JP2011246503A - Novel polymer and intermediate thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel polymer having excellent charge transport ability useful as a photoelectric conversion element or a charge transport material of a solar cell, an intermediate thereof, and a photoelectric conversion element and a solar cell using the novel polymer.SOLUTION: The polymer has a structural unit represented by formula (1), wherein Rand Rare each independently a hydrogen atom etc., and Ris thiophene.

Description

  The present invention relates to a novel polymer, an intermediate thereof, and a photoelectric conversion element and a solar cell using the novel polymer.

  A photoelectric conversion material is a material that can convert light energy into electrical energy using the photoelectric effect. In photoelectric conversion materials, when light is irradiated, electrons bound to atoms in the material can move freely by light energy, and free electrons and free electron holes (holes) are generated. Thus, these free electrons and holes are efficiently separated, and electric energy can be continuously taken out.

  Photoelectric conversion materials are applied to various uses by utilizing such characteristics, and one of them is a solar cell. Examples of such a solar cell include a dye-sensitized solar cell and a solid solar cell using a conductive polymer for the purpose of manufacturing at low cost.

  A dye-sensitized solar cell is mainly composed of, for example, a semiconductor electrode and a counter electrode on which a dye is adsorbed, and an electrolyte layer sandwiched between these electrodes. When the semiconductor electrode is irradiated with light, the electrode side The generated electrons move to the counter electrode through the electric circuit, and the electrons moved to the counter electrode move as ions in the electrolyte and return to the semiconductor electrode, which can be repeated to extract electric energy. Is.

  However, the semiconductor used in this dye-sensitized solar cell uses a photo-oxidation catalyst such as titanium oxide, and the electrolyte is mainly used as the electrolyte that is decomposed or used together. Therefore, there is a problem that the electrolytic solution cannot be sufficiently retained, and the electrolytic solution leaks or volatilizes from the gap between the working electrode and the counter electrode. Moreover, there is a problem that the apparatus configuration is complicated in order to prevent leakage of the electrolytic solution.

  On the other hand, as solid-state solar cells using conductive polymers, for example, photoelectric conversion elements using specific heterocyclic polymers and fullerene derivatives as charge transport materials have been reported (Patent Documents 1 and 2).

JP 2005-116617 A JP 2006-278682 A

In recent years, development of a polymer more useful as a charge transport material for photoelectric conversion elements and solar cells has been desired.
Therefore, this invention makes it a subject to provide the novel polymer useful as a charge transport material of a photoelectric conversion element or a solar cell, its intermediate body, and the photoelectric conversion element and solar cell using the said novel polymer.

  Therefore, as a result of intensive studies to solve the above problems, the present inventors have obtained a benzodithiophene derivative having an ether bond at the 4-position and the 8-position, and a thiophene derivative or thienothiophene derivative into which a specific substituent has been introduced. The present inventors have found that a novel polymer having a structure in which is bonded as a repeating unit is useful as a charge transport material for a photoelectric conversion element and a solar cell, and has completed the present invention.

  That is, 1) The present invention provides the following formula (1)

[In Formula (1), R < ¹ > and R < ² > show a hydrogen atom or a substituted or unsubstituted C1-C20 hydrocarbon group each independently, and R < ³ > is following formula (2).

(In formula (2), R ⁴ represents a hydrogen atom, a cyano group, a substituted or unsubstituted alkoxycarbonyl group having 2 to 20 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, or a substituted or non-substituted group. A substituted C1-C30 hydrocarbon group is shown, R < ⁵ > shows a hydrogen atom or a substituted or unsubstituted C1-C30 hydrocarbon group, and * shows a bond.)
Or a group represented by the following formula (3)

(In the formula (3), R ⁴ , R ⁵ and * are as defined above.)
The group represented by these is shown. ]
The polymer (henceforth a polymer (1)) which has a structural unit represented by these is provided.

  Moreover, 2) this invention provides the photoelectric conversion element characterized by having a solid layer containing a polymer (1) between a pair of electrodes.

  Furthermore, 3) the present invention provides the following formula (10)

(In the formula (10), R ⁶ and R ⁷ each independently represent a hydrogen atom or a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms, R ¹ and R ² are as defined above. )
And a compound represented by the following formula (8)

(In formula (8), X ¹ and X ² each independently represent a halogen atom, and R ⁴ and R ⁵ are as defined above.)
Or a compound represented by the following formula (9):

(In formula (9), R ⁴ , R ⁵ , X ¹ and X ² are as defined above.)
The manufacturing method of the polymer of Claim 1 or 2 including the process with which the compound (henceforth a compound (9)) represented by these is made to react is provided.

  Furthermore, 4) this invention provides a compound (8).

  Furthermore, 5) this invention provides a compound (9).

  The polymer of the present invention absorbs a wide range of light and has charge transport ability and excellent thermal stability. Therefore, the polymer of the present invention is useful as a charge transport material for photoelectric conversion elements and solar cells.

It is sectional drawing which shows typically an example of the photoelectric conversion element of this invention. ¹ is a diagram showing a ¹ H-NMR spectrum of compound 10. FIG. It is a figure which shows the < ¹ > H-NMR spectrum of the polymer P1. ¹ is a diagram showing a ¹ H-NMR spectrum of compound 14. FIG. It is a figure which shows the < ¹ > H-NMR spectrum of the polymer P2. ¹ is a diagram showing a ¹ H-NMR spectrum of compound 25. FIG. 2 is a diagram showing a ¹ H-NMR spectrum of compound 26. FIG. 3 is a diagram showing a ¹ H-NMR spectrum of compound 28. FIG. It is a figure which shows the < ¹ > H-NMR spectrum of the polymer P3. It is a figure which shows the UV-vis spectrum of the polymer P1. It is a figure which shows the UV-vis spectrum of the polymer P2. It is a figure which shows the UV-vis spectrum of the polymer P3. It is a figure which shows the TGA curve of the polymer P1. It is a figure which shows the TGA curve of the polymer P2. It is a figure which shows the TGA curve of the polymer P3. It is a figure which shows the IV curve of the device using the polymer P2.

First, definitions of symbols used in this specification will be described.
R ¹ and R ² each independently represent a hydrogen atom or a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms. Among these, a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms is preferable from the viewpoints of charge transport ability, thermal stability, light absorption, solubility, and compatibility. The “hydrocarbon group” is a concept including an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group, but has a charge transporting ability, thermal stability, light absorption, solubility, and phase. From the viewpoint of solubility, an aliphatic hydrocarbon group is preferred. Note that the hydrocarbon group may have an unsaturated bond in the molecule.

  The aliphatic hydrocarbon group has 1 to 20 carbon atoms, preferably 3 to 18 and more preferably 4 to 16 in terms of charge transportability, thermal stability, light absorption, solubility, and compatibility. 5 to 12 is preferable and particularly preferable. The aliphatic hydrocarbon group may be linear or branched. Specific examples include an alkyl group, an alkenyl group, and an alkynyl group, and an alkyl group is preferable from the viewpoint of charge transport ability, thermal stability, light absorption, solubility, and compatibility. Specifically, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, n-hexyl group, n-heptyl group Group, n-octyl group, 2-ethylhexyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-hexadecyl group, etc. Can be mentioned. Among these, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group and n-decyl group are preferable.

  Examples of the group that can be substituted with the “hydrocarbon group having 1 to 20 carbon atoms” include alkoxy groups having 1 to 12 carbon atoms such as a methoxy group, an ethoxy group, a propoxy group, a butoxy group, and a cyclohexyloxy group; Halogen atoms such as fluorine atom, chlorine atom, bromine atom, iodine atom; cyano group; amino group; oxo group; alkanoyl group having 2 to 10 carbon atoms such as tert-butylcarbonyl group; methoxycarbonyl group, ethoxycarbonyl group, etc. An alkoxycarbonyl group etc. are mentioned. The position and number of these substituents are arbitrary, and when having two or more substituents, the substituents may be the same or different.

R ³ represents the following formula (2)

(In formula (2), R ⁴ represents a hydrogen atom, a cyano group, a substituted or unsubstituted alkoxycarbonyl group having 2 to 20 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, or a substituted or non-substituted group. A substituted C1-C30 hydrocarbon group is shown, R < ⁵ > shows a hydrogen atom or a substituted or unsubstituted C1-C30 hydrocarbon group, and * shows a bond.)
Or a group represented by the following formula (3)

(In the formula (3), R ⁴ , R ⁵ and * are as defined above.)
The group represented by these is shown.

  In addition, as group represented by the said Formula (3), from the point of thermal stability and light absorption, following formula (4)

(In the formula (4), R ⁴ , R ⁵ and * are as defined above.)
The group represented by these is preferable.

R ⁴ is a hydrogen atom, a cyano group, a substituted or unsubstituted alkoxycarbonyl group having 2 to 20 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, or a substituted or unsubstituted carbon group having 1 to 30 carbon atoms. Represents a hydrocarbon group. Among these, from the viewpoint of charge transportability, thermal stability, light absorption, solubility, and compatibility, a cyano group, a substituted or unsubstituted alkoxycarbonyl group having 2 to 20 carbon atoms is preferable, and a substituted or unsubstituted carbon number. 2-20 alkoxycarbonyl groups are more preferred. The alkoxycarbonyl group has 2 to 20 carbon atoms, preferably 3 to 16, more preferably 4 to 14 from the viewpoint of charge transport ability, thermal stability, light absorption, solubility, and compatibility. 5 to 12 is particularly preferable. In addition, the alkyl group part in the alkoxycarbonyl group may be linear, branched, or cyclic.
Specifically, methoxycarbonyl group, ethoxycarbonyl group, n-propoxycarbonyl group, isopropoxycarbonyl group, n-butoxycarbonyl group, isobutoxycarbonyl group, sec-butoxycarbonyl group, tert-butoxycarbonyl group, n-pentyl Examples thereof include an oxycarbonyl group, an n-hexyloxycarbonyl group, an n-heptyloxycarbonyl group, and an n-octyloxycarbonyl group. Among these, an n-pentyloxycarbonyl group, an n-hexyloxycarbonyl group, an n-heptyloxycarbonyl group, and an n-octyloxycarbonyl group are preferable.

R ⁵ represents a hydrogen atom or a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms, but is substituted or non-substituted from the viewpoint of charge transport ability, thermal stability, light absorption, solubility, and compatibility. A substituted hydrocarbon group having 1 to 30 carbon atoms is preferred. Examples of the “hydrocarbon group” include those similar to R ¹ , but an aliphatic hydrocarbon group is preferable. Moreover, although carbon number of an aliphatic hydrocarbon group is 1-30, 1-26 are preferable from the point of charge transport ability, thermal stability, light absorption, solubility, and compatibility, and 3-20 are. More preferably, 4-16 are still more preferable, and 5-14 are especially preferable. Among these, 5 to 10 is particularly preferable.

In R ⁴ and R ⁵ , the group that can be substituted with an alkoxycarbonyl group having 2 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, and a hydrocarbon group having 1 to 30 carbon atoms is the same as R ¹ . Things.

The combination of R ³ , R ⁴ and R ⁵ includes the following (i) to (iii) from the viewpoint of charge transport ability, thermal stability, light absorption, solubility, and compatibility.
(I) A combination in which R ³ is a group represented by formula (2), R ⁴ is a cyano group, and R ⁵ is a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms;
(Ii) R ³ is a group represented by the formula (2), R ⁴ is a substituted or unsubstituted alkoxycarbonyl group having 2 to 20 carbon atoms, and R ⁵ is a substituted or unsubstituted carbon number 1 to 1. A combination which is 30 hydrocarbon groups;
(Iii) A combination in which R ³ is a group represented by formula (3), R ⁴ is a cyano group, and R ⁵ is a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms;
The combination of is preferable.
Among them, R ³ is a group represented by the formula (2), R ⁴ is a substituted or unsubstituted alkoxycarbonyl group having 2 to 20 carbon atoms, and R ⁵ is a substituted or unsubstituted carbon number of 1 to 30. A combination of the following hydrocarbon groups is particularly preferred.

Next, the manufacturing method of this invention is demonstrated.
The polymer (1) of the present invention can be produced according to the following reaction. That is, the compound represented by the following formula (5) is reacted with the thiophene carbaldehyde derivative represented by the formula (6) or the thienothiophene carbaldehyde derivative represented by the formula (7) to obtain the compound (8) or (9) is obtained (Step 1), and the compound (8) or (9) and the benzodithiophene derivative represented by the formula (10) are Still coupled in the presence of a transition metal catalyst ( Step 2), the polymer (1) can be produced. In addition, in the manufacturing method of this invention, the said compounds (5)-(7) may be used independently, and 2 or more types may be mixed and used for them.

Wherein R ⁶ and R ⁷ each independently represent a hydrogen atom or a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms, X ¹ and X ² each independently represent a halogen atom, and R ^{1 to} R ⁵ are as defined above.)

Examples of R ⁶ and R ⁷ include the same as R ¹ described above. In addition, although carbon number of the hydrocarbon group in R < ⁶ > and R < ⁷ > is 1-20, 1-10 are preferable from the point of reaction efficiency, 1-6 are more preferable, and 1-4 are especially preferable. Preferable specific examples include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group and n-hexyl group. A methyl group is particularly preferred.
Examples of X ¹ and X ² include a bromine atom, a chlorine atom, an iodine atom, and a fluorine atom. Among these, from the viewpoint of reaction efficiency, a bromine atom and an iodine atom are preferable, and a bromine atom is particularly preferable.

Hereinafter, step 1 will be described.
In step 1, the amount of compound (6) or (7) used is preferably about 0.5 to 2 molar equivalents relative to compound (5).

Step 1 can be performed in the presence or absence of a catalyst, but is preferably performed in the presence of a catalyst. Examples of the catalyst include bases such as piperidine, triphenylphosphine, and ethylenediamine. Of these, piperidine is preferable from the viewpoint of reaction efficiency. Although the usage-amount of a catalyst is about 1 * 10 < ^-8 > -0.1mL with respect to 1 mg of compounds (5), 0.0001-0.1mL is preferable.

In addition, this step can be performed in the presence or absence of a solvent, but is preferably performed in the presence of a solvent. The solvent is preferably an alcohol solvent such as ethanol, 1-butanol or 1-propanol; an aromatic hydrocarbon such as toluene, benzene or xylene; a nitrile solvent such as acetonitrile; or a mixed solvent thereof. . Of these, ethanol, toluene, and acetonitrile are particularly preferable. Although the usage-amount of a solvent is about 1 * 10 < ^-5 > -0.1mL with respect to 1 mg of compounds (5), 0.0001-0.1mL is preferable.

  As reaction time of the process 1, 30 minutes-48 hours are preferable. The reaction temperature is preferably room temperature to 200 ° C.

  In addition, the compounds (8) and (9) obtained by the said process 1 are novel compounds.

  In addition, the production methods of the compounds (6) and (7) will be described by taking the compound (7) as an example. That is, compound (11) can be produced by oxidizing compound (11) with an oxidizing agent such as pyridinium dichromate to obtain compound (12) and then halogenating with a halogenating agent such as NBS.

(In the formula, X ¹ and X ² are as defined above.)

Hereinafter, step 2 will be described.
In step 2, the amount of compound (8) or (9) used is preferably about 0.8 to 1.5 molar equivalents relative to compound (10).
Moreover, as a transition metal catalyst used for this process, palladium, a palladium compound, nickel, a nickel compound, cobalt, a cobalt compound, iron, and an iron compound are mentioned. Of these, palladium and palladium compounds are preferred.
Examples of the palladium compound include palladium chloride, palladium bromide, palladium oxide, palladium sulfide, palladium disulfide, palladium dichloride, palladium ditelluride, palladium hydroxide (II), palladium selenide, Pd (PPh ₃ ). ₄ , Pd (PhCN) ₂ Cl ₂ , PdCl ₂ [PPh ₃ ] ₂ , PdCl ₂ (CH ₃ CN) ₂ , [Pd (CH ₃ CN) ₄ ] [BF ₄ ] ₂ , [Pd (C ₂ H ₅ CN ) ₄ ] [BF ₄ ] ₂ , palladium acetylacetonate, palladium acetate and the like. Among these, Pd (PPh ₃ ) ₄ is particularly preferable from the viewpoint of reaction efficiency. Moreover, the usage-amount of a transition metal catalyst has a preferable 0.001-1 molar equivalent with respect to a compound (10).

Step 2 can be performed in the presence or absence of a solvent, but is preferably performed in the presence of a solvent. Examples of the solvent include aromatic hydrocarbons such as toluene, benzene, and xylene; amide solvents such as dimethylformamide and dimethylacetamide; ether solvents such as THF; and mixed solvents thereof. The usage-amount of a solvent is about 0.0001-0.1mL with respect to 1 mg of compounds (10).
As reaction time of the process 2, 30 minutes-12 hours are preferable. As reaction temperature, 30-250 degreeC is preferable and 30-150 degreeC is more preferable.

  The step 2 is preferably performed in an inert gas atmosphere from the viewpoint of smooth still coupling promotion. The inert gas is not particularly limited, and examples thereof include argon gas, nitrogen gas, and helium gas.

In the above steps 1 and 2, each reaction product is subjected to usual means such as filtration, washing, drying, recrystallization, concentration, reprecipitation, centrifugation, extraction with various solvents, neutralization, chromatography and the like as necessary. Can be separated from the reaction system by appropriate combination and isolation and purification. In addition, the compound obtained in Step 1 can be subjected to the next reaction without isolation.
The polymer (1) obtained by the Stille coupling is a novel conjugated polymer and can be produced simply and efficiently. In addition, as shown in the following examples, the polymer (1) absorbs a wide range of light, and has excellent charge transport ability and excellent thermal stability. Therefore, the polymer (1) is useful as a charge transport material for photoelectric conversion elements such as photoelectric conversion elements, solar cells, and optical switching devices and sensors.

Further, the weight average molecular weight (Mw) of the polymer (1) is preferably 2 × 10 ^{4 to} 5 × 10 ^5, more preferably 3 × 10 ^{4 to} 45 × 10 ⁴ , and 4 × 10 ⁴ to 4 × 10. ⁵ is particularly preferred. Moreover, as Mw / Mn, 1-4 are preferable and 1.2-3.5 are more preferable.

Hereinafter, the photoelectric conversion element of the present invention will be described.
In the present invention, examples of the “photoelectric conversion element” include an element that converts electric energy into light and an element that converts light into electric energy, and an element that converts light into electric energy is preferable. In addition, the photoelectric conversion element is a photoelectric conversion element having a pair of electrodes, and a photoelectric conversion element having a working electrode and a counter electrode that forms a pair with the working electrode is preferable, and the working electrode and the counter electrode that forms a pair with the working electrode. And a photoelectric conversion element having a solid layer is more preferable, and a photoelectric conversion element having a working electrode and a counter electrode paired with the working electrode and having a solid layer between the working electrode and the counter electrode is particularly preferable. The solid layer containing the polymer of the present invention is preferably a charge transport layer, and more preferably a photoelectric conversion layer.

In the photoelectric conversion element of the present invention, the solid layer contains the polymer (1). 20-60 mass% is preferable with respect to the whole solid layer, as for content of the said polymer (1), 25-55 mass% is more preferable, and 30-50 mass% is especially preferable.
In addition, the solid layer preferably contains fullerene, a fullerene derivative, a carbon nanotube, or the like from the viewpoint of photoelectric conversion efficiency. Among them, it is particularly preferable to include a fullerene derivative.
The fullerene is preferably C60 fullerene, C70 fullerene or a mixture thereof from the viewpoint of stability and safety.
The fullerene derivative refers to a substance having a charge transport property and having various functional groups introduced into fullerene, and a C60 fullerene derivative and a C70 fullerene derivative are preferable. In addition, you may use these 1 type or 2 types. The functional group to be introduced is preferably an ester group, an imino group, an alkyl group, an aralkyl group, or a thiophenyl group from the viewpoint of optimization of solubility and energy level. The functional group may further have a substituent such as a phenyl group or an alkoxycarbonyl group.

Specific examples of the fullerene derivative include [6,6] phenyl C61 butyric acid hexyl ester.
When the fullerene or fullerene derivative is contained, the content of the fullerene or fullerene derivative is preferably 40 to 80% by mass, more preferably 45 to 80% by mass, and particularly preferably 50 to 80% by mass with respect to the entire solid layer. . Moreover, when fullerene or a fullerene derivative is contained, the content ratio of the polymer (1) and the fullerene or fullerene derivative is 0.25 to 1 with respect to 1 part by mass of the fullerene or fullerene derivative. It is preferable to contain 2 mass parts, and it is especially preferable to contain 0.25-1 mass parts.
In addition, the said fullerene derivative can be manufactured by well-known methods, such as addition reaction, substitution reaction, radical reaction, and cycloaddition reaction.

  The solid layer may contain an additive such as 1,8-diiodooctane.

  In addition, as thickness of a solid layer, 0.1-5000 nm is preferable, 1-1000 nm is more preferable, and 1-500 nm is especially preferable. Moreover, the film forming method of the solid layer is not particularly limited, but it is preferable to form the film at a rotation of about 1000 to 5000 rpm with a spin coater.

The working electrode preferably has a transparent film and a light transmissive conductive layer. The transparent film may be a glass substrate or the like, and as the light transmissive conductive layer, for example, a transparent conductive film such as ITO, tin oxide, or zinc oxide is preferable.
The counter electrode is preferably an aluminum electrode.

  The photoelectric conversion element of the present invention has a donor buffer layer containing poly (3,4-ethylenedioxythiophene) -poly (styrene sulfonate) or the like between the working electrode and the solid layer. Alternatively, an electronic buffer layer containing lithium fluoride or the like may be provided between the counter electrode and the solid layer.

  As shown in the following examples, the photoelectric conversion element of the present invention has excellent photoelectric conversion efficiency and durability. Therefore, the photoelectric conversion element of the present invention is useful as a raw material for photovoltaic devices such as solar cells, optical switching devices, and sensors.

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

Reference Example 1 Synthesis of benzodithiophene derivative (1)
According to the following synthesis route, using 3-thiophenecarboxylic acid (compound 1) as a raw material, 2,6-bis (trimethylstannyl) -4,8-bis (2-ethylhexyloxy) benzo [1,2-b: 4 , 5-b '] dithiophene (compound 13) was synthesized.

1) Synthesis of thiophene-3-carboxylic acid chloride (compound 2) To a solution of compound 1 (5.00 g, 39.0 mmol) and dichloromethane (10 mL) was added oxalyl chloride (9.9 g, 78.0 mmol) at 0 ° C. After stirring at room temperature for 18 hours, the solvent was distilled off under reduced pressure to obtain Compound 2 as a white solid. The obtained compound 2 was used in the next reaction without purification.

2) Synthesis of thiophene-3-carboxylic acid diethylamine (compound 3)
At 0 ° C., compound 2 obtained by the above reaction was mixed with 12 mL of dichloromethane, and this solution was added to a solution of diethylamine (5.7 g, 78.0 mmol) and dichloromethane (12 mL). Then, the mixed solution was stirred at room temperature for 1 hour and then poured into dichloromethane (100 mL). After washing this with water (50 mL) three times, the organic phase was separated and dried over magnesium sulfate. After the solvent was distilled off, the residue was purified by distillation to obtain colorless oily compound 3 (4.9 g) in a yield of 69%.

3) Synthesis of benzo [1,2-b: 4,5-b '] dithiophene-4,8-dione (compound 4) Compound 3 (4.05 g, 22.10 mmol) and THF (20 mL) were mixed together. N-BuLi (14.1 mL, 23.2 mmol) (1.65 M hexane solution) was added to the solution at 0 ° C. The temperature was raised and the mixture was stirred at room temperature for 30 minutes and then poured into ice water. The obtained solid product was filtered and washed with water, methanol and hexane to obtain yellow solid compound 4 (1.93 g) in a yield of 79%.

4) Synthesis of 2-ethylhexyl p-toluenesulfonate (compound 5)
To a solution of 2-ethyl-1-hexanol (5.69 g, 43.7 mmol) and pyridine (50 mL) was added p-toluenesulfonyl chloride (10.0 g, 52.5 mmol) at 0 ° C. The mixture was stirred at room temperature for 3 hours, poured into water (300 mL) and extracted with ethyl ether. After drying the organic phase with magnesium sulfate, the solution was distilled off. The oily residue was purified by silica gel column chromatography (hexane: diethyl ether = 1: 1) to obtain colorless oily compound 5 (10.5 g) in a yield of 84%.

5) Synthesis of 4,8-bis (2-ethylhexyloxy) benzo [1,2-b: 4,5-b '] dithiophene (Compound 6) Compound 4 (2.00 g, 9.08 mmol) and zinc powder (1.31 g , 19.98 mmol) was added ethanol (8 mL) and 20% aqueous sodium hydroxide (30 mL). After refluxing for 2 hours, Compound 5 (8.01 g, 28.15 mmol) was added, and the mixture was further refluxed for 14 hours. The temperature was lowered and insoluble matters were removed by filtration.
The filtrate was diluted with water (150 mL) and extracted three times with chloroform (50 mL). After drying this organic phase with magnesium sulfate, the solvent was distilled off and the residue was purified by silica gel column chromatography (chloroform: hexane = 1: 5) to give colorless oily compound 6 (1.72 g) in a yield of 42%. Obtained.

6) Synthesis of 2,6-bis (trimethylstannyl) -4,8-bis (2-ethylhexyloxy) benzo [1,2-b: 4,5-b '] dithiophene (Compound 13) Compound 6 (1.50 g, 3.36 mmol) and THF (30 mL) were added n-BuLi (3.5 mL, 8.39 mmol) (1.57 M hexane solution) at -80 ° C. The mixture was stirred at -80 ° C for 30 minutes and then stirred at room temperature for 30 minutes. The temperature was lowered again to −80 ° C. and dissolved in THF (5 mL). Chlorotrimethyltin (2.01 g, 10.09 mmol) was added. After stirring for 18 hours at room temperature, water was added. Extracted with hexane and the organic phase was dried over magnesium sulfate. After the solvent was distilled off, the obtained solid was recrystallized from isopropanol to obtain colorless solid compound 13 (1.52 g) in 59% yield.

<Example 1> Synthesis of 2-cyano-3- (2,5-dibromothiophen-3-yl) dodecyl acrylate (dihalothiophene ester derivative) According to the following synthesis route, using cyanoacetic acid (compound 7) as a raw material , Dodecyl 2-cyano-3- (2,5-dibromothiophen-3-yl) acrylate (compound 10) was synthesized.

1) Synthesis of dodecyl cyanoacetate (compound 8) Sulfuric acid (0.1 mL) was added to a mixture of cyanoacetic acid (compound 7, 5 g, 58.78 mmol), toluene (70 mL) and n-dodecanol (10.95 g, 58.78 mmol). The mixture was refluxed for 24 hours while removing water using a Dean-Stark apparatus. After the solvent was distilled off, purification by silica gel column chromatography (ethyl acetate: hexane = 4: 1) gave colorless liquid compound 8 (10.5 g) in a yield of 71%.

2) Synthesis of dodecyl 2-cyano-3- (2,5-dibromothiophen-3-yl) acrylate (Compound 10)
2,5-dibromo-3-thiophenecarbaldehyde (compound 9, 1 g, 3.7 mmol), dodecyl cyanoacetate (compound 8, 0.95 g, 3.7 mmol), piperidine (5 μL) and ethanol (10 mL) After the mixture was refluxed for 1 hour, the temperature was lowered to room temperature, and the precipitated solid was filtered. The obtained solid was washed with cold methanol to obtain Compound 10 (1.37 g) as a yellow solid in a yield of 73%. The ¹ H-NMR (400 MHz, CDCl ₃ ) measurement result of the obtained compound 10 is shown below (FIG. 2).

¹ H-NMR (CDCl ₃ ): δ (ppm) 0.88 (t, J = 6.8 Hz, -CH ₃ , 3H), 1.26-1.43 (m, -CH _2- , 12H), 1.72-1.80 (m,- CH _2- , 2H), 4.32 (t, J = 6.8 Hz, -OCH _2- , 2H), 8.02 (s, th-H, 1H), 8.16 (s,> C = CH-, 1H)

Example 2 Synthesis of Polymer P1 Polymer P1 was synthesized from compound 13 as a raw material according to the following synthesis route.

Compound 13 (386 mg, 0.50 mmol), Compound 10 (253 mg, 0.50 mmol) and Pd (PPh ₃ ) ₄ (25 mg, 0.016 mmol) were mixed, and the mixture was dried in vacuo for 10 minutes. (8 mL) and N, N-dimethylformamide (DMF, 2 mL) were added. Next, this mixed solution was bubbled with argon gas for 10 minutes, and then stirred at 120 ° C. for 7 hours under an argon atmosphere. Thereafter, the temperature was returned to room temperature, reprecipitated with hexane, and the precipitate was filtered. The obtained solid was dissolved in THF and purified by column chromatography (PSQ100B, THF). The organic solvent was distilled off, hexane (400 mL) was added, and the resulting solid was filtered with a membrane to obtain a brown solid polymer P1 (0.30 g) in a 75% yield. The ¹ H-NMR (400 MHz, CDCl ₃ ) measurement result of the obtained polymer P1 is shown below (FIG. 3).

¹ H-NMR (CDCl ₃ ): δ (ppm) 0.91-1.88 (m, -CH ₂ -and -CH ₃ , 53H), 4.17-4.42 (br, -OCH _2- , 6H), 7.33-8.58 (m , th-H and> C = CH-, 3H)

Example 3 Synthesis of 2- (2,5-dibromothiophen-3-ylmethylene) -dihexyl malonate (dihalothiophene ester derivative) According to the following synthesis route, using malonic acid (compound 11) as a raw material, 2- Synthesis of (2,5-dibromo-thiophen-3-ylmethylene) -dihexyl malonate (compound 14) was synthesized.

1) Synthesis of dihexyl malonate (compound 12) Sulfuric acid (0.1 mL) was added to a mixture of malonic acid (compound 11, 5 g, 48 mmol), hexanol (10.3 g, 100.8 mmol) and toluene (50 mL). The mixture was refluxed for 18 hours while removing water using a Dean-Stark apparatus. After the solvent was distilled off, the residue was purified by silica gel column chromatography (ethyl acetate: hexane = 4: 1) to obtain colorless liquid compound 12 (11.2 g) in a yield of 86%.

2) Synthesis of 2- (2,5-dibromo-thiophen-3-ylmethylene) -dihexyl malonate (compound 14)
2,5-dibromo-3-thiophenecarbaldehyde (compound 9, 1 g, 3.7 mmol), dihexyl malonate (compound 12, 1.01 g, 3.7 mmol), piperidine (0.1 mL) and toluene (10 mL) After the mixture was refluxed for 16 hours, the temperature was lowered to room temperature and the organic solvent was distilled off. The resulting oily mixture was purified by silica gel column chromatography (chloroform: hexane = 1: 3) to obtain colorless oily compound 14 (1.3 g) in a yield of 65%. The ¹ H-NMR (400 MHz, CDCl ₃ ) measurement result of the obtained compound 14 is shown below (FIG. 4).

¹ H-NMR (CDCl ₃ ): δ (ppm) 0.87-0.92 (m, -CH ₃ , 6H), 1.25-1.44 (m, -CH _2- , 12H), 1.66-1.74 (m, -CH _2- , 4H), 4.24 (t, J = 6.6 Hz, -OCH _2- , 2H), 4.29 (t, J = 6.8 Hz, -OCH _2- , 2H), 7.02 (s, th-H, 1H), 7.59 (s,> C = CH-, 1H)

Reference Example 2 Synthesis of benzodithiophene derivative (2)
According to the following synthesis route, using 3-thiophenecarboxylic acid (compound 1) as a raw material, 2,6-bis (trimethylstannyl) -4,8-bis (octyloxy) benzo [1,2-b: 4,5 -b '] dithiophene (compound 17) was synthesized.

1) Synthesis of 4,8-bis (octyloxy) benzo [1,2-b: 4,5-b ′] dithiophene (Compound 16) Benzo [1,2-obtained in the same manner as in Reference Example 1 above. b: 4,5-b '] dithiophene-4,8-dione (compound 4,1.00 g, 4.54 mmol) and zinc powder (0.65 g, 9.98 mmol) in ethanol (4 mL) and 20% sodium hydroxide Aqueous solution (15 mL) was added. After refluxing for 2 hours, Compound 15 (8.01 g, 28.15 mmol) was added, and the mixture was further refluxed for 14 hours. The temperature was lowered and insolubles were removed by filtration. The filtrate was diluted with water (150 mL) and extracted three times with chloroform (50 mL). After drying this organic phase over magnesium sulfate, the solvent was distilled off and the residue was purified by silica gel column chromatography (chloroform: hexane = 1: 5) to give colorless solid compound 16 (1.2 g) in 59% yield. Obtained.

2) Synthesis of 2,6-bis (trimethylstannyl) -4,8-bis (octyloxy) benzo [1,2-b: 4,5-b '] dithiophene (Compound 17) Compound 16 (1.00 g, N-BuLi (3.60 mL, 8.40 mmol) (1.57 M hexane solution) was added to a mixture of 2.24 mmol) and THF (30 mL) at -80 ° C. The mixture was stirred at -80 ° C for 30 minutes and then stirred at room temperature for 30 minutes. The temperature was lowered again to −80 ° C. and dissolved in THF (5 mL). Chlorotrimethyltin (1.34 g, 6.72 mmol) was added. After stirring for 18 hours at room temperature, water was added. Extracted with hexane and the organic phase was dried over magnesium sulfate. After the solvent was distilled off, the resulting solid was recrystallized from isopropanol to obtain colorless solid compound 17 (1.13 g) in a 71% yield.

Example 4 Synthesis of Polymer P2 Polymer P2 was synthesized from compound 17 as a raw material according to the following synthesis route.

Compound 17 (386 mg, 0.50 mmol), Compound 14 (269 mg, 0.50 mmol) and Pd (PPh ₃ ) ₄ (25 mg, 0.016 mmol) were mixed, and the mixture was dried in vacuo for 10 minutes. (8 mL) and DMF (2 mL) were added. The mixed solution was bubbled with argon gas for 10 minutes, and then stirred at 120 ° C. for 7 hours under an argon atmosphere. Thereafter, the temperature was returned to room temperature, reprecipitated with methanol, and the precipitate was filtered. The solid was dissolved in chloroform and purified by column chromatography (PSQ100B, chloroform). After distilling off the organic solvent, toluene (30 mL) was added to dissolve the solid, and reprecipitated with methanol (400 mL). The obtained solid was filtered with a membrane to obtain a brown solid polymer P2 (0.38 g) in 94% yield. The results of ¹ H-NMR (400 MHz, CDCl ₃ ) measurement of the polymer P2 obtained are shown below (FIG. 5).

¹ H-NMR (CDCl ₃ ): δ (ppm) 0.81-0.90 (m, -CH ₃ , 12H), 1.29-1.79 (m, -CH _2- , 36H), 1.94 (br, -CH _2- , 4H ), 4.27 (t, J = 6.4 Hz, -OCH _2- , 2H) 4.48 (br, -OCH _2- , 6H), 7.42 (s, th-H, 1H), 7.56 (s, th-H, 2H ), 8.03 (s,> C = CH-, 1H)

Example 5 Synthesis of 2-cyano-3- (4,6-dibromothieno [3,4-b] thiophen-2-yl) dodecyl acrylate According to the following synthetic route, 2-thiophenecarbalaldehyde (compound 18) ) Was used as a raw material to synthesize dodecyl 2-cyano-3- (4,6-dibromothieno [3,4-b] thiophen-2-yl) acrylate (compound 28).

1) Synthesis of methyl thiophene-2-carboxylate (Compound 19)
Sulfuric acid (0.5 mL) was added to a mixture of 2-thiophenecarbivalaldehyde (Compound 18, 10.00 g, 78.03 mmol) and methanol (40 mL), and the mixture was refluxed for 16 hours, and then the solvent was distilled off. The residue was purified by silica gel column chromatography (ethyl acetate: hexane = 5: 1) to obtain colorless liquid compound 19 (9.5 g) in a yield of 86%.

2) Synthesis of methyl 4,5-bischloromethylthiophene-2-carboxylate (compound 20) To a mixture of compound 19 (4.0 g, 28.1 mmol) and chloromethyl methyl ether (11.3 g, 140.1 mmol) at 0 ° C After adding tin tetrachloride (SnCl ₄ ) (13.2 g, 50.6 mmol), the mixture was stirred at room temperature for 2 hours. The solution was then poured into ice water and stirred for 30 minutes. The obtained solid was filtered and washed with water to obtain a light yellow solid compound 20 (5.4 g) in a yield of 81%.

3) Synthesis of methyl 4,6-dihydro-thieno [3,4-b] thiophene-2-carboxylate (Compound 21) To a mixture of Compound 20 (4.8 g, 20.0 mmol) and methanol (200 mL), methanol was added. A mixture of sodium sulfide nonahydrate (Na ₂ S · 9H ₂ O) (5.28 g, 22.0 mmol) dissolved in (80 mL) was added. After refluxing for 30 minutes, the temperature was returned to room temperature, and the solid matter was removed by filtration. After the filtrate was distilled off, chloroform (300 mL) was added. After drying this solution with magnesium sulfate, the solvent was distilled off to obtain a solid. The solid was purified by silica gel column chromatography (dichloromethane: hexane = 2: 3) to obtain colorless solid compound 21 (1.70 g) in a yield of 42%.

4) Synthesis of methyl thieno [3,4-b] thiophene-2-carboxylate (compound 23) To a mixture of compound 21 (0.50 g, 2.50 mmol) and ethyl acetate (5 mL), ethyl acetate (3 mL) Metachloroperbenzoic acid (mCPBA) (0.43 g, 2.50 mmol) dissolved in was added at 0 ° C. After stirring at 0 ° C. for 10 minutes, the solvent was distilled off to obtain Compound 22 as a white solid. Compound 22 was not purified and acetic anhydride (4 mL) was added thereto and stirred for 1 hour. After the residual acetic anhydride was distilled off, the residue was purified by silica gel column chromatography (ethyl acetate: hexane = 1: 10) to obtain colorless solid compound 23 (0.45 g) in a yield of 90%.

5) Synthesis of thiophene [3,4-b] thiophene-2-carbaldehyde (compound 25) To a mixture of compound 23 (1.4 g, 7.06 mmol) and THF (50 mL), lithium aluminum hydride (LiAlH ₄ ) (0.54 mmol, 14.12 mmol) was added at 0 ° C., and the mixture was stirred at room temperature for 3 hours. After completion of the reaction, the mixture was poured into water for hydrolysis, and extracted with ethyl acetate. After drying the organic phase with magnesium sulfate, the solvent was distilled off to obtain Compound 24. Compound 24 was not purified but was dissolved in dichloromethane (30 mL), pyridinium dichromate (PDC) (1.70 g, 4.52 mmol) was added, and the mixture was stirred at room temperature for 7 hours. Thereafter, the solvent was distilled off, and the resulting residue was purified by silica gel column chromatography (ethyl acetate: hexane = 1: 10) to obtain yellow solid compound 25 (0.65 g) in a yield of 55%. The ¹ H-NMR (400 MHz, CDCl ₃ ) measurement result of the obtained compound 25 is shown below (FIG. 6).

¹ H-NMR (CDCl ₃ ): δ (ppm) 7.33 (dd, J = 2.6 and 1.2 Hz, th-H, 1H), 7.68 (d, J = 1.2 Hz, th-H, 1H), 7.77 (d , J = 2.6 Hz, th-H, 1H), 10.01 (s, -CHO, 1H)

6) Synthesis of 4,6-dibromothieno [3,4-b] thiophene-2-carbaldehyde (compound 26) To a mixture of compound 25 (0.24 g, 1.43 mmol) and chloroform (5 mL), N-bromo Succinimide (NBS) (0.56 g, 3.14 mmol) was added and stirred at room temperature for 2 hours. Thereafter, chloroform (30 mL) was added to dilute, and the mixture was washed twice with 5% aqueous sodium hydroxide solution (20 mL) and water (20 mL). The organic phase was dried over magnesium sulfate, and then the solvent was distilled off to obtain Compound 26 (0.31 g) as a yellow solid in a yield of 66%. The ¹ H-NMR (400 MHz, CDCl ₃ ) measurement result of the obtained compound 26 is shown below (FIG. 7).

¹ H-NMR (CDCl ₃ ): δ (ppm) 7.53 (s, th-H, 1H), 9.97 (s, -CHO, 1H)

7) Synthesis of 2-cyano-3- (4,6-dibromothieno [3,4-b] thiophen-2-yl) dodecyl acrylate (Compound 28) Compound 27 (100 mg, 0.31 mmol), Compound 26 (93 mg, 0.38 mmol) and acetonitrile (3 mL) were added with piperidine (5 μL) and refluxed for 5 hours, and then the solvent was distilled off to obtain a solid. The solid was purified by silica gel column chromatography (ethyl acetate: hexane = 1: 3) to obtain brown solid compound 28 (0.12 g) in a yield of 69%. The ¹ H-NMR (400 MHz, CDCl ₃ ) measurement result of the obtained compound 28 is shown below (FIG. 8).

¹ H-NMR (CDCl ₃ ): δ (ppm) 0.88 (t, J = 6.8 Hz, -CH ₃ , 3H), 1.26-1.43 (m, -CH _2- , 18H), 1.72-1.77 (m,- CH _2- , 2H), 4.31 (t, J = 6.6 Hz, -OCH _2- , 2H), 7.41 (s, th-H, 1H), 8.24 (s,> C = CH-, 1H)

Example 6 Synthesis of 2-cyano-3- (5-bromo-2-iodothiophen-3-yl) hexyl acrylate (Compound 30) According to the following synthetic route, 2-cyano-3 -(5-Bromo-2-iodothiophen-3-yl) acrylic acid hexyl (compound 30) was synthesized.

5-bromo-2-iodo-3-thiophenecarbaldehyde (compound 29, 100 mg, 0.32 mmol), cyanoacetic acid hexyl ester (69 g, 0.41 mmol), piperidine (2 μL) and ethanol (3 mL) After the mixture was refluxed for 2 hours, the temperature was lowered to room temperature, and the precipitated solid was filtered. The obtained solid was washed with cold methanol to obtain Compound 30 (110 mg) as a pale yellow solid in a yield of 73%. The ¹ H-NMR (400 MHz, CDCl ₃ ) measurement results of Compound 30 obtained are shown below.

¹ H-NMR (CDCl ₃ ): δ (ppm) 0.91 (t, J = 7.2 Hz, -CH ₃ , 3H), 1.32-1.35 (m, -CH _2- , 4H), 1.41-1.45 (m,- CH _2- , 2H), 1.73-1.80 (m, -CH _2- , 2H), 4.32 (t, J = 6.6 Hz, -OCH _2- , 2H), 7.95 (s, th-H, 1H), 8.03 (s,> C = CH-, 1H)

Example 7 Synthesis of 2-cyano-3- (2,5-dibromo-thiophen-3-yl) acrylic acid (Compound 31) 2,5-Dibromo-3-thiophenecarbaldehyde (Compound) according to the following reaction formula 2-Cyano-3- (2,5-dibromo-thiophen-3-yl) acrylic acid (Compound 31) was synthesized using 9) as a raw material.

A mixture of 2,5-dibromo-3-thiophenecarbaldehyde (compound 9, 1.50 g, 5.56 mmol), cyanoacetic acid (0.568 g, 6.67 mmol), piperidine (5 μL) and acetonitrile (50 mL) After refluxing for a time, the temperature was lowered to room temperature, and the precipitated solid was filtered. The obtained solid was purified by recrystallization using a mixed solvent of ethanol and water to obtain Compound 31 (1.10 g) as a yellow solid in a yield of 59%. The results of ¹ H-NMR (400 MHz, CDCl ₃ ) measurement of the obtained compound 31 are shown below.

¹ H-NMR (DMSO-d ₆ ): δ (ppm) 7.75 (s, th-H, 1H), 7.97 (s,> C = CH-, 1H), 14.67 (br, COOH, 1H)

<Example 8> Synthesis of hexyl 2-cyano-3- (2,5-dibromothiophen-3-yl) acrylate (Compound 33) According to the following synthesis route, Cyano-3- (2,5-dibromothiophen-3-yl) acrylic acid hexyl (compound 33) was synthesized.

1) Synthesis of hexyl cyanoacetate (compound 32) Sulfuric acid (0.06 mL) was added to a mixture of cyanoacetic acid (compound 7,5.00 g, 58.8 mmol), toluene (70 mL) and n-hexanol (7.81 g, 76.4 mmol). In addition, the mixture was refluxed for 4 hours while removing water using a Dean-Stark apparatus. After the solvent was distilled off, the residue was purified by silica gel column chromatography (ethyl acetate: hexane = 4: 1) to obtain colorless liquid compound 32 (5.9 g) in a yield of 59%.

2) Synthesis of hexyl 2-cyano-3- (2,5-dibromothiophen-3-yl) acrylate (compound 33)
2,5-Dibromo-3-thiophenecarbaldehyde (Compound 9,1.00 g, 3.70 mmol), Cyanoacetic acid hexyl ester (Compound 32, 0.63 g, 3.70 mmol), Piperidine (5 μL) and Ethanol (10 mL) After the mixture was refluxed for 2 hours, the temperature was lowered to room temperature, and the precipitated solid was filtered. The obtained solid was washed with cold methanol to obtain Compound 33 (1.3 g) as a pale yellow solid in a yield of 81%.

¹ H NMR (DMSO-d ₆ ): δ (ppm) 7.75 (s, th-H, 1H), 7.97 (s, C = CH-, 1H), 14.67 (br, COOH, 1H)

<Example 9> Synthesis of polymer P3 Polymer P3 was synthesized from compound 28 as a raw material according to the following synthesis route.

Compound 13 (386 mg, 0.50 mmol), compound 28 (281 mg, 0.50 mmol) and Pd (PPh ₃ ) ₄ (25 mg, 0.016 mmol) were mixed, and the mixture was dried in vacuo for 10 minutes. (8 mL) and DMF (2 mL) were added. The mixed solution was bubbled with argon gas for 10 minutes, and then stirred at 120 ° C. for 3 hours under an argon atmosphere. Thereafter, the temperature was returned to room temperature, reprecipitated with hexane, and the precipitate was filtered. The solid was dissolved in chloroform and purified by silica gel column chromatography (chloroform). After distilling off the organic solvent, hexane was added and the resulting solid was membrane filtered to obtain black solid P3 (295 mg) in 53% yield. The ¹ H-NMR (400 MHz, CDCl ₃ ) measurement result of the obtained polymer P3 is shown below (FIG. 9).

¹ H-NMR (CDCl ₃ ): δ (ppm) 0.95-1.88 (m, -CH ₃ and -CH ₃ , 53H), 3,80-4.55 (br, -OCH _2- , 6H), 6.78-8.21 ( br, th-H and> C = CH-, 3H)

<Test Example 1>
1) Molecular weight measurement The weight average molecular weight and molecular weight distribution were measured about the polymers P1-P3. Polymer molecular weight measurement results using GPC (gel permeation chromatography: solvent THF) HLC-8320GPC (manufactured by Tosoh Corporation), P1 is Mw288,000 (Mw / Mn: 2.32), P2 is Mw333,000 (Mw / Mn: 3.44) and P3 showed Mw46,600 (Mw / Mn: 1.87). The measured value is based on polystyrene.
2) UV-vis measurement 1 × 10 ⁻⁵ M chloroform solutions of the polymers P1 to P3 were respectively prepared (P1 solution, P2 solution, P3 solution).
In addition, 10 mg / mL concentration chloroform solutions of P1 to P3 were prepared, and after hanging them on a glass substrate, Kyowa Riken Co., Ltd. spin coater (MODEL K-359S-1) (1000 rpm for 10 seconds) For 60 seconds at 3000 rpm) (P1 thin film, P2 thin film, P3 thin film).
Each of P1 solution to P3 solution and P1 thin film to P3 thin film was subjected to UV-vis measurement with JASCO V570 spectrum meter. The UV-vis spectrum of P1 is shown in FIG. 10, the UV-vis spectrum of P2 is shown in FIG. 11, and the UV-vis spectrum of P3 is shown in FIG.
The maximum absorption in the solution was observed at P1 of 545 nm, P2 of 476 nm, and P3 of 711 nm. The maximum absorption in the thin film was observed at P1 of 551 nm, P2 of 524 nm, and P3 of 735 nm.
P1 showed a 27 nm long wavelength shift compared to P2. That is, as a result of UV-vis measurement, maximum absorption was observed for P1 on the longer wavelength side than P2 for both the solution and the thin film.
In addition, as for P3, the maximum absorption on the long wavelength side was observed in both the solution and the thin film as compared with P1 and P2.
From the results of UV-vis measurement, it was found that the absorption wavelength of light can be controlled by changing the substituent on the polymer side chain. This result suggests that the conjugation length of the polymer is shortened when an alkyl ester is substituted for the cyano group.

3) Thermal decomposition measurement About said P1-P3, the thermal decomposition measurement was performed by TGA, respectively. Pyrolysis measurement was performed by using a TG-DTA6200 manufactured by Seiko Instruments Inc. and using an aluminum pan to raise the temperature in a nitrogen stream of 150 mL / min at 10 ° C./min.
As a result of thermal decomposition measurement by TGA, it was found that all polymers were stable without being thermally decomposed up to 200 ° C.
The 5% decomposition temperature was observed at 280 ° C for P1, 327 ° C for P2, and 315 ° C for P3. The 10% decomposition temperature was observed at 312 ° C for P1, 340 ° C for P2, and 334 ° C for P3. That is, P2 showed higher thermal stability than P1 and P3.
FIG. 13 shows the TGA curve for P1, FIG. 14 shows the TGA curve for P2, and FIG. 15 shows the TGA curve for P3. Table 1 shows these results.

Reference Example 3 Synthesis of Fullerene Derivative According to the following synthesis route, [6,6] phenyl C61 butyric acid hexyl ester ([6,6] PCBH, fullerene derivative) was synthesized using 4-benzoylbutyric acid (Compound 37) as a raw material. did.

1) Synthesis of hexyl 4-benzoylbutyrate (Compound 35)
Concentrated sulfuric acid (0.13 g, 1.3 mmol) was added to a mixture of 4-benzoylbutyric acid (compound 34) (5.0 g, 26.0 mmol), n-hexanol (3.46 g, 33.8 mmol) and toluene (50 mL) at room temperature. . The mixture was refluxed for 4 hours while removing water produced using a Dean-Stark apparatus, then the temperature was returned to room temperature, the solvent was distilled off, and the resulting oil was subjected to silica gel column chromatography (hexane: ethyl acetate = 4: Purification in 1) yielded a pale yellow oil compound 35 (6.9 g) in 96% yield.

2) Synthesis of hexyl 4-benzoylbutyrate p-tosylhydrazone (compound 37) To a mixture of compound 35 (5.77 g, 20.88 mmol) and methanol (15 mL), p-toluenesulfonyl hydrazide (compound 36) (3.50 g, 18.79 mmol) was added at room temperature. After refluxing for 4 hours, the temperature was returned to room temperature and the solvent was distilled off. Hexane was added to the obtained colorless oily product to form a white solid. The solid was filtered and then washed with hexane to obtain Compound 37 (7.5 g) as a white solid in a yield of 87%.

3) Synthesis of [6,6] phenyl C61 butyric acid hexyl ester ([6,6] PCBH) To a mixture of compound 37 (2.04 g, 4.59 mmol) and pyridine (34 mL), sodium methoxide (0.26 mg, 4.78 mmol) ) Was added at room temperature. The mixture was stirred at room temperature for 10 minutes, and then a mixture of o-dichlorobenzene (210 mL) and fullerene (3.00 g) was added to the mixture at room temperature. The resulting mixture was stirred at 65 ° C. for 18 hours, and then 150 mL of the organic solvent was distilled off. The remaining solution was purified by silica gel (PSQ100B) column chromatography (toluene) to obtain [5,6] phenyl C61 butyric acid hexyl ester ([5,6] PCBH).
O-Dichlorobenzene (50 mL) was added to purified [5,6] PCBH, and the mixture was refluxed for 16 hours. After returning the temperature to room temperature, the mixture was purified by silica gel (PSQ100B) column chromatography (toluene). After purification, the solvent was distilled off, leaving about 50 mL of solvent, and then methanol (150 m) was added. The obtained solid was subjected to membrane filtration to obtain [6,6] PCBH (fullerene derivative) (1.2 g) as a black brown solid in a yield of 29%.

<Example 10> Production of photoelectric conversion element Using P2 obtained by the above method as a donor material and the above [6,6] PCBH (fullerene derivative) as an acceptor material, respectively, the composition ratio of the donor material and the acceptor material It was dissolved in toluene at 1: 1 and a concentration of 1 wt% to prepare a DA (donor-acceptor) mixed solution. Furthermore, 1vol% of DIO (1,8-diiodooctane) was added as an additive and optimized.
A method for manufacturing a photoelectric conversion element will be described with reference to FIG. First, a glass substrate 1 (10Ω) on which ITO (light-transmissive conductive layer 2) was formed was cut, subjected to ultrasonic cleaning, and then dried at 120 ° C. for 30 minutes. Before applying PEDOT-PSS, irradiation with a photo cleaner (ultraviolet light: 192 nm) was performed for 5 minutes in order to remove organic substances on the substrate 1.
Next, the PEDOT-PSS ([poly (3,4-ethylenedioxythiophene) -poly (styrenesulfonate)]) PEDOT-PSS solution used for forming the donor buffer layer 3 was passed through a 0.2 μm filter with a spin coater. After that, the donor buffer layer 3 was formed by drying at 150 ° C. for 10 minutes. On the substrate 1 on which the donor buffer layer 3 is formed, the DA mixed solution is applied with a spin coater (15 seconds at 3000 rpm) and baked at 100 ° C. for 15 minutes, and the DA mixed layer 4 (donor material and acceptor material) A mixed layer) was formed.
Thereafter, a LiF layer (about 1 nm) as the electron buffer layer 5 was vacuum deposited by attaching a mask, and then Al (about 100 nm) as an electrode was deposited. Thus, a photoelectric conversion element having a device structure of ITO glass / PEDOT-PSS / DA mixed layer / LiF / Al structure was obtained.

<Test Example 2> Measurement of conversion efficiency
After correcting the amount of light using a Si standard cell, characteristics were evaluated with an IV measuring device (source meter) under the condition of 100 mW / cm ² (AM1.5G). The evaluation was performed in an inert atmosphere.
Next, the above evaluation results are shown. From the IV curve in FIG. 16, it was confirmed that a conversion efficiency of 1.90% was obtained at Jsc = 5.76 mA / cm ² , Voc = 0.76 V, and FF = 0.43.
Therefore, it was found that the DA mixed layer 4 has an excellent charge transport capability.

  The polymer of the present invention absorbs a wide range of light, has an excellent charge transport ability, and has high thermal stability. Therefore, according to the present invention, it is possible to provide a photoelectric conversion device having excellent photoelectric conversion efficiency and durability, a solar cell using the photoelectric conversion device, and a photoelectric conversion device such as an optical switching device and a sensor.

1 ... Glass substrate (transparent film)
2 ... Light-transmissive conductive layer 3 ... Donor buffer layer 4 ... DA mixed layer (solid layer)
5 ... Electronic buffer layer

Claims (10)

Following formula (1)

[In Formula (1), R < ¹ > and R < ² > show a hydrogen atom or a substituted or unsubstituted C1-C20 hydrocarbon group each independently, and R < ³ > is following formula (2).

(In formula (2), R ⁴ represents a hydrogen atom, a cyano group, a substituted or unsubstituted alkoxycarbonyl group having 2 to 20 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, or a substituted or non-substituted group. A substituted C1-C30 hydrocarbon group is shown, R < ⁵ > shows a hydrogen atom or a substituted or unsubstituted C1-C30 hydrocarbon group, and * shows a bond.)
Or a group represented by the following formula (3)

(In the formula (3), R ⁴ , R ⁵ and * are as defined above.)
The group represented by these is shown. ]
The polymer which has a structural unit represented by these. R ¹ and R ² are each independently a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, and R ⁴ is a cyano group or a substituted or unsubstituted alkoxycarbonyl group having 2 to 20 carbon atoms. The polymer according to claim 1, wherein R ⁵ is a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms.   It has a solid layer containing the polymer of Claim 1 or 2 between a pair of electrodes, The photoelectric conversion element characterized by the above-mentioned.   The photoelectric conversion element according to claim 2, wherein the solid layer further contains fullerene or a fullerene derivative.   A solar cell comprising the photoelectric conversion element according to claim 3. Following formula (10)

(In formula (10), R ¹ , R ² , R ⁶ and R ⁷ each independently represent a hydrogen atom or a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms.)
And a compound represented by the following formula (8)

(In formula (8), R ⁴ represents a hydrogen atom, a cyano group, a substituted or unsubstituted alkoxycarbonyl group having 2 to 20 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, or a substituted or non-substituted group. A substituted hydrocarbon group having 1 to 30 carbon atoms, R ⁵ represents a hydrogen atom or a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms, and each of X ¹ and X ² independently represents a halogen atom; Show.)
Or a compound represented by the following formula (9)

(In formula (9), R ⁴ , R ⁵ , X ¹ and X ² are as defined above.)
The manufacturing method of the polymer of Claim 1 or 2 including the process with which the compound represented by these is made to react. Following formula (8)

(In formula (8), R ⁴ represents a hydrogen atom, a cyano group, a substituted or unsubstituted alkoxycarbonyl group having 2 to 20 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, or a substituted or non-substituted group. A substituted hydrocarbon group having 1 to 30 carbon atoms, R ⁵ represents a hydrogen atom, or a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms, and X ¹ and X ² are each independently a halogen atom; Is shown.)
A compound represented by Following formula (5)

(In the formula (5), R ⁴ represents a hydrogen atom, a cyano group, a substituted or unsubstituted alkoxycarbonyl group having 2 to 20 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, or a substituted or non-substituted group. A substituted C1-C30 hydrocarbon group is shown, R < ⁵ > shows a hydrogen atom or a substituted or unsubstituted C1-C30 hydrocarbon group.)
And a compound represented by the following formula (6)

(In formula (6), X ¹ and X ² each independently represent a halogen atom.)
The method for producing a compound according to claim 7, wherein the compound is reacted with the compound represented by the formula: Following formula (9)

(In the formula (9), R ⁴ represents a hydrogen atom, a cyano group, a substituted or unsubstituted alkoxycarbonyl group having 2 to 20 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, or a substituted or non-substituted group. A substituted hydrocarbon group having 1 to 30 carbon atoms, R ⁵ represents a hydrogen atom, or a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms, and X ¹ and X ² are each independently a halogen atom; Is shown.)
A compound represented by Following formula (5)

(In the formula (5), R ⁴ represents a hydrogen atom, a cyano group, a substituted or unsubstituted alkoxycarbonyl group having 2 to 20 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, or a substituted or non-substituted group. A substituted C1-C30 hydrocarbon group is shown, R < ⁵ > shows a hydrogen atom or a substituted or unsubstituted C1-C30 hydrocarbon group.)
And a compound represented by the following formula (7)

(In formula (7), X ¹ and X ² each independently represent a halogen atom.)
The method for producing a compound according to claim 9, wherein the compound represented by the formula is reacted.

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