WO2020255609A1

WO2020255609A1 - Photoelectric conversion element

Info

Publication number: WO2020255609A1
Application number: PCT/JP2020/019867
Authority: WO
Inventors: 崇倉田; 良樹今西; 紅里山上; 光田中; 一剛萩谷
Original assignee: 東洋紡株式会社
Priority date: 2019-06-17
Filing date: 2020-05-20
Publication date: 2020-12-24
Also published as: JPWO2020255609A1

Abstract

Provided is a photoelectric conversion element having a high open circuit voltage (Voc) and a high short circuit current density (Jsc). Furthermore, an organic thin film solar cell including said photoelectric conversion element is provided. The photoelectric conversion element has a structure in which a cathode, an active layer, and an anode are arranged in this order, wherein the active layer contains a polymer compound having a benzobisthiazole structure unit represented by Formula (1), an aromatic compound represented by Formula (2), and an aromatic compound represented by Formula (3).

Description

Photoelectric conversion element

The present invention has a photoelectric conversion element having a structure in which a cathode, an active layer, and an anode are arranged in this order, and the active layer has a polymer compound having a specific benzobisthiazole structural unit and a specific structure. The present invention relates to a photoelectric conversion element containing an aromatic compound.

Organic semiconductor materials are one of the most important materials in the field of organic electronics, and can be classified into electron-donating p-type organic semiconductor compounds and electron-accepting n-type organic semiconductor compounds. Various semiconductor devices can be manufactured by appropriately combining such p-type organic semiconductor compounds and n-type organic semiconductor compounds. Semiconductor devices include, for example, organic electroluminescence that emits light by the action of excitons (exciton) formed by the recombination of electrons and holes, organic thin-film transistor cells that convert light into electric power, and organic that controls current and voltage. It is used in organic electronic devices such as thin film transistors. An example of an organic semiconductor material used in an organic electronic device is disclosed in, for example, Patent Document 1. The organic semiconductor material described in Patent Document 1 contains a polymer compound having a structural unit having a specific benzobisthiazole skeleton. Further, Patent Documents 2 and 3 describe a photoelectric conversion element containing a polymer compound having a specific benzobisthiazole structural unit.

International Publication No. 2015/122321 International Publication No. 2016/125822 International Publication No. 2016/132917

By the way, among organic electronic devices, organic thin-film solar cells are useful for environmental conservation because they do not emit carbon dioxide into the atmosphere, and because they have a simple structure and are easy to manufacture, demand is increasing. Organic thin-film solar cells are desired to have high efficiency of converting sunlight energy into electric power (energy conversion efficiency PCE), and the energy conversion efficiency PCE includes short-circuit current density (Jsc), open circuit voltage (Voc), and so on. It can be calculated by the following equation based on the curve factor (FF) and the incident energy (Pin).
PCE = (Jsc x Voc x FF / Pin) x 100

In order to increase the energy conversion efficiency PCE of the photoelectric conversion element, it is conceivable to improve either the short-circuit current density (Jsc), the open circuit voltage (Voc), or the curve factor (FF), or lower the incident energy (Pin). Be done. By improving the open circuit voltage (Voc) among these, it is possible to increase the output of electric power and realize stable electric power supply. On the other hand, the short-circuit current density (Jsc) is known to correlate with the amount of energy received by the organic semiconductor compound. In order to improve the short-circuit current density (Jsc), the organic semiconductor compound is exposed to the visible region to the near infrared. It is necessary to absorb light in a wide wavelength range up to the region. Among the light that can be absorbed by the organic semiconductor compound, the wavelength of the light having the lowest energy (the longest wavelength) is the absorption edge wavelength, and the energy corresponding to this wavelength corresponds to the band gap energy. Therefore, in order for the organic semiconductor compound to absorb light in a wide wavelength range, the energy of the bandgap [HOMO level (highest occupied orbital level) and LUMO level (lowest empty orbital level) of the p-type organic semiconductor compound) Difference] needs to be narrowed.

An object of the present invention is to provide a photoelectric conversion element having a high open circuit voltage (Voc) and a short circuit current density (Jsc). Another object of the present invention is to provide an organic thin film solar cell provided with the photoelectric conversion element.

The present invention includes the following inventions.
[1] A photoelectric conversion element having a structure in which a cathode, an active layer, and an anode are arranged in this order, and the active layer has a high molecular weight having a benzobisthiazole structural unit represented by the following formula (1). A photoelectric conversion element containing a molecular compound, an aromatic compound represented by the following formula (2), and / or an aromatic compound represented by the following formula (3).

[In formula (1), whether T ¹ and T ² are independently alkoxy groups, thioalkoxy groups, or thiophene rings that may be substituted with a hydrocarbon group or an organosilyl group. , A thiazole ring optionally substituted with a hydrocarbon group or an organosilyl group, or even if substituted with a hydrocarbon group, an organosilyl group, an alkoxy group, an thioalkoxy group, a trifluoromethyl group, or a halogen atom. Represents a good phenyl group.
Further, B ¹ and B ² each independently represent a thiophene ring which may be substituted with a hydrocarbon group, a thiazole ring which may be substituted with a hydrocarbon group, or an ethynylene group. .. ]

[In formula (2), R ¹⁰¹ to R ¹¹⁶ are independently hydrogen atoms, alkyl groups, alkoxy groups, thioalkoxy groups, fluorine atoms, or alkyl. Represents a benzene ring that may be substituted with a group, alkoxy group, thioalkoxy group, or fluorine atom, or a thiophene ring that may be substituted with an alkyl group, alkoxy group, thioalkoxy group, or fluorine atom. ]

[In formula (3), R ²⁰¹ to R ²¹⁴ are independently hydrogen atoms, alkyl groups, alkoxy groups, thioalkoxy groups, fluorine atoms, or alkyl. Represents a benzene ring that may be substituted with a group, alkoxy group, thioalkoxy group, or fluorine atom, or a thiophene ring that may be substituted with an alkyl group, alkoxy group, thioalkoxy group, or fluorine atom. ]
[2] The photoelectric conversion element according to [1], wherein T ¹ and T ² are independent groups represented by any of the following formulas (t1) to (t5).

Wherein (t1) ~ formula ^{(t5), R 13, R} 14 each independently represent a hydrocarbon group having 6 to 30 carbon atoms.
R ¹⁵ and R ¹⁶ each independently represent a hydrocarbon group having 6 to 30 carbon atoms or a group represented by * -Si (R ¹⁸ ) ₃ .
Each of R ¹⁷ independently contains a hydrocarbon group having 6 to 30 carbon atoms, * -Si (R ¹⁸ ) ₃ , * -OR ¹⁹ , * -SR ²⁰ , * -CF ₃ , or a halogen atom. Represent.
n1 represents an integer of 1 to 3, n2 represents an integer of 1 or 2, n3 represents an integer of 1 to 5, and a plurality of R ^15s may be the same or different, and a plurality of R ^16s may be the same or different. , Multiple R ^17s may be the same or different.
Each of R ¹⁸ independently represents an aliphatic hydrocarbon group having 1 to 20 carbon atoms or an aromatic hydrocarbon group having 6 to 10 carbon atoms, and a plurality of R ^18s may be the same or different.
R ¹⁹ and R ²⁰ each independently represent a hydrocarbon group having 6 to 30 carbon atoms.
* Represents a bond. ]
[3] The photoelectric conversion element according to [1] or [2], wherein B ¹ and B ² are independent groups represented by any of the following formulas (b1) to (b3).

[In formulas (b1) to (b3), R ²¹ and R ²² each independently represent a hydrocarbon group having 6 to 30 carbon atoms.
n4 represents an integer of 0 to 2, n5 represents 0 or 1, and a plurality of R ^21s may be the same or different.
* Represents a bond, and * on the left represents a bond that binds to the benzene ring of the benzobisthiazole structural unit. ]
[4] The photoelectric conversion element according to any one of [1] to [3], wherein the polymer compound containing the benzobisthiazole structural unit represented by the formula (1) is a donor-acceptor type semiconductor polymer compound. ..
[5] The photoelectric conversion element according to any one of [1] to [4], which has an electron transport layer between the cathode and the active layer.
[6] The photoelectric conversion element according to any one of [1] to [5], which has a hole transport layer between the anode and the active layer.
[7] The photoelectric conversion element according to any one of [1] to [6], wherein the base material is arranged on one side of the cathode and the active layer is arranged on the other side of the cathode.
[8] The photoelectric conversion element according to any one of [1] to [6], wherein the base material is arranged on one side of the anode and the active layer is arranged on the other side of the anode.
[9] An organic thin-film solar cell including the photoelectric conversion element according to any one of [1] to [8].

The photoelectric conversion element of the present invention has a structure in which a cathode, an active layer, and an anode are arranged in this order, and the active layer is a specific polymer compound having a specific benzobisthiazole structural unit. It contains an aromatic compound having a structure. As a result, both the open circuit voltage (Voc) and the short-circuit current density (Jsc) of the photoelectric conversion element become high, so that the power output can be increased, a stable power supply can be realized, and the energy conversion efficiency PCE is improved. Is also possible. Further, according to the present invention, it is possible to provide an organic thin film solar cell provided with the above photoelectric conversion element.

FIG. 1 is a schematic view showing an embodiment of a photoelectric conversion element of the present invention. FIG. 2 is a schematic view showing another embodiment of the photoelectric conversion element of the present invention.

The present inventors have been diligently studying with the aim of increasing the energy conversion efficiency PCE of the photoelectric conversion element by improving both the open circuit voltage (Voc) and the short-circuit current density (Jsc). As a result, in the active layer, a polymer compound having a benzobisthiazole structural unit represented by the formula (1) described later, an aromatic compound represented by the formula (2) described later, and / or described later. If it contains an aromatic compound represented by the formula (3), it has a wide range of light absorption over the entire visible light region, and the HOMO level and LUMO level can be adjusted to an appropriate range. We have found that the short-circuit current density (Jsc) can be improved while improving Voc), and the energy conversion efficiency PCE of the photoelectric conversion element can be increased, and the present invention has been completed. Hereinafter, embodiments of the present invention will be described in detail. The description of the constituent elements described below is an example (representative example) of the embodiment of the present invention, and the present invention is not limited to these contents as long as the gist thereof is not exceeded.

<1. Photoelectric conversion element>
The photoelectric conversion element according to the present invention is a photoelectric conversion element having a structure in which a cathode, an active layer, and an anode are arranged in this order, and the active layer is a benzobis represented by the following formula (1). Polymer compound having a thiazole structural unit [hereinafter, may be referred to as polymer compound (1). ] And an aromatic compound represented by the following formula (2) [hereinafter, may be referred to as an aromatic compound (2). ], And / or an aromatic compound represented by the following formula (3) [hereinafter, may be referred to as an aromatic compound (3). ] Is a photoelectric conversion element containing.

[In formula (3), R ²⁰¹ to R ²¹⁴ are independently hydrogen atoms, alkyl groups, alkoxy groups, thioalkoxy groups, fluorine atoms, or alkyl. Represents a benzene ring that may be substituted with a group, alkoxy group, thioalkoxy group, or fluorine atom, or a thiophene ring that may be substituted with an alkyl group, alkoxy group, thioalkoxy group, or fluorine atom. ]

The photoelectric conversion element according to the present invention has a structure in which a cathode, an active layer, and an anode are arranged in this order, and one embodiment of the present invention will be specifically described with reference to the drawings. The photoelectric conversion element according to the present invention is not limited to the configuration shown in the drawings.

FIG. 1 is a schematic view showing an embodiment of the photoelectric conversion element of the present invention, and shows a configuration example of a photoelectric conversion element used in a general organic thin film solar cell. The photoelectric conversion element (I) shown in FIG. 1 has a structure in which a cathode (electrode) (C), an active layer (X), and an anode (electrode) (A) are arranged in this order. In the embodiment shown in FIG. 1, the base material (B) is arranged on one side of the cathode (C), and the active layer (X) is arranged on the other side of the cathode (C). The photoelectric conversion element (I) shown in FIG. 1 further has an electron transport layer (E) and a hole transport layer (H) as a buffer layer. That is, the photoelectric conversion element (I) shown in FIG. 1 has an electron transport layer (E) between the cathode (C) and the active layer (X), and has an anode (A) and an active layer (X). It has a hole transport layer (H) between the two. Therefore, in the embodiment shown in FIG. 1, the base material (B), the cathode (C), the electron transport layer (E) as the buffer layer, the active layer (X), and the hole transport layer (H) as the buffer layer. ) And the anode (A) are arranged in this order.

FIG. 2 is a schematic view showing another embodiment of the photoelectric conversion element of the present invention, and shows a configuration example of the photoelectric conversion element used in a general organic thin film solar cell. The photoelectric conversion element (II) shown in FIG. 2 has a structure in which a cathode (electrode) (C), an active layer (X), and an anode (electrode) (A) are arranged in this order. In the embodiment shown in FIG. 2, the base material (B) is arranged on one side of the anode (A), and the active layer (X) is arranged on the other side of the anode (A). The photoelectric conversion element (II) shown in FIG. 2 further has an electron transport layer (E) and a hole transport layer (H) as a buffer layer. That is, the photoelectric conversion element (II) shown in FIG. 2 has an electron transport layer (E) between the cathode (C) and the active layer (X), and has an anode (A) and an active layer (X). It has a hole transport layer (H) between the two. Therefore, in the embodiment shown in FIG. 2, the base material (B), the anode (A), the hole transport layer (H) as the buffer layer, the active layer (X), and the electron transport layer (E) as the buffer layer. ) And the cathode (C) are arranged in this order. Each of these parts will be described below.

<1.1 Active layer (X)>
The active layer (X) refers to a layer on which photoelectric conversion is performed. When the photoelectric conversion element receives light, the light is absorbed by the active layer (X), and the interface between the p-type organic semiconductor compound and the n-type organic semiconductor compound. Electricity is generated at, and the generated electricity is taken out from the cathode (C) and the anode (A).

The active layer (X) is a polymer compound [polymer compound (1)] having a benzobisthiazole structural unit represented by the above formula (1) and an aromatic compound represented by the above formula (2). It contains [aromatic compound (2)] and / or an aromatic compound represented by the above formula (3) [aromatic compound (3)]. The polymer compound (1) is a p-type organic semiconductor compound, and the aromatic compound (2) and the aromatic compound (3) are n-type organic semiconductor compounds.

The active layer (X) may contain one kind of polymer compound [polymer compound (1)] having a benzobisthiazole structural unit represented by the above formula (1), or may contain two or more kinds. May be good. Further, the active layer (X) may further contain an organic semiconductor compound having no benzobisthiazole structural unit represented by the above formula (1) as the p-type organic semiconductor compound. Hereinafter, the organic semiconductor compound having no benzobisthiazole structural unit represented by the above formula (1) may be hereinafter referred to as an organic semiconductor compound (11).

The active layer (X) may contain either the aromatic compound (2) or the aromatic compound (3), or the aromatic compound (2) and the aromatic compound (3). It may contain both of the above, and it is preferable to contain either the aromatic compound (2) or the aromatic compound (3). Further, the active layer (X) may further contain an n-type organic semiconductor compound other than the aromatic compound (2) or the aromatic compound (3).

The film thickness of the active layer (X) is not particularly limited, but is preferably 70 nm or more and 1000 nm or less, for example. By setting the film thickness of the active layer (X) to 70 nm or more, improvement in the energy conversion efficiency PCE of the photoelectric conversion element can be expected. Further, by setting the film thickness of the active layer (X) to 70 nm or more, a through-short circuit in the film can be prevented. The film thickness of the active layer (X) is preferably 70 nm or more, more preferably 90 nm or more, and further preferably 100 nm or more. On the other hand, in general, the thicker the active layer (X), the greater the distance that the electric charge generated in the active layer (X) travels to the electrode, which hinders the transport of the electric charge to the electrode. .. When the active layer (X) is thick as described above, the region capable of absorbing light increases, but it is difficult to transport the electric charge generated by the light absorption, so that the energy conversion efficiency PCE is lowered. Therefore, by setting the film thickness of the active layer (X) to 1000 nm or less, the distance between the electrodes is not too large, the charge diffusion is good, and the internal resistance of the active layer (X) is also reduced. The film thickness of the active layer (X) is preferably 1000 nm or less, more preferably 750 nm or less, and further preferably 500 nm or less. Further, by setting the film thickness of the active layer (X) to 70 nm or more and 1000 nm or less, the reproducibility in the process of producing the active layer (X) is further improved. Further, it is preferable that the film thickness of the active layer (X) is 70 nm or more and 500 nm or less because the open circuit voltage (Voc) can be secured in addition to the improvement of the energy conversion efficiency PCE.

[1.1.1 Layer structure of active layer]
The layer structure of the active layer (X) includes a thin film laminated type in which a p-type organic semiconductor compound and an n-type organic semiconductor compound are laminated, or a layer in which a p-type organic semiconductor compound and an n-type organic semiconductor compound are mixed. Bulk heterojunction type and the like can be mentioned. Of these, a bulk heterojunction type active layer is preferable because the energy conversion efficiency PCE can be further improved.

The bulk heterojunction type active layer has a layer in which a p-type organic semiconductor compound and an n-type organic semiconductor compound are mixed (hereinafter, may be referred to as i-layer). The i-layer has a structure in which a p-type organic semiconductor compound and an n-type organic semiconductor compound are phase-separated, carrier separation occurs at the phase interface, and the generated carriers (holes and electrons) are transported to the electrode.

When the mass of the p-type organic semiconductor compound contained in the i-layer is 100%, the content of the polymer compound (1) is preferably 50% by mass or more, more preferably 70% by mass or more, and further preferably 90% by mass. % Or more, most preferably 100% by mass. Since the polymer compound (1) has properties suitable as a p-type organic semiconductor compound, it is most preferable to contain only the polymer compound (1) as the p-type organic semiconductor compound contained in the i-layer.

The mass ratio of the p-type organic semiconductor compound to the n-type organic semiconductor compound in the i-layer (p-type organic semiconductor compound / n-type organic semiconductor compound) improves the energy conversion efficiency PCE by obtaining a good phase-separated structure. From the viewpoint of the above, 0.2 or more is preferable, 0.5 or more is more preferable, 1 or more is more preferable, 5 or less is preferable, 4 or less is more preferable, 3 or less is more preferable, and 2 or less is particularly preferable. is there.

The i-layer can be formed by any method including a coating method and a vapor deposition method (for example, a co-evaporation method), but it is preferable to use the coating method because the i-layer can be formed more easily. The polymer compound (1) is preferable because it has good solubility in a solvent and is excellent in coating film-forming property. When the i-layer is formed by the coating method, a coating liquid containing a p-type organic semiconductor compound and an n-type organic semiconductor compound may be prepared and the coating liquid may be applied. The coating liquid containing the p-type organic semiconductor compound and the n-type organic semiconductor compound may be prepared by preparing a solution containing the p-type organic semiconductor compound and a solution containing the n-type organic semiconductor compound, and then mixing them. It may be prepared by dissolving a p-type organic semiconductor compound and an n-type organic semiconductor compound in a solvent.

The total concentration of the p-type organic semiconductor compound and the n-type organic semiconductor compound in the coating liquid is not particularly limited, but is 1.0 with respect to the entire coating liquid from the viewpoint of forming the active layer (X) having a sufficient thickness. It is preferably 4.0% by mass or more, and preferably 4.0% by mass or less with respect to the entire coating liquid from the viewpoint of sufficiently dissolving the semiconductor compound.

Any method can be used as the coating method, for example, spin coating method, inkjet method, doctor blade method, drop casting method, reverse roll coating method, gravure coating method, kiss coating method, roll brushing method, spray coating method, etc. Examples include the air knife coating method, the wire barber coating method, the pipe doctor method, the impregnation / coating method, the curtain coating method, and the flexo coating method. After applying the coating liquid, a drying treatment such as heating may be performed.

The solvent of the coating liquid is not particularly limited as long as it can uniformly dissolve the p-type organic semiconductor compound and the n-type organic semiconductor compound, and is, for example, an aliphatic such as hexane, heptane, octane, isooctane, nonane, or decane. Hydrocarbons; aromatic hydrocarbons such as toluene, xylene, mesityrene, indan, tetraline, cyclohexylbenzene, chlorobenzene, or orthodichlorobenzene; fats such as cyclopentane, cyclohexane, methylcyclohexane, cycloheptane, cyclooctane, or decalin Cyclic hydrocarbons; lower alcohols such as methanol, ethanol, propanol, or anisole; aliphatic ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone (MIBK), cyclopentanone, or cyclohexanone; acetophenone, or propiophenone Aromatic ketones such as; esters such as ethyl acetate, isopropyl acetate, butyl acetate, or methyl lactate; halogen hydrocarbons such as chloroform, methylene chloride, dichloroethane, trichloroethane, or trichloroethylene; ethyl ether, tetrahydrofuran, cyclopentylmethyl ether , Dibutyl ethers, diphenyl ethers, or ethers such as dioxane; or amides such as dimethylformamide, N-methylpyrrolidone (NMP), 1,3-dimethyl-2-imidazolidinone (DMI), or dimethylacetamide; etc. These may be used alone or in combination of two or more. Of these, aromatic hydrocarbons such as toluene, xylene, mesitylene, tetraline, cyclohexylbenzene, chlorobenzene, or orthodichlorobenzene; alicyclics such as cyclopentane, cyclohexane, methylcyclohexane, cycloheptane, cyclooctane, or decalin. Formula hydrocarbons; aliphatic ketones such as acetone, methyl ethyl ketone, cyclopentane, or cyclohexanone; or ethers such as ethyl ether, tetrahydrofuran, or dioxane.

When the bulk heterojunction type active layer is formed by the coating method, an additive may be added to the coating liquid containing the p-type organic semiconductor compound and the n-type organic semiconductor compound. The phase-separated structure of the p-type organic semiconductor compound and the n-type organic semiconductor compound in the bulk heterojunction type active layer is used in the light absorption process, exciton diffusion process, exciton dissociation (carrier separation) process, carrier transport process, etc. Affects Therefore, it is considered that good energy conversion efficiency PCE can be realized by optimizing the phase separation structure of the p-type organic semiconductor compound and the n-type organic semiconductor compound in the bulk heterojunction type active layer. Therefore, by incorporating an additive having a high affinity with the p-type organic semiconductor compound or the n-type organic semiconductor compound in the coating liquid, an active layer having a preferable phase separation structure can be obtained, and the energy conversion efficiency PCE can be improved. Conceivable.

The additive is preferably a solid or a liquid having a high boiling point in that it is not easily lost from the active layer (X).

Specifically, when the additive is a solid, the melting point (1 atm) of the additive is usually preferably 35 ° C. or higher, more preferably 50 ° C. or higher, still more preferably 80 ° C. or higher, and particularly preferably 150 ° C. or higher. Most preferably, it is 200 ° C. or higher. The upper limit of the melting point is, for example, preferably 400 ° C. or lower, more preferably 350 ° C. or lower, still more preferably 300 ° C. or lower. Examples of the solid additive include aliphatic hydrocarbons having 10 or more and 20 or less carbon atoms, aromatic compounds having 10 or more and 20 or less carbon atoms which may have a substituent, and the like, and have a substituent. Aromatic compounds having 10 or more and 20 or less carbon atoms which may be used are preferable. Specific examples of the aromatic compound include naphthalene compounds, and a compound in which a substituent of 1 to 8 is bonded to naphthalene is particularly preferable. Substituents bonded to naphthalene include halogen atom, hydroxyl group, cyano group, amino group, amide group, carbonyloxy group, carboxyl group, carbonyl group, oxycarbonyl group, silyl group, alkenyl group, alkynyl group and alkoxy group. , Aryloxy group, alkylthio group, arylthio group or aromatic group.

When the additive is a liquid, the boiling point (1 atm) of the additive is preferably 80 ° C. or higher, more preferably 100 ° C. or higher, and further preferably 150 ° C. or higher. The upper limit of the boiling point is, for example, preferably 300 ° C. or lower, more preferably 250 ° C. or lower, still more preferably 200 ° C. or lower. Examples of the liquid additive include aliphatic hydrocarbons having 8 to 9 carbon atoms and aromatic compounds having 8 to 9 carbon atoms which may have a substituent. Specific examples of the aliphatic hydrocarbons include dihalogen hydrocarbon compounds, and compounds in which a substituent of 1 to 8 is bonded to octane are particularly preferable. Substituents bonded to octane include halogen atoms, hydroxyl groups, thiol groups, alkoxy groups, thioalkoxy groups, cyano groups, amino groups, amide groups, carbonyloxy groups, carboxyl groups, carbonyl groups, or aromatic groups. Can be mentioned. Specific examples of the aromatic compound include benzene, which includes a halogen atom, a hydroxyl group, a thiol group, an alkoxy group, a thioalkoxy group, a cyano group, an amino group, an amide group, a carbonyloxy group, a carboxyl group, or a carbonyl group. A benzene compound having a substituent such as, or a benzene compound in which 4 or more and 6 or less halogen atoms are bonded is preferable. More specifically, anisole; a benzene compound substituted with one or more alkoxy groups such as 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,5-dimethylanisole and an alkyl group; thioanisole; Ethylphenyl sulfide; 4- (methylthio) toluene and its positional isomers; 2-methoxythioanisole and its positional isomers; methoxynaphthalene positional isomers such as 1-methoxynaphthalene and 2-methoxynaphthalene; 1,4-dimethoxynaphthalene , 1,6-Dimethoxynaphthalene, 1,7-dimethoxynaphthalene, 2,3-dimethoxynaphthalene, 2,6-dimethoxynaphthalene, dimethoxynaphthalene positional isomers such as 2,7-dimethoxynaphthalene; and the like.

The additive is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and 10% by mass or more, based on the total mass of the coating liquid containing the p-type organic semiconductor compound and the n-type organic semiconductor compound. It is preferably 5% by mass or less, more preferably 5% by mass or less. When the amount of the additive is in this range, a preferable phase separation structure can be obtained.

[1.1.2 p-type organic semiconductor compound]
The active layer (X) contains a polymer compound (1) as a p-type organic semiconductor compound. The polymer compound (1) is a p-type organic semiconductor compound, and may be referred to as a benzobisthiazole structural unit represented by the following formula (1) (hereinafter, referred to as a “structural unit represented by the formula (1)”. .).

Since the polymer compound (1) has a benzobisthiazole structural unit represented by the above formula (1), the band gap can be narrowed while deepening the HOMO level, and the energy conversion efficiency PCE can be improved. It is advantageous. The polymer compound (1) is preferably a donor-acceptor type semiconductor polymer compound obtained by copolymerizing a benzobisthiazole structural unit represented by the above formula (1) with a copolymerization component (12) described later. The donor-acceptor type semiconductor polymer compound means a polymer compound in which donor units and acceptor units are alternately arranged. A donor unit means an electron-donating structural unit, and an acceptor-like unit means an electron-accepting structural unit. The donor-acceptor type semiconductor polymer compound is preferably a polymer compound in which the structural unit represented by the formula (1) and the copolymerization component (12) described later are alternately arranged. With such a structure, it can be suitably used as a p-type organic semiconductor compound.

In the benzobisthiazole structural unit represented by the above formula (1), T ¹ and T ² are independently an alkoxy group, a thioalkoxy group, a thiophene ring, or a thiazole ring, respectively. Or represents a phenyl group. The thiophene ring may be substituted with a hydrocarbon group or an organosilyl group, the thiazole ring may be substituted with a hydrocarbon group or an organosilyl group, and the phenyl group may be a hydrocarbon group, an organosilyl group, It may be substituted with an alkoxy group, a thioalkoxy group, a trifluoromethyl group, or a halogen atom. As the halogen atom, any of fluorine, chlorine, bromine and iodine can be used.

The organosilyl group means a monovalent group in which one or more hydrocarbon groups are substituted for Si atoms, and the number of hydrocarbon groups substituted for Si atoms is preferably two or more, preferably three. More preferred.

The T ¹ and T ² may be the same or different from each other, but are preferably the same from the viewpoint of easy production.

The T ¹ and T ² are preferably groups represented by any of the following formulas (t1) to (t5) independently. That is, the alkoxy group represented by T ¹ and T ² is preferably the group represented by the following formula (t 1), and the thioalkoxy group represented by T ¹ and T ² is represented by the following formula (t 2). preferably a group represented, preferably a group represented by the following formula (t3) as thiophene ring represented by T ^1, T ^2, the following formula is a thiazole ring represented by T ^1, T ² The group represented by (t4) is preferable, and the phenyl group represented by T ¹ and T ² is preferably the group represented by the following formula (t 5). When the above T ¹ and T ² are groups represented by any of the following formulas (t1) to (t5), they can absorb light having a short wavelength and have high flatness, which is efficient. Since π-π stacking is formed in, the energy conversion efficiency PCE can be further improved.

The formula (t1) in to Formula ^{(t5), R 13, R} 14 each independently represent a hydrocarbon group having 6 to 30 carbon atoms. R ¹⁵ and R ¹⁶ each independently represent a hydrocarbon group having 6 to 30 carbon atoms or a group represented by * -Si (R ¹⁸ ) ₃ . Each of R ¹⁷ independently contains a hydrocarbon group having 6 to 30 carbon atoms, * -Si (R ¹⁸ ) ₃ , * -OR ¹⁹ , * -SR ²⁰ , * -CF ₃ , or a halogen atom. Represent. n1 represents an integer of 1 to 3, n2 represents an integer of 1 or 2, n3 represents an integer of 1 to 5, and a plurality of R ^15s may be the same or different, and a plurality of R ^16s may be the same or different. , Multiple R ^17s may be the same or different. Each of R ¹⁸ independently represents an aliphatic hydrocarbon group having 1 to 20 carbon atoms or an aromatic hydrocarbon group having 6 to 10 carbon atoms, and a plurality of R ^18s may be the same or different. R ¹⁹ and R ²⁰ each independently represent a hydrocarbon group having 6 to 30 carbon atoms. * Represents a bond.

In the above formulas (t1) to (t5), as the hydrocarbon group having 6 to 30 carbon atoms represented by R ¹³ to R ¹⁷ , a branched hydrocarbon group is preferable, and a branched chain saturated hydrocarbon is more preferable. It is a hydrogen group. Since the hydrocarbon groups represented by R ¹³ to R ¹⁷ have branches, the solubility in an organic solvent can be increased, and the polymer compound (1) can obtain appropriate crystallinity.

The larger the number of carbon atoms of the hydrocarbon groups represented by R ¹³ to R ¹⁷ , the better the solubility in an organic solvent, but if it becomes too large, the reactivity in the coupling reaction described later will decrease. It becomes difficult to synthesize the polymer compound (1). Therefore, the number of carbon atoms of the hydrocarbon group represented by R ¹³ to R ¹⁷ is preferably 6 to 30, more preferably 8 to 25, still more preferably 8 to 20, and particularly preferably 8 to 16.

Specific examples of the hydrocarbon group represented by R ¹³ to R ¹⁷ include an alkyl group having 6 carbon atoms such as an n-hexyl group; an alkyl group having 7 carbon atoms such as an n-heptyl group; and n-octyl. Group, 1-n-butylbutyl group, 1-n-propylpentyl group, 1-ethylhexyl group, 2-ethylhexyl group, 3-ethylhexyl group, 4-ethylhexyl group, 1-methylheptyl group, 2-methylheptyl group, 6 -Alkyl group having 8 carbon atoms such as methylheptyl group, 2,4,4-trimethylpenttyl group, 2,5-dimethylhexyl group; n-nonyl group, 1-n-propylhexyl group, 2-n-propylhexyl Group, 1-ethylheptyl group, 2-ethylheptyl group, 1-methyloctyl group, 2-methyloctyl group, 6-methyloctyl group, 2,3,3,4-tetramethylpentyl group, 3,5,5 -Alkyl group having 9 carbon atoms such as trimethylhexyl group; n-decyl group, 1-n-pentylpentyl group, 1-n-butylhexyl group, 2-n-butylhexyl group, 1-n-propylheptyl group, Alkyl group having 10 carbon atoms such as 1-ethyloctyl group, 2-ethyloctyl group, 1-methylnonyl group, 2-methylnonyl group, 3,7-dimethyloctyl group; n-undecyl group, 1-n-butylheptyl group , 2-n-butylheptyl group, 1-n-propyloctyl group, 2-n-propyloctyl group, 1-ethylnonyl group, 2-ethylnonyl group and other 11-carbon alkyl groups; n-dodecyl group, 1- 12 carbon atoms such as n-pentylheptyl group, 2-n-pentylheptyl group, 1-n-butyloctyl group, 2-n-butyloctyl group, 1-n-propylnonyl group, 2-n-propylnonyl group, etc. Alkyl group; n-tridecyl group, 1-n-pentyloctyl group, 2-n-pentyloctyl group, 1-n-butylnonyl group, 2-n-butylnonyl group, 1-methyldodecyl group, 2-methyldodecyl group Such as an alkyl group having 13 carbon atoms; n-tetradecyl group, 1-n-heptyl heptyl group, 1-n-hexyl octyl group, 2-n-hexyl octyl group, 1-n-pentyl nonyl group, 2-n- 14-carbon alkyl group such as pentyl-nonyl group; 15-carbon alkyl group such as n-pentadecyl group, 1-n-heptyloctyl group, 1-n-hexylnonyl group, 2-n-hexylnonyl group; n -Hexadecyl group, 2-n-hexyldecyl group, 1-n-octyloctyl group, 1-n-heptylnonyl group, 2-n-hepti Alkyl group having 16 carbon atoms such as lunayl group; alkyl group having 17 carbon atoms such as n-heptadecyl group and 1-n-octylnonyl group; alkyl having 18 carbon atoms such as n-octadecyl group and 1-n-nonylnonyl group. Group; Alkyl group having 19 carbon atoms such as n-nonadecyl group; Alkyl group having 20 carbon atoms such as n-eicosyl group and 2-n-octyldodecyl group; Alkyl group having 21 carbon atoms such as n-heneicosyl group; n -Alkyl group having 22 carbon atoms such as docosyl group; alkyl group having 23 carbon atoms such as n-tricosyl group; alkyl group having 24 carbon atoms such as n-tetracosyl group and 2-n-decyltetradecyl group; and the like. Be done. Among them, particularly preferably 2-ethylhexyl group, 3,7-dimethyloctyl group, 2-n-butyloctyl group, 2-n-hexyldecyl group, 2-n-octyldodecyl group, 2-n-decyltetradecyl group. Is. When the hydrocarbon group represented by R ¹³ to R ¹⁷ is the above group, the polymer compound (1) has improved solubility in an organic solvent and has appropriate crystallinity.

The hydrocarbon group represented by R ¹³ to R ¹⁷ is particularly preferably a branched chain alkyl group having 8 to 16 carbon atoms.

The formula (t3) ~ formula (t5), R ¹⁸ in the * -Si (R ¹⁸⁾ ₃ of the groups represented by R ¹⁵ ~ R ¹⁷ are each independently of 1 to 20 carbon atoms aliphatic hydrocarbon It represents a group or an aromatic hydrocarbon group having 6 to 10 carbon atoms, and a plurality of R ^18s may be the same or different. When R ¹⁵ to R ¹⁷ are groups represented by * -Si (R ¹⁸ ) ₃ , the solubility of the polymer compound (1) in an organic solvent is improved.

The halogen atom represented by R ¹⁷ is preferably fluorine, chlorine, bromine or iodine.

The number of carbon atoms of the aliphatic hydrocarbon group represented by R ¹⁸ is preferably 1 to 18, and more preferably 1 to 8. Examples of the aliphatic hydrocarbon group represented by R ¹⁸ include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a tert-butyl group, an isobutyl group, an n-pentyl group and a tert-. Pentyl group, isopentyl group, n-hexyl group, n-heptyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, 2-octylbutyl Examples thereof include a group, an n-tridecyl group, an n-tetradecyl group, an n-pentadecyl group, an n-hexadecyl group, a 2-hexadecyl group, an n-heptadecyl group and an octadecyl group. The number of carbon atoms of the aromatic hydrocarbon group represented by R ¹⁸ is preferably 6 to 8, more preferably 6 or 7, and particularly preferably 6. Examples of the aromatic hydrocarbon group represented by R ¹⁸ include a phenyl group and the like. Among them, R ¹⁸ is preferably an aliphatic hydrocarbon group having 1 to 20 carbon atoms, more preferably a branched aliphatic hydrocarbon group having 1 to 20 carbon atoms, and particularly preferably an isopropyl group.

The plurality of R ^18s may be the same or different, but are preferably the same.

In the above formulas (t3) to (t5), the groups of * -Si (R ¹⁸ ) ₃ represented by R ¹⁵ to R ¹⁷ are specifically trimethylsilyl groups, ethyldimethylsilyl groups, and isopropyldimethylsilyl groups. Alkylsilyl groups such as groups, triisopropylsilyl groups, tert-butyldimethylsilyl groups, triethylsilyl groups, triisobutylsilyl groups, tripropylsilyl groups, tributylsilyl groups, dimethylphenylsilyl groups, methyldiphenylsilyl groups; triphenylsilyl groups. Examples thereof include an arylsilyl group such as a tert-butylchlorodiphenylsilyl group; and the like. Of these, an alkylsilyl group is preferable, and a trimethylsilyl group or a triisopropylsilyl group is particularly preferable.

In the above formula (t5), R ¹⁹ or R ²⁰ in the group * -O-R ¹⁹ or * -S-R ²⁰ represented by R ¹⁷ are each independently a hydrocarbon group having 6 to 30 carbon atoms As the hydrocarbon group having 6 to 30 carbon atoms, the group exemplified as the hydrocarbon group having 6 to 30 carbon atoms represented by R ¹³ to R ¹⁷ can be preferably used.

In the above formula (t3), the plurality of R ^15s may be the same or different, but are preferably the same. n1 is preferably 1 or 2, more preferably 1. In the above formula (t4), the plurality of R ^16s may be the same or different, but are preferably the same. n2 is preferably 1. In the above formula (t5), the plurality of R ^17s may be the same or different, but are preferably the same. n3 is preferably an integer of 1 to 3, more preferably 1 or 2, and even more preferably 1.

As T ¹ and T ² , an electron donating group or an electron attracting group can be used. Examples of the electron donating group include a group represented by any of the formulas (t1) to (t3).

In the above formulas (t1) to (t3), * represents a bond that binds to the thiazole ring of the benzobisthiazole structural unit.

The above R ¹³ to R ¹⁵ represent the same groups as described above. n1 is synonymous with the above.

As the electron donating group, the group represented by the above formula (t1) or the above formula (t3) is more preferable, and the above formula is more preferable from the viewpoint of excellent flatness as a whole structural unit represented by the above formula (1). The group represented by (t3) is more preferable, and the group represented by the following formulas (t3-1) to (t3-16) is particularly preferable. In the following formulas (t3-1) to (t3-16), * represents a bond.

Examples of the electron-attracting group include a group represented by the following formula (t4) or the following formula (t5).

In the above formulas (t4) and (t5), * represents a bond that binds to the thiazole ring of the benzobisthiazole structural unit.

The above R ¹⁶ and R ¹⁷ represent the same groups as described above. n2 and n3 are synonymous with the above.

In the benzobisthiazole structural unit represented by the above formula (1), B ¹ and B ² independently represent a thiophene ring, a thiazole ring, or an ethynylene group. The thiophene ring may be substituted with a hydrocarbon group, and the thiazole ring may be substituted with a hydrocarbon group.

The above B ¹ and B ² may be the same or different from each other, but are preferably the same from the viewpoint of easy production.

B ¹ and B ² are preferably groups represented by any of the following formulas (b1) to (b3) independently. That is, the thiophene ring represented by B ¹ and B ² is preferably a group represented by the following formula (b 1), and the thiazole ring represented by B ¹ and B ² is represented by the following formula (b 2). The group represented by the following formula (b3) is preferable as the ethynylene group represented by B ¹ and B ² . When the above B ¹ and B ² are groups represented by the following formulas (b1) and (b2), the benzobisthiazole structural unit represented by the above formula (1) as a whole is excellent in flatness and can be obtained. The polymer compound (1) as a whole has excellent flatness. Further, when the above B ¹ and B ² are groups represented by the following formulas (b1) and (b2), an interaction between S atoms and N atoms occurs in the benzobisthiazole structural unit, and the flatness is further improved. improves. As a result, the energy conversion efficiency PCE can be further increased.

In the above formulas (b1) to (b3), R ²¹ and R ²² each independently represent a hydrocarbon group having 6 to 30 carbon atoms. n4 represents an integer of 0 to 2, n5 represents 0 or 1, and a plurality of R ^21s may be the same or different. * Represents a bond, and * on the left represents a bond that binds to the benzene ring of the benzobisthiazole structural unit.

In the above formulas (b1) and (b2), it is preferable that R ²¹ and R ²² are hydrocarbon groups having 6 to 30 carbon atoms because the energy conversion efficiency PCE may be further enhanced. In the above formulas (b1) and (b2), the hydrocarbon group having 6 to 30 carbon atoms represented by R ²¹ and R ²² is a hydrocarbon group having 6 to 30 carbon atoms represented by R ¹³ to R ¹⁷ above. The group exemplified as the hydrogen group can be preferably used.

In the above formula (b1), the plurality of R ^21s may be the same or different, but are preferably the same. n4 is preferably 0 or 1, more preferably 0. When n4 is 0, it is preferable because the donor-acceptor type semiconductor polymer can be easily formed. In the above formula (b2), n5 is preferably 0. When n5 is 0, it is preferable because the donor-acceptor type semiconductor polymer can be easily formed.

Specific examples of the benzobisthiazole structural unit represented by the above formula (1) include structural units represented by the following formulas (1-1) to (1-48).

The polymer compound containing the benzobisthiazole structural unit represented by the above formula (1) is preferably a donor-acceptor type semiconductor polymer compound.

Conventionally known structural units can be used as the copolymerization component (12) for forming the donor-acceptor type semiconductor polymer compound in combination with the benzobisthiazole structural unit represented by the above formula (1). The polymerization component (12) may be a donor unit or an acceptor unit. Specific examples of the copolymerization component (12) include the following structural units.

[In the formulas (c1) to (c45), R ³⁰ to R ⁸¹ each independently represent a group similar to the hydrocarbon group having 6 to 30 carbon atoms represented by R ¹³ to R ¹⁷ , and A ³⁰ , A ³¹ independently represent the same groups as T ¹ and T ^2, and are specifically substituted with an alkoxy group, a thioalkoxy group, a hydrocarbon group or an organosilyl group, respectively. It may be a thiophene ring, a thiazole ring which may be substituted with a hydrocarbon group or an organosilyl group, a hydrocarbon group, an organosilyl group, an alkoxy group, a thioalkoxy group, a trifluoromethyl group, or Represents a phenyl group that may be substituted with a halogen atom. In equation (c13), j represents an integer from 0 to 4. ● represents a bond that binds to B ¹ or B ² of the benzobisthiazole structural unit represented by the formula (1). ]

The groups represented by the above formulas (c1) to (c32) act as acceptor units, and the groups represented by the above formulas (c34) to (c45) act as donor units. Is the basis.

The group represented by the above formula (c33) may act as an acceptor unit or a donor unit depending on the types of A ³⁰ and A ³¹ .

The ratio of the structural unit represented by the formula (1) in the polymer compound (1) to the repeating unit of the copolymerization component (12) is not particularly limited, but is usually preferably 1 mol% or more. It is preferably 5 mol% or more, more preferably 15 mol% or more, and particularly preferably 30 mol% or more. On the other hand, it is usually preferably 99 mol% or less, more preferably 95 mol% or less, still more preferably 85 mol% or less, and particularly preferably 70 mol% or less. The ratio of the structural unit represented by the formula (1) to the repeating unit of the copolymerization component (12) is the molecular weight of the structural unit represented by the formula (1) and the structure represented by the formula (1). It may be calculated based on the molecular weight of the copolymerization component (12) that copolymerizes with the unit.

In the polymer compound (1), the arrangement state of the benzobisthiazole structural unit represented by the formula (1) and the copolymerization component (12) may be alternating, blocked or random. That is, the polymer compound (1) may be any of an alternating copolymer, a block copolymer, and a random copolymer, and more preferably an alternating copolymer.

In the polymer compound (1), the benzobisthiazole structural unit represented by the formula (1) and the copolymerization component (12) may each contain only one type. Further, two or more kinds of benzobisthiazole structural units represented by the above formula (1) may be contained, and two or more kinds of copolymerization component (12) may be contained. The type of the benzobisthiazole structural unit and the copolymerization component (12) represented by the above formula (1) is not limited, but is usually preferably 8 or less, and more preferably 5 or less. Particularly preferably, it is a polymer compound (1) containing one of the benzobisthiazole structural units represented by the formula (1) and one of the copolymerization components (12) alternately, and most preferably. It is a polymer compound (1) containing only one type of structural unit represented by the formula (1) and only one type of copolymerization component (12) alternately.

Preferred specific examples of the above polymer compound (1) are shown below. In the following specific examples, ^RT is an n-octyl group, a 2-ethylhexyl group, a 3,7-dimethyloctyl group, a 2-n-butyloctyl group, a 2-n-hexyldecyl group, a 2-n-octyldodecyl group. , 2-n-decyltetradecyl group, triisopropylsilyl group. R ⁴³ represents an n-octyl group, a 2-ethylhexyl group, a 3,7-dimethyloctyl group, a 2-n-butyloctyl group, and a 2-n-hexyldecyl group. When the polymer compound (1) contains a plurality of repeating units, the ratio of the number of each repeating unit is arbitrary.

The polymer compound (1) preferably has absorption in a long wavelength region (600 nm or more). Further, the photoelectric conversion element using the polymer compound (1) exhibits a high open circuit voltage (Voc) and a high energy conversion efficiency PCE. The polymer compound (1) is a p-type organic semiconductor compound, and the aromatic compound represented by the formula (2) described later and / or the aromatic compound represented by the formula (3) is an n-type organic semiconductor compound. When combined, they exhibit particularly high energy conversion efficiency PCE. In addition, the polymer compound (1) has an advantage that the HOMO energy level is low and it is difficult to be oxidized. Further, since the polymer compound (1) exhibits high solubility in a solvent, it has an advantage that coating film formation is easy. Further, since the range of selection of the solvent is widened when the coating film is formed, a solvent more suitable for the film formation can be selected, and the film quality of the formed active layer can be improved. This is also considered to be one of the reasons why the photoelectric conversion element using the polymer compound (1) exhibits high energy conversion efficiency PCE.

The weight average molecular weight (Mw) of the polymer compound (1) is generally preferably 2000 or more and 500,000 or less, and more preferably 3000 or more and 200,000 or less. The number average molecular weight (Mn) of the polymer compound (1) is generally preferably 2000 or more and 500,000 or less, and more preferably 3000 or more and 200,000 or less. The weight average molecular weight (Mw) and number average molecular weight (Mn) of the polymer compound (1) can be calculated based on a calibration curve prepared by using gel permeation chromatography and polystyrene as a standard sample.

The maximum light absorption wavelength (λmax) of the polymer compound (1) is preferably 400 nm or more, more preferably 450 nm or more, while usually 1200 nm or less, more preferably 1000 nm or less, still more preferably 900 nm or less. is there. The half width is usually preferably 10 nm or more, more preferably 20 nm or more, and usually 300 nm or less. Further, it is desirable that the absorption wavelength region of the polymer compound (1) is closer to the absorption wavelength region of sunlight.

The solubility of the polymer compound (1) is not particularly limited, but the solubility in chlorobenzene at 25 ° C. is usually 0.1% by mass or more, more preferably 0.4% by mass or more, still more preferably 0.8% by mass. % Or more, on the other hand, usually 30% by mass or less, more preferably 20% by mass or less. High solubility is preferable in that the active layer can be formed thicker.

The polymer compound (1) is preferably one that interacts between molecules. In the present invention, the interaction between molecules means that the distance between polymer chains is shortened due to the interaction of π-π stacking between molecules of the polymer compound and the like. The stronger the interaction, the higher the carrier mobility and / or crystallinity of the polymeric compound tends to be. That is, since charge transfer between molecules is likely to occur in a polymer compound that interacts between molecules, a p-type organic semiconductor compound (polymer compound (1)) and an n-type organic semiconductor compound in the active layer (X) It is considered that the holes generated at the interface with and can be efficiently transported to the anode (A).

Next, a method capable of producing the above polymer compound (1) will be described.

The polymer compound (1) can be produced by coupling a compound having a benzobisthiazole structural unit represented by the formula (1) with the following copolymer component (12).

The compound having the benzobisthiazole structural unit represented by the above formula (1) can be produced, for example, by the method described in International Publication No. WO2016 / 132917.

The coupling reaction between the compound having the benzobisthiazole structural unit represented by the above formula (1) and the following copolymer component (12) may be carried out in the presence of a metal catalyst. That is, it can be carried out by reacting a compound having a benzobisthiazole structural unit represented by the above formula (1) with any of the compounds represented by the following formulas (C1) to (C45). The polymer compound (1) thus obtained becomes a donor-acceptor type polymer compound.

[In the formulas (C1) to (C45), R ³⁰ to R ⁸¹ independently represent groups similar to the hydrocarbon groups having 6 to 30 carbon atoms represented by R ¹³ to R ¹⁷ , and A ³⁰ , A ³¹ independently represent the same groups as T ¹ and T ^2, and are specifically substituted with an alkoxy group, a thioalkoxy group, a hydrocarbon group or an organosilyl group, respectively. It may be a thiophene ring, a thiazole ring which may be substituted with a hydrocarbon group or an organosilyl group, a hydrocarbon group, an organosilyl group, an alkoxy group, a thioalkoxy group, a trifluoromethyl group, or Represents a phenyl group that may be substituted with a halogen atom. In equation (C13), j represents an integer from 0 to 4. X represents a halogen atom. ]

(Other p-type organic semiconductor compounds)
The active layer (X) contains the polymer compound (1) as a p-type organic semiconductor compound, and further does not have the benzobisthiazole structural unit represented by the formula (1). ) May be contained. That is, the polymer compound (1) and the organic semiconductor compound (11) may be mixed and / or laminated to form the active layer (X). The organic semiconductor compound (11) that can be used in combination will be described below. The organic semiconductor compound (11) may be a high molecular weight organic semiconductor compound or a low molecular weight organic semiconductor compound, but a high molecular weight organic semiconductor compound is preferable.

(Organic semiconductor compound (11))
Examples of the organic semiconductor compound (11) include conjugated copolymer semiconductor compounds such as polythiophene, polyfluorene, polyphenylene vinylene, polythienylene vinylene, polyacetylene and polyaniline; copolymers such as oligothiophene substituted with an alkyl group or other substituents. Semiconductor compounds; copolymer semiconductor compounds obtained by copolymerizing two or more kinds of monomer units; and the like.

Conjugated copolymers include, for example, Handbook of Control Polymers, 3rd Ed. (2 volumes in total), 2007, J. Mol. Polymer. Sci. Part A: Polym. Chem. 2013, 51, 743-768, J. Mol. Am. Chem. Soc. 2009,131,13886-13887, Angew.Chem. Int. Ed. 2013, 52, 8341-8344, Adv. Mater. Copolymers that can be synthesized by combining the copolymers and derivatives thereof described in known literature such as 2009, 21, 2093-2097, and the monomers described can be used.

The organic semiconductor compound (11) may be one kind of compound or a mixture of a plurality of kinds of compounds. By using the organic semiconductor compound (11), it is expected that the amount of absorbance will increase due to the addition of the absorption wavelength band. Specific examples of the organic semiconductor compound (11) include, but are not limited to, the following.

The HOMO (maximum occupied orbital) energy level of the p-type organic semiconductor compound is not particularly limited and can be selected depending on the type of the n-type organic semiconductor compound described later. In particular, when the aromatic compound (2) and / or the aromatic compound (3) and the fullerene compound are used in combination as the n-type organic semiconductor compound, the lower limit of the HOMO energy level of the p-type organic semiconductor compound is usually set. It is preferably −7 eV or higher, more preferably −6.5 eV or higher, and particularly preferably −6.2 eV or higher. On the other hand, the upper limit of the HOMO energy level is usually preferably -4.0 eV or less, more preferably -4.5 eV or less, and particularly preferably -5.1 eV or less. In particular, when the HOMO energy level of the p-type organic semiconductor compound is -6.2 eV or more, the characteristics as a p-type semiconductor are improved, and the HOMO energy level of the p-type organic semiconductor compound is -5.1 eV or less. As a result, the stability of the p-type organic semiconductor compound is improved, and the open circuit voltage (Voc) is also improved.

The LUMO (minimum empty orbit) energy level of the p-type organic semiconductor compound is not particularly limited and can be selected depending on the type of the n-type organic semiconductor compound described later. In particular, when the aromatic compound (2) and / or the aromatic compound (3) and the fullerene compound are used in combination as the n-type organic semiconductor compound, the LUMO energy level of the p-type organic semiconductor compound is usually -4. It is preferably .5 eV or more, more preferably -4.3 eV or more. When the LUMO energy level of the p-type organic semiconductor compound is −4.5 eV or more, electron transfer to the n-type organic semiconductor compound is likely to occur, and the short-circuit current density (Jsc) is improved. On the other hand, the upper limit of the LUMO energy level is usually preferably −2.5 eV or less, more preferably −2.7 eV or less. When the LUMO energy level of the p-type organic semiconductor compound is −2.5 eV or less, the band gap is adjusted, long-wavelength light energy can be effectively absorbed, and the short-circuit current density (Jsc) is improved.

When the LUMO energy level of the p-type organic semiconductor compound is -4.5 eV or more, electron transfer to the n-type organic semiconductor compound is likely to occur, and the short-circuit current density (Jsc) is improved. Examples of the method for calculating the LUMO energy level and the HOMO energy level include a method of theoretically calculating the calculated value and a method of actually measuring the LUMO energy level. Examples of the method for theoretically calculating the calculated value include a semi-empirical molecular orbital method and an ab initio molecular orbital method. Examples of the actual measurement method include an ultraviolet-visible absorption spectrum measurement method or a method of measuring the ionization potential with an ultraviolet photoelectron analyzer (“AC-3” manufactured by RIKEN Keiki Co., Ltd.) under normal temperature and pressure. Among them, it is preferable to measure using an ultraviolet photoelectron analyzer, and in the present invention, "AC-3" manufactured by RIKEN KEIKI is used as the ultraviolet photoelectron analyzer.

[1.1.3 n-type organic semiconductor compounds]
The active layer (X) is an aromatic compound [aromatic compound (2)] represented by the following formula (2) and / or an aromatic compound [fragrance] represented by the following formula (3). Group compound (3)] is contained.

The aromatic compound (2) and the aromatic compound (3) are both n-type organic semiconductor compounds. By using the aromatic compound (2) and / or the aromatic compound (3) as the n-type organic semiconductor compound and the above-mentioned polymer compound (1) as the p-type organic semiconductor compound, the speed and efficiency are increased. Charge separation is possible.

(Aromatic compound (2))
The aromatic compound (2) is a compound represented by the following formula (2).

In the above formula (2), R ¹⁰¹ to R ¹¹⁶ are independently hydrogen atoms, alkyl groups, alkoxy groups, thioalkoxy groups, fluorine atoms, or benzene. It is a ring or represents a thiophene ring. The benzene ring may be substituted with an alkyl group, an alkoxy group, a thioalkoxy group, or a fluorine atom, and the thiophene ring may be substituted with an alkyl group, an alkoxy group, a thioalkoxy group, or a fluorine atom. The alkyl group represented by R ¹⁰¹ to R ¹¹⁶ and the alkyl group substituted with the benzene ring or thiophene ring represented by R ¹⁰¹ to R ¹¹⁶ are preferably hydrocarbon groups having 1 to 10 carbon atoms, and are hydrocarbons. The group may be linear or may have a branch. The alkoxy group represented by R ¹⁰¹ to R ¹¹⁶ and the alkoxy group substituted with the benzene ring or the thiophene ring represented by R ¹⁰¹ to R ¹¹⁶ are some carbons of the hydrocarbon group having 1 to 10 carbon atoms. A group in which is replaced with oxygen is preferable. The thioalkoxy group represented by R ¹⁰¹ to R ¹¹⁶ and the thioalkoxy group substituted with the benzene ring or thiophene ring represented by R ¹⁰¹ to R ¹¹⁶ are one of the hydrocarbon groups having 1 to 10 carbon atoms. A group in which the carbon of the portion is replaced with sulfur is preferable. Each of R ¹⁰¹ to R ¹¹⁶ is independently a hydrogen atom, an alkyl group, a fluorine atom, or a benzene ring substituted with an alkyl group, an alkoxy group, or a thioalkoxy group. A thiophene ring substituted with an alkyl group is preferable, and a benzene ring substituted with a hydrogen atom or an alkyl group is particularly preferable.

A preferable specific example of the aromatic compound (2) is shown below.

(Aromatic compound (3))
The aromatic compound (3) is a compound represented by the following formula (3).

In the above formula (3), R ²⁰¹ to R ²¹⁴ are independently hydrogen atoms, alkyl groups, alkoxy groups, thioalkoxy groups, fluorine atoms, or benzene. It is a ring or represents a thiophene ring. The benzene ring may be substituted with an alkyl group, an alkoxy group, a thioalkoxy group, or a fluorine atom, and the thiophene ring may be substituted with an alkyl group, an alkoxy group, a thioalkoxy group, or a fluorine atom. The alkyl group represented by R ²⁰¹ to R ²¹⁴ and the alkyl group substituted with the benzene ring or the thiophene ring represented by R ²⁰¹ to R ²¹⁴ are preferably hydrocarbon groups having 1 to 10 carbon atoms, and are hydrocarbons. The group may be linear or may have a branch. The alkoxy group represented by R ²⁰¹ to R ²¹⁴ and the alkoxy group substituted with the benzene ring or the thiophene ring represented by R ²⁰¹ to R ²¹⁴ are carbons of a part of the hydrocarbon groups having 1 to 10 carbon atoms. A group in which is replaced with oxygen is preferable. The thioalkoxy group represented by R ²⁰¹ to R ²¹⁴ and the thioalkoxy group substituted with the benzene ring or thiophene ring represented by R ²⁰¹ to R ²¹⁴ are one of the hydrocarbon groups having 1 to 10 carbon atoms. A group in which carbon in the portion is replaced with sulfur is preferable. R ²⁰¹ to R ²¹⁴ are independently substituted with an alkyl group, an alkyl group, an alkoxy group, a fluorine atom, an alkyl group, an alkoxy group, or a thioalkoxy group, respectively. A benzene ring is preferable, and a benzene ring which is a hydrogen atom or is substituted with an alkyl group is more preferable.

A preferable specific example of the aromatic compound (3) is shown below.

Comparing the aromatic compound (2) and the aromatic compound (3), the energy conversion efficiency PCE tends to be higher when the aromatic compound (2) is used as the n-type organic semiconductor compound. It is preferable because there is.

(Other n-type organic semiconductor compounds)
The active layer (X) contains the aromatic compound (2) and / or the aromatic compound (3) as an n-type organic semiconductor compound, and further contains the aromatic compound (2) and the aromatic compound. An n-type organic semiconductor compound other than the sex compound (3) may be contained.

That is, the active layer (X) may be formed by mixing and / or laminating the aromatic compound (2) and / or the aromatic compound (3) and the n-type organic semiconductor compound. The n-type organic semiconductor compound that can be used in combination will be described below. The n-type organic semiconductor compound may be a high molecular weight organic semiconductor compound or a low molecular weight organic semiconductor compound, but a high molecular weight organic semiconductor compound is preferable.

As the n-type organic semiconductor compound other than the aromatic compound (2) and the aromatic compound (3), the lowest empty orbital (LUMO) level is generally -3.5 to -4.5 eV. A π-electron conjugated compound such as a π-electron conjugated compound, for example, a π-electron conjugated compound containing a thiophene ring and a benzene ring, fullerene or a derivative thereof, octaazaporphyrin, etc., in which the hydrogen atom of a p-type organic semiconductor compound is replaced with a fluorine atom. Aromatic carboxylic acid anhydrides such as perfluoro compounds (for example, perfluoropentacene and perfluorophthalocyanine), naphthalenetetracarboxylic acid anhydrides, naphthalenetetracarboxylic acid diimides, perylenetetracarboxylic acid anhydrides, and perylenetetracarboxylic acid diimides and the like. Examples thereof include polymer compounds containing an imidized product as a skeleton. Among these n-type organic semiconductor compounds, fullerenes or derivatives thereof are preferable because they can perform charge separation from the polymer compound (1) at high speed and efficiently.

Fullerenes and their derivatives include C60 fullerenes, C70 fullerenes, C76 fullerenes, C78 fullerenes, C84 fullerenes, C240 fullerenes, C540 fullerenes, mixed fullerenes, fullerene nanotubes, and some of these hydrogen atoms, halogen atoms, substitutions or absences. Examples thereof include fullerene derivatives substituted with substituted alkyl groups, alkenyl groups, alkynyl groups, aryl groups, heteroaryl groups, cycloalkyl groups, silyl groups, ether groups, thioether groups, amino groups, silyl groups and the like. As the fullerene derivative, phenyl-C61-butyric acid ester, diphenyl-C62-bis (butyric acid ester), phenyl-C71-butyric acid ester, phenyl-C85-butyric acid ester or thienyl-C61-butyric acid ester is preferable, and the above-mentioned butyric acid ester is used. The carbon number of the alcohol moiety is preferably 1 to 30, more preferably 1 to 8, still more preferably 1 to 4, and most preferably 1. Examples of preferred fullerene derivatives are phenyl-C61-butyric acid methyl ester ([60] PCBM), phenyl-C61-butyric acid n-butyl ester ([60] PCBnB), phenyl-C61-butyric acid isobutyl ester ([60] PCBiB). , Phenyl-C61-butyric acid n-hexyl ester ([60] PCBH), phenyl-C61-butyric acid n-octyl ester ([60] PCBO), diphenyl-C62-bis (butyric acid methyl ester) (bis [60] PCBM) , Phenyl-C71-butyric acid methyl ester ([70] PCBM), phenyl-C85-butyric acid methyl ester ([84] PCBM), thienyl-C61-butyric acid methyl ester ([60] ThCBM), C60 pyrrolidinetrisic acid, C60 pyrrolidine Trisic acid ethyl ester, N-methylfuraropyrrolidine (MP-C60), (1,2-methanoflarene C60) -61-carboxylic acid, (1,2-methanoflarene C60) -61-carboxylic acid t-butyl ester , Japanese Patent Application Laid-Open No. 2008-1330889, etc., metallosenized fullerene, and US Pat. No. 7,329,709, etc., which have a cyclic ether group. There is no problem whether these are used alone or in combination of two or more.

<1.2 Cathode (C), Anode (A)>
The cathode (C) and anode (A) have a function of collecting holes and electrons generated by light absorption. Therefore, it is preferable to use an electrode suitable for collecting electrons [that is, a cathode (C)] and an electrode suitable for collecting holes [that is, an anode (A)] as the pair of electrodes. One of the pair of electrodes may be translucent, and both may be translucent. Translucent means that 40% or more of sunlight is transmitted. Further, it is preferable that the translucent transparent electrode has a sunlight transmittance of 70% or more in order to allow the transparent electrode to pass through and allow light to reach the active layer (X). The light transmittance can be measured with a normal spectrophotometer.

The cathode (C) is preferably an electrode having a function of smoothly extracting electrons generated in the active layer (X). The film thickness of the cathode (C) is not particularly limited, but is usually preferably 10 nm or more, more preferably 20 nm or more, and further preferably 50 nm or more. On the other hand, it is usually preferably 10 μm or less, more preferably 1 μm or less, still more preferably 500 nm or less. When the film thickness of the cathode (C) is 10 nm or more, the sheet resistance is suppressed, and when the film thickness of the cathode (C) is 10 μm or less, the light is efficiently transferred to electricity without lowering the light transmittance. Can be converted. When the cathode (C) is a transparent electrode, it is necessary to select a film thickness that can achieve both light transmittance and sheet resistance. The sheet resistance of the cathode (C) is not particularly limited, but is usually preferably 1 Ω / sq or more, while it is preferably 1000 Ω / sq or less, more preferably 500 Ω / sq or less, and further preferably 100 Ω / sq or less.

The anode (A) is preferably an electrode having a function of smoothly extracting holes generated in the active layer (X). The film thickness of the anode (A) is not particularly limited, but is usually preferably 10 nm or more, more preferably 20 nm or more, and further preferably 50 nm or more. On the other hand, it is usually preferably 10 μm or less, more preferably 1 μm or less, still more preferably 500 nm or less. When the film thickness of the anode (A) is 10 nm or more, the sheet resistance is suppressed, and when the film thickness of the anode (A) is 10 μm or less, the light is efficiently transferred to electricity without lowering the light transmittance. Can be converted. When the anode (A) is a transparent electrode, it is necessary to select a film thickness capable of achieving both light transmittance and sheet resistance. The sheet resistance of the anode (A) is not particularly limited, but is usually preferably 1 Ω / sq or more, while it is preferably 1000 Ω / sq or less, more preferably 500 Ω / sq or less, and further preferably 100 Ω / sq or less.

The cathode (C) and the anode (A) may have a laminated structure of two or more layers. Further, the characteristics (electrical characteristics, wet characteristics, etc.) may be improved by performing surface treatment on the cathode (C) and the anode (A).

Next, the materials of the cathode (C) and the anode (A) will be described. The materials of the cathode (C) and the anode (A) differ depending on the laminated structure with respect to the substrate.

(In the case of the photoelectric conversion element shown in FIG. 1)
As shown in FIG. 1, when the base material is arranged on one side of the cathode (C) and the active layer (X) is arranged on the other side of the cathode (C), the material of the cathode (C). Examples include conductive metal oxides such as nickel oxide, tin oxide, indium oxide, indium tin oxide (ITO), indium-zirconium oxide (IZO), titanium oxide or zinc oxide; gold, platinum, silver, chromium. , Metals such as aluminum, magnesium or cobalt, or alloys thereof.

In the photoelectric conversion element shown in FIG. 1, it is preferable that the cathode (C) has translucency. When the cathode (C) is a transparent electrode, it is preferable to use a translucent conductive metal oxide such as ITO, zinc oxide or tin oxide, and it is more preferable to use ITO.

Examples of the method for forming the cathode (C) include a vacuum film forming method such as a vapor deposition method or a sputtering method, or a wet coating method in which an ink containing nanoparticles or a precursor is applied to form a film.

Examples of the material of the anode (A) include metals such as platinum, gold, silver, copper, iron, tin, zinc, aluminum, indium, chromium, lithium, sodium, potassium, cesium, calcium or magnesium and their alloys; Inorganic salts such as lithium oxide and cesium fluoride; metal oxides such as nickel oxide, aluminum oxide, lithium oxide, indium tin oxide (ITO) or cesium oxide; sulfone to polythiophene, polypyrrole, polyacetylene, triphenylenediamine or polyaniline, etc. Examples thereof include a conductive polymer doped with an acid and / or iodine, a polythiophene derivative having a sulfonyl group as a substituent, and a conductive organic compound such as arylamine. From the viewpoint of electrode protection, the anode (A) is preferably a metal electrode formed of a metal such as platinum, gold, silver, copper, iron, tin, aluminum, calcium or indium and an alloy using these metals.

Examples of the method for forming the anode (A) include a vacuum film forming method such as a vapor deposition method or a sputtering method, or a wet coating method in which an ink containing nanoparticles or a precursor is applied to form a film.

(In the case of the photoelectric conversion element shown in FIG. 2)
As shown in FIG. 2, when the base material is arranged on one side of the anode (A) and the active layer (X) is arranged on the other side of the anode (A), the material of the cathode (C). Examples include metals such as platinum, gold, silver, copper, iron, tin, zinc, aluminum, indium, chromium, lithium, sodium, potassium, cesium, calcium or magnesium and their alloys; lithium fluoride and cesium fluoride. Inorganic salts such as: nickel oxide, aluminum oxide, lithium oxide, indium tin oxide (ITO), metal oxides such as cesium oxide, and the like. From the viewpoint of electrode protection, the cathode (C) is preferably a metal electrode formed of a metal such as platinum, gold, silver, copper, iron, tin, aluminum, calcium or indium and an alloy using these metals.

Examples of the material of the anode (A) include conductive metal oxides such as nickel oxide, tin oxide, indium oxide, indium tin oxide (ITO), indium-zinc oxide (IZO), titanium oxide or zinc oxide; gold. , Platinum, silver, chromium, cobalt and other metals or alloys thereof; polythiophene, polypyrrole, polyacetylene, triphenylenediamine, polyaniline and the like, and having a conductive polymer and sulfonyl group doped with sulfonic acid and / or iodine as substituents. Examples thereof include polythiophene derivatives and conductive organic compounds such as arylamine.

In the photoelectric conversion element shown in FIG. 2, it is preferable that the anode (A) has translucency. When the anode (A) is a transparent electrode, it is preferable to use a translucent conductive metal oxide such as ITO, zinc oxide or tin oxide, and it is particularly preferable to use ITO.

<1.3 Base material (B)>
The photoelectric conversion element usually has a base material (B) as a support. That is, a cathode (C), an anode (A), and an active layer (X) are formed as electrodes on the base material (B).

The material of the base material (B) is not particularly limited as long as the effect of the present invention is not significantly impaired. Preferable examples of the material of the base material (B) are inorganic materials such as quartz, glass, sapphire or titania; polyethylene terephthalate, polyethylene naphthalate, polyether sulfone, polyimide, nylon, polystyrene, polyvinyl alcohol, ethylene vinyl alcohol. Copolymers, fluororesin films, polyolefins such as vinyl chloride or polyethylene, organic materials such as cellulose, polyvinylidene chloride, aramid, polyphenylene sulfide, polyurethane, polycarbonate, polyarylate, polynorbornene or epoxy resins; paper or synthetic paper, etc. Paper material; a composite material such as a metal such as stainless steel, titanium, or aluminum coated or laminated on the surface to impart insulating properties; and the like. Examples of the glass include soda glass, blue plate glass, non-alkali glass and the like. Of these, non-alkali glass is preferable because there are few elution ions from the glass.

The shape of the base material (B) is not limited, and for example, a plate shape, a film shape, a sheet shape, or the like can be used.

The film thickness of the base material (B) is not limited, but is usually preferably 5 μm or more, more preferably 20 μm or more, while usually 20 mm or less, more preferably 10 mm or less. It is preferable that the film thickness of the base material (B) is 5 μm or more because the possibility that the strength of the photoelectric conversion element is insufficient is reduced. It is preferable that the film thickness of the base material (B) is 20 mm or less because the cost can be suppressed and the weight does not become heavy. In particular, when the material of the base material (B) is glass, the film thickness is usually preferably 0.01 mm or more, more preferably 0.1 mm or more, while it is usually preferably 10 mm or less, more preferably 5 mm or less. Is. It is preferable that the film thickness of the glass base material (B) is 0.01 mm or more because the mechanical strength increases and it becomes difficult to crack. Further, it is preferable that the film thickness of the glass base material (B) is 5 mm or less because the weight does not become heavy.

<1.4 Buffer layers (E), (H)>
The photoelectric conversion element has an electron transport layer (E) as a buffer layer between the active layer (X) and the cathode (C), and holes as a buffer layer between the active layer (X) and the anode (A). It is preferable to have a transport layer (H). By providing the buffer layer, the movement of electrons or holes between the active layer (X) and the cathode (C) or the anode (A) can be facilitated, and a short circuit between the electrodes can be prevented.

The hole transport layer (H) and the electron transport layer (E) are arranged so as to sandwich the active layer (X) between a pair of electrodes (cathode and anode). That is, when the photoelectric conversion element includes both the hole transport layer (H) and the electron transport layer (E), the anode (A), the hole transport layer (H), the active layer (X), and the electron transport layer (E). , And the cathode (C) are arranged in this order. When the photoelectric conversion element contains the hole transport layer (H) and does not include the electron transport layer (E), the anode (A), the hole transport layer (H), the active layer (X), and the cathode (C) are in this order. Be placed. When the photoelectric conversion element contains the electron transport layer (E) and does not include the hole transport layer (H), the anode (A), the active layer (X), the electron transport layer (E), and the cathode (C) are in this order. Be placed.

[1.4.1 Electron transport layer (E)]
The electron transport layer (E) is a layer for extracting electrons from the active layer (X) to the cathode (C), and is not particularly limited as long as it is an electron transporting material that improves the efficiency of electron extraction, and is organic. It may be a compound or an inorganic compound, but an inorganic compound is preferable.

Preferred examples of the material of the inorganic compound include alkali metal salts such as lithium, sodium, potassium, and cesium, metal oxides, and the like. Among them, as the alkali metal salt, a fluoride salt such as lithium fluoride, sodium fluoride, potassium fluoride, or cesium fluoride is preferable. As the metal oxide, a metal oxide having n-type semiconductor characteristics such as titanium oxide (TiOx) and zinc oxide (ZnO) is preferable. A more preferable material for the inorganic compound is a metal oxide having n-type semiconductor properties, such as titanium oxide (TiOx) or zinc oxide (ZnO). Titanium oxide (diox) is particularly preferable. Although the operating mechanism of such a material is unknown, it is conceivable to reduce the work function and increase the voltage applied to the inside of the solar cell element when combined with the cathode (VI).

The film thickness of the electron transport layer (E) is not particularly limited, but is usually preferably 0.1 nm or more, more preferably 0.5 nm or more, still more preferably 1.0 nm or more, and usually 200 nm or less. It is more preferably 150 nm or less, further preferably 100 nm or less, and particularly preferably 70 nm or less. When the film thickness of the electron transport layer (E) is 0.1 nm or more, it functions as a buffer material. When the film thickness of the electron transport layer (E) is 200 nm or less, electrons can be easily taken out, and the energy conversion efficiency PCE can be improved.

[14.2 Hole Transport Layer (H)]
The hole transport layer (H) is a layer for extracting holes from the active layer (X) to the anode (A), and is a hole transporting material capable of improving the efficiency of hole extraction. There is no particular limitation. Specifically, a conductive polymer obtained by doping polythiophene, polypyrrole, polyacetylene, triphenylenediamine, polyaniline, etc. with sulfonic acid and / or iodine, a polythiophene derivative having a sulfonyl group as a substituent, a conductive organic substance such as arylamine, etc. Examples thereof include compounds, metal oxides having p-type semiconductor properties such as molybdenum trioxide, vanadium pentoxide or nickel oxide, and the above-mentioned p-type organic semiconductor compounds. Among them, a conductive polymer doped with sulfonic acid is preferable, and poly (3,4-ethylenedioxythiophene) poly (styrene sulfonic acid) (PEDOT: PSS) and molybdenum oxide obtained by doping a polythiophene derivative with polystyrene sulfonic acid can be mentioned. And metal oxides such as vanadium oxide are more preferred. Further, a thin film of a metal such as gold, indium, silver or palladium can also be used. The thin film such as metal may be formed alone or in combination with the above-mentioned organic material.

The film thickness of the hole transport layer (H) is not particularly limited, but is usually preferably 0.2 nm or more, more preferably 0.5 nm or more, still more preferably 1.0 nm or more, and usually 400 nm or less. It is more preferably 200 nm or less, further preferably 100 nm or less, and particularly preferably 70 nm or less. When the film thickness of the hole transport layer (H) is 0.2 nm or more, it functions as a buffer material. When the film thickness of the hole transport layer (H) is 400 nm or less, holes can be easily taken out, and the energy conversion efficiency PCE can be improved.

There are no restrictions on the method of forming the electron transport layer (E) and the hole transport layer (H). For example, when a material having sublimation property is used, it can be formed by a vacuum vapor deposition method or the like. Further, for example, when a material soluble in a solvent is used, it can be formed by a wet coating method such as spin coating or an inkjet. When a semiconductor compound is used for the electron transport layer (E), the precursor may be converted into the semiconductor compound after forming a layer containing the semiconductor compound precursor as in the active layer (X).

<1.5 Manufacturing method of photoelectric conversion element>
The method for manufacturing the photoelectric conversion element is not particularly limited, but the photoelectric conversion element can be manufactured according to the following method.

(Photoelectric conversion element (I))
The photoelectric conversion element (I) is formed by sequentially laminating a base material (B), a cathode (C), an electron transport layer (E), an active layer (X), a hole transport layer (H), and an anode (A). Can be made. As described above, the electron transport layer (E) and / or the hole transport layer (H) may not necessarily be provided.

In the photoelectric conversion element (I), for example, a glass substrate (manufactured by Geomatec) in which an indium tin oxide (ITO) transparent conductive film is patterned as a cathode (C) is ultrasonically cleaned with acetone, and then ultrasonically cleaned with ethanol. After that, it is dried by a nitrogen blow and UV-ozone treatment is carried out to form a base material (B) with a cathode. Next, an electron transport layer converted into zinc oxide by applying a 0.5 M zinc acetate / 0.5 M aminoethanol / 2-methoxyethanol solution with a spin coater (3000 rpm, 40 seconds) and then annealing at 175 ° C. for 30 minutes. (E) can be formed. Next, it is carried into a glove box, spin-coated with a mixed solution of a p-type organic semiconductor compound and an n-type organic semiconductor compound in an inert gas atmosphere, and activated by annealing or drying under reduced pressure on a hot plate. A layer (X) can be formed. Then, molybdenum oxide is vapor-deposited under reduced pressure to prepare a hole transport layer (H). Finally, silver, which is an electrode, is vapor-deposited, and this is used as an anode (A) to obtain a photoelectric conversion element (I). Further, a photoelectric conversion element having a different configuration, for example, a photoelectric conversion element having at least one of an electron transport layer (E) and a hole transport layer (H) can be manufactured by the same method.

(Photoelectric conversion element (II))
The photoelectric conversion element (II) is formed by sequentially laminating a base material (B), an anode (A), a hole transport layer (H), an active layer (X), an electron transport layer (E), and a cathode (C). Can be made. As described above, the electron transport layer (E) and / or the hole transport layer (H) may not necessarily be provided.

In the photoelectric conversion element (II), for example, a glass substrate (manufactured by Geomatec) in which an indium tin oxide (ITO) transparent conductive film is patterned as an anode (A) is ultrasonically cleaned with acetone, and then ultrasonically cleaned with ethanol. After that, it is dried by a nitrogen blow and UV-ozone treatment is carried out to form a base material (B) with an anode. Then, a PEDOT-PSS (poly (3,4-ethylenedioxythiophene) -poly (styrene sulfonic acid)) aqueous dispersion was applied with a spin coater (5000 rpm, 50 seconds) and then annealed at 200 ° C. for 10 minutes. , The hole transport layer (H) can be formed. Next, it is carried into a glove box, spin-coated with a mixed solution of a p-type organic semiconductor compound and an n-type organic semiconductor compound in an inert gas atmosphere, and activated by annealing or drying under reduced pressure on a hot plate. A layer (X) can be formed. Next, in the atmosphere, an ethanol solution (about 0.3 v%) of tetraisopropyl orthotitamate can be spin-coated and converted into titanium oxide by the moisture in the atmosphere to prepare an electron transport layer (E). Finally, aluminum, which is an electrode, is vapor-deposited and used as a cathode (C) to obtain a photoelectric conversion element (II). Further, a photoelectric conversion element having a different configuration, for example, a photoelectric conversion element having at least one of a hole transport layer (H) and an electron transport layer (E) can be manufactured by the same method.

<1.6 Photoelectric conversion characteristics>
The photoelectric conversion characteristics of the photoelectric conversion element can be obtained as follows. The photoelectric conversion element is irradiated with light under AM 1.5G condition with a solar simulator at an irradiation intensity of 100 mW / cm ² , and the current-voltage characteristics are measured. From the obtained current-voltage curve, photoelectric conversion characteristics such as short-circuit current density (Jsc), open circuit voltage (Voc), curve factor (FF), series resistance, shunt resistance, and incident energy (Pin) can be obtained. Further, the energy conversion efficiency PCE can be calculated by the following equation based on the short-circuit current density (Jsc), the open circuit voltage (Voc), the curve factor (FF), and the incident energy (Pin).
PCE = (Jsc x Voc x FF / Pin) x 100

<2. Organic thin-film solar cell according to the present invention>
The photoelectric conversion element according to the present invention is preferably used as a solar cell element of a solar cell, particularly an organic thin film solar cell.

There is no limitation on the use of the organic thin-film solar cell according to the present invention, and it can be used for any purpose. The organic thin-film solar cell according to the present invention is, for example, a solar cell for building materials, a solar cell for automobiles, a solar cell for interiors, a solar cell for sensors, a solar cell for railways, a solar cell for ships, a solar cell for airplanes, and a spacecraft. It can be used as a solar cell, a solar cell for home appliances, a solar cell for a mobile phone, a solar cell for a toy, or the like.

The organic thin-film solar cell according to the present invention may be used as it is, or the organic thin-film solar cell according to the present invention may be installed on the base material (B) and used as a solar cell module. To give a specific example, when a plate material for building materials is used as the base material (B), a solar cell panel can be manufactured as a solar cell module by providing the organic thin film solar cell according to the present invention on the surface of the plate material.

This application claims the benefit of priority based on Japanese Patent Application No. 2019-112104 filed on June 17, 2019. The entire contents of the specification of Japanese Patent Application No. 2019-112104 are incorporated herein by reference.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited by the following Examples, and may be modified to the extent that it can be adapted to the above and the following purposes. It is possible, and they are all within the technical scope of the invention.

The measurement method used in the examples is as follows.

(NMR spectrum measurement)
For the compound, NMR spectrum measurement was performed using an NMR spectrum measuring device (“400MR” manufactured by Agilent (formerly Varian)).

(Gel Permeation Chromatography (GPC))
The compounds were measured for molecular weight using gel permeation chromatography (GPC). In the measurement, the compound is dissolved in a mobile phase solvent (chloroform) so as to have a concentration of 0.5 g / L, the measurement is performed under the following conditions, and the conversion is performed based on the calibration curve prepared using polystyrene as a standard sample. , The number average molecular weight (Mn) and the weight average molecular weight (Mw) of the compound were calculated. The GPC conditions in the measurement are as follows.
Mobile phase: Chloroform flow rate is 0.6 mL / min
Equipment: HLC-8320GPC (manufactured by Tosoh)
Column: TSKgel (registered trademark), SuperHM-H'2 + TSKgel (registered trademark), SuperH2000 (manufactured by Tosoh)

First, the synthetic conditions of the compound used in the examples will be described.

(Synthesis Example 1)
Synthesis of 2,6-bis [5- (2-hexyldecyl) thiophen-2-yl] benzo [1,2-d; 4,5-d'] bistiazole (DBTH-HDTH)

2,6-Diiodobenzo [1,2-d; 4,5-d'] bistazole (DBTH-DI, 5.2 g, 11.7 mmol), tributyl [5- (2-hexyldecyl) thiophene-in a 300 mL flask. 2-Il] Stannane (HDT-Sn, 23.2 g, 38.6 mmol), Tris (2-furyl) phosphine (443 mg, 1.87 mmol), Tris (dibenzylideneacetone) dipalladium (0) -chloroform adduct (0) 490 mg, 0.47 mol) and N, N-dimethylformamide (115 mL) were added and reacted at 120 ° C. for 23 hours. After completion of the reaction, the mixture was cooled to room temperature, water was added, the mixture was extracted twice with chloroform, the organic layer was washed with water, and then dried over anhydrous magnesium sulfate. Then, the crude product obtained by filtration and concentration was purified by column chromatography (silica gel, chloroform / hexane = 1/1) to obtain 2,6-bis [5- (2-hexyldecyl) thiophene-2-. Il] benzo [1,2-d; 4,5-d'] bistazole (DBTH-HDTH) was obtained in an amount of 5.62 g as a pale yellow solid (yield 60%). ¹ It was confirmed by ¹ H-NMR measurement that the target compound was produced.
^{1 1} H-NMR (400 MHz, CDCl ₃ ): δ 8.39 (s, 2H), 7.53 (d, J = 3.6 Hz, 2H), 6.81 (d, J = 3.6 Hz, 2H), 2.81 (m, 4H), 1.66 (m, 2H), 1.37-1.24 (m, 48H), 0.90 (t, J = 6.4 Hz, 6H), 0.88 (t, J = 6.4 Hz, 6H).

(Synthesis Example 2)
Of 2,6-bis [5- (2-hexyldecyl) thiophene-2-yl] -4,8-diiodobenzo [1,2-d; 4,5-d'] bistiazole (DI-DBTH-HDTH) Synthetic

In a 100 mL flask, the 2,6-bis [5- (2-hexyldecyl) thiophen-2-yl] benzo [1,2-d; 4,5-d'] bistazole obtained in Synthesis Example 1 above ( DBTH-HDTH (4 g, 4.97 mmol) and tetrahydrofuran (80 mL) were added and cooled to −40 ° C., then lithium diisopropylamide (2M solution, 5.5 mL, 10.9 mmol) was added dropwise, and the mixture was stirred for 30 minutes. Then, iodine (3.8 g, 14.9 mol) was added, and then the reaction was carried out at room temperature for 2 hours. After completion of the reaction, 10 mass% sodium hydrogen sulfite was added and extracted with chloroform, and the obtained organic layer was washed with saturated aqueous sodium hydrogen carbonate and then saturated brine, and dried over anhydrous magnesium sulfate. Then, the crude product obtained by filtration and concentration was purified by column chromatography (silica gel, chloroform / hexane = 1/1) to obtain 2,6-bis [5- (2-hexyldecyl) thiophene-2-. Il] -4,8-diiodobenzo [1,2-d; 4,5-d'] bistazole (DI-DBTH-HDTH) was obtained in an amount of 2.66 g as a yellow solid (yield 51%). ¹ It was confirmed by ¹ H-NMR measurement that the target compound was produced.
^{1 1} H-NMR (400 MHz, CDCl ₃ ): δ 7.53 (d, J = 3.6 Hz, 2H), 6.81 (d, J = 3.6 Hz, 2H), 2.80 (m, 4H), 1.70 (m, 2H), 1.36-1.24 (m, 48H), 0.89 (t, J = 6.4 Hz, 6H), 0.86 (t, J = 6.4 Hz, 6H).

(Synthesis Example 3)
2,6-bis [5- (2-hexyldecyl) thiophene-2-yl] -4,8-dithiophene-2-yl-benzo [1,2-d; 4,5-d'] bistiazole (DTH) -DBTH-HDTH) synthesis

In a 50 mL flask, the 2,6-bis [5- (2-hexyldecyl) thiophen-2-yl] -4,8-diiodobenzo [1,2-d; 4,5-d] obtained in Synthesis Example 2 above '] Bistiazole (DI-DBTH-HDTH, 1.1 g, 1.04 mmol), tributylthiophene-2-yl-stannan (830 μL, 2.60 mmol), tris (2-furyl) phosphine (40 mg, 0.17 mmol) ), Tris (dibenzylideneacetone) dipalladium (0) -chloroform adduct (45 mg, 0.04 mmol), and N, N-dimethylformamide (22 mL) were added and reacted at 80 ° C. for 19 hours. After completion of the reaction, the mixture was cooled to room temperature, water was added, the mixture was extracted twice with chloroform, the organic layer was washed with water, and then dried over anhydrous magnesium sulfate. Then, the crude product obtained by filtration and concentration was purified by column chromatography (silica gel, chloroform / hexane = 1/1 to chloroform) to obtain 2,6-bis [5- (2-hexyldecyl) thiophene-. 2-Il] -4,8-dithiophene-2-yl-benzo [1,2-d; 4,5-d'] Bistiazole (DTH-DBTH-HDTH) was obtained in an amount of 1.01 g as a yellow solid. (Yield 100%). ¹ It was confirmed by ¹ H-NMR measurement that the target compound was produced.
^{1 1} H-NMR (400 MHz, CDCl ₃ ): δ 8.00 (dd, J = 4.0, 0.8 Hz, 2H), 7.58 (dd, J = 5.2, 0.8 Hz, 2H), 7.55 (d, J = 4.0 Hz, 2H) ), 7.27 (dd, J = 5.2, 4.0 Hz, 2H), 6.81 (d, J = 4.0 Hz, 2H), 2.81 (m, 4H), 1.72 (m, 2H), 1.34-1.25 (m, 48H) , 0.89 (t, J = 6.4 Hz, 6H), 0.87 (t, J = 6.4 Hz, 12H).

(Synthesis Example 4)
2,6-bis [5- (2-hexyldecyl) thiophene-2-yl] -4,8-bis (5-trimethylstannylthiophene-2-yl) -benzo [1,2-d; 4,5 -D'] Synthesis of bistiazole (DTH-DBTH-HDTH-DSM)

In a 30 mL flask, the 2,6-bis [5- (2-hexyldecyl) thiophen-2-yl] -4,8-dithiophene-2-yl-benzo [1,2-d] obtained in Synthesis Example 3 above 4,5-d'] Bistiazole (DTH-DBTH-HDTH, 700 mg, 0.72 mmol) and tetrahydrofuran (14 mL) were added and cooled to -50 ° C to lithium diisopropylamide (2M solution, 0.79 mL, 1). .58 mmol) was added dropwise and the mixture was stirred for 30 minutes. Then, trimethyltin chloride (1M solution, 16 mL, 1.58 mmol) was added, the temperature was raised to room temperature, and the mixture was stirred for 2 hours. After completion of the reaction, water was added, the mixture was extracted twice with toluene, the organic layer was washed with water, and then dried over anhydrous magnesium sulfate. Then, the crude product obtained by filtration and concentration was purified by GPC-HPLC (JAIGEL-1H, 2H, chloroform) to obtain 2,6-bis [5- (2-hexyldecyl) thiophene-2-yl]. -4,8-bis (5-trimethylstannylthiophene-2-yl) -benzo [1,2-d; 4,5-d'] bistazole (DTH-DBTH-HDTH-DSM) 518 mg, yellow solid (Yield 55%). ¹ It was confirmed by ¹ H-NMR measurement that the target compound was produced.
^{1 1} H-NMR (400 MHz, CDCl ₃ ): δ 8.16 (d, J = 3.6 Hz, 2H), 7.56 (d, J = 3.6 Hz, 2H), 7.37 (d, J = 3.6 Hz, 2H), 6.82 ( d, J = 3.6 Hz, 2H), 2.82 (m, 4H), 1.71 (m, 2H), 1.35-1.25 (m, 48H), 0.88 (t, J = 6.4 Hz, 6H), 0.87 (t, J = 6.4 Hz, 6H), 0.47 (s, 18H).

(Synthesis Example 5)
Synthesis of P-THDT-DBTH-EH-IMTH

In a 20 mL flask, 2,6-bis [5- (2-hexyldecyl) thiophen-2-yl] -4,8-bis (5-trimethylstannylthiophen-2-yl) obtained in Synthesis Example 4 above. -Benzo [1,2-d; 4,5-d'] bistazole (DTH-DBTH-HDTH-DSM, 100 mg, 0.08 mmol) and 1,3-dibromo-5- (2-ethylhexyl) thieno- [3,4-c] Pyrolo-4,6-dione (EH-IMTH-DB, 33 mg, 0.08 mmol), tris (dibenzylideneacetone) dipalladium (0) -chloroform adduct (3 mg, 3 μmol), tris (2-methoxyphenyl) phosphine (5 mg, 12 μmol) and chlorobenzene (6 mL) were added and reacted at 120 ° C. for 24 hours. After completion of the reaction, the reaction solution was added to methanol (60 mL), the precipitated solid was collected by filtration, and the obtained solid was washed with Soxhlet (methanol, acetone, hexane). Then, Soxhlet extraction was performed using chloroform to obtain 85 mg of P-THDT-DBTH-EH-IMTH as a black solid (yield 90%). As a result of measuring the molecular weight of the obtained black solid using GPC, the number average molecular weight (Mn) was 25,000 and the weight average molecular weight (Mw) was 63000.

(Synthesis Example 6)
Synthesis of P-THDT-DBTH-O-IMTH

In a 20 mL flask, 2,6-bis [5- (2-hexyldecyl) thiophen-2-yl] -4,8-bis (5-trimethylstannylthiophen-2-yl) obtained in Synthesis Example 4 above. -Benzo [1,2-d; 4,5-d'] bistazole (DTH-DBTH-HDTH-DSM, 90 mg, 0.07 mmol) and 1,3-dibromo-5-octylthioeno [3,4-c ] Pyrolo-4,6-dione (O-IMTH-DB, 30 mg, 0.07 mmol), tris (dibenzylideneacetone) dipalladium (0) -chloroform adduct (3 mg, 2 μmol), tris (2-methoxyphenyl) Phosphene (4 mg, 12 μmol) and chloroform (7 mL) were added and reacted at 120 ° C. for 24 hours. After completion of the reaction, the reaction solution was added to methanol (50 mL), the precipitated solid was collected by filtration, and the obtained solid was washed with Soxhlet (methanol, acetone, hexane). Then, Soxhlet extraction was performed using chloroform to obtain 74 mg of P-THDT-DBTH-O-IMTH as a black solid (yield 87%). As a result of measuring the molecular weight of the obtained black solid using GPC, the number average molecular weight (Mn) was 7100 and the weight average molecular weight (Mw) was 15100.

(Synthesis Example 7)
Synthesis of P-THDT-DBTH-DMO-IMTH

In a 20 mL flask, 2,6-bis [5- (2-hexyldecyl) thiophen-2-yl] -4,8-bis (5-trimethylstannylthiophen-2-yl) obtained in Synthesis Example 4 above. -Benzo [1,2-d; 4,5-d'] bistazole (DTH-DBTH-HDTH-DSM, 100 mg, 0.08 mmol) and 1,3-dibromo-5- (3,7-dimethyloctyl). ) Thieno [3,4-c] pyrolo-4,6-dione (DMO-IMTH-DB, 35 mg, 0.08 mmol), tris (dibenzylideneacetone) dipalladium (0) -chloroform adduct (3 mg, 3 μmol) , Tris (2-methoxyphenyl) phosphine (4 mg, 12 μmol), and chlorobenzene (4 mL) were added and reacted at 120 ° C. for 24 hours. After completion of the reaction, the reaction solution was added to methanol (50 mL), the precipitated solid was collected by filtration, and the obtained solid was washed with Soxhlet (methanol, acetone, hexane). Then, Soxhlet extraction was performed using chloroform to obtain 80 mg of P-THDT-DBTH-DMO-IMTH as a black solid (yield 83%). As a result of measuring the molecular weight of the obtained black solid using GPC, the number average molecular weight (Mn) was 11,000 and the weight average molecular weight (Mw) was 24,000.

Next, the polymer compounds obtained in Synthesis Examples 5 to 7 were used as the p-type organic semiconductor compound to prepare a mixed solution of the p-type organic semiconductor compound and the n-type organic semiconductor compound.

<Example 1>
In Example 1, the polymer compound having the structure of P-THDT-DBTH-EH-IMTH obtained in Synthesis Example 5 was used as the p-type organic semiconductor compound, and is represented by the following formula as the n-type organic semiconductor compound. An ITIC manufactured by 1-Material Co., Ltd. was used. The mass ratio of the p-type organic semiconductor compound to the n-type organic semiconductor compound was set to p-type organic semiconductor compound: n-type organic semiconductor compound = 1: 1 and dissolved in chlorobenzene to prepare a solution. The total concentration of the p-type organic semiconductor compound and the n-type organic semiconductor compound was set to 2.4% by mass. The obtained solution was stirred and mixed on a hot stirrer at a temperature of 100 ° C. for 2 hours or more. The mixed solution 1 of the p-type organic semiconductor compound and the n-type organic semiconductor compound was prepared by filtering the solution after stirring and mixing with a 0.45 μm filter.

<Example 2>
In Example 2, as the p-type organic semiconductor compound, the polymer compound having the structure of P-THDT-DBTH-EH-IMTH obtained in Synthesis Example 5 was used, and as the n-type organic semiconductor compound, the above-mentioned Example 1 The ITIC manufactured by 1-Material and PC61BM (phenyl C61 butyric acid methyl ester) manufactured by Frontier Carbon were used. The mass ratio of the p-type organic semiconductor compound, ITIC, and PC61BM was set to p-type organic semiconductor compound: ITIC: PC61BM = 1: 1: 1 and dissolved in chlorobenzene to prepare a solution. The total concentration of the p-type organic semiconductor compound and the n-type organic semiconductor compound was set to 2.4% by mass. The obtained solution was stirred and mixed on a hot stirrer at a temperature of 100 ° C. for 2 hours or more. The mixed solution 2 of the p-type organic semiconductor compound and the n-type organic semiconductor compound was prepared by filtering the solution after stirring and mixing with a 0.45 μm filter.

<Example 3>
In Example 3, the polymer compound having the structure of P-THDT-DBTH-O-IMTH obtained in Synthesis Example 6 was used as the p-type organic semiconductor compound, and is represented by the following formula as the n-type organic semiconductor compound. 1-Material ITIC-M manufactured by Material was used. The mass ratio of the p-type organic semiconductor compound to the n-type organic semiconductor compound was set to p-type organic semiconductor compound: n-type organic semiconductor compound = 1: 1 and dissolved in chlorobenzene to prepare a solution. The total concentration of the p-type organic semiconductor compound and the n-type organic semiconductor compound was set to 2.4% by mass. The obtained solution was stirred and mixed on a hot stirrer at a temperature of 100 ° C. for 2 hours or more. The mixed solution 3 of the p-type organic semiconductor compound and the n-type organic semiconductor compound was prepared by filtering the solution after stirring and mixing with a 0.45 μm filter.

<Example 4>
In Example 4, the polymer compound having the structure of P-THDT-DBTH-O-IMTH obtained in Synthesis Example 6 was used as the p-type organic semiconductor compound, and is represented by the following formula as the n-type organic semiconductor compound. A 4TIC manufactured by 1-Material Co., Ltd. was used. The mass ratio of the p-type organic semiconductor compound to the n-type organic semiconductor compound was set to p-type organic semiconductor compound: n-type organic semiconductor compound = 1: 1 and dissolved in chlorobenzene to prepare a solution. The total concentration of the p-type organic semiconductor compound and the n-type organic semiconductor compound was set to 2.4% by mass. The obtained solution was stirred and mixed on a hot stirrer at a temperature of 100 ° C. for 2 hours or more. The mixed solution 4 of the p-type organic semiconductor compound and the n-type organic semiconductor compound was prepared by filtering the solution after stirring and mixing with a 0.45 μm filter.

<Example 5>
In Example 5, the polymer compound having the structure of P-THDT-DBTH-DMO-IMTH obtained in Synthesis Example 7 was used as the p-type organic semiconductor compound, and the n-type organic semiconductor compound was used in Example 1 above. The ITIC manufactured by 1-Material used in 1 was used. The mass ratio of the p-type organic semiconductor compound to the n-type organic semiconductor compound was set to p-type organic semiconductor compound: n-type organic semiconductor compound = 1: 1 and dissolved in chlorobenzene to prepare a solution. The total concentration of the p-type organic semiconductor compound and the n-type organic semiconductor compound was set to 2.4% by mass. The obtained solution was stirred and mixed on a hot stirrer at a temperature of 100 ° C. for 2 hours or more. The mixed solution 5 of the p-type organic semiconductor compound and the n-type organic semiconductor compound was prepared by filtering the solution after stirring and mixing with a 0.45 μm filter.

<Example 6>
In Example 6, a polymer compound having the structure of P-THDT-DBTH-DMO-IMTH obtained in Synthesis Example 7 was used as the p-type organic semiconductor compound, and Example 1 was used as the n-type organic semiconductor compound. The ITIC manufactured by 1-Material and PC71BM (phenylC71 butyrate methyl ester) manufactured by Frontier Carbon Co., Ltd. used in the above were used. The mass ratio of the p-type organic semiconductor compound, ITIC, and PC71BM was set to p-type organic semiconductor compound: ITIC: PC71BM = 2: 1: 1 and dissolved in chlorobenzene to prepare a solution. The total concentration of the p-type organic semiconductor compound and the n-type organic semiconductor compound was set to 2.4% by mass. The obtained solution was stirred and mixed on a hot stirrer at a temperature of 100 ° C. for 2 hours or more. The mixed solution 6 of the p-type organic semiconductor compound and the n-type organic semiconductor compound was prepared by filtering the solution after stirring and mixing with a 0.45 μm filter.

Next, a photoelectric conversion element was prepared using the mixed solutions obtained in Examples 1 to 6, and evaluated by the following procedure.

(Manufacturing of photoelectric conversion element)
A glass substrate manufactured by Geomatec, in which an electrode, an indium tin oxide (ITO) transparent conductive film (cathode), was patterned, was ultrasonically cleaned with acetone, then ultrasonically cleaned with ethanol, and then dried with a nitrogen blow. After UV-ozone treatment was performed on the dried glass substrate, an electron transport layer was formed. The electron transport layer was formed by applying a 0.5 M zinc acetate / 0.5 M aminoethanol / 2-methoxyethanol solution to a glass substrate with a spin coater (3000 rpm, 40 seconds) and then annealing at 175 ° C. for 30 minutes. .. The glass substrate on which the electron transport layer is formed is carried into the glove box, and a mixed solution 1 to 6 of the p-type organic semiconductor compound and the n-type organic semiconductor compound is spin-coated in an inert gas atmosphere and annealed on a hot plate. The process was carried out. The annealing treatment was carried out at 110 ° C. for 15 minutes. Next, molybdenum oxide, which is a hole transport layer, was deposited with a thin-film deposition machine. Then, silver, which is an electrode (anode), was vapor-deposited to produce a photoelectric conversion element, which is an inverted configuration device. For the obtained inverted configuration device, the photoelectric conversion element was evaluated using a solar simulator according to the following procedure.

(Evaluation method of photoelectric conversion element)
A 0.05027 mm square metal mask is attached to the photoelectric conversion element, and a solar simulator (OTENTO-SUNIII, AM1.5G filter, radiant intensity 100 mW / cm ² , manufactured by a spectroscope) is used as an irradiation light source, and a source meter (manufactured by Keithley Co., Ltd.) The current-voltage characteristic between the ITO electrode and the silver electrode was measured by the 2400 type). From this measurement result, the short-circuit current density Jsc (mA / cm ² ), the open circuit voltage Voc (V), the curve factor FF, and the energy conversion efficiency PCE (%) were calculated. The short-circuit current density Jsc is the current density when the voltage value is 0V. The open circuit voltage Voc is a voltage value when the current value is 0 mA / cm ² . The curve factor FF is a factor representing the internal resistance, and is expressed by the following equation where the maximum output is Pmax.
FF = Pmax / (Jsc × Voc)
The energy conversion efficiency PCE is given by the following equation, where the incident energy is Pin.
PCE = (Pmax / Pin) x 100 = (Jsc x Voc x FF / Pin) x 100

The photoelectric conversion element of the present invention has a high short-circuit current density (Jsc) and an open circuit voltage (Voc), and has a high energy conversion efficiency PCE. Further, it can be seen that the energy conversion efficiency PCE is larger when the aromatic compound (2) is used as the n-type organic semiconductor compound.

I, II Photoelectric conversion element A Anode H Hall transport layer X Active layer E Electron transport layer C Cathode B Base material

Claims

A photoelectric conversion element having a structure in which a cathode, an active layer, and an anode are arranged in this order.
The active layer is
A polymer compound having a benzobisthiazole structural unit represented by the following formula (1) and
A photoelectric conversion element containing an aromatic compound represented by the following formula (2) and / or an aromatic compound represented by the following formula (3).

[In formula (1), whether T 1 and T 2 are independently alkoxy groups, thioalkoxy groups, or thiophene rings that may be substituted with a hydrocarbon group or an organosilyl group. , A thiazole ring optionally substituted with a hydrocarbon group or an organosilyl group, or even if substituted with a hydrocarbon group, an organosilyl group, an alkoxy group, an thioalkoxy group, a trifluoromethyl group, or a halogen atom. Represents a good phenyl group.
Further, B 1 and B 2 each independently represent a thiophene ring which may be substituted with a hydrocarbon group, a thiazole ring which may be substituted with a hydrocarbon group, or an ethynylene group. .. ]

[In formula (2), R 101 to R 116 are independently hydrogen atoms, alkyl groups, alkoxy groups, thioalkoxy groups, fluorine atoms, or alkyl. Represents a benzene ring that may be substituted with a group, alkoxy group, thioalkoxy group, or fluorine atom, or a thiophene ring that may be substituted with an alkyl group, alkoxy group, thioalkoxy group, or fluorine atom. ]

[In formula (3), R 201 to R 214 are independently hydrogen atoms, alkyl groups, alkoxy groups, thioalkoxy groups, fluorine atoms, or alkyl. Represents a benzene ring that may be substituted with a group, alkoxy group, thioalkoxy group, or fluorine atom, or a thiophene ring that may be substituted with an alkyl group, alkoxy group, thioalkoxy group, or fluorine atom. ]
The photoelectric conversion element according to claim 1 , wherein T 1 and T 2 are independently represented by any of the following formulas (t1) to (t5).

Wherein (t1) ~ formula (t5), R 13, R 14 each independently represent a hydrocarbon group having 6 to 30 carbon atoms.
R 15 and R 16 each independently represent a hydrocarbon group having 6 to 30 carbon atoms or a group represented by * -Si (R 18 ) 3 .
Each of R 17 independently contains a hydrocarbon group having 6 to 30 carbon atoms, * -Si (R 18 ) 3 , * -OR 19 , * -SR 20 , * -CF 3 , or a halogen atom. Represent.
n1 represents an integer of 1 to 3, n2 represents an integer of 1 or 2, n3 represents an integer of 1 to 5, and a plurality of R 15s may be the same or different, and a plurality of R 16s may be the same or different. , Multiple R 17s may be the same or different.
Each of R 18 independently represents an aliphatic hydrocarbon group having 1 to 20 carbon atoms or an aromatic hydrocarbon group having 6 to 10 carbon atoms, and a plurality of R 18s may be the same or different.
R 19 and R 20 each independently represent a hydrocarbon group having 6 to 30 carbon atoms.
* Represents a bond. ]
The photoelectric conversion element according to claim 1 or 2, wherein B 1 and B 2 are independently represented by any of the following formulas (b1) to (b3).

[In formulas (b1) to (b3), R 21 and R 22 each independently represent a hydrocarbon group having 6 to 30 carbon atoms.
n4 represents an integer of 0 to 2, n5 represents 0 or 1, and a plurality of R 21s may be the same or different.
* Represents a bond, and * on the left represents a bond that binds to the benzene ring of the benzobisthiazole structural unit. ]
The photoelectric conversion element according to any one of claims 1 to 3, wherein the polymer compound containing the benzobisthiazole structural unit represented by the formula (1) is a donor-acceptor type semiconductor polymer compound.
The photoelectric conversion element according to any one of claims 1 to 4, which has an electron transport layer between the cathode and the active layer.
The photoelectric conversion element according to any one of claims 1 to 5, which has a hole transport layer between the anode and the active layer.
The photoelectric conversion element according to any one of claims 1 to 6, wherein a base material is arranged on one side of the cathode and the active layer is arranged on the other side of the cathode.
The photoelectric conversion element according to any one of claims 1 to 6, wherein a base material is arranged on one side of the anode and the active layer is arranged on the other side of the anode.
An organic thin-film solar cell including the photoelectric conversion element according to any one of claims 1 to 8.