JP2013221074A - π-ELECTRON CONJUGATED BLOCK COPOLYMER AND PHOTOELECTRIC TRANSFER ELEMENT - Google Patents

Abstract

When used as a photoelectric conversion active layer of a photoelectric conversion element together with an electron-accepting material, an ideal phase separation structure can be formed in a bulk heterojunction structure, like a homopolymer of a monomer as a raw material The present invention provides a high-purity π-electron conjugated block copolymer with a small amount of impurities and high block efficiency.
A π-electron conjugated block copolymer has a condensed π-electron conjugated skeleton, a fluorene skeleton, a carbazole skeleton, a dibenzosilole skeleton, a dibenzogermol skeleton, and a substituent having a thiophene ring as part of the chemical structure. A π-electron conjugated block copolymer containing at least two types of polymer blocks containing a monomer unit having a skeleton selected from bithiophene skeletons, wherein the polymer block is composed of a monocyclic aromatic ring. Are connected by a divalent group.
[Selection figure] None

Description

  The present invention relates to a novel π-electron conjugated block copolymer having self-organization, a method for producing the same, and a photoelectric conversion element having an organic thin film obtained from a composition containing the copolymer as a photoelectric conversion active layer. It is.

  Organic thin-film solar cells that can be produced by a coating method using a polymer material that is soluble in a solvent are manufactured at a lower cost than inorganic solar cells such as polycrystalline silicon, amorphous silicon, and compound semiconductors that are currently mainstream solar cells. It is said that it can be done and is attracting a lot of attention.

Organic thin-film solar cells, which are one type of photoelectric conversion element, mainly have a bulk heterojunction structure in which a conjugated polymer and an electron-accepting material are mixed as a photoelectric conversion active layer. Specific examples include Non-Patent Document 1, poly (3-hexylthiophene) (P3HT) as a conjugated polymer, and [6,6] -phenyl C ₆₁ butyric acid methyl ester (PCBM) as a fullerene derivative that is an electron-accepting material. An organic thin film solar cell having a photoelectric conversion active layer mixed with is described.

  In a bulk heterojunction structure, light incident from a transparent electrode is absorbed by a conjugated polymer or an electron-accepting material to generate excitons in which electrons and holes are combined. The generated exciton moves to the heterojunction interface where the conjugated polymer and the electron-accepting material are adjacent to each other, and charges are separated into holes and electrons. Holes and electrons are transported through the conjugated polymer phase and the electron-accepting material phase, respectively, and are extracted from the electrode. Therefore, to increase the conversion efficiency of organic thin-film solar cells, increase the amount of light absorbed by the photoelectric conversion active layer and control the phase separation structure (morphology) of the bulk heterojunction structure consisting of a conjugated polymer and an electron-accepting material. is important.

  As an excellent method capable of controlling the morphology of the conjugated polymer and the electron-accepting material, there is a method using a conjugated block copolymer. For example, Non-Patent Document 2 reports an organic thin film solar cell using a diblock copolymer of 3-hexylthiophene and 3- (2-ethylhexylthiophene). However, such a diblock copolymer is a polymer mainly having a polythiophene skeleton and cannot absorb light having an absorption wavelength longer than 650 nm, so that there is a limit to improvement in photoelectric conversion efficiency.

  On the other hand, with the aim of high conversion efficiency, a π-electron conjugated block using a π-electron conjugated polymer (hereinafter sometimes abbreviated as a narrow band gap polymer) that absorbs even longer wavelengths (near infrared region). Copolymers have also been proposed.

  Patent Document 1 discloses a π-electron conjugated block copolymer partially containing benzothiadiazole. However, in the production method described in Patent Document 1, it is difficult to control the reaction terminal of the polymer block, and a large amount of homopolymers that do not constitute a block copolymer are mixed because the terminal is missing. Therefore, when such a block copolymer is used as a photoelectric conversion active layer of an organic thin film solar cell, a phase separation structure between a conjugated polymer and an electron accepting material in a bulk heterojunction structure cannot be formed, and the conversion efficiency is 3 to 3. It remains at around 4%.

  Non-Patent Document 3 describes a method of synthesizing a π-electron conjugated block copolymer by polymerizing each polymer block separately and coupling them. However, in the method described in Non-Patent Document 3, a functional group involved in the coupling reaction is lost or modified by a catalyst, a base, water, or the like when isolating each polymer block. The homopolymer which does not perform is mixed, and the purity of the obtained π-electron conjugated block copolymer is lowered.

  As described in these prior art documents, in the π-electron conjugated block copolymer of the narrow band gap polymer, as a result of mixing impurities such as a homopolymer of a monomer that does not constitute the block copolymer, When the purity of the block copolymer is reduced and it is used as a photoelectric conversion active layer of an organic thin film solar cell, a phase separation structure between a conjugated polymer and an electron-accepting material in a bulk heterojunction structure cannot be formed, resulting in a decrease in photoelectric conversion efficiency. There is a problem of doing.

JP 2010-74127 A

Angew. Chem. Int. Ed, 47, 58 (2008) J. et al. Am. Chem. Soc. , 130, 7812 (2008) Macromolecules, 42, 1107 (2009)

  The present invention has been made to solve the above-described problems, and when used as a photoelectric conversion active layer of a photoelectric conversion element together with an electron-accepting material, an ideal phase separation structure can be formed in a bulk heterojunction structure. , A high-purity π-electron conjugated block copolymer having a low block efficiency and a high block efficiency, such as a monomer homopolymer as a raw material, and a method for producing the same, and the π-electron conjugated block copolymer It aims at providing the photoelectric conversion element which has the outstanding photoelectric conversion efficiency formed from the composition containing an electron-accepting material.

  The π-electron conjugated block copolymer according to claim 1, which has been made to achieve the above object, is a condensed π-electron conjugated skeleton having a thiophene ring as a part of a chemical structure, A π-electron conjugated system containing at least two polymer blocks including a monomer unit having a skeleton selected from a fluorene skeleton, a carbazole skeleton, a dibenzosilole skeleton, a dibenzogermole skeleton, and a bithiophene skeleton having a substituent. A block copolymer is characterized in that the polymer blocks are linked by a divalent group consisting of a monocyclic aromatic ring.

  The π-electron conjugated block copolymer according to claim 2 is the one described in claim 1, wherein the divalent group consisting of the monocyclic aromatic ring is benzene, thiophene, pyrrole, pyridine, pyrimidine. , Pyrazine, imidazole, or a group formed by removing two hydrogen atoms from furan.

で表されるいずれかの基を有し、−ｂ−は下記化学式（８）〜（１８）

で表されるいずれかの基を有する前記単量体単位（前記化学式（１）〜（１８）中、Ｖ^１は窒素（−ＮＲ^１−）、酸素（−Ｏ−）または硫黄（−Ｓ−）であり、Ｖ^２は炭素（−ＣＲ^１ _２−）、窒素（−ＮＲ^１−）、ケイ素（−ＳｉＲ^１ _２−）またはゲルマニウム（−ＧｅＲ^１ _２−）であり、Ｖ^３は−（Ａｒ）_ｍ−で表されるアリール基またはヘテロアリール基であり、Ｖ^４は窒素（−ＮＲ^１−）、酸素（−Ｏ−）または−ＣＲ^２＝ＣＲ^２−であり、Ｖ^５は酸素（Ｏ）または硫黄（Ｓ）である。Ｒ^１はそれぞれ独立に置換されていてもよい炭素数１〜１８のアルキル基であり、Ｒ^２はそれぞれ独立に水素原子または置換されていてもよい炭素数１〜１８のアルキル基であり、Ｒ^３はそれぞれ独立に置換されていてもよい炭素数１〜１８のアルキル基またはアルコキシ基であり、Ｒ^４はそれぞれ独立に水素原子、ハロゲン原子または置換されていてもよい炭素数１〜１８のアルキル基若しくはアリール基であり、Ｒ^５は置換されていてもよい炭素数１〜１８のアルキル基、アリール基、アルキルカルボニル基またはアルキルオキシカルボニル基であり、Ｒ^６は水素原子またはハロゲン原子である。ｍは０〜３の整数、ｎは０または１を表す。）であることを特徴とする。 The π-electron conjugated block copolymer according to claim 3 is the one described in claim 1 or 2, wherein at least one of the polymer blocks is a monomer unit-(ab). -A- represents the following chemical formulas (1) to (7)

-B- is represented by the following chemical formulas (8) to (18).

The monomer unit having any group represented by the formula (in the chemical formulas (1) to (18), V ¹ represents nitrogen (—NR ¹ —), oxygen (—O—) or sulfur (—S—). V ² is carbon (—CR ¹ ₂ —), nitrogen (—NR ¹ —), silicon (—SiR ¹ ₂ —) or germanium (—GeR ¹ ₂ —), and V ³ is — (Ar ) _m - in an aryl or heteroaryl group represented, ^{V 4} are nitrogen ^(-NR 1 -), oxygen (-O-) or ^{-CR 2} = CR 2 - is and, ^{V 5} is oxygen (O R ¹ is an optionally substituted alkyl group having 1 to 18 carbon atoms, and R ² is independently a hydrogen atom or optionally substituted 1 carbon atom. an ~ 18 alkyl group, optionally carbon also R ³ is optionally substituted independently An alkyl group or an alkoxy group having 1 to 18, R ⁴ are each independently a hydrogen atom, a halogen atom or a substituted carbon atoms and optionally 1 to 18 alkyl group or aryl group, R ⁵ is substituted And an alkyl group having 1 to 18 carbon atoms, an aryl group, an alkylcarbonyl group or an alkyloxycarbonyl group, R ⁶ is a hydrogen atom or a halogen atom, m is an integer of 0 to 3, and n is 0 or 1)).

The method for producing a π-electron conjugated block copolymer according to claim 4, wherein a condensed π-electron conjugated skeleton having a thiophene ring as part of a chemical structure, a fluorene skeleton, a carbazole skeleton, a dibenzosilole skeleton, and a dibenzogermol skeleton And a first polymer block containing a monomer unit having a skeleton selected from a bithiophene skeleton having a substituent, and the following chemical formula (i)
M ^r −L−M ^r (i)
(Wherein, ^{M r} independently of one another are halogen, boronic acid, boronic acid ester, -MgX, -ZnX, -SiX ₃ or -SnRa ₃ (however, X is a halogen atom, Ra is from 1 to 4 carbon atoms A straight-chain alkyl group) and L is a divalent group consisting of a monocyclic aromatic ring) to synthesize an intermediate, and a thiophene ring has a chemical structure in the intermediate A second polymer comprising a monomer unit having a skeleton selected from a condensed π-electron conjugated skeleton, a fluorene skeleton, a carbazole skeleton, a dibenzosilole skeleton, a dibenzogermole skeleton, and a bithiophene skeleton having a substituent. A monomer serving as a block is added and reacted to connect the first polymer block and the second polymer block with a divalent group comprising the monocyclic aromatic ring.

It manufacturing method of π-electron conjugated block copolymer according to claim 5, which has been described in claim 4, M ^r of the compound represented by the formula (i) is a halogen atom It is characterized by.

The method for producing a π-electron conjugated block copolymer according to claim 6 includes a condensed π-electron conjugated skeleton having a thiophene ring as a part of a chemical structure, a fluorene skeleton, a carbazole skeleton, a dibenzosilole skeleton, and a dibenzogermol skeleton. And a first polymer block containing a monomer unit having a skeleton selected from a bithiophene skeleton having a substituent, and the following chemical formula (i)
M ^r −L−M ^r (i)
(Wherein, ^{M r} independently of one another are halogen, boronic acid, boronic acid ester, -MgX, -ZnX, -SiX ₃ or -SnRa ₃ (however, X is a halogen atom, Ra is from 1 to 4 carbon atoms A straight-chain alkyl group) and L is a divalent group consisting of a monocyclic aromatic ring) to synthesize an intermediate, and the intermediate and the thiophene ring have a chemical structure A second polymer comprising a monomer unit having a skeleton selected from a condensed π-electron conjugated skeleton, a fluorene skeleton, a carbazole skeleton, a dibenzosilole skeleton, a dibenzogermole skeleton, and a bithiophene skeleton having a substituent. The block is reacted to connect the first polymer block and the second polymer block with a divalent group comprising the monocyclic aromatic ring.

  The method for producing a π-electron conjugated block copolymer according to claim 7 is the method according to any one of claims 4 to 6, wherein the compound represented by the chemical formula (i) It is characterized by using 1 mol to 100 mol with respect to 1 mol of the monomer constituting one polymer block.

  A composition according to an eighth aspect includes the π-electron conjugated block copolymer according to any one of the first to third aspects and an electron-accepting material.

  The photoelectric conversion device according to claim 9 has a layer made of the composition according to claim 8.

  The π-electron conjugated block copolymer of the present invention can form an ideal phase separation structure in a bulk heterojunction structure when used as a photoelectric conversion active layer of a photoelectric conversion element together with an electron accepting material. As a result, the current value increases and the resistance decreases, and the photoelectric conversion efficiency can be greatly improved.

  According to the method for producing a π-electron conjugated block copolymer of the present invention, it is possible to control terminal functional groups that are easy to link each polymer block and that are easily lost or modified, and the monomer as a raw material alone A high-purity π-electron conjugated block copolymer with few impurities such as a polymer can be obtained.

  The composition of the present invention is an organic semiconductor material, and can form an organic thin film useful for a photoelectric conversion element.

  The photoelectric conversion element of the present invention has excellent photoelectric conversion performance, and can be applied to various photoelectric conversion devices using a photoelectric conversion function and an optical rectification function.

  Hereinafter, although the preferable form for implementing this invention is demonstrated in detail, the scope of the present invention is not limited to these forms.

  The π-electron conjugated block copolymer of the present invention has at least two types of polymer blocks, and the polymer blocks are linked by a divalent group consisting of a monocyclic aromatic ring. is there. The polymer block is at least one selected from a condensed π-electron conjugated skeleton having a thiophene ring as a part of a chemical structure, a fluorene skeleton, a carbazole skeleton, a dibenzosilole skeleton, a dibenzogermol skeleton, and a bithiophene skeleton having a substituent. A monomer unit having a skeleton is included.

Examples of the condensed π-electron conjugated skeleton having the thiophene ring as a part of the chemical structure include, for example, thiophene rings such as cyclopentadithiophene, dithienopyrrole, dithienosilole, dithienogermole, benzodithiophene, and naphthodithiophene. Examples thereof include a skeleton of a condensed π electron conjugated compound having a part of the structure. These condensed ring π electron conjugated skeletons may have a substituent for the purpose of controlling solubility and polarity.
The fluorene skeleton, carbazole skeleton, dibenzosilole skeleton, and dibenzogermol skeleton may also have a substituent. Examples of the substituent that these condensed heterocyclic skeletons may have include an alkyl group, an alkoxy group, an aryl group, an alkylcarbonyl group, an alkyloxycarbonyl group, and a halogen atom. You may have. The number of alkyl carbon atoms in the substituent is preferably 1-18.

  The bithiophene having a substituent has at least one substituent, and examples thereof include those having the exemplified substituent. Especially, what has an alkyl group and an alkoxy group as a substituent is preferable. Specific examples of the bithiophene having a substituent include 4-4-di (2-ethylhexyl) -2,2′-bithiophene, 4-4-dioctyl-2,2′-bithiophene, and 4--4-didodecyl-2. , 2′-bithiophene and the like.

  The π-electron conjugated block copolymer of the present invention has at least two polymer blocks containing the monomer unit having the skeleton, and is not particularly limited. It is preferable from a viewpoint of photoelectric conversion efficiency that it has a polymer block which consists of (ab)-.

  Among the monomer units-(ab)-, -a- is a donor organic group (group having a skeleton showing electron donating properties), and -b- is an acceptor organic group (showing electron withdrawing properties). Group having a skeleton). The band gap of the monomer unit-(ab)-can be controlled by a combination of -a- and b-, and by reducing the band gap, the monomer unit-(ab)- The absorption wavelength of the polymer block becomes longer, and the polymer block comprising the monomer unit can have a light absorption band up to a long wavelength region. As a result, it is considered that the amount of sunlight absorbed increases and the photoelectric conversion efficiency is improved. -A- is selected from a condensed π-electron conjugated skeleton having a thiophene ring as part of its chemical structure, a fluorene skeleton, a carbazole skeleton, a dibenzosilole skeleton, a dibenzogermole skeleton, and a bithiophene skeleton having at least one substituent. It is preferably a group having a skeleton. Specific examples include groups represented by the chemical formulas (1) to (7). -B- is preferably any group represented by the chemical formulas (8) to (18).

In the chemical formulas (1) to (18), V ¹ is nitrogen (—NR ¹ —), oxygen (—O—) or sulfur (—S—), V ² is carbon (—CR ¹ ₂ —), Nitrogen (—NR ¹ —), silicon (—SiR ¹ ₂ —) or germanium (—GeR ¹ ₂ —), V ³ is an aryl group or heteroaryl group represented by — (Ar) _m —, V ⁴ is nitrogen (—NR ¹ —), oxygen (—O—) or —CR ² ═CR ² —, and V ⁵ is oxygen (O) or sulfur (S). n is 0 or 1. V ³ is a monocyclic or polycyclic aryl group or heteroaryl group (m is an integer of 0 to 3) represented by — (Ar) _m —, and is a part of the main chain skeleton in the monomer unit. is there. V ³ is particularly preferably a thiophene ring. Each polymer block constituting the π-electron conjugated block copolymer preferably has 6 to 40 total carbon atoms constituting the ring structure excluding the substituent in the monomer unit.

Each polymer block constituting the π-electron conjugated block copolymer of the present invention may have a substituent represented by R ^{1 to} R ⁶ in the chemical formula. R ¹ is an independently substituted alkyl group having 1 to 18 carbon atoms; R ² is independently a hydrogen atom or an optionally substituted alkyl group having 1 to 18 carbon atoms; ³ is an optionally substituted alkyl group or alkoxy group having 1 to 18 carbon atoms, and R ⁴ is independently a hydrogen atom, halogen atom or optionally substituted alkyl having 1 to 18 carbon atoms. R ⁵ is an optionally substituted alkyl group having 1 to 18 carbon atoms, an aryl group, an alkylcarbonyl group, or an alkyloxycarbonyl group, and R ⁶ is a hydrogen atom or a halogen atom. . When the monomer unit has a substituent at a plurality of positions, each may be different.

  Examples of the alkyl group having 1 to 18 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, Isopentyl group, neopentyl group, tert-pentyl group, n-hexyl group, isohexyl group, 2-ethylhexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, cyclopropyl group, cyclopentyl group , A cyclohexyl group, a cyclooctyl group, and the like.

  Examples of the alkoxy group having 1 to 18 carbon atoms include methoxy group, ethoxy group, n-propyloxy group, isopropyloxy group, n-butoxy group, n-hexyl group, cyclohexyloxy group, n-octyloxy group, n -Decyloxy group, n-dodecyloxy group, etc. are mentioned.

  Examples of the aryl group include a phenyl group, a 1-naphthyl group, a 2-naphthyl group, a 1-anthracenyl group, a 2-anthracenyl group, and a 9-anthracenyl group, which are further substituted with an alkyl group, an alkoxy group, or the like. It may have a group.

  Examples of the heteroaryl group include a pyridyl group, a thienyl group, a furyl group, a pyrrolyl group, a quinolyl group, and an isoquinolyl group.

The substituents represented by R ^{1 to} R ⁵ which each polymer block may have include an alkyl group, an alkoxy group, a halogen atom, a hydroxyl group, an amino group, a thiol group, a silyl group, an ester group, an aryl group, It may be further substituted with a heteroaryl group or the like. The alkyl group or alkoxy group which may be further substituted on the substituent may be linear, branched or alicyclic.

Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Examples of the alkyl group substituted with a halogen atom include an ω-bromoalkyl group and a perfluoroalkyl group.
Examples of the amino group include primary or secondary amino groups such as a dimethylamino group, a diphenylamino group, a methylphenylamino group, a methylamino group, and an ethylamino group.
Examples of the thiol group include a mercapto group and an alkylthio group. Examples of the silyl group include a trimethylsilyl group, a triethylsilyl group, a tripropylsilyl group, a triisopropylsilyl group, a dimethylisopropylsilyl group, and a dimethyl tert-butylsilyl group.
Examples of the ester group include a methoxycarbonyl group, an ethoxycarbonyl group, a propoxycarbonyl group, an isopropoxycarbonyl group, a tert-butoxycarbonyl group, a phenoxycarbonyl group, an acetyloxy group, and a benzoyloxy group.

  As the monomer unit-(ab)-, any combination of the donor organic group -a- and the acceptor organic group -b- may be used, and the combination of -a- and -b- It is not limited. From the viewpoint of forming a narrow band gap polymer, the combination of -a- and -b- includes the chemical formula (1), the chemical formula (8), the chemical formula (3), the chemical formula (18), and the chemical formula (3). And the chemical formula (17), the chemical formula (1), the chemical formula (16), the chemical formula (7), and the chemical formula (16). More specific examples of this combination include monomer units represented by the following chemical formulas (19) to (25). That is, examples of monomer units represented by chemical formulas-(1)-(8)-are chemical formulas (19), (20), and (21), and are represented by chemical formulas-(3)-(18)-. An example of the monomer unit is Chemical Formula (22), an example of the monomer unit represented by Chemical Formula-(3)-(17)-is Chemical Formula (23), and Chemical Formula-(1)- An example of a monomer unit represented by (16)-is chemical formula (24), and an example of a monomer unit represented by chemical formula-(7)-(16)-is chemical formula (25).

式中、Ｒ^１、Ｒ^２、Ｒ^３、Ｒ^４、Ｒ^５およびＲ^６は前記定義の通りである。

In the formula, R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are as defined above.

Each polymer block constituting the π-electron conjugated block copolymer may be a homopolymer comprising the same monomer including the structure of the substituent, or a polymer block having a plurality of types of monomer units. There may be. As a polymer block having a plurality of types of monomer units, for example, a random copolymer composed of monomer units-(ab)-and monomer units-(ab)-different from the monomer units-(ab)- This is a polymer block. Here, the random copolymer means that the ring skeletons constituting the main chain are different from each other, or the substituent R ⁿ (R ⁿ represents any ^one of R ^{1 to} R ⁶ in the above formula. The same as in the present specification) refers to a copolymer in which a plurality of different monomer units are randomly bonded.

  Each of these polymer blocks is preferably connected by a divalent group consisting of a monocyclic aromatic ring. The divalent group consisting of a monocyclic aromatic ring means a divalent group obtained by removing two hydrogen atoms from a monocyclic aromatic ring compound or heteroaromatic ring compound which is not condensed. Examples of such a divalent group include a group formed by removing two hydrogen atoms from benzene, thiophene, pyrrole, pyridine, pyrimidine, pyrazine, imidazole, furan and the like. The bond between the divalent group and each polymer block is preferably connected by a carbon-carbon bond. In particular, a divalent group obtained by removing two hydrogen atoms from benzene (phenylene group) and a divalent group obtained by removing two hydrogen atoms from thiophene (thienylene group) are suitable for linking polymer blocks. It is.

The divalent group may have a substituent. Examples of the substituent that the divalent group may have include an alkyl group, an alkoxy group, a halogen atom, a hydroxyl group, an amino group, a thiol group, a silyl group, and an ester group. Of these, an alkyl group and an alkoxy group are preferable from the viewpoint of increasing the solubility of the π-electron conjugated block copolymer. Specific examples of these substituents include the same ones as exemplified for the aforementioned R ^{1 to} R ⁶ .

  As a connection structure of the π-electron conjugated block copolymer of the present invention, any of a diblock structure, a triblock structure, a tetrablock structure, a pentablock structure, and a multiblock structure having higher structure can be taken. For example, when a polymer block A and a polymer block B different from the polymer block A are connected to a divalent group L, the connection structure includes an ALB type diblock copolymer, A -L-B-L-A type or B-L-A-L-B type triblock copolymer, A-L-B-L-A-L-B type or B-L-A-L-B -LA type tetrablock copolymer, A-LB-L-A-L-B-L-A type or B-L-A-L-B-L-A-L-B type pentablock A copolymer etc. are mentioned. Here, A and B each represent a polymer block, and L represents a divalent group. Further, it may be a multi-block copolymer having many types of blocks in which polymer blocks other than the polymer block A and the polymer block B are further connected by a divalent group L. However, if the number of polymer blocks is too large, the phase separation structure with the electron-accepting material is not sufficiently formed in the bulk heterojunction structure, which may reduce the conversion efficiency. From the viewpoint of conversion efficiency, an ALB type diblock copolymer is preferable.

  The connection position at which each polymer block and a divalent group comprising a monocyclic aromatic ring are not particularly limited. When the divalent group has a hetero atom on the aromatic ring, the carbon atom on the aromatic ring of the divalent group is bonded to the polymer block from the viewpoint of easy connection with each polymer block. It is preferable. Specific examples including the bonding position of the divalent group include 2,5-thienylene group, 2,4-thienylene group, 2,3-thienylene group; 1,4-phenylene group, 1,3-phenylene. Group, 1,2-phenylene group; pyridine-2,6-diyl group, pyridine-2,5-diyl group, pyridine-2,4-diyl group, pyridine-2,3-diyl group; pyrrole-2,5 -Diyl group, pyrrole 2,4-diyl group, pyrrole-2,3-diyl group; pyrazine-2,6-diyl group, pyrazine-2,5-diyl group; pyrimidine-2,5-diyl group, pyrimidine- 2,4-diyl group and the like can be mentioned.

  The composition ratio of each polymer block constituting the π-electron conjugated block copolymer of the present invention is not particularly limited, but if the ratio of one polymer block is too large, the photoelectric conversion efficiency is sufficient. May not be able to be increased. Preferably, in the case of the diblock copolymer having the polymer block A and the polymer block B, the weight ratio is A: B = 90: 10 to 10:90.

  The π-electron conjugated block copolymer of the present invention has the advantage that each polymer block is easily connected due to the presence of a divalent group consisting of a monocyclic aromatic ring. It is possible to increase the molecular weight. In general, the π-electron conjugated block copolymer preferably has a larger number average molecular weight from the viewpoints of processability, crystallinity, solubility, photoelectric conversion characteristics, and the like. The number average molecular weight of the π-electron conjugated block copolymer is preferably from 5,000 to 300,000 g / mol, and more preferably from 10,000 to 250,000 g / mol. If the number average molecular weight is too small, crystallinity, film stability, photoelectric conversion characteristics and the like are deteriorated. Here, the number average molecular weight means a molecular weight in terms of polystyrene by gel permeation chromatography (hereinafter sometimes referred to as GPC). The number average molecular weight of the π-electron conjugated block copolymer of the present invention can be determined by ordinary GPC using a solvent such as tetrahydrofuran (THF), chloroform, dimethylformamide (DMF) and the like. However, some π-electron conjugated block copolymers have low solubility near room temperature. In such cases, the number average molecular weight may be determined by high-temperature GPC chromatography using dichlorobenzene, trichlorobenzene, or the like as a solvent. .

  The π-electron conjugated block copolymer is a condensed π-electron conjugated skeleton having a thiophene ring as part of its chemical structure, a fluorene skeleton, a carbazole skeleton, a dibenzosilole skeleton, and a dibenzogermol skeleton unless the effects of the present invention are impaired. In addition to at least two polymer blocks containing a monomer unit having a skeleton selected from a bithiophene skeleton having a substituent, other monomer components copolymerizable with the monomer unit may be included. Good. Examples of such other monomer components include -a-single component represented by the above formulas (2) to (8) and -b-single represented by the above formulas (9) to (19). Components, or other components containing a monocyclic or condensed (hetero) arylene group. When the π-electron conjugated block copolymer of the present invention contains other monomer components, these may be linked by a divalent group consisting of a monocyclic aromatic ring, or 2 consisting of a monocyclic aromatic ring. You may couple | bond with each polymer block irrespective of a valence group.

  The π electron conjugated block copolymer may include a polymer block made of a non-π electron conjugated polymer as the arbitrary polymer block C. Examples of monomers constituting the block include aromatic vinyl compounds (styrene, chloromethyl styrene, vinyl pyridine, vinyl naphthalene, etc.), (meth) acrylic acid esters (methyl (meth) acrylate, (meth) acrylic). Acid ester, hydroxyethyl (meth) acrylate, etc.), vinyl esters (vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate, etc.), and alpha hydroxy acids (lactic acid, glycolic acid, etc.).

  In consideration of the fact that the polymer block C is a non-π electron conjugated polymer and does not contribute to photoelectric conversion, the proportion of the polymer block C in the π electron conjugated block copolymer is 30% by mass or less. More preferably, it is still more preferably 20% by mass or less.

  Next, each reaction process and a manufacturing method are demonstrated as an example of the manufacturing method of the (pi) electron conjugated block copolymer of this invention.

  The first method for producing a π-electron conjugated block copolymer is to synthesize each polymer block (for example, the first polymer block and the second polymer block) separately and link them together. There is a method (hereinafter sometimes referred to as “consolidation method”). As the second method, in the presence of one polymer block (first polymer block) among the constituent polymer blocks, a monomer that becomes another polymer block (second polymer block) is added. There is a method of linking while polymerizing (hereinafter sometimes referred to as “macroinitiator method”). As the linking method and the macroinitiator method, an optimum method can be used depending on the π-electron conjugated block copolymer to be synthesized.

  Hereinafter, a method for producing a π-electron conjugated block copolymer having a polymer block A and a polymer block B connected by a divalent group L composed of a monocyclic aromatic ring will be described in detail.

When producing the π-electron conjugated block copolymer by coupling method, as shown in the following reaction formula (I), the compound B-X with a compound A-M ^p and the polymer block B having a polymer block A Can be produced by carrying out a coupling reaction in the presence of a catalyst.

式（Ｉ）中、ＡおよびＢは重合体ブロック、Ｘはハロゲン原子、Ｍ^ｐはボロン酸、ボロン酸エステル、−ＭｇＸ、−ＺｎＸ、−ＳｉＸ_３または−ＳｎＲａ_３(ただしＲａは炭素数１〜４の直鎖アルキル基)、Ｌは単環芳香環からなる２価の基を表す。ＸおよびＭ^ｐはカップリング反応に関与する末端官能基である。

In formula (I), A and B are polymer blocks, X is a halogen atom, M ^p is boronic acid, boronic acid ester, -MgX, -ZnX, -SiX ₃ or -SnRa ₃ (where Ra is 1 to 4 linear alkyl group), L represents a divalent group consisting of a monocyclic aromatic ring. X and M ^p are terminal functional groups involved in the coupling reaction.

Polymer block A and polymer block B may be the interchanged terminal substituents, as illustrated in the following reaction formula (II), the compound B-M ^p and the polymer block A having a polymer block B It can also manufacture by performing a coupling reaction with the compound AX which has it in the presence of a catalyst.

式（ＩＩ）中、Ａ、Ｂ、Ｘ、Ｍ^ｐ、Ｌは前記と同義である。

In the formula (II), A, B, X, M ^p and L are as defined above.

X and M ^q possessed by the polymer block A and the polymer block B may be lost or modified by a catalyst, a base, water or the like. Therefore, the following chemical formula (i) having a stable functional group ^Mr
M ^r −L−M ^r (i)
The terminal functional group can be prevented from being lost by bonding a compound represented by the formula (hereinafter sometimes referred to as a linker compound) to the terminal. L is a divalent group consisting of a single aromatic ring as defined in the, ^{M r} independently of one another, a halogen atom, boronic acid, boronic acid ester, -MgX, -ZnX, -SiX ₃ or -SnRa ₃ Where Ra is a linear alkyl group having 1 to 4 carbon atoms. The M ^r, from the viewpoint of stability in the coupling reaction, a halogen atom, preferably a boronic acid or boronic acid ester, in particular a halogen atom.

In Reaction Scheme (I) and (II), when allowed to act linker compound, at least one of M ^p or wherein X means M ^r. That is, the intermediate to introduce M ^r as terminal functional groups by reacting a linker compound on at least one polymer block of the polymer block A and polymer block B, M ^p as terminal functional ^groups, X or M ^r The π-electron conjugated block copolymer of the present invention can be produced by coupling and coupling with the other polymer block. It is also possible that a linker compound is bonded to both the polymer block A and the polymer block B, and both polymer blocks are linked by ^Mr derived therefrom.

Next, the macro initiator method will be described. Macroinitiator method, the polymerization initial compound A-X or A-M ^p having a polymer block A polymer block B, or polymerization medium term to coexist is a technique to carry out the polymerization of the polymer block B. The polymerization initial compound B-X or B-M ^p a polymer block A having a polymer block B, or polymerization medium term to coexist may be carried out polymerization of the polymer block A, [pi electrons of interest The optimum order can be selected depending on the conjugated block copolymer.

If described in more detail, in the presence of a compound A-X and catalyst having polymer block A according to the following reaction formula (III), and M ^{q1 -Y-M q1} monomeric polymer block B M ^q2 -ZM ^q2 is reacted, and the terminal of the polymer block A and the monomer of the polymer block B or the polymer block B are bonded during the polymerization by a coupling reaction. An electron conjugated block copolymer can be obtained. Further, the presence of a compound ^{A-M p} and catalyst having polymer block A according to the following reaction formula (IV), is a monomer of the polymer block B ^{M q1 -Y-M} q1 and ^M q2 -Z- By reacting M ^q2 and coupling the terminal of the polymer block A and the monomer of the polymer block B or the polymer block B during the polymerization by a coupling reaction, the π-electron conjugated block copolymer of the present invention is combined. A polymer can be obtained. Here, by combining the intermediate is reacted with the linker compound represented by Formula to the compound A-X and A-M ^p having a polymer block A (i), similar to the above polymer block A As a terminal functional group, stable ^Mr can be introduced, and the polymer block B can be efficiently linked.

Similarly, M ^q1 -YM ^q1 and M ^q2 -ZM which are monomers of the polymer block A in the presence of the compound BX having the polymer block B and a catalyst according to the reaction formula (III) By reacting ^q2 and coupling the terminal of the polymer block B and the monomer of the polymer block A or the polymer block A during the polymerization by a coupling reaction, Coalescence can be obtained. Further, the presence of a compound ^{B-M p} and catalyst having polymer block B in accordance with the reaction formula (IV), is a monomer of the polymer block A ^{M q1 -Y-M} q1 and ^M q2 -Z-M By reacting ^q2 and coupling the terminal of the polymer block B and the monomer of the polymer block A or the polymer block A during the polymerization by a coupling reaction, Coalescence can be obtained. Here, by combining the intermediate is reacted with a compound B-X and the linker compound represented by the chemical formula B-M ^p (i) having a polymer block B, similarly to the above, the polymer block B As a terminal functional group, stable ^Mr can be introduced, and the polymer block A can be efficiently linked.

In formulas (III) and (IV), A, B, X, M p and L are as defined above, when allowed to act linker compound, X and ^{M p} denotes an ^{M r.} M ^q1 and M ^q2 are not the same and are each independently a halogen atom, or boronic acid, boronic acid ester, —MgX, —ZnX, —SiX ₃ or —SnRa ₃ (where Ra is a linear alkyl having 1 to 4 carbon atoms) Group X is the same as defined above. That is, when M ^q1 is a halogen atom, M ^q2 is boronic acid, boronic acid ester, —MgX, —ZnX, —SiX ₃ or —SnRa ₃ , and conversely, when M ^q2 is a halogen atom, M ^q1 is boronic acid. , Boronic acid ester, —MgX, —ZnX, —SiX ₃ or —SnRa ₃ . Y and Z represent the skeleton constituting at least a part of the monomer unit of the π-electron conjugated block copolymer of the present invention, for example, any one of the chemical formulas (1) to (18) It is a heteroaryl skeleton having a group. A-LB, which is a product of the reaction formula, is a block copolymer including a copolymer of Y and Z.

The compound AX or A-M ^p having the polymer block A and the compound BX or B-M ^p having the polymer block B are present according to the following reaction formulas (V) and (VI). can be a ^{M q1 -Y-M} q1 and ^{M q2 -Z-M} q2 is monomeric under reacted, prepared by the coupling reaction.

When produced in this manner, X or M ^p possessed by the compounds AX, A-M ^p , B-X, and B-M ^p is the terminal functional group of the polymer block A or the polymer block B, and is usually a single functional group. a functional group derived from the ^{M q1 -Y-M} q1 and ^{M q2 -Z-M} q2 is dimer.

In the case of producing compound AX or A-M ^p , compound BX or B-M ^p according to the above reaction formulas (V) and (VI), monomers M ^q1 -YM ^q1 and M ^q2 the terminal of the polymer block is controlled to either one of M ^q1 or M ^q2 by charged more than an equimolar ratio either one of the -Z-M ^q2, also be introduced M ^r from linker compound Is possible. However, if either one of M ^q1 -Y-M ^q1 and M ^q2 -Z-M ^q2 is added excessively, the polymerization will not proceed, so M ^q1 -Y-M ^q1 and M ^q2 -Z-M ^q2 The molar ratio is preferably 0.5 to 1.5, more preferably 0.7 to 1.3.

The linker compound represented by the chemical formula (i) used in the production method will be described. L is a divalent group consisting of the monocyclic aromatic ring defined above, and examples thereof include the same ones as exemplified above. From the viewpoint of reactivity and availability, L is preferably a thienylene group or a phenylene group which may have a substituent. ^Mr is preferably a halogen atom, a boronic acid or a boronic ester. Specific examples of the linker compound include 2,5-dibromothiophene, 2,5-thiophenediboronic acid, 2,5-bis (3,3,4,4-tetramethyl-2,5,1-dioxaborolane. -1-yl) thiophene, 1,4-dibromobenzene, 1,4-benzenediboronic acid, 1,4-bis (3,3,4,4-tetramethyl-2,5,1-dioxaborolane-1 -Yl) benzene and the like.

The linker compound M ^r -L-M ^r is introduced into the monomer block M ^q1 -Y-M ^q1 and M ^q2 -ZM ^q2 in the early stage, middle stage or late stage of the polymer block. It is possible to introduce ^Mr derived from a linker compound. The linker compound is preferably introduced at the late stage of polymerization. Here, a method of introducing ^Mr as a terminal functional group without using a linker compound by reacting a terminal blocker or the like after polymerization of the polymer block and then functionalizing the polymer block can be considered. Then, it is difficult to completely introduce ^Mr at the end of the polymer block, and there is a possibility that functional groups other than the target portion may be functionalized.

The amount of the linker compound represented by the chemical formula (i) used is preferably 1 mol or more, more preferably 1 mol per monomer unit constituting the polymer block in both the linking method and the macroinitiator method. Is 5 mol or more, particularly preferably 10 mol or more. By adding linker compound in a very excessive amount relative to the terminal functional groups of the resulting polymer block, the M ^r of from linker compound can be introduced preferentially as terminal functional groups of the polymer block . Although an upper limit is not specifically limited, It is preferable that it is 100 mol or less of linker compounds with respect to 1 mol of monomer units which comprise a polymer block from an economical viewpoint, and it is more preferable that it is 30 mol or less.

  Examples of the catalyst used in each reaction include transition metal complexes having metals such as Ni, Pd, Ti, Zr, V, Cr, Co, and Fe. Of these, Ni complexes and Pd complexes are more preferable. Moreover, as a ligand of the complex to be used, a monodentate phosphine ligand such as triphenylphosphine; a bidentate phosphine ligand such as 1,3-diphenylphosphinopropane (dppp); tetramethylethylenediamine, bipyridine, acetonitrile It is preferable that nitrogen-containing ligands such as are contained.

  In addition, although the usage-amount of a catalyst changes with kinds of (pi) electron conjugated system block copolymer to manufacture, 0.001-0.1 mol is preferable with respect to 1 mol of monomers. Too much catalyst causes a decrease in the molecular weight of the resulting polymer, and is also economically disadvantageous. On the other hand, if the amount is too small, the reaction rate becomes slow and stable production becomes difficult.

  The π-electron conjugated block copolymer of the present invention is preferably produced in the presence of a solvent. The solvent that can be used for the production needs to be selected depending on the type of the π-electron conjugated block copolymer to be produced, but a commercially available solvent can be generally selected. For example, ether systems such as tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, dimethyl ether, ethyl methyl ether, diethyl ether, dipropyl ether, butyl methyl ether, t-butyl methyl ether, dibutyl ether, cyclopentyl methyl ether, diphenyl ether Solvent, aliphatic or alicyclic saturated hydrocarbon solvent such as pentane, hexane, heptane, cyclohexane, aromatic hydrocarbon solvent such as benzene, toluene, xylene, alkyl halide solvent such as dichloromethane, chloroform, chlorobenzene, Aromatic aryl halide solvents such as dichlorobenzene, amide solvents such as dimethylformamide, diethylformamide, N-methylpyrrolidone, water, and these And mixtures thereof. The amount of the organic solvent used is preferably in the range of 1 to 1000 times the weight of the monomer of the π-electron conjugated block copolymer to be produced, and the solubility of the resulting linked body and the stirring efficiency of the reaction solution From the viewpoint of the above, it is preferably 10 times by weight or more, and from the viewpoint of the reaction rate, it is preferably 100 times by weight or less.

  In this invention, although superposition | polymerization temperature changes with kinds of (pi) electron conjugated system block copolymer to manufacture, it is normally implemented in the range of -80 degreeC-200 degreeC. In the present invention, the pressure of the reaction system is not particularly limited, but is preferably 0.1 to 10 atm. The reaction is usually carried out at around 1 atm. The reaction time varies depending on the π-electron conjugated block copolymer to be produced, but is usually 20 minutes to 100 hours.

  The resulting π-electron conjugated block copolymer is a π-electron conjugated system such as reprecipitation, solvent removal under heating, solvent removal under reduced pressure, solvent removal with steam (steam stripping), etc. The block copolymer can be separated and obtained from the reaction mixture by a normal operation for isolating the block copolymer from the solution. The obtained crude product can be purified by washing or extracting with a commercially available solvent using a Soxhlet extractor.

  The resulting π-electron conjugated block copolymer is a π-electron conjugated block copolymer such as reprecipitation, solvent removal under heating, solvent removal under reduced pressure, or solvent removal with steam (steam stripping). By separating the polymer from the solution, it can be separated from the by-product and obtained by a normal operation.

  In the π-electron conjugated block copolymer of the present invention, as a terminal group, a coupling residue such as a halogen atom, a trialkyltin group, a boronic acid group, or a boronic ester group, or those atoms or groups are eliminated. The terminal structure may have a hydrogen atom, and these terminal groups may be substituted with an end capping agent made of an aromatic halide such as benzene bromide or an aromatic boronic acid compound. .

  As long as the effects of the present invention are not impaired, homopolymers such as polymer block A and polymer block B, random polymers, etc. remain in the π-electron conjugated block copolymer produced by the above method. Also good.

  The π-electron conjugated block copolymer of the present invention is a composition that forms an organic thin film useful as a photoelectric conversion active layer of a photoelectric conversion element by mixing with an electron accepting material.

The electron-accepting material contained in the composition of the present invention is not particularly limited as long as it is an organic material exhibiting n-type semiconductor characteristics. Examples of the electron accepting material, for _example, fullerene derivatives such as _{C 60} or _{C 70,} naphthalene tetracarboxylic dianhydride (NTCDA), perylenetetracarboxylic dianhydride (PTCDA), N, N'-dioctyl - Nafuchirutetora Carboxydiimide (NTCDI-C ₈ H), oxazole derivatives, triazole derivatives, phenanthroline derivatives, carbon nanotubes (CNT), poly-p-phenylene vinylene-based polymer derivatives (CN-PPV), etc. . These may be used alone or in combination of two or more. Among these, fullerene derivatives are preferably used from the viewpoint of an n-type semiconductor that is stable and excellent in carrier mobility.

Examples of the fullerene derivative suitably used as the electron-accepting material include, for example, unsubstituted ones such as C ₆₀ , C ₇₀ , C ₇₆ , C ₇₈ , C ₈₂ , C ₈₄ , C ₉₀ , C ₉₄ , and [ 6,6] - phenyl _{C 61} butyric acid methyl ester _{([6,6] -C 61 -PCBM)} , [5,6] - phenyl _{C 61} butyric acid methyl ester, [6,6] - phenyl _{C 61} Butyric acid n-butyl ester, [6,6] -phenyl C ₆₁ butyric acid i-butyl ester, [6,6] -phenyl C ₆₁ butyric acid hexyl ester, [6,6] -phenyl C ₆₁ buty Rick acid dodecyl ester, [6,6] -diphenyl C ₆₂ bis (butyric acid methyl ester) ([6,6] -C _{6 2 -bis-PCBM), [6,6} ] - and substituted derivatives including phenyl _{C 71} butyric acid methyl ester _([6,6] -C 71 -PCBM) and the like. These fullerene derivatives can be used alone or as a mixture. From the viewpoint of solubility in organic solvents, [6,6] -C ₆₁ -PCBM, [6,6] -C ₆₂ -bis-PCBM), [ 6,6] -C ₇₁ -PCBM is preferably used.

  The ratio of the electron-accepting material in the composition of the present invention is preferably 10 to 1000 parts by weight, and preferably 50 to 500 parts by weight with respect to 100 parts by weight of the π-electron conjugated block copolymer. More preferred.

  The mixing method of the π-electron conjugated block copolymer and the electron-accepting material is not particularly limited. However, after adding the solvent in a desired ratio, heating, stirring, ultrasonic irradiation, etc. The method of making it a solution by making it melt | dissolve in a solvent combining seeds or multiple types is mentioned.

  Although it does not specifically limit as a solvent, It is preferable from a viewpoint on organic thin film forming to use the solvent whose solubility in 20 degreeC is 1 mg / mL or more about each of (pi) electron conjugated block copolymer and an electron-accepting material. When the solubility is less than 1 mg / mL, it is difficult to produce a homogeneous organic thin film, and the composition of the present invention cannot be obtained. Furthermore, from the viewpoint of arbitrarily controlling the thickness of the organic thin film, it is more preferable to use a solvent having a solubility at 20 ° C. of 3 mg / mL or more for each of the π-electron conjugated block copolymer and the electron-accepting material. . Further, the boiling point of these solvents is preferably in the range of room temperature to 200 ° C. from the viewpoint of film forming properties and the manufacturing process described later.

  Examples of the solvent include tetrahydrofuran, 1,2-dichloroethane, cyclohexane, chloroform, bromoform, benzene, toluene, o-xylene, chlorobenzene, bromobenzene, iodobenzene, o-dichlorobenzene, anisole, methoxybenzene, trichlorobenzene, and pyridine. Etc. These solvents may be used singly or in combination of two or more types. Particularly, o-dichlorobenzene, chlorobenzene, bromobenzene having high solubility of π electron conjugated block copolymer and electron accepting material. , Iodobenzene, chloroform and mixtures thereof are preferred. More preferably, o-dichlorobenzene, chlorobenzene and a mixture thereof are used.

  The solution may contain an additive having a boiling point higher than that of the solvent in addition to the π-electron conjugated block copolymer and the electron-accepting material. In the process of forming an organic thin film by adding an additive, a fine and continuous phase separation structure of a π-electron conjugated block copolymer and an electron-accepting material is formed, so that photoelectric conversion is excellent in photoelectric conversion efficiency. An active layer can be obtained. Examples of the additive include octanedithiol (boiling point: 270 ° C.), dibromooctane (boiling point: 272 ° C.), diiodooctane (boiling point: 327 ° C.), and the like.

  The addition amount of the additive used in the present invention is not particularly limited as long as the π-electron conjugated block copolymer and the electron-accepting material do not precipitate and give a uniform solution, but the volume fraction with respect to the solvent It is preferably 0.1% to 20%. When the additive amount is less than 0.1%, a sufficient effect cannot be obtained to form a fine and continuous phase separation structure. When the additive amount is more than 20%, The drying speed becomes slow and it becomes difficult to obtain a homogeneous organic thin film. More preferably, it is in the range of 0.5% to 10%.

  The composition of the present invention may contain other components such as a surfactant, a binder resin, and a filler as long as the object of the present invention is not impaired.

  The photoelectric conversion element using the organic thin film obtained from the composition of the present invention can generate electric power when the composition containing a π-electron conjugated block copolymer and an electron-accepting material functions as a photoelectric conversion active layer. it can.

  The film thickness of the photoelectric conversion active layer is usually 1 nm to 1 μm, preferably 2 nm to 1000 nm, more preferably 5 nm to 500 nm, and further preferably 20 nm to 300 nm. If the film thickness is too thin, the light is not sufficiently absorbed, and conversely if it is too thick, the carriers are difficult to reach the electrode.

  The method for coating a solution containing a π-electron conjugated block copolymer and an electron-accepting material on a substrate or a support is not particularly limited, and a conventionally known coating using a liquid coating material. Any of the methods can be employed. For example, a coating method such as a dip coating method, a spray coating method, an ink jet method, a spin coating method can be adopted, and a coating method depending on the properties of the coating film to be obtained, such as coating thickness control and orientation control. Should be selected.

  The photoelectric conversion active layer may be further subjected to thermal annealing as necessary. Thermal annealing is performed by holding the substrate on which the organic thin film is formed at a desired temperature. Thermal annealing may be performed under reduced pressure or in an inert gas atmosphere, and a preferable temperature is 40 ° C to 300 ° C, more preferably 70 ° C to 200 ° C. If the temperature is low, a sufficient effect cannot be obtained, and if the temperature is too high, the organic thin film is oxidized and / or decomposed, and sufficient photoelectric conversion characteristics cannot be obtained.

  The substrate on which the photoelectric conversion element of the present invention is formed may be any substrate that does not change when an electrode or a photoelectric conversion active layer is formed. For example, inorganic materials such as alkali-free glass and quartz glass, metal films such as aluminum, and any organic material such as polyester, polycarbonate, polyolefin, polyamide, polyimide, polyphenylene sulfide, polyparaxylene, epoxy resin and fluorine resin Films and plates produced by the method can be used. In the case of using an opaque substrate, the opposite electrode (that is, the electrode far from the substrate) is preferably transparent or translucent. Although the film thickness of a board | substrate is not specifically limited, Usually, it is the range of 1 micrometer-10 mm.

  In the photoelectric conversion element of the present invention, it is preferable that either the positive electrode or the negative electrode have optical transparency. The light transmittance of the electrode is not particularly limited as long as incident light reaches the photoelectric conversion active layer and an electromotive force is generated. The thickness of the electrode may be in a range having light transparency and conductivity, and is preferably 20 nm to 300 nm, although it varies depending on the electrode material. The other electrode is not necessarily light-transmitting as long as it has conductivity, and the thickness is not particularly limited.

  The positive electrode included in the photoelectric conversion element is a metal such as lithium, magnesium, calcium, tin, gold, platinum, silver, copper, chromium, or nickel, and the transparent electrode is a metal oxide such as indium or tin, or a composite metal. Oxides (indium tin oxide (ITO), indium zinc oxide (IZO), fluorine-doped tin oxide (FTO), etc.) are preferably used. Transparent organic conductor films such as derivatives, polythiophene and derivatives thereof may be used, and methods for producing the positive electrode include vacuum deposition, sputtering, ion plating, and plating. , Metal paste, low-melting-point metal, organic conductor ink, etc. are used to fabricate the positive electrode Rukoto can also.

  The photoelectric conversion element of this invention may provide a positive hole transport layer between a positive electrode and a photoelectric conversion active layer as needed. The material for forming the hole transport layer is not particularly limited as long as it has p-type semiconductor characteristics. However, polythiophene polymers, polyaniline polymers, poly-p-phenylene vinylene polymers, polyfluorene polymers are not limited. Conductive polymers such as coalescence, low molecular organic compounds exhibiting p-type semiconductor properties such as phthalocyanine derivatives (such as H2Pc, CuPc, and ZnPc), porphyrin derivatives, and metal oxides such as molybdenum oxide, zinc oxide, and vanadium oxide are preferable. Used. The thickness of the hole transport layer is preferably 1 nm to 600 nm, more preferably 20 nm to 300 nm.

  When preparing a hole transport layer between the positive electrode and the photoelectric conversion active layer, for example, in the case of a conductive polymer soluble in a solvent, a liquid such as a dip coating method, a spray coating method, an ink jet method, a spin coating method, etc. It can apply | coat by the coating method conventionally known using the coating material of this. When using a low molecular weight organic material such as a phthalocyanine derivative or a porphyrin derivative, it is preferable to apply a vapor deposition method using a vacuum vapor deposition machine.

  The photoelectric conversion element of this invention may provide an electron carrying layer between a negative electrode and a photoelectric conversion active layer as needed. The material for forming the electron transport layer is not particularly limited as long as it has n-type semiconductor properties, but the above-described electron-accepting organic materials (NTCDA, PTCDA, NTCDI-C8H, oxazole derivatives, triazole derivatives, phenanthroline derivatives, Fullerene derivatives, CNT, CN-PPV, etc.) are preferably used. The thickness of the electron transport layer is preferably 1 nm to 600 nm, more preferably 5 nm to 100 nm. The electron transport layer can be produced by the same method as the hole transport layer.

  The photoelectric conversion element is a metal fluoride such as lithium fluoride, sodium fluoride, potassium fluoride, magnesium fluoride, calcium fluoride, cesium fluoride, more preferably lithium fluoride between the negative electrode and the photoelectric conversion active layer. It is also possible to improve the extraction current by introducing cesium fluoride.

  The photoelectric conversion element of the present invention can be applied to various photoelectric conversion devices using a photoelectric conversion function, an optical rectification function, and the like. For example, it is useful for photovoltaic cells such as solar cells, optical sensors, optical switches, electronic elements such as phototransistors, optical recording materials such as optical memories, and the like.

  Examples of the present invention will be described in detail below, but the scope of the present invention is not limited to these examples.

Synthesis of polymer blocks constituting the π-electron conjugated block copolymer of the present invention is shown in Polymerization Examples 1 to 5, and examples of block copolymer synthesis using the polymer blocks obtained in the polymerization examples are shown. Shown in 1-8. Further, synthesis of a polymer block constituting a block copolymer which is not applicable to the present invention is shown in Comparative Polymerization Examples 1 and 2, and a block copolymer using the polymer block obtained in the Comparative Polymerization Example is shown. The synthesis is shown in Comparative Examples 1 and 2.
The physical property measurement and purification in each of these steps were performed as follows.

<Weight average molecular weight / number average molecular weight>
The weight average molecular weight (Mw) and the number average molecular weight (Mn) are both determined in terms of polystyrene based on measurement by gel permeation chromatography (GPC). Here, HLC-8320 (product number) manufactured by Tosoh Co., Ltd. was used as the GPC apparatus, and TSKgel Multipore HZ manufactured by Tosoh Corporation was connected in series as the column. The column and injector were 40 ° C., and chloroform was used as the elution solvent.
However, the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the polymers of Examples 5 to 8, Comparative Example 2, and Polymerization Examples 2 to 4 are all GPC / V2000 manufactured by Waters as a GPC device. As a column, a column in which two Shodex AT-G806MS manufactured by Showa Denko KK were connected in series was used. The column and injector were 145 ° C., and o-dichlorobenzene was used as an elution solvent.

<Purification of polymer>
The polymer was purified using a preparative GPC column. As the apparatus used, Recycling Preparative HPLC LC-908 manufactured by Nippon Analytical Industrial Co., Ltd. was used. In addition, the kind of column connects the two styrene-type polymer columns 2H-40 and 2.5H-40 by Nippon Analysis Industry Co., Ltd. in series. Further, chloroform was used as an elution solvent.

<Purification of solvent (THF)>
The solvent was dehydrated tetrahydrofuran (THF) (without stabilizer) manufactured by Wako Pure Chemical Industries, Ltd. in the presence of metallic sodium and purified over molecular sieves 5A manufactured by Wako Pure Chemical Industries, Ltd. for a day or more. Purification was carried out by contact.

<Measurement of ¹ H-NMR>
JEOLJNM-EX270FT-NMR apparatus manufactured by JEOL Ltd. was used for ¹ H-NMR measurement. In the present specification, unless otherwise specified, ¹ H-NMR is measured at 270 MHz, the solvent is chloroform (CDCl ₃ ), and measured at room temperature.

(Polymerization example 1)
Polymer block A1 was synthesized according to the following reaction formula. In the following reaction formula, EtHex = ethylhexyl is indicated, and p is a repeating unit of the polymer block A. The same applies to other polymerization examples, examples and comparative examples.

In a 100 mL three-necked flask under a nitrogen atmosphere, 2,6-dibromo-4,4′-bis (2-ethylhexyl) -cyclopenta [2,1-b: 3,4-b ′] dithiophene (1.50 g, 2.68 mmol). ), 4,7-bis (3,3,4,4-tetramethyl-2,5,1-dioxaborolan-1-yl) benzo [c] [1,2,5] thiadiazole (1.08 g, 2. 68 mmol), toluene (51 mL), 0.21 M aqueous potassium carbonate solution (51 mL, 10.7 mmol), tetrakis (triphenylphosphine) palladium (0) (Pd (PPh ₃ ) ₄ ; 62.0 mg, 54.0 μmol), aliquat 336 (2 mg, 4.95 μmol) was added, followed by stirring at 80 ° C. for 1 hour. Thereafter, 2,5-dibromothiophene (6.47 g, 26.8 mmol) was added as a linker compound, and the mixture was stirred at 80 ° C. for 16 hours. After completion of the reaction, the reaction solution was poured into methanol (500 mL), the precipitated solid was collected by filtration, washed with water (100 mL) and methanol (100 mL), and the resulting solid was dried under reduced pressure to obtain a crude product. It was. The crude product was washed with acetone (200 mL) and hexane (200 mL) using a Soxhlet extractor and then extracted with chloroform (200 mL). The organic layer was concentrated to dryness, and the resulting black purple solid was dissolved in chloroform (30 mL) and reprecipitated with methanol (300 mL). The obtained solid was collected by filtration and dried under reduced pressure to obtain a black purple solid (1.24 g, 87%). Thereafter, purification was performed using a GPC preparative column to obtain a polymer block A1 as a black purple solid (0.54 g, 38%). The resulting polymer block A1 had a weight average molecular weight of 29,800, a number average molecular weight of 18,600, and a polydispersity of 1.60.
¹ H-NMR (270 MHz, CDCl ₃ ), (ppm): δ = 8.10-7.95 (m, 2H), 7.80-7.61 (m, 2H), 2.35-2.12 (M, 4H), 1.60-1.32 (m, 18H), 1.18-0.82 (m, 12H)

(Polymerization example 2)
Polymer block A2 was synthesized according to the following reaction formula. In the following reaction formulae, Me = methyl and 3-Hep = hept-3-yl are shown. The same applies to other polymerization examples, examples and comparative examples.

As a monomer constituting the polymer block A2 in a 100 mL three-necked flask under a nitrogen atmosphere, 2,6-bis (trimethyltin) -4,8-didodecylbenzo [1,2-b: 4,5-b ′ ] Dithiophene (0.74 g, 0.87 mmol), 1- (4,6-dibromothieno [3,4-b] thiophen-2-yl) -2-ethylhexane-1-one (0.32 g, 0.75 mmol) ), DMF (1.1 mL), toluene (4.3 mL), tetrakis (triphenylphosphine) palladium (0) (9.2 mg, 7.8 μmol) were added, and the mixture was heated at 115 ° C. for 1 hour 30 minutes. Next, 2,5-dibromothiophene (1.84 g, 7.6 mmol) was added as a linker compound and heated at 115 ° C. for 8 hours. After completion of the reaction, the reaction solution was poured into methanol (500 mL), the precipitated solid was collected by filtration, and the obtained solid was dried under reduced pressure to obtain a crude product. The crude product was washed with acetone (200 mL) and hexane (200 mL) using a Soxhlet extractor and then extracted with chloroform (200 mL). The organic layer was concentrated to dryness, and the resulting black purple solid was dissolved in chloroform (30 mL) and reprecipitated with methanol (300 mL). The obtained solid was collected by filtration and dried under reduced pressure to obtain polymer block A2 (0.51 g, 86%) as a black purple solid. The resulting polymer block A2 had a weight average molecular weight of 45,000, a number average molecular weight of 18,000, and a polydispersity of 2.5.
¹ H-NMR (270 MHz, CDCl ₃ ): δ = 7.60-7.30 (br, 3H), 3.30-3.00 (Br, 5H), 2.00-1.10 (br, 52H) ), 1.00-0.70 (br, 12H)

(Polymerization example 3)
A polymer block A3 was obtained using the same method as in Polymerization Example 2 except that 1,4-dibromobenzene (1.79 g, 7.6 mmol) was used as the linker compound (0.53 g, 90%). . The resulting polymer block A3 had a weight average molecular weight of 36,800, a number average molecular weight of 16,000, and a polydispersity of 2.3.
¹ H-NMR (270 MHz, CDCl ₃ ): δ = 7.60-7.30 (br, 3H), 3.30-3.00 (Br, 5H), 2.00-1.09 (br, 52H) ), 1.00-0.72 (br, 12H)

(Polymerization example 4)
Polymer block A4 was synthesized according to the following reaction formula.

In a 50 mL eggplant flask under nitrogen atmosphere, tris (o-tolyl) phosphine (P (o-tol) ₃ ; 37 mg, 0.12 mmol) and tris (dibenzylideneacetone) dipalladium (Pd ₂ (dba) ₃ ; 14 mg , 15 μmol) and chlorobenzene (Ph—Cl; 32 mL) were heated at 50 ° C. for 10 minutes. After heating, the temperature is once returned to room temperature, and 2,6-bis (trimethyltin) -4,8-diethylhexyloxybenzo [1,2-b: 4,5-b is used as a monomer constituting the polymer block A4. '] Dithiophene (0.64 g, 0.75 mmol) and 1,3-dibromo-5-octylthieno [3,4-c] pyrrole-4,6-dione (0.32 g, 0.75 mmol) are added and 130 Heat at 3 ° C. for 3 hours. Next, 2,5-dibromothiophene (1.84 g, 7.6 mmol) was added as a linker compound and heated at 115 ° C. for 8 hours. After completion of the reaction, polymer block A4 (0.51 g, 96%) was obtained in the same manner as in Polymerization Example 3. The resulting polymer block A4 had a weight average molecular weight of 250,000, a number average molecular weight of 52,000, and a polydispersity of 4.80.
¹ H-NMR: δ = 8.52 (br, 2H), 4.65-3.66 (br, 4H), 3.58 (s, 2H), 1.38-1.25 (m, 30H) , 0.97-0.90 (br, 15H)

(Polymerization Example 5)
Polymer block A5 was synthesized according to the following reaction formula.

In a nitrogen atmosphere, tris (o-tolyl) phosphine (37 mg, 0.12 mmol), tris (dibenzylideneacetone) dipalladium (14 mg, 15 μmol) and chlorobenzene (32 mL) were heated at 50 ° C. for 10 minutes. did. After heating, the temperature is once returned to room temperature, and 1,3-dibromo-5-ethylhexylthieno [3,4-c] pyrrole-4,6-dione (0.32 g, 0) is used as a monomer constituting the polymer block A5. .75 mmol), 4,4′-didodecyl-5,5′-trimethyltin 2,2′-bithiophene (0.62,0.75 mmol) was added and heated at 130 ° C. for 3 hours. Next, 2,5-dibromothiophene (1.84 g, 7.6 mmol) was added as a linker compound and heated at 135 ° C. for 16 hours. After completion of the reaction, the reaction solution was concentrated, poured into methanol (500 mL), the precipitated solid was collected by filtration, and the obtained solid was dried under reduced pressure to obtain a crude product. The crude product was washed with acetone (200 mL) and hexane (200 mL) using a Soxhlet extractor and then extracted with chloroform (200 mL). The organic layer was concentrated to dryness, and the resulting black purple solid was dissolved in chloroform (30 mL) and reprecipitated with methanol (300 mL). The obtained solid was collected by filtration and dried under reduced pressure to obtain polymer block A5 (0.46 g, 80%) as a black purple solid. The resulting polymer block A5 had a weight average molecular weight of 210,000, a number average molecular weight of 48,000, and a degree of dispersion of 4.38.
¹ H-NMR (270 MHz, CDCl ₃ ): δ = 7.17 (s, 2H), 3.56 (br, 2H), 2.84-2.81 (br, 4H), 1.88 (br, 1H), 1.73-1.66 (br, 4H), 1.49-1.27 (br, 44H), 0.95-0.86 (br, 12H)

Example 1
The block copolymer 1 was synthesized according to the following reaction formula. In the following reaction formula, p represents a repeating unit of the polymer block A, and q represents a repeating unit of the polymer block B. The same applies to other examples and comparative examples.

2,6-Dibromo-4,4′-bis (2-ethylhexyl) as a monomer constituting the polymer block A1 (0.50 g, 0.94 mmol) and the polymer block B in a 25 mL three-necked flask under a nitrogen atmosphere Dithieno [3,2-b: 2 ′, 3′-d] germole (0.58 g, 0.91 mmol) and 4,7-bis (3,3,4,4-tetramethyl-2,5,1) -Dioxaborolan-1-yl) benzo [c] [1,2,5] thiadiazole (0.36 g, 0.94 mmol) was added, toluene (20 mL), 2M aqueous potassium carbonate (10 mL, 20 mmol), tetrakis (triphenyl) Phosphine) palladium (0) (20.5 mg, 17.7 μmol) and aliquat 336 (0.8 mg, 1.98 μmol) were added, and the mixture was stirred at 80 ° C. for 16 hours. Stir. After completion of the reaction, the reaction solution was poured into methanol (200 mL), the precipitated solid was collected by filtration, washed with water (20 mL) and methanol (20 mL), and the resulting solid was dried under reduced pressure to obtain a crude product. It was. The crude product was washed with acetone (200 mL) and hexane (200 mL) using a Soxhlet extractor and then extracted with chloroform (200 mL). The organic layer was concentrated to dryness, and the resulting black purple solid was dissolved in chloroform (30 mL) and reprecipitated with methanol (300 mL). The obtained solid was collected by filtration and then dried under reduced pressure to obtain block copolymer 1 as a black purple solid (0.41 g, 76%). The obtained block copolymer 1 had a weight average molecular weight of 76,700, a number average molecular weight of 27,200, and a dispersity of 2.82.
1H-NMR (270 MHz): δ = 8.12-7.96 (m, 8H), 7.90-7.61 (m, 8H), 2.75 (t, J = 7.56 Hz, 4H), 2.35-1.92 (m, 20H), 1.59-1.32 (m, 54H), 1.18-0.81 (m, 36H))

(Comparative polymerization example 1)
Polymer block a1 was synthesized according to the following reaction formula.

In a 100 mL three-necked flask under nitrogen atmosphere, 2,6-dibromo-4,4′-bis (2-ethylhexyl) -cyclopenta [2,1-b: 3,4, which is a monomer constituting the polymer block a1. b ′] dithiophene (1.50 g, 2.68 mmol) and 4,7-bis (3,3,4,4-tetramethyl-2,5,1-dioxaborolan-1-yl) benzo [c] [1, 2,5] thiadiazole (1.04 g, 2.68 mmol), toluene (50 mL), 2M aqueous potassium carbonate solution (25 mL, 50 mmol), tetrakis (triphenylphosphine) palladium (0) (61.9 mg, 53.5 μmol) , Aliquat 336 (2 mg, 4.95 μmol) was added, followed by stirring at 80 ° C. for 2 hours. After completion of the reaction, the reaction solution was poured into methanol (500 mL), the precipitated solid was collected by filtration, washed with water (100 mL) and methanol (100 mL), and the resulting solid was dried under reduced pressure to obtain a crude product. It was. The crude product was washed with acetone (200 mL) and hexane (200 mL) using a Soxhlet extractor and then extracted with chloroform (200 mL). The obtained solution was concentrated, poured into methanol (500 mL), and the precipitated solid was collected by filtration and dried under reduced pressure to obtain polymer block A1 as a black purple solid (1.06 g, 74%). The resulting polymer block a1 had a weight average molecular weight of 40,800, a number average molecular weight of 19,500, and a polydispersity of 2.09.
¹ H-NMR (270 MHz): δ = 8.10-7.96 (m, 2H), 7.81-7.61 (m, 2H), 2.35-2.13 (m, 4H), 1 .59-1.32 (m, 18H), 1.18-0.81 (m, 12H)

(Comparative Example 1)
A block copolymer 1 ′ was synthesized according to the following reaction formula.

2,6-Dibromo-4,4′-bis (2-ethylhexyl) as a monomer constituting polymer block a1 (0.50 g, 0.94 mmol) and polymer block B in a 25 mL three-necked flask in a nitrogen atmosphere Dithieno [3,2-b: 2 ′, 3′-d] germole (0.58 g, 0.91 mmol) and 4,7-bis (3,3,4,4-tetramethyl-2,5,1) -Dioxaborolan-1-yl) benzo [c] [1,2,5] thiadiazole (0.36 g, 0.94 mmol) was added, toluene (20 mL), 2M aqueous potassium carbonate (10 mL, 20 mmol), tetrakis (triphenyl) Phosphine) palladium (0) (20.5 mg, 17.7 μmol) and aliquat 336 (0.8 mg, 1.98 μmol) were added, and the mixture was stirred at 80 ° C. for 16 hours. Stir. After completion of the reaction, the reaction solution was poured into methanol (200 mL), the precipitated solid was collected by filtration, washed with water (20 mL) and methanol (20 mL), and the resulting solid was dried under reduced pressure to obtain a crude product. It was. The crude product was washed with acetone (200 mL) and hexane (200 mL) using a Soxhlet extractor and then extracted with chloroform (200 mL). The organic layer was concentrated to dryness, and the resulting black purple solid was dissolved in chloroform (30 mL) and reprecipitated with methanol (300 mL). The obtained solid was collected by filtration and dried under reduced pressure to obtain block copolymer 1 ′ as a black purple solid (0.41 g, 76%). The resulting block copolymer 1 ′ had a weight average molecular weight of 59,400, a number average molecular weight of 19,600, and a polydispersity of 3.03.
¹ H-NMR (270 MHz): δ = 8.12-7.96 (m, 8H), 7.90-7.61 (m, 8H), 2.75 (t, J = 7.56 Hz, 4H) 2.35-1.92 (m, 20H), 1.59-1.32 (m, 54H), 1.18-0.81 (m, 36H)

(Example 2)
The block copolymer 2 was synthesized according to the following reaction formula.

In a 50 mL flask under nitrogen atmosphere, 2,6-bis (trimethyltin) -4,8-bis (octyl) as a monomer constituting the polymer block A2 (0.59 g, 0.75 mmol) and the polymer block B Benzo [1,2-b: 4,5-b ′] dithiophene (0.56 g, 0.75 mmol) and 1- (4,6-dibromothieno [3,4-b] thiophen-2-yl) -2- Ethylhexane-1-one (0.32 g, 0.75 mmol), DMF (3.0 mL), toluene (12 mL), tetrakis (triphenylphosphine) palladium (0) (30 mg, 26 μmol) were added, and the inside of the container was filled with argon. After bubbling with gas for 20 minutes, it was heated at 110 ° C. for 10 hours. After completion of the reaction, the reaction solution was poured into methanol (300 mL), the precipitated solid was collected by filtration, and the obtained solid was dried under reduced pressure to obtain a crude product. The crude product was washed with acetone (200 mL) and hexane (200 mL) using a Soxhlet extractor and then extracted with chloroform (200 mL). The obtained solution was concentrated, poured into methanol (300 mL), and the precipitated solid was collected by filtration and dried under reduced pressure to obtain block copolymer 2 as a black purple solid (0.50 g, 45%). The resulting block copolymer 2 had a weight average molecular weight of 84,600, a number average molecular weight of 28,800, and a dispersity of 2.99.
¹ H-NMR (270 MHz, CDCl ₃ ): δ = 7.60-7.30 (br, 6H), 4.40-4.00 (br, 8H), 3.20-3.00 (br, 2H) ), 2.00-0.60 (br, 176H)

(Example 3)
The block copolymer 3 was synthesized according to the following reaction formula.

A block copolymer 3 was obtained in the same manner as in Example 2 except that the polymer block A3 was used (0.53 g, 53%). The obtained block copolymer 3 had a weight average molecular weight of 82,000, a number average molecular weight of 27,700, and a dispersity of 2.96.
¹ H-NMR (270 MHz, CDCl ₃ ): δ = 7.60-7.30 (br, 6H), 4.40-4.00 (br, 8H), 3.20-3.00 (br, 2H) ), 2.00-0.60 (br, 176H)

Example 4
The block copolymer 4 was synthesized according to the following reaction formula.

  Polymer block A2 (0.59 g, 0.75 mmol), 2,6-bis (trimethyltin) -4,8-bis (5- (2-ethylhexyl) thiophene-2 as a monomer constituting polymer block B -Yl) benzo [1,2-b: 4,5-b ′] dithiophene (0.68 g, 0.75 mmol) and 1- (4,6-dibromothieno [3,4-b] thiophen-2-yl) The same method as in Example 2 was used, except that 2-ethylhexane-1-one (0.32 g, 0.75 mmol) was used. The resulting block copolymer 4 (0.48 g, 76%) had a weight average molecular weight of 67,600, a number average molecular weight (Mn) of 27,500, and a degree of dispersion of 2.46.

(Example 5)
The block copolymer 5 was synthesized according to the following reaction formula.

Polymer block A2 (160.0 mg, 0.12 mol) and 2,6-bis (trimethyltin) -4,8-bis (2-ethylhexyloxy) as two types of monomers constituting the polymer block B Benzo [1,2-b: 4,5-b ′] dithiophene (113.0 mg, 0.16 mmol), 2,6-bis (trimethyltin) -4,8-dipropylbenzo [1,2-b: 4,5-b ′] dithiophene (40.9 mg, 0.07 mmol) and 1- (4,6-dibromothieno [3,4-b] thiophen-2-yl) -2-ethylhexane-1-one (86 0.0 mg, 0.20 mmol) was used in the same manner as in Example 2. The resulting block copolymer 5 (221.0 mg, 75.4%) had a weight average molecular weight of 86,400, a number average molecular weight of 28,800, and a polydispersity of 2.99.
¹ H-NMR (270 MHz, CDCl ₃ ): δ = 7.60-7.30 (br, 3H), 4.40-4.00 (br, 4H), 3.30-3.00 (Br, 4H) ), 2.00-0.60 (br, 51H)

(Example 6)
The block copolymer 6 was synthesized according to the following reaction formula.

In a nitrogen atmosphere, tris (o-tolyl) phosphine (37 mg, 0.12 mmol), tris (dibenzylideneacetone) dipalladium (14 mg, 15 μmmol), and chlorobenzene (32 mL) were heated at 50 ° C. for 10 minutes. did. After heating, the temperature is once returned to room temperature, and the polymer block A4 (0.16 g, 0.12 mmol) and the two types of monomers constituting the polymer block B are 2,6-bis (trimethyltin) -4, 8-bis (propioxy) benzo [1,2-b: 4,5-b ′] dithiophene (24 mg, 0.04 mmol), 2,6-bis (trimethyltin) -4,8-bis (2-ethylhexene) Siloxy) benzo [1,2-b: 4,5-b ′] dithiophene (65 mg, 0.08 mmol), 1,3-dibromo-5-octylthieno [3,4-c] pyrrole-4,6-dione ( 51 mg, 0.12 mmol) was added, and the mixture was heated at 130 ° C. for 15 hours. After completion of the reaction, block copolymer 6 (0.16 g, 69%) was obtained using the same method as in Example 2. The resulting block copolymer 6 had a weight average molecular weight of 908,000, a number average molecular weight of 250,000, and a polydispersity of 3.63.
¹ H-NMR: δ = 8.52 (br, 2H), 4.65-3.66 (br, 4H), 3.58 (s, 2H), 1.38-1.25 (m, 26H) , 0.97-0.90 (br, 13H)

(Example 7)
The block copolymer 7 was synthesized according to the following reaction formula.

As a monomer constituting the polymer block A4 (0.53 g, 0.75 mmol) and the polymer block B, 4,4-bis (2-ethylhexyl) -2,6-bis (trimethyltin) -dithieno [3 , 2-b: 2 ′, 3′-d ′] silole (0.56 g, 0.75 mmol) and 3-dibromo-5-octylthieno [3,4-c] pyrrole-4,6-dione (0. 32 g, 0.75 mmol), DMF (3.0 mL), toluene (12 mL), tetrakis (triphenylphosphine) palladium (0) (60 mg, 0.05 mmol) were added, and the inside of the container was bubbled with argon gas for 20 minutes. And heated at 110 ° C. for 5 hours. After completion of the reaction, block copolymer 6 (0.37 g, 73%) was obtained using the same method as in Example 2. The resulting block copolymer 7 had a weight average molecular weight of 374,000, a number average molecular weight of 96,000, and a polydispersity of 3.90.
¹ H-NMR (270 MHz, CDCl ₃ ): δ = 8.61-8.50 (br, 3H), 7.60-7.30 (br, 1H), 4.65-3.55 (br, 8H) ), 2.00-1.25 (m, 82H), 1.00-0.90 (m, 30H)

(Example 8)
The block copolymer 8 was synthesized according to the following reaction formula.

In a nitrogen atmosphere, tris (o-tolyl) phosphine (37 mg, 0.12 mmol), tris (dibenzylideneacetone) dipalladium (14 mg, 15 μmol) and chlorobenzene (32 mL) were heated at 50 ° C. for 10 minutes. did. After heating, the temperature is once returned to room temperature, and 1,3-dibromo-5-octylthieno [3,4-c] is used as a monomer constituting the polymer block A5 (0.57 g, 0.75 mmol) and the polymer block B. Pyrrole-4,6-dione (0.32 g, 0.75 mmol), 4,4′-di (2-ethylhexyl) -5,5′-trimethyltin-2,2′-bithiophene (0.54 g, 0. 75 mmol) and heated at 130 ° C. for 3 hours. Thereafter, using the same method as in Polymerization Example 5, block copolymer 8 (0.85 g, 80%) was obtained. The resulting block copolymer 8 had a weight average molecular weight of 370,000, a number average molecular weight of 88,000, and a polydispersity of 4.21.
¹ H-NMR (270 MHz, CDCl ₃ ): δ = 7.17 (s, 4H), 3.58-3.54 (br, 4H), 2.84-2.81 (br, 8H), 1. 88-1.27 (m, 98H), 0.95-0.86 (br, 24H)

(Comparative polymerization example 2)
Polymer block a2 was synthesized according to the following reaction formula.

In a 50 mL eggplant flask under nitrogen atmosphere, 2,6-bis (trimethyltin) -4,8-didodecylbenzo [1,2-b: 4,5-b, which is a monomer constituting the polymer block a2. '] Dithiophene (0.64 g, 0.75 mmol) and 1- (4,6-dibromothieno [3,4-b] thiophen-2-yl) -2-ethylhexane-1-one (0.32 g,. 75 mmol), DMF (6.2 mL), toluene (25 mL), tetrakis (triphenylphosphine) palladium (0) (9.2 mg, 7.8 μmol) were added, and the mixture was heated at 115 ° C. for 1 hour 30 minutes. After completion of the reaction, the reaction solution was concentrated, poured into methanol (500 mL), the precipitated solid was collected by filtration, and the obtained solid was dried under reduced pressure to obtain a crude product. The crude product was washed with acetone (200 mL) and hexane (200 mL) using a Soxhlet extractor and then extracted with chloroform (200 mL). The organic layer was concentrated to dryness, and the resulting black purple solid was dissolved in chloroform (30 mL) and reprecipitated with methanol (300 mL). The obtained solid was collected by filtration and dried under reduced pressure to obtain a polymer block a2 as a black purple solid. The resulting polymer block a2 (0.51 g, 86%) had a weight average molecular weight of 33,100, a number average molecular weight of 14,600, and a polydispersity of 2.27.
¹ H-NMR (270 MHz, CDCl ₃ ): δ = 7.60-7.30 (br, 3H), 3.30-3.00 (Br, 5H), 2.00-1.10 (br, 52H) ), 1.00-0.70 (br, 12H)

(Comparative Example 2)
A block copolymer 5 ′ was synthesized according to the following reaction formula.

  In a 50 mL flask under nitrogen atmosphere, 2,6-bis (trimethyltin) -4,8-bis (ethylhexyloxy) as a monomer constituting polymer block a2 (160.0 mg, 0.12 mmol) and polymer block B ) Benzo [1,2-b: 4,5-b ′] dithiophene (113.0 mg, 0.16 mmol), 2,6-bis (trimethyltin) -4,8-dipropylbenzo [1,2-b : 4,5-b ′] dithiophene (40.9 mg, 0.07 mmol) and 1- (4,6-dibromothieno [3,4-b] thiophen-2-yl) -2-ethylhexan-1-one ( 86.0 mg, 0.20 mmol), DMF (3.0 mL), toluene (12 mL), tetrakis (triphenylphosphine) palladium (0) (30 mg, 26 μmol) were added. The vessel was bubbled 20 minutes with argon gas, and heated at 110 ° C. 10 hours. After completion of the reaction, the reaction solution was poured into methanol (300 mL), the precipitated solid was collected by filtration, and the obtained solid was dried under reduced pressure to obtain a crude product. The crude product was washed with acetone (200 mL) and hexane (200 mL) using a Soxhlet extractor and then extracted with chloroform (200 mL). The obtained solution was concentrated, poured into methanol (300 mL), and the precipitated solid was collected by filtration and dried under reduced pressure to obtain block copolymer 5 'as a black purple solid (205 mg, 70%). The resulting block copolymer 5 'had a weight average molecular weight of 53,600, a number average molecular weight of 15,100, and a degree of dispersion of 3.55.

(Comparative Example 3)
A block copolymer 9 composed of an alternating copolymer block of dialkylfluorene and substituted thiophene dimer and an alternating copolymer block of dialkylfluorene and dithienobenzothiadiazole was synthesized (details of synthesis of the diblock copolymer) This procedure is described in JP 2010-74127 (Patent Document 1). The resulting block copolymer 9 (2.78 g, 85%) had a weight average molecular weight of 286,000, a number average molecular weight of 108,000, and a polydispersity of 2.65.

<Measurement of photoelectric conversion efficiency>
[Production of mixed solution of block copolymer and electron-accepting material]
16.0 mg of the block copolymer 1 obtained in Example 1, 12.8 mg of PCBM (E100H manufactured by Frontier Carbon Co., Ltd.) as an electron-accepting material, and 1 mL of chlorobenzene as a solvent at 40 ° C. for 6 hours. And mixed. Then, it cooled to room temperature 20 degreeC and filtered with the PTFE filter with the hole diameter of 0.45 micrometer, and manufactured the solution containing a block copolymer and PCBM.

[Manufacture of an organic solar cell having a layer made of a block copolymer composition]
A glass substrate provided with an ITO film (resistance value 10Ω / □) with a thickness of 150 nm by sputtering was subjected to surface treatment by ozone UV treatment for 15 minutes. A PEDOT: PSS aqueous solution (manufactured by HC Starck Co., Ltd .: CLEVIOS PH500) serving as a hole transport layer was formed on the substrate to a thickness of 40 nm by spin coating. After heating and drying at 140 ° C. for 20 minutes on a hot plate, a solution containing the block copolymer produced by the above method and PCBM was applied by spin coating, and a photoelectric conversion active layer (film thickness of about 100 nm) of the organic solar cell was applied. ) After vacuum drying for 3 hours and thermal annealing at 120 ° C. for 30 minutes, lithium fluoride was deposited in a thickness of 1 nm by a vacuum deposition method, and then Al was deposited in a thickness of 100 nm. Thereby, the organic thin-film solar cell which is a photoelectric conversion element which has a layer which consists of a composition containing the pi-electron conjugated block copolymer of this invention was obtained. The light-receiving surface shape of the organic thin film solar cell was a regular square of 5 × 5 mm.

[Evaluation of organic solar cells]
The photoelectric conversion efficiency of the obtained organic thin film solar cell was measured with a 300 W solar simulator (trade name: PEC L11: AM1.5G filter, irradiance: 100 mW / cm ² , manufactured by Peccell Technology Co., Ltd.). The photoelectric conversion performance of the polymer was evaluated.

  For the block copolymer 1 ′ obtained in Comparative Example 1, an organic thin-film solar cell that is a photoelectric conversion element having a layer made of a composition containing the block copolymer 1 ′ was produced in the same manner as described above. The photoelectric conversion efficiency was measured and the photoelectric conversion performance was evaluated.

  Table 1 shows photoelectric conversion efficiencies of organic thin-film solar cells using the π-electron conjugated block copolymers obtained in Example 1 and Comparative Example 1.

  From the comparison between Example 1 and Comparative Example 1 in which two types of polymer blocks, polymer block A and polymer block B, have the same structure, the present invention has a divalent group L composed of a monocyclic aromatic ring. It was revealed that the π-electron conjugated block copolymer of the present invention exhibits a photoelectric conversion efficiency superior to that of the block copolymer of Comparative Example 1 that does not have the divalent group L. This is because the π-electron conjugated block copolymer of the present invention used in Example 1 is a monomer homopolymer (for example, heavy polymer) as a result of polymer block A and polymer block B being connected by a divalent group L. A polymer containing only the monomer constituting the combined block A) is less mixed, and the purity is high. In other words, it is a π-electron conjugated block copolymer with high block efficiency, whereas the block copolymer of Comparative Example 1 has a small difference in number average molecular weight compared to the polymer block a1 that is a raw material. From this, it is considered that a large amount of monomer homopolymer is mixed in the obtained block copolymer, and the purity of the block copolymer is lowered. For this reason, when the block copolymer of the comparative example 1 is used for the photoelectric conversion active layer of the organic thin film solar cell, an ideal phase separation structure (morphology) cannot be formed, and the photoelectric conversion efficiency is considered inferior. It is done.

  Tables 2 and 3 show the results of measuring the photoelectric conversion efficiency of the π-electron conjugated block copolymers obtained in Examples 2 to 8 and Comparative Examples 2 and 3 by the method described above.

From the results of Examples 2 to 8, the π-electron conjugated block copolymer of the present invention having a divalent group L composed of a monocyclic aromatic ring is high in photoelectric conversion even if the structure of each polymer block constituting it is changed. It became clear to show efficiency. By comparison between Comparative Example 2 and Example 5 in which both the polymer block A and the polymer block B have the same structure, the π-electron conjugated block copolymer having a divalent group L has a divalent group L. Since there is less mixture of monomer homopolymers and the like than the block copolymer of Comparative Example 5 which does not have high purity (high block efficiency), an ideal morphology can be formed in the photoelectric conversion active layer, and high photoelectric conversion efficiency showed that. Further, as a result of comparison with the block copolymer of Comparative Example 3, the π-electron conjugated block of the present invention was compared with the block copolymer having no divalent group L even if the structure of each polymer block was changed. The copolymer was found to exhibit excellent photoelectric conversion efficiency.
It was.

  The π-electron conjugated block copolymer of the present invention can be used as a material for forming a photoelectric conversion active layer of a photoelectric conversion element. Photoelectric conversion elements using this π-electron conjugated block copolymer are used as various optical sensors including solar cells.

Claims (9)

A monomer unit having a skeleton selected from a condensed π-electron conjugated skeleton, a fluorene skeleton, a carbazole skeleton, a dibenzosilole skeleton, a dibenzogermole skeleton, and a bithiophene skeleton having a substituent having a thiophene ring as a part of the chemical structure A π-electron conjugated block copolymer containing at least two types of polymer blocks comprising:
A π-electron conjugated block copolymer, wherein the polymer blocks are connected by a divalent group consisting of a monocyclic aromatic ring.   The divalent group consisting of the monocyclic aromatic ring is a group formed by removing two hydrogen atoms from benzene, thiophene, pyrrole, pyridine, pyrimidine, pyrazine, imidazole, or furan. The π-electron conjugated block copolymer described. At least one of the polymer blocks includes a monomer unit-(ab)-,
-A- represents the following chemical formulas (1) to (7)

Having any group represented by
-B- represents the following chemical formulas (8) to (18)

The monomer unit having any group represented by the formula (in the chemical formulas (1) to (18), V ¹ represents nitrogen (—NR ¹ —), oxygen (—O—) or sulfur (—S—). V ² is carbon (—CR ¹ ₂ —), nitrogen (—NR ¹ —), silicon (—SiR ¹ ₂ —) or germanium (—GeR ¹ ₂ —), and V ³ is — (Ar ) _m - in an aryl or heteroaryl group represented, ^{V 4} are nitrogen ^(-NR 1 -), oxygen (-O-) or ^{-CR 2} = CR 2 - is and, ^{V 5} is oxygen (O ) Or sulfur (S).
R ¹ is an independently substituted alkyl group having 1 to 18 carbon atoms; R ² is independently a hydrogen atom or an optionally substituted alkyl group having 1 to 18 carbon atoms; ³ is an optionally substituted alkyl group or alkoxy group having 1 to 18 carbon atoms, and R ⁴ is independently a hydrogen atom, halogen atom or optionally substituted alkyl having 1 to 18 carbon atoms. R ⁵ is an optionally substituted alkyl group having 1 to 18 carbon atoms, an aryl group, an alkylcarbonyl group or an alkyloxycarbonyl group, and R ⁶ is a hydrogen atom or a halogen atom.
m represents an integer of 0 to 3, and n represents 0 or 1. )
The π-electron conjugated block copolymer according to claim 1 or 2, wherein: A monomer unit having a skeleton selected from a condensed π-electron conjugated skeleton, a fluorene skeleton, a carbazole skeleton, a dibenzosilole skeleton, a dibenzogermole skeleton, and a bithiophene skeleton having a substituent having a thiophene ring as a part of the chemical structure A first polymer block containing the following chemical formula (i)
M ^r −L−M ^r (i)
(Wherein, ^{M r} independently of one another are halogen, boronic acid, boronic acid ester, -MgX, -ZnX, -SiX ₃ or -SnRa ₃ (however, X is a halogen atom, Ra is from 1 to 4 carbon atoms Linear alkyl group) and L is a divalent group consisting of a monocyclic aromatic ring)
Is reacted with a compound represented by
The intermediate has a skeleton selected from a condensed π-electron conjugated skeleton having a thiophene ring as a part of a chemical structure, a fluorene skeleton, a carbazole skeleton, a dibenzosilole skeleton, a dibenzogermol skeleton, and a bithiophene skeleton having a substituent. A divalent group composed of the monocyclic aromatic ring is prepared by adding a monomer to be a second polymer block containing a monomer unit and reacting the monomer to form the first polymer block and the second polymer block. A method for producing a π-electron conjugated block copolymer, characterized by being linked by Method for producing a π-electron conjugated block copolymer according to claim 4 in which M ^r of the compound represented by Formula (i) is characterized in that it is a halogen atom. A monomer unit having a skeleton selected from a condensed π-electron conjugated skeleton, a fluorene skeleton, a carbazole skeleton, a dibenzosilole skeleton, a dibenzogermole skeleton, and a bithiophene skeleton having a substituent having a thiophene ring as a part of the chemical structure A first polymer block containing the following chemical formula (i)
M ^r −L−M ^r (i)
(Wherein, ^{M r} independently of one another are halogen, boronic acid, boronic acid ester, -MgX, -ZnX, -SiX ₃ or -SnRa ₃ (however, X is a halogen atom, Ra is from 1 to 4 carbon atoms Linear alkyl group) and L is a divalent group consisting of a monocyclic aromatic ring)
Is reacted with a compound represented by
The intermediate and a skeleton selected from a condensed π-electron conjugated skeleton having a thiophene ring as a part of a chemical structure, a fluorene skeleton, a carbazole skeleton, a dibenzosilole skeleton, a dibenzogermol skeleton, and a bithiophene skeleton having a substituent. Reacting with a second polymer block containing a monomer unit, and connecting the first polymer block and the second polymer block with a divalent group comprising the monocyclic aromatic ring, A method for producing a π-electron conjugated block copolymer.   The compound represented by the chemical formula (i) is used in an amount of 1 mol to 100 mol with respect to 1 mol of the monomer constituting the first polymer block. The manufacturing method of the pi-electron conjugated block copolymer of description.   A composition comprising the π-electron conjugated block copolymer according to any one of claims 1 to 3 and an electron-accepting material.   It has a layer which consists of a composition of Claim 8, The photoelectric conversion element characterized by the above-mentioned.