JP6696432B2 - Photoelectric conversion element and organic semiconductor compound used therein - Google Patents

Description

  The present invention provides a photoelectric conversion device having a structure in which a base material, a cathode, an active layer, and an anode are arranged in this order, and a photoelectric conversion containing a polymer compound having a specific benzobisthiazole skeleton structural unit. Regarding the device.

  The organic semiconductor compound is one of the most important materials in the field of organic electronics, and can be classified into an electron-donating p-type organic semiconductor compound and an electron-accepting n-type organic semiconductor compound. Various devices can be manufactured by appropriately combining a p-type organic semiconductor compound and an n-type organic semiconductor compound, and such a device includes, for example, excitons formed by recombination of electrons and holes ( It is applied to organic electroluminescence that emits light by the action of excitons, organic thin-film solar cells that convert light into electric power, and organic thin film transistors that control the amount of current and the amount of voltage.

  Among these, organic thin-film solar cells are useful for environmental protection because they do not release carbon dioxide into the atmosphere, and because they have a simple structure and are easy to manufacture, demand for them is increasing. However, the photoelectric conversion efficiency of organic thin-film solar cells is still insufficient. The photoelectric conversion efficiency η is calculated by the product of the short circuit current density (Jsc), the open circuit voltage (Voc) and the fill factor (FF) “η = open circuit voltage (Voc) × short circuit current density (Jsc) × fill factor (FF)”. In order to increase the photoelectric conversion efficiency, it is necessary to improve not only the open circuit voltage (Voc) but also the short circuit current density (Jsc) and the fill factor (FF).

  The open circuit voltage (Voc) is proportional to the energy difference between the HOMO (highest occupied molecular orbital) level of the p-type organic semiconductor compound and the LUMO (lowest unoccupied molecular orbital) level of the n-type organic semiconductor compound. In order to improve (Voc), it is necessary to deepen (lower) the HOMO level of the p-type organic semiconductor.

  The short-circuit current density (Jsc) correlates with the amount of energy received by the organic semiconductor compound, and in order to improve the short-circuit current density (Jsc) of the organic semiconductor compound, the visible region to the near-infrared region is increased. It is necessary to absorb light in a wide wavelength range. Of the light that can be absorbed by the organic semiconductor compound, the wavelength of the light with the lowest energy (longest wavelength) is the absorption edge wavelength, and the energy corresponding to this wavelength corresponds to the bandgap energy. Therefore, in order to absorb light in a wider wavelength range, it is necessary to narrow the band gap (energy difference between HOMO level and LUMO level of p-type semiconductor).

On the other hand, research on p-type organic semiconductor compounds has also been actively conducted. For example, in Non-Patent Document 1, a copolymerization of 4,4′-bis (2-ethylhexyl) dithieno [3,2-b; 2 ′, 3 ′,-d] silole and 2,1,3-benzothiadiazole is described. Coalescing is proposed. However, the p-type organic semiconductor compound described in Non-Patent Document 1 may not have a sufficiently deep HOMO level in some cases. Non-Patent Document 2 proposes a p-type organic semiconductor compound having a benzodithiophene skeleton. However, in the p-type organic semiconductor compound described in Non-Patent Document 2, the skeleton and substituents that can be introduced are limited due to problems in the synthesis method.
Further, Patent Documents 1 and 2 propose compounds each having a benzobisthiazole skeleton, but the conversion efficiency is not clear.

JP, 2007-238530, A JP, 2010-053093, A

Jianhui Hou, 4 others, "Synthesis, Characterization, and Photovoltaic Properties of a Low Band Gap Polymer Based on Silole-Containing Polythiophenes and 2,1,3-Benzothiadiazole" Journal of the American Chemical Society, 2008, 130, 16144-16145 . Latian Dou, 8 others, "Systematic Investigation of Benzodithiophene- and Diketopyrrolopyrrole-Based Low-Bandgap Polymers Designed for Single Junction and Tandem Polymer Solar Cells," Journal of the American Chemical Society, 2012, 134, 10071-10079. Eiichiro Fukuchi, et al., "Evaluation using reverse organic thin-film solar cells using low band gap polymer PCBBT and characteristic change due to oxidation", Solar Energy, 2012, 38, 53-58.

  An object of the present invention is to provide a photoelectric conversion element that exhibits a high open circuit voltage. In addition, the capability of the photoelectric conversion element depends on the type and combination of organic semiconductor compounds, the configuration of the photoelectric conversion element, and the like. In the organic semiconductor compound, HOMO and open circuit voltage are closely related to each other. Another object of the present invention is to provide a photoelectric conversion element using a polymer compound capable of introducing a substituent. In recent years, as shown in Non-Patent Document 3, attention is focused on an inverted-type constituent element having an electrode (cathode) for collecting electrons on the base material side due to its high stability, and it is also necessary to examine the element configuration. ..

  In order to manufacture a photoelectric conversion device having high conversion efficiency, that is, to improve short circuit current density (Jsc) while improving open circuit voltage (Voc), the present inventors have proposed p-type organic semiconductor compounds with a wide wavelength range. It was found that the HOMO level is made moderately deep while absorbing light in the range. Then, an intensive study was conducted focusing on the correlation between the HOMO level and the chemical structure in the p-type organic semiconductor compound. As a result, the HOMO level or the LUMO level can be adjusted to an appropriate range by examining the device structure using an organic semiconductor compound having a polymer compound having a specific structure, so that the photoelectric conversion with a high open circuit voltage (Voc) is possible. The inventors have found that a conversion element can be produced and completed the present invention.

That is, the present invention is a photoelectric conversion device having a structure in which a base material, a cathode, an active layer, and an anode are arranged in this order, and the active layer contains a specific benzo compound represented by the formula (1). It is characterized by containing a polymer compound having a structural unit of a bisthiazole skeleton (hereinafter sometimes referred to as "polymer compound (1)").

[In Formula (1),
A ¹ and A ² are each independently an alkoxy group, a thioalkoxy group, a thiophene ring optionally substituted with a hydrocarbon group, a thiazole ring optionally substituted with a hydrocarbon group or an organosilyl group, or It represents a phenyl group which may be substituted with a hydrocarbon group, an alkoxy group, a thioalkoxy group, an organosilyl group, a halogen atom, or a trifluoromethyl group. ]
In the above formula (1), it is preferable that each of A ¹ and A ² is a group represented by the following formula.

[In the formulas (a1) to (a5), R ^{21 to} R ²³ and R ^{25 to} R ²⁶ each independently represent a hydrocarbon group having 8 to 30 carbon atoms. R ²⁴ represents a hydrogen atom or a hydrocarbon group having 8 to 30 carbon atoms. * Represents a bond that bonds to the benzene ring of benzobisthiazole. ]

  The polymer compound (1) used in the photoelectric conversion device of the present invention is preferably a donor-acceptor type semiconductor polymer.

  The active layer preferably further contains an n-type organic semiconductor compound, and the n-type semiconductor compound is preferably fullerene or a derivative thereof.

  The photoelectric conversion element of the present invention preferably has an electron transport layer between the cathode and the active layer, and preferably has a hole transport layer between the anode and the active layer. Further, the cathode is preferably a transparent electrode, and the anode is preferably a metal electrode.

  The polymer compound (1) used in the present invention has a deep HOMO level and can absorb a wide range of light from the visible region to the near infrared region. As a result, the photoelectric conversion element having the element structure shown in FIG. 1 can obtain a high open circuit voltage (Voc) and a high photoelectric conversion efficiency η. Further, various substituents can be introduced as a substituent into the benzobisthiazole skeleton constituting the polymer compound (1) used in the present invention, and a material having various influences on photoelectric conversion element characteristics. Characteristics (crystallinity, film-forming property, absorption wavelength) can be controlled. As an element structure, an inverted type element that collects electrons on the substrate side can be manufactured.

FIG. 1 shows an element structure of a photoelectric conversion element in which a base material, a cathode, an active layer, and an anode are arranged in this order.

  Embodiments of the present invention will be described in detail below. 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 unless the gist thereof is exceeded.

Photoelectric conversion element The photoelectric conversion element according to the present invention is a photoelectric conversion element having a structure in which a base material, a cathode, an active layer, and an anode are arranged in this order, and the active layer has the formula (1). A polymer compound having a benzobisthiazole structural unit represented by

  A photoelectric conversion element (VII) according to one embodiment of the present invention is shown in FIG. 1 shows a photoelectric conversion element used in a general organic thin-film solar cell, the photoelectric conversion element according to the present invention is not limited to the configuration shown in FIG.

  The photoelectric conversion element (VII) has a structure in which a base material (I), an electrode (cathode) (II), an active layer (IV), and an electrode (anode) (VI) are arranged in this order. The photoelectric conversion element (VII) preferably further has a buffer layer (electron transport layer) (III) and a buffer layer (hole transport layer) (V). That is, the photoelectric conversion element (VII) includes a base material (I), a cathode (II), a buffer layer (electron transport layer) (III), an active layer (IV), a buffer layer (hole transport layer) (V). ) And the anode (VI) are preferably arranged in this order. However, the photoelectric conversion element according to the present invention may not have the electron transport layer (III) and the hole transport layer (V). Each of these parts will be described below.

<1.1 Active layer (IV)>
The active layer (IV) refers to a layer in which photoelectric conversion is performed, and usually contains one or more p-type semiconductor compounds and one or more n-type semiconductor compounds. Specific examples of the p-type semiconductor compound include, but are not limited to, the polymer compound (1) and the organic semiconductor compound (10) described later. In the present invention, it is necessary to use at least the polymer compound (1) as the p-type semiconductor compound. When the photoelectric conversion element (VII) receives light, the light is absorbed by the active layer (IV), and electricity is generated at the interface between the p-type semiconductor compound and the n-type semiconductor compound, and the generated electricity is generated by the cathode (II) and It is taken out from the anode (VI). In the present invention, the polymer compound (1) is used as a p-type semiconductor compound.

  The thickness of the active layer (IV) is not particularly limited, but is preferably 70 nm or more, more preferably 90 nm or more, and may be 100 nm or more. On the other hand, the thickness of the active layer (IV) is preferably 1000 nm or less, more preferably 750 nm or less, and further preferably 500 nm or less.

  When the film thickness of the active layer (IV) is 70 nm or more, improvement in conversion efficiency of the photoelectric conversion element (VII) can be expected. In addition, it is preferable that the thickness of the active layer (IV) is 70 nm or more in terms of preventing a through short circuit in the film. It is preferable that the thickness of the active layer (IV) is 1000 nm or less because the internal resistance becomes small, and the distance between the electrodes (II) and (VI) is not too large, so that the diffusion of charges becomes good. Furthermore, it is preferable that the film thickness of the active layer (IV) is 70 nm or more and 1000 nm or less, because the reproducibility in the process of manufacturing the active layer (IV) is improved.

Generally, the thicker the active layer is, the longer the migration distance of the charges generated in the active layer to the electrode or the electron transporting layer or the hole transporting layer is. Therefore, the transport of the charges to the electrode is hindered. Be done. As described above, when the active layer (IV) is thick, the region capable of absorbing light increases, but it is difficult to transport the charge generated by light absorption, and thus the photoelectric conversion efficiency decreases.
Therefore, it is preferable to set the film thickness of the active layer (IV) to 70 nm or more and 500 nm or less from the viewpoint of ensuring voltage and improving conversion efficiency.

[1.1.1 Layer structure of active layer]
The layer structure of the active layer (IV) is a thin film laminated type in which a p-type semiconductor compound and an n-type semiconductor compound are laminated, or a bulk heterojunction type having a layer in which a p-type semiconductor compound and an n-type semiconductor compound are mixed. Is mentioned. Among them, the bulk heterojunction type active layer is preferable because the photoelectric conversion efficiency can be further improved.

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

  Of the p-type semiconductor compound contained in the i-layer, usually 50% by weight or more, preferably 70% by weight or more, more preferably 90% by weight or more is the benzobisthiazole structural unit represented by the formula (1) and Is a polymer compound (1) comprising a copolymerization component (2). Since the polymer compound (1) has suitable properties as a p-type semiconductor compound, it is particularly preferable that the p-type semiconductor compound contains only the polymer compound (1).

  The weight ratio of the p-type semiconductor compound and the n-type semiconductor compound in the i layer (p-type semiconductor compound / n-type semiconductor compound) is 0 from the viewpoint of improving the photoelectric conversion efficiency by obtaining a good phase separation structure. It is preferably 0.5 or more, more preferably 1 or more, while preferably 4 or less, more preferably 3 or less, and particularly preferably 2 or less.

  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. Since the polymer compound (1) according to the present invention has solubility in a solvent, it is preferable in that it is excellent in coating film formation. When the i layer is formed by a coating method, a coating solution containing a p-type semiconductor compound and an n-type semiconductor compound may be prepared and the coating solution may be applied. The coating liquid containing the p-type semiconductor compound and the n-type semiconductor compound may be prepared by mixing a solution containing the p-type semiconductor compound and a solution containing the n-type semiconductor compound after preparation, and a p-type semiconductor in a solvent described below. It may be prepared by dissolving the compound and the n-type semiconductor compound.

  The total concentration of the p-type semiconductor compound and the n-type semiconductor compound in the coating solution is not particularly limited, but is 1.0% by weight or more based on the entire coating solution from the viewpoint of forming an active layer having a sufficient film thickness. From the viewpoint of sufficiently dissolving the semiconductor compound, it is preferably 4.0% by weight or less based on the whole coating liquid.

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

  The solvent of the coating liquid is not particularly limited as long as it can dissolve the p-type semiconductor compound and the n-type semiconductor compound uniformly, but for example, aliphatic hydrocarbons such as hexane, heptane, octane, isooctane, nonane or decane. Aromatic hydrocarbons such as toluene, xylene, mesitylene, cyclohexylbenzene, chlorobenzene or orthodichlorobenzene; cycloaliphatic hydrocarbons such as cyclopentane, cyclohexane, methylcyclohexane, cycloheptane, cyclooctane, tetralin or decalin; methanol , Lower alcohols such as ethanol or propanol; aliphatic ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone (MIBK), cyclopentanone or cyclohexanone; acetophenone Is an aromatic ketone such as propiophenone; an ester such as ethyl acetate, isopropyl acetate, butyl acetate or methyl lactate; a halogenated hydrocarbon such as chloroform, methylene chloride, dichloroethane, trichloroethane or trichloroethylene; ethyl ether, tetrahydrofuran, cyclopentyl Examples thereof include ethers such as methyl ether and dioxane; and amides such as dimethylformamide and dimethylacetamide.

  Among them, preferably, aromatic hydrocarbons such as toluene, xylene, mesitylene, cyclohexylbenzene, chlorobenzene or orthodichlorobenzene; alicyclic carbons such as cyclopentane, cyclohexane, methylcyclohexane, cycloheptane, cyclooctane, tetralin or decalin. Hydrogens; ketones such as acetone, methyl ethyl ketone, cyclopentanone or cyclohexanone; or ethers such as ethyl ether, tetrahydrofuran or dioxane.

  When the bulk heterojunction type active layer is formed by a coating method, an additive may be further added to the coating liquid containing the p-type semiconductor compound and the n-type semiconductor compound. The phase separation structure of the p-type semiconductor compound and the n-type semiconductor compound in the bulk heterojunction type active layer has an influence on the light absorption process, the exciton diffusion process, the exciton dissociation (carrier separation) process, the carrier transport process, and the like. is there. Therefore, it is considered that good photoelectric conversion efficiency can be realized by optimizing the phase separation structure. By containing an additive having a high affinity for the p-type semiconductor compound or the n-type semiconductor compound in the coating liquid, an active layer having a preferable phase separation structure can be obtained and the photoelectric conversion efficiency can be improved.

  The additive is preferably solid or has a high boiling point in that the additive is less likely to be lost from the active layer (IV).

  Specifically, when the additive is solid, the melting point (1 atm) of the additive is usually 35 ° C. or higher, preferably 50 ° C. or higher, more preferably 80 ° C. or higher, still more preferably 150 ° C. or higher. And particularly preferably 200 ° C. or higher.

  When the additive is a liquid, the boiling point (1 atm) is 80 ° C or higher, more preferably 100 ° C or higher, and particularly preferably 150 ° C or higher.

  Examples of the additive include aliphatic hydrocarbons having 10 or more carbon atoms or aromatic compounds as long as they are solid. A specific example is a naphthalene compound, and a compound in which 1 to 8 substituents are bonded to naphthalene is particularly preferable. As the substituent bonded to naphthalene, a halogen atom, a hydroxyl group, a cyano group, an amino group, an amide group, a carbonyloxy group, a carboxyl group, a carbonyl group, an oxycarbonyl group, a silyl group, an alkenyl group, an alkynyl group, an alkoxy group. , An aryloxy group, an alkylthio group, an arylthio group or an aromatic group.

  If the additive is a liquid, aliphatic hydrocarbons having 8 or more carbon atoms, aromatic compounds and the like can be mentioned. Specific examples thereof include a dihalogenated hydrocarbon compound, and a compound in which octane is bonded with 1 to 8 substituents is particularly preferable. Examples of the substituent bonded to octane include a halogen atom, a hydroxyl group, a thiol group, a cyano group, an amino group, an amide group, a carbonyloxy group, a carboxyl group, a carbonyl group, or an aromatic group. Another example of the additive is a benzene compound having 4 or more and 6 or less halogen atoms bonded thereto.

  The amount of the additive contained in the coating liquid containing the p-type semiconductor compound and the n-type semiconductor compound is preferably 0.1% by weight or more, and more preferably 0.5% by weight or more, based on the entire coating liquid. Further, it is preferably 10% by weight or less, more preferably 5% by weight or less, based on the whole coating liquid. When the amount of the additive is within this range, a preferable phase separation structure can be obtained.

[1.1.2 p-type semiconductor compound]
The active layer (IV) contains at least the polymer compound (1) as a p-type semiconductor compound.

(Polymer compound (1))
The polymer compound used in the photoelectric conversion device of the present invention (hereinafter sometimes referred to as “polymer compound (1)”) is one type of p-type semiconductor compound, and is a benzo compound represented by the formula (1). It has a bisthiazole structural unit (hereinafter sometimes referred to as “structural unit represented by the formula (1)”).

[In Formula (1),
A ¹ and A ² are each independently an alkoxy group, a thioalkoxy group, a thiophene ring optionally substituted with a hydrocarbon group, a thiazole ring optionally substituted with a hydrocarbon group or an organosilyl group, or It represents a phenyl group which may be substituted with a hydrocarbon group, an alkoxy group, a thioalkoxy group, an organosilyl group, a halogen atom, or a trifluoromethyl group. ]

  The polymer compound used in the photoelectric conversion element of the present invention has a benzobisthiazole structural unit represented by the formula (1). Therefore, the band gap can be narrowed while the HOMO level is deepened, which is advantageous in increasing the photoelectric conversion efficiency. The polymer compound (1) is preferably a donor-acceptor type semiconductor polymer obtained by copolymerizing the structural unit represented by the formula (1) and a copolymerization component (2) described below. The donor-acceptor type semiconducting polymer means a polymer compound in which donor units and acceptor units are alternately arranged. The donor unit means an electron-donating structural unit, and the acceptor unit means an electron-accepting structural unit. The donor-acceptor type semiconductor polymer is preferably a polymer compound in which a structural unit represented by the formula (1) and a copolymerization component (2) described later are alternately arranged. With such a structure, it can be suitably used as a p-type semiconductor compound.

In the benzobisthiazole structural unit represented by the formula (1), A ¹ and A ² may be the same or different from each other, but from the viewpoint of easy production, it is preferable that they are the same.
In the benzobisthiazole structural unit represented by the formula (1), A ¹ and A ² are preferably groups represented by the following formulas (a1) to (a5). When A ¹ and A ² are groups represented by the following formulas (a1) to (a5), light having a short wavelength can be absorbed, and thus the photoelectric conversion efficiency can be further enhanced.

[In formulas (a1) to (a5), R ^{21 to} R ²³ and R ^{25 to} R ²⁶ each independently represent a hydrocarbon group having 8 to 30 carbon atoms. R ²⁴ represents a hydrogen atom or a hydrocarbon group having 8 to 30 carbon atoms. * Represents a bond that bonds to the benzene ring of benzobisthiazole. ]

R ²⁴ is preferably a hydrocarbon group having 8 to 30 carbon atoms.
The hydrocarbon group having 8 to 30 carbon atoms of R ^{21 to} R ²⁶ is preferably a branched hydrocarbon group, and more preferably a branched chain saturated hydrocarbon group. Since the hydrocarbon group of R ^{21 to} R ²⁶ has a branch, the solubility in an organic solvent can be increased and appropriate crystallinity can be obtained. The larger the carbon number of the hydrocarbon group of A ¹ and A ² is, the more the solubility in the organic solvent can be improved. The synthesis of 1) may be difficult. Therefore, the number of carbon atoms of the hydrocarbon group of A ¹ and A ² is preferably 8 to 25, more preferably 8 to 20, and further preferably 8 to 16.

Examples of the hydrocarbon group having 8 to 30 carbon atoms represented by R ^{21 to} R ²⁶ include n-octyl group, 1-n-butylbutyl group, 1-n-propylpentyl group, 1-ethylhexyl group, 2- Such as ethylhexyl group, 3-ethylhexyl group, 4-ethylhexyl group, 1-methylheptyl group, 2-methylheptyl group, 6-methylheptyl group, 2,4,4-trimethylpentyl group and 2,5-dimethylhexyl group. C8 alkyl group; n-nonyl group, 1-n-propylhexyl group, 2-n-propylhexyl group, 1-ethylheptyl group, 2-ethylheptyl group, 1-methyloctyl group, 2-methyloctyl group Group, 6-methyloctyl group, 2,3,3,4-tetramethylpentyl group, 3,5,5-trimethylhexyl group, and other alkyl groups having 9 carbon atoms; n-decyl group, 1-n-pentylpentyl group Group, 1-n-butylhexyl group, 2-n-butylhexyl group, 1-n-propylheptyl group, 1-ethyloctyl group, 2-ethyloctyl group, 1-methylnonyl group, 2-methylnonyl group, 3, Alkyl group having 10 carbon atoms such as 7-dimethyloctyl group; n-undecyl group, 1-n-butylheptyl group, 2-n-butylheptyl group, 1-n-propyloctyl group, 2-n-propyloctyl group An alkyl group having 11 carbon atoms such as 1-ethylnonyl group and 2-ethylnonyl group; n-dodecyl group, 1-n-pentylheptyl group, 2-n-pentylheptyl group, 1-n-butyloctyl group, 2- C12 alkyl group such as n-butyloctyl group, 1-n-propylnonyl group, 2-n-propylnonyl group; n-tridecyl group, 1-n-pentyloctyl group, 2-n-pentyloctyl group , 1-n-butylnonyl group, 2-n-butylnonyl group, 1-methyldecyl group, 2-methyldecyl group and the like having 13 carbon atoms; n-tetradecyl group, 1-n-heptylheptyl group, 1-n- Alkyl group having 14 carbon atoms such as hexyloctyl group, 2-n-hexyloctyl group, 1-n-pentylnonyl group, 2-n-pentylnonyl group; n-pentadecyl group, 1-n-heptyloctyl group, 1 An alkyl group having 15 carbon atoms such as -n-hexylnonyl group and 2-n-hexylnonyl group; n-hexadecyl group, 1-n-octyloctyl group, 1-n-heptylnonyl group, 2-n-heptylnonyl group, Alkyl group having 16 carbon atoms such as 2-n-hexyldecyl group; n-heptadecyl group, 1-n-octylno C17 alkyl group such as nyl group; C18 alkyl group such as n-octadecyl group and 1-n-nonylnonyl group; C19 alkyl group such as n-nonadecyl group; n-eicosyl group, n An alkyl group having 20 carbon atoms such as octyldodecyl group; an alkyl group having 21 carbon atoms such as n-heneicosyl group; an alkyl group having 22 carbon atoms such as n-docosyl group; an alkyl group having 23 carbon atoms such as n-tricosyl group Group; an alkyl group having 24 carbon atoms such as an n-tetracosyl group and a 2-decyltetradecyl group; and the like. It is preferably an alkyl group having 8 to 20 carbon atoms, more preferably an alkyl group having 8 to 16 carbon atoms, further preferably a branched chain alkyl group having 8 to 16 carbon atoms, particularly preferably n-octyl. Group, 2-ethylhexyl group, 3,7-dimethyloctyl group, 2-n-butyloctyl, 2-n-hexyldecyl group. It is preferable that R ^{21 to} R ²⁵ are the above groups because the solubility of the polymer compound (1) in the organic solvent is improved and the polymer compound (1) has appropriate crystallinity.

In the benzobisthiazole structural unit represented by the formula (1), A ¹ and A ² are each independently an alkoxy group, a thioalkoxy group, a thiophene ring which may be substituted with a hydrocarbon group, a hydrocarbon group or A thiazole ring which may be substituted with an organosilyl group, or a phenyl group which may be substituted with a hydrocarbon group, an alkoxy group, a thioalkoxy group, an organosilyl group, a halogen atom or a trifluoromethyl group. Preferably. In particular, when the groups A ¹ and A ² are groups represented by the following formulas (a1) to (a5), the structural unit represented by the formula (1) has high planarity, so that Since π-π stacking is formed, the conversion efficiency can be further improved, which is more preferable.

Wherein (a1) ~ (a5), * represents a ^{bond, R 21 ~R 23, R 25} ~R 26 independently represent a hydrocarbon group having 8 to 30 carbon atoms. R ²⁴ represents a hydrogen atom or a hydrocarbon group having 8 to 30 carbon atoms. * Represents a bond that bonds to the benzene ring of benzobisthiazole. ]

A ¹ and A ² are more preferably a group represented by the formula (a1) or (a3) from the viewpoint of excellent planarity as a whole structural unit represented by the formula (1), and a group represented by the formula (a1-1) To (a1-5) and (3-1) to (3-10) are more preferred, and formulas (a1-1) to (a1-3) and (a3-1) to (a3-6) are preferred. The group represented by) is particularly preferable. In the formula, * represents a bond that bonds to the benzene ring of benzobisthiazole.

  Examples of the structural unit represented by the formula (1) include groups represented by the following formula.

(Copolymerization component (2))
The polymer compound (1) used in the present invention preferably contains the copolymerization component (2) in combination with the structural unit represented by the formula (1). The copolymerization component (2) can use a conventionally known structural unit as a structural unit (donor unit, acceptor unit) forming a donor-acceptor type semiconductor polymer. Although not particularly limited, specific examples thereof include the following structural units, which may be used alone or in combination of two or more kinds.

[In the formulas (b1) to (b28), R ^{30 to} R ⁵⁸ each independently represent a group similar to the hydrocarbon group having 8 to 30 carbon atoms of R ^{21 to} R ²⁶ , and A ³⁰ and A ³¹ are , Each independently represent the same group as A ¹ and A ^2, and j represents an integer of 1 to 4. The symbol ● represents a bond to be bonded to the thiazole ring of the structural unit represented by the formula (1). ]

The groups represented by the formulas (b1) to (b15) are groups that act as acceptor units, and the groups represented by the formulas (b17) to (b28) are groups that act as donor units. Is. The group represented by the formula (b16) may act as an acceptor unit or a donor unit depending on the types of A ³⁰ and A ³¹ .

  The repeating ratio of the structural unit represented by the formula (1) in the polymer compound (1) used in the present invention is not particularly limited, but is usually 1 mol% or more, preferably 5 mol% or more, more preferably It is 15 mol% or more, more preferably 30 mol% or more. On the other hand, it is usually 99 mol% or less, preferably 95 mol% or less, more preferably 85 mol% or less, and further preferably 70 mol% or less.

  The ratio of the repeating unit of the copolymerization component (2) in the polymer compound (1) is not particularly limited, but is usually 1 mol% or more, preferably 5 mol% or more, more preferably 15 mol% or more, It is preferably 30 mol% or more. On the other hand, it is usually 99 mol% or less, preferably 95 mol% or less, more preferably 85 mol% or less, and further preferably 70 mol% or less.

  In the polymer compound (1) according to the present invention, the arrangement state of the structural unit represented by the formula (1) of the repeating unit and the copolymerization component (2) may be alternating, block or random. That is, the polymer compound (1) according to the present invention may be any of an alternating copolymer, a block copolymer and a random copolymer. Preferably, they are arranged alternately.

  In the polymer compound (1), the structural unit represented by the formula (1) and the copolymerization component (2) may each contain only one kind. Further, the structural unit represented by the formula (1) may be contained in two or more kinds, and the copolymerization component (2) may be contained in two or more kinds. The types of the structural unit represented by the formula (1) and the copolymerization component (2) are not limited, but are usually 8 or less, preferably 5 or less. Particularly preferred is a polymer compound (1) containing alternately one type of constitutional unit represented by the formula (1) and one type of the copolymerization component (2), and most preferably the formula (1). ) Is a polymer compound (1) alternately containing only one type of structural unit represented by the formula (1) and only one type of copolymerization component (2).

Preferred specific examples of the polymer compound (1) are shown below. However, the polymer compound (1) according to the present invention is not limited to the following examples. In the following ^{embodiment, R} 30 to R ⁴⁹ is n- octyl, 2-ethylhexyl, 3,7-dimethyl octyl group, 2-n- butyl-octyl, represents a 2-n- hexyl-decyl 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) used in the present invention has absorption in a long wavelength region (600 nm or more). Moreover, the photoelectric conversion element using the polymer compound (1) exhibits a high open circuit voltage (Voc) and exhibits high photoelectric conversion characteristics. When the polymer compound (1) is used as a p-type organic semiconductor compound and the fullerene compound is used as an n-type organic semiconductor compound, particularly high photoelectric conversion characteristics are exhibited. Further, the polymer compound (1) according to the present invention has an advantage that it has a low HOMO energy level and is hard to be oxidized.

  Further, since the polymer compound (1) has high solubility in a solvent, there is an advantage that coating and film formation are easy. Further, since the range of selection of the solvent is widened when performing the coating film formation, a solvent 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) according to the present invention exhibits high photoelectric conversion characteristics.

  The weight average molecular weight and number average molecular weight of the polymer compound (1) of the present invention are generally preferably 2,000 or more and 500,000 or less, more preferably 3,000 or more and 200,000 or less. Is. The weight average molecular weight and the number average molecular weight of the polymer compound (1) of the present invention can be calculated using gel permeation chromatography based on a calibration curve prepared using polystyrene as a standard sample.

  The polymer compound (1) according to the present invention preferably has a light absorption maximum wavelength (λmax) of 400 nm or more, more preferably 450 nm or more, while it is usually 1200 nm or less, preferably 1000 nm or less, more preferably 900 nm or less. is there. The full width at half maximum is usually 10 nm or more, preferably 20 nm or more, while it is usually 300 nm or less. Further, the absorption wavelength region of the polymer compound (1) according to the present invention is preferably as close as possible to the absorption wavelength region of sunlight.

  The solubility of the polymer compound (1) according to the present invention is not particularly limited, but the solubility in chlorobenzene at 25 ° C. is usually 0.1% by weight or more, more preferably 0.4% by weight or more, and further preferably It is 0.8% by weight or more, while it is usually 30% by weight or less, preferably 20% by weight. High solubility is preferable in that a thicker active layer can be formed.

  The polymer compound (1) according to the present invention preferably interacts between molecules. In the present invention, the term “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. As the interaction is stronger, the polymer compound tends to exhibit higher carrier mobility and / or crystallinity. That is, in a polymer compound that interacts between molecules, charge transfer between molecules is likely to occur, so that the p-type semiconductor compound (polymer compound (1)) and the n-type semiconductor compound in the active layer (IV) are separated from each other. It is considered that the holes generated at the interface can be efficiently transported to the anode (VI).

(Method for producing polymer compound (1))
The method for producing the polymer compound (1) used in the present invention is not particularly limited. For example, a compound represented by the formula (3) using benzobisthiazole as a starting material,

[In the formula (3), R ^{1 to} R ⁶ each independently represent an aliphatic hydrocarbon group having 1 to 20 carbon atoms or an aromatic hydrocarbon group having 6 to 10 carbon atoms. ]
A compound represented by the formula (4),

[In the formula (4), X and R ^{1 to} R ⁶ represent the same groups as described above. ]
A compound represented by the formula (5),

[In the formula (5), A ¹ , A ² , and R ^{1 to} R ⁶ each represent the same group as described above. ]
A compound represented by formula (6), and

[In the formula (6), A ¹ and A ² each represent the same group as described above. ]
Compound represented by formula (7)

[In the formula (7), A ¹ and A ² each represent the same group as described above. M ¹ and M ² each independently represent a boron atom or a tin atom. R ^{7 to} R ¹⁰ each independently represent an aliphatic hydrocarbon group having 1 to 6 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, or an aryloxy group having 6 to 10 carbon atoms. R ⁷ and R ⁸ may form a ring with M ¹ , and R ⁹ and R ¹⁰ may form a ring with M ² . m and n each represent an integer of 1 or 2. When m and n are 2, a plurality of R ⁷ and R ⁹ may be the same or different. ]
It is possible to manufacture by the manufacturing method.

The aliphatic hydrocarbon group represented by R ^{1 to} R ⁶ preferably has 1 to 18 carbon atoms, and more preferably 1 to 8 carbon atoms. Examples of the aliphatic hydrocarbon group of R ^{1 to} R ⁶ include a methyl group, an ethyl group, an isopropyl group, a tert-butyl group, an isobutyl group, an octyl group and an octadecyl group. The aromatic hydrocarbon group of R ^{1 to} R ⁶ preferably has 6 to 8 carbon atoms, more preferably 6 to 7 carbon atoms, and particularly preferably 6 carbon atoms. Examples of the aromatic hydrocarbon group of R ^{1 to} R ⁶ include a phenyl group. Among them, as R ^{1 to} R ⁶ , an aliphatic hydrocarbon group is preferable, a branched aliphatic hydrocarbon group is more preferable, and an isopropyl group is particularly preferable.

The compound of the above formula (7) can be produced, for example, as follows.
First step: a step in which benzobisthiazole is reacted with a base and a halogenated silane compound to obtain a compound represented by formula (3) Second step: a compound represented by formula (3) and a halogenating reagent Reacting with and obtaining a compound represented by the formula (4).

Furthermore, the compound represented by the formula (7) can be obtained by the steps including the following third step, fourth step and fifth step.
Third step: reacting the compound represented by formula (4) with the compound represented by formula (8) and / or (9).

[In the formulas (8) and (9), A ¹ and A ² each represent the same group as described above. R ¹¹ and R ¹² each independently represent a hydrogen atom or * -M ³ (R ¹³ ) _k R ¹⁴ . R ^13, R ¹⁴ each independently represent an aliphatic hydrocarbon group having 1 to 6 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, or an aryloxy group having 6 to 10 carbon atoms. M ³ represents a boron atom or a tin atom. R ¹³ and R ¹⁴ may form a ring together with M ³ . k represents an integer of 1 or 2. When k is 2, the plurality of R ¹³ may be the same or different. * Represents a bond to A ¹ or A ^1,,. A step of reacting the compound represented by the formula (4) to obtain the compound represented by the formula (4) Fourth step: treating the compound represented by the formula (5) with an acid or a base to form the compound represented by the formula (6) Fifth step of obtaining a compound represented by formula: Step of reacting a compound represented by formula (6) with a tin halide compound to obtain a compound represented by formula (7)

Coupling Reaction Further, the polymer compound (1) is combined with the structural unit represented by the formula (1) and the copolymerization component (2) by a coupling reaction so as to be alternately arranged, and thus the polymer compound (1) is a donor-acceptor type. It can be produced as a polymer compound.

The coupling reaction can be carried out by reacting the compound represented by the formula (6) with any of the compounds represented by the following formulas (B1) to (B21) in the presence of a metal catalyst.

[In formulas (B1) to (B28), R ^{30 to} R ⁵⁸ each independently represents a group similar to the hydrocarbon group having 8 to 30 carbon atoms of R ^{21 to} R ²⁶ , and A ³⁰ and A ³¹ are , Each independently represent the same groups as A ¹ and A ² . X represents a halogen atom. j represents an integer of 1 to 4. ]

(Other p-type semiconductor compounds)
The active layer (IV) contains at least the polymer compound (1) according to the present invention as a p-type semiconductor compound. However, a p-type semiconductor compound different from the polymer compound (1) can be mixed and / or laminated with the polymer compound (1) and used in combination. Other p-type semiconductor compounds that can be used in combination include, but are not particularly limited to, organic semiconductor compound (10). Hereinafter, the organic semiconductor compound (10) will be described. The organic semiconductor compound (10) may be a high molecular weight organic semiconductor compound or a low molecular weight organic semiconductor compound, but is preferably a high molecular weight organic semiconductor.

(Organic semiconductor compound (10))
The organic semiconductor compound (10) is not particularly limited, and a conjugated copolymer semiconductor compound such as polythiophene, polyfluorene, polyphenylene vinylene, polythienylene vinylene, polyacetylene or polyaniline; oligothiophene substituted with an alkyl group or other substituents. Copolymer semiconductor compounds and the like. Moreover, the copolymer semiconductor compound which copolymerized two or more types of monomer units is also mentioned. Conjugated copolymers are described, for example, in Handbook of Conducting Polymers, 3rd Ed. (2 volumes in total), 2007, J. Polym. Sci. Part A: Polym. Chem. 2013, 51, 743-768, J. Am. Chem. Soc. 2009, 131, 13886-13887, Angew. Chem. Int. Ed. 2013, 52, 8341-8344, Adv. Mater. It is possible to use copolymers described in publicly known documents such as 2009, 21, 2093-2097, derivatives thereof, and copolymers that can be synthesized by combining the described monomers. The organic semiconductor compound (10) may be one kind of compound or a mixture of plural kinds of compounds. The use of the organic semiconductor compound (10) can be expected to increase the amount of absorption due to the addition of the absorption wavelength band.

  Specific examples of the organic semiconductor compound (10) include the following, but are not limited to the following.

  The HOMO (highest occupied molecular orbital) energy level of the p-type semiconductor compound is not particularly limited and can be selected depending on the type of the n-type semiconductor compound described later. In particular, when a fullerene compound is used as the n-type semiconductor compound, the HOMO energy level of the p-type semiconductor compound is usually -5.9 eV or more, more preferably -5.7 eV or more, while usually -4.6 eV or less, It is preferably −4.8 eV or less. When the HOMO energy level of the p-type semiconductor compound is -5.9 eV or more, the characteristics as a p-type semiconductor are improved, and when the HOMO energy level of the p-type semiconductor compound is -4.6 eV or less, p-type The stability of the semiconductor compound is improved and the open circuit voltage (Voc) is also improved.

  The LUMO (lowest unoccupied molecular orbital) energy level of the p-type semiconductor compound is not particularly limited, but can be selected depending on the type of the n-type semiconductor compound described later. In particular, when a fullerene compound is used as an n-type semiconductor compound, the LUMO energy level of the p-type semiconductor compound is usually -4.5 eV or higher, preferably -4.3 eV or higher. On the other hand, it is usually −2.5 eV or less, preferably −2.7 eV or less. When the LUMO energy level of the p-type semiconductor is −2.5 eV or less, the band gap is adjusted, light energy with a long wavelength can be effectively absorbed, and the short-circuit current density is improved. When the LUMO energy level of the p-type semiconductor compound is −3.9 eV or more, electron transfer to the n-type semiconductor compound easily occurs, and the short-circuit current density improves.

As a method of calculating the LUMO energy level and the HOMO energy level, there are a method of theoretically obtaining a calculated value and a method of actually measuring. As a method of theoretically obtaining the calculated value, there are a semi-empirical molecular orbital method and an ab initio molecular orbital method. As an actual measurement method, an ionization potential can be measured by an ultraviolet-visible absorption spectrum measurement method or an ultraviolet photoelectron analyzer ("AC-3" manufactured by Riken Keiki Co., Ltd.) under normal temperature and normal pressure.
Among them, AC-3 measurement is preferable, and the AC-3 measurement method is used in the present invention.

[1.1.3 n-type semiconductor compound]
The n-type organic semiconductor compound is not particularly limited, but is generally a π-electron conjugated compound having a lowest unoccupied molecular orbital (LUMO) level of 3.5 to 4.5 eV, such as fullerene or Derivatives thereof, such as octaazaporphyrin, perfluoro compounds obtained by substituting hydrogen atoms of p-type organic semiconductor compounds with fluorine atoms (for example, perfluoropentacene and perfluorophthalocyanine), naphthalenetetracarboxylic acid anhydrides, naphthalenetetracarboxylic acid diimides, Examples thereof include aromatic carboxylic acid anhydrides such as perylene tetracarboxylic acid anhydride and perylene tetracarboxylic acid diimide, and polymer compounds containing the imidized compound as a skeleton.

Of these n-type organic semiconductor compounds, fullerene or a derivative thereof is preferable because it can rapidly and efficiently perform charge separation with the polymer compound (1) having the specific structural unit of the present invention (p-type organic semiconductor compound).
The fullerene and its derivatives include C60 fullerene, C70 fullerene, C76 fullerene, C78 fullerene, C84 fullerene, C240 fullerene, C540 fullerene, mixed fullerene, fullerene nanotube, and some of these hydrogen atoms, halogen atoms, substituted or none. Examples thereof include a fullerene derivative substituted with a substituted alkyl group, alkenyl group, alkynyl group, aryl group, heteroaryl group, cycloalkyl group, silyl group, ether group, thioether group, amino group, silyl group 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 number of carbon atoms in the alcohol moiety is preferably 1 to 30, more preferably 1 to 8, even 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 pyrrolidine trisic acid, C60 pyrrolidine. Tris acid ethyl ester, -Methylfuraropyrrolidine (MP-C60), (1,2-methanofullerene C60) -61-carboxylic acid, (1,2-methanofullerene C60) -61-carboxylic acid t-butyl ester, JP 2008-130889 Examples thereof include metallocenated fullerenes such as those disclosed in JP-A Nos. 7-31868, and fullerenes having a cyclic ether group such as those of U.S. Pat. No. 7,329,709.

<1.2 Cathode (II), Anode (VI)>
The cathode (II) and the anode (VI) have a function of collecting holes and electrons generated by light absorption. Therefore, it is preferable to use the electrode (II) (cathode) suitable for collecting electrons and the electrode (VI) (anode) suitable for collecting holes as the pair of electrodes. One of the pair of electrodes need only be translucent, and both may be translucent. “Translucent” means that 40% or more of sunlight is transmitted. In addition, it is preferable that the transparent electrode having a light-transmitting property has a solar ray transmittance of 70% or more in order to allow light to reach the active layer (IV) through the transparent electrode. The light transmittance can be measured by an ordinary spectrophotometer.

The cathode (II) is an electrode that is generally made of a conductive material having a work function smaller than that of the anode and has a function of smoothly extracting electrons generated in the active layer (IV).

  Examples of the material of the cathode (II) include conductive metals such as nickel oxide, tin oxide, indium oxide, indium tin oxide (ITO), indium-zirconium oxide (IZO), titanium oxide, indium oxide or zinc oxide. Oxides: metals such as gold, platinum, silver, chromium or cobalt, or alloys thereof can be used. These substances are preferable because they have a low work function, and further preferable because a conductive polymer material typified by PEDOT: PSS in which a polythiophene derivative is doped with polystyrenesulfonic acid can be laminated. In the case of stacking such a conductive polymer, since the conductive polymer material has a large work function, it is suitable for a cathode such as aluminum or magnesium even if the material has a small work function as described above. Metals can also be widely used.

  When the cathode (II) is a transparent electrode, it is preferable to use a transparent conductive metal oxide such as ITO, zinc oxide or tin oxide, and particularly preferably ITO.

  The film thickness of the cathode (II) is not particularly limited, but is usually 10 nm or more, preferably 20 nm or more, more preferably 50 nm or more. On the other hand, it is usually 10 μm or less, preferably 1 μm or less, more preferably 500 nm or less. When the thickness of the cathode (II) is 10 nm or more, the sheet resistance is suppressed, and when the thickness of the cathode (II) is 10 μm or less, the light is efficiently converted into electricity without lowering the light transmittance. Can be converted. When the cathode (II) is a transparent electrode, it is necessary to select a film thickness that is compatible with both light transmittance and sheet resistance.

  The sheet resistance of the cathode (II) is not particularly limited, but is usually 1 Ω / sq or more, on the other hand, 1000 Ω / sq or less, preferably 500 Ω / sq or less, more preferably 100 Ω / sq or less.

  The anode (VI) is an electrode that is generally made of a conductive material having a work function larger than that of the cathode and has a function of smoothly extracting holes generated in the active layer (IV).

  Examples of materials for the anode (VI) include metals such as platinum, gold, silver, copper, iron, tin, zinc, aluminum, indium, chromium, lithium, sodium, potassium, cesium, calcium or magnesium and alloys thereof; Examples thereof include inorganic salts such as lithium fluoride and cesium fluoride; metal oxides such as nickel oxide, aluminum oxide, lithium oxide and cesium oxide. These materials are preferable because they have a high work function. When an n-type semiconductor compound having conductivity such as zinc oxide is used as the material of the hole transport layer (V), a material having a small work function such as indium tin oxide (ITO) is used as the anode (VI). ) Can also be used as the material. From the viewpoint of electrode protection, the cathode (II) material is preferably a metal such as platinum, gold, silver, copper, iron, tin, aluminum, calcium or indium, and an alloy using these metals.

  The film thickness of the anode (VI) is not particularly limited, but is usually 10 nm or more, preferably 20 nm or more, more preferably 50 nm or more. On the other hand, it is usually 10 μm or less, preferably 1 μm or less, more preferably 500 nm or less. When the thickness of the anode (VI) is 10 nm or more, the sheet resistance is suppressed, and when the thickness of the anode (VI) is 10 μm or less, the light is efficiently converted into electricity without lowering the light transmittance. Can be converted. When the anode (VI) is used as a transparent electrode, it is necessary to select a film thickness that achieves both light transmittance and sheet resistance.

  The sheet resistance of the anode (VI) is not particularly limited, but is usually 1000 Ω / sq or less, preferably 500 Ω / sq or less, more preferably 100 Ω / sq or less. The lower limit is not limited, but is usually 1 Ω / sq or more.

  As a method of forming the anode (VI), there are 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.

  Furthermore, the cathode (II) and the anode (VI) may have a laminated structure of two or more layers. Further, the characteristics (electrical characteristics, wetting characteristics, etc.) may be improved by subjecting the cathode (II) and the anode (VI) to surface treatment.

<1.3 Base material (I)>
The photoelectric conversion element (VII) usually has a base material (I) which serves as a support. That is, the electrodes (II) and (VI) and the active layer (IV) are formed on the base material.

  The material of the base material (I) is not particularly limited as long as the effects of the present invention are not significantly impaired. Suitable examples of the material of the substrate (I) include inorganic materials such as quartz, glass, sapphire or titania; polyethylene terephthalate, polyethylene naphthalate, polyether sulfone, polyimide, nylon, polystyrene, polyvinyl alcohol, ethylene vinyl alcohol. Organic materials such as copolymers, fluororesin films, polyolefins such as vinyl chloride or polyethylene, cellulose, polyvinylidene chloride, aramid, polyphenylene sulfide, polyurethane, polycarbonate, polyarylate, polynorbornene or epoxy resin; paper or synthetic paper Examples include paper materials; composite materials such as those obtained by coating or laminating the surface of a metal such as stainless steel, titanium, or aluminum so as to provide insulation.

  Examples of the glass include soda glass, soda lime glass, non-alkali glass and the like. Among these, non-alkali glass is preferable in that the amount of ions eluted from the glass is small.

  The shape of the base material (I) is not limited and, for example, a plate-shaped, film-shaped or sheet-shaped material can be used. The film thickness of the substrate (I) is not limited, but is usually 5 μm or more, preferably 20 μm or more, while it is usually 20 mm or less, preferably 10 mm or less. It is preferable that the film thickness of the base material (I) is 5 μm or more because the possibility of insufficient strength of the photoelectric conversion element is reduced. It is preferable that the film thickness of the base material (I) is 20 mm or less because the cost is suppressed and the weight does not become heavy. When the material of the substrate (I) is glass, the film thickness is usually 0.01 mm or more, preferably 0.1 mm or more, while it is usually 1 cm or less, preferably 0.5 cm or less. It is preferable that the film thickness of the glass substrate (I) is 0.01 mm or more because the mechanical strength increases and the glass becomes less likely to break. Further, it is preferable that the film thickness of the glass substrate (I) is 0.5 cm or less because the weight does not become heavy.

<1.4 Buffer layer (III, V)>
The photoelectric conversion element (VII) includes an active layer (IV), a cathode (II) (hereinafter, also referred to as “electrode (II)”), and an anode (VI) (hereinafter, also referred to as “electrode (VI)”). It is preferable to have buffer layers (III) and (V) between them. The buffer layer can be classified into a hole transport layer (V) and an electron transport layer (III). Providing the buffer layer facilitates the movement of electrons or holes between the active layer (IV) and the cathode (II), and can prevent a short circuit between the electrodes. However, in the present invention, the buffer layers (III) and (V) may not be present.

  The hole transport layer (V) and the electron transport layer (III) are arranged so as to sandwich the active layer (IV) between the pair of electrodes (II) and (VI). That is, when the photoelectric conversion device (VII) according to the present invention includes both the hole transport layer (V) and the electron transport layer (III), the anode (VI), the hole transport layer (V), the active layer (IV). , The electron transport layer (III), and the cathode (II) are arranged in this order. When the photoelectric conversion device (VII) according to the present invention includes the hole transport layer (V) and does not include the electron transport layer (III), the anode (VI), the hole transport layer (V), the active layer (IV), and The cathode (II) is arranged in this order.

[1.4.1 Electron Transport Layer (III)]
The electron transport layer (III) is a layer for taking out electrons from the active layer (IV) to the cathode (II), and there is no particular limitation as long as it is a material having an electron transporting property that improves the efficiency of taking out electrons. Although it may be a compound or an inorganic compound, an inorganic compound is preferred.

  Preferable examples of the material of the inorganic compound include salts of alkali metals such as lithium, sodium, potassium or cesium, and metal oxides. Among them, the salt of alkali metal is preferably a fluoride salt such as lithium fluoride, sodium fluoride, potassium fluoride or cesium fluoride, and the metal oxide is titanium oxide (TiOx) or zinc oxide (ZnO). The metal oxide having n-type semiconductor characteristics such as the above) is preferable, and the conductive polymer is preferably polyethyleneimine ethoxylate. More preferably, the material of the inorganic compound is a metal oxide having n-type semiconductor characteristics, such as titanium oxide (TiOx) or zinc oxide (ZnO). Particularly preferred are zinc oxide (ZnO) and polyethyleneimine ethoxylate. These may be used alone or may be laminated. 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 (II).

  The LUMO energy level of the material of the electron transport layer (III) is not particularly limited, but is usually -4.0 eV or more, preferably -3.9 eV or more. On the other hand, it is usually −1.9 eV or less, preferably −2.0 eV or less. The LUMO energy level of the material of the electron transport layer (III) is preferably −1.9 eV or less in that the charge transfer can be promoted. It is preferable that the LUMO energy level of the material of the electron transport layer (III) is -4.0 eV or higher, because reverse electron transfer to the n-type semiconductor compound can be prevented.

  The HOMO energy level of the material of the electron transport layer (III) is not particularly limited, but is usually -9.0 eV or higher, preferably -8.0 eV or higher. On the other hand, it is usually -5.0 eV or less, preferably -5.5 eV or less. It is preferable that the HOMO energy level of the material of the electron transport layer (III) is −5.0 eV or less, because holes can be prevented from moving. As a method of calculating the LUMO energy level and the HOMO energy level of the material of the electron transport layer (III), a cyclic voltammogram measurement method can be mentioned.

  The thickness of the electron transport layer (III) is not particularly limited, but is usually 0.1 nm or more, preferably 0.5 nm or more, more preferably 1.0 nm or more. On the other hand, it is usually 100 nm or less, preferably 70 nm or less, more preferably 50 nm or less, particularly preferably 30 nm or less. When the thickness of the electron transport layer (III) is 0.1 nm or more, it functions as a buffer material, and when the thickness of the electron transport layer (III) is 100 nm or less, electrons are easily taken out. Therefore, the photoelectric conversion efficiency can be improved.

[1.4.2 Hole Transport Layer (V)]
The hole transport layer (V) is a layer for extracting holes from the active layer (IV) to the anode (VI), and is a hole transporting material capable of improving the efficiency of hole extraction. It is not particularly limited. Specifically, polythiophene, polypyrrole, polyacetylene, triphenylenediamine or polyaniline, etc., a conductive polymer doped with sulfonic acid and / or iodine, a polythiophene derivative having a sulfonyl group as a substituent, a conductive organic compound such as arylamine Examples thereof include compounds, metal oxides having p-type semiconductor characteristics such as molybdenum trioxide, vanadium pentoxide and nickel oxide, and the above-mentioned p-type semiconductor compounds. Among them, a conductive polymer doped with sulfonic acid is preferable, and poly (3,4-ethylenedioxythiophene) poly (styrenesulfonic acid) (PEDOT: PSS) obtained by doping a polythiophene derivative with polystyrenesulfonic acid, molybdenum oxide And metal oxides such as vanadium oxide are more preferable. Further, a thin film of a metal such as gold, indium, silver or palladium can also be used. The thin film of metal or the like may be formed alone or may be used in combination with the above organic material.

  The thickness of the hole transport layer (V) is not particularly limited, but is usually 0.2 nm or more, preferably 0.5 nm or more, more preferably 1.0 nm or more. On the other hand, it is usually 400 nm or less, preferably 200 nm or less, more preferably 100 nm or less, and particularly preferably 70 nm or less. When the thickness of the hole transport layer (V) is 0.2 nm or more, it functions as a buffer material, and when the thickness of the hole transport layer (V) is 400 nm or less, holes are taken out. It becomes easier and the photoelectric conversion efficiency can be improved.

  There is no limitation on the method of forming the electron transport layer (III) and the hole transport layer (V). For example, when a sublimable material 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 inkjet. When a semiconductor compound is used for the electron transport layer (III), the precursor may be converted into a semiconductor compound after the layer containing the semiconductor compound precursor is formed, like the active layer (IV).

<1.5 Method for manufacturing photoelectric conversion element>
The method for producing the photoelectric conversion element (VII) is not particularly limited, but the substrate (I), the cathode (II), the electron transport layer (III), the active layer (IV), the hole transport layer (V ), And the anode (VI) are sequentially laminated. For example, a glass substrate (manufactured by Geomatec Co., Ltd.) on which a transparent conductive film of indium tin oxide (ITO) (cathode) is patterned is subjected to ultrasonic cleaning with acetone, then ultrasonic cleaning with ethanol, and then dried by nitrogen blow, and UV- A substrate with an anode is obtained by performing ozone treatment. Next, a 0.5 M zinc acetate / 0.5 M aminoethanol / 2-methoxyethanol solution used as an electron transport layer was applied by a spin coater (3000 rpm for 40 seconds) and then annealed at 175 ° C. for 30 minutes to convert the electrons into zinc oxide. A transport layer can be formed. After that, the active layer can be formed by carrying in a glove box, spin-coating a mixed solution of a donor material and an acceptor material in an inert gas atmosphere, and performing annealing treatment or reduced pressure drying on a hot plate. Then, molybdenum oxide is deposited under reduced pressure to form a hole transport layer. Finally, silver, which is an electrode, is vapor-deposited to serve as an anode to obtain a photoelectric conversion element. Further, a photoelectric conversion element having a different structure, for example, at least one of an electron transport layer (III) and a hole transport layer (V) A photoelectric conversion element not having one can also be manufactured by the same method.

<1.6 Photoelectric conversion characteristics>
The photoelectric conversion characteristic of the photoelectric conversion element (VII) can be obtained as follows. The photoelectric conversion element (VII) is irradiated with light under AM1.5G conditions with a solar simulator at an irradiation intensity of 100 mW / cm 2 to measure current-voltage characteristics. From the obtained current-voltage curve, photoelectric conversion characteristics such as photoelectric conversion efficiency (PCE), short circuit current density (Jsc), open circuit voltage (Voc), fill factor (FF), series resistance and shunt resistance can be obtained.

  In addition, as a method of measuring the durability of the photoelectric conversion element, there is a method of obtaining a maintenance rate of photoelectric conversion efficiency before and after exposing the photoelectric conversion element to the atmosphere. (Maintenance rate) = (Photoelectric conversion efficiency N hours after exposure to air) / (Photoelectric conversion efficiency immediately before exposure to air)

  In order to put the photoelectric conversion element into practical use, it is important that it has high photoelectric conversion efficiency and high durability in addition to being simple and inexpensive to manufacture. From this viewpoint, the maintenance rate of the photoelectric conversion efficiency before and after exposure to the atmosphere for one week is preferably 60% or more, more preferably 80% or more, and the higher the better.

<2. Organic thin-film solar cell according to the present invention>
The photoelectric conversion element (VII) according to the present invention is preferably used as a solar cell element, in particular, an organic thin film solar cell.

  The application of the organic thin-film solar cell according to the present invention is not limited and can be used for any application. Examples of fields to which the organic thin-film solar cell according to the present invention can be applied include solar cells for building materials, solar cells for automobiles, solar cells for interiors, solar cells for railways, solar cells for ships, solar cells for airplanes, and spacecraft. Solar cells for home appliances, solar cells for home appliances, solar cells for mobile phones, solar cells for toys, and the like.

  The organic thin film solar cell according to the present invention may be used as it is, or may be used as a solar cell module by installing a solar cell on the substrate (I). As a specific example, when a plate material for building materials is used as the base material, a thin film solar cell is provided on the surface of the plate material to produce a solar cell panel as a solar cell module.

  The measuring method used in the synthesis example is as follows.

(NMR spectrum measurement)
The NMR spectrum of the benzobisthiazole compound was measured using an NMR spectrum measuring device ("400MR" manufactured by Agilent (formerly Varian) and "AVANCE500" manufactured by Bruker).

(High-resolution mass spectrum measurement)
The benzobisthiazole compound was subjected to high-resolution mass spectrum measurement (APCI: atmospheric pressure chemical ionization method) using a mass spectrometer (“MicrOTOF” manufactured by Bruker Daltnics).

(Gel Permeation Chromatography (GPC))
The molecular weight of the benzobisthiazole compound was measured by gel permeation chromatography (GPC). At the time of measurement, the benzobisthiazole compound was dissolved in a mobile phase solvent (chloroform) to a concentration of 0.5 g / L, the measurement was performed under the following conditions, and based on a calibration curve prepared using polystyrene as a standard sample. The weight average molecular weight of the benzobisthiazole compound was calculated by conversion. The GPC conditions in the measurement are as follows.
Mobile phase: Chloroform Flow rate: 0.6 ml / min
Device: HLC-8320GPC (manufactured by Tosoh Corporation)
Column: TSKgel (registered trademark) SuperHM-H'2 + TSKgel (registered trademark) SuperH2000 (manufactured by Tosoh Corporation)

(IR spectrum)
The IR spectrum of the benzobisthiazole compound was measured using an infrared spectrophotometer (“FT / IR-6100” manufactured by JASCO).

(UV visible absorption spectrum)
The obtained benzobisthiazole compound was dissolved in chloroform so that the concentration became 0.03 g / L, and an ultraviolet / visible spectrophotometer (manufactured by Shimadzu Corporation, "UV-2450", "UV-3150"), and The UV-visible absorption spectrum was measured using a cell having an optical path length of 1 cm.

(Melting point measurement)
The melting point of the benzobisthiazole compound was measured using a melting point measuring device (Buchi, "M-560").

(Ionization potential measurement)
A benzobisthiazole compound was deposited on a glass substrate so as to have a thickness of 50 nm to 100 nm. The ionization potential of this film was measured at room temperature and atmospheric pressure with an ultraviolet photoelectron analyzer ("AC-3" manufactured by Riken Keiki Co., Ltd.).

  An example of the synthesis of the polymer compound (1) used in this patent is shown below. The polymer compound (1) used in the present invention is not limited by the following synthesis examples, and the synthesis method itself may be appropriately modified within a range compatible with the gist of the above and the following. Of course it is possible. In the following, "part" means "part by mass" and "%" means "% by mass" unless otherwise specified.

Synthesis example 1
Synthesis of DBTH-DT (2,6-bis-triisopropylsilanylbenzo [1,2-d; 4,5-d '] bisthiazole)

Under a nitrogen atmosphere, DBTH (benzo [1,2-d; 4,5-d '] bisthiazole, 4 g, 20.8 mmol) and tetrahydrofuran (160 mL) were added to a 200 mL flask and cooled to -40 ° C to obtain lithium diisopropylamide. The solution (1.5 M solution, 29.1 mL, 43.7 mmol) was added dropwise. Then, after stirring at -40 ° C for 1 hour, triisopropyl chloride (8.8 mL, 41.6 mmol) was added dropwise, the temperature was raised to room temperature, and the mixture was stirred for 2 hours. After completion of the reaction, 10% saline was added and liquid-separated, and the obtained aqueous layer was extracted once with ethyl acetate. The organic layers were combined, washed with saturated saline and dried over anhydrous magnesium sulfate. Then, the crude product obtained by filtration and concentration is purified by column chromatography (silica gel, chloroform) to obtain DBTH-DT (2,6-bis-triisopropylsilanylbenzo [1,2-d; 4,5-d '] Bisthiazole) was obtained as a white solid in 7.14 g (68% yield). It was confirmed by ¹ H-NMR measurement, ¹³ C-NMR measurement, melting point measurement, and high-resolution mass spectrum analysis that the target compound was produced.

Synthesis example 2
Synthesis of DI-DBTH-DT (4,8-diiodo-2,6-bis-triisopropylsilanylbenzo [1,2-d; 4,5-d '] bisthiazole)

DBTH-DT (2,6-bis-triisopropylsilanylbenzo [1,2-d; 4,5-d '] bisthiazole, 3 g, 5.88 mmol), N, N, in a 200 mL flask under a nitrogen atmosphere. N ′, N′-Tetramethylethylenediamine (1.84 mL, 12.4 mmol) and tetrahydrofuran (60 mL) were added, and the mixture was cooled to −40 ° C. and lithium diisopropylamide solution (1.5 M solution, 8.24 mL, 12.4 mmol). Was dripped. Then, after stirring at 0 degreeC for 30 minutes, it cooled at -80 degreeC, iodine (7.47 g, 29.4 mmol) was added, it heated up to room temperature, and stirred for 2 hours. After completion of the reaction, 10% aqueous sodium hydrogen sulfite solution was added for liquid separation, and the obtained aqueous layer was extracted once with ethyl acetate, and then the organic layers were combined and washed with 5% aqueous sodium hydrogen carbonate and saturated brine, and dried. It was dried using magnesium sulfate. The crude product obtained by filtration and concentration was purified by column chromatography (silica gel, chloroform / hexane = 1/1) to give DI-DBTH-DT (4,8-diiodo-2,6-bis-triisopropylsilanylbenzo). [1,2-d; 4,5-d '] Bisthiazole) was obtained as a white solid in an amount of 1.95 g (yield 44%). It was confirmed by ¹ H-NMR measurement, ¹³ C-NMR measurement, melting point measurement, and high-resolution mass spectrum analysis that the target compound was produced.

Synthesis example 3
Synthesis reaction of DBTH-EHT (4,8-bis [5- (2-ethylhexyl) thiophen-2-yl] benzo [1,2-d; 4,5-d '] bisthiazole

Under a nitrogen atmosphere, DI-DBTH-DT (4,8-diiodo-2,6-bis-triisopropylsilanylbenzo [1,2-d; 4,5-d '] bisthiazole, 800 mg, 1 was added to a 30 mL flask. 0.06 mmol), tributyl [5- (2-ethylhexyl) thiophen-2-yl] stannane (1.80 g, 3.70 mmol), tris (dibenzylideneacetone) dipalladium (0) -chloroform adduct (115 mg, 0. (08 mmol), tris (2-furyl) phosphine (39 mg, 0.37 mmol), and N, N-dimethylformamide (16 mL) were added, and the mixture was heated to 60 ° C. and reacted for 19 hours. Then, the mixture was cooled to room temperature, a tetrabutylammonium fluoride solution (1M tetrahydrofuran solution, 5.2 mL, 3.18 mmol) was added, and the mixture was reacted for 3 hours. After the reaction was completed, water was added and the mixture was extracted twice with chloroform. The obtained organic layer was washed with water and dried over anhydrous magnesium sulfate. The crude product obtained by filtration and concentration was purified by column chromatography (silica gel, chloroform / hexane = 1/1) to obtain DBTH-EHT (4,8-bis [5- (2-diethylhexyl) thiophen-2-yl]. ] Benzo [1,2-d; 4,5-d '] bisthiazole) was obtained as a yellow solid in 442 mg (83% yield). It was confirmed by ¹ H-NMR measurement, ¹³ C-NMR measurement, IR spectrum measurement, and high-resolution mass spectrum analysis that the target compound was produced.

Synthesis Examples 4 and 5
Similarly to Synthesis Example 3, DBTH-C8THO (4,8-bis (5-octylthiophen-2-yl) benzo [1,2-d; 4,5-d '] bisthiazole) (Synthesis Example 4), DBTH-DMOT (4,8-bis [5- (3,7-dimethyloctyl) thiophen-2-yl) benzo [1,2-d; 4,5-d '] bisthiazole) (Synthesis example 5) Obtained. The yield was 83-84%.

Synthesis example 6
DBTH-EHT-DSM (4,8-bis [5- (2-ethylhexyl) thiophen-2-yl] -2,6-bistrimethylstannylbenzo [1,2-d; 4,5-d '] bis (Thiazole) synthesis (tinning reaction of DBTH-EHT)

DBTH-EHT (4,8-bis [5- (2-ethylhexyl) thiophen-2-yl] benzo [1,2-d; 4,5-d '] bisthiazole, 400 mg, in a 30 mL flask under a nitrogen atmosphere. 0.69 mmol) and tetrahydrofuran (12 mL) were added, the mixture was cooled to 0 ° C., and a lithium diisopropylamide solution (2M solution, 0.76 mL, 1.51 mmol) was added dropwise. Then, after stirring at 0 ° C. for 30 minutes, the mixture was cooled to −80 ° C., trimethyltin chloride (1.72 mL, 1.72 mmol) was added, the temperature was raised to room temperature, and the mixture was stirred for 2 hours. After the reaction was completed, water was added and the organic layer obtained by extracting once with toluene was washed with saturated saline and dried over anhydrous magnesium sulfate. The crude product obtained by filtration and concentration was purified by GPC-HPLC (JAIGEL-1H, 2H, chloroform) to obtain DBTH-EHT-DSM (4,8-bis [5- (2-ethylhexyl) thiophen-2-yl]. -2,6-bistrimethylstannylbenzo [1,2-d; 4,5-d '] bisthiazole) was obtained as an orange solid in an amount of 434 mg (yield 70%). It was confirmed by ¹ H-NMR measurement that the target compound was produced.

Synthesis examples 7 and 8
Similar to Synthesis Example 6, DDBTH-C8THO-DSM (4,8-bis (5-octylthiophen-2-yl) -2,6-bistrimethylstannylbenzo [1,2-d; 4,5-d '] Bisthiazole) (Synthesis example 7), DBTH-DMOT-DSM (4,8-bis [5- (3,7-dimethyloctyl) thiophen-2-yl] -2,6-bistrimethylstannylbenzo [ 1,2-d; 4,5-d '] bisthiazole) (Synthesis example 8) was obtained. The yield was 33 to 34%.

Synthesis example 9
Synthesis of P-DBTH-EHT-O-IMTH

  In a 20 mL flask under a nitrogen atmosphere, DBTH-EHT-DSB (4,8-bis [5- (2-ethylhexyl) thiophen-2-yl] -2,6-bistributylstannylbenzo [1,2-d; 4,5-d ′] Bisthiazole, 150 mg, 0.13 mmol), O-IMTH-DB (1,3-dibromo-5-octylthieno [3,4-c] pyrrole-4,6-dione, 57 mg, 0 .13 mmol), tris (dibenzylideneacetone) dipalladium (0) -chloroform adduct (5.4 mg, 5.2 μmol), tris (o-tolyl) phosphine (6.3 mg, 21 μmol) and chlorobenzene (12 mL) were added. The reaction was carried out at 120 ° C for 23 hours. After completion of the reaction, the reaction liquid was added to methanol (60 mL), and the precipitated solid was collected by filtration, and the obtained solid was subjected to Soxhlet washing (methanol, acetone, hexane). Then, Soxhlet extraction (chloroform) was performed to obtain 89 mg (82%) of P-DBTH-EHT-O-IMTH as a black solid.

Synthesis example 10
P-DBTH-EHT-EH-DPP (Synthesis Example 10) was obtained in the same manner as in Synthesis Example 9. The yield was 43%.

Synthesis Example 11
Synthesis reaction of DHD-DBTH (4,8-bis (2-hexyldecyloxy) benzo [1,2-d; 4,5-d '] bisthiazole)

  In a 50 mL flask under a nitrogen atmosphere, DI-DBTH-DT (4,8-diiodo-2,6-bis-triisopropylsilanylbenzo [1,2-d; 4,5-d '] bisthiazole, 3 g, 4.0 mmol), 2-hexyldecanol (5.8 g, 23.8 mmol), copper (I) iodide (151 mg, 0.79 mmol), 1,10-PHT (1,10-phenanthroline, 286 mg, 1.59 mmol). , T-butoxy sodium (1.14 g, 11.9 mmol) and 1,4-dioxane (30 mL) were added, and the mixture was reacted under reflux for 23 hours. After cooling to room temperature, tetrabutylammonium fluoride (1M-tetrahydrofuran solution, 12.0 mL, 11.9 mmol) was added, and the mixture was further reacted at room temperature for 3 hours. After completion of the reaction, water was added and the organic layer obtained by extracting twice with chloroform was washed with water and dried over anhydrous magnesium sulfate. The crude product obtained by filtration and concentration was purified by column chromatography (silica gel, chloroform / hexane = 1/1) to obtain DHD-DBTH (4,8-bis (2-hexyldecyloxy) benzo [1,2-d]. 4,5-d '] bisthiazole) was obtained as a brown oil in 1.30 g (yield 49%).

Synthesis Examples 12 and 13
Similarly to Synthesis Example 11, DEH-DBTH (4,8-bis (2-ethylhexyloxy) benzo [1,2-d; 4,5-d '] bisthiazole) (Synthesis Example 12), DDMO-DBTH (4,8-bis (3,7-dimethyloctyloxy) benzo [1,2-d; 4,5-d '] bisthiazole) (Synthesis Example 13) was obtained. The yield was 44-60%.

Synthesis Example 14
Synthesis of DHD-DBTH-DSB (4,8-bis (2-hexyldecyloxy) -2,6-bistributylstannylbenzo [1,2-d; 4,5-d '] bisthiazole) (DHD- Tinning reaction of DBTH)

In a 30 mL flask under a nitrogen atmosphere, DHD-DBTH (4,8-bis (2-hexyldecyloxy) benzo [1,2-d; 4,5-d '] bisthiazole, 1 g, 1.49 mmol) and tetrahydrofuran ( 20 mL) was added and the mixture was cooled to −80 ° C. and n-butyllithium (1.6M hexane solution, 1.95 mL, 3.12 mmol) was added dropwise. Then, after stirring for 30 minutes, tributyltin chloride (0.87 mL, 3.19 mmol) was added, the temperature was raised to room temperature, and the mixture was stirred for 2 hours. After the reaction was completed, water was added and the organic layer obtained by extracting once with toluene was washed with saturated saline and dried over anhydrous magnesium sulfate. The crude product obtained by filtration and concentration is purified by GPC-HPLC (JAIGEL-1H, 2H, chloroform) to give DHD-DBTH-DSB (4,8-bis (2-hexyldecyloxy) -2,6-bistributyl. 1.12 g (yield 63%) of stannyl benzo [1,2-d; 4,5-d '] bisthiazole) was obtained as a brown oil. It was confirmed by ¹ H-NMR measurement that the target compound was produced.

Synthesis examples 15 to 16
Similar to Synthesis Example 14, DEH-DBTH-DSB (4,8-bis (2-ethylhexyloxy) -2,6-bistributylstannylbenzo [1,2-d; 4,5-d '] bis Thiazole) (Synthesis Example 15), DDMO-DBTH-DSB (4,8-bis (3,7-dimethyloctyloxy) -2,6-bistributylstannylbenzo [1,2-d; 4,5-d '] Bisthiazole) (Synthesis example 16) was obtained. The yield was 36-63%.

Synthesis Example 17
Synthesis of P-DHD-DBTH-O-IMTHT

  Under a nitrogen atmosphere, DHD-DBTH-DSB (4,8-bis (2-hexyldecyloxy) -2,6-bistributylstannylbenzo [1,2-d; 4,5-d '] was added to a 20 mL flask. Bisthiazole, 0.14 mmol), O-IMTHT-DB (1,3-dibromo-5-octylthieno [3,4-c] pyrrole-4,6-dione, 0.14 mmol), tris (dibenzylideneacetone) di Palladium (0) -chloroform adduct (5.6 mg, 5.4 μmol), tris (o-tolyl) phosphine (6.2 mg, 22 μmol) and chlorobenzene (12 mL) were added, and the mixture was reacted at 120 ° C. for 24 hours. After completion of the reaction, the reaction solution was added to methanol (60 mL), and the precipitated solid was collected by filtration, and the obtained solid was washed with Soxhlet (methanol, acetone). Then, Soxhlet extraction (chloroform) was performed to obtain P-DHD-DBTH-O-IMTHT as a solid in a yield of 75%.

Synthesis Examples 18-21
Similar to Synthesis Example 17, P-DHD-DBTH-TDZT (Synthesis Example 18), P-DHD-DBTH-DMO-DPP (Synthesis Example 19), P-DHD-DBTH-3HTDZT (Synthesis Example 18), P- DEH-DBTH-EH-DPP (Synthesis Example 20) and P-DDMO-DBTH-EH-BDT (Synthesis Example 21) were obtained. The yield was 19-99%.

(Evaluation method of photoelectric conversion element)
A 0.05027 mm square metal mask is attached to the photoelectric conversion element, a solar simulator (CEP2000, AM1.5G filter, radiant intensity 100 mW / cm ² , manufactured by Spectrometer) is used as an irradiation light source, and a source meter (manufactured by Keithley, model 2400) is used. ), The current-voltage characteristic between the ITO electrode and the aluminum electrode was measured. From this measurement result, the open circuit voltage Voc (V), the short circuit current density Jsc (mA / cm ² ), the fill factor FF, and the photoelectric conversion efficiency PCE (%) were calculated.

Here, the open circuit voltage Voc is a voltage value when the current value is 0 (mA / cm2), and the short circuit current density Jsc is a current density when the voltage value is 0 (V). The fill factor FF is a factor representing the internal resistance, and is represented by the following equation when the maximum output is Pmax.
FF = Pmax / (Voc x Jsc)
Further, the photoelectric conversion efficiency PCE is given by the following equation when the incident energy is Pin.
PCE = (Pmax / Pin) × 100
= (Voc x Jsc x FF / Pin) x 100

<Example 1>

(Preparation of mixed solution of p-type semiconductor compound and n-type semiconductor compound)
As the p-type semiconductor compound, a polymer compound having a structure of P-DHD-DBTH-O-IMTHT [Chemical Formula 28] was used.
PC61BM (phenyl C61 butyric acid methyl ester, manufactured by Frontier Carbon Co., NS-E100H) was used as an n-type semiconductor compound, and p-type semiconductor compound: n-type semiconductor compound = 1: 2 (weight) was added to chlorobenzene at a total concentration of 2.5 wt%. Dissolved. This solution was stirred and mixed on a hot stirrer at a temperature of 100 ° C. for 2 hours or more. The solution after stirring and mixing was filtered with a 0.45 μm filter to obtain a mixed solution of a p-type semiconductor compound and an n-type semiconductor compound.

(Production of photoelectric conversion element)
A glass substrate (manufactured by Geomatec) on which a transparent conductive film (cathode) of indium tin oxide (ITO) was patterned was subjected to ultrasonic cleaning with acetone, ultrasonic cleaning with ethanol, and then dried by nitrogen blow.

After the UV-ozone treatment, a 0.5 M zinc acetate / 0.5 M aminoethanol / 2-methoxyethanol solution used as an electron transport layer is applied by a spin coater (3000 rpm).
40 seconds) and then annealed at 175 ° C. for 30 minutes.

  The mixed solution of the p-type semiconductor compound and the n-type semiconductor compound was spin-coated in the glove box under an inert gas atmosphere, and annealed or dried under reduced pressure on a hot plate.

  Molybdenum oxide, which is a hole transport layer, was vapor-deposited with a vapor deposition machine. After that, silver, which is an electrode, was vapor-deposited to form an inverted device. The obtained device was evaluated for the above photoelectric conversion element. The results are shown in Table 1.

<Example 2>

A polymer compound having a structure of P-DHD-DBTH-TDZT [Chemical Formula 29] was used as the p-type semiconductor compound.
PCBM (C61) was used as an n-type semiconductor compound, and p-type semiconductor compound: n-type semiconductor compound = 1: 1.5 (weight) was dissolved in chlorobenzene at a total concentration of 2.0 wt% to obtain a 0.45 μm filter. To give a mixed solution. Using the obtained mixed solution, a device was manufactured in the same manner as in Example 1. The obtained photoelectric conversion element was evaluated for the obtained reverse-type constituent device. The results are shown in Table 1.

<Example 3>

As the p-type semiconductor compound, a polymer compound having a structure of P-DBTH-EHT-O-IMTH [Chemical Formula 30] was used.
PCBM (C61) was used as an n-type semiconductor compound, dissolved in chlorobenzene with a p-type semiconductor compound: n-type semiconductor compound = 1: 2 (weight) and a total concentration of 6.0 wt% and passed through a 0.45 μm filter. A mixed solution was prepared. Using the obtained mixed solution, an inverted component device was manufactured in the same manner as in Example 1. The obtained device was evaluated for the above photoelectric conversion element. The results are shown in Table 1.

<Example 4>

A polymer compound having a structure of P-DHD-DBTH-TDZT [Chemical Formula 29] was used as the p-type semiconductor compound.
Using PCBM (C61) as an n-type semiconductor compound, p-type semiconductor compound: n-type semiconductor compound = 1: 1.5 (weight), dissolved in chlorobenzene at a total concentration of 2.0 wt% to form a 0.45 μm filter. To obtain a mixed solution of a p-type semiconductor compound and an n-type semiconductor compound.

(Production of photoelectric conversion element)
A glass substrate (manufactured by Geomatec) on which a transparent conductive film (cathode) of indium tin oxide (ITO) was patterned was subjected to ultrasonic cleaning with acetone, ultrasonic cleaning with ethanol, and then dried by nitrogen blow.

  After the UV-ozone treatment, a 0.05 wt% polyethyleneimine ethoxylate / 2-methoxyethanol solution used as an electron transport layer was applied by a spin coater (3000 rpm for 40 seconds), and then annealed at 100 ° C. for 1 minute.

  The mixed solution of the p-type semiconductor compound and the n-type semiconductor compound was spin-coated in the glove box under an inert gas atmosphere, and annealed or dried under reduced pressure on a hot plate.

  Molybdenum oxide, which is a hole transport layer, was vapor-deposited with a vapor deposition machine. After that, silver, which is an electrode, was vapor-deposited to form an inverted device. The obtained device was evaluated for the above photoelectric conversion element. The results are shown in Table 1.

<Example 5>

A polymer compound having a structure of P-DHD-DBTH-TDZT [Chemical Formula 29] was used as the p-type semiconductor compound.
Using PCBM (C61) as an n-type semiconductor compound, p-type semiconductor compound: n-type semiconductor compound = 1: 1.5 (weight), dissolved in chlorobenzene at a total concentration of 2.0 wt% to form a 0.45 μm filter. To obtain a mixed solution of a p-type semiconductor compound and an n-type semiconductor compound.

(Production of photoelectric conversion element)
A glass substrate (manufactured by Geomatec) on which a transparent conductive film (cathode) of indium tin oxide (ITO) was patterned was subjected to ultrasonic cleaning with acetone, ultrasonic cleaning with ethanol, and then dried by nitrogen blow.

After the UV-ozone treatment, a 0.5 M zinc acetate / 0.5 M aminoethanol / 2-methoxyethanol solution used as an electron transport layer is applied by a spin coater (3000 rpm).
40 seconds) and then annealed at 175 ° C. for 30 minutes.
Further, in order to stack an electron transport layer, a 0.05 wt% polyethyleneimine ethoxylate / 2-methoxyethanol solution was applied by a spin coater (3000 rpm for 40 seconds), and then annealed at 100 ° C. for 1 minute.

  The mixed solution of the p-type semiconductor compound and the n-type semiconductor compound was spin-coated in the glove box under an inert gas atmosphere, and annealed or dried under reduced pressure on a hot plate.

  Molybdenum oxide, which is a hole transport layer, was vapor-deposited with a vapor deposition machine. After that, silver, which is an electrode, was vapor-deposited to form an inverted device. The obtained device was evaluated for the above photoelectric conversion element. The results are shown in Table 1.

<Example 6>

A polymer compound having a structure of P-DHD-DBTH-TDZT [Chemical Formula 29] was used as the p-type semiconductor compound.
Using PCBM (C61) as an n-type semiconductor compound, p-type semiconductor compound: n-type semiconductor compound = 1: 1.5 (weight), dissolved in chlorobenzene at a total concentration of 2.0 wt% to form a 0.45 μm filter. To obtain a mixed solution of a p-type semiconductor compound and an n-type semiconductor compound.

(Production of photoelectric conversion element)
A glass substrate (manufactured by Geomatec) on which a transparent conductive film (cathode) of indium tin oxide (ITO) was patterned was subjected to ultrasonic cleaning with acetone, ultrasonic cleaning with ethanol, and then dried by nitrogen blow.

After the UV-ozone treatment, a 0.5 M zinc acetate / 0.5 M aminoethanol / 2-methoxyethanol solution used as an electron transport layer is applied by a spin coater (3000 rpm).
40 seconds) and then annealed at 175 ° C. for 30 minutes.

  The mixed solution of the p-type semiconductor compound and the n-type semiconductor compound was spin-coated in the glove box under an inert gas atmosphere, and annealed or dried under reduced pressure on a hot plate.

Vanadium oxide, which is a hole transport layer, was vapor-deposited with a vapor deposition machine. After that, silver, which is an electrode, was vapor-deposited to form an inverted device. The obtained device was evaluated for the above photoelectric conversion element. The results are shown in Table 1.

  It is confirmed that most of the photoelectric conversion elements made of the polymer compound used in the present invention as described above exhibit a high voltage of 0.74V or more because the HOMO level is moderately deep, and the maximum is 0.87V. Was achieved. Furthermore, it was confirmed by the production method that the polymer compound used in the present invention can introduce various skeletons and substituents, and Voc of the photoelectric conversion element can be finely adjusted.

(VII) Photoelectric conversion element (VI) Anode (V) Hole transport layer
(IV) Active layer (III) Electron transport layer (II) Cathode (I) Substrate

Claims (9)

A substrate, a cathode, an active layer, and the anode is a photoelectric conversion element having an arrangement structure in this order, to the active layer, and benzobisthiazole structural unit represented by the formula (1), wherein A polymer compound which is a donor-acceptor type semiconductor polymer in which the copolymerization component (2) represented by any one of (b1) to (b16), (b19) to (b25) and (b28) is alternately arranged . A photoelectric conversion element comprising:
[In Formula (1),
A ¹ and A ² are each independently an alkoxy group, a thioalkoxy group, a thiophene ring optionally substituted with a hydrocarbon group, a thiazole ring optionally substituted with a hydrocarbon group or an organosilyl group, or It represents a phenyl group which may be substituted with a hydrocarbon group, an alkoxy group, a thioalkoxy group, an organosilyl group, a halogen atom, or a trifluoromethyl group. ]
Expression (b1) ~ (b16), (b19) ~ (b25), (b28) in, the ^{R 30 ~R 44, R 46 ~R} 55, R 58 are each independently a hydrocarbon of 8 to 30 carbon atoms Represents a group , A ³⁰ and A ³¹ each independently represent the same group as A ¹ and A ^2, and j represents an integer of 1 to 4. The symbol ● represents a bond to be bonded to the thiazole ring of the structural unit represented by the formula (1). ] The photoelectric conversion element according to claim ¹ , wherein A ¹ and A ² of the polymer compound are groups represented by the following formulas (a1) to (a4) , respectively.
[In formulas (a1) to (a4) ,
R ²¹ ~R ^23, R ²⁵ each independently represent a hydrocarbon group having 8 to 30 carbon atoms. R ²⁴ represents a hydrogen atom or a hydrocarbon group having 8 to 30 carbon atoms. * Represents a bond that bonds to the benzene ring of benzobisthiazole. ] The active layer, the photoelectric conversion element according to claim 1 or 2 further comprising an n-type organic semiconductor compound. The photoelectric conversion element according to claim 3 , wherein the n-type organic semiconductor compound is fullerene or a derivative thereof. The photoelectric conversion device according to any one of claims 1 to 4 having an electron-transporting layer between the cathode and the active layer. The photoelectric conversion device according to any one of claims 1 to 5 having a hole transporting layer between the anode and the active layer. The photoelectric conversion device according to any one of claims 1 to 6, wherein said cathode is a transparent electrode. The photoelectric conversion device according to any one of claims 1 to 7, wherein the anode is a metal electrode. The organic thin film solar cell, comprising the photoelectric conversion device according to any one of claims 1-8.