JP2020077775A - Hole transport agent, composition for forming hole transport layer, method for forming hole transport film, photoelectric conversion element, and solar cell - Google Patents

Abstract

To provide a hole transport agent capable of suppressing variation in the amount of decrease in photoelectric conversion efficiency between elements, a composition for forming a hole transport layer including the hole transport agent, a method for forming a hole transport film capable of suppressing variations in the amount of decrease in photoelectric conversion efficiency, and a photoelectric conversion element and a solar cell in which variation in the amount of decrease in photoelectric conversion efficiency between elements is small.SOLUTION: There are provided a hole transfer agent including a compound having a group represented by a specific formula, a composition for forming a hole transport layer including the hole transport agent, a method for forming a hole transport film which applies the composition, and a photoelectric conversion element and a solar cell provided with the hole transporting layer including the hole transporting agent including the compound.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a hole transporting agent, a composition for forming a hole transporting layer, a method for forming a hole transporting film, a photoelectric conversion element and a solar cell.

  Photoelectric conversion elements are used in various optical sensors, copying machines, solar cells, and the like. The solar cell is expected to be put into practical use in full scale, as it uses non-depleting solar energy. Among them, a solar cell using a metal halide as a compound having a perovskite type crystal structure (hereinafter, also referred to as a perovskite compound) is attracting attention because it can achieve relatively high photoelectric conversion efficiency (for example, Non-Patent Document 1).

  In such a solar cell, research and development are being conducted not only on the perovskite compound but also on the hole transport layer and the compound forming the hole transport layer. For example, Non-Patent Document 2 describes a polymer such as poly [bis (4-phenyl) (2,4,6-trimethylphenyl) amine] (PTAA) as a hole transport material forming a hole transport layer. Has been done. Further, Patent Document 1 describes an aromatic amine derivative which is a low molecular weight compound as a suitable compound for forming a charge transport layer of a photoelectric conversion element, although it is not used in combination with a perovskite compound as a light absorber. There is.

JP, 2013-149446, A

Science, 2012, vol. 338, p. 643-647 Dalton Trans. , 2014, 43, p. 5247-5251

  It is known that the perovskite compound used as a light absorber generally has insufficient stability to water and is easily decomposed. A solar cell using such a perovskite compound as a light absorber has a photoelectric conversion efficiency between elements even if a hole transport layer having a hydrophobic property is used to form a hole transport layer under the same conditions and methods. It has been found that there is a problem (variation in humidity resistance and durability) that the amount of decrease in the electric field greatly varies (the decrease behavior of the photoelectric conversion efficiency greatly varies). The above-mentioned decrease in photoelectric conversion efficiency and variation in humidity resistance and durability become remarkable especially in a high humidity environment (for example, an environment having a humidity of 80% RH or more).

The present invention relates to a photoelectric conversion device including a photosensitive layer containing a perovskite compound as a light absorber and a hole transport layer, and the amount of reduction in photoelectric conversion efficiency between the devices by being contained in the hole transport layer. It is an object of the present invention to provide a hole transporting agent capable of suppressing the variation of the above, and a composition for forming a hole transporting layer containing the hole transporting agent.
Further, the present invention uses a photoelectric conversion device including a photosensitive layer containing a perovskite compound and a hole transport layer as a hole transport layer, thereby suppressing variation in the amount of decrease in photoelectric conversion efficiency between devices. An object of the present invention is to provide a method for producing a hole transport film that can be used.
Further, the present invention provides a photoelectric conversion element having a small variation in the amount of decrease in photoelectric conversion efficiency between elements, even though the perovskite compound is used as a light absorber, and a solar cell using the photoelectric conversion element. Is an issue.

  The inventors of the present invention reproduced a uniform film even if the hole transfer agent composed of the specific compound having a group represented by any one of formulas 1-a to 1-c described later was used in a normal solution coating method. It was found that it can be formed with good properties. Furthermore, by using a film formed of the above hole transporting agent as a hole transporting layer provided in a photoelectric conversion element having a photosensitive layer containing a perovskite compound, the photoelectric conversion element obtained has a photoelectric conversion between elements. It has been found that it is possible to suppress variation in the amount of decrease in efficiency. The present invention has been completed through further studies based on these findings.

式中、Ｒ^１及びＲ^２は置換基を示す。
Ｒは水素原子又は置換基を示す。
Ｒ^３及びＲ^４は水素原子、置換基又は上記化合物との連結部位を示す。
Ｘ^１は−Ｎ（Ｒ^ａ）−又は−Ｏ−を示し、Ｒ^ａは置換基又は水素原子を示す。
＊は上記化合物との連結部位を示す。
ただし、上記式１−ｂ又は式１−ｃで表される基を有する化合物は下記式（Ｓ１）で表わされる母核構造を有している。

式（Ｓ１）中、Ａｒ^ｘ１及びＡｒ^ｘ２はアリール基又はヘテロアリール基を示す。
Ａｒ^１及びＡｒ^２はアリーレン基又はヘテロアリーレン基を示す。
Ｒ^１Ｓは置換基を示す。
ｎ１及びｎ２は０以上の整数である。ただし、ｎ１＋ｎ２≧１である。
ｎ３は３以上の整数である。 The above problems of the present invention have been solved by the following means.
<1> A hole transport material comprising a compound having a group represented by any one of the following formulas 1-a to 1-c.

In the formula, R ¹ and R ² represent a substituent.
R represents a hydrogen atom or a substituent.
R ³ and R ⁴ represent a hydrogen atom, a substituent or a linking site with the above compound.
X ¹ represents —N (R ^a ) — or —O—, and R ^a represents a substituent or a hydrogen atom.
* Indicates a linking site with the above compound.
However, the compound having a group represented by the above formula 1-b or formula 1-c has a mother nucleus structure represented by the following formula (S1).

In formula (S1), Ar ^x1 and Ar ^x2 represent an aryl group or a heteroaryl group.
Ar ¹ and Ar ² represent an arylene group or a heteroarylene group.
R ^1S represents a substituent.
n1 and n2 are integers of 0 or more. However, n1 + n2 ≧ 1.
n3 is an integer of 3 or more.

<2> The hole transport material according to <1>, wherein the compound having a group represented by Formula 1-a has a mother nucleus structure represented by Formula (S1).
<3> In <1> or <2>, at least one of Ar ^x1 and Ar ^{x2 in} formula (S1) has a group represented by any one of formulas 1-a to 1-c. Hole transport material.
<4> The hole-transporting agent according to any one of <1> to <3>, in which the compound has a group represented by Formula 1-a or Formula 1-c.
<5> A composition for forming a hole transport layer, containing the hole transport agent according to any one of the above <1> to <4>.
<6> A method for forming a hole transport film, which comprises applying the composition for forming a hole transport layer according to <5> above.
<7> When the compound contained in the hole transport layer forming composition has a group represented by formula 1-a, at least one of acid treatment and base treatment after applying the hole transport layer forming composition. The method for forming a hole transporting film according to <6>, which comprises performing a post-treatment of seeds.
<8> When the compound contained in the composition for forming a hole transport layer has a group represented by Formula 1-c, active energy ray irradiation treatment is performed after the composition for forming a hole transport layer is applied. <6> The method for forming a hole transport film according to <6>.
<9> A photoelectric conversion element having an electrode having a photosensitive layer containing a light absorber on a conductive support, a counter electrode, and a hole transport layer between the conductive support and the counter electrode,
A photoelectric conversion element, wherein the hole transport layer contains the hole transport agent according to any one of <1> to <4>.
<10> The photoelectric conversion device according to <9>, wherein the hole transport layer is a hole transport film formed by the method for producing a hole transport film according to any one of <6> to <8>. Conversion element.
<11> The photoelectric conversion element according to <9> or <10>, in which the light absorber contains a compound having a perovskite type crystal structure.
<12> A solar cell using the photoelectric conversion element according to any one of <9> to <11>.

  The hole-transporting agent and the composition for forming a hole-transporting layer of the present invention are used as a material for forming the hole-transporting layer of a photoelectric conversion element including a photosensitive layer containing a perovskite compound as a light absorber, It is possible to suppress variation in the amount of decrease in photoelectric conversion efficiency between elements. Further, the method for producing a hole transport film of the present invention is applied as a method for forming a hole transport layer of a photoelectric conversion element, so that it is possible to suppress variations in the amount of decrease in photoelectric conversion efficiency between elements. Transport membranes can be manufactured. Further, the photoelectric conversion element and the solar cell of the present invention use the perovskite compound as a light absorber, and the variation in the amount of decrease in photoelectric conversion efficiency between elements is small.

FIG. 1 is a sectional view schematically showing a preferable embodiment of the photoelectric conversion element of the present invention, including an enlarged view of a circular portion in a layer. FIG. 2 is a sectional view schematically showing a preferred embodiment having a thick photosensitive layer of the photoelectric conversion element of the present invention. FIG. 3 is a sectional view schematically showing another preferable embodiment of the photoelectric conversion element of the present invention. FIG. 4 is a sectional view schematically showing another preferable embodiment of the photoelectric conversion element of the present invention. FIG. 5 is a sectional view schematically showing still another preferred embodiment of the photoelectric conversion element of the present invention.

  In the present invention, a part of the notation of each formula may be expressed as a rational formula in order to understand the chemical structure of the compound. Along with this, in each formula, the partial structure is referred to as a (substituted) group, ion or atom, etc., but in the present invention, these are represented by the above formula in addition to the (substituted) group, ion or atom, etc. Group, or an element group forming an ion (substitution) or an ion.

In the present invention, the “hole-transporting agent comprising a compound” has the same meaning as a hole-transporting agent containing a compound, and the aspect in which the hole-transporting agent is composed only of the compound and the compound and a component other than this compound. And an embodiment including and. As the other component, a component usually used for a hole transport material, a hole transport material and the like can be used without particular limitation.
In the present invention, the expression of a compound (including a complex and a dye) is used to mean not only the compound itself but also its salt and its ion. Furthermore, a compound for which substitution or non-substitution is not specified is meant to include a compound having any substituent as long as the intended effect is not impaired. This also applies to substituents, linking groups and the like (hereinafter referred to as substituents and the like).

  In the present invention, when there are a plurality of substituents and the like represented by a specific code, or when a plurality of substituents and the like are defined at the same time, each substituent and the like may be the same or different from each other, unless otherwise specified. Good. 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 (particularly when they are adjacent to each other), unless otherwise specified, they may be linked to each other to form a ring. Further, a ring such as an alicyclic ring, an aromatic ring or a hetero ring may be further condensed to form a condensed ring.

  Further, in the present invention, the numerical range represented by using "to" means a range including the numerical values before and after "to" as the lower limit value and the upper limit value.

The hole transport material of the present invention comprises a compound having a specific group represented by any one of the formulas 1-a to 1-c described later, and is applied to various electronic devices to obtain a hole transport material. Function. Above all, it is suitably used for a photoelectric conversion element, particularly a photoelectric conversion element using a perovskite compound as a light absorber.
In the present specification, the hole transport agent of the present invention, the composition for forming a hole transport layer, and the method for producing the hole transport film of the present invention will be described together with a photoelectric conversion element and a solar cell.

[Photoelectric conversion element]
The photoelectric conversion element of the present invention has an electrode having a photosensitive layer containing a light absorber on a conductive support, a counter electrode, and a hole transport layer between the conductive support and the counter electrode. This hole-transporting layer contains a hole-transporting agent composed of a specific compound having a group represented by any of the formulas 1-a to 1-c described below (hereinafter, sometimes referred to as a specific group). is doing.

As described above, the photoelectric conversion device of the present invention having the above-described configuration can suppress variations in the amount of decrease in photoelectric conversion efficiency among devices even if the perovskite compound is used as a light absorber. The reason for this is not clear yet, but it can be considered as follows.
That is, the compound having a specific group defined in the present invention has improved solubility in a solvent or the like. Furthermore, it is considered that the crystal formability (crystal growth rate) from the solvent is also improved. It is considered that, by improving the solubility and the crystal formability, even if a film is formed by a normal solution coating method, a film having uniform crystal grain boundaries and further surface flatness can be formed with good reproducibility. Therefore, between a plurality of photoelectric conversion elements, the interface state with the layer provided on the surface of the uniform hole transport layer formed of this compound is improved uniformly, water can be prevented from entering from the interface, and the perovskite compound It can prevent decomposition (deterioration). The improvement of the interface state (prevention of water invasion) is further enhanced by curing the compound having the specific group. As a result, it is considered that the photoelectric conversion element of the present invention exhibits a small variation in humidity resistance and durability even in a high humidity environment (variation in the amount of decrease in photoelectric conversion efficiency among elements can be reduced).

  In the present invention, the electrode (also referred to as the first electrode) has a photosensitive layer provided on a conductive support (between the conductive support and the counter electrode). In the present invention, having a photosensitive layer on a conductive support means that a photosensitive layer is provided (directly provided) in contact with the surface of the conductive support, and another layer is provided above the surface of the conductive support. It is meant to include a mode in which the photosensitive layer is provided via the. In a mode in which the photosensitive layer is provided above the surface of the conductive support via another layer, the other layer provided between the conductive support and the photosensitive layer is a solar cell battery using a photoelectric conversion element. There is no particular limitation as long as it does not deteriorate the performance. For example, a porous layer, a blocking layer, an electron transport layer, a hole transport layer, etc. are mentioned. In the present invention, as an embodiment in which the photosensitive layer is provided above the surface of the conductive support through another layer, for example, the photosensitive layer is a thin film (see FIG. 1) or a thick film on the surface of the porous layer. (See FIG. 2), thin film or thick film on the surface of the blocking layer (see FIG. 3), thin film or thick film on the surface of the electron transport layer (see FIG. 4) And a thin film or a thick film (see FIG. 5) provided on the surface of the hole transport layer. The photosensitive layer may be linearly or dispersedly provided, but is preferably provided as a film.

  In the photoelectric conversion element of the present invention, the first electrode and the counter electrode (also referred to as the second electrode) are opposed to each other, and the first electrode and the counter electrode are stacked in contact with each other, and the first electrode and the counter electrode. And (2) are laminated via another layer (for example, a hole transport layer) (that is, the first electrode and the counter electrode are arranged to face each other with the other layer interposed).

  The photoelectric conversion element of the present invention is preferably, between a conductive support forming a first electrode and a second electrode facing the first electrode, a photosensitive layer, and laminated on the photosensitive layer, and And a hole transport layer containing a hole transport agent composed of a compound having a specific group described later. In the present invention, the lamination of the photosensitive layer and the hole transport layer means that the photosensitive layer and the hole transport layer are directly stacked (adjacent to each other), and the photosensitive layer and the hole transport layer are different from each other. Stacking through layers. The layer, which is stacked between the photosensitive layer and the hole transport layer, is not particularly limited in material, layer thickness and the like as long as the effects of the present invention are not impaired (for example, charge transfer described below is not hindered). For example, a thin layer that does not interfere with charge transfer may be provided. In the present invention, the photosensitive layer and the hole transport layer are preferably adjacent to each other.

  In the photoelectric conversion element of the present invention, the layer structure having the photosensitive layer and the hole transport layer between the conductive support and the second electrode includes the following two aspects. That is, a mode in which the photosensitive layer and the hole transport layer are laminated in this order from the conductive support toward the second electrode, and a mode in which the hole transport layer and the photosensitive layer are laminated in this order. is there.

  The photoelectric conversion element of the present invention is not particularly limited in configuration other than the configuration specified in the present invention, and known configurations 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 as, for example, a single layer or a multi-layer (laminated structure).

Other than the materials and members specified in the present invention, the materials and members used for the photoelectric conversion element or the solar cell can be prepared by a conventional method. For a photoelectric conversion element or a solar cell using a perovskite compound, for example, refer to Patent Document 1 and Non-Patent Documents 1 and 2.
Further, the materials and each member used for the dye-sensitized solar cell can be referred to. Regarding the dye-sensitized solar cell, for example, JP 2001-291534 A, U.S. Pat. No. 4,927,721, U.S. Pat. No. 4,684,537, U.S. Pat. No. 5,084,365. Description, US Pat. No. 5,350,644, US Pat. No. 5,463,057, US Pat. No. 5,525,440, JP-A-7-249790, JP2004. Reference can be made to JP-A-220974 and JP-A-2008-135197.

  The photoelectric conversion element of the present invention itself can be produced by a usual production method, but it is subjected to a method for producing a hole transport film of the present invention described later (hole transport produced by the method for producing a hole transport film of the present invention. It is preferably manufactured (using a membrane).

Hereinafter, preferred forms of the photoelectric conversion element of the present invention will be described.
1 to 5, the same reference numerals indicate the same constituent elements (members).
1 and 2, the size of the fine particles forming the porous layer 12 is emphasized. These fine particles are preferably blocked (deposited or adhered) to the conductive support 11 in the horizontal direction and the vertical direction to form a porous structure.

  In the present specification, simply referring to the photoelectric conversion element 10 means the photoelectric conversion elements 10A to 10E unless otherwise specified. The same applies to the system 100 and the first electrode 1. Further, when simply referred to as the photosensitive layer 13, it means the photosensitive layers 13A to 13C unless otherwise specified. Similarly, the hole transport layer 3 means the hole transport layers 3A and 3B unless otherwise specified.

As a preferable aspect of the photoelectric conversion element of the present invention, for example, the photoelectric conversion element 10A shown in FIG. 1 can be mentioned. The system 100A shown in FIG. 1 is a system in which the photoelectric conversion element 10A is applied to a battery that causes the operating means M (for example, an electric motor) to work in the external circuit 6.
This photoelectric conversion element 10A includes a first electrode 1A, a second electrode 2, and a hole transport layer 3A between a first electrode 1A and a second electrode 2 and a photosensitive layer 13A forming the first electrode 1A. And have.
The first electrode 1A includes a conductive support 11 composed of a support 11a and a transparent electrode 11b, a porous layer 12, and a porous layer 12 as shown in FIG. The surface of the textured layer 12 has a photosensitive layer 13A containing a perovskite compound. Further, the blocking layer 14 is provided on the transparent electrode 11b, and the porous layer 12 is formed on the blocking layer 14. As described above, in the photoelectric conversion element 10A having the porous layer 12, the surface area of the photosensitive layer 13A is increased, and thus it is estimated that the charge separation and charge transfer efficiency are improved.

  The photoelectric conversion element 10B shown in FIG. 2 schematically shows a preferable embodiment in which the photosensitive layer 13A of the photoelectric conversion element 10A shown in FIG. 1 is provided thick and the hole transport layer is provided thin. In this photoelectric conversion element 10B, the hole transport layer 3B is thinly provided adjacent to the photosensitive layer 13B. The photoelectric conversion element 10B is different from the photoelectric conversion element 10A shown in FIG. 1 in the thickness of the photosensitive layer 13B and the hole transport layer 3B, but is the same as the photoelectric conversion element 10A except for these points. ing.

  The photoelectric conversion element 10C shown in FIG. 3 schematically shows another preferable embodiment of the photoelectric conversion element of the present invention. The photoelectric conversion element 10C is different from the photoelectric conversion element 10B shown in FIG. 2 in that the porous layer 12 is not provided, but is the same as the photoelectric conversion element 10B except for this point. That is, in the photoelectric conversion element 10C, the photosensitive layer 13C is formed as a thick film on the surface of the blocking layer 14, and the hole transport layer 3B is formed in contact with the surface of the photosensitive layer 13C. In the photoelectric conversion element 10C, the hole transport layer 3B can be formed thick similarly to the hole transport layer 3A.

  The photoelectric conversion element 10D shown in FIG. 4 schematically shows another preferable embodiment of the photoelectric conversion element of the present invention. This photoelectric conversion element 10D is different from the photoelectric conversion element 10C shown in FIG. 3 in that an electron transport layer 15 is provided instead of the blocking layer 14, but other than this point, it is configured similarly to the photoelectric conversion element 10C. There is. The first electrode 1D has a conductive support 11, and an electron transport layer 15 and a photosensitive layer 13C which are sequentially formed on the conductive support 11. The hole transport layer 3B is formed in contact with the surface of the photosensitive layer 13C. This photoelectric conversion element 10D is preferable in that each layer can be formed of an organic material. As a result, the productivity of the photoelectric conversion element is improved, and it is possible to make it thinner or flexible.

The photoelectric conversion element 10E shown in FIG. 5 schematically shows still another preferable embodiment of the photoelectric conversion element of the present invention. A system 100E including the photoelectric conversion element 10E is a system applied to a battery as in the system 100A.
The photoelectric conversion element 10E has a first electrode 1E, a second electrode 2, and an electron transport layer 4 between the first electrode 1E and the second electrode 2. The first electrode 1E has a conductive support 11, and a hole transport layer 16 and a photosensitive layer 13C which are sequentially formed on the conductive support 11. The photosensitive layer 13C is formed in contact with the surface of the hole transport layer 16. Like the photoelectric conversion element 10D, the photoelectric conversion element 10E is preferable in that each layer can be formed of an organic material.

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, the light that has passed through the conductive support 11 or the second electrode 2 and is incident on the photosensitive layer 13 excites the light absorber. The excited light absorber has an electron with high energy and can emit this electron. The light absorber that has emitted high-energy electrons becomes an oxidant (cation).

In the photoelectric conversion elements 10A to 10D, the electrons emitted from the light absorbing agent move between the light absorbing agents and reach the conductive support 11 (transparent electrode 11b). The electrons reaching the conductive support 11 work in the external circuit 6 and then return to the photosensitive layer 13 via the second electrode 2 and the hole transport layer 3. The light absorber is reduced by the electrons returned to the photosensitive layer 13. On the other hand, in the photoelectric conversion element 10E, the electrons emitted from the light absorber reach the second electrode 2 from the photosensitive layer 13C through the electron transport layer 4 and work in the external circuit 6 and then the conductive support 11 It returns to the photosensitive layer 13 through the (transparent electrode 11b) and the hole transport layer 16. The light absorber is reduced by the electrons returned to the photosensitive layer 13.
In the photoelectric conversion element 10, the system 100 functions as a solar cell by repeating such a cycle of excitation of the light absorber and electron transfer.

In the photoelectric conversion elements 10A to 10D, the way electrons flow from the photosensitive layer 13 to the conductive support 11 varies depending on the presence or absence of the porous layer 12 and the type thereof. In the photoelectric conversion element 10 of the present invention, electron conduction occurs in which electrons move between the light absorbers. Therefore, in the present invention, when the porous layer 12 is provided, the porous layer 12 can be formed of an insulator other than the conventional semiconductor. When the porous layer 12 is formed of a semiconductor, electron conduction occurs in which electrons move inside and between the semiconductor particles of the porous layer 12. On the other hand, when the porous layer 12 is formed of an insulator, electron conduction does not occur in the porous layer 12. When the porous layer 12 is formed of an insulator, if aluminum oxide (Al ₂ O ₃ ) fine particles are used as the insulating fine particles, a relatively high electromotive force (Voc) is obtained.
Even when the blocking layer 14 as the other layer is formed of a conductor or a semiconductor, electron conduction occurs in the blocking layer 14. Further, electron conduction also occurs in the electron transport layer 15.

  The photoelectric conversion element of the present invention is not limited to the above-described preferred embodiments, and the configurations and the like of each embodiment can be appropriately combined between the embodiments without departing from the spirit of the present invention.

  Hereinafter, members and compounds suitable for use in the photoelectric conversion element and the solar cell of the present invention will be described.

<Electrode (first electrode) 1>
The first electrode 1 has a conductive support 11 and a photosensitive layer 13, and functions as a working electrode in the photoelectric conversion element 10.
As shown in FIGS. 1 to 5, the first electrode 1 preferably has at least one layer of a porous layer 12, a blocking layer 14, an electron transport layer 15 and a hole transport layer 16.
The first electrode 1 preferably has at least the blocking layer 14 in terms of short circuit prevention, and more preferably has the porous layer 12 and blocking layer 14 in terms of light absorption efficiency and short circuit prevention.
In addition, the first electrode 1 preferably has an electron transport layer 15 or a hole transport layer 16 formed of an organic material in terms of improving the productivity of the photoelectric conversion element and making it thinner or flexible.

-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 11 is composed of a material having conductivity, for example, a metal, or a glass or plastic support 11a, and a transparent electrode 11b as a conductive film formed on the surface of the support 11a. A configuration having is preferable.

Among them, as shown in FIGS. 1 to 5, a conductive support 11 in which a transparent metal 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 the transparent polymer film described in paragraph No. 0153 of JP 2001-291534 A. As a material for forming the support 11a, besides glass and plastic, it is possible to use ceramic (JP 2005-135902 A) and conductive resin (JP 2001-160425 A). 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) are particularly preferable. At this time, the coating amount of the metal oxide 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, it is preferable that light be 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 thickness of the support 11a and the conductive support 11 is not particularly limited and is set to an appropriate thickness. For example, it 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 the transparent electrode 11b is provided, the film thickness of the transparent electrode 11b is not particularly limited and is, for example, preferably 0.01 to 30 μm, more preferably 0.02 to 25 μm, and 0.025 to 20 μm. Is particularly preferable.

  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 described in JP-A-2003-123859, a high refractive film and a low refractive index oxide film are alternately laminated. Well, it may have a light guide function described in JP-A-2002-260746.

-Blocking layer 14-
In the present invention, like the photoelectric conversion elements 10A to 10C, preferably on the surface of the transparent electrode 11b, that is, the conductive support 11, the porous layer 12, the photosensitive layer 13, the hole transport layer 3, and the like. In between, a blocking layer 14 is provided.
In the photoelectric conversion element, for example, when the photosensitive layer 13 or the hole transport layer 3 is electrically connected to the transparent electrode 11b or the like, 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 blocking layer 14 can also function as a scaffold that carries a light absorber.
The blocking layer 14 may be provided even when the photoelectric conversion element has an electron transport layer. For example, in the case of the photoelectric conversion element 10D, it may be provided between the conductive support 11 and the electron transport layer 15, and in the case of the photoelectric conversion element 10E, it is provided between the second electrode 2 and the electron transport layer 4. May be

The material for forming the blocking layer 14 is not particularly limited as long as it is a material that can perform the above functions, but it is a substance that transmits visible light, such as the conductive support 11 (transparent electrode 11b) or the second electrode. It is preferable that it is an insulating material. The "insulating substance for the conductive support 11 (transparent electrode 11b)" is specifically a material having an energy level in the conduction band that forms the conductive support 11 (metal oxide that forms the transparent electrode 11b). Compound) which is higher than the energy level of the conduction band of the substance) and lower than the energy level of the conduction band of the material forming the porous layer 12 or the energy level of the ground state of the light absorber (n-type semiconductor compound).
Examples of the material forming the blocking layer 14 include silicon oxide, magnesium oxide, aluminum oxide, calcium carbonate, cesium carbonate, polyvinyl alcohol, polyurethane and the like. Further, it may be a material generally used as a photoelectric conversion material, and examples thereof include titanium oxide, tin oxide, zinc oxide, niobium oxide, and tungsten oxide. Among them, titanium oxide, tin oxide, magnesium oxide, aluminum oxide and the like are preferable.
The 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.

  In the present invention, the film thickness of each layer can be measured by observing the cross section of the photoelectric conversion element 10 using a scanning electron microscope (SEM: Scanning Electron Microscope) or the like.

-Porous layer 12-
In the present invention, like the photoelectric conversion elements 10A and 10B, the porous layer 12 is preferably provided on the transparent electrode 11b. When the blocking layer 14 is provided, the porous layer 12 is preferably formed on the blocking layer 14.
The porous layer 12 is a layer that functions as a scaffold that carries the photosensitive layer 13 on its 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 surface area of the porous layer 12 as a whole.

The porous layer 12 is preferably a fine particle layer having fine 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 formed by depositing two or more kinds of fine particles. When the porous layer 12 is a fine particle layer having pores, the amount of the light absorber carried (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 each fine particle that constitutes the porous layer 12. In the present invention, in the 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 the projection area, and 100 times or more. Is more preferable. The upper limit is not particularly limited, but is usually about 5000 times. The particle diameter of the fine particles forming the porous layer 12 is preferably 0.001 to 1 μm as primary particles 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 forming the porous layer 12 is not particularly limited in terms of conductivity, and may be an insulator (insulating material), a conductive material or a semiconductor (semi-conductive material). ..
As a material for forming the porous layer 12, for example, a metal chalcogenide (for example, an oxide, a sulfide, a selenide, or the like), a compound having a perovskite type crystal structure (excluding a perovskite compound used as a light absorber), and silicon. (For example, silicon dioxide, zeolite) or carbon nanotubes (including carbon nanowires and carbon nanorods) can be used.

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

  The compound having a perovskite type crystal structure is not particularly limited, and examples thereof include transition metal oxides. 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, sodium titanate, and bismuth titanate. Of these, strontium titanate and calcium titanate are preferable.

  The carbon nanotube has a shape obtained by rolling 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, two-walled carbon nanotubes in which two graphene sheets are wound concentrically (DWCNT), and multiple graphene sheets are concentric circles. It is classified as a multi-walled carbon nanotube (MWCNT) that is wound into a shape. As the porous layer 12, any carbon nanotube is not particularly limited and can be used.

  Among them, the material forming the porous layer 12 is preferably an oxide of titanium, tin, zinc, zirconium, aluminum or silicon, or a carbon nanotube, and more preferably titanium oxide or aluminum oxide.

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

  The thickness of the porous layer 12 is not particularly limited, but is usually in the range of 0.05 to 100 μm, preferably 0.1 to 100 μm. When used as a solar cell, the thickness is preferably 0.1 to 50 μm, more preferably 0.2 to 30 μm.

-Electron transport layer 15-
In the present invention, like the photoelectric conversion element 10D, the electron transport layer 15 is preferably provided on the surface of the transparent electrode 11b.
The electron transport layer 15 has a function of transporting electrons generated in the photosensitive layer 13 to the conductive support 11. The electron transport layer 15 is formed of an electron transport material capable of exhibiting this function. The electron transport material is not particularly limited, but an organic material (organic electron transport material) is preferable. Examples of the organic electron transporting material include fullerene compounds such as [6,6] -Phenyl-C61-Butyric Acid Methyl Ester (PC ₆₁ BM), perylene compounds such as perylene tetracarboxydiimide (PTCDI), and tetracyanoquinodimethane. Examples thereof include low molecular weight compounds such as (TCNQ) or high molecular weight compounds.
The thickness of the electron transport layer 15 is not particularly limited, but is preferably 0.001 to 10 μm, more preferably 0.01 to 1 μm.

-Hole transport layer 16-
In the present invention, like the photoelectric conversion element 10E, the hole transport layer 16 is preferably provided on the surface of the transparent electrode 11b. The hole transport layer 16 has a hole transport function of transporting holes generated by the charge separation of the excited light absorber to the conductive support 11 (electrons injected from the transparent electrode 11b are oxidants of the light absorber). It has the function of transporting (supplementing) to (1) and is the same as the hole transporting layer 3 described later, except that the formed position is different.

-Photosensitive layer (light absorbing layer) 13-
The photosensitive layer 13 is preferably a porous layer 12 (photoelectric conversion elements 10A and 10B), a blocking layer 14 (photoelectric conversion element 10C), an electron transport layer 15 (photoelectric conversion element 10D) or a hole transport layer 16 (photoelectric conversion). It is provided on the surface of each layer of the element 10E (including the inner surface of the concave portion when the surface on which the photosensitive layer 13 is provided is uneven).
In the present invention, the photosensitive layer 13 contains a light absorber. This light absorber contains at least one perovskite compound described below. In addition to the perovskite compound, the photosensitive layer may have a light absorbing component such as a metal complex dye or an organic dye. The light absorber contained in the photosensitive layer 13 is preferably the above perovskite compound.

  The photosensitive layer 13 may be a single layer or a laminated structure of two or more layers. When the photosensitive layer 13 has a laminated structure of two or more layers, it may have a laminated structure in which layers made of different light absorbers are laminated, and a hole transporting material described later may be provided between the photosensitive layers. It may be a laminated structure having an intermediate layer containing. When the photosensitive layer 13 has a laminated structure of two or more layers, it may contain at least one kind, and all the photosensitive layers may contain at least one kind of perovskite compound.

  The mode in which the photosensitive layer 13 is provided on the conductive support 11 is as described above. The photosensitive layer 13 is preferably provided on the surface of each layer so that the excited electrons flow to the conductive support 11 or the second electrode 2. At this time, the photosensitive layer 13 may be provided on the entire surface of each layer, or may be provided on a part of the surface.

The film thickness of the photosensitive layer 13 is appropriately set according to the aspect in which the photosensitive layer 13 is provided on the conductive support 11, and is not particularly limited. Usually, the film thickness is, for example, preferably 0.001 to 100 μm, more preferably 0.01 to 10 μm, and particularly preferably 0.01 to 5 μm.
When the porous layer 12 is provided, the total film thickness together with the film thickness of the porous layer 12 is preferably 0.01 μm or more, more preferably 0.05 μm or more, further preferably 0.1 μm or more, and 0.3 μm or more. Particularly preferred. The total film thickness is preferably 100 μm or less, more preferably 50 μm or less, still more preferably 30 μm or less. The total film thickness can be within a range in which the above values are appropriately combined.
When the photoelectric conversion element 10 has the porous layer 12 and the hole transport layer 3, the total film thickness of the porous layer 12, the photosensitive layer 13, and the hole transport layer 3 is not particularly limited, but may be, for example, 0. 01 μm or more is preferable, 0.05 μm or more is more preferable, 0.1 μm or more is further preferable, and 0.3 μm or more is particularly preferable. The total film thickness is preferably 200 μm or less, more preferably 50 μm or less, further preferably 30 μm or less, and particularly preferably 5 μm or less. The total film thickness can be within a range in which the above values are appropriately combined.
In the present invention, when the photosensitive layer is provided in the form of a thick film (photosensitive layers 13B and 13C), the light absorber contained in this photosensitive layer may function as a hole transport material.

[Light absorber]
-Perovskite compound-
The light absorber in the photosensitive layer 13 includes "an element of the periodic table group 1 or a cationic organic group A", "a metal atom M other than the element of the periodic table group 1", and "anionic atom or atomic group X". And a perovskite compound having In the perovskite compound, the periodic table group 1 element or the cationic organic group A, the metal atom M and the anionic atom or the atomic group X are respectively a cation (for convenience, may be referred to as a cation A) and a metal in the perovskite type crystal structure. It exists as each constituent ion of a cation (sometimes referred to as cation M for convenience) and an anion (sometimes referred to as anion X for convenience).
In the present invention, the cationic organic group refers to an organic group having a property of becoming a cation in a perovskite type crystal structure, and the anionic atom or atomic group is an atom or an atomic group having a property of becoming an anion in a perovskite type crystal structure. Say.

In the perovskite compound used in the present invention, the cation A is a cation of a Group 1 element of the periodic table or an organic cation composed of a cationic organic group A. The cation A may be one kind of cation or two or more kinds of cations. When it is two or more kinds of cations, it may be a cation of two or more kinds of periodic table group 1 elements, or two or more kinds of organic cations, and at least one cation of a periodic table group 1 element and at least one. It may also contain a species of organic cation. The cation A preferably contains an organic cation, more preferably an organic cation. When there are two or more kinds of cations, the abundance ratio of each cation is not particularly limited.
The cation of a Group 1 element of the periodic table is not particularly limited, and examples thereof include a cation of each element of lithium, sodium, potassium, or cesium, and a cesium cation is particularly preferable.
The organic cation is not particularly limited as long as it is an cation of an organic group having the above-mentioned properties, but an organic cation of a cationic organic group represented by the following formula (1) is more preferable.
Formula (1): _{^{R 1A -N (R 1a) 3}} +

In the formula, R ^1A represents a substituent. The substituent which can be adopted as R ^1A is not particularly limited as long as it is an organic group, but is an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an aryl group, a heteroaryl group (aromatic heterocyclic group), an aliphatic heterocycle. A group or a group that can be represented by the following formula (2) is preferable. Among them, an alkyl group and a group represented by the following formula (2) are more preferable.
R ^1a represents a hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an aryl group, an aromatic heterocycle or an aliphatic heterocycle group. Among them, a hydrogen atom or an alkyl group is preferable, and a hydrogen atom is more preferable.

In the formula, X ^a 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 the bonding position with the N atom in formula (1).

In the present invention, the organic cation of the cationic organic group A is an ammonium cationic organic group A in which R ^1a is a hydrogen atom and R ^1A and N (R ^1a ) _{3 in} the above formula (1) are bonded. An organic ammonium cation (R ^1A —NH ₃ ⁺ ) consisting of is preferred. 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, when X ^a is NH (R ^1c is a hydrogen atom) in the group represented by the above formula (2), the organic cation is a bond between the group represented by the above formula (2) and NH _3. In addition to the organic ammonium cation of the ammonium cationic organic group formed as described above, 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 composed of an amidinium cationic organic group include cations represented by the following formula (A ^am ). In the present invention, a cation represented by the following formula (A ^am ) may be referred to as “R ^1b C (═NH) —NH ₃ ⁺ ” for convenience.

The alkyl group that can be used as R ^1A and R ^1a is preferably an alkyl group having 1 to 36 carbon atoms, more preferably an alkyl group having 1 to 18 carbon atoms, further preferably an alkyl group having 1 to 6 carbon atoms, and an alkyl group having 1 to 3 carbon atoms. Is particularly preferable. For example, methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, pentyl, hexyl and the like can be mentioned.
The cycloalkyl group that can be used as R ^1A and R ^1a is preferably a cycloalkyl group having 3 to 10 carbon atoms, more preferably a cycloalkyl group having 3 to 8 carbon atoms, and examples thereof include cyclopropyl, cyclopentyl or cyclohexyl.

The alkenyl group that can be used as R ^1A and R ^1a is preferably an alkenyl group having 2 to 36 carbon atoms, more preferably an alkenyl group having 2 to 18 carbon atoms, and still more preferably an alkenyl group having 2 to 6 carbon atoms. For example, vinyl, allyl, butenyl, hexenyl and the like can be mentioned.
The alkynyl group that can be used as R ^1A and R ^1a is preferably an alkynyl group having 2 to 36 carbon atoms, more preferably an alkynyl group having 2 to 18 carbon atoms, and further preferably an alkynyl group having 2 to 4 carbon atoms. For example, ethynyl, butynyl, hexynyl and the like can be mentioned.

The aryl group that can be used as R ^1A and R ^1a is preferably an aryl group having 6 to 24 carbon atoms, more preferably an aryl group having 6 to 12 carbon atoms, and examples thereof include phenyl.
When the aromatic heterocycle that can be used as R ^1A and R ^1a is a condensed ring, in addition to a group consisting of a monocyclic aromatic heterocycle, a monocyclic aromatic heterocycle may be replaced with another ring such as an aromatic ring. It includes a group consisting of a condensed hydrocarbon ring in which an aromatic hydrocarbon ring, an aliphatic hydrocarbon ring or a heterocycle is condensed. The number of ring-constituting heteroatoms constituting the aromatic heterocycle may be one or more, and the heteroatoms are preferably nitrogen atoms, oxygen atoms and sulfur atoms. Further, the number of ring members of the aromatic heterocycle is preferably a 3- to 8-membered ring, and more preferably a 5-membered ring or a 6-membered ring. The aromatic heterocycle preferably has 5 to 24 carbon atoms, more preferably 5 to 18 carbon atoms, and further preferably 5 to 10 carbon atoms. Examples of the 5-membered aromatic heterocycle and the condensed heterocycle including the 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 6-membered aromatic heterocycle and the condensed heterocycle containing the 6-membered aromatic heterocycle include pyridine ring, pyrimidine ring, pyrazine ring, triazine ring, quinoline ring, and quinazoline ring. Is mentioned.

The aliphatic heterocyclic group that can be used as R ^1A and R ^1a is a monocyclic group consisting of only an aliphatic heterocycle and an aliphatic condensed heterocycle in which another ring (for example, an aliphatic ring) is condensed with the aliphatic heterocycle. And a group consisting of a ring. The number of ring-constituting heteroatoms constituting the aliphatic heterocycle may be 1 or more, and the heteroatom is preferably a nitrogen atom, an oxygen atom or a sulfur atom. Further, the number of ring members of the aliphatic heterocycle is preferably a 3- to 8-membered ring, more preferably a 5-membered ring or a 6-membered ring. The aliphatic heterocycle preferably has 0 to 24 carbon atoms, more preferably 1 to 18 carbon atoms, further preferably 2 to 10 carbon atoms, and particularly preferably 3 to 5 carbon atoms. Specific preferred examples of the aliphatic heterocycle include a pyrrolidine ring, an oxolane ring, a thiolane ring, a piperidine ring, a tetrahydrofuran ring, an oxane ring (tetrahydropyran ring), a thiane ring, a piperazine ring, a morpholine ring, a quinuclidine ring, a pyrrolidine ring, and azetidine. Examples thereof include a ring, an oxetane ring, an aziridine ring, a dioxane ring, a pentamethylene sulfide ring and γ-butyrolactone.

In the group which can be taken as R ^1A and can be represented by the formula (2), X ^a represents NR ^1c , an oxygen atom or a sulfur atom, and NR ^1c is preferable. Here, R ^1c represents a hydrogen atom or a substituent, preferably a hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an aryl group, an aromatic heterocycle or an aliphatic heterocycle group, and a hydrogen atom is More preferable.
R ^1b represents a hydrogen atom or a substituent, and a hydrogen atom is preferable. ^Examples of the substituent that can be adopted as R ^1b include an amino group, an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an aryl group, an aromatic heterocycle or an aliphatic heterocycle group.
An alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an aryl group, an aromatic heterocycle or an aliphatic heterocyclic group, which R ^1b and R ^1c can each have, is synonymous with each group of the above R ^1A and is preferable. Things are the same.
The amino group that can be used as R ^1b may be unsubstituted or substituted, and includes an alkylamino group, an alkenylamino group, an alkynylamino group, a cycloalkylamino group, a cycloalkenylamino group, an arylamino group, and a heterocyclic amino group. . The amino group preferably has 0 to 20 carbon atoms.

Examples of the group that can be represented by the formula (2) include a (thio) acyl group, a (thio) carbamoyl group, an imidoyl group and an amidino group.
The (thio) acyl group includes an acyl group and a thioacyl group. Acyl group, the total carbon number preferably an acyl group having 1 to 7, for example, formyl, acetyl _{(CH 3 C (= O)} -), propionyl, hexanoyl and the like. Thioacyl group, the total carbon number of preferably thioacyl group having 1 to 7, for example, thioformyl, thioacetyl _{(CH 3 C (= S)} -), thiopropionyl, and the like.
(Thio) carbamoyl group, a carbamoyl group _{(H 2 NC (= O)} -) and thiocarbamoyl group _{(H 2 NC (= S)} -) embraces.

The imidoyl group is a group represented by R ^1b -C (= NR ^1c )-, and R ^1b and R ^1c are each preferably a hydrogen atom or an alkyl group, and the alkyl group has the same meaning as the alkyl group for R ^1A. Is more preferable. For example, formimidoyl (HC (= NH) -) , acetimidoyl _{(CH 3 C (= NH)} -), propionic imidoyl _{(CH 3 CH 2 C (=} NH) -) and the like. Among them, formimidoyl is preferable.
Amidino group as group which can be represented by the formula (2) is, ^{R 1c R 1b} of the imidoyl group at the amino group has the structure (-C (= NH) NH ₂₎ is a hydrogen atom.

Any of an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an aryl group, an aromatic heterocycle, an aliphatic heterocycle group and a group that can be represented by the above formula (2), which can be adopted as R ^1A and R ^1a , Or may have a substituent. The substituent that R ^1A and 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, and a heterocyclic group (aromatic heterocycle, aliphatic group). Group heterocyclic group), alkoxy group, alkylthio group, amino group (alkylamino group, arylamino group, etc.), acyl group, alkylcarbonyloxy group, aryloxy group, alkoxycarbonyl group, aryloxycarbonyl group, acylamino group, sulfone Examples thereof include an amide group, a carbamoyl group, a sulfamoyl group, a halogen atom, a cyano group, a hydroxy group and a carboxy group. Each substituent that R ^1A and 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 other than a Group 1 element of the periodic table and is a cation of a metal atom capable of adopting a perovskite type crystal structure. Examples of such metal atoms include metal atoms such as calcium, strontium, cadmium, copper, nickel, manganese, iron, cobalt, palladium, germanium, tin, lead, ytterbium, europium, indium, titanium and bismuth. ..
M may be one kind of metal cation or two or more kinds of metal cations. Among them, the metal cation M is preferably a divalent cation, a divalent lead cation (Pb ²⁺ ), a divalent copper cation (Cu ²⁺ ), a divalent germanium cation (Ge ²⁺ ) and a divalent cation. At least one selected from the group consisting of tin cations (Sn ²⁺ ) is more preferable, Pb ²⁺ or Sn ²⁺ is further preferable, and Pb ²⁺ is particularly preferable. When there are two or more metal cations, the ratio of metal cations is not particularly limited.

In the perovskite compound used in the present invention, the anion X represents an anion of an anionic atom or atomic group X. The anion is preferably an anion of a halogen atom or an anion of each atomic group of NCS ⁻ , NCO ⁻ , HO ⁻ , NO ₃ ⁻ , CH ₃ COO ⁻ or HCOO ⁻ . Of these, an anion of a halogen atom is more preferable. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom and the like.
The anion X may be an anion of one kind of anionic atom or atomic group, or may be an anion of two or more kinds of anionic atoms or atomic groups. When the anion is one kind of anionic atom or atomic group, the anion of iodine atom is preferable. On the other hand, when it is an anion of two or more kinds of anionic atoms or atomic groups, anions of two kinds of halogen atoms, particularly anions of bromine atom or chlorine atom and anions of iodine atom are preferable. The ratio of the two or more anions is not particularly limited.

  The perovskite compound used in the present invention has a perovskite type crystal structure having each of the constituent ions described above, and is preferably a perovskite 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 Group 1 element of the periodic table. X represents an anionic atom or atomic group.
a represents 1 or 2, m represents 1, and a, m and x satisfy a + 2m = x.

  In the formula (I), the periodic table group 1 element or the cationic organic group A forms the cation A having a perovskite type crystal structure. Therefore, 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 be the cation A to form the perovskite type crystal structure. The Group 1 element of the periodic table or the cationic organic group A has the same meaning as the group 1 element of the Periodic Table or the cationic organic group described for the cation A, and the preferable ones are also the same. A may contain a Group 1 element of the periodic table and a cationic organic group.

  The metal atom M is a metal atom forming the metal cation M of the perovskite type crystal structure. The metal atom M is not particularly limited as long as it is an atom other than the Group 1 element of the periodic table and can form the perovskite type crystal structure as the metal cation M. The metal atom M has the same meaning as the metal atom described for the metal cation M, and the preferred ones are also the same.

  The anionic atom or atomic group X forms the anion X having a perovskite type crystal structure. The anionic atom or atomic group X is not particularly limited as long as it is an atom or atomic group capable of forming the anion X and forming a perovskite type crystal structure. The anionic atom or atomic group X has the same meaning as the anionic atom or atomic group described for the anion X above, and the preferred ones are also the same.

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

  The perovskite compound used in the present invention may be either the compound represented by the formula (I-1) or the compound represented by the formula (I-2), or a mixture thereof. Therefore, in the present invention, at least one kind of the perovskite compound 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, the molecular formula, the crystal structure and the like. ..

  Specific examples of the perovskite compound that can be used in the present invention are shown below, but the present invention is not limited thereto. In the following, the compound represented by the formula (I-1) and the compound represented by the formula (I-2) are described separately. However, the compounds exemplified as the compound represented by the formula (I-1) may be the compound represented by the formula (I-2) depending on the synthesis conditions and the like, and the compound represented by the formula (I It may be a mixture of the compound represented by -1) and the compound represented by the formula (I-2). Similarly, even a compound exemplified as the compound represented by the formula (I-2) may be a compound represented by the formula (I-1), and is also represented by the formula (I-1). And a compound represented by formula (I-2) in some cases.

Specific examples of the compound represented by formula (I-1), 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, CH 3 NH 3 _{PbBr 2 I, CH 3 NH 3} SnBr 3, CH 3 NH 3 SnI 3, CH 3 NH 3 GeCl 3, CH (= NH) NH 3 PbI 3, CsSnI 3, CsGeI 3, Cs 0.04 FA 0.8 ( _{CH 3 NH 3) 0.16 PbI 2.84} Br 0.16 , and the like. Here, FA represents a formamide-yl group _{(-C (= NH) NH 2} ).

Specific examples of the compound represented by formula (I-2), for _{example, (C 2 H 5 NH 3} ) 2 PbI 4, (C 10 H 21 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 5} CH 2 CH 2 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, (} CH 3 NH 3) 2 CuCl 4, (C 4 H 9 NH 3) 2 GeI 4, include _{(C 3 H 7 NH 3)} 2 FeBr 4 , and the like. _{Here, C} 4 _{H 3} SNH 3 in _{(C 4 H 3 SNH 3)} 2 PbI 4 is aminothiophene.

The amount of the light absorber used may be an amount that covers at least a part of the surface of the hole transport layer 3 on which light is incident, and an amount that covers the entire surface is preferable.
In the photosensitive layer 13, the content of the perovskite compound in the light absorber is usually 1 to 100% by mass.

<Counter electrode (second electrode) 2>
The second electrode 2 functions as a positive electrode in the solar cell. The second electrode 2 is not particularly limited as long as it has electrical conductivity, and usually has the same configuration as the electrically conductive support 11. The support 11a is not always necessary if the strength is sufficiently maintained.
As the structure of the second electrode 2, a structure having a high current collecting effect is preferable. 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 the present invention, it is preferable that the conductive support 11 is transparent and sunlight or the like is incident from the support 11a side. In this case, the second electrode 2 more preferably has a property of reflecting light.

Examples of the material for forming the second electrode 2 include metals such as platinum, gold, nickel, copper, silver, indium, ruthenium, palladium, rhodium, iridium, osmium, and aluminum, and the conductive support 11 described above. Examples thereof include metal oxides, carbon materials, and known conductive polymers. Any carbon material may be used as long as it is a conductive material formed by bonding carbon atoms, and examples thereof include fullerenes, carbon nanotubes, graphite and graphene. Any carbon material may be used as long as it is a conductive material formed by bonding carbon atoms, and examples thereof include fullerenes, carbon nanotubes, graphite and graphene.
As the second electrode 2, a thin film of a metal or a conductive metal oxide (including a thin film formed by vapor deposition), or a glass substrate or a plastic substrate having this thin film is preferable. As the glass substrate or the plastic substrate, glass having a thin film of gold or platinum, or platinum-deposited glass is preferable.

  The film thickness of the second electrode 2 is not particularly limited and is preferably 0.01 to 100 μm, more preferably 0.01 to 10 μm, and further preferably 0.01 to 1 μm.

<Hole transport layer 3>
The photoelectric conversion element of the present invention is one of the preferable aspects in which the photoelectric conversion elements 10A to 10D have the hole transport layer 3 between the first electrode 1 and the second electrode 2. In this embodiment, it is preferable that the hole transport layer 3 is in contact (lamination) with the photosensitive layer 3C. 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 layer 3 has a hole transport function of transporting holes generated by the charge separation of the excited light absorber to the second electrode 2 (electrons injected from the second electrode 2 are oxidized by the light absorber). The layer is not particularly limited as long as it has at least a function of transporting (supplementing) the body. The hole transport layer 3 may have an electron blocking function, a hole extraction function, etc. in addition to the hole transport function. When having these functions, the hole transport layer 3 is also referred to as, for example, an electron blocking layer or a hole extraction layer.
The film thickness of the hole transport layer is not particularly limited and is preferably 50 μm or less, more preferably 0.1 nm to 10 μm, further preferably 5 nm to 5 μm, and particularly preferably 10 nm to 1 μm.

  The hole transport layer 3 is preferably a solid layer (solid hole transport layer), and is composed of a compound having a specific group represented by any one of the following formulas 1-a to 1-c. Contains an agent. In the present invention, that the hole-transporting material is composed of a compound having a specific group means that the compound having a specific group itself (state having a specific group as it is (without reacting)) Both embodiments including a reaction product of a compound having a group (a compound in which a specific group has reacted (modified, decomposed)). That is, in the present invention, the hole transport agent is composed of a compound having a specific group represented by any one of the following formulas 1-a to 1-c or a reaction product of this compound. Therefore, the fact that the hole transport layer contains the hole transport agent made of the compound having a specific group means that the hole transport layer made of the compound having the specific group is contained as it is, Both the embodiment containing a hole-transporting agent consisting of a reaction product of a compound having a group and the embodiment. The reaction product of the compound having the specific group represented by any one of formulas 1-a to 1-c will be described later.

(Hole transfer material)
The hole-transporting material contained in the hole-transporting layer of the photoelectric conversion element is the hole-transporting material defined in the present invention (hole-transporting material of the present invention), and specifically, the formula 1-a to It is composed of a compound having a specific group represented by any one of 1-c and may contain other components.

The hole transport material of the present invention is a compound having the above-described specific group and a mother nucleus structure, and can be applied to various electronic devices. Among them, a photoelectric conversion element, in particular, a perovskite compound as a light absorber is used. It is preferably used as a hole transporting agent for forming the hole transporting layer of the photoelectric conversion element.
The mother nucleus structure described above is not particularly limited, and examples thereof include a mother nucleus structure of a compound that is usually used as a hole transport material of a photoelectric conversion element. In the present invention, the mother nucleus structure refers to a residue (a partial structure having a binding site with a specific group) obtained by removing the above specific group from the chemical structure constituting the compound. The mother nucleus structure can also be referred to as a partial structure in which a hydrogen atom or a group is removed from a compound having a hole transporting function by the number of bonding sites necessary for bonding with a specific group. The mother nucleus structure may be a mother nucleus structure of a low molecular weight compound or may be a mother nucleus structure of a high molecular compound.

The hole transport material that forms such a mother nucleus structure is not particularly limited, and examples thereof include hole transport materials that are commonly used in photoelectric conversion elements. For example, JP-A No. 2001-291534, paragraphs 0209 to The organic hole transport material described in 0212 and the like can be mentioned. Specific examples of the organic hole transport material include conductive polymers such as polythiophene, polyaniline, polypyrrole and polysilane, and spiro compounds in which two rings share a central atom having a tetrahedral structure such as C and Si, and tria. Examples thereof include aromatic amine compounds (triarylamine compounds) having a reel amino group and the like, triphenylene compounds, nitrogen-containing heterocyclic compounds, porphyrins, phthalocyanines, naphthalocyanines, cyclic compounds such as squarylium, and liquid crystalline cyano compounds. In addition to these, the hole transporting materials described in WO 2015/107454, WO 2015/114521, or WO 2014/111365 may be mentioned.
Among them, a mother nucleus structure made of a compound represented by the following formula (S1) is preferable in terms of variations in moisture resistance and durability.

  However, in the present invention, when the specific group is a group represented by Formula 1-b or Formula 1-c described later, the mother nucleus structure is a mother nucleus structure composed of a compound represented by the following formula (S1). is there. That is, the compound in this case is a compound represented by the following formula (S1) having a group represented by the above formula 1-b or formula 1-c.

式（Ｓ１）中、Ａｒ^ｘ１及びＡｒ^ｘ２はアリール基又はヘテロアリール基を示し、直接又は連結基を介してＡｒ^１又はＡｒ^２と結合している。
Ａｒ^１及びＡｒ^２はアリーレン基又はヘテロアリーレン基を示す。
Ｒ^１Ｓは置換基を示す。
ｎ１及びｎ２は０以上の整数である。ただし、ｎ１＋ｎ２≧１である。
ｎ３は３以上の整数である。 The compound represented by the following formula (S1) is a polymer that functions as a hole transport material, and preferably has a hole transport function.

In formula (S1), Ar ^x1 and Ar ^x2 represent an aryl group or a heteroaryl group, and are bonded to Ar ¹ or Ar ² directly or via a linking group.
Ar ¹ and Ar ² represent an arylene group or a heteroarylene group.
R ^1S represents a substituent.
n1 and n2 are integers of 0 or more. However, n1 + n2 ≧ 1.
n3 is an integer of 3 or more.

The aryl group that can be used as Ar ^x1 and Ar ^x2 may be a monocyclic ring or a condensed ring, and a monocyclic ring is preferable. In the condensed aryl group, the number of rings to be condensed is not particularly limited, and is preferably 2 to 5, more preferably 2 or 3, and even more preferably 2. Examples of the monocyclic aryl group include a benzene ring group (phenyl group), and examples of the condensed aryl group include a naphthalene ring, anthracene ring, phenanthrene ring, triphenylene ring, chrysene ring, picene ring, pyrene ring, and fluorene. Each group of a ring or an azulene ring is mentioned. Of these, a phenyl group and a naphthyl group are preferable.
The number of ring-constituting atoms of the aryl group that can be used as Ar ^x1 and Ar ^x2 is not particularly limited, but is preferably 6 to 30, more preferably 6 to 15, and further preferably 6 to 13.

The heteroaryl group that can be used as Ar ^x1 and Ar ^x2 may be a monocycle or a condensed ring, and a monocycle is preferable.
The monocyclic heteroaryl group is not particularly limited, but it is a carbon atom and at least one (preferably one or two) hetero atom (eg, nitrogen atom, oxygen atom, sulfur atom, silicon atom, selenium atom). Or a phosphorus atom) is a heteroaryl group having a ring-constituting atom. The monocyclic heteroaryl group is not particularly limited, but a 5-membered or 6-membered ring group is preferable. Examples of the monocyclic heteroaryl group include a thiophene ring, a furan ring, a pyrrole ring, a selenophene ring, a thiazole ring, an oxazole ring, an isothiazole ring, an isoxazole ring, an imidazole ring, a pyrazole ring, a thiadiazole ring, and an oxadiazole ring. , Triazole ring, silole ring, phosphole ring, pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, triazine ring or tetrazine ring, and thiophene ring or furan ring is preferable.
Examples of the condensed heteroaryl group include a ring group formed by condensing a plurality of monocyclic heteroaryls, and a ring group formed by condensing a plurality of monocyclic heteroaryls and a monocyclic hydrocarbon ring. The number of rings to be condensed is not particularly limited, and is preferably 2 to 5, more preferably 2 or 3, and even more preferably 2. Examples of the condensed heteroaryl group include a benzofuran ring, an isobenzofuran ring, a benzothiophene ring, a benzoisothiophene ring, an indazole ring, an indole ring, an isoindole ring, an indolizine ring, a carbazole ring (dibenzopyrrole ring), and quinoline. Ring, isoquinoline ring, benzoxazole ring, benzisoxazole ring, benzothiazole ring, benzisothiazole ring, benzimidazole ring, benzotriazole ring, dibenzofuran ring, dibenzothiophene ring, thienopyridine ring, silafluorene ring (dibenzosilole ring), Examples thereof include thienothiophene ring, trithiophene ring, cyclopentadithiophene ring, cyclopentadifuran ring, benzodifuran ring, benzodithiophene ring, dithienopyrrole ring, dithienofuran ring and dithienosilole ring.
The number of ring-constituting carbon atoms of the heteroaryl group that can be used as Ar ^x1 and Ar ^x2 is not particularly limited, but is preferably 0 to 24, more preferably 1 to 18, and further preferably 3 to 10. More preferable.

Each of Ar ^x1 and Ar ^x2 is preferably an aryl group, and more preferably a phenyl group.
Ar ^x1 and Ar ^x2 may be the same or different, but are preferably the same.

The aryl group and heteroaryl group that can be used as Ar ^x1 and Ar ^x2 may have a substituent (excluding the groups represented by any one of the above formulas 1-a to 1-c). The substituent is not particularly limited, and examples thereof include the substituent that R ^1S described later may have. The number of substituents that Ar ^x1 and Ar ^x2 have is not particularly limited and is appropriately determined. The substituents may combine with each other to form a ring. However, when the condensed ring to be formed also corresponds to the above-mentioned condensed aryl group or heteroaryl group, the condensed ring to be formed as a whole may be a condensed ring aryl group or heteroaryl that can be used as Ar ^x1 and Ar ^x2. Interpret as a group.

In Ar ^x1 and Ar ^x2 , a site (position of a ring-constituting atom) to be bonded to Ar ¹ or Ar ² (a nitrogen atom when n1 or n2 is 0) described later is not particularly limited, and may be an appropriate ring-constituting atom. Can be used as the connection site.
Ar ^x1 and Ar ^x2 may each be directly bonded to Ar ¹ or Ar ² (a nitrogen atom when n1 or n2 is 0) in the formula (S1), or may be bonded via a linking group. Good. The linking group that bonds Ar ^x1 and Ar ¹ and the linking group that bonds Ar ^x2 and Ar ² are not particularly limited, and examples thereof include an arylene group, a heteroarylene group, or a combination thereof. Examples of the arylene group or heteroarylene group that can be used as the linking group include an arylene group and a heteroarylene group that can be used as Ar ¹ . The number of groups to be combined is not particularly limited, but examples thereof include 2 to 5.

Ar ¹ and Ar ² are each an arylene group or a heteroarylene group, preferably an arylene group.
The arylene group that can be used as Ar ¹ and Ar ² is not particularly limited, and examples thereof include a group obtained by further removing one hydrogen atom from the aryl group that can be used as Ar ^x1 . Of these, a phenylene group, or a naphthalene ring group or a fluorene ring group is preferable.
The heteroarylene group that can be used as Ar ¹ and Ar ² is not particularly limited, and examples thereof include a group obtained by further removing one hydrogen atom from the heteroaryl group that can be used as Ar ^x1 . Of these, a thienylene group is preferable.
Each of Ar ¹ and Ar ² is preferably an arylene group, and more preferably a phenylene group.

The aryl group and heteroaryl group that can be used as Ar ¹ and Ar ² may have a substituent (excluding the groups represented by any one of the above formulas 1-a to 1-c). The substituent is not particularly limited, and examples thereof include the substituent that R ^1S described later may have. The number of substituents that Ar ¹ and Ar ² have is not particularly limited and is appropriately determined. The substituents may combine with each other to form a ring. Further, when adjacent Ar ^{1 s} , Ar ^x1 or Ar ^x2 and Ar ¹ or Ar ² , and further Ar ¹ and Ar ² bonded to the nitrogen atom in the formula (S1) each have a substituent, these substituents May combine with each other to form a ring. However, when the condensed ring to be formed also corresponds to the above-mentioned condensed ring arylene group or heteroarylene group, the condensed ring to be formed is interpreted as a condensed ring arylene group or heteroarylene group as a whole.

In Ar ¹ and Ar ² , the site (position of ring-constituting atom) that binds to Ar ^x1 or Ar ^x2 described above is not particularly limited, and an appropriate ring-constituting atom can be the linking site. For example, the 3-position or 4-position is preferable with respect to the ring-constituting atom bonded to the nitrogen atom in the formula (S1).
Ar ¹ and Ar ² may be the same or different, but are preferably the same. Further, Ar ^x1 and Ar ¹ , and Ar ^x2 and Ar ² may be the same or different, but are preferably the same.

n1 and n2 are each an integer of 0 or more, preferably an integer of 1 or more. The upper limit is not particularly limited, but an integer of 10 or less is preferable, and an integer of 5 or less is more preferable. More preferably, n1 and n2 are 1 or 2, respectively. n1 and n2 may be the same or different.
In the present invention, n1 and n2 are integers of 1 or more in total (n1 + n2 ≧ 1), preferably integers of 1 to 20 in total, more preferably integers of 2 to 10 in total, and particularly preferably Is an integer of 2 to 5 in total. When n1 and n2 are integers of 2 or more, Ar ¹ and Ar ² of 2 or more may be the same or different.

R ^1S represents a substituent. The substituent that can be adopted as R ^1S is not particularly limited, and examples thereof include an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an aryl group, a heteroaryl group, and an aliphatic heterocyclic group. Of these, an alkyl group, a cycloalkyl group, an aryl group, and a heteroaryl group are preferable. The alkyl group, cycloalkyl group, alkenyl group, alkynyl group and aliphatic heterocycle which can be adopted as R ^{1S have the same meanings} as the above-mentioned groups which can be adopted as R ^1A . The aryl group and the heteroaryl group that can be taken as R ^{1S have the same meanings} as the aryl group and the heteroaryl group that can be taken as Ar ^x1 .
R ^1S may be the same as or different from Ar ¹ or Ar ^2, and is preferably the same. In this aspect, R ^1S , Ar ¹ and Ar ² are preferably a group consisting of a benzene ring (a repeating unit in the formula (S1) is a unit derived from a triphenylamine compound).

The substituent that can be adopted as R ^1S may further have a substituent (provided that a group represented by any one of formulas 1-a to 1-c described later is excluded). The substituent which may be further possessed is not particularly limited, and examples thereof include an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an aryl group, and a heterocyclic group (aromatic heterocycle, aliphatic heterocyclic group). , Alkoxy group, alkylthio group, amino group (alkylamino group, arylamino group, etc.), acyl group, alkylcarbonyloxy group, alkenylcarbonyloxy group, aryloxy group, alkoxycarbonyl group, aryloxycarbonyl group, acylamino group, sulfone Examples thereof include an amide group, a carbamoyl group, a sulfamoyl group, a halogen atom, a cyano group, hydroxy, a carboxy group, and a silyl group (alkylsilyl group, arylsilyl group, etc.).
The above-mentioned alkyl group, cycloalkyl group, alkenyl group, alkynyl group, aryl group, aromatic heterocyclic group and aliphatic heterocyclic group have the same ^meanings as the corresponding groups of R ^1A . The alkyl group, the alkenyl group, or the aryl group, which is a group other than the above and has an alkyl group, an alkenyl group, or an aryl group (alkoxy group, alkylthio group, amino group, etc.), corresponds to the group that can be taken as R ^1A. Is synonymous with.
The number of the substituents that the substituent that can be used as R ^1S may further have is not particularly limited and is appropriately determined, but examples thereof include 1 to 7.
In the present invention, R ^1S and Ar ¹ or Ar ² bonded to the nitrogen atom in the formula (S1) are not bonded to each other, directly bonded (by a single bond), or via a linking group. Or both of the embodiments in which they are bonded to each other through the substituent which R ^1S , Ar ² or Ar ¹ has. In the present invention, an embodiment in which R ^1S and Ar ¹ or Ar ² are not bonded to each other is preferable.

n3 is an integer of 3 or more, preferably an integer of 3 to 5000, more preferably an integer of 3 to 1000, further preferably an integer of 5 to 200, and particularly preferably an integer of 5 to 50. In the present invention, n3 is the number of repeating units (degree of polymerization) in which the repeating units enclosed in square brackets in the above formula (S1) are bonded, and is a value calculated by the following method. That is, the number average molecular weight of the compound represented by the formula (S1) was measured by gel permeation chromatography to be described later, and the obtained number average molecular weight was divided by the molecular weight of the repeating unit (rounded to the nearest whole number). And
In the compound represented by the formula (S1), three or more repeating units may be the same or different. Further, the compound represented by the formula (S1) may include at least one polymer in which n3 is an integer of 3 or more, and may be a mixture of polymers having a plurality of different n3.

The specific group contained in the compound forming the hole transporting agent is a group represented by any of the following formulas 1-a to 1-c. In each formula, * indicates a linking site with the above compound (nucleus structure).

In the formula, R ¹ and R ² represent a substituent. The substituent that can be used as R ¹ and R ² is not particularly limited, and examples thereof include the substituent that the substituent that can be used as R ^1S may further have. Among them, an alkyl group, a cycloalkyl group, an aryl group or a heterocyclic group is preferable, and an alkyl group or a cycloalkyl group is more preferable.
In Formula 1-b, three R ² may be the same or different.

In Formula 1-a, R represents a hydrogen atom or a substituent. The substituent that can be used as R is not particularly limited, and examples thereof include the substituent that the substituent that can be used as R ^1S may further have. Among them, an alkyl group, a cycloalkyl group, an aryl group or a heterocyclic group is preferable, and an alkyl group or an aryl group is more preferable.

X ¹ represents -N (R ^a )-or -O-, and -O- is preferable.
Here, R ^a represents a hydrogen atom or a substituent. The substituent that can be used as R ^a is not particularly limited, and examples thereof include the substituent that the substituent that can be used as R ^1S may further have. Among them, an alkyl group, a cycloalkyl group, an aryl group or hetero A cyclic group is preferable, and an alkyl group or a cycloalkyl group is more preferable.

R ³ and R ⁴ represent a hydrogen atom, a substituent or a linking site with a compound described later, and a substituent or a linking site is preferable.
The substituent that can be used as R ³ and R ⁴ is not particularly limited, and examples thereof include the substituent that the substituent that can be used as R ^1S may further have, and among them, an alkyl group and a cycloalkyl group. , An alkenyl group, an alkynyl group or an aryl group is preferable, an alkyl group, a cycloalkyl group, an alkenyl group or an aryl group is more preferable, and an alkenyl group is still more preferable. R ³ and R ⁴ may combine with each other to form a ring.
Each of R ³ and R ⁴ can also be a connecting site with the above-mentioned mother structure. In this case, the group represented by the formula 1-c becomes a tetravalent group (partial structure) and may be incorporated in the mother nucleus structure. Examples of such a partial structure include a partial structure incorporated in the compound c3 for comparison used in Examples described later.

The group represented by any one of the above formulas 1-a to 1-c is introduced into the mother nucleus structure of the compound to improve the solubility of the compound in a solvent and the like, and to crystallize from a solvent. It is considered that the formability can also be improved. Among the above-mentioned specific groups, a group represented by Formula 1-a or Formula 1-c is preferable. When a compound having a group represented by Formula 1-a or Formula 1-c among the above-mentioned groups is reacted (modified or decomposed) with these groups to form another layer on the surface of the hole transport layer. In addition, it is possible to prevent the surface from being dissolved in the solvent in the layer forming liquid and effectively maintain the surface flatness after the film formation. The reaction of the above group is not particularly limited, but in the group represented by the formula 1-a, the R ¹ —O—CO— group is eliminated from the nitrogen atom (elimination or decomposition reaction) by acid treatment or base treatment. Then, it becomes a nitrogen-containing group such as an amino group, an amide group, a thioamide group or a salt thereof. On the other hand, the group represented by the formula 1-c becomes a benzene ring group by elimination (elimination or decomposition reaction) of the —CO—CO— group by the active energy ray irradiation treatment.

  The specific group represented by each of the above formulas may be bonded via the linking group at the linking site, but is preferably bonded directly to the mother nucleus structure. Such a linking group is not particularly limited and includes, for example, an alkylene group, an arylene group, a heteroarylene group, an ether group (-O-), a sulfide group (-S-), a carbonyl group, an imino group, or these. Examples of the linking group include a combination of two or more (preferably two or three).

  The compound may have at least one of the specific groups, but preferably has at least two and more preferably has two to four. The upper limit of the number of the compound having a specific group is not unique depending on the site where the specific group is introduced. For example, when a specific group is introduced into a repeating unit, it is the product of the number of repeating units and the number of repeating units in one repeating unit, and when the specific group is introduced into the terminal group, Is the maximum number of hydrogen atoms that can be substituted in the terminal group. When the compound has a plurality of specific groups, they may be the same or different, and are preferably the same. When a plurality of groups different from each other are contained, it is preferable that these groups are the same in the above reaction from the viewpoint of productivity.

The above-mentioned compound may have the above-mentioned specific group at any site of the nucleus structure, but at the point that a uniform film can be formed with high reproducibility (high film-forming ability), the end portion of the nucleus structure is It is preferable to have it at the end (if it is a polymer). Specifically, in the compound represented by the formula (S1), the specific group is preferably contained in at least one of Ar ^x1 and Ar ^{x2 in} the formula (S1), and Ar ^x1 and Ar ^x2. It is more preferable to have at least one in each, and it is more preferable to have one in each of Ar ^x1 and Ar ^x2 . The position at which the above-mentioned specific group is bonded to Ar ^x1 or Ar ^x2 is not particularly limited, but in view of film-forming ability, a ring of Ar ^x1 or Ar ^x2 that bonds to Ar ¹ or Ar ² in the formula (S1). The 2-position or 3-position is preferable with respect to the constituent atom (1-position).

The weight average molecular weight of the compound having the specific group is not particularly limited, but is preferably, for example, 500 to 2,000,000, because the network of the compound is more densely formed, and the photoelectric conversion efficiency can be improved. , 500 to 1,000,000, more preferably 1000 to 200,000.
In the above compound or polymer, the weight average molecular weight or the number average molecular weight means a value (standard polystyrene conversion value) measured by gel permeation chromatography (GPC) unless otherwise specified. The measuring device and the measuring conditions are basically based on the following conditions, but depending on the polymer species, an appropriate carrier (eluent) and a column suitable for it may be appropriately selected and used.
For other matters, refer to JIS K 7252-1 to 4: 2008. It should be noted that, for the sparingly soluble compound, the concentration is determined to be soluble under the following conditions.
-Condition-
・ Column: Two TOSOH TSKgel Super AWM-H (trade name) are connected ・ Carrier: 10 mM LiBr / N-methylpyrrolidone ・ Measurement temperature: 40 ° C
・ Carrier flow rate: 1.0 mL / min
・ Sample concentration: 0.1% by mass
・ Detector: RI (refractive index) detector ・ Injection volume: 0.1 mL

  The compound having the specific group can be synthesized by referring to a known method, or a commercially available product can be used. For example, it can be synthesized by introducing the above-mentioned specific group into a known hole-transporting material or a compound represented by the formula (S1) by a known method (for example, a coupling reaction of a compound having a specific group). .. Specific examples of the synthesizing method include the synthesizing methods described in Examples below.

  Hereinafter, specific examples of the compound having the above-described specific group will be illustrated, but the present invention is not limited thereto. In each formula, n3 has the same meaning as n3 in formula (S1). In addition, in compound S1-2, Me shows methyl.

  The content of the hole-transporting agent composed of the compound having a specific group in the hole-transporting layer is not particularly limited and is, for example, preferably 1 to 100% by mass, and 5 to 100% by mass. Is more preferable, and 10 to 100% by mass is further preferable. When the reaction product of the compound represented by the formula (S1) is contained as the hole transport agent, the content of the reaction product relative to the total of the compound (unreacted product) represented by the formula (S1) and the reaction product is It is not particularly limited, and is preferably 1% by mass or more, for example.

  The hole-transporting layer contains a hole-transporting agent (material) other than the hole-transporting agent composed of a compound having a specific group, a reaction catalyst of a compound having a specific group or a decomposition product thereof, and other components. You may have. As the hole-transporting agent other than the hole-transporting agent composed of the compound having a specific group, a known hole-transporting material having no specific group (for example, the above-mentioned material) may be used without particular limitation. it can. The content of the hole transport material may be in the range that does not impair the effects of the present invention, and is, for example, 99% by mass or less.

  In the photoelectric conversion element of the present invention, the hole transporting layer is provided with a layer containing the hole transporting agent of the present invention, and the hole transporting material other than the hole transporting agent of the present invention is used. It may or may not have a transport layer.

<Hole injection layer>
The photoelectric conversion element of the present invention may include a hole injection layer (not shown in FIGS. 1 to 5). The hole injection layer is a layer that receives electric charges from the hole transport layer (hole transport material) to generate free charges in the hole transport layer and improve the conductivity of the hole transport layer. The degree of improving the conductivity is not particularly limited, but is preferably about 1.01 to ^{10 10} times, for example. The hole injection layer is usually provided in the vicinity of the hole transport layer, and is provided on the side opposite to the photosensitive layer with respect to the hole transport layer, preferably adjacent to the hole transport layer.
Material for forming the hole injection layer is not particularly limited, for example, metal complexes, include metal salts or organic compounds, and more specifically, for _{example, (p-BrC 6 H 4} ) 3 NSbCl 6, three Valent cobalt complex (FK209 and others), LiTFSI (lithium bis (trifluoromethanesulfonyl) imide), FeCl ₃ , WO ₃ , MoO ₃ , Molybdenum tris (1- (trifluoroorcetyl) -2- (trifluoro)-(trifluoroethyl) -2- (trifluoro)). SnCl ₄ , SbCl ₅ , F4-TCNQ and the like can be mentioned.
The film thickness of the hole injection layer is not particularly limited, preferably 0.1 nm to 10 μm, more preferably 1 nm to 1 μm, still more preferably 10 nm to 0.5 μm.

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

[Solar cell]
The solar cell of the present invention is configured using the photoelectric conversion element of the present invention. For example, as shown in FIGS. 1 to 5, the photoelectric conversion element 10 configured to work the external circuit 6 can be used as a solar cell. The external circuit 6 connected to the first electrode 1 (conductive support 11) and the second electrode 2 may be a known one without particular limitation.
Further, a solar cell can be configured by connecting a plurality of photoelectric conversion elements of the present invention.
The present invention is disclosed in, for example, Patent Document 1, Non-Patent Documents 1 and 2, J. Am. Chem. Soc. , 2009, 131 (17), p. It can be applied to each solar cell described in 6050-6051.
The solar cell of the present invention is preferably sealed on the side surface with a polymer, an adhesive or the like in order to prevent the deterioration and evaporation of the constituents.

[Composition for forming hole transport layer and kit for forming hole transport layer]
Next, the composition for forming a hole transport layer and the kit for forming a hole transport layer, which are preferably used in both the method for producing the photoelectric conversion element of the present invention and the method for manufacturing the solar cell of the present invention, will be described.
The hole transport layer-forming composition and the hole transport layer-forming kit of the present invention can be applied to various electronic devices to form a hole transport film (hole transport layer). Above all, it is suitably used for forming a hole transport layer of a photoelectric conversion element, particularly a photoelectric conversion element using a perovskite compound as a light absorber.

<Hole transport layer forming composition>
The composition for forming a hole transport layer of the present invention contains the hole transport agent of the present invention described above. Among the hole-transporting agents of the present invention, this hole-transporting layer-forming composition preferably contains an unreacted compound of the compound having the above-mentioned specific group. In this case, the reaction of the unreacted compound is caused or It may also contain a accelerating reaction catalyst. The reaction catalyst is appropriately selected depending on the groups represented by the above formulas contained in the hole transfer agent of the present invention, and cannot be uniquely determined. For example, when the hole transfer agent of the present invention has a group represented by formula 1-a, the reaction catalyst includes an acid catalyst or a base catalyst. The composition for forming a hole transport layer may contain one kind of reaction catalyst or two or more kinds of reaction catalysts.
When the composition for forming a hole transport layer contains a reaction catalyst, it is prepared, handled, and further stored under the condition that the hole transport agent of the present invention does not cause a reaction. This condition is not unique depending on the type (combination) of the group represented by the above formula and the reaction catalyst, but is, for example, a temperature of 50 ° C. or less, a light-shielding environment, and the like. In the present invention, the hole-transporting layer-forming composition is used in the present invention unless the film-forming property (film-forming ability of the hole-transporting agent of the present invention), handleability, etc. of the composition for forming a hole-transporting layer are impaired. The reaction of the hole transfer material may occur. For example, the reaction may be carried out as long as it is 10 mol% or less based on the total number of moles of the group represented by the above formula.

  The composition for forming a hole transport layer of the present invention may contain other components, a solvent and the like.

  The solvent contained in the composition for forming a hole transport layer of the present invention is not particularly limited, and examples thereof include the solvents described in “Solvent or dispersion medium used in method for producing photoelectric conversion element” described below.

The content of the hole-transporting agent in the composition for forming a hole-transporting layer of the present invention is not particularly limited and is, for example, preferably 0.1 to 100% by mass, more preferably 0.1 to 50% by mass. , 0.5 to 20 mass% is more preferable, and 0.5 to 2 mass% is particularly preferable.
The content of the reaction catalyst in the composition for forming a hole transport layer of the present invention is appropriately determined according to the type or number of the above groups contained in the hole transport agent, the type of the reaction catalyst, or the like. .. The content of the reaction catalyst is usually a catalytic amount, but it may be used in excess. For example, it can be 0.001 to 100 parts by mass, preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the hole transport material.

  The content of the solvent in the composition for forming a hole transport layer of the present invention is not particularly limited, but is, for example, preferably 0 to 99.9% by mass, more preferably 10 to 99.9% by mass, and 80 to 99. More preferably, it is 0.9% by mass.

  The composition for forming a hole transport layer of the present invention can be prepared by mixing the respective components by a usual method. As the mixing conditions, the above-mentioned conditions in which the hole transport agent of the present invention does not undergo a curing reaction are preferably adopted.

<Kit for forming hole transport layer>
The kit for forming a hole transport layer of the present invention is a composition obtained by combining a composition containing the hole transfer agent of the present invention (hole transfer agent composition) and a composition containing a reaction catalyst (catalyst composition). It is a thing kit. In this kit for forming a hole transport layer, the reaction catalyst constitutes the kit as a drug or component independent of the hole transport agent of the present invention. The hole transport material and the reaction catalyst of the present invention are as described above. The form of the hole transport material composition and the catalyst composition is not particularly limited, and may be a form of the hole transport material or the reaction catalyst alone, or in the form of a mixture with other components, a solvent, etc. It may be. The reaction catalyst and solvent are as described in the composition for forming a hole transport layer of the present invention. In the hole transport layer forming kit, an appropriate reaction catalyst is combined depending on the groups represented by the above formulas contained in the hole transport agent. Specific examples of the combination include commonly used combinations, and are, for example, as described in the above-mentioned composition for forming a hole transport layer of the present invention.

In the hole-transporting material composition, the content of the hole-transporting material is not particularly limited, and is, for example, preferably 0.1 to 99% by mass, more preferably 0.5 to 20% by mass, and 0.5 to 2%. Mass% is more preferable. The content of the solvent is not particularly limited and is, for example, preferably 0 to 99.9% by mass, more preferably 90 to 99.9% by mass.
In the catalyst composition, the content of the reaction catalyst is not particularly limited and may be, for example, 0.01 to 100% by mass, preferably 1 to 10% by mass.

The amount of the reaction catalyst to be used is appropriately determined depending on the type or number of the above groups contained in the hole transfer agent in the hole transfer agent composition combined with the catalyst composition, the type of the reaction catalyst, or the like. The amount used refers to the ratio of the reaction catalyst that actually reacts or acts on the hole transfer material in the hole transfer material composition. For example, when the catalyst composition is applied on the coating film of the hole transfer material composition by the spin coating method, it refers to the ratio of the reaction catalyst remaining after the spin coating. The amount of the reaction catalyst used with respect to the hole transfer agent is usually a catalytic amount, but it may be used in excess. The amount used is not unique, but can be, for example, 0.01 to 100 parts by mass.
The hole transport layer forming kit may have a combination of a composition comprising a solvent or the like for adjusting the concentration of the hole transport agent composition or the catalyst composition.
The method of using this kit will be described in the method of manufacturing a hole transport film described later.

[Method for manufacturing photoelectric conversion element and method for manufacturing solar cell]
Both the method for producing a photoelectric conversion element of the present invention and the method for producing a solar cell of the present invention (hereinafter collectively referred to as the production method of the present invention) include (via) the method for producing a hole transport film of the present invention described below, It is a method for producing the photoelectric conversion element or the solar cell of the present invention.
The production method of the present invention will be described below.
The photoelectric conversion element and the solar cell of the present invention can be manufactured by a usual manufacturing method, for example, Patent Document 1, Non-Patent Document 1, J. Am. Chem. Soc. , 2009, 131 (17), p. 6050-6051, and Science, 338, p. It can be manufactured according to the method described in 643 (2012) and the like.

The photoelectric conversion element of the present invention is preferably manufactured by a manufacturing method including a step of providing a photosensitive layer on a conductive support and a step of providing a hole transport layer before or after this step.
In this manufacturing method, providing the photosensitive layer on the conductive support means that the photosensitive layer is provided (directly provided) in contact with the surface of the conductive support, and another layer is provided above the surface of the conductive support. It is meant to include a mode in which the photosensitive layer is provided via the. In the embodiment in which the photosensitive layer is provided above the surface of the conductive support via another layer, the other layers provided between the conductive support and the photosensitive layer are as described above.

<Method for manufacturing photoelectric conversion element>
-Preparation of first electrode-
In the manufacturing method of the present invention, first, the conductive support 11 is prepared according to the above-mentioned method or a known method. Next, at least one of the blocking layer 14, the porous layer 12, the electron transport layer 15, and the hole transport layer 16 is formed on the surface of the conductive support 11, if desired.

(Formation of blocking layer)
The blocking layer 14 can be formed by, for example, a method of applying a dispersion containing the above-mentioned insulating substance or a precursor compound thereof to the surface of the conductive support 11 and firing it, or a spray pyrolysis method.

(Formation of porous layer)
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, the method described in Chemical Review, Vol. 110, page 6595 (2010)). Be done. In these methods, after the dispersion (paste) is applied to the surface of the conductive support 11 or the surface of the blocking layer 14, baking may be performed at a temperature of 100 to 800 ° C. for 10 minutes to 10 hours, for example, in the air. preferable. This makes it possible to bring the fine particles into close contact with each other.
When firing is performed a plurality of times, the firing temperature other than the last firing (the firing temperature other than the last) is preferably lower than the last firing temperature (the last firing temperature). For example, when using a titanium oxide paste, the firing temperature other than the last can be set within the range of 50 to 300 ° C. Further, the final firing temperature can be set so as to be higher than the firing temperatures other than the last firing temperature within the range of 100 to 600 ° C. When a glass support is used as the support 11a, the firing temperature is preferably 60 to 500 ° C.
The coating amount of the porous material when forming the porous layer 12 is appropriately set according to the film thickness of the porous layer 12, the number of coatings, and the like, and is not particularly limited. The coating amount of the porous material per 1 m ² of surface area of the conductive support 11 is, for example, preferably 0.5 to 500 g, more preferably 5 to 100 g.

(Formation of electron transport layer or hole transport layer)
When the electron transport layer 15 or the hole transport layer 16 is provided, they can be formed in the same manner as the hole transport layer 3 or the electron transport layer 4 described later, respectively.
When the hole transport layer 16 is provided on the transparent electrode 11, a hole injection layer can be formed prior to the formation of the hole transport layer 16 if desired. The method for forming the hole injection layer will be described later.

(Formation of photosensitive layer)
Then, the photosensitive layer 13 is provided.
The perovskite compound used for forming the photosensitive layer can be synthesized from a compound represented by the following formula (II) and a compound represented by the following formula (III).
Formula (II): AX
Formula (III): MX ₂
In the formula (II), A represents a Group 1 element of the periodic table or a cationic organic group, has the same meaning as A in the formula (I), and the preferred ones are also the same. X represents an anionic atom or atomic group, has the same meaning as X in the above formula (I), and the preferred ones are also the same. The compound represented by the formula (A-2) is usually a compound in which a cation M of a metal atom other than an element belonging to Group 1 of the periodic table and an anionic atom or X of an atomic group are ionically bonded.
In the formula (III), M represents a metal atom other than the Group 1 element of the periodic table, has the same meaning as M in the formula (I), and the preferred ones are also the same. X represents an anionic atom or atomic group, has the same meaning as X in the above formula (I), and the preferred ones are also the same. The compound represented by the formula (A-3) is usually a compound in which the cation A of the Group 1 element of the periodic table or the cationic organic group and X of the anionic atom or atomic group are ionically bonded.

  In the manufacturing method of the present invention, the method of providing the photosensitive layer 14 includes a wet method and a dry method, and is not particularly limited. In the present invention, a wet method is preferable, for example, a method of contacting with a light absorbent composition (solution) containing a light absorbent is preferable.

In the manufacturing method of the present invention, first, a light absorber composition for forming the photosensitive layer 14 is prepared. The light absorber composition may be a composition containing the perovskite compound itself, but the compound represented by the formula (II) and the compound represented by the formula (III), which are raw materials for synthesizing the perovskite compound. A composition containing each is preferred. In this light absorber composition, the molar ratio of the compound (AX) represented by the above formula (II) and the compound (MX ₂ ) represented by the above formula (III) is appropriately adjusted according to the purpose. . When forming the perovskite compound as a light absorbing agent, the molar ratio of AX and MX ₂ is 1: 1 to 10: 1. This light absorber composition can be prepared by mixing AX and MX ₂ in a predetermined molar ratio and then preferably heating. This composition is usually a solution, but may be a suspension. The heating conditions are not particularly limited, but the heating temperature is preferably 30 to 200 ° C, more preferably 60 to 150 ° C. The heating time is preferably 0.5 to 100 hours, more preferably 1 to 20 hours, still more preferably 1 to 3 hours. As the solvent or dispersion medium, those described below can be used.

  Next, the prepared light absorber composition is used to form a layer on the surface of which the photosensitive layer 13 is formed (also referred to as a photosensitive layer-forming layer, for example, any one of the porous layer 12, the blocking layer 14 and the electron transport layer 15). Of the above). Specifically, it is preferable to coat the surface of the layer on which the photosensitive layer is formed with the light absorber composition or immerse the layer on which the photosensitive layer is formed in the light absorber composition. As a result, the perovskite compound is deposited or adsorbed on the surface of the photosensitive layer forming layer to form the photosensitive layer. The contact temperature is preferably 5 to 100 ° C., the immersion time is preferably 5 seconds to 24 hours, and more preferably 20 seconds to 1 hour. The coating conditions can be appropriately determined depending on the film thickness and the like. When the applied light absorber composition is dried, the light absorber composition is preferably dried by heat, and is usually dried by heating at 20 to 300 ° C., preferably 50 to 170 ° C. under normal pressure. .

Further, AX compositions containing the AX and (ammonium salt composition), MX ₂ compositions containing the MX ₂ and (metal salt composition), separately, into contact with the surface of the photosensitive layer to be formed layer The method is also included. In this method, either composition may be contacted first, but preferably the MX ₂ composition is contacted first. In this method, the molar ratio of AX and MX ₂ , the method of contacting and the conditions, and the drying conditions are the same as in the above method. In this method, instead of contacting the AX composition and the MX ₂ composition, AX or MX ₂ may be vapor-deposited.

Further, a dry method such as vacuum deposition using a compound or mixture obtained by removing the solvent of the above-mentioned light absorber composition can be mentioned. For example, a method of vapor-depositing the AX and the MX ₂ simultaneously or sequentially may be used.

  As another method, the photosensitive layer can be formed according to the method of synthesizing the perovskite compound. Regarding the method for synthesizing the perovskite compound, for example, the method described in Patent Document 1 can be referred to. Also, J. Am. Chem. Soc. , 2009, 131 (17), p. The method described in 6050-6051 can also be referred to.

  In this way, the photosensitive layer 13 is formed on the surface of the layer on which the photosensitive layer is formed, and the first electrode is produced.

  In the manufacturing method of the present invention, the hole transport layer 3 or the electron transport layer 4 is formed on the photosensitive layer 13.

-Formation of hole transport layer-
In the manufacturing method of the present invention, the method for forming the hole transport layer is not particularly limited as long as the hole transport layer containing the hole transport agent composed of the compound having the specific group can be formed. When the hole transport layer of the photoelectric conversion element is formed by the method for producing a hole transport film of the present invention, a method for performing the method for producing a hole transport film of the present invention on the surface of the photosensitive layer 13 or the conductive support 11. Is preferred.

(Method for producing hole transport film of the present invention)
The method for producing a hole transport film of the present invention includes the above-described composition for forming a hole transport layer of the present invention or the kit for forming a hole transport layer of the present invention (hereinafter simply referred to as a composition for forming a hole transport layer, etc.). However, it is preferable to use The hole transport agent contained in the hole transport layer forming composition of the present invention and the hole transport layer forming kit of the hole transport layer forming kit is a compound represented by formula (S1) represented by formula 1-a or When it has a group represented by formula 1-c (when the compound represented by formula (S1) is a reactive compound), it may contain a reaction product of the above compound, but it is an unreacted product of the above compound. The inclusion of is preferable from the viewpoint of the state of formation of the hole transport film. Therefore, the method for producing a hole transport film of the present invention includes a method in which the compound (specific group) in the composition for forming a hole transport layer is not positively reacted, and a method in which the compound is positively reacted. Both methods are included.

  As a method of not positively curing the above compound (including a method of forming a coating film of a composition for forming a hole transport layer in a mode of reacting in a post-treatment described later), a composition for forming a hole transport layer is included. Can be applied to the surface of the photosensitive layer 13 (including a dip coating method) and dried if desired. The composition for forming a hole transport layer used in this method may contain either an unreacted product or a reaction product of the above compound. Further, this composition for forming a hole transport layer may contain the above-mentioned reaction catalyst, but it is preferable not to contain it (hole transfer agent composition). When the composition for forming a hole transport layer is applied by spin coating, the conditions are not particularly limited, but for example, the rotation speed may be 10 to 20,000 rpm and the application time may be 1 to 600 seconds. When the applied composition for forming a hole transport layer is dried, the drying conditions are appropriately set depending on the kind of the hole transport agent, the reaction catalyst of the hole transport agent, and the like. When the hole transporting agent is not positively reacted in this drying step, the drying condition is set such that the reaction of the compound having the specific group in the composition for forming the hole transporting layer is not completed. Usually, when the composition for forming a hole transport layer is dried, the hole transport agent may be changed depending on the kind of the hole transport agent, the group represented by any one of formulas 1-a to 1-c, and the reactants. May partially react, but with an unreacted state or a partially reacted state (for example, 10 mol% or less with respect to the total number of moles of the group represented by any one of formulas 1-a to 1-c) The following drying conditions apply. As such a drying condition, a heating condition is preferable, and for example, a method and a condition of heating at a heating temperature of 30 to 200 ° C., preferably 40 to 110 ° C. for 1 minute or more are mentioned. From the viewpoint of suppressing the reaction of the group represented by Formula 1-a or the like, the heating temperature may be, for example, less than 100 ° C, preferably 30 ° C or more and less than 100 ° C, more preferably 40 to 70 ° C.

The method of positively reacting the compound is not particularly limited as long as the compound can be reacted on the surface of the photosensitive layer 13, and may be appropriately selected depending on the form of the composition for forming a hole transport layer or the like. The method can be adopted. In this method, a compound (unreacted product) having a group represented by the above formula 1-a or formula 1-c among the above specific groups is used.
In this method, the amount of the reaction catalyst used with respect to the hole transfer agent is as described above.
The method for positively curing the above compound will be specifically described below.

1. Embodiment in which the hole-transporting agent of the present invention comprises a compound having a group represented by Formula 1-a In this embodiment, after the composition for forming a hole-transporting layer is applied (optionally dried) on the surface of the photosensitive layer. As the reaction step, a method of performing at least one post-treatment of acid treatment and base treatment as (insolubilization treatment) is preferable. As a result, the group represented by the formula 1-a in the compound can be converted to the group represented by the formula 1-a depending on the skeleton of the group (type of R ^1S etc.), the catalyst species of the post-treatment, the conditions and the like. The compound can be insolubilized by being cleaved and decomposed into a nitrogen-containing group such as an amino group, an amide group or a thioamide group or a salt thereof.
The coating conditions and drying conditions for coating and drying the hole transport layer-forming composition are not particularly limited, and for example, the same coating conditions and drying as the above-described method of not positively curing the hole transporting agent. Conditions are mentioned.
The acid treatment and the base treatment are not particularly limited as long as they are methods and conditions capable of reacting (decomposing or cleaving) the group represented by Formula 1-a, and for example, a composition for forming a hole transport layer. There is a method of bringing the above-mentioned acid catalyst or base catalyst into contact with the coating film of the substance as a reaction catalyst. Here, the coating film of the composition for forming a hole transport layer means a film formed by applying the composition for forming a hole transport layer, and in the case of drying the applied composition for forming a hole transport layer. Includes a coated and dried film. The contact method and conditions are not particularly limited, and examples thereof include a contact method and a contact condition between the photosensitive layer-forming layer and the light absorber, but a composition containing a reaction catalyst is more preferable than the dipping method on the surface of the coating film. The method of applying to is preferable.
The acid treatment or the base treatment can be performed alone or in combination of two or more types depending on the composition of the composition for forming a hole transport layer.

After performing the acid treatment or the base treatment in this manner, a drying treatment is preferably performed. The drying conditions are not particularly limited, and examples thereof include the same drying conditions as the above-mentioned method in which the hole transport material is not positively cured.
In the method of bringing the reaction catalyst into contact with the composition for forming a hole transport layer containing no reaction catalyst, for example, the above-described kit for forming a hole transport layer of the present invention can be used.

2. Embodiment in which the hole-transporting agent of the present invention comprises a compound having a group represented by Formula 1-c In this embodiment, after the composition for forming a hole-transporting layer is applied (optionally dried) to the surface of the photosensitive layer. In the reaction step, a method of performing active energy ray irradiation treatment as a post-treatment (insolubilization treatment) is preferable. Thereby, the group represented by formula 1-c in the compound can be modified (decomposed) into a benzene ring to insolubilize the compound.
The coating conditions and drying conditions for coating and drying the hole transport layer-forming composition are not particularly limited, and for example, the same coating conditions and drying as the above-described method of not positively curing the hole transporting agent. Conditions are mentioned.
The active energy ray used for the active energy ray irradiation treatment is not particularly limited, and examples thereof include rays such as deep ultraviolet rays, ultraviolet rays, near ultraviolet rays and infrared rays, electromagnetic waves such as X rays and γ rays, electron beams, proton rays, and the like. Examples include neutron rays. Plasma can also be used. Ultraviolet rays are preferable in terms of curing speed, availability of irradiation equipment, and price.
The device for irradiating the active energy ray is not particularly limited, but examples thereof include a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp that emits light in the wavelength range of 150 to 450 nm, an ultrahigh pressure mercury lamp, a carbon arc lamp, a metal halide lamp, and a Deep- UV light, xenon lamp, chemical lamp, carbon arc lamp, electrodeless discharge lamp, ultraviolet LED and the like can be used. The energy of light irradiation is not particularly limited, but is preferably ¹ to 10 J / cm ² , for example.
The condition for irradiating the electron beam is not particularly limited, but for example, a condition for irradiating the electron beam with an accelerating voltage of 30 to 1,000 kV for 1 second to 30 minutes using a known electron beam irradiating device (EPS). Is mentioned.
The conditions for irradiating the plasma are not particularly limited, but, for example, the conditions for irradiating 1 second to 30 minutes by using a known plasma ray irradiation device with nitrogen gas, argon gas, helium gas or the like as the discharge gas may be used. Can be mentioned.

  The above-mentioned post-treatment can be performed alone or in combination of two or more types depending on the composition of the composition for forming a hole transport layer.

  After performing the active energy ray irradiation treatment in this way, a drying treatment can also be performed. The drying conditions are not particularly limited, and examples thereof include the same drying conditions as the above-mentioned method in which the hole transport material is not positively cured.

As described above, the hole transport layer can be formed on the surface of the photosensitive layer 13.
When the hole transport layer in the photoelectric conversion element is formed by the method for manufacturing a hole transport film of the present invention, a uniform hole transport layer can be formed with good reproducibility even by an ordinary solution coating method, and the moisture resistance and durability can be varied. Contribute to the reduction and improvement of In particular, the method of reacting the compound having the specific group described above does not impair the high surface flatness of the hole transport layer (provides an interface defect) when another layer is provided on the surface of the hole transport layer, An excellent interface state between the hole transport layer and another layer can be maintained. As a result, it is possible to contribute to further reduction in variations in humidity resistance and durability.

  In the manufacturing method of the present invention, the formation liquid for the layer formed on the surface of the hole transport layer may contain an appropriate solvent from the solvents described below. In particular, when the above compound contains a reactant in the hole transport layer, the solubility of the hole transport layer (particularly in the vicinity of the surface) in the solvent is lowered (insolubilized), and No particular solvent need be selected to maintain surface flatness.

-Formation of hole injection layer-
In the manufacturing method of the present invention, after forming the hole transport layer 3, a hole injection layer is formed if desired. The hole-injection layer can be formed by applying a hole-injection material solution containing the above-mentioned material and drying it, or by a dry method (evaporation or the like) using the above-mentioned material.

− Formation of electron transport layer −
The electron transport layer 4 can be formed, for example, by applying an electron transport material composition containing an electron transport material and drying the composition. The coating temperature and coating time are not particularly limited and may be set appropriately. The electron transport material composition is preferably dried under heating conditions, usually 30 to 200 ° C., preferably 40 to 110 ° C.

-Preparation of the second electrode-
In the manufacturing method of the present invention, the second electrode 2 is further formed on the hole transport layer 3, the hole injection layer or the electron transport layer 4. The second electrode 2 can be formed by a known method.

  In this way, the photoelectric conversion element of the present invention can be manufactured.

− Layer forming conditions, etc. −
The film thickness of each layer can be set by appropriately changing the concentration of the composition (solution or dispersion) forming each layer and the number of times of coating (immersion time). For example, when the photosensitive layers 13B and 13C having a large film thickness are provided, the composition for forming a photosensitive layer, the ammonium salt composition or the metal salt composition may be applied and dried plural times.

  Each of the above-mentioned dispersions and compositions may contain an appropriate additive such as a dispersion aid and a surfactant.

  Examples of the solvent or dispersion medium used in the method for producing a photoelectric conversion element include the solvents described in JP 2001-291534 A, but are not particularly limited thereto. In the present invention, an organic solvent is preferable, and further, an alcohol solvent, an amide solvent, a nitrile solvent, a hydrocarbon solvent, a lactone solvent, a halogen solvent, a sulfide solvent, and a mixed solvent of two or more kinds thereof are preferable. The mixed solvent is preferably a mixed solvent of an alcohol solvent and a solvent selected from an amide solvent, a nitrile solvent or a hydrocarbon solvent. Specifically, methanol, ethanol, isopropyl alcohol, γ-butyrolactone, n-propyl sulfide, chloroform, chlorobenzene, acetonitrile, N, N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO) or dimethylacetamide, or these Mixed solvents are preferred.

The method for applying the composition or the dispersant for 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, Known coating methods such as an inkjet printing method and a dipping method can be used. Of these, spin coating, screen printing, dipping and the like are preferable.
The atmosphere for performing each treatment such as coating and drying is not particularly limited, but is preferably a low humidity environment, for example, under dry air, in an inert gas (for example, in an argon gas, a helium gas, or a nitrogen gas). Middle).

  The photoelectric conversion device of the present invention may be subjected to efficiency stabilization treatment such as annealing, light soaking, and leaving in an oxygen atmosphere.

<Method of manufacturing solar cell>
The solar cell of the present invention can be manufactured through the method for manufacturing a photoelectric conversion element of the present invention described above. Specifically, a solar cell can be manufactured by connecting the external circuit 6 to the first electrode 1 and the second electrode 2 of the photoelectric conversion element manufactured as described above. In the method for manufacturing a solar cell of the present invention, a plurality of photoelectric conversion elements may be connected to form a photoelectric conversion element unit before or after the external circuit 6 is connected, and a solar cell may be formed using the photoelectric conversion element unit.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited thereto.
In the following examples, "parts" and "%" representing compositions are based on mass unless otherwise specified. In the present invention, "room temperature" means 25 ° C.

[Synthesis of Compound Having Specific Group Above and Represented by Formula (S1)]
The compounds S1-1 to S1-4 and S1-10 used in the examples were synthesized as follows.
Hereinafter, the method for synthesizing the compound having the above-mentioned specific group used in the examples will be described in detail, but the starting material, the dye intermediate and the synthetic route are not limited thereto.

<Synthesis Example 1: Synthesis of compound S1-1>
Compound S1-1 was synthesized based on the following scheme.

-Synthesis of Compound S1d-
2 g of 4,4′-dibromotriphenylamine S1a and 1.05 molar equivalent of compound S1b were mixed in toluene, to which 5 mol% Pd (PPh ₃ ) ₄ and 2 molar equivalents were based on amine S1a. Potassium carbonate was added and the mixture was heated to 100 ° C. and stirred under a nitrogen atmosphere for 8 hours. To the resulting mixture, compound S1b was added in an amount of 0.05 molar equivalent with respect to amine S1a and stirred for 1 hour, and then 0.2 molar equivalent of compound S1c was added and further stirred for 1 hour. The obtained reaction product was allowed to cool to room temperature, water and chloroform were added for liquid separation, and the organic layer was concentrated and purified by column chromatography to obtain 1.3 g of compound S1d.
Compound S1b can be synthesized according to Journal of Materials Chemistry, 2012, vol. 22, # 16, p. It was synthesized according to the method described in 7945.

-Synthesis of Compound S1-1-
1 mol equivalent of di-tert-butyl dicarbonate and 2 mol equivalents of triethylamine were mixed in methylene chloride at 0 ° C. for 6 hours with respect to the total amount of S1d thus obtained and the compound S1a used as a raw material for the compound S1d. It was stirred. Then, the obtained reaction product was allowed to cool to room temperature and further stirred for 2 hours, and subsequently water was added to separate the layers. The obtained organic layer was concentrated and then purified by column chromatography to obtain 0.3 g of compound S1-1.
The weight average molecular weight and the number average molecular weight of the compound S1-1 were measured, and the degree of polymerization n3 was calculated from the number average molecular weight (hereinafter, the same applies to other synthesized compounds).
Weight average molecular weight: 22000
Number average molecular weight: 9500 (n3 = 39)

<Synthesis Examples 2 and 3: Synthesis of Compounds S1-2 and S1-3>
-Synthesis of Compounds S1-2 and S1-3-
In the synthesis of compound S1-1, (4-bromophenyl) (trimethylsilyl) ether or the following compound S3a was used in place of compound S1c (except for the reaction with di-tert-butyl dicarbonate). , S1-2 and S1-3 were respectively synthesized in the same manner as the synthesis of compound S1-1.
Compound S3a is synthesized according to Tetrahedron, 1990, vol. 46, # 13/14, p. 4573-4586, Journal of the American Chemical Society, 2006, vol. 128, # 30, p. 9612-9613 and Chemical Communications, 2013, vol. 49, # 35, p. It was synthesized according to the method described in each of the documents of 3661-3663.

-Identification of compound S1-2-
Weight average molecular weight: 23000
Number average molecular weight: 9800 (n3 = 40)
-Identification of compound S1-3-
Weight average molecular weight: 22000
Number average molecular weight: 9600 (n3 = 40)

<Synthesis Example 4: Synthesis of compound S1-4>
-Synthesis of Compound S1-4-
Compound S1-4 was synthesized based on the following scheme.

2.2 g of compound S4a and 0.5 molar equivalent of compound S4b were mixed in n-butanol, heated to 130 ° C. and stirred for 4 hours. The obtained reaction product was allowed to cool to room temperature, water and chloroform were added for liquid separation, and the organic layer was concentrated and purified by column chromatography to obtain 0.7 g of compound S1-4.
Compound S4a was synthesized by reacting 5-amino-2,3,3-trimethyl-3H-indole with di-tert-butyl dicarbonate according to a known method.
The compound S1-4 was confirmed by mass spectrometry (Mass Spectrometry: MS).
MS-ESI m / z = 627.3 (M + H).

<Synthesis Example 5: Synthesis of compound S1-10>
In the synthesis of compound S1d, except that compound S1c was not used and 2.5 molar equivalents of compound S1c were used with respect to compound S1b, and compound S1c was not added in the latter stage of the reaction, In the same manner as above, an intermediate compound having an amino group at the terminal (n3 = 1 in the above compound S1d) was obtained.
Compound S1-10 was obtained by reacting the obtained intermediate compound with di-tert-butyl dicarbonate according to a known method.
The structure of compound S1-10 was confirmed by mass spectrometry.
MS-ESI m / z = 628.3 (M + H) ⁺

For comparison, the following hole transport materials and the following compounds c1 to c5 were prepared.
spiro-MeTAD: tetrakis (N, N-di-p-methoxyphenyl-amine) -9,9'-spiro-bifluorene (manufactured by Aldrich)
PTAA: poly [bis (4-phenyl) (2,4,6-trimethylphenyl) amine] (weight average molecular weight 16000, number average molecular weight 8000, manufactured by Aldrich)
In addition, the alkyl groups of the compounds c1 and c2 shown below are both linear alkyl groups, and Me in the compound c5 represents a methyl group.

<Synthesis Examples 6 and 7: Synthesis of Compounds c1 and c2>
-Compounds c1 and c2 synthesis-
In the synthesis of compound S1-1, 4-bromo-N, N-dibutylaniline or 4-n-octyloxybromobenzene was used in place of compound S1c (reaction with di-tert-butyl dicarbonate was performed. Compounds c1 and c2 were respectively synthesized in the same manner as in the synthesis of compound S1-1, except that
-Identification of compound c1-
Weight average molecular weight: 21,000
Number average molecular weight: 9200 (n3 = 38)
-Identification of compound c2-
Weight average molecular weight: 22000
Number average molecular weight: 9400 (n3 = 39)

<Synthesis Example 8: Synthesis of compound c3>
-Synthesis of Compound c3-
It was synthesized according to the method described in Tetrahedron Letters, 2005, 12, 1981.
The structure of compound c3 was confirmed by mass spectrometry.
MS-ESI m / z = 335.1 (M + H) ^+.
<Synthesis Examples 9 and 10: Synthesis of Compounds c4 and c5>
-Synthesis of Compounds c4 and c5-
In the synthesis of the compound S1d, 2.5 mol equivalents of the compound S3a or (4-bromophenyl) (trimethylsilyl) ether to the compound S1b were used in the latter stage of the reaction of the compound S1c without using the compound 1a. Compounds c4 and c5 were obtained according to the synthesis of compound S1d except that no addition was performed.
The structures of compounds c4 and c5 were confirmed by mass spectrometry.
Compound c4: MS-ESI m / z = 710.2 (M + H) ⁺
Compound c5: MS-ESI m / z = 574.3 (M + H) ⁺

[Evaluation of solubility]
The solubility of the compounds S1-1 to S1-4, S1-10, spiro-MeTAD, PTAA and c1 to c5 in a solvent was evaluated.
As a result, it was confirmed that all the compounds were completely dissolved at the visual level under the conditions (12 mg / mL in chloroform) of the hole transport layer composition in the examples.

Example 1
[Production of photoelectric conversion element (Sample No. 101)]
The photoelectric conversion element 10A shown in FIG. 1 was manufactured by the procedure shown below. When the photosensitive layer 13 has a large film thickness, it corresponds to the photoelectric conversion element 10B shown in FIG.

<Preparation of first electrode>
-Preparation of conductive support 11-
A fluorine-doped SnO ₂ conductive film (transparent electrode 11b, film thickness 300 nm) was formed on a glass substrate (transparent substrate 11a, thickness 2 mm) to prepare a conductive support 11.

-Formation of blocking layer 14-
First, a 15 mass% isopropanol solution of titanium diisopropoxide bis (acetylacetonate) (manufactured by Aldrich) was diluted with 1-butanol to prepare a 0.02 M (mol / L) blocking layer solution.
Then, a blocking layer 14 (thickness: 50 nm) made of titanium oxide was formed on the SnO ₂ conductive film of the conductive support 11 by spray pyrolysis using this blocking layer solution at 450 ° C.

-Formation of porous layer 12-
First, ethyl cellulose, lauric acid and terpineol were added to an ethanol dispersion of titanium oxide (anatase, average particle size 20 nm) to prepare a titanium oxide paste.
Next, the prepared titanium oxide paste was applied onto the blocking layer 14 by a screen printing method, and baked in air at 500 ° C. for 3 hours. Thereafter, the obtained fired body of titanium oxide was immersed in a 40 mM TiCl ₄ aqueous solution, and then heated at 60 ° C. for 1 hour, and subsequently heated at 500 ° C. for 30 minutes to form a porous layer 12 (made of TiO ₂ A film thickness of 250 nm) was formed.

-Formation of photosensitive layer 13A-
(Preparation of light absorber solution A)
A 40 mass% methanol solution of methylamine (27.86 mL) and a 57 mass% aqueous solution of hydrogen iodide (hydroiodic acid, 30 mL) were stirred in a flask at 0 ° C. for 2 hours and then concentrated. A crude product of CH ₃ NH ₃ I was obtained. The obtained CH ₃ NH ₃ I crude product was dissolved in ethanol and recrystallized from diethyl ether. The obtained crystals were collected by filtration and dried under reduced pressure at 60 ° C. for 5 hours to obtain purified CH ₃ NH ₃ I. Obtained.
Then, purified CH ₃ NH ₃ I and PbI ₂ were stirred and mixed in DMF at a molar ratio of 3: 1 at 60 ° C. for 12 hours, and then filtered through a polytetrafluoroethylene (PTFE) syringe filter to obtain 40% by mass. A light absorber solution A was prepared.
(Formation of photosensitive layer)
The prepared light absorbing agent solution A was applied onto the porous layer 12 formed on the conductive support 11 by the spin coating method (at 2000 rpm for 60 seconds) (application temperature: 25 ° C.), and then applied light absorption. The agent solution A was dried on a hot plate at 100 ° C. for 60 minutes to form a photosensitive layer 13A (thickness 300 nm (including the thickness 250 nm of the porous layer 12)) made of a perovskite compound of CH ₃ NH ₃ PbI ₃ . did.

  Thus, the first electrode 1A was produced.

<Formation of hole transport layer 3A>
— Composition for forming hole transport layer No. Preparation of 101-
A hole-transporting material (12 mg) composed of the compound S1-1 as a hole-transporting material is dissolved in chloroform (1 mL), and then filtered with a polytetrafluoroethylene (PTFE) syringe filter to form a hole-transporting layer forming composition. Material (solution) No. 101 was prepared.
-Formation of hole transport layer-
Then, the composition No. 1 for forming a hole transport layer. 101 is applied (coating temperature: 25 ° C.) on the photosensitive layer 13A formed on the surface of the first electrode 1A by spin coating (3,000 rpm for 30 seconds), and the applied composition for forming a hole transport layer. The product was dried (50 ° C., 10 minutes) to form a solid hole transport layer 3A (film thickness 60 nm). The content of the compound S1-1 in the hole transport layer 3A was 100% by mass.
The hole transport layer contained the compound S1-1 (unreacted material) as a hole transport agent.

<Production of second electrode 2>
Gold was vapor-deposited on the hole transport layer by a vapor deposition method to prepare the second electrode 2 (film thickness 100 nm).
Thus, the photoelectric conversion element 10A (Sample No. 101) was manufactured.
Each film thickness was observed and measured by a scanning electron microscope (SEM) according to the above method.

[Production of photoelectric conversion element (Sample Nos. 102 to 105)]
Sample No. Sample No. 101 except that the compound S1-1 was changed to the compound shown in Table 1 in the production of the photoelectric conversion element of No. 101. Sample No. 101 in the same manner as in the production of the photoelectric conversion element of No. 101. The photoelectric conversion elements 10 of 102 to 105 were manufactured.
Each sample No. The hole transport layer of the photoelectric conversion element of No. 2 contained compounds S1-2 to S1-4 and S1-10 (unreacted substances) as hole transport agents, respectively.

[Production of photoelectric conversion element (Sample No. 106)]
Sample No. In the production of the photoelectric conversion element of Sample No. 101, Sample No. 1 was prepared except that the hole transport layer 3A was formed by the method for producing a hole transport film described below. Sample No. 101 in the same manner as in the production of the photoelectric conversion element of No. 101. The photoelectric conversion element 10 of 106 was manufactured.
<Formation of hole transport layer 3A>
Sample No. In the same manner as in the production of the photoelectric conversion element of No. 101, Composition No. 1 for forming a hole transport layer, which was coated and dried on the photosensitive layer 13A. The following acid treatment solution No. 106 was applied (application temperature: 25 ° C.) by spin coating (1000 rpm, 30 seconds). Then, it dried at the temperature of 40 degreeC for 1 hour, and continuously at the temperature of 90 degreeC for 1 hour.
The spin coating conditions were set so that the amount of acid catalyst used was within the above range.
-Acid treatment liquid No. Preparation of 106-
Trifluoroacetic acid was dissolved in ethanol, and the acid treatment liquid No. 106 was prepared.

  The hole transport layer contained, as a hole transport agent, a reaction product in which the t-butoxycarbonyl group was eliminated from each of the specific groups of the compound S1-1 to become an amino group. The fact that the reaction product had an amino group (the mother nucleus structure was not reacted) means that the hole transfer agent was eluted with chloroform from the photoelectric conversion device before the formation of the second electrode, which was separately prepared in the same manner. It was confirmed by concentrating the substance and then analyzing it by nuclear magnetic resonance (NMR) spectrum, high efficiency liquid chromatography (HPLC), gas chromatography (GC), mass spectrometry (Mass Spectrometry: MS) and the like.

[Production of photoelectric conversion element (Sample No. 107)]
Sample No. In the same manner as in the production of the photoelectric conversion element 103, a coating film for drying the composition for forming a hole transport layer, which has been coated and dried on the photosensitive layer 13A, is provided with an ultraviolet / visible light curing conveyor system: Eye Grandage (eye graphics) (Manufactured by K.K.) and a metal halide lamp were used to irradiate ultraviolet (UV) light of 200 to 400 nm for 10 minutes (light irradiation energy: 1000 to 2000 mJ / cm ² ). After forming the hole transport layer in this manner, Sample No. Sample No. 103 in the same manner as in the production of the photoelectric conversion element of No. 103. The photoelectric conversion element of 107 was manufactured.
In the hole transport layer, as a hole transport agent, a —CO—CO— group was eliminated from each of the specific groups of the compound S1-3 to become a benzene ring group (an anthracene ring was formed together with Ar ^x1 or Ar ^x2 . ) Containing reactant. The reaction product had a benzene ring group (that was produced) in Sample No. It confirmed by the method similar to 106.

[Production of photoelectric conversion elements (Sample Nos. 108 and 109)]
Sample No. In the production of the photoelectric conversion element of Sample No. 107, sample No. 107 was used except that electron beam (EB) irradiation or plasma irradiation was performed under the following conditions instead of UV irradiation. Sample No. 107 in the same manner as in the production of the photoelectric conversion element of No. 107. The photoelectric conversion elements 10 of 108 and 109 were manufactured, respectively.
Electron beam irradiation conditions: acceleration voltage 125 KV, irradiation time 2 minutes Plasma irradiation conditions: nitrogen gas as discharge gas, irradiation time 30 seconds Sample No. The hole transport layers of 108 and 109 are sample No. It was confirmed that the same reaction product as in the hole transport layer of 107 was contained.

[Production of photoelectric conversion elements (Sample Nos. 110 and 111)]
Sample No. In the production of the photoelectric conversion element of Sample No. 106, Sample No. was changed to the compound shown in Table 1 instead of Compound S1-1. Sample No. 106 in the same manner as in the production of the photoelectric conversion element of No. 106. The photoelectric conversion elements 10 of 110 and 111 were manufactured, respectively.
Material No. The hole transport layer of the photoelectric conversion element of No. 2 contained, as a hole transport agent, a reaction product in which the butoxycarbonyl group was eliminated from each of the specific groups of the compound S1-4 or S1-10 to become an amino group. .. The fact that an amino group was generated (the mother nucleus structure was not reacted) indicates that the sample No. It confirmed by the method similar to 106.

[Production of photoelectric conversion element (Sample No. c101)]
Sample No. In the production of the photoelectric conversion element of No. 101, the following solution No. for forming hole transport layer was formed. Sample No. 1 except that c101 was used. Sample No. 101 in the same manner as in the production of the photoelectric conversion element of No. 101. The photoelectric conversion element 10 of c101 was manufactured.
<Hole Transport Layer Forming Solution No. Preparation of c101>
Spiro-OMeTAD (12 mg) as a hole transport material was dissolved in chlorobenzene (1 mL). To this chlorobenzene solution, 37.5 μL of an acetonitrile solution in which lithium-bis (trifluoromethanesulfonyl) imide (15 mg) was dissolved in acetonitrile (1 mL) and t-butylpyridine (TBP, 1 μL) were added and mixed, The solution for forming the hole transport layer No. was filtered with a polytetrafluoroethylene (PTFE) syringe filter. c101 was prepared.
The hole transport layer contained spiro-OMeTAD as a hole transport agent.

[Production of photoelectric conversion element (Sample No. c102)]
Sample No. In the production of the photoelectric conversion element of No. 101, the following solution No. for forming hole transport layer was formed. Sample No. 1 except that c102 was used. Sample No. 101 in the same manner as in the production of the photoelectric conversion element of No. 101. The photoelectric conversion element 10 of c102 was manufactured.
<Hole Transport Layer Forming Solution No. Preparation of c102>
After dissolving PTAA (12 mg) as a hole transport material in chloroform (1 mL), it was filtered with a polytetrafluoroethylene (PTFE) syringe filter to obtain a hole transport layer forming solution No. c102 was prepared.
The hole transport layer contained PTAA as a hole transport material.

[Production of photoelectric conversion elements (Sample Nos. C103 to c105)]
Sample No. Sample No. 101 except that the compound S1-1 was changed to the compound shown in Table 1 in the production of the photoelectric conversion element of No. 101. Sample No. 101 in the same manner as in the production of the photoelectric conversion element of No. 101. The photoelectric conversion elements 10 of c103 to c105 were manufactured.
Each hole transport layer contained the unreacted material of each of the compounds c1 to c3 as a hole transport agent.

[Production of photoelectric conversion element (Sample Nos. C106 to c112)]
Sample No. In the production of the photoelectric conversion element of No. 107, except that the compound S1-3 was changed to the compound shown in Table 1 (for the sample Nos. C106 and c107, the hole transport layer forming solutions No. c101 and c102 were used). , Sample no. Sample No. 107 in the same manner as in the production of the photoelectric conversion element of No. 107. Each of the photoelectric conversion elements 10 of c106 to c112 was manufactured.
Sample No. Each of the hole-transporting layers of c106 and c107 contained spiro-OMeTAD or PTAA (both unreacted substances) as a hole-transporting agent. In addition, the sample No. Each of the hole-transporting layers of c108, c109, and c112 contained unreacted substances of each of the compounds c1, c2, and c5 as a hole-transporting agent. On the other hand, sample No. The hole transport layers of c110 and c111 are reaction products (pentacene compound or anthranil compound) in which a —CO—CO— group is eliminated from a specific group of the compounds c3 and c4 as a hole transport agent, respectively. Compound having a group). The confirmation is based on the sample No. The same procedure as 107 was performed.

[Evaluation of variation in moisture resistance and durability]
As described below, the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after storage in a moisture-resistant environment were measured to evaluate the variation in the amount of decrease in the photoelectric conversion efficiency. The results are shown in Table 1.
<Measurement of initial photoelectric conversion efficiency>
As described above, each sample No. 6 photoelectric conversion elements were manufactured.
Each sample No. A battery characteristic test was performed for each of the six samples of the photoelectric conversion element in ^{Example 1} to measure the initial photoelectric conversion efficiency (η ^INI /%).
The battery characteristic test was performed by using a solar simulator “WXS-85H” (manufactured by WACOM) to irradiate simulated sunlight of 1000 W / m ² from a xenon lamp that passed an AM1.5G filter. The current-voltage characteristics were measured using an IV tester to obtain the initial photoelectric conversion efficiency.
Photoelectric conversion element No. 101 to 111 showed a sufficient initial photoelectric conversion efficiency (η ^INI /%).

<Measurement of photoelectric conversion efficiency after storage and evaluation of variation in humidity resistance and durability>
Each sample No. After storing each of the 6 photoelectric conversion element samples of 4 in a thermo-hygrostat at a temperature of 40 ° C. and a humidity of 80% RH for 48 hours, a battery characteristic test is performed and stored in the same manner as in <Measurement of initial photoelectric conversion efficiency>. The subsequent photoelectric conversion efficiency (η ^AFT /%) was measured.
Then, each sample No. The reduction rate of the photoelectric conversion efficiency was calculated according to the following formula (I) for all the photoelectric conversion elements of the 6 samples. In addition, from the decrease rate of the photoelectric conversion efficiency of the obtained 6 samples, each sample No. The average reduction rate of the photoelectric conversion element was calculated.
The photoelectric conversion element No. Nos. 101 to 111 maintained the initial photoelectric conversion efficiency (η ^INI /%) and showed sufficient photoelectric conversion efficiency (η ^AFT /%) after storage.

Reduction rate (%) = 100− [100 × (η ^AFT ) / (η ^INI )] ... (I)

Each sample No. Regarding the photoelectric conversion element of No. 3, the relative reduction rate of each of the photoelectric conversion elements of the six specimens was calculated, where the average reduction rate of the photoelectric conversion efficiency thus obtained was 1. At this time, the range including the absolute value of the largest difference between the average reduction rate and each relative reduction rate was classified according to the following evaluation criteria, and the moisture resistance durability variation was evaluated. Here, the largest difference means that the absolute value of the value obtained by subtracting 1 from the value obtained by dividing each of the reduction rates of the photoelectric conversion elements of the six samples by the average reduction rate is the largest.
In this test, the evaluation level "E" or higher is the passing level.
− Evaluation criteria for variation in moisture resistance and durability −
A: 0 or more and 0.15 or less B: 0.15 or more and 0.18 or less C: 0.18 or more and 0.22 or less D: 0.22 or more and 0.26 or less E: 0.26 Over, 0.29 or less F: over 0.29, 0.32 or less G: over 0.32

The following can be seen from the results in Table 1.
In the photoelectric conversion device having no hole transport layer containing the hole transport agent comprising the compound defined in the present invention, the hole transport material in the composition for forming a hole transport layer has sufficient solubility in a solvent. Even if it shows, it is understood that there is a large variation in humidity resistance and durability. Photoelectric conversion element No. The hole-transporting layers of c101, c102, c106 and c107 contain a normal hole-transporting agent. Photoelectric conversion element No. The hole-transporting layers c103, c104, c108 and c109 contain a hole-transporting agent having no specific group defined in the present invention. Photoelectric conversion element No. Each of the hole-transporting layers of c105 and c110 to c112 contains a hole-transporting agent which does not have the mother nucleus structure represented by the formula (S1), even if it has the specific group defined in the present invention. To do. These hole-transporting materials show no improvement in moisture resistance and durability regardless of whether UV irradiation is performed (Sample Nos. C101 to c105 and c106 to c112).
On the other hand, it can be seen that the photoelectric conversion device including the hole transport layer containing the hole transport agent composed of the compound defined in the present invention can effectively suppress the variation in moisture resistance and durability. The group represented by the formula 1-a defined in the present invention, when introduced into the mother structure of the compound represented by the formula (S1) defined in the present invention, comprises a squarylium mother structure or a triarylamine compound. It is more effective in suppressing the variation in moisture resistance and durability than being introduced into the mother nucleus structure (Sample Nos. 101, 104 and 105). This point is the same for the reaction products of the compounds (Sample Nos. 106, 110 and 111). In particular, a photoelectric conversion device provided with a hole transport layer containing a reactant obtained by reacting a specific group represented by Formula 1-a or Formula 1-c as a hole transport agent has a smaller variation in moisture resistance and durability. Is shown.

Example 2
In this example, the perovskite compound was changed, and the moisture resistance durability variation of the photoelectric conversion element was evaluated.
[Production of photoelectric conversion element (Sample Nos. 201 to 207)]
Sample No. 1 in Example 1 101-104, 106, 107 and 110, except that the photosensitive layer was formed as follows in the production of photoelectric conversion elements. Sample Nos. 101 to 104, 106, 107, and 110, in the same manner as in the production of photoelectric conversion elements. 201-207 photoelectric conversion element 10A was manufactured, respectively.
<Preparation of light absorber solution B>
39 mg of cesium iodide, 516 mg of formamidine hydroiodide, 67 mg of CH ₃ NH ₃ Br, and 1.73 g of lead iodide were mixed with DMF and DMSO (dimethyl sulfoxide) in a mixed solvent (DMF / It was dissolved in DMSO = 4/1 (volume ratio). The obtained liquid was filtered with a polytetrafluoroethylene (PTFE) syringe filter to prepare a 40% by mass light absorber solution B.
<Formation of photosensitive layer 13A>
The prepared light absorber solution B was applied (coating temperature: 25 ° C.) on the porous layer 12 formed on the conductive support 11 by the spin coating method (5000 rpm for 50 seconds). In addition, chlorobenzene (500 μL) was sprayed on the surface of the coating layer with a pipettor during coating. Then, the applied light absorber solution B is dried at 100 ° C. for 60 minutes by a hot plate to obtain a perovskite compound of Cs _0.04 FA _0.8 (CH ₃ NH ₃ ) _0.16 PbI _2.84 Br _0.16 . A photosensitive layer 13A (having a thickness of 200 nm (excluding the thickness of the porous layer 12 of 250 nm)) was provided.

[Production of photoelectric conversion element (Sample No. c201)]
Sample No. In the production of the photoelectric conversion element of No. 201, sample No. 1 in Example 1 was used. Solution No. for forming hole transport layer prepared in c101. Sample No. 1 except that c101 was used. Sample No. 201 in the same manner as in the production of the photoelectric conversion element of No. 201. The photoelectric conversion element 10 of c201 was manufactured.

<Evaluation of variation in moisture resistance and durability>
For each manufactured photoelectric conversion element, the variation in humidity resistance and durability was evaluated in the same manner as in Example 1. The results are shown in Table 2.

  From the results of Table 2, even if the type of the perovskite compound is changed with respect to the photoelectric conversion element of Example 1, when the compound defined in the present invention is used as the hole transfer agent, excellent moisture resistance is obtained as in Example 1. It can be seen that there is a variation in durability.

Example 3
In this example, the photoelectric conversion element 10E having the layer structure shown in FIG. 5 was manufactured, and the variation in humidity resistance and durability of the photoelectric conversion element was evaluated.
[Production of photoelectric conversion element (Sample No. 301)]
<Preparation of first electrode>
-Formation of hole transport layer 16-
On the ITO substrate (conductive substrate 11 and transparent electrode 11b having a film thickness of 300 nm), the sample No. Composition No. 101 for forming a hole transport layer prepared in No. 101. 101 was applied by a spin coating method (3000 rpm for 30 seconds) (application temperature: 25 ° C.) and dried (50 ° C. for 10 minutes). Then, the sample No. Acid treatment solution No. 106 106 was applied (application temperature: 25 ° C.) by spin coating (1000 rpm, 30 seconds). After that, the hole transport layer 16 was formed by drying at a temperature of 40 ° C. for 1 hour and subsequently at a temperature of 90 ° C. for 1 hour in this order.

-Formation of photosensitive layer 13C-
Sample No. in Example 2 The light absorbent solution B prepared in 201 was applied (application temperature: 25 ° C.) on the hole transport layer 16 by spin coating (5000 rpm, 50 seconds). The applied light absorber solution B was dried on a hot plate at 100 ° C. for 60 minutes to be composed of a perovskite compound of Cs _0.04 FA _0.8 (CH ₃ NH ₃ ) _0.16 PbI _2.84 Br _0.16. A photosensitive layer 13C (film thickness 200 nm) was provided.

  Thus, the first electrode 1E was produced.

<Formation of electron transport layer 4>
− Preparation of electron transport material solution −
An electron-transporting material solution was prepared by dissolving [6,6] -phenyl-C61-butyric acid acid methyl ester (PC ₆₁ BM, 20 mg / mL) in chlorobenzene (1 mL).
-Formation of electron transport layer 4-
Then, the prepared electron transport layer solution was applied onto the photosensitive layer 13C by a spin coating method (application temperature: 25 ° C.). The applied electron transport layer solution was dried (120 ° C. for 30 minutes) to form a solid electron transport layer 4 (film thickness 100 nm).
<Production of second electrode 2>
Aluminum was vapor-deposited on the electron transport layer 4 by a vapor deposition method to form the second electrode 2 (film thickness 100 nm).
Thus, the photoelectric conversion element 10E (Sample No. 301) was manufactured.

[Production of photoelectric conversion element (Sample No. c301)]
Sample No. In the production of the photoelectric conversion element No. 301, the sample No. 301 in Example 1 was used. Solution No. for forming hole transport layer prepared in c101. Sample No. 1 except that c101 was used. Sample No. 301 in the same manner as in the production of the photoelectric conversion element of No. 301. The photoelectric conversion element 10 of c301 was manufactured.

<Evaluation of variation in moisture resistance and durability>
For each manufactured photoelectric conversion element, the variation in humidity resistance and durability was evaluated in the same manner as in Example 1. The results are shown in Table 3.

  From the results shown in Table 3, even if the type of the perovskite compound and the layer structure of the photoelectric conversion element were changed from those of the photoelectric conversion element of Example 1, when the compound specified in the present invention was used as the hole transfer agent, It can be seen that excellent moisture resistance and durability are exhibited as in No. 1.

From the above results, the following can be understood. That is, in the photoelectric conversion element and the solar cell of the present invention, even if the perovskite compound is used as the light absorber, the variation in moisture resistance and durability among the elements is small.
Further, the hole transport agent and the composition for forming a hole transport layer of the present invention are used as a material for forming a hole transport layer of a photoelectric conversion element having a photosensitive layer containing a perovskite compound as a light absorber. As a result, it is possible to suppress variation in the amount of decrease in photoelectric conversion efficiency between elements. Further, the method for producing a hole transport film of the present invention is applied as a method for forming a hole transport layer of a photoelectric conversion element, so that even if a plurality of elements are produced by a normal solution coating method, In the above, it is possible to manufacture the hole transport film capable of suppressing the variation in the decrease amount of the photoelectric conversion efficiency. By using this hole transport film as a hole transport layer of a photoelectric conversion element, it is possible to suppress variations in the amount of decrease in photoelectric conversion efficiency between elements.

1A to 1E electrode (first electrode)
11 Conductive Support 11a Support 11b Transparent Electrode 12 Porous Layer 13A-13C Photosensitive Layer 14 Blocking Layer 2 Second Electrodes 3A, 3B, 16 Hole Transport Layer 4, 15 Electron Transport Layer 6 External Circuit (Lead)
10A-10E Photoelectric conversion element 100A-100E System M using a solar cell Electric motor

Claims (12)

A hole transport material comprising a compound having a group represented by any one of the following formulas 1-a to 1-c.

In the formula, R ¹ and R ² represent a substituent.
R represents a hydrogen atom or a substituent.
R ³ and R ⁴ represent a hydrogen atom, a substituent or a linking site with the compound.
X ¹ represents —N (R ^a ) — or —O—, and R ^a represents a substituent or a hydrogen atom.
* Indicates a linking site with the compound.
However, the compound having a group represented by Formula 1-b or Formula 1-c has a mother nucleus structure represented by Formula (S1) below.

In formula (S1), Ar ^x1 and Ar ^x2 represent an aryl group or a heteroaryl group.
Ar ¹ and Ar ² represent an arylene group or a heteroarylene group.
R ^1S represents a substituent.
n1 and n2 are integers of 0 or more. However, n1 + n2 ≧ 1.
n3 is an integer of 3 or more.   The hole transport material according to claim 1, wherein the compound having a group represented by Formula 1-a has a mother nucleus structure represented by Formula (S1). The hole transport according to claim 1 or 2, wherein at least one of Ar ^x1 and Ar ^x2 in the formula (S1) has a group represented by any one of the formulas 1-a to 1-c. Agent.   The hole transport material according to any one of claims 1 to 3, wherein the compound has a group represented by the formula 1-a or the formula 1-c.   A composition for forming a hole-transporting layer, which comprises the hole-transporting agent according to claim 1.   A method for forming a hole transport film, which comprises applying the composition for forming a hole transport layer according to claim 5.   When the compound contained in the hole transport layer forming composition has a group represented by formula 1-a, at least one of acid treatment and base treatment after coating the hole transport layer forming composition. The method for forming a hole transport film according to claim 6, wherein the post-treatment is performed.   When the compound contained in the composition for forming a hole transport layer has a group represented by the formula 1-c, active energy ray irradiation treatment is performed after applying the composition for forming a hole transport layer. Item 7. A method for forming a hole transport film according to Item 6. An electrode having a photosensitive layer containing a light absorber on a conductive support, a counter electrode, and a hole transport layer between the conductive support and the counter electrode, a photoelectric conversion element,
A photoelectric conversion element, wherein the hole transport layer contains the hole transport material according to any one of claims 1 to 4.   The photoelectric conversion element according to claim 9, wherein the hole transport layer is formed of the hole transport film formed by the method of manufacturing the hole transport film according to any one of claims 6 to 8.   The photoelectric conversion element according to claim 9, wherein the light absorber contains a compound having a perovskite type crystal structure.   A solar cell using the photoelectric conversion element according to any one of claims 9 to 11.

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