JP6300333B2 - Photoelectric conversion element, dye-sensitized solar cell, metal complex dye, dye solution, and terpyridine compound or esterified product thereof - Google Patents

Description

  The present invention relates to a photoelectric conversion element, a dye-sensitized solar cell, a metal complex dye, a dye solution, and a terpyridine compound or an esterified product thereof.

  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 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, research on photoelectrochemical cells (also called dye-sensitized solar cells) using metal complex dyes has been vigorously conducted. In particular, it was the research results of Graetzel and others at the Swiss Lausanne University of Technology. They adopted a structure in which a dye composed of a ruthenium complex was fixed on the surface of a porous titanium oxide film, realizing photoelectric conversion efficiency comparable to that of amorphous silicon. As a result, dye-sensitized solar cells that can be manufactured without using an expensive vacuum apparatus have attracted attention from researchers all over the world.

  After the report of Graetzel et al., Dyes called N3, N719, N749 (also referred to as black dye), Z907, and J2 have been developed as metal complex dyes used in dye-sensitized solar cells.

In addition to these dyes, development of metal complex dyes that improve the photoelectric conversion efficiency or durability of photoelectric conversion elements and dye-sensitized solar cells is in progress.
For example, Patent Document 1 discloses a terpyridine ligand and three benzene ring groups or thiophene ring groups containing an amino group bonded to the 3-position of the ring nitrogen atom coordinated to the metal ion of the terminal pyridine ring. Metal complex dyes having a monodentate ligand are described. It is also described that the photoelectrochemical cell using this metal complex dye achieved high photoelectric conversion efficiency and was excellent in durability.
Patent Document 2 discloses a tridentate ligand in which a thiophene ring group having a diphenylaminophenyl group is bonded to the 3-position of a ring-constituting nitrogen atom coordinated to a metal ion of an α-pyridine ring, and this Metal complexes having a ligand and three isothiocyanate anions are described.
Patent Document 3 describes a metal complex dye having a terpyridine ligand having a terminal pyridine ring to which a thiophene ring group substituted with an alkyl group having 15 carbon atoms is bonded. It is also described that a photoelectrochemical cell using this metal complex dye has high photoelectric conversion efficiency and excellent durability.
Patent Document 4 discloses a terpyridine ligand in which a thiophene ring group substituted with an alkyl group is bonded to the 3-position of a ring-constituting nitrogen atom coordinated to a metal ion of a terminal pyridine ring, and a specific substituent. Metal complex dyes having a donor ligand with a cyclic group substituted with. It is also described that the photoelectrochemical cell using this metal complex dye can achieve both reduction in performance variation and improvement in photoelectric conversion efficiency and durability.

JP 2013-67773 A US Patent Application Publication No. 2012/0247561 JP 2012-36237 A JP2013-229285A

  However, in recent years, research and development of photoelectric conversion elements and dye-sensitized solar cells have been actively performed, and the required performance has become higher. In particular, further improvement and improvement in photoelectric conversion efficiency and durability are desired.

  In a photoelectric conversion element and a dye-sensitized solar cell, a layer formed of semiconductor fine particles and supporting a metal complex dye (also referred to as a semiconductor layer) is usually formed in a layer having a thickness of 10 to several hundred μm. Such photoelectric conversion elements and dye-sensitized solar cells are also required to be thin (downsized) and lightweight. However, the photoelectric conversion efficiency varies depending on the film thickness of the semiconductor layer, and tends to decrease as the film thickness decreases. Therefore, it is desired to exhibit excellent photoelectric conversion efficiency even when the thickness of the semiconductor layer is reduced.

  INDUSTRIAL APPLICABILITY The present invention is less influenced by the film thickness of a semiconductor layer, and particularly exhibits excellent photoelectric conversion efficiency even when the film thickness is reduced, and has high durability, a photoelectric conversion element and a dye-sensitized solar cell, and the use thereof It is an object of the present invention to provide a metal complex dye, a dye solution, and a terpyridine compound or an esterified product thereof.

  The present inventors have made various studies on metal complex dyes used in photoelectric conversion elements and dye-sensitized solar cells. As a result, a tridentate structure in which three rings having a ring nitrogen atom coordinated to a metal ion are bonded. As the ligand, it is possible to use a ligand in which a specific amino group-containing aromatic ring group is introduced into the ring constituent atom at the 4-position with respect to the ring constituent nitrogen atom of the terminal ring. In the solar cell, it was found that the photoelectric conversion efficiency and durability are further improved, and that even if the semiconductor layer is a thin film, high photoelectric conversion efficiency is realized. The present invention has been 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 (I): A photoelectric conversion element having semiconductor fine particles carrying a metal complex dye.

Formula (I) M (LA) (LD) _p (LX) _q · (CI) _z

In the formula, M represents a metal ion.
LA represents a tridentate ligand represented by the following formula (LA-1).
LD represents a bidentate or tridentate ligand. p represents 0 or 1;
LX represents a monodentate ligand. q represents 3 when p is 0, represents 0 when p is 1 and LD is a tridentate ligand, and represents 1 when p is 1 and LD is a bidentate ligand. .
CI represents a counter ion necessary for neutralizing the charge of the metal complex dye. z represents an integer of 0 to 3.

In the formula, Za and Zb each independently represents a group of nonmetallic atoms necessary to complete a 5-membered or 6-membered ring. However, each ring formed by Za and Zb has one acidic group.
L ^W each independently represents a nitrogen atom or CR ^{W, R W} represents a hydrogen atom or a substituent.
L ¹ is a single ring selected from the group consisting of a benzene ring, a furan ring, a selenophene ring, a cyclopentadiene ring, a silole ring and a nitrogen-containing aromatic ring, or a polycyclic ring containing this single ring as a condensed ring. in the ring-constituting carbon atom to form a ring represents an aromatic ring group bonded to a ring containing L ^W.
L ² represents an aromatic ring group. m represents an integer of 0 to 5.
R ¹ and R ² each independently represents an alkyl group or an aromatic ring group.

<2> The ring formed by Za is a pyridine ring, pyrimidine ring, pyrazine ring, pyridazine ring, triazine ring, tetrazine ring, quinoline ring, isoquinoline ring, imidazole ring, pyrazole ring, triazole ring, thiazole ring, oxazole ring, benzo At least one selected from the group consisting of an imidazole ring, a benzotriazole ring, a benzoxazole ring and a benzothiazole ring,
The ring formed by Zb is a pyridine ring, pyrimidine ring, pyrazine ring, pyridazine ring, triazine ring, tetrazine ring, quinoline ring, isoquinoline ring, imidazole ring, triazole ring, thiazole ring, oxazole ring, benzoimidazole ring, benzotriazole ring , At least one selected from the group consisting of a benzoxazole ring and a benzothiazole ring,
Ring containing L ^W is a pyridine ring, a pyrimidine ring, a pyridazine ring, a triazine ring, a photoelectric conversion device according to at least one selected from the group consisting of tetrazine ring and quinoline ring <1>.
<3> The photoelectric conversion element according to <1> or <2>, in which M is Ru ²⁺ or Os ²⁺ .
<4> The photoelectric conversion element according to any one of <1> to <3>, in which LA is represented by the following formula (LA-2).

^Wherein, L ^1, L 2, m, ^{R 1} and ^{R 2} are each the same meaning ^{L 1,} L 2, m of formula (LA-1), and ^{R 1} and ^{R 2.} Anc1 and Anc2 each independently represent an acidic group.

<5> The photoelectric conversion element according to any one of <1> to <4>, wherein R ¹ and R ² are both aromatic ring groups.
<6> The photoelectric conversion element according to any one of <1> to <5>, wherein the single ring is a benzene ring, a furan ring, or a pyrrole ring.
<7> The photoelectric conversion element according to any one of <1> to <6>, in which LA is represented by the following formula (LA-3).

In the formula, Z represents —O— or —NR ²³ —. R ^{11 to} R ²³ each independently represents a hydrogen atom or a substituent. Anc1 and Anc2 each independently represent an acidic group. L ² has the same meaning as ^{L 2} in Formula (LA-1). n represents 0 or 1.

<8> The photoelectric conversion element according to any one of <1> to <7>, wherein the acidic group is a carboxy group or a salt thereof.

<9> The LD is a bidentate ligand represented by any one of the following formulas (2L-1) to (2L-4), and is described in any one of <1> to <8> Photoelectric conversion element.

In the formula, ring D ^2L represents an aromatic ring. A ^{111 to} A ¹⁴¹ each independently represents an anion of a nitrogen atom or an anion of a carbon atom. R ^{111 to} R ¹⁴³ each independently represent a hydrogen atom or a substituent having no acidic group. * Represents a coordination position to the metal ion M.

<10> The LD is a tridentate ligand represented by any one of the following formulas (3L-1) to (3L-4), and is described in any one of <1> to <8> Photoelectric conversion element.

In the formula, ring D ^2L represents an aromatic ring. A ^{211 to} A ²⁴² each independently represent a nitrogen atom or a carbon atom. However, in each of A ²¹¹ and A ²¹² , A ²²¹ and A ²²² , A ²³¹ and A ²³² , and A ²⁴¹ and A ²⁴² , at least one is an anion. R ^{211 to} R ²⁴¹ each independently represent a hydrogen atom or a substituent having no acidic group. * Represents a coordination position to the metal ion M.

<11> A dye-sensitized solar cell including the photoelectric conversion element according to any one of the above items <1> to <10>.
<12> A metal complex dye represented by the following formula (I).

Formula (I) M (LA) (LD) _p (LX) _q · (CI) _z

In the formula, M represents a metal ion.
LA represents a tridentate ligand represented by the following formula (LA-1).
LD represents a bidentate or tridentate ligand. p represents 0 or 1;
LX represents a monodentate ligand. q represents 3 when p is 0, represents 0 when p is 1 and LD is a tridentate ligand, and represents 1 when p is 1 and LD is a bidentate ligand. .
CI represents a counter ion necessary for neutralizing the charge of the metal complex dye. z represents an integer of 0 to 3.

In the formula, Za and Zb each independently represents a group of nonmetallic atoms necessary to complete a 5-membered or 6-membered ring. However, each ring formed by Za and Zb has one acidic group. L ^W each independently represents a nitrogen atom or CR ^{W, R W} represents a hydrogen atom or a substituent.
L ¹ is a single ring selected from the group consisting of a benzene ring, a furan ring, a selenophene ring, a cyclopentadiene ring, a silole ring and a nitrogen-containing aromatic ring, or a polycyclic ring containing this single ring as a condensed ring. in the ring-constituting carbon atom to form a ring represents an aromatic ring group bonded to a ring containing L ^W.
L ² represents an aromatic ring group. m represents an integer of 0 to 5.
R ¹ and R ² each independently represents an alkyl group or an aromatic ring group.

<13> A dye solution containing the metal complex dye described in <12> and a solvent.
<14> A terpyridine compound represented by the following formula (LA-2) or an esterified product thereof.

In the formula, L ¹ is a single ring selected from the group consisting of a benzene ring, a furan ring, a selenophene ring, a cyclopentadiene ring, a silole ring and a nitrogen-containing aromatic ring, or a polycyclic ring containing this single ring as a condensed ring. Represents an aromatic ring group bonded to the pyridine ring at a ring-constituting carbon atom forming this monocycle.
L ² represents an aromatic ring group. m represents an integer of 0 to 5.
R ¹ and R ² each independently represents an alkyl group or an aromatic ring group.
Anc1 and Anc2 each independently represent an acidic 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 code, or when simultaneously defining a plurality of substituents, etc., unless otherwise specified, The substituents and the like may be the same as or different from each other. The same applies to the definition of the number of substituents and the like. Further, when a plurality of substituents and the like are close to each other (especially when they are adjacent to each other), they may be connected to each other to form a ring unless otherwise specified.

In the present invention, the ring has the following meanings unless otherwise specified. The same applies to the cyclic group.
In the present invention, the number of ring members is not particularly limited, but is preferably 4 to 8 members, more preferably 5 or 6 members. The ring may be a condensed ring. That is, the ring includes a single ring and a polycycle (condensed ring) formed by condensing a plurality of rings. The number of rings forming the polycycle (the number of condensed rings) is not particularly limited, and is preferably 2 to 5 rings, for example.

In the present invention, the ring includes an aromatic ring and an aliphatic ring.
The aromatic ring includes an aromatic hydrocarbon ring and an aromatic heterocycle. An aromatic hydrocarbon ring refers to a hydrocarbon ring exhibiting aromaticity. Although not particularly limited, for example, a benzene ring is exemplified as the monocyclic aromatic hydrocarbon ring, and a naphthalene ring and a fluorene ring are exemplified as the polycyclic aromatic hydrocarbon ring. The aromatic heterocycle refers to a heterocycle exhibiting aromaticity, and includes a monocyclic aromatic heterocycle and a polycyclic aromatic heterocycle. The aromatic hydrocarbon ring group is also referred to as an aryl group or an arylene group depending on the valence, and similarly, the aromatic heterocyclic group is also referred to as a heteroaryl group or a heteroarylene group.
An aliphatic ring refers to a ring other than an aromatic ring, and includes an aliphatic hydrocarbon ring and an aliphatic hetero ring. Examples of the aliphatic hydrocarbon ring include a saturated hydrocarbon ring and an unsaturated hydrocarbon ring that does not exhibit aromaticity. For example, monocyclic saturated hydrocarbon ring (cycloalkane), polycyclic saturated hydrocarbon ring, monocyclic unsaturated hydrocarbon ring (cycloalkene, cycloalkyne), polycyclic unsaturated hydrocarbon ring and the like can be mentioned. .
An aromatic heterocycle and an aliphatic heterocycle may be collectively referred to as a heterocycle. A heterocycle refers to a ring having a ring atom composed of a carbon atom and a heteroatom (for example, a nitrogen atom, an oxygen atom, a sulfur atom, a silicon atom, a selenium atom, or a phosphorus atom).

  In this specification, about the display of a compound (a complex and a pigment | dye are included), it uses for the meaning containing its salt and its ion besides the compound itself. Moreover, it is the meaning including what changed a part of structure in the range which does not impair the target effect. Furthermore, the compounds that do not specify substitution or non-substitution include those having an arbitrary substituent as long as the intended effect is not impaired. As such a substituent, a substituent selected from the substituent group T described later is preferably exemplified. The same applies to substituents, linking groups and ligands.

  Further, in this specification, a numerical range expressed 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 are amino acids described later in the ring-constituting carbon atom at the 4-position with respect to the ring-constituting nitrogen atom coordinated to the metal ion in the ring forming the tridentate ligand LA. It has a metal complex dye having a tridentate ligand into which a group-containing aromatic ring group is introduced. Thereby, the influence of the film thickness of the semiconductor layer is small, and excellent photoelectric conversion efficiency and high durability are exhibited. Therefore, according to the present invention, the influence of the film thickness of the semiconductor layer is small. Particularly, even when the film thickness is reduced, the photoelectric conversion element and the dye-sensitized solar cell exhibiting excellent photoelectric conversion efficiency and high durability, and these Metal complex dyes, dye solutions, and terpyridine compounds or esterified products thereof can be provided.
The above and other features and advantages of the present invention will become more apparent from the following description, with reference where appropriate to the accompanying drawings.

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.

[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, at least a part of the semiconductor fine particles forming the photoreceptor layer carries a metal complex dye represented by the formula (I) described later as a sensitizing dye. Here, the aspect in which the metal complex dye is supported on the surface of the semiconductor fine particle includes an aspect in which the metal complex dye is adsorbed on the surface of the semiconductor fine particle, an aspect in which the metal complex dye is deposited on the surface of the semiconductor fine particle, and an aspect in which these are mixed. The adsorption includes chemical adsorption and physical adsorption, and chemical adsorption is preferable.
The semiconductor fine particles may carry another metal complex dye together with the metal complex dye of the formula (I) described later.
It is preferable that the semiconductor fine particles carry a co-adsorbent described later together with the metal complex dye.

  The photoreceptor layer contains an electrolyte. The electrolyte contained in the photoreceptor layer may be the same as or different from the electrolyte of the charge transfer layer, but is preferably the same. Here, “the same type of electrolyte” is an embodiment in which the components contained in the electrolyte of the photoreceptor layer and the components contained in the electrolyte of the charge transfer layer are the same, and the content of each component is the same, and The components included in the electrolyte of the photoreceptor layer and the components included in the electrolyte of the charge transfer layer are the same, but include the aspects in which the content of each component is different.

  The photoelectric conversion element of the present invention is not particularly limited except for 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 supporting a dye (metal complex dye) 21, and a photoreceptor layer 2 including an electrolyte between the semiconductor fine particles 22, It consists of a charge transfer layer 3 that is a hole transport layer and a counter electrode 4.
In the photoelectric conversion element 10, the light receiving electrode 5 includes the conductive support 1 and the photoreceptor layer 2, and functions as a working electrode.

  In the system 100 to which the photoelectric conversion element 10 is applied, light incident on the photoreceptor layer 2 excites the metal complex dye 21. The excited metal complex dye 21 has high energy electrons, and these electrons are transferred from the metal complex dye 21 to the conduction band of the semiconductor fine particles 22 and reach the conductive support 1 by diffusion. At this time, the metal complex dye 21 is an oxidant (cation). Electrons that have reached the conductive support 1 work in the external circuit 6, reach the oxide of the metal complex dye 21 via the counter electrode 4 and the charge transfer layer 3, and reduce this oxide. 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. 1 by the structure of the electroconductive support body 41 and the photoreceptor layer 42, and the point which has the spacer S, those photoelectric conversion elements are different. 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. 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.

  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 configurations and the like of each embodiment can be appropriately combined between the respective 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 conventional 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.

<Metal Complex Dye Represented by Formula (I)>
The metal complex dye of the present invention is represented by the following formula (I). The metal complex dye of the present invention has a ligand LA represented by the following formula (LA-1), so that the photoelectric conversion element and the dye-sensitized solar cell are less affected by the change in the film thickness of the semiconductor layer. High photoelectric conversion efficiency and excellent thermal stability can be imparted. Therefore, the metal complex dye of the present invention is preferably used as a sensitizing dye in a dye-sensitized solar cell.

Formula (I) M (LA) (LD) _p (LX) _q · (CI) _z

In the formula (I), M represents a metal ion.
LA represents a tridentate ligand represented by the following formula (LA-1).

In the formula, Za and Zb each independently represent a group of nonmetallic atoms necessary to form a 5-membered or 6-membered ring. However, at least one of the rings formed by Za and Zb has an acidic group. Three L ^W each independently represents a nitrogen atom or CR ^W, R ^W represents a hydrogen atom or a substituent.
L ¹ is a single ring selected from the group consisting of a benzene ring, a furan ring, a selenophene ring, a cyclopentadiene ring, a silole ring and a nitrogen-containing aromatic ring, or a polycyclic ring containing this single ring as a condensed ring. in the ring-constituting carbon atom to form a ring represents an aromatic ring group bonded to a ring containing L ^W.
L ² represents an aromatic ring group. m is an integer of 0 to 5, preferably an integer of 0 to 2, and more preferably 0 or 1.
R ¹ and R ² each independently represents an alkyl group or an aromatic ring group.
In the tridentate ligand represented by the formula (LA-1), the “—L ¹ — (L ² ) m—NR ¹ R ² ” group is referred to as an “amino group-containing aromatic ring group”.

LD represents a bidentate or tridentate ligand. p represents 0 or 1; P is preferably 1 in that excellent durability can be imparted to the photoelectric conversion element and the dye-sensitized solar cell.
LX represents a monodentate ligand. q represents 3 when p is 0, represents 0 when p is 1 and LD is a tridentate ligand, and represents 1 when p is 1 and LD is a bidentate ligand. .

  CI represents a counter ion necessary for neutralizing the charge of the metal complex dye. z represents an integer of 0 to 3, preferably 0 or 1, and more preferably 0.

− Metal ion M −
M is a central metal of the metal complex dye, and examples include ions of each element of Groups 6 to 12 on the long periodic table. Examples of such metal ions include Ru, Fe, Os, Cu, W, Cr, Mo, Ni, Pd, Pt, Co, Ir, Rh, Re, Mn, and Zn ions. The metal ion M may be one kind of ion or two or more kinds of ions.
In the present invention, the metal ion M is preferably Os ²⁺ , Ru ²⁺ or Fe ²⁺ , more preferably Os ²⁺ or Ru ²⁺ , and particularly preferably Ru ²⁺ .
In the state incorporated in the photoelectric conversion element, the valence of M may change due to an oxidation-reduction reaction with surrounding materials.

-Ligand LA-
The ligand LA is a tridentate ligand (compound) represented by the formula (LA-1) and coordinated to the metal ion M by three nitrogen atoms.
The ligand LA has a function of supporting the metal complex dye of the present invention on the semiconductor fine particles by an acidic group (also referred to as an adsorbing group) included in at least one of a ring formed by Za and a ring formed by Zb.

Ligands LA is a nitrogen atom, the ring-constituting carbon atom at the 4-position relative to the coordinating ring-constituting nitrogen atom to the metal ion of the ring formed by carbon atoms and L ^W (also referred to as ring containing L ^W) It has an amino group-containing aromatic ring group. In the ligands LA, when the amino group-containing aromatic ring group at the 4-position ring-constituting carbon atom of the ring containing L ^W are bonded, the absorbance of the metal complex dye having the ligand LA increases considered It is done. Photoelectric conversion elements and dye-sensitized solar cells that contain a metal complex dye having increased absorbance in the photoreceptor layer have improved photoelectric conversion efficiency. Further, even if the thickness of the semiconductor layer provided with the photoreceptor layer is reduced, excellent photoelectric conversion efficiency is exhibited. Furthermore, durability of the photoelectric conversion element and the dye-sensitized solar cell is also improved. Therefore, this ligand LA is preferably used as a ligand of a metal complex dye used in a dye-sensitized solar cell.

In formula (LA-1), Za and Zb each independently represent a nonmetallic atom group necessary for forming a 5-membered ring or a 6-membered ring. Za and Zb are preferably a nonmetallic atom group selected from a carbon atom and the above hetero atom, and more preferably a nonmetallic atom group selected from a carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom and a phosphorus atom. preferable.
The ring formed by Za and Zb is preferably a 5-membered aromatic heterocycle or a 6-membered aromatic heterocycle. In addition to a single ring, these rings include a condensed ring in which at least one of an aromatic ring and an aliphatic ring is condensed to the single ring. Moreover, the ring formed by Za and the ring formed by Zb may preferably have a substituent selected from the substituent group T described later. You may form the condensed ring which the ring which Za and Zb form mutually couple | bonded through this substituent. Examples of such a condensed ring include a 1,10-phenanthroline ring.

The 5-membered aromatic heterocycle may be a 5-membered ring containing the above heteroatoms as ring-constituting atoms. For example, at least one of a pyrazole ring, an imidazole ring, a triazole ring, a thiazole ring, an oxazole ring, a benzoimidazole ring, a benzotriazole ring, a benzoxazole ring, and a benzothiazole ring is preferable. The 6-membered aromatic heterocycle may be a 6-membered ring containing the above heteroatom as a ring-constituting atom. For example, at least one of pyridine ring, pyrimidine ring, pyrazine ring, pyridazine ring, triazine ring, tetrazine ring, quinoline ring and isoquinoline ring is preferable.
The rings formed by Za and Zb are each at least one selected from the group consisting of the group of the 5-membered aromatic heterocycle and the group of the 6-membered aromatic heterocycle. Aromatic heterocycles that are compatible with the structure of each ring represented by
The rings formed by Za and Zb are respectively a pyridine ring, pyrimidine ring, pyrazine ring, pyridazine ring, triazine ring, tetrazine ring, quinoline ring, isoquinoline ring, imidazole ring, pyrazole ring, triazole ring, thiazole ring, oxazole ring, It is preferably at least one selected from the group consisting of a benzimidazole ring, a benzotriazole ring, a benzoxazole ring and a benzothiazole ring. Specifically, the ring formed by Za is a pyridine ring, pyrimidine ring, pyrazine ring, pyridazine ring, triazine ring, tetrazine ring, quinoline ring, isoquinoline ring, imidazole ring, pyrazole ring, triazole ring, thiazole ring, oxazole ring. And at least one selected from the group consisting of a benzimidazole ring, a benzotriazole ring, a benzoxazole ring, and a benzothiazole ring. The ring formed by Zb is a pyridine ring, pyrimidine ring, pyrazine ring, pyridazine ring, triazine ring, tetrazine ring, quinoline ring, isoquinoline ring, imidazole ring, triazole ring, thiazole ring, oxazole ring, benzimidazole ring, benzo It is preferably at least one selected from the group consisting of a triazole ring, a benzoxazole ring and a benzothiazole ring.
Of these, the rings formed by Za and Zb are each more preferably an imidazole ring, a pyridine ring or a pyrimidine ring, and particularly preferably both are pyridine rings.

  At least one of the rings formed by Za and Zb has an acidic group. Both of these rings preferably have at least one acidic group. The number of acidic groups that each of the rings formed by Za and Zb has is preferably 1 to 3, more preferably 1 or 2, and even more preferably 1, each ring being an acidic group. It is particularly preferable to have one each. The substitution position of the acidic group is not particularly limited. As a substitution position, each ring preferably has a ring constituent atom that is furthest away from the nitrogen atom coordinated to the metal ion M. For example, when the ring formed by Za and Zb is a six-membered ring, the metal ion M A ring-constituting atom at the 4-position with respect to the ring-constituting nitrogen atom is exemplified.

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 acid groups exhibiting acidity such as a carboxy group, a phosphonyl group, a phosphoryl group, a sulfo group, and a boric acid group, or groups having these acid groups. Examples of the group having an acid group include a group having an acid group and a linking group. The linking group is not particularly limited, and examples thereof include a divalent group, and preferable examples include an alkylene group, an alkenylene group, an alkynylene group, an arylene group, and a heteroarylene group. This linking group may have a group selected from the substituent group T described later as a substituent. As the acidic group having an acid group and a linking group, for example, carboxymethyl, carboxyvinylene, dicarboxyvinylene, cyanocarboxyvinylene, 2-carboxy-1-propenyl, 2-carboxy-1-butenyl, carboxyphenyl and the like are preferable. Can be mentioned.
The acidic group is preferably a group having a carboxy group, a phosphonyl group, a sulfo group or a carboxy group, and more preferably a carboxy group.

When incorporated in the metal complex dye represented by the formula (I), the acidic group may be an anion dissociated by releasing a proton, or may be a salt. Although it does not specifically limit as a counter ion when an acidic group turns into a salt, For example, the example of the positive ion in the following counter ion CI is mentioned.
The acidic group may be esterified as described later.

In the formula (LA-1), the ring containing L ^W encompasses monocyclic and condensed ring, when it is a condensed ring also includes a condensed ring with the ring formed is Zb.

L ^W represents a nitrogen atom or a CR ^W. R ^W represents a hydrogen atom or a substituent, preferably a hydrogen atom. Substituents can take as R ^W is not particularly limited, a group selected from the later-described Substituent Group T (preferably excluding the following amino-group-containing aromatic ring group.) Can be mentioned. When a ring containing L ^W has a plurality of R ^W, it may form a ring by bonding R ^W together.
Ring, Za and Zb from the group of 6-membered aromatic heterocyclic ring described as ring formed has the formula (LA-1) an aromatic heterocyclic ring preferably chosen conforms to the ring structure containing an L ^W Is done. More preferably, it is at least one of a pyridine ring, a pyrimidine ring, a pyridazine ring, a triazine ring, a tetrazine ring and a quinoline ring, more preferably a pyridine ring or a pyrimidine ring, and particularly preferably a pyridine ring.

L ¹ in the amino group-containing aromatic ring group is a monocyclic aromatic ring group selected from the group consisting of a benzene ring, a furan ring, a selenophene ring, a cyclopentadiene ring, a silole ring and a nitrogen-containing aromatic ring, or this A polycyclic aromatic ring group containing a single ring as a condensed ring. Here, each ring included in the group is a single ring.
In the silole ring, the ring-constituting silicon atom may have a substituent. The substituent is not particularly limited, and examples thereof include groups selected from the substituent group T described later, and preferred are an alkyl group, an aryl group, a heteroaryl group, and the like.
The nitrogen-containing aromatic ring is not particularly limited as long as it is a monocyclic nitrogen-containing aromatic ring, and preferably a pyrrole ring, pyrazole ring, imidazole ring, triazole ring, thiazole ring, thiadiazole ring, oxazole ring, oxadiazole Examples thereof include 5-membered rings such as a ring, 6-membered single rings such as a pyridine ring, a pyrimidine ring, a pyridazine ring, a pyrazine ring, a triazine ring and a tetrazine ring.
The single ring selected from the above group is preferably a benzene ring, a furan ring, a selenophene ring or a nitrogen-containing aromatic ring, and more preferably a furan ring, a selenophene ring or a 5-membered nitrogen-containing aromatic ring in terms of photoelectric conversion efficiency. On the other hand, a benzene ring is more preferable in terms of cost and productivity. More preferred are a benzene ring, a furan ring or a pyrrole ring, and a furan ring or a pyrrole ring is particularly preferred from the viewpoint of photoelectric conversion efficiency.

Examples of the polycyclic aromatic ring group include a ring group formed by condensing a single ring selected from the above group, and a ring group formed by condensing this single ring with another ring. Although it does not specifically limit as another ring, For example, a thiophene ring is mentioned.
Here, the number of rings forming the polycycle is not particularly limited, and is preferably, for example, 2 to 5 rings, and more preferably 2 or 3 rings.
Examples of the polycyclic aromatic ring group include naphthalene ring, anthracene ring, phenanthrene ring, fluorene ring, indene ring, indole ring, benzothiophene ring, benzoisothiophene ring, benzofuran ring, thienopyridine ring, cyclopentadithiophene ring , Thieno [3,2-b] thiophene ring, thieno [3,4-b] thiophene ring, trithiophene ring, benzodithiophene ring, benzodifuran ring, dibenzofuran ring, dithienopyrrole ring, dithienosilole ring, dibenzosilole ring, carbazole ring , Benzopyrazole ring, benzimidazole ring, benzoxazole ring, benzothiazole ring, quinoline ring and the like.
Of these, a fluorene ring group, a benzofuran ring, and an indole ring are preferable.

L ¹ is a ring-constituting carbon atom that forms a single ring, and is bonded to a ring containing L ^W. Therefore, L ¹ does not contain an aromatic ring group bonded to a ring containing L ^W by a thiophene ring. Examples of the aromatic ring group not included in L ¹ include thieno [3,2-b] thiophene ring, thieno [3,4-b] thiophene ring, and trithiophene ring among the polycyclic aromatic ring groups. each ring group, and binds to the ring containing L ^W in the ring-constituting carbon atoms to form a thiophene ring, cyclopentadithiophene ring, and each ring group such as benzodithiophene ring and Jichienopiroru ring.

L ¹ may have a substituent. Such a substituent is not particularly limited, and examples thereof include a group selected from the substituent group T described later. The substituent is preferably an alkyl group, an alkoxy group, an alkylthio group, an aryl group or the like. When there are a plurality of substituents, adjacent substituents may be bonded to form an aliphatic ring together with the ring constituent atom of L ¹ . Preferred examples of the group capable of forming such an aliphatic ring include an alkylenedioxy group (—O—R ^ve —O— group) in which two alkoxy groups are linked. ^Rve represents an alkylene group, and examples thereof include ethylene and propylene.
L ¹ may be bonded to one of R ¹ and R ² described later to form a ring. The ring formed by combining ^{one of} L ¹ , N atom, and R ¹ and R ² is not particularly limited, and may be an aromatic ring or an aliphatic ring. Examples of such a ring include an aromatic heterocycle having a “nitrogen-containing ring group” structure described later, and a carbazole ring, an acridan ring, a phenoxazine ring, a phenothiazine ring, and the like are preferable.

L ² in the amino group-containing aromatic ring group is an aromatic ring group, that is, an aromatic hydrocarbon ring group or an aromatic heterocyclic group.
The aromatic hydrocarbon ring group is not particularly limited, and may be a single ring or a condensed ring. Preferably, each group of a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, and a fluorene ring is mentioned.
An aromatic heterocyclic group is not particularly limited, an aromatic ring group described above L ^1, is an aromatic ring group other than an aromatic ring group described above L ¹ and the like. When L ² is the aromatic ring group described for L ¹ , L ² and L ¹ may be the same or different ring groups.

When L ² is an aromatic ring group other than the aromatic ring group described in the above L ¹ , examples of L ² include a thiophene ring and the above-described aromatic ring group not included in L ¹ .

L ² is preferably an aromatic hydrocarbon ring group or a monocyclic and 5-membered heterocyclic group, and more preferably a benzene ring, a furan ring or a thiophene ring.

L ² may have a substituent. Such a substituent is not particularly limited, and has the same meaning as the substituent that L ¹ may have, and preferred ones are also the same. L ¹ and L ² may each form a ring by a substituent that each may have.
L ² may be bonded to one of R ¹ and R ² described later to form a ring. The ring formed by combining ^{one of} L ² , N atom, and R ¹ and R ² is not particularly limited, and is synonymous with the ring formed by L ¹ , and preferred ones are also the same.

R ¹ and R ² are each independently an alkyl group or an aromatic ring group.
The alkyl group preferably has 1 to 24 carbon atoms, and more preferably 1 to 12 carbon atoms. The alkyl group may be linear, branched or cyclic, but is preferably a linear or branched alkyl group. Examples of the alkyl group include methyl, ethyl, isopropyl, n-butyl, t-butyl, isobutyl, n-hexyl, n-octyl, 2-ethylhexyl, 3,7-dimethyloctyl, 2-butyloctyl, and n-dodecyl. , N-hexadecyl, 2-hexyldecyl, t-butyl, n-hexyl, 2-ethylhexyl or n-octyl is preferred.
The aromatic ring group includes an aryl group or a heteroaryl group.
The aryl group preferably has 6 to 24 carbon atoms, and more preferably 6 to 18 carbon atoms. In the present invention, the aryl group may be a group consisting of an aromatic hydrocarbon ring, and may be a condensed ring group in which at least one of another aromatic hydrocarbon ring and an aliphatic hydrocarbon ring is condensed. Aryl groups include phenyl, naphthyl, fluorenyl, biphenyl, anthracenyl. The aryl group as R ¹ and R ² is preferably phenyl, naphthyl or fluorenyl, more preferably phenyl.
The heteroaryl group preferably has 0 to 24 carbon atoms, and more preferably 1 to 18 carbon atoms. The hetero ring to form a heteroaryl group is not particularly limited, each ring are exemplified as described in each ring and said L ² described above L ^1.

At least one of R ¹ and R ² is preferably an aryl group or a heteroaryl group, more preferably an aryl group or a heteroaryl group from the viewpoint of photoelectric conversion efficiency, and both are an aryl group. Particularly preferred.

R ¹ and R ² may not be bonded to each other, and may be bonded to each other to form a ring. The nitrogen-containing cyclic group formed by combining R ¹ and R ² is not particularly limited, and may be an aromatic cyclic group or an aliphatic cyclic group. Examples of such nitrogen-containing ring groups include morpholine ring groups, thiomorpholine ring groups, piperidine ring groups, indole rings, and the following nitrogen-containing ring groups.

Here, R ^DA3 and R ^DA4 each independently represent an alkyl group or an aryl group. Alkyl and aryl group has the same meaning as alkyl or aryl group of R ¹ and R ^2, and preferred ones are also the same.
Each of the above nitrogen-containing ring groups may have a substituent. Examples of the substituent that these rings may have include a substituent selected from the substituent group T described later. Also, the number of substituents is not particularly limited. When it has a plurality of substituents, the same substituent or different substituents may be used.

R ¹ and R ² may each independently have a substituent. The R ¹ and R ² substituents which may have, respectively, but are not limited to, include groups selected from Substituent Group T described later. Of these, an alkyl group, an aryl group, an alkoxy group, an alkylthio group, a silyl group, a halogen atom and an amino group are preferable, and an alkoxy group and an alkylthio group are more preferable.

The N, N-dialkylamino group in which R ¹ and R ² are both alkyl groups is not particularly limited. For example, N, N-dimethylamino, N, N-diethylamino, N, N-dipropylamino, N , N-dipentylamino, N, N-bis (n-hexyl) amino, N, N-didecylamino, N-methyl-Nn-hexylamino, N, N-bis (2-ethylhexyl) amino, N, N -Bis (n-octyl) amino, N, N-bis (n-decyl) amino and the like.
The N, N-diarylamino group in which R ¹ and R ² are both aryl groups is not particularly limited. For example, N, N-diphenylamino, N, N-di (4-methylphenyl) amino, N, N-di (4- (t-butyl) phenyl) amino, N, N-di (4- (n-hexyl) phenyl) amino, N, N-di (4-methoxyphenyl) amino, N, N-di (4- (n-octyloxy) phenyl) amino, N, N-di (4-trimethylsilylphenyl) amino, N, N-di (3,5-dimethylphenyl) amino, N, N-di (4-dimethyl) Aminophenyl) amino, N, N-di (4-methylthiophenyl) amino, N, N-di (4-biphenyl) amino, N, N-dinaphthylamino, N, N-difluorenylamino, N, N -Di (4-Diff Nylaminophenyl) amino, N, N-di (4-fluorophenyl) amino, N, N-di (4-trifluoromethylphenyl) amino, N, N-di (4-chlorophenyl) amino, N-methoxyphenyl -N-naphthylamino, 4,7-di (t-butylcarbazoyl) amino and the like.
N, N-diheteroarylamino groups in which R ¹ and R ² are both heteroaryl groups include N, N-dithienylamino, N, N-di (4-alkylthienyl) amino, N, N-di (4- (n-hexyl) thienyl) amino, N, N-di (3-pyridyl) amino and the like.

  The ligand LA is preferably a tridentate ligand (terpyridine compound) represented by the following formula (LA-2).

^{Wherein, L 1, L 2, m,} R 1 and ^{R 2} are each the same meaning as ^{L 1, L 2, m,} R 1 and ^{R 2} in the formula (LA-1), preferred ones are also the same It is. However, L < ¹ > is couple | bonded with a pyridine ring by the ring-constituting carbon atom which forms the said monocycle in L < ¹ >.
Anc1 and Anc2 each independently represent an acidic group. An acidic group is synonymous with the acidic group of a formula (LA-1), and its preferable thing is also the same.

The terpyridine compound is the ligand LA itself, but in the present invention, the ligand LA can be used as a precursor compound of the ligand LA as described later. Therefore, in the present invention, the ligand LA includes a precursor compound of the ligand LA in addition to the ligand LA itself (the terpyridine compound). Preferable precursor compounds include ester bodies in which at least one of Anc1 and Anc2 of the terpyridine compound is esterified (also referred to as an esterified product of a terpyridine compound).
This esterified compound is a compound in which the acidic group is protected and can be regenerated to an acidic group by hydrolysis or the like, and is not particularly limited. Examples thereof include alkyl esterified products, aryl esterified products, and heteroaryl esterified products of the above acidic group. Among these, alkyl esterified products are preferable. The alkyl group that forms the alkyl ester product is not particularly limited, but an alkyl group having 1 to 10 carbon atoms is preferable, an alkyl group having 1 to 6 carbon atoms is more preferable, and an alkyl group having 1 to 4 carbon atoms is more preferable. The aryl group forming the aryl esterified product and the heteroaryl group forming the heteroaryl esterified product are not particularly limited, and examples thereof include those exemplified in the substituent group T described later. These groups may have one or more substituents selected from the substituent group T described later.
The acidic group to be esterified is preferably two of Anc1 and Anc. In this case, the two esters may be the same or different.

  The ligand LA is more preferably a tridentate ligand represented by the following formula (LA-3). The tridentate ligand represented by the formula (LA-3) has the amino group-containing aromatic ring group. When such a tridentate ligand LA is introduced into the photoelectric conversion element and the metal complex dye contained in the photoreceptor layer of the dye-sensitized solar cell, the photoelectric conversion efficiency and durability are further improved.

In the formula, Z represents —O— or —NR ²³ —.
R ^{11 to} R ²³ each independently represents a hydrogen atom or a substituent. The substituents that R ^{11 to} R ²³ can take are synonymous with the substituents that R ¹ and R ² can take, and preferred ones are also the same. Two adjacent ones of R ^{11 to} R ²² may be connected to each other to form a ring.
Anc1 and Anc2 each independently represent an acidic group. An acidic group is synonymous with the acidic group of a formula (LA-1), and its preferable thing is also the same.
L ² has the same meaning as ^{L 2} in Formula (LA-1). n represents 0 or 1.
The esterified product of the terpyridine compound represented by the formula (LA-3) is synonymous with the esterified product of the terpyridine compound represented by (LA-2), and preferred ones are also the same.

The ligand LA can be synthesized by a usual method. For example, the ligand LA represented by the formula (L1-4) comprises a compound represented by the formula (L1-1) and a compound represented by the formula (L1-2) as shown in the following scheme. It can synthesize | combine by carrying out a coupling reaction and hydrolyzing the ester group of the precursor compound represented by Formula (L1-3). In this synthesis method, an esterified product of a carboxy group is shown as a precursor compound. However, in the present invention, the precursor compound is not limited to this and may be any precursor compound obtained by esterifying any of the acidic groups.
The coupling reaction at this time is, for example, the “Suzuki coupling reaction” or “Still coupling reaction” described in the Chemical Society of Japan, “Experimental Chemistry Course 5th Edition”, Maruzen Co., Ltd., Volume 13, p92-117. Etc. or according to these. The hydrolysis can be performed, for example, according to the method described in the Chemical Society of Japan, “Experimental Chemistry Course 5th Edition”, Maruzen Co., Ltd., Volume 16, p10-15. For example, the method synthesized in Examples described later can be mentioned.
In the present invention, the metal complex dye of the present invention can be synthesized using the ligand LA synthesized by hydrolyzing the precursor compound. Moreover, after converting into a metal complex dye using a precursor compound like Example 1 mentioned later, an ester group is hydrolyzed according to the said method, and the metal complex dye of this invention can also be synthesize | combined.

Wherein, ^{L V} of the amino group-containing aromatic Hajime Tamaki represents - ^{(-L 1 (L 2) m} -NR 1 R 2). In Formula (L1-1), Y ¹ represents a trialkyltin group, a boronic acid group, a boronic acid ester group, a halogen atom, or a perfluoroalkylsulfonyloxy group.
In Formula (L1-2), Y ² represents a halogen atom or a perfluoroalkylsulfonyloxy group when Y ¹ in Formula (L1-1) is a trialkyltin group, a boronic acid group, or a boronic ester group, When Y ^{1 in} formula (L1-1) is a halogen atom or a perfluoroalkylsulfonyloxy group, it represents a trialkyltin group, a boronic acid group, or a boronic ester group.
In formula (L1-2) and formula (L1-3), R represents an alkyl group, an aryl group, or a heteroaryl group.

  Specific examples of the ligand LA are shown below. Examples of the ligand LA include a ligand LA in a metal complex dye described later. Moreover, the compound which made at least 1 of -COOH the salt of the carboxy group with respect to the ligand LA of the following specific example and the specific example of a metal complex dye is also mentioned. In this compound, examples of a counter cation that forms a salt of a carboxy group include positive ions described in the following CI. Furthermore, examples of the esterified product of the terpyridine compound include compounds obtained by esterifying at least one acidic group with respect to the ligand L1 in the following specific examples and specific examples of the metal complex dye. The present invention is not limited to these ligands LA, salts or esterified products thereof. In the following specific examples, Me represents methyl.

− Ligand LD −
LD is a bidentate ligand or a tridentate ligand different from the ligand LA.
This ligand LD preferably does not have an acidic group adsorbed on the surface of the semiconductor fine particles. Even if the ligand LD contains a group corresponding to an acidic group, the ligand LD is preferably not adsorbed on the surface of the semiconductor fine particles.

  In the ligand LD, at least one of the coordination atoms bonded to the metal ion M is preferably an anion. “Is an anion” means that a hydrogen atom bonded to any hydrogen atom or coordination atom in the molecule can be dissociated and bonded to the metal ion M. When the metal complex dye has a ligand LD that coordinates to the metal ion M by an anion of the coordination atom together with the ligand LA, the thermal stability of the photoelectric conversion element or the dye-sensitized solar cell is improved. In addition to high photoelectric conversion efficiency, it exhibits particularly high durability.

The ligand LD is not particularly limited as long as it is a bidentate or tridentate ligand.
For example, acyloxy group, acylthio group, thioacyloxy group, thioacylthio group, acylaminooxy group, thiocarbamate group, dithiocarbamate group, thiocarbonate group, dithiocarbonate group, trithiocarbonate group, acyl group, alkylthio group, A ligand coordinated by a group selected from the group consisting of an arylthio group, an alkoxy group and an aryloxy group, for example, a coordinate coordinated by a group in which two or three groups selected from the above group are linked to each other A child.
Other examples include ligands such as 1,3-diketone, carbonamide, thiocarbonamide, thiourea, quinolinol, or bipyridine. The 1,3-diketone is not particularly limited, but preferably a 1,3-diketone having 3 to 20 carbon atoms, such as acetylacetone, trifluoroacetylacetone, trifluoroacetyltrifluoroacetone, 4-fluorobenzoyltrifluoro Acetone, dipivaloylmethane, dibenzoylmethane, 3-chloroacetylacetone and the like can be mentioned.

Furthermore, the ligand represented by a following formula (DL) is also mentioned.
Among the above ligands, a ligand represented by the following formula (DL) is preferable.

In the formula, ring D ^DL , ring E ^DL and ring F each independently represent a 5-membered or 6-membered aromatic ring. R ^a , R ^a1 and R ^a4 each independently represent a substituent having no acidic group. mb represents 0 or 1.
ma1 and ma4 each independently represents an integer of 0 to 3. ma represents an integer of 0 to 4 when mb is 0, and represents an integer of 0 to 3 when mb is 1.
Here, when each of ma, ma1, and ma4 is an integer of 2 or more, the plurality of R ^a , the plurality of R ^a1, and the plurality of R ^a4 may be the same or different and are bonded to each other to form a ring. May be. R ^a and R ^a1 , R ^a and R ^a4 may be linked to form a ring.

Examples of the 5-membered or 6-membered aromatic ring in ring D ^DL , ring E ^DL and ring F include aromatic hydrocarbon rings and aromatic hetero rings, and aromatic hetero rings are preferable. In each of the ring D ^DL , the ring E ^DL and the ring F, at least one of an aromatic ring and an aliphatic hydrocarbon ring may be condensed.
When Ring D ^DL , Ring E ^DL and Ring F are aromatic hydrocarbon rings, a benzene ring is preferred.
The aromatic heterocycle may be an aromatic ring containing the above heteroatom as a ring-constituting atom, for example, a non-condensed 6-membered ring, a 5-membered condensed 6-membered ring, or a benzene ring condensed 5 A 6-membered ring in which a member ring or a benzene ring is condensed is preferable, a 6-membered ring having a non-condensed ring, a 5-membered ring having a 5-membered ring condensed is more preferable, and a 6-membered ring having a non-condensed ring is further preferable.

Examples of such an aromatic heterocycle include 6-membered rings such as a pyridine ring, a pyrimidine ring, a pyrazine ring, a triazine ring, a quinoline ring, and a quinazoline ring. In addition, pyrrole ring, imidazole ring, pyrazole ring, oxazole ring, thiazole ring, benzimidazole ring, benzoxazole ring, benzothiazole ring, indole ring, indazole ring, triazole ring, thiophene ring, furan ring, etc. Can be mentioned.
Ring D ^DL and ring E ^DL are preferably a pyrrole ring, a pyrazole ring, an imidazole ring, a triazole ring, a pyrazine ring or a benzene ring, and more preferably a pyrazole ring, a triazole ring or a benzene ring.
Ring F is preferably an aromatic heterocycle containing a nitrogen atom, more preferably a pyridine ring, pyrimidine ring or triazine ring, still more preferably a pyridine ring or pyrimidine ring, and particularly preferably a pyridine ring.

Here, the ring D ^DL , the ring E ^DL and the ring F include a coordination atom that is bonded to the metal ion M. The coordination atom is not particularly limited, but is preferably a carbon atom, a nitrogen atom, a sulfur atom, an oxygen atom or an anion of these atoms.
As an anion to bind metal ions M is not particularly limited, = C - ^- carbanion such as an ion,> N ^- nitrogen anions such as ions are preferred.

^Examples of the substituent for R ^a , R ^a1 and R ^a4 include a group selected from the substituent group T described later.
R ^a is an aromatic heterocyclic group, aromatic hydrocarbon ring group, ethenyl group, ethynyl group, halogen atom, alkyl group, amino group (alkylamino group, dialkylamino group, arylamino group, diarylamino group, among others. , N-alkyl-N-arylamino groups, etc.), alkoxy groups, aryloxy groups, alkylthio groups, arylthio groups, silyl groups are preferred, aromatic heterocyclic groups, aromatic hydrocarbon ring groups, ethenyl groups, ethynyl. A group, an alkyl group, an alkoxy group or an amino group (including an alkylamino group, a dialkylamino group, an arylamino group, a diarylamino group and the like) is more preferable. A group formed by combining the above groups is also preferable.

R ^a1 and R ^a4 are each an alkyl group, a cycloalkyl group, an alkenyl group (preferably ethenyl group), an alkynyl group (preferably ethynyl group), an aryl group, or a heterocyclic group (preferably an aromatic heterocyclic group). , Halogen atom, alkoxy group, alkoxycarbonyl group, cycloalkoxycarbonyl group, aryloxy group, alkylthio group, arylthio group, amino group, cyano group, alkylsulfonyl group, arylsulfonyl group, halogenated alkyl group (for example, fluoroalkyl group) ), Preferably a halogenated aryl group, more preferably a halogenated alkyl group, a halogenated aryl group, a halogen atom, a cyano group, an alkylsulfonyl group or an arylsulfonyl group, a halogenated alkyl group, a halogenated aryl group, a halogen atom, Roh group is more preferable. A group formed by combining the above groups is also preferable. The halogenated alkyl group and the halogenated aryl group will be described later.

The number of carbon atoms of each substituent that can be taken as R ^a is not particularly limited, but among the substituents that can be taken as R ^a , the substituent of the same type as the substituent that can be taken as R ^AA described later is R ^AA. It is preferably the same as the carbon number of the substituent that can be taken. More preferably, the preferable range of the carbon number is the same. Among the substituents that can be taken as R ^a , the substituents that are not substituents that can be taken as R ^AA described later are the same as the carbon number of each substituent in the substituent group T described later, and the preferred ranges are also the same. is there. The same applies to each substituent that can be adopted as R ^a1 or R ^a4 .

When R ^a , R ^a1, or R ^a4 has a group formed by further combining the above groups as a substituent, R ^a , R ^a1, and R ^a4 are each represented by the following formula (V ^U -1) as a substituent. ^{Alternatively} , it preferably has a group R ^VU represented by the formula (V ^U -2), and R ^a preferably has the following group R ^VU .

In formula (V ^U -1), T represents an oxygen atom, a sulfur atom, -NR ^CA- , -C (R ^CA ) ₂ -or -Si (R ^CA ) _2- , and R ^CA is a hydrogen atom or Represents a substituent. R ^AA , R ^AB and R ^AC each independently represent a hydrogen atom or a substituent, and at least one of R ^{AA to} R ^AC represents a substituent. At least one of R ^AA and R ^AC is preferably a substituent, and R ^AA is more preferably a substituent.
In formula (V ^U -2), R ^{BA to} R ^BE each independently represent a hydrogen atom or a substituent, and at least one of R ^BA , R ^BB , R ^BD and R ^BE represents a substituent.

The number of groups R ^VU possessed by the ligand LD may be one or more, preferably 1 to 3, and more preferably 1 or 2.

In the formula (V ^U -1), T is preferably a sulfur atom. R ^CA is preferably a hydrogen atom. The substituents can take as R ^CA include groups selected from Substituent Group T described later.

R ^AA preferably represents a substituent. The substituent that can be adopted as R ^AA is not particularly limited, and examples thereof include a group selected from substituent group T described later. Preferably, alkyl group, alkenyl group (preferably ethenyl group), alkynyl group (preferably ethynyl group), cycloalkyl group, alkoxy group, cycloalkoxy group, aryloxy group, alkylthio group, cycloalkylthio group, arylthio group, amino group A group, an alkylamino group, a cycloalkylamino group, an arylamino group, a heterocyclic amino group, a silyl group or a silyloxy group.
Among the above groups, the substituent that can be taken as R ^AA is an alkyl group, cycloalkyl group, alkoxy group, cycloalkoxy group, alkylthio group, cycloalkylthio group, amino group, alkylamino group, cycloalkylamino group, or aryl. It is more preferably an amino group, more preferably an alkyl group, a cycloalkyl group, an alkoxy group, a cycloalkoxy group, an alkylamino group, a cycloalkylamino group or an arylamino group, and an alkyl group, an alkoxy group or an alkylamino group. It is particularly preferably a group, and most preferably an alkyl group or an alkoxy group.
Any of the substituents that can be ^employed as the R ^AA is preferably bonded to a thiophene ring (when T is a sulfur atom) in terms of photoelectric conversion efficiency.
The above substituent that can be taken as R ^AA may be further substituted with a group selected from the substituent group T described later.

  The alkyl group includes a straight chain alkyl group and a branched alkyl group. 1-30 are preferable, as for carbon number of an alkyl group, 4-30 are more preferable, 5-26 are more preferable, and 6-20 are especially preferable. Examples of the alkyl group include methyl, ethyl, n-butyl, t-butyl, n-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-decyl, 3,7-dimethyloctyl, isodecyl, s- Examples include decyl, n-dodecyl, 2-butyloctyl, n-hexadecyl, isohexadecyl, n-eicosyl, n-hexacosyl, isooctacosyl, trifluoromethyl or pentafluoroethyl.

  3-30 are preferable, as for carbon number of a cycloalkyl group, 5-30 are more preferable, 6-26 are more preferable, and 6-20 are especially preferable. Examples of the cycloalkyl group include cyclopropyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl. The cycloalkyl group may be condensed with a heterocycle.

  The alkoxy group includes a straight-chain alkoxy group and a branched alkoxy group. The alkyl part of the alkoxy group has the same meaning as the above alkyl group, and preferred ones are also the same. Examples of the alkoxy group include methoxy, ethoxy, n-propoxy, i-propoxy, n-butoxy, t-butoxy, n-pentoxy, n-hexyloxy, n-octyloxy, 2-ethylhexyloxy, 3,7- Dimethyloctyloxy, n-decyloxy, isodecyloxy, s-decyloxy, 2-butyloctyloxy, n-dodecyloxy, n-hexadecyloxy, isohexadecyloxy, n-eicosyloxy, n-hexacosyloxy or An example is isooctacosyloxy.

  The cycloalkyl part of the cycloalkoxy group has the same meaning as the above cycloalkyl group, and preferred ones are also the same. Examples of the cycloalkoxy group include cyclopropyloxy, cyclopentyloxy, cyclohexyloxy, cycloheptyloxy, and cyclooctyloxy.

  The aryloxy group includes a hydrocarbon ring-type aryloxy group in which the aryl group is an aromatic hydrocarbon ring group, and a heteroaryloxy group in which the aryl group is an aromatic heterocyclic group. 3-30 are preferable, as for carbon number of an aryloxy group, 3-25 are more preferable, 3-20 are more preferable, and 3-16 are especially preferable. Examples of the aryloxy group include phenoxy, naphthoxy, imidazolyloxy, benzimidazolyloxy, pyridin-4-yloxy, pyrimidinyloxy, quinazolinyloxy, purinyloxy and thiophen-3-yloxy. A thiophene ring is preferred as the heterocycle of the heteroaryloxy group.

  The alkylthio group includes a linear alkylthio group and a branched alkylthio group. The alkyl part of the alkylthio group has the same meaning as the above alkyl group, and preferred ones are also the same. Examples of the alkylthio group include methylthio, ethylthio, n-propylthio, i-propylthio, n-butylthio, t-butylthio, n-pentylthio, n-hexylthio, n-octylthio, 2-ethylhexylthio, 3,7-dimethyloctyl. Examples include thio, n-decylthio, isodecylthio, s-decylthio, n-dodecylthio, 2-butyloctylthio, n-hexadecylthio, isohexadecylthio, n-eicosylthio, n-hexacosylthio or isooctacosylthio.

  The cycloalkyl part of the cycloalkylthio group has the same meaning as the above cycloalkyl group, and the preferred ones are also the same. Examples of the cycloalkylthio group include cyclopropylthio, cyclopentylthio, cyclohexylthio, cycloheptylthio, and cyclooctylthio.

  The arylthio group includes a hydrocarbon ring-type arylthio group in which the aryl group is an aromatic hydrocarbon ring group, and a heteroarylthio group in which the aryl group is an aromatic heterocyclic group. 3-30 are preferable, as for carbon number of an arylthio group, 3-25 are more preferable, 3-20 are more preferable, and 3-16 are especially preferable. Examples of the arylthio group include phenylthio, naphthylthio, imidazolylthio, benzimidazolylthio, pyridin-4-ylthio, pyrimidinylthio, quinazolinylthio, purinylthio, thiophen-3-ylthio and the like. A thiophene ring is preferred as the heterocycle of the heteroarylthio group.

  The alkylamino group includes an N-alkylamino group and an N, N-dialkylamino group, and the alkyl group preferably has 1 to 30 carbon atoms, and more preferably 2 to 30 carbon atoms. Examples of the alkylamino group include ethylamino, diethylamino, 2-ethylhexylamino, bis (2-ethylhexyl) amino, and n-octadecylamino.

  The cycloalkylamino group includes an N-cycloalkylamino group and an N, N-dicycloalkylamino group. The cycloalkyl part of the cycloalkylamino group has the same meaning as the above cycloalkyl group, and the preferred ones are also the same. Examples of the cycloalkylamino group include cyclopropylamino, dicyclopropylamino, N-cyclopropyl-N-ethylamino, cyclopentylamino, dicyclopentylamino, N-cyclopentyl-N-methylamino, cyclohexylamino, dicyclohexylamino, And cycloheptylamino or cyclooctylamino.

The arylamino group includes a hydrocarbon ring system arylamino group in which the aryl group is an aromatic hydrocarbon ring group, and a heteroarylamino group in which the aryl group is an aromatic heterocyclic group. The hydrocarbon ring system arylamino group includes an N-arylamino group, an N-alkyl-N-arylamino group, and an N, N-diarylamino group. The heteroarylamino group includes an N-heteroarylamino group, an N-alkyl-N-heteroarylamino group, an N-aryl-N-heteroarylamino group and an N, N-diheteroarylamino group.
3-30 are preferable, as for carbon number of an arylamino group, 3-25 are more preferable, 3-20 are more preferable, and 3-16 are especially preferable. Examples of the arylamino group include phenylamino, N-phenyl-N-ethylamino, naphthylamino, imidazolylamino, benzimidazolylamino, pyridin-4-ylamino, pyrimidinylamino, quinazolinylamino, purinylamino, and thiophen-3-yl. Ilamino and the like can be mentioned.

  The heterocyclic amino group is a heterocyclic amino group other than the heteroarylamino group (aliphatic heterocyclic amino group). 0-30 are preferable, as for carbon number, 1-25 are more preferable, 2-20 are more preferable, and 2-16 are especially preferable. Moreover, as a heterocyclic ring, what a ring-constituting hetero atom is chosen from an oxygen atom, a sulfur atom, and a nitrogen atom is preferable, and a 5-7 membered ring is preferable, and a 5 or 6 membered ring is more preferable. Examples of the heterocyclic amino group include pyrrolidin-3-ylamino, imidazolidinylamino, benzimidazolidinylamino, piperidin-4-ylamino, and tetrahydrothiophen-3-ylamino.

  The silyl group includes an alkylsilyl group, a cycloalkylsilyl group, an arylsilyl group, an alkyloxysilyl group, a cycloalkyloxysilyl group, and an aryloxysilyl group. Preferred silyl groups are alkylsilyl groups, cycloalkylsilyl groups, or arylsilyl groups. 3-30 are preferable, as for carbon number of a silyl group, 3-24 are more preferable, 3-20 are more preferable, and 3-18 are especially preferable. Examples of the silyl group include trimethylsilyl, triethylsilyl, t-butyldimethylsilyl, cyclohexyldimethylsilyl, triisopropylsilyl, t-butyldiphenylsilyl, methyldimethoxysilyl, phenyldimethoxysilyl, and phenoxydimethylsilyl.

  The silyloxy group includes an alkylsilyloxy group, a cycloalkylsilyloxy group, and an arylsilyloxy group. 3-30 are preferable, as for carbon number of a silyloxy group, 3-24 are more preferable, 3-20 are more preferable, and 3-18 are especially preferable. Examples of the silyloxy group include trimethylsilyloxy, triethylsilyloxy, t-butyldimethylsilyloxy, triisopropylsilyloxy, cyclohexyldimethylsilyloxy, and t-butyldiphenylsilyloxy.

R ^AB represents a hydrogen atom or a substituent, and is preferably a hydrogen atom.
R ^AC represents a hydrogen atom or a substituent.
The substituent which can be taken as R ^AB and R ^AC has the same meaning as R ^AA , and preferred ones are also the same. When R ^AB or R ^AC is a substituent, this substituent may be the same as or different from R ^AA .

In the group R ^VU represented by the formula (V ^U -2), R ^{BA to} R ^BE each independently represent a hydrogen atom or a substituent. The substituent that each of R ^{BA to} R ^BE can take is synonymous with R ^AA described above, and preferred ones are also the same.
However, at least one of R ^BA , R ^BB , R ^BD and R ^BE is a substituent. At least one or both of R ^BA and R ^BE are substituents, and R ^BB , R ^BC and R ^BD are all hydrogen atoms, or at least one or both of R ^BB and R ^BD are substituents, and R ^BA , R ^BC and R ^BE are particularly preferably all hydrogen atoms.
When two or more of R ^{BA to} R ^BE are substituents, the two or more substituents may be the same as or different from each other.

  In the formula (DL), ma, ma1 and ma4 are preferably integers of 0 to 2, and more preferably 1 or 2.

When the ring F has R ^a , the position (substitution position) to which R ^a is bonded in the ring F is not particularly limited. When the ring F is a 5-membered ring, the 3-position with respect to the ring-constituting nitrogen atom coordinated to the metal atom M is preferable. When the ring F is a 6-membered ring, the 3-position or 4-position is preferable with respect to the ring-constituting nitrogen atom coordinated to the metal atom M, and 4-position is more preferable.
Moreover, if the ring ^{D DL} and ring ^{E DL} each have a ^{R a1} or ^{R a} 4, a ^{position R a1} or ^{R a} 4 are attached in each ring ^{D DL} and ring ^{E DL} is not particularly limited.

  The ligand represented by the above formula (DL) is preferably represented by the following formula (DL-1) or (DL-2).

R ^a2 and R ^a3 each independently represent a substituent having no acidic group. ma2 represents 0 or 1, and 1 is preferable. ma3 represents an integer of 0 to 2, and 1 or 2 is more preferable.
X1 and X2 each independently represent CR ^a5 or a nitrogen atom. R ^a5 has the same meaning as R ^a in formula (DL), and the preferred range is also the same. The ring containing X1 and X2 (also referred to as ring F) has the same meaning as ring F in formula (DL), and the preferred range is also the same.
R ^{a1, R} a4, ma1 and ma4 has the same meaning as ^{R a1,} R a4, ma1 and ma4 in the formula (DL), and the preferred range is also the same.
The substituent represented by R ^a2 and R ^a3 has the same meaning as R ^a in the above formula (DL), and the preferred range is also the same.
When each of ma1, ma3 and ma4 is an integer of 2 or more, the plurality of R ^a1 , R ^a3 and R ^a4 may be the same or different, and may be bonded to each other to form a ring.

Ring D and ring E each independently represent a 5-membered or 6-membered aromatic ring. Examples of such an aromatic ring include the rings mentioned in the ring DD ^L and ring E ^DL in the above formula (DL), and preferred aromatic rings are the same as those mentioned in the ring D ^DL and ring E ^DL. .
The bond between D ¹ and D ^{2 in} ring D and ring E and the carbon atom bonded to the F ring may be a single bond or a double bond.
D ¹ and D ² each independently represents an anion of a carbon atom or an anion of a nitrogen atom.

  Ring D and ring E are preferably a pyrrole ring, an imidazole ring, a pyrazole ring, a triazole ring or a benzene ring, and more preferably a pyrazole ring, a triazole ring or a benzene ring.

  When the ligand LD is a bidentate ligand, a bidentate ligand represented by any one of the following formulas (2L-1) to (2L-4) is preferable.

In the formula, * represents a coordination position (bonding position) with the metal ion M. Ring D ^2L represents an aromatic ring. A ^{111 to} A ¹⁴¹ each independently represents an anion of a nitrogen atom or an anion of a carbon atom. R ^{111 to} R ¹⁴³ each independently represent a hydrogen atom or a substituent having no acidic group.

Here, A ^{111 to} A ¹⁴¹ are an anion of a carbon atom or an anion of a nitrogen atom in which a hydrogen atom bonded to a nitrogen atom or a carbon atom constituting the ring D ^2L is dissociated. In the formulas (2L-1) to (2L-4), the ring ^D2L is an aromatic hydrocarbon ring, an aromatic heterocycle containing oxygen, an aromatic heterocycle containing sulfur, or an aromatic heterocycle containing nitrogen. Is mentioned.
Examples of the aromatic hydrocarbon ring include a benzene ring and a naphthalene ring, and a benzene ring is preferable, and a benzene ring substituted with a halogen atom, a halogenated alkyl group, or a halogenated aryl group is more preferable. The halogenated alkyl group is an alkyl group substituted with a halogen atom, and a fluorinated alkyl group (for example, a trifluoromethyl group) is preferable. As the halogenated aryl group, a phenyl group substituted with 1 to 5 halogen atoms is preferable.
The aromatic heterocycle containing oxygen is preferably a furan ring, and the aromatic heterocycle containing sulfur is preferably a thiophene ring. As the aromatic heterocycle containing nitrogen, a pyrrole ring, a pyrazole ring, an imidazole ring and a triazole ring are preferable.
Ring D ^2L is, for example, each ring in which one of the ring constituent atoms of a benzene ring, thiophene ring or furan ring is an anion, or the following formulas (a-1) to (a-5), (a-1a) , (A-2a), (a-1b) and each ring represented by (a-4a) are preferably exemplified.

  In the formula, Rd represents a substituent having no acidic group. b1 represents an integer of 0 to 2, b2 represents an integer of 0 to 3, and b3 represents 0 or 1, respectively. When b1 is 2 or b2 is 2 or more, a plurality of Rd may be the same or different. A plurality of Rd's may be bonded to each other to form a ring. Examples of Rd include a group selected from the substituent group T described later.

  In the formula, Rd and b1 to b3 are synonymous with Rd and b1 to b3 in the above formulas (a-1) to (a-5), and preferred ranges are also the same. b4 represents an integer of 0 to 4, and b5 represents an integer of 0 to 5. In the formulas (a-1a) and (a-1b), Rd represents not only a benzene ring but also a pyrrole ring.

  Rd is preferably a linear or branched alkyl group, cycloalkyl group, alkenyl group, fluoroalkyl group, aryl group, halogen atom, alkoxycarbonyl group, cycloalkoxycarbonyl group, cyano group, alkylsulfonyl group, arylsulfonyl group and A group formed by combining these, more preferably a linear or branched alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, and a group formed by combining these, more preferably a linear or branched alkyl halide. Group, a halogenated aryl group.

As the substituent represented by R ¹¹¹ to R ^143, it has the same meaning as ^{R a} in the formula (DL), and the preferred range is also the same.
At least one of R ^{111 to} R ¹¹⁴ , at least one of R ^{121 to} R ¹²³ , at least one of R ^{131 to} R ¹³³ , and at least one of R ^{141 to} R ¹⁴³ are preferably a substituent, Or it is more preferable that two are substituents.

  When the ligand LD is a tridentate ligand, a tridentate ligand represented by any one of the following formulas (3L-1) to (3L-4) is preferable.

In the formula, * represents a coordination position (bonding position) with the metal ion M. Ring D ^2L represents an aromatic ring. A ^{211 to} A ²⁴² each independently represents a nitrogen atom or a carbon atom. However, at least one of A ²¹¹ and A ²¹² , A ²²¹ and A ²²² , A ²³¹ and A ²³² , and A ²⁴¹ and A ²⁴² is an anion. R ^{211 to} R ²⁴¹ each independently represents a hydrogen atom or a substituent having no acidic group.

What is an anion among A ^{211 to} A ^{242 has} the same meaning as A ^{111 to} A ^{141 in} the above formulas (2L-1) to (2L-4). What does not have an anion among A ²¹¹ -A ²⁴² is a nitrogen atom which does not have a hydrogen atom.
Ring D ^2L in formulas (3L-1) to (3L-4) has the same meaning as ring D ^{2L in} formulas (2L-1) to (2L-4), and the preferred range is also the same. Ring D ^2L is more preferably an aromatic ring containing any one of A ^{211 to} A ^{242 and} a carbon atom or two carbon atoms. At this time, in each formula, two rings ^D2L may be the same or different.
The substituents represented by R ^{211 to} R ²⁴¹ each have the same meaning as R ^a in the above formula (DL), and the preferred range is also the same.
At least one of R ^{211 to} R ²¹³ , at least one of R ²²¹ and R ²²² , at least one of R ²³¹ and R ²³² , and R ²⁴¹ are preferably substituents.

In the present invention, among the bidentate or tridentate ligands in the ligand LD, the atom coordinated to the metal ion M is a nitrogen anion or a carbon anion, and the substituent is a (hetero) arylamino group or divalent. Those having a (hetero) arylamino group are particularly preferred because the absorption becomes longer.
Specifically, the preferable ligand described above is a ligand in which at least one of the atoms coordinated to the metal ion M is a nitrogen anion or a carbon anion, and the partial structure has the following formula (SA): .

In the formula, R ^DA1 represents an aryl group or a heteroaryl group, and R ^DA2 represents an alkyl group, an aryl group, or a heteroaryl group. R ^DA1 and R ^DA2 may be bonded to each other to form a ring. LL represents an ethenyl group, an ethynyl group, an arylene group, or a heteroarylene group. a represents an integer of 0 to 5, and when a is 2 or more, a plurality of LLs may be the same or different.

The group represented by the formula (SA) is preferably substituted with an aromatic hydrocarbon ring coordinated to the metal ion M or an aromatic heterocycle containing nitrogen, and the aromatic heterocycle containing a nitrogen atom More preferably, it is substituted.
Of the groups represented by the formula (SA), at least one of R ^DA1 and R ^DA2 is preferably an aryl group or a heteroaryl group, and more preferably an aryl group. The alkyl group, aryl group, and heteroaryl group may have a substituent, and examples of such a substituent include a group selected from the substituent group T described later.
Although it does not specifically limit as an aryl group, A phenyl group, a naphthyl group, etc. are mentioned, A phenyl group is preferable. Although it does not specifically limit as a heteroaryl group, A furanyl group and a thienyl group are preferable.

LL may form a condensed ring structure together with an aromatic hydrocarbon ring or a nitrogen-containing aromatic heterocycle containing a ligand coordination atom. For example, LL may be an ethenyl group, and this ethenyl group may be bonded to a nitrogen-containing aromatic heterocycle containing a ligand coordination atom to form a quinoline ring.
Examples of the arylene group in LL include a phenylene group and a naphthylene group, and the heteroarylene group is preferably a divalent 5- or 6-membered ring containing an oxygen atom, a sulfur atom, or a nitrogen atom as a ring-constituting atom. And may be condensed with a benzene ring or a hetero ring.
Examples of the hetero ring of the heteroarylene group include a furan ring, a thiophene ring, a pyrrole ring, and a pyridine ring, and a furan ring and a thiophene ring are preferable.

  The ethenyl group, arylene group, and heteroarylene group in LL may have a substituent, and examples of the substituent include a group selected from the substituent group T described later.

  In the above formula (SA), it is preferable that a is 0, or a is 1 and LL is an ethenyl group, ethynyl group, phenylene group or heteroarylene group, and a is 0 or a is 1 and phenylene. Or a heteroarylene group, more preferably a is 0, or a is 1, a phenylene group, a divalent furan ring group, or a divalent thiophene ring group, and a is 0. It is particularly preferred.

In the present invention, those in which R ^DA1 and R ^DA2 are bonded to each other to form a ring are also preferred.
The ring to be formed is preferably a 5- or 6-membered ring, and more preferably bonded when R ^DA1 and R ^DA2 are both aryl groups.
The ring formed by combining R ^DA1 and R ^DA2 with each other is preferably the following ring.

Here, R ^DA3 and R ^DA4 each independently represents an alkyl group.
The ring may have a substituent, and examples of such a substituent include a group selected from the substituent group T described later.

  The ligand represented by the above formula (DL) is disclosed in US Patent Application Publication No. 2010 / 0258175A1, Japanese Patent No. 4298799, Angew. Chem. Int. Ed. 2011, 50, p. It can be synthesized by the method described in 2054-2058, the method described in the references cited in this document, or a method according to these methods.

Specific examples of the ligand represented by the above formula (DL) are shown below. Moreover, the ligand LD in the metal complex pigment | dye mentioned later is also mentioned as ligand LD. The present invention is not limited to these ligands LD. In the following specific examples, Me represents methyl, and * represents a bonding position at which the rings or the pyridine ring and the substituent R ²⁰¹ are bonded to each other.

-Ligand LX-
The ligand LX may be a monodentate ligand and is an acyloxy group, acylthio group, thioacyloxy group, thioacylthio group, acylaminooxy group, thiocarbamate group, dithiocarbamate group, thiocarbonate group, dithiocarbonate. A group selected from the group consisting of a group, trithiocarbonate group, acyl group, thiocyanate group, isothiocyanate group, cyanate group, isocyanate group, cyano group, alkylthio group, arylthio group, alkoxy group, aryloxy group and halogen atom, or Atoms or their anions are preferred.
When the ligand LX contains an alkyl group, an alkenyl group, an alkynyl group, an alkylene group, etc., they may or may not have a substituent. Moreover, when an aryl group, a heterocyclic group, a cycloalkyl group, etc. are included, they may or may not have a substituent, and may be monocyclic or condensed.

  Among them, the ligand LX is preferably a cyanate group, an isocyanate group, a thiocyanate group and an isothiocyanate group or anions thereof, more preferably an isocyanate group (isocyanate anion) or an isothiocyanate (NCS) group (isothiocyanate anion), An isothiocyanate group (isothiocyanate anion) is particularly preferred.

− Charge neutralization counter ion CI −
CI represents a counter ion necessary for neutralizing the charge of the metal complex dye. In general, whether a metal complex dye is a cation or an anion or has a net ionic charge depends on the metal, ligand and substituent in the metal complex dye.
The metal complex dye may be dissociated and have a negative charge because the substituent has a dissociable group. In this case, the entire charge of the metal complex dye is electrically neutralized by CI.

When the counter ion CI is a positive counter ion, for example, the counter ion CI is an inorganic or organic ammonium ion (for example, tetraalkylammonium ion, pyridinium ion, etc.).
Phosphonium ions (for example, tetraalkylphosphonium ions, alkyltriphenylphosphonium ions, etc.), alkali metal ions (Li ions, Na ions, K ions, etc.), alkaline earth metal ions, metal complex ions, or protons. As the positive counter ion, inorganic or organic ammonium ions (tetraethylammonium ion, tetrabutylammonium ion, tetrahexylammonium ion, tetraoctylammonium ion, tetradecylammonium ion, etc.), alkali metal ions, and protons are preferable.

  When the counter ion CI is a negative counter ion, for example, the counter ion CI may be an inorganic anion or an organic anion. For example, hydroxide ion, halogen anion (for example, fluoride ion, chloride ion, bromide ion, iodide ion, etc.), substituted or unsubstituted alkylcarboxylate ion (acetate ion, trifluoroacetate ion, etc.), Substituted or unsubstituted arylcarboxylate ions (benzoate ions, etc.), substituted or unsubstituted alkylsulfonate ions (methanesulfonate ions, trifluoromethanesulfonate ions, etc.), substituted or unsubstituted arylsulfonate ions (for example, p-toluenesulfonate ion, p-chlorobenzenesulfonate ion, etc.), aryl disulfonate ion (for example, 1,3-benzenedisulfonate ion, 1,5-naphthalenedisulfonate ion, 2,6-naphthalenedisulfonate ion, etc.) , Alkyl sulfate ion Such as methyl sulfate ion, etc.), sulfate ion, thiocyanate ion, perchlorate ion, tetrafluoroborate ion, hexafluorophosphate ion, and a picrate ion. Further, as the charge balance counter ion, an ionic polymer or another dye having a charge opposite to that of the dye may be used, and a metal complex ion (for example, bisbenzene-1,2-dithiolatonickel (III)) can also be used. is there. Negative counter ions include halogen anions, substituted or unsubstituted alkyl carboxylate ions, substituted or unsubstituted alkyl sulfonate ions, substituted or unsubstituted aryl sulfonate ions, aryl disulfonate ions, perchlorate ions , Hexafluorophosphate ions are preferred, and halogen anions and hexafluorophosphate ions are more preferred.

− Metal complex dye −
The metal complex dye of the present invention is represented by the following formula (I).

Formula (I) M (LA) (LD) _p (LX) _q · (CI) _z
In the formula, M, LA, LD, p, LX, q, CI and z are as described above, and preferable ones are also the same.

  The metal complex dye represented by the formula (I) is preferably a metal complex dye represented by the following formula (I-1) or (I-2).

In the formula, M and LX have the same meanings as M and LX in the above formula (I).
L ^{1, L} 2, m, ^{R 1} and ^{R 2} are ^{L 1,} L 2, m in the formula (LA-1), ^{R 1} and ^{R 2} synonymous.
Anc1 and Anc2 each independently represent an acidic group. An acidic group is synonymous with the acidic group of a formula (LA-1), and its preferable thing is also the same.
Ring D and ring E each independently represent a 5-membered or 6-membered aromatic ring. D ¹ and D ² each independently represents an anion of a carbon atom or an anion of a nitrogen atom. Here, the bond between D ¹ and D ² in ring D and ring E and the carbon atom bonded to the pyridine ring is a single bond or a double bond. Ring D and ring E have the same meanings as ring D and ring E in the above formulas (DL-1) and (DL-2), and preferred ones are also the same.
R ^{a1 to} R ^a4 each independently represents a substituent. R ^{a1 to} R ^a4 have the same meaning as R ^{a1 to} R ^{a4 in} the above formulas (DL-1) and (DL-2), respectively, and preferred ones are also the same.
ma1, ma2 and ma4 each independently represents an integer of 0 to 3. ma3 represents an integer of 0 to 4. ma1 and ma4 are synonymous with ma1 and ma4 in the above formulas (DL-1) and (DL-2), respectively, and preferred ones are also the same. The preferred range of ma2 and ma3 is the same as the preferred range of ma in the above formula (DL). When each of ma1 to ma4 represents an integer of 2 or more, a plurality of R ^{a1 to} R ^a4 may be bonded to each other to form a ring.

  Examples of the metal complex dye represented by the formula (I) include a method described in JP2013-084594A, a method described in Japanese Patent No. 4298799, US Patent Application Publication No. 2013 / 0018189A1, and US Patent Application Publication. No. 2012 / 0073660A1, U.S. Patent Application Publication No. 2012 / 0111410A1, and U.S. Patent Application Publication No. 2010 / 0258175A1, Angew. Chem. Int. Ed. 2011, 50, p. It can be synthesized by the method described in 2054-2058, the method described in the reference cited in this document, the above-mentioned patent document relating to solar cells, a known method, or a method according thereto.

  In the metal complex dye represented by the formula (I), 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.

Specific examples of the metal complex dye represented by the formula (I) are shown below and in the examples. In addition to the following specific examples and specific examples, metal complex dyes in which at least one of -COOH is a salt of a carboxy group are also included. In this metal complex dye, examples of the counter cation that forms a salt of a carboxy group include positive ions described in the above CI. The present invention is not limited to these metal complex dyes. These metal complex dyes may be any of these isomers or a mixture of these isomers when optical isomers and geometric isomers are present.
The specific examples shown in the following specific examples and examples are independent of the specific combinations of the ligands LA, LD and LX in each specific example. It is shown. In the specific examples, Me represents methyl, Et represents ethyl, and TBA represents tetrabutylammonium.

<Substituent group T>
In the present invention, preferred substituents include groups selected from the following substituent group T. The substituent group T is a substituent group that does not contain the acidic group.
In the present specification, when only described as a substituent, this substituent group T is referred to, and each group, for example, an alkyl group, is only described. The preferred ranges and specific examples in the corresponding group of the substituent group T are applied.
Further includes in this specification, when an alkyl group is stated separately and cycloalkyl groups (e.g., wherein the substituents can take as R ^AA), the alkyl groups are straight chain alkyl groups and branched alkyl groups Used in meaning. On the other hand, when an alkyl group is not described separately from a cycloalkyl group (when simply described as an alkyl group), and unless otherwise specified, an alkyl group is a linear alkyl group or a branched alkyl group And cycloalkyl group. This is because a group containing a group that can take a cyclic structure (alkyl group, alkenyl group, alkynyl group, etc.) (alkoxy group, alkylthio group, alkenyloxy group, etc.) or a group containing a group that can take a cyclic structure (the above alkyl ester). The same applies to chemicals). In the description of the substituent group T below, for example, a straight-chain or branched structure group and a cyclic structure group are clearly described, such as an alkyl group and a cycloalkyl group. Sometimes.

Examples of the group included in the substituent group T include the following groups and groups formed by combining a plurality of the following groups.
An alkyl group (preferably having 1 to 20 carbon atoms such as methyl, ethyl, isopropyl, n-butyl, t-butyl, pentyl, hexyl, heptyl, octyl, 1-ethylpentyl, benzyl, 2-ethoxyethyl, 1-carboxyl. Methyl or trifluoromethyl), an alkenyl group (preferably having 2 to 20 carbon atoms such as vinyl, allyl or oleyl), an alkynyl group (preferably having 2 to 20 carbon atoms such as ethynyl, butynyl or phenylethynyl), A cycloalkyl group (preferably having 3 to 20 carbon atoms such as cyclopropyl, cyclopentyl, cyclohexyl or 4-methylcyclohexyl), a cycloalkenyl group (preferably having 5 to 20 carbon atoms such as cyclopentenyl or cyclohexenyl), aryl Group (aromatic carbonization A cyclic group, preferably having 6 to 26 carbon atoms, such as phenyl, 1-naphthyl, 4-methoxyphenyl, 2-chlorophenyl, 3-methylphenyl, difluorophenyl or tetrafluorophenyl), a heterocyclic group (preferably carbon A 5-membered or 6-membered heterocyclic group having at least one oxygen atom, sulfur atom, or nitrogen atom is more preferable, and the heterocyclic ring includes an aromatic ring and an aliphatic ring. Examples of the heterocyclic group (for example, heteroaryl group) include the following groups, such as 2-pyridyl, 4-pyridyl, 2-imidazolyl, 2-benzimidazolyl, 2-thiazolyl or 2-oxazolyl), an alkoxy group (preferably carbon 1-20, for example, methoxy, ethoxy, isopropyloxy or benzyloxy), alke Ruoxy group (preferably having 2 to 20 carbon atoms, for example, vinyloxy or allyloxy), alkynyloxy group (preferably having 2 to 20 carbon atoms, for example, 2-propynyloxy or 4-butynyloxy), cycloalkyloxy group (preferably Has 3 to 20 carbon atoms, such as cyclopropyloxy, cyclopentyloxy, cyclohexyloxy or 4-methylcyclohexyloxy), an aryloxy group (preferably having 6 to 26 carbon atoms, such as phenoxy, 1-naphthyloxy, 3 -Methylphenoxy or 4-methoxyphenoxy), heterocyclic oxy groups (for example imidazolyloxy, benzimidazolyloxy, thiazolyloxy, benzothiazolyloxy, triazinyloxy or purinyloxy),

An alkoxycarbonyl group (preferably having 2 to 20 carbon atoms such as ethoxycarbonyl or 2-ethylhexyloxycarbonyl), a cycloalkoxycarbonyl group (preferably having 4 to 20 carbon atoms such as cyclopropyloxycarbonyl, cyclopentyloxycarbonyl or Cyclohexyloxycarbonyl), aryloxycarbonyl group (preferably having 6 to 20 carbon atoms, for example, phenyloxycarbonyl or naphthyloxycarbonyl), amino group (preferably having 0 to 20 carbon atoms, alkylamino group, alkenylamino group, Including alkynylamino group, cycloalkylamino group, cycloalkenylamino group, arylamino group, heterocyclic amino group, such as amino, N, N-dimethylamino, N, N-diethylamino, N Ethylamino, N-allylamino, N- (2-propynyl) amino, N-cyclohexylamino, N-cyclohexenylamino, anilino, pyridylamino, imidazolylamino, benzoimidazolylamino, thiazolylamino, benzothiazolylamino or triazinylamino) A sulfamoyl group (preferably an alkyl, cycloalkyl or aryl sulfamoyl group having 0 to 20 carbon atoms, such as N, N-dimethylsulfamoyl, N-cyclohexylsulfamoyl or N-phenylsulfamoyl) An acyl group (preferably having 1 to 20 carbon atoms such as acetyl, cyclohexylcarbonyl or benzoyl), an acyloxy group (preferably having 1 to 20 carbon atoms such as acetyloxy, cyclohexyl Boniruokishi or benzoyloxy), a carbamoyl group (preferably with 1 to 20 carbon atoms, alkyl, a carbamoyl group of the cycloalkyl or aryl Preferably, for example, N, N- dimethylcarbamoyl, N- cyclohexylcarbamoyl or N- phenylcarbamoyl),

An acylamino group (preferably an acylamino group having 1 to 20 carbon atoms, such as acetylamino, cyclohexylcarbonylamino or benzoylamino), a sulfonamide group (preferably an alkyl, cycloalkyl or aryl sulfonamide group having 0 to 20 carbon atoms) For example, methanesulfonamide, benzenesulfonamide, N-methylmethanesulfonamide, N-cyclohexylsulfonamide or N-ethylbenzenesulfonamide), an alkylthio group (preferably having 1 to 20 carbon atoms such as methylthio, ethylthio). , Isopropylthio, pentylthio or benzylthio), a cycloalkylthio group (preferably having 3 to 20 carbon atoms, such as cyclopropylthio, cyclopentylthio, cyclohexylthio or 4 Methylcyclohexylthio), arylthio groups (preferably having 6 to 26 carbon atoms, such as phenylthio, 1-naphthylthio, 3-methylphenylthio or 4-methoxyphenylthio), alkyl, cycloalkyl or arylsulfonyl groups (preferably carbon In formulas 1 to 20, for example, methylsulfonyl, ethylsulfonyl, cyclohexylsulfonyl or benzenesulfonyl),

A silyl group (preferably a silyl group having 1 to 20 carbon atoms and substituted with alkyl, aryl, alkoxy and aryloxy is preferable, for example, trimethylsilyl, triethylsilyl, triisopropylsilyl, triphenylsilyl, diethylbenzylsilyl or dimethylphenylsilyl. ), Silyloxy groups (preferably silyloxy groups having 1 to 20 carbon atoms and substituted by alkyl, aryl, alkoxy and aryloxy, such as triethylsilyloxy, triphenylsilyloxy, diethylbenzylsilyloxy or dimethylphenylsilyloxy) ), 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 group 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, alkylthio group, cycloalkylthio group, arylthio group. , Alkoxycarbonyl group, cycloalkoxycarbonyl group, amino group, acylamino group, cyano group or halogen atom, particularly preferably alkyl group, alkenyl group, heterocyclic group, alkoxy group, alkylthio group, alkoxycarbonyl group, amino group, An acylamino group or a cyano group is mentioned.

  When a compound or a substituent includes an alkyl group, an alkenyl group, etc., these may be substituted or unsubstituted. When an aryl group, a heterocyclic group, or the like is included, they may be monocyclic or condensed, and may be substituted or unsubstituted.

  Next, the preferable aspect of the main member of a photoelectric conversion element and a dye-sensitized solar cell is demonstrated with reference to FIG. 1 and FIG.

<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 includes the conductive support 1 made of a conductive material, for example, a metal, or a glass or plastic substrate 44 and a transparent conductive film 43 formed on the surface of the substrate 44. A conductive support 41 is preferred.

Among these, the conductive support 41 in which a conductive metal oxide is coated on the surface of the substrate 44 to form a transparent conductive film 43 is more preferable. 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, the material for forming the substrate 44 may be ceramic (Japanese Patent Laid-Open No. 2005-135902) or conductive resin (Japanese Patent Laid-Open No. 2001-160425). 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.

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, but 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 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.

  The crystal structure of titania includes anatase type, brookite type, or 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 size of the semiconductor fine particles 22 is 0.001 to 1 μm as the primary particle in terms of the average particle size when the projected area is converted into a circle, and 0.01 to 100 μm as the average particle size of the dispersion. Is preferred. Examples of a 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 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. Although there is no restriction | limiting in particular in this upper limit, Usually, it is about 5000 times. In general, the larger the thickness of the semiconductor layer 45 (synonymous with the photoreceptor layer 2 in the photoelectric conversion element 10) formed by the semiconductor fine particles 22, the greater the amount of the dye 21 that can be carried per unit area, and the higher the light absorption efficiency. However, since the diffusion distance of the generated electrons increases, the loss due to charge recombination also increases.

  In the photoelectric conversion element and the dye-sensitized solar cell as described above, the shorter the diffusion distance of the excited electrons, the higher the electron transport efficiency can be expected. However, if the thickness of the semiconductor layer is reduced, the photoelectric conversion efficiency may be lowered. The photoelectric conversion element and the dye-sensitized solar cell of the present invention have the metal complex dye of the present invention using the ligand LA and preferably the ligand LD. Thereby, both when the semiconductor layer has the conventional thickness and when the semiconductor layer is thinner than the conventional thickness, excellent photoelectric conversion efficiency is exhibited. Thus, according to this invention, the influence of the film thickness of a semiconductor layer is small, and the outstanding photoelectric conversion efficiency is exhibited.

The preferred thickness of the semiconductor layer 45 (photosensitive layer 2 in the photoelectric conversion element 10) is not uniquely determined depending on the use of the photoelectric conversion element, but is typically 0.1 to 100 μm. When using as a dye-sensitized solar cell, 1-50 micrometers is more preferable and 3-30 micrometers is more preferable.
In the present invention, since the metal complex dye represented by the above formula (I) is used, the thickness of the semiconductor layer 45 can be reduced. For example, within the above preferable range, it can be 8 μm or less, and further 6 μm or less.

  The semiconductor fine particles 22 are preferably applied to the conductive support 1 or 41 and then baked at a temperature of 100 to 800 ° C. for 10 minutes to 10 hours to bring the particles into close contact with each other. 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.

The coating amount of the semiconductor fine particles 22 per 1 m ² of the surface area of the conductive support 1 or 41 is preferably 0.5 to 500 g, more preferably 5 to 100 g.

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) or a separator.

− Dye −
In the photoelectric conversion element 10 and the dye-sensitized solar cell 20, at least one metal complex dye represented by the above formula (I) is used as a sensitizing dye. The metal complex dye represented by the formula (I) is as described above.

  In the present invention, examples of the dye that can be used in combination with the metal complex dye of the above formula (I) include a Ru complex dye, a squarylium cyanine dye, an organic dye, a porphyrin dye, and a phthalocyanine dye.

  Examples of the Ru complex dye include Ru complex dyes described in JP-A-7-500630 (especially synthesized in Examples 1 to 19 on page 5, lower left column, line 5 to page 7, upper right column, line 7). Dyes), Ru complex dyes described in JP-T-2002-512729 (especially dyes synthesized in Examples 1 to 16 on the third line to the 29th page and the 23rd line from the bottom of page 20), JP, Ru complex dyes described in 2001-59062 (especially dyes described in paragraphs 0087 to 0104), Ru complex dyes described in JP-A-2001-6760 (particularly dyes described in paragraphs 0093 to 0102) ), Ru complex dyes described in JP-A No. 2001-253894 (particularly dyes described in paragraph Nos. 0009 to 0010), Ru complex dyes described in JP-A No. 2003-212851 (particularly in paragraph No. 0005) Dyes), Ru complex dyes described in International Publication No. 2007/91525 (particularly dyes described in [0067]), Ru complex dyes described in Japanese Patent Application Laid-Open No. 2001-291534 (particularly, paragraphs 0120- 0144), Ru complex dyes described in JP2012-012570A (particularly dyes described in paragraphs 0095 to 0103), Ru metal complex dyes described in JP2013-084594A (particularly, , Dyes described in paragraphs 0072 to 0081, etc.), Ru complex dyes described in International Publication No. 2013/088888 (particularly, dyes described in [0286] to [0293]), or International Publication Nos. 2013/47615. Ru complex dyes described in No. (especially, the dyes described in [0078] to [0082]).

  As the squarylium cyanine dye, for example, squarylium cyanine dye described in JP-A-11-214730 (particularly the dye described in paragraphs 0036 to 0047), squarylium cyanine dye described in JP2012-144688 (particularly, And dyes described in paragraph numbers 0039 to 0046 and paragraphs 0054 to 0060) or squarylium cyanine dyes described in JP 2012-84503 A (in particular, dyes described in paragraph numbers 0066 to 0076 and the like). .

  Examples of the organic dye include organic dyes described in JP-A-2004-063274 (particularly dyes described in paragraph numbers 0017 to 0021), organic dyes described in JP-A-2005-123033 (particularly paragraph numbers). 0021 to 0028), organic dyes described in JP-A-2007-287694 (particularly dyes described in paragraphs 0091 to 0096), organic dyes described in JP-A-2008-71648 (particularly, And dyes described in Paragraph Nos. 0030 to 0034) or organic dyes described in International Publication No. 2007/119525 (particularly, the dye described in [0024]).

  Examples of porphyrin dyes include Angew. Chem. Int. Ed. 49, p. 1-5 (2010) etc., and phthalocyanine dyes include, for example, Angew. Chem. Int. Ed. 46, p. 8358 (2007) and the like.

  The dye that can be used in combination is preferably a Ru complex dye, a squarylium cyanine dye, or an organic dye.

The total amount of the dye used is preferably 0.01 to 100 mmol, more preferably 0.1 to 50 mmol, particularly preferably 0.1 to 10 mmol per 1 m ² of the surface area of the conductive support 1 or 41. is there. Further, the adsorption amount of the dye 21 to the semiconductor fine particles 22 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 22. By using such a dye amount, the sensitizing effect in the semiconductor fine particles 22 can be sufficiently obtained.

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

  After the dye is supported on the semiconductor fine particles 22, the surface of the semiconductor fine particles 22 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.

− Coadsorbent −
In the present invention, it is preferable to use a coadsorbent together with the metal complex dye represented by the formula (I) or a dye used in combination as 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 is cholic acid.

  A preferred co-adsorbent is a compound represented by the following formula (CA).

In the formula, R ^A1 represents a substituent having an acidic group. R ^A2 represents a substituent. nA represents an integer of 0 or more.
An acidic group is synonymous with the acidic group in said formula (LA-1), and its preferable range is also the same.
Among these, R ^A1 is preferably a carboxy group or a sulfo group or an alkyl group substituted with a salt thereof, —CH (CH ₃ ) CH ₂ CH ₂ CO ₂ H, —CH (CH ₃ ) CH ₂ CH _2. More preferred is CONHCH ₂ CH ₂ SO ₃ H.

Examples of R ^A2 include a group selected from the above substituent group T. Of these, an alkyl group, a hydroxy group, an acyloxy group, an alkylaminocarbonyloxy group or an arylaminocarbonyloxy group is preferable, and an alkyl group, a hydroxy group or an acyloxy group is more preferable.
nA is preferably from 2 to 4.

  The co-adsorbent has an effect of suppressing inefficient association of the metal complex dye and an effect of preventing reverse electron transfer from the surface of the semiconductor fine particles to the redox system in the electrolyte by being adsorbed on the semiconductor fine particles 22. Although the usage-amount of a coadsorbent is not specifically limited, From a viewpoint of expressing said effect | action effectively, Preferably it is 1-200 mol with respect to 1 mol of said metal complex pigment | dyes, More preferably, it is 10-150 mol, Most preferably, it is 20-50 mol.

− Light scattering layer −
In the present invention, the light scattering layer is different from the semiconductor layer 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 particles. Examples of the metal oxide particles used in the light scattering layer 46 include the metal chalcogenide (oxide) 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-2002-289274, and the description of JP-A-2002-289274 is preferably incorporated in the present specification as it is.

<Charge transfer layer>
The charge transfer body layers 3 and 47 used in the photoelectric conversion element of the present invention 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. It is done.
The charge transfer layer 3 and 47 contains an electrolyte. Here, “the charge transfer layer contains an electrolyte” means to include both modes of the mode in which the charge transfer layer is made of only an electrolyte and the mode containing an electrolyte and a substance other than the electrolyte.
The charge transfer body layers 3 and 47 may be solid, liquid, gel, or a mixed state thereof.

− Electrolyte −
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 the description of paragraphs 0144 to 0156 of JP2014-82189A is described below. 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, but 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.

  Molten salts include ionic liquids containing imidazolium or triazolium cations, ionic liquids containing oxazolium cations, ionic liquids containing pyridinium cations, ionic liquids containing guanidinium cations, and these A combination is preferred. Moreover, you may combine a specific anion with respect to these cations. Additives may be added to these molten salts. The molten salt may have a liquid crystalline substituent. Moreover, the molten salt of a quaternary ammonium salt can also be used as the molten salt.

  As molten salts other than these, for example, flowability at room temperature was imparted by mixing polyethylene oxide with lithium iodide and at least one other lithium salt (for example, lithium acetate, lithium perchlorate, etc.). And the like. In this case, the amount of the polymer added is 1 to 50% by mass. Moreover, (gamma) -butyrolactone may be contained in electrolyte solution, and thereby the diffusion efficiency of iodide ion becomes high and photoelectric conversion efficiency improves.

  Examples of the polymer (polymer matrix) used in the gel electrolyte matrix include polyacrylonitrile and polyvinylidene fluoride.

  The electrolyte may be quasi-solidified by adding a gelling agent to an electrolyte solution composed of an electrolyte and a solvent to cause gelation (hereinafter, the quasi-solid electrolyte is also referred to as “pseudo-solid electrolyte”). Examples of the gelling agent include organic compounds having a molecular weight of 1000 or less, Si-containing compounds having a molecular weight in the range of 500 to 5000, organic salts made of a specific acidic compound and a basic compound, sorbitol derivatives, and polyvinylpyridine.

Alternatively, a method of confining a polymer matrix, a crosslinkable polymer compound or monomer, a crosslinking agent, an electrolyte, and a solvent in the polymer may be used.
The polymer matrix is preferably a polymer having a nitrogen-containing heterocycle in the main chain or side chain repeating unit, a cross-linked product obtained by reacting these with an electrophilic compound, a polymer having a triazine structure, or a polymer having a ureido structure. Molecules, compounds containing liquid crystal compounds, polymers having an ether bond, polyvinylidene fluoride, methacrylates, acrylates, thermosetting resins, crosslinked polysiloxanes, polyvinyl alcohol (PVA), inclusion compounds such as polyalkylene glycols and dextrins, Examples include systems to which oxygen-containing or sulfur-containing polymers are added, natural polymers, and the like. An alkali swelling polymer, a polymer having a compound capable of forming a charge transfer complex of a cation moiety and iodine in one polymer, and the like may be added to these.

  As the polymer matrix, a system including a crosslinked polymer obtained by reacting a bifunctional or higher functional isocyanate group with a functional group such as a hydroxy group, an amino group, or a carboxy group may be used. In addition, a crosslinking method in which a crosslinked polymer composed of a hydrosilyl group and a double bond compound, polysulfonic acid, polycarboxylic acid, or the like is reacted with a divalent or higher valent metal ion compound may be used.

  Examples of the solvent that can be preferably used in combination with the quasi-solid electrolyte include a specific phosphate ester, a mixed solvent containing ethylene carbonate, and a solvent having a specific dielectric constant. The liquid electrolyte solution may be held in the solid electrolyte membrane or the pores. A preferred method for holding the liquid electrolyte solution is a method using a cloth-like solid such as a conductive polymer film, a fibrous solid, or a filter.

  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) 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 liquid electrolyte and quasi-solid electrolyte, a solid charge transport layer such as a p-type semiconductor or a hole transport material, for example, CuI, CuNCS, or the like 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 layer. The organic hole transport material is preferably a conductive polymer such as polythiophene, polyaniline, polypyrrole or polysilane, and a spiro compound in which two rings share a central element such as C or Si and a tetrahedral structure, an aromatic such as triarylamine Group amine derivatives, triphenylene derivatives, nitrogen-containing heterocyclic derivatives, and liquid crystalline cyano derivatives.

  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, but 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. As the structure of the counter electrodes 4 and 48, a structure having a high current collecting effect is preferable. 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, the conductive support 1 or 41 is preferably transparent, and sunlight is preferably 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, a glass or plastic on which a metal or conductive oxide is vapor-deposited is preferable, and a glass on which platinum is vapor-deposited is particularly preferable. In the dye-sensitized solar cell, it is preferable to seal the side surface of the battery with a polymer, an adhesive or the like in order to prevent the constituents from evaporating.

  The present invention includes, for example, Japanese Patent No. 4260494, Japanese Patent Application Laid-Open No. 2004-146425, Japanese Patent Application Laid-Open No. 2000-340269, Japanese Patent Application Laid-Open No. 2002-289274, Japanese Patent Application Laid-Open No. 2004-152613, and Japanese Patent Application Laid-Open No. 9-27352. It can be applied to the photoelectric conversion element and the dye-sensitized solar cell described in the publication. JP-A-2004-152613, JP-A-2000-90989, JP-A-2003-217688, JP-A-2002-367686, JP-A-2003-323818, JP-A-2001-43907, JP 2000-340269, JP 2005-85500, JP 2004-273272, JP 2000-323190, JP 2000-228234, JP 2001-266963, JP 2001-185244, JP-T-2001-525108, JP-A-2001-203377, JP-A-2000-1000048, JP-A-2001-210390, JP-A-2002-280588, JP-A-2001-2001. 273937, JP-A 2000-285 77 No. photoelectric conversion device described in JP-A-2001-320068, can be applied to a dye-sensitized solar cell.

[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 (the dye solution of the present invention) containing the metal complex dye of the present invention and a solvent.

  In such a dye solution, the metal complex dye of the present invention is dissolved in a solvent and may contain a co-adsorbent and other components as necessary.

  Examples of the solvent to be used include the solvents described in JP-A No. 2001-291534, but are not particularly limited thereto. In the present invention, an organic solvent is preferable, and an alcohol solvent, an amide solvent, a nitrile 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, or 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, a mixed solvent of an alcohol solvent and a nitrile solvent, and particularly preferably a mixed solvent of an alcohol solvent and an amide solvent, an alcohol solvent and a nitrile solvent. It is a mixed solvent. Specifically, a mixed solvent of at least one of methanol, ethanol, propanol and t-butanol and at least one of dimethylformamide and dimethylacetamide, at least one of methanol, ethanol, propanol and t-butanol, and acetonitrile The mixed solvent is preferable.

The dye solution preferably contains a co-adsorbent. As the co-adsorbent, the above-mentioned co-adsorbent is preferable, and among them, the compound represented by the above formula (CA) is preferable.
Here, the dye solution of the present invention is a dye solution in which the concentration of the metal complex dye or coadsorbent is adjusted so that the solution can be used as it is when producing a photoelectric conversion element or a dye-sensitized solar cell. Is preferred. In the present invention, the dye solution of the present invention preferably contains 0.001 to 0.1% by mass of the metal complex dye of the present invention. The amount of coadsorbent used is as described above.

  The pigment solution preferably adjusts the water content. In the present invention, the water content is preferably adjusted to 0 to 0.1% by mass.

In the present invention, the photoreceptor layer is preferably prepared by supporting the metal complex dye represented by the formula (I) 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 dip method) to semiconductor fine particles provided on a conductive support, and drying or curing.
The photoelectric conversion element or the dye-sensitized solar cell of the present invention can be obtained by further providing a charge transfer layer, a counter electrode, and the like on the light-receiving electrode provided with the photoreceptor layer thus prepared.

  The dye-sensitized solar cell is 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.

Below, the synthesis | combining method of the metal complex dye of this invention is demonstrated.
In this specification, room temperature means 25 degreeC. Me represents methyl and TBA represents tetrabutylammonium.
The metal complex dye and synthetic intermediate synthesized in Example 1 were identified by MS (mass spectrum) measurement.
Since the synthesized TBA salt of the metal complex dye is protonated and has the same mass as the electrically neutral metal complex dye in the MS measurement, the result of the MS measurement is omitted for the TBA salt.

Example 1 (Synthesis of metal complex dye)
The metal complex dyes (D-1) to (D-16) synthesized in this example are shown below.

(Synthesis of Metal Complex Dye (D-1) and Metal Complex Dye (D-1TBA))
A metal complex dye (D-1) and a metal complex dye (D-1TBA) were synthesized according to the following scheme.

(I) Synthesis of Compound (1-2) Compound (1-1), diphenylamine, and t-butoxy sodium were added to toluene (300 mL), and deaeration was repeated by repeating reduced pressure (vacuum) and nitrogen gas replacement. Palladium acetate and tri (t-butyl) phosphine were added thereto, and the resulting mixture was heated and reacted for 2 hours under reflux. Thereafter, the reaction mixture was allowed to cool and a saturated aqueous ammonium chloride solution was added to extract the reaction product. The organic phase was washed with saturated brine and dried over magnesium sulfate. Magnesium sulfate was filtered, and the filtrate was concentrated to obtain a crude product. The resulting crude product was purified by silica gel column chromatography to obtain compound (1-2).

(Ii) Synthesis of Compound (1-5) A solution obtained by dissolving Compound (1-2) in THF (tetrahydrofuran, 30 mL) was cooled to −78 ° C., and n-butyllithium (1.6 M hexane solution, 8.1 mL) was added dropwise. Thereafter, the temperature was raised to 0 ° C., the compound (1-2) and n-butyllithium were reacted at 0 ° C. for 1 hour, and then the compound (1-3) was added dropwise to the reaction solution at 0 ° C. The resulting liquid was further stirred at 0 ° C. for 1 hour, and then a saturated aqueous ammonium chloride solution was added. The reaction product was extracted with ethyl acetate, and the organic phase was washed with saturated brine and dried over magnesium sulfate. Magnesium sulfate was filtered, and the filtrate was concentrated to obtain compound (1-4).
Subsequently, the obtained compound (1-4), 2-chloro-4-iodopyridine and potassium carbonate were added to THF / H ₂ O (9: 1), and degassed by bubbling nitrogen gas. Palladium acetate and SPhos (2-dicyclohexylphosphino-2 ′, 6′-dimethoxybiphenyl) were added thereto, and the mixture was heated and reacted for 10 hours under reflux. Thereafter, the reaction mixture was allowed to cool, and water and ethyl acetate were added to extract the reaction product. The organic phase was washed with saturated brine and dried over magnesium sulfate. Magnesium sulfate was filtered, and the filtrate was concentrated to obtain a crude product. The resulting crude product was purified by silica gel column chromatography to obtain compound (1-5).
Compound (1-5) was confirmed from the following data.
MS (ESI ^<+> ) m / z: 349 ([M + H] ^< +>)

(Iii) Synthesis of Compound (1-7) Compound (1-5) and hexamethyldistin were added to toluene, and deaeration was repeated by repeating reduced pressure (vacuum) and nitrogen gas replacement. Tetrakis (triphenylphosphine) palladium (0) was added thereto, and the mixture was heated and reacted for 8 hours under reflux. Compound (1-6) was added to the obtained liquid, and the mixture was further reacted under reflux for 3 hours. The resulting reaction mixture was allowed to cool and then concentrated, and the concentrated residue was purified by silica gel column chromatography to obtain a compound (1-7) which is a diethyl esterified product of a terpyridine compound.
Compound (1-7) was confirmed from the following data.
MS (ESI ^<+> ) m / z: 611 ([M + H] ^< +>)

(Iv) Synthesis of Compound (1-8) Compound (1-7) and ruthenium trichloride trihydrate were added to ethanol, and the mixture was reacted under reflux for 4 hours. The reaction mixture was allowed to cool, and the precipitate was collected by filtration and washed with ethanol to give compound (1-8). The obtained compound (1-8) was used for the next reaction without purification.

(V) Synthesis of Compound (1-10) Compound (1-8) and compound (1-9) were added to DMF (N, N-dimethylformamide), and the mixture was reacted under reflux for 3 hours. The reaction mixture was allowed to cool and then concentrated, and the concentrated residue was purified by silica gel column chromatography (eluent: chloroform) to give compound (1-10).
Compound (1-10) was confirmed from the following data.
MS (ESI ^<+> ) m / z: 1126 ([M + H] ^< +>)

(Vi) Synthesis of Compound (1-11) Compound (1-10) and ammonium thiocyanate were added to DMF, and the mixture was reacted at 120 ° C. for 6 hours. The reaction mixture was allowed to cool and then concentrated, and the concentrated residue was purified by silica gel column chromatography to obtain compound (1-11).
Compound (1-11) was confirmed from the following data.
MS (ESI ^<+> ) m / z: 1149 ([M + H] ^< +>)

(Vii) Synthesis of Metal Complex Dye (D-1) Compound (1-11) was added to DMF, and 3M aqueous sodium hydroxide solution was added dropwise thereto. After the mixture was reacted at room temperature for 30 minutes, 1M (mol / L) trifluoromethanesulfonic acid methanol solution was added to the mixture to adjust to acidic (pH = 2.5). Water was added to the obtained liquid, and the precipitated solid was collected by filtration, washed with water, and then vacuum dried to obtain a metal complex dye (D-1).
The metal complex dye (D-1) was confirmed from the following data.
MS (ESI ^<+> ) m / z: 1093 ([M + H] ^< +>)

(Viii) Synthesis of metal complex dye (D-1TBA) In a recovery flask, a metal complex dye (D-1, 109 mg, 0.10 mmol) and a 10% MeOH solution of tetrabutylammonium hydroxide (TBAOH) (25.9 mg) , 0.10 mmol) and allowed to react at room temperature. The obtained reaction solution was concentrated to obtain a metal complex dye (D-1TBA, 133 mg).

(Synthesis of metal complex dyes (D-2) to (D-16) and metal complex dyes (D-2TBA) to (D-16TBA))
The metal complex dyes (D-2) to (D-16) were synthesized in the same manner as the metal complex dye (D-1), except that the compound used was changed. That is, in the above-described method for synthesizing a metal complex dye (the above scheme), each of compound (1-1), compound (1-2), diphenylamine and compound (1-9) is compatible with the metal complex dye for synthesis. The metal complex dyes (D-2) to (D-16) were synthesized in the same manner as in the metal complex dye (D-1) except that the change was made to.
Further, the metal complex dyes (D-8) and (D-9) were synthesized without performing a reaction for introducing the NCS group. Further, the metal complex dye (D-15) was synthesized by directly converting the compound corresponding to the compound (1-8) to NCS.
Each of the metal complex dyes (D-2TBA) to (D-16TBA) has an amount of TBAOH in such an amount that the molar ratio of the metal complex dyes (D-2) to (D-16) and TBAOH is 1: 1. It was synthesized in the same manner as the metal complex dye (D-1TBA) using a 10% MeOH solution.

(Identification of metal complex dyes (D-2) to (D-16) and metal complex dyes (D-2TBA) to (D-16TBA))
The synthesized metal complex dyes (D-2) to (D-16) were confirmed from the following data.
Metal Complex Dye (D-2) MS (ESI ⁺ ) m / z: 1106 ([M + H] ⁺ )
Metal Complex Dye (D-3) MS (ESI ⁺ ) m / z: 1103 ([M + H] ⁺ )
Metal Complex Dye (D-4) MS (ESI ⁺ ) m / z: 1219 ([M + H] ⁺ )
Metal Complex Dye (D-5) MS (ESI ⁺ ) m / z: 1153 ([M + H] ⁺ )
Metal Complex Dye (D-6) MS (ESI ⁺ ) m / z: 1310 ([M + H] ⁺ )
Metal Complex Dye (D-7) MS (ESI ⁺ ) m / z: 1055 ([M + H] ⁺ )
Metal Complex Dye (D-8) MS (ESI ⁺ ) m / z: 1278 ([M + H] ⁺ )
Metal Complex Dye (D-9) MS (ESI ⁺ ) m / z: 1262 ([M + H] ⁺ )
Metal Complex Dye (D-10) MS (ESI ⁺ ) m / z: 1123 ([M + H] ⁺ )
Metal Complex Dye (D-11) MS (ESI ⁺ ) m / z: 1171 ([M + H] ⁺ )
Metal Complex Dye (D-12) MS (ESI ⁺ ) m / z: 1172 ([M + H] ⁺ )
Metal Complex Dye (D-13) MS (ESI ⁺ ) m / z: 1197 ([M + H] ⁺ )
Metal Complex Dye (D-14) MS (ESI ⁺ ) m / z: 1009 ([M + H] ⁺ )
Metal Complex Dye (D-15) MS (ESI ⁺ ) m / z: 841 ([M + H] ⁺ )
Metal Complex Dye (D-16) MS (ESI ⁺ ) m / z: 1143 ([M + H] ⁺ )

Example 2 (Production of dye-sensitized solar cell)
Using the metal complex dyes (D-1) to (D-16) and (D-1TBA) to (D-16TBA) synthesized in Example 1 or the following comparative compounds (C-1) to (C-3), respectively. Thus, the dye-sensitized solar cell 20 (5 mm × 5 mm scale) shown in FIG. 2 was manufactured. Manufacture was performed according to the following procedure. The following performance of each of the produced dye-sensitized solar cells 20 was evaluated. The results are shown in Table 1.

(Preparation of light receiving electrode precursor [A])
A fluorine-doped SnO ₂ conductive film (transparent conductive film 43, film thickness: 500 nm) was formed on a glass substrate (substrate 44, thickness 4 mm) to produce a conductive support 41. Then, the SnO ₂ conductive film, titania paste "18NR-T" a (Dyesol Inc.) was screen-printed, dried at 120 ° C.. Next, the titania paste “18NR-T” was screen-printed again and dried at 120 ° C. for 1 hour. Thereafter, the dried titania paste was baked in air at 500 ° C. to form a semiconductor layer 45 (layer thickness: 10 μm). 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. Thereafter, the dried titania paste was baked at 500 ° C., and a light scattering layer 46 (layer thickness: 5 μm) was formed on the semiconductor layer 45.
In this way, the photoreceptor layer 42 (light receiving surface area: 5 mm × 5 mm, layer thickness: 15 μm, metal complex dye not supported) is formed on the SnO ₂ conductive film, and the metal complex dye is not supported. A light receiving electrode precursor [A] was prepared.

(Preparation of light receiving electrode precursor [B])
A fluorine-doped SnO ₂ conductive film (transparent conductive film 43, film thickness: 500 nm) was formed on a glass substrate (substrate 44, thickness 4 mm) to produce a conductive support 41. Then, the SnO ₂ conductive film, titania paste "18NR-T" a (Dyesol Inc.) was screen-printed, dried at 120 ° C.. Thereafter, the dried titania paste was baked in air at 500 ° C. to form a semiconductor layer 45 (light receiving surface area; 5 mm × 5 mm, layer thickness; 6 μm).
Thus, on the SnO ₂ conductive film, a photoreceptor layer 42 (light receiving surface area: 5 mm × 5 mm, layer thickness: 6 μm, metal complex dye not supported) without the light scattering layer 46 is formed, A light receiving electrode precursor [B] carrying no metal complex dye was prepared.

(Dye adsorption)
Next, each of the metal complex dyes ((D-1) to (D-16) and (D-1TBA) to (D-16TBA) synthesized in Example 1 on the photoreceptor layer 42 that does not carry the metal complex dye. ) Was supported as follows. First, each of the above metal complex dyes 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, 30 mol of cholic acid was added to 1 mol of the metal complex dye to prepare each dye solution. Next, the light receiving electrode precursor [A] was immersed in each dye solution at 25 ° C. for 20 hours, pulled up from the dye solution, and then dried.
In this way, each of the light receiving electrodes 40 in which each metal complex dye was supported on the light receiving electrode precursor [A] was produced.

  Similarly, each metal complex dye was supported on the light receiving electrode precursor [B], and light receiving electrodes 40 each having the metal complex dye supported on the light receiving electrode precursor [B] were 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. Moreover, iodine 0.1M (mol / L), lithium iodide 0.1M, 4-t-butylpyridine 0.5M, and 1,2-dimethyl-3-propylimidazolium iodide 0.6M were used as electrolyte solution. A liquid electrolyte was prepared by dissolving in acetonitrile. Further, a spacer S “Surlin” (trade name, manufactured by DuPont) having a shape matched 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 produced and the electrolyte injection port were sealed and cured using Resin XNR-5516 (manufactured by Nagase Chemtech), and each dye-sensitized solar cell (sample numbers 1 to 16) was Manufactured.

The dye-sensitized solar cells of the respective sample numbers produced as described above are those using electrically neutral metal complex dyes (D-1 to D-16) and TBA salt metal complex dyes (D -1 TBA to D-16 TBA).
Moreover, in the dye-sensitized solar cell of each sample number, the dye-sensitized solar cell using an electrically neutral metal complex dye is a dye-sensitized solar cell manufactured using the light-receiving electrode precursor [A] ( 2) including a sample number “A”) and a dye-sensitized solar cell manufactured using the light receiving electrode precursor [B] (a sample number “B” may be added). .
Similarly, a dye-sensitized solar cell using a metal complex dye of a TBA salt was manufactured using a dye-sensitized solar cell manufactured using a light-receiving electrode precursor [A] and a light-receiving electrode precursor [B]. Includes two types of dye-sensitized solar cells.

For comparison, in the production of the dye-sensitized solar cell, the dyes described above were used except that the following metal complex dyes (C-1) to (C-3) were used instead of the metal complex dyes synthesized in Example 1. Dye-sensitized solar cells (sample numbers c1 to c3) were manufactured in the same manner as the sensitized solar cells.
The metal complex dye (C-1) is the compound “Dye108” described in Patent Document 1. The metal complex dye (C-2) is an electrically neutral metal complex dye of the compound “A-4” described in Patent Document 3. The metal complex dye (C-3) is the compound “D-40” described in Patent Document 4.

<Test of photoelectric conversion efficiency>
A battery characteristic test was performed using each of the produced dye-sensitized solar cells. The battery characteristic test was performed by using a solar simulator (WXS-85H, manufactured by WACOM) and irradiating 1000 W / m ² of pseudo-sunlight from a xenon lamp through an AM1.5 filter. The current-voltage characteristics were measured using an IV tester to determine the photoelectric conversion efficiency.

(Conversion efficiency (A))
For each of the dye-sensitized solar cells (sample numbers 1A to 16A and c1A to c3A) manufactured using the light-receiving electrode precursor [A] among the dye-sensitized solar cells of the respective sample numbers, photoelectric conversion is performed as described above. Efficiency was measured (referred to as conversion efficiency (A)). The measured conversion efficiency (A) was evaluated. The evaluation was based on the conversion efficiency (S _A ) of the dye-sensitized solar cell (sample number c1A) produced using the light receiving electrode precursor [A].
In the evaluation criteria for the conversion efficiency (A), “A” and “B” are acceptable levels of this test, and preferably “A”. On the other hand, “C” and “D” have insufficient conversion efficiency and do not reach the pass level (required level) of the present invention.
(Evaluation criteria for conversion efficiency (A))
Conversion efficiency (A) is compared to conversion efficiency (S _A )
A: More than 1.2 times B: More than 1.1 times and less than 1.2 times C: More than 1.0 times and less than 1.1 times D: Less than 1.0 times

(Conversion efficiency (B))
For each of the dye-sensitized solar cells (sample numbers 1B to 16B and c1B to c3B) manufactured using the light-receiving electrode precursor [B] among the dye-sensitized solar cells of the respective sample numbers, Conversion efficiency was measured (referred to as conversion efficiency (B)). The measured conversion efficiency (B) was evaluated. The evaluation was based on the conversion efficiency (S _A ) of the dye-sensitized solar cell (sample number c1A) produced using the light receiving electrode precursor [A].
In the evaluation criteria for the conversion efficiency (B), “A” and “B” are acceptable levels of this test, and preferably “A”. On the other hand, “C” and “D” have insufficient conversion efficiency and do not reach the pass level (required level) of the present invention.
(Evaluation criteria for conversion efficiency (B))
Conversion efficiency (B) is compared to conversion efficiency (S _A )
A: More than 1.1 times B: More than 1.0 times, 1.1 times or less C: More than 0.9 times, 1.0 times or less D: 0.9 times or less

<Durability evaluation>
Dye-sensitized solar cells (sample numbers 1A to 16A and c1A to c3A) manufactured using the light-receiving electrode precursor [A] among the dye-sensitized solar cells of the respective sample numbers were used for durability (thermal deterioration). A heat cycle test was performed as an evaluation.
Each dye-sensitized solar cell was alternately put into a −10 ° C. freezer and a 50 ° C. thermostat every 12 hours, and cooling and heating were repeated (heat cycle test). The current was measured for each of the dye-sensitized solar cell before the heat cycle test and the dye-sensitized solar cell after 72 hours of the heat cycle test. The current value (short-circuit current density) obtained from the current-voltage characteristic measurement in the dye-sensitized solar cell 72 hours after the heat cycle test was measured in the dye-sensitized solar cell before the heat cycle test (short-circuit current density). Divided by. This value was defined as the current retention rate. The durability was evaluated based on the following criteria based on the current retention ratio thus obtained.
In the durability evaluation criteria, “A” and “B” are acceptable levels of this test, and preferably “A”. On the other hand, “C” and “D” have insufficient current holding ratios and do not reach the pass (required level) of the present invention.
A: 0.9 times or more B: Less than 0.9 times, 0.8 times or more C: Less than 0.8 times, 0.7 times or more D: Less than 0.7 times

From the results in Table 1, the following can be understood.
In Sample Nos. 1 to 16 (invention), the metal complex dye (D) having the tridentate ligand LA in which the amino group-containing aromatic ring group is introduced at the 4-position of the terminal pyridine ring of terpyridine. -1 to D-16) were used. In the photoelectric conversion element and the dye-sensitized solar cell (sample numbers 1 to 16) of the present invention in which such metal complex dyes (D-1 to D-16) are supported on semiconductor fine particles, both conversion efficiency ( A) and conversion efficiency (B) were both high, and the current holding ratio was also high.

In the photoelectric conversion element and the dye-sensitized solar cell (sample numbers ¹ , 2, 5-12 and 14), L ¹ is a metal having a 5-membered aromatic ring which is a furan ring or a pyrrole ring. Complex dyes (D-1, 2, 5-12 and 14) were used. All of these photoelectric conversion elements and dye-sensitized solar cells (Sample Nos. 1, 2, 5-12, and 14) exhibited excellent photoelectric conversion efficiency and high durability. Moreover, the influence of the film thickness of the semiconductor layer is small, and even if the film thickness is reduced to 6 μm, the photoelectric conversion efficiency and the high durability are excellent.

In the photoelectric conversion element and the dye-sensitized solar cell (sample numbers 1 to 13 and 16), the ligand LA into which an amino group-containing aromatic ring group having a diarylamino group is introduced and the bidentate or tridentate coordination described above Metal complex dyes (D-1 to 13 and 16) having a child LD were used. As a result, both of them maintained high conversion efficiency (A) and conversion efficiency (B), and the current holding ratio was further increased.
In addition, the metal complex dye of the present invention imparts the above characteristics excellent to photoelectric conversion elements and dye-sensitized solar cells as shown in Table 1, regardless of whether they are electrically neutral or TBA salts. did it.

  Furthermore, the metal complex dye of this invention was able to be used suitably as a sensitizing dye of the photoelectric conversion element and dye-sensitized solar cell of this invention. In addition, the dye solution of the present invention containing the metal complex dye of the present invention and a solvent could be suitably used for preparing semiconductor fine particles carrying the metal complex dye of the present invention. Furthermore, the terpyridine compound of the present invention is suitable as a ligand for the metal complex dye of the present invention, and its esterified product is particularly suitable as a ligand precursor for the metal complex dye of the present invention.

On the other hand, the photoelectric conversion element and the dye-sensitized solar cell (sample numbers c1 to c3) in which the metal complex dye not having the ligand LA is supported on the semiconductor fine particles are both in terms of conversion efficiency and durability. And did not reach the passing level.
Specifically, in the photoelectric conversion elements and dye-sensitized solar cells of sample numbers c1 and c3, a substituent or alkoxyphenyl group containing an arylamino group at the 3-position with respect to the ring nitrogen atom of the terminal pyridine ring of terpyridine The metal complex dye (C-1 and C-3) which has the tridentate ligand which introduce | transduced was used. These photoelectric conversion elements and dye-sensitized solar cells (sample numbers c1 and c3) can be used regardless of whether the ligand other than the ligand LA is a monodentate ligand LX or a tridentate ligand LD. At least the conversion efficiency (A) and the conversion efficiency (B) did not reach the acceptable level.
In the photoelectric conversion element and dye-sensitized solar cell of sample number c2, a metal having a tridentate ligand in which an alkylthiophene ring group is introduced at the 4-position with respect to the ring nitrogen atom of the terminal pyridine ring of terpyridine A complex dye (C-2) was used. However, in this photoelectric conversion element and the dye-sensitized solar cell (sample number c2), none of the conversion efficiency (A), the conversion efficiency (B), and the current holding ratio reached the acceptable level.

  While this invention has been described in conjunction with its embodiments, we do not intend to limit our invention in any detail of the description unless otherwise specified and are contrary to the spirit and scope of the invention as set forth in the appended claims. I think it should be interpreted widely.

  This application claims priority based on Japanese Patent Application No. 2014-1992249 filed in Japan on September 29, 2014, and Japanese Patent Application No. 2015-113835 filed on June 4, 2015 in Japan. Which are hereby incorporated by reference herein as part of their description.

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 External circuit 10 Photoelectric conversion element 100 Application of photoelectric conversion element to 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 (14)

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 a metal represented by the following formula (I) A photoelectric conversion element having semiconductor fine particles carrying a complex dye.
Formula (I) M (LA) (LD) _p (LX) _q · (CI) _z
In the formula, M represents a metal ion.
LA represents a tridentate ligand represented by the following formula (LA-1).
LD represents a bidentate or tridentate ligand. p represents 0 or 1;
LX represents a monodentate ligand. q represents 3 when p is 0, represents 0 when p is 1 and LD is a tridentate ligand, and represents 1 when p is 1 and LD is a bidentate ligand. .
CI represents a counter ion necessary for neutralizing the charge of the metal complex dye. z represents an integer of 0 to 3.

In the formula, Za and Zb each independently represents a group of nonmetallic atoms necessary to complete a 5-membered or 6-membered ring. However, each ring formed by Za and Zb has one acidic group.
L ^W each independently represents a nitrogen atom or CR ^{W, R W} represents a hydrogen atom or a substituent.
L ¹ is a monocyclic ring selected from the group consisting of a benzene ring, a furan ring, a selenophene ring, a cyclopentadiene ring, a silole ring and a nitrogen-containing aromatic ring, or a polycyclic ring containing the monocyclic ring as a condensed ring. in the ring-constituting carbon atom to form a ring represents an aromatic ring group bonded to a ring containing the L ^W.
L ² represents an aromatic ring group. m represents an integer of 0 to 5.
R ¹ and R ² each independently represents an alkyl group or an aromatic ring group. The ring formed by Za is a pyridine ring, pyrimidine ring, pyrazine ring, pyridazine ring, triazine ring, tetrazine ring, quinoline ring, isoquinoline ring, imidazole ring, pyrazole ring, triazole ring, thiazole ring, oxazole ring, benzimidazole ring , At least one selected from the group consisting of a benzotriazole ring, a benzoxazole ring and a benzothiazole ring,
The ring formed by Zb is a pyridine ring, pyrimidine ring, pyrazine ring, pyridazine ring, triazine ring, tetrazine ring, quinoline ring, isoquinoline ring, imidazole ring, triazole ring, thiazole ring, oxazole ring, benzimidazole ring, benzotriazole At least one selected from the group consisting of a ring, a benzoxazole ring and a benzothiazole ring,
The ring containing L ^W is a pyridine ring, a pyrimidine ring, a pyridazine ring, a triazine ring, a photoelectric conversion element according to claim 1 is at least one selected from the group consisting of tetrazine ring and quinoline ring. The photoelectric conversion element according to claim 1, wherein the M is Ru ²⁺ or Os ²⁺ . The photoelectric conversion element according to any one of claims 1 to 3, wherein the LA is represented by the following formula (LA-2).

^Wherein, L ^1, L 2, m, ^{R 1} and ^{R 2} are each, ^{L 1,} L 2, m in the formula (LA-1), the same meaning as that of ^{R 1} and ^{R 2.} Anc1 and Anc2 each independently represent an acidic group. The photoelectric conversion element according to any one of claims 1 to 4, wherein each of R ¹ and R ² is an aromatic ring group.   The photoelectric conversion element according to claim 1, wherein the single ring is a benzene ring, a furan ring, or a pyrrole ring. The photoelectric conversion element according to claim 1, wherein the LA is represented by the following formula (LA-3).

In the formula, Z represents —O— or —NR ²³ —. R ^{11 to} R ²³ each independently represents a hydrogen atom or a substituent. Anc1 and Anc2 each independently represent an acidic group. L ² has the same meaning as ^{L 2} in Formula (LA-1). n represents 0 or 1.   The photoelectric conversion element according to claim 1, wherein the acidic group is a carboxy group or a salt thereof. The photoelectric conversion device according to any one of claims 1 to 8, wherein the LD is a bidentate ligand represented by any one of the following formulas (2L-1) to (2L-4). .

In the formula, ring D ^2L represents an aromatic ring. A ^{111 to} A ¹⁴¹ each independently represents an anion of a nitrogen atom or an anion of a carbon atom. R ^{111 to} R ¹⁴³ each independently represent a hydrogen atom or a substituent not having the acidic group. * Represents a coordination position to the metal ion M. The photoelectric conversion device according to any one of claims 1 to 8, wherein the LD is a tridentate ligand represented by any one of the following formulas (3L-1) to (3L-4). .

In the formula, ring D ^2L represents an aromatic ring. A ^{211 to} A ²⁴² each independently represent a nitrogen atom or a carbon atom. However, in each of A ²¹¹ and A ²¹² , A ²²¹ and A ²²² , A ²³¹ and A ²³² , and A ²⁴¹ and A ²⁴² , at least one is an anion. R ^{211 to} R ²⁴¹ each independently represent a hydrogen atom or a substituent not having the acidic group. * Represents a coordination position to the metal ion M.   The dye-sensitized solar cell provided with the photoelectric conversion element of any one of Claims 1-10. A metal complex dye represented by the following formula (I).
Formula (I) M (LA) (LD) _p (LX) _q · (CI) _z
In formula (I), M represents a metal ion.
LA represents a tridentate ligand represented by the following formula (LA-1).
LD represents a bidentate or tridentate ligand. p represents 0 or 1;
LX represents a monodentate ligand. q represents 3 when p is 0, represents 0 when p is 1 and LD is a tridentate ligand, and represents 1 when p is 1 and LD is a bidentate ligand. .
CI represents a counter ion necessary for neutralizing the charge of the metal complex dye. z represents an integer of 0 to 3.

In the formula, Za and Zb each independently represents a group of nonmetallic atoms necessary to complete a 5-membered or 6-membered ring. However, each ring formed by Za and Zb has one acidic group.
L ^W each independently represents a nitrogen atom or CR ^{W, R W} represents a hydrogen atom or a substituent.
L ¹ is a monocyclic ring selected from the group consisting of a benzene ring, a furan ring, a selenophene ring, a cyclopentadiene ring, a silole ring and a nitrogen-containing aromatic ring, or a polycyclic ring containing the monocyclic ring as a condensed ring. in the ring-constituting carbon atom to form a ring represents an aromatic ring group bonded to a ring containing the L ^W.
L ² represents an aromatic ring group. m represents an integer of 0 to 5.
R ¹ and R ² each independently represents an alkyl group or an aromatic ring group.   A dye solution containing the metal complex dye according to claim 12 and a solvent. A terpyridine compound represented by the following formula (LA-2) or an esterified product thereof.

In the formula, L ¹ is a single ring selected from the group consisting of a benzene ring, a furan ring, a selenophene ring, a cyclopentadiene ring, a silole ring and a nitrogen-containing aromatic ring, or a polycyclic ring containing the single ring as a condensed ring. Represents an aromatic ring group bonded to a pyridine ring at a ring-constituting carbon atom forming the monocycle. L ² represents an aromatic ring group. m represents an integer of 0 to 5. R ¹ and R ² each independently represents an alkyl group or an aromatic ring group. Anc1 and Anc2 each independently represent an acidic group.

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