JP2016003238A - π-ELECTRON CONJUGATED POLYMER AND PHOTOELECTRIC CONVERSION ELEMENT USING THE SAME - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a donor-acceptor-type π-electron conjugated polymer which is constituted of a donor molecular structure and an acceptor molecular structure, and exhibits higher photoelectric conversion efficiency than conventional products having similar molecular structures and molecular weights.SOLUTION: Provided is a donor-acceptor-type π-electron conjugated polymer represented by the following chemical formula (1) (in the formula, -Ar- is a donor group constituted of a condensed heterocyclic backbone having at least three rings condensed including a thiophene ring; -Ar- is an acceptor group containing a thiophene backbone which may have a substituent or a nitrogen-containing condensed heterocyclic backbone which may have a substituent; x:y is from 1:99 to 20:80; and r represents that the polymer is a random polymer).

Description

  The present invention relates to a donor-acceptor type π-electron conjugated polymer composed of a donor molecular structure and an acceptor molecular structure, and an organic semiconductor photoelectric conversion element formed from an organic semiconductor composition using the same.

  Solar cells are currently attracting attention as a potential energy source for increasing energy problems. As semiconductor materials for photovoltaic elements in solar cells, inorganic semiconductors such as compound semiconductors, amorphous silicon, polycrystalline silicon, and single crystal silicon are used. However, solar cell power generation is expensive compared to thermal power generation and nuclear power generation, which are currently mainstream, due to the high manufacturing cost of the inorganic semiconductor. A main factor that increases the manufacturing cost is that a thin film is formed by a vapor deposition process under high temperature and vacuum conditions. On the other hand, when an organic material such as a conjugated polymer is used as a semiconductor material, there is an advantage that a vapor deposition process is unnecessary and the manufacturing process can be simplified. For this reason, studies on solar cells (photoelectric conversion elements) using organic semiconductors and organic dyes are underway.

Factors that determine the performance of the photoelectric conversion element mainly include short-circuit current density (J _SC ), open-circuit voltage (V _OC ), and fill factor (FF). Among them, J _SC is because it is highly dependent on the optical absorption properties of the semiconductor material, it is possible to better light absorbing region is wide material of the material converts to a current more light. In an organic material, a compound having a wide light absorption region needs to have a small energy difference (band gap) between the highest occupied orbital (HOMO) level and the lowest unoccupied orbital (LUMO) level. In addition, from the viewpoint of the coatability of a compound at the time of device fabrication, research on polymers rather than small molecules has been actively promoted.

  Examples of the compound having these characteristics include a donor-acceptor type π-electron conjugated polymer which is a narrow band gap polymer. For example, Non-Patent Document 1 discloses a copolymer of cyclopentadithiophene, which is an electron donating (donor) group, and benzothiadiazole, which is an electron accepting group, as an example of a narrow band gap polymer. Examples of copolymers with benzothiadiazole using dithienosilol as a donor molecule so as to have a wider light absorption region are disclosed in Patent Document 1 and Non-Patent Document 2.

Narrow bandgap polymers disclosed in Patent Document 1, Non-Patent Document 1 and Non-Patent Document 2 have a wide absorption wavelength band, and organic solar cells produced using these have promising high _JSC and photoelectric conversion efficiency. Material. However, further improvement in photoelectric conversion efficiency is necessary for practical use.

  On the other hand, the narrow band gap polymer has a problem that the performance difference between synthetic batches is large. In Non-Patent Document 1, a material having the same molecular structure as that reported by the authors in a previous paper (Non-Patent Document 3) was synthesized by the authors himself using the same technique, and When the conversion element was produced and evaluated, the photoelectric conversion efficiency different from the former was expressed. In the paper, the authors themselves describe that there are performance differences between synthetic batches.

  In general, donor-acceptor type π-electron conjugated polymers that are polymerized by the cross-coupling method are considered to be polymers in which the donor molecular structure and the acceptor molecular structure are alternately linked. Depending on the functional group, homo-coupling proceeds and the chain between the donor molecule and the acceptor molecule is disrupted.

  For example, in a Stille coupling reaction using a trialkyltin at the reactive end of the donor molecular monomer, a halogen atom at the reactive end of the acceptor molecular monomer, and a Pd complex as the polymerization catalyst, it is used as the catalyst. When Pd is zero-valent, the cross-coupling reaction proceeds, but when Pd is oxidized and becomes divalent, it catalyzes the homocoupling of the donor molecule monomer having trialkyltin at the reactive end. A reaction route is conceivable.

  In donor-acceptor type π-electron conjugated polymers, disruption of the chain between the donor molecular structure and the acceptor molecular structure results in an increase in the twist of the molecule due to steric hindrance, leading to an increase in the band gap and a decrease in charge mobility. The performance of the conversion element is degraded.

Special table 2010-507233 gazette

Journal of the American Chemical Society, 2008, 130, p. 3619-3623 Journal of the American Chemical Society, 2008, 130, p. 16144-16145 Nature Materials, 2007, Vol. 6, p. 497-500

  The present invention has been made to solve the above-mentioned problems, and is a donor that exhibits a higher photoelectric conversion efficiency than a conventional product having a similar molecular structure and molecular weight, which is composed of a donor molecular structure and an acceptor molecular structure. An object of the present invention is to provide an acceptor-type π-electron conjugated polymer and a photoelectric conversion element using the polymer.

（式中、−Ａｒ^１−は置換基を有し、チオフェン環を含む少なくとも三環が縮環した縮合ヘテロ環骨格からなるドナー性の基であり、−Ａｒ^２−は置換基を有してもよいチエノチオフェン骨格又は置換を有してもよい窒素含有縮合ヘテロ環骨格を有するアクセプター性の基であり、ｘ：ｙが１：９９〜２０：８０であり、ｒはランダムであることを示す。）で表されることを特徴とする。 The present inventors analyzed in detail a donor-acceptor type π-electron conjugated polymer having different photoelectric conversion efficiency when producing and evaluating a photoelectric conversion element while having the same molecular weight and molecular weight distribution. However, the inventors have found that the photoelectric conversion efficiency tends to be high for those in which the ratio of the single repeating unit of donor molecule and the chain repeating unit of donor molecule and acceptor molecule is in a specific range, and the present invention has been completed. A donor-acceptor type π-electron conjugated polymer made to achieve the above-mentioned object is represented by the following chemical formula (1).

(In the formula, -Ar ¹ -has a substituent, and is a donor group composed of a condensed heterocyclic skeleton in which at least three rings including a thiophene ring are condensed, and -Ar ² -has a substituent. An acceptor group having a thienothiophene skeleton that may be substituted or a nitrogen-containing fused heterocyclic skeleton that may have a substituent, wherein x: y is from 1:99 to 20:80, and r is random )).

  The π-electron conjugated polymer preferably has a weight average molecular weight of 30,000 to 100,000 g / mol.

（式中、Ｒ^１は、置換基を有してもよい炭素数１〜１８のアルキル基、アルコキシ基、アリール基、ヘテロアリール基、アルキルカルボニル基又はアルキルオキシカルボニル基である）であることが好ましい。 In the π-electron conjugated polymer, the -Ar ¹ -is represented by the following chemical formula (2)

(Wherein R ¹ is an optionally substituted alkyl group having 1 to 18 carbon atoms, an alkoxy group, an aryl group, a heteroaryl group, an alkylcarbonyl group, or an alkyloxycarbonyl group). preferable.

（式中、Ｒ^２は、置換基を有してもよい炭素数１〜１８のアルキル基、アルコキシ基、アリール基、ヘテロアリール基、アルキルカルボニル基又はアルキルオキシカルボニル基であり、Ｘ^１は水素原子又はハロゲン原子である）であることが好ましい。 In the π-electron conjugated polymer, the —Ar ² — is represented by the following chemical formula (3)

(Wherein R ² is an optionally substituted alkyl group having 1 to 18 carbon atoms, an alkoxy group, an aryl group, a heteroaryl group, an alkylcarbonyl group or an alkyloxycarbonyl group, and X ¹ is hydrogen. It is preferably an atom or a halogen atom.

であり、前記−Ａｒ^２−が、下記化学式（５）

であってもよい。 In the π-electron conjugated polymer, the —Ar ¹ — is represented by the following chemical formula (4):

The —Ar ² — represents the following chemical formula (5)

It may be.

  Similarly, an organic semiconductor composition made to achieve the above object includes the π-electron conjugated polymer.

  Similarly, an organic semiconductor device made to achieve the above object includes the π-electron conjugated polymer.

  The organic semiconductor device is preferably a photoelectric conversion element.

  Similarly, a photoelectric conversion element made to achieve the above object has a layer containing the π-electron conjugated polymer and an electron-accepting material.

  Similarly, a tandem photoelectric conversion element made to achieve the above object has the photoelectric conversion element.

  The π-electron conjugated polymer of the present invention can be provided with a photoelectric conversion element composed of a donor molecular structure and an acceptor molecular structure and exhibiting higher photoelectric conversion efficiency than conventional products having the same molecular structure and molecular weight. It becomes.

It is a schematic cross section of the photoelectric conversion element with which the pi-electron conjugated polymer to which this invention is applied contained in the photoelectric conversion active layer.

  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 polymer of the present invention is represented by the chemical formula (1), and is composed of a donor-acceptor type π-electron conjugated polymer composed of a single repeating unit of donor molecule and a chain repeating unit of a donor molecule and an acceptor molecule. It is. The band gap of the monomer unit can be controlled by a combination of —Ar ¹ — and —Ar ² —. 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.

—Ar ¹ — has a substituent and is a donor group composed of a condensed heterocyclic skeleton in which at least three rings including a thiophene ring are condensed. Examples of the condensed heterocyclic skeleton include cyclopentadithiophene, dithienopyrrole, dithienosilole, dithienogermol, benzodithiophene, and naphthodithiophene. Among these, -Ar ¹ -is a benzodithiophene represented by the following chemical formula (2) from the viewpoint that it has excellent planarity and can obtain high photoelectric conversion efficiency when a photoelectric conversion element is produced. Is preferred.

In the chemical formula (2), R ¹ is an optionally substituted alkyl group having 1 to 18 carbon atoms, an alkoxy group, an aryl group, a heteroaryl group, an alkylcarbonyl group, or an alkyloxycarbonyl group.

  The alkyl group may be a linear or branched alkyl group or a cyclic cycloalkyl group. Examples of the alkyl group 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, Linear or branched alkyl groups such as tert-pentyl group, n-hexyl group, isohexyl group, 2-ethylhexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, dodecyl group A cycloalkyl group such as cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, cyclononyl group, cyclodecyl group, cycloundecyl group, cyclododecyl group; Among these, an alkyl group having 3 or more carbon atoms is preferable from the viewpoint of easy synthesis and excellent solubility. The upper limit of the carbon number is not particularly limited, but 20 or less is preferable from the viewpoint of solubility. Here, the carbon number means the carbon number excluding the substituent exemplified below.

  The alkyl group may have a substituent. Examples of the substituent include an aryl group such as a phenyl group, a naphthyl group, an anthryl group, and a phenanthryl group; a pyridyl group, a thienyl group, a furyl group, a pyrrolyl group, and an imidazolyl group. , Pyrazinyl group, oxazolyl group, thiazolyl group, pyrazolyl group, benzothiazolyl group, benzoimidazolyl group and other heteroaryl groups; methoxy group, ethoxy group, n-propyloxy group, isopropoxy group, n-butoxy group, isobutoxy group, sec- Butoxy group, tert-butoxy group, pentyloxy group, isopentyloxy group, neopentyloxy group, n-hexyloxy group, cyclohexyloxy group, heptyloxy group, n-octyloxy group, nonyloxy group, n-decyloxy group, n-dodecyloxy group, etc. Alkoxy group; alkylthio group such as methylthio group, ethylthio group, propylthio group, butylthio group; arylthio group such as phenylthio group, naphthylthio group; methoxycarbonyl group, ethoxycarbonyl group, propoxycarbonyl group, isopropoxycarbonyl group, n-butoxycarbonyl Groups, isobutoxycarbonyl groups, sec-butoxycarbonyl groups, tert-butoxycarbonyl groups, pentyloxycarbonyl groups, hexyloxycarbonyl groups, heptyloxycarbonyl groups, alkoxycarbonyl groups such as octyloxycarbonyl groups; methyl sulfoxide groups, Alkyl sulfenyl groups such as ethyl sulfoxide groups; aryl sulfoxide groups such as phenyl sulfoxide groups; methyl sulfonyloxy groups; Sulphonic acid ester groups such as onyloxy group, phenylsulfonyloxy group, methoxysulfonyl group, ethoxysulfonyl group, and phenyloxysulfonyl group; 1 such as dimethylamino group, diphenylamino group, methylphenylamino group, methylamino group, and ethylamino group Primary or secondary amino group; methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl substituted with acetyl, benzoyl, benzenesulfonyl, tert-butoxycarbonyl, etc. Group, an amino group which may be substituted with an alkyl group such as a phenyl group or an aryl group; a cyano group; a nitro group; a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom or an iodine atom. Among these, from the viewpoint of expanding the π-conjugated system of the main skeleton, an aryl group such as a phenyl group or a naphthyl group, or a heteroaryl group such as a pyridyl group or a thienyl group is preferable.

  Examples of the alkoxy group include methoxy group, ethoxy group, n-propyloxy group, isopropoxy group, n-butoxy group, isobutoxy group, sec-butoxy group, tert-butoxy group, pentyloxy group, isopentyloxy group, A neopentyloxy group, n-hexyloxy group, cyclohexyloxy group, heptyloxy group, n-octyloxy group, nonyloxy group, n-decyloxy group, n-dodecyloxy group and the like can be mentioned.

  Examples of the aryl group include a phenyl group, a naphthyl group, an anthryl group, and a phenanthryl group. These aryl groups may have a substituent, and as such a substituent, a substituent other than the aryl group exemplified in the description of the alkyl group, the above-described alkyl group, and the like can be used.

  Examples of the heteroaryl group include a pyridyl group, a thienyl group, a furyl group, a pyrrolyl group, an imidazolyl group, a pyrazinyl group, an oxazolyl group, a thiazolyl group, a pyrazolyl group, a benzothiazolyl group, and a benzoimidazolyl group. These heteroaryl groups may have a substituent, and as such a substituent, a substituent other than the heteroaryl group exemplified in the description of the alkyl group, the above-described alkyl group, and the like can be used. .

  Examples of the alkylcarbonyl group include a methylcarbonyl group, an ethylcarbonyl group, a propylcarbonyl group, an isopropylcarbonyl group, an n-butylcarbonyl group, an isobutylcarbonyl group, a sec-butylcarbonyl group, a tert-butylcarbonyl group, a pentylcarbonyl group, Examples include alkoxycarbonyl groups such as a hexylcarbonyl group, a heptylcarbonyl group, and an octyloxycarbonyl group.

  Examples of the alkyloxycarbonyl group include methoxycarbonyl group, ethoxycarbonyl group, propoxycarbonyl group, isopropoxycarbonyl group, n-butoxycarbonyl group, isobutoxycarbonyl group, sec-butoxycarbonyl group, tert-butoxycarbonyl group, pentyl. Examples thereof include an oxycarbonyl group, a hexyloxycarbonyl group, a heptyloxycarbonyl group, and an octyloxycarbonyl group.

-Ar ¹ -is more preferably the following chemical formula (4).

-Ar ^1- 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 of the π-electron conjugated copolymer changes, so that it can be controlled to any band gap in accordance with the configuration of the organic photoelectric conversion element, and the photoelectric conversion element has excellent conversion efficiency Can be provided.

—Ar ² — is an acceptor group having a thienothiophene skeleton which may have a substituent or a nitrogen-containing condensed heterocyclic skeleton which may have a substituent. Examples of the nitrogen-containing fused heterocyclic skeleton which may have a substituent include, for example, benzothiadiazole, benzoselenadiazole, benzotellodiazole, benzotriazole, pyridinothiadiazole, pyridinoselenadiazole, thienothiadiazole, naphthobis Examples include thiadiazole, naphthothiadiazole, quinoxaline, benzobisthiadiazole, thienopyrrole, diketopyrrolopyrrole, thiazolothiazole, triazine, and tetrazine. -Ar 2 ^- is preferably a acceptor molecular structure represented by the following chemical formula (3).

In the chemical formula (3), R ² is an optionally substituted alkyl group having 1 to 18 carbon atoms, an alkoxy group, an aryl group, a heteroaryl group, an alkylcarbonyl group, or an alkyloxycarbonyl group. These may be the same as those exemplified for R ¹ , and the same examples of such substituents.

In the chemical formula (3), X ¹ is a hydrogen atom or a halogen atom. As a halogen atom, a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom are mentioned, for example.

-Ar ² - is more preferably a following chemical formula (5).

  In the chemical formula (1), x and y are composition ratios (mol%) of each unit. x is a ratio of repeating units in which two or more donor molecules are linked, y is a ratio of chain repeating units of donor molecules and acceptor molecules, and x: y is 1:99 to 20:80. That is, the π-electron conjugated polymer of the present invention is basically an alternating copolymer of a donor molecule and an acceptor molecule, but 1-20 mol% of a donor molecule alone is inserted, and a structure in which a donor molecule is continuous in part. It is a copolymer having. x is preferably 1 to 10 mol%. When x is larger than 20 mol%, the photoelectric conversion efficiency of the donor-acceptor type π-electron conjugated polymer is lower than that in the above range. This is thought to be because if the linkage between the donor molecular structure and the acceptor molecular structure is disturbed, the twist of the molecule increases due to steric hindrance, leading to an increase in the band gap and a decrease in charge mobility. On the other hand, it is difficult to industrially produce x smaller than 1 mol%.

The values of x and y shown in the formula (1) can be calculated from the area ratio of carbon characteristic of —Ar ¹ — and —Ar ² — obtained from ¹³ C-NMR.

The π-electron conjugated polymer of the present invention preferably has a donor-acceptor chain (Ar ¹ -Ar ² ) in the composition of 80.0 to 99.0 mol%. In the π-electron conjugated polymer, the composition ratio (mol%) of the donor unit (Ar ¹ ) and the acceptor unit (Ar ² ) in the composition is donor unit (Ar ¹ ): acceptor unit (Ar ² ), It is preferable that it is 50.5: 49.5-60: 40.

  The π-electron conjugated polymer of the present invention may contain another monomer unit having a different side chain structure as long as the effects of the present invention are not impaired. Moreover, the form which the polymer block which consists of pi electron conjugated polymer represented by the said Chemical formula (1) which is a random copolymer may comprise a part of block copolymer may be sufficient. The molecular chain may be linear, branched, physically or chemically cross-linked.

  The weight average molecular weight of the π-electron conjugated polymer of the present invention is preferably 5,000 to 5,000,000 g / mol from the viewpoints of processability, crystallinity, solubility, photoelectric conversion characteristics, etc., and 30,000 to 100,000. More preferably, it is 000 g / mol. If the weight average molecular weight is too high, the solubility is lowered, and the workability of a thin film or the like may be lowered. On the other hand, if the weight average molecular weight is too low, crystallinity, film stability, photoelectric conversion characteristics and the like may be deteriorated.

  A weight average molecular weight means the weight average molecular weight of polystyrene conversion by gel permeation chromatography (henceforth GPC). The weight average molecular weight of the π-electron conjugated polymer 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 polymers of the present invention have low solubility around room temperature. In such cases, the weight average molecular weight may be determined by high-temperature GPC chromatography using dichlorobenzene, trichlorobenzene or the like as a solvent. .

  The degree of polymerization of the π-electron conjugated polymer is not particularly limited as long as the requirements of the present invention are satisfied, but is preferably 2,000 or less from the viewpoint of dissolving in an organic solvent to obtain a uniform solution. Moreover, it is preferable that it is 5 or more from a viewpoint of obtaining a homogeneous organic thin film, and it is more preferable that it is 15 or more.

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

The π-electron conjugated copolymer represented by the chemical formula (1) of the present invention is obtained by, for example, forming a monomer constituting a monomer unit (—Ar ¹ —) and a monomer unit (—Ar ² —) with a desired content. It can be produced by mixing at a charging ratio and polymerizing. A known coupling reaction can be used for the polymerization.

In more detail, according to the following reaction formula (I), a reactive unit for constituting the monomer unit (—Ar ¹ —) and the monomer unit (—Ar ² —) in the presence of a catalyst. The π-electron conjugated copolymer of the present invention can be obtained by reacting M ^q1 -Ar ¹ -M ^q1 and M ^q2 -Ar ² -M ^q2 which are monomers and polymerizing by a known coupling reaction. it can.

In the formula (I), —Ar ¹ —, —Ar ² —, x, and y are as described above. 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 straight chain having 1 to 4 carbon atoms) An alkyl group, 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 boron. acid, comprising boronic acid ester, -MgX, -ZnX, a -SiX _3, or -SnRa _3. n is a number of 1 or more.

^{M q1 -Ar} 1 ^-M q1 and ^{M q2 -Ar} 2 ^-M q2 shown in formula (I) can be synthesized by a known reaction.

  The π-electron conjugated copolymer represented by the chemical formula (1) of the present invention 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 an atom or A terminal structure in which a group may have a detached hydrogen atom, and these terminal groups are further substituted with an end capping agent such as an aromatic halide such as benzene bromide or an aromatic boronic acid compound. It may be.

In the formula (I), examples of the halogenating agent used for the synthesis of M ^q1 -Ar ¹ -M ^q1 or M ^q2 -Ar ² -M ^q2 include N-chlorosuccinimide, N-chlorophthalic acid imide, chlorine, five Chlorinating agents such as phosphorus chloride, thionyl chloride, 1,2-dichloro-1,1,2,2-tetrafluoroethane; N-bromosuccinimide, N-bromophthalimide, N-bromoditrifluoromethylamine, bromine, Brominating agents such as boron tribromide, copper bromide, silver bromide, t-butyl bromide, bromine oxide, 1,2-dibromo-1,1,2,2-tetrafluoroethane; iodine, iodotri And an iodinating agent such as chloride, N-iodophthalimide, and N-iodosuccinimide. Among these, it is preferable to use a brominating agent or an iodinating agent, and it is more preferable to use a brominating agent.

The amount of the halogenating agent to be used is not particularly limited, and is preferably ² to 8 mol with respect to 1 mol of the compound represented by H—Ar ¹ —H or H—Ar ² —H. When the amount of the halogenating agent used is less than 2 mol, the substitution reaction of bromine becomes insufficient, or the separation and purification work with the compound represented by H-Ar ¹ -H or H-Ar ² -H as the raw material is complicated. There is a risk of becoming. On the other hand, when the amount of the halogenating agent used exceeds 8 mol, there is a risk that a substitution reaction other than the intended position occurs, and the removal of the unreacted halogenating agent becomes complicated.

The halogenation reaction is preferably performed in the presence of a solvent. Examples of such solvents include saturated aliphatic hydrocarbons such as pentane, hexane, heptane, octane, nonane, decane, and cyclohexane; aromatic hydrocarbons such as benzene, toluene, ethylbenzene, propylbenzene, xylene, and ethyltoluene; dimethyl ether, Examples thereof include ethers such as ethyl methyl ether, diethyl ether, dipropyl ether, butyl methyl ether, t-butyl methyl ether, dibutyl ether, tetrahydrofuran and 1,4-dioxane. Of these, two or more may be used in combination. The amount of the solvent used is preferably in the range of 1 to 100 parts by mass with respect to 1 part by mass of the compound represented by H-Ar ¹ -H or H-Ar ² -H. Moreover, it does not specifically limit about the reaction temperature at the time of making a halogenating agent react, It is preferable that it is the range of -100-100 degreeC. When reaction temperature is less than -100 degreeC, there exists a possibility that reaction rate may become very slow, and it is more preferable that it is -20 degreeC or more. On the other hand, when reaction temperature exceeds 100 degreeC, there exists a possibility of accelerating | stimulating decomposition | disassembly of a product, It is more preferable that it is 50 degrees C or less, and it is still more preferable that it is 10 degrees C or less. The reaction time is preferably 1 minute to 20 hours, and more preferably 0.5 to 10 hours. The reaction pressure is preferably 0 to 3 MPa (gauge pressure).

In Formula (I), M ^q1 or M ^q2 is other than a halogen atom, that is, boronic acid, boronic acid ester, —MgY, —ZnY, and —SnR ^a ₃ (wherein R ^a is a linear alkyl having 1 to 4 carbon atoms) Group, Y is any one selected from a halogen atom), a halogenating agent was first reacted with the compound represented by H-Ar ¹ -H or H-Ar ² -H to halogenate both ends. It can be obtained by obtaining an intermediate and then reacting the intermediate with a terminal functionalizing agent. As the halogenating agent used at this time, the halogenating agents exemplified above can be preferably used.

Examples of the terminal functionalizing agent include trialkyltin halides. In this case, M ^q1 or M ^q2 is —SnR ^a ₃ . In addition, for example, when a boronating agent or a boronic acid esterifying agent is used, M ^q1 or M ^q2 becomes a boronic acid or a boronic acid ester. A terminal functionalizing agent is not specifically limited, A well-known thing can be selected.

  Specific examples of the trialkyltin halide used as the terminal functionalizing agent include trimethyltin chloride, triethyltin chloride, tri-n-propyltin chloride, and tri-n-butyltin chloride. Among them, it is desirable to use trimethyltin chloride. Specific examples of the boronating agent include trimethyl borate, triethyl borate, tri-n-propyl borate, tri-n-butyl borate, triisopropyl borate and the like. Among them, it is desirable to use trimethyl borate from the viewpoint of reaction efficiency. Specific examples of the boronic acid esterifying agent include, for example, 4, 4, 5, 5-tetramethyl-1, 3, 2-dioxaborolane, 2-methoxy-4, 4, 5, 5-tetramethyl-1, 3, Examples include 2-dioxaborolane, 2-isopropoxy-4, 4,5,5-tetramethyl-1,3,2-dioxaborolane. Among these, it is desirable to use 2-isopropoxy-4, 4, 5, 5-tetramethyl-1, 3, 2-dioxaborolane.

  The terminal functionalization reaction is preferably performed in the presence of a solvent. As such a solvent, the same solvents as exemplified in the halogenation reaction can be used, and two or more kinds may be used in combination. The usage-amount of a solvent is preferable in it being 1-100 mass parts with respect to 1 mass part of intermediate bodies, and it is more preferable in it being 1-50 mass parts. Moreover, it does not specifically limit about the reaction temperature at the time of making a terminal functionalizing agent react, It is preferable that it is the range of -100-100 degreeC. When reaction temperature is less than -100 degreeC, there exists a possibility that reaction rate may become very slow, and it is more preferable that it is -80 degreeC or more. On the other hand, when reaction temperature exceeds 100 degreeC, there exists a possibility of accelerating | stimulating decomposition | disassembly of a product, It is more preferable that it is 50 degrees C or less, and it is still more preferable that it is 0 degrees C or less. The reaction time is preferably 1 minute to 20 hours, and more preferably 0.5 to 5 hours. The reaction pressure is preferably 0 to 3 MPa (gauge pressure).

  The terminal functionalization reaction is preferably performed in the presence of a base catalyst. As the base to be used, an organic lithium compound is suitable. Examples of the organic lithium compound include alkyllithium compounds such as methyllithium, n-butyllithium, sec-butyllithium, and tert-butyllithium; aryllithium compounds such as phenyllithium; alkenyllithium compounds such as vinyllithium; lithium diisopropylamide And lithium amide compounds such as lithium bistrimethylsilylamide. Among these, it is preferable to use an alkyl lithium compound. It does not specifically limit about the usage-amount of an organolithium compound, It is preferable that it is 0.5-5 mol with respect to 1 mol of intermediate bodies. When the amount of the organolithium compound used exceeds 5 mol, there is a risk of promoting side reactions and product decomposition.

  It is preferable to use a transition metal complex as a catalyst for the coupling reaction when the π-electron conjugated copolymer represented by the chemical formula (1) of the present invention is produced. Usually, transition metal complexes belonging to Groups 3 to 10 of the periodic table (Group 18 long-period periodic table), particularly, Groups 8 to 10 are 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 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 Liter; Tetramethyl Ethylenediamine, bipyridine, can be preferably used, such as nitrogen-containing ligands such as acetonitrile.

  In addition, although the usage-amount of a complex changes with pi electron conjugated polymers to manufacture, 0.001-0.1 mol is preferable with respect to a monomer. When there are too many catalysts, it will cause the molecular weight fall of the polymer obtained. It is also economically disadvantageous. On the other hand, when there are too few catalysts, reaction rate will become slow and stable production will become difficult.

  The π-electron conjugated polymer 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 polymer to be produced, but a commercially available solvent can be generally selected. Examples of the solvent used here include 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. Ether solvents such as methyl ether and diphenyl ether; aliphatic or alicyclic saturated hydrocarbon solvents such as pentane, hexane, heptane and cyclohexane; aromatic hydrocarbon solvents such as benzene, toluene and xylene; Alkyl halide solvents; aromatic aryl halide solvents such as chlorobenzene and dichlorobenzene; solvents such as dimethylformamide, diethylformamide and N-methylpyrrolidone De solvents; such as water and mixtures thereof. The amount of the solvent used is preferably in the range of 1 to 1000 times the mass of the monomer of the π-electron conjugated polymer to be produced. Among these, from the viewpoint of the solubility of the obtained π-electron conjugated polymer and the stirring efficiency of the reaction solution, it is more preferably 10 times by mass or more, and more preferably 100 times by mass or less from the viewpoint of reaction rate.

  The polymerization temperature for synthesizing the π-electron conjugated polymer of the present invention varies depending on the kind of the π-electron conjugated polymer to be produced, but is usually in the range of −80 ° C. to 200 ° C. In the present invention, the pressure of the reaction system is not particularly limited, but is preferably from 0.1 to 10 atm, and more preferably at about 1 atm. The reaction time is preferably 20 minutes to 150 hours.

  The π-electron conjugated copolymer represented by the chemical formula (1) of the present invention is usually used for reprecipitation, solvent removal under heating, solvent removal under reduced pressure, solvent removal with steam (steam stripping), etc. From the reaction solution, it can be isolated and obtained. The crude product thus obtained can be purified by washing or extraction using a commercially available solvent using a Soxhlet extractor.

  Examples of the solvent used here include ether solvents such as tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, dimethyl ether, and ethyl methyl ether; aliphatic or alicyclic saturation such as pentane, hexane, heptane, and cyclohexane. Hydrocarbon solvents; aromatic hydrocarbon solvents such as benzene, toluene and xylene; ketone solvents such as acetone, ethyl methyl ketone and diethyl ketone; alkyl halide solvents such as dichloromethane and chloroform; chlorobenzene and dichlorobenzene Aromatic aryl halide solvents; amide solvents such as dimethylformamide, diethylformamide, N-methylpyrrolidone; water and mixtures thereof.

When synthesizing the π-electron conjugated polymer of the present invention, it is important to control the oxygen concentration contained in the system to 1 to 50 ppm with respect to the polymerization solvent from the viewpoint of suppressing homocoupling due to oxidation of the polymerization catalyst. It is. By controlling the oxygen concentration within the above range, a donor-acceptor type π-electron conjugated polymer having a composition x value of 1 to 20% can be synthesized. In synthesizing the π-electron conjugated polymer of the present invention, a known method such as vacuum degassing, freeze degassing, N ₂ bubbling, ultrasonic irradiation can be used to reduce the oxygen concentration in the system. . When synthesizing the π-electron conjugated polymer of the present invention, an oxygen absorbent may be added to reduce the oxygen concentration in the system. For example, when triphenylphosphine used as a ligand for the polymerization catalyst (palladium) is added, triphenylphosphine reacts strongly with oxygen in the system, thereby suppressing the oxidation of palladium and consequently suppressing homocoupling. Can do.

  The π-electron conjugated polymer of the present invention can be used as an organic semiconductor material taking advantage of the above characteristics. In particular, it is useful for organic semiconductor devices such as thin-film organic transistors, organic EL elements, and photoelectric conversion elements.

  The organic semiconductor composition containing the π-electron conjugated polymer in the present invention is not particularly limited as long as it contains the π-electron conjugated polymer of the present invention, organic semiconductor materials other than the present invention, solvents, crystallization agents, It includes compositions with antioxidants, various forms of metal materials, inorganic crystals and so on. When the π-electron conjugated polymer of the present invention is formed by a coating process, it may be in the form of a solution containing at least one component that can dissolve the π-electron conjugated polymer.

  The composition containing the π-electron conjugated polymer of the present invention may be a solution to which a poor solvent is added in order to improve the crystallinity of the polymer, and improves the stability of the π-electron conjugated polymer of the present invention. A stabilizer such as an antioxidant may be included for the purpose. A thin film after the solution is formed into a film by various coating methods and the solvent is distilled off is also included in the composition of the present invention. In addition, when the composition containing the π-electron conjugated polymer of the present invention is used for a photoelectric conversion element, it may contain an electron-accepting semiconductor.

  As an example of the organic semiconductor device containing the π-electron conjugated polymer of the present invention, a photoelectric conversion element is preferably exemplified. Hereinafter, description will be given with reference to the drawings.

  A preferred embodiment of the photoelectric conversion element is shown in FIG. The photoelectric conversion element 10 includes a positive electrode 25 that is a transparent electrode, a hole transport layer 24 that is an arbitrary smooth layer, and a photoelectric conversion active layer 23 that is an organic photoelectric conversion layer containing a π-electron conjugated polymer on a substrate 26. The electron transport layer 22 and the negative electrode 21 which are arbitrary smooth layers are sequentially laminated. In the example of FIG. 1, the substrate 26 side is a positive electrode 25 that is a transparent electrode, and the side far from the substrate is a negative electrode 21 that is a counter electrode. The structure of the photoelectric conversion element 10 is not limited to these, and the positive electrode and the negative electrode, the hole transport material, and the electron transport material may be interchanged depending on the characteristics of the material.

The π-electron conjugated polymer of the present invention can be used for the photoelectric conversion active layer 23 of the photoelectric conversion element 10 by forming an organic semiconductor 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 characteristics. For example, 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA), 3,4 , 9,10-perylenetetracarboxylic dianhydride (PTCDA), N, N′-dioctyl-3,4,9,10-naphthyltetracarboxydiimide (NTCDI-C ₈ H), 2- (4-biphenylyl)- Oxazole derivatives such as 5- (4-t-butylphenyl) -1,3,4-oxadiazole and 2,5-di (1-naphthyl) -1,3,4-oxadiazole; 3- (4 -Biphenylyl) -4-phenyl-5- (4-t-butylphenyl) -1,2,4-triazole and other triazole derivatives; phenanthroline _Conductor, fullerene derivatives such as _{C 60} or _{C 70;} carbon nanotube (CNT), poly -p- phenylene vinylene-based polymer derivatives obtained by introducing cyano group into (CN-PPV) and the like. 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 derivatives include unsubstituted fullerene derivatives including C ₆₀ , C ₇₀ , C ₇₆ , C ₇₈ , C ₈₂ , C ₈₄ , C ₉₀ , and C ₉₄ ; [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 butyric acid dodecyl ester, [6 6 - diphenyl _{C 62-bis} (butyric acid methyl _{ester) ([6,6] -C 62 -bis} -PCB ), [6,6] - and substituted fullerene derivatives including phenyl _{C 71} butyric acid methyl ester _([6,6] -C 71 -PCBM) and the like.

  The ratio of the electron-accepting material in the composition is preferably 10 to 1000 parts by mass, and more preferably 50 to 500 parts by mass with respect to 100 parts by mass of the π-electron conjugated polymer of the present invention. .

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

  The mixing method of the π-electron conjugated polymer and the electron-accepting material of the present invention is not particularly limited, but after adding to the solvent in a desired ratio, one method such as heating, stirring, and ultrasonic irradiation is used. Alternatively, a method may be mentioned 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 organic thin film forming to use the solvent whose solubility in 20 degreeC is 1 mg / mL or more about each of the (pi) electron conjugated polymer and electron-accepting material of this invention. When the solubility is 1 mg / mL or less, 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 film 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 polymer and the electron-accepting material of the present invention. .

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

  In addition to the π-electron conjugated polymer and the electron-accepting material of the present invention, the composition solution may contain an additive having a boiling point higher than that of the solvent. In the process of forming an organic thin film by adding an additive, a fine and continuous phase separation structure of the π-electron conjugated polymer and the electron-accepting material of the present invention is formed, so that photoelectric conversion is excellent in photoelectric conversion efficiency. The active layer 23 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 is not particularly limited as long as the π-electron conjugated polymer and the electron-accepting material of the present invention do not precipitate and give a uniform solution. It is preferably 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 film thickness of the photoelectric conversion active layer 23 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.

  The method for coating the solution containing the π-electron conjugated polymer and the electron-accepting material of the present invention 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, dip coating method, spray coating method, ink jet 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 , Slit reverse coater method, micro gravure method, comma coater method, etc. can be adopted, and the coating method can be selected according to the coating film properties to be obtained, such as coating thickness control and orientation control. That's fine.

  The photoelectric conversion active layer 23 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. 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 26 on which the photoelectric conversion element 10 is formed may be any substrate that does not change when the electrode or the photoelectric conversion active layer 23 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. When a transparent substrate is used, the substrate-side electrode is preferably transparent or translucent. Although the film thickness of the board | substrate 26 is not specifically limited, Usually, it is the range of 1 micrometer-10 mm.

  In the photoelectric conversion element 10, it is preferable that one of the positive electrode 25 and the negative electrode 21 has light transmittance. The light transmittance of the electrode is not particularly limited as long as incident light reaches the photoelectric conversion active layer 23 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.

  Examples of the 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 A film made using a conductive material made of (IZO), gallium / zinc / oxide, aluminum / zinc / oxide, antimony / zinc / oxide, or an ultrathin film of gold, platinum, silver, or copper is used. Of these, ITO, FTO, IZO, and tin oxide are preferable. 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 electrically 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 does not have to be light transmissive, 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 One or more 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. It is done.

  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 of the present invention preferably uses a conductive material having a high work function on one side and a conductive material having a low work function on the other side. At this time, an electrode using a conductive material having a high work function is a positive electrode, and an electrode using a conductive material having a low work function is a negative electrode.

In the photoelectric conversion element 10, a hole transport layer 24 may be provided between the positive electrode 25 and the photoelectric conversion active layer 23 as necessary. The material for forming the hole transport layer 24 is not particularly limited as long as it has p-type semiconductor characteristics. However, the polythiophene polymer, the polyaniline polymer, the poly-p-phenylene vinylene polymer, and the polyfluorene polymer are not particularly limited. Conductive polymers such as polymers, low molecular organic compounds exhibiting p-type semiconductor properties such as phthalocyanine derivatives (such as H ₂ Pc, CuPc, and ZnPc), porphyrin derivatives, and metal oxides such as molybdenum oxide, zinc oxide, and vanadium oxide The product is preferably used. The thickness of the hole transport layer 24 is preferably 1 nm to 600 nm, and more preferably 20 nm to 300 nm.

  When the hole transport layer 24 is formed between the positive electrode 25 and the photoelectric conversion active layer 23, 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, 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, slit reverse coater method, micro gravure method, comma coater method, etc. Can be applied. 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. Further, the electron transport layer 22 described below can be similarly produced.

  In the photoelectric conversion element 10, an electron transport layer 22 may be provided between the negative electrode 21 and the photoelectric conversion active layer 23 as necessary. The material for forming the electron transport layer 22 is not particularly limited as long as it has n-type semiconductor characteristics, but the above-described electron-accepting 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 22 is preferably 1 nm to 600 nm, and more preferably 5 nm to 100 nm.

  In the photoelectric conversion element 10, a metal fluoride may be provided as a buffer layer that further facilitates charge transfer between the negative electrode 21 and the photoelectric conversion active layer 23. Examples of the metal fluoride include lithium fluoride, sodium fluoride, potassium fluoride, magnesium fluoride, calcium fluoride, cesium fluoride, and particularly preferably lithium fluoride and cesium fluoride. The buffer layer preferably has a thickness of 0.05 nm to 50 nm, more preferably 0.5 nm to 20 nm. The buffer layer may be used in combination with the electron transport layer 22 described above, and when used in combination, the buffer layer is preferably formed on the electrode side.

  The photoelectric conversion element thus formed may be used as a tandem photoelectric conversion element. The tandem photoelectric conversion element in the present invention can be produced by a method known in the literature, for example, a method described in Science, 2007, Vol. 317, pp222. Specifically, a structure in which a charge recombination layer is sandwiched between an active layer (1) produced using the organic semiconductor composition of the present invention and an active layer (2) capable of photoelectric conversion in a different absorption band. The connection order of the active layer (1) and the active layer (2) may be reversed.

  The charge recombination layer functions to recombine electrons generated in the active layer on the positive electrode side and holes generated in the active layer on the negative electrode side. Holes and electrons generated by charge separation in each active layer move toward the positive electrode and the negative electrode, respectively, by an internal electric field in the active layer. At this time, holes generated in the active layer on the positive electrode side and electrons generated in the active layer on the negative electrode side are taken out to the positive electrode and the negative electrode, respectively, and electrons generated on the active layer on the positive electrode side and the negative electrode side Recombination of holes generated in the active layer causes each active layer to function as a battery in which the active layers are electrically connected in series, increasing the open circuit voltage.

  The charge recombination layer preferably has optical transparency so that a plurality of 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 have to be a film. For example, the charge recombination layer is a metal cluster uniformly formed on the active layer. It does not matter. Therefore, the charge recombination layer includes 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 several nm or less. (Including alloys), ITO, IZO, AZO, GZO, FTO, highly light-transmitting metal oxide films and clusters such as titanium oxide and molybdenum oxide, polyethylene dioxythiophene with added polystyrene sulfonic acid (PSS) ( A conductive organic material film such as PEDOT) or a composite thereof 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, for example, Advanced Materials, 2006, Vol. 18, p. The sol-gel method described in 572 may be used. If it is a composite metal oxide such as ITO or IZO, the film may be formed by sputtering. These charge recombination layer formation methods and types may be appropriately selected in consideration of the non-destructive property to the active layer when forming the charge recombination layer, the formation method of the active layer to be laminated next, and the like.

  The photoelectric conversion element 10 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 devices (such as optical sensors, optical switches, 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. Moreover, the physical property measurement and purification of the π-electron conjugated polymer of the present invention produced in the above steps and the following steps were carried out as follows.

(Oxygen concentration measurement)
The oxygen concentration in the polymerization system was quantified by gas chromatography equipped with a thermal conductivity detector. The apparatus is GC-14B (manufactured by Shimadzu Corporation), the column is WG-100 (manufactured by GL Science), and the analysis conditions are vaporization chamber temperature 50 ° C., column temperature 50 ° C., He flow rate 40 mL / min, detector temperature 50 ° C, sample injection amount 0.2 μL. The average value of 3 times of measurement was defined as the oxygen concentration.

(Measurement of molecular weight)
A weight average molecular weight (Mw) is calculated | required by the polystyrene conversion value based on the measurement by a gel permeation chromatography (GPC). In the present invention, HLC-8020 (product number) manufactured by Tosoh Corporation was used as the GPC apparatus. When tetrahydrofuran (THF) was used as the eluent, ShoF KF804 was connected in series when the column was used as an eluent, and TSKgel Multipore HZ manufactured by Tosoh Corporation was connected in series when chloroform was used as the eluent. A thing was used.

(Identification of molecular structure, calculation of composition x and y)
The molecular structure of the π-electron conjugated polymer in the present invention was identified by ¹ H-NMR (nuclear magnetic resonance) measurement. Further, the composition represented by x and ^y, 13 C-NMR -Ar obtained from ¹ - and -Ar ² - are calculated from the specific characteristic integral value of carbon. The apparatus is a 600 MHz superconducting nuclear magnetic resonance apparatus Avance 600 (manufactured by Bruker), dissolved in deuterated chloroform at a concentration of 20 mg / mL, filtered through a 0.45 μm polytetrafluoroethylene (PTFE) filter, and 25 Measured at ° C. The number of integrations was 64 times for ¹ H-NMR and 113600 times for ¹³ C-NMR.

  The meaning of the abbreviations used herein is EtHex for 2-ethylhexyl group and Me for methyl group.

Monomers (Ar ¹ , Ar ² , M ^q1 -Ar ¹ -M ^q1 , M ^q2 -Ar ² -M ^q2 shown in formula (I)) used in the production of the π-electron conjugated polymer of the present invention are advanced materials. (Advanced Materials), 2009, Vol. 21, p. 209, Advanced Functional Materials, 2007, Vol. 17, p. It was synthesized according to the method described in 632 and the like.

(Example 1)
The π-electron conjugated polymer 1 was synthesized according to the following reaction formula.

  2,6-bis (trimethyltin) -4,8-bis (2-ethylhexyloxy) benzo [1,2-b: 4,5-b ′] dithiophene as a monomer constituting the π-electron conjugated polymer 1 (69.0 mg, 0.09 mmol) and 2-ethylhexyl-6-dibromo-3-fluorothieno [3,4-b] thiophene-2-carboxylate (56.6 mg, 0.12 mmol) as the polymerization solvent (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 nitrogen gas for 60 minutes. The oxygen concentration in the system determined using gas chromatography was 40 ppm. Heated at 110 ° C. for 10 hours under nitrogen atmosphere. 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 π-electron conjugated polymer 1 as a black purple solid. The obtained π-electron conjugated polymer 1 (42.9 mg) had a weight average molecular weight of 41,000 and a polydispersity of 1.6.

The spectrum data of ¹ H-NMR is as follows and supports the structure represented by the above reaction formula.
¹ H-NMR: δ = 7.90-7.00 (br), 4.70-4.00 (br), 2.40-1.20 (br), 0.90-0.60 (br)
¹³ C-NMR: δ = 11.2, 13.9 ppm (alkyl side chain terminal 6C; ¹⁾ ), 68.5 ppm (carbonyl carbon 1C of thienothiophene (Ar ² ); ²⁾ ), ¹⁾ The integrated value of ²⁾ when it is 20 is 2.86. The acceptor unit (Ar ² ) is thienothiophene 2.86, while the donor unit (Ar ¹ ) is benzodithiophene (20 / 2-2.86) /2=3.57. Therefore, donor unit (Ar ¹ ): acceptor unit (Ar ² ) = 55.5: 44.5 (mol%). From the above results, x = Ar ¹ −Ar ² = 11.0% and y = 89.0% shown in Formula (1) are obtained.

(Example 2)
A π-electron conjugated polymer 2 was synthesized in the same manner as in Example 1 except that ½ equivalent of triphenylphosphine of tetrakis (triphenylphosphine) palladium was added. The oxygen concentration in the polymerization system determined by gas chromatography was 14 ppm. The obtained π-electron conjugated polymer 2 (39.8 mg) had a weight average molecular weight of 40,400 and a polydispersity of 1.8.
¹³ C-NMR: δ = 11.2, 13.9 ppm (alkyl side chain terminal 6C; ³⁾ ), 68.5 ppm (carbonyl carbon 1C of thienothiophene (Ar ² ); ⁴⁾ ), ³⁾ The integration value of ⁴⁾ when set to 20 is 3.23. The acceptor unit (Ar ² ) is thienothiophene 3.23, while the donor unit (Ar ¹ ) is benzodithiophene (20 / 2-3.24) /2=3.38. Therefore, donor unit (Ar ¹ ): acceptor unit (Ar ² ) = 51.1: 48.9 (mol%). From the above results, x = Ar ¹ −Ar ² = 2.2% and y = 97.8% shown in Formula (1) are obtained.

(Example 3)
The amount of 2,6-bis (trimethyltin) -4,8-bis (2-ethylhexyloxy) benzo [1,2-b: 4,5-b ′] dithiophene was changed (84.3 mg, 0.11 mmol) The π-electron conjugated polymer 3 was synthesized by the same method as in Example 1 except that. The oxygen concentration in the polymerization system determined by gas chromatography was 35 ppm. The obtained π-electron conjugated polymer 3 (45.2 mg) had a weight average molecular weight of 69,000 and a polydispersity of 3.1.
¹³ C-NMR: δ = 11.2, 13.9 ppm (alkyl side chain terminal 6C; ⁵⁾ ), 68.5 ppm (carbonyl carbon 1C of thienothiophene (Ar ² ); ⁶⁾ ), ⁵⁾ The integrated value of ⁶⁾ when it is 20 is 2.66. The acceptor unit (Ar ² ) is thienothiophene 2.66, while the donor unit (Ar ¹ ) is benzodithiophene (20 / 2-2.66) /2=3.67. Therefore, donor unit (Ar ¹ ): acceptor unit (Ar ² ) = 58.0: 42.0 (mol%). From the above results, x = Ar ¹ −Ar ² = 16.0% and y = 84.0% shown in Formula (1) are obtained.

(Comparative Example 1)
A π-electron conjugated polymer 4 was synthesized by the same method as in Example 1 except that nitrogen bubbling was not performed before the start of polymerization. The oxygen concentration in the polymerization system determined by gas chromatography was 230 ppm. The obtained π-electron conjugated polymer 4 (56.2 mg) had a weight average molecular weight of 42,500 and a polydispersity of 1.7.
¹³ C-NMR: δ = 11.2, 13.9 ppm (alkyl side chain terminal 6C; ⁷⁾ ), 68.5 ppm (carbonyl carbon 1C of thienothiophene (Ar ² ); ⁸⁾ ), ⁷⁾ The integrated value of ⁸⁾ when set to 20 is 3.23. The acceptor unit (Ar ² ) is thienothiophene 1.86, while the donor unit (Ar ¹ ) is benzodithiophene (20 / 2-1.86) /2=4.07. Therefore, donor unit (Ar ¹ ): acceptor unit (Ar ² ) = 68.6: 31.4 (mol%). From the above results, x = Ar ¹ −Ar ² = 37.2% and y = 62.8% shown in Formula (1).

(Comparative Example 2)
A π-electron conjugated polymer 5 was synthesized in the same manner as in Example 3 except that nitrogen bubbling was not performed before the start of polymerization. The oxygen concentration in the polymerization system determined by gas chromatography was 220 ppm. The obtained π-electron conjugated polymer 5 (49.7 mg) had a weight average molecular weight of 60,800 and a polydispersity of 2.5.
¹³ C-NMR: δ = 11.2, 13.9 ppm (alkyl side chain terminal 6C; ⁹⁾ ), 68.5 ppm (carbonyl carbon 1C of thienothiophene (Ar ² ); ¹⁰⁾ ), ⁹⁾ The integrated value of ¹⁰⁾ when it is 20 is 1.54. The acceptor unit (Ar ² ) is thienothiophene 1.54, while the donor unit (Ar ¹ ) is benzodithiophene (20 / 2−1.54) /2=4.23. Therefore, donor unit (Ar ¹ ): acceptor unit (Ar ² ) = 73.3: 26.7 (mol%). From the above results, x = Ar ¹ −Ar ² = 46.6% and y = 53.4% shown in Formula (1) are obtained.

(Photoelectric conversion characteristics evaluation)
3.0 mg of the π-electron conjugated polymer of the present invention obtained in Examples 1 to 3 and Comparative Examples 1 and 2 and 6.0 mg of PC ₇₁ BM (E110 manufactured by Frontier Carbon Co.) as an electron-accepting material and a solvent. The mixture was mixed with 0.25 mL of chlorobenzene containing 2.5 vol% 1,8-diiodooctane at 100 ° C. over 6 hours. Then cooled to room temperature 20 ° C., to produce a composition solution comprising a π-electron conjugated polymer and the _PC 71 BM of the present invention was filtered through a PTFE filter having a pore size of 1.0 .mu.m. A composition solution containing PC ₇₁ BM was produced by the same method for the π-electron conjugated polymer obtained in Comparative Example 1.

  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 Heraeus: CLEVIOS P VP AI4083) serving as a hole transport layer was formed on the substrate to a thickness of 30 nm by a spin coating method, and dried by heating at 140 ° C. for 20 minutes using a hot plate. Next, the said composition solution was apply | coated with the spin coat method, and it vacuum-dried for 3 hours, and formed the photoelectric converting layer (film thickness of about 90 nm) which is a thin film. Next, lithium fluoride was vapor-deposited with a film thickness of 0.5 nm by a vacuum vapor deposition method, and then Al was vapor-deposited with a film thickness of 100 nm. Thereby, each photoelectric conversion element containing each polymer obtained in Example 1 and Comparative Example 1 was produced. The light receiving surface shape of the photoelectric conversion element was a regular square of 5 × 5 mm.

The photoelectric conversion efficiency was measured under the following measurement conditions using a solar simulator and a 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 photoelectric conversion efficiencies of the π-electron conjugated polymers of Examples and Comparative Examples and photoelectric conversion elements prepared using the same are summarized. In the table below, D represents the donor unit (Ar ¹ ), A represents the acceptor unit (Ar ² ), and D—A chain represents the donor-acceptor chain (Ar ¹ -Ar ² ).

  As can be seen from the comparison between the photoelectric conversion element using the π-electron conjugated polymer of the present invention shown in Table 1 and the photoelectric conversion element using the π-electron conjugated polymer shown in the comparative example from Table 1, By using a π-electron conjugated polymer, it was possible to obtain a photoelectric conversion element having high photoelectric conversion efficiency when compared with the same molecular weight.

  The π-electron conjugated polymer of the present invention can be used as a photoelectric conversion layer of a photoelectric conversion element, and the photoelectric conversion element comprising the polymer has applications as various photosensors including solar cells.

  10 is a photoelectric conversion element, 21 is a negative electrode, 22 is an electron transport layer, 23 is a photoelectric conversion active layer, 24 is a hole transport layer, 25 is a positive electrode, and 26 is a substrate.

Claims (10)

The following chemical formula (1)

(In the formula, -Ar ¹ -has a substituent, and is a donor group composed of a condensed heterocyclic skeleton in which at least three rings including a thiophene ring are condensed, and -Ar ² -has a substituent. An acceptor group having a thienothiophene skeleton that may be substituted or a nitrogen-containing fused heterocyclic skeleton that may have a substituent, wherein x: y is from 1:99 to 20:80, and r is random A donor-acceptor type π-electron conjugated polymer,   The π-electron conjugated polymer according to claim 1, wherein the weight average molecular weight is 30,000 to 100,000 g / mol. The —Ar ¹ — represents the following chemical formula (2)

(Wherein R ¹ is an optionally substituted alkyl group having 1 to 18 carbon atoms, an alkoxy group, an aryl group, a heteroaryl group, an alkylcarbonyl group, or an alkyloxycarbonyl group). The π-electron conjugated polymer according to claim 1 or 2, characterized in that The —Ar ² — represents the following chemical formula (3)

(Wherein R ² is an optionally substituted alkyl group having 1 to 18 carbon atoms, an alkoxy group, an aryl group, a heteroaryl group, an alkylcarbonyl group or an alkyloxycarbonyl group, and X ¹ is hydrogen. The π-electron conjugated polymer according to claim 1, wherein the π-electron conjugated polymer is an atom or a halogen atom. The —Ar ¹ — represents the following chemical formula (4)

The —Ar ² — represents the following chemical formula (5)

The π-electron conjugated polymer according to any one of claims 1 to 4, wherein   An organic semiconductor composition comprising the π-electron conjugated polymer according to claim 1.   An organic semiconductor device comprising the π-electron conjugated polymer according to claim 1.   It is a photoelectric conversion element, The organic-semiconductor device of Claim 7 characterized by the above-mentioned.   A photoelectric conversion element comprising a layer containing the π-electron conjugated polymer according to claim 1 and an electron-accepting material.   A tandem photoelectric conversion element comprising the photoelectric conversion element according to claim 8.

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