WO2018047494A1 - Photoelectric conversion element, dye-sensitized solar cell and dipyrromethene complex compound - Google Patents

Abstract

Provided are: a photoelectric conversion element and a dye-sensitized solar cell, each of which has excellent photoelectric conversion efficiency; and a dipyrromethene complex compound which is suitable for use in these photoelectric conversion element and dye-sensitized solar cell. This photoelectric conversion element comprises a conductive supporting body, a photosensitive body layer containing an electrolyte, a charge transfer layer containing the electrolyte, and a counter electrode; and the photosensitive body layer contains semiconductor fine particles which support a dipyrromethene complex compound represented by formula (1). In the formula, X represents CR⁵ or N; R⁵ represents a specific group such as an alkyl group; each of R¹-R⁴ represents a specific group such as an alkyl group; each of L¹ and L² represents a single bond or a linking group; each of Z¹ and Z² represents an acidic group or a salt thereof; each of m and n represents an integer of 1 or more; and each of Y¹ and Y² represents a specific group such as a halogen atom.

Description

Photoelectric conversion element, dye-sensitized solar cell, and dipyrromethene complex compound

The present invention relates to a photoelectric conversion element, a dye-sensitized solar cell, and a dipyrromethene complex compound.

Photoelectric conversion elements are used in various photosensors, photocopiers, photoelectrochemical cells such as solar cells, and the like. Various methods such as a method using a metal, a method using a semiconductor, a method using an organic pigment or a dye, or a combination of these methods have been put to practical use for this photoelectric conversion element. In particular, a solar cell using non-depleting solar energy does not require fuel, and full-scale practical use is highly expected as it uses inexhaustible clean energy. Among them, silicon-based solar cells have been researched and developed for a long time, and are spreading due to national policy considerations. However, since silicon is an inorganic material, there is a limit to improving throughput and cost.

Therefore, photoelectrochemical cells using dyes (also called dye-sensitized solar cells) have been studied. For example, a dye-sensitized solar cell using a dye made of a ruthenium complex has been reported by Graetzel et al.
In addition, a dye-sensitized solar cell using a dye other than a dye made of a ruthenium complex has been studied. For example, Patent Document 1 proposes a dye-sensitized solar cell using a boron complex compound having a 2-thienyl-5-carboxythiazole skeleton as a sensitizing dye. Furthermore, Non-Patent Document 1 proposes a dye-sensitized solar cell using, as a sensitizing dye, a dipyrromethene complex compound in which a boron atom is bonded to a dipyrromethene skeleton formed by bonding two pyrrole rings with a methine group. Specifically, in this dipyrromethene complex compound, a triarylamino group was introduced via the ethenylene group at the 3rd and 5th positions of the dipyrromethene skeleton (the ring carbon atom adjacent to the ring nitrogen atom of each pyrrole ring). It is a complex compound.

International Publication No. 2012/121397

Patent Document 1 describes that by using the boron complex compound as a sensitizing dye of a dye-sensitized solar cell, improvement in photoelectric conversion efficiency can be expected. Further, in Non-Patent Document 1, it is possible to improve the short circuit current density and the conversion efficiency (overall conversion efficiency) by using the dipyrromethene complex compound as a sensitizing dye of a dye-sensitized solar cell. Are listed.

However, the performance required for photoelectric conversion elements and dye-sensitized solar cells is increasing year by year, and further improvement in photoelectric conversion efficiency is desired in dye-sensitized solar cells using dyes such as dipyrromethene complex compounds. Yes.

An object of the present invention is to provide a photoelectric conversion element and a dye-sensitized solar cell exhibiting excellent photoelectric conversion efficiency, and a dipyrromethene complex compound suitably used for these.

The inventors of the present invention have provided a photoelectric conversion element using a dipyrromethene complex compound in which an acidic group is introduced at positions 3 and 5 of the dipyrromethene skeleton, and more preferably a substituent is introduced at positions 2 and 6 of the skeleton as a sensitizing dye, and It was found that when used in a dye-sensitized solar cell, a high external quantum yield (IPCE) was exhibited even in a long wavelength region of 800 nm or more, and excellent photoelectric conversion efficiency could be exhibited. The present invention has been further studied and completed based on these findings.

That is, the subject of this invention was achieved by the following means.
<1> A photoelectric conversion element having a conductive support, a photoreceptor layer containing an electrolyte, a charge transfer layer containing an electrolyte, and a counter electrode, wherein the photoreceptor layer is represented by the following formula (1). A photoelectric conversion element having semiconductor fine particles carrying a dipyrromethene complex compound.

In the formula, X represents CR ⁵ or N. R ⁵ represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heteroaryl group.
R ¹ to R ⁴ each independently represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an alkoxy group, an alkylthio group, a heteroaryl group, an amino group, or a halogen atom.
L ¹ and L ² each independently represent a single bond or a linking group.
Z ¹ and Z ² each independently represent an acidic group or a salt thereof, and m and n each independently represents an integer of 1 or more.
Y ¹ and Y ² each independently represent a halogen atom, an alkynyl group, an aryl group, a heteroaryl group, an alkoxy group, an aryloxy group, a heteroaryloxy group, an alkylthio group, an arylthio group or a heteroarylthio group.

<2> Each of L ¹ and L ² is an aliphatic unsaturated hydrocarbon group, an aromatic hydrocarbon ring group or an aromatic heterocyclic group, or an aliphatic unsaturated hydrocarbon group, an aromatic hydrocarbon ring group And the photoelectric conversion element according to <1>, which represents a linking group formed by combining two or more groups selected from the group consisting of an aromatic heterocyclic group.
<3> The photoelectric conversion element according to <1> or <2>, in which L ¹ and L ² are both conjugated linking groups.
<4> Linkage in which L ¹ and L ² are each a combination of two or more groups selected from the group consisting of an aliphatic unsaturated hydrocarbon group, an aromatic hydrocarbon ring group, and an aromatic heterocyclic group The photoelectric conversion element according to any one of <1> to <3>, which is a group.
<5> L ¹ and L ² are both a linking group formed by combining two or more groups selected from the group consisting of an alkenylene group, an alkynylene group, an aromatic hydrocarbon ring group, and an aromatic heterocyclic group. The photoelectric conversion element according to any one of <1> to <4>.

<6> The photoelectric conversion element according to any one of <1> to <5>, wherein L ¹ and L ² are both groups represented by the following formula (L).
Formula (L) * -L ^L1 -Ar ^L -***
In the formula, L ^L1 represents a group represented by any of the following formulas (L-1) to (L-4). Ar ^L represents an aromatic hydrocarbon ring group or an aromatic heterocyclic group. * Represents a bond to the pyrrole ring in formula (1), and *** represents a bond to Z ¹ or Z ^{2 in} formula (1).

In the formula, R ²¹ to R ²⁸ each independently represent a hydrogen atom or a substituent, and A represents an oxygen atom or a sulfur atom. * Represents a bond to the pyrrole ring in formula (1), and ** represents a bond to Ar ^L.

<7> The photoelectric conversion element according to any one of <1> to <6>, wherein L ¹ and L ² are both styryl groups.
<8> The photoelectric conversion element according to any one of <1> to <7>, wherein m and n are all 1.
<9> Each of Z ¹ and Z ² is an acidic group selected from —COOH, —SO ₃ H, —PO (OH) ₂ , —OH and —SH or a salt thereof <1> to <8><10> A dye-sensitized solar cell comprising the photoelectric conversion element according to any one of <1> to <9> above.

<11> A dipyrromethene complex compound represented by the following formula (1).

In the formula, X represents CR ⁵ or N. R ⁵ represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heteroaryl group.
R ¹ to R ⁴ each independently represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an alkoxy group, an alkylthio group, a heteroaryl group, an amino group, or a halogen atom.
L ¹ and L ² each independently represent a single bond or a linking group.
Z ¹ and Z ² each independently represent an acidic group or a salt thereof, and m and n each independently represents an integer of 1 or more.
Y ¹ and Y ² each independently represent a halogen atom, an alkynyl group, an aryl group, a heteroaryl group, an alkoxy group, an aryloxy group, a heteroaryloxy group, an alkylthio group, an arylthio group or a heteroarylthio group.

In the present specification, unless otherwise specified, the double bond may be either E-type or Z-type in the molecule, or a mixture thereof.
When there are a plurality of substituents, linking groups, ligands, etc. (hereinafter referred to as substituents, etc.) indicated by a specific symbol or formula, or when a plurality of substituents etc. are specified simultaneously, there is no special notice. As long as each substituent is the same, it may be the same or different. The same applies to the definition of the number of substituents and the like. Further, when a plurality of substituents and the like are adjacent (particularly adjacent), they may be connected to each other to form a ring unless otherwise specified. In addition, unless otherwise specified, a ring such as an alicyclic ring, an aromatic ring, or a heterocyclic ring may be further condensed to form a condensed ring.

In the present specification, the display of a compound (including a complex and a dye) is used to mean not only the compound itself but also its salt and its ion. Moreover, it is the meaning including what changed a part of structure in the range which does not impair the effect of this invention. Furthermore, it is the meaning which may have arbitrary substituents in the range which does not impair the effect of this invention about the compound which does not specify substitution or unsubstituted. The same applies to substituents, linking groups and ligands.

In addition, in the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

The photoelectric conversion element and the dye-sensitized solar cell of the present invention show excellent photoelectric conversion efficiency by supporting the dipyrromethene complex compound represented by the formula (1). Moreover, the dipyrromethene complex compound of this invention can raise the photoelectric conversion efficiency of a photoelectric conversion element and a dye-sensitized solar cell by using as a sensitizing dye.

FIG. 1 is a cross-sectional view schematically showing an enlarged view of a circular portion in a layer in a system in which the photoelectric conversion element according to the first aspect of the present invention is applied to a battery. FIG. 2 is a cross-sectional view schematically showing a dye-sensitized solar cell including the photoelectric conversion element according to the second aspect of the present invention. FIG. 3 shows action spectra in a dye-sensitized solar cell (sample number 1) using the dipyrromethene complex compound D-1 and a dye-sensitized solar cell (sample number c1) using the dye compound C1 for comparison. FIG.

[Photoelectric conversion element and dye-sensitized solar cell]
The photoelectric conversion element of the present invention has a conductive support, a photoreceptor layer containing an electrolyte, a charge transfer body layer containing an electrolyte, and a counter electrode (counter electrode). The photosensitive layer, the charge transfer layer, and the counter electrode are provided on the conductive support in this order.

In the photoelectric conversion element of the present invention, the semiconductor fine particles forming the photoreceptor layer are also referred to as a dipyrromethene complex compound represented by the following formula (1) as a sensitizing dye (also referred to as a dipyrromethene complex dye when used as a sensitizing dye). ). Here, the aspect in which the dipyrromethene complex dye is supported on the surface of the semiconductor fine particle includes an aspect in which the dipyrromethene complex dye is adsorbed on the surface of the semiconductor fine particle, an aspect in which the dipyrromethene complex dye is deposited on the surface of the semiconductor fine particle To do. The adsorption includes chemical adsorption and physical adsorption, and chemical adsorption is preferable.
The dipyrromethene complex compound is preferably adsorbed on the semiconductor fine particles via an acidic group (also referred to as an adsorbing group) described later. At this time, the acidic group becomes an anion or a salt thereof dissociated by releasing a proton. It may be. The counter ion when the acidic group becomes a salt has the same meaning as described later.
When the dipyrromethene complex compound is adsorbed on the semiconductor fine particles via an acidic group, the acidic group may be one or two or more.

The photoelectric conversion element of the present invention is not particularly limited in structure other than the structure defined in the present invention, and a known structure relating to the photoelectric conversion element can be adopted. Each of the layers constituting the photoelectric conversion element of the present invention is designed according to the purpose, and may be formed in a single layer or multiple layers, for example. Moreover, you may have layers other than said each layer if needed.

The dye-sensitized solar cell of the present invention uses the photoelectric conversion element of the present invention.
Hereinafter, preferred embodiments of the photoelectric conversion element and the dye-sensitized solar cell of the present invention will be described.

A system 100 shown in FIG. 1 is an application of the photoelectric conversion element 10 according to the first aspect of the present invention to a battery application in which an operation means M (for example, an electric motor) is caused to work by an external circuit 6.
The photoelectric conversion element 10 includes a conductive support 1, semiconductor fine particles 22 sensitized by carrying a dye (dipyrromethene complex dye) 21, a photoreceptor layer 2 containing an electrolyte between the semiconductor fine particles 22, It consists of a charge transfer layer 3 as a hole transport layer and a counter electrode 4.
In the photoelectric conversion element 10, the dipyrromethene complex dye represented by the formula (1) is adsorbed to the semiconductor fine particles 22 in the photoreceptor layer 2, which is also referred to as an oxide semiconductor electrode. The light receiving electrode 5 has a conductive support 1 and a photoreceptor layer 2 and functions as a working electrode.

In the system 100 to which the photoelectric conversion element 10 is applied, the light incident on the photoreceptor layer 2 excites the dipyrromethene complex dye 21. The excited dipyrromethene complex dye 21 has electrons with high energy, and these electrons are transferred from the dipyrromethene complex dye 21 to the conduction band of the semiconductor fine particles 22 and further reach the conductive support 1 by diffusion. At this time, the dipyrromethene complex dye 21 is an oxidant (cation). Electrons that reach the conductive support 1 reach the oxidized form of the dipyrromethene complex dye 21 via the counter electrode 4 and the charge transfer layer 3 while working in the external circuit 6, and the oxidized form is reduced. By repeating the cycle of excitation and electron transfer of the dipyrromethene complex dye, the system 100 functions as a solar cell.

The dye-sensitized solar cell 20 shown in FIG. 2 is configured by the photoelectric conversion element of the second aspect of the present invention.
Although the photoelectric conversion element used as the dye-sensitized solar cell 20 differs with respect to the photoelectric conversion element shown in FIG. Except for this point, the photoelectric conversion element 10 is configured in the same manner as the photoelectric conversion element 10 shown in FIG. That is, the conductive support 41 has a two-layer structure including a substrate 44 and a transparent conductive film 43 formed on the surface of the substrate 44. The photoreceptor layer 42 has a two-layer structure including a semiconductor layer 45 and a light scattering layer 46 formed adjacent to the semiconductor layer 45. In this photoreceptor layer 42, at least the dipyrromethene complex dye represented by the formula (1) is adsorbed on the semiconductor fine particles forming the photoreceptor layer 42, and is also referred to as an oxide semiconductor electrode. A spacer S is provided between the conductive support 41 and the counter electrode 48. In the dye-sensitized solar cell 20, reference numeral 40 denotes a light receiving electrode, and 47 denotes a charge transfer body layer.

The dye-sensitized solar cell 20 functions as a solar cell when light enters the photoreceptor layer 42 as in the system 100 to which the photoelectric conversion element 10 is applied.

As will be described later, the photoelectric conversion element and the dye-sensitized solar cell of the present invention have a high external quantum yield even in a long wavelength region of 800 nm or more, and exhibit excellent photoelectric conversion efficiency. This excellent photoelectric conversion efficiency is exhibited even under sunlight irradiation (also referred to as a high illuminance environment) in fine weather, and also in a low illuminance environment in which the illuminance is low compared to sunlight in fine weather.
The low illuminance environment is not particularly limited, and refers to an environment having an illuminance of 10,000 lux or less, for example. Examples of such a low illuminance environment include a low illuminance sunlight environment such as in cloudy weather or rainy weather, or a low illuminance environment under illumination such as an indoor environment or a fluorescent lamp.

The photoelectric conversion element and the dye-sensitized solar cell of the present invention are not limited to the above-described preferred embodiments, and the configuration of each embodiment can be appropriately combined between the embodiments without departing from the gist of the present invention.

In the present invention, materials and members used for the photoelectric conversion element or the dye-sensitized solar cell can be prepared by a usual method. For example, US Pat. No. 4,927,721, US Pat. No. 4,684,537, US Pat. No. 5,084,365, US Pat. No. 5,350,644, U.S. Pat. No. 5,463,057, U.S. Pat. No. 5,525,440, JP-A-7-249790, JP-A 2001-185244, JP-A 2001-210390, JP Reference can be made to JP2003-217688A, JP2004220974A, and JP2008-135197A.

<Dipyrromethene Complex Compound Represented by Formula (1)>
Next, the dipyrromethene complex compound used in the present invention will be described.
The dipyrromethene complex compound is represented by the following formula (1). The dipyrromethene complex compound having such a structure imparts high photoelectric conversion efficiency to the photoelectric conversion element and the dye-sensitized solar cell.

Although the details of the reason why the dipyrromethene complex compound represented by the formula (1) can impart the above-described excellent performance to the photoelectric conversion element and the dye-sensitized solar cell are not clear yet, it is considered as follows.
The dipyrromethene complex compound represented by the formula (1) has acidic groups (Z ¹ and Z ² in the formula (1)) at the 3rd and 5th positions of the dipyrromethene skeleton, and more preferably the 2nd and 6th positions. Have substituents (R ¹ and R ⁴ in formula (1)). Accordingly, the adsorption stability is improved because the semiconductor fine particles are strongly adsorbed and are not easily desorbed from the semiconductor fine particles. As a result, the ability to absorb light in a long wavelength region of 800 nm or more is increased. Furthermore, it has substituents at the 2-position and the 6-position, and in addition to this, when an acidic group is introduced into the dipyrromethene skeleton via a linking group, light in the long wavelength region can be absorbed more effectively. . Therefore, the dipyrromethene complex compound is excited by light in a wide wavelength region from a short wavelength to a long wavelength, and the generated electrons are injected into the semiconductor fine particles. As a result, it is considered that the photoelectric conversion efficiency is improved.

In the present invention, the dipyrromethene complex dye represented by the formula (1) is an isomer such as an optical isomer, a geometric isomer, a bond isomer, an ionized isomer, and any of these isomers. It may also be a mixture of these isomers.

The compound represented by the formula (1) may change to an oxidized state by an oxidation-reduction reaction with a surrounding material in a state where the compound is incorporated in the photoelectric conversion element.

In the formula (1), X represents CR ⁵ or N, and CR ⁵ is preferable.
R ⁵ represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heteroaryl group. For these groups that can be adopted as R ⁵ , preferred ranges and the like in the corresponding groups of the substituent group T described later are applied. However, as described later, the alkyl group and alkenyl group which can be adopted as R ⁵ include a cycloalkyl group and a cycloalkenyl group, respectively.
Examples of the aryl group that can be adopted as R ⁵ include phenyl and naphthyl, and phenyl is preferable.
Examples of the heteroaryl group that can be adopted as R ⁵ include a thiophene ring, a furan ring, a thiazole ring, a pyrrole ring, an oxazole ring, an imidazole ring, a pyrazole ring, and a 5-membered ring group such as a triazole ring, a pyridine ring, and a pyrazine ring. , Pyrimidine ring, pyridazine ring, triazine ring or tetrazine ring 6-membered ring.
R ⁵ is preferably an aryl group or a heteroaryl group, more preferably an aryl group, and still more preferably phenyl.

Each of the above groups that can be adopted as R ⁵ may further have a substituent. Further, the substituent that may be included is not particularly limited, and a substituent selected from the substituent group T described later is preferable. More preferably, an alkyl group, an alkoxy group, an aryl group, an amino group, and a halogen atom are mentioned, an alkyl group or a halogen atom is more preferable, and a fluorine-containing alkyl group (fluorinated alkyl group) or a fluorine atom is particularly preferable. When R ⁵ further has a substituent, the number of further substituents is not particularly limited as long as it is 1 or more. For example, 1 to 16 is preferable, 1 to 12 is more preferable, and 2 to 8 is preferable. Is more preferable.
Further, as a group having a substituent, for example, (tetra or penta) fluorophenyl, (mono-, di- or tri-) (trifluoromethyl) phenyl, amino or alkoxyphenyl, (mono-, di- or tri-) Examples thereof include alkylphenyl, (alkyl) phenylethenyl, phenylethynyl and the like.
Each of the above groups that can be employed as R ⁵ preferably does not have an acidic group described later.

In the formula (1), R ¹ to R ⁴ each represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an alkoxy group, an alkylthio group, a heteroaryl group, an amino group, or a halogen atom.
For each of the above groups or halogen atoms that can be adopted as R ¹ to R ⁴ , preferred ranges of the corresponding groups or halogen atoms in the substituent group T described later are applied. However, as described later, an alkyl group, an alkenyl group, an alkoxy group, and an alkylthio group that can be adopted as R ¹ to R ⁴ are, respectively, a cycloalkyl group, a cycloalkenyl group, a cycloalkyloxy group in the substituent group T, and A cycloalkylthio group is included.
R ¹ and R ⁴ are each preferably an alkyl group, an alkenyl group, an alkynyl group, an aryl group, or a heteroaryl group, and more preferably an alkyl group, an alkynyl group, an aryl group, or a heteroaryl group.
R ² and R ³ are each preferably an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heteroaryl group, more preferably an alkyl group, an alkynyl group, an aryl group or a heteroaryl group, and even more preferably an alkyl group.
In R ¹ to R ⁴ , R ¹ and R ⁴ are preferably the same, and R ² and R ³ are preferably the same. At this time, R ¹ and R ² may be different from R ³ and R ⁴ .

Each of the above groups that can be adopted as R ¹ to R ⁴ may further have a substituent. Further, the substituent that may be included is not particularly limited, and a substituent selected from the substituent group T described later is preferable. An alkyl group, an alkenyl group, an alkynyl group, an aryl group, a halogen atom, an alkoxy group or an amino group is more preferable, and an alkyl group, an aryl group, an alkoxy group or a halogen atom is still more preferable. When R ¹ to R ⁴ further have a substituent, the number of further substituents is not particularly limited as long as it is 1 or more. For example, 1 to 16 is preferable, and 2 to 12 is more preferable.
Further, as a group having a substituent, for example, (tetra or penta) fluorophenyl, (mono-, di- or tri-) (trifluoromethyl) phenyl, (mono-, di- or tri-) alkylphenyl, (mono -, Di- or tri-) alkylphenylethenyl, (mono-, di- or tri-) alkylphenylethynyl, or alkylthienyl.

Each of the above groups that can be taken as R ¹ to R ⁴ preferably does not have an acidic group described later.

In Formula (1), L ¹ and L ² each represent a single bond or a linking group, and a linking group is preferred.
The linking group that can be taken as L ¹ and L ² is preferably a linking group (conjugated linking group) conjugated with the dipyrromethene skeleton (pyrrole ring) in the formula (1) in terms of IPCE and photoelectric conversion efficiency. Examples of the linking group that can be adopted as L ¹ and L ² include an aliphatic unsaturated hydrocarbon group, an aromatic hydrocarbon ring group, an aromatic heterocyclic group, an aliphatic unsaturated hydrocarbon group, and an aromatic hydrocarbon ring group. And a linking group formed by combining two or more groups selected from the group consisting of aromatic heterocyclic groups, and a linking group formed by combining the two or more groups is more preferable.

Examples of the aliphatic unsaturated hydrocarbon group include a group having at least one carbon-carbon unsaturated bond inside or at the end, and an ethylene hydrocarbon group or an acetylene hydrocarbon group is preferable. In the aliphatic unsaturated hydrocarbon group, a carbon-carbon unsaturated bond having a terminal is preferable.

Examples of the ethylene-based hydrocarbon group include a hydrocarbon group having at least one carbon-carbon double bond in the group, and a group containing a group represented by —CR ^L ═CR ^L —. ^L = CR ^L - group represented by are preferred. The number of carbon atoms of the ethylene-based hydrocarbon group is preferably 2 to 20, more preferably 2 to 12, and still more preferably 2. R ^L represents a hydrogen atom or a substituent, and is preferably a hydrogen atom. This ethylene-based hydrocarbon group may have a substituent. The substituent that the ethylene hydrocarbon group may have and the substituent that can be taken as ^RL are not particularly limited, and examples thereof include a substituent selected from the substituent group T described later. This substituent may further have a substituent. When this ethylene-based hydrocarbon group is a trivalent or higher group, it is a group obtained by removing a predetermined number ((valence-2)) of hydrogen atoms (including ^RL that takes a hydrogen atom) in the group. For example, when m or n described later is an integer of 2 or more, the ethylene-based hydrocarbon group is a group obtained by removing (m−1) or (n−1) or more hydrogen atoms in the group.
The ethylene-based hydrocarbon group is preferably a divalent group (when m or n is 1) (alkenylene group), and more preferably a group represented by -CR ^L = CR ^L -group (ethenylene group).

Examples of the acetylene hydrocarbon group include a hydrocarbon group having at least one carbon-carbon triple bond in the group, and a group containing a group represented by —C≡C—, and —C≡C— The group represented by these is preferable. The carbon number of the acetylene hydrocarbon group is preferably 2 to 20, more preferably 2 to 12, and still more preferably 2. The acetylene hydrocarbon group may have a substituent. The substituent that the acetylene hydrocarbon group may have has the same meaning as the substituent that the ethylene hydrocarbon group may have. When the acetylene hydrocarbon group is a trivalent or higher group, it is a group obtained by removing a predetermined number ((valence-2)) of hydrogen atoms in the group. For example, when m or n described later is an integer of 2 or more, the acetylene hydrocarbon group is a group obtained by removing (m−1) or (n−1) or more hydrogen atoms in the group.
The acetylene hydrocarbon group is preferably a divalent group (for example, when m or n is 1) (alkynylene group), and is referred to as a group represented by —C≡C— (ethynylene group).

Examples of the aromatic hydrocarbon ring group include groups obtained by further removing m or n hydrogen atoms from an aryl group of the following substituent group T. As a preferable range and the like in the aromatic hydrocarbon ring group, a preferable range and the like in the aryl group of the following substituent group T is applied.
Examples of the aromatic heterocyclic group include groups obtained by further removing m or n hydrogen atoms from the aromatic heterocyclic group among the heterocyclic groups described in the substituent group T below. As the preferred range and the like for the aromatic heterocyclic group, the preferred range and the like for the aromatic heterocyclic group of the following substituent group T are applied.
The aromatic hydrocarbon ring group and the aromatic heterocyclic group are preferably divalent groups (arylene group and heteroarylene group). For example, the groups exemplified for the arylene group and heteroarylene group which can be adopted as R ⁵ are preferable. It is done.

In the linking group formed by combining two or more groups selected from the group consisting of an aliphatic unsaturated hydrocarbon group, an aromatic hydrocarbon ring group and an aromatic heterocyclic group, the group to be combined is selected from the above group Two or more groups may be the same group or different groups. The number of groups to be combined is not particularly limited, preferably 2 to 6, more preferably 2 to 4, and still more preferably 2 or 3.

When the linking group that can be taken as L ¹ and L ² is a linking group formed by combining two or more groups described above, a group consisting of an alkenylene group, an alkynylene group, an aromatic hydrocarbon ring group, and an aromatic heterocyclic group A linking group formed by combining two or more selected groups is preferred, and a group represented by the following formula (L) is more preferred.
Formula (L) * -L ^L1 -Ar ^L -***
In the formula (L), L ^L1 represents a group represented by any of the following formulas (L-1) to (L-4). Ar ^L represents an aromatic hydrocarbon ring group or an aromatic heterocyclic group, preferably an arylene group or a heteroarylene group. * Represents a bond to the pyrrole ring in the above formula (1), and *** represents a bond to Z ¹ or Z ² in the above formula (1).

In formulas (L-1) to (L-4), * represents a bond to the pyrrole ring in formula (1), and ** represents a bond to Ar ^L.

R ²¹ to R ²⁸ each independently represent a hydrogen atom or a substituent, and any of them is preferably a hydrogen atom.
The substituent that can be adopted as R ²¹ to R ²⁸ is not particularly limited, and examples thereof include a substituent selected from the substituent group T described later. Of these, an alkyl group or an alkoxy group is preferable. This substituent may further have a substituent.
In the formula (L-4), A represents an oxygen atom or a sulfur atom.
In particular, L ^L1 is preferably a linking group represented by any one of formula (L-1), formula (L-2) and formula (L-3), and is represented by formula (L-1) or formula (L- The linking group represented by 2) is more preferable, and the linking group represented by formula (L-1) is more preferable.

Ar ^L is an aromatic hydrocarbon ring group or an aromatic heterocyclic group, and preferably an aromatic hydrocarbon ring group.
The aromatic hydrocarbon ring group that can be taken as Ar ^L is synonymous with the above-described aromatic hydrocarbon ring group that can be taken as L ¹ and L ² , and includes monocyclic and condensed polycyclic groups. The aromatic hydrocarbon ring group preferably has 6 to 30 carbon atoms, more preferably 6 to 10 carbon atoms, and particularly preferably 6 carbon atoms. Specific examples include a benzene ring group or a naphthyl ring group. When the aromatic hydrocarbon ring group is a divalent group (arylene group), phenylene or naphthylene is preferable.

The aromatic heterocyclic group that can be taken as Ar ^L is synonymous with the aromatic heterocyclic group that can be taken as L ¹ and L ² described above, and includes monocyclic and condensed polycyclic groups. As the preferred range and the like for the aromatic heterocyclic group, the preferred range and the like for the aromatic heterocyclic group of the following substituent group T are applied. As the aromatic heterocyclic group, for example, the groups mentioned for the heteroarylene group which can be adopted as R ⁵ are mentioned, and among them, a thiophene ring group or a furan ring group is preferred. In the case where the aromatic heterocyclic group is a divalent group (heteroarylene group), a group obtained by further removing one hydrogen atom from the aromatic heterocyclic group among the heterocyclic groups described in Substituent Group T below Is mentioned.

The aromatic hydrocarbon ring group or aromatic heterocyclic group that can be adopted as Ar ^L may further have a substituent selected from the substituent group T described later, but does not have a substituent. Is preferred. When the aromatic hydrocarbon ring group or aromatic heterocyclic group has a substituent, the number is not particularly limited as long as it is 1 or more, and for example, 1 to 5 is preferable.

As the group represented by the above formula (L), L ^L1 is a group represented by the above formula (L-1), and Ar ^L is an aromatic hydrocarbon ring group (an ethenylene group and an aromatic carbon group). A linking group formed by combining a hydrogen ring group) is preferred.

The linking group that can be taken as L ¹ and L ² is a combination of two or more groups selected from the group consisting of an aliphatic unsaturated hydrocarbon group, an aromatic hydrocarbon ring group, and an aromatic heterocyclic group. And a linking group formed by combining two or more groups selected from the group consisting of an alkenylene group, an alkynylene group, an aromatic hydrocarbon ring group, and an aromatic heterocyclic group is more preferable. Or a linking group formed by combining two or more groups selected from the group consisting of an alkenylene group, an alkynylene group, and an aromatic hydrocarbon ring group, and an ethenylene group (formula (L- A linking group formed by combining the group represented by 1) and an aromatic hydrocarbon ring group is particularly preferable, and a linking group formed by combining an ethenylene group and a phenylene group (styryl group) is most preferable. There.

L ¹ and L ² may be the same or different, and are preferably the same.
When L ¹ and L ² are a linking group formed by combining two or more of the above-mentioned groups, a group other than the terminal group, for example, a group bonded to the pyrrole ring of formula (1) is an acidic group described later. It is preferable not to have.

In the formula (1), Z ¹ and Z ² represent an acidic group or a salt thereof.
In the present invention, an acidic group is a substituent having a dissociative proton, and a pKa of 11 or less. The pKa of the acidic group is determined by J.M. Phys. Chem. A2011, 115, p. It can be determined according to the “SMD / M05-2X / 6-31G ^* ” method described in 6641-6645. Examples of the acidic group include a carboxy group (—COOH), a phosphonyl group (—PO (OH) ₂ ), a phosphoryl group (—O—PO (OH) ₂ ), a sulfo group (—SO ₃ H), and a boric acid group. , (Phenolic) hydroxyl group, thiophenol group or sulfonamide group.
The acidic group is preferably —COOH, —SO ₃ H, —PO (OH) ₂ , —OH or —SH, more preferably a carboxy group.

When incorporated in the dipyrromethene complex compound represented by the formula (1), the acidic group may be an anion dissociated by releasing a proton, or may be a salt. The acid group salt may be a metal salt or a non-metal salt. The counter ion when the acidic group becomes a salt is not particularly limited, and examples thereof include the following counter ions.
The counter ion is not particularly limited. For example, inorganic or organic ammonium ions (for example, tetraalkylammonium ions, amidinium ions, guanidinium ions, pyridinium ions, etc.), phosphonium ions (for example, tetraalkylphosphonium ions, alkyls) Triphenylphosphonium ions, etc.), alkali metal ions (Li ions, Na ions, K ions, etc.), alkaline earth metal ions, or metal complex ions. Of these, inorganic or organic ammonium ions or alkali metal ions are preferable, and tetraalkylammonium ions (tetraethylammonium ion, tetrabutylammonium ion, tetrahexylammonium ion, tetraoctylammonium ion, tetradecylammonium ion, etc.) as the organic ammonium ion. ) Is more preferable.

Z ¹ and Z ² may be the same or different and are preferably the same.

In the formula (1), m and n are each an integer of 1 or more. The upper limit is the same as (number of hydrogen atoms each of L ¹ and L ² + 1). m and n are each preferably 1 or 2, more preferably 1, and still more preferably 1.

In Formula (1), Y ¹ and Y ² are each independently a halogen atom, alkynyl group, aryl group, heteroaryl group, alkoxy group, aryloxy group, heteroaryloxy group, alkylthio group, arylthio group or heteroary A ruthio group is shown.
Of the above groups that can be taken as Y ¹ and Y ² , a halogen atom, an alkynyl group, an aryl group, an alkoxy group, an aryloxy group, an alkylthio group, and an arylthio group are preferable in the corresponding groups of the following substituent group T, respectively. Ranges etc. apply. However, as described later, the alkoxy group and the alkylthio group that can be taken as Y ¹ and Y ² include a cycloalkyloxy group and a cycloalkylthio group, respectively.
As the heteroaryl group that can be adopted as Y ¹ and Y ² , preferred ranges and the like of the aromatic heterocyclic group among the heterocyclic groups described in the substituent group T below are applied.
Heteroaryl groups in the heteroaryl group and heteroarylthio group may take as Y ¹ and Y ² are each as defined above heteroaryl groups can take as Y ¹ and Y ^2, are preferred are also the same.
The above-mentioned substituents that can be taken as Y ¹ and Y ² may further have a substituent. Further, the substituent that may be included is not particularly limited, and a substituent selected from the substituent group T described later is preferable.

Each of Y ¹ and Y ² preferably has no acidic group, preferably a halogen atom, an alkynyl group or an alkoxy group, more preferably a halogen atom, and still more preferably a fluorine atom.
Y ¹ and Y ² may be the same or different, and are preferably the same.

Y ¹ and Y ² may be linked to each other or linked to L ¹ and L ² to form a ring, as described later.
In the embodiment in which Y ¹ and Y ² are connected to each other to form a ring, in addition to the first embodiment in which groups each formed by removing a hydrogen atom from groups taken as Y ¹ and Y ² are bonded to each other, Y ^A second embodiment in which a part of the group taken as ¹ or Y ² is bonded and bonded is included. In this second embodiment, ^one of Y ¹ and Y ² can be regarded as the above-mentioned group, and the other can be regarded as a part of the above-mentioned group (such as —O— or —S—). Examples of the first embodiment, for example, when Y ¹ and Y ² are both alkoxy groups include 2 or more alkylenedioxy group carbon atoms. In the second embodiment, for example, when Y ¹ and Y ² are both phenyloxy groups, Y ¹ and Y ² are phenyl groups that share a phenylene structure (—C ₆ H ₄ —) of the phenyloxy group. A range oxy group is mentioned. In this case, Y ¹ is a phenyloxy group, and Y ² can be regarded as —O—.
Similarly, in the embodiment in which Y ¹ and L ¹ are linked to form a ring, in addition to the first embodiment in which groups each formed by removing a hydrogen atom from the groups taken as Y ¹ and L ¹ are bonded to each other , Y ¹ or L ¹ includes a second aspect in which a part of the group is shared and bonded. This point is the same for embodiments and Y ² and L ² are connected to form a ring.

In the formula (1), X, R ¹ to R ⁴ , L ¹ , L ² , Y ¹ and Y ² , and the substituents that these may further have, are each other substituents or linkages. It may combine with a group or the like to form a ring. For example, R ¹ and R ² , R ³ and R ⁴ , R ¹ and L ¹ , R ⁴ and L ² , L ¹ and Y ¹ , and L ² and Y may each form a ring. The ring structure thus formed is not particularly limited. However, when L ¹ and L ² are bonded to each other, the porphyrin ring is not formed including the dipyrromethene skeleton represented by the formula (1).

The dipyrromethene complex compound represented by the above formula (1) can be synthesized by, for example, Patent Document 1, Non-Patent Document 1, known methods, synthesis examples in Examples, or methods according to these.

In the dipyrromethene complex compound represented by the formula (1), the maximum absorption wavelength in the solution is preferably in the range of 300 to 1000 nm, more preferably in the range of 350 to 950 nm, and particularly preferably in the range of 370 to 900 nm. is there.

<Substituent group T>
In the present invention, preferred substituents include substituents selected from the following substituent group T. The above-mentioned acidic group is not included in the substituent group T.
Further, in the present specification, when only described as a substituent, this substituent group T is referred to. When each group, for example, an alkyl group, is only described, Preferred ranges for the corresponding groups of this substituent group T apply.
Furthermore, in the present specification, when an alkyl group is described separately from a cyclic (cyclo) alkyl group, the alkyl group is used in a sense including a linear alkyl group and a branched alkyl group. On the other hand, when the alkyl group is not described separately from the cyclic alkyl group (when simply described as an alkyl group), and unless otherwise specified, the alkyl group is a linear alkyl group or a branched alkyl group. And cycloalkyl group. The same applies to a compound containing a group (an alkoxy group, an alkylthio group, an alkenyloxy group, etc.) containing a group that can take a cyclic structure (an alkyl group, an alkenyl group, an alkynyl group, etc.) or a group containing a group that can take a cyclic structure. is there. When the group can form a cyclic skeleton, the lower limit of the number of atoms of the group forming the cyclic skeleton is 3 or more regardless of the lower limit of the number of atoms specifically described below for the group that can take this structure, 5 or more is preferable.
In the following description of the substituent group T, for example, in order to clarify a linear or branched group and a cyclic group, such as an alkyl group and a cycloalkyl group, they are described separately. There is also.

Examples of the group included in the substituent group T include the following groups.
An alkyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms), an alkenyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms), an alkynyl group (preferably having 2 to 20 carbon atoms, more Preferably 2 to 12), a cycloalkyl group (preferably 3 to 20 carbon atoms), a cycloalkenyl group (preferably 5 to 20 carbon atoms), an aryl group (preferably 6 to 26 carbon atoms, more preferably 6 to 10 carbon atoms). ), A heterocyclic group (having at least one oxygen atom, sulfur atom or nitrogen atom as a ring-constituting atom, preferably having 2 to 20 carbon atoms, more preferably a 5- or 6-membered heterocyclic group. The heterocyclic group includes an aromatic heterocyclic group (heteroaryl group) and an aliphatic heterocyclic group.), An alkoxy group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms), an A kenyloxy group (preferably 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms), an alkynyloxy group (preferably 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms), a cycloalkyloxy group (preferably 3 to 3 carbon atoms). 20), an aryloxy group (preferably having 6 to 26 carbon atoms), a heterocyclic oxy group (preferably having 2 to 20 carbon atoms),

An alkoxycarbonyl group (preferably having a carbon number of 2 to 20), a cycloalkoxycarbonyl group (preferably having a carbon number of 4 to 20), an aryloxycarbonyl group (preferably having a carbon number of 6 to 20), an amino group (preferably having a carbon number of 0 to 20, (mono- or di-) alkylamino group, (mono- or di-) alkenylamino group, (mono- or di-) alkynylamino group, (mono- or di-) cycloalkylamino group, (mono -Or di-) cycloalkenylamino group, (mono- or di-) arylamino group, (mono- or di-) heterocyclic amino group), sulfamoyl group (preferably having 0 to 20 carbon atoms and alkyl , A cycloalkyl or aryl sulfamoyl group is preferred), an acyl group (preferably having a carbon number of 1 to 20), an acyloxy group (preferably 1 to 20 carbon atoms), a carbamoyl group (preferably 1 to 20 carbon atoms, alkyl, a carbamoyl group of the cycloalkyl or aryl preferable.),

An acylamino group (preferably having a carbon number of 1 to 20), a sulfonamide group (preferably having a carbon number of 0 to 20, a sulfonamido group of alkyl, cycloalkyl or aryl is preferred), an alkylthio group (preferably having a carbon number of 1 to 20). More preferably 1 to 12), a cycloalkylthio group (preferably 3 to 20 carbon atoms), an arylthio group (preferably 6 to 26 carbon atoms), an alkyl, cycloalkyl or arylsulfonyl group (preferably 1 to 20 carbon atoms). ),

A silyl group (preferably a silyl group having 1 to 20 carbon atoms and substituted by alkyl, aryl, alkoxy and aryloxy), a silyloxy group (preferably having 1 to 20 carbon atoms, alkyl, aryl, alkoxy and aryloxy) And a hydroxy group, a cyano group, a nitro group, or a halogen atom (for example, a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom).

The substituent selected from the substituent group T is more preferably an alkyl group, alkenyl group, cycloalkyl group, aryl group, heterocyclic group, alkoxy group, cycloalkoxy group, aryloxy group, alkoxycarbonyl group, cycloalkoxycarbonyl. Group, amino group, acylamino group, cyano group or halogen atom, particularly preferably an alkyl group, alkenyl group, aryl group, heterocyclic group, alkoxy group, alkoxycarbonyl group, amino group, acylamino group or cyano group. .

The substituent selected from the substituent group T includes a group formed by combining a plurality of the above groups unless otherwise specified. For example, when a compound or a substituent includes an alkyl group, an alkenyl group, etc., these may be substituted or unsubstituted. In addition, when an aryl group, a heterocyclic group, and the like are included, they may be monocyclic or condensed, and may be substituted or unsubstituted.

Specific examples of the dipyrromethene complex compound represented by the formula (1) are shown below, but the present invention is not limited to these dipyrromethene complex compounds. In the following specific examples, Me represents methyl and Ph represents phenyl.

Next, preferred embodiments of the main members of the photoelectric conversion element and the dye-sensitized solar cell will be described.

<Conductive support>
The conductive support is not particularly limited as long as it has conductivity and can support the photoreceptor layer 2 and the like. The conductive support is made of a conductive material, for example, a conductive support 1 made of a metal described later, or a glass or plastic substrate 44 and a transparent conductive film 43 formed on the surface of the substrate 44. The electroconductive support body 41 which has is preferable.

Among these, the conductive support 41 having the metal oxide transparent conductive film 43 on the surface of the substrate 44 is more preferable. Such a conductive support 41 is obtained by applying a conductive metal oxide to the surface of the substrate 44 to form a transparent conductive film 43. Examples of the substrate 44 made of plastic include a transparent polymer film described in paragraph No. 0153 of JP-A-2001-291534. In addition to glass and plastic, ceramic (Japanese Patent Laid-Open No. 2005-135902) or conductive resin (Japanese Patent Laid-Open No. 2001-160425) can be used as a material for forming the substrate 44. As the metal oxide, tin oxide (TO) is preferable, and fluorine-doped tin oxide such as indium-tin oxide (tin-doped indium oxide; ITO) and fluorine-doped tin oxide (FTO) is particularly preferable. The coating amount of the metal oxide at this time is preferably 0.1 to 100 g per 1 m ² of the surface area of the substrate 44. When the conductive support 41 is used, light is preferably incident from the substrate 44 side.

The conductive supports 1 and 41 are preferably substantially transparent. “Substantially transparent” means that the transmittance of light (wavelength 300 to 1200 nm) is 10% or more, preferably 50% or more, and particularly preferably 80% or more. .
The thickness of the conductive supports 1 and 41 is not particularly limited and is preferably 0.05 μm to 10 mm, more preferably 0.1 μm to 5 mm, and particularly preferably 0.3 μm to 4 mm. .
When the transparent conductive film 43 is provided, the thickness of the transparent conductive film 43 is preferably 0.01 to 30 μm, more preferably 0.03 to 25 μm, and particularly preferably 0.05 to 20 μm. .

The conductive supports 1 and 41 preferably have a metal oxide film made of a metal oxide on the surface thereof. As the metal oxide, the metal oxides that form the transparent conductive film 43 and the metal oxides exemplified in the semiconductor fine particles described later can be used, and the metal oxides exemplified in the semiconductor fine particles are preferable. The metal oxide may be the same type of metal oxide as that of the metal oxide or the semiconductive fine particles forming the transparent conductive film 43, or may be a different type of metal oxide. Good. This metal oxide film is usually formed as a thin film, and preferably has a thickness of 0.01 to 100 nm, for example. The formation method of a metal oxide film is not specifically limited, The method similar to the formation method of the layer which the semiconductor fine particle mentioned later forms is mentioned. For example, a metal oxide film can be formed by applying and heating (baking) a liquid containing a metal oxide or a precursor thereof (for example, a halide or an alkoxide).

The conductive supports 1 and 41 may have a light management function on the surface. For example, an antireflection film in which high refractive films and low refractive index oxide films described in JP-A-2003-123859 are alternately laminated may be provided on the surface, as described in JP-A-2002-260746. The light guide function may be provided.

<Photoreceptor layer>
Other configurations are not particularly limited as long as the photoreceptor layer includes the semiconductor fine particles 22 on which the dye 21 is supported and an electrolyte. Preferably, the photoreceptor layer 2 and the photoreceptor layer 42 are used.

-Semiconductor fine particles (layers formed by semiconductor fine particles)-
The semiconductor fine particles 22 are preferably fine particles of a metal chalcogenide (eg, oxide, sulfide, selenide, etc.) or a compound having a perovskite crystal structure. Preferred examples of the metal chalcogenide include titanium, tin, zinc, tungsten, zirconium, hafnium, strontium, indium, cerium, yttrium, lanthanum, vanadium, niobium or tantalum oxide, cadmium sulfide, and cadmium selenide. Preferred examples of the compound having a perovskite crystal structure include strontium titanate and calcium titanate. Of these, titanium oxide (titania), zinc oxide, tin oxide, and tungsten oxide are particularly preferable.

Examples of the crystal structure of titania include anatase type, brookite type, and rutile type, and anatase type and brookite type are preferable. Titania nanotubes, nanowires, and nanorods can be used alone or mixed with titania fine particles.

The particle diameters of the semiconductor fine particles 22 are 0.001 to 1 μm as primary particles and 0.01 to 100 μm as the average particle diameter of the dispersion in terms of the average particle diameter when the projected area is converted into a circle. Is preferred.

The semiconductor fine particles 22 preferably have a large surface area so that a large amount of the dye 21 can be adsorbed. For example, in a state where the semiconductor fine particles 22 are coated on the conductive support 1 or 41, the surface area thereof is preferably 10 times or more, more preferably 100 times or more the projected area. This upper limit is not particularly limited, and is usually about 5000 times. In general, the greater the thickness of the layer (photoreceptor layer) formed by semiconductor fine particles, the higher the amount of dye 21 that can be carried per unit area and the higher the light absorption efficiency, but the longer the diffusion distance of the generated electrons, the higher the charge. Loss due to recombination also increases.

The preferred thickness of the layer formed by the semiconductor fine particles is not unambiguous depending on the use of the photoelectric conversion element, but is typically preferably 0.1 to 100 μm, more preferably 1 to 50 μm, still more preferably 3 to 30 μm. .

The layer of the semiconductor fine particles 22 can be formed, for example, by applying the semiconductor fine particles 22 to the conductive support 1 or 41 and then baking at a temperature of 100 to 800 ° C. for 10 minutes to 10 hours. Thereby, the semiconductor fine particles can be brought into close contact with each other, which is preferable.
Examples of the method for coating the semiconductor fine particles 22 on the conductive support 1 or 41 include a wet method, a dry method, and other methods. The coating amount of the semiconductor fine particles 22 per 1 m ² of the surface area of the conductive support is preferably 0.5 to 500 g, more preferably 5 to 100 g.
The film forming temperature is preferably 60 to 600 ° C. when glass is used as the material of the conductive support 1 or the substrate 44.

-Light scattering layer-
In the present invention, the photoreceptor layer may have a light scattering layer. This light scattering layer is different from the semiconductor layer 45 in that it has a function of scattering incident light.
In the dye-sensitized solar cell 20, the light scattering layer 46 preferably contains rod-like or plate-like metal oxide fine particles. Examples of the metal oxide used in the light scattering layer 46 include the chalcogenide (oxide) of the metal described as the compound that forms the semiconductor fine particles. When the light scattering layer 46 is provided, the thickness of the light scattering layer is preferably 10 to 50% of the thickness of the photoreceptor layer 42.
The light scattering layer 46 is preferably a light scattering layer described in JP-A No. 2002-289274, and the description of JP-A No. 2002-289274 is preferably incorporated in this specification as it is.

-Metal oxide coating-
In the present invention, the semiconductor fine particles (including those forming the semiconductor layer 45 and the light scattering layer 46) forming the photoreceptor layer preferably have a metal oxide film on the surface thereof. As the metal oxide for forming the metal oxide film, the metal oxides mentioned above for the semiconductor fine particles can be used. May be. This metal oxide film is usually formed as a thin film, and preferably has a thickness of 0.1 to 100 nm, for example. In the present invention, when the semiconductor fine particles have a metal oxide film, the dipyrromethene complex compound is adsorbed on the semiconductor fine particles through the metal oxide film. The method for forming the metal oxide film is as described above.
In the present invention, each of the surfaces of the conductive support and the semiconductor fine particles may have a metal oxide film. In this case, each metal oxide film may be formed of the same type of metal oxide or may be formed of different types of metal oxide.

-Dye-
In the photoelectric conversion element 10 and the dye-sensitized solar cell 20, the dipyrromethene complex dye represented by the above formula (1) is supported as the sensitizing dye. The dipyrromethene complex dye represented by the formula (1) is as described above.

The semiconductor fine particles may carry other dyes together with the above-described dipyrromethene complex dye. In the present invention, the dye that can be used in combination with the dipyrromethene complex dye is not particularly limited, and examples thereof include a Ru complex dye, a squarylium cyanine dye, an organic dye, a porphyrin dye, and a phthalocyanine dye. The dye that can be used in combination is preferably a Ru complex dye, a squarylium cyanine dye, or an organic dye.

The amount of the dye used cannot be generally determined, but is preferably 0.01 to 100 mmol, more preferably 0.1 to 50 mmol, particularly preferably 1 to 10 per 1 m ² of the surface area of the conductive support 1 or 41. Millimolar. Further, the adsorption amount of the dye to the semiconductor fine particles is preferably 0.001 to 1 mmol, more preferably 0.1 to 0.5 mmol, with respect to 1 g of the semiconductor fine particles. By using such a dye amount, the sensitizing effect in the semiconductor fine particles can be sufficiently obtained.

When the dipyrromethene complex dye represented by formula (1) is used in combination with another dye, the ratio of the mass of the dipyrromethene complex dye represented by formula (1) / the mass of the other dye is 95/5 to 10/90. Is preferred, 95/5 to 50/50 is more preferred, 95/5 to 60/40 is still more preferred, 95/5 to 65/35 is particularly preferred, and 95/5 to 70/30 is most preferred.

- Electrolytes -
The photoreceptor layer contains an electrolyte. The electrolyte contained in the photoreceptor layer is synonymous with the electrolyte that the charge transfer layer described later has, and preferred ones are also the same. The electrolyte contained in the photoreceptor layer may be the same as or different from the electrolyte of the charge transfer layer, and is preferably the same.

-Coadsorbent-
In the present invention, it is preferable that the semiconductor fine particles carry a co-adsorbent together with the dipyrromethene complex dye represented by the formula (1) or a dye used in combination if necessary. As such a co-adsorbent, a co-adsorbent having at least one acidic group (preferably a carboxy group or a salt thereof) is preferable, and examples thereof include a compound having a fatty acid or a steroid skeleton.
The fatty acid may be a saturated fatty acid or an unsaturated fatty acid, and examples thereof include butanoic acid, hexanoic acid, octanoic acid, decanoic acid, hexadecanoic acid, dodecanoic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, and linolenic acid. .
Examples of the compound having a steroid skeleton include cholic acid, glycocholic acid, chenodeoxycholic acid, hyocholic acid, deoxycholic acid, lithocholic acid, ursodeoxycholic acid and the like. Preferred are cholic acid, deoxycholic acid and chenodeoxycholic acid, and more preferred are chenodeoxycholic acid.

Preferable coadsorbents include compounds represented by the formula (CA) described in paragraphs 0125 to 0129 of JP 2014-82187 A, and descriptions of paragraphs 0125 to 0129 of JP 2014-82187 A. Are preferably incorporated in the present specification as they are.

The co-adsorbent has an effect of suppressing inefficient association of the dipyrromethene complex dye and an effect of preventing reverse electron transfer from the surface of the semiconductor fine particle to the redox system in the electrolyte by being adsorbed on the semiconductor fine particle. The amount of the co-adsorbent used is not particularly limited, and is preferably 0.1 to 200 mol, more preferably 1 to 100, with respect to 1 mol of the dipyrromethene complex dye from the viewpoint of effectively expressing the above action. Mol, particularly preferably 2 to 50 mol.

-Amine compounds-
After the dye is supported on the semiconductor fine particles, the surface of the semiconductor fine particles may be treated with an amine compound. Preferable amine compounds include pyridine compounds (for example, 4-t-butylpyridine, polyvinylpyridine) and the like. In the case of a liquid, these may be used as they are, or may be used after being dissolved in an organic solvent.

<Charge transfer layer>
The charge transfer body layers 3 and 47 are layers having a function of replenishing electrons to the oxidant of the dye 21, and are provided between the light receiving electrode 5 or 40 and the counter electrode 4 or 48.
The charge transfer body layers 3 and 47 contain an electrolyte. Here, “the charge transfer layer includes an electrolyte” means to include both of an embodiment in which the charge transfer layer is composed only of an electrolyte and an embodiment that contains an electrolyte and a substance other than the electrolyte.
The charge transfer layer 3 and 47 may be solid, liquid, gel, or a mixed state thereof.

- Electrolytes -
Examples of the electrolyte include a liquid electrolyte in which a redox couple is dissolved in an organic solvent, a molten salt containing a redox couple, and a so-called gel electrolyte in which a polymer matrix is impregnated with a liquid in which a redox couple is dissolved in an organic solvent. . Especially, a liquid electrolyte is preferable at the point of photoelectric conversion efficiency.

As an oxidation-reduction pair, for example, iodine and iodide (iodide salt, ionic liquid is preferable, lithium iodide, tetrabutylammonium iodide, tetrapropylammonium iodide, methylpropylimidazolium iodide are preferable) A combination of an alkyl viologen (eg, methyl viologen chloride, hexyl viologen bromide, benzyl viologen tetrafluoroborate) and a reduced form thereof, a combination of polyhydroxybenzene (eg, hydroquinone, naphthohydroquinone, etc.) and an oxidized form thereof, A combination of trivalent iron complexes (for example, a combination of red blood salt and yellow blood salt), a combination of divalent and trivalent cobalt complexes, and the like. Among these, a combination of iodine and iodide or a combination of divalent and trivalent cobalt complexes is preferable, and a combination of iodine and iodide is particularly preferable.

The cobalt complex is preferably a complex represented by the formula (CC) described in paragraphs 0144 to 0156 of JP2014-82189A, and described in paragraphs 0144 to 0156 of JP2014-82189A. It is preferably incorporated in the present specification as it is.

When a combination of iodine and iodide is used as the electrolyte, it is preferable to further use an iodine salt of a 5-membered or 6-membered nitrogen-containing aromatic cation.

The organic solvent used for the liquid electrolyte and the gel electrolyte is not particularly limited, and is an aprotic polar solvent (for example, acetonitrile, propylene carbonate, ethylene carbonate, dimethylformamide, dimethyl sulfoxide, sulfolane, 1,3-dimethylimidazolinone, 3 -Methyloxazolidinone etc.) are preferred.
In particular, the organic solvent used for the liquid electrolyte is preferably a nitrile compound, an ether compound, an ester compound, more preferably a nitrile compound, and particularly preferably acetonitrile or methoxypropionitrile.

As the molten salt or gel electrolyte, those described in paragraph No. 0205 and paragraph Nos. 0208-0213 of JP-A No. 2014-139931 are preferable, and those of paragraph No. 0205 and paragraph Nos. 0208-0213 of JP-A No. 2014-139931 are preferable. The description is preferably incorporated herein as it is.

In addition to pyridine compounds such as 4-t-butylpyridine, electrolytes include aminopyridine compounds, benzimidazole compounds, aminotriazole compounds and aminothiazole compounds, imidazole compounds, aminotriazine compounds, urea compounds, amide compounds, and pyrimidines as additives. It may contain a compound or a nitrogen-free heterocycle.

Moreover, in order to improve photoelectric conversion efficiency, you may take the method of controlling the water | moisture content of electrolyte solution. Preferred methods for controlling moisture include a method for controlling the concentration and a method in which a dehydrating agent is allowed to coexist. It is preferable to adjust the water content (content ratio) of the electrolytic solution to 0 to 0.1% by mass.
Iodine can also be used as an inclusion compound of iodine and cyclodextrin. Cyclic amidine may be used, and an antioxidant, hydrolysis inhibitor, decomposition inhibitor, and zinc iodide may be added.

Instead of the above-mentioned liquid electrolyte and quasi-solid electrolyte, a solid charge transport material such as a p-type semiconductor or a hole transport material, for example, CuI or CuNCS can be used. Also, Nature, vol. 486, p. The electrolyte described in 487 (2012) or the like may be used. An organic hole transport material may be used as the solid charge transport material. The organic hole transport material is preferably a hole transport material that can be applied by solution and becomes a solid.
Examples of the hole transporting material include a low molecular compound or a high molecular compound, such as a triarylamine compound, a polythiophene compound (for example, poly (3-hexylthiophene-2,5-diyl), polyethylenedioxythiophene (PEDOT)). , A polyphenylene vinylene compound, a polyaniline compound, a polypyrrole compound, or a copolymer thereof.

The triarylamine compound may be a low molecular compound or a high molecular compound.
Examples of the triarylamine compound include a compound represented by the following formula (HT-1).

In formula (HT-1), R ^A1 to R ^A15 each represent a hydrogen atom or a substituent.
Examples of the substituent that can be adopted as R ^A1 to R ^A15 include a substituent selected from the above substituent group T. Even if adjacent substituents are bonded via a single bond or a linking group to form a ring. Good. From the viewpoint of heat resistance and ^durability, that at least one of R A1 ^~ Preferably, at least one of ^{R A5} is an aryl ^group, R A1 ^~ least one and ^R a ^{R A5} A6 ^{~ R A10} is an aryl group More preferred.

In the triarylamine compound, the molecular weight is preferably 400 or more, 1200 or less, more preferably 550 or more and 1100 or less, and more preferably 600 or more and 1000 or less from the viewpoint of suppressing the manufacturing variation of the photoelectric conversion element. More preferably, it is 600 or more and 900 or less.

Specific examples of the compound represented by the above formula (HT-1) include 2,2 ′, 7,7′-tetrakis- (N, N-di-p-methoxyphenylamine) -9,9-spirobi Examples include fluorene (Spiro-OMeTAD) and the compounds represented by the following (HTL-1) to (HTL-14), but the present invention is not limited thereto.

Examples of the organic hole transport material include 2,2 ′, 7,7′-tetrakis- (N, N-di-p-methoxyphenylamine) -9,9-spirobifluorene, poly (3-hexylthiophene-2 , 5-diyl), 4- (diethylamino) benzaldehyde, diphenylhydrazone, or polyethylenedioxythiophene.

Since the redox couple becomes an electron carrier, it is preferably contained at a certain concentration. A preferable concentration is 0.01 mol / L or more in total, more preferably 0.1 mol / L or more, and particularly preferably 0.3 mol / L or more. The upper limit in this case is not particularly limited, and is usually about 5 mol / L.

<Counter electrode>
The counter electrodes 4 and 48 preferably function as positive electrodes of the dye-sensitized solar cell. The counter electrodes 4 and 48 can usually have the same configuration as that of the conductive support 1 or 41, but the substrate 44 is not necessarily required in a configuration in which the strength is sufficiently maintained.
Examples of the metal forming the counter electrode include platinum (Pt), gold (Au), nickel (Ni), copper (Cu), silver (Ag), indium (In), ruthenium (Ru), palladium (Pd), Examples include rhodium (Rh), iridium (Ir), osmium (Os), and aluminum (Al).
The structure of the counter electrodes 4 and 48 is preferably a structure having a high current collecting effect. In order for light to reach the photoreceptor layers 2 and 42, at least one of the conductive support 1 or 41 and the counter electrode 4 or 48 must be substantially transparent. In the dye-sensitized solar cell of the present invention, it is preferable that the conductive support 1 or 41 is transparent, and sunlight is incident from the conductive support 1 or 41 side. In this case, it is more preferable that the counter electrodes 4 and 48 have a property of reflecting light. As the counter electrodes 4 and 48 of the dye-sensitized solar cell, glass or plastic on which a metal or a conductive oxide is vapor-deposited is preferable, and glass on which platinum is vapor-deposited is particularly preferable.
The thickness of the counter electrode is not particularly limited, but is preferably 0.01 to 100 μm, more preferably 0.01 to 10 μm, and particularly preferably 0.01 to 1 μm.

<Other configurations>
Between the conductive support 1 or 41 and the photoreceptor layer 2 or 42, in order to prevent reverse current due to direct contact between the electrolyte contained in the photoreceptor layer 2 or 42 and the conductive support 1 or 41, It is preferable to form a short-circuit prevention layer.
In order to prevent contact between the light receiving electrode 5 or 40 and the counter electrode 4 or 48, it is preferable to use a spacer S (see FIG. 2) and / or a separator.
Furthermore, in the photoelectric conversion element or the dye-sensitized solar cell, it is preferable to seal the side surface of the photoelectric conversion element or the dye-sensitized solar cell with a polymer, an adhesive, or the like in order to prevent transpiration of the constituents.

The dye-sensitized solar cell of the present invention is configured using the above-described photoelectric conversion element. For example, as shown in FIG. 1, a dye-sensitized solar cell can be obtained by connecting a conductive support of a photoelectric conversion element and a counter electrode with an external circuit 6. As the external circuit 6, a known circuit can be used without particular limitation.

The photoelectric conversion element and the dye-sensitized solar cell carry the dipyrromethene complex compound represented by the above formula (1). Thereby, high photoelectric conversion efficiency is shown.
This dipyrromethene complex compound usually exhibits yellow to blue color. Therefore, although depending on the material of each layer, when the conductive support or the counter electrode is substantially transparent, the photoelectric conversion element and the dye-sensitized solar cell exhibit yellow to blue color and are excellent in design.

[Method for producing photoelectric conversion element and dye-sensitized solar cell]
The photoelectric conversion element and the dye-sensitized solar cell of the present invention are preferably produced using a dye solution containing a dipyrromethene complex compound represented by the above formula (1) and a solvent.

In such a dye solution, the dipyrromethene complex compound represented by the above formula (1) is dissolved in a solvent, and may contain other components as necessary.

Examples of the solvent to be used include, but are not limited to, the solvents described in JP-A No. 2001-291534. In the present invention, an organic solvent is preferable, and an alcohol solvent, an amide solvent, a nitrile solvent, a ketone solvent, a hydrocarbon solvent, and a mixed solvent of two or more of these are more preferable. As the mixed solvent, a mixed solvent of an alcohol solvent and a solvent selected from an amide solvent, a nitrile solvent, a ketone solvent and a hydrocarbon solvent is preferable. More preferably, it is a mixed solvent of an alcohol solvent and an amide solvent, a mixed solvent of an alcohol solvent and a hydrocarbon solvent, or a mixed solvent of an alcohol solvent and a nitrile solvent, particularly preferably a mixed solvent of an alcohol solvent and an amide solvent, an alcohol solvent. And a mixed solvent of nitrile solvent. Specifically, a mixed solvent of at least one of methanol, ethanol, propanol and t-butanol and at least one of dimethylformamide and dimethylacetamide, or at least one of methanol, ethanol, propanol and t-butanol A mixed solvent with acetonitrile is preferred.

The dye solution preferably contains a co-adsorbent, and the co-adsorbent is preferably the above-mentioned co-adsorbent.
Here, the dye solution is preferably a dye solution in which the concentration of a dipyrromethene complex dye or a co-adsorbent is adjusted so that the solution can be used as it is when a photoelectric conversion element or a dye-sensitized solar cell is produced. The dye solution preferably contains 0.001 to 0.1% by mass of the dipyrromethene complex dye represented by the above formula (1). The amount of coadsorbent used is as described above.

The dye solution preferably has a low moisture content in terms of dye adsorption. For example, the water content is preferably adjusted to 0 to 0.1% by mass at least during use. The water content can be adjusted by a usual method at least at the time of use.

In the present invention, it is preferable to prepare a photoreceptor layer by supporting the dipyrromethene complex dye represented by the formula (1) or a dye containing the same on the surface of the semiconductor fine particles using the dye solution. That is, the photoreceptor layer is preferably formed by applying the above dye solution (including a dipping method) to semiconductor fine particles provided on a conductive support, and drying or curing.
The photoelectric conversion element of the present invention can be produced by further providing a charge transfer layer, a counter electrode and the like on the light-receiving electrode provided with the photoreceptor layer thus produced by a usual method.
Furthermore, the dye-sensitized solar cell can be manufactured by connecting the external circuit 6 to the conductive support 1 and the counter electrode 4 of the photoelectric conversion element manufactured as described above.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited thereto.

The dipyrromethene complex compounds D-1 and D-2 used in this example are shown below.

Although the synthesis method of the said dipyrromethene complex compound is demonstrated in detail below, a starting material, a pigment | dye intermediate body, and a synthetic route are not limited to these.
In the present invention, room temperature means 25 ° C.

Synthesis Example 1: Synthesis of dipyrromethene complex compound D-1 Based on the following scheme, Org. Biomol. Chem. 2010, 8, p. The dipyrromethene complex compound D-1 was synthesized according to the method described in 4546.

The dipyrromethene complex compound D-1 was identified from the following data.
In ESI-MS, m / z: 679 ([M + H] ⁺ )
Further, NMR of the obtained dipyrromethene complex compound D-1 was measured. Biomol. Chem. 2010, 8, p. Consistent with the NMR spectrum described in 4546.

Synthesis Example 2: Synthesis of dipyrromethene complex compound D-2 A dipyrromethene complex compound D-2 was synthesized according to the following scheme.

<Synthesis of Compound D-2-A>
Under a nitrogen atmosphere, 16.22 g of 3,5-bis (trifluoromethyl) benzaldehyde and 200 mL of dichloromethane were added to a 1 L three-necked flask and stirred at room temperature. Next, while cooling with water, 15.75 g of 2,4-dimethylpyrrole was added dropwise to the obtained mixture, followed by 5 drops of trifluoroacetic acid, followed by stirring at room temperature for another 30 minutes.
Next, 19.45 g of chloranil was added to the obtained mixture while cooling with water, and the mixture was further stirred at room temperature for 30 minutes. Thereafter, 80 mL of diisopropylethylamine was added dropwise with water cooling, and the mixture was further stirred at room temperature for 30 minutes. Subsequently, 85 mL of boron trifluoride diethyl ether complex was added dropwise to the obtained mixture while cooling with water, and the mixture was further stirred at room temperature for 30 minutes.
After 400 mL of a saturated aqueous sodium hydrogen carbonate solution was added dropwise to the reaction product thus obtained, the organic layer obtained by extraction and liquid separation was pre-dried with anhydrous sodium sulfate. Subsequently, the mixture was concentrated under reduced pressure, and the resulting crude product was purified by silica gel column chromatography (developing solvent: hexane / ethyl acetate) and then recrystallized from ethanol to obtain 4.40 g of compound D-2-A. .

<Synthesis of Compound D-2-B>
To a 300 mL three-necked flask, 3.05 g of compound D-2-A and 60 mL of 1,1,1,3,3,3-hexafluoro-2-propanol were added and stirred at room temperature.
Next, 3.60 g of N-iodosuccinimide (NIS) was added to the obtained mixture, and the mixture was further stirred at room temperature for 1.5 hours. After concentration of the reaction solution under reduced pressure, 50 mL of aqueous sodium thiosulfate solution (dissolved in 10 g of sodium thiosulfate) and 100 mL of methylene chloride were added to the concentrated residue, and the resulting organic layer was extracted and separated with anhydrous sodium sulfate. Pre-dried. Subsequently, the filtrate was concentrated under reduced pressure, and the resulting crude product was recrystallized from ethanol to obtain 3.90 g of Compound D-2-B.

<Synthesis of Compound D-2-C>
To a 300 mL three-necked flask was added 3.5 g of compound D-2-B, 2.5 g of 2,4,6-trimethylphenylboronic acid, 3.4 g of cesium fluoride, and 100 mL of dimethoxyethane (DME), and at room temperature. While stirring, degassed under reduced pressure, and then nitrogen gas was introduced to make a nitrogen atmosphere. To the obtained mixture, 76 mg of palladium acetate and 411 mg of SPhos (2-dicyclohexylphosphino-2 ′, 6′-dimethoxybiphenyl) were added, and the mixture was heated to reflux for 1 hour. A saturated aqueous ammonium chloride solution (100 mL) and ethyl acetate (100 mL) were added to the resulting reaction product, and the organic layer obtained by extracting and separating the mixture was pre-dried over anhydrous sodium sulfate. Subsequently, the mixture was concentrated under reduced pressure, and the resulting crude product was purified by silica gel column chromatography (developing solvent: hexane / ethyl acetate) and then recrystallized from ethanol to obtain 2.5 g of compound D-2-C. .

<Synthesis of Compound D-2-D>
To a 100 mL three-necked flask, 2.1 g of compound D-2-C, 1.5 g of 4- (methoxycarbonyl) benzaldehyde, and 40 mL of dehydrated toluene were added and stirred at room temperature. Piperidine (4 mL) was added to the obtained mixture, and the mixture was further stirred at 65 ° C. for 1 hour. The crude product obtained by concentrating the reaction solution under reduced pressure was purified by silica gel column chromatography (developing solvent: hexane / ethyl acetate) and then recrystallized from ethanol to obtain 2.4 g of compound D-2-D. Obtained.

<Synthesis of Compound D-2>
To a 100 mL three-necked flask, 1.0 g of compound D-2-D, 20 mL of tetrahydrofuran, and 5 mL of methanol were added. While heating at 40 ° C., 1 mL of 3N aqueous sodium hydroxide solution was further added and stirred for 2 hours. The resulting mixture was cooled to room temperature, and then 4 mL of a 1N trifluoromethanesulfonic acid methanol solution was added with stirring. 25 mL of water was added to the mixture thus obtained, and the precipitated solid was collected by filtration to obtain 0.9 g of dipyrromethene complex compound D-2.

The dipyrromethene complex compound D-2 was identified from the following data.
In ESI-MS, m / z: 962 ([M + H] ⁺ )

Example 1: Production of dye-sensitized solar cell Using the dipyrromethene complex compound synthesized in each synthesis example or the following comparative dye compounds C1 and C2, the dye-sensitized solar cell 20 ( 5 mm × 5 mm scale) was manufactured and the following performance was evaluated. The results are shown in Table 1.

(Preparation of light receiving electrode precursor)
A conductive substrate 41 was prepared by forming a fluorine-doped SnO ₂ conductive film (transparent conductive film 43, film thickness: 500 nm) on a glass substrate (substrate 44, thickness 4 mm). Then, the glass substrate obtained by forming the SnO ₂ conductive film was immersed for 30 minutes in an aqueous titanium tetrachloride solution of 40 mM, ultrapure water, washed with ethanol, followed by firing at 450 ° C., SnO ₂ conductive film A thin film layer of titanium oxide (metal oxide film, not shown in FIG. 2) was formed thereon. On this thin film layer, a titania paste “18NR-T” (manufactured by DyeSol) was screen-printed and dried at 120 ° C., and then the titania paste “18NR-T” was screen-printed again and dried at 120 ° C. for 1 hour. I let you. Thereafter, the dried titania paste was baked at 500 ° C. In this way, a semiconductor layer 45 (film thickness: 10 μm) was formed. Further, a titania paste “18NR-AO” (manufactured by DyeSol) was screen-printed on the semiconductor layer 45 and dried at 120 ° C. for 1 hour, and then the dried titania paste was baked at 500 ° C. Next, this glass substrate was immersed in a 20 mM titanium tetrachloride aqueous solution, washed with ultrapure water and then with ethanol, and the whole glass substrate was heated at 460 ° C. for 30 minutes. By allowing this to cool, a light scattering layer 46 (film thickness: 5 μm) was formed on the semiconductor layer 45. By the above operation, a photoreceptor layer 42 (light receiving surface area: 5 mm × 5 mm, film thickness: 15 μm) was formed on the SnO ₂ conductive film. In this way, a light receiving electrode precursor not carrying a dipyrromethene complex compound was produced.

(Dye adsorption method)
Next, each dipyrromethene complex compound synthesized in the above synthesis example was supported on the photoreceptor layer 42 not supporting the dipyrromethene complex compound as follows. First, each of the above dipyrromethene complex compounds is dissolved in a 1: 1 (volume ratio) mixed solvent of t-butanol and acetonitrile so as to have a concentration of 2 × 10 ⁻⁴ mol / L, and the coadsorbent is further dissolved therein. As a result, 10 moles of chenodeoxycholic acid was added to 1 mole of the dipyrromethene complex compound to prepare each dye solution. Next, the light receiving electrode precursor was immersed in each dye solution at 25 ° C. for 5 hours, pulled up from the dye solution, and then dried. In this way, the light receiving electrode 40 carrying each dipyrromethene complex dye on the light receiving electrode precursor was produced.

(Assembly of dye-sensitized solar cell)
As the counter electrode 48, a platinum electrode (Pt thin film thickness: 100 nm) having the same shape and size as the conductive support 41 was prepared. Further, as an electrolytic solution, iodine 0.001M (mol / L), lithium iodide 0.1M, 4-t-butylpyridine 0.5M, and 1,2-dimethyl-3-propylimidazolium iodide 0.6M were used. A liquid electrolyte was prepared by dissolving in acetonitrile. Furthermore, a spacer S (trade name: “Surlin”) manufactured by DuPont having a shape corresponding to the size of the photoreceptor layer 42 was prepared.
Each of the light-receiving electrodes 40 and the counter electrode 48 manufactured as described above are thermocompression-bonded so as to face each other via the spacer S, and then the electrolyte solution injection port is interposed between the photoreceptor layer 42 and the counter electrode 48. The charge transfer layer 47 was formed by filling the liquid electrolyte. The outer periphery of the battery thus prepared and the electrolyte inlet were sealed and cured using Resin XNR-5516 manufactured by Nagase Chemtech to produce each dye-sensitized solar cell (sample numbers 1 and 2). .

In the production of the dye-sensitized solar cell, for comparison, in the same manner as in the production of the dye-sensitized solar cell, except that the following dye compounds C1 and C2 for comparison were used instead of the dipyrromethene complex compound, respectively. Dye-sensitized solar cells (sample numbers c1 and c2) were produced.
The dye compound C1 is the dipyrromethene complex dye “ZH-b” described in Non-Patent Document 1.
The dye compound C2 is the compound 19 described in Patent Document 1. In the following formula, Hexyl represents a hexyl group, and Mes represents a mesityl group (2,4,6-trimethylphenyl group).

<Evaluation of photoelectric conversion efficiency (low illumination environment: indoor light)>
A battery characteristic test was performed using each of the produced dye-sensitized solar cells.
The battery characteristic test was performed using a white LED (model number: LDA8N-GK / D / 60W) manufactured by Toshiba. The illuminance adjustment (300 μW / cm ² (1000 lux)) was performed using ND filters (ND1 to ND80) manufactured by Shibuya Optical Co., Ltd. The adjusted illuminance measurement was confirmed using a spectroscope USB4000 manufactured by Ocean Photonics. The current-voltage characteristics were measured using an IV tester to determine the photoelectric conversion efficiency (η).
For each dye-sensitized solar cell (sample numbers 1, 2 and c2), the obtained photoelectric conversion efficiency (η) is compared with the photoelectric conversion efficiency of the dye-sensitized solar cell (sample number c1) for comparison. With respect to (η _c1 ), the following criteria were evaluated.
In this evaluation, evaluations A and B are acceptable levels, preferably A.
The photoelectric conversion efficiency (η) is relative to the photoelectric conversion efficiency (η _c1 ).
A: greater than 1.05 times B: greater than 1.01 times, 1.05 times or less C: greater than 1 time, 1.01 times or less D: 1 time or less

<Measurement of action spectrum>
The action spectrum (IPCE spectrum) was measured for each of the produced dye-sensitized solar cells.
Using PEC-S20 (trade name), a spectrum of action spectrum (IPCE spectrum) manufactured by Pexel Technologies, Inc. Irradiating simulated sunlight under irradiation conditions (150 W xenon lamp, AM1.5G, 100 mW / cm ² ) I went there.
The action spectrum in the dye-sensitized solar cell (sample number 1) using the dipyrromethene complex compound D-1 and the action spectrum in the dye-sensitized solar cell (sample number c1) using the dye compound C1 for comparison are shown in FIG. This is shown in FIG. In FIG. 3, the dipyrromethene complex compound D-1 is referred to as “compound D-1”, and the dye compound C1 is referred to as “compound C1”.

From the results shown in Table 1 and FIG.
The dye-sensitized solar cell (sample number c1) using the dye compound C1 for comparison has a small external quantum efficiency shown in FIG. 3 as a whole, and particularly the external quantum efficiency at 800 nm is 3% or less. The photoelectric conversion efficiency was not shown.
In contrast, the dye-sensitized solar cell (sample number 1) having semiconductor fine particles carrying the dipyrromethene complex compound represented by the formula (1) has a spectrum that spreads to a long wavelength region of 800 to 900 nm, The external quantum yield at a wavelength of 800 nm showed a high value exceeding 10%. Furthermore, a high external quantum yield was exhibited over a wavelength region of 300 to 800 nm. Moreover, the outstanding photoelectric conversion efficiency was shown with respect to the dye-sensitized solar cell of sample number c1.

DESCRIPTION OF SYMBOLS 1,41 Conductive support body 2,42 Photoconductor layer 21 Dye 22 Semiconductor fine particle 3,47 Charge transfer body layer 4,48 Counter electrode 5,40 Photosensitive electrode 6 Circuit 10 Photoelectric conversion element 100 The photoelectric conversion element was applied to the battery use System M Operating means (eg electric motor)
20 Dye-sensitized solar cell 43 Transparent conductive film 44 Substrate 45 Semiconductor layer 46 Light scattering layer S Spacer

Claims (11)

1. A photoelectric conversion element having a conductive support, a photoreceptor layer containing an electrolyte, a charge transfer layer containing an electrolyte, and a counter electrode, wherein the photoreceptor layer is dipyrromethene represented by the following formula (1) A photoelectric conversion element having semiconductor fine particles carrying a complex compound.
   

   

   
   In the formula, X represents CR ⁵ or N. R ⁵ represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heteroaryl group.
   R ¹ to R ⁴ each independently represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an alkoxy group, an alkylthio group, a heteroaryl group, an amino group, or a halogen atom.
   L ¹ and L ² each independently represent a single bond or a linking group.
   Z ¹ and Z ² each independently represent an acidic group or a salt thereof, and m and n each independently represents an integer of 1 or more.
   Y ¹ and Y ² each independently represent a halogen atom, an alkynyl group, an aryl group, a heteroaryl group, an alkoxy group, an aryloxy group, a heteroaryloxy group, an alkylthio group, an arylthio group or a heteroarylthio group.
2. Each of L ¹ and L ² is an aliphatic unsaturated hydrocarbon group, an aromatic hydrocarbon ring group or an aromatic heterocyclic group, or an aliphatic unsaturated hydrocarbon group, an aromatic hydrocarbon ring group and an aromatic group. The photoelectric conversion element of Claim 1 which shows the coupling group formed by combining 2 or more groups selected from the group which consists of a group heterocyclic group.
3. The photoelectric conversion element according to claim 1, wherein both of L ¹ and L ² are conjugated linking groups.
4. L ¹ and L ² are both linking groups formed by combining two or more groups selected from the group consisting of an aliphatic unsaturated hydrocarbon group, an aromatic hydrocarbon ring group, and an aromatic heterocyclic group. The photoelectric conversion element according to any one of claims 1 to 3.
5. Each of L ¹ and L ² is a linking group formed by combining two or more groups selected from the group consisting of an alkenylene group, an alkynylene group, an aromatic hydrocarbon ring group, and an aromatic heterocyclic group. Item 5. The photoelectric conversion element according to any one of Items 1 to 4.
6. The photoelectric conversion element according to any one of claims 1 to 5, wherein both L ¹ and L ² are groups represented by the following formula (L).
   Formula (L) * -L ^L1 -Ar ^L -***
   In the formula, L ^L1 represents a group represented by any of the following formulas (L-1) to (L-4). Ar ^L represents an aromatic hydrocarbon ring group or an aromatic heterocyclic group. * Represents a bond part with the pyrrole ring in the formula (1), and *** represents a bond part with Z ¹ or Z ² in the formula (1).
   

   

   
   In the formula, R ²¹ to R ²⁸ each independently represent a hydrogen atom or a substituent, and A represents an oxygen atom or a sulfur atom. * Represents a bond to the pyrrole ring in the formula (1), and ** represents a bond to Ar ^L.
7. 7. The photoelectric conversion element according to claim 1, wherein both of L ¹ and L ² are styryl groups.
8. The photoelectric conversion element according to any one of claims 1 to 7, wherein both m and n are 1.
9. The Z ¹ and Z ² are both an acidic group selected from —COOH, —SO ₃ H, —PO (OH) ₂ , —OH and —SH, or a salt thereof. The photoelectric conversion element of a term.
10. A dye-sensitized solar cell comprising the photoelectric conversion element according to any one of claims 1 to 9.
11. A dipyrromethene complex compound represented by the following formula (1).
    

    

    
    In the formula, X represents CR ⁵ or N. R ⁵ represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heteroaryl group.
    R ¹ to R ⁴ each independently represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an alkoxy group, an alkylthio group, a heteroaryl group, an amino group, or a halogen atom.
    L ¹ and L ² each independently represent a single bond or a linking group.
    Z ¹ and Z ² each independently represent an acidic group or a salt thereof, and m and n each independently represents an integer of 1 or more.
    Y ¹ and Y ² each independently represent a halogen atom, an alkynyl group, an aryl group, a heteroaryl group, an alkoxy group, an aryloxy group, a heteroaryloxy group, an alkylthio group, an arylthio group or a heteroarylthio group.
    

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