JP2017057264A - Polymer having silylacetylene groups as side chains, and photoelectric conversion element and solar cell employing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoelectric conversion element with a high open circuit voltage (Voc) by employing a novel polymer.SOLUTION: The polymer includes a repeating unit represented by the general formula (1) in the figure, which comprises a condensed heterocyclic structure and a benzodifuran structure having silylacetylene groups as side chains.SELECTED DRAWING: None

Description

  Embodiments described herein relate generally to a polymer having a silylacetylene group as a side chain, and a photoelectric conversion element and a solar cell using the polymer.

  Solar cells are environmentally friendly electrical energy sources and are currently attracting attention as potential energy sources for increasingly serious energy problems. Currently, inorganic materials such as single crystal silicon, polycrystalline silicon, amorphous silicon, and compound semiconductors are used as semiconductor materials for photoelectric conversion elements of solar cells. However, solar cells manufactured using inorganic semiconductors have not been widely used in general households because of high costs. The high cost factor is mainly in the process of manufacturing a semiconductor thin film under vacuum and high temperature. Therefore, organic solar cells using organic semiconductors and organic dyes such as conjugated polymers and organic crystals are being studied as semiconductor materials expected to simplify the manufacturing process.

  However, an organic solar cell using a conjugated polymer or the like has a large problem that its photoelectric conversion efficiency is lower than that of a conventional solar cell using an inorganic semiconductor, and has not yet been put into practical use. The photoelectric conversion efficiency of organic solar cells using conventional conjugated polymers is low because of the low absorption efficiency of sunlight and the bound state of exciton where electrons and holes generated by sunlight are difficult to separate. This is because a trap for trapping carriers (electrons and holes) is easily formed, and thus generated carriers are easily trapped by traps, and the mobility of carriers is slow. So far, photoelectric conversion elements using organic semiconductors are currently Schottky-type, electron-accepting organic materials (n-type organic semiconductors) that join an electron-donating organic material (p-type organic semiconductor) and a metal having a low work function. And an electron donating organic material (p-type organic semiconductor) can be classified into a heterojunction type. In these elements, only the organic layer (about several molecular layers) at the junction contributes to the photocurrent generation, so that the photoelectric conversion efficiency is low, and its improvement is a problem. As a method for improving the photoelectric conversion efficiency of the photoelectric conversion element, a junction that contributes to photoelectric conversion by mixing an electron-accepting organic material (n-type organic semiconductor) and an electron-donating organic material (p-type organic semiconductor). There is a method of using a bulk heterojunction type with an increased number of planes. In particular, conjugated polymers are used as electron-donating organic materials (p-type organic semiconductors), and conductive polymers with n-type semiconductor properties, fullerenes such as C60 and fullerene derivatives are used as electron-accepting organic materials. A bulk heterojunction photoelectric conversion element has been reported.

  By the way, in order to improve the conversion efficiency of the photoelectric conversion element, it is necessary to improve the performance in terms of both current and voltage. In order to improve the current, there are a method for improving the conversion efficiency in the current wavelength region and a method for expanding the absorption wavelength region. In order to improve the voltage, it is necessary to widen the energy level of the photoelectric conversion material. However, development of photoelectric conversion materials is indispensable in order to substantially improve current and voltage performance. To date, many materials have been reported to improve current and voltage characteristics, and polymers obtained by copolymerizing benzodithiophene and thienothiophene are known to have high conversion efficiency. The voltage is not high enough. In addition, a material having a benzodifuran skeleton similar to benzodithiophene has been developed for the purpose of enhancing carrier mobility and solubility, but this also cannot be said to have a sufficient open-circuit voltage.

Japanese Patent No. 5482973

Macromolecules, 2012, 45, 6923-6929

  An object of the present invention is to provide a photoelectric conversion element having a high open circuit voltage (Voc) by using a novel polymer.

［式中、Ｒは互いに独立して、水素、置換または非置換のアルキル基、芳香族基およびヘテロ芳香族基から選択される置換基であり、Ａｒは置換または非置換の縮合複素環構造を示し、該縮合複素環構造における縮合複素環と前記ベンゾジフラン構造における縮合複素環とが直接結合している。］ The polymer according to the embodiment includes a repeating unit represented by the following general formula (1), which includes a benzodifuran structure having a silylacetylene group as a side chain and a condensed heterocyclic structure.

[Wherein, R is independently of one another a substituent selected from hydrogen, a substituted or unsubstituted alkyl group, an aromatic group and a heteroaromatic group, and Ar is a substituted or unsubstituted condensed heterocyclic structure. As shown, the condensed heterocyclic ring in the condensed heterocyclic structure and the condensed heterocyclic ring in the benzodifuran structure are directly bonded. ]

It is a schematic cross section of the photoelectric conversion element by embodiment.

[Polymer having silylacetylene group as side chain]
The polymer according to the embodiment has a repeating unit represented by the general formula (1). This repeating unit consists of a benzodifuran structure having a silylacetylene group as a side chain and a condensed heterocyclic structure (Ar). In this repeating unit, a benzodifuran structure having a silylacetylene group as a side chain is a donor unit, and a condensed heterocyclic structure (Ar) is an acceptor unit.

  R in the silylacetylene group is independently a substituent selected from hydrogen, a substituted or unsubstituted alkyl group, an aromatic group and a heteroaromatic group. As such an alkyl group, a linear, branched or cyclic alkyl group can be used. Carbon number of the alkyl group except a substituent becomes like this. Preferably it is 1-50, More preferably, it is 1-10. Examples of such alkyl groups include methyl groups, ethyl groups, n-propyl groups, n-butyl groups, n-pentyl groups, n-hexyl groups and n-heptyl groups, linear alkyl groups such as isopropyl groups, sec Examples include, but are not limited to, branched alkyl groups such as butyl group, isobutyl group and tert-butyl group, and cyclic alkyl groups such as cyclopentyl group, cyclohexyl group and cycloheptyl group.

  Examples of the aromatic group include a phenyl group, a benzyl group, a phenoxy group, and a benzoyl group. Examples of the heteroaromatic group include, but are not limited to, a furyl group, a pyridyl group, a quinolyl group, a thienyl group, a piperidyl group, and an isoquinonyl group.

  Specific examples of the silylacetylene group include trialkylsilylacetylene groups such as trimethylsilylacetylene group, triethylsilylacetylene group, tert-butyldimethylsilylacetylene group and triisopropylsilylacetylene group, and tert-butyldiphenylsilylacetylene group. Among them, a triisopropylsilylacetylene group is preferable among them.

  Ar represents a substituted or unsubstituted condensed heterocyclic structure, and the condensed heterocyclic ring in the condensed heterocyclic structure is directly bonded to the condensed heterocyclic ring in the benzodifuran structure. Here, “the condensed heterocyclic ring in the condensed heterocyclic structure and the condensed heterocyclic ring in the benzodifuran structure are directly bonded” means “the condensed heterocyclic ring in the condensed heterocyclic structure” and “the condensed in the benzodifuran structure”. It means that the carbon element on the “heterocycle” is directly bonded without any other substituent such as an alkyl group or a monocyclic heterocyclic compound group.

［式中、R₁は水素、置換または非置換のアルキル基、芳香族基およびヘテロ芳香族基から選択される置換基であり、R₂は水素、ハロゲン元素、シアノ基ならびに置換または非置換のアルキル基から選択される置換基であり、R₃は置換または非置換のアルキル基、置換または非置換のアルコキシ基、および置換または非置換の芳香族基から選択される置換基であり、ＸはＳまたはＯから選択される元素である。］ Ar is not particularly limited as long as it is a substituted or unsubstituted condensed heterocyclic structure, but is preferably a condensed heterocyclic structure containing at least S. More preferably, Ar is selected from a fused heterocyclic structure of the formula

[Wherein R ₁ is a substituent selected from hydrogen, a substituted or unsubstituted alkyl group, an aromatic group and a heteroaromatic group, and R ₂ is hydrogen, a halogen element, a cyano group, and a substituted or unsubstituted group. R ₃ is a substituent selected from an alkyl group, R ₃ is a substituent selected from a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, and a substituted or unsubstituted aromatic group, and X is It is an element selected from S or O. ]

  As the alkyl group, a linear, branched or cyclic alkyl group can be used. Carbon number of the alkyl group except a substituent becomes like this. Preferably it is 1-50, More preferably, it is 1-10. Examples of such alkyl groups include methyl groups, ethyl groups, n-propyl groups, n-butyl groups, n-pentyl groups, n-hexyl groups, n-heptyl groups, and the like, isopropyl groups, sec Examples include branched alkyl groups such as -butyl group, isobutyl group, tert-butyl group, 1-methylbutyl group and 1-ethylpropyl group, and cyclic alkyl groups such as cyclopentyl group, cyclohexyl group and cycloheptyl group. It is not limited to.

  Examples of the aromatic group include a phenyl group, a benzyl group, a phenoxy group, a benzoyl group, and a naphthyl group. Examples of the heteroaromatic group include, but are not limited to, a furyl group, a pyridyl group, a quinolyl group, a thienyl group, a piperidyl group, and an isoquinonyl group.

  Examples of the halogen element include fluorine, chlorine, bromine and iodine, and among them, fluorine is preferable.

  As the alkoxy group, a linear or branched alkoxy group can be used. Carbon number of the alkoxy group except a substituent becomes like this. Preferably it is 1-50, More preferably, it is 1-10. Such alkoxy groups include linear alkoxy groups such as methoxy group, ethoxy group, n-propoxy group, n-butoxy group, isopropoxy group, sec-butoxy group, isobutoxy group, tert-butoxy group, 2-ethylhexyl. Examples thereof include, but are not limited to, branched alkoxy groups such as oxy groups. As the alkoxy group, a 2-ethylhexyloxy group is particularly preferable.

  Examples of the substituent that the alkyl group, alkoxy group and aromatic group may have include an ester group, an amide group, an amino group, an alkylamino group, a mercapto group, and a cyano group, but are not limited thereto. It is not something.

  Although the specific example of the repeating unit by embodiment is shown below, this embodiment is not limited to these specific examples.

When Ar-1 is selected as Ar and isopropyl is selected as R, the repeating unit represented by the general formula (1) is shown as follows.

When Ar-2 is selected as Ar and isopropyl is selected as R, the repeating unit represented by the general formula (1) is shown as follows.

［式中、R₁は水素、置換または非置換のアルキル基、芳香族基およびヘテロ芳香族基から選択される置換基である。］ When Ar-3 is selected as Ar and an isopropyl group is selected as R, the repeating unit represented by the general formula (1) is shown as follows.

[Wherein R ₁ is a substituent selected from hydrogen, a substituted or unsubstituted alkyl group, an aromatic group and a heteroaromatic group. ]

Specific examples include the following repeating units.

［式中、R₁は水素、置換または非置換のアルキル基、芳香族基およびヘテロ芳香族基から選択される置換基である。］ When Ar-4 is selected as Ar and an isopropyl group is selected as R, the repeating unit represented by the general formula (1) is shown as follows.

[Wherein R ₁ is a substituent selected from hydrogen, a substituted or unsubstituted alkyl group, an aromatic group and a heteroaromatic group. ]

Specific examples include the following repeating units.

［式中、R₁は水素、置換または非置換のアルキル基、芳香族基およびヘテロ芳香族基から選択される置換基であり、ＸはＳまたはＯから選択される元素である。］ When Ar-5 is selected as Ar and isopropyl is selected as R, the repeating unit represented by the general formula (1) is shown as follows.

[Wherein R ₁ is a substituent selected from hydrogen, a substituted or unsubstituted alkyl group, an aromatic group and a heteroaromatic group, and X is an element selected from S and O. ]

Specific examples include the following repeating units.

［式中、R₁は水素、置換または非置換のアルキル基、芳香族基およびヘテロ芳香族基から選択される置換基である。］ When Ar-6 is selected as Ar and isopropyl is selected as R, the repeating unit represented by the general formula (1) is shown as follows.

[Wherein R ₁ is a substituent selected from hydrogen, a substituted or unsubstituted alkyl group, an aromatic group and a heteroaromatic group. ]

Specific examples include the following repeating units.

［式中、R₂は水素、ハロゲン元素、シアノ基および置換または非置換のアルキル基から選択される置換基であり、R₃は置換または非置換のアルキル基、置換または非置換のアルコキシ基、および置換または非置換の芳香族基から選択される置換基であり、ＸはＳまたはＯから選択される元素である。］ When Ar-7 is selected as Ar and an isopropyl group is selected as R, the repeating unit represented by the general formula (1) is shown as follows.

Wherein R ₂ is a substituent selected from hydrogen, a halogen element, a cyano group and a substituted or unsubstituted alkyl group, R ₃ is a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, And a substituent selected from a substituted or unsubstituted aromatic group, and X is an element selected from S or O. ]

Specific examples include the following repeating units.

  Among the above repeating units, a polymer containing a repeating unit represented by the above general formula (A-7) is preferred, and a polymer containing a repeating unit represented by the formula (A-7d) is more preferred.

These polymers of this embodiment may contain a crosslinking group. Preferably, in the repeating unit, at least one of R ₁ , R ₂ and R ₃ has a bridging group. The crosslinking group may be any substituent that causes a crosslinking reaction by light, heat, or a radical initiator. For example, examples of the cross-linking group that causes cross-linkage by decomposition by light include a substituent containing an alkyl group or an alkoxyl group substituted with bromine or iodine, and a substituent containing an azo group or a diazo group.

The crosslinking group may be a substituent containing a carbon-carbon double bond or triple bond that undergoes photodimerization by light, a substituent that undergoes a nucleophilic substitution reaction, or a substituent that undergoes an addition reaction by heat. Such bridging groups include anthranyl groups, cinnamoyl groups, substituents containing coumarin structures, phenylmaleimide groups, furfuryl acrylate groups, benzocyclobutanes, cyclopentadienyl groups, substituents having benzocyclobutane and sultin structures, and odors. Illustrative are halogenated alkyl groups such as alkyl halide groups and alkyl chloride groups. Further, the crosslinking group may be a substituent containing a carbon-carbon multiple bond such as an acryl group or a methacryl group as a substituent that reacts as a radical initiator. Specific examples of the repeating unit of the polymer having a crosslinking group are shown below. However, the polymer is not limited to the polymer containing the repeating units of the specific examples shown below.

  The polymer according to the embodiment preferably has a polystyrene-reduced weight average molecular weight (Mw) of 10,000 to 300,000 by gel permeation chromatography (GPC). In addition, the polymer of the embodiment preferably has a number average molecular weight (Mn) of 3,000 to 100,000.

[Photoelectric conversion element]
Next, the form in which the polymer according to the above embodiment is used for a photoelectric conversion element will be described below with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view of a photoelectric conversion element according to an embodiment. On the transparent substrate 6, the transparent electrode 1, the first buffer layer 2, the photoelectric conversion layer 3, the second buffer layer 4, and the back electrode 5 are laminated. The photoelectric conversion element according to the present embodiment has a photoelectric conversion layer containing at least one polymer of the above embodiment. In the embodiment, the first and second buffer layers are not essential and may be omitted. The transparent electrode 1 and the back electrode 5 become a cathode or an anode, respectively, and electrons or holes are taken out, respectively. The case where the transparent electrode is an anode is called a forward configuration, and the case where it is a cathode is called a reverse configuration. The embodiment may have either structure. The photoelectric conversion layer 3 is excited by light incident through the transparent substrate 6, the transparent electrode 1, and the first buffer layer 2, and distributes electrons and holes to the transparent electrode 1 and the back electrode 5, respectively. It is a layer to do. The first buffer layer 2 and the second buffer layer 4 are sandwiched between the photoelectric conversion layer and the cathode or anode.

  When using the electron donating material which is a polymer of this embodiment for a photoelectric conversion element, one type of polymer having the structure represented by the general formula (1) may be used, or two or more types may be used. Moreover, you may mix and use another polymer. When used as a photoelectric conversion element having a bulk heterostructure, an electron-accepting material known as an n-type material is preferably used together with a polymer having a structure represented by the general formula (1).

  As the electron acceptor, fullerene and its derivatives are preferably used. The fullerene derivative used here is not particularly limited as long as it is a derivative having a fullerene skeleton. Specific examples include derivatives containing C60, C70, C76, C78, C84 and the like as a basic skeleton. In the fullerene derivative, carbon atoms in the fullerene skeleton may be modified with an arbitrary functional group, and these functional groups may be bonded to each other to form a ring. Fullerene derivatives also include fullerene bonded polymers. A fullerene derivative having a functional group with high affinity for the solvent and high solubility in the solvent is preferred. Examples of the functional group in the fullerene derivative include (i) a hydrogen atom, (ii) a hydroxyl group, (iii) a halogen atom such as a fluorine atom and a chlorine atom, (iv) an alkyl group such as a methyl group and an ethyl group, and (v) Alkenyl groups such as vinyl groups, (vi) cyano groups, (vii) alkoxy groups such as methoxy groups, ethoxy groups, (viii) aromatic hydrocarbon groups such as phenyl groups, naphthyl groups, (ix) thienyl groups, pyridyl groups And aromatic heterocyclic groups such as

Specific examples of the fullerene _{derivative, C 60} H _36, C 70 hydrogenated fullerenes such as _{H 36,} oxide fullerenes a basic skeleton C60, C70, etc., fullerene metal complexes. Among the above-described compounds, it is particularly preferable to use 60PCBM ([6,6] -phenyl C61 butyric acid methyl ester) or 70PCBM ([6,6] -phenyl C71 butyric acid methyl ester) as the fullerene derivative. When using an unsubstituted fullerene, it is preferable to use C70. Fullerene C70 has high photocarrier generation efficiency and is suitable for use in organic thin-film solar cells. More preferably, a fullerene derivative is used as the electron-accepting material. The content ratio of the electron donor material and the electron acceptor material is preferably in the range of 1: 99-99: 1, more preferably in the range of 10: 90-90: 10, and even more preferably 20: 80-80: A range of 20.

  The constituent members of the photoelectric conversion element according to the embodiment will be described as follows.

(Transparent substrate 6)
The transparent substrate 6 is for supporting other components. It can be arbitrarily selected from those used in conventionally known photoelectric conversion elements. However, since incident light must pass through this transparent electrode and reach the photoelectric conversion layer, it must be transparent or translucent.

  The transparent substrate 6 is capable of forming an electrode on the surface thereof, and is preferably one that is not altered by heat or an organic solvent. The material of the transparent substrate 6 may be an inorganic material or an organic material. Examples of the inorganic material include alkali-free glass and quartz glass. Examples of the organic material include plastic materials such as polyethylene, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide, polyamide, polyamideimide, polyester, and polycycloolefin. These organic materials may be in the form of a liquid crystal polymer or a polymer film.

  The thickness of the substrate is not particularly limited as long as it has sufficient strength to support other components. For example, a flexible material can be used. Since the transparent substrate 6 is disposed on the light incident side, an antireflection film having a moth-eye structure, for example, can be provided on the light incident surface. By providing such an antireflection film, it is possible to efficiently capture incident light and improve the energy conversion efficiency of the photoelectric conversion element. Here, the moth-eye structure is a structure having a regular protrusion arrangement of about 100 nm on the surface. This projection structure changes the refractive index in the thickness direction continuously, so there is no discontinuous change in the refractive index by mediating a non-reflective film, reducing the reflection of light and converting the photoelectric conversion element Efficiency is improved.

(Transparent electrode 1)
The transparent electrode 1 may be transparent or translucent as long as it has conductivity to transmit light, and the material is not particularly limited. The transparent or translucent electrode material can be arbitrarily selected from materials used for conventionally known photoelectric conversion elements. Examples of such materials include conductive metal oxides and translucent metals. Specifically, indium oxide, zinc oxide, tin oxide (NESA), and their composites such as indium tin oxide (ITO), fluorine-doped tin oxide (FTO), indium zinc oxide (IZO), etc. Alternatively, gold, platinum, silver, copper or the like is used. In particular, ITO or FTO is preferable. Further, as an electrode material, polyaniline and a derivative thereof, which is an organic conductive polymer, polythiophene and a derivative thereof, or the like may be used.

  The transparent electrode can be produced by depositing these materials on the surface of the transparent substrate 6 by, for example, vacuum deposition, sputtering, ion plating, plating, coating, or the like.

  When the film thickness of the transparent electrode is an electrode made of, for example, ITO, the minimum film thickness is preferably 30 to 300 nm. When the minimum film thickness is 30 nm or more, the conductivity becomes sufficient and the photoelectric conversion efficiency tends to increase. On the other hand, when the minimum film thickness is 300 nm or less, the flexibility of the ITO film, which is a transparent electrode, increases, and cracks and the like tend not to occur even when stress is applied. The sheet resistance of the transparent electrode is preferably as low as possible, specifically 10Ω / □ or less. The transparent electrode may be a single layer, or may be a laminate of layers made of materials having different work functions. Furthermore, if necessary, a wire electrode can be combined with the transparent electrode layer.

(First buffer layer 2)
In the photoelectric conversion element according to the embodiment, a hole transport material may be used for the first buffer layer 2 in the case of the forward configuration. Examples of hole transport materials include polythiophene polymers, poly-p-phenylene vinylene polymers, polyfluorene polymers, polypyrrole polymers, polyaniline polymers, polyfuran polymers, polypyridine polymers, and polycarbazole polymers. Conductive polymers, phthalocyanine derivatives (H ₂ Pc, CuPc, ZnPc, etc.), porphyrin derivatives, low molecular organic compounds exhibiting p-type semiconductor properties such as acene compounds (tetracene, pentacene, etc.), graphene, graphene oxide, etc. Carbon compounds, molybdenum oxide such as MoO ₃ (MoO _x ), tungsten oxide such as WO ₃ (WO _x ), nickel oxide such as NiO (NiO _x ), vanadium oxide such as V ₂ O ₅ (VO _x ), ZrO ₂ zirconium oxide, such as _(ZrO x), _Cu 2 O Which copper oxide _(CuO x), copper iodide, ruthenium oxide, such as RuO ₄ (RuO _x), inorganic compounds such as rhenium oxide (ReO _x), such as Re ₂ O ₇ is preferably used. In particular, polyethylenedioxythiophene (PEDOT), which is a polythiophene polymer, PEDOT to which polystyrene sulfonate (PSS) is added, molybdenum oxide, vanadium oxide, and tungsten oxide are preferably used.

In the case of the reverse configuration, an electron transport material may be used for the first buffer layer 2. As the electron transporting material, alkali metal salts such as lithium, sodium, potassium, and cesium, and n-type oxide semiconductor compounds such as titanium oxide (TiO _x ) and zinc oxide (ZnO) are used. As the alkali metal salt, fluoride salts such as lithium fluoride, sodium fluoride, potassium fluoride and cesium fluoride are used. Organic materials can also be used, and materials such as polyethyleneimine are also used. The hole transport material and the electron transport material may be used alone or in combination of two or more. The thickness of the first buffer layer 2 is preferably 5 nm to 600 nm, more preferably 10 nm to 200 nm.

(Photoelectric conversion layer 3)
As described above, the photoelectric conversion layer uses an organic semiconductor material containing the polymer of the present embodiment or a mixture of an organic semiconductor material and an electron donating material. These organic semiconductor materials can be formed into a film by dissolving in a solvent to prepare a solution and applying the solution. Therefore, there is an advantage that a large-area organic thin film solar cell can be manufactured at low cost with inexpensive equipment by a printing method or the like. Preferably, the photoelectric conversion layer is a bulk hetero layer comprising at least one polymer of the above embodiment and a fullerene derivative.

  In order to apply the organic semiconductor material, it is necessary to dissolve in a solvent. Examples of the solvent used for the organic semiconductor material include (i) toluene, xylene, tetralin, decalin, mesitylene, n-butylbenzene, sec-butylbenzene, unsaturated hydrocarbon solvents such as tert-butylbenzene, (ii) halogenated aromatic hydrocarbons such as chlorobenzene, dichlorobenzene, trichlorobenzene, (iii) carbon tetrachloride, chloroform, dichloromethane, dichloroethane, chlorobutane, bromobutane, Halogenated saturated hydrocarbons such as chloropentane, chlorohexane, bromohexane and chlorocyclohexane, and (iv) ethers such as tetrahydrofuran and tetrahydropyran. In particular, a halogenated aromatic solvent is preferable. These solvents can be used alone or in combination.

  As a method of applying the solution, spin coating method, dip coating method, casting method, bar coating method, roll coating method, wire bar coating method, spray method, screen printing, gravure printing method, flexographic printing method, offset printing method, Examples include gravure offset printing, dispenser application, nozzle coating method, capillary coating method, and ink jet method. In the embodiment, these coating methods can be used alone or in combination.

In the embodiment, an organic-inorganic hybrid material having a perovskite structure can also be used for the photoelectric conversion layer. An organic-inorganic hybrid material having a perovskite structure is composed of ions A, B, and X, and can be represented by the chemical formula ABX3. When the ion B is smaller than the ion A, a perovskite structure may be taken. It has a cubic or tetragonal unit cell, A is arranged at each vertex of the cubic crystal, B is arranged at the body center, and X is arranged at each face center of the cubic crystal centering on this. The orientation of the BX6 octahedron is easily distorted by the interaction with A. Due to the decrease in symmetry, the Mott transition occurs and the valence electrons localized in the ions M can spread as a band. The ion A is preferably an alkylamine such as CH ₃ NH ₃ , the ion B is preferably Pb or Sn, and the ion X is preferably Cl, Br, or I. The ions A, B, and X constituting the perovskite structure may be single or mixed. Note that in this specification, a photoelectric conversion element using an organic-inorganic hybrid material having a perovskite structure in a photoelectric conversion layer is referred to as a perovskite photoelectric conversion element. The perovskite photoelectric conversion element according to the embodiment preferably uses a perovskite material for the photoelectric conversion layer, and includes at least one polymer of the above embodiment as a hole transport layer.

(Second buffer layer 4)
In the photoelectric conversion element according to the embodiment, in the case of the forward configuration, an electron transport material may be used for the second buffer layer 4. As the electron transporting material, alkali metal salts such as lithium, sodium, potassium and cesium, and n-type oxide semiconductor compounds such as titanium oxide (TiOx) and zinc oxide (ZnO) are used. As the alkali metal salt, fluoride salts such as lithium fluoride, sodium fluoride, potassium fluoride and cesium fluoride are used. Organic materials can also be used, and materials such as polyethyleneimine are also used.

In the case of the reverse configuration, a hole transport material may be used for the second buffer layer 4. Examples of hole transport materials include polythiophene polymers, poly-p-phenylene vinylene polymers, polyfluorene polymers, polypyrrole polymers, polyaniline polymers, polyfuran polymers, polypyridine polymers, and polycarbazole polymers. Conductive polymers, phthalocyanine derivatives (H ₂ Pc, CuPc, ZnPc, etc.), porphyrin derivatives, low molecular organic compounds exhibiting p-type semiconductor properties such as acene compounds (tetracene, pentacene, etc.), graphene, graphene oxide, etc. Carbon compounds, molybdenum oxide such as MoO ₃ (MoO _x ), tungsten oxide such as WO ₃ (WO _x ), nickel oxide such as NiO (NiO _x ), vanadium oxide such as V ₂ O ₅ (VO _x ), ZrO ₂ zirconium oxide, such as _(ZrO x), _Cu 2 O Which copper oxide _(CuO x), copper iodide, ruthenium oxide, such as RuO ₄ (RuO _x), inorganic compounds such as rhenium oxide (ReO _x), such as Re ₂ O ₇ is preferably used. In particular, molybdenum oxide, vanadium oxide, and tungsten oxide are preferably used.

  A single material may be used for the electron transport material and the hole transport material, or two or more materials may be mixed and used. The thickness of the second buffer layer 4 is preferably 1 nm to 600 nm.

(Back electrode 5)
The back electrode 5 is not particularly limited as long as it has conductivity. The back electrode is preferable in terms of light management because it can effectively use incident light by reflection or the like by using an opaque metal. By making the back electrode transparent or semi-transparent, it is also possible to produce a see-through photoelectric conversion element. Moreover, in order to take in light from the back electrode side, the back electrode can be formed of a transparent or translucent conductive material.

  Examples of the material for the opaque metal electrode include metals such as gold, silver, platinum, copper, manganese, titanium, cobalt, nickel, tungsten, and tin, or alloys containing them. Examples of the alloy include a lithium-aluminum alloy, a lithium-magnesium alloy, a lithium-indium alloy, a magnesium-silver alloy, a calcium-indium alloy, a magnesium-aluminum alloy, an indium-silver alloy, and a calcium-aluminum alloy. Examples of the transparent or translucent electrode material include conductive metal oxides and translucent metals. Specifically, indium oxide, zinc oxide, tin oxide (NESA), and their composites such as indium tin oxide (ITO), fluorine-doped tin oxide (FTO), indium zinc oxide (IZO), etc. Is used. Furthermore, organic substances such as a conductive polymer can also be used.

  The back electrode can be formed by, for example, a vacuum deposition method, a sputtering method, an ion plating method, a plating method, a coating method, or the like. Each film thickness is not particularly defined, but when an opaque metal electrode is used, the minimum film thickness is preferably 100 nm or more from the viewpoint of optical management. In the case of a transparent electrode, ITO or FTO is preferable. Further, as an electrode material, polyaniline and a derivative thereof, which is an organic conductive polymer, polythiophene and a derivative thereof, or the like may be used. For example, when ITO is used, the minimum film thickness is preferably 30 to 300 nm. By setting the minimum film thickness to 30 nm or more, high conductivity can be maintained, and photoelectric conversion efficiency can be improved. In addition, it is preferable that the minimum film thickness be 300 nm or less because the ITO film has sufficient flexibility, and cracks and the like are less likely to get angry even when stress is applied. The sheet resistance is preferably as low as possible, specifically 10Ω / □ or less. The back electrode may be a single layer or may be a laminate of layers made of materials having different work functions.

[Application of photoelectric conversion elements]
The photoelectric conversion element according to the embodiment can be applied to any conventionally known device. Typically, it can be used for solar cells, particularly organic thin film solar cells and perovskite solar cells. The photoelectric conversion element according to the embodiment can also be applied to an optical sensor, an imaging element, and the like. The image sensor can be formed by two-dimensionally arranging the photoelectric conversion elements according to the embodiment. In addition, photoelectric conversion elements can be arranged in one dimension and used for a scanner or the like.

  The present embodiment will be specifically described with reference to various examples. However, the present embodiment is not limited to these examples.

ソックスレー抽出で、酢酸エチル、ヘキサン、トルエンの順で精製した。以後、トルエン抽出成分を使用した。
［ ^１ Ｈ−ＮＭＲ（２７０ＭＨｚ，ＣＤＣｌ _３ ） ∂：７．６（ｂｒｏａｄ），−７．２（ｂｒｏａｄ）、４．４（ｂｒｏａｄ）、１．８−０．９（ｂｒｏａｄ）］
Ｍｗ＝３２，０００、Ｍｎ＝１５，０００（ＧＰＣ）
実施例１〜６のモノマーは文献 Ｄｙｅｓ ａｎｄ Ｐｉｇｍｅｎｔｓ ２０１４，１０９，８１−８９および特許第５４８２９７３号を参考に合成した。 [Synthesis of polymer having silylacetylene group as side chain]
Example 1
Synthesis of Polymer [P1] In a three-necked flask equipped with a three-way cock under a stream of argon, 422.3 g (0.5 mmol) of 4,8-bis-[(triisopropylsilanyl) -ethynyl] -2,6 -Bis-trimethylstannanyl-benzo [1,2-b; 4,5-b '] difuran, 236.1 g (0.5 mmol) of 4,6-dibromo-3-fluoro-thieno- [3,4 b] Thiophene-2-carboxylic acid octyl ester and 0.025 g of tetrakis (triphenylphosphine) palladium (catalyst) were weighed and subjected to vacuum degassing three times. Thereafter, 12 ml of toluene deaerated in a separate container and 3 ml of dimethylformamide were added from a three-way cock, and vacuum deaeration was further performed three times, followed by heating and refluxing at 120 ° C. for 12 hours. After cooling to room temperature, 361.4 g (1.5 mmol) of trimethylphenyltin was dissolved in 2.5 mL of degassed toluene, added from the three-way cock in the same manner as above, and heated under reflux for 2 hours. Further, after cooling to room temperature, 314.0 g (2.0 mmol) of bromobenzene was dissolved in 2.5 mL of degassed toluene and added from the three-way cock in the same manner as described above, followed by heating under reflux for 2 hours. After cooling to room temperature, the reaction solution was added dropwise to 500 mL of methanol while stirring to precipitate the polymer. Thereafter, the precipitate was filtered with a glass filter, dissolved in chloroform, and the catalyst was removed with a celite column. Furthermore, after concentrating a solvent with an evaporator, methanol was added, the polymer was precipitated, and it filtered using the glass filter, and obtained solid. This solid was vacuum-dried at 80 ° C. for 4 hours to obtain 393 g of a polymer having a metallic luster and having a repeating unit represented by the following formula.

Purification was performed in the order of ethyl acetate, hexane, and toluene by Soxhlet extraction. Thereafter, toluene extracted components were used.
[ ¹ H-NMR (270 MHz, CDCl ₃ ) ∂: 7.6 (broad), −7.2 (broad), 4.4 (broad), 1.8-0.9 (broad)]
Mw = 32,000, Mn = 15,000 (GPC)
The monomers of Examples 1 to 6 were synthesized with reference to documents Dyes and Pigments 2014, 109, 81-89 and Japanese Patent No. 5482973.

ソックスレー抽出で、酢酸エチル、ヘキサン、トルエンの順で精製した。以後、トルエン抽出成分を使用した。
［ ^１ Ｈ−ＮＭＲ（２７０ＭＨｚ，ＣＤＣｌ _３ ） ∂：７．６（ｂｒｏａｄ），７．２（ｂｒｏａｄ）、４．４（ｂｒｏａｄ）、１．８−０．９（ｂｒｏａｄ）］
Ｍｗ＝５３，０００、Ｍｎ＝２０，０００（ＧＰＣ） (Example 2)
Synthesis of polymer [P2] In place of 4,6-dibromo-3-fluoro-thieno- [3,4-b] thiophene-2-carboxylic acid octyl ester of Example 1, 4,6-dibromo-3- Fluoro-thieno- [3,4-b] thiophene-2-carboxylic acid A polymer containing a repeating unit represented by the following formula, which was synthesized under the same conditions as in Example 1 except that 2-ethyl-hexyl ester was used. 471 g was obtained.

Purification was performed in the order of ethyl acetate, hexane, and toluene by Soxhlet extraction. Thereafter, toluene extracted components were used.
[ ¹ H-NMR (270 MHz, CDCl ₃ ) ∂: 7.6 (broad), 7.2 (broad), 4.4 (broad), 1.8-0.9 (broad)]
Mw = 53,000, Mn = 20,000 (GPC)

ソックスレー抽出で、酢酸エチル、ヘキサン、トルエンの順で精製した。以後、トルエン抽出成分を使用した。
［ ^１ Ｈ−ＮＭＲ（２７０ＭＨｚ，ＣＤＣｌ _３ ） ∂：７．６（ｂｒｏａｄ），７．２（ｂｒｏａｄ）、２．３（ｂｒｏａｄ）、１．８−０．９（ｂｒｏａｄ）］
Ｍｗ＝５０，０００、Ｍｎ＝１８，０００（ＧＰＣ） (Example 3)
Synthesis of polymer [P3] In place of 4,6-dibromo-3-fluoro-thieno- [3,4-b] thiophene-2-carboxylic acid octyl ester of Example 1, 4,6-dibromo-3- Synthesis was carried out under the same conditions as in Example 1 except that fluoro-thieno- [3,4-b] thiophene-2-carboxylic acid 4-octylphenyl ester was used, and a polymer containing a repeating unit represented by the following formula was obtained. 527 g was obtained.

Purification was performed in the order of ethyl acetate, hexane, and toluene by Soxhlet extraction. Thereafter, toluene extracted components were used.
[ ¹ H-NMR (270 MHz, CDCl ₃ ) ∂: 7.6 (broad), 7.2 (broad), 2.3 (broad), 1.8-0.9 (broad)]
Mw = 50,000, Mn = 18,000 (GPC)

ソックスレー抽出で、酢酸エチル、ヘキサン、トルエンの順で精製した。以後、トルエン抽出成分を使用した。
［ ^１ Ｈ−ＮＭＲ（２７０ＭＨｚ，ＣＤＣｌ _３ ） ∂：７．６（ｂｒｏａｄ），−７．２（ｂｒｏａｄ）、４．４（ｂｒｏａｄ）、１．８−０．９（ｂｒｏａｄ）］
Ｍｗ＝４３，０００、Ｍｎ＝２４，０００（ＧＰＣ） Example 4
Synthesis of polymer [P4] In place of 4,6-dibromo-3-fluoro-thieno- [3,4-b] thiophene-2-carboxylic acid octyl ester of Example 1, 4,6-dibromo-3- The synthesis was performed under the same conditions as in Example 1 except that fluoro-thieno- [3,4-b] furan-2-carboxylic acid octyl ester was used, and 427 g of a polymer containing a repeating unit represented by the following formula was obtained. .

Purification was performed in the order of ethyl acetate, hexane, and toluene by Soxhlet extraction. Thereafter, toluene extracted components were used.
[ ¹ H-NMR (270 MHz, CDCl ₃ ) ∂: 7.6 (broad), −7.2 (broad), 4.4 (broad), 1.8-0.9 (broad)]
Mw = 43,000, Mn = 24,000 (GPC)

ソックスレー抽出で、酢酸エチル、ヘキサン、トルエンの順で精製した。以後、トルエン抽出成分を使用した。
［ ^１ Ｈ−ＮＭＲ（２７０ＭＨｚ，ＣＤＣｌ _３ ） ∂：７．６（ｂｒｏａｄ），７．２（ｂｒｏａｄ）、４．４（ｂｒｏａｄ）、１．８−０．９（ｂｒｏａｄ）］
Ｍｗ＝２５，０００、Ｍｎ＝１８，０００（ＧＰＣ） (Example 5)
Synthesis of polymer [P5] In place of 4,6-dibromo-3-fluoro-thieno- [3,4-b] thiophene-2-carboxylic acid octyl ester of Example 1, 4,6-dibromo-3- A polymer containing a repeating unit represented by the following formula, which was synthesized under the same conditions as in Example 1 except that fluoro-thieno- [3,4-b] furan-2-carboxylic acid 2-ethyl-hexyl ester was used. 412 g was obtained.

Purification was performed in the order of ethyl acetate, hexane, and toluene by Soxhlet extraction. Thereafter, toluene extracted components were used.
[ ¹ H-NMR (270 MHz, CDCl ₃ ) ∂: 7.6 (broad), 7.2 (broad), 4.4 (broad), 1.8-0.9 (broad)]
Mw = 25,000, Mn = 18,000 (GPC)

ソックスレー抽出で、酢酸エチル、ヘキサン、トルエンの順で精製した。以後、トルエン抽出成分を使用した。
［ ^１ Ｈ−ＮＭＲ（２７０ＭＨｚ，ＣＤＣｌ _３ ） ∂：７．６（ｂｒｏａｄ），７．２（ｂｒｏａｄ）、２．２（ｂｒｏａｄ）、１．８−０．９（ｂｒｏａｄ）］
Ｍｗ＝４３，０００、Ｍｎ＝１９，０００（ＧＰＣ） (Example 6)
Synthesis of polymer [P6]
Instead of 4,6-dibromo-3-fluoro-thieno- [3,4-b] thiophene-2-carboxylic acid octyl ester of Example 1, 4,6-dibromo-3-fluoro-thieno- [3 , 4-b] furan-2-carboxylic acid 4-octyl-phenyl ester was used under the same conditions as in Example 1 to obtain 522 g of a polymer containing a repeating unit represented by the following formula.

Purification was performed in the order of ethyl acetate, hexane, and toluene by Soxhlet extraction. Thereafter, toluene extracted components were used.
[ ¹ H-NMR (270 MHz, CDCl ₃ ) ∂: 7.6 (broad), 7.2 (broad), 2.2 (broad), 1.8-0.9 (broad)]
Mw = 43,000, Mn = 19000 (GPC)

ソックスレー抽出で、酢酸エチル、ヘキサン、トルエンの順で精製した。以後、トルエン抽出成分を使用した。
［ ^１ Ｈ−ＮＭＲ（２７０ＭＨｚ，ＣＤＣｌ _３ ） ∂：７．６（ｂｒｏａｄ），７．２（ｂｒｏａｄ）、２．８（ｂｒｏａｄ）、２．０−０．９（ｂｒｏａｄ）］
Ｍｗ＝６３，０００、Ｍｎ＝３４，０００（ＧＰＣ） (Example 7)
Synthesis of polymer [P7] In place of 4,6-dibromo-3-fluoro-thieno- [3,4-b] thiophene-2-carboxylic acid octyl ester of Example 1, 1,3-dibromo-5- Synthesis was performed under the same conditions as in Example 1 except that octyl-2,7-dithia-5-aza-cyclopenta [a] pentalene-4,6-dione was used, and a polymer containing a repeating unit represented by the following formula was used. 394 g was obtained.
The monomers of Examples 7 to 12 were synthesized with reference to the literature Macromolecules, 2013, 46 (10), 3861-3869.

Purification was performed in the order of ethyl acetate, hexane, and toluene by Soxhlet extraction. Thereafter, toluene extracted components were used.
[ ¹ H-NMR (270 MHz, CDCl ₃ ) ∂: 7.6 (broad), 7.2 (broad), 2.8 (broad), 2.0-0.9 (broad)]
Mw = 63,000, Mn = 34,000 (GPC)

ソックスレー抽出で、酢酸エチル、ヘキサン、トルエンの順で精製した。以後、トルエン抽出成分を使用した。
［ ^１ Ｈ−ＮＭＲ（２７０ＭＨｚ，ＣＤＣｌ _３ ） ∂：７．６（ｂｒｏａｄ），７．２（ｂｒｏａｄ）、２．８（ｂｒｏａｄ）、２．０−０．９（ｂｒｏａｄ）］
Ｍｗ＝５４，０００、Ｍｎ＝１９，０００（ＧＰＣ） (Example 8)
Synthesis of polymer [P8] In place of 4,6-dibromo-3-fluoro-thieno- [3,4-b] thiophene-2-carboxylic acid octyl ester of Example 1, 1,3-dibromo-5- Synthesis was performed under the same conditions as in Example 1 except that (4-ethyl-hexyl) -2,7-dithia-5-aza-cyclopenta [a] pentalene-4,6-dione was used. 521 g of a polymer containing repeating units was obtained.

Purification was performed in the order of ethyl acetate, hexane, and toluene by Soxhlet extraction. Thereafter, toluene extracted components were used.
[ ¹ H-NMR (270 MHz, CDCl ₃ ) ∂: 7.6 (broad), 7.2 (broad), 2.8 (broad), 2.0-0.9 (broad)]
Mw = 54,000, Mn = 19000 (GPC)

ソックスレー抽出で、酢酸エチル、ヘキサン、トルエンの順で精製した。以後、トルエン抽出成分を使用した。
［ ^１ Ｈ−ＮＭＲ（２７０ＭＨｚ，ＣＤＣｌ _３ ） ∂：７．６（ｂｒｏａｄ），７．２（ｂｒｏａｄ）、２．２（ｂｒｏａｄ）、１．７−０．９（ｂｒｏａｄ）］
Ｍｗ＝３１，０００、Ｍｎ＝１３，０００（ＧＰＣ） Example 9
Synthesis of polymer [P9] In place of 4,6-dibromo-3-fluoro-thieno- [3,4-b] thiophene-2-carboxylic acid octyl ester of Example 1, 1,3-dibromo-5- Synthesis was carried out under the same conditions as in Example 1 except that (4-octyl-phenyl) -2,7-dithia-5-aza-cyclopenta [a] pentalene-4,6-dione was used, and it was represented by the following formula. 570 g of a polymer containing repeating units was obtained.

Purification was performed in the order of ethyl acetate, hexane, and toluene by Soxhlet extraction. Thereafter, toluene extracted components were used.
[ ¹ H-NMR (270 MHz, CDCl ₃ ) ∂: 7.6 (broad), 7.2 (broad), 2.2 (broad), 1.7-0.9 (broad)]
Mw = 31,000, Mn = 13,000 (GPC)

ソックスレー抽出で、酢酸エチル、ヘキサン、トルエンの順で精製した。以後、トルエン抽出成分を使用した。
［ ^１ Ｈ−ＮＭＲ（２７０ＭＨｚ，ＣＤＣｌ _３ ） ∂：７．６（ｂｒｏａｄ），７．２（ｂｒｏａｄ）、２．７（ｂｒｏａｄ）、１．７−０．９（ｂｒｏａｄ）］
Ｍｗ＝７９，０００、Ｍｎ＝４４，０００（ＧＰＣ） (Example 10)
Synthesis of polymer [P10] In place of 4,6-dibromo-3-fluoro-thieno- [3,4-b] thiophene-2-carboxylic acid octyl ester of Example 1, 1,3-dibromo-5- The synthesis is performed under the same conditions as in Example 1 except that octyl-7-oxa-2-thia-5-aza-cyclopenta [a] pentalene-4,6-dione is used, and includes a repeating unit represented by the following formula. 453 g of polymer was obtained.

Purification was performed in the order of ethyl acetate, hexane, and toluene by Soxhlet extraction. Thereafter, toluene extracted components were used.
[ ¹ H-NMR (270 MHz, CDCl ₃ ) ∂: 7.6 (broad), 7.2 (broad), 2.7 (broad), 1.7-0.9 (broad)]
Mw = 79,000, Mn = 44,000 (GPC)

ソックスレー抽出で、酢酸エチル、ヘキサン、トルエンの順で精製した。以後、トルエン抽出成分を使用した。
［ ^１ Ｈ−ＮＭＲ（２７０ＭＨｚ，ＣＤＣｌ _３ ） ∂：７．６（ｂｒｏａｄ），７．２（ｂｒｏａｄ）、２．８（ｂｒｏａｄ）、１．７−１．０（ｂｒｏａｄ）］
Ｍｗ＝３２，０００、Ｍｎ＝１８，０００（ＧＰＣ） (Example 11)
Synthesis of polymer [P11] In place of 4,6-dibromo-3-fluoro-thieno- [3,4-b] thiophene-2-carboxylic acid octyl ester of Example 1, 1,3-dibromo-5- Synthesis was carried out under the same conditions as in Example 1 except that (2-ethyl-hexyl) -7-oxa-2-thia-5-aza-cyclopenta [a] pentalene-4,6-dione was used. 453 g of polymer containing the indicated repeating units were obtained.

Purification was performed in the order of ethyl acetate, hexane, and toluene by Soxhlet extraction. Thereafter, toluene extracted components were used.
[ ¹ H-NMR (270 MHz, CDCl ₃ ) ∂: 7.6 (broad), 7.2 (broad), 2.8 (broad), 1.7-1.0 (broad)]
Mw = 32,000, Mn = 18,000 (GPC)

ソックスレー抽出で、酢酸エチル、ヘキサン、トルエンの順で精製した。以後、トルエン抽出成分を使用した。
［ ^１ Ｈ−ＮＭＲ（２７０ＭＨｚ，ＣＤＣｌ _３ ） ∂：７．６（ｂｒｏａｄ），７．２（ｂｒｏａｄ）、２．２（ｂｒｏａｄ）、１．７−１．０（ｂｒｏａｄ）］
Ｍｗ＝４８，０００、Ｍｎ＝１８，０００（ＧＰＣ） (Example 12)
Synthesis of polymer [P12] In place of 4,6-dibromo-3-fluoro-thieno- [3,4-b] thiophene-2-carboxylic acid octyl ester of Example 1, 1,3-dibromo-5- Synthesis was carried out under the same conditions as in Example 1 except that (4-octyl-phenyl) -7-oxa-2-thia-5-aza-cyclopenta [a] pentalene-4,6-dione was used. 442 g of polymer containing the indicated repeating unit was obtained.

Purification was performed in the order of ethyl acetate, hexane, and toluene by Soxhlet extraction. Thereafter, toluene extracted components were used.
[ ¹ H-NMR (270 MHz, CDCl ₃ ) ∂: 7.6 (broad), 7.2 (broad), 2.2 (broad), 1.7-1.0 (broad)]
Mw = 48,000, Mn = 18,000 (GPC)

ソックスレー抽出で、酢酸エチル、ヘキサン、トルエンの順で精製した。以後、トルエン抽出成分を使用した。
［ ^１ Ｈ−ＮＭＲ（２７０ＭＨｚ，ＣＤＣｌ _３ ） ∂：７．７−７．５（ｂｒｏａｄ），７．２（ｂｒｏａｄ）、２．５（ｂｒｏａｄ）、１．７−１．１（ｂｒｏａｄ）］
Ｍｗ＝５８，０００、Ｍｎ＝３０，０００（ＧＰＣ） (Example 13)
Synthesis of polymer [P13] In place of 4,6-dibromo-3-fluoro-thieno- [3,4-b] thiophene-2-carboxylic acid octyl ester of Example 1, 4,6-dibromo-2- Synthesis was performed under the same conditions as in Example 1 except that (2-hexyl-decane-1-sulfonyl) -thieno [3,4-b] thiophene was used, and 489 g of a polymer containing a repeating unit represented by the following formula was obtained. It was.
The monomer of Example 13 was synthesized with reference to the literature Chemical Communications, 2011, 47, 8904-8906.

Purification was performed in the order of ethyl acetate, hexane, and toluene by Soxhlet extraction. Thereafter, toluene extracted components were used.
[ ¹ H-NMR (270 MHz, CDCl ₃ ) ∂: 7.7-7.5 (broad), 7.2 (broad), 2.5 (broad), 1.7-1.1 (broad)]
Mw = 58,000, Mn = 30,000 (GPC)

ソックスレー抽出で、酢酸エチル、ヘキサン、トルエンの順で精製した。以後、トルエン抽出成分を使用した。
［ ^１ Ｈ−ＮＭＲ（２７０ＭＨｚ，ＣＤＣｌ _３ ） ∂：７．６（ｂｒｏａｄ），７．２（ｂｒｏａｄ）、２．７（ｂｒｏａｄ）、２．０−１．１（ｂｒｏａｄ）］
Ｍｗ＝４２，０００、Ｍｎ＝１６，０００（ＧＰＣ） (Example 14)
Synthesis of polymer [P14] Instead of 4,6-dibromo-3-fluoro-thieno- [3,4-b] thiophene-2-carboxylic acid octyl ester of Example 1, 1,3-dibromo-5- The synthesis was performed under the same conditions as in Example 1 except that octyl-thieno [3,4-c] pyrrole-4,6-dione was used, and 532 g of a polymer containing a repeating unit represented by the following formula was obtained.
The monomers of Examples 14 to 16 were synthesized with reference to the document CHEMISTRY OF MATERIALS 2014, 26 (7), 2299-2306.

Purification was performed in the order of ethyl acetate, hexane, and toluene by Soxhlet extraction. Thereafter, toluene extracted components were used.
[ ¹ H-NMR (270 MHz, CDCl ₃ ) ∂: 7.6 (broad), 7.2 (broad), 2.7 (broad), 2.0-1.1 (broad)]
Mw = 42,000, Mn = 16,000 (GPC)

ソックスレー抽出で、酢酸エチル、ヘキサン、トルエンの順で精製した。以後、トルエン抽出成分を使用した。
［ ^１ Ｈ−ＮＭＲ（２７０ＭＨｚ，ＣＤＣｌ _３ ） ∂：７．６（ｂｒｏａｄ），７．２（ｂｒｏａｄ）、２．８（ｂｒｏａｄ）、２．０−１．０（ｂｒｏａｄ）］
Ｍｗ＝６２，０００、Ｍｎ＝２３，０００（ＧＰＣ） (Example 15)
Synthesis of polymer [P15] In place of 4,6-dibromo-3-fluoro-thieno- [3,4-b] thiophene-2-carboxylic acid octyl ester of Example 1, 1,3-dibromo-5- Synthesis was performed under the same conditions as in Example 1 except that (2-ethyl-hexyl) -thieno [3,4-c] pyrrole-4,6-dione was used, and a polymer containing a repeating unit represented by the following formula was used. 403 g was obtained.

Purification was performed in the order of ethyl acetate, hexane, and toluene by Soxhlet extraction. Thereafter, toluene extracted components were used.
[ ¹ H-NMR (270 MHz, CDCl ₃ ) ∂: 7.6 (broad), 7.2 (broad), 2.8 (broad), 2.0-1.0 (broad)]
Mw = 62,000, Mn = 23,000 (GPC)

ソックスレー抽出で、酢酸エチル、ヘキサン、トルエンの順で精製した。以後、トルエン抽出成分を使用した。
［ ^１ Ｈ−ＮＭＲ（２７０ＭＨｚ，ＣＤＣｌ _３ ） ∂：７．６（ｂｒｏａｄ），７．２（ｂｒｏａｄ）、２．２（ｂｒｏａｄ）、１．７−０．９（ｂｒｏａｄ）］
Ｍｗ＝６９，０００、Ｍｎ＝３９，０００（ＧＰＣ） (Example 16)
Synthesis of polymer [P16] In place of 4,6-dibromo-3-fluoro-thieno- [3,4-b] thiophene-2-carboxylic acid octyl ester of Example 1, 1,3-dibromo-5- Synthesis was performed under the same conditions as in Example 1 except that (4-octyl-phenyl) -thieno [3,4-c] pyrrole-4,6-dione was used, and a polymer containing a repeating unit represented by the following formula was used. 383 g was obtained.

Purification was performed in the order of ethyl acetate, hexane, and toluene by Soxhlet extraction. Thereafter, toluene extracted components were used.
[ ¹ H-NMR (270 MHz, CDCl ₃ ) ∂: 7.6 (broad), 7.2 (broad), 2.2 (broad), 1.7-0.9 (broad)]
Mw = 69,000, Mn = 39,000 (GPC)

ソックスレー抽出で、酢酸エチル、ヘキサン、トルエンの順で精製した。以後、トルエン抽出成分を使用した。
［ ^１ Ｈ−ＮＭＲ（２７０ＭＨｚ，ＣＤＣｌ _３ ） ∂：７．６（ｂｒｏａｄ），７．２（ｂｒｏａｄ）、７．０（ｂｒｏａｄ）、２．８（ｂｒｏａｄ）、１．７−０．９（ｂｒｏａｄ）］
Ｍｗ＝５７，０００、Ｍｎ＝２８，０００（ＧＰＣ） (Comparative Example 1)
Synthesis of polymer [CP1]
Instead of 4,6-dibromo-3-fluoro-thieno- [3,4-b] thiophene-2-carboxylic acid octyl ester of Example 1, except using 2,5-dibromo-3-hexyl-thiophene Was synthesized under the same conditions as in Example 1 to obtain 427 g of a polymer containing a repeating unit represented by the following formula.

Purification was performed in the order of ethyl acetate, hexane, and toluene by Soxhlet extraction. Thereafter, toluene extracted components were used.
[ ¹ H-NMR (270 MHz, CDCl ₃ ) ∂: 7.6 (broad), 7.2 (broad), 7.0 (broad), 2.8 (broad), 1.7-0.9 (broad ]]
Mw = 57,000, Mn = 28,000 (GPC)

ソックスレー抽出で、酢酸エチル、ヘキサン、トルエンの順で精製した。以後、トルエン抽出成分を使用した。
［ ^１ Ｈ−ＮＭＲ（２７０ＭＨｚ，ＣＤＣｌ _３ ） ∂：８．０（ｂｒｏａｄ），７．７（ｂｒｏａｄ）、４．３（ｂｒｏａｄ）、１．８−０．９（ｂｒｏａｄ）］
Ｍｗ＝３６，０００、Ｍｎ＝２２，０００（ＧＰＣ） (Comparative Example 2)
Synthesis of polymer [CP2] 4,8-bis-[(triisopropylsilanyl) -ethynyl] -2,6-bis-trimethylstannanyl-benzo [1,2-b; '] In place of difuran, 4,8-bis-[(triisopropylsilanyl) -ethynyl] -2,6-bis-trimethylstannanyl-1,5-dithia-s-indacene is used. Instead of dibromo-3-fluoro-thieno- [3,4-b] thiophene-2-carboxylic acid octyl ester, 4,6-dibromo-3-fluoro-thieno- [3,4-b] thiophene-2 -Carboxylic acid Synthesis was carried out under the same conditions as in Example 1 except that 2-ethyl-hexyl ester was used, and 555 g of a polymer containing a repeating unit represented by the following formula was obtained.
The monomer of Comparative Example 2 was synthesized with reference to the document “Jornar of Materials Chemistry, 2012, 22, 22224-22232”.

Purification was performed in the order of ethyl acetate, hexane, and toluene by Soxhlet extraction. Thereafter, toluene extracted components were used.
[ ¹ H-NMR (270 MHz, CDCl ₃ ) ∂: 8.0 (broad), 7.7 (broad), 4.3 (broad), 1.8-0.9 (broad)]
Mw = 36,000, Mn = 22,000 (GPC)

ソックスレー抽出で、酢酸エチル、ヘキサン、トルエンの順で精製した。以後、トルエン抽出成分を使用した。
［ ^１ Ｈ−ＮＭＲ（２７０ＭＨｚ，ＣＤＣｌ _３ ） ∂：７．６（ｂｒｏａｄ），７．２（ｂｒｏａｄ）、４．３（ｂｒｏａｄ）、２．５（ｂｒｏａｄ）、１．８−０．９（ｂｒｏａｄ）］
Ｍｗ＝５６，０００、Ｍｎ＝２４，０００（ＧＰＣ） (Comparative Example 3)
Synthesis of polymer [CP3] 4,8-bis-[(triisopropylsilanyl) -ethynyl] -2,6-bis-trimethylstannanyl-benzo [1,2-b; '] In place of difuran, 2,6-bis (trimethyltin) -4,8-bis (2-ethylhexyloxy) benzo [1,2-b; 4,5-b'] difuran is used, Instead of 6-dibromo-3-fluoro-thieno- [3,4-b] thiophene-2-carboxylic acid octyl ester, 4,6-dibromo-3-fluoro-thieno- [3,4-b] thiophene 2-Carboxylic acid Synthesis was carried out under the same conditions as in Example 1 except that 2-ethyl-hexyl ester was used, and 477 g of a polymer containing a repeating unit represented by the following formula was obtained. In the formula, R is a 2-ethylhexyl group.
The monomers of Comparative Examples 3 and 4 were synthesized with reference to the literature Macromolecules, 2012, 45 (17), 6923-6929.

Purification was performed in the order of ethyl acetate, hexane, and toluene by Soxhlet extraction. Thereafter, toluene extracted components were used.
[ ¹ H-NMR (270 MHz, CDCl ₃ ) ∂: 7.6 (broad), 7.2 (broad), 4.3 (broad), 2.5 (broad), 1.8-0.9 (broad ]]
Mw = 56,000, Mn = 24,000 (GPC)

ソックスレー抽出で、酢酸エチル、ヘキサン、トルエンの順で精製した。以後、トルエン抽出成分を使用した。
［ ^１ Ｈ−ＮＭＲ（２７０ＭＨｚ，ＣＤＣｌ _３ ） ∂：７．７−７．６（ｂｒｏａｄ），７．２（ｂｒｏａｄ）、６．８（ｂｒｏａｄ）、４．３（ｂｒｏａｄ）、２．８（ｂｒｏａｄ）、１．８−０．９（ｂｒｏａｄ）］
Ｍｗ＝６０，０００、Ｍｎ＝２６，０００（ＧＰＣ） (Comparative Example 4)
Synthesis of polymer [CP4] 4,8-bis-[(triisopropylsilanyl) -ethynyl] -2,6-bis-trimethylstannanyl-benzo [1,2-b; '] In place of difuran, 2,6-bis (trimethyltin) -4,8-bis (5- (2-ethylhexyl) thiophen-2-yl) -benzo [1,2-b; 4,5-b '] Difuran, and instead of 4,6-dibromo-3-fluoro-thieno- [3,4-b] thiophene-2-carboxylic acid octyl ester, 4,6-dibromo-3-fluoro-thieno- [3,4-b] thiophene-2-carboxylic acid Except that 2-ethyl-hexyl ester is used, the synthesis is performed under the same conditions as in Example 1, and a polymer containing a repeating unit represented by the following formula is represented by 496. Obtained. In the formula, R is a 2-ethylhexyl group.

Purification was performed in the order of ethyl acetate, hexane, and toluene by Soxhlet extraction. Thereafter, toluene extracted components were used.
[ ¹ H-NMR (270 MHz, CDCl ₃ ) ∂: 7.7-7.6 (broad), 7.2 (broad), 6.8 (broad), 4.3 (broad), 2.8 (broad) ), 1.8-0.9 (broad)]
Mw = 60,000, Mn = 26,000 (GPC)

[Production of photoelectric conversion element]
Photoelectric conversion elements were prepared using the polymers obtained in the above Examples and Comparative Examples (Examples 17 to 32, Comparative Examples 5 to 8). First, the polymers (P1 to P16) of Examples 1 to 16 which are p-type semiconductor materials and the polymers (CP1 to CP4) of Comparative Examples 1 to 4 are converted into 70PCBM ([6,6] -phenyl which is an n-type semiconductor material. C71 butyric acid methyl ester) was mixed so that the mass ratio was 1: 2. Next, the mixture was dissolved in chlorobenzene to which 1,8-diiodooctane was added in a nitrogen atmosphere so that the concentration of the mixture was 16.0 mg / mL in a nitrogen atmosphere. This was stirred and mixed for 1 hour at a temperature of 120 ° C. using a hot stirrer to obtain an activator coating solution.

A glass substrate having an ITO electrode (first electrode) formed by sputtering was prepared. A ZnO precursor solution is spin-coated in a nitrogen atmosphere on the ITO electrode forming surface of a glass substrate and dried under the condition of 150 ° C. × 5 minutes in the atmosphere to thereby form a ZnO film (electron transport layer) having a thickness of 15 nm. Formed. Next, the activator coating solution in which the p-type semiconductor material and the n-type semiconductor material are dissolved is spin-coated using a syringe equipped with a 0.20 μm polytetrafluoroethylene (PTFE) filter to thereby obtain a thickness. A bulk heterojunction photoelectric conversion layer of about 100 nm was formed. Next, a V ₂ O ₅ film (hole transport layer) having a thickness of 2 nm and an Ag film (second electrode) having a thickness of 100 nm are formed on the photoelectric conversion layer by a vapor deposition method, so that the power generation area is 1 cm square. A photoelectric conversion element was prepared.

A 1 cm square metal mask is attached to the solar cell element thus manufactured, and SPECTR solar simulator-IVP0605 (trade name) manufactured by Asahi Spectroscopic Co., Ltd. with an air mass (AM) of 1.5 G and an irradiance of 100 mW / cm ² is used as an irradiation light source. Using, the current-voltage characteristic between the ITO electrode and the silver electrode was measured. Table 1 shows open circuit voltage (Voc), short circuit current density (Jsc), fill factor (FF), and conversion efficiency as measurement results.

As is clear from Table 1, the photoelectric conversion element using the polymer of the example has a higher open circuit voltage than the comparative example. Therefore, for example, when a solar cell including this photoelectric conversion element is mounted on a small device, an electromotive force necessary for the device can be obtained with a small series junction, that is, with a smaller installation area.

[Preparation of perovskite photoelectric conversion elements]
Using the polymers of Examples 2, 8 and 15 as hole transport layers, perovskite photoelectric conversion elements were prepared (Examples 33 to 35).

First, lead iodide (PbI ₂ ) and methylammonium iodide (CH ₃ NH ₄ I) are mixed at a molar ratio of 1: 1, and this mixture is mixed with dimethyl in a nitrogen atmosphere so that the concentration becomes 40% by mass. Dissolved in formamide. This solution was stirred and mixed at a temperature of 120 ° C. for 1 hour using a hot stirrer to obtain an active layer coating solution of a perovskite compound.

  The polymers of Examples 2, 8 and 15 (P2, P8 and P15), which are p-type semiconductor materials, were dissolved in chlorobenzene in a nitrogen atmosphere so as to have a concentration of 16.0 mg / mL. These solutions were stirred and mixed at a temperature of 120 ° C. for 1 hour using a hot stirrer. The solution after stirring and mixing was cooled to room temperature, and then filtered through a 0.20 μm PTFE filter to obtain a hole transport layer coating solution using each polymer.

A glass substrate on which a fluorine-doped tin oxide (FTO) transparent conductive film is patterned is cleaned in the order of ultrasonic cleaning with a surfactant, water with ultrapure water, and ultrasonic cleaning with ultrapure water. It dried and heat-dried at 120 degreeC in air | atmosphere for 5 minutes. Finally, ultraviolet ozone cleaning was performed on the substrate. This substrate was spin-coated with an ethanol solution of titanium diisopropoxide bis (acetylacetone), heated at 450 ° C. for 30 minutes, and then cooled. This substrate was immersed in an aqueous solution of titanium chloride (TiCl ₄ ) at 70 ° C. for 30 minutes. The substrate taken out of the aqueous solution was washed and dried, and then heated in air at 500 ° C. for 20 minutes to form an electron transport layer having a thickness of about 20 nm. The perovskite compound active layer coating solution prepared above was filtered on a substrate on which an electron transport layer was formed with a syringe equipped with a 0.45 μm polytetrafluoroethylene (PTFE) filter at a rate of 600 rpm in a nitrogen atmosphere. A photoelectric conversion layer having a thickness of about 300 nm was formed by spin coating and drying at 70 ° C. for about 30 minutes. On the photoelectric conversion layer, the hole transport layer was formed by spin-coating the prepared polymer hole transport layer coating solution at a speed of 2000 rpm. Thereafter, gold having a thickness of 100 nm was formed as an electrode layer by resistance heating vacuum deposition. Thus, a 1 cm square perovskite photoelectric conversion element (organic / inorganic hybrid solar cell element) was produced.

(Comparative Example 5)
A perovskite photoelectric conversion element was produced in the same manner as in Example 33 except that poly (3-hexylthiophene-2,5-diyl) (P3HT) was used as a material for forming the hole transport layer.

[Evaluation of perovskite photoelectric conversion elements]
A 1 cm square metal mask is attached to a perovskite photoelectric conversion element (organic / inorganic hybrid solar cell element), SPECTR solar simulator-IVP0605 manufactured by Asahi Spectroscopic Co., Ltd. with an air mass (AM) of 1.5 G and an irradiance of 100 mW / cm ² as an irradiation light source. Using (trade name), the current-voltage characteristics between the FTO electrode and the Au electrode were measured. Table 2 shows open circuit voltage (Voc), short circuit current density (Jsc), fill factor (FF), and conversion efficiency as measurement results.

Further, the perovskite photoelectric conversion element was sealed with glass, heated on a hot plate in a nitrogen atmosphere at 90 ° C. for 15 minutes, and then cooled to room temperature. Similar characteristics were measured after the heating test to determine the deterioration rate. Table 2 shows the deterioration rate of the characteristics before and after heating. When spiro-OMeTAD + Li-TFSI was used as the hole transport layer, the deterioration rate exceeded 70%.

Claims (12)

A polymer comprising a repeating unit represented by the following general formula (1), comprising a benzodifuran structure having a silylacetylene group as a side chain and a condensed heterocyclic structure.

[Wherein, R is independently of one another a substituent selected from hydrogen, a substituted or unsubstituted alkyl group, an aromatic group and a heteroaromatic group, and Ar is a substituted or unsubstituted condensed heterocyclic structure. As shown, the condensed heterocyclic ring in the condensed heterocyclic structure and the condensed heterocyclic ring in the benzodifuran structure are directly bonded. ] The polymer of claim 1, wherein Ar is selected from a fused heterocyclic structure of the formula

Wherein R ₁ is a substituent selected from hydrogen, a substituted or unsubstituted alkyl group, an aromatic group and a heteroaromatic group, and R ₂ is hydrogen, a halogen, a cyano group and a substituted or unsubstituted alkyl R ₃ is a substituent selected from a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, and a substituted or unsubstituted aromatic group, and X is S Or it is an element selected from O. ] The polymer according to claim 1, comprising a repeating unit represented by the following general formula (A-7).

[Wherein R ₂ is a substituent selected from hydrogen, halogen, cyano group and substituted or unsubstituted alkyl group, R ₃ is a substituted or unsubstituted alkyl group, substituted or unsubstituted alkoxy group, and A substituent selected from a substituted or unsubstituted aromatic group, and X is an element selected from S or O; ] The polymer according to claim 3, wherein R ₂ is fluorine. The polymer according to claim 3 or 4, wherein R ₃ is a 2-ethylhexyloxy group. The polymer according to claim 1, comprising a repeating unit represented by the following formula (A-7d).

  The polymer according to any one of claims 1 to 6, wherein the polymer contains a crosslinking group. The polymer according to claim 2, wherein in the repeating unit, at least one of R ₁ , R ₂ and R ₃ has a crosslinking group.   It has a photoelectric converting layer containing at least 1 sort (s) as described in any one of Claims 1-8, The photoelectric conversion element characterized by the above-mentioned. The photoelectric conversion layer
At least one polymer according to any one of claims 1 to 8,
It is a bulk hetero layer containing a fullerene derivative, The photoelectric conversion element characterized by the above-mentioned. Using a perovskite material for the photoelectric conversion layer,
A perovskite photoelectric conversion element comprising the polymer according to any one of claims 1 to 8 as a hole transport layer.   A solar cell comprising the photoelectric conversion element according to any one of claims 9 to 11.

Images