JP6089007B2 - Photoelectric conversion element, method for producing photoelectric conversion element, and solar cell - Google Patents

Description

  The present invention relates to a photoelectric conversion element, a method for manufacturing a photoelectric conversion element, and a solar cell.

  Photoelectric conversion elements are used in various optical sensors, copying machines, solar cells, and the like. Solar cells are expected to be put into full-scale practical use as non-depleting solar energy. Among these, a dye-sensitized solar cell using an organic dye or a Ru bipyridyl complex as a sensitizer has been actively researched and developed, and the photoelectric conversion efficiency has reached about 11%.

On the other hand, in recent years, research results have been reported that solar cells using metal halides as compounds having a perovskite crystal structure can achieve relatively high conversion efficiency (see Non-Patent Documents 1 and 2). Patent applications have been filed (see Patent Document 1) and are attracting attention.
Patent Document 1 discloses a compound having a perovskite crystal structure represented by CH ₃ NH ₃ MX ₃ (M represents Pb or Sn, and X represents a halogen atom) and a light absorption layer including a semiconductor fine particle layer, A solar cell with an electrolyte layer made of an electrolyte is described. Non-Patent Document 1 discloses a TiO ₂ film in which a compound having a perovskite crystal structure of CH ₃ NH ₃ PbX ₃ (X represents a bromine atom or an iodine atom) is adsorbed as nano-sized fine particles, an electrolyte solution, A solar cell is described. Non-Patent Document 2 describes a solar cell using a compound having a perovskite crystal structure of CH ₃ NH ₃ PbI ₂ Cl and a hole transport material.

Korean Registered Patent No. 10-1172374

J. et al. Am. Chem. Soc. 2009, 131 (17), 6050-6051. Science, 338, 643 (2012)

As described above, the photoelectric conversion element and the solar cell using the compound having a perovskite crystal structure of a metal halide have achieved certain results in improving the photoelectric conversion efficiency.
On the other hand, in a solar cell using an InGaAs compound composed of indium (In), gallium (Ga) and arsenic (As), photoelectric conversion efficiency is less than 36%, and from InGaP, gallium and arsenic composed of indium, gallium and phosphorus (P). In the junction cell (solar cell) using the condensing compound of GaAs or InGaAs, a photoelectric conversion efficiency of 43% or more is achieved. However, these compounds are expensive and cannot be used for general purposes.
For this reason, attention was paid to a photoelectric conversion element and a solar cell using a compound having a perovskite crystal structure such as a metal halide which can be manufactured at low cost.
In the research of the present inventors, in order to improve the photoelectric conversion efficiency of a photoelectric conversion element and a solar cell using a compound having a perovskite crystal structure of a metal halide, an IPCE (incident photo to current conversion efficiency at each wavelength). And found that it is important to further improve the photoelectric conversion efficiency, quantum yield or sensitivity).

  Therefore, this invention makes it a subject to provide the manufacturing method of a photoelectric conversion element with high IPCE in each wavelength, a solar cell provided with the same, and a photoelectric conversion element.

The present inventors have advanced various studies on solar cells (also called perovskite sensitized solar cells) using a compound having a perovskite crystal structure (also called a perovskite compound or a perovskite light absorber). For example, in the case of CH ₃ NH ₃ PbX ₃ (X represents a halogen atom), the perovskite light absorber has the following structure as one of the crystal structures. That is, X ⁻ is arranged in an octahedral structure on the central metal of Pb ²⁺ , and this octahedron is incorporated into a cubic structure composed of nitrogen atoms of CH ₃ NH ₃ ⁺ at each of the four vertices. each X present in ^- is a structure to place the center of each plane of the cube. In each of the six faces of the cube of this structure, this unit structure is repeated sharing the four nitrogen atoms forming the plane.
It is also known that in a high-temperature superconductor such as Bi ₂ Sr ₂ Ca ₂ Cu ₃ O ₁₀ , the two-dimensional arrangement of the unit structures in the perovskite crystal structure is also important.
For this reason, in the perovskite type light absorber, it seems that it is important for charge transfer whether the crystal structure can be regularly arranged in as constant order as possible.

However, in our research, in the combination with various materials, the perovskite type light absorption is considered to be partly disrupted in the regular arrangement of the at least two-dimensional unit structure of the perovskite type crystal structure. It has been found that when the agent is used in combination with a metal complex dye or an organic dye, IPCE is greatly improved.
The present invention has been completed based on these findings.

That is, the above problem has been solved by the following means.
<1> A porous layer provided on a conductive support, a first electrode having a photosensitive layer containing a light absorber on the porous layer, a second electrode facing the first electrode, and a first electrode And a hole transport layer provided between the second electrode and a photoelectric conversion element,
The light absorber contains at least two kinds of light absorbers I and II, and the light absorber I is a cation of a periodic table group 1 element or a cationic organic group A, and a cation of a metal atom M other than the periodic table group 1 element. and at least one compound having a perovskite crystal structure having an anion of the anionic atom X, the light absorbing agent II is, photoelectric conversion element is a Ru metal complex color element having an amino group in the molecule.
<2> Ru metal complex dye, photoelectric conversion device according to a Ru metal complex dye ligand bipyridine or terpyridine skeleton is coordinated <1>.
< 3 > The photosensitive layer has (a) at least one of light absorbers I and II on the porous layer, or (b) any of light absorbers I and II on the surface of the porous layer. The photoelectric conversion device according to <1> or <2> , having one and having the other of the light absorbers I and II across an intermediate layer containing a hole transport material.
< 4 > The photosensitive layer has (a) at least one of light absorbers I and II on the porous layer, and (ai) both of the light absorbers I and II are in contact with the surface of the porous layer. Or (aii) any one of <1> to < 3 >, wherein either one of the light absorbers I and II is in contact with the porous layer and the other is laminated on the one light absorber. The photoelectric conversion element as described in one.
< 5 > The photoelectric conversion element according to any one of <1> to < 4 >, wherein the compound having a perovskite crystal structure is a compound represented by the following formula (I).

Formula (I): A _a M _m X _x
In the formula, A represents a group 1 element of the periodic table or a cationic organic group. M represents a metal atom other than the first group element of the periodic table. X represents an anionic atom. a represents 1 or 2, m represents 1, and a, m, and x satisfy a + 2m = x.

< 6 > The photoelectric conversion element according to any one of <1> to < 5 >, wherein the compound having a perovskite crystal structure includes a compound represented by the following formula (I-1).

Formula (I-1): AMX ₃
In the formula, A represents a group 1 element of the periodic table or a cationic organic group. M represents a metal atom other than the first group element of the periodic table. X represents an anionic atom.

< 7 > The photoelectric conversion element according to any one of <1> to < 5 >, wherein the compound having a perovskite crystal structure includes a compound represented by the following formula (I-2).

Formula (I-2): A ₂ MX ₄
In the formula, A represents a group 1 element of the periodic table or a cationic organic group. M represents a metal atom other than the first group element of the periodic table. X represents an anionic atom.

< 8 > The photoelectric conversion element according to any one of <1> to < 7 >, wherein A is a cationic organic group represented by the following formula (I-3).

Formula (I-3): R ^1a —NH ₃
In the formula, R ^1a represents a substituent.
< 9 > The photoelectric conversion according to < 8 >, wherein R ^1a is an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an aryl group, a heteroaryl group, or a group that can be represented by the following formula (I-4). element.

In the formula, Xa represents NR ^1c , an oxygen atom or a sulfur atom. R ^1b and R ^1c each independently represent a hydrogen atom or a substituent. * Represents a bonding position with N in the formula (I-3).

The photoelectric conversion element as described in any one of <1>-< 9 > whose < 10 > X is a halogen atom.
< 11 > The photoelectric conversion element according to any one of <1> to < 10 >, wherein M is at least one of Pb and Sn.
< 12 > A solar cell having the photoelectric conversion element according to any one of <1> to < 11 >.
< 13 > The method for producing a photoelectric conversion element according to any one of <1> to < 11 >, wherein the photosensitive layer is formed on the surface of the porous layer, and (ai) the light absorbers I and II are provided. (Iii) Applying a light absorber solution containing either one of the light absorbers I and II, and then applying the other light absorber solution. Or (b) after applying a light absorber solution containing any one of the light absorbers I and II, an intermediate layer containing a hole transport material is provided, and the light absorber I and The manufacturing method of the photoelectric conversion element which apply | coats the light absorber solution containing the other of II, and forms into a film.

In the present specification, each of the above formulas, particularly the formula (I-3), the formula (I-4) and the formula (A ^am ) is partially used for understanding the chemical structure of a compound having a perovskite crystal structure. Sometimes expressed as a formula. Accordingly, in each formula, a partial structure is referred to as a group, a substituent, or an atom. In this specification, these mean an element group or an element constituting a (substitution) group represented by the above formula. To do.

  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. In addition, it means that a part of the structure is changed as long as the desired effect is achieved. Furthermore, a compound that does not specify substitution or non-substitution is meant to include a compound having an arbitrary substituent as long as a desired effect is achieved. The same applies to substituents and linking groups (hereinafter referred to as substituents and the like).

  In this specification, when there are a plurality of substituents and the like indicated by a specific symbol, or when a plurality of substituents and the like are specified at the same time, the respective substituents are the same as or different from each other unless otherwise specified. May be. 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 addition, a ring such as an alicyclic ring, an aromatic ring, or a heterocyclic ring may be further condensed to form a condensed ring.

  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.

  According to the present invention, a photoelectric conversion element having a high IPCE at each wavelength, a solar cell including the photoelectric conversion element, and a method for manufacturing the photoelectric conversion element can be provided.

It is sectional drawing which showed typically about the preferable aspect of the photoelectric conversion element of this invention. It is sectional drawing which showed typically about the preferable aspect which has a thick photosensitive layer of the photoelectric conversion element of this invention. It is sectional drawing which expanded and showed the porous layer typically about the preferable aspect of the photosensitive layer in the photoelectric conversion element of this invention. It is a figure explaining the crystal structure of a perovskite compound.

<< Photoelectric conversion element >>
The photoelectric conversion element of the present invention was provided between a first electrode having a conductive support, a porous layer and a photosensitive layer, a second electrode facing the first electrode, and the first electrode and the second electrode. And a hole transport layer. The porous layer, the photosensitive layer, the hole transport layer, and the second electrode are preferably provided on the conductive support in this order.

The photosensitive layer is formed on the porous layer.
In the present invention, examples of the mode having the photosensitive layer on the porous layer include a mode in which the photosensitive layer is provided in a thin film shape on the porous layer (see FIG. 1), and a thickness provided on the porous layer. A mode (refer FIG. 2) is mentioned. The photosensitive layer may be provided in a linear or dispersed form, but is preferably provided in a film form.
In the present invention, the photosensitive layer 13 may be a single layer or a laminate of two or more layers. When the photosensitive layer 13 is a laminate, the photosensitive layer 13 may be a laminate of layers made of different light absorbers, and an intermediate layer containing a hole transport material may be provided between the photosensitive layer and the photosensitive layer.
In the present invention, the photosensitive layer is preferably provided on the surface of the porous layer.

  The photosensitive layer contains at least two light absorbers I and II. In the present invention, one of the light absorbers I and II is at least one perovskite compound, and the other is at least one selected from metal complex dyes and organic dyes.

In the present invention, the photosensitive layer only needs to contain the light absorbers I and II, and the embodiment containing the light absorber is not particularly limited. The embodiment in which the photosensitive layer contains a light absorber preferably includes both the following embodiments (a) and (b).
(A) A mode in which the photosensitive layer contains at least one of each of the light absorber I and the light absorber II on the porous layer (b) The photosensitive layer has the light absorbers I and II on the surface of the porous layer. An embodiment having either one of the light absorbers I and II with an intermediate layer containing a hole transport material interposed therebetween

The embodiment (a) further includes the following three embodiments (ai) to (aii-2).
(Ai) An embodiment in which the photosensitive layer contains at least one of each of the light absorbers I and II, and both the light absorbers I and II are in contact with the surface of the porous layer (in this embodiment, the light absorber I And II are mixed on the surface of the porous layer)
Preferably, as shown to Fig.3 (a), the photosensitive layer 13a of the one layer provided in the surface of the porous layer 12 and containing the light absorbers I and II is mentioned.
(Aii-1) The photosensitive layer includes at least one of each of the light absorbers I and II, has the light absorber I in contact with the surface of the porous layer, and the light absorber II on the light absorber I. Preferably, as shown in FIG. 3 (b), the first photosensitive layer 13b1 containing the light absorber I provided on the surface of the porous layer 12 and the surface of the first photosensitive layer 13b1 A photosensitive layer 13b having a second photosensitive layer 13b2 that is laminated and includes a light absorber II is exemplified.
(Aii-2) The photosensitive layer contains at least one of each of the light absorbers I and II, has the light absorber II in contact with the surface of the porous layer, and the light absorber I on the light absorber II. Preferably, as shown in FIG. 3C, on the surface of the second photosensitive layer 13c1 including the light absorbing agent II provided on the surface of the porous layer 12, and on the surface of the second photosensitive layer 13c1. The photosensitive layer 13c which is laminated | stacked and has the 1st photosensitive layer 13c2 containing the light absorber I is mentioned.

In addition, the above-described aspect (b) includes the following two aspects (bi) and (bii).
(Bi) An embodiment in which the photosensitive layer has a light absorber I on the surface of the porous layer, and has the light absorber II on the light absorber I with an intermediate layer containing a hole transport material interposed therebetween. 3 (d), an I-th photosensitive layer 13d1 including a light absorber I provided on the surface of the porous layer 12, an intermediate layer 13s provided on the surface of the I-th photosensitive layer 13d1, and an intermediate layer The photosensitive layer 13d which has the II photosensitive layer 13d2 containing the light absorber II provided in the surface of 13s is mentioned.
(Bii) An embodiment in which the photosensitive layer has a light absorber II on the surface of the porous layer, and has the light absorber I on the light absorber II with an intermediate layer containing a hole transport material interposed therebetween. 3 (e), the second photosensitive layer 13e1 provided on the surface of the porous layer 12 and containing the light absorber II, the intermediate layer 13s provided on the surface of the second photosensitive layer 13e1, and the intermediate layer The photosensitive layer 13e which has the 1st photosensitive layer 13e2 containing the light absorber I provided in the surface of 13s is mentioned.

  In the above embodiment (b), the intermediate layer is a layer containing a hole transport material, preferably a layer formed of a hole transport material. The intermediate layer is a layer that performs the same function as the hole transport layer 3 described later. The intermediate layer is preferably substantially transparent. The hole transport material contained in the intermediate layer is the same as that of the hole transport layer 3, and the preferred range is also the same.

  In the present invention, the photosensitive layer is formed by appropriately combining the above embodiments (a) and (b), and further, film-like, linear, or dispersed embodiments without departing from the spirit of the present invention. A photosensitive layer.

  The photoelectric conversion element of the present invention is not particularly limited in structure other than the structure defined in the present invention, and a known structure relating to the photoelectric conversion element and the solar cell can be adopted. Each layer 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.

Hereinafter, the preferable aspect of the photoelectric conversion element of this invention is demonstrated.
In FIG. 1 and FIG. 2, the same code | symbol means the same component (member).
1 and 2 show the size of the fine particles forming the porous layer with emphasis. These fine particles are preferably packed horizontally and vertically with respect to the conductive substrate to form a porous structure.

  In this specification, the term “photoelectric conversion element 10” means the photoelectric conversion elements 10A and 10B unless otherwise specified. The same applies to the system 100, the first electrode 1, the photosensitive layer 13, and the hole transport layer 3.

As a preferable aspect of the photoelectric conversion element of the present invention, for example, a photoelectric conversion element 10A shown in FIG. A system 100A shown in FIG. 1 is a system applied to a battery for causing an operation circuit M (for example, an electric motor) to perform work by the external circuit 6 using the photoelectric conversion element 10A.
The photoelectric conversion element 10A includes a first electrode 1A, a second electrode 2, and a hole transport layer 3A. 1 A of 1st electrodes have the electroconductive support body 11 which consists of the support body 11a and the transparent electrode 11b, the porous layer 12, and the photosensitive layer 13A containing at least 2 sorts of light absorbers. In addition, the blocking layer 14 is preferably provided on the transparent electrode 11 b, and the porous layer 12 is formed on the blocking layer 14.

  The photoelectric conversion element 10B shown in FIG. 2 schematically shows a preferred embodiment in which the photosensitive layer 13A of the photoelectric conversion element 10A shown in FIG. In the photoelectric conversion element 10B, the hole transport layer 3B is thinly provided. The photoelectric conversion element 10B differs from the photoelectric conversion element 10A shown in FIG. 1 in the film thicknesses of the photosensitive layer 13B and the hole transport layer 3B, but is configured in the same manner as the photoelectric conversion element 10A except for these points. ing.

In the present invention, the system 100 to which the photoelectric conversion element 10 is applied functions as a solar cell as follows.
That is, in the photoelectric conversion element 10, light that has passed through the conductive support 11 or the second electrode 2 and entered the photosensitive layer 13 excites the light absorber. The excited light absorber has high-energy electrons, and these electrons reach the conductive support 11 from the photosensitive layer 13. At this time, the light absorber that has released electrons with high energy is an oxidant. Electrons reaching the conductive support 11 return to the photosensitive layer 13 via the second electrode 2 and then the hole transport layer 3 while working in the external circuit 6. The light absorber is reduced by the electrons returning to the photosensitive layer 13. By repeating excitation and electron transfer of the light absorber, the system 100 functions as a solar cell.

The flow of electrons from the photosensitive layer 13 to the conductive support 11 differs depending on the presence or absence of the porous layer 12, the type thereof, the type of light absorber, and the like.
In the light absorber I, electron conduction occurs in which electrons move between perovskite compounds. Therefore, when providing the porous layer 12, the porous layer 12 can be formed with an insulator other than the conventional semiconductor. When the porous layer 12 is formed of a semiconductor, electron conduction in which electrons move inside or between the semiconductor particles of the porous layer 12 also occurs. When the porous layer 12 is formed of an insulator, electron conduction does not occur in the porous layer 12.
On the other hand, in the light absorber II, electrons may move between metal complex dyes or organic dyes, but usually, electron conduction occurs in which electrons move inside or between the semiconductor fine particles of the porous layer 12. . Therefore, when a metal complex dye or an organic dye is used alone, it is necessary to provide the porous layer 12 with a conductor or a semiconductor. However, in the present invention in which the light absorber II is used in combination with the light absorber I, the porous layer 12 is not necessarily provided by a conductor or a semiconductor.

Thus, in this invention, the porous layer 12 can be formed with a conductor or a semiconductor, and can also be formed with an insulator. When the porous layer 12 is formed of an insulator, a relatively high electromotive force (Voc) can be obtained by using aluminum oxide (Al ₂ O ₃ ; alumina) fine particles.
Even when the blocking layer 14 as the other layer is formed of a conductor or a semiconductor, electron conduction in the blocking layer 14 occurs.

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

  In this invention, the material and each member which are used for a photoelectric conversion element or a solar cell can be prepared by a conventional method except a light absorber. For a photoelectric conversion element or a solar cell using a perovskite compound, for example, Patent Document 1 and Non-Patent Documents 1 and 2 can be referred to. As for the dye-sensitized solar cell, for example, JP-A No. 2001-291534, US Pat. No. 4,927,721, US Pat. No. 4,684,537, US Pat. No. 5,084, 365, US Pat. No. 5,350,644, US Pat. No. 5,463,057, US Pat. No. 5,525,440, JP-A-7-249790, JP 2004-220974 A and JP 2008-135197 A can be referred to.

  Hereinafter, the preferable aspect of the main member and compound of the photoelectric conversion element of this invention and a solar cell is demonstrated.

<First electrode 1>
The first electrode 1 includes a conductive support 11, a porous layer 12, and a photosensitive layer 13, and functions as a working electrode in the photoelectric conversion element 10.
The first electrode 1 preferably has a blocking layer 14.

− Conductive support 11 −
The conductive support 11 is not particularly limited as long as it has conductivity and can support the photosensitive layer 13 and the like. The conductive support is made of a conductive material, for example, a conductive support made of metal, or a glass or plastic support 11a and a conductive electrode as a transparent electrode 11b formed on the surface of the support 11a. A conductive support 11 having a membrane is preferred.

In particular, as shown in FIGS. 1 and 2, a conductive support 11 in which a transparent metal electrode 11b is formed by coating a conductive metal oxide on the surface of a glass or plastic support 11a is more preferable. . Examples of the support 11a made of plastic include a transparent polymer film described in paragraph No. 0153 of JP-A No. 2001-291534. As a material for forming the support 11a, ceramic (Japanese Patent Laid-Open No. 2005-135902) and conductive resin (Japanese Patent Laid-Open No. 2001-160425) can be used in addition to glass and plastic. 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 support 11a. When the conductive support 11 is used, light is preferably incident from the support 11a side.

The conductive support 11 is preferably substantially transparent. In the present invention, “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 thicknesses of the support 11a and the conductive support 11 are not particularly limited, and are set to appropriate thicknesses. For example, the thickness is preferably 0.01 μm to 10 mm, more preferably 0.1 μm to 5 mm, and particularly preferably 0.3 μm to 4 mm.
When providing the transparent electrode 11b, the film thickness of the transparent electrode 11b is not specifically limited, For example, it is preferable that it is 0.01-30 micrometers, It is more preferable that it is 0.03-25 micrometers, 0.05-20 micrometers It is particularly preferred that

  The conductive support 11 or the support 11a may have a light management function on the surface. For example, even if the surface of the conductive support 11 or the support 11a has an antireflection film in which high refractive films and low refractive index oxide films are alternately stacked as described in JP-A-2003-123859. The light guide function described in JP-A-2002-260746 may be provided.

− Blocking layer 14 −
In the present invention, a blocking layer 14 is preferably provided on the surface of the transparent electrode 11b, that is, between the conductive support 11 and the porous layer 12 or the hole transport layer 3 or the like.
In the photoelectric conversion element and the solar cell, when the hole transport layer 3 and the transparent electrode 11b are in direct contact, a reverse current is generated. The blocking layer 14 functions to prevent this reverse current. The blocking layer 14 is also referred to as a short circuit prevention layer.

The material for forming the blocking layer 14 is not particularly limited as long as it is a material capable of fulfilling the above function, but is a substance that transmits visible light and is an insulating substance for the conductive support 11 (transparent electrode 11b). Preferably there is. Specifically, the “insulating substance with respect to the conductive support 11 (transparent electrode 11b)” specifically refers to a material whose conduction band energy level forms the conductive support 11 (metal oxide forming the transparent electrode 11b). A compound (n-type semiconductor compound) that is higher than the energy level of the conduction band of the material and lower than the energy level of the conduction band of the material constituting the porous layer 12 and the ground state of the light absorber.
Examples of the material for forming the blocking layer 14 include silicon oxide, magnesium oxide, aluminum oxide, calcium carbonate, polyvinyl alcohol, and polyurethane. Moreover, the material generally used for the photoelectric conversion material may be used, and examples thereof include titanium oxide, tin oxide, niobium oxide, and tungsten oxide. Of these, titanium oxide, tin oxide, magnesium oxide, aluminum oxide and the like are preferable.
The film thickness of the blocking layer 14 is preferably 0.001 to 10 μm, more preferably 0.005 to 1 μm, and particularly preferably 0.01 to 0.1 μm.

− Porous layer 12 −
In the present invention, the porous layer 12 is provided on the transparent electrode 11b. When the blocking layer 14 is provided, the porous layer 12 is formed on the blocking layer 14.
The porous layer 12 is a layer that functions as a scaffold for carrying the photosensitive layer 13 on the surface. In the solar cell, in order to increase the light absorption efficiency, it is preferable to increase the surface area of at least a portion that receives light such as sunlight, and it is preferable to increase the entire surface area of the porous layer 12.

The porous layer 12 is preferably a fine particle layer having pores, in which fine particles of the material forming the porous layer 12 are deposited or adhered. The porous layer 12 may be a fine particle layer in which two or more kinds of multi-fine particles are deposited. When the porous layer 12 is a fine particle layer having pores, the amount of light absorbent supported (adsorption amount) can be increased.
In order to increase the surface area of the porous layer 12, it is preferable to increase the surface area of the individual fine particles constituting the porous layer 12. In the present invention, in a state where the fine particles forming the porous layer 12 are coated on the conductive support 11 or the like, the surface area of the fine particles is preferably 10 times or more, more than 100 times the projected area. It is more preferable. Although there is no restriction | limiting in particular in this upper limit, Usually, it is about 5000 times. The particle diameter of the fine particles forming the porous layer 12 is preferably 0.001 to 1 μm as the primary particle in the average particle diameter using the diameter when the projected area is converted into a circle. When the porous layer 12 is formed using a dispersion of fine particles, the average particle diameter of the fine particles is preferably 0.01 to 100 μm as the average particle diameter of the dispersion.

The material for forming the porous layer 12 is not particularly limited with respect to conductivity, and may be an insulator (insulating material), a conductive material, or a semiconductor (semiconductive material). .
Examples of the material for forming the porous layer 12 include metal chalcogenides (for example, oxides, sulfides, selenides, etc.), compounds having a perovskite crystal structure (excluding the light absorber I described later), and silicon. Oxides (eg, silicon dioxide, zeolite) or carbon nanotubes (including carbon nanowires and carbon nanorods) can be used.

  The metal chalcogenide is not particularly limited, but is preferably titanium, tin, zinc, tungsten, zirconium, hafnium, strontium, indium, cerium, yttrium, lanthanum, vanadium, niobium, aluminum or tantalum oxide, cadmium sulfide. , Cadmium selenide and the like. Examples of the crystal structure of the metal chalcogenide include an anatase type, brookite type and rutile type, and anatase type and brookite type are preferable.

  Although it does not specifically limit as a compound which has a perovskite type crystal structure, A transition metal oxide etc. are mentioned. For example, strontium titanate, calcium titanate, barium titanate, lead titanate, barium zirconate, barium stannate, lead zirconate, strontium zirconate, strontium tantalate, potassium niobate, bismuth ferrate, strontium barium titanate , Barium lanthanum titanate, calcium titanate, sodium titanate, bismuth titanate. Of these, strontium titanate, calcium titanate and the like are preferable.

  The carbon nanotube has a shape obtained by rounding a carbon film (graphene sheet) into a cylindrical shape. Carbon nanotubes are single-walled carbon nanotubes (SWCNT) in which one graphene sheet is wound in a cylindrical shape, double-walled carbon nanotubes (DWCNT) in which two graphene sheets are wound in a concentric shape, and multiple graphene sheets are concentric Are classified into multi-walled carbon nanotubes (MWCNT) wound in a shape. As the porous layer 12, any carbon nanotube is not particularly limited and can be used.

  Among these materials, the material forming the porous layer 12 is preferably titanium, tin, zinc, zirconium, aluminum or silicon oxide, or carbon nanotube, and more preferably titanium oxide or aluminum oxide.

  The porous layer 12 may be formed of at least one of the above-described metal chalcogenide, compound having a perovskite crystal structure, silicon oxide, and carbon nanotube, and may be formed of a plurality of types. .

  The material for forming the porous layer 12 is preferably used as fine particles as described later. The material forming the porous layer 12 includes a metal chalcogenide, a compound having a perovskite crystal structure, and a silicon oxide nanotube, nanowire or nanorod, a metal chalcogenide, a compound having a perovskite crystal structure, a silicon oxide. It can also be used with fine particles of carbon nanotubes.

  Although the film thickness of the porous layer 12 is not specifically limited, Usually, it is the range of 0.1-100 micrometers, and when using as a solar cell, 0.1-50 micrometers is preferable and 0.3-30 micrometers is more preferable.

The film thickness of the porous layer 12 is a lower layer surface on which the porous layer 12 is formed along a linear direction intersecting at an angle of 90 ° with the surface of the conductive support 11 in the cross section of the photoelectric conversion element 10. Defined by the average distance from the surface of the porous layer 12 to the surface of the porous layer 12. Here, the “lower surface on which the porous layer 12 is formed” means the interface between the conductive support 11 and the porous layer 12. When another layer such as the blocking layer 14 is formed between the conductive support 11 and the porous layer 12, it means the interface between the other layer and the porous layer 12. Further, the “surface of the porous layer 12” is a porous layer located closest to the second electrode 2 from the conductive support 11 on a virtual straight line that intersects the surface of the conductive support 11 at an angle of 90 °. It refers to the point of the layer 12 (intersection of the virtual straight line and the contour line of the porous layer 12). The “average distance” is 10 along an observation range of a specific range in the cross section of the photoelectric conversion element 10 along a horizontal (parallel) direction (left and right direction in FIGS. 1 and 2) with respect to the surface of the conductive support 11. The longest distance from the surface of the lower layer to the surface of the porous layer 12 is obtained for each equally divided section, and the average value of the longest distances of these 10 sections is obtained. The film thickness of the porous layer 12 can be measured by observing the cross section of the photoelectric conversion element 10 with a scanning electron microscope (SEM).
Unless otherwise stated, the thickness of other layers such as the blocking layer 14 can be measured in the same manner.

− Photosensitive layer (light absorbing layer) 13 −
As shown in FIGS. 1 to 3, the photosensitive layer 13 is provided on the surface of the porous layer 12 (including the inner surface when the surface is uneven).

  The mode that the photosensitive layer 13 has on the porous layer 12 is as described above, and the photosensitive layer 13 is preferably provided on the porous layer 12 so that excited electrons flow to the conductive support 11. . At this time, the photosensitive layer 13 may be provided on the entire surface of the porous layer 12 or may be provided on a part of the surface.

The film thickness of the photosensitive layer 13 is appropriately set according to the mode having the photosensitive layer 13 on the porous layer 12 and is not particularly limited. For example, the film thickness of the photosensitive layer 13 (total film thickness with the film thickness of the porous layer 12) is preferably 0.1 to 100 μm, more preferably 0.1 to 50 μm, and particularly preferably 0.3 to 30 μm. The film thickness of the photosensitive layer 13 can be measured in the same manner as the film thickness of the porous layer 12.
Here, the film thickness of the photosensitive layer 13 means the total film thickness of each layer when the photosensitive layer 13 is a laminate, and means the total film thickness including the intermediate layer when the photosensitive layer 13 includes the intermediate layer. . The thickness of the intermediate layer is preferably 0.05 to 5.0 μm, more preferably 0.08 to 3.0 μm, and further preferably 0.1 to 2.0 μm.
When the photosensitive layer 13 is a thin film, the thickness of the photosensitive layer 13 is the interface between the porous layer 12 and the hole transport layer 3 along the direction perpendicular to the surface of the porous layer 12. And the distance.

  Note that the photoelectric conversion element 10B illustrated in FIG. 2 includes a photosensitive layer 13B having a thickness larger than that of the photosensitive layer 13A of the photoelectric conversion element 10A illustrated in FIG. In this case, the perovskite compound as the light absorber I can be a hole transporting material, similar to the compound having the perovskite crystal structure as the material for forming the porous layer 12 described above.

(Light absorber)
In the present invention, the photosensitive layer 13 has at least two different light absorbers I and II.
The light absorber I is at least one perovskite compound.
The perovskite compound has a periodic table group 1 element or cationic organic group A, a metal atom M other than the periodic table group 1 element, and an anionic atom X. In the perovskite type crystal structure, the periodic table group 1 element or the cationic organic group A, the metal atom M, and the anionic atom X of the perovskite compound are each a cation (for convenience, sometimes referred to as cation A), a metal cation (for convenience). , Sometimes referred to as cation M) and anion (sometimes referred to as anion X for convenience).
In the present invention, the cationic organic group means an organic group having a property of becoming a cation in the perovskite type crystal structure, and the anionic atom means an atom having a property of becoming a cation in the perovskite type crystal structure.
In the present invention, the light absorber I can be a perovskite compound alone or in combination of two or more.

  The light absorber II is at least one selected from metal complex dyes and organic dyes. In the present invention, as the light absorber, two or more kinds of metal complex dyes can be used, two or more kinds of organic dyes can be used, and one or more kinds of metal complex dyes and one or more kinds of organic dyes can be used. A pigment can be used in combination.

1. Perovskite light absorber

  The perovskite compound used in the present invention is not particularly limited as long as it is a compound that can have a perovskite crystal structure containing the above constituent ions.

In the perovskite compound used in the present invention, the cation A is an organic cation composed of a cation of a group 1 element of the periodic table or a cationic organic group A. The cation A is preferably an organic cation.
The cation of the Group 1 element of the periodic table is not particularly limited, and for example, the cation (Li ⁺ , Na ⁺ , K ⁺ of each element of lithium (Li), sodium (Na), potassium (K), or cesium (Cs). Cs ⁺ ), and a cesium cation (Cs ⁺ ) is particularly preferable.
The organic cation is more preferably an organic cation of a cationic organic group represented by the following formula (I-3).
Formula (I-3): R ^1a —NH ₃

In the formula, R ^1a represents a substituent. R ^1a is not particularly limited as long as it is an organic group, but can be represented by an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an aryl group, a heteroaryl group, or the following formula (I-4). Groups are preferred. Among these, an alkyl group and a group that can be represented by the following formula (I-4) are more preferable.

In formula, ^Xa represents NR ^<1c> , an oxygen atom, or a sulfur atom. R ^1b and R ^1c each independently represent a hydrogen atom or a substituent. * Represents a bonding position with N in the formula (I-3).

In the present invention, the organic cation of the cationic organic group A is preferably an organic ammonium cation composed of an ammonium cationic organic group A formed by combining R ^1a and NH _{3 in} the above formula (I-3). When the organic ammonium cation can have a resonance structure, the organic cation includes a cation having a resonance structure in addition to the organic ammonium cation. For example, in the group that can be represented by the above formula (I-4), when X ^a is NH (R ^1c is a hydrogen atom), the organic cation is NH and the group that can be represented by the above formula (I-4). _In addition to the organic ammonium cation of the ammonium cationic organic group formed by bonding to ₃ , an organic amidinium cation which is one of the resonance structures of this organic ammonium cation is also included. Examples of the organic amidinium cation comprising an amidinium cationic organic group include a cation represented by the following formula (A ^am ). In this specification, for convenience the cation represented by the following formula ^{(A am),} may be referred to as ^{"R 1b C (= NH) -NH} 3 ".

The alkyl group for the substituent R ^1a is preferably an alkyl group having 1 to 18 carbon atoms, and more preferably an alkyl group having 1 to 6 carbon atoms. For example, methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, pentyl, hexyl and the like can be mentioned.
The cycloalkyl group is preferably a cycloalkyl group having 3 to 8 carbon atoms, and examples thereof include cyclopropyl, cyclopentyl, and cyclohexyl.

The alkenyl group is preferably an alkenyl group having 2 to 18 carbon atoms, and examples thereof include vinyl, allyl, butenyl and hexenyl.
The alkynyl group is preferably an alkynyl group having 2 to 18 carbon atoms, and examples thereof include ethynyl, butynyl and hexynyl.

The aryl group is preferably an aryl group having 6 to 14 carbon atoms, and examples thereof include phenyl.
The heteroaryl group includes a group consisting only of an aromatic heterocycle and a group consisting of a condensed heterocycle obtained by condensing an aromatic heterocycle with another ring such as an aromatic ring, an aliphatic ring or a heterocycle.
As a ring-constituting hetero atom constituting the aromatic hetero ring, a nitrogen atom, an oxygen atom and a sulfur atom are preferable. The number of ring members of the aromatic heterocycle is preferably a 5-membered ring or a 6-membered ring.
Examples of the condensed heterocycle including a 5-membered aromatic heterocycle and a 5-membered aromatic heterocycle include a pyrrole ring, an imidazole ring, a pyrazole ring, an oxazole ring, a thiazole ring, a triazole ring, a furan ring, and a thiophene ring. , Benzimidazole ring, benzoxazole ring, benzothiazole ring, indoline ring, and indazole ring. Examples of the condensed heterocycle including a 6-membered aromatic heterocycle and a 6-membered aromatic heterocycle include, for example, pyridine ring, pyrimidine ring, pyrazine ring, triazine ring, quinoline ring, and quinazoline ring. Is mentioned.

In the group that can be represented by the formula (I-4), X ^a represents NR ^1c , an oxygen atom or a sulfur atom, and NR ^1c is preferable. Here, R ^1c is preferably a hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an aryl group or a heteroaryl group, and more preferably a hydrogen atom.
R ^1b represents a hydrogen atom or a substituent, and preferably a hydrogen atom. ^Examples of the substituent that R ^1b can take include a hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an aryl group, and a heteroaryl group.
The alkyl group, cycloalkyl group, alkenyl group, alkynyl group, aryl group, and heteroaryl group that R ^1b and R ^1c can each have the same meanings as those of R ^1a , and the preferred ones are also the same.
Examples of the group that can be represented by the formula (I-4) include formimidoyl (HC (═NH) —), acetimidoyl (CH ₃ C (═NH) —), propionimidoyl (CH ₃ CH ₂ C (= NH)-) and the like. Among these, formimidoyl is preferable.

The alkyl group, cycloalkyl group, alkenyl group, alkynyl group, aryl group, heteroaryl group and group that can be represented by the above formula (I-4), which R ^1a can take, all have a substituent. May be. The substituent that R ^1a may have is not particularly limited, and examples thereof include an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group, an alkoxy group, an alkylthio group, an amino group, Examples include alkylamino group, arylamino group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, acylamino group, sulfonamido group, carbamoyl group, sulfamoyl group, halogen atom, cyano group, hydroxy group or carboxy group. Each substituent that R ^1a may have may be further substituted with a substituent.

  In the perovskite compound used in the present invention, the metal cation M is not particularly limited as long as it is a cation of a metal atom M other than a group 1 element of the periodic table and a cation of a metal atom capable of taking a perovskite crystal structure. Examples of such metal atoms include calcium (Ca), strontium (Sr), cadmium (Cd), copper (Cu), nickel (Ni), manganese (Mn), iron (Fe), cobalt (Co), Examples include metal atoms of palladium (Pd), germanium (Ge), tin (Sn), lead (Pb), ytterbium (Yb), europium (Eu), and indium (In). Of these, the metal atom forming the metal cation is particularly preferably Pb or Sn. The metal atom may be one kind of metal atom or two or more kinds of metal atoms. In the case of two or more kinds of metal atoms, two kinds of Pb and Sn are preferable. In addition, the ratio of the metal atom at this time is not specifically limited.

  In the perovskite compound used in the present invention, the anion X represents an anion of the anionic atom X. This anion is preferably an anion of a halogen atom. As a halogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc. are mentioned, for example. The anion X may be an anion of one kind of anionic atom or an anion of two or more kinds of anionic atoms. In the case of anions of two or more types of anionic atoms, two types of anions of halogen atoms, particularly anions of bromine atoms and iodine atoms are preferred. In addition, the ratio of the anion of the anionic atom at this time is not particularly limited.

  The perovskite compound used in the present invention is preferably a perovskite compound having a perovskite crystal structure having each of the above constituent ions and represented by the following formula (I).

Formula (I): A _a M _m X _x
In the formula, A represents a group 1 element of the periodic table or a cationic organic group.
M represents a metal atom other than Group 1 elements of the periodic table. X represents an anionic atom.
a represents 1 or 2, m represents 1, and a, m, and x satisfy a + 2m = x. That is, x is 3 when a is 1 and 4 when a is 2.

  In the formula (I), the periodic table group 1 element or the cationic organic group A forms the cation A having a perovskite crystal structure. Accordingly, the Group 1 element of the periodic table and the cationic organic group A are not particularly limited as long as they are elements or groups that can form the perovskite crystal structure by becoming the cation A. The Periodic Table Group 1 element or the cationic organic group A has the same meaning as the Periodic Table Group 1 element or the cationic organic group described above for the cation A, and the preferred ones are also the same.

  The metal atom M is a metal atom that forms the metal cation M having a perovskite crystal structure. Therefore, the metal atom M is not particularly limited as long as it is a metal atom other than the Group 1 element of the periodic table and can form the perovskite crystal structure by forming the metal cation M. The metal atom M is synonymous with the metal atom described in the metal cation M, and the preferred ones are also the same.

  The anionic atom X forms the anion X having a perovskite crystal structure. Therefore, the anionic atom X is not particularly limited as long as it is an atom that can form the perovskite crystal structure by becoming the anion X. The anionic atom X is synonymous with the anionic atom demonstrated by the said anion X, and its preferable thing is also the same.

When a is 1, the perovskite compound represented by the formula (I) is a perovskite compound represented by the following formula (I-1), and when a is 2, the following formula (I-2) It is a perovskite compound represented.
Formula (I-1): AMX ₃
Formula (I-2): A ₂ MX ₄
In formula (I-1) and formula (I-2), A represents a periodic table group 1 element or a cationic organic group, and is synonymous with A of the said formula (I), and its preferable thing is also the same.
M represents a metal atom other than the Group 1 element of the periodic table, and is synonymous with M in the above formula (I), and preferred ones are also the same.
X represents an anionic atom, and is synonymous with X of the said formula (I), and its preferable thing is also the same.

Here, the perovskite crystal structure will be described.
As described above, the perovskite crystal structure contains the cation A, the metal cation M, and the anion X as constituent ions.
FIG. 4A is a diagram showing a basic unit cell of a perovskite crystal structure, and FIG. 4B is a diagram showing a structure in which the basic unit cell is three-dimensionally continuous in the perovskite crystal structure. FIG. 4C is a diagram showing a layered structure in which inorganic layers and organic layers are alternately stacked in a perovskite crystal structure.
In the perovskite compound represented by the formula (I-1), as shown in FIG. 4A, a cation A is arranged at each apex, a metal cation M is arranged at the body center, and the metal cation M is the center. A cubic basic unit cell in which an anion X is arranged at each face center of the cubic crystal. As shown in FIG. 4 (b), one basic unit cell shares the cation A and the anion X with each of the other 26 basic unit cells adjacent (surrounding), and is three-dimensional. The basic unit cell has a continuous structure.

On the other hand, the perovskite compound represented by the formula (I-2) has an MX ₆ octahedron composed of a metal cation M and an anion X with respect to the perovskite compound represented by the formula (I-1). Same in respect, but different in basic unit cell and its arrangement. That is, the perovskite compound represented by the formula (I-2) is an inorganic layer formed by arranging MX ₆ octahedrons in a two-dimensional (planar) form as shown in FIG. 4 (c). And an organic layer formed by alternately inserting a cation A between the inorganic layers.
In such a layered structure, the basic unit cell shares the cation A and the anion X with other adjacent basic unit cells in the plane of the same layer. On the other hand, the basic unit cell does not share the cation A and the anion X in different layers. This layered structure has a two-dimensional layer structure in which the inorganic layer is divided by the organic group of the cation A. As shown in FIG. 4C, the organic group in the cation A functions as a spacer organic group between the inorganic layers.
For perovskite compounds having a layered structure, see, for example, New. J. et al. Chem. , 2008, 32, 1736.

In the perovskite compound, a possible crystal structure is determined by the cation A (group 1 element of the periodic table or cationic organic group A). For example, when the cation A is a cation of a group 1 element of the periodic table or an organic cation of a cationic organic group A having a substituent R ^1a having 1 carbon atom, the perovskite compound is represented by the formula (I-1) It is easy to take a cubic crystal structure. Examples of the cation A include CH ₃ —NH ₃ and HC (═NH) —NH ₃ (R ^1b and R 1) among organic cations having a group that can be represented by the formula (I-4). ^And cations such as when ^1c is a hydrogen atom.
On the other hand, when the cation A is a cation of a cationic organic group A having a substituent R ^1a having 2 or more carbon atoms, the perovskite compound is represented by the formula (I-2) and easily takes a layered crystal structure. Examples of such a cation A include an alkyl group having 2 or more carbon atoms, a cycloalkyl group, an alkenyl group, an alkynyl group, an aryl group, a heteroaryl group, and the above formula (I-4) described as the substituent R ^1a. And an organic cation of the cationic organic group A having a group that can be represented by the ^formula (provided that R ^1b and R ^1c are substituents).

  The perovskite compound used in the present invention may be either a compound represented by formula (I-1) or a compound represented by formula (I-2), or a mixture thereof. Therefore, in the present invention, at least one perovskite compound only needs to be present as a light absorber, and it is not necessary to clearly distinguish which compound is strictly based on the composition formula, molecular formula, crystal structure, and the like. .

  Specific examples of the perovskite compound used in the present invention are illustrated below, but the present invention is not limited thereby. In the following, the compound represented by the formula (I-1) and the compound represented by the formula (I-2) are described separately. However, even if it is a compound illustrated as a compound represented by a formula (I-1), depending on synthesis conditions etc., it may become a compound represented by a formula (I-2). In some cases, the mixture is a mixture of the compound represented by -1) and the compound represented by formula (I-2). Similarly, even if it is a compound illustrated as a compound represented by a formula (I-2), it may become a compound represented by a formula (I-1), and is represented by a formula (I-1). In some cases, the compound is a mixture of the compound represented by formula (I-2).

Specific examples of the compound represented by formula (I-1) include, for example, CH ₃ NH ₃ PbCl ₃ , CH ₃ NH ₃ PbBr ₃ , CH ₃ NH ₃ PbI ₃ , CH ₃ NH ₃ PbBrI ₂ , and CH ₃ NH _3. PbBr _{2 I,} include _{CH 3 NH 3 SnBr 3, CH} 3 NH 3 SnI 3, CH (= NH) NH 3 PbI 3.

Specific examples of the compound represented by the formula (I-2) include, for example, (C ₂ H ₅ NH ₃ ) ₂ PbI ₄ , (CH ₂ = CHNH ₃ ) ₂ PbI ₄ , (CH≡CNH ₃ ) ₂ PbI _{4 , (n-C 3 H 7} NH 3) 2 PbI 4, (n-C 4 H 9 NH 3) 2 PbI 4, (C 6 H 5 NH 3) 2 PbI 4, (C 6 H 3 F 2 NH 3 ) ₂ PbI ₄ , (C ₆ F ₅ NH ₃ ) ₂ PbI ₄ , (C ₄ H ₃ SNH ₃ ) ₂ PbI ₄ .
_{Here, C} 4 _{H 3} SNH 3 in _{(C 4 H 3 SNH 3)} 2 PbI 4 is aminothiophene.

The perovskite light absorber represented by the formula (I) can be synthesized from MX ₂ and AX. For example, the said nonpatent literature 1 is mentioned. Also, Akihiro Kojima, Kenjiro Teshima, Yasuo Shirai, and Tsutomu Miyasaka, “Organometric Halide Perovskites as Visible Slightly.” Am. Chem. Soc. , 2009, 131 (17), 6050-6051.

  The amount of the perovskite light absorber used may be at least a part of the surface of the porous layer 12 on which light is incident, and is preferably an amount covering the entire surface.

2. Metal complex dye, organic dye
Metallic complex dye and an organic dye, any structure may be a compound having, but metal complex dye is preferably Ru metal complex dye and phthalocyanine dyes, Ru metal complex dye is more preferable. The organic dye is preferably a cyanine dye.

2a. Ru metal complex dye The Ru metal complex dye is not particularly limited, but a Ru metal complex dye represented by the following formula (DA), a Ru metal complex dye coordinated with a ligand of a bipyridine or terpyridine skeleton is preferable.
Among them, the Ru metal complex dye is preferably a Ru metal complex dye represented by the following formula (DA), wherein L2 is a ligand of a bipyridine skeleton or L3 is a ligand of a terpyridine skeleton, A Ru metal complex dye having an amino group in the molecule of the Ru metal complex dye is preferable.

Formula (DA)
Ru (L1) m1 (L2) m2 (L3) m3 · CI

  In the formula, L1 represents a monodentate ligand, L2 represents a bidentate ligand, and L3 represents a tridentate ligand. CI represents the counter ion when the counter ion is required to neutralize the charge. m1 represents an integer of 0 to 3, m2 represents an integer of 0 to 3, and m3 represents an integer of 0 to 2. However, m1 + m2 × 2 + m3 × 3 = 6.

  The monodentate ligand in L1 is not particularly limited, but is preferably a halogen ion, a cyanate anion, an isocyanate anion, a thiocyanate anion, an isothiocyanate anion, a selenocyanate anion, an isoselenocyanate anion, an isocyanate anion, an isothiocyanate anion, An isoselenocyanate anion is more preferred, and an isothiocyanate anion is particularly preferred.

  The bidentate ligand in L2 is not particularly limited, but bipyridine (particularly 2,2'-bipyridine), 2- (5-pyrazolyl) pyridine, and 1,3-diketone are preferable, and bipyridine is more preferable. L2 is more preferably bipyridine substituted with a carboxy group (particularly 4,4'-dicarboxy-2,2'-bipyridine). When it has two or more L2, it is preferable that at least one is bipyridine substituted by the carboxy group.

Although it does not specifically limit as a tridentate ligand in L3, Coordination in which three nitrogen-containing heteroaryl rings are bonded by a single bond between ring-constituting carbon atoms bonded to a nitrogen-constituting nitrogen atom of a nitrogen-containing heteroaryl ring A child is preferred. Examples of the nitrogen-containing heteroaryl ring include heterocycles having a nitrogen atom as a ring-constituting atom of the aromatic heterocycle or fused heterocycle of the heteroaryl group in R ^1a . L3 is particularly preferably terpyridine (particularly 2,2 ′: 6 ′, 2 ″ -terpyridine).
These nitrogen-containing heteroaryl rings are preferably substituted with a carboxy group, more preferably two or more nitrogen-containing heteroaryl rings are substituted with a carboxy group, and three nitrogen-containing heteroaryl rings are carboxy groups. More preferably, it is substituted with a group.
Of these, 4,4 ′, 4 ″ -tricarboxy-2,2 ′: 6 ′, 2 ″ -terpyridine is preferable.

CI includes Cl ⁻ , I ⁻ , CF ₃ SO ₃ ⁻ (TfO ⁻ ), PF ₆ ⁻ , H ⁺ , N (C ₄ H ₉ ) ₄ ⁺ (NBu ₄ ⁺ ), and Cl ⁻ , N (C ₄ H ₉ ) ₄ ⁺ is preferred.

The Ru metal complex dye preferably has an amino group in the molecule. When the Ru metal complex dye has an amino group in the molecule, the photoelectric conversion efficiency is improved. In particular, in the case of the above embodiments (ai) and (aii-1) in which the photosensitive layer 13 contains a light absorber, when a Ru metal complex dye having an amino group in the molecule is used in combination with the perovskite compound, the photoelectric conversion efficiency is improved. The effect becomes remarkable.
The amino group that the Ru metal complex dye preferably has is not particularly limited, but an amino group having at least one hydrogen atom bonded to a nitrogen atom (monosubstituted amino group or unsubstituted amino group) is preferable, and 2 bonded to the nitrogen atom. More preferred is an amino group having two hydrogen atoms (an unsubstituted amino group).
Examples of the substituent of the monosubstituted amino group include an alkyl group, an aryl group, and a heteroaryl group. The alkyl group, aryl group, and heteroaryl group are not particularly limited, but are the same as the alkyl group, aryl group, and heteroaryl group of R ^1a described above, and preferred ones are also the same.

Examples of the amino group that the Ru metal complex dye preferably has include, for example, unsubstituted amino (—NH ₂ ), alkylamino group (such as methylamino, ethylamino, n-hexylamino, 2-ethylhexylamino, or n-octadecylamino), An arylamino group (such as phenylamino or N-naphthylamino) or a heteroarylamino group (such as N-imidazolylamino, pyrrolylamino or thienylamino) can be mentioned. Unsubstituted amino is preferred.

In the amino group, a nitrogen atom may be directly bonded to the ligand L1, L2 or L3, or may be bonded to the ligand L1, L2 or L3 via a divalent linking group. Although it does not specifically limit as a bivalent coupling group, An alkylene group, alkenylene group, alkynylene group, arylene group, heteroaryl ring group, a carbonyl group, etc. are mentioned. Of these, a carbonyl group is preferred.
The ligand to which the amino group is bonded and the bonding position in the ligand are not particularly limited.

  As the amino group bonded to the ligand via a linking group, an unsubstituted amino group (carbamoyl group) having a carbonyl group is preferable.

Specific examples of Ru metal complex dyes are illustrated below, but the present invention is not limited thereby. In the following specific examples, Bu denotes a _-C 4 _{H 9.}

  In addition to the above, the Ru metal complex dye includes the Ru metal complex dye used in the following Examples, the Ru metal complex dye described in JP2013-084594A (in particular, the Ru metal described in paragraphs 0072 to 0081, etc.). Complex dyes), Ru metal complex dyes described in International Publication No. 2013/0888898 (in particular, Ru metal complex dyes described in Paragraph Nos. 0286 to 0293), and US Patent Application Publication No. 2012-0073660. Ru metal complex dyes (particularly, Ru metal complex dyes described in paragraphs 0033 to 0049) can also be preferably used in the present invention.

2b. Phthalocyanine dye The phthalocyanine dye contains a naphthalocyanine dye, and in the present invention, a phthalocyanine dye represented by the following formula (DB) is preferable.

In the formula, R ^{f1 to} R ^f16 each independently represent a hydrogen atom or a substituent, and among these, adjacent groups may be bonded to each other to form a ring. M ^II represents a metal atom or a metal oxide.

The substituent in R ^{f1 to} R ^f16 is not particularly limited, but an alkyl group, alkenyl group, alkynyl group, aryl group, heterocyclic group, alkoxy group, alkylthio group, amino group, alkylamino group, arylamino group, acyl group , Alkoxycarbonyl group, aryloxycarbonyl group, acylamino group, sulfonamido group, carbamoyl group, sulfamoyl group, halogen atom, cyano group, hydroxy group, carboxy group or sulfo group. R ^f1 , R ^f4 , R ^f5 , R ^f8 , R ⁹ , R ^f12 , R ^f13 and R ^f16 are each independently preferably a hydrogen atom, an alkyl group or an alkoxy group, and a hydrogen atom or a carbon number of 1 to 6 More preferred are alkoxy groups.

^Examples of the ring formed by the groups adjacent to R ^{f1 to} R ^f16 include an aromatic ring, an aliphatic ring, and a heterocyclic ring. As the aromatic ring, a benzene ring and a naphthalene ring are preferable. As the aliphatic ring, a cyclopentane ring and a cyclohexane ring are preferable. As the hetero ring, the ring ^exemplified for the heteroaryl group in R ^1a is preferable. In addition to the heteroaryl ring, the hetero ring is preferably a non-aromatic hetero ring. The non-aromatic heterocycle is preferably a 5- or 6-membered heterocycle having a nitrogen atom, an oxygen atom or a sulfur atom as the ring constituent atom. Examples of the 5-membered or 6-membered non-aromatic heterocycle include a tetrahydrothiophene ring, a tetrahydrofuran ring, a pyrrolidine ring, a pyrroline ring, an imidazolidine ring, a pyrazolidine ring, a piperidine ring, a piperazine ring, and a morpholine ring. The non-aromatic hetero ring is also preferably a ring in which a benzene ring is condensed to the 5-membered or 6-membered non-aromatic hetero ring.
R ^f2 and R ^f3 , R ^f6 and R ^f7 , R ¹⁰ and R ^f11 , R ^f14 and R ^f15 are preferably each independently bonded to form a benzene ring or a naphthalene ring.

As the metal atom ^{M II} is, Co, Ni, Cu, Zn or Pb are preferred. As the metal oxide, titanyloxy, vanadyloxy or molybdyloxy is preferable.

Hereinafter, you specific examples of the phthalocyanine dye. Incidentally, Bu is _-C 4 _{H 9.}

  In addition to the above, phthalocyanine dyes include phthalocyanine dyes described in JP-A-2007-2331040 (particularly phthalocyanine dyes described in paragraph No. 0029) and phthalocyanine dyes described in JP-A-2012-167189 (particularly in paragraphs). The phthalocyanine dyes described in Nos. 0036 to 0040 can also be preferably used in the present invention.

3. Cyanine dye The cyanine dye may be a cyanine dye having any structure, but a dye having a long absorption wavelength is preferable, a dye having an absorption wavelength of 600 nm or more is preferable, a dye having an absorption wavelength of 700 nm or more is more preferable, and 800 nm More preferred are dyes having an absorption wavelength. Especially, the pigment | dye which has an absorption wavelength in the range of 600-1500 nm is preferable, The pigment | dye which has an absorption wavelength in the range of 700-1400 nm is more preferable, The pigment | dye which has an absorption wavelength in the range of 800-1200 nm is further more preferable.
Here, the wavelength in the absorption of the dye in this specification is a wavelength in a state of being incorporated in the photosensitive layer 13. Specifically, the wavelength in the state incorporated in the photosensitive layer 13 is obtained by measuring the reflection spectrum.

  A preferred cyanine dye in the present invention is a cyanine dye represented by the following formula (DC).

In the formula, Q represents a tetravalent aromatic group, and X ¹ and X ² each independently represent a sulfur atom, an oxygen atom, or —C (Ra) (Rb) —. Here, Ra and Rb each independently represent a hydrogen atom, an aliphatic group, an aromatic group, or a heterocyclic group bonded with a carbon atom, and these may be substituted. R ^D1 and R ^D2 each independently represent an aliphatic group, an aromatic group or a heterocyclic group bonded with a carbon atom, and these may be substituted. P ¹ and P ² each independently represent a dye residue, which may be the same or different from each other. W ¹ represents a counter ion as necessary to neutralize the charge.
In the formula (DC), the aromatic group may be a group having aromaticity, for example, a group consisting of an aromatic ring described in the above R ^{f1 to} R ^f16 or a heteroaryl group described in the above R ^1a Etc. The aromatic group is a group formed by removing a hydrogen atom so as to match the valence of the group in the formula (DC).
The aliphatic group may be any group that does not have aromaticity, such as an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an alkylthio group, an alkylamino group, an alkoxycarbonyl group, an acylamino group, a sulfonamide group, and a carbamoyl group. Group, a sulfamoyl group, or a group composed of an aliphatic ring or a non-aromatic heterocycle described in R ^{f1 to} R ^f16 above. Especially, an alkyl group is preferable and a C1-C10 alkyl group is more preferable.

P ¹ and P ² are preferably groups represented by the following formula (a) or (b).

In the formula, V ^a1 represents a substituent.
n represents an integer of 0 to 4, n is preferably an integer of 0 to 2, and 0 or 1 is more preferable.
When n is 2 or more, the plurality of V ^a1 may be the same or different, or may be bonded to each other to form a ring.
Y represents —S—, —N (R ^a9 ) — or —C (R ^a11 ) (R ^a12 ) —. Here, R ^a9 represents a hydrogen atom, an aliphatic group, an aromatic group, or a heterocyclic group bonded with a carbon atom. R ^a11 and R ^a12 each independently represent a hydrogen atom, an aliphatic group, an aromatic group, or a heterocyclic group bonded by a carbon atom, which may be the same or different and are bonded to each other to form a ring. Also good.
Z represents an aliphatic group, an aromatic group, or a heterocyclic group bonded with a carbon atom, and may have a substituent. Z is preferably an alkyl group.
R ^{a3 to} R ^a6 and R ^a8 each independently represent a hydrogen atom, an aliphatic group, an aromatic group or a heterocyclic group, and these may have a substituent.
R ^a7 represents an oxygen atom and a divalent carbon atom in which the sum of σp in the Hammett rule of the two substituents to be bonded is positive.

The substituent in V ^a1 is an alkyl group, alkenyl group, alkynyl group, aryl group, heterocyclic group, alkoxy group, alkylthio group, amino group, alkylamino group, arylamino group, acyl group, alkoxycarbonyl group, aryloxycarbonyl. Group, acylamino group, sulfonamido group, carbamoyl group, sulfamoyl group, halogen atom, cyano group, hydroxy group, carboxy group or sulfo group.

The aliphatic group and the aromatic group in R ^{a3 to} R ^a6 , R ^a8 , R ^a9 , R ^a11 and R ^{a12 have the same meanings as} the aliphatic group and the aromatic group described in the above formula (DC). The heterocyclic group in R ^{a3 to} R ^a6 , R ^a8 , R ^a9 , R ^a11 and R ^a12 is preferably a group consisting of a heterocyclic ring in R ^{f1 to} R ^f16 . R ^{a3 to} R ^a6 and R ^a8 are each preferably a hydrogen atom, and R ^a9 , R ^a11 and R ^a12 are each preferably an alkyl group.
Q is preferably a tetravalent benzene ring group or a naphthalene ring group.
R ^a7 preferably has an oxygen atom and the following structure, and more preferably an oxygen atom.

Examples of W ¹ include CI in the above formula (DA), and the preferred range is also the same.

Hereinafter, you Specific examples of the cyanine dye.

  In addition to the above, the cyanine dye represented by the formula (DC) is also a cyanine dye described in JP 2012-144688 A (in particular, a cyanine dye described in paragraphs 0039 to 0046 and paragraphs 0054 to 0060). It can be preferably used.

The light absorber II is preferably a dye having absorption at 800 nm or more, and more preferably a dye having absorption in the range of 800 nm to 1200 nm.
In the present invention, a Ru metal complex dye having an amino group in the molecule is used as the light absorber II.

3. Light absorber I and light absorber II
In the present invention, if the light absorber I and the light absorber II are contained in the photosensitive layer 13 so that the photosensitive layer 13 exhibits the above function, the content (use amount) and the content of each light absorber. The amount ratio is not particularly limited. The photosensitive layer containing the light absorber I can be formed thick. For example, it may be the film thickness of the photosensitive layer. On the other hand, the photosensitive layer made of the light absorber II is usually thin and formed, for example, in the form of a monomolecular film.

<Hole transport layer 3>
The hole transport layer 3 has a function of replenishing electrons to the oxidant of the light absorber, and is preferably a solid layer. The hole transport layer 3 is preferably provided between the photosensitive layer 13 of the first electrode 1 and the second electrode 2.

The hole transport material for forming the hole transport layer 3 is not particularly limited, but is an inorganic material such as CuI or CuNCS, and the organic hole transport material described in JP-A-2001-291534, paragraphs 0209-0212. Etc. The organic hole transport material is preferably a conductive polymer such as polythiophene, polyaniline, polypyrrole and polysilane, a spiro compound in which two rings share a tetrahedral structure such as C and Si, and triarylamine. And aromatic amine compounds such as triphenylene compounds, nitrogen-containing heterocyclic compounds, and liquid crystalline cyano compounds.
The hole transport material is preferably an organic hole transport material that can be applied by a solution and becomes a solid. Specifically, 2,2 ′, 7,7′-tetrakis- (N, N-di-p-methoxyphenyl) is preferable. Amine) -9,9-spirobifluorene (also referred to as Spiro-OMeTAD), poly (3-hexylthiophene-2,5-diyl), 4- (diethylamino) benzaldehyde diphenylhydrazone, polyethylenedioxythiophene (PEDOT), etc. Is mentioned.

  Although the film thickness of the positive hole transport layer 3 is not specifically limited, 50 micrometers or less are preferable, 1 nm-10 micrometers are more preferable, 5 nm-5 micrometers are further more preferable, and 10 nm-1 micrometer are especially preferable. The film thickness of the hole transport layer 3 corresponds to the distance between the second electrode 2 and the surface of the porous layer 12 or the surface of the photosensitive layer 13. This film thickness can be measured by observing the cross section of the photoelectric conversion element 10 using a scanning electron microscope (SEM) or the like.

  In the present invention, the total film thickness of the porous layer 12, the photosensitive layer 13, and the hole transport layer 3 is not particularly limited, but is preferably 0.1 to 200 μm, more preferably 0.5 to 50 μm, and 0 More preferably, it is 5-5 micrometers.

<Second electrode 2>
The second electrode 2 functions as a positive electrode in the solar cell. The 2nd electrode 2 will not be specifically limited if it has electroconductivity, Usually, it can be set as the same structure as the electroconductive support body 11. FIG. If the strength is sufficiently maintained, the support 11a is not necessarily required.
The structure of the second electrode 2 is preferably a structure having a high current collecting effect. In order for light to reach the photosensitive layer 13, at least one of the conductive support 11 and the second electrode 2 must be substantially transparent. In the solar cell of this invention, it is preferable that the electroconductive support body 11 is transparent and sunlight is entered from the support body 11a side. In this case, it is more preferable that the second electrode 2 has a property of reflecting light.

Examples of the material for forming the second electrode 2 include platinum (Pt), gold (Au), nickel (Ni), copper (Cu), silver (Ag), indium (In), ruthenium (Ru), palladium ( Examples thereof include metals such as Pd), rhodium (Rh), iridium (Ir), and osnium (Os), the above-described conductive metal oxides, and carbon materials. The carbon material may be a conductive material formed by bonding carbon atoms to each other, and examples thereof include fullerene, carbon nanotube, graphite, and graphene.
The second electrode 2 is preferably glass or plastic having a metal or conductive metal oxide thin film (including a thin film formed by vapor deposition), glass having a thin film of Au or Pt, or glass vapor-deposited with Pt. Is particularly preferred.

  The film thickness of the 2nd electrode 2 is not specifically limited, 0.01-100 micrometers is preferable, 0.01-10 micrometers is more preferable, 0.01-1 micrometer is especially preferable.

<Other configurations>
In the present invention, in order to prevent contact between the first electrode 1 and the second electrode 2, a spacer or a separator can be used instead of the blocking layer 14 or together with the blocking layer 14.
A hole blocking layer may be provided between the second electrode 2 and the hole transport layer 3.

<< Solar cell >>
The solar cell of this invention is comprised so that the photoelectric conversion element of this invention may work with respect to the external circuit 6, as FIG. 1 and FIG. 2 shows, for example. The external circuit connected to the first electrode 1 (conductive support 11) and the second electrode 2 can be used without particular limitation.
In the solar cell of the present invention, it is preferable to seal the side surface with a polymer, an adhesive or the like in order to prevent deterioration of the components and transpiration.
The solar cell to which the photoelectric conversion element of the present invention is applied is not particularly limited, and examples thereof include solar cells described in Patent Document 1, Non-Patent Documents 1 and 2.

<< Photoelectric Conversion Element and Solar Cell Manufacturing Method >>
The photoelectric conversion element and solar cell of the present invention can be produced according to known production methods, for example, the methods described in Patent Document 1, Non-Patent Documents 1 and 2, and the like.
Below, the manufacturing method of the photoelectric conversion element and solar cell of this invention is demonstrated easily.

If desired, a blocking layer 14 and a porous layer 12 are formed on the surface of the conductive support 11.
The blocking layer 14 can be formed by, for example, a method of applying a dispersion containing the insulating material or a precursor compound thereof on the surface of the conductive support 11 and baking it, or a spray pyrolysis method.

The material forming the porous layer 12 is preferably used as fine particles, and more preferably used as a dispersion containing fine particles.
The method for forming the porous layer 12 is not particularly limited, and examples thereof include a wet method, a dry method, and other methods [for example, a method described in Chemical Review, Vol. 110, page 6595 (2010)]. Can be mentioned. In these methods, it is preferable that the dispersion (paste) is applied to the surface of the conductive support 11 or the surface of the blocking layer 14 and then baked at a temperature of 100 to 800 ° C. for 10 minutes to 10 hours. Thereby, microparticles | fine-particles can be stuck.
When firing is performed a plurality of times, the firing temperature other than the last firing (the firing temperature other than the last firing) is preferably performed at a temperature lower than the last firing temperature (the last firing temperature). For example, when a titanium oxide paste is used, the firing temperature other than the last can be set within a range of 50 to 300 ° C. Moreover, the last baking temperature can be set so that it may become higher than the baking temperature other than the last within the range of 100-600 degreeC. When a glass support is used as the support 11a, the firing temperature is preferably 60 to 500 ° C.

The amount of the porous material applied when forming the porous layer 12 is appropriately set according to the thickness of the porous layer 12 to be formed, the number of times of application, and the like, and is not particularly limited. The coating amount of the porous material per 1 m ² of the surface area of the conductive support 11 is preferably, for example, 0.5 to 500 g, and more preferably 5 to 100 g.

Next, the photosensitive layer 13 is provided.
The photosensitive layer 13 can be formed by an appropriate method depending on the above-described aspect of the photosensitive layer to be provided.
For example, the photosensitive layer 13a of the above embodiment (ai) can be formed by applying (ai) a light absorbent solution containing the light absorbents I and II onto the porous layer 12. In addition, the photosensitive layers 13b and 13c of the above aspect (aii-1) or (aii-2) each have a light absorption containing either one of the light absorbers I and II on the porous layer 12 (aii). After applying the agent solution, a film can be formed by applying a light absorber solution containing the other of the light absorbers I and II. Further, the photosensitive layers 13d and 13e of the above-described embodiment (b) are formed by applying a light absorbent solution containing either one of the light absorbents I and II onto the porous layer 12 and then transporting holes. A film can be formed by providing an intermediate layer containing the material and further applying a light absorbent solution containing the other of the light absorbents I and II. The intermediate layer 13s can be formed in the same manner as the film forming method of the hole transport layer 3 described later.

Here, the light absorbent solution containing the light absorbent I may be a solution containing the light absorbent I itself, but the cation A, metal, which is a component of the light absorbent I represented by the formula (I) A solution containing a cation M and an anion X or a solution containing MX ₂ and AX is preferable. When a solution containing MX ₂ and AX is used as the light absorber solution, this solution is applied onto the porous layer 12 and dried to form a perovskite compound represented by the formula (I). A photosensitive layer 13 containing a perovskite compound is formed.

A hole transport material solution containing a hole transport material is applied onto the photosensitive layer 13 thus provided, and dried to form the hole transport layer 3.
The concentration of the hole transport material is 0.1 to 1.0 M (mol / L) in that the hole transport material solution is excellent in applicability and easily penetrates into the pores of the porous layer 12. Is preferred.

  After forming the hole transport layer 3, the second electrode 2 is formed, and a photoelectric conversion element and a solar cell are manufactured.

  The film thickness of each layer can be adjusted by appropriately changing the concentration of each dispersion or solution and the number of coatings. For example, when the thick photosensitive layer 13B shown in FIG. 2 is provided, the dispersion may be applied and dried several times.

  Each of the dispersions and solutions described above may contain additives such as a dispersion aid and a surfactant, if necessary.

  Examples of the solvent or dispersion medium used in the method for manufacturing a photoelectric conversion element and a solar cell include, but are not limited to, the solvents described in JP-A No. 2001-291534. In the present invention, an organic solvent is preferable, and an alcohol solvent, an amide solvent, a nitrile solvent, a hydrocarbon solvent, a lactone 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. Specifically, methanol, ethanol, γ-butyrolactone, chlorobenzene, acetonitrile, dimethylformamide (DMF) or dimethylacetamide, or a mixed solvent thereof is preferable.

  The application method of the solution or dispersant forming each layer is not particularly limited, and spin coating, extrusion die coating, blade coating, bar coating, screen printing, stencil printing, roll coating, curtain coating, spray coating, dip coating, inkjet A known coating method such as a printing method or a dipping method can be used. Of these, spin coating, screen printing, dipping, and the like are preferable.

  The solar cell is manufactured by connecting an external circuit to the first electrode 1 and the second electrode 2 of the photoelectric conversion element manufactured as described above.

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

  The photoelectric conversion element 10A and the solar cell shown in FIG. 1 were manufactured by the following procedure. In addition, when the film thickness of the photosensitive layer 13 is large, it corresponds to the photoelectric conversion element 10B and the solar cell shown in FIG.

Example 1
The photoelectric conversion element 10 and the solar cell shown in FIG. 1 were manufactured by the following procedure.

  The perovskite type light absorber and the light absorber II of the light absorber I used were as follows.

(Manufacture of photoelectric conversion elements and solar cells)
<Preparation of solution for blocking layer>
A 15% by mass isopropanol solution of titanium diisopropoxide bis (acetylacetonate) (Aldrich) was diluted with 1-butanol to prepare a 0.02M blocking layer solution.

<Deposition of blocking layer 14>
A fluorine-doped SnO ₂ conductive film (transparent electrode 11b) was formed on a glass substrate (support 11a, thickness 2.2 mm) to produce a conductive support 11. A blocking layer 14 (thickness 0.05 μm) was formed on the SnO ₂ conductive film at 450 ° C. by spray pyrolysis using the prepared 0.02M blocking layer solution.

<Deposition of porous layer>
The porous layer 12 was formed using the porous material shown in Table 1 as follows.
(Deposition of titanium oxide porous layer)
1. Preparation of titanium oxide titanium oxide paste (TiO _2, anatase, average particle size 20 nm) in ethanol dispersion of ethylcellulose, the addition of lauric acid and terpineol was prepared titanium oxide paste.
2. Formation of Titanium Oxide Porous Layer On the blocking layer 14, the prepared titanium oxide paste was applied by screen printing and baked. The titanium oxide paste was applied and fired twice. As the firing temperature, the first firing was performed at 130 ° C., and the second firing was performed at 500 ° C. for 1 hour. The obtained sintered body of titanium oxide was immersed in a 40 mM TiCl ₄ aqueous solution and then heated at 60 ° C. for 1 hour and then at 500 ° C. for 30 minutes to form a porous layer 12 (thickness 1.. 0 μm) was formed.

(Preparation of alumina porous layer)
1. Preparation of Alumina Paste A 10% by mass aqueous dispersion of alumina particles (average particle size 20 nm) was centrifuged, and water in the separated solution was replaced with ethanol. Terpineol and ethyl cellulose were added to the obtained alumina dispersion, and the concentration was adjusted by a concentration operation to obtain an alumina paste.
2. Formation of Alumina Porous Layer On the blocking layer 14, the prepared alumina paste was applied by screen printing and baked. The film thickness was adjusted by repeating the coating and baking steps. The firing conditions were 550 ° C. and 0.5 hour. In this way, a porous layer 12 (film thickness: 1.0 μm) made of alumina was formed.

<Formation of photosensitive layer 13A>
On the porous layer 12 formed as described above, any one of the following photosensitive layer preparation methods 1 to 5 using the following light absorbent solutions IA to IC and II (see Table 1). ) To form a photosensitive layer 13, thereby producing the first electrode 1.

(Preparation of light absorber solution IA)
A 40% methanol solution of methylamine (27.86 mL) and an aqueous solution of 57% by mass of hydrogen iodide (hydroiodic acid, 30 mL) were stirred in a flask at 0 ° C. for 2 hours, and then concentrated to obtain CH _3. A crude NH ₃ I was obtained. The obtained crude CH ₃ NH ₃ I was dissolved in ethanol and recrystallized from diethyl ether. The precipitated crystals were collected by filtration and dried under reduced pressure at 60 ° C. for 24 hours to obtain purified CH ₃ NH ₃ I.
Next, purified CH ₃ NH ₃ I and PbI ₂ were stirred and mixed in γ-butyrolactone at a molar ratio of 2: 1 at 60 ° C. for 12 hours, and then filtered through a polytetrafluoroethylene (PTFE) syringe filter to obtain a light absorber. A light absorbent solution IA containing 40% by mass of I-1a was prepared.

(Preparation of light absorber solution IB)
Formamidine acetate and an aqueous solution of 57% by mass of hydrogen iodide containing 2 equivalents of hydrogen iodide with respect to formamidine acetate were stirred in a flask at 0 ° C. for 1 hour, and then heated to 50 ° C. The mixture was further stirred for 1 hour and mixed. The obtained solution was concentrated to obtain a crude formamidine hydrogen iodide. The obtained crude product was recrystallized with diethyl ether, and the precipitated crystals were collected by filtration and dried under reduced pressure at 50 ° C. for 10 hours to obtain purified formamidine hydrogen iodide salt.
Next, purified formamidine hydrogen iodide and PbI ₂ were mixed at a molar ratio of 2: 1 in dimethylformamide (DMF) with stirring at 60 ° C. for 3 hours, and then with a polytetrafluoroethylene (PTFE) syringe filter. Filtration was performed to prepare a light absorbent solution IB containing 40% by mass of the light absorbent I-1b.

(Preparation of light absorber solution IC)
A 40% ethanol solution of ethylamine and an aqueous solution of 57% by mass of hydrogen iodide were stirred in a flask at 0 ° C. for 2 hours and then concentrated to obtain a CH ₃ CH ₂ NH ₃ I crude product. The obtained crude product was dissolved in ethanol and recrystallized from diethyl ether. The precipitated crystals were collected by filtration and dried under reduced pressure at 60 ° C. for 12 hours to obtain purified CH ₃ CH ₂ NH ₃ I.
Next, purified CH ₃ CH ₂ NH ₃ I and PbI ₂ were mixed at a molar ratio of 3: 1 in dimethylformamide (DMF) with stirring at 60 ° C. for 5 hours, and then passed through a polytetrafluoroethylene (PTFE) syringe filter. Filtration was performed to prepare a light absorbent solution IC containing 40% by mass of the light absorbent I-2a.

(Preparation of light absorber solution II)
The light absorbers II (D-1 to D-7, respectively) shown in Table 1 below were dissolved in γ-butyrolactone so that the concentration was 0.2 mM, and each of the light absorber solutions II-1 to II- was dissolved. 7 were prepared respectively.

Photosensitive layer preparation method 1 (Aspect of photosensitive layer to be formed (aii-2), FIG. 3C)
Each of the light absorbent solutions II-1 to II-7 (0.1 mL) containing the light absorbent II shown in Table 1 on the porous layer 12 formed on the conductive support 11 was spin-coated. (60 seconds at 2000 rpm, followed by 60 seconds at 3000 rpm). Each applied light absorber solution was dried at 100 ° C. for 2 minutes by a hot plate to form a first photosensitive layer 13c1 containing the light absorber II.
Next, a light absorbent solution IA, IB or IC (0.1 mL) containing the light absorbent I shown in Table 1 was applied to the spin coat method (2000 rpm for 60 seconds, followed by 3000 rpm for 60 seconds). ) On the first photosensitive layer 13c1. Each applied light absorber solution was dried on a hot plate under the following drying conditions to form a second photosensitive layer 13c2 having a perovskite compound represented by the following formula.
Drying conditions and perovskite compound absorbent solution IA: temperature 100 ° C., time 20 minutes, CH ₃ NH ₃ PbI ₃
Absorbent solution IB: temperature 160 ° C., time 40 minutes, [CH (═NH) NH ₃ ] PbI ₃
Absorbent solution IC: temperature 140 ° C., time 40 minutes, (CH ₃ CH ₂ NH ₃ ) ₂ PbI ₄

  In this manner, a photosensitive layer 13c (film thickness: 1.1 μm) composed of the first photosensitive layer 13c1 and the second photosensitive layer 13c2 was formed, and the first electrode 1 was produced.

Photosensitive layer preparation method 2 (photosensitive layer form (ai) to be formed, FIG. 3A)
Each of the light absorbent solution IA containing the light absorbent I-1a and the light absorbent solutions II-1 to II-5 (0.1 mL) containing the light absorbent II shown in Table 1 in volume A light absorber mixed solution was prepared by mixing at a ratio of 1/1.
The light absorbent mixed solution was applied on the porous layer 12 formed on the conductive support 11 by a spin coating method (1500 rpm for 60 seconds, followed by 2000 rpm for 60 seconds). Each applied light absorber mixed solution was dried with a hot plate at a temperature of 100 ° C. for 20 minutes. In this manner, a photosensitive layer 13a (thickness: 1.1 μm) containing a perovskite compound represented by CH ₃ NH ₃ PbI ₃ and any of the light absorbers D-1 to D-5 was formed. One electrode 1 was produced.

Photosensitive layer preparation method 3 (aspect of photosensitive layer to be formed (aii-1), FIG. 3B)
On the porous layer 12 formed on the conductive support 11, the light absorbent solution IA (0.1 mL) containing the light absorbent I-1a is continuously applied by spin coating (at 2000 rpm for 60 seconds). For 60 seconds at 3000 rpm). The applied light absorbent solution IA was dried with a hot plate at 100 ° C. for 20 minutes to form a first photosensitive layer 13b1 containing a perovskite compound represented by CH ₃ NH ₃ PbI ₃ .
Next, each of the light absorbent solutions II-1 to II-5 (0.1 mL) containing the light absorbent II shown in Table 1 was prepared by spin coating (2000 rpm for 60 seconds, followed by 3000 rpm for 60 seconds). One photosensitive layer 13b1 was applied. Each of the applied light absorbent solutions was dried with a hot plate at a temperature of 100 ° C. for 5 minutes to form a second photosensitive layer 13b2 containing the light absorbent II.

  In this manner, a photosensitive layer 13b (film thickness: 1.1 μm) composed of the first photosensitive layer 13b1 and the second photosensitive layer 13b2 was formed, and the first electrode 1 was produced.

Photosensitive layer preparation method 4 (photosensitive layer form (bi), FIG. 3D)
On the porous layer 12 formed on the conductive support 11, the light absorbent solution IA (0.1 mL) containing the light absorbent I-1a is continuously applied by spin coating (at 2000 rpm for 60 seconds). For 60 seconds at 3000 rpm). The applied light absorbent solution IA was dried for 2 minutes at 100 ° C. by a hot plate, and the first photosensitive layer 13d1 (thickness 1.1 μm) containing a perovskite compound represented by CH ₃ NH ₃ PbI ₃ was used. ) Was formed.
Subsequently, Spiro-OMeTAD (180 mg) as a hole transport material was dissolved in chlorobenzene (1 mL). To this chlorobenzene solution, an acetonitrile solution (37.5 μL) in which lithium-bis (trifluoromethanesulfonyl) imide (170 mg) was dissolved in acetonitrile (1 mL) and t-butylpyridine (TBP, 17.5 μL) were added. By mixing, an intermediate layer solution was prepared. Next, an intermediate layer solution (0.1 mL) prepared on the formed first photosensitive layer 13d1 was applied by spin coating and dried to form an intermediate layer 13s (film thickness 50 nm).
Furthermore, each of the light absorber solutions II-1 to II-5 (0.05 mL) containing the light absorber II shown in Table 1 is spin-coated (at 2000 rpm for 60 seconds and subsequently at 3000 rpm for 60 seconds), It apply | coated on the intermediate | middle layer 13s. Each applied light absorber solution was dried at 50 ° C. for 2 minutes by a hot plate to form a second photosensitive layer 13d2 (thickness of 10 nm or less) containing the light absorber II.

  Thus, the photosensitive layer 13d which consists of the 1st photosensitive layer 13d1, the intermediate | middle layer 13s, and the 2nd photosensitive layer 13d2 was formed into a film, and the 1st electrode 1 was produced.

Photosensitive layer preparation method 5 (mode of photosensitive layer to be formed: light absorber I only)
On the porous layer 12 formed on the conductive support 11, the light absorbent solution IA (0.1 mL) containing the light absorbent I-1a is continuously applied by spin coating (at 2000 rpm for 60 seconds). For 60 seconds at 3000 rpm). The applied light absorber solution IA was dried on a hot plate at 100 ° C. for 20 minutes, and the first photosensitive layer containing a perovskite compound represented by CH ₃ NH ₃ PbI ₃ (thickness: 1.1 μm) A photosensitive layer consisting only of was formed.

<Preparation of hole transport material solution>
Spiro-OMeTAD (180 mg) as a hole transport material was dissolved in chlorobenzene (1 mL). To this chlorobenzene solution, an acetonitrile solution (37.5 μL) in which lithium-bis (trifluoromethanesulfonyl) imide (170 mg) was dissolved in acetonitrile (1 mL) and t-butylpyridine (TBP, 17.5 μL) were added. A hole transport material solution was prepared by mixing.

<Film Formation of Hole Transport Layer 3>
Next, the prepared hole transport material solution (0.1 mL) is applied onto the photosensitive layer 13 of the first electrode 1 by spin coating, and the applied hole transport material solution is dried to form a hole transport layer. 3 (film thickness 0.1 μm) was formed.

<Preparation of the second electrode 2>
Gold was vapor-deposited on the hole transport layer 3 by the vapor deposition method, and the 2nd electrode 2 (film thickness of 0.3 micrometer) was produced.
Thus, the photoelectric conversion element and the solar cell were manufactured.

  Here, according to the above method, each film thickness was observed with an SEM, an average of 10 sections within the observation range was obtained, and this value was taken as the film thickness.

(Measurement of IPCE)
Each of the solar cells produced as described above was measured for IPCE (quantum yield) at a wavelength of 300 to 1000 nm with an IPCE measuring device (Peccell). Of these, IPCE values at 600 nm and 800 nm were used for IPCE evaluation.
Based on the IPCE values of comparative sample numbers c11 and c12 containing only the perovskite type light absorber (I-1a) of the light absorber I in the photosensitive layer 13, the light absorber I and the light absorber II were used in combination. From the IPCE values of the sample numbers 101 to 128, the IPCE increase rates of the sample numbers 101 to 126 were obtained by the following formula.
In each of the sample numbers 101 to 128, when the porous layer 12 was formed of titanium oxide, the reference sample number c11 was used as a reference, and when the porous layer 12 was formed of aluminum oxide, the reference sample number c12 was used as a reference.

  IPCE increase rate (%) = [(IPCE value of sample using both light absorber I and light absorber II−IPCE value of sample containing only light absorber I) / Sample containing only light absorber I Value of IPCE] × 100

Evaluation standard of IPCE increase rate at 600 nm A: 5% or more B: 3% or more and less than 5% C: 1% or more and less than 3% D: 0% or more and less than 1%

Evaluation standard of IPCE increase rate at 800 nm A: 300% or more B: 200% or more and less than 300% C: 100% or more and less than 200% D: 0% or more and less than 100%

Here, it is a target achievement level that both IPCE increase rates of 600 nm and 800 nm are C or more, and practically, it is preferably A or B.
The results obtained are summarized in Table 1 below.

From the results shown in Table 1, the solar cells of the present invention (sample numbers 103, 108, 113, 118, 121 to 124 ) using the light absorbent I and the light absorbent II of the present invention in combination have the light absorbent I (I It can be seen that IPCE is improved at both wavelengths of 600 nm and 800 nm as compared with solar cells (sample numbers c11 and c12) using -Ia) alone.
This multi-porous layer 12 be formed by any of the TiO ₂ or alumina, the solar cell (sample No. c11 and c12), are the same.
Further, in the solar cell of the invention described above, improves the light absorbing agent I is Ri compound der represented by formula (I-1), with respect to solar cells (sample numbers c11 and c12), IPCE is You can see that
Furthermore, the solar cell (sample numbers 103, 108, 113, 118, 121 to 124 ) of the present invention is the same as the solar cell (sample numbers c11 and c12) in any of the production methods 1 to 4 of the photosensitive layer 13. It can be seen that IPCE is improved.
In addition, in the photosensitive layer manufacturing methods 2 and 3, the solar cell of the present invention (sample number 108, sample No. 108, in which Ru metal complex dye (D-3) having an amino group in the molecule as the light absorber II is used in combination with the light absorber I. 113, 122, and 123) are found to have a higher effect of improving the photoelectric conversion efficiency than other photosensitive layer preparations.
On the other hand, the solar cells (sample numbers c11 and c12) provided with the photosensitive layer containing only the light absorber I (I-Ia) all had low IPCE.

1A, 1B 1st electrode 11 Conductive support 11a Support 11b Transparent electrode 12 Porous layer 13A, 13B, 13a-13e Photosensitive layer (light absorption layer)
13b1, 13c2, 13d1, 13e2 First photosensitive layer 13b2, 13c1, 13d2, 13e1 Second photosensitive layer 13s Intermediate layer 14 Blocking layer 2 Second electrode 3A, 3B Hole transport layer 6 External circuit (lead)
10A, 10B Photoelectric conversion element 100A, 100B System M applying photoelectric conversion element for battery use Electric motor

Claims (13)

A first electrode having a porous layer provided on a conductive support, and a photosensitive layer containing a light absorber on the porous layer, a second electrode facing the first electrode, and the first electrode And a hole transport layer provided between the second electrode and a photoelectric conversion element,
The light absorber includes at least two light absorbers I and II, and the light absorber I is a cation of the periodic table group 1 element or the cationic organic group A, or a metal atom other than the periodic table group 1 element. at least one compound having a perovskite crystal structure having an anion of the M cations and anionic atom X, light absorbing agent II is, photoelectric conversion element is a Ru metal complex color element having an amino group in the molecule . The Ru metal complex dye, photoelectric conversion element according to claim 1 ligand bipyridine or terpyridine skeleton is coordinated the Ru metal complex dye. The photosensitive layer has (a) at least one of the light absorbers I and II on the porous layer, or (b) the light absorbers I and II on the surface of the porous layer. has either, photoelectric conversion element according to claim 1 or 2 via the intermediate layer having the other one of said light-absorbing agent I and II containing a hole transport material. The photosensitive layer has (a) at least one of the light absorbers I and II on the porous layer, and (ai) the light absorbers I and II are both in contact with the surface of the porous layer. a Te, or either (aii) the light absorber I and II has contact with the porous layer, according to claim 1 to 3 in which the other has been laminated on one of the light absorbing agent said The photoelectric conversion element of any one of these. The photoelectric conversion element according to any one of claims 1 to 4 , wherein the compound having a perovskite crystal structure is a compound represented by the following formula (I).
Formula (I): A _a M _m X _x
In the formula, A represents a group 1 element of the periodic table or a cationic organic group. M represents a metal atom other than the first group element of the periodic table. X represents an anionic atom. a represents 1 or 2, m represents 1, and a, m, and x satisfy a + 2m = x. Said compound having a perovskite crystal structure, the photoelectric conversion device according to any one of claims 1 to 5 including a compound represented by the following formula (I-1).
Formula (I-1): AMX ₃
In the formula, A represents a group 1 element of the periodic table or a cationic organic group. M represents a metal atom other than the first group element of the periodic table. X represents an anionic atom. Said compound having a perovskite crystal structure, the photoelectric conversion device according to any one of claims 1 to 5 including a compound represented by the following formula (I-2).
Formula (I-2): A ₂ MX ₄
In the formula, A represents a group 1 element of the periodic table or a cationic organic group. M represents a metal atom other than the first group element of the periodic table. X represents an anionic atom. Wherein A is a photoelectric conversion device according to any one of claims 1 to 7, which is a cationic organic group represented by the following formula (I-3).
Formula (I-3): R ^1a —NH ₃
In the formula, R ^1a represents a substituent. The photoelectric conversion element according to claim 8 , wherein R ^1a is an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an aryl group, a heteroaryl group, or a group that can be represented by the following formula (I-4).

In formula, ^Xa represents NR ^<1c> , an oxygen atom, or a sulfur atom. R ^1b and R ^1c each independently represent a hydrogen atom or a substituent. * Represents a bonding position with N in the formula (I-3). Wherein X is a photoelectric conversion device according to any one of claims 1 to 9, which is a halogen atom. Wherein M is a photoelectric conversion device according to any one of claims 1-10 is at least one of Pb and Sn. Solar cell comprising the photoelectric conversion device according to any one of claims 1 to 11. A manufacturing method of a photoelectric conversion device according to any one of claims 1 to 11, and the photosensitive layer, the surface of the porous layer, the light containing (ai) the light absorbing agent I and II (Iii) Applying a light absorber solution containing one of the light absorbers I and II, and then applying a light absorber solution containing the other light absorber Or (b) after applying a light absorber solution containing any one of the light absorbers I and II, an intermediate layer made of a hole transport material is provided, and the light absorber I and The manufacturing method of the photoelectric conversion element which apply | coats the light absorber solution containing the other of II, and forms into a film.

Images