JP2014051556A - π-ELECTRON CONJUGATED RANDOM COPOLYMER, AND PHOTOELECTRIC CONVERSION ELEMENT USING THE SAME - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a π-electron conjugated random copolymer in which increase of a light absorption amount and control of morphology of a photo-electric conversion active layer can be achieved, and an excellent photo-electric conversion efficiency can be exhibited, and to provide a photoelectric conversion element using a composition including the π-electron conjugated random copolymer and an electron acceptability material.SOLUTION: A π-electron conjugated random copolymer is a random copolymer that has two-kind monomer units (-a-b-) having a donor group comprising a condensation heterocyclic skeleton (cyclopentadithiophene, dithieno germole, benzothiadiazole or the like) in which at least three rings including a thiophene ring for a part of a chemical constitution performs ring condensation, and condensation heterocyclic skeletons included in each monomer unit are mutually different or/and substituents which each monomer unit has are mutually different.

Description

  The present invention relates to a novel π-electron conjugated random copolymer and a composition containing the π-electron conjugated random polymer and useful as a photoelectric conversion element.

  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 great deal of attention.

  Organic thin-film solar cells have a bulk heterojunction structure in which a conjugated polymer and an electron-accepting material are mixed as a photoelectric conversion active layer. As a specific example, photoelectric conversion in which poly (3-hexylthiophene) (P3HT) as a conjugated polymer and [6,6] -phenyl C61 butyric acid methyl ester (PCBM) as an electron-accepting material are mixed. There is an organic thin film solar cell having an active layer (Non-patent Document 1).

  In the bulk heterojunction structure, light incident from the transparent electrode is absorbed by the conjugated polymer and / or the 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 to the conjugated polymer phase and the electron-accepting material phase, respectively, and taken out from the electrode. Therefore, to increase the photoelectric conversion efficiency of organic thin-film solar cells, increase the amount of light absorbed by the photoelectric conversion active layer, and the morphology of the bulk heterojunction structure formed by phase separation of the conjugated polymer and the electron-accepting material (form) It is important to control.

  Poly (3-hexylthiophene) has a light absorption in the visible light region, but a conjugated polymer (hereinafter sometimes abbreviated as a narrow band gap polymer) having an absorption up to a further longer wavelength region (near infrared region). Many proposals have already been made (Non-Patent Documents 2 and 3). However, in a narrow band gap polymer having a rigid main chain skeleton, it is a big problem to control the solubility in a solvent and the miscibility with a fullerene derivative which is an electron accepting material.

  Further, an organic thin film solar cell element using a conjugated block copolymer of a narrow band gap polymer aiming at high photoelectric conversion efficiency is also disclosed (Patent Document 1). Here, the fluorene skeleton is used as the main chain skeleton.

JP 2008-266459 A

Angew. Chem. Int. Ed, 47, 58 (2008) Adv. Mater. , 22, E6 (2010) Adv. Mater. , 22, 3839 (2010)

In the organic thin film solar cell using the conjugated block copolymer of the narrow band gap polymer listed in the above prior art documents, the production cost is high for the synthesis of the conjugated block copolymer, and the fluorene skeleton has a relatively wide band gap. For this reason, the light use efficiency is poor and the photoelectric conversion efficiency is as low as about 2-3%. Moreover, since they are not composed of the same monomer unit, the difference in the HOMO level between the blocks is likely to result in a significant decrease in the open circuit voltage (V _oc ). Furthermore, it is difficult to control the morphology in the conjugated block copolymer having the same side chain substituent.

  The present invention has been made to solve such problems, and can be industrially inexpensively manufactured, can increase the amount of light absorption of the photoelectric conversion active layer and can control the morphology, and exhibits excellent photoelectric conversion efficiency. It is an object of the present invention to provide a π-electron conjugated random copolymer that can be produced, and to provide a photoelectric conversion element comprising a composition containing an electron-accepting material using such a π-electron conjugated random polymer.

The π-electron conjugated random polymer of the invention according to claim 1 made to achieve the above object is represented by the following formula (1):
-(Ab)-(1)
(In the formula, -a- has a substituent and a donor group composed of a condensed heterocyclic skeleton in which at least three rings including a thiophene ring are condensed, and -b- may have a substituent.) Each of the monomers having at least two monomer units represented by a skeleton and / or an acceptor group having a condensed heterocyclic skeleton of any of the nitrogen-containing condensed heterocyclic skeletons optionally having a substituent) The condensed heterocyclic skeletons contained in the units are different from each other or / and the substituents of the monomer units are different from each other.

  Similarly, the π-electron conjugated random polymer of the invention according to claim 2 is the π-electron conjugated random polymer of the invention according to claim 1, wherein -a- is represented by the following formulas (2) to (6):

Wherein R ¹ is a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, R ² is an alkyl group having 1 to 18 carbon atoms, R ³ is an alkyl group having 1 to 18 carbon atoms, an alkoxy group, an aryl group, hetero Aryl group, alkylcarbonyl group or alkyloxycarbonyl group, R ⁴ is hydrogen atom, alkyl group having 1 to 18 carbon atoms, aryl group or halogen atom, R ⁵ is alkyl group having 1 to 18 carbon atoms, aryl group, alkylcarbonyl Group or alkyloxycarbonyl group, R ⁶ is hydrogen atom or halogen atom, V ¹ is C (R ² ) ₂ , Si (R ² ) ₂ , Ge (R ² ) ₂ or NR ² )
It is any group selected from

  The π-electron conjugated random polymer of the invention according to claim 3 is the π-electron conjugated random polymer of the invention according to claim 1, wherein -a- is the following formula (2) or (3),

  -B- is represented by the following formulas (7) and (15) to (17).

(Wherein R ^{1 to} R ⁶ and V ¹ are as defined above, V ² is NR ² , O, S or Se, V ⁴ is O or S, and n is a number from 0 to 3) It is a group.

  The π-electron conjugated random polymer of the invention according to claim 4 is the π-electron conjugated random polymer of the invention according to any one of claims 1 to 3, wherein the number average molecular weight is 1000 to 500,000 g / mol. Features.

  The π-electron conjugated random polymer of the invention according to claim 5 is the π-electron conjugated random polymer of the invention according to any one of claims 1 to 4, wherein the -a- contained in each monomer unit is The substituents possessed are different from each other.

  The π-electron conjugated random polymer of the invention according to claim 6 is the π-electron conjugated random polymer of the invention according to any one of claims 1 to 5, wherein the -a- contained in one monomer unit. Having an alkyl group or alkoxy group having 1 to 18 carbon atoms, and the -a- contained in the other monomer unit has a different alkyl group or alkoxy group having 1 to 18 carbon atoms. To do.

  The composition of the invention according to claim 7, which was also made to achieve the above object, comprises an electron accepting material, and the π-electron conjugated random of the invention according to claim 1. Including polymers.

  The photoelectric conversion element of the invention according to claim 8 which is also made to achieve the above object has a layer made of the composition of the invention according to claim 7.

  Similarly, the photoelectric conversion element of the invention according to claim 9 has a layer made of the composition of the invention according to claim 7, wherein the electron-accepting material is fullerene or a derivative thereof.

  In the π-electron conjugated random copolymer of the present invention, the crystallinity is moderately lowered by disturbing the order of the main chain or side chain constituting the random copolymer, and the mixing property with the electron accepting material is improved. As a result, the interface area between the electron donating material and the electron accepting material is increased, and the performance of the photoelectric conversion element can be greatly improved.

  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 random copolymer of the present invention has at least two types of monomer units represented by the following formula (1).
-(Ab)-(1)

  The π-electron conjugated random copolymer of the present invention is composed of a donor group represented by -a- in the formula (1) (a group having a skeleton showing an electron donating property) and -b- in the formula (1). It consists of a monomer unit having an acceptor group (group having a skeleton showing electron-withdrawing properties). The band gap of the monomer unit can be controlled by a combination of -a- and -b-. By reducing the band gap, the absorption wavelength of the monomer unit becomes longer, and it is possible to have a light absorption band up to a long wavelength region. Therefore, since the π-electron conjugated random copolymer of the present invention is a narrow band gap polymer having a light absorption band up to a long wavelength region, the light absorption amount of sunlight is increased and the photoelectric conversion efficiency is excellent.

  -A- is a donor group composed of a condensed heterocyclic skeleton having a substituent and at least three rings containing one or more thiophene rings condensed. Examples of the condensed heterocyclic skeleton in which at least three rings including one or more thiophene rings are condensed include cyclopentadithiophene, dithienopyrrole, dithienosilole, dithienogermol, benzodithiophene, naphthodithiophene, and the like. The upper limit of the ring on which the condensed heterocyclic skeleton can be condensed is not particularly limited, but from the viewpoint of solubility, it is preferably not more than seven rings, and more preferably not more than five rings. The ring forming the condensed heterocyclic skeleton is preferably a 5-membered ring or a 6-membered ring. A substituent is introduced into the main chain skeleton by a covalent bond for the purpose of controlling the solubility and polarity of the π-electron conjugated random copolymer.

  -A- may contain a furan ring or a selenophene ring in part of the chemical structure as long as it contains at least one thiophene ring in part of the chemical structure. By using a furan ring or a selenophene ring, the band gap becomes narrower, light absorption on the longer wavelength side becomes possible, and a photoelectric conversion element excellent in conversion efficiency can be provided.

As said -a-, the structure represented by following formula (2)-(6) can be used preferably. Especially, the structure represented by Formula (2) or Formula (3) is preferable, and the structure represented by Formula (3) is particularly preferable.

  The -b- is an acceptor group having a condensed heterocyclic skeleton which is any of a thienothiophene skeleton which may have a substituent and a nitrogen-containing condensed heterocyclic skeleton which may have a substituent. Examples of the nitrogen-containing fused heterocyclic skeleton include benzothiadiazole, benzoselenadiazole, benzotellodiazole, benzotriazole, pyridinothiadiazole, pyridinoselenadiazole, thienothiadiazole, naphthobithiadiazole, naphthothiadiazole, quinoxaline, benzobis Examples include thiadiazole, thienopyrrole, diketopyrrolopyrrole, thiazolothiazole, triazine, and tetrazine. -B- may have a substituent in the main chain skeleton for the purpose of controlling the solubility and polarity of the π-electron conjugated random copolymer.

As -b-, for example, structures represented by the following formulas (7) to (17) can be preferably used. Among these, the structures represented by (7) and (15) to (17) are preferable, and the structure represented by Formula (17) is particularly preferable.

In the formulas (1) to (17), V ¹ is C (R ² ) ₂ , Si (R ² ) ₂ , Ge (R ² ) ₂ or NR ² , V ² is NR ² , O, S, and S is particularly preferable.

  In formulas (7) to (17), n is a number from 0 to 3, preferably 0 or 1.

In formulas (1) to (17), R ¹ is a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, R ² is an alkyl group having 1 to 18 carbon atoms, and R ³ is an alkyl group having 1 to 18 carbon atoms. An alkyl group, an alkoxy group, an aryl group, a heteroaryl group, an alkylcarbonyl group or an alkyloxycarbonyl group, R ⁴ is a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, an aryl group or a halogen atom, and R ⁵ is 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. Each R ^{1 to} R ⁶ may be the same or 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, a 9-anthracenyl group, and the like. These further include substituents such as an alkyl group and an alkoxy group. You may have.

  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 substituent represented by R ^{1 to} R ⁵ that the π-electron conjugated random copolymer of the present invention may have is an alkyl group, an alkoxy group, a halogen atom, a hydroxyl group, an amino group, a thiol group, a silyl group, It may be further substituted with an ester group, an aryl group, a heteroaryl group or the like. The alkyl group or alkoxy group may be linear, branched or alicyclic.

Examples of the alkyl group, alkoxy group, aryl group and heteroaryl group which may be substituted on the substituents R ^{1 to} R ⁵ of the π-electron conjugated random copolymer of the present invention include those exemplified above. .

  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.

Preferable specific examples of the monomer unit represented by the formula (1) include structures represented by the following formulas (18) to (26).

  That is, the monomer unit represented by the formula-(2)-(7)-(where n = 0 in the formula (7)) is the formula (18). The monomer unit represented by the formula-(2)-(15)-is the formula (19). The monomer unit represented by the formula-(2)-(16)-(where n = 0 in the formula (16)) is the formula (20). The monomer unit represented by the formula-(2)-(17)-is the formula (21). The monomer unit represented by Formula- (3)-(7)-(where n = 1 in Formula (7)) is Formula (22. Formula- (3)-(11)-(here The monomer unit represented by the formula (11) is n = 1) is the formula (23) The monomer unit represented by the formula-(3)-(15)-is represented by the formula (23). The monomer unit represented by the formula-(3)-(16)-(where n = 0 in the formula (16)) is the formula (25). The monomer unit represented by (17)-is represented by the formula (26), among which the monomer unit represented by the formula (26) is particularly preferable, and a π-electron conjugated random exhibiting excellent photoelectric conversion efficiency. A copolymer can be provided.

  In addition, as long as the monomer unit in this invention has two or more fixed structures in a polymer, it includes making the structure (for example, -ab-) which connected multiple heterocycles into one unit. That is, a completely alternating copolymer of a donor group -a- and an acceptor group -b- is regarded as a homopolymer of monomer units -ab, as long as the substituents are the same. And

  In the π-electron conjugated random copolymer of the present invention, the total number of only carbon atoms constituting the ring structure excluding substituents in one type of monomer unit including up to the embodiment of the monomer unit -ab- 6 to 40 is preferable.

  The π-electron conjugated random copolymer of the present invention is composed of at least two different monomer units. That the monomer units are different from each other means that the condensed heterocyclic skeletons contained in each monomer unit are different from each other, or the substituents of each monomer unit are different from each other. Since the monomer units constituting the random copolymer have the above-mentioned differences, the π-electron conjugated random copolymer of the present invention has a disordered main chain or side chain order, and is mixed with an electron accepting material. As a result, the interface area between the electron donating material and the electron accepting material can be increased.

That the heteroaryl skeletons constituting the main chain are different from each other means that at least a part of the main chain skeleton excluding a substituent is different from each other. In this case, the substituents are not necessarily the same. For example, among the monomer units (-a-b-), -a- or -b- are different from each other, or even if they are the same monomer unit -ab-, V ^{1 to} V ⁵ are different from each other. Anything different can be used suitably.

That each monomer unit has a different substituent means that at least a part of the substituents R ^{1 to} R ⁶ excluding the condensed heterocyclic skeleton constituting the main chain in each monomer unit is different from each other. Point to. For example, any one of the substituents that -a- or -b- of the monomer units -a-b- has may be different, or both substituents may be different. In this case, the condensed heterocyclic ring skeletons are not necessarily the same. However, when the condensed heterocyclic skeletons are the same, the HOMO levels of the monomer units are close to each other. Therefore, in the photoelectric conversion characteristics when the organic photoelectric conversion element is produced, charge recombination and a decrease in the open-circuit voltage are reduced. It is suppressed and the photoelectric conversion efficiency is further improved.

  As an example of a specific embodiment in which the substituents of each monomer unit are different from each other, one in which the difference in the number of carbon atoms of the substituents is 4 or more can be mentioned. That is, the total number of carbon atoms of the substituents contained in the monomer unit (-ab-) of the π-electron conjugated random copolymer of the present invention and the single amount of another π-electron conjugated random copolymer of the present invention. This means that the difference in the total number of carbon atoms of the substituents contained in the body unit (-a'-b-) or (-a-b'-) is 4 or more. When the difference in the number of carbon atoms is 4 or more, the ordering of the side chains is disturbed, and the electron-accepting material is easily contained in the voids on the short chain alkyl group side, so that the mixing property can be improved. It is also one of the preferable embodiments that when any one of the substituents contained in the monomer unit is compared, the maximum difference in carbon number is 4 or more.

  Moreover, as an example of a specific embodiment in which the substituents of the respective monomer units are different from each other, there may be mentioned those in which the substituents of the monomer units include branched and linear ones. That is, the π-electron conjugated random copolymer of the present invention comprises a monomer unit (-ab-) having only a linear alkyl group in the side chain substituent and a branched alkyl group in the side chain substituent. It contains containing the monomer unit (-a'-b-) or (-a-b'-) which has group. By randomly having branched alkyl chains, the order of the side chain substitution machine is disturbed, and the electron-accepting material is accommodated in voids formed by steric hindrance, so that the mixing property can be improved.

  In addition, examples of specific embodiments in which the substituents of the monomer units are different from each other include those in which the side chain substituents of the monomer units include and do not include heteroatoms. . That is, the π-electron conjugated random copolymer of the present invention has a monomer unit (-ab-) having only an alkyl group containing no hetero atom in the side chain substituent and a hetero atom in the side chain substituent. It contains containing the monomer unit (-a'-b-) or (-a-b'-). By having side chain substituents that include heteroatoms at random, the ordering of the side chain substituter is disturbed, and the polarity changes due to the contribution of heteroatoms, which improves the mixing with electron-accepting materials. it can. A hetero atom refers to an atom different from a carbon atom or a hydrogen atom in an organic compound, and includes a halogen atom, an oxygen atom, a sulfur atom, a silicon atom, a nitrogen atom, etc. Among them, an oxygen atom and a halogen atom are preferable. . The halogen atom that can be used includes a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a fluorine atom is particularly preferable.

  In the case where the substituents of the respective monomer units are different from each other, it is more preferable that the substituents of -a- are different from each other. Among them, the -a- contained in one monomer unit has an alkyl group or alkoxy group having 1 to 18 carbon atoms, and the -a- contained in the other monomer unit has a different carbon number. Those having 1 to 18 alkyl groups or alkoxy groups are particularly preferred.

  The composition ratio of the monomer unit (-ab-) and the monomer unit (-a'-b-) or (-ab-) of the π-electron conjugated random copolymer of the present invention is The ratio is preferably 99: 1 to 1:99, and more preferably 95: 5 to 5:95.

  The number average molecular weight of the π-electron conjugated random copolymer is preferably 1,000 to 500,000 g / mol, and preferably 5,000 to 200,000 g / mol from the viewpoints of processability, crystallinity, solubility, photoelectric conversion characteristics and the like. More preferably, it is the range. 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 random 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 of the π-electron conjugated random copolymers of the present invention have low solubility around room temperature. In such a case, the number average molecular weight is obtained by high-temperature GPC chromatography using dichlorobenzene or trichlorobenzene as a solvent. Also good.

  The π-electron conjugated random copolymer of the present invention may have monomer units other than those described above as necessary. Examples of such other monomer units include a monomer unit composed of a component containing a -a-unit alone, a -b-unit alone, or other monocyclic or condensed (hetero) arylene groups. Is mentioned. In addition, a non-π electron conjugated monomer may be included. Examples of the monomer include aromatic vinyl compounds (styrene, chloromethylstyrene, vinylpyridine, vinylnaphthalene, etc.), (meth) acrylic acid esters ( Methyl (meth) acrylate, ethyl (meth) acrylate, hydroxyethyl (meth) acrylate, etc., vinyl esters (vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate, etc.), alpha hydroxy acids (lactic acid, glycol) Acid, etc.).

  The π-electron conjugated random copolymer of the present invention may form a linking body with another π-electron conjugated polymer, that is, a block copolymer, a graft copolymer, or a dendrimer, if necessary. By making it a linked body with other π-electron conjugated polymer, a portion having miscibility with the electron-accepting component and a portion having no miscibility with the electron-accepting component are phase-separated, and a photoelectric conversion element It is possible to form a morphology having excellent characteristics.

  As an example of the method for producing the π-electron conjugated random copolymer of the present invention, each reaction step and production method will be described in detail.

  The π-electron conjugated random copolymer of the present invention is a monomer comprising a monomer unit (-ab-) and a monomer unit (-a'-b-) or (-ab-). The body is obtained by mixing and polymerizing at a desired charging ratio.

If it demonstrates in detail, according to following Reaction formula (I), the monomer which comprises a monomer unit (-ab-) and a monomer unit (-a'-b-) in presence of a catalyst M ^q1 -a-M ^q1 , M ^q1 -a′-M ^q1 and M ^q2 -b-M ^q2 are reacted with each other and polymerized by a coupling reaction. Coalescence can be obtained.

Further, according to the following reaction formula (II), M ^q1 − which is a monomer constituting the monomer unit (−ab−) and the monomer unit (−ab ′) in the presence of a catalyst. The π-electron conjugated random copolymer of the present invention can be obtained by reacting aM ^q1 , M ^q2 -b-M ^q2 and M ^q2 -b′-M ^q2 and polymerizing by a coupling reaction. .

In formula (I) and formula (II), -a-, -a'-, -b-, -b'- represent monomer units (-a-b-) and (-a'-b-) and Represents a condensed heterocyclic skeleton constituting at least a part of the monomer constituting (-a-b'-), and M ^q1 and M ^q2 are not the same and are each independently a halogen atom, or boronic acid or boronic acid Ester, -MgX, -ZnX, -SiX ₃ or -SnRa ₃ (where Ra is a linear alkyl group having 1 to 4 carbon atoms and X is a halogen atom). 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 .

  As the catalyst used in each of the above production methods, a complex of a transition metal can be suitably used. For example, the transition metal complex which belongs to 3-10 group of a periodic table (Group 18 long periodic type periodic table), especially 8-10 group is mentioned. Specific examples include known complexes 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, tridentate phosphine coordination such as trimethylphosphine, triethylphosphine, triisopropylphosphine, tri-t-butylphosphine, tricyclohexylphosphine, triphenylphosphine, tris (2-methylphenyl) phosphine Diphenylphosphinomethane (dppm), 1,2-diphenylphosphinoethane (dppe), 1,3-diphenylphosphinopropane (dppp), 1,4-diphenylphosphnobutane (pdbb), 1,3- Bidentate phosphine compounds such as bis (dicyclohexylphosphino) propane (dcpp), 1,1′-bis (diphenylphosphino) ferrocene (dppf), 2,2-dimethyl-1,3-bis (diphenylphosphino) propane Lico; tetramethyl Ethylenediamine, bipyridine, it is preferable that such a nitrogen-containing ligands such as acetonitrile is contained.

  Although the usage-amount of a catalyst changes with kinds of (pi) electron conjugated random copolymer to manufacture, 0.001-0.1 mol is preferable with respect to a monomer. 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 random copolymer of the present invention is preferably produced in the presence of a solvent. The solvent which can be used for manufacture can select the solvent generally marketed. For example, ether solvents 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 , Aliphatic or alicyclic saturated hydrocarbon solvents such as pentane, hexane, heptane, cyclohexane, aromatic hydrocarbon solvents such as benzene, toluene, xylene, alkyl halide solvents such as dichloromethane and chloroform, chlorobenzene, di Aromatic aryl halide solvents such as chlorobenzene, amide solvents such as dimethylformamide, diethylformamide, N-methylpyrrolidone, water and these Such compounds, and the like.

  The amount of the organic solvent used is preferably in the range of 1 to 1000 times by weight with respect to the monomer of the π-electron conjugated random copolymer to be produced, and the solubility of the resulting conjugate and the stirring efficiency of the reaction solution From the viewpoint, it is preferably 10 times by weight or more, and from the viewpoint of reaction rate, it is preferably 100 times by weight or less.

  The polymerization temperature varies depending on the type of π-electron conjugated random copolymer to be produced, but is usually in the range of −80 to 200 ° C. Although the pressure of a reaction system is not specifically limited, 0.1-10 atmospheres is preferable. The reaction is usually carried out at around 1 atm. The reaction time varies depending on the π-electron conjugated random copolymer to be produced, but is usually 20 minutes to 100 hours.

  The resulting π-electron conjugated random copolymer is π-electron conjugated random copolymer such as reprecipitation, solvent removal under heating, solvent removal under reduced pressure, solvent removal with steam (steam stripping), etc. The combined product can be separated and obtained from the reaction mixture and by-products by a normal operation in isolating the combined product from the solution. The obtained crude product can be purified by washing or extracting with a commercially available solvent using a Soxhlet extractor. For example, ether solvents 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 Etc. are suitable.

  The π-electron conjugated random copolymer has, 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 a hydrogen atom from which these atoms or groups are eliminated. Further, a terminal structure in which these terminal groups are substituted with a terminal blocking agent made of an aromatic halide such as benzene bromide or an aromatic boronic acid compound may be used.

  As long as the effects of the present invention are not impaired, the -a- or -b- homopolymer may remain in the π-electron conjugated random copolymer produced by the above method. The residual component is preferably 70% or less.

  Next, a composition containing the π electron conjugated random copolymer of the present invention and an electron accepting material will be described. The π-electron conjugated random copolymer can be used for, for example, a photoelectric conversion active layer of a photoelectric conversion element by forming a composition with an electron accepting material. The electron-accepting material constituting the composition is not particularly limited as long as it is an organic material exhibiting n-type semiconductor properties. For example, 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA), 3,4, 9,10-perylenetetracarboxylic dianhydride (PTCDA), N, N′-dioctyl-3,4,9,10-naphthyltetracarboxydiimide (NTCDIC8H), 2- (4-biphenylyl) -5- (4- oxazole derivatives such as t-butylphenyl) -1,3,4-oxadiazole and 2,5-di (1-naphthyl) -1,3,4-oxadiazole, 3- (4-biphenylyl) -4 -Triazole derivatives such as phenyl-5- (4-t-butylphenyl) -1,2,4-triazole, phenanthroline derivatives And fullerene derivatives such as C60 and C70, carbon nanotubes (CNT), and derivatives obtained by introducing a cyano group into a poly-p-phenylene vinylene polymer (CN-PPV). 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.

Fullerene derivatives suitably used as n-type organic semiconductors include 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 (PC ₆₁ BM), [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 butyric acid dodecyl ester, [6,6] - diphenyl _{C 62} bis (butyric acid methyl _{ester) (bis-PC 62 BM)} , [6,6] - phenyl ₇₁ butyric acid methyl ester _{(PC 71 BM), [6,6} ] - diphenyl _{C 72} bis (butyric acid methyl _{ester) (bis-PC 72 BM)} , indene _{C 60} - monoadduct, indene _{C 60} - bis adduct, indene C _{70 -} monoadduct, indene C _{70 -} and substituted derivatives including bis adduct thereof.

The fullerene derivatives can be used alone or as a mixture thereof. From the viewpoint of solubility in an organic solvent, PC ₆₁ BM, bis-PC ₆₂ BM, PC ₇₁ BM, bis-PC ₇₂ BM, indene C ₆₀ -mono adduct, indene C ₆₀ -bis adduct, indene C ₇₀ -mono Adducts and indene C ₇₀ -bis adducts are preferably used. Further, among these, from the viewpoint of light absorption, PC ₇₁ BM, bis-PC ₇₂ BM, indene C ₇₀ -mono adduct, and indene C ₇₀ -bis adduct are used. From the viewpoint of production cost, PC ₆₁ BM Bis-PC ₆₂ BM and indene C ₆₀ -bis adduct are more preferably used.

  The ratio of the electron-accepting material in the composition is preferably 10 to 1000 parts by weight and more preferably 50 to 500 parts by weight with respect to 100 parts by weight of the π-electron conjugated random copolymer. The composition may contain other components such as a surfactant, a binder resin, and a filler as long as the object of the invention is not impaired.

  The method of mixing the π-electron conjugated random copolymer and the electron-accepting material is not particularly limited, but after adding to the solvent at a desired ratio, one method such as heating, stirring, and ultrasonic irradiation may be used. A method in which a plurality of types are combined and dissolved in a solvent to form a solution.

  Although it does not specifically limit as a solvent, It is preferable from a viewpoint on film forming that the solubility in 20 degreeC is 1 mg / mL or more about each of (pi) electron conjugated random copolymer and an electron-accepting material. Furthermore, from the viewpoint of arbitrarily controlling the film thickness, 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 random 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.

  These solvents include tetrahydrofuran, 1,2-dichloroethane, cyclohexane, chloroform, bromoform, benzene, toluene, o-xylene, m-xylene, chlorobenzene, bromobenzene, iodobenzene, o-dichlorobenzene, anisole, methoxybenzene, Examples include trichlorobenzene and pyridine. Solvents may be used singly or in combination of two or more types, and in particular, o-xylene, chlorobenzene, o-dichlorobenzene, tri-electrolyte having high solubility of π electron conjugated random copolymer and electron accepting material. Chlorobenzene, bromobenzene, iodobenzene, chloroform and mixtures thereof are preferred. More preferably, o-xylene, chlorobenzene, o-dichlorobenzene, trichlorobenzene 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 random copolymer and the electron-accepting material. By including an additive, a fine and continuous phase separation structure of a π-electron conjugated random copolymer and an electron-accepting material is formed in the layer, so that a photoelectric conversion active layer having excellent photoelectric conversion efficiency can be obtained. Become. Examples of the additives include octanedithiol (boiling point: 270 ° C.), dibromooctane (boiling point: 272 ° C.), diiodooctane (boiling point: 327 ° C.), diiodohexane (boiling point: 142 ° C. [10 mmHg]), diiodobutane (boiling point). : 125 ° C. [12 mmHg]), diethylene glycol diethyl ether (boiling point: 162 ° C.), N-methyl-2-pyrrolidone (boiling point: 229 ° C.), 1- or 2-chloronaphthalene (boiling point: 256 ° C.), etc. . Among these, from the viewpoint of obtaining a photoelectric conversion element having excellent photoelectric conversion efficiency, octanedithiol, dibromooctane, diiodooctane, 1- or 2-chloronaphthalene is preferably used.

  The addition amount of the additive is not particularly limited as long as the π-electron conjugated random copolymer and the electron-accepting material do not precipitate and give a uniform solution. It is preferably 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 0.5 to 10% of range.

  The photoelectric conversion element of this invention has the photoelectric conversion active layer which consists of a composition containing the said (pi) electron conjugated random copolymer and an electron-accepting material. The photoelectric conversion element has a photoelectric conversion active layer between a pair of electrodes, at least one of which has optical transparency, that is, between a positive electrode and a negative electrode.

  The photoelectric conversion element is formed on a substrate. This substrate does not change when an electrode is formed and an organic layer is formed. For example, inorganic materials such as alkali-free glass, quartz glass, silicon, polyester, polycarbonate, polyolefin, polyamide, polyimide, polyphenylene sulfide, poly A film or a plate produced by an arbitrary method from an organic material such as paraxylene, an epoxy resin, or a fluorine resin can be used. In the case of an opaque substrate, the opposite electrode, that is, the electrode far from the substrate is preferably transparent or translucent. In the case of a transparent substrate, the electrode in contact with the substrate may be a light transmissive electrode. Although the film thickness of a board | substrate is not specifically limited, Usually, it is the range of 1 micrometer-10 mm.

  Examples of the transparent or translucent electrode material having optical transparency include a conductive metal oxide film and a translucent metal thin film. Specifically, indium oxide, zinc oxide, tin oxide, and their composites, indium tin oxide (ITO), fluorine tin oxide (FTO), antimony tin oxide, indium zinc oxide (IZO), gallium / zinc / oxide, aluminum / zinc / oxide, antimony / zinc / oxide conductive film, gold, platinum, silver, copper ultrathin film is used, ITO , FTO, IZO and tin oxide are preferred. Examples of the method for producing the electrode include a vacuum deposition method, a sputtering method, an ion plating method, and a plating method. Moreover, you may use organic transparent conductive films, such as polyaniline and its derivative (s), polythiophene, and its derivative (s) as a transparent electrode material.

  As the counter electrode material, a known metal, a conductive polymer, or the like can be used, and it may not have optical transparency, and may be transparent or translucent. Preferably, one of the pair of electrodes is preferably made of a material having a low work function. For example, metals such as lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, barium, aluminum, scandium, vanadium, zinc, yttrium, indium, cerium, samarium, europium, terbium, ytterbium, and two of them The above alloys, or one or more of them and an alloy of one or more of gold, silver, platinum, copper, manganese, titanium, cobalt, nickel, tungsten, tin, graphite, or a graphite intercalation compound are used. . Examples of the alloy include magnesium-silver alloy, magnesium-indium alloy, magnesium-aluminum alloy, indium-silver alloy, lithium-aluminum alloy, lithium-magnesium alloy, lithium-indium alloy, calcium-aluminum alloy, and the like.

  The electrode used for the photoelectric conversion element is preferably a conductive material having a large work function on one side and a conductive material having a small work function on the other side. At this time, an electrode using a conductive material having a large work function is An electrode using a conductive material having a small work function is a negative electrode.

  The film thickness of the photoelectric conversion active layer comprising a composition containing a π-electron conjugated random copolymer is usually 1 nm to 1 μm, preferably 2 to 1000 nm, more preferably 5 to 500 nm, and still more preferably. 20-300 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.

  A solution containing the composition can be applied to a substrate or a support to form a photoelectric conversion active layer. The coating method is not particularly limited, and any conventionally known coating method using a liquid coating material can be employed. For example, dip coating method, spray coating method, inkjet method, aerosol jet method, spin coating method, bead coating method, wire bar coating method, blade coating method, roller coating method, curtain coating method, slit die coater method, gravure coater method, A coating method such as a slit reverse coater method, a micro gravure method, a comma coater method, etc. can be adopted, and if a coating method is selected according to the coating film characteristics to be obtained, such as coating film thickness control and orientation control. Good.

  The photoelectric conversion active layer may be subjected to heat or solvent annealing as necessary. By performing the annealing treatment, it is possible to change the crystallinity of the photoelectric conversion active layer material and the phase separation structure between the p-type organic semiconductor and the n-type organic semiconductor, thereby obtaining an element having excellent photoelectric conversion characteristics. In addition, you may perform this annealing process after formation of a negative electrode.

  Thermal annealing is performed by holding the substrate on which the photoelectric conversion active layer is formed at a desired temperature. You may carry out under reduced pressure or inert gas atmosphere, and preferable temperature is 40 to 150 degreeC, More preferably, it is 70 to 150 degreeC. If the temperature is low, a sufficient effect cannot be obtained. If the temperature is too high, the organic thin film is oxidized and / or decomposed, and sufficient photoelectric conversion characteristics cannot be obtained.

  Solvent annealing is performed by holding the substrate on which the photoelectric conversion active layer is formed in a solvent atmosphere for a desired time. The annealing solvent at this time is not particularly limited, but is preferably a good solvent for the photoelectric conversion active layer. Solvent annealing may be performed in a state where the organic semiconductor composition constituting the photoelectric conversion active layer is applied onto the substrate and the solvent remains in the composition.

  The photoelectric conversion element of this invention may provide a positive hole transport layer further between a positive electrode and an organic photoelectric converting 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. In particular, polyethylenedioxythiophene (PEDOT), which is a polythiophene polymer, or PEDOT to which polystyrene sulfonate (PSS) is added is preferably used. The thickness of the hole transport layer is preferably 1 to 600 nm, more preferably 20 to 300 nm.

  In the photoelectric conversion element of the present invention, an electron transport layer may be further provided between the negative electrode and the active layer as necessary. 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 and the like) and polyfluorene are preferably used. The electron transport layer preferably has a thickness of 0.1 to 600 nm, more preferably 0.5 to 100 nm.

  When preparing a hole transport layer between the positive electrode and the active layer, for example, in the case of a conductive polymer soluble in a solvent, a dip coating method, a spray coating method, an ink jet method, an aerosol jet method, a spin coating method, a bead It can be applied by coating method, wire bar coating method, blade coating method, roller coating method, curtain coating method, slit die coater method, gravure coater method, slit reverse coater method, micro gravure method, comma coater method and the like. 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 electron transport layer can be similarly produced.

  If necessary, the photoelectric conversion element may be provided with a metal fluoride as a buffer layer that facilitates charge transfer between the electrode, the photoelectric conversion active layer, and the electrode. Examples of the metal fluoride include lithium fluoride, sodium fluoride, potassium fluoride, magnesium fluoride, calcium fluoride, cesium fluoride, and lithium fluoride is particularly preferably used. The buffer layer preferably has a thickness of 0.05 nm to 50 nm, more preferably 0.5 nm to 20 nm. The method for forming these metal fluorides is not particularly limited, but it is preferable to apply a vapor deposition method using a vacuum vapor deposition machine from the viewpoint of controlling an arbitrary film thickness.

  The photoelectric conversion element may be used as a tandem photoelectric conversion element. The tandem photoelectric conversion element can be produced by a method known in the literature, for example, the method described in Science, 2007, Vol. 317, pp222. Specifically, the photoelectric conversion active layer (I) capable of absorbing and photoelectrically converting the charge recombination layer to the long wavelength side (up to 1100 nm) and the photoelectric conversion in the ultraviolet to visible light region (190 to 700 nm) are possible. A structure sandwiched between the photoelectric conversion active layer (II) may be mentioned. The order of connection between the photoelectric conversion active layer (I) and the photoelectric conversion active layer (II) may be reversed.

  The charge recombination layer functions to recombine electrons generated in the positive-electrode side photoelectric conversion active layer and holes generated in the negative-electrode side photoelectric conversion active layer. Holes and electrons generated by charge separation in each photoelectric conversion active layer move toward the positive electrode and the negative electrode, respectively, by an internal electric field in the photoelectric conversion active layer. At this time, holes generated in the photoelectric conversion active layer on the positive electrode side and electrons generated in the photoelectric conversion active layer on the negative electrode side are taken out to the positive electrode and the negative electrode, respectively, and electrons generated on the photoelectric conversion active layer on the positive electrode side and the negative electrode side When the holes generated in the photoelectric conversion active layer are recombined, each photoelectric conversion active layer functions as a battery electrically connected in series, and the open circuit voltage increases.

  The charge recombination layer preferably has optical transparency so that the plurality of photoelectric conversion active layers can absorb light. In addition, the charge recombination layer only needs to be designed so that holes and electrons are sufficiently recombined. Therefore, the charge recombination layer does not necessarily need to be a film, and is a metal formed uniformly on the photoelectric conversion active layer. It can be a cluster. Therefore, for the charge recombination layer, a very thin metal film or metal cluster made of gold, platinum, chromium, nickel, lithium, magnesium, calcium, tin, silver, aluminum or the like and having a light transmittance of about several nanometers or less ( Alloys), ITO, IZO, AZO, GZO, FTO, highly light-transmitting metal oxide films and clusters such as titanium oxide and molybdenum oxide, conductive organic material films such as PEDOT to which PSS is added, or these A complex of the above is used. For example, uniform silver clusters can be formed by depositing silver so as to be several nm or less on a quartz oscillator film thickness monitor using a vacuum deposition method. In addition, if a titanium oxide film is formed, the sol-gel method described in, for example, Advanced Materials, 2006, Vol. 18, pp572 can be used. If it is a composite metal oxide such as ITO or IZO, it can be formed by sputtering. The formation method and type of these charge recombination layers are appropriately selected in consideration of the non-destructive property to the photoelectric conversion active layer at the time of charge recombination layer formation, the formation method of the next photoelectric conversion active layer, etc. do it.

  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), electronic elements (such as optical sensors, optical switches, and 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.
In addition, about the material obtained at each above-mentioned process, and the material manufactured at the following process, the physical-property measurement and refinement | purification were performed as follows.

<Weight average molecular weight (Mw) / Number average molecular weight (Mn)>
The number average molecular weight and the weight average molecular weight are both determined in terms of polystyrene based on measurement by gel permeation chromatography (GPC). Unless otherwise specified, HLC-8020 manufactured by Tosoh Corporation is used as the GPC apparatus, and TSKgel manufactured by Tosoh Corporation is used as the column.
It measured using what connected two multipore HZ in series. The measurement temperature in the column and the injector was 40 ° C., and chloroform was used as the solvent.

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

  EtHex and HexEt used in the specification or the chemical formulas in the specification are 2-ethylhexyl groups, and 3-Hep is a 3-heptyl group.

(Synthesis Example 1)
2,6-bis (trimethyltin) -4,8-didodecylbenzo [1,2-b: 4,5-b ′] dithiophene represented by the following chemical formula (i) is Am. Chem. Soc. , 131, 7792 (2009), and synthesized from 4,8-didodecylbenzo [1,2-b: 4,5-b ′] dithiophene.

^１Ｈ−ＮＭＲ：δ＝７．４９（ｓ、２Ｈ）、３．２０（ｔ、４Ｈ）、１．８３（ｍ、４Ｈ）、１．５４−１．２２（ｍ、３６Ｈ）、０．８８（ｔ、６Ｈ）、０．４５（ｓ、１８Ｈ）

¹ H-NMR: δ = 7.49 (s, 2H), 3.20 (t, 4H), 1.83 (m, 4H), 1.54-1.22 (m, 36H), 0.88 (T, 6H), 0.45 (s, 18H)

(Synthesis Example 2)
2,6-bis (trimethyltin) -4,8-dipropylbenzo [1,2-b: 4,5-b ′] dithiophene represented by the following chemical formula (ii) Am. Chem. Soc. , 131, 7792 (2009), and synthesized from 4,8-dipropylbenzo [1,2-b: 4,5-b ′] dithiophene.

^１Ｈ−ＮＭＲ：δ＝７．５０（ｓ、２Ｈ）、３．２０（ｔ、４Ｈ）、１．８９−１．８５（ｍ、４Ｈ）、１．０６（ｔ、６Ｈ）、０．４５（ｓ、１８Ｈ）

¹ H-NMR: δ = 7.50 (s, 2H), 3.20 (t, 4H), 1.89-1.85 (m, 4H), 1.06 (t, 6H), 0.45 (S, 18H)

(Synthesis Example 3)
2,6-bis (trimethyltin) -4,8-bis (propyloxy) benzo [1,2-b: 4,5-b ′] dithiophene represented by the following chemical formula (iii) Am. Chem. Soc. , 131, 7792 (2009), and synthesized from 4,8-bis (propyloxy) benzo [1,2-b: 4,5-b ′] dithiophene.

^１Ｈ−ＮＭＲ：δ＝７．５１（ｓ、２Ｈ）、４．２７（ｔ、４Ｈ）、１．９５−１．８８（ｍ、４Ｈ）、１．３６（ｔ、６Ｈ）、０．５０−０．３４（ｓ、１８Ｈ）

¹ H-NMR: δ = 7.51 (s, 2H), 4.27 (t, 4H), 1.95-1.88 (m, 4H), 1.36 (t, 6H), 0.50 -0.34 (s, 18H)

(Synthesis Example 4)
2,6-bis (trimethyltin) -4,8-dioctylbenzo [1,2-b: 4,5-b ′] dithiophene represented by the following chemical formula (iV) Am. Chem. Soc. , 131, 7792 (2009), and synthesized from 4,8-dioctylbenzo [1,2-b: 4,5-b ′] dithiophene.

^１Ｈ−ＮＭＲ：δ＝７．５０（ｓ、２Ｈ）、３．２１（ｔ、４Ｈ）、１．５４−１．２１（ｍ、２０Ｈ）、０．８９（ｔ、６Ｈ）、０．４６（ｓ、１８Ｈ）

¹ H-NMR: δ = 7.50 (s, 2H), 3.21 (t, 4H), 1.54-1.21 (m, 20H), 0.89 (t, 6H), 0.46 (S, 18H)

  For methods for synthesizing other monomers, see, for example, Organometallics, 30, 3233 (2011), Adv. Funct. Mater. 17, 632 (2007), J. Am. Am. Chem. Soc. 131, 15586 (2009); Am. Chem. Soc. 131, 7792 (2009).

Example 1
Random copolymer 1 was synthesized according to the following reaction formula. In the structural formulas or reaction formulas of the polymers in the following examples, “-r-” represents random copolymerization.

  In a 100 mL three-necked flask under a nitrogen atmosphere, 2,6-dibromo-4,4′-bis (2-ethylhexyl) -dithieno [3,2-b: 2 ′, 3′-d] germole (0.83 g, 1 .34 mmol), 2,6-dibromo-4,4′-bis (2-ethylhexyl) -cyclopenta [2,1-b: 3,4-b ′] dithiophene (0.75 g, 1.34 mmol) and 4, Add 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) Furthermore, toluene (50 mL), 2M aqueous potassium carbonate solution (25 mL, 50 mmol), tetrakis (triphenylphosphine) palladium (0) (62.0 mg, 54.0 μmol), and aliq at336 (2mg, 4.95μmol) was stirred for 1 hour at 80 ° C. after the addition of the.

  After completion of the reaction, the reaction solution was poured into methanol (500 mL), and the precipitated solid was collected by filtration and washed with water and methanol to obtain a crude product. The crude product was washed with acetone and hexane using a Soxhlet extractor, extracted with chloroform (200 mL), and purified by reprecipitation with methanol to obtain random copolymer 1 as a black purple solid. . The yield and yield were 1.20 g. The number average molecular weight (Mn) of the obtained polymer was 66,000, and the polydispersity (PDI) was 15.9.

¹ H-NMR: δ = 8.19 (br, 2H), 7.80 (br, 2H), 2.10 (br, 2H), 1.25 to 1.08 (br, 20H), 0.89 -0.75 (br, 12H) This analysis result supports the chemical structure on the right side of the chemical formula.

  The content of germanium atoms contained in the obtained polymer was measured using an ICP emission analyzer “IRIS-AP” manufactured by Jarrel Ash, and the composition represented by x and y from the germanium weight in the polymer weight The ratio was calculated to be x / y = 55/45.

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

  As a monomer constituting the random copolymer, 2,6-bis (trimethyltin) -4,8-didodecylbenzo [1,2-b: 4,5-b ′] dithiophene (76.5 mg, 0. 09 mmol), 2,6-bis (trimethyltin) -4,8-dipropylbenzo [1,2-b: 4,5-b ′] dithiophene (23.8 mg, 0.04 mmol) and 1- (4 6-Dibromothieno [3,4-b] thiophen-2-yl) -2-ethylhexane-1-one (50.1 mg, 0.12 mmol) as a polymerization solvent, DMF (0.3 mL), toluene (1. 4 mL) and tetrakis (triphenylphosphine) palladium (0) (3.4 mg, 2.98 μmol) were added, and the inside of the container was bubbled with argon gas for 20 minutes, and then heated at 110 ° C. for 10 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 obtained solution was poured into methanol (300 mL), and the precipitated solid was collected by filtration and dried under reduced pressure to obtain random copolymer 2 as a black purple solid. Random copolymer 2 (76.3 mg) obtained had Mn of 29,000 and PDI of 2.86.
¹ H-NMR: δ = 7.60-7.30 (br), 3.30-3.00 (Br), 2.09-1.10 (br), 1.00-0.60 (br)
This analysis result supports the chemical structure on the right side of the chemical formula.

  Also, the integral value of δ = 7.60-7.30 (br) attributed to the proton of the main skeleton and the integral value of δ = 2.9-1.10 (br) attributed to the proton of the side chain methylene chain. When the composition ratio indicated by x and y was calculated from the proportional calculation with the value, x / y = 76/24.

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

  As monomers constituting the random copolymer, 2,6-bis (trimethyltin) -4,8-bis (2-ethylhexyloxy) benzo [1,2-b: 4,5-b ′] dithiophene (69 0.0 mg, 0.09 mmol), 2,6-bis (trimethyltin) -4,8-dipropylbenzo [1,2-b: 4,5-b ′] dithiophene (23.8 mg, 0.04 mmol) and 1- (4,6-Dibromothieno [3,4-b] thiophen-2-yl) -2-ethylhexane-1-one (50.1 mg, 0.12 mmol) was used as a polymerization solvent in DMF (0.3 mL). , Toluene (1.4 mL), tetrakis (triphenylphosphine) palladium (0) (3.4 mg, 2.98 μmol) were added, and the inside of the container was bubbled with argon gas for 20 minutes. It was heated for 10 hours at ℃. 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 obtained solution was poured into methanol (300 mL), and the precipitated solid was collected by filtration and then dried under reduced pressure to obtain random copolymer 3 as a black purple solid. Random copolymer 3 (80.2 mg) obtained had Mn of 111,000 and PDI of 26.3.
¹ H-NMR: δ = 7.60-7.30 (br), 4.30-4.00 (br), 3.20-3.00 (br), 2.00-1.00 (br) 0.90-0.40 (br)
This analysis result supports the chemical structure on the right side of the chemical formula.

  Also, the integral value of δ = 7.60-7.30 (br) attributed to the proton of the main skeleton and the integral value of δ = 2.00-1.00 (br) attributed to the proton of the side chain methylene chain. When the composition ratio indicated by x and y was calculated from the proportional calculation with the value, x / y = 72/28.

Example 4
The monomer constituting the random copolymer 4 is charged with 2,6-bis (trimethyltin) -4,8-bis (2-ethylhexyloxy) benzo [1,2-b: 4,5-b ′. Dithiophene (89.7 mg, 0.117 mmol), 2,6-bis (trimethyltin) -4,8-dipropylbenzo [1,2-b: 4,5-b ′] dithiophene (7.5 mg, 0 .013 mmol) and 1- (4,6-dibromothieno [3,4-b] thiophen-2-yl) -2-ethylhexane-1-one (50.1 mg, 0.12 mmol). A black purple random copolymer 4 was obtained in the same manner as in Example 3. Random copolymer 4 (82.2 mg) obtained had Mn of 168,000 and PDI of 6.7.
¹ H-NMR: δ = 7.60-7.30 (br), 4.30-4.00 (br), 3.20-3.00 (br), 2.00-1.00 (br) 0.90-0.40 (br)
This analysis result supports the chemical structure on the right side of the chemical formula of Example 3.

  Also, the integral value of δ = 7.60-7.30 (br) attributed to the proton of the main skeleton and the integral value of δ = 2.00-1.00 (br) attributed to the proton of the side chain methylene chain. When the composition ratio represented by x and y was calculated from the proportional calculation with the value, x / y = 91/9.

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

  As monomers constituting the random copolymer, 2,6-bis (trimethyltin) -4,8-bis (2-ethylhexyloxy) benzo [1,2-b: 4,5-b ′] dithiophene (69 .0 mg, 0.09 mmol), 2,6-bis (trimethyltin) -4,8-bis (propyloxy) benzo [1,2-b: 4,5-b ′] dithiophene (25.1 mg,. 04 mmol) and 1- (4,6-dibromothieno [3,4-b] thiophen-2-yl) -2-ethylhexane-1-one (50.1 mg, 0.12 mmol) as DMF (0 3 mL), toluene (1.4 mL), tetrakis (triphenylphosphine) palladium (0) (3.4 mg, 2.98 μmol), and the inside of the container was bubbled with argon gas for 20 minutes. Later, heated at 110 ° C. 10 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 obtained solution was poured into methanol (300 mL), and the precipitated solid was collected by filtration and then dried under reduced pressure to obtain random copolymer 5 as a black purple solid. The obtained random copolymer 5 (65.4 mg) had a Mn of 36,000 and a PDI of 9.50.
¹ H-NMR: δ = 7.60-7.30 (br), 4.40-4.00 (br), 3.20-3.00 (br), 2.00-1.00 (br) 0.90-0.40 (br)
This analysis result supports the chemical structure on the right side of the chemical formula.

  Also, the integral value of δ = 7.60-7.30 (br) attributed to the proton of the main skeleton and the integral value of δ = 2.00-1.00 (br) attributed to the proton of the side chain methylene chain. When the composition ratio represented by x and y was calculated from the proportional calculation with the value, x / y = 70/30.

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

  As monomers constituting the random copolymer, 2,6-bis (trimethyltin) -4,8-bis (2-ethylhexyloxy) benzo [1,2-b: 4,5-b ′] dithiophene (69 0.0 mg, 0.09 mmol), 2,6-bis (trimethyltin) -4,8-dioctylbenzo [1,2-b: 4,5-b ′] dithiophene (29.8 mg, 0.04 mmol) and 1 -(4,6-dibromothieno [3,4-b] thiophen-2-yl) -2-ethylhexane-1-one (50.1 mg, 0.12 mmol) as a polymerization solvent, DMF (0.3 mL), Toluene (1.4 mL) and tetrakis (triphenylphosphine) palladium (0) (3.4 mg, 2.98 μmol) were added, and the inside of the container was bubbled with argon gas for 20 minutes. It was heated for 10 hours at ℃. 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 obtained solution was poured into methanol (300 mL), and the precipitated solid was collected by filtration and then dried under reduced pressure to obtain random copolymer 6 as a black purple solid. Mn of the obtained random copolymer 6 (67.1 mg) was 50,000, and PDI was 2.80.
¹ H-NMR: δ = 7.60-7.30 (br), 4.40-4.00 (br), 3.30-3.00 (br), 2.00-1.20 (br) 0.90-0.40 (br)
This analysis result supports the chemical structure on the right side of the chemical formula.

  Also, the integral value of δ = 7.60-7.30 (br) attributed to the proton of the main skeleton and the integral value of δ = 2.00-1.20 (br) attributed to the proton of the side chain methylene chain. When the composition ratio represented by x and y was calculated from the proportional calculation with the value, x / y = 69/31.

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

  As monomers constituting the random copolymer, 2,6-bis (trimethyltin) -4,8-bis (2-ethylhexyloxy) benzo [1,2-b: 4,5-b ′] dithiophene (69 0.0 mg, 0.09 mmol), 2,6-bis (trimethyltin) -4,8-dipropylbenzo [1,2-b: 4,5-b ′] dithiophene (23.8 mg, 0.04 mmol) and Ethylhexyl-6-dibromo-3-fluorothieno [3,4-b] thiophene-2-carboxylate (56.6 mg, 0.12 mmol) was used as a polymerization solvent for DMF (0.3 mL) and toluene (1.4 mL). Then, tetrakis (triphenylphosphine) palladium (0) (3.4 mg, 2.98 μmol) was added, and the inside of the container was bubbled with argon gas for 20 minutes. It was heated for 10 hours at ℃. 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 obtained solution was poured into methanol (300 mL), and the precipitated solid was collected by filtration and dried under reduced pressure to obtain random copolymer 7 as a black purple solid. Random copolymer 7 (62.9 mg) obtained had Mn of 37,000 and PDI of 10.2.
¹ H-NMR: δ = 7.90-7.00 (br), 4.70-4.00 (br), 2.40-1.20 (br), 0.90-0.60 (br)
This analysis result supports the chemical structure on the right side of the chemical formula.

  Also, the integral value of δ = 7.90-7.00 (br) attributed to the proton of the main skeleton and the integral value of δ = 2.40-1.20 (br) attributed to the proton of the side chain methylene chain. When the composition ratio indicated by x and y was calculated from the proportional calculation with the value, x / y = 72/28.

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

  As monomers constituting the random copolymer, 2,6-bis (trimethyltin) -4,8-bis (2-ethylhexyloxy) benzo [1,2-b: 4,5-b ′] dithiophene (69 .0 mg, 0.09 mmol), 2,6-bis (trimethyltin) -4,8-bis (isopropyloxy) benzo [1,2-b: 4,5-b ′] dithiophene (25.1 mg, 0.09 mmol). 04 mmol) and 1- (4,6-dibromothieno [3,4-b] thiophen-2-yl) -2-ethylhexane-1-one (50.1 mg, 0.12 mmol) as DMF (0 3 mL), toluene (1.4 mL), tetrakis (triphenylphosphine) palladium (0) (3.4 mg, 2.98 μmol), and the inside of the container was bubbled with argon gas for 20 minutes. After heated at 110 ° C. 10 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 obtained solution was poured into methanol (300 mL), and the precipitated solid was collected by filtration and then dried under reduced pressure to obtain a black purple solid and random copolymer 8 was obtained. Mn of the obtained random copolymer 8 (58.2 mg) was 30,000, and PDI was 19.8.
¹ H-NMR: δ = 7.60-7.30 (br), 4.40-4.00 (br), 3.50-3.00 (br), 1.80-1.57 (br) 1.50-1.20 (br), 1.00-0.80 (br)
This analysis result supports the chemical structure on the right side of the chemical formula.

  Also, the integral value of δ = 7.60-7.30 (br) attributed to the proton of the main skeleton and the integral value of δ = 1.80-0.80 (br) attributed to the proton of the side chain methylene chain. When the composition ratio indicated by x and y was calculated from the proportional calculation with the value, x / y = 68/32.

Example 9
Random copolymer 9 was synthesized according to the following reaction formula.

  As a monomer constituting the random copolymer, 2,6-bis (trimethyltin) -4,8-bis (2-ethylhexyloxy) benzo [1,2-b: 4,5-b ′] dithiophene (85 .0 mg, 0.12 mmol), 1- (4,6-dibromothieno [3,4-b] thiophen-2-yl) -2-ethylhexane-1-one (35.1 mg, 0.084 mmol) and 1, 3-Dibromo-5- (2-ethylhexyl) thieno [3,4-c] pyrrole-4,6-dione (15.3 mg, 0.036 mmol) was used as a polymerization solvent with DMF (0.3 mL), toluene (1 4 mL) and tetrakis (triphenylphosphine) palladium (0) (3.4 mg, 2.98 μmol) were added, and the inside of the container was bubbled with argon gas for 20 minutes. It was heated for 10 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 obtained solution was poured into methanol (300 mL), and the precipitated solid was collected by filtration and dried under reduced pressure to obtain random copolymer 9 as a black purple solid. The obtained random copolymer 9 (62.4 mg) had a Mn of 35,000 and a PDI of 6.5.
¹ H-NMR: δ = 7.60-7.30 (br), 4.40-4.00 (br), 3.50-3.00 (br), 1.85-1.57 (br) 1.50-1.15 (br), 1.00-0.80 (br)
This analysis result supports the chemical structure on the right side of the chemical formula.

  Also, the integral value of δ = 7.60-7.30 (br) attributed to the proton of the main skeleton and the integral value of δ = 1.50-0.15 (br) attributed to the proton of the side chain methylene chain. When the composition ratio represented by x and y was calculated from the proportional calculation with the value, x / y = 79/21.

[Production of mixed solution of random copolymer and electron-accepting material]
Random copolymer 1 (10.0 mg), PC ₇₁ BM (E110 manufactured by Frontier Carbon Co.) (20.0 mg) as an electron-accepting material, and chlorobenzene (1 mL) as a solvent at 100 ° C. for 6 hours And mixed. Then cooled to room temperature 20 ° C., to produce a solution containing a random copolymer and _PC 71 BM was filtered through a PTFE filter having a pore size of 1.0 .mu.m. Each random copolymer obtained in Examples 2 to 9 also produced a solution containing PC ₇₁ BM in the same manner.

[Production of Organic Thin Film Solar Cell Having Layer Consisting of Random 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. PEDOT: PSS aqueous solution (manufactured by HC Starck: CLEVIOS) serving as a hole transport layer on the substrate
PH500) was deposited 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 each random copolymer produced as described above and PC ₇₁ BM was applied by spin coating, and an organic photoelectric conversion layer (film) of the organic thin film solar cell was then applied. A thickness of about 100 nm) was obtained. After vacuum drying for 3 hours, lithium fluoride was vapor-deposited with a film thickness of 0.5 nm using a vacuum vapor deposition method, and then Al was vapor-deposited with a film 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 random copolymer obtained in Examples 1-9 was obtained. The area of the organic thin film solar cell was 0.25 cm ² .

(Comparative Example 1)
According to the information described in Patent Document 1, a block copolymer comprising a copolymer block of alkylfluorene and bisalkylthienylbenzothiadiazole and a copolymer block of alkylfluorene and thiophene pentamer was synthesized. . The detailed procedure of synthesis is described in Japanese Patent Application Laid-Open No. 2008-266459 (Patent Document 1). The obtained block copolymer had Mn of 9,000 and PDI of 2.8.

(Comparative Example 2)
Polymer A1 was synthesized according to the following reaction formula.

  In a 100 mL three-necked flask under a nitrogen atmosphere, 2,6-dibromo-4,4′-bis (2-ethylhexyl) -dithieno [3,2-b: 2 ′, 3 ′ as a monomer constituting the polymer A1. -D] germol (1.66 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) was added, further toluene (50 mL), 2M aqueous potassium carbonate solution (25 mL, 50 mmol), tetrakis (triphenylphosphine) palladium (0) (61.9 mg, 53.5 μmol) and aliquat 336 (2 mg, 4.95 μmol) were added, followed by stirring at 80 ° C. for 2 hours.

Thereafter, phenyl bromide (0.21 g, 1.34 mmol) was added as a terminal blocking agent, and the mixture was stirred at 80 ° C. for 18 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. Obtained. 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 A1 (1.03 g) as a black purple solid. Obtained polymer A1 had Mn of 18,000 and PDI of 2.36.
¹ H-NMR (270 MHz): δ = 8.20-7.95 (br, 2H), 7.90-7.12 (br, 2H), 2.34-2.10 (br, 4H), 1 .59-1.33 (br, 18H), 1.19-0.81 (br, 12H)

(Comparative Example 3)
Polymer B1 was synthesized according to the following reaction formula.

As a monomer constituting the polymer B1, 2,6-dibromo-4,4′-bis (2-ethylhexyl) -cyclopenta [2,1-b: 3,4-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, Polymer B1 (1.06 g) was obtained in the same manner as in Comparative Example 2 except that 2.68 mmol) was used. Mn of the obtained polymer B1 was 20,100, and PDI was 2.20.
¹ H-NMR (270 MHz): δ = 8.10-7.96 (br, 2H), 7.81-7.61 (br, 2H), 2.35-2.13 (br, 4H), 1 .59-1.32 (br, 18H), 1.18-0.81 (br, 12H)

(Comparative Example 4)
A blend was prepared by mixing the polymer A1 obtained in Comparative Example 2 and the polymer B1 obtained in Comparative Example 3 at a weight ratio of A1 / B1 = 70/30.

(Comparative Example 5)
Polymer A2 was synthesized according to the following reaction formula.

  In a 50 mL eggplant flask under a nitrogen atmosphere, 2,6-bis (trimethyltin) -4,8-didodecylbenzo [1,2-b: 4,5-b ′ as a monomer constituting the polymer A2 was used. ] 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, 0.75 mmol) ), DMF (6.2 mL), toluene (25 mL), and tetrakis (triphenylphosphine) palladium (0) (9.2 mg, 7.8 μmol) were added, and the inside of the container was filled with argon gas for 20 minutes. After bubbling, it was heated at 110 ° C. for 10 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 A2 (0.51 g) as a black purple solid. Obtained polymer A2 had Mn of 14,000 and PDI of 2.27.
¹ H-NMR (270 MHz): 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)

A mixed solution with an electron-accepting material was produced in the same manner as in the Examples, and an organic thin film solar cell having a layer made of a composition containing the polymer obtained in Comparative Examples 1 to 5 was manufactured using the mixed solution. . The area of the organic thin film solar cell was 0.25 cm ² .

[Evaluation of photoelectric conversion characteristics]
About the spectral sensitivity (photoelectric conversion wavelength band) of the produced photoelectric conversion element, it measured on the following measurement conditions using the spectral sensitivity measuring apparatus. The irradiation intensity at a specific wavelength at the time of measurement was calibrated using a photodiode (S1337-66BQ, manufactured by Hamamatsu Photonics). At the time of measurement, an irradiation light mask having the same area as the light receiving area of the photoelectric conversion element was worn to eliminate excessive light incidence.
<Measurement conditions>
Apparatus: Spectral sensitivity measuring device SM-250 type (manufactured by Spectrometer Co., Ltd.)
Light receiving area: 0.25cm2
Source meter: Keithley 2400 (manufactured by KEITHLEY)

About the photoelectric conversion efficiency of the produced photoelectric conversion element, it measured on the following measurement conditions using the solar simulator and the source meter. The irradiation intensity at the time of measurement was adjusted to be a solar cell evaluation standard using a photodiode (BS-520, manufactured by Spectrometer Co., Ltd.). At the time of measurement, an irradiation light mask having the same area as the light receiving area of the photoelectric conversion element was worn to eliminate excessive light incidence.
<Measurement conditions>
Solar simulator: PEC-L11 (Peccell Technology)
Source meter: KEITHLEY2400 (manufactured by KEITHLEY)
Irradiation spectrum: AM1.5
Irradiation intensity: 100 mW / cm ²
Light receiving area: 0.25 cm ²
The measurement results are shown in Table 1 (Examples 1 to 4), Table 2 (Examples 5 to 9), and Table 3 (Comparative Examples 1 to 5).

  As is clear from the table, the photoelectric conversion element produced using the π-electron conjugated random copolymer of the present invention has a higher photoelectric conversion efficiency than the photoelectric conversion element produced using the polymer obtained in the comparative example. showed that.

  In addition, the π-electron conjugated random copolymers (Examples 1 to 9) of the present invention having a donor group and an acceptor group composed of a condensed heterocyclic skeleton containing a thiophene ring as a part of the chemical structure, As compared with the polymer of Comparative Example 1 mainly containing a fluorene skeleton and a monocyclic thiophene skeleton, it was revealed that it has a light absorption band up to a long wavelength region and is excellent in photoelectric conversion efficiency.

  The π-electron conjugated random copolymer of the present invention can be used as a photoelectric conversion active layer of a photoelectric conversion element, and the photoelectric conversion element comprising the copolymer can be used as various photosensors including solar cells. is there.

Claims (9)

Following formula (1)
-(Ab)-(1)
(In the formula, -a- has a substituent and a donor group composed of a condensed heterocyclic skeleton in which at least three rings including a thiophene ring are condensed, and -b- may have a substituent.) Having at least two types of monomer units represented by an acceptor group having a fused heterocyclic skeleton of any of the nitrogen-containing fused heterocyclic skeleton, which may have a skeleton and a substituent,
A π-electron conjugated random polymer, wherein the condensed heterocyclic skeletons contained in each monomer unit are different from each other or / and the substituents of each monomer unit are different from each other. -A- is represented by the following formulas (2) to (6).

Wherein R ¹ is a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, R ² is an alkyl group having 1 to 18 carbon atoms, R ³ is an alkyl group having 1 to 18 carbon atoms, an alkoxy group, an aryl group, hetero Aryl group, alkylcarbonyl group or alkyloxycarbonyl group, R ⁴ is hydrogen atom, alkyl group having 1 to 18 carbon atoms, aryl group or halogen atom, R ⁵ is alkyl group having 1 to 18 carbon atoms, aryl group, alkylcarbonyl Group or alkyloxycarbonyl group, R ⁶ is hydrogen atom or halogen atom, V ¹ is C (R ² ) ₂ , Si (R ² ) ₂ , Ge (R ² ) ₂ or NR ² )
The π-electron conjugated random polymer according to claim 1, which is any group selected from the group consisting of: -A- is the following formula (2) or (3),

-B- is represented by the following formulas (7) and (15) to (17).

(Wherein R ^{1 to} R ⁶ and V ¹ are as defined above, V ² is NR ² , O, S or Se, V ⁴ is O or S, and n is a number from 0 to 3).
The π-electron conjugated random polymer according to claim 1, which is any group selected from the group consisting of:   The π electron conjugated random copolymer according to any one of claims 1 to 3, wherein the number average molecular weight is 1000 to 500,000 g / mol.   The π-electron conjugated random copolymer according to any one of claims 1 to 4, wherein the -a- contained in each monomer unit has different substituents.   The -a- contained in one monomer unit has an alkyl group or alkoxy group having 1 to 18 carbon atoms, and the -a- contained in the other monomer unit is different from 1 to It has 18 alkyl groups or alkoxy groups, The (pi) electron conjugated random copolymer as described in any one of Claims 1-5 characterized by the above-mentioned.   The composition containing an electron-accepting material and the pi-electron conjugated random copolymer of any one of Claims 1-6.   The photoelectric conversion element which has a layer which consists of a composition of Claim 7.   The photoelectric conversion element having a layer made of the composition according to claim 7, wherein the electron-accepting material is fullerene or a derivative thereof.