JP2013207252A - Photoelectric conversion element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoelectric conversion element having high photoelectric conversion efficiency.SOLUTION: A photoelectric conversion element includes: a first electrode; a second electrode; and an active layer disposed between the first electrode and the second electrode. The active layer contains an electron-donative polymer compound and an electron-accepting polymer compound. At least one of the electron-donative polymer compound and the electron-accepting polymer compound is a polymer compound comprised only of arylene group and one or more kinds of repetitive units selected from the group consisting of divalent heterocyclic groups. The electron-donative polymer compound has a weight-average molecular weight of 70000 or more in terms of polystyrene. The electron-accepting polymer compound has a weight-average molecular weight of 70000 or more in terms of polystyrene.

Description

  The present invention relates to a photoelectric conversion element, and more specifically to a photoelectric conversion element including an active layer containing a polymer compound containing a predetermined repeating unit.

  The photoelectric conversion element includes a pair of electrodes mainly including an anode and a cathode, and an active layer provided between the pair of electrodes. Organic thin-film solar cells having an active layer containing an organic compound that is one embodiment of a photoelectric conversion element may be able to significantly reduce manufacturing costs compared to inorganic solar cells having an active layer made of an inorganic compound such as silicon. It has attracted attention as a cheaper solar cell.

  As a photoelectric conversion element, the active layer includes, in the active layer, poly (3-hexylthiophene), which is an electron-donating polymer compound, and the following repeating unit having an electron-accepting polymer compound and a polystyrene-equivalent weight average molecular weight of 28,000 ( A photoelectric conversion element containing a polymer compound containing A) and a repeating unit (B) has been proposed (see Patent Document 1).

JP 2010-62550 A

  However, the photoelectric conversion element has insufficient photoelectric conversion efficiency. Accordingly, an object of the present invention is to provide a photoelectric conversion element having higher photoelectric conversion efficiency.

  That is, the present invention first has a first electrode and a second electrode, and an electron-donating polymer compound and an electron-accepting compound are interposed between the first electrode and the second electrode. And an active layer containing a molecular compound, wherein at least one of the electron-donating polymer compound and the electron-accepting polymer compound is selected from the group consisting of an arylene group and a divalent heterocyclic group. It is a polymer compound consisting only of repeating units, and the electron-donating polymer compound has a polystyrene-equivalent weight average molecular weight of 70000 or more, and the electron-accepting polymer compound has a polystyrene-equivalent weight average molecular weight of 70000 or more. A photoelectric conversion element is provided.

  In the present invention, secondly, at least one selected from the group consisting of a divalent aromatic hydrocarbon group and a divalent heterocyclic group, both of the electron donating polymer compound and the electron accepting polymer compound. The photoelectric conversion element, which is a polymer compound composed of only the repeating unit, is provided.

  Thirdly, the present invention provides the photoelectric conversion element, wherein the electron-donating polymer compound has a polystyrene-equivalent weight average molecular weight of 80,000 or more.

  Fourthly, the present invention provides the photoelectric conversion element, wherein the electron-accepting polymer compound has a polystyrene-equivalent weight average molecular weight of 80,000 or more.

  Fifth, the present invention provides the photoelectric conversion element, wherein at least one of the electron donating polymer compound and the electron accepting polymer compound is a polymer compound containing a repeating unit containing a thiophene skeleton.

  Sixthly, the present invention relates to the photoelectric conversion, wherein at least one of the electron donating polymer A compound and the electron accepting polymer compound is a polymer compound containing a repeating unit represented by the following formula (1): An element is provided.

[In the formula (1), R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ each independently represents a hydrogen atom or a substituent. ^{Two of} R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are linked, and two groups linked together and a carbon atom to which the two linked groups are bonded An annular structure may be formed. X ¹ , X ² and X ³ each independently represents a sulfur atom, an oxygen atom, a selenium atom, a group represented by —N (R ⁷ ) —, or a group represented by —CR ⁸ ═CR ⁹ —. Represent. R ⁷ , R ⁸ and R ⁹ each independently represents a hydrogen atom or a substituent. n and m each independently represents an integer of 0 to 5. When there are a plurality of R ^{1 s} , they may be the same or different. When there are a plurality of R ^{2 s} , they may be the same or different. When there are a plurality of R ⁵ , they may be the same or different. When there are a plurality of R ^{6 s} , they may be the same or different. When there are a plurality of X ¹ , they may be the same or different. When there are a plurality of X ³ , they may be the same or different. ]

  Seventh, the present invention has the largest number of repeating units represented by the formula (1) among all kinds of repeating units contained in the polymer compound containing the repeating unit represented by the formula (1). The photoelectric conversion element is provided.

  Eighth, the present invention provides a solar cell module including the photoelectric conversion element.

  Ninthly, the present invention provides an image sensor including the photoelectric conversion element or the solar cell module.

  The photoelectric conversion element of the present invention is extremely useful because of high photoelectric conversion efficiency.

  Hereinafter, the present invention will be described in detail.

(Basic form of photoelectric conversion element)
The photoelectric conversion element of the present invention has a first electrode and a second electrode, and an electron-donating polymer compound and an electron-accepting polymer are provided between the first electrode and the second electrode. And an active layer containing the compound. At least one of the first electrode and the second electrode is preferably a transparent or translucent electrode.

(substrate)
The photoelectric conversion element of the present invention is usually formed on a substrate. The substrate may be any substrate that does not change chemically when, for example, an electrode is formed on its main surface and a layer containing an organic compound is formed. Examples of the material for the substrate include glass, plastic, polymer film, and silicon. In the case where the photoelectric conversion element is formed on an opaque substrate, it is preferable that the electrode on the side opposite to the substrate (that is, the electrode far from the substrate) is transparent or translucent.

(electrode)
Examples of the transparent or translucent electrode include a conductive metal oxide film and a translucent metal thin film. Examples of transparent or translucent electrode materials include indium oxide, zinc oxide, tin oxide, and indium tin oxide (ITO), indium zinc oxide (IZO), NESA, gold, platinum, and silver, which are composites thereof. And copper, and ITO, IZO, and tin oxide are preferred. Examples of the electrode forming method include a vacuum deposition method, a sputtering method, an ion plating method, and a plating method. Moreover, you may use the transparent conductive film which consists of organic materials, such as a polyaniline and its derivative (s), polythiophene, and its derivative (s) as a transparent or semi-transparent electrode. The transparent or translucent electrode may be an anode or a cathode.

  The photoelectric conversion element of the present invention may have an opaque electrode that is not transparent or translucent, and examples of the material for the opaque electrode include metals and conductive polymers. Specific examples of opaque electrode materials include lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, barium, aluminum, scandium, vanadium, zinc, yttrium, indium, cerium, samarium, europium, terbium, ytterbium A metal such as an alloy of two or more of the metals, one or more of the metals, and selected from the group consisting of gold, silver, platinum, copper, manganese, titanium, cobalt, nickel, tungsten and tin Examples include alloys with one or more metals, graphite, graphite intercalation compounds, polyaniline and its derivatives, polythiophene and its derivatives. Examples of the alloy include magnesium-silver alloy, magnesium-indium alloy, magnesium-aluminum alloy, indium-silver alloy, lithium-aluminum alloy, lithium-magnesium alloy, lithium-indium alloy, and calcium-aluminum alloy.

(Buffer layer)
The photoelectric conversion element of this invention may have additional intermediate | middle layers (charge transport layer etc.) other than an active layer as a further structure for improving a photoelectric conversion efficiency. Examples of the material used for the intermediate layer include alkali metal halides such as lithium fluoride, alkaline earth metal halides, alkali metal oxides, and alkaline earth metal oxides.
In addition, fine particles of inorganic semiconductors such as titanium oxide, a mixture of PEDOT (poly (3,4-ethylenedioxythiophene)) and PSS (poly (4-styrenesulfonate)) (PEDOT: PSS), etc. are used for the intermediate layer. It may be used as

(Active layer)
The active layer contained in the photoelectric conversion element of the present invention contains an electron donating polymer compound and an electron accepting polymer compound. At least one of the electron donating polymer compound and the electron accepting polymer compound is a polymer compound comprising only one or more repeating units selected from the group consisting of an arylene group and a divalent heterocyclic group. Both the electron-donating polymer compound and the electron-accepting polymer compound are polymer compounds composed of only one or more repeating units selected from the group consisting of an arylene group and a divalent heterocyclic group. preferable.
Whether an electron-donating polymer compound or an electron-accepting polymer compound is determined from the energy level of the highest occupied molecular orbital (HOMO) or lowest unoccupied molecular orbital (LUMO) of each combined compound. Relatively determined.

An arylene group means a group obtained by removing two hydrogen atoms directly bonded to an aromatic ring from an optionally substituted aromatic hydrocarbon, such as a phenylene group, naphthalenediyl group, anthracenediyl Groups, pyrenediyl groups and fluorenediyl groups.
The divalent heterocyclic group means a group in which two hydrogen atoms directly bonded to the heterocyclic ring are removed from the heterocyclic compound, such as a thiophene diyl group, a benzothiadiazole diyl group, a furandiyl group, and pyridine. A diyl group and a pyrrole diyl group are mentioned. The divalent heterocyclic group is preferably a divalent aromatic heterocyclic group.

(Electron donating polymer)
The electron-donating polymer compound has a polystyrene-equivalent weight average molecular weight of 70000 or more and is not particularly limited as long as it has absorption in the sunlight wavelength region. As the electron-donating polymer compound, a polymer compound having an energy level of the highest occupied molecular orbital of −4.7 eV or lower and an energy level of the lowest unoccupied molecular orbital of −4.0 eV or higher is preferable. Examples of the electron donating polymer compound include polythiophene and derivatives thereof, and polypyrrole and derivatives thereof. As the electron-donating polymer compound, polythiophene and derivatives thereof are preferable, and a polymer compound having a structure including a 2 to 5 mer of thiophene or a polymer compound having a structure including a 2 to 5 mer of a derivative of thiophene. More preferred. Here, the polythiophene derivative is a polymer compound having a thiophenediyl group having a substituent as a repeating unit.

  Polythiophene and its derivatives are preferably homopolymers. A homopolymer is a polymer in which only a plurality of repeating units selected from the group consisting of a thiophenediyl group and a substituted thiophenediyl group are bonded. The thiophene diyl group is preferably a thiophene-2,5-diyl group, and the thiophene diyl group having a substituent is preferably an alkylthiophene-2,5-diyl group. Specific examples of polythiophene that is a homopolymer and derivatives thereof include poly (3-hexylthiophene-2,5-diyl) (P3HT), poly (3-octylthiophene-2,5-diyl), and poly (3-dodecyl). Thiophene-2,5-diyl) and poly (3-octadecylthiophene-2,5-diyl). Among the polythiophenes and derivatives thereof that are homopolymers, polythiophene homopolymers composed of thiophene diyl groups substituted with alkyl groups having 6 to 30 carbon atoms are preferred.

(Electron-accepting polymer compound)
The electron-accepting polymer compound has a polystyrene-equivalent weight average molecular weight of 70000 or more. As the electron-accepting polymer compound, a polymer compound having an energy level of the highest occupied molecular orbital of −5.0 eV or lower and an energy level of the lowest unoccupied molecular orbital of −4.3 eV or higher is preferable. Examples of the electron-accepting polymer compound include polyquinoline and derivatives thereof, polyquinoxaline and derivatives thereof, and polyfluorene and derivatives thereof. As the electron-accepting polymer compound, a polymer compound having a benzothiadiazole structure in a repeating unit and a polymer compound having a quinoxaline structure in a repeating unit are preferable, and a polymer compound having a benzothiadiazole structure in a repeating unit is more preferable.

  Examples of the polymer compound containing a benzothiadiazole structure in the repeating unit include a polymer compound represented by the following formula (3). In formula (3), p represents an integer of 2 or more.

  The weight of the electron-accepting polymer compound relative to the weight of the electron-donating polymer compound in the active layer is preferably 10 parts by weight to 1000 parts by weight with respect to 100 parts by weight of the electron-donating polymer compound. More preferably, the amount is from parts by weight to 500 parts by weight.

  The thickness of the active layer is preferably 1 nm to 100 μm, more preferably 2 nm to 1000 nm, still more preferably 5 nm to 500 nm, and particularly preferably 20 nm to 200 nm.

  In the present invention, the polystyrene-equivalent weight average molecular weight of the electron donating polymer compound and the electron accepting polymer compound is a weight average molecular weight measured at normal temperature by gel permeation chromatography. The weight average molecular weight in terms of polystyrene of the electron donating polymer compound and the electron accepting polymer compound is 70000 or more, preferably 75000 or more, and more preferably 80000 or more.

  In the photoelectric conversion element of the present invention, it is preferable that at least one of the electron donating polymer compound and the electron accepting polymer compound is a polymer compound including a repeating unit containing a thiophene skeleton.

  In the photoelectric conversion element of the present invention, it is preferable that at least one of the electron donating polymer compound and the electron accepting polymer compound is a polymer compound containing a repeating unit represented by the following formula (1).

  In formula (1), n and m each independently represent an integer of 0 to 5. n and m are preferably integers of 1 to 3, and more preferably 1.

R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ each independently represent a hydrogen atom or a substituent. When there are a plurality of R ^{1 s} , they may be the same or different. When there are a plurality of R ^{2 s} , they may be the same or different. When there are a plurality of R ⁵ , they may be the same or different. When there are a plurality of R ^{6 s} , they may be the same or different.

As the substituent represented by R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ , a fluorine atom and a group having 1 to 30 carbon atoms are preferable. Examples of the substituent represented by R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ include a fluorine atom, a methyl group, an ethyl group, a butyl group, a hexyl group, an octyl group, and a dodecyl group. Alkoxy groups such as alkyl groups, methoxy groups, ethoxy groups, butoxy groups, hexyloxy groups, octyloxy groups, dodecyloxy groups, etc., aryl groups such as phenyl groups, naphthyl groups, alkylthio groups such as methylthio groups, dimethylamino groups And substituted amino groups.

In addition, ^{two of} R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are connected to each other, and two groups connected to each other and a carbon atom to which the two connected groups are bonded. And may form a ring structure.
Examples of the combination of two groups that can be connected to each other include a combination of R ¹ and R ^2, a combination of R ³ and R ^{4, and} a combination of R ⁵ and R ⁶ .

A ring structure in which R ¹ and R ² are linked, the linked R ¹ and R ² , the carbon atom to which R ¹ is bonded, and the carbon atom to which R ² is bonded; and R ⁵ and R ⁶ is linked, and R ⁵ and R ⁶ coupled, specific examples of the cyclic structure which may be formed with carbon atoms to which carbon atoms and R ⁶ R ⁵ is attached is attached is represented by the following formula ( 4).

Specific examples of the cyclic structure that R ³ and R ⁴ are connected to each other, the connected R ³ and R ⁴ , the carbon atom to which R ³ is bonded, and the carbon atom to which R ⁴ is bonded are as follows: Examples include the structure represented by the following formula (5) and the structure represented by the following formula (6).

In formula (5), R ¹² and R ¹³ each independently represents a hydrogen atom or a substituent.

Specific examples of the substituents represented by R ¹² and R ¹³ are the same as the specific examples of the substituents represented by R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ .

R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are preferably a hydrogen atom or an alkyl group, more preferably a hydrogen atom.

In formula (1), X ¹ , X ² and X ³ are each independently a sulfur atom, an oxygen atom, a selenium atom, a group represented by —N (R ⁷ ) — or —CR ⁸ ═CR ⁹ —. Represents a group represented by R ⁷ , R ⁸ and R ⁹ each independently represents a hydrogen atom or a substituent. When there are a plurality of X ¹ , they may be the same or different. When there are a plurality of X ³ , they may be the same or different.

Examples of the substituent represented by R ⁷ , R ⁸ and R ⁹ include alkyl groups such as methyl group, ethyl group, butyl group, hexyl group, octyl group and dodecyl group, and aryl groups such as phenyl group and naphthyl group. Groups.
X ¹ , X ² and X ³ are preferably sulfur atoms.

  As the repeating unit represented by the formula (1), a repeating unit represented by the following formula (1-1) is preferable.

  When at least one of the electron-donating polymer compound and the electron-accepting polymer compound is a polymer compound containing a repeating unit represented by the formula (1), all types of repetitions included in the polymer compound Of the units, the number of repeating units represented by formula (1) is preferably the largest.

  Since the photoelectric conversion efficiency of the photoelectric conversion element can be increased, the ratio of the number of repeating units represented by the formula (1) possessed by the polymer compound containing the repeating units represented by the formula (1) is: Is preferably more than 50%, more preferably 52% or more, and even more preferably 55% or more with respect to the total number of all repeating units possessed by.

  Further, the ratio of the number of repeating units represented by formula (1) is preferably less than 100%, more preferably 98% or less, with respect to the total number of all repeating units in the polymer compound. Preferably, it is 70% or less.

At least one of the electron donating polymer compound and the electron accepting polymer compound preferably contains another repeating unit in addition to the repeating unit represented by the formula (1).
As another repeating unit, the repeating unit represented by following formula (2) is mentioned, for example.

In formula (2), ring A and ring B each independently represent an aromatic ring. R ¹⁰ and R ¹¹ each independently represents a hydrogen atom or a substituent. R ¹⁰ and R ¹¹ are linked, and the linked R ¹⁰ and R ¹¹ and the carbon atom to which R ¹⁰ is bonded and the carbon atom to which R ¹¹ is bonded may form a cyclic structure.

Examples of the substituent represented by R ¹⁰ and R ¹¹ include methyl, ethyl, butyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, and the like. Group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, eicosyl group and other alkyl groups, and phenyl group, naphthyl group and other aryl groups. The number of carbon atoms of the substituent represented by R ¹⁰ and R ¹¹ is preferably 12 or more. R ¹⁰ and R ¹¹ are preferably a monovalent hydrocarbon group such as an alkyl group and an aryl group, and more preferably an alkyl group.

  Examples of the ring A and the ring B include aromatic carbocycles such as a benzene ring and a naphthalene ring, and aromatic heterocycles such as thiophene. Ring A and ring B are preferably 5- to 10-membered rings, and more preferably benzene rings and naphthalene rings.

  As the repeating unit represented by the formula (2), a repeating unit represented by the following formula (2-1) is preferable.

In formula (2-1), R ¹⁰ and R ¹¹ represent the same meaning as described above.

  When at least one of the electron-donating polymer compound and the electron-accepting polymer compound includes a repeating unit represented by the formula (1) and a repeating unit represented by the formula (2), Among all kinds of repeating units, it is preferable that the number of repeating units represented by the formula (1) is the largest, and then the number of repeating units represented by the formula (2) is large. The polymer compound containing the repeating unit represented by the formula (1) and the repeating unit represented by the formula (2) is only the repeating unit represented by the formula (1) and the repeating unit represented by the formula (2). Preferably it consists of.

  In order to express various functions, the active layer may contain other components in addition to the electron donating polymer compound and the electron accepting polymer compound as necessary. Other components include, for example, an ultraviolet absorber, an antioxidant, a sensitizer for sensitizing the function of generating charge by absorbed light, and a light stabilizer for increasing the stability to ultraviolet light. Can be mentioned.

  The blending amount of the other components in the active layer is preferably 5 parts by weight or less, particularly 0.01 parts by weight to 3 parts by weight with respect to 100 parts by weight of the total amount of the electron donating compound and the electron accepting compound. It is effective to mix | blend in the ratio.

  The active layer may contain a polymer compound other than the electron donating compound and the electron accepting compound as a polymer binder in order to enhance the mechanical properties. As the polymer binder, a polymer compound that does not inhibit the electron transport property or hole transport property is preferable, and a polymer compound that absorbs less visible light is preferable. Examples of the polymer binder include poly (N-vinylcarbazole), polyaniline and derivatives thereof, polythiophene and derivatives thereof, poly (p-phenylene vinylene) and derivatives thereof, and poly (2,5-thienylene vinylene) and derivatives thereof. , Polycarbonate, polyacrylate, polymethyl acrylate, polymethyl methacrylate, polystyrene, polyvinyl chloride, and polysiloxane.

<Method for producing polymer compound>
The method for producing the electron donating polymer compound and the electron accepting polymer compound used in the present invention is not particularly limited. Since the synthesis | combination of a high molecular compound can be made easier, the manufacturing method using a Suzuki coupling reaction or a Stille coupling reaction is preferable.

As a method using the Suzuki coupling reaction, for example, the following formula (100):
Q ₁ -E ₁ -Q ₂ (100)
[In formula (100), E ₁ represents an arylene group or a divalent heterocyclic group. Q ₁ and Q ₂ each independently represents a dihydroxyboryl group (—B (OH) ₂ ) or a boric acid ester residue. ]
One or more compounds represented by formula (200):
T ₁ -E ₂ -T ₂ (200)
[In formula (200), E ₂ represents a group represented by formula (1). T ₁ and T ₂ each independently represent a halogen atom or a sulfonic acid residue. ]
The manufacturing method which has a process with which 1 or more types of compounds represented by these are made to react in presence of a palladium catalyst and a base is mentioned.

E ₁ is preferably a group represented by the formula (2). E ₂ may be the same group as E ₁ or a different group, but is preferably a different group.

  The boric acid ester residue means a group obtained by removing a hydroxyl group from a boric acid diester, and examples thereof include a dialkyl ester residue, a diaryl ester residue, and a di (arylalkyl) ester residue. Examples of the boric acid ester residue include groups represented by the following formula.

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

Examples of the halogen atom represented by T ₁ and T ₂ in the compound represented by the formula (200) include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. In view of the ease of synthesis of the polymer compound, the halogen atom represented by T ₁ and T ₂ is preferably a bromine atom or an iodine atom, and more preferably a bromine atom.

In the compound represented by the formula (200), the sulfonic acid residue represented by T ₁ and T ₂ is an atom obtained by removing acidic hydrogen from sulfonic acid (a compound having a group represented by —SO ₃ H). Means a group. Specific examples of the sulfonic acid residues represented by T ₁ and T ₂ include alkyl sulfonate groups (for example, methane sulfonate group, ethane sulfonate group), aryl sulfonate groups (for example, benzene sulfonate group, p-toluene sulfonate group). , Arylalkyl sulfonate groups (eg, benzyl sulfonate groups) and trifluoromethane sulfonate groups.

  Examples of the method for performing the Suzuki coupling reaction include a method in which a palladium catalyst is used as a catalyst in an arbitrary solvent and the reaction is performed in the presence of a base.

  Examples of the palladium catalyst used in the Suzuki coupling reaction include a Pd (0) catalyst and a Pd (II) catalyst. Specific examples of the palladium catalyst include palladium [tetrakis (triphenylphosphine)], palladium acetates, dichlorobis (triphenylphosphine) palladium, palladium acetate, tris (dibenzylideneacetone) dipalladium, bis (dibenzylideneacetone). Palladium may be mentioned, and dichlorobis (triphenylphosphine) palladium, palladium acetate, and tris (dibenzylideneacetone) dipalladium are preferable from the viewpoint of ease of reaction (polymerization) operation and reaction (polymerization) rate.

  The addition amount of the palladium catalyst is not particularly limited as long as it is an effective amount as a catalyst. The addition amount of the palladium catalyst is usually 0.0001 mol to 0.5 mol, preferably 0.0003 mol to 0.1 mol, relative to 1 mol of the compound represented by the formula (100).

  When using palladium acetate as the palladium catalyst used in the Suzuki coupling reaction, for example, a phosphorus compound such as triphenylphosphine, tri (o-tolyl) phosphine, tri (o-methoxyphenyl) phosphine is used as a ligand. Can be added. In this case, the addition amount of the ligand is usually 0.5 mol to 100 mol, preferably 0.9 mol to 20 mol, more preferably 1 mol to 10 mol, relative to 1 mol of the palladium catalyst. is there.

Examples of the base used for the Suzuki coupling reaction include inorganic bases, organic bases, inorganic salts and the like. Examples of the inorganic base include potassium carbonate, sodium carbonate, and barium hydroxide. Examples of the organic base include triethylamine and tributylamine. An example of the inorganic salt is cesium fluoride.
The addition amount of the base is usually 0.5 mol to 100 mol, preferably 0.9 mol to 20 mol, more preferably 1 mol to 10 mol, relative to 1 mol of the compound represented by the formula (100). is there.

The Suzuki coupling reaction is usually performed in a solvent. Examples of the solvent include N, N-dimethylformamide, toluene, dimethoxyethane, and tetrahydrofuran. From the viewpoint of solubility of the polymer compound used in the present invention, toluene and tetrahydrofuran are preferred. Further, the base may be added as an aqueous solution and reacted in a two-phase system. When an inorganic salt is used as the base, it is usually added as an aqueous solution and reacted from the viewpoint of solubility of the inorganic salt.
In addition, when adding a base as aqueous solution and making it react by a two-phase system, you may add phase transfer catalysts, such as a quaternary ammonium salt, as needed.

  The temperature at which the Suzuki coupling reaction is performed is set according to the solvent used. This temperature is usually about 50 ° C. to 160 ° C., and the resulting polymer compound can have a higher molecular weight, so 60 ° C. to 120 ° C. is preferable. Alternatively, the temperature may be raised to near the boiling point of the solvent and refluxed. The reaction time may be the end point when the desired degree of polymerization is reached. The reaction time is usually about 0.1 hour to 200 hours. About 1 hour to 30 hours is efficient and preferable.

  The reaction is carried out in a reaction system in which the Pd (0) catalyst is not deactivated under an inert atmosphere such as argon gas or nitrogen gas. For example, it is performed in a system sufficiently deaerated with argon gas or nitrogen gas. Specifically, after the inside of the polymerization vessel (reaction system) is sufficiently substituted with nitrogen gas and degassed, the compound represented by the formula (100), the compound represented by the formula (200), Dichlorobis (triphenylphosphine) palladium (II) was charged, the polymerization vessel was sufficiently replaced with nitrogen gas, degassed, and then degassed by adding a degassed solvent such as toluene by bubbling with nitrogen gas in advance. Thereafter, a base degassed by bubbling with nitrogen gas in advance, for example, an aqueous sodium carbonate solution, is dropped into this solution, and then heated and heated, for example, while maintaining an inert atmosphere at the reflux temperature for 8 hours. Polymerize.

  If the polymerization active group remains at the terminal of the electron-donating polymer compound and the electron-accepting polymer compound, characteristics and lifetime of the photoelectric conversion element obtained when used for the production of the photoelectric conversion element may be reduced. Therefore, it may be protected with a stable group. The stable group is preferably a group having a conjugated bond continuous with the conjugated structure of the main chain.

<Method for producing active layer>
As the method for producing the active layer, film formation from a solution containing an electron donating polymer compound and an electron accepting polymer compound is preferable.

The solvent used for film formation from a solution is not particularly limited as long as it dissolves an electron-donating polymer compound and an electron-accepting polymer compound. Examples of the solvent include hydrocarbon solvents such as toluene, xylene, mesitylene, tetralin, decalin, bicyclohexyl, n-butylbenzene, sec-butylbenzene, tert-butylbenzene, carbon tetrachloride, chloroform, dichloromethane, dichloroethane, Examples include halogenated hydrocarbon solvents such as chlorobutane, bromobutane, chloropentane, bromopentane, chlorohexane, bromohexane, chlorocyclohexane, bromocyclohexane, chlorobenzene, dichlorobenzene, and trichlorobenzene, and ether solvents such as tetrahydrofuran and tetrahydropyran. . The electron donating polymer compound and the electron accepting polymer compound can usually be dissolved in the solvent in an amount of 0.1% by weight or more.
For film formation, spin coating method, casting method, micro gravure coating method, gravure coating method, bar coating method, roll coating method, wire bar coating method, dip coating method, spray coating method, screen printing method, gravure printing method, Application methods such as flexographic printing method, offset printing method, inkjet printing method, dispenser printing method, nozzle coating method, capillary coating method can be used, spin coating method, flexographic printing method, gravure printing method, inkjet printing method, and Dispenser printing is preferred.

<Application of photoelectric conversion element>
The photoelectric conversion element of the present invention can be operated as an organic thin film solar cell by generating photovoltaic power between the electrodes by making light such as sunlight enter from the transparent or translucent electrode side. It can also be used as an organic thin film solar cell module by integrating a plurality of organic thin film solar cells.

  In addition, when light is incident from the transparent or translucent electrode side in a state where a voltage is applied between the electrodes or in a state where no voltage is applied, a photocurrent flows and the organic light sensor can be operated. It can also be used as an organic image sensor by integrating a plurality of organic photosensors.

<Solar cell module>
The organic thin film solar cell can basically have the same module structure as a conventional solar cell module. The solar cell module generally has a structure in which cells are formed on a support substrate such as metal or ceramic, and the cell is covered with a filling resin or protective glass, and light is taken in from the opposite side of the support substrate. It is also possible to use a transparent material such as tempered glass for the support substrate, configure a cell thereon, and take in light from the transparent support substrate side. Specifically, a module structure called a super straight type, a substrate type, and a potting type, a substrate integrated module structure used in an amorphous silicon solar cell, and the like are known. The organic thin film solar cell of this invention can select these module structures suitably according to a use purpose, a use place, and a use environment.

  In a typical super straight type or substrate type module, cells are arranged at regular intervals between support substrates that are transparent on one or both sides and treated with antireflection, and adjacent cells are connected by metal leads or flexible wiring. It is connected, and the collector electrode is arrange | positioned in the outer edge part, It has the structure which can take out the electric power which generate | occur | produced outside. Various types of plastic materials such as ethylene vinyl acetate (EVA) may be used between the substrate and the cell in the form of a film or a filling resin depending on the purpose in order to protect the cell and improve the current collection efficiency. Also, when used in places where there is no need to cover the surface with a hard material, such as where there is little impact from the outside, the surface protective layer is made of a transparent plastic film, or the protective function is achieved by curing the filling resin. It is possible to eliminate the supporting substrate on one side. The periphery of the support substrate is sandwiched and fixed by a metal frame in order to ensure internal sealing and module rigidity, and the support substrate and the frame are hermetically sealed with a sealing material. If a flexible material is used for the cell itself, the support substrate, the filling material, and the sealing material, the module can be formed on a curved surface.

  In the case of a solar cell using a flexible support such as a polymer film, cells are sequentially formed while feeding out a roll-shaped support, cut to a desired size, and then the periphery is sealed with a flexible and moisture-proof material. Thus, a solar cell body can be produced. A module structure called “SCAF” described in Solar Energy Materials and Solar Cells, 48, p383-391 can also be used. Furthermore, a solar cell using a flexible support can be used by being bonded and fixed to a curved glass or the like.

  Examples are given below to illustrate the present invention in more detail. The present invention is not limited to these examples.

Synthesis example 1
(Production of polymer compound A1)

  In a 200 mL flask whose internal gas was replaced with argon, 0.945 g (1.60 mmol) of monomer (1) represented by the above formula (1), a single amount represented by the above formula (2) 0.9164 g (2.00 mmol) of the body (2), 460 mg of Aliquat 336 (manufactured by Sigma-Aldrich), 40 mL of toluene, and 26.4 mg of tris (o-methoxyphenyl) phosphine were added to obtain a suspension. The resulting suspension was bubbled with argon for 30 minutes. After bubbling, 5.2 mg of palladium (II) acetate was added, and the flask was immersed in an oil bath at 100 ° C. Thereafter, 10 mL of a 16.7% by weight aqueous sodium carbonate solution was added dropwise over 15 minutes. After the dropwise addition, the mixture was stirred at 100 ° C. for 3.5 hours, and then a solution prepared by dissolving 270 mg of phenyl borate in 1 mL of tetrahydrofuran was added, and the mixture was further stirred at 100 ° C. for 9 hours. After stirring, the flask was cooled to 25 ° C. and 25 mL of toluene was added. The resulting solution was washed twice with 50 mL of water, twice with 50 mL of a 3 wt% aqueous acetic acid solution, and further washed twice with 50 mL of water. The obtained organic layer was poured into 1000 mL of methanol to precipitate a polymer. The precipitated polymer was collected by filtration to obtain 1.43 g of polymer. The resulting polymer was dissolved in 100 mL of chloroform and passed through a column packed with 100 g of alumina. The obtained chloroform solution was poured into methanol to precipitate a purified polymer, which was filtered and dried to obtain a polymer compound A1 represented by the following formula as a purified polymer. The polymer compound A1 measured at room temperature had a polystyrene equivalent weight average molecular weight of 20,000 and a polystyrene equivalent number average molecular weight of 10,200.

Synthesis example 2
(Production of polymer compound A2)
Synthesis was performed in the same manner as in Synthesis Example 1 except that 1.063 g (1.80 mmol) of the monomer (1) was used, to obtain a polymer compound A2 represented by the following formula. The weight average molecular weight in terms of polystyrene of the polymer compound A2 measured at room temperature was 119000, and the number average molecular weight in terms of polystyrene was 26500.

Synthesis example 3
(Production of polymer compound A3)
A polymer was produced in the same manner as in Synthesis Example 1 except that 1.181 g (2.00 mmol) of the monomer (1) was used, to obtain a polymer compound A3 represented by the following formula. The polystyrene equivalent weight average molecular weight of the polymer compound A3 measured at room temperature was 302,000, and the polystyrene equivalent number average molecular weight was 26100.
The weight average molecular weight in terms of polystyrene measured at 140 ° C. was 78,000, and the number average molecular weight in terms of polystyrene was 28,000.

Example 1
(Production and evaluation of organic thin-film solar cells)
A glass substrate on which an ITO film having a thickness of 150 nm was formed by sputtering was cleaned with ozone generated by irradiation with ultraviolet rays, and surface treatment was performed. Next, polymer compound B (manufactured by Sigma-Aldrich), which is an electron-donating polymer compound, and polymer compound A2, which is an electron-accepting polymer compound represented by the following formula, are increased with respect to the weight of polymer compound A. A chloroform solution was prepared by dissolving in chloroform so that the weight ratio of the molecular compound B was 1. The number average molecular weight of polystyrene conversion of the high molecular compound B was 42300, and the weight average molecular weight of polystyrene conversion was 80400. The obtained chloroform solution was applied onto the ITO film by spin coating to form an active layer. The thickness of the active layer was about 100 nm. Lithium fluoride was deposited on the active layer with a thickness of 1 nm by a vacuum deposition machine, and then Al was deposited with a thickness of 70 nm, and then the active layer was heat-treated at 140 ° C. for 10 minutes in an inert atmosphere. An organic thin film solar cell was produced. The shape of the obtained organic thin film solar cell was a square of 2 mm × 2 mm. The obtained organic thin-film solar cell is irradiated with a certain amount of light using a solar simulator (product name: OTENTO-SUNII: AM1.5G filter, irradiance: 100 mW / cm ² ), and the generated current is measured. Short-circuit current density, open-circuit voltage, fill factor, and photoelectric conversion efficiency were determined. Short-circuit current density was 4.6 mA / cm ^2, the open circuit voltage is 1.22V, the fill factor is 0.44, the photoelectric conversion efficiency was 2.46%.

Example 2
(Production and evaluation of organic thin-film solar cells)
The polymer compound A3 was used in place of the polymer compound A2, and after forming the active layer, the active layer was heat-treated at 140 ° C. for 10 minutes under an inert atmosphere. An organic thin-film solar cell was prepared and evaluated in the same manner as in Example 1 except that it was deposited on the active layer and then Al was deposited at a thickness of 70 nm. The short circuit current density was 3.88 mA / cm ² , the open circuit voltage was 1.26 V, the fill factor was 0.55, and the photoelectric conversion efficiency was 2.70%.

Comparative Example 1
(Production and evaluation of organic thin-film solar cells)
An organic thin film solar cell was prepared and evaluated in the same manner as in Example 2 except that the polymer compound A1 was used instead of the polymer compound A3. The short-circuit current density was 2.81 mA / cm ² , the open circuit voltage was 1.25 V, the fill factor was 0.53, and the photoelectric conversion efficiency was 1.85%.

Claims (9)

An active layer that includes a first electrode and a second electrode, and includes an electron-donating polymer compound and an electron-accepting polymer compound between the first electrode and the second electrode. ,
At least one of the electron donating polymer compound and the electron accepting polymer compound is a polymer compound comprising only one or more repeating units selected from the group consisting of an arylene group and a divalent heterocyclic group. The photoelectric conversion element wherein the electron-donating polymer compound has a polystyrene-equivalent weight average molecular weight of 70000 or more, and the electron-accepting polymer compound has a polystyrene-equivalent weight average molecular weight of 70000 or more.   A polymer in which both the electron donating polymer compound and the electron accepting polymer compound are composed only of one or more repeating units selected from the group consisting of a divalent aromatic hydrocarbon group and a divalent heterocyclic group. The photoelectric conversion element according to claim 1, which is a compound.   The photoelectric conversion element according to claim 1 or 2, wherein the electron-donating polymer compound has a polystyrene-equivalent weight average molecular weight of 80,000 or more.   The photoelectric conversion element as described in any one of Claims 1-3 whose weight average molecular weight of polystyrene conversion of an electron-accepting high molecular compound is 80000 or more.   The photoelectric conversion according to any one of claims 1 to 4, wherein at least one of the electron-donating polymer compound and the electron-accepting polymer compound is a polymer compound containing a repeating unit containing a thiophene skeleton. element. 6. The polymer compound according to claim 1, wherein at least one of the electron donating polymer compound and the electron accepting polymer compound is a polymer compound containing a repeating unit represented by the following formula (1). The photoelectric conversion element as described.

[In the formula (1), R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ each independently represents a hydrogen atom or a substituent. ^{Two of} R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are linked, and two groups linked together and a carbon atom to which the two linked groups are bonded An annular structure may be formed. X ¹ , X ² and X ³ each independently represents a sulfur atom, an oxygen atom, a selenium atom, a group represented by —N (R ⁷ ) —, or a group represented by —CR ⁸ ═CR ⁹ —. Represent. R ⁷ , R ⁸ and R ⁹ each independently represents a hydrogen atom or a substituent. n and m each independently represents an integer of 0 to 5. When there are a plurality of R ^{1 s} , they may be the same or different. When there are a plurality of R ^{2 s} , they may be the same or different. When there are a plurality of R ⁵ , they may be the same or different. When there are a plurality of R ^{6 s} , they may be the same or different. When there are a plurality of X ¹ , they may be the same or different. When there are a plurality of X ³ , they may be the same or different. ]   The number of repeating units represented by the formula (1) is the largest among all types of repeating units contained in the polymer compound including the repeating unit represented by the formula (1). The photoelectric conversion element as described.   The solar cell module containing the photoelectric conversion element as described in any one of Claims 1-7.   The image sensor containing the photoelectric conversion element as described in any one of Claims 1-7, or the solar cell module of Claim 8.