JP2015218221A - Copolymer, photoelectric conversion element, solar battery and solar battery module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a p-type semiconductor compound which enables absorption of light on the longer-wavelength side and is suitable for photoelectric conversion elements.SOLUTION: A copolymer having a structural unit of formula (1) is provided. In formula (1), Rto Rare independently a hydrogen atom or a monovalent organic group; Rand R, Rand R, and/or Rand Rmay bind to each other to form a ring; X is a divalent atom or a divalent group; a ring Y is an aliphatic hydrocarbon ring optionally having a substituent, an aromatic hydrocarbon ring optionally having a substituent, an aliphatic heterocyclic ring optionally having a substituent or an aromatic heterocyclic ring optionally having a substituent.

Description

  The present invention relates to a copolymer, a photoelectric conversion element, a solar cell, and a solar cell module.

  In recent years, electronic devices using organic semiconductors, especially organic thin-film solar cells (OPV) and organic electroluminescent elements (OLEDs) have been actively developed. Since a device using an organic semiconductor can maintain flexibility by using a flexible base material as a base material, it has a feature that it can be installed in various situations.

  In general, π-conjugated polymer compounds have been studied as organic semiconductors used in organic thin-film solar cells, and π-conjugated polymer compounds include copolymers of specific donor monomers and specific acceptor monomers. (Hereinafter sometimes referred to as a copolymer) has been studied. For example, Non-Patent Document 1 proposes a copolymer that is a p-type semiconductor compound having an isothianaphthene skeleton and a fluorene skeleton. Non-Patent Document 2 proposes a copolymer containing an isothianaphthene skeleton and a benzothiadiazole skeleton.

Macromolecular Rapid Communications (2007), 28 (17), 1786-1791. Journal of Physical Chemistry C (2009), 113 (52), 21928-21936

In order to improve the conversion efficiency of the organic thin film solar cell, a p-type semiconductor compound capable of absorbing light on a longer wavelength side is required. In particular, in the case of a solar cell having a tandem structure, by stacking materials having different absorption wavelengths, light of a wider range can be absorbed, and p-type capable of absorbing light on a long wavelength side. Semiconductor compounds are desired.
However, the absorption wavelength region of the p-type semiconductor compound described in Non-Patent Document 1 is about 350 to 800 nm, and when the p-type semiconductor compound described in Non-Patent Document 2 is used for the active layer. The absorption wavelength region is about 300 nm to 820 nm, which is not sufficient for practical use.
An object of this invention is to provide the p-type semiconductor compound suitable for the photoelectric conversion element which solves the said problem and can absorb the light of a longer wavelength side.

As a result of intensive studies to solve the above problems, the present inventors have solved the above problems by using a copolymer having an isothianaphthene skeleton and a specific skeleton in the active layer of a photoelectric conversion element, and the present invention. It came to achieve. That is, the gist of the present invention is as follows.
[1] A copolymer having a structural unit represented by the following formula (1).

(In formula (1), R ^{1 to} R ⁶ are each independently a hydrogen atom or a monovalent organic group, or R ¹ and R ² , R ³ and R ⁴ , R ⁵ and R ⁶ are Each may be bonded to each other to form a ring, X represents a divalent atom or a divalent group, and ring Y has an aliphatic hydrocarbon ring which may have a substituent, or a substituent. An aromatic hydrocarbon ring which may be substituted, an aliphatic heterocyclic ring which may have a substituent, or an aromatic heterocyclic ring which may have a substituent.

[2] In the formula (1), X represents O, S, Se, N (R ⁷ ), C (R ⁸ ) (R ⁹ ), or Si (R ¹⁰ ) (R ¹¹ ), and R ⁷ to The copolymer according to [1], wherein R ¹¹ is a hydrogen atom or a monovalent organic group.
[3] In the formula (1), R ^{1 to} R ⁶ are each independently a hydrogen atom or an aliphatic hydrocarbon group which may have a substituent, according to [1] or [2]. Copolymer.
[4] A photoelectric conversion element having at least a pair of electrodes and an active layer between the pair of electrodes on a substrate, wherein the active layer is any one of [1] to [3]. The photoelectric conversion element characterized by containing the copolymer of these.
[5] A solar cell having the photoelectric conversion element according to [4].
[6] A solar cell module having the solar cell according to [5].

  According to the present invention, it is possible to provide a p-type semiconductor compound suitable for a photoelectric conversion element that can absorb light on a longer wavelength side.

It is sectional drawing which shows typically the structure of the photoelectric conversion element as one Embodiment of this invention. It is sectional drawing which shows typically the structure of the solar cell as one Embodiment of this invention. It is sectional drawing which shows typically the structure of the solar cell module as one Embodiment of this invention. It is sectional drawing which shows typically the structure of the tandem structure type photoelectric conversion element as one Embodiment of this invention. 2 is an absorption spectrum of copolymer 1 obtained in Example 1.

Hereinafter, embodiments of the present invention will be described in detail. The description of the constituent requirements described below is an example (representative example) of an embodiment of the present invention, and the present invention is not specified in these contents unless it exceeds the gist.
<1. Copolymer according to the present invention>
The copolymer according to the present invention has a structural unit represented by the following formula (1).

In formula (1), R ^{1 to} R ⁶ are each independently a group selected from a hydrogen atom and a monovalent organic group, or R ¹ and R ² , R ³ and R ⁴ , and R ³ and R ⁴ may combine with each other to form a ring.

  The monovalent organic group is not particularly limited, but includes a halogen atom, an aliphatic hydrocarbon group which may have a substituent, an aromatic hydrocarbon group which may have a substituent, and a substituent. An aliphatic heterocyclic group which may have, an aromatic heterocyclic group which may have a substituent, a hydroxyl group, an alkoxy group which may have a substituent, and a substituent which may have An alkylthio group, an aryloxy group which may have a substituent, an arylthio group which may have a substituent, a nitro group, an amino group which may have a substituent, and a substituent; And a silyl group which may have a substituent, a thiocarbonyl group which may have a substituent, a sulfonyl group which may have a substituent, or a cyano group.

  Although there is no special restriction | limiting in a halogen atom, A fluorine atom, a chlorine atom, a bromine atom, and an iodine atom are mentioned, Among these, a fluorine atom is preferable.

  Examples of the aliphatic hydrocarbon group include an alkyl group, an alkenyl group, and an alkynyl group. The aliphatic hydrocarbon group may be a linear aliphatic hydrocarbon group, a branched aliphatic hydrocarbon group, or an alicyclic aliphatic hydrocarbon group.

  The aliphatic hydrocarbon group is not particularly limited, but an aliphatic hydrocarbon group having usually 1 or more carbon atoms and 20 or less carbon atoms is preferable.

  Examples of the alkyl group include a straight chain alkyl group such as a methyl group, an n-butyl group, an n-hexyl group, an n-octyl group, an n-decyl group, and an n-dodecyl group; 2-methylpropyl group, 2-methylbutyl Group, 2-ethylhexyl group, 2,5-dimethylhexyl group, 2-methyldodecyl group, 2-propylpentyl group, 2-hexyldecyl group and other branched alkyl groups; or cyclopropyl group, cyclopentyl group, cyclo Examples thereof include a cycloalkyl group such as a hexyl group, a cyclooctyl group, a cyclodecyl group, and a cyclolauryl group.

  Examples of alkenyl groups include linear alkenyl groups such as ethenyl group, 2-butenyl group, 5-hexenyl group, 7-octenyl group, 9-decenyl group, 11-dodecenyl group; 2-methyl-2-propenyl group, 3 A branched alkenyl group such as a methyl-3-butenyl group and a 4-methyl-2-hexenyl group; or a 2-cyclopropenyl group, a 2-cyclobutenyl group, a 2-cyclopentenyl group, a 3-cyclopentenyl group, a 2-cyclohexenyl group, Examples include cycloalkenyl groups such as 2-cycloheptenyl group and 2-cyclooctenyl group.

Examples of the alkynyl group include linear alkenyl groups such as ethynyl group, 2-butynyl group, 5-hexynyl group, 7-octynyl group, 9-decynyl group, 11-dodecynyl group; 1-methyl-2-propenyl group, 2- Examples thereof include branched alkenyl groups such as methyl-3-butenyl group and 4-methyl-2-hexenyl group; and cycloalkynyl groups such as 2-cyclooctynyl group and 3-cyclooctynyl group.

  Among the above aliphatic hydrocarbon groups, an aliphatic hydrocarbon group having 4 or more carbon atoms is preferable, and an aliphatic hydrocarbon group having 6 or more carbon atoms is particularly preferable in order to improve solubility in an organic solvent. On the other hand, from the viewpoint of reducing steric hindrance, an aliphatic hydrocarbon group having 16 or less carbon atoms is preferable, and an aliphatic hydrocarbon group having 12 or less carbon atoms is particularly preferable. Particularly preferred aliphatic hydrocarbon groups include n-octyl groups.

  The aromatic hydrocarbon group is not particularly limited, but is preferably an aromatic hydrocarbon having 6 to 30 carbon atoms. Specifically, monocyclic aromatic hydrocarbon groups such as phenyl groups; naphthyl groups, indanyl groups, indenyl groups, phenanthryl groups, fluorenyl groups, anthryl groups, anthracenyl groups, azulenyl groups, pyrenyl groups, perylenyl groups, etc. Examples thereof include a condensed polycyclic aromatic hydrocarbon group; or a polycyclic aromatic hydrocarbon group such as a biphenyl group and a terphenyl group.

  The aliphatic heterocyclic group is not particularly limited, but is preferably an aliphatic heterocyclic group having 3 to 30 carbon atoms. Specifically, aliphatic heterocyclic groups containing nitrogen such as pyrrolidyl group, piperidyl group, piperazyl group; heterocyclic groups containing oxygen such as tetrahydrofuranyl group, dioxanyl group; containing nitrogen and oxygen such as morpholinyl group An aliphatic heterocycle containing nitrogen and sulfur such as a thiomorpholinyl group.

  The aromatic heterocyclic group is not particularly limited, but is preferably an aromatic heterocyclic group having 2 to 20 carbon atoms. Specifically, monocyclic aromatic heterocyclic groups such as thienyl group, furanyl group, pyridyl group, pyrimidyl group, thiazolyl group, oxazolyl group, triazolyl group; or benzothiophenyl group, benzofuranyl group, benzothiazolyl group, benzooxa Examples thereof include condensed polycyclic aromatic heterocyclic groups such as zolyl group, benzotriazolyl group, and thiadiazolopyridine. Of these, a thienyl group, a pyridyl group, a pyrimidyl group, a thiazolyl group, or an oxazolyl group is preferable.

  The alkoxy group is not particularly limited, but is preferably an alkoxy group having 1 to 20 carbon atoms. Specific examples include methoxy group, ethoxy group, n-propoxy group, i-propoxy group, n-butoxy group, i-butoxy group, n-heptoxy group, i-heptoxy group and the like.

  The alkylthio group is not particularly limited, but is preferably an alkylthio group having 1 to 20 carbon atoms. Specific examples include a methylthio group, an ethylthio group, an n-propylthio group, an i-propylthio group, an n-butylthio group, an i-butylthio group, an n-hexylthio group, and an i-hexylthio group.

  The aryloxy group is not particularly limited, but is preferably an aryloxy group having 6 to 20 carbon atoms. Specific examples include a phenyloxy group.

  The arylthio group is not particularly limited, but is preferably an arylthio group having 6 to 20 carbon atoms. Specific examples include a phenylthio group.

The carbonyl group is not particularly limited, but is a formyl group; an alkylcarbonyl group having 2 to 20 carbon atoms such as an acetyl group, a bitylyl group, or a lauroyl group; a haloalkylcarbonyl group having 2 to 20 carbon atoms such as a trifluoroacetyl group; An alkoxycarbonyl group having 2 to 20 carbon atoms such as a methoxycarbonyl group and an ethoxycarbonyl group; a carbamoyl group having 1 to 20 carbon atoms such as an ethylcarbamoyl group and a dimethylcarbamoyl group; an arylcarbonyl having 7 to 30 carbon atoms such as a phenylcarbonyl group Group; aryloxycarbonyl groups having 7 to 30 carbon atoms such as phenoxycarbonyl group.

  The thiocarbonyl group having a substituent is not particularly limited. For example, a thioaldehyde group; an alkylthiocarbonyl group having 1 to 20 carbon atoms such as a thioacetyl group; a haloalkylthio having 1 to 20 carbon atoms such as a trifluorothioacetyl group. Carbonyl group; alkoxythiocarbonyl group having 1 to 20 carbon atoms such as methoxythiocarbonyl group; arylthiocarbonyl group having 7 to 30 carbon atoms such as phenylthiocarbonyl group; aryl having 7 to 30 carbon atoms such as phenoxythiocarbonyl group An oxythiocarbonyl group is mentioned.

The sulfonyl group is not particularly limited, but for example, an alkylsulfonyl group having 1 to 20 carbon atoms such as a mesyl group, a butanesulfonyl group, an octanesulfonyl group, or a dodecanesulfonyl group; and having 1 to 20 carbon atoms such as a trifluoromethanesulfonyl group. Haloalkylsulfonyl group; C2-C20 alkoxysulfonyl group such as methoxysulfonyl group; C6-C30 arylsulfonyl group such as phenylsulfonyl group; C6-C30 haloarylsulfonyl such as monofluorophenylsulfonyl group Group; C6-C30 aryloxy sulfonyl groups, such as a phenoxy sulfonyl group, are mentioned.

In addition, the above group may further have one or more substituents. The substituent that the above group may have is not particularly limited, and examples thereof include the groups described above for R ^{1 to} R ⁶ . Specifically, halogen atom, aliphatic hydrocarbon group, aromatic hydrocarbon group, aliphatic heterocyclic group, aromatic heterocyclic group, hydroxyl group, alkoxy group, alkylthio group, aryloxy group, arylthio group, nitro group, An amino group, a silyl group, a carbonyl group, a thiocarbonyl group, a sulfonyl group, a cyano group, etc. are mentioned. Specific examples of each group include the groups mentioned above.

When R ¹ and R ² , R ³ and R ⁴ , R ⁵ and R ⁶ are bonded to each other to form a ring, the ring is an aliphatic hydrocarbon ring which may have a substituent, a substituent. Examples thereof include an aromatic hydrocarbon ring which may have, an aliphatic heterocyclic ring which may have a substituent, and an aromatic heterocyclic ring which may have a substituent.

  The aliphatic hydrocarbon ring is not particularly limited, and examples thereof include a cycloalkane ring such as a cyclopentane ring or a cyclohexane ring; and a condensed aliphatic hydrocarbon ring such as a decalin ring, a cyclopentadiene ring, or a dicyclopentadiene ring. Of these, a cycloalkane ring such as cyclohexane is preferable.

  The aromatic hydrocarbon ring is not particularly limited, but a monocyclic aromatic hydrocarbon ring such as a benzene ring; or a condensed polycyclic ring such as a naphthalene ring, an indane ring, an indene ring, a fluorene ring, an anthracene ring, or an azulene ring And an aromatic hydrocarbon ring. Of these, monocyclic aromatic hydrocarbon rings such as benzene are preferable.

  The aliphatic heterocyclic ring is not particularly limited, but is an aliphatic heterocyclic ring containing nitrogen such as a pyrrolidine ring, piperidine ring or piperazine ring; an aliphatic heterocyclic ring containing oxygen such as tetrahydrofuran ring or dioxane ring; morpholine ring An aliphatic heterocycle containing nitrogen and oxygen such as; or an aliphatic heterocycle containing nitrogen and sulfur such as a thiomorpholine ring. Among them, an aliphatic heterocyclic ring containing nitrogen such as pyrrolidine ring, piperidine ring or piperazine ring; an aliphatic heterocyclic ring containing nitrogen and oxygen such as morpholine ring; or a fat containing nitrogen and sulfur such as thiomorpholine ring An aromatic heterocyclic ring is preferable, and an aliphatic heterocyclic ring containing nitrogen such as a pyrrolidine ring or a piperidine ring is more preferable.

The aromatic heterocycle is not particularly limited, but a monocyclic aromatic heterocycle such as a thiophene ring, a furan ring, a pyrrole ring, a thiazole ring, a thiadiazole ring, a pyridine ring, a pyrimidine ring, a dioxopyrrole ring; or an indole Examples thereof include condensed polycyclic aromatic heterocycles such as rings. Of these, monocyclic aromatic heterocycles containing nitrogen such as thiophene ring, pyrrole ring, thiazole ring, thiadiazole ring, pyrimidine ring, dioxopyrrole ring and the like are preferable.

The substituent that these rings may have is not particularly limited, and examples thereof include the same groups as the substituents that the above-described groups R ^{1 to} R ⁶ may have. Specifically, halogen atom, aliphatic hydrocarbon group, aromatic hydrocarbon group, aliphatic heterocyclic group, aromatic heterocyclic group, hydroxyl group, alkoxy group, alkylthio group, aryloxy group, arylthio group, nitro group, An amino group, a silyl group, a carbonyl group, a thiocarbonyl group, a sulfonyl group, or a cyano group can be mentioned.

Among these, in order to maintain the planarity of the polymer, R ^{1 to} R ⁶ are each independently a hydrogen atom, an alkyl group having 6 to 12 carbon atoms, an alkoxy group having 6 to 12 carbon atoms, or 6 carbon atoms. It is preferably an alkylthio group having 12 or less, an aromatic hydrocarbon group having 6 to 12 carbon atoms, an aryloxy group having 12 to 18 carbon atoms, or an arylthio group having 12 to 18 carbon atoms, An alkyl group having 6 to 12 carbon atoms is particularly preferable.

In formula (1), X represents a divalent atom or a divalent group. The divalent atom is not particularly limited, and examples thereof include O, S, or Se. The divalent group is not particularly limited, and examples thereof include N (R ⁷ ), C (R ⁸ ) (R ⁹ ), and Si (R ¹⁰ ) (R ¹¹ ). R ^{7 to} R ¹¹ each independently represent a hydrogen atom or a monovalent organic group, and the monovalent organic group is not particularly limited, but the monovalent examples described for R ^{1 to} R ⁶ The same group as an organic group is mentioned. Among these, in order to improve semiconductor characteristics, X is preferably S or Se, and particularly preferably S.

  In formula (1), ring Y is an aliphatic hydrocarbon ring which may have a substituent, an aromatic hydrocarbon ring which may have a substituent, and an aliphatic which may have a substituent. It is an aromatic heterocycle which may have an aromatic heterocycle or a substituent.

The aliphatic hydrocarbon ring, aromatic hydrocarbon ring, aliphatic heterocyclic ring, and aromatic hydrocarbon ring are not particularly limited. Specifically, the above-described R ¹ and R ² , R ³ and R ⁴ , Examples thereof include the same ring as the ring formed by combining R ⁵ and R ⁶ with each other.

  The substituents that these rings may have are not particularly limited, but include a halogen atom, an aliphatic hydrocarbon group, an aromatic hydrocarbon group, an aliphatic heterocyclic group, an aromatic hydrocarbon group, Examples include a hydroxyl group, an alkoxy group, an alkylthio group, an aryloxy group, an arylthio group, a nitro group, an amino group, a silyl group, a carbonyl group, a thiocarbonyl group, a sulfonyl group, or a cyano group.

  Among the above, ring Y is preferably an aromatic hydrocarbon ring which may have a substituent or an aromatic heterocyclic ring which may have a substituent, and has solubility in various organic solvents. From the viewpoint of being high, it is preferably an aromatic heterocyclic ring which may have a substituent.

  Among the compounds represented by the above formula (1), a compound represented by the following formula (2) is preferable in that a longer wavelength can be expected.

In the formula ^(2), R 1 to R ⁶ and X are each the same meanings as ^R 1 to R ⁶ and X in the formula (1).

In Formula (2), R ⁷ includes a hydrogen atom or a monovalent organic group. The monovalent organic group is not particularly limited, and specific examples thereof include the same groups as the monovalent organic groups described in R ^{1 to} R ⁶ in formula (1), and preferred groups are also the same. It is.

  Preferred specific examples of the copolymer according to the present invention are shown below. However, the copolymer according to the present invention is not limited to the following examples. Note that n represents an integer of 1 or more.

  The copolymer according to the present invention may contain a structural unit other than the structural unit represented by the above formula (1) as long as the effects of the present invention are not impaired. For example, there is no particular limitation other than the structural unit represented by the above formula (1), but a dithienooxane structural unit, a dithienosilole structural unit, a dithienopyrrole structural unit, a cyclopentadithiophene structural unit, a dithienogermol structural unit, a benzoic acid A dithiophene structural unit, a diketopyrrolopyrrole structural unit, a thienothiophene structural unit, a benzothiadiazole structural unit, a benzotriazole structural unit, a benzoxazole structural unit, and the like may be included.

  The proportion of the structural unit represented by the above formula (1) in the structural unit constituting the copolymer according to the present invention is not particularly limited, but is usually 2 mol% or more, preferably 10 mol% or more, more preferably Is at least 25 mol%, more preferably at least 70 mol%, and the copolymer according to the present invention comprises only the structural unit represented by the above formula (1) and / or the structural unit represented by the formula (2). Are particularly preferred.

The polystyrene-reduced weight average molecular weight (Mw) of the copolymer according to the present invention is not particularly limited, but is usually 2.0 × 10 ³ or more, preferably 2.0 × 10 ⁴ or more, more preferably 4
. It is 0 × 10 ⁴ or more, more preferably 5.0 × 10 ⁴ or more, still more preferably 7.0 × 10 ⁴ or more, and particularly preferably 1.0 × 10 ⁵ or more. On the other hand, it is preferably 1.0 × 10 ⁷ or less, more preferably 1.0 × 10 ⁶ or less, and particularly preferably 5.0 × 10 ⁵ or less. The weight average molecular weight is preferably in this range from the viewpoint of increasing the light absorption wavelength, from the viewpoint of realizing high absorbance, from the viewpoint of realizing high carrier movement, and from the viewpoint of solubility in an organic solvent.

The polystyrene-reduced number average molecular weight (Mn) of the copolymer according to the present invention is usually 5.0 × 10 ³ or more, preferably 1.0 × 10 ⁴ or more, more preferably 2.0 × 10 ⁴ or more, and still more preferably. It is 2.5 × 10 ⁴ or more, particularly preferably 3.0 × 10 ⁴ or more. On the other hand, it is preferably 1.0 × 10 ⁷ or less, more preferably 1.0 × 10 ⁶ or less, further preferably 5.0 × 10 ⁵ or less, even more preferably 2.0 × 10 ⁵ or less, and particularly preferably 1 0.0 × 10 ⁵ or less. The number average molecular weight is preferably in this range from the viewpoint of increasing the light absorption wavelength, from the viewpoint of realizing high absorbance, from the viewpoint of realizing high carrier movement, and from the viewpoint of solubility in an organic solvent.

  The molecular weight distribution (PDI, (weight average molecular weight / number average molecular weight (Mw / Mn))) of the copolymer according to the present invention is usually 1.0 or more, preferably 1.1 or more, more preferably 1.2 or more, Preferably it is 1.3 or more. On the other hand, it is preferably 20.0 or less, more preferably 15.0 or less, and still more preferably 10.0 or less. The molecular weight distribution is preferably in this range in that the solubility of the copolymer can be in a range suitable for coating.

  The polystyrene-reduced weight average molecular weight, number average molecular weight, and molecular weight distribution of the copolymer according to the present invention can be determined by gel permeation chromatography (GPC). Specifically, two Polymer Laboratories GPC columns (PLgel MIXED-B 10 μm inner diameter 7.5 mm, length 30 cm) are connected in series as a column, LC-10AT (manufactured by Shimadzu Corporation) as a pump, and an oven It can be measured by using CTO-10A (manufactured by Shimadzu Corp.), a differential refractive index detector (manufactured by Shimadzu Corp .: RID-10A), and a UV-vis detector (manufactured by Shimadzu Corp .: SPD-10A). As a measuring method, a copolymer (1 mg) to be measured is dissolved in chloroform (200 mg), and 1 μL of the obtained solution is injected into a column. Measurement is performed at a flow rate of 1.0 mL / min using chloroform as the mobile phase. For the analysis, LC-Solution (manufactured by Shimadzu Corporation) is used.

  The solubility of the copolymer according to the present invention is not particularly limited, but preferably the solubility in chlorobenzene at 25 ° C. is usually 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 1% by mass or more. On the other hand, it is usually 30% by mass or less, preferably 20% by mass. High solubility is preferable because a thicker film can be formed by coating.

  The copolymer according to the present invention preferably has an appropriate interaction between molecules. In the present specification, the interaction between molecules means that the distance between polymer chains is shortened by an interaction such as π-π stacking between molecules. The stronger the interaction, the higher the mobility and / or crystallinity, and the more suitable the semiconductor material is. That is, in a copolymer that interacts between molecules, electron transfer between molecules is likely to occur. For example, when the copolymer according to the present invention is used in an active layer in a photoelectric conversion element, a p-type semiconductor compound in the active layer is used. It is considered that holes generated at the interface between the n-type semiconductor compound and the n-type semiconductor compound can be efficiently transported to the electrode (anode).

  An example of a crystallinity measuring method is an X-ray diffraction method (XRD). In this specification, having crystallinity means that an X-ray diffraction spectrum obtained by XRD measurement has a diffraction peak. Having crystallinity is considered to mean that it has a laminated structure in which molecules are arranged, and is preferable in that the active layer described later tends to be thickened. XRD measurement can be performed based on a method described in a known document (X-ray crystal analysis guide (applied physics selection book 4)).

The hole mobility of the copolymer according to the present invention (sometimes referred to as hole mobility) is usually 1.0 × 10 ⁻⁷ cm ² / Vs or more, preferably 1.0 × 10 ⁻⁶ cm ² / Vs or more. More preferably, it is 1.0 × 10 ⁻⁵ cm ² / Vs or more, and particularly preferably 1.0 × 10 ⁻⁴ cm ² / Vs or more. On the other hand, the hole mobility of the copolymer according to the present invention is usually 1.0 × 10 ⁴ cm ² / Vs or less, preferably 1.0 × 10 ³ cm ² / Vs or less, and more preferably 1.0 × 10 6. ² cm ² / Vs or less, particularly preferably 1.0 × 10 cm ² / Vs or less. When the hole mobility is in this range, the copolymer according to the present invention is suitably used as a semiconductor material. Further, in order to obtain high conversion efficiency in the photoelectric conversion element, it is important to balance the mobility of the n-type semiconductor compound and the mobility of the p-type semiconductor compound. When the copolymer according to the present invention is used as a p-type semiconductor compound in a photoelectric conversion element, from the viewpoint of bringing the hole mobility of the copolymer according to the present invention close to the electron mobility of the n-type semiconductor compound, the copolymer according to the present invention is positive. The hole mobility is preferably within this range. As a method for measuring the hole mobility, there is an FET method. The FET method can be performed by a method described in a known document (Japanese Patent Laid-Open No. 2010-045186).

  On the other hand, the copolymer according to the present invention preferably has high storage stability in a solution state. High storage stability means that it is difficult to aggregate when made into a solution. More specifically, 2 mg of the copolymer according to the present invention was placed in a 2 mL screw vial, dissolved in o-xylene to a concentration of 1.5% by mass, and then cooled to room temperature. Then, it is preferable not to gel for 5 minutes or more, and it is more preferable not to gel for 1 hour or more.

  The impurities in the copolymer according to the present invention are preferably as few as possible. In particular, when a copolymer having a structural unit represented by the formula (1) is synthesized, when a transition metal catalyst such as palladium or copper is used, these may remain in the copolymer. If these metal catalysts remain in the copolymer, exciton traps due to the heavy atom effect of the transition metal occur and charge transfer is inhibited. As a result, when the copolymer according to the present invention is used in a photoelectric conversion element, There is a risk of reducing the conversion efficiency. Therefore, the concentration of the transition metal catalyst is usually 1000 ppm or less, preferably 500 pm or less, more preferably 100 ppm or less per 1 g of copolymer. On the other hand, it is usually larger than 0 ppm and may be 1 ppm or more, or 3 ppm or more.

  The impurities contained in the copolymer can be measured by, for example, ICP mass spectrometry. ICP mass spectrometry can be carried out by a method described in a known document (“Plasma ion source mass spectrometry” (Academic Publishing Center)). Specifically, about palladium atom and copper atom, after wet-decomposing the sample, Pd and Sn in the decomposition solution are analyzed by a calibration curve method using an ICP mass spectrometer (ICP mass spectrometer 7500ce type manufactured by Agilent Technologies). It can be quantified.

  As shown in the formula (1), the copolymer according to the present invention is considered to have high linearity and planarity in the main chain direction of the polymer because five-membered rings are arranged in the main chain. When the linearity of the polymer is high, the π conjugation becomes linearly long, so that it is possible to strongly absorb long wavelength light. In addition, when the planarity of the polymer is high, the polymers are easily π-stacked with each other, and the durability is improved and the mobility in the π-stack direction is improved. In addition, since the polymer has high planarity, HOMO and LUMO are distributed throughout the polymer, thereby improving the mobility in the polymer, and no matter where the n-type semiconductor comes into contact with the polymer, LUMO can overlap with LUMO of the polymer, and charge separation is likely to occur.

<2. Method for producing copolymer according to the present invention>
The method for producing the copolymer of the present invention is not particularly limited, and for example, it can be produced by a known method using isothianaphthene derivatives and thiophene derivatives. A preferred method for producing a copolymer according to the present invention comprises an isothianaphthene derivative compound represented by the following general formula (3) and a 5-membered ring derivative compound represented by the following general formula (4), if necessary. The method of superposing | polymerizing in presence of a suitable catalyst is mentioned.

In the above formula ^(3), R 1 to R ⁶ have the same meanings as ^R 1 to R ⁶ of formula (1).

A in the above formula (3) and Q in the above formula (4) can be appropriately selected according to the kind of the polymerization reaction, and there is no particular limitation, but each independently represents a halogen atom, an alkylstannyl group, Alkylsulfo group, arylsulfo group, arylalkylsulfo group, boric acid ester residue, sulfonium methyl group, phosphonium methyl group, phosphonate methyl group, monohalogenated methyl group, boric acid residue (-B (OH) ₂ ), Represents a formyl group, an alkenyl group or an alkynyl group.

  The halogen atom is not particularly limited, but is preferably a bromine atom or an iodine atom.

  The borate ester residue is not particularly limited, and examples thereof include a group represented by the following formula.

(In the above formula, Me represents a methyl group and Et represents an ethyl group.)

  The alkylstannyl group is not particularly limited, and examples thereof include a group represented by the following formula.

(In the above formula, Me represents a methyl group and Bu represents a butyl group.)

  The alkenyl group is not particularly limited, but for example, an alkenyl group having 2 to 12 carbon atoms is preferable.

Among the above, A and Q are each independently a halogen atom, an alkylstannyl group, boron, from the viewpoint of synthesis of the compound represented by formula (3) or (4) and the viewpoint of easy reaction. It is preferably an acid ester residue or a boric acid residue (—B (OH) ₂ ).

The reaction method used for the polymerization of the copolymer of the present invention includes Suzuki-Miyaura cross-coupling reaction method, Stille coupling reaction method, Yamamoto coupling reaction method, Grignard reaction method, Heck reaction method, Sonogashira reaction method, FeCl _{3 and the} like. A reaction method using an oxidizing agent, a method using an electrochemical oxidation reaction, a reaction method by decomposition of an intermediate compound having an appropriate leaving group, and the like. Among these, the Suzuki-Miyaura coupling reaction method, the Stille coupling reaction method, the Yamamoto coupling reaction method, and the Grignard reaction method are preferable in terms of easy structure control. In particular, the Suzuki-Miyaura cross-coupling reaction method, the Stille coupling reaction method, and the Grignard reaction method are preferable from the viewpoint of easy availability of materials and easy reaction operation. These reactions are described in "Cross Coupling-Fundamentals and Industrial Applications (CMC Publishing)", "Transition Metal Catalyzed Reactions for Organic Synthesis (edited by Jiro Jiro: edited by Organic Synthetic Chemistry Association)", "For Organic Synthesis" The reaction can be carried out according to a method described in known literature such as “catalytic reaction 103 (Teijiro Hatakeyama: Tokyo Kagaku Dojin)”.

  Although there is no particular limitation, for example, when A or Q is an alkylstannyl group, the reaction may be performed in accordance with known Stille coupling reaction conditions. Further, when A or B is a boric acid ester residue or a boric acid residue, the reaction may be carried out according to the conditions of a known Suzuki-Miyaura coupling reaction. Furthermore, when A or Q is a silyl group, the reaction may be carried out according to the conditions of the known Hiyama coupling reaction. As a catalyst for the coupling reaction, for example, a combination of a transition metal such as palladium and a ligand (for example, a phosphine ligand such as triphenylphosphine) can be used.

  Below, the manufacturing method of the copolymer based on this invention using the Stille coupling reaction method is demonstrated as a typical example.

  When the Stille coupling reaction method is used, A in Formula (3) is a halogen atom and B in Formula (4) is an alkylstannyl group, or A in Formula (3) is alkylstannyl. It is preferable that X in the formula (4) is a halogen atom.

  The ratio of the amount of the compound represented by the formula (4) to the amount of the compound represented by the formula (3) used in the polymerization reaction is usually 0.90 or more, preferably 0.8. On the other hand, it is usually 1.3 or less, preferably 1.2 or less. It is preferable that the molar ratio is within such a range because a high molecular weight product can be obtained with a higher yield.

  When the copolymer according to the present invention is produced with high purity, it is preferable to carry out the polymerization reaction after purifying the monomer before polymerization (compounds represented by formulas (3) and (4)). Examples of the purification method include distillation, sublimation purification, column chromatography, recrystallization, and the like.

  For example, when the copolymer according to the present invention is used as a material for an organic photoelectric conversion device, it is desirable that the copolymer has a high purity because the device characteristics can be improved due to its high purity. When the copolymer according to the present invention is used as a material for an organic photoelectric conversion element, the purity of each of the compounds represented by the formulas (3) and (4) is preferably 90% or more, and 95% or more. Is more preferable.

  A transition metal catalyst or the like may be used for promoting polymerization in the polymerization reaction. What is necessary is just to select a transition metal catalyst according to the kind of superposition | polymerization. Examples of transition metal catalysts include homogeneous transition metal catalysts and heterogeneous transition metal catalysts.

The homogeneous transition metal catalyst is preferably one that is sufficiently soluble in the solvent used for the polymerization reaction. Preferred examples include late transition metal complex catalysts containing palladium, nickel, iron, or copper, among others. Specific examples include zero-valent palladium catalysts such as tetrakis (triphenylphosphine) palladium (Pd (PPh ₃ ) ₄ ) or tris (dibenzylideneacetone) dipalladium (Pd ₂ (dba) ₃ ); bis (tri Palladium (Pd) catalysts such as phenylphosphine) palladium chloride (PdCl ₂ ((PPh ₃ )) ₂ ) or divalent palladium catalysts such as palladium acetate; nickel such as Ni (dppp) Cl ₂ or Ni (dppe) Cl ₂ Catalysts: iron catalysts such as iron chloride; copper catalysts such as copper iodide. Here, dba represents dibenzylideneacetone, dppp represents 1,2-bis (diphenylphosphino) propane, and dppe represents 1,2-bis (diphenylphosphino) ethane.

Specific examples of the zero-valent Pd catalyst include Pd (PPh ₃ ) ₄ , Pd (P (o-tolyl) ₃ ) ₄ , Pd (PCy ₃ ) ₂ , Pd ₂ (dba) _3, PdCl ₂ (PPh ₃ ) ) ₂ etc. are mentioned. When a divalent Pd catalyst such as PdCl ₂ ((PPh ₃ )) ₂ or palladium acetate is used, it is preferably used in combination with an organic ligand such as PPh ₃ or P (o-tolyl) ₃ . Here, Ph represents a phenyl group, Cy represents a cyclohexyl group, and o-tolyl represents a 2-tolyl group.

  Examples of the heterogeneous transition metal catalyst include a catalyst obtained by supporting a homogeneous transition metal catalyst as described above on a carrier. Preferable examples of the transition metal included in the heterogeneous transition metal catalyst include late transition metals including palladium, nickel, iron, or copper. As an organic ligand which a heterogeneous transition metal complex catalyst has, the same thing as what was mentioned about the homogeneous transition metal complex catalyst can be used. In addition, organic ligands described in known literature (Strem, “Heterogeneous Catalysts” (2011)) can also be used. Examples of the carrier include metals, nanocolloids, nanoparticles, magnetic compounds, metal oxides, porous materials, clays, polymers such as urea resins, and dendrimers. Specific examples of the porous material include microporous material, mesoporous material, activated carbon, silica gel, alumina, and zeolite. In particular, it is preferable to use a heterogeneous transition metal complex catalyst supported on a polymer because the heterogeneous transition metal complex catalyst can be easily recovered. Moreover, it is more preferable that the polymer is porous in terms of promoting the reaction.

  In the polymerization reaction, it is preferable to use two or more transition metal complex catalysts in that a high molecular weight copolymer can be obtained. For example, two or more kinds of homogeneous transition metal complexes may be used, two or more kinds of heterogeneous transition metal complexes may be used, or a combination of a homogeneous transition metal complex and a heterogeneous transition metal complex may be used. May be used. Of these two or more transition metal complex catalysts, at least one of them is preferably a heterogeneous metal complex catalyst in that a monomer can be quickly converted into an oligomer under coupling reaction conditions. In addition, since oligomerization tends to decrease the polymerization reaction rate due to the heterogeneous metal catalyst, it is preferable to induce the oligomer to the polymer with the homogeneous metal catalyst in order to obtain a high molecular weight product. From this viewpoint, it is more preferable that at least one of the two or more transition metal complex catalysts is a heterogeneous metal complex catalyst and at least one is a homogeneous metal complex catalyst.

The amount of the transition metal complex used relative to the total amount of the compounds represented by formulas (3) and (4) is usually 1 × 10 ⁻⁴ mol% or more, preferably 1 × 10 ⁻³ mol% or more, more preferably and a 1 × ¹⁰ -2 mol% or more, whereas, usually 1 × ¹⁰ 2 mol%, more preferably at most 5 mol%. It is preferable that the amount of the catalyst used be in this range because a higher molecular weight copolymer tends to be obtained at a lower cost and a higher yield.

  When a transition metal catalyst is used, an alkali, a cocatalyst, or a phase transfer catalyst may be used in combination.

  Examples of the alkali include inorganic bases such as potassium carbonate, sodium carbonate and cesium carbonate; organic bases such as triethylamine.

Examples of the cocatalyst include inorganic salts such as cesium fluoride, copper oxide, and copper halide. The amount of the cocatalyst used is usually 1 × 10 ⁻⁴ mol% or more, preferably 1 × 10 ⁻³ mol% or more, based on the total amount of the compounds represented by formulas (3) and (4). Preferably, it is 1 × 10 ⁻² mol% or more, and is usually 1 × 10 ⁴ mol% or less, preferably 1 × 10 ³ mol% or less, more preferably 1.5 × 10 ² mol% or less. It is preferable that the amount of the cocatalyst used be in this range because the copolymer tends to be obtained at a lower cost and with a higher yield.

Examples of the phase transfer catalyst include tetraethylammonium hydroxide or quaternary ammonium salts such as Aliquat 336 (manufactured by Aldrich). The amount of the phase transfer catalyst used is usually 1 × 10 ⁻⁴ mol% or more, preferably 1 × 10 ⁻³ mol% or more, based on the total amount of the compounds represented by the formulas (3) and (4). More preferably, it is 1 × 10 ⁻² mol% or more, while it is usually 5 mol% or less, more preferably 3 mol% or less. It is preferable that the amount of the phase transfer catalyst used is in this range because the copolymer tends to be obtained at a lower cost and in a higher yield.

  Examples of the solvent used in the polymerization reaction include saturated hydrocarbons such as pentane, hexane, heptane, octane, and cyclohexane; aromatic hydrocarbons such as benzene, toluene, ethylbenzene, and xylene; halogens such as chlorobenzene, dichlorobenzene, and trichlorobenzene. Aromatic hydrocarbons; alcohols such as methanol, ethanol, propanol, isopropanol, butanol or t-butyl alcohol; water; ethers such as dimethyl ether, diethyl ether, methyl t-butyl ether, tetrahydrofuran, tetrahydropyran or dioxane; DMF And aprotic polar organic solvents such as These solvents may be used alone or in combination of two or more.

The amount of the solvent used is usually 1 × 10 ⁻² mL or more, preferably 1 × 10 ⁻¹ mL or more, more preferably ¹ mL with respect to a total of 1 g of the compounds represented by formulas (3) and (4). On the other hand, it is usually 1 × 10 ⁵ mL or less, preferably 1 × 10 ³ mL or less, more preferably 2 × 10 ² mL or less. It is preferable that the amount of the solvent used is in this range in that the reaction can be easily controlled.

The reaction temperature of the polymerization reaction is usually 0 ° C. or higher, preferably 20 ° C. or higher, more preferably 40 ° C. or higher, and further preferably 60 ° C. or higher. On the other hand, it is usually 300 ° C. or lower, preferably 250 ° C. or lower, more preferably 200 ° C. or lower, further preferably 180 ° C. or lower, and particularly preferably 160 ° C. or lower. The heating method is not particularly limited, but examples include oil bath heating, thermocouple heating, infrared heating, microwave heating, heating by contact using an IH heater, and the like. The time for the polymerization reaction is usually 1 minute or more, preferably 10 minutes or more, while it is usually 160 hours or less, preferably 120 hours or less, more preferably 100 hours or less. The polymerization reaction is preferably performed in a nitrogen (N ₂ ) or argon (Ar) atmosphere. By carrying out the reaction under these reaction conditions, the copolymer can be obtained in a shorter time and with a higher yield.

It is preferable to further end-treat the copolymer obtained by the polymerization reaction. By performing the terminal treatment of the copolymer, the residual amount of the terminal residues (A and Q described above) of the copolymer can be reduced. For example, when a copolymer is polymerized by a Stille coupling reaction, halogen atoms such as bromine (Br) and iodine (I) and alkylstannyl groups present at the terminal of the copolymer can be reduced by terminal treatment. This terminal treatment is preferable because a copolymer having better performance in terms of efficiency and durability can be obtained.

  The terminal treatment method of the copolymer after the polymerization reaction is not particularly limited, and examples thereof include a method of substituting the terminal residue with another substituent such as an aromatic group.

  For example, as a terminal treatment method when a copolymer is polymerized by a Stille coupling reaction, the following method may be mentioned. The method for terminal treatment of the halogen atom of the copolymer can be carried out by adding aryltrialkyltin as a terminal treatment agent in the reaction system after the polymerization reaction and before purification, followed by heating and stirring. Examples of aryltrialkyltin include phenyltrimethyltin or thienyltrimethyltin. Substitution of a halogen atom at the terminal of the copolymer with an aromatic group is preferable because the copolymer becomes more stable due to the conjugate stability effect.

The addition amount of the end treatment agent is not particularly limited, but is usually 1.0 × 10 ⁻² molar equivalent or more with respect to the amount of the monomer (3 or 4) having a halogen atom at the terminal used in the polymerization reaction. , Preferably 0.1 molar equivalents or more, more preferably 1 molar equivalents or more, and usually 50 molar equivalents or less, preferably 20 molar equivalents or less, more preferably 10 molar equivalents or less. The reaction temperature of the halogen atom terminal treatment is usually 0 ° C. or higher, preferably 20 ° C. or higher, more preferably 40 ° C. or higher, and further preferably 60 ° C. or higher. On the other hand, it is usually 300 ° C. or lower, preferably 250 ° C. or lower, more preferably 200 ° C. or lower, further preferably 180 ° C. or lower, and particularly preferably 160 ° C. or lower. The heating method is not particularly limited, and examples thereof include oil bath heating, thermocouple heating, infrared heating, microwave heating, heating by contact using an IH heater, and the like. The reaction time of the terminal treatment of the halogen atom of the copolymer is not particularly limited, but is usually 30 minutes or longer, preferably 1 hour or longer, and is usually 50 hours or shorter, preferably 20 hours or shorter. By performing the reaction under these reaction conditions, the terminal treatment can be performed in a shorter time and with a higher conversion rate.

  Further, the terminal treatment method of the alkylstannyl group of the copolymer can be carried out by adding an aryl halide as a terminal treating agent in the reaction system after the polymerization reaction and before purification, followed by heating and stirring. Examples of aryl halides include iodothiophene, iodobenzene, bromothiophene or bromobenzene. By substituting the alkylstannyl group at the terminal of the copolymer with another substituent, the Sn atom in the alkylstannyl group which is easily thermally decomposed does not exist in the copolymer, and deterioration of the copolymer over time can be suppressed. Further, substitution of the alkylstannyl group at the terminal of the copolymer with an aryl group is also preferable in that the copolymer can be more stable due to the conjugate stability effect.

The addition amount of the end treatment agent is not particularly limited, but is usually 1.0 × 10 ⁻² molar equivalent to the amount of the monomer (3 or 4) having an alkylstannyl group at the terminal used for polymerization. As mentioned above, Preferably it is 0.1 molar equivalent or more, More preferably, it is 1 molar equivalent or more, On the other hand, Usually, it is 50 molar equivalent or less, Preferably it is 20 molar equivalent or less, More preferably, it is 10 molar equivalent or less. As the reaction temperature and reaction conditions for the terminal treatment of the alkylstannyl group, those similar to the terminal treatment of the halogen atom of the copolymer can be used. By performing the reaction under these reaction conditions, the terminal treatment can be performed in a shorter time and with a higher conversion rate.

Moreover, the following method is mentioned as a method of terminal treatment at the time of polymerizing a copolymer by Suzuki-Miyaura cross-coupling reaction. Examples of the method for terminal treatment of the halogen atom of the copolymer include a method in which arylboronic acid is added and then heated and stirred. Examples of the terminal treatment method of the boron atom-containing group of the copolymer include a method in which an aryl halide is added as a terminal treatment agent and then heated and stirred.

  There is no particular limitation on the terminal treatment method of the terminal residue, but it is preferable to carry out each independently. In addition, there is no special restriction | limiting in the order of each terminal process, It can select suitably.

  Further, the terminal treatment may be performed before the purification of the copolymer, but may be performed after the purification of the copolymer. When the end treatment is performed after the copolymer purification, the copolymer and one of the end treatment agents (for example, aryl halide or aryltrialkyltin) are dissolved in an organic solvent, and then a reaction is performed by adding a transition metal catalyst such as a palladium catalyst. Further, the other end treatment agent (aryltrialkyltin or aryl halide) may be added to carry out the reaction. From the viewpoint of accelerating the reaction, it is preferable to perform heating and stirring during the terminal treatment, as in the case where the terminal treatment is performed before the purification of the copolymer. Moreover, it is also preferable to perform reaction under nitrogen conditions from a viewpoint of improving a yield. The reaction time is not particularly limited, but is usually 30 minutes or longer, preferably 1 hour or longer, and is usually 25 hours or shorter, preferably 10 hours or shorter.

The addition amount of the transition metal catalyst is not particularly limited, but usually 5.0 × 10 ⁻³ molar equivalents or more, preferably with respect to the total amount of the compounds represented by formula (3) or (4) Is 1.0 × 10 ⁻² molar equivalent or more, and is usually 1.0 × 10 ⁻¹ molar equivalent or less, preferably 5.0 × 10 ⁻² molar equivalent or less. When the addition amount of the catalyst is within this range, the end treatment can be performed at a lower cost and at a higher conversion rate.

The addition amount of the alkylstannyl end-treating agent at the end treatment after refining the copolymer is not particularly limited, but the amount of the monomer (3 or 4) having an alkylstannyl group at the terminal used in the polymerization Is usually 1.0 × 10 ⁻² molar equivalents or more, preferably 1.0 × 10 ⁻¹ molar equivalents or more, more preferably 1 molar equivalents or more, and usually 50 molar equivalents or less, preferably 20 The molar equivalent or less, more preferably 10 molar equivalent or less. When the added amount of the end treatment agent is within this range, the end treatment can be performed at a lower cost and at a higher conversion rate.

The addition amount of the halogen atom end treatment agent at the end treatment after the copolymer formation is not particularly limited, but with respect to the amount of the monomer (2 or 3) having a halogen atom at the terminal used for polymerization, Usually 1.0 × 10 ⁻² molar equivalent or more, preferably 1.0 × 10 ⁻¹ molar equivalent or more, more preferably 1 molar equivalent or more, while usually 50 molar equivalent or less, preferably 20 molar equivalent or less, More preferably, it is 10 molar equivalents or less. When the added amount of the end treatment agent is within this range, the end treatment can be performed at a lower cost and at a higher conversion rate.

  Although there is no limitation in particular as a process performed after a polymerization reaction, Usually, the process of isolate | separating a copolymer is performed. When the terminal treatment of the copolymer is performed, it is preferable to perform a step of separating the copolymer after the terminal treatment. If necessary, further copolymer separation and purification may be performed prior to copolymer termination. From the viewpoint of obtaining the copolymer in a shorter processing step, it is preferable to carry out the terminal treatment of the copolymer, separation of the copolymer and purification of the copolymer in this order after the polymerization reaction.

  As a method for separating the copolymer, for example, the reaction solution and a poor solvent are mixed to precipitate the copolymer, or the active species in the reaction solution is quenched with water or hydrochloric acid, and then the copolymer is extracted with an organic solvent. Examples include a method of distilling off the organic solvent.

  Examples of the purification method of the copolymer include known methods such as reprecipitation purification, extraction using a Soxhlet extractor, gel permeation chromatography, or metal removal using a scavenger.

[2-1. Method for producing compounds represented by formulas (3) and (4)]
The method for producing the compound represented by the above formula (3) used as a raw material for the polymerization reaction is not particularly limited and can be produced by a known method. For example, it can be produced according to the method described in known literature (Macromolecular Rapid Communications (2007), 28 (17), 1786-1791). Similarly, the production method of the compound represented by the above formula (4) is not particularly limited and can be produced by a known method. For example, the known J.P. Am. Chem. , Soc. , 2010, 132 (22) 7595-7597.

<3. Electronic Device Using Copolymer According to the Present Invention>
An organic electronic device using the copolymer according to the present invention will be described. Specifically, the copolymer according to the present invention can be used for a light emitting element, a switching element, a photoelectric conversion element, a photosensor utilizing photoelectric conductivity, and the like.

  Examples of the light emitting element include various light emitting elements used for display devices. Specific examples include a liquid crystal display element, a polymer dispersion type liquid crystal display element, an electrophoretic display element, an electroluminescent element, an electrochromic element, and the like. Specific examples of the switching element include a diode (pn junction diode, Schottky diode, MOS diode, etc.), a transistor (bipolar transistor, field effect transistor (FET), etc.), a thyristor, and a composite element thereof (for example, TTL). Etc.). Specific examples of the photoelectric conversion element include a thin film solar cell, a charge coupled device (CCD), a photomultiplier tube, and a photocoupler. Moreover, what utilized these photoelectric conversion elements is mentioned as an optical sensor using photoelectric conductivity.

  The part of the organic electronic device in which the copolymer according to the present invention is used is not particularly limited and can be used in any part, but it is preferably used as a semiconductor layer material for the organic electronic device. In particular, in the case of a photoelectric conversion element, the organic semiconductor layer containing the organic semiconductor material according to the present invention is usually used as an organic active layer. Hereinafter, the photoelectric conversion element using the copolymer according to the present invention will be described.

<4. Photoelectric conversion element>
The photoelectric conversion element according to the present invention includes at least a base material, a pair of electrodes formed on the base material, and an active layer formed between the pair of electrodes, and the active layer is the present invention. Containing a copolymer according to Hereinafter, an embodiment of a photoelectric conversion element according to the present invention will be described with reference to FIG.

  As shown in FIG. 1, one embodiment of the photoelectric conversion element according to the present invention includes a lower electrode 101, a lower buffer layer 102, an active layer 103, an upper buffer layer 104, and an upper electrode on a substrate 106. 105 has a layered structure formed sequentially. In the present invention, the lower electrode means an electrode laminated on the substrate 106 side, and the upper electrode means an electrode laminated above the lower electrode when the substrate 106 is used as the bottom. . In the present invention, the lower electrode 101 and the upper electrode 105 may be collectively referred to as a pair of electrodes. In addition, the lower buffer layer 102 and the upper buffer layer 104 are not essential components, and may be provided arbitrarily, and may include only one of the lower buffer layer 102 and the upper buffer layer 104. Moreover, the photoelectric conversion element may optionally have another layer other than the above. Hereinafter, each component of the photoelectric conversion element will be described.

<4-1. Substrate 106>
The photoelectric conversion element 107 is usually formed on a base material 106 that serves as a support. There is no particular limitation on the material of the substrate 106. Preferable examples of the material of the substrate 106 include inorganic materials such as quartz, glass, sapphire, and titania, and flexible substrates. Specific examples of the flexible substrate include, but are not limited to, polyethylene terephthalate, polyethylene naphthalate, polyethersulfone, polyimide, nylon, polystyrene, polyvinyl alcohol, ethylene vinyl alcohol copolymer, fluororesin film, vinyl chloride. Or polyolefin such as polyethylene; organic material (resin substrate) such as cellulose, polyvinylidene chloride, aramid, polyphenylene sulfide, polyurethane, polycarbonate, polyarylate, polynorbornene, or epoxy resin; paper material such as paper or synthetic paper; stainless steel, Examples thereof include composite materials such as a metal foil such as titanium or aluminum whose surface is coated or laminated in order to impart insulation.

  Examples of the glass include soda glass, blue plate glass, and non-alkali glass. Among these, alkali-free glass is preferable in that there are few eluted ions from the glass.

  There is no restriction | limiting in the shape of the base material 106, For example, things, such as plate shape, a film form, or a sheet form, can be used.

  Although there is no restriction | limiting in the film thickness of the base material 106, Usually, it is 5 micrometers or more, Preferably it is 20 micrometers or more, On the other hand, it is 20 mm or less normally, Preferably it is 10 mm or less. It is preferable that the thickness of the substrate is 5 μm or more because the possibility that the strength of the photoelectric conversion element is insufficient is reduced. It is preferable that the thickness of the substrate 106 is 20 mm or less because the cost is suppressed and the mass is not increased. In addition, the film thickness when the material of the base material 106 is glass is usually 0.01 mm or more, preferably 0.1 mm or more, and is usually 1 cm or less, preferably 0.5 cm or less. It is preferable that the glass substrate has a film thickness of 0.01 mm or more because the mechanical strength increases and it is difficult to break. Moreover, it is preferable that the film thickness of the glass substrate is 0.5 cm or less because the mass does not increase.

<4-2. Pair of electrodes (lower electrode 101 and upper electrode 105)>
The pair of electrodes (101, 106) has a function of collecting holes and electrons generated by light absorption. Accordingly, the pair of electrodes includes an electrode suitable for collecting holes (hereinafter sometimes referred to as an anode) and an electrode suitable for collecting electrons (hereinafter sometimes referred to as a cathode). It is preferable to use it. Any one of the pair of electrodes may be translucent, and both may be translucent. Translucency means that sunlight passes through 40% or more. Further, the solar light transmittance of the transparent electrode is preferably 70% or more in order to allow light to reach the active layer through the transparent electrode. The light transmittance can be measured with a normal spectrophotometer.

  The anode is an electrode generally made of a conductive material having a work function higher than that of the cathode and having a function of smoothly extracting holes generated in the active layer.

  Examples of anode materials include conductive metal oxides such as nickel oxide, tin oxide, indium oxide, indium tin oxide (ITO), indium-zirconium oxide (IZO), titanium oxide, indium oxide, and zinc oxide; Examples thereof include metals such as gold, platinum, silver, chromium and cobalt, or alloys thereof. These substances are preferable because they have a high work function, and further, a conductive polymer material represented by PEDOT: PSS in which a polythiophene derivative is doped with polystyrene sulfonic acid can be stacked. When laminating such a conductive polymer, the work function of this conductive polymer material is high, so even if it is not a material with a high work function as described above, it is suitable for cathodes such as Al and Mg. Metals can also be widely used. PEDOT: PSS in which a polythiophene derivative is doped with polystyrene sulfonic acid, or a conductive polymer material in which polypyrrole, polyaniline, or the like is doped with iodine or the like can also be used as an anode material.

  When the anode is a transparent electrode, it is preferable to use a light-transmitting conductive metal oxide such as ITO, zinc oxide or tin oxide, and ITO is particularly preferable.

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

  The sheet resistance of the anode is not particularly limited, but is usually 1Ω / □ or more, on the other hand, 1000Ω / □ or less, preferably 500Ω / □ or less, more preferably 100Ω / □ or less.

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

  The cathode is generally an electrode made of a conductive material having a low work function, and having a function of smoothly extracting electrons generated in the active layer 103. The cathode is adjacent to the electron extraction layer.

  Examples of cathode materials include platinum, gold, silver, copper, iron, tin, zinc, aluminum, indium, chromium, lithium, sodium, potassium, cesium, calcium, and magnesium, and alloys thereof; lithium fluoride And inorganic salts such as cesium fluoride and metal oxides such as nickel oxide, aluminum oxide, lithium oxide, and cesium oxide. These materials are preferable because they are materials having a low work function. Similarly to the anode, a material having a high work function can be used for the cathode by using an n-type semiconductor such as titania having conductivity as the electron extraction layer. From the viewpoint of electrode protection, the cathode material is preferably a metal such as platinum, gold, silver, copper, iron, tin, aluminum, calcium or indium, or an alloy using these metals such as indium tin oxide.

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

  The sheet resistance of the cathode is not particularly limited, but is usually 1000Ω / □ or less, preferably 500Ω / □ or less, and more preferably 100Ω / □ or less. Although there is no restriction on the lower limit, it is usually 1Ω / □ or more.

  As a method for forming the cathode, there are a vacuum film formation method such as a vapor deposition method or a sputtering method, or a wet coating method in which an ink containing nanoparticles or a precursor is applied to form a film.

  Furthermore, the anode and the cathode may have a laminated structure of two or more layers. In addition, characteristics (electric characteristics, wetting characteristics, etc.) may be improved by performing surface treatment on the anode and the cathode.

  After laminating the anode and cathode, the photoelectric conversion element is usually heated in a temperature range of 50 ° C. or higher, preferably 80 ° C. or higher, and usually 300 ° C. or lower, preferably 280 ° C. or lower, more preferably 250 ° C. or lower. Is preferable (this step may be referred to as an annealing treatment step). By performing the annealing treatment step at a temperature of 50 ° C. or more, an effect of improving the adhesion between the layers of the photoelectric conversion element, for example, the adhesion between the electron extraction layer and the cathode and / or the electron extraction layer and the active layer described later is obtained. Therefore, it is preferable. By improving the adhesion between the layers, the thermal stability and durability of the thin-film solar cell element can be improved. It is preferable to set the temperature of the annealing treatment step to 300 ° C. or lower because the possibility that the organic compound in the active layer is thermally decomposed is reduced. In the annealing treatment step, stepwise heating may be performed within the above temperature range.

  The heating time is usually 1 minute or longer, preferably 3 minutes or longer, and usually 3 hours or shorter, preferably 1 hour or shorter. The annealing treatment step is preferably terminated when the open-circuit voltage, the short-circuit current, and the fill factor, which are parameters of the solar cell performance, reach a constant value. Further, the annealing treatment step is preferably performed under normal pressure and in an inert gas atmosphere.

  As a heating method, the organic thin film solar cell element may be placed on a heat source such as a hot plate, or the organic thin film solar cell element may be placed in a heating atmosphere such as an oven. The heating may be performed batchwise or continuously.

<4-3. Active layer 103>
The active layer 103 is a layer that contains a p-type semiconductor compound and an n-type semiconductor compound and undergoes photoelectric conversion. Specifically, when the photoelectric conversion element 107 receives light, the light is absorbed by the active layer 103, electricity is generated at the interface between the p-type semiconductor material and the n-type semiconductor material, and the generated electricity is extracted from the anode and the cathode. It is.

  As the layer structure of the active layer 103, a thin film stack type in which a layer containing a p-type semiconductor compound and a layer containing an n-type semiconductor compound are stacked, or a layer in which a p-type semiconductor compound and an n-type semiconductor compound are mixed is used. A bulk heterojunction type. Note that the bulk heterojunction active layer may have a structure in which a layer containing a p-type semiconductor compound and / or a layer containing an n-type semiconductor compound is further stacked in addition to the mixed layer. From the viewpoint that high photoelectric conversion efficiency can be expected, a bulk heterojunction type is preferable.

  Examples of the p-type semiconductor compound contained in the active layer 103 include a copolymer according to the present invention. When the active layer 103 contains the copolymer according to the present invention, light on a longer wavelength side can be absorbed, and a photoelectric conversion element having high conversion efficiency can be provided.

  The active layer 103 may contain other p-type semiconductor compounds in addition to the copolymer according to the present invention as long as the effects according to the present invention are not impaired. The other p-type semiconductor compound may be a low molecular organic compound or a high molecular compound. Although there is no special restriction | limiting as these p-type semiconductor compounds, For example, what is described in well-known literatures, such as international publication 2011/016430 or Unexamined-Japanese-Patent No. 2012-191194, can be used.

The n-type semiconductor compound is not particularly limited. For example, a fullerene compound; a quinolinol derivative metal complex represented by 8-hydroxyquinoline aluminum; a condensed ring tetracarboxylic acid such as naphthalenetetracarboxylic acid diimide or perylenetetracarboxylic acid diimide. Acid diimides; perylene diimide derivatives, terpyridine metal complexes, tropolone metal complexes, flavonol metal complexes, perinone derivatives, benzimidazole derivatives, benzoxazole derivatives, thiazole derivatives, benzthiazole derivatives, benzothiadiazole derivatives, oxadiazole derivatives, thiadiazole derivatives, Triazole derivatives, aldazine derivatives, bisstyryl derivatives, pyrazine derivatives, phenanthroline derivatives, quinoxaline derivatives, benzoquinoline derivatives, Pyridine derivatives, borane derivatives; anthracene, pyrene, total fluoride condensed polycyclic aromatic hydrocarbons such as naphthacene or pentacene; single-walled carbon nanotubes, n-type polymer (n-type polymer semiconductor material), and the like.

  Among them, fullerene compounds, borane derivatives, thiazole derivatives, benzothiazole derivatives, benzothiadiazole derivatives, N-alkyl-substituted naphthalenetetracarboxylic acid diimides, N-alkyl-substituted perylene diimide derivatives or n-type polymer semiconductor materials are preferable. More preferred are fullerene compounds, N-alkyl substituted perylene diimide derivatives, N-alkyl substituted naphthalene tetracarboxylic acid diimides or n-type polymer semiconductor compounds, and fullerene compounds are particularly preferred. These compounds are not particularly limited, but for example, compounds described in publicly known documents such as International Publication No. 2011-016430 or JP 2012-191194 A can be used. In addition, a kind of compound may be used among the above, and a mixture of a plurality of kinds of compounds may be used. Among these, it is particularly preferable to use 60 PCBM, 70 PCBM or a mixture thereof.

  The thickness of the active layer 103 is not particularly limited, but is usually 10 nm or more, preferably 50 nm or more, and is usually 1 μm or less, preferably 500 nm or less, more preferably 200 nm or less. A thickness of the active layer 103 of 10 nm or more is preferable because the uniformity of the film is maintained and a short circuit is hardly caused. In addition, it is preferable that the thickness of the active layer 103 is 1 μm or less because the internal resistance is reduced, and further, the charge diffusion is improved without the pair of electrodes being separated too much.

  A method for forming the active layer 103 is not particularly limited, but is preferably formed by a coating method because productivity is improved. Specifically, the active layer 103 is preferably formed by applying an active layer forming ink containing a copolymer according to the present invention.

  As the coating method, any method can be used. For example, spin coating method, reverse roll coating method, gravure coating method, kiss coating method, roll brush method, spray coating method, air knife coating method, wire barber coating method, pipe Examples include a doctor method, an impregnation / coating method, and a curtain coating method.

  When forming a laminated type active layer, an active layer forming ink containing at least a copolymer according to the present invention as a p-type semiconductor compound and an active layer ink containing an n-type semiconductor compound are used, respectively, by a coating method. An active layer may be formed by stacking a p-type semiconductor-containing layer and an n-type semiconductor-containing layer. On the other hand, when forming a bulk hetero type active layer, an active layer forming ink containing at least a copolymer according to the present invention and an n type semiconductor compound as a p type semiconductor compound is used, and a bulk hetero type active layer is formed by a coating method. An active layer may be formed.

The above-mentioned ink for forming an active layer usually contains a solvent in addition to the above-mentioned compound. The solvent is not particularly limited, but for example, aliphatic hydrocarbons such as hexane, heptane, octane, isooctane, nonane or decane; aromatic such as toluene, xylene, mesitylene, cyclohexylbenzene, chlorobenzene or orthodichlorobenzene Hydrocarbons; cycloaliphatic hydrocarbons such as cyclopentane, cyclohexane, methylcyclohexane, cycloheptane, cyclooctane, tetralin or decalin; lower alcohols such as methanol, ethanol or propanol; acetone, methyl ethyl ketone, cyclopentanone or cyclohexanone Aliphatic ketones such as acetophenone or propiophenone; esters such as ethyl acetate, butyl acetate or methyl lactate; chloroform, Methylene, dichloroethane, halogenated hydrocarbons such as trichloroethane or trichlorethylene; ethers such as ethyl ether and tetrahydrofuran or dioxane; or an amide such as dimethylformamide or dimethylacetamide, and the like.

  Among them, aromatic hydrocarbons such as toluene, xylene, mesitylene, cyclohexylbenzene, chlorobenzene or orthodichlorobenzene; cycloaliphatic carbonization such as cyclopentane, cyclohexane, methylcyclohexane, cycloheptane, cyclooctane, tetralin or decalin Hydrogens; ketones such as acetone, methyl ethyl ketone, cyclopentanone or cyclohexanone; halogen hydrocarbons such as chloroform, methylene chloride, dichloroethane, trichloroethane or trichloroethylene; or ethers such as ethyl ether, tetrahydrofuran or dioxane. More preferably, non-halogen aromatic hydrocarbons such as toluene, xylene, mesitylene or cyclohexylbenzene; non-halogen ketones such as cyclopentanone or cyclohexanone; aromatic ketones such as acetophenone or propiophenone; tetrahydrofuran, cyclohexane Alicyclic hydrocarbons such as pentane, cyclohexane, methylcyclohexane, cycloheptane, cyclooctane, tetralin or decalin; ketones such as acetone, methyl ethyl ketone, cyclopentanone or cyclohexanone; or non-halogens such as 1,4-dioxane Aliphatic ethers. Particularly preferred are non-halogen aromatic hydrocarbons such as toluene, xylene, mesitylene or cyclohexylbenzene.

  As the solvent, one kind of solvent may be used alone, or any two or more kinds of solvents may be used in any ratio. When two or more kinds of solvents are used in combination, it is preferable to combine a low boiling point solvent having a boiling point of 60 ° C. or higher and 150 ° C. or lower and a high boiling point solvent having a boiling point of 180 ° C. or higher and 250 ° C. or lower. Examples of combinations of low and high boiling solvents include non-halogen aromatic hydrocarbons and alicyclic hydrocarbons, non-halogen aromatic hydrocarbons and aromatic ketones, ethers and alicyclic carbonization. Examples thereof include hydrogens, ethers and aromatic ketones, aliphatic ketones and alicyclic hydrocarbons, or aliphatic ketones and aromatic ketones. Specific examples of preferred combinations include toluene and tetralin, xylene and tetralin, toluene and acetophenone, xylene and acetophenone, tetrahydrofuran and tetralin, tetrahydrofuran and acetophenone, methyl ethyl ketone and tetralin, methyl ethyl ketone and acetophenone, and the like.

  In addition to the compounds described above, the active layer forming ink may contain other additives as long as the effects of the present invention are not impaired.

<4-4. Lower buffer layer 102, upper buffer layer 104>
As described above, the photoelectric conversion element according to this embodiment includes the lower buffer layer 102 between the lower electrode 101 and the active layer 103, and the upper buffer layer 104 between the upper electrode 105 and the active layer 103. . The lower buffer layer 102 and the upper buffer layer 104 each have a function of improving the electron extraction efficiency from the active layer 103 to the cathode or the hole extraction efficiency from the active layer 103 to the anode. Note that a buffer layer having a function of improving the electron extraction efficiency from the active layer 103 to the cathode is referred to as an electron extraction layer, and a buffer layer having a function of improving the electron extraction efficiency from the active layer 103 to the cathode is referred to as a hole extraction layer. As described above, the lower buffer layer 102 and the upper buffer layer 104 are not essential components, and the organic thin film solar cell element 4 may not include the lower buffer layer 102 and the upper buffer layer 104. Moreover, you may have only any one layer.

Either the lower buffer layer 102 or the upper buffer layer 104 may be an electron extraction layer or a hole extraction layer, but when the lower electrode 101 is a cathode and the upper electrode 105 is an anode, the lower buffer layer 102 is an electron extraction layer. The upper buffer layer 104 is a hole extraction layer. On the other hand, when the lower electrode 101 is an anode and the upper electrode 105 is a cathode, the lower buffer layer 102 is a hole extraction layer and the upper buffer layer 104 is an electron extraction layer.

<4-4-1. Electron extraction layer>
The material of the electron extraction layer is not particularly limited as long as it is a material that improves the efficiency of extracting electrons from the active layer 103 to the cathode, and examples thereof include inorganic compounds and organic compounds.

  Examples of inorganic compounds include salts of alkali metals such as Li, Na, K or Cs; n-type semiconductor oxides such as titanium oxide (TiOx) and zinc oxide (ZnO). Among them, the alkali metal salt is preferably a fluoride salt such as LiF, NaF, KF or CsF, and the n-type semiconductor oxide is preferably zinc oxide (ZnO). Although the operation mechanism of such a material is unknown, it is conceivable to reduce the work function of the cathode when combined with a cathode made of Al or the like and increase the voltage applied to the solar cell element.

  Examples of organic compounds include phosphine compounds having a double bond between a phosphorus atom and a group 16 element such as triarylphosphine oxide compounds; substituents such as bathocuproin (BCP) or bathophenanthrene (Bphen) A phenanthrene compound in which the 1-position and the 10-position may be substituted with a heteroatom; a boron compound such as triarylboron; an organometallic such as (8-hydroxyquinolinato) aluminum (Alq3) Oxide; Compound having 1 or 2 ring structure which may have a substituent such as oxadiazole compound or benzimidazole compound; naphthalenetetracarboxylic anhydride (NTCDA) or perylenetetracarboxylic anhydride Such as (PTCDA), such as dicarboxylic anhydride Aromatic compounds having a slip dicarboxylic acid structure.

  The thickness of the electron extraction layer is usually 0.1 nm or more, preferably 1 nm or more, more preferably 10 nm or more. On the other hand, it is usually 400 nm or less, preferably 200 nm or less. When the film thickness of the electron extraction layer is 0.1 nm or more, it functions as a buffer material. When the film thickness of the electron extraction layer is 400 nm or less, electrons are easily extracted and the photoelectric conversion efficiency is improved. Can improve.

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

  The HOMO energy level of the material for the electron extraction layer is not particularly limited, but is usually −9.0 eV or more, preferably −8.0 eV or more. On the other hand, it is usually −5.0 eV or less, preferably −5.5 eV or less. The HOMO energy level of the material for the electron extraction layer is preferably −5.0 eV or less from the viewpoint of preventing movement of holes.

  As a method for calculating the LUMO energy level and the HOMO energy level of the material of the electron extraction layer, a cyclic voltammogram measurement method may be mentioned. For example, it can implement with reference to the method as described in well-known literature (International Publication 2011/016430).

When the material of the electron extraction layer is an organic compound, the glass transition temperature (hereinafter sometimes referred to as Tg) of this compound as measured by the DSC method is not particularly limited, but is not observed, or It is preferable that it is 55 degreeC or more. That the glass transition temperature is not observed by the DSC method means that there is no glass transition temperature. Specifically, the determination is made based on the presence or absence of a glass transition temperature of 400 ° C. or lower. A material in which the glass transition temperature by the DSC method is not observed is preferable in that it has high thermal stability.

  Among the compounds having a glass transition temperature of 55 ° C. or higher as measured by the DSC method, the glass transition temperature is preferably 65 ° C. or higher, more preferably 80 ° C. or higher, more preferably 110 ° C. or higher, particularly preferably. A compound having a temperature of 120 ° C. or higher is desirable. On the other hand, the upper limit of the glass transition temperature is not particularly limited, but is usually 400 ° C. or lower, preferably 350 ° C. or lower, more preferably 300 ° C. or lower. Moreover, it is preferable that the material of an electron taking-out layer is a thing by which the glass transition temperature by DSC method is not observed below 30 degreeC or more and less than 55 degree | times.

  The glass transition temperature in the present specification is defined as a point at which specific heat changes in an amorphous solid, which is a temperature at which local molecular motion is started by thermal energy. When the temperature rises further than Tg, the solid structure changes and crystallization occurs (the temperature at this time is defined as the crystallization temperature (Tc)). When the temperature rises further, it generally melts at the melting point (Tm) and changes to a liquid state. However, these phase transitions may not be observed due to molecular decomposition or sublimation at high temperatures.

  The DSC method is a thermophysical property measurement method (differential scanning calorimetry method) defined in JIS K-0129 “General Rules for Thermal Analysis”. In order to determine the glass transition temperature more clearly, it is desirable to measure after rapidly cooling a sample once heated to a temperature higher than the glass transition temperature. For example, the measurement can be carried out by a method described in a known document (International Publication No. 2011/016430).

  When the glass transition temperature of the compound used for the electron extraction layer is 55 ° C. or higher, the structure of this compound is difficult to change against external stress such as applied electric field, flowing current, stress due to bending or temperature change. It is preferable in terms of durability. Furthermore, since there is a tendency that the crystallization of the thin film of the compound does not proceed easily, the stability of the electron extraction layer is improved by making it difficult for the compound to change between the amorphous state and the crystalline state in the operating temperature range. Therefore, it is preferable in terms of durability. This effect becomes more prominent as the glass transition temperature of the material is higher.

  There is no restriction | limiting in the formation method of an electronic taking-out layer. For example, when a material having sublimation property is used, it can be formed by a vacuum deposition method or the like. Further, for example, when a material soluble in a solvent is used, it can be formed by a wet coating method such as spin coating or inkjet.

When the electron extraction layer is formed by a coating method, a surfactant may be further contained in the coating solution. By using the surfactant, the occurrence of dents due to adhesion of fine bubbles or foreign matters and / or uneven coating in the drying process is suppressed. Known surfactants (cationic surfactants, anionic surfactants, nonionic surfactants) can be used as the surfactant. Of these, silicon-based surfactants, acetylenic diol-based surfactants, and fluorine-based surfactants are preferable. In addition, as surfactant, only 1 type may be used and 2 or more types may be used together by arbitrary combinations and a ratio.
Specifically, for example, when an alkali metal salt is used as a material for the electron extraction layer, the electron extraction layer can be formed by using a vacuum film formation method such as vacuum deposition or sputtering. Especially, it is desirable to form an electron taking-out layer by vacuum vapor deposition by resistance heating. By using vacuum deposition, damage to other layers such as an active layer can be reduced.

On the other hand, for metal oxides of n-type semiconductors, for example, when zinc oxide ZnO is used as the material for the electron extraction layer, a vacuum film formation method such as sputtering can be used. It is desirable to form the extraction layer. For example, Sol-Gel Science, C.I. J. et al. Brinker, G.M. W. According to the sol-gel method described by Scherer, Academic Press (1990), an electron extraction layer composed of zinc oxide can be formed. In this case, the film thickness is usually 0.1 nm or more, preferably 2 nm or more, more preferably 5 nm or more, and usually 1 μm or less, preferably 100 nm or less, more preferably 50 nm or less. If the electron extraction layer is too thin, the effect of improving the electron extraction efficiency is not sufficient, and if it is too thick, the electron extraction layer tends to deteriorate the characteristics of the device by acting as a series resistance component.

<4-4-2. Hole extraction layer>
The material for the hole extraction layer is not particularly limited as long as it is a material capable of improving the efficiency of extracting holes from the active layer 103 to the anode. Specifically, conductive polymers in which polythiophene, polypyrrole, polyacetylene, triphenylenediamine, polyaniline, etc. are doped with sulfonic acid and / or iodine, polythiophene derivatives having a sulfonyl group as a substituent, conductive organics such as arylamine Examples thereof include compounds, copper oxide, nickel oxide, manganese oxide, molybdenum oxide, vanadium oxide, metal oxide such as tungsten oxide, Nafion, and a p-type semiconductor described later. Among them, a conductive polymer doped with sulfonic acid is preferable, and (3,4-ethylenedioxythiophene) poly (styrenesulfonic acid) (PEDOT: PSS) in which a polythiophene derivative is doped with polystyrene sulfonic acid is more preferable. It is. A thin film of metal such as gold, indium, silver or palladium can also be used. A thin film of metal or the like may be formed alone or in combination with the above organic material.

  The film thickness of the hole extraction layer is usually 0.1 nm or more. On the other hand, it is usually 400 nm or less, preferably 200 nm or less. When the film thickness of the hole extraction layer is 0.1 nm or more, it functions as a buffer material. When the film thickness of the hole extraction layer is 400 nm or less, holes are easily extracted, Conversion efficiency can be improved.

There is no restriction | limiting in the formation method of a positive hole taking-out layer. For example, when a material having sublimation property is used, it can be formed by a vacuum deposition method or the like. For example, when a material soluble in a solvent is used, it can be formed by a wet coating method such as a spin coating method or an ink jet method. When a semiconductor material is used for the hole extraction layer, the precursor may be converted into a semiconductor compound after forming the layer using the precursor, similarly to the low-molecular organic semiconductor compound of the active layer.
Especially, when using PEDOT: PSS as a material of a hole taking-out layer, it is preferable to form a hole taking-out layer by the method of apply | coating a dispersion liquid. Examples of the dispersion of PEDOT: PSS include CLEVIOSTM series manufactured by Heraeus, ORGACONTM series manufactured by Agfa, and the like.

  When the hole extraction layer is formed by a coating method, a surfactant may be further contained in the coating solution. By using the surfactant, the occurrence of dents due to adhesion of fine bubbles or foreign matters and / or uneven coating in the drying process is suppressed. Known surfactants (cationic surfactants, anionic surfactants, nonionic surfactants) can be used as the surfactant. Of these, silicon-based surfactants, acetylenic diol-based surfactants, and fluorine-based surfactants are preferable. In addition, as surfactant, only 1 type may be used and 2 or more types may be used together by arbitrary combinations and a ratio.

<4-5. Configuration of other photoelectric conversion elements>
The structure of the photoelectric conversion element according to an embodiment of the present invention may be a photoelectric conversion element having a tandem structure as shown in FIG. 4 in addition to the structure of FIG. Note that a photoelectric conversion element having a tandem structure is a photoelectric conversion element having a structure in which several pn junctions made of the same or different materials are stacked in the light traveling direction. Specifically, the base 106, the lower electrode 101, the lower buffer layer 102, the first active layer 108, the intermediate layer 109, the second active layer 110, the upper buffer layer 104, and the upper electrode 107 were sequentially formed. A structure having a layer structure may be used. The base material 106, the lower electrode 101, the lower buffer layer 102, the upper buffer layer 104, and the upper electrode 106 have the same functions as those described in the constituent layers of the photoelectric conversion element in FIG. It can be formed by film thickness or the like.

  The first active layer 108 and the second active layer 110 contain a p-type semiconductor compound and an n-type semiconductor compound, similarly to the active layer 103 in FIG. 1, and when the photoelectric conversion element 107 receives light, Is absorbed by the active layer 103, electricity is generated at the interface between the p-type semiconductor material and the n-type semiconductor material, and the generated electricity is extracted from the anode and the cathode.

  The layer structure of the first active layer 108 and the second active layer 110 is the same as that of the active layer 103, but is a thin film stacked type in which a p-type semiconductor compound layer and an n-type semiconductor compound layer are stacked, and a p-type semiconductor compound. A bulk heterojunction type, p-type semiconductor compound layer having a layer in which an n-type semiconductor compound is mixed, a layer (i layer) in which a p-type semiconductor compound and an n-type semiconductor compound are mixed, and an n-type semiconductor compound layer are stacked. And the like. Among these, a bulk heterojunction type having a layer in which a p-type semiconductor compound and an n-type semiconductor compound are mixed is preferable.

  The film thicknesses of the first active layer 108 and the second active layer 110 are not particularly limited, but each is usually 10 nm or more, preferably 50 nm or more, while usually 1 μm or less, preferably 500 nm or less, more preferably Is 200 nm or less. It is preferable that the thickness of the active layer 103 is 10 nm or more because the uniformity of the film is maintained and a short circuit is less likely to occur. In addition, the thickness of the active layer 103 being 1 μm or less means that the internal resistance is small, and the electrodes (canode 101-intermediate layer 104, intermediate layer 104-anode 107) are not too far apart and the charge diffusion is good. It is preferable at this point. Note that the film thicknesses of the first active layer 108 and the second active layer 110 may be the same or different from each other.

  The p-type semiconductor compound and the n-type semiconductor compound contained in the first active layer 108 and the second active layer 110 may be the same material, but may be different from each other. Although not limited, the p-type semiconductor compound and the n-type semiconductor compound contained in the first active layer 108 and the second active layer 110 are the p-type semiconductor compound and the n-type semiconductor compound described in the active layer 103 of FIG. Type semiconductor compounds.

  Among these, it is preferable that the first active layer 108 and the second active layer 110 contain p-type semiconductor compounds having different light absorption wavelengths. By using materials with different light absorption wavelengths, photoelectric conversion can be performed efficiently without transmission loss of incident light. In particular, since the copolymer according to the present invention can absorb light on the long wavelength side (600 nm to 1000 nm), it is preferably used in combination with a p-type semiconductor compound that absorbs light on the short wavelength side. Specifically, one of the first active layer 108 and the second active layer 110 includes a copolymer according to the present invention, and the first active layer 108 and the second active layer 110 Of these, the other active layer preferably contains a p-type semiconductor compound having a light absorption wavelength of (300 nm to 700 nm). Specific examples of the p-type semiconductor compound include P3HT and benzoporphyrin, but are not limited thereto.

  Note that a method for forming the first active layer 108 and the second active layer 110 is not particularly limited and can be formed by a method similar to that for the active layer 103.

The intermediate layer 109 includes positive holes generated in the first active layer 108 and electrons generated in the second active layer 110, or electrons generated in the first active layer 108 and positive ions generated in the second active layer 110. It has a function of eliminating pores by recombination. At this time, since the single cells are connected in series by the intermediate layer 109, the release voltage of the tandem is ideally the sum of the release voltages of the single cells. The intermediate layer 109 may be formed of one type of conductive layer, but is usually preferably a multilayer including an electron extraction layer and a hole extraction layer so that no loss occurs in the sum of the release voltages. . Note that the intermediate layer 109 may have a layer structure in which a metal layer or an oxide semiconductor layer is added between the electron extraction layer and the hole extraction layer, but the manufacturing cost increases as the layer configuration increases. For this reason, the intermediate layer composed of two or three layers is preferable, and the intermediate layer composed of two layers is particularly preferable as a layer structure that provides high electrical characteristics and is low in manufacturing cost and BR>. An intermediate layer formed of two layers, an electron extraction layer and a hole extraction layer, is expected to have high electrical characteristics in addition to low manufacturing costs.

  Note that the metal layer and the oxide semiconductor layer that the intermediate layer 109 may have are not particularly limited, but a metal layer such as Ag, Au, or Al or an oxide semiconductor layer such as ITO, IZO, AZO, or GZO is included. Among these, Ag, Au, ITO, and IZO are particularly preferable from the viewpoint of light transmittance. Further, the electron extraction layer and / or hole extraction layer that the intermediate layer 109 may have are the electron extraction layer and / or hole extraction layer described in the items of the lower buffer layer 102 and the upper buffer layer 104 in FIG. Materials that can be used for the layer are mentioned.

  The thickness of the intermediate layer 109 is not particularly limited, but is usually 0.5 nm or more. On the other hand, it is usually 800 nm or less, preferably 400 nm or less. When the film thickness of the intermediate layer 106 is 0.5 nm or more, it functions as a bonding layer material. When the film thickness of the intermediate layer 104 is 800 nm or less, charges can be easily taken out, and light The photoelectric conversion efficiency can be improved by increasing the transmittance.

  The method for forming the intermediate layer 109 is not particularly limited. For example, when a material having sublimation property is used, the intermediate layer 109 can be formed by a dry film formation method such as a vacuum evaporation method. For example, when a material soluble in a solvent is used, the film can be formed by a wet film formation method such as a spin coating method or an ink jet method.

<4.6. Manufacturing method of photoelectric conversion element>
A photoelectric conversion element 107 having the configuration shown in FIG. 1 is formed on a base 106 by a lower electrode 101, a lower buffer layer 102, an active layer 103, an upper buffer layer 104, and an upper electrode in accordance with the method described above for each layer. It can be manufactured by sequentially stacking 105. In the case of manufacturing the photoelectric conversion element having the tandem structure shown in FIG. 2, the lower electrode 101, the lower buffer layer 102, the first active layer 108, the intermediate layer 109, and the second active element are formed on the substrate 106. The layer 110, the upper buffer layer 104, and the upper electrode 105 can be sequentially stacked.

  After laminating the lower electrode 101 and the upper electrode 105, the photoelectric conversion element is usually in a temperature range of 50 ° C. or higher, preferably 80 ° C. or higher, usually 300 ° C. or lower, preferably 280 ° C. or lower, more preferably 250 ° C. or lower. It is preferable to heat (this step is referred to as an annealing treatment step).

Performing the annealing process at a temperature of 50 ° C. or higher improves adhesion between the layers of the photoelectric conversion element, for example, adhesion between the lower buffer layer 102 and the lower electrode 101 and / or the lower buffer layer 102 and the active layer 103. This is preferable because the effect of By improving the adhesion between the layers, the thermal stability and durability of the photoelectric conversion element can be improved. In addition, the self-organization of the active layer can be promoted by the annealing process. It is preferable to set the temperature of the annealing treatment step to 300 ° C. or lower because the possibility that the organic compound in the active layer 103 is thermally decomposed is reduced. In the annealing treatment step, stepwise heating may be performed within the above temperature range.

  The heating time is usually 1 minute or longer, preferably 3 minutes or longer, and usually 3 hours or shorter, preferably 1 hour or shorter. The annealing treatment step is preferably terminated when the open-circuit voltage, the short-circuit current, and the fill factor, which are parameters of the solar cell performance, reach a constant value. Further, the annealing treatment step is preferably performed under normal pressure and in an inert gas atmosphere.

  As a heating method, the photoelectric conversion element may be placed on a heat source such as a hot plate, or the photoelectric conversion element may be placed in a heating atmosphere such as an oven. The heating may be performed batchwise or continuously.

  Although the thermal treatment and durability of the photoelectric conversion element can be improved by the annealing treatment step, the fullerene compound is aggregated during the annealing treatment step and phase separation is promoted, so that the photoelectric conversion efficiency may be lowered. . However, since the active layer 103 contains an additive, aggregation of the fullerene compound during the annealing process is suppressed by the additive. Thus, the photoelectric conversion element 107 with higher photoelectric conversion efficiency after performing an annealing process can be obtained by making the active layer 103 contain an additive.

  Each layer constituting the photoelectric conversion element according to the present invention is not particularly limited, and can be formed by a sheet-to-sheet (manyoba) method or a roll-to-roll method. -It is preferable to form by a two-roll system.

  The roll-to-roll method is a method in which a flexible base material wound in a roll shape is fed out and processed intermittently or continuously until it is taken up by a take-up roll. is there. According to the roll-to-roll method, it is possible to batch-process long substrates on the order of km, so that the production method is more suitable for mass production than the sheet-to-sheet method.

  The size of the roll that can be used in the roll-to-roll method is not particularly limited as long as it can be handled by a roll-to-roll manufacturing apparatus, but the outer diameter is usually 5 m or less, preferably 3 m or less. Preferably, it is 1 m or less, usually 10 cm or more, preferably 20 cm or more, more preferably 30 cm or more. The outer diameter of the roll core is usually 4 m or less, preferably 3 m or less, more preferably 0.5 m or less, usually 1 cm or more, preferably 3 cm or more, more preferably 5 cm or more, still more preferably 10 cm or more, particularly preferably 20 cm or more. When these diameters are not more than the above upper limit, it is preferable in terms of high handleability of the roll, and when it is more than the lower limit, the layer formed in each of the following steps is less likely to be broken by bending stress. Is preferable. The width of the roll is usually 5 cm or more, preferably 10 cm or more, more preferably 20 cm or more, and is usually 5 m or less, preferably 3 m or less, more preferably 2 m or less. When the width is not more than the upper limit, it is preferable from the viewpoint of high handleability of the roll, and when the width is not less than the lower limit, the degree of freedom of the size of the photoelectric conversion element is preferable.

<4-7. Photoelectric conversion characteristics>
The photoelectric conversion characteristics of the photoelectric conversion element 107 can be obtained as follows. The photoelectric conversion element 107 is irradiated with light having an AM 1.5G condition by a solar simulator at an intensity of 100 mW / cm ^2.
And measure the current-voltage characteristics. From the obtained current-voltage curve, photoelectric conversion characteristics such as photoelectric conversion efficiency (PCE), short circuit current density (Jsc), open circuit voltage (Voc), fill factor (FF), series resistance, and shunt resistance can be obtained.

The photoelectric conversion efficiency of the photoelectric conversion element according to the present invention is not particularly limited, but is usually 1% or more, preferably 1.5% or more, more preferably 2% or more. On the other hand, there is no particular limitation on the upper limit, and the higher the better.

Moreover, as a method for measuring the durability of the photoelectric conversion element, a method for obtaining a maintenance ratio of the photoelectric conversion efficiency before and after exposing the photoelectric conversion element to the atmosphere can be mentioned.
(Maintenance rate) = (Photoelectric conversion efficiency after N hours of atmospheric exposure) / (Photoelectric conversion efficiency immediately before atmospheric exposure)

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

<5. Solar cell>
The photoelectric conversion element according to the above-described embodiment is preferably used as a solar cell, particularly a solar cell element of a thin film solar cell. FIG. 2 is a cross-sectional view schematically showing the configuration of a thin-film solar cell as one embodiment of the present invention. As shown in FIG. 2, the thin film solar cell 14 of this embodiment includes a weather-resistant protective film 1, an ultraviolet cut film 2, a gas barrier film 3, a getter material film 4, a sealing material 5, and a photoelectric conversion element. 6, a sealing material 7, a getter material film 8, a gas barrier film 9, and a back sheet 10 are provided in this order. And a thin film solar cell is normally irradiated with light from the side (downward in the figure) in which the weather-resistant protective film 1 was formed, and the photoelectric conversion element 6 generates electric power. Note that the thin-film solar cell does not need to have all of these constituent members, and each constituent member may be arbitrarily selected and provided.

  There are no particular restrictions on these constituent members constituting the thin-film solar cell and the manufacturing method thereof, and well-known techniques can be used. For example, the thing described in well-known literatures, such as international publication 2011/016430 or Unexamined-Japanese-Patent No. 2012-191194, can be used.

  There is no special restriction | limiting in the use of the solar cell which concerns on this invention, especially the thin film solar cell 14 mentioned above, It can use for arbitrary uses. Examples include solar cells for building materials, solar cells for automobiles, solar cells for spacecrafts, solar cells for home appliances, solar cells for mobile phones, solar cells for toys, and the like.

  The solar cell according to the present invention, particularly a thin-film solar cell, may be used as it is, or for example, a solar cell may be installed on a substrate and used as a solar cell module. For example, as shown in FIG. 3, the solar cell module 13 having the thin film solar cell 14 on the base 12 can be installed and used at a place of use. For the substrate 12, a well-known technique can be used, and for example, those described in International Publication No. 2011-016430 or JP 2012-191194 A can be used. For example, when a building material plate is used as the substrate 12, a solar cell panel can be produced as the solar cell module 13 by providing the thin film solar cell 14 on the surface of the plate.

  Hereinafter, embodiments of the present invention will be described by way of examples. However, the present invention is not limited to these examples as long as the gist of the present invention is not exceeded. The items described in the examples were measured by the following methods.

[Method for measuring weight average molecular weight and number average molecular weight]
The polystyrene equivalent weight average molecular weight (Mw) and number average molecular weight (Mn) were determined by gel permeation chromatography (GPC). The molecular weight distribution (PDI) represents Mw / Mn.

Gel permeation chromatography (GPC) measurement was performed under the following conditions.
Column: PolymerLaboratories GPC column (PLgel MIXED-B 10 μm inner diameter 7.5 mm, length 30 cm) used in series connected Pump: LC-10AT (manufactured by Shimadzu Corporation)
Oven: CTO-10A (manufactured by Shimadzu Corporation)
Detector: differential refractive index detector (manufactured by Shimadzu Corporation, RID-10A) and UV-vis detector (manufactured by Shimadzu Corporation, RID-10A) and UV-vis detector (manufactured by Shimadzu Corporation, SPD-10A)
Sample: 1 μL of 1 mg sample dissolved in orthodichlorobenzene (200 mg)
Mobile phase: orthodichlorobenzene
Flow rate: 1.0 mL / min
Analysis: LC-Solution (manufactured by Shimadzu Corporation)

<Synthesis Example 1: Synthesis of Compound E2>

To a 100 mL multi-necked flask, 4.4 g (18 mmol) of 4,5-dichlorophthalic acid (Compound E1) and 0.2 ml of DMF were added. 8.9 g (74 mmol) of thionyl chloride was added to the dropping funnel and slowly added dropwise. Stirring was performed at 60 ° C. in an oil bath. The temperature was raised to 75 ° C., and the reaction was terminated when the system became uniform. The solvent was removed by distillation under reduced pressure to obtain acid chloride (Compound E2).
<Synthesis Example 2: Synthesis of Compound E3>

A 200 mL multi-neck flask was placed in an ice bath under nitrogen, and 4.1 g (37 mL) of mercaptopyridine was added.
mol), 66 mL of tetrahydrofuran and 6.6 mL of triethylamine were added and stirred for 15 minutes. The acid chloride (Compound E2) obtained in Synthesis Example 1 was dissolved in 26 mL of tetrahydrofuran, and the solution was added to the system. Next, 264 mL of 1% hydrochloric acid was added, extracted with chloroform, washed with a 10% aqueous sodium hydroxide solution, further washed with a 1M sodium hydrogen carbonate solution, washed with water, and then dried over sodium sulfate. The solvent was removed by distillation under reduced pressure, ether was added, and the residue was distilled again under reduced pressure to precipitate the desired thioester (compound E3) as 1.3 g of crystals. The chemical shift of compound E3 is as follows.

H1NMR (δ 8.65 (m, 2H), δ 7.98 (s, 2H), 7.73-7.80 (
m, 4H), 7.32 (m, 2H)
<Synthesis Example 3: Synthesis of Compound E4>

Under nitrogen, 3.5 g (8.3 mmol) of a thioester (compound E3) and 42 mL of dehydrated tetrahydrofuran were added to a 300 mL multi-necked flask and stirring was started. It put on the ice bath, 2-7.9nyl magnesium bromide tetrahydro solution 17.9mL (17.9 mmol) was added slowly, and it stirred for 1 hour. After slowly adding 34 mL of 10% hydrochloric acid, the mixture was extracted with ether and dried over sodium sulfate. The solvent was removed by distillation under reduced pressure, ether was added once more, and the precipitated powder was collected by filtration to obtain 2.7 g of the desired compound (Compound E4). The chemical shift of compound E4 is as follows.

H1 NMR (δ 7.83 (s, 2H), δ 7.7 (dd, 2H), δ 7.47 (dd, 2
H), δ 7.1 (dd, 2H)
<Synthesis Example 4: Synthesis of Compound E5>

  To a 500 mL multi-neck flask under nitrogen, 2.7 g (7.3 mmol) of dichloromethane (91 mL) and Lawson reagent 4.2 g (10 mmol) were added and stirred at 60 ° C. for 30 minutes. The solvent was removed by distillation under reduced pressure, 91 mL of ethanol was added, and the mixture was heated to reflux for 30 minutes. 100 mL of water was added, extracted with 200 mL of chloroform and then dried over sodium sulfate. The origin component was removed by silica gel column chromatography, and crystallization was performed with a mixed solvent of chloroform-hexane. 2.4 g of the target compound E5 was obtained. The chemical shift of compound E5 is as follows.

H1NMR (δ 8.04 (s, 2H), δ 7.43 (dd, 2H), δ 7.33 (dd, 2
H), δ 7.18 (dd, 2H))
<Synthesis Example 5: Synthesis of Compound E6>

Under nitrogen, 1.3 g (54 mmol) of magnesium, 1 mg of iodine and 20 mL of dehydrated ether were added to a 100 mL multi-necked flask and stirring was started. A solution of 9.3 mL (54 mmol) of bromooctane in 20 mL of ether was slowly added dropwise. The mixture was heated and stirred for 4 hours to obtain a Grineer reagent. In a separate 500 mL multi-neck flask, under nitrogen, 2.0 g (5.4 mmol) of compound E5, 40 mL of ether, 0.15 g (0) of [1,3-bis (diphenylphosphino) propane] nickel (II) dichloride. .3 mmol) was added, and the previously prepared Grineer reagent was added dropwise and stirred for 5 hours. Quenched with 200 mL of 1% hydrochloric acid, extracted with chloroform and dried over sodium sulfate. The solvent was removed by distillation under reduced pressure, and the residue was purified by silica gel chromatography to obtain 3.2 g (including bromooctane) of orange oil (compound E6). The chemical shift of compound E6 is as follows.

H1NMR (δ 7.7 (s, 2H), δ 7.35 (dd, 2H), δ 7.33 (dd, 2H
), Δ 7.15 (dd, 2H), δ 2.7 (t), δ 1.65 (m), δ 1.3-1.5
(M), δ 0.9 (m))
<Synthesis Example 6: Synthesis of Compound E7>

Under nitrogen, 99 mg (0.2 mmol) of Compound E7 and 25 mL of dehydrated tetrahydrofuran were added to a 100 mL multi-necked flask and stirred. The system was cooled to −65 ° C. in a dry ice bath, and LDA 0.57 mL (0.57 mmol) and trimethyltin chloride 113 mg (0.57 mmol) were slowly added in two portions. Thereafter, it was quenched with water, extracted with chloroform, and dried over magnesium sulfate. The solvent was removed by distillation under reduced pressure, and the residue was purified using GPC to obtain 200 mg of an isothianaphthene derivative (Compound E7).
<Synthesis Example 7: Synthesis of Compound F2>

To a 500 mL eggplant flask, 5.3 g (30.7 mmol) of thiophene dicarboxylic acid and 100 mL of acetic anhydride were added and heated at 140 ° C. for 6 hours. The solvent was removed by distillation under reduced pressure, and recrystallization was performed with Torun to obtain 3.5 g of 1H, 3H-thieno [3,4-c] furan-1,3-dione (Compound F2).
<Synthesis Example 8: Synthesis of Compound F3>

Under nitrogen, 3.57 g (0.023 mol) of 1H, 3H-thieno [3,4-c] furan-1,3-dione (Compound F2) was dissolved in 35 mL of dehydrated DMF in a 100 mL eggplant flask. Then, 4.2 mL (0.025 mol) of n-octylamine was added in an ice bath and heated at 140 ° C. for 2 hours. The mixture was allowed to cool and then mixed with water, and the precipitated skin-colored powder was collected by filtration and washed with cold methanol to obtain 5.3 g of 4-[[1-octylamino] carbonyl] -3-thienophenecarboxylic acid (Compound F3). .
<Synthesis Example 9: Synthesis of Compound F4>

4-[[1-octylamino] carbonyl] -3-thienophenecarboxylic acid (Compound E3) (5.27 g, 18.6 mmol) and thionyl chloride (18 mL) are added to a 100 mL eggplant flask and the bath temperature is set to 72 ° C. and heated for 3 hours. did. After allowing to cool, the mixture was added dropwise to a 1N aqueous sodium hydroxide solution, and the precipitated brown powder was collected by filtration. Washing with cold methanol and drying gave 4.55 g of 5-octyl-4H-thieno [3,4-c] pyrrole-4,6 (5H) -dione (compound F4) (91% yield). .
<Synthesis Example 10: Synthesis of Compound F5>

  In a 200 mL eggplant flask under nitrogen, 2.65 g (10 mmol) of 5-octyl-4H-thieno [3,4-c] pyrrole-4,6 (5H) -dione (Compound F4) was added to 50 mL of trifluoroacetic acid, concentrated. Dissolved in 15 mL of sulfuric acid. The mixture was further stirred in an ice bath until 5.33 g (30 mmol) of NBS was dissolved. After quenching by mixing with ice water, extraction was performed using chloroform, the solvent was removed by distillation under reduced pressure, and the residue was purified by column chromatography (developing solvent hexane: chloroform 2: 1 → 1: 1). After suspension washing with hexane, an imidothiophene derivative (1,3-dibromo-5-octyl-4H-thieno [3,4-c] pyrrole-4,6- (5H) -dione) (compound F5) was obtained. 2.58 g was obtained (yield 61%).

<Synthesis Example 11: Synthesis of Copolymer 1>

  In a 50 mL two-necked eggplant flask under a nitrogen atmosphere, the isothianaphthene derivative obtained in Synthesis Example 6 (Compound E7, 0.06 g, 0.08 mmol) and the imidothiophene derivative obtained in Synthesis Example 10 (Compound F5, 0 .03 g, 0.07 mmol), and tetrakistriphenylphosphine palladium 4.2 mg (0.004 mmol), toluene 1.3 mL, DMF 0.3 mL, and CEM microwave focused chemical synthesis system. The polymerization reaction was carried out at 80 ° C. for 2 minutes, 130 ° C. for 2 minutes, 170 ° C. for 2 minutes, and 200 ° C. for 50 minutes. The reaction solution was diluted 4-fold with toluene as a terminal treatment, trimethyl (phenyl) tin (0.1 mL) was added, and the end cap was 80 ° C. for 2 minutes, 130 ° C. for 2 minutes, 170 ° C. for 2 minutes, Stir at 200 ° C. for 20 minutes, add bromobenzene (0.1 mL) and stir at 80 ° C. for 2 minutes, 130 ° C. for 2 minutes, 170 ° C. for 2 minutes, and 200 ° C. for 20 minutes. The mixture was poured into methanol, and the deposited precipitate was collected by filtration. The obtained solid was dissolved in chloroform, added to methanol, and the deposited precipitate was separated by filtration to obtain the target copolymer 1 (20 mg). The obtained copolymer 1 was dissolved in chloroform, and the melted polymer had a weight average molecular weight Mw of 2800 and a PDI of 1.4.

<Example 1: Measurement of absorption wavelength of copolymer>
The absorption wavelength of the copolymer 1 obtained in Synthesis Example 11 was measured. In addition, the absorption wavelength measurement was implemented using the spectrophotometer (the Hitachi make, U-3500). Specifically, a toluene solution of copolymer 1 was prepared, and using a 1 cm square quartz cell, 400 nm to 1000 n
Measurements were made in the range of m. The obtained results are shown in FIG.

  A copolymer containing a benzene ring which is a six-membered ring in the main chain described in a known document (Macromolecular Rapid Communications (2007), 28 (17), 1786-1791) loses linearity and weakly absorbs at a long wavelength. The absorption edge is about 820 nm. On the other hand, as shown in FIG. 5, the copolymer according to the present invention has a high linearity because the main chain is composed of a five-membered ring, and its absorption edge is about 1000 nm, and a longer wavelength is achieved. Yes. Therefore, the copolymer according to the present invention can absorb light on the long wavelength side, and an improvement in conversion efficiency is expected. It is also promising as a long wavelength side material in a tandem solar cell element.

DESCRIPTION OF SYMBOLS 101 Lower electrode 102 Lower buffer layer 103 Active layer 104 Upper buffer layer 105 Upper electrode 106 Base material 107 Photoelectric conversion element 108 First active layer 109 Intermediate layer 110 Second active layer 1 Weatherproof protective film 2 UV cut film 3, 9 Gas barrier films 4, 8 Getter material films 5, 7 Sealing material 6 Solar cell element 10 Back sheet 12 Base material 13 Solar cell module 14 Thin film solar cell

Claims (6)

Copolymer having a structural unit represented by the following formula (1)

(In formula (1), R ^{1 to} R ⁶ are each independently a hydrogen atom or a monovalent organic group, or R ¹ and R ² , R ³ and R ⁴ , R ⁵ and R ⁶ are Each may be bonded to each other to form a ring, X represents a divalent atom or a divalent group, and ring Y has an aliphatic hydrocarbon ring which may have a substituent, or a substituent. An aromatic hydrocarbon ring which may be substituted, an aliphatic heterocyclic ring which may have a substituent, or an aromatic heterocyclic ring which may have a substituent. In the formula (1), X represents O, S, Se, N (R ⁷ ), C (R ⁸ ) (R ⁹ ), or Si (R ¹⁰ ) (R ¹¹ ), and R ^{7 to} R ¹¹ are The copolymer according to claim 1, which is independently a hydrogen atom or a monovalent organic group. The copolymer according to claim 1 or 2, wherein in the formula (1), R ^{1 to} R ⁶ are each independently a hydrogen atom or an aliphatic hydrocarbon group which may have a substituent.   It is a photoelectric conversion element which has a pair of electrode and an active layer between said pair of electrodes on a base material, Comprising: The said active layer is a copolymer of any one of Claims 1-3. A photoelectric conversion element comprising:   The solar cell which has a photoelectric conversion element of Claim 4.   A solar cell module comprising the solar cell according to claim 5.

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