JP2011057828A - Novel photosensitizer and photoelectromotive force element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a novel photosensitizer which absorbs a broad region of ray from visible ray to infrared ray, and has a sufficient photoelectric conversion performance. <P>SOLUTION: The photosensitizer comprises a metal complex which has a structure represented by formula (I), wherein the symbols are each specifically defined. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a novel photosensitizer, and more particularly to a novel photosensitizer that is suitably used for a dye-sensitized solar cell. The present invention also relates to a photovoltaic device using the novel photosensitizer.

  The dye-sensitized solar cell element announced by Gretzell et al. In 1991 is a wet solar cell using a titanium oxide porous thin film spectrally sensitized by a ruthenium complex as a working electrode, and can obtain performance equivalent to that of a silicon solar cell. Has been reported (see Non-Patent Document 1). Since this method can use an inexpensive oxide semiconductor such as titania without purifying it with high purity, it can provide an inexpensive dye-sensitized solar cell element, and since the absorption of the dye is broad, it is visible. It has the advantage of being able to convert light in almost all wavelength regions of light into electricity, and has attracted attention.

  However, the known ruthenium complex dye absorbs visible light but hardly absorbs infrared light having a wavelength longer than 700 nm, and thus has a low photoelectric conversion ability in the infrared region. Therefore, in order to further increase the conversion efficiency, development of a dye having absorption not only in the visible light but also in the infrared region has been desired.

  On the other hand, a black die which is a kind of ruthenium complex dye can absorb light up to 920 nm. Moreover, in the following patent document 1, a photosensitizer capable of absorbing light in a wide range from visible light to infrared light is proposed.

JP 2009-64680 A

B. O'Regan, M. Graetzel, "Nature", (UK), 1991, 353, p. 737

  However, even with the above-described black die and the photosensitizer described in Patent Document 1, the amount of light absorption and photoelectric conversion characteristics in the infrared region are not always sufficient. There is a need for improvement.

  The present invention has been made in view of the above-mentioned problems of the prior art, absorbs a wide range of light from visible light to infrared light, and has a novel photosensitizer having sufficient photoelectric conversion characteristics, And it aims at providing a photovoltaic device using the same.

［式（Ｉ）中、Ｒ^１は水素原子、ハロゲン原子、アルキル基、アルキルアミノ基、ヒドロキシル基、アルコキシ基、アシル基、エステル基、シアノ基、ニトロ基、アミノ基、アルコキシアルキル基、アミノアルキル基、パーフルオロアルキル基、アリール基又は複素環基、或いは、カルボキシル基、スルホン酸基若しくはリン酸基又はそれらの金属塩、四級アンモニウム塩若しくは窒素含有複素環塩を示し、Ｒ^２、Ｒ^３、Ｒ^４及びＲ^５はそれぞれ独立に、水素原子、ハロゲン原子、アルキル基、アルキルアミノ基、ヒドロキシル基、アルコキシ基、アシル基、エステル基、シアノ基、ニトロ基、アミノ基、アルコキシアルキル基、アミノアルキル基、パーフルオロアルキル基、アリール基又は複素環基、或いは、カルボキシル基、スルホン酸基若しくはリン酸基又はそれらの金属塩、四級アンモニウム塩若しくは窒素含有複素環塩、或いは、カルボキシル基、スルホン酸基若しくはリン酸基又はそれらの金属塩、四級アンモニウム塩若しくは窒素含有複素環塩を置換基として有するアリール基を示し、Ｒ^６は水素原子、ハロゲン原子、アルキル基、アルキルアミノ基、ヒドロキシル基、アルコキシ基、アシル基、エステル基、シアノ基、ニトロ基、アミノ基、アルコキシアルキル基、アミノアルキル基、パーフルオロアルキル基、アリール基又は複素環基、或いは、カルボキシル基、スルホン酸基若しくはリン酸基又はそれらの金属塩、四級アンモニウム塩若しくは窒素含有複素環塩、或いは、カルボキシル基、スルホン酸基若しくはリン酸基又はそれらの金属塩、四級アンモニウム塩若しくは窒素含有複素環塩を置換基として有するアリール基、或いは、Ｍに配位する窒素原子を含む下記一般式（Ｉ−ａ）で表されるイミノ基又はＭに配位する窒素原子を含む下記一般式（Ｉ−ｂ）で表されるピリジル基を示し、Ｘはそれぞれ独立にハロゲン原子、ヒドロキシ基、シアノ基、メチル基、水素原子、チオシアネート基、ヒドラジド基、アジド基、イソシアニド基、シアネート基、イソチオシアネート基又はニトロ基を示し、Ｌは下記一般式（Ｉ−ｃ）又は（Ｉ−ｄ）で表される２座配位子、或いは、下記一般式（Ｉ−ｅ）で表される３座配位子を示し、Ｚは炭素原子、窒素原子、硫黄原子又はリン原子を示し、Ｍは鉄原子、ルテニウム原子、オスミウム原子、コバルト原子、ロジウム原子、イリジウム原子又はレニウム原子を示し、ｐは０〜２の整数を示し、ｑは１〜４の整数を示し、ｒは０又は１を示す。］

［式（Ｉ−ａ）、（Ｉ−ｂ）、（Ｉ−ｃ）、（Ｉ−ｄ）及び（Ｉ−ｅ）中、Ｒ^１１、Ｒ^１２、Ｒ^１３、Ｒ^１４、Ｒ^１５、Ｒ^１６、Ｒ^１７、Ｒ^１８、Ｒ^１９、Ｒ^２０及びＲ^２１はそれぞれ独立に、水素原子、ハロゲン原子、アルキル基、アルキルアミノ基、ヒドロキシル基、アルコキシ基、アシル基、エステル基、シアノ基、ニトロ基、アミノ基、アルコキシアルキル基、アミノアルキル基、パーフルオロアルキル基、アリール基又は複素環基、或いは、カルボキシル基、スルホン酸基若しくはリン酸基又はそれらの金属塩、四級アンモニウム塩若しくは窒素含有複素環塩を示す。］ In order to achieve the above object, the present invention provides a photosensitizer comprising a metal complex containing a structure represented by the following general formula (I).

[In the formula (I), R ¹ represents a hydrogen atom, a halogen atom, an alkyl group, an alkylamino group, a hydroxyl group, an alkoxy group, an acyl group, an ester group, a cyano group, a nitro group, an amino group, an alkoxyalkyl group, an aminoalkyl group. A group, a perfluoroalkyl group, an aryl group or a heterocyclic group, or a carboxyl group, a sulfonic acid group or a phosphoric acid group, or a metal salt, a quaternary ammonium salt or a nitrogen-containing heterocyclic salt thereof; R ² , R ³ , R ⁴ and R ⁵ are each independently a hydrogen atom, halogen atom, alkyl group, alkylamino group, hydroxyl group, alkoxy group, acyl group, ester group, cyano group, nitro group, amino group, alkoxyalkyl group, amino group Alkyl group, perfluoroalkyl group, aryl group or heterocyclic group, carboxyl group, sulfo group Acid group or phosphate group or metal salt thereof, quaternary ammonium salt or nitrogen-containing heterocyclic salt, or carboxyl group, sulfonic acid group or phosphoric acid group or metal salt thereof, quaternary ammonium salt or nitrogen-containing complex R ⁶ represents an aryl group having a ring salt as a substituent, and R ⁶ represents a hydrogen atom, a halogen atom, an alkyl group, an alkylamino group, a hydroxyl group, an alkoxy group, an acyl group, an ester group, a cyano group, a nitro group, an amino group, an alkoxy group. An alkyl group, an aminoalkyl group, a perfluoroalkyl group, an aryl group or a heterocyclic group, or a carboxyl group, a sulfonic acid group or a phosphoric acid group or a metal salt thereof, a quaternary ammonium salt or a nitrogen-containing heterocyclic salt, or Carboxyl group, sulfonic acid group or phosphoric acid group or their metal salts, quaternary ammonia An aryl group having a nium salt or a nitrogen-containing heterocyclic salt as a substituent, an imino group represented by the following general formula (Ia) containing a nitrogen atom coordinated to M, or a nitrogen atom coordinated to M Including a pyridyl group represented by the following general formula (Ib), wherein X is independently a halogen atom, a hydroxy group, a cyano group, a methyl group, a hydrogen atom, a thiocyanate group, a hydrazide group, an azide group, an isocyanide group, A cyanate group, an isothiocyanate group or a nitro group is shown, and L is a bidentate ligand represented by the following general formula (Ic) or (Id) or represented by the following general formula (Ie). Z represents a carbon atom, nitrogen atom, sulfur atom or phosphorus atom, M represents an iron atom, ruthenium atom, osmium atom, cobalt atom, rhodium atom, iridium atom or rhenium Represents an atomic, p represents an integer of 0 to 2, q represents an integer of 1 to 4, r is 0 or 1. ]

[Formula (I-a), (I -b), (I-c), (I-d) and in ^{(I-e), R 11} , R 12, R 13, R 14, R 15, R 16 , R ¹⁷ , R ¹⁸ , R ¹⁹ , R ²⁰ and R ²¹ are each independently a hydrogen atom, halogen atom, alkyl group, alkylamino group, hydroxyl group, alkoxy group, acyl group, ester group, cyano group, nitro group , Amino group, alkoxyalkyl group, aminoalkyl group, perfluoroalkyl group, aryl group or heterocyclic group, or carboxyl group, sulfonic acid group or phosphoric acid group or metal salt thereof, quaternary ammonium salt or nitrogen-containing complex A ring salt is shown. ]

  According to the photosensitizer comprising the metal complex including the structure represented by the general formula (I), it is possible to sufficiently absorb a wide range of light from visible light to infrared light, and sufficient Photoelectric conversion characteristics can be obtained.

  The present invention also provides a photovoltaic device comprising a metal oxide semiconductor layer containing the photosensitizer of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, the novel photosensitizer which absorbs the light of a wide range from visible light to infrared light, and has sufficient photoelectric conversion characteristics, and a photovoltaic device using the same are provided. be able to.

It is a schematic cross section which shows suitable one Embodiment of the photovoltaic device of this invention. It is a figure which shows the 2D-NMR analysis result of the complex pigment | dye (ttt-I ester body) produced in the Example. It is a figure which shows the 2D-NMR analysis result of the complex pigment | dye (tcc-I ester body) produced in the Example. It is a figure which shows the 2D-NMR analysis result of the complex pigment | dye (cct-I ester body) produced in the Example. It is a figure which shows the spectral absorption spectrum of the photosensitizer of Examples 1-4 and the comparative example 1. It is a figure which shows the incident photon-current conversion efficiency (IPCE) in the photovoltaic cell using the photosensitizer of Examples 1-4.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings as the case may be. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios.

The photosensitizer of the present invention comprises a metal complex (complex dye) containing a structure represented by the following general formula (I).

In general formula (I), R ¹ is a hydrogen atom, halogen atom, alkyl group, alkylamino group, hydroxyl group, alkoxy group, acyl group, ester group, cyano group, nitro group, amino group, alkoxyalkyl group, aminoalkyl. Group, perfluoroalkyl group, aryl group or heterocyclic group, or carboxyl group, sulfonic acid group or phosphoric acid group, or a metal salt, quaternary ammonium salt or nitrogen-containing heterocyclic salt thereof, hydrogen atom, carboxyl group , An alkyl group, an alkylamino group, an alkoxy group or an alkoxyalkyl group, and more preferably a hydrogen atom or a carboxyl group.

In general formula (I), R ² , R ³ , R ⁴ and R ⁵ are each independently a hydrogen atom, halogen atom, alkyl group, alkylamino group, hydroxyl group, alkoxy group, acyl group, ester group, cyano group. Nitro group, amino group, alkoxyalkyl group, aminoalkyl group, perfluoroalkyl group, aryl group or heterocyclic group, or carboxyl group, sulfonic acid group or phosphoric acid group or metal salt thereof, quaternary ammonium salt or A nitrogen-containing heterocyclic salt, or an aryl group having a carboxyl group, a sulfonic acid group or a phosphoric acid group or a metal salt, a quaternary ammonium salt or a nitrogen-containing heterocyclic salt as a substituent. Among these, R ² is preferably an aryl group, an aryl group having a carboxyl group as a substituent, or a heterocyclic group, more preferably an aryl group or an aryl group having a carboxyl group as a substituent. preferable. R ³ , R ⁴ and R ⁵ are each independently preferably a hydrogen atom, a carboxyl group, an alkyl group, an alkylamino group, an alkoxy group or an alkoxyalkyl group, more preferably a hydrogen atom or a carboxyl group. preferable.

In general formula (I), R ⁶ represents a hydrogen atom, a halogen atom, an alkyl group, an alkylamino group, a hydroxyl group, an alkoxy group, an acyl group, an ester group, a cyano group, a nitro group, an amino group, an alkoxyalkyl group, an aminoalkyl. Group, perfluoroalkyl group, aryl group or heterocyclic group, carboxyl group, sulfonic acid group or phosphoric acid group, or metal salts thereof, quaternary ammonium salt or nitrogen-containing heterocyclic salt, or carboxyl group, sulfonic acid An aryl group having a group or a phosphate group or a metal salt thereof, a quaternary ammonium salt or a nitrogen-containing heterocyclic salt as a substituent, or the following general formula (Ia) containing a nitrogen atom coordinated to M Or a pyridyl group represented by the following general formula (Ib) containing a nitrogen atom coordinated to M, and coordinated to M It is preferably an imino group represented by the following general formula (Ia) containing a nitrogen atom.

In the general formula (I), R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are independent substituents and do not have a bond between these substituents.

  In general formula (I), each X independently represents a halogen atom, hydroxy group, cyano group, methyl group, hydrogen atom, thiocyanate group, hydrazide group, azide group, isocyanide group, cyanate group, isothiocyanate group or nitro group. , A halogen atom, a thiocyanate group, a hydroxy group or a cyano group, more preferably a halogen atom or a thiocyanate group.

  In general formula (I), L is a bidentate ligand represented by the following general formula (Ic) or (Id), or a tridentate represented by the following general formula (Ie) A bidentate ligand, which represents a ligand and is represented by the following general formula (Ic) or (Id), is preferable.

  In general formula (I), Z represents a carbon atom, a nitrogen atom, a sulfur atom or a phosphorus atom, preferably a carbon atom or a nitrogen atom, and more preferably a carbon atom.

  In the general formula (I), M represents an iron atom, ruthenium atom, osmium atom, cobalt atom, rhodium atom, iridium atom or rhenium atom, preferably an iron atom, ruthenium atom or osmium atom, and is a ruthenium atom. It is more preferable.

In general formula (I), p represents an integer of 0 to 2, q represents an integer of 1 to 4, and r represents 0 or 1. Among these, p is 2 when Z is a phosphorus atom, 1 when Z is a sulfur atom or a carbon atom, and 0 when Z is a nitrogen atom. Further, q varies depending on the number of nitrogen coordinated to M. Further, r varies depending on the value of q and the number of nitrogens coordinated to M. For example, q is 3 and R ⁶ is represented by the general formula (Ia) or (Ib). 0 can be taken when In addition, since the effect of this invention is acquired more fully, it is preferable that p is 1, q is 2, and r is 1.

In the general formulas (Ia), (Ib), (Ic), and (Id), R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ , R ^{17 are used.} , R ¹⁸ , R ¹⁹ , R ²⁰ and R ²¹ are each independently a hydrogen atom, halogen atom, alkyl group, alkylamino group, hydroxyl group, alkoxy group, acyl group, ester group, cyano group, nitro group, amino group An alkoxyalkyl group, an aminoalkyl group, a perfluoroalkyl group, an aryl group or a heterocyclic group, or a carboxyl group, a sulfonic acid group or a phosphoric acid group, or a metal salt, a quaternary ammonium salt or a nitrogen-containing heterocyclic salt thereof. Show. Among these, R ¹¹ is preferably an aryl group or a heterocyclic group, and more preferably an aryl group. R ^{12 to} R ²¹ are preferably a hydrogen atom, a carboxyl group, an alkyl group, an alkylamino group, an alkoxy group or an alkoxyalkyl group, and more preferably a hydrogen atom or a carboxyl group.

  The structure represented by the general formula (I) is preferably a structure represented by the following general formula (II), since the effects of the present invention can be obtained more sufficiently. The structure represented is more preferable, and the structure represented by the following general formula (IV) is particularly preferable.

In the general formulas (II) to (IV), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ¹⁴ , R ¹⁵ , R ¹⁶ , X, L, Z, and M are as described above. R ²² represents a hydrogen atom, a carboxyl group, a sulfonic acid group or a phosphoric acid group, or a metal salt, a quaternary ammonium salt or a nitrogen-containing heterocyclic salt thereof, and R ²³ represents R ^{3 to} R ⁵ . It is synonymous. However, in the general formulas (II) and (III), R ⁶ is a group other than the group represented by the general formula (Ia) or (Ib), and Z is a carbon atom or a nitrogen atom. And L is a bidentate ligand represented by the above general formula (Ic) or (Id). In the general formulas (II) and (III), R ¹ , R ³ , R ⁴ , R ⁵ , R ⁶ and R ²² are a hydrogen atom or a carboxyl group, and at least one of them is a carboxyl group It is preferable that Further, in the general formula (IV), R ¹ , R ¹⁴ , R ¹⁵ , R ¹⁶ , R ²² and R ²³ are a hydrogen atom or a carboxyl group, and at least one of them is a carboxyl group. preferable.

Moreover, the photosensitizer of the present invention may have a counter ion having a structure represented by the general formula (I). Examples of the counter ion include halide ions, PF ₆ ⁻ , BF ₄ ⁻ , ClO ₄ ⁻ , BR ₄ ⁻ , RSO ₃ ⁻ and NBu ₄ ⁺ .

  The structure represented by the general formula (I) can take a plurality of geometric isomers, but the photosensitizer of the present invention may be composed of any isomer. The photosensitizer of the present invention may be composed of only one kind of isomer or may be composed of a mixture of two or more kinds of isomers.

  Specific examples of the photosensitizer comprising the metal complex having the structure represented by the general formula (I) include the following.

  Next, a method for synthesizing the photosensitizer of the present invention will be described. In the following, a case where ruthenium is used as M in the general formula (I) will be described as an example. As a method for synthesizing the photosensitizer of the present invention, a method in which a ruthenium precursor is reacted with a ligand containing a nitrogen atom coordinated to ruthenium in the molecule and a compound containing X in the molecule is preferably used. It is done.

  As the ruthenium precursor, for example, ruthenium chloride, dichloro (p-cymene) ruthenium dimer, diiodo (p-cymene) ruthenium dimer, or the like can be used.

  When two kinds of different ligands are reacted with the ruthenium precursor, these reactions may be carried out by sequentially adding them, or they may be carried out by adding them simultaneously. When performing reaction sequentially, the order of the ligand to add is not specifically limited.

  As a reaction solvent, a general organic solvent, water, or the like can be used, but alcohol solvents such as ethanol, methanol, and butanol, amide solvents such as dimethylformamide and dimethylacetamide, dimethyl sulfoxide, propylene carbonate, N- It is preferable to use a polar solvent such as methylpyrrolidone.

  The reaction temperature is not particularly limited, but it is preferable to warm from the viewpoint of efficiently proceeding the reaction, and it is particularly preferable to perform the reaction in a temperature range of 50 to 250 ° C. When two kinds of different ligands are reacted sequentially, the reaction temperature of the first stage reaction and the second stage reaction may be changed. Further, the heating can be performed using an oil bath, a water bath, a microwave heating device, or the like.

  Although reaction time is not specifically limited, Usually, it is 1 minute-several days, Preferably it is 5 minutes-1 day, It is preferable to change time with a heating apparatus.

  About X, it can introduce | transduce by adding corresponding ammonium salt, a metal salt, etc., and reacting. The reaction time and reaction temperature at that time are not particularly limited. The order of the step of introducing X into the ruthenium precursor and the step of reacting the ligand with the ruthenium precursor are not particularly limited, and either step may be performed first.

  Next, the photovoltaic element of the present invention will be described. The photovoltaic device of the present invention comprises a metal oxide semiconductor layer containing the above-described photosensitizer of the present invention.

  FIG. 1 is a schematic cross-sectional view showing a preferred embodiment of the photovoltaic element of the present invention. In the photovoltaic device shown in FIG. 1, a semiconductor layer (metal oxide semiconductor layer) 3 on which a photosensitizer of the present invention is adsorbed is disposed on a transparent conductive substrate 1 and is opposed to the semiconductor layer 3. An electrolyte layer 4 is disposed between the electrode substrate 2 and the periphery thereof is sealed with a sealing material 5. Note that the lead wire is connected to the conductive portions of the transparent conductive substrate 1 and the counter electrode substrate 2 so that electric power can be taken out.

  The transparent conductive substrate 1 is usually manufactured by laminating a transparent conductive layer on a transparent substrate. Here, it does not specifically limit as a transparent substrate, A material, thickness, a dimension, a shape, etc. can be suitably selected according to the objective. For example, as the transparent substrate, colorless or colored glass, netted glass, glass block, or the like may be used, or a colorless or colored transparent resin may be used. Specific examples of the resin include polyesters such as polyethylene terephthalate, polyamide, polysulfone, polyether sulfone, polyether ether ketone, polyphenylene sulfide, polycarbonate, polyimide, polymethyl methacrylate, polystyrene, cellulose triacetate, and polymethylpentene. Etc. The term “transparent” in the present invention means that it has a transmittance of 10 to 100%, and the substrate in the present invention has a smooth surface at room temperature, and the surface is a flat surface or a curved surface. It may be deformed by stress.

The transparent conductive layer that forms the conductive layer of the electrode is not particularly limited as long as it fulfills the object of the present invention. For example, a conductive thin film made of gold, silver, chromium, copper, tungsten, or the like, or a conductive film made of a metal oxide. Examples include membranes. Examples of the metal oxide include Indium Tin Oxide (ITO (In ₂ O ₃ : Sn)), Fluorine doped Tin Oxide (FTO (SnO ₂ : F)) in which tin oxide or zinc oxide is slightly doped with another metal element. ), Aluminum doped Zinc Oxide (AZO (ZnO: Al)) and the like are preferably used.

  The film thickness of the transparent electrode layer is usually 10 nm to 10 μm, preferably 100 nm to 2 μm. The surface resistance (resistivity) of the transparent electrode layer is appropriately selected depending on the use of the photovoltaic element, but is usually 0.5 to 500 Ω / sq, preferably 2 to 50 Ω / sq.

  As the counter electrode, platinum, carbon electrodes, etc. can be usually used. The material of the substrate is not particularly limited, and the material, thickness, size, shape, and the like can be appropriately selected according to the purpose. For example, as the substrate, colorless or colored glass, netted glass, glass block, or the like may be used, or a colorless or colored transparent resin may be used. Specific examples of the resin include polyesters such as polyethylene terephthalate, polyamide, polysulfone, polyether sulfone, polyether ether ketone, polyphenylene sulfide, polycarbonate, polyimide, polymethyl methacrylate, polystyrene, cellulose triacetate, and polymethylpentene. Etc. A metal plate or the like can also be used as the substrate.

As the semiconductor layer 3 used in the photovoltaic device of the present invention is not particularly limited, for _example, TiO 2, _ZnO, such as a layer made of SnO 2, _Nb 2 _{O 5} and the like, from among them _TiO 2, ZnO Is preferred.

  The semiconductor used for the semiconductor layer 3 may be single crystal or polycrystalline. As the crystal system, anatase type, rutile type, brookite type and the like are mainly used, and anatase type is preferable.

  A known method can be used to form the semiconductor layer 3. Examples of the method for forming the semiconductor layer 3 include a method in which the above-described semiconductor nanoparticle dispersion, sol solution, or the like is applied onto a substrate by a known method. The coating method in this case is not particularly limited, and various printing methods such as a screen printing method can be used in addition to a method obtained in a thin film state by a casting method, a spin coating method, a dip coating method, a bar coating method. it can.

  The thickness of the semiconductor layer 3 is not particularly limited, but is usually 0.5 μm to 50 μm, preferably 1 μm to 20 μm.

  As a method for adsorbing the photosensitizer of the present invention to the semiconductor layer 3, for example, a solution obtained by dissolving a photosensitizer in a solvent is applied on the semiconductor layer 3 by spray coating or spin coating, and then dried. Can be used. In this case, the substrate may be heated to an appropriate temperature. Alternatively, a method in which the semiconductor layer 3 is immersed and adsorbed in a solution in which a photosensitizer is dissolved can be used. The immersion time is not particularly limited as long as the photosensitizer is sufficiently adsorbed to the semiconductor layer 3, but is preferably 10 minutes to 30 hours, and more preferably 1 to 20 hours. Moreover, you may heat a solvent and a board | substrate as needed, when immersing. When preparing a solution in which the photosensitizer is dissolved, the concentration of the photosensitizer is preferably about 0.01 to 100 mmol / L, more preferably about 0.1 to 50 mmol / L. preferable. As the solvent, alcohols, ethers, nitriles, esters, hydrocarbons and the like can be used.

  Further, in order to reduce the interaction such as aggregation between the photosensitizers, a colorless compound having properties as a surfactant may be added and co-adsorbed to the semiconductor layer 3. Examples of such colorless compounds include steroid compounds such as cholic acid having a carboxyl group or sulfo group, deoxycholic acid, chenodeoxycholic acid, taurodeoxycholic acid, sulfonates, and the like.

  After the photosensitizer is adsorbed on the semiconductor layer 3 by the above-described method, it is preferable that the non-adsorbed photosensitizer is quickly removed by washing. Washing is preferably performed using acetonitrile, an alcohol-based solvent or the like in a wet washing tank.

The adsorption amount of the photosensitizer is calculated by detaching the photosensitizer from the semiconductor layer 3 using a strong alkali solution and measuring the light absorption amount of the alkali solution. This adsorption amount is preferably in the range of 1.0 × 10 ⁻⁸ mol / cm ^{2 to} 1.0 × 10 ⁻⁶ mol / cm ² with respect to the semiconductor surface area.

  After adsorbing the photosensitizer to the semiconductor layer 3, amines, quaternary ammonium salts, ureido compounds having at least one ureido group, silyl compounds having at least one silyl group, alkali metal salts, alkaline earth metals The surface of the semiconductor layer 3 may be treated with salt or the like. Examples of preferred amines include pyridine, 4-t-butylpyridine, polyvinylpyridine and the like. Examples of preferred quaternary ammonium salts include tetrabutylammonium iodide, tetrahexylammonium iodide and the like. These may be used by dissolving in an organic solvent, or may be used as they are in the case of a liquid.

  The electrolyte used for the electrolyte layer 4 is not particularly limited and may be either a liquid system or a solid system, but it is desirable to have a reversible electrochemical redox characteristic. Here, showing reversible electrochemical redox characteristics means that an electrochemical redox reaction can occur reversibly in the potential region where the photovoltaic element acts. Typically, it is usually desirable to be reversible in the potential region of −1 to +2 Vvs NHE with respect to the hydrogen reference electrode (NHE).

The ionic conductivity of the electrolyte is usually 1 × 10 ⁻⁷ S / cm or more at room temperature, preferably 1 × 10 ⁻⁶ S / cm or more, more preferably 1 × 10 ⁻⁵ S / cm or more. It is desirable to be.

  The thickness of the electrolyte layer 4 is not particularly limited, but is preferably 1 μm or more, more preferably 10 μm or more, and preferably 3 mm or less, more preferably 1 mm or less.

  The electrolyte is not particularly limited as long as the above-described conditions are satisfied, and those known in the art such as liquid systems and solid systems, and quasi-solid systems in which a solid system electrolyte contains a plasticizer may be used. Can be used.

  As the sealing material 5, for example, an epoxy resin, an acrylic resin, a Teflon (registered trademark) resin, a photocurable resin such as butyl rubber, a thermosetting resin, or a thermoplastic resin is used. An inorganic sealing material containing glass powder or the like can also be used.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example.

[Examples 1 to 4]
(Synthesis of bidentate chelate ligand)
First, 4.73 g of 4-aminobenzoic acid and 20 ml of thionyl chloride were added to 70 ml of toluene, and this mixture was reacted by stirring at 110 ° C. for 6 hours in an argon atmosphere. After the obtained reaction product was returned to room temperature, the reaction product was slowly added dropwise to 84 ml of tertiary butyl alcohol in a water bath and further stirred at 110 ° C. for 1 hour. Next, 120 ml of saturated aqueous potassium carbonate solution was added to the reaction product, and 80 ml of chloroform was further added, and extraction operation was performed three times. The extracted organic layer was dried over 150 mg of magnesium sulfate and filtered, and then the solvent contained in the filtrate was distilled off. Thereafter, the target product was separated by silica gel column chromatography using chloroform as a developing solvent, and recrystallized from a carbon tetrachloride / hexane mixed solvent to obtain 2.7 g of aminobutyl tert-butylaminobenzoate (below) Reaction formula (a) reference).

Next, 2320 mg of aminobenzoic acid tertiary butyl ester and 1160 μl of 2-pyridinecarbaldehyde were added to 20 ml of ethanol and stirred at room temperature for 30 minutes, and then the solvent was distilled off. Thereafter, dichloromethane and pentane were added to the reaction product and recrystallized to obtain 2.12 g of tertiary butyl ester as a target bidentate chelate ligand (see the following reaction formula (b)). The structure and purity of the product were identified by ¹ H-NMR. The results of ¹ H-NMR analysis are shown below.
¹ H NMR (CDCl ₃ ): δ 8.76 (1H, d, J = 4.4); 8.60 (1H, s); 8.24 (1H, d, J = 7.9); 8.14 (2H, d, J = 8.4); 7.89 (2H, d, J = 8.4); 7.87 (1H, dd, J = 7.9., 7.1); 7.43 (1H, dd, J = 7.1, 4.9)

(Synthesis of complex dye 1)
First, 360 mg of ruthenium chloride and 1.5 g of lithium iodide were added to 200 ml of ethanol, and this mixture was stirred at 90 ° C. for 30 minutes in an argon atmosphere. Thereafter, 1.25 g of the bidentate chelate ligand was added to the mixture, and the mixture was further stirred at 90 ° C. for 30 minutes. Next, the solvent of the obtained reaction product was distilled off, and the target product was separated by silica gel column chromatography using chloroform: acetonitrile = 8: 2 as a developing solvent, and reprecipitated with chloroform / ethanol. The complex dye was obtained. As the complex dye, three types of isomers were obtained, 124 mg of the ttt-I ester, 56 mg of the tcc-I ester, and 114 mg of the cct-I ester (the following reaction formula (c )reference). The structures of these isomers were identified by ¹ H-NMR and 2D-NMR (1H-1H COSY). The results of ¹ H-NMR analysis are shown below, and the results of 2D-NMR analysis are shown in FIGS. As shown in FIGS. 2 to 4, in the ttt-I ester, a and b are close to each other and coupled (FIG. 2), and in the tcc-I ester, a and b are separated from each other. In the ester body of cct-I, a and b are relatively close to each other and are weakly coupled (FIG. 4).
¹ H NMR (CDCl ₃ ): [ttt-I ester]: δ 8.87 (1H, s); 8.21 (2H, d, J = 8.2); 8.08 (2H, d, J = 8.2); 7.94 (1H, d, J = 5.7); 7.90 (1H, d, J = 7.5); 7.68 (1H, dd, J = 7.5., 7.5); 7.00 (1H, dd, J = 5.7, 7.5); 1.56 (9H, s )
[tcc-I ester]: δ9.69 (1H, d, J = 5.6); 8.57 (1H, s); 8.00 (1H, d, J = 7.6); 7.93 (1H, dd, J = 7.6, 7, 6); 7.65 (1H, dd, J = 5.6, 7.6); 7.58 (2H, d, J = 8.2); 7.33 (2H, d, J = 8.2); 1.56 (9H, s)
[cct-I ester]: δ 10.16 (1H, d, J = 5.7); 8.72 (1H, s); 7.81 (1H, d, J = 7.7); 7.73 (2H, d, J = 8.4); 7.65 (1H, dd, J = 7.7, 7.7); 7.36 (1H, dd, J = 7.7, 5.7); 7.04 (2H, d, J = 8.4); 1.56 (9H, s)

Next, 10 mg of the ester of ttt-I was added to 5 ml of chloroform, 20 ml of trifluoroacetic acid was added thereto, and the mixture was stirred at room temperature for 30 minutes. Thereafter, the solvent was distilled off completely, and then dichloromethane was added and the solvent was distilled off five times. The obtained reaction product was purified and separated by gel permeation chromatography (Sephadex LH-20) using methanol as a developing solvent to obtain the target complex dye (see the following reaction formula (d)). This complex dye was used as the photosensitizer of Example 1. Further, the structure of the obtained complex dye was identified by mass spectrometry. The analysis results are shown below.
MS (ESI-MS): m / z: 402.4 (M-2H) ^2- , 806.4 (MH) ^- ; MW: 807.34 calcd.for C ₂₆ H ₂₄ I ₂ N ₄ O ₄ Ru

(Synthesis of complex dye 2)
20 mg of the ester of ttt-I obtained in Synthesis 1 of the complex dye was added to 20 ml of 2-methoxyethanol, and a mixture of 150 mg of lead (II) thiocyanate in 1 ml of water was added thereto. Stir for hours. Thereafter, the reaction product was filtered, the solvent of the obtained filtrate was distilled off, and 5 ml of 2-methoxyethanol and 100 ml of water were added thereto for reprecipitation to obtain an ester of ttt-NCS ( See the following reaction formula (e)). The same operation was performed on other isomers to obtain ester bodies of tcc-NCS and cct-NCS. The structure of these ester bodies was confirmed by mass spectrometry. The analysis results are shown below.
MS (ESI-MS): m / z: [ttt-NCS ester] 781.4 (M) ⁺ ;
[tcc-NCS ester] 781.2 (M) ⁺ ;
[cct-NCS ester] 781.4 (M) ⁺ ;
MW: 781.91 calcd.for C ₃₆ H ₃₆ N ₆ O ₄ RuS ₂

Next, 10 mg of the ester of ttt-NCS was added to 5 ml of chloroform, 20 ml of trifluoroacetic acid was added thereto, and the mixture was stirred at room temperature for 30 minutes. Thereafter, the solvent was distilled off completely, and then dichloromethane was added and the solvent was distilled off five times. The obtained reaction product was purified and separated by gel permeation chromatography (Sephadex LH-20) using methanol as a developing solvent to obtain a target complex dye (see the following reaction formula (f)). This complex dye was used as the photosensitizer of Example 2. The same operation was performed on the ester bodies of tcc-NCS and cct-NCS, and the resulting complex dyes were used as the photosensitizers of Examples 3 and 4, respectively. The structure of the obtained complex dye was identified by mass spectrometry. The analysis results are shown below.
MS (ESI-MS): m / z: [ttt-NCS] 334.4 (M-2H) ^2- , 668.4 (MH) ^- ;
[tcc-NCS] 334.2 (M-2H) ^2- , 668.2 (MH) ^- ;
[cct-NCS] 334.4 (M-2H) ^2- , 668.4 (MH) ^- ;
MW: 669.7 calcd.for C ₂₈ H ₂₀ N ₆ O ₄ RuS ₂

  The photosensitizers of Examples 1 to 4 produced by the above procedure are represented by the following formulas (1) to (4), respectively.

[Comparative Example 1]
The complex dye represented by the following formula (5) (trade name: N719, manufactured by Solaronics) was used as the photosensitizer of Comparative Example 1.

[Comparative Example 2]
Dichloro (p-cymene) ruthenium dimer (1.22 g; 2 mmol) and 2,2′-bipyridine-4,4′-dicarboxylic acid (0.49 g; 2 mmol) were dissolved in ethanol and heated to reflux for 3 hours. . After completion of the reaction, the solvent was distilled off to obtain Compound A.

  On the other hand, phenanthrolinediamine was synthesized by the method described in the literature (Tetrahedron letters 38, 8159 (1997)). Phenanthrolinediamine (0.21 g; 1.0 mmol) and salicylaldehyde (0.24 g; 2.0 mmol) were dissolved in ethanol, orthoformate (0.1 ml) was added, and the mixture was heated to reflux for 3 hours. After completion of the reaction, Compound B was obtained by filtration.

  Compound A and Compound B were dissolved in DMF and heated and stirred at 135 ° C. for 4 hours to obtain Compound C. Then, ammonium thiocyanate (0.4 g) was added, and the mixture was heated to reflux for 4 hours. After completion of the reaction, the mixture was concentrated under reduced pressure, dispersed in water, and filtered. The obtained solid was purified by column chromatography (filler: Sephadex LH-20, eluent: DMF) to obtain 0.3 g (0.3 mmol) of a complex dye represented by the following formula (6). . This was used as the photosensitizer of Comparative Example 2.

[Measurement of absorption spectrum]
About the photosensitizer obtained in Examples 1-4 and the comparative example 1, the spectral absorption spectrum from visible light to infrared light was measured with the spectrophotometer (brand name: V570 product made from JASCO Corporation). The measurement liquid was prepared in a DMF solvent at a concentration of 0.5 × 10 ⁻⁴ to 2 × 10 ⁻⁴ mol / l. The result is shown in FIG.

[Production of photovoltaic cell and measurement of photoelectric conversion characteristics]
A photovoltaic cell based on sensitization of a titanium dioxide film supported on a conductive substrate was produced by the following procedure. First, colloidal TiO ₂ particles (particle size: 20-30 nm) are applied on conductive glass (fluorine-doped SnO ₂ , 10Ω), baked at 450 ° C. for 30 minutes (film thickness: 10 μm), In order to scatter light, TiO ₂ particles (particle size: 300 to 400 nm) were applied and baked at 520 ° C. for 1 hour (film thickness: 6 to 8 μm). These two layers were immersed in a TiCl ₄ solution for 30 minutes and then heated at 450 ° C. for 30 minutes.

In the case of Examples 1-4, the obtained film | membrane was compared with the said photosensitizer (Examples 1-4) / methanol solution (3.0 * 10 < ^-4 > mol / L) for 3 hours, Comparative Examples 1-2. In the case of No. 1, the dye (photosensitizer) layer was formed by immersing in the photosensitizer (Comparative Examples 1 and 2) / ethanol solution (3.0 × 10 ⁻⁴ mol / L) for 15 hours. The obtained substrate and the Pt surface of the glass with the Pt thin film were combined, and in the case of Examples 1 to 4, an acetonitrile solution containing 2.0 mol / L lithium iodide and 0.025 mol / L iodine, In the case of Comparative Examples 1 and 2, acetonitrile solutions containing 0.3 mol / L lithium iodide and 0.03 mol / L iodine were each soaked by capillary action, and the periphery was sealed with an epoxy adhesive. A lead wire was connected to the conductive layer portion of the transparent conductive substrate and the counter electrode. Thereby, a photovoltaic cell was obtained.

  The obtained photovoltaic cell was irradiated with pseudo-sunlight, and incident photons to current conversion efficiency (IPCE) were measured. Table 1 shows the measurement results of IPCE (%) at wavelengths of 750 nm, 780 nm, 850 nm, 900 nm, and 950 nm. FIG. 6 shows the IPCE spectrum of the photovoltaic cell using the photosensitizer of the example.

DESCRIPTION OF SYMBOLS 1 ... Transparent conductive substrate, 2 ... Counter electrode substrate, 3 ... Semiconductor layer which adsorb | sucked photosensitizer, 4 ... Electrolyte layer, 5 ... Sealing material.

Claims (2)

The photosensitizer which consists of a metal complex containing the structure represented with the following general formula (I).

[In the formula (I), R ¹ represents a hydrogen atom, a halogen atom, an alkyl group, an alkylamino group, a hydroxyl group, an alkoxy group, an acyl group, an ester group, a cyano group, a nitro group, an amino group, an alkoxyalkyl group, an aminoalkyl group. A group, a perfluoroalkyl group, an aryl group or a heterocyclic group, or a carboxyl group, a sulfonic acid group or a phosphoric acid group, or a metal salt, a quaternary ammonium salt or a nitrogen-containing heterocyclic salt thereof; R ² , R ³ , R ⁴ and R ⁵ are each independently a hydrogen atom, halogen atom, alkyl group, alkylamino group, hydroxyl group, alkoxy group, acyl group, ester group, cyano group, nitro group, amino group, alkoxyalkyl group, amino group Alkyl group, perfluoroalkyl group, aryl group or heterocyclic group, carboxyl group, sulfo group Acid group or phosphate group or metal salt thereof, quaternary ammonium salt or nitrogen-containing heterocyclic salt, or carboxyl group, sulfonic acid group or phosphoric acid group or metal salt thereof, quaternary ammonium salt or nitrogen-containing complex R ⁶ represents an aryl group having a ring salt as a substituent, and R ⁶ represents a hydrogen atom, a halogen atom, an alkyl group, an alkylamino group, a hydroxyl group, an alkoxy group, an acyl group, an ester group, a cyano group, a nitro group, an amino group, an alkoxy group. An alkyl group, an aminoalkyl group, a perfluoroalkyl group, an aryl group or a heterocyclic group, or a carboxyl group, a sulfonic acid group or a phosphoric acid group or a metal salt thereof, a quaternary ammonium salt or a nitrogen-containing heterocyclic salt, or Carboxyl group, sulfonic acid group or phosphoric acid group or their metal salts, quaternary ammonia An aryl group having a nium salt or a nitrogen-containing heterocyclic salt as a substituent, an imino group represented by the following general formula (Ia) containing a nitrogen atom coordinated to M, or a nitrogen atom coordinated to M Including a pyridyl group represented by the following general formula (Ib), wherein X is independently a halogen atom, a hydroxy group, a cyano group, a methyl group, a hydrogen atom, a thiocyanate group, a hydrazide group, an azide group, an isocyanide group, A cyanate group, an isothiocyanate group or a nitro group is shown, and L is a bidentate ligand represented by the following general formula (Ic) or (Id) or represented by the following general formula (Ie). Z represents a carbon atom, nitrogen atom, sulfur atom or phosphorus atom, M represents an iron atom, ruthenium atom, osmium atom, cobalt atom, rhodium atom, iridium atom or rhenium Represents an atomic, p represents an integer of 0 to 2, q represents an integer of 1 to 4, r is 0 or 1. ]

[Formula (I-a), (I -b), (I-c), (I-d) and in ^{(I-e), R 11} , R 12, R 13, R 14, R 15, R 16 , R ¹⁷ , R ¹⁸ , R ¹⁹ , R ²⁰ and R ²¹ are each independently a hydrogen atom, halogen atom, alkyl group, alkylamino group, hydroxyl group, alkoxy group, acyl group, ester group, cyano group, nitro group , Amino group, alkoxyalkyl group, aminoalkyl group, perfluoroalkyl group, aryl group or heterocyclic group, or carboxyl group, sulfonic acid group or phosphoric acid group or metal salt thereof, quaternary ammonium salt or nitrogen-containing complex A ring salt is shown. ] A photovoltaic device comprising a metal oxide semiconductor layer containing the photosensitizer according to claim 1.

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