (lithium cations, sodium cations, potassium cations, rubidium cations, cesium cations, etc.), alkaline earth metal cations (magnesium cations, calcium cations, strontium cations, etc.), substituted or unsubstituted Ammonium cation (unsubstituted ammonium cation, triethylammonium cation, tetramethylammonium cation, tetra-n-butylammonium cation, tetra-n-hexylammonium cation, eryltrimethylammonium cation, etc.), substituted or unsubstituted imidazolium cation (1 , 3-dimethylimidazolium cation, 1-ethyl-3-methylimidazolium cation, 1-butyl-3-methylimidazolium cation, 2,3-dimethyl-1-propylimid Tetrazolium cation), a substituted or unsubstituted pyridinium cation (N- methylpyridinium cation, 4-phenyl pyridinium cation, etc.) and the like. M is preferably an alkali metal cation, alkaline earth metal cation, quaternary ammonium cation, imidazolium cation or pyridinium cation, more preferably an alkali metal cation or imidazolium cation, particularly preferably a lithium cation or 1,3 -Dialkylimidazolium cation. M represents the type and number of cations.For example, (A₁-L)_n1-A₂Has a negative valence of 1 and the cation type is Mg²⁺M is `` 1/2 (Mg<sup>2+</sup>) ”.
[0018]
In general formula (I), L represents a divalent linking group or a simple bond. Examples of the divalent linking group include a substituted or unsubstituted linear or branched alkylene group having 1 to 18 carbon atoms (methylene group, ethylene group, trimethylene group, tetramethylene group, isopropylene group, tetrafluoroethylene group, etc. ), An oxyalkylene group having 1 to 18 carbon atoms (-CH<sub>2</sub>CH<sub>2</sub>OCH<sub>2</sub>CH<sub>2</sub>-, -CH<sub>2</sub>CH<sub>2</sub>OCH<sub>2</sub>CH<sub>2</sub>OCH<sub>2</sub>CH<sub>2</sub>-, Etc.), C1-C18 alkyleneoxy and phenyleneoxy groups (-CH<sub>2</sub>CH<sub>2</sub>O-, -CH<sub>2</sub>CH<sub>2</sub>CH<sub>2</sub>O-, -CH<sub>2</sub>CH<sub>2</sub>OCH<sub>2</sub>CH<sub>2</sub>O-, -PhO-, etc.), an alkyleneamino group having 1 to 18 carbon atoms and a phenyleneamino group (-(CH<sub>2</sub>CH<sub>2</sub>)<sub>2</sub>N-,-(OCH<sub>2</sub>CH<sub>2</sub>)<sub>2</sub>N-, -PhNH-, etc.), an alkylenethio group having 1 to 18 carbon atoms or a phenylenethio group (-CH<sub>2</sub>CH<sub>2</sub>S-, -CH<sub>2</sub>CH<sub>2</sub>CH<sub>2</sub>S-, -CH<sub>2</sub>CH<sub>2</sub>OCH<sub>2</sub>CH<sub>2</sub>CH<sub>2</sub>S-, -PhS-, etc.), substituted or unsubstituted phenylene group having 6 to 20 carbon atoms, sulfamoyl linking group (-SO<sub>2</sub>NH-), carbamoyl linking group (-CONH-), amide linking group (-NHCO-), sulfonamide linking group (-NHSO<sub>2</sub>-), Ureido linking group (-NHCONH-), thioureido linking group (-NHCSNH-), urethane linking group (-OCONH-), thiourethane linking group (-OCSNH-), oxycarbonyl linking group (-OCO-), Carbonyloxy linking group (-CO<sub>2</sub>-), A heterocyclic linking group, a combination thereof, and the like. L is preferably an alkylene group having 1 to 6 carbon atoms or a simple bond, particularly preferably a simple bond.
[0019]
In general formula (I), (A<sub>1</sub>N1 which shows the number of -L) is an integer of 1-3. n1 is preferably 1.
[0020]
In general formula (I), A<sub>1</sub>ButN <sup>-</sup> Group havingAnd A<sub>2</sub>ButPyridyl group or imidazolyl groupIt is preferable that M is an alkali metal cation or an imidazolium cation, L is a simple bond, and n1 is 1. In addition, A<sub>1</sub>Is R<sub>1</sub>SO<sub>2</sub>N<sup>-</sup>-(R<sub>1</sub>Represents an alkyl group substituted with at least one fluorine atom), and A<sub>2</sub>Is particularly preferably a pyridyl group, M is a lithium cation or an imidazolium cation, L is a simple bond, and n1 is 1.
[0021]
Specific examples of compound (I) are shown below, but the present invention is not limited thereto.
[0022]
[Chemical Formula 3]
[0023]
[Formula 4]
[0024]
[Chemical formula 5]
[0025]
[Chemical 6]
[0026]
[Chemical 7]
[0028]
Compound (I) can be easily synthesized by applying a known method. For example A<sub>1</sub>Is N<sup>-</sup>Nucleophilic substitution reaction of amines or amides and electrophilic agents (acid halides, acid anhydrides, alkyl halides, halogen-substituted heterocyclic compounds, etc.), amines or amides and acids (carboxylic acids, etc.) By preparing a amide, imide, or the like by a condensation reaction with the compound, adding a base (alkali metal hydroxide, etc.) to this, or performing cation exchange to form a salt, compound (I) can be easily and highly enhanced. The yield can be obtained.
[0029]
[II] Compound (II)
In the method for producing a photoelectric conversion element of the present invention, it is preferable to treat the semiconductor fine particles with the compound (I) and the compound (II) represented by the following general formula (II).
[Chemical 9]
[0030]
In general formula (II), X isOxygen atomRepresents.
[0031]
In general formula (II), R<sup>1</sup>And R<sup>2</sup>Each independently represents a hydrogen atom, aliphatic hydrocarbon group, aryl group, heterocyclic group, -OR<sup>Four</sup>, -N (R<sup>Five</sup>) (R<sup>6</sup>), -C (= O) R<sup>7</sup>, -C (= S) R<sup>8</sup>Or SO<sub>2</sub>R<sup>9</sup>Represents. Where R<sup>Four</sup>And R<sup>Ten</sup>Each represents a hydrogen atom or an aliphatic hydrocarbon group, R<sup>Five</sup>And R<sup>6</sup>Is R<sup>1</sup>And R<sup>2</sup>Is synonymous with R<sup>7</sup>, R<sup>8</sup>And R<sup>9</sup>Is synonymous with Y described later.
[0032]
R<sup>1</sup>And R<sup>2</sup>When represents an aliphatic hydrocarbon group, examples thereof include a linear or branched unsubstituted alkyl group having 1 to 30 carbon atoms (for example, a methyl group, an ethyl group, an i-propyl group, an n-propyl group, an n-butyl group). Group, t-butyl group, 2-pentyl group, n-hexyl group, n-octyl group, t-octyl group, 2-ethylhexyl group, 1,5-dimethylhexyl group, n-decyl group, n-dodecyl group, n-tetradecyl group, n-hexadecyl group, n-octadecyl group, etc.), linear or branched substituted alkyl group having 1 to 30 carbon atoms (for example, N, N-dimethylaminopropyl group, trifluoroethyl group, tri-n) -Hexylammoniumpropyl group, pyridylpropyl group, triethoxysilylpropyl group, trimethoxysilylpropyl group, trichlorosilylmethyl group, carboxymethyl group, sulfoethyl group, sulfomethyl group, phosphopropyl group, dimethoxyphos Propyl group, n-butoxypropyl group, methoxyethoxyethyl group, polyethoxyethyl group, acetyloxyethyl group, methylthiopropyl group, 3- (N-ethylureido) propyl group, etc.), substituted or non-substituted with 3 to 18 carbon atoms A substituted cyclic alkyl group (for example, cyclopropyl group, cyclopentyl group, cyclohexyl group, cyclooctyl group, adamantyl group, cyclododecyl group, etc.), alkenyl group having 2 to 16 carbon atoms (for example, allyl group, 2-butenyl group, 3- Pentenyl group and the like), alkynyl groups having 2 to 10 carbon atoms (for example, propargyl group, 3-pentynyl group and the like), aralkyl groups having 6 to 16 carbon atoms (for example, benzyl group and the like), and the like.
R<sup>1</sup>And R<sup>2</sup>In the case where represents an aryl group, examples thereof include a substituted or unsubstituted phenyl group having 6 to 30 carbon atoms (for example, an unsubstituted phenyl group, a methylphenyl group, an octylphenyl group, a cyanophenyl group, an ethoxycarbonylphenyl group, a diethylphosphoryl group). Methylphenyl group, sulfophenyl group, dimethylaminophenyl group, trimethoxysilylphenyl group, trifluoromethylphenyl group, carboxyphenyl group, butoxyphenyl group, etc.), naphthyl group (for example, unsubstituted naphthyl group, 4-sulfonaphthyl group, etc.) ) And the like.
R<sup>1</sup>And R<sup>2</sup>When represents a heterocyclic group, examples thereof include a substituted or unsubstituted nitrogen-containing hetero 5-membered ring (eg, imidazolyl group, benzoimidazolyl group, pyrrole group, etc.), a substituted or unsubstituted nitrogen-containing hetero 6-membered ring (eg, pyridyl). Group, quinolyl group, pyrimidyl group, triazino group, morpholino group and the like), furyl group, thiofuryl group and the like.
R<sup>1</sup>And R<sup>2</sup>-OR<sup>Four</sup>Represents R<sup>Four</sup>Examples of the aliphatic hydrocarbon group represented by<sup>1</sup>And R<sup>2</sup>The thing similar to the example of the aliphatic hydrocarbon group which represents is mentioned. R<sup>1</sup>And R<sup>2</sup>-N (R<sup>Five</sup>) (R<sup>6</sup>) For R<sup>Five</sup>And R<sup>6</sup>Is R<sup>1</sup>And R<sup>2</sup>And -C (= O) R<sup>7</sup>, -C (= S) R<sup>8</sup>And SO<sub>2</sub>R<sup>9</sup>R for representing<sup>7</sup>, R<sup>8</sup>And R<sup>9</sup>Is synonymous with Y shown below.
[0033]
R<sup>1</sup>And R<sup>2</sup>Are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted phenyl group having 6 to 20 carbon atoms, a nitrogen-containing heterocyclic group, -N (R<sup>Five</sup>) (R<sup>6</sup>), -C (= O) R<sup>7</sup>Or SO<sub>2</sub>R<sup>9</sup>It is preferably a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 18 carbon atoms, a substituted or unsubstituted phenyl group having 6 to 18 carbon atoms, or a nitrogen-containing hetero 6-membered ring, more preferably a hydrogen atom And particularly preferably a substituted or unsubstituted alkyl group having 1 to 16 carbon atoms or a substituted or unsubstituted phenyl group having 6 to 16 carbon atoms, R<sup>1</sup>Represents a hydrogen atom and R<sup>2</sup>Is most preferably a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 16 carbon atoms, or a substituted or unsubstituted phenyl group having 6 to 16 carbon atoms.
[0034]
In the general formula (II), Y is a hydrogen atom, an aliphatic hydrocarbon group, an aryl group, a heterocyclic group, -OR<sup>Four</sup>, -N (R<sup>Five</sup>) (R<sup>6</sup>) Or -SR<sup>Ten</sup>Represents. Aliphatic hydrocarbon group represented by Y, aryl group, heterocyclic group, -OR<sup>Four</sup>, -N (R<sup>Five</sup>) (R<sup>6</sup>) As an example of R<sup>1</sup>And R<sup>2</sup>The same thing as the example of is mentioned. -SR<sup>Ten</sup>R for representing<sup>Ten</sup>Is R above<sup>Four</sup>It is synonymous with.
[0035]
Y is a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 16 carbon atoms, a substituted or unsubstituted phenyl group having 6 to 16 carbon atoms, a nitrogen-containing heterocyclic group, or -N (R<sup>Five</sup>) (R<sup>6</sup>Is preferably a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted phenyl group having 6 to 12 carbon atoms, a nitrogen-containing hetero 6-membered ring, or -N (R<sup>Five</sup>) (R<sup>6</sup>), More preferably -N (R<sup>Five</sup>) (R<sup>6</sup>Is particularly preferred, -NH<sub>2</sub>Most preferably, is represented.
[0036]
In addition, X, Y, R in the general formula (II)<sup>1</sup>And R<sup>2</sup>May be linked to each other to form a ring.
[0037]
Preferred R<sup>Five</sup>And R<sup>6</sup>As above, R<sup>1</sup>And R<sup>2</sup>The same as the preferred examples of<sup>7</sup>, R<sup>8</sup>And R<sup>9</sup>Are the same as the preferred examples of Y above.
[0039]
The compound (II) used in the present invention isR <sup>1</sup> , R <sup>2</sup> And / or Y may have a substituent.Preferred examples of the substituent include -C (= O) OR ', -P (= O) (OR')<sub>2</sub>, -S (= O) OR ', -OR', -B (OR ')<sub>2</sub>, -Si (R<sup>11</sup>) (R<sup>12</sup>) (R<sup>13</sup>) And the like. R ′ each independently represents a hydrogen atom or an aliphatic hydrocarbon group (for example, a methyl group, an ethyl group, etc.);<sup>11</sup>, R<sup>12</sup>And R<sup>13</sup>Are each independently a hydroxy group, an alkyloxy group (eg, methoxy group, ethoxy group, i-propyl group, etc.), an isocyanate group, a halogen atom (eg, chlorine atom), or an aliphatic hydrocarbon group (eg, methyl group, ethyl group, etc.) ) And R<sup>11</sup>, R<sup>12</sup>And R<sup>13</sup>At least one of them is an alkyloxy group, an isocyanate group or a halogen atom. More preferred substituents include -C (= O) OR ', -P (= O) (OR')<sub>2</sub>And -Si (R<sup>11</sup>) (R<sup>12</sup>) (R<sup>13</sup>And particularly preferably -Si (R<sup>11</sup>) (R<sup>12</sup>) (R<sup>13</sup>).
[0040]
Further, when the compound (II) has a charge, it may have an anion or cation as a counter ion for neutralizing the charge. The anion or cation is not particularly limited, and may be an organic ion or an inorganic ion. Typical examples of anions include halide ions (fluoride ions, chloride ions, bromide ions, iodide ions), perchlorate ions, tetrafluoroborate ions, hexafluorophosphate ions, acetate ions, Fluoroacetate ion, methanesulfonate ion, p-toluenesulfonate ion, trifluoromethanesulfonate ion, bis (trifluoroethanesulfonyl) imide ion, tris (trifluoromethanesulfonyl) methide ion, etc. (Lithium ions, sodium ions, potassium ions, etc.), alkaline earth metal ions (magnesium ions, calcium ions, etc.), substituted or unsubstituted ammonium ions (unsubstituted ammonium ions, triethylammonium ions, etc.) , Tetramethylammonium ions, etc.), substituted or unsubstituted pyridinium ions (unsubstituted pyridinium ions, 4-phenylpyridinium ions, etc.), substituted or unsubstituted imidazolium ions (N-methylimidazolium ions, etc.), etc. It is done.
[0041]
Specific examples of compound (II) preferably used in the present invention are shown below, but the present invention is not limited thereto.
[0042]
[Chemical Formula 10]
[0043]
Embedded image
[0044]
Embedded image
[0045]
Embedded image
[0046]
[III] Treatment method
(A) Treatment method using only compound (I)
Here, `` treatment '' means an operation of bringing semiconductor fine particles and compound (I) into contact for a certain period of time before installing the charge transport layer, and even if compound (I) is adsorbed on the semiconductor fine particles after contact, It may not be adsorbed. Further, the semiconductor fine particles to be subjected to the treatment may be in any state in the process of producing the photoelectric conversion element, but it is preferable to perform the treatment after the formation of the semiconductor fine particle film, and to adsorb the dye to the semiconductor fine particles. It is particularly preferable that the treatment is performed after the treatment. On the other hand, the compound (I) to be treated is preferably used as a solution dissolved in a solvent (hereinafter referred to as a treatment solution) or a dispersed dispersion (hereinafter referred to as a treatment dispersion), but the compound itself is a liquid. In this case, it may be used without a solvent. More preferably, the treatment is performed using a treatment solution, and the solvent is preferably an organic solvent.
[0047]
When an organic solvent is used, it can be appropriately selected depending on the solubility of the compound (I). 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, benze Or a mixed solvent thereof. Of these, nitriles, alcohols and amides are particularly preferred solvents.
[0048]
As a method of processing using a processing solution or a processing dispersion (hereinafter, both solutions are collectively referred to as a processing solution), a method of immersing a semiconductor fine particle film in the processing solution (hereinafter, referred to as an immersion processing method) is preferable. Can be mentioned. Further, a method of spraying the treatment liquid in a spray form for a certain time (hereinafter referred to as a spray method) can also be applied. When performing the immersion treatment method, the temperature of the treatment liquid and the time for the treatment may be arbitrarily set, but the immersion treatment is preferably performed at a temperature of 20 ° C. to 80 ° C. for 30 seconds to 24 hours. It is preferable to wash with a solvent after the immersion treatment. The solvent used for washing is preferably of the same composition as the solvent used for the treatment liquid, or a polar solvent such as nitriles, alcohols, amides.
[0049]
Further, the treatment liquid may contain at least one compound (I) and other substances as additives as appropriate. As an example of using an additive, there is a case where a colorless compound having a surface active property or structure is added to the dye to reduce the interaction such as aggregation between the dyes and co-adsorbed to the semiconductor fine particles. . Examples of the additive include a steroid compound having a carboxyl group (for example, chenodeoxycholic acid, cholic acid, etc.), an ultraviolet absorber, a surfactant, and the like.
[0050]
The concentration of compound (I) in the treatment liquid is preferably 1 × 10^-6˜2 mol / L, more preferably 1 × 10^-Five~ 5 × 10^-1mol / L.
[0051]
(B) Treatment method using compound (I) and compound (II)
As described above, in the present invention, it is preferable to treat the semiconductor fine particles with the compound (I) and the compound (II). The term “treatment” as used herein means an operation in which the semiconductor fine particles are brought into contact with the compound (I) and the compound (II) for a certain period of time before the charge transport layer is installed. Alternatively, the compound (II) may or may not be adsorbed. Further, the semiconductor fine particles to be subjected to the treatment may be in any state in the process of producing the photoelectric conversion element, but it is preferable to perform the treatment after the formation of the semiconductor fine particle film, and to adsorb the dye to the semiconductor fine particles. It is particularly preferable that the treatment is performed after the treatment. On the other hand, the compound (I) and compound (II) to be treated are preferably used as a treatment solution or a dispersion, but when the compound itself is a liquid, it may be used without a solvent. More preferably, the treatment is performed using a treatment solution, and the solvent is preferably an organic solvent. In the case of using an organic solvent, the same organic solvent as in the case of treating with only the compound (I) described above can be used.
[0052]
The treatment with compound (I) and the treatment with compound (II) may be performed simultaneously or separately, and are preferably performed simultaneously. When carrying out simultaneously, it is particularly preferable to use a solution in which both the compound (I) and the compound (II) are dissolved and treat it as a mixed solution.
[0053]
In the case of treatment using a mixed treatment solution of compound (I) and compound (II), the immersion treatment method can be preferably used as in the case of treatment with compound (I) alone. The temperature of the treatment liquid and the time required for the treatment when performing the immersion treatment method may be arbitrarily set as in the case of treating with only the compound (I).
[0054]
Similarly to the treatment with compound (I) alone, additives such as a steroid compound having a carboxyl group, an ultraviolet absorber and a surfactant, and a base may be added to the treatment liquid.
[0055]
When the treatment with compound (II) is performed using a treatment liquid containing the compound, the concentration of compound (II) in the treatment liquid is preferably 1 × 10^-6~ 2mol / L, more preferably 1x10^-Five~ 5 × 10^-1mol / L. This preferable concentration is the same as in the case of treatment using a mixed treatment solution of compound (I) and compound (II).
[0056]
[IV] Photoelectric conversion element
The photoelectric conversion element of the present invention is produced by the production method of the present invention. As shown in FIG. 1, the photoelectric conversion element of the present invention is preferably formed by laminating a conductive layer 10, an undercoat layer 60, a photosensitive layer 20, a charge transport layer 30, and a counter electrode conductive layer 40 in this order. The semiconductor fine particles 21 sensitized by 22 and the charge transport material 23 that has penetrated into the gaps between the semiconductor fine particles 21 are formed. The charge transport material 23 in the photosensitive layer 20 is usually the same material used for the charge transport layer 30. Further, a substrate 50 may be provided as a base for the conductive layer 10 and / or the counter electrode conductive layer 40 in order to impart strength to the photoelectric conversion element. 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”. 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. A photocell is made for the purpose of generating electrical work by connecting this photoelectric conversion element to an external load (power generation), and a photosensor is made for the purpose of sensing optical information. Among photocells, the case where the charge transport material is mainly composed of an ion transport material is particularly called a photoelectrochemical cell, and the case where the main purpose is power generation by sunlight is called a solar cell.
[0057]
In the photoelectric conversion element shown in FIG. 1, when the semiconductor fine particles are n-type, the light incident on the photosensitive layer 20 including the semiconductor fine particles 21 sensitized by the dye 22 excites the dye 22 and the like, and the excited dye 22 High-energy electrons in the same are passed 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 an oxidant such as the dye 22 through the counter electrode conductive layer 40 and the charge transport layer 30 while working in an external circuit, and the dye 22 is regenerated. The photosensitive layer 20 functions as a negative electrode (photoanode), and the counter electrode conductive layer 40 functions as a positive electrode. At each layer boundary (for example, the boundary between the conductive layer 10 and the photosensitive layer 20, the boundary between the photosensitive layer 20 and the charge transport layer 30, the boundary between the charge transport layer 30 and the counter conductive layer 40, etc.) They may be diffusively mixed with each other. Each layer will be described in detail below.
[0058]
(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. In the case of (1), a material that can maintain sufficient strength and sealability as the conductive layer, for example, a metal material (platinum, gold, silver, copper, zinc, titanium, aluminum, an alloy containing these, etc.) Can be used. In the case of (2), a substrate having a conductive layer containing a conductive agent on the photosensitive layer side can be used. Preferred conductive agents include metals (platinum, gold, silver, copper, zinc, titanium, aluminum, indium, alloys containing these), carbon, and conductive metal oxides (indium-tin composite oxides, fluorine in tin oxide) Or those doped with antimony). The thickness of the conductive layer is preferably about 0.02 to 10 μm.
[0059]
The lower the surface resistance of the conductive support, the better. The range of the surface resistance is preferably 50Ω / □ or less, more preferably 20Ω / □ or less.
[0060]
When irradiating light from the conductive support side, the conductive support is preferably substantially transparent. The term “substantially transparent” means that the transmittance is 10% or more in a part or all of the light in the visible to near infrared region (400 to 1200 nm), preferably 50% or more, 80% or more is more preferable. In particular, it is preferable that the transmittance in a wavelength region where the photosensitive layer is sensitive is high.
[0061]
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. Preferred as the transparent conductive layer is fluorine dioxide or antimony-doped tin dioxide or indium-tin oxide (ITO). As the transparent substrate, a transparent polymer film can be used in addition to a glass substrate such as soda glass which is advantageous in terms of low cost and strength, alkali-free glass which is not affected by alkali dissolution. Transparent polymer film materials include triacetyl cellulose (TAC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), syndiotactic polystyrene (SPS), polyphenylene sulfide (PPS), polycarbonate (PC), polyarylate ( PAr), polysulfone (PSF), polyester sulfone (PES), polyimide (PI), polyetherimide (PEI), cyclic polyolefin, brominated phenoxy resin, and the like can be used. In order to ensure sufficient transparency, the amount of conductive metal oxide applied is 1 m of glass or plastic support.²The amount is preferably 0.01 to 100 g.
[0062]
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 platinum, gold, nickel, titanium, aluminum, copper, or silver. The metal lead is preferably provided on a transparent substrate by vapor deposition, sputtering or the like, and a transparent conductive layer made of conductive tin oxide or ITO film is preferably provided thereon. 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%.
[0063]
(B) Photosensitive layer
In the photosensitive layer, the semiconductor acts as a photoconductor, absorbs light, separates charges, and generates electrons and holes. In a dye-sensitized semiconductor, light absorption and generation of electrons and holes thereby occur mainly in the dye, and the semiconductor fine particles receive and transmit these electrons (or holes). The semiconductor used in the present invention is preferably an n-type semiconductor which gives an anode current when conductor electrons become carriers under photoexcitation.
[0064]
(1) Semiconductor
Semiconductors include simple semiconductors such as silicon and germanium, III-V group compound semiconductors, metal chalcogenides (oxides, sulfides, selenides, composites thereof, etc.), compounds having a perovskite structure (strontium titanate) , Calcium titanate, sodium titanate, barium titanate, potassium niobate, etc.) can be used.
[0065]
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. Furthermore, M_xO_yS_zOr M_1xM_2yO_z(M, M₁And M₂Also, composites such as are each a metal element, O is oxygen, and x, y, and z are combinations of which the valence is neutral) can also be preferably used.
[0066]
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, SrTiO_Three, GaP, InP, GaAs, CuInS₂, CuInSe₂And more preferably TiO₂, ZnO, SnO₂, Fe₂O_Three, WO_Three, Nb₂O_Five, CdS, PbS, CdSe, SrTiO_Three, InP, GaAs, CuInS₂Or CuInSe₂And particularly preferably TiO₂Or Nb₂O_FiveAnd most preferably TiO₂It is. TiO₂Among them, TiO containing 70% or more of anatase type crystals₂100% anatase type TiO₂Is particularly preferred. It is also effective to dope metals for the purpose of increasing the electron conductivity in these semiconductors. As a metal to dope, a bivalent or trivalent metal is preferable. In order to prevent a reverse current from flowing from the semiconductor to the charge transport layer, it is also effective to dope the semiconductor with a monovalent metal.
[0067]
The semiconductor used in the present invention may be single crystal or polycrystalline, but is preferably polycrystalline from the viewpoint of production cost, securing raw materials, energy payback time, etc., and the layer of semiconductor fine particles is particularly preferably a porous film. Moreover, a part amorphous part may be included.
[0068]
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 30 μm. 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 25 nm or less, more preferably 10 nm or less. In order to improve the light capture rate by scattering incident light, it is also preferable to mix semiconductor particles having a large particle size, for example, about 100 to 300 nm.
[0069]
Two or more different types of semiconductor fine particles may be mixed and used. When two or more kinds of semiconductor fine particles are mixed and used, one of them is TiO₂, ZnO, Nb₂O_FiveOr SrTiO_ThreeIt is preferable that The other is SnO₂, Fe₂O_ThreeOr WO_ThreeIt is preferable that A more preferable combination is ZnO and SnO.₂, ZnO and WO_Three, ZnO and SnO₂And WO_ThreeAnd the like. When two or more kinds of semiconductor fine particles are mixed and used, their particle sizes may be different. Especially the above TiO₂, ZnO, Nb₂O_FiveOr SrTiO_ThreeThe particle size of SnO₂, Fe₂O_ThreeOr WO_ThreeA combination with a small is preferred. Preferably, the large particle size is 100 nm or more, and the small particle size is 15 nm or less.
[0070]
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 described sol-gel method and Tadao Sugimoto's "Synthesis and size control of monodisperse particles by the new synthetic gel-sol method", Materia, Vol. 35, No. 9, pp. 1012-1018 (1996) Etc.) is preferred. In addition, a method developed by Degussa for producing an oxide by high-temperature hydrolysis of a chloride in an oxyhydrogen salt can be preferably used.
[0071]
When the semiconductor fine particles are titanium oxide, the sol-gel method, gel-sol method, and high-temperature hydrolysis method in oxyhydrogen salt of chloride are all preferred, but Kiyoshi Manabu's “Titanium oxide properties and applied technology” The sulfuric acid method or 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 Barbe et al., Vol. 80, No. 12, pp. 3157-3171 (1997), the chemistry of Burnside et al. , Vol. 10, No. 9, pages 2419-2425 are also preferred.
[0072]
(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. Typical examples of the wet film forming method include a coating method, a printing method, an electrolytic deposition method, and an electrodeposition method. Also, a method of oxidizing metal, a method of depositing in a liquid phase from a metal solution by ligand exchange (LPD method), a method of vapor deposition by sputtering, a CVD method, or a metal that is thermally decomposed on a heated substrate An SPD method in which a metal oxide is formed by spraying an oxide precursor can also be used.
[0073]
In addition to the sol-gel method described above, a method for preparing a dispersion of semiconductor fine particles includes a method of grinding in a mortar, a method of dispersing while pulverizing using a mill, and fine particles in a solvent when synthesizing a semiconductor. The method of depositing and using as it is is mentioned.
[0074]
As the dispersion medium, water and various organic solvents (for example, methanol, ethanol, isopropyl alcohol, citronellol, terpineol, dichloromethane, acetone, acetonitrile, ethyl acetate, etc.) can be used. At the time of dispersion, a polymer such as polyethylene glycol, hydroxyethyl cellulose, carboxymethyl cellulose, a surfactant, an acid, a chelating agent, or the like may be used as a dispersion aid as necessary. By changing the molecular weight of the polyethylene glycol, the viscosity of the dispersion can be adjusted, and a semiconductor layer that is difficult to peel off can be formed and the porosity of the semiconductor layer can be controlled. Therefore, it is preferable to add polyethylene glycol.
[0075]
Application methods such as roller method and dip method as application system, air knife method and blade method as metering system, and application and metering are disclosed in Japanese Examined Patent Publication No. 58-4589. 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, the film forming method may be selected according to the liquid viscosity and the wet thickness.
[0076]
The semiconductor fine particle layer is not limited to a single layer, and 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.
[0077]
In general, as the semiconductor fine particle layer thickness (same as the photosensitive layer thickness) 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 1 to 30 μm, and more preferably 2 to 25 μm. Semiconductor fine particle support 1m²The coating amount per unit is preferably 0.5 to 100 g, more preferably 3 to 50 g.
[0078]
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. The range of preferable heating temperature is 40-700 degreeC, More preferably, it is 100-600 degreeC. 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 temperature as possible (for example, 50-350 degreeC) also from a viewpoint of cost. The temperature can be lowered by heat treatment in the presence of small semiconductor particles of 5 nm or less, mineral acids, and metal oxide precursors, and by applying ultraviolet rays, infrared rays, microwaves, etc., electric fields, and ultrasonic waves. It can also be done. At the same time, for the purpose of removing unnecessary organic substances and the like, it is preferable to use a combination of irradiation, application, heating, decompression, oxygen plasma treatment, pure water cleaning, solvent cleaning, gas cleaning and the like in combination as appropriate.
[0079]
After the heat treatment, for example, chemical plating using titanium tetrachloride aqueous solution or titanium trichloride to increase the surface area of the semiconductor fine particles, increase the purity in the vicinity of the semiconductor fine particles, and increase the efficiency of electron injection from the dye into the semiconductor fine particles. You may perform the electrochemical plating process using aqueous solution. In order to prevent a reverse current from flowing from the semiconductor fine particles to the charge transport layer, it is also effective to adsorb an organic substance having a low electron conductivity other than a dye on the particle surface. The organic substance to be adsorbed is preferably one having a hydrophobic group.
[0080]
The semiconductor fine particle layer preferably has a large surface area so that a large amount of dye can be adsorbed. The surface area of the semiconductor fine particle layer coated on the support is preferably at least 10 times, more preferably at least 100 times the projected area. The upper limit is not particularly limited, but is usually about 1000 times.
[0081]
(3) Dye
The sensitizing dye used in the photosensitive layer can be arbitrarily used as long as it is a compound that has absorption in the visible region and near-infrared region and can sensitize a semiconductor. However, a metal complex dye, a methine dye, a porphyrin dye, or a phthalocyanine dye Dyes are preferred, and metal complex dyes are particularly preferred. Moreover, in order to make the wavelength range of photoelectric conversion as wide as possible and increase the conversion efficiency, two or more kinds of dyes can be used in combination or mixed. In this case, it is possible to select the dye to be used or mixed and the ratio thereof so as to match the wavelength range and intensity distribution of the target light source.
[0082]
Such a dye preferably has an appropriate interlocking group capable of adsorbing to the surface of the semiconductor fine particles. Preferred linking groups include -COOH group, -OH group, -SO₂H group, -P (O) (OH)₂Group and -OP (O) (OH)₂And chelating groups having π conductivity such as oximes, dioximes, hydroxyquinolines, salicylates and α-ketoenolates. -COOH group, -P (O) (OH)₂Group and -OP (O) (OH)₂The group is particularly preferred. These groups may form a salt with an alkali metal or the like, or may form an internal salt. In the case of a polymethine dye, if the methine chain contains an acidic group as in the case where the methine chain forms a squarylium ring or a croconium ring, this part may be used as a linking group. Hereinafter, preferred sensitizing dyes used in the photosensitive layer will be specifically described.
[0083]
(a) Metal complex dye
When the dye is a metal complex dye, a metal phthalocyanine dye, a metal porphyrin dye or a ruthenium complex dye is preferable, and a ruthenium complex dye is particularly preferable. Examples of the ruthenium complex dye include, for example, U.S. Pat. And those described in JP-A No. 2000-26487 and the like.
[0084]
The ruthenium complex dye used in the present invention has the following general formula (III):
(A_Three)_pRu (B-a) (B-b) (B-c) (III)
Is preferably represented by: In general formula (III), A_ThreeRepresents a mono or bidentate ligand, preferably Cl, SCN, H₂It is a ligand selected from the group consisting of O, Br, I, CN, NCO, SeCN, β-diketone derivatives, oxalic acid derivatives and dithiocarbamic acid derivatives. p is an integer of 0-3. B-a, B-b and B-c each independently represents an organic ligand represented by any of the following formulas B-1 to B-10.
[0085]
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[0086]
In formulas B-1 to B-10, R₁₁Each represents a hydrogen atom or a substituent, and examples of the substituent include a halogen atom, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted aralkyl group having 7 to 12 carbon atoms, Examples thereof include substituted or unsubstituted aryl groups having 6 to 12 carbon atoms, the aforementioned acidic groups (these acidic groups may form a salt), and chelating groups. Here, the alkyl part of the alkyl group and the aralkyl group may be linear or branched, and the aryl part of the aryl group and the aralkyl group may be monocyclic or polycyclic (fused ring, ring assembly). B-a, B-b and B-c may be the same or different, and may be any one or two.
[0087]
Specific examples of preferable metal complex dyes are shown below, but the present invention is not limited thereto.
[0088]
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[0089]
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[0090]
(b) Methine dye
Preferred methine dyes that can be used in the present invention are polymethine dyes such as cyanine dyes, merocyanine dyes, and squarylium dyes. Examples of preferred polymethine dyes include JP-A-11-35836, JP-A-11-67285, JP-A-11-86916, JP-A-11-97725, JP-A-11-158395, JP-A-11-163378, Examples thereof include the dyes described in JP-A-11-214730, JP-A-11-214731, JP-A-11-238905, JP-A-2000-26487, European Patents 892411, 911841 and 991092. Specific examples of preferable methine dyes are shown below.
[0091]
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[0092]
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[0093]
(4) Adsorption of dye to semiconductor fine particles
Adsorption of the dye to the semiconductor fine particles can be performed by immersing a conductive support having a well-dried semiconductor fine particle layer in the dye solution or by applying a dye solution to the semiconductor fine particle layer. 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 case of the immersion method, the adsorption of the 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, and a spray method. In addition, a dye can be applied in an image form by an inkjet method or the like, and the image itself can be used as a photoelectric conversion element.
[0094]
Solvents used for the dye solution (adsorption solution) are preferably 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.), It is a hydrocarbon (hexane, petroleum ether, benzene, toluene, etc.) or a mixed solvent thereof.
[0095]
The total amount of dye adsorbed is the unit area of the semiconductor fine particle layer (1 m²) Is preferably 0.01 to 100 mmol. The amount of the dye adsorbed on the semiconductor fine particles is preferably in the range of 0.01 to 1 mmol per 1 g of the semiconductor fine particles. By using such an amount of dye adsorbed, a sensitizing 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. 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 perform the dye adsorption operation quickly when the temperature of the semiconductor fine particle layer is between 60 to 150 ° C. without returning to room temperature.
[0096]
The unadsorbed dye is preferably removed by washing immediately after adsorption. The washing is preferably performed using a wet washing tank with a polar solvent such as acetonitrile or an organic solvent such as an alcohol solvent.
[0097]
(5) Additive to dye adsorbent
A colorless compound may be added to the dye adsorbing solution and co-adsorbed on the semiconductor fine particles for the purpose of reducing the interaction such as aggregation between the dyes or increasing the amount of the dye adsorbed. Preferred examples of such colorless compounds include steroid compounds having a carboxyl group (such as chenodeoxycholic acid), sulfonic acid compounds, compounds having a ureido group (hereinafter referred to as ureido compounds), alkali metal salts, alkaline earth metals. Examples include salts. Of these, ureido compounds and alkali metal salts are more preferred, and alkali metal salts are particularly preferred. Of the alkali metal salts, lithium salts are most preferred.
[0098]
Preferred specific examples of the ureido compound are shown below. The addition amount of the ureido compound is preferably 0.1 to 1000 times mol, more preferably 1 to 500 times mol, and particularly preferably 10 to 100 times mol to the dye.
[0099]
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[0100]
In the alkali metal salt and alkaline earth metal salt, the anion species that forms a salt by pairing with an alkali metal cation or an alkaline earth metal cation is not particularly limited. These salts are halogen salts (fluorine salts, chlorine salts, bromine salts, iodine salts, etc.), carboxylates, sulfonates, phosphonates, sulfonamides, sulfonylimide salts (bistrifluoromethanesulfonimide, bispenta). Fluoroethanesulfonimide salt, etc.), sulfonylmethide salt, sulfate, thiocyanate, cyanate, perchlorate, tetrafluoroborate, hexafluorophosphate, etc., preferably iodine salt , Bistrifluoromethanesulfonimide salt, thiocyanate, tetrafluoroborate or hexafluorophosphate, more preferably iodine salt, bistrifluoromethanesulfonimide salt or tetrafluoroborate, particularly preferably It is an iodine salt. The addition amount of the alkali metal salt or alkaline earth metal salt is preferably 0.1 to 1000 times mol, more preferably 1 to 500 times mol, and particularly preferably 10 to 100 times mol to the dye.
[0101]
For the purpose of reducing aggregation between the dyes, a steroid compound having a surface active property and having a carboxyl group (such as chenodeoxycholic acid) or the following sulfonates may be added to the dye adsorbing liquid.
[0102]
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[0103]
(C) Charge transport layer
The charge transport layer is a layer containing a charge transport material having a function of replenishing electrons to the oxidant of the dye. The charge transport material used in the present invention may be (i) a charge transport material related to ions, or (ii) a charge transport material related to carrier movement in a solid. (i) Charge transport materials involving ions include molten salt electrolyte compositions containing redox counter ions, solutions in which redox pair ions are dissolved (electrolytic solutions), and redox couple solutions in polymer matrix gels. Examples of so-called gel electrolyte compositions and solid electrolyte compositions impregnated include (ii) charge transport materials that involve carrier movement in solids, such as electron transport materials and hole transport materials. A plurality of these charge transport materials can be used in combination. In the present invention, it is preferable to use a molten salt electrolyte composition or an electrolytic solution for the charge transport layer.
[0104]
(1) Molten salt electrolyte composition
The molten salt electrolyte is preferably used for the charge transport material from the viewpoint of achieving both photoelectric conversion efficiency and durability. The molten salt electrolyte is an electrolyte that is liquid at room temperature or has a low melting point. For example, WO95 / 18456, JP-A-8-259543, Electrochemistry, Vol. 65, No. 11, 923 (1997) Pyridinium salts, imidazolium salts, triazolium salts and the like described in the above. The melting point of the molten salt is preferably 100 ° C. or less, and is particularly preferably liquid around room temperature.
[0105]
In the present invention, a molten salt represented by any of the following general formulas (Ya), (Yb) and (Yc) can be preferably used.
[0106]
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[0107]
Q in general formula (Y-a)_y1Represents an atomic group that forms a 5- or 6-membered aromatic cation with a nitrogen atom. Q_y1Is preferably composed of atoms selected from the group consisting of carbon atoms, hydrogen atoms, nitrogen atoms, oxygen atoms and sulfur atoms. Q_y1Is preferably an oxazole ring, a thiazole ring, an imidazole ring, a pyrazole ring, an isoxazole ring, a thiadiazole ring, an oxadiazole ring, a triazole ring, an indole ring or a pyrrole ring. Or it is more preferable that it is an imidazole ring, and it is especially preferable that it is an oxazole ring or an imidazole ring. Q_y1The 6-membered ring formed by is preferably a pyridine ring, pyrimidine ring, pyridazine ring, pyrazine ring or triazine ring, and particularly preferably a pyridine ring.
[0108]
A in general formula (Y-b)_y1Represents a nitrogen atom or a phosphorus atom.
[0109]
R in general formulas (Y-a), (Y-b) and (Y-c)_y1~ R_y11Each independently represents a substituted or unsubstituted alkyl group (preferably having 1 to 24 carbon atoms, which may be linear, branched or cyclic, such as a methyl group, Ethyl group, propyl group, isopropyl group, pentyl group, hexyl group, octyl group, 2-ethylhexyl group, t-octyl group, decyl group, dodecyl group, tetradecyl group, 2-hexyldecyl group, octadecyl group, cyclohexyl group, cyclopentyl Group) or a substituted or unsubstituted alkenyl group (preferably having 2 to 24 carbon atoms, which may be linear or branched, such as a vinyl group or an allyl group). R_y1~ R_y11Are each independently more preferably an alkyl group having 2 to 18 carbon atoms or an alkenyl group having 2 to 18 carbon atoms, and particularly preferably an alkyl group having 2 to 6 carbon atoms.
[0110]
R in general formula (Y-b)_y2~ R_y5Two or more of them connected to each other_y1May form a non-aromatic ring containing R in general formula (Y-c)_y6~ R_y11Two or more of them may be connected to each other to form a ring.
[0111]
Q above_y1And R_y1~ R_y11May have a substituent. Preferred examples of this substituent include halogen atoms (F, Cl, Br, I, etc.), cyano groups, alkoxy groups (methoxy group, ethoxy group, methoxyethoxy group, methoxyethoxyethoxy group, etc.), aryloxy groups (phenoxy group). Etc.), alkylthio group (methylthio group, ethylthio group etc.), alkoxycarbonyl group (ethoxycarbonyl group etc.), carbonate group (ethoxycarbonyloxy group etc.), acyl group (acetyl group, propionyl group, benzoyl group etc.), sulfonyl Groups (methanesulfonyl group, benzenesulfonyl group, etc.), acyloxy groups (acetoxy group, benzoyloxy group, etc.), sulfonyloxy groups (methanesulfonyloxy group, toluenesulfonyloxy group, etc.), phosphonyl groups (diethylphosphonyl group, etc.), Amide group (acetylamino group, benzoy Amino group, etc.), carbamoyl group (N, N-dimethylcarbamoyl group, etc.), alkyl group (methyl group, ethyl group, propyl group, isopropyl group, cyclopropyl group, butyl group, 2-carboxyethyl group, benzyl group, etc.) Aryl groups (phenyl group, toluyl group, etc.), heterocyclic groups (pyridyl group, imidazolyl group, furanyl group, etc.), alkenyl groups (vinyl group, 1-propenyl group, etc.), silyl groups, silyloxy groups, and the like.
[0112]
The molten salt represented by any one of the general formulas (Y-a), (Y-b) and (Y-c) is Q_y1And R_y1~ R_y11A multimer may be formed via any of the above.
[0113]
In general formulas (Y-a), (Y-b) and (Y-c), X^-Represents an anion. X^-Preferred examples of halides include halide ions (I^-, Cl^-, Br^-Etc.), SCN^-, BF_Four ^-, PF₆ ^-, ClO_Four ^-, (CF_ThreeSO₂)₂N^-, (CF_ThreeCF₂SO₂)₂N^-, CH_ThreeSO_Three ^-, CF_ThreeSO_Three ^-, CF_ThreeCOO^-, Ph_FourB^-, (CF_ThreeSO₂)_ThreeC^-, Etc. X^-Is I^-, SCN^-, CF_ThreeSO_Three ^-, CF_ThreeCOO^-, (CF_ThreeSO₂)₂N^-Or BF_Four ^-It is more preferable that
[0114]
Specific examples of the molten salt preferably used in the present invention are listed below, but the present invention is not limited thereto.
[0115]
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[0116]
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[0117]
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[0118]
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[0119]
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[0120]
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[0121]
The molten salt may be used alone or in combination of two or more. Also, other iodine salts such as LiI and LiBF_Four, CF_ThreeCOOLi, CF_ThreeAlkali metal salts such as COONa, LiSCN and NaSCN can also be used in combination. The addition amount of the alkali metal salt is preferably 0.02 to 2% by mass, and more preferably 0.1 to 1% by mass with respect to the entire composition.
[0122]
The molten salt electrolyte is preferably in a molten state at room temperature, and it is preferable not to use a solvent for a composition containing the molten salt electrolyte. Although the solvent described later may be added, the content of the molten salt is preferably 50% by mass or more, particularly preferably 90% by mass or more, based on the entire composition. Moreover, it is preferable that 50 mass% or more of the salt which a composition contains is an iodine salt.
[0123]
It is preferable to add iodine to the molten salt electrolyte composition. In this case, the content of iodine is preferably 0.1 to 20% by mass, and preferably 0.5 to 5% by mass with respect to the entire composition. More preferred.
[0124]
(2) Electrolyte
The electrolytic solution is preferably composed of an electrolyte, a solvent, and an additive. The electrolyte contains I as an electrolyte.₂And iodide (LiI, NaI, KI, CsI, CaI₂A combination of metal iodides such as tetraalkylammonium iodide, pyridinium iodide, imidazolium iodide and other quaternary ammonium compound iodine salts), Br₂And bromide (LiBr, NaBr, KBr, CsBr, CaBr₂In addition to metal bromides such as tetraalkylammonium bromide and pyridinium bromide bromides, etc., metal complexes such as ferrocyanate-ferricyanate and ferrocene-ferricinium ions, sodium polysulfide Sulfur compounds such as alkylthiol-alkyldisulfides, viologen dyes, hydroquinone-quinones, and the like can be used. I among them₂An electrolyte in which LiI or a quaternary ammonium compound iodine salt such as pyridinium iodide or imidazolium iodide is combined is preferable. The electrolytes described above may be used in combination.
[0125]
The electrolyte concentration in the electrolytic solution is preferably 0.1 to 10M, more preferably 0.2 to 4M. Moreover, the preferable addition density | concentration of iodine when adding an iodine to electrolyte solution is 0.01-0.5M.
[0126]
The solvent used in the electrolytic solution is preferably a compound that has low viscosity and improved ion mobility, or has a high dielectric constant and improved effective carrier concentration, and can exhibit excellent ion conductivity. Examples of such solvents include carbonate compounds such as ethylene carbonate and propylene carbonate, heterocyclic compounds such as 3-methyl-2-oxazolidinone, ether compounds such as dioxane and diethyl ether, ethylene glycol dialkyl ether, propylene glycol dialkyl ether, polyethylene Chain ethers such as glycol dialkyl ether and polypropylene glycol dialkyl ether, methanol, ethanol, ethylene glycol monoalkyl ether, alcohols such as propylene glycol monoalkyl ether, polyethylene glycol monoalkyl ether, polypropylene glycol monoalkyl ether, ethylene glycol, Propylene glycol, polyethylene glycol, polypropylene glycol , Polyhydric alcohols such as glycerin, acetonitrile, glutarodinitrile, methoxyacetonitrile, propionitrile, nitrile compounds such as benzonitrile, aprotic polar substances such as dimethyl sulfoxide and sulfolane, water and the like. Can also be used.
[0127]
Further, basic compounds such as tert-butylpyridine, 2-picoline, 2,6-lutidine and the like described in J. Am. Ceram. Soc., 80 (12) 3157-3171 (1997), The compound (I) is preferably added to the above-described molten salt electrolyte composition or electrolytic solution, and it is more preferable to add the compound (I). The preferred concentration range when adding the basic compound or compound (I) to the electrolyte is 0.05 to 2M. When added to the molten salt electrolyte composition, the mass ratio of the basic compound or compound (I) to the entire composition is preferably 0.1 to 40 mass%, more preferably 1 to 20 mass%.
[0128]
(3) Gel electrolyte composition
In the present invention, the molten salt electrolyte composition or the electrolytic solution is gelated (solidified) by a method such as addition of a polymer, addition of an oil gelling agent, polymerization including polyfunctional monomers, or a crosslinking reaction of the polymer. You can also In the case of gelation by addition of a polymer, compounds described in “Polymer Electrolyte Reviews-1 and 2” (JR MacCallum and CA Vincent, ELSEVIER APPLIED SCIENCE) can be used. Vinylidene can be preferably used. In the case of gelation by adding an oil gelling agent, Journal of Industrial Science (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, and J. Chem Although compounds described in Soc., Chem. Commun., 1997, 545 can be used, preferred compounds are those having an amide structure in the molecular structure. An example of gelling the electrolytic solution is described in JP-A No. 11-185863, and an example of gelling the molten salt electrolyte is also described in JP-A No. 2000-58140, which can also be applied to the present invention.
[0129]
Moreover, when making it gelatinize by the crosslinking reaction of a polymer, it is desirable to use together the polymer and crosslinking agent containing the reactive group which can be bridge | crosslinked. In this case, preferred crosslinkable reactive groups are amino groups and nitrogen-containing heterocyclic rings (pyridine ring, imidazole ring, thiazole ring, oxazole ring, triazole ring, morpholine ring, piperidine ring, piperazine ring, etc.), and preferred bridges. The agent is a bifunctional or higher reagent capable of electrophilic reaction with nitrogen atoms (alkyl halides, halogenated aralkyls, sulfonic acid esters, acid anhydrides, acid chlorides, isocyanate compounds, α, β A saturated sulfonyl compound, an α, β-unsaturated carbonyl compound, an α, β-unsaturated nitrile compound, etc.), and the crosslinking techniques described in JP-A Nos. 2000-17076 and 2000-86724 can also be applied.
[0130]
(4) Hole transport material
In the present invention, instead of an ion conductive electrolyte such as a molten salt, a solid hole transport material that is organic or inorganic or a combination of both can be used.
[0131]
(a) Organic hole transport material
Organic hole transport materials applicable to the present invention include J. Hagen, et al., Synthetic Metal, 89, 215-220 (1997), Nature, Vol. 395, 8 Oct., p583-585 (1998). And WO97 / 10617, JP-A-59-194393, JP-A-5-34681, U.S. Pat.No. 4,923,774, JP-A-4-308688, U.S. Pat. 129271, JP 4-175395, JP 4-264189, JP 4-90851, JP 4-364153, JP 5-25473, JP 5-239455, JP 5-320634 , JP-A-6-1972, JP-A-7-138562, JP-A-7-252474, JP-A-11-144773, etc., JP-A-11-149821, JP-A-11- Triphenylene derivatives described in 148067, JP-A-11-176489 and the like can be preferably used. Also, Adv. Mater., 9, No. 7, p557 (1997), Angew. Chem. Int. Ed. Engl., 34, No. 3, p303-307 (1995), JACS, Vol. 120, No. 4, p664-672 (1998) etc., oligothiophene compounds described in K. Murakoshi, et al., Chem. Lett. P471 (1997), “Handbook of Organic Conductive Molecules and Polymers, Vol. 1,2,3,4 "(by NALWA, published by WILEY), polyacetylene and its derivatives, poly (p-phenylene) and its derivatives, poly (p-phenylene vinylene) and its derivatives, polythienylene vinylene And conductive polymers such as polythiophene and derivatives thereof, polyaniline and derivatives thereof, polytoluidine and derivatives thereof can be preferably used.
[0132]
Hole transport materials such as tris (4-bromophenyl) aminium hexachloroantimonate are used to control the dopant level as described in Nature, Vol. 395, 8 Oct., p583-585 (1998). Li [(CF to add compounds containing various cation radicals and to control the potential of oxide semiconductor surfaces (space charge layer compensation)_ThreeSO₂)₂A salt such as N] may be added.
[0133]
(b) Inorganic hole transport material
A p-type inorganic compound semiconductor can be used as the inorganic hole transport material. The p-type inorganic compound semiconductor for this purpose preferably has a band gap of 2 eV or more, and more preferably 2.5 eV or more. In addition, the ionization potential of the p-type inorganic compound semiconductor needs to be smaller than the ionization potential of the dye-adsorbing electrode from the condition that the holes of the dye can be reduced. Although the preferred range of the ionization potential of the p-type inorganic compound semiconductor varies depending on the dye used, it is generally preferably 4.5 eV or more and 5.5 eV or less, and more preferably 4.7 eV or more and 5.3 eV or less. Preferred p-type inorganic compound semiconductors are compound semiconductors containing monovalent copper. Examples of compound semiconductors containing monovalent copper include CuI, CuSCN, and CuInSe.₂, Cu (In, Ga) Se₂, CuGaSe₂, Cu₂O, CuS, CuGaS₂, CuInS₂, CuAlSe₂Etc. Among these, CuI and CuSCN are preferable, and CuI is most preferable. Other p-type inorganic compound semiconductors include GaP, NiO, CoO, FeO, and Bi.₂O_Three, MoO₂, Cr₂O_ThreeEtc. can be used.
[0134]
(5) Formation of charge transport layer
There are two possible methods for forming the charge transport layer. One is a method in which a counter electrode is first bonded onto the photosensitive layer, and a liquid charge transport layer is sandwiched between the gaps. The other is a method in which a charge transport layer is provided directly on the photosensitive layer, and a counter electrode is subsequently provided.
[0135]
In the case of the former method, as a method for sandwiching the charge transport layer, a normal pressure process using capillary action due to dipping or the like, or a vacuum process in which the gas phase in the gap is replaced with a liquid phase at a pressure lower than normal pressure can be used.
[0136]
In the case of the latter method, the wet charge transport layer is provided with a counter electrode without being dried, and measures for preventing liquid leakage at the edge portion are taken. In the case of a gel electrolyte, there is a method in which it is applied in a wet manner and solidified by a method such as polymerization. In this case, the counter electrode can be applied after drying and fixing. As a method for applying the wet organic hole transporting material and the gel electrolyte in addition to the electrolytic solution, the same methods as those for the semiconductor fine particle layer and the dye can be used.
[0137]
In the case of a solid electrolyte or a solid hole transport material, a charge transport layer can be formed by a dry film forming process such as a vacuum deposition method or a CVD method, and then a counter electrode can be provided. 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. Also in the case of an inorganic solid compound, it can be introduced into the electrode by techniques such as casting, coating, spin coating, dipping, electrolytic deposition, and electroless plating.
[0138]
(D) Counter electrode
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 the conductive material used for the counter electrode conductive layer, metal (platinum, gold, silver, copper, aluminum, magnesium, indium, etc.), carbon, and conductive metal oxide (indium-tin composite oxide, fluorine-doped tin oxide, etc.) Is mentioned. Among these, platinum, gold, silver, copper, aluminum, and magnesium can be preferably used. The support substrate used for the counter electrode is preferably a glass substrate or a plastic substrate, and the conductive material is applied or vapor-deposited thereon for use. The thickness of the counter electrode conductive layer is not particularly limited, but is preferably 3 nm to 10 μm. The lower the surface resistance of the counter electrode conductive layer, the better. The range of the surface resistance is preferably 50Ω / □ or less, more preferably 20Ω / □ or less.
[0139]
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 deposited with a metal or a conductive oxide, or a metal thin film can be used.
[0140]
The counter electrode may be formed by directly applying, plating or vapor-depositing (PVD, CVD) a conductive agent on the charge transport layer, or attaching the conductive layer side of the substrate having the conductive layer. 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. In addition, the material and installation method of a preferable metal lead, the fall of the incident light amount by metal lead installation, etc. are the same as the case of an electroconductive support body.
[0141]
(E) Other layers
In order to prevent a short circuit between the counter electrode and the conductive support, it is preferable that a dense semiconductor thin film layer is preliminarily applied as an undercoat layer between the conductive support and the photosensitive layer. This method of preventing a short circuit by the undercoat layer is particularly effective when an electron transport material or a hole transport material is used for the charge transport layer. The undercoat layer is preferably TiO₂, SnO₂, Fe₂O_Three, WO_Three, ZnO or Nb₂O_FiveMore preferably TiO₂Consists of. The undercoat layer can be applied by, for example, a spray pyrolysis method or a sputtering method described in Electrochim. Acta, 40, 643-652 (1995). The preferred thickness of the undercoat layer is 5 to 1000 nm, and more preferably 10 to 500 nm.
[0142]
Moreover, you may provide functional layers, such as a protective layer and an antireflection layer, in the outer surface of one or both of the electroconductive support body which acts as an electrode, and a counter electrode, between an electroconductive layer and a board | substrate, or in the middle of a board | substrate. For forming these functional layers, a coating method, a vapor deposition method, a bonding method, or the like can be used depending on the material.
[0143]
(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.
[0144]
In the structure shown in FIG. 2, the photosensitive layer 20 and the charge transport layer 30 are interposed between the transparent conductive layer 10a and the transparent counter electrode conductive layer 40a, and light is incident from both sides. . In the structure shown in FIG. 3, a metal lead 11 is partially provided on a transparent substrate 50a, a transparent conductive layer 10a is provided thereon, and an undercoat layer 60, a photosensitive layer 20, a charge transport layer 30, and a counter electrode conductive layer 40 are arranged in this order. In addition, a support substrate 50 is arranged, and light is incident from the conductive layer side. The structure shown in FIG. 4 has a conductive layer 10 on a support substrate 50, a photosensitive layer 20 provided through an undercoat layer 60, a charge transport layer 30 and a transparent counter electrode conductive layer 40a, and a metal in part. The transparent substrate 50a provided with the leads 11 is disposed with the metal lead 11 side inward, and has a structure in which light enters from the counter electrode side. In the structure shown in FIG. 5, the subbing layer 60, the photosensitive layer 20 and the charge transport layer 30 are provided between a pair of metal leads 11 provided on a transparent substrate 50a and further provided with a transparent conductive layer 10a (or 40a). In this structure, light enters from both sides. In the structure shown in FIG. 6, a transparent conductive layer 10a, an undercoat layer 60, a photosensitive layer 20, a charge transport layer 30 and a counter electrode conductive layer 40 are provided on a transparent substrate 50a, and a support substrate 50 is disposed thereon. In this structure, light enters from the conductive layer side. The structure shown in FIG. 7 has a conductive layer 10 on a support substrate 50, a photosensitive layer 20 provided through an undercoat layer 60, a charge transport layer 30 and a transparent counter electrode conductive layer 40a, and a transparent substrate thereon. 50a is arranged, and light is incident from the counter electrode side. In the structure shown in FIG. 8, a transparent conductive layer 10a is provided on a transparent substrate 50a, a photosensitive layer 20 is provided via an undercoat layer 60, a charge transport layer 30 and a transparent counter electrode conductive layer 40a are provided, and a transparent layer is provided thereon. The substrate 50a is disposed, and light is incident from both sides. In the structure shown in FIG. 9, the conductive layer 10 is provided on the support substrate 50, the photosensitive layer 20 is provided via the undercoat layer 60, and the solid charge transport layer 30 is further provided. It has a metal lead 11 and has a structure in which light is incident from the counter electrode side.
[0145]
[V] Photovoltaic
The photovoltaic cell of the present invention is one in which the photoelectric conversion element of the present invention is caused to work with an external load. Among photocells, the case where the charge transport material is mainly composed of an ion transport material is particularly called a photoelectrochemical cell, and the case where the main purpose is power generation by sunlight is called a solar cell.
[0146]
The side surface of the photovoltaic cell is preferably sealed with a polymer, an adhesive or the like in order to prevent deterioration of the constituents and volatilization of the contents. The external circuit itself connected to the conductive support and the counter electrode via a lead may be a known one.
[0147]
When the photoelectric conversion element of the present invention is applied to a solar cell, the structure inside the cell is basically the same as the structure of the photoelectric conversion element described above. Moreover, the dye-sensitized solar cell using the photoelectric conversion element 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, a potting type, a substrate integrated module structure used in amorphous silicon solar cells, and the like are known, and dye sensitization using the photoelectric conversion element of the present invention is known. As for the solar cell, the module structure can be appropriately selected depending on the purpose of use, the place of use and the environment. Specifically, the structures and embodiments described in Japanese Patent Application Nos. 11-8457 and 2000-268892 are preferable.
[0148]
【Example】
Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto.
[0149]
Synthesis example 1
Synthesis of Compound Ib-1
To a solution consisting of 3.8 g of 3-aminopyridine, 5.7 ml of triethylamine and 50 ml of acetonitrile, a solution of 6.8 ml of trifluoromethanesulfonic anhydride and 50 ml of methylene chloride was slowly added dropwise at -50 ° C. under a nitrogen atmosphere. . The resulting reaction solution was stirred as it was for 1 hour, the temperature was raised to room temperature, and the mixture was further stirred for 1 hour. The filtrate obtained by filtering this was concentrated, and the residue was purified by silica gel column chromatography to obtain 6.4 g of 3-trifluoromethanesulfonamidopyridine.
0.4 g of 3-trifluoromethanesulfonamide pyridine was dissolved in an aqueous solution consisting of 1.2 g of sodium hydroxide and 80 ml of water, and 4.6 g of silver nitrate and an aqueous solution of 20 ml of water were added thereto. After stirring this reaction liquid at 40 degreeC for 2 hours, the deposit produced | generated in the reaction liquid was separated by filtration and wash | cleaned with acetonitrile. The washed precipitate was added to 50 ml of acetonitrile, to which was added an aqueous solution consisting of 2.7 g of 1-ethyl-3-methylimidazolium bromide and 50 ml of water. After stirring the resulting mixture at 40 ° C. for 2 hours, the precipitated silver bromide was removed by filtration, then the filtrate was concentrated, the residue was purified by silica gel column chromatography, dried with a vacuum pump, and 3.0 g Compound Ib-1 was obtained.
The obtained compound Ib-1 was a low-viscosity liquid at room temperature. Compound Ib-1 has the structure¹Confirmed by H-NMR and MASS spectra. Compound Ib-1¹H-NMR peak shift values are shown below.
¹H-NMR (δ value, deuterated dimethyl sulfoxide): 9.33 (s, 1H), 8.28 (s, 1H), 8.08 (d, 1H), 7.51 (d, 1H), 7.31 (s, 1H), 7.30 (s, 1H), 7.07 (dd, 1H), 4.09 (q, 2H), 3.89 (s, 3H), 1.49 (t, 3H).
[0150]
Example 1
1. Preparation of titanium dioxide particle coating solution
Titanium dioxide particles with a titanium dioxide concentration of 11% by mass in the same manner as described in Barbe et al., Journal of American Ceramic Society, Volume 80, page 3157, except that the autoclave temperature was 230 ° C. A dispersion was obtained. The average size of the titanium dioxide particles in this dispersion was about 10 nm. To this dispersion, 20% by mass of polyethylene glycol (molecular weight 20000, manufactured by Wako Pure Chemical Industries, Ltd.) with respect to titanium dioxide was added and mixed to obtain a titanium dioxide particle coating solution.
[0151]
2. Preparation of dye-adsorbed titanium dioxide electrode
(1) Preparation of dye adsorption electrode
Transparent conductive glass coated with tin oxide doped with fluorine (made by Nippon Sheet Glass, surface resistance: approx. 10Ω / cm²) Apply the above titanium dioxide particle coating solution to the thickness of 120μm on the conductive surface side with a doctor blade, dry at 25 ° C for 30 minutes, and then use an electric furnace ("Muffle furnace FP-32 type" manufactured by Yamato Scientific) The mixture was baked at 450 ° C. for 30 minutes and cooled to form a titanium dioxide layer to obtain a titanium dioxide electrode. Titanium dioxide coating amount per unit area of transparent conductive glass is 18g / m²The thickness of the titanium dioxide layer was 12 μm.
The resulting titanium dioxide electrode was converted to ruthenium complex dye R-1 (cis- (dithiocyanate) -N, N'-bis (2,2'-bipyridyl-4,4'-dicarboxylic acid) ruthenium (II) complex. The dye-adsorbing electrode T-1 was prepared by immersing it in a dye-adsorbing solution containing 25) at 25 ° C. for 16 hours and washing sequentially with ethanol and acetonitrile. The dye adsorbing liquid is composed of ruthenium complex dye R-1 and a mixed solvent of ethanol and acetonitrile (ethanol: acetonitrile = 1: 1 (volume ratio)). The concentration of ruthenium complex dye R-1 in the dye adsorbing liquid is 3 × 10^-FourMole / liter.
In addition, 1 × 10^-2A dye adsorbing electrode T-2 was produced in the same manner as the dye adsorbing electrode T-1, except that lithium iodide was added so as to have a concentration of mol / liter. Further, a dye adsorption electrode T-3 was prepared in the same manner as the dye adsorption electrode T-1, except that the ruthenium complex dye R-10 was used instead of the ruthenium complex dye R-1.
[0152]
(2) Fabrication of treated electrodes
Any one of the dye adsorption electrodes T-1 to T-3 is immersed in one of the treatment liquids A-1 to A-5 shown in Table 1 below at 40 ° C. for 1.5 hours, washed with acetonitrile, and then in a nitrogen stream. Then, it was dried in a dark place to prepare treated electrodes TA-1 to TA-11. Table 1 shows compound (I), compound (II) and additives contained in each treatment solution. The concentrations of compound (I), compound (II) and additives in each treatment solution were 0.01 mol / liter, respectively, and acetonitrile was used as a solvent for the treatment solution. Table 1 shows the pKa values of the compound (I) and t-butylpyridine used.
[0153]
[Table 1]
[0154]
3. Production of photoelectric conversion element
(1) Photoelectric conversion element using electrolyte
The dye-adsorbed titanium oxide electrode T-1 (2 cm × 2 cm) obtained as described above was superposed on a platinum-deposited glass having the same size. Next, using a capillary phenomenon in the gap between the two glasses, an electrolyte (1,3-dimethylimidazolium iodide (0.65 mol / l) and iodine (0.05 mol / l) in acetonitrile) was soaked in titanium oxide. It introduced in the electrode and obtained the photoelectric conversion element CS-1 for a comparison. As shown in FIG. 10, this photoelectric conversion element is composed of conductive glass 1 (with a conductive layer 3 formed on glass 2), a dye-adsorbed titanium dioxide layer 4, a charge transport layer 5, a platinum layer 6, and glass. 7 has a layered structure. In addition, the photoelectric conversion elements CS-2 to CS-6 for comparison and the photoelectric conversion element of the present invention were produced in the same manner as the production of the photoelectric conversion element CS-1 except that the electrodes were changed to those shown in Table 2 below. CS-7 to CS-14 were prepared respectively.
[0155]
(2) Photoelectric conversion element using molten salt electrolyte composition
A 25 μm-thick thermoplastic resin (1.5 cm × 1.5 cm) having a round hole with a diameter of 1 cm was placed on the titanium dioxide layer (2 cm × 2 cm) of the electrode T-1, and pressure-bonded at 100 ° C. for 20 seconds. Thereafter, 2: 1 (1: 1-methyl-3-propylimidazolium iodide (Y6-8) and 1-ethyl-3-methylimidazolium tetrafluoroborate (Y6-2) are inserted into the holes of the thermoplastic resin. (Mass ratio) 2 mass% iodine I in the mixture₂10 μl of the molten salt electrolyte composition prepared by dissolving the solution was poured and left at 50 ° C. for 12 hours to allow the molten salt electrolyte composition to soak into the dye-adsorbed titanium dioxide electrode. Subsequently, a platinum-deposited glass (2 cm × 3 cm) was placed on this electrode, and the excess molten salt electrolyte composition that had protruded was wiped off, followed by pressure bonding at 130 ° C. for 30 seconds to produce a comparative photoelectric conversion element CM-1. Was made. All of these operations were performed in a dry room having a dew point of -50 ° C or lower. As shown in FIG. 10, this photoelectric conversion element is composed of conductive glass 1 (with a conductive layer 3 formed on glass 2), a dye-adsorbed titanium dioxide layer 4, a charge transport layer 5, a platinum layer 6, and glass. 7 has a layered structure.
In addition, the photoelectric conversion elements CM-2 to CM-6 for comparison and the photoelectric conversion element of the present invention were produced in the same manner as the production of the photoelectric conversion element CM-1, except that the electrodes were changed to those shown in Table 3 below. CM-7 to CM-14 were prepared.
[0156]
4. Measurement of photoelectric conversion efficiency
Simulated sunlight was generated by passing light from a 500 W xenon lamp (USHIO) through a spectral filter ("AM1.5" manufactured by Oriel). The intensity of this simulated sunlight is 100mW / cm on the vertical plane.²Met. A silver paste is applied to the end of the conductive glass of each of the photoelectric conversion elements CS-1 to CS-14 and CM-1 to CM-14 to form a negative electrode, and this negative electrode and platinum-deposited glass (positive electrode) are used as a current-voltage measuring device. (Connected to Keithley SMU238) The photoelectric conversion efficiency was obtained by measuring the current-voltage characteristics while irradiating each photoelectric conversion element with simulated sunlight vertically. Tables 2 and 3 show the conversion efficiency of each photoelectric conversion element.
[0157]
[Table 2]
[0158]
[Table 3]
[0159]
From Table 2 and Table 3, compared with the comparative photoelectric conversion elements CS-1 to CS-6 and CM-1 to CM-6 in which the semiconductor fine particles are not treated with the compound (I), the compound (I) It can be seen that the processed photoelectric conversion elements CS-7 to CS-14 and CM-7 to CM-14 of the present invention all have high conversion efficiency regardless of the type of adsorbed dye or the type of charge transport material. It can also be seen that when the semiconductor fine particles are treated with the compounds (I) and (II), the conversion efficiency is further improved.
[0160]
Example 2
As shown in Table 4 below, comparative photoelectric conversion elements CO-1 and CO- were used in the same manner as in Example 1 except that merocyanine dye M-3 or squarylium dye M-1 was used instead of ruthenium complex dye. 2, CO-4 and CO-5, and photoelectric conversion elements CO-3 and CO-6 of the present invention were produced. In addition, the said molten salt electrolyte composition was used as a charge transport material. The concentration of each dye in the dye adsorbent is 1 x 10^-Fourmol / l. The conversion efficiency of each photoelectric conversion element was measured in the same manner as in Example 1. As shown in Table 4, the photoelectric conversion elements CO-3 and CO-6 of the present invention in which the semiconductor fine particles were treated with the compound (I) were obtained. Showed excellent conversion efficiency.
[0161]
[Table 4]
[0162]
【The invention's effect】
As described above in detail, by treating the semiconductor fine particles with the compound (I), a dye-sensitized photoelectric conversion element having a conversion efficiency superior to that of the conventional one can be obtained. Further, when the semiconductor fine particles are treated with the compound (I) and the compound (II), the conversion efficiency can be further improved.
[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 illustrating a structure of a photoelectric conversion element manufactured in an example.
[Explanation of symbols]
10 ... conductive layer
10a ・ ・ ・ Transparent conductive layer
11 ... Metal lead
20 ... Photosensitive layer
21 ... Semiconductor fine particles
22 ... Dye
23 ... Charge transport material
30 ... Charge transport layer
40 ... Counterelectrode conductive layer
40a ・ ・ ・ Transparent counter conductive layer
50 ... Board
50a ・ ・ ・ Transparent substrate
60 ... Undercoat layer
1 ... conductive glass
2 ... Glass
3. Conductive layer
4 ... Dye adsorption titanium dioxide layer
5 ... Charge transport layer
6 ... Platinum layer
7 ... Glass

Claims (8)

In a method for producing a photoelectric conversion element comprising a layer of semiconductor fine particles adsorbed with a dye and a conductive support, the semiconductor fine particle is treated with a compound represented by the following general formula (I): How to create
(A ₁ -L) _n1 -A ₂・ M (I)
In general formula (I), A ₁ represents a group having N ⁻ , A ₂ represents a pyridyl group or an imidazolyl group , and M represents a cation that neutralizes the negative charge of (A ₁ -L) _n1 -A _2. L represents a divalent linking group or a simple bond, and n1 represents an integer of 1 to 3. 2. The method for producing a photoelectric conversion device according to claim 1 , wherein the semiconductor fine particles are treated with a compound represented by the general formula (I) and a compound represented by the following general formula (II). A method for creating a conversion element.
In general formula (II), X represents an oxygen atom , and R ¹ and R ² are each independently a hydrogen atom, an aliphatic hydrocarbon group, an aryl group, a heterocyclic group, -OR ⁴ , -N (R ⁵ ) ( R ⁶ ), —C (═O) R ⁷ , —C (═S) R ⁸ or SO ₂ R ⁹ , Y represents a hydrogen atom, an aliphatic hydrocarbon group, an aryl group, a heterocyclic group, —OR ⁴ represents ^{-N (R 5) (R 6} ) or -SR ^10. R ³ represents a hydrogen atom, an aliphatic hydrocarbon group, a hydroxy group or an alkoxy group, R ⁴ represents a hydrogen atom or an aliphatic hydrocarbon group, and R ⁵ and R ⁶ have the same meanings as R ¹ and R ² . R ⁷ , R ⁸ and R ⁹ are synonymous with Y, and R ¹⁰ is synonymous with R ⁴ . In the creation method of a photoelectric conversion element according to claim 2, the method of creating a photoelectric conversion element, wherein the Y represents ^{-N (R 5) (R 6} ). In the creation method of a photoelectric conversion element according to claim 2 or 3, having a substituent group the compound represented by the general formula (II) is represented by ^{-Si (R 11) (R 12} ) (R 13) A method for producing a photoelectric conversion element. However, R ¹¹ , R ¹² and R ¹³ each independently represent a hydroxy group, an alkyloxy group, an isocyanate group, a halogen atom or an aliphatic hydrocarbon group, and at least one of R ¹¹ , R ¹² and R ¹³ is an alkyl group. An oxy group, an isocyanate group or a halogen atom; 5. The method for producing a photoelectric conversion element according to claim 1 , wherein the compound represented by the general formula (I) and / or the general formula (II) is used after the dye is adsorbed to the semiconductor fine particles. A method for producing a photoelectric conversion element, characterized by treatment with a compound represented by the formula: The method for producing a photoelectric conversion element according to claim 1 , wherein the dye is a ruthenium complex dye. A photoelectric conversion element produced by the method according to claim 1 . A photovoltaic cell comprising the photoelectric conversion element according to claim 7 .