JP6441196B2 - Polymer and solar cell using the same - Google Patents

Description

  The present invention relates to a polymer compound, an organic thin-film solar cell and an organic-inorganic hybrid solar cell using the polymer compound.

The organic semiconductor is expected to be applied to solar cell elements such as organic thin film solar cells, light emitting elements, and optical sensors. Among these, if polymer molecules are used as the organic semiconductor material, the active layer can be produced by an inexpensive coating method. On the other hand, due to the problem of energy and CO ₂ emission reduction, solar cells are rapidly growing as one of clean energy with little environmental load. Currently, silicon-based solar cells are the mainstream, but the efficiency is around 15%, and it is difficult to reduce the cost. A CdTe solar cell is also known as a solar cell that can be manufactured at low cost. However, since Cd, which is a toxic element, is used, environmental problems may occur. Under such circumstances, there is an increasing expectation for the development of organic thin-film solar cells and organic-inorganic hybrid solar cells, which are low-cost, high energy conversion efficiency and harmless next-generation solar cells.

  One of the challenges of organic thin film solar cells is to improve power generation efficiency. In order to improve the power generation efficiency, it is important to improve the open circuit voltage (Voc). The open-circuit voltage of an organic solar cell greatly depends on the combination of an electron donating material and an electron accepting material, and it is necessary to optimize the material used. It is known that the open-circuit voltage of an organic thin-film solar cell correlates with the difference between the energy level of the highest occupied molecular orbital (HOMO) of the p-type material and the energy level of the lowest unoccupied molecular orbital of the n-type material. . In organic thin film solar cell research currently being promoted all over the world, fullerenes (for example, PCBM) are considered to be optimal as n-type semiconductor materials. On the other hand, the most commonly used P-type semiconductor material is a polythiophene conjugated polymer (for example, P3HT (poly (3-hexylthiophene-2,5-diyl))).

  The open voltage of an organic thin film solar cell combining PCBM and P3HT is as low as about 0.6 V, which is not always satisfactory from a practical viewpoint, and further improvement is desired. As a method for improving the open circuit voltage value, a means for lowering the HOMO level of the P-type semiconductor material can be considered. However, in this case, the band gap of the P-type semiconductor is widened and light in a long wavelength region cannot be absorbed. That is, the light absorption efficiency on the long wavelength side in the visible light region is reduced, and incident light cannot be used effectively. As a result, there is room for improvement because the energy efficiency does not increase.

  As described above, the open-circuit voltage and the light absorption in the long wavelength region often have a trade-off relationship, and it has been difficult to achieve both at a higher level.

Recently, in order to improve the open circuit voltage, it has been proposed to use a polymer in which imide is fused to thiophene as a p-type material. However, in that case, although the open circuit voltage is improved to 0.85 V, the conversion efficiency is only about 0.75%, and further improvement is desired.
Another problem with organic thin-film solar cells is extending their life. For this purpose, it has been reported that an active substance (donor and acceptor) having high stability to light is required.

  Furthermore, recently, an organic-inorganic hybrid solar cell having high energy conversion efficiency using an organic-inorganic hybrid perovskite compound and an inorganic perovskite compound in the photoelectric conversion layer has been studied. In order to achieve high efficiency in this organic-inorganic hybrid solar cell, as a hole transport layer, spiro-OMeTAD, polyarylamine, t-butylpyridine (hereinafter sometimes referred to as TBP), bis (trifluoromenanesulfonyl) imide lithium Combining a dopant agent such as (hereinafter sometimes referred to as Li-TFSI) has been studied. However, TBP is a liquid, and performance degradation and shortening of the life due to diffusion and dissipation to the photoelectric conversion layer due to temperature rise are likely to occur. In addition, since Li-TFSI is deliquescent, it tends to absorb water molecules and degrade performance, shortening the life. Therefore, there is room for improvement in these as well.

  Moreover, although it has been reported that P3HT of a p-type polymer is used as the hole transport layer, there is a problem that power generation efficiency is not sufficient.

JP 2011-168747 A WO 2010/008672 specification JGB No. 2008/066933 Specification

Adv. Mater. 2012, 24, 580 Jin Hyuck Heo, Nature Photonics vol. 7,2013,486-491 Journal of Polymer Science: Part A: Polymer Chemistry), 2001, Vol. 39, p. 1533-1 Adv. Mater. 18,572 (2006) Sol-Gel Science, C.I. J. et al. Brinker, G.M. W. Scherer, Academic Press (1990)

  In view of such problems, the present embodiment aims to provide a polymer for achieving both a high open-circuit voltage and a long life in an organic thin-film solar cell and a perovskite organic-inorganic hybrid solar cell. . And this embodiment is excellent in film forming property, and also has an organic thin film solar cell provided with a photoelectric conversion layer using a polymer that can realize a high open-circuit voltage with fullerenes, as well as excellent film forming property and high It is another object of the present invention to provide an organic-inorganic hybrid solar cell including a hole transport layer using a polymer capable of realizing efficiency and durability.

The polymer according to the embodiment has the following formulas (1) to (4):
(Where
R ¹ and R ² are each independently hydrogen, unsubstituted alkyl group, substituted alkyl group, unsubstituted alkoxy group, substituted alkoxy group, unsubstituted acyl group, substituted acyl group, unsubstituted aryl group, substituted aryl group, unsubstituted A group selected from the group consisting of a heteroaryl group and a substituted heteroaryl group, wherein R ¹ and R ² are not simultaneously hydrogen and X ¹ and X ² are each independently a group consisting of O, S, and Se An atom selected from
Ar is a divalent unsubstituted conjugated unsaturated bond group or a substituted conjugated unsaturated bond group)
It contains at least one type of repeating unit selected from the group consisting of.

  The solar cell according to the embodiment includes the polymer.

  In addition, the bulk hetero-type organic thin film solar cell according to the embodiment includes an active layer including the polymer as an electron donor and a fullerene derivative as an electron acceptor.

  In addition, the organic-inorganic hybrid solar cell according to the embodiment includes a hole transport layer including the polymer and a photoelectric conversion layer including an organic-inorganic perovskite structure.

Sectional drawing of the solar cell element which concerns on embodiment of this invention.

  Hereinafter, this embodiment will be described in detail.

The polymer according to the embodiment includes a specific repeating unit. This repeating unit is represented by the following formulas (1) to (4).
In the formula, each of R ¹ and R ² independently represents hydrogen, an unsubstituted alkyl group, a substituted alkyl group, a substituted alkoxy group, an unsubstituted acyl group, a substituted acyl group, an unsubstituted aryl group, a substituted aryl group, or an unsubstituted heteroaryl. And a group selected from the group consisting of a substituted heteroaryl group. The unsubstituted alkyl group, substituted alkyl group, unsubstituted alkoxy group, substituted alkoxy group, unsubstituted acyl group, substituted acyl group, and unsubstituted acyl group preferably have 1 to 30 carbon atoms, an unsubstituted aryl group, The substituted aryl group, unsubstituted heteroaryl group, and substituted heteroaryl group preferably have 2 to 30 carbon atoms. R ¹ and R ² may be bonded to each other to form a cyclic structure.

Here, R ¹ and R ² are not hydrogen at the same time. Incidentally, the polymer according to the present embodiment, by R ¹ and R ² are not simultaneously hydrogen, lower solubility in polar solvents. For this reason, separation and purification are facilitated during production, industrial production is easy, and mass production is also possible.

X ¹ and X ² are each independently an atom selected from the group consisting of O, S, and Se.

  Ar is a divalent unsubstituted conjugated unsaturated bond group or a substituted conjugated unsaturated bond group.

  The molecular weight of these polymers is not particularly limited, but the weight average molecular weight is preferably 3,000 to 1,000,000, and more preferably 10,000 to 400,000. Here, the weight average molecular weight is a polystyrene equivalent weight average molecular weight by gel permeation chromatography.

Specific examples of the repeating unit represented by formula (1) and formula (2) include the following. However, the repeating unit contained in the polymer according to the embodiment is not limited thereto. In the formula, Bu represents a butyl group, Ph represents a phenyl group, 2-EH represents a 2-ethylhexyl group, Et represents an ethyl group, Oct represents an octyl group, and Hex represents a hexyl group.

  In addition, specific examples of the formulas (3) and (4) are obtained by adding a conjugated unsaturated bond group Ar to the above repeating units of the formula (1) or (2). What is used as a donor unit in the usual organic semiconductor polymer generally used can also be used as Ar.

Specific examples of Ar are listed below, but are not limited thereto. In the formula, R is hydrogen, halogen, cyano group, nitro group, substituted amino group, unsubstituted alkylthio group, substituted alkylthio group, unsubstituted alkyl group, substituted alkyl group, unsubstituted alkoxy group, substituted alkoxy group, unsubstituted It is a group selected from the group consisting of an acyl group, a substituted acyl group, an unsubstituted aryl group, a substituted aryl group, an unsubstituted heteroaryl group, and a substituted heteroaryl group.

Furthermore, although the specific example of the repeating unit contained in the polymer by embodiment is shown, it is not limited. In the formula, n is a number representing the degree of polymerization, a number of 2 or more, 2-HD represents a 2-hexyldecyl group, and 2-ODod represents a 2-octyldodecyl group.

  Moreover, although the polymer by embodiment contains the said repeating unit, it may contain the other repeating unit. However, the ratio of the repeating units represented by the above formulas (1) to (4) with respect to the total number of moles of the repeating units contained in the polymer is 50 mol% or more so that the effects of the present embodiment are more remarkably exhibited. It is preferable that

Moreover, it is preferable that the polymer of embodiment contains a crosslinking group. This cross-linking group may be contained in the end group of the main chain of the polymer, or any substituent of R ¹ , R ² , or Ar may be a cross-linking group.

Such a polymer is represented by the following formulas (1A) to (4A), for example.
In the formula, R ¹ and R ² are each independently hydrogen, unsubstituted alkyl group, substituted alkyl group, unsubstituted alkoxy group, substituted alkoxy group, unsubstituted acyl group, substituted acyl group, unsubstituted aryl group, substituted aryl. A group selected from the group consisting of a group, an unsubstituted heteroaryl group, and a substituted heteroaryl group. The unsubstituted alkyl group, substituted alkyl group, unsubstituted alkoxy group, substituted alkoxy group, unsubstituted acyl group, substituted acyl group, and unsubstituted acyl group preferably have 1 to 30 carbon atoms, an unsubstituted aryl group, The substituted aryl group, unsubstituted heteroaryl group, and substituted heteroaryl group preferably have 2 to 30 carbon atoms. R ¹ and R ² may be bonded to each other to form a cyclic structure. R ^t is a group selected from the group consisting of hydrogen, halogen elements, unsubstituted aryl groups, substituted aryl groups, unsubstituted heteroaryl groups, and substituted heteroaryl groups.

Here, R ¹ and R ² are not hydrogen at the same time.

X ¹ and X ² are each independently an atom selected from the group consisting of O, S, and Se.

  Ar is a divalent unsubstituted conjugated unsaturated bond group or a substituted conjugated unsaturated bond group.

  p is a number of 2 or more.

The polymer represented by the formula (1A) ~ (4A) ^is, R 1, ^{R 2,} and ^{R t} one of includes a crosslinking group. The number of cross-linking groups contained in the polymer may be one or more. For example, only two R ^t at both ends of the polymer may contain a cross-linking group, or a part of R ¹ of the repeating unit contains a cross-linking group. It may be.

  The crosslinking group is not particularly limited as long as it is a substituent that can undergo a crosslinking reaction with light, heat, a radical initiator, or the like. For example, as a crosslinking group in which a bond is decomposed by light to cause crosslinking, there are a substituent having an alkyl or alkoxy group substituted with bromine or iodine, a substituent having an azo and diazo group, and the like.

  In addition, there is a cross-linking group having a carbon-carbon double bond or triple bond that causes (2 + 2) photodimerization by light, for example, an anthranyl group. In addition, there are benzocyclobutane, cyclopentadienyl group, cinnamoyl group, substituents having a coumarin structure, phenylmaleimide group, furfurylacrylate group, acetylene group, etc., as radical groups that cause an addition reaction by heat, radical initiation Examples of the crosslinking group that reacts as an agent include a substituent having a carbon-carbon multiple bond, such as an acryl group and a methacryl group. In addition, any cross-linking group can be used, and is not limited to those described above.

Although the specific example of the polymer which has a crosslinking group is given to the following, it is not necessarily limited to it.

Examples of the polymer according to the embodiment include polymers represented by the following formulas (1B) to (4B).
In the formula, R ¹ , R ² , R ¹ ′ and R ² ′ are each independently hydrogen, unsubstituted alkyl group, substituted alkyl group, unsubstituted alkoxy group, substituted alkoxy group, unsubstituted acyl group, substituted acyl group. , An unsubstituted aryl group, a substituted aryl group, an unsubstituted heteroaryl group, and a substituted heteroaryl group. The unsubstituted alkyl group, substituted alkyl group, unsubstituted alkoxy group, substituted alkoxy group, unsubstituted acyl group, substituted acyl group, and unsubstituted acyl group preferably have 1 to 30 carbon atoms, an unsubstituted aryl group, The substituted aryl group, unsubstituted heteroaryl group, and substituted heteroaryl group preferably have 2 to 30 carbon atoms. R ¹ and R ² , or R ¹ ′ and R ² ′ may be bonded to each other to form a cyclic structure.

Here, R ¹ and R ² are not hydrogen at the same time. R ¹ ′ and R ² ′ may be hydrogen at the same time or may not be hydrogen at the same time.

X ¹ and X ² , X ¹ ′ and X ² ′ are each independently an atom selected from the group consisting of O, S and Se.

  Ar and Ar ′ are a divalent unsubstituted conjugated unsaturated bond group or a substituted conjugated unsaturated bond group.

  q and q ′ are numbers satisfying 0.01 ≦ q ′ / (q + q ′) ≦ 0.5.

The polymer represented by the formula (1B) ~ (4B) ^{is, R 1, R 2, R} 1 ', R 2' in any one of and polymer end include a crosslinking group. The crosslinkable group contained in the polymer may be one or more.

  As a crosslinking group, the same thing as what was described about Formula (1A)-(4A) can be used.

Although the specific example of the polymer of Formula (1B)-(4B) below is given, it is not necessarily limited to it.

<Polymer synthesis method>
The polymer according to the embodiment may be synthesized by any method. For example, after synthesizing a monomer having a functional group suitable for the polymerization reaction, the monomer is dissolved in an organic solvent as necessary, and an alkali, a catalyst, It can synthesize | combine by superposing | polymerizing using the well-known aryl coupling reaction using a ligand etc. Examples of the polymerization by the aryl coupling reaction include Stille coupling, Suzuki coupling reaction, polymerization by direct aryl coupling, and the like.

  Stille coupling uses a palladium complex as a catalyst, adds a ligand as necessary, and a monomer having a trialkyltin residue and a monomer having a halogen atom such as a bromine atom, an iodine atom or a chlorine atom. Polymerization to be reacted. Examples of the radium complex include palladium [tetrakis (triphenylphosphine)], [tris (dibenzylideneacetone)] dipalladium, palladium acetate, and bis (triphenylphosphine) palladium dichloride.

  Details of the polymerization by the Stille coupling reaction are described in, for example, Patent Document 2. Examples of the solvent used in the Stille coupling reaction include toluene, xylene, N, N-dimethylacetamide, N, N-dimethylformamide, and organic solvents such as a mixed solvent obtained by mixing two or more of these solvents. However, the solvent is not limited to these. The solvent used in the Stille coupling reaction is preferably deoxygenated before the reaction in order to suppress side reactions.

  Polymerization by Suzuki coupling reaction uses a palladium complex or nickel complex as a catalyst in the presence of an inorganic base or an organic base, and a ligand is added as necessary to have a boronic acid residue or a boric acid ester residue. Polymerization in which a monomer is reacted with a monomer having a halogen atom such as a bromine atom, an iodine atom or a chlorine atom, or a monomer having a sulfonate group such as a trifluoromethanesulfonate group or a p-toluenesulfonate group.

  In the polymerization by direct aryl coupling reaction, a palladium complex or a palladium salt is used as a catalyst in the presence of an inorganic base or an organic base, a ligand is added as necessary, a substituted aryl group monomer, a bromine atom, an iodine atom , Polymerization in which a monomer having a halogen atom such as a chlorine atom is reacted.

  Examples of the solvent used for Suzuki and the direct aryl coupling reaction include organic solvents such as toluene, xylene, N, N-dimethylacetamide, N, N-dimethylformamide, and a mixed solvent obtained by mixing two or more of these solvents. It is done. However, the solvent is not limited to these. The solvent used in these coupling reactions is preferably subjected to deoxygenation before the reaction in order to suppress side reactions.

  Examples of the inorganic base include sodium carbonate, potassium carbonate, cesium carbonate, tripotassium phosphate, and potassium fluoride. Examples of the organic base include tetrabutylammonium fluoride, tetrabutylammonium chloride, tetrabutylammonium bromide, and tetraethylammonium hydroxide. Examples of the palladium complex include palladium [tetrakis (triphenylphosphine)], [tris (dibenzylideneacetone)] dipalladium, palladium acetate, and bis (triphenylphosphine) palladium dichloride. Examples of the nickel complex include bis (cyclooctadiene) nickel. Examples of the ligand include triphenylphosphine, tri (2-methylphenyl) phosphine, tri (2-methoxyphenyl) phosphine, diphenylphosphinopropane, tri (cyclohexyl) phosphine, and tri (tert-butyl) phosphine. It is done.

  Details of the polymerization by the Suzuki coupling reaction are described in Non-Patent Document 3, for example. In the polymerization by the aryl coupling reaction, a solvent is usually used. The solvent may be selected in consideration of the polymerization reaction used, the solubility of the monomer and polymer, and the like. Specifically, tetrahydrofuran, toluene, 1,4-dioxane, dimethoxyethane, N, N-dimethylacetamide, N, N-dimethylformamide, an organic solvent such as a mixed solvent obtained by mixing two or more of these solvents, an organic solvent Examples thereof include a solvent having two phases of a phase and an aqueous phase. Solvents used in the Suzuki coupling reaction are organic solvents such as tetrahydrofuran, toluene, 1,4-dioxane, dimethoxyethane, N, N-dimethylacetamide, N, N-dimethylformamide, and mixed solvents in which two or more of these solvents are mixed. A solvent and a solvent having two phases of an organic solvent phase and an aqueous phase are preferred. The solvent used for the Suzuki coupling reaction is preferably deoxygenated before the reaction in order to suppress side reactions.

  The lower limit of the reaction temperature of the aryl coupling reaction is preferably −100 ° C., more preferably −20 ° C., and particularly preferably 0 ° C. from the viewpoint of reactivity. The upper limit of the reaction temperature is preferably 200 ° C., more preferably 150 ° C., and particularly preferably 120 ° C. from the viewpoint of the stability of the monomer and the polymer compound.

  In the polymerization by the aryl coupling reaction, a known method may be used as a method for taking out the polymer according to the embodiment from the reaction solution after completion of the reaction. For example, the polymer according to the embodiment can be obtained by adding a reaction solution to lower alcohol such as methanol, filtering the deposited precipitate, and drying the filtrate. When the purity of the obtained polymer compound is low, it can be purified by recrystallization, continuous extraction with a Soxhlet extractor, column chromatography, or the like.

The polymer according to the embodiment can be synthesized using, for example, a Stille coupling reaction. For example, it can be synthesized by polymerizing a dihalogen compound represented by the formulas (M1) and (M2) and a bis (trialkyl) tin represented by the formula (MA).

R ¹ and R ² are each independently hydrogen, unsubstituted alkyl group, substituted alkyl group, unsubstituted alkoxy group, substituted alkoxy group, unsubstituted acyl group, substituted acyl group, unsubstituted aryl group, substituted aryl group, unsubstituted It is a group selected from the group consisting of a heteroaryl group and a substituted heteroaryl group. The unsubstituted alkyl group, substituted alkyl group, unsubstituted alkoxy group, substituted alkoxy group, unsubstituted acyl group, substituted acyl group, and unsubstituted acyl group preferably have 1 to 30 carbon atoms, an unsubstituted aryl group, The substituted aryl group, unsubstituted heteroaryl group, and substituted heteroaryl group preferably have 2 to 30 carbon atoms. R ¹ and R ² may be bonded to each other to form a cyclic structure. Here, R ¹ and R ² are not hydrogen at the same time.

X ¹ and X ² are each independently an atom selected from the group consisting of O, S, and Se.

  Ar is a divalent unsubstituted conjugated unsaturated bond group or a substituted conjugated unsaturated bond group.

  Y is a halogen atom, for example, represented by Cl, Br, or I. Each Y may be the same or different.

Examples of the compounds represented by the formulas (M1) and (M2) include, but are not limited to, the following compounds.

  Examples of the compound represented by the formula (MA) include, but are not limited to, the following compounds.

In the formula, R is hydrogen, halogen, cyano group, nitro group, substituted amino group, unsubstituted alkylthio group, substituted alkylthio group, unsubstituted alkyl group, substituted alkyl group, unsubstituted alkoxy group, substituted alkoxy group, unsubstituted acyl group , A substituted acyl group, an unsubstituted aryl group, a substituted aryl group, an unsubstituted heteroaryl group, and a substituted heteroaryl group,
R ^′ is a group selected from the group consisting of unsubstituted alkyl groups and may be the same or different.

Specific examples of such monomers are as follows.

Furthermore, although the following specific compounds can be illustrated, it is not necessarily limited to these.

Furthermore, as a monomer that is a raw material of a polymer having a crosslinking group at the end of the polymer main chain, a general formula
R ^t -Y
R ^t —SnR ′ ₃
The thing represented by is mentioned.

Here, R ^t is an unsubstituted alkyl group, a substituted alkyl group, an unsubstituted alkoxy group, a substituted alkoxy group, an unsubstituted acyl group, a substituted acyl group, an unsubstituted aryl group, a substituted aryl group, an unsubstituted heteroaryl group, and A group selected from the group consisting of substituted heteroaryl groups and having an optional bridging group;
R ^′ is an alkyl group, for example, a methyl group, an ethyl group, a butyl group, an octyl group,
Y is a halogen atom, for example, represented by Cl, Br, or I. Each Y may be the same or different.

Further, as the crosslinking group contained in ^Rt , any substituent can be selected as long as it can undergo a crosslinking reaction with light, heat, and a radical initiator. Specifically, those described above can be used. Specific examples of such monomers are given below.

Furthermore, what is represented by a following formula (M1-1)-a formula (M1-3) can be used as a monomer with a crosslinking group.
In formulas (M1-1) and (M1-2), R ¹ ″ and R ² ″ each independently represent hydrogen, an unsubstituted alkyl group, a substituted alkyl group, an unsubstituted alkoxy group, a substituted alkoxy group, or unsubstituted A bridging group from the group consisting of an acyl group, a substituted acyl group, an unsubstituted aryl group, a substituted aryl group, an unsubstituted heteroaryl group, and a substituted heteroaryl group. Here, the unsubstituted alkyl group, the substituted alkyl group, the unsubstituted alkoxy group, the substituted alkoxy group, the unsubstituted acyl group, and the substituted acyl group preferably have 1 to 30 carbon atoms, and the unsubstituted aryl group and the substituted aryl group The unsubstituted heteroaryl group and the substituted heteroaryl group preferably have 2 to 30 carbon atoms.

  Ar is a group selected from the group consisting of an unsubstituted aryl group, a substituted aryl group, an unsubstituted heteroaryl group, and a substituted heteroaryl group.

X ¹ and X ² are each independently an atom selected from the group consisting of O, S, and Se.

  Y is a halogen atom, for example, represented by Cl, Br, or I. Each Y may be the same or different.

Such monomers include, but are not limited to, the following compounds:

Moreover, although the polymer by embodiment was shown to synthesize | combine with Stille couplingin, it can manufacture also by another coupling reaction. For example, in the method of synthesizing a polymer using the Suzuki coupling reaction, for example, a compound represented by formulas (M1) and (M2) and a compound represented by the following formula (MB) are polymerized as monomers. Can be synthesized.
Q-Ar-Q (MB)
In the formula (MB), Q represents a boric acid ester residue. A boric acid ester residue means a group obtained by removing a hydroxy group from a boric acid diester, and specific examples thereof include groups represented by the following formulas, but are not limited thereto.
(In the formula, Me represents a methyl group, and Et represents an ethyl group.)
The synthesis catalyst can be synthesized by dissolving the above monomer in a solvent, adding a ligand or base as an additive of a palladium complex or a palladium salt, and heating in an inert gas atmosphere.

  As another method, the production of the polymer by direct aryl coupling includes the dihalogen-substituted monomer represented by the formula (M1), the formula (M2) and the formula (MC), and the monomer represented by the formula (M1 ′) and (M2 ′). And a substituted aryl monomer represented by (MD) is used for polymer synthesis. Moreover, as a polymerization catalyst, a ligand, a base, etc. are added as an additive of a palladium complex or a palladium salt, and it can synthesize | combine by heating in inert gas atmosphere.

Here, the dihalogen-substituted monomer is represented by the following formula (MC).
Y-Ar-Y (MD)
here,
Ar is a divalent unsubstituted conjugated unsaturated bond group or a substituted conjugated unsaturated bond group,
Y is a halogen atom, for example, represented by Cl, Br, or I, and is preferably Br. Each Y may be the same or different.

The monomer represented by the formula (MD) is represented by the following formula, for example.

The substituted aryl monomer is represented by the following formula (MD).
H-Ar-H (MD)
Here, Ar is a divalent unsubstituted conjugated unsaturated bond group or a substituted conjugated unsaturated bond group. Monomers (M1 ′) and (M2 ′) used in accordance with this are represented by the following formulae. (

R ¹ and R ² are each independently hydrogen, unsubstituted alkyl group, substituted alkyl group, unsubstituted alkoxy group, substituted alkoxy group, unsubstituted acyl group, substituted acyl group, unsubstituted aryl group, substituted aryl group, unsubstituted It is a group selected from the group consisting of a heteroaryl group and a substituted heteroaryl group.

X ¹ and X ² are each independently an atom selected from the group consisting of O, S, and Se.

Examples of such monomers include, but are not limited to, the following compounds:

<Solar cell>
The photoelectric conversion element included in the solar cell according to the embodiment includes at least an active layer between a pair of electrodes. Below, one Embodiment of the photoelectric conversion element which concerns on embodiment is described.

<Organic thin film solar cell>
In the present embodiment, the active layer includes the polymer and the n-type semiconductor material shown below.
FIG. 1 shows a solar cell element 100 according to an embodiment. FIG. 1 shows a solar cell element used in a general organic thin film solar cell, but the solar cell element according to the embodiment is not limited to the structure shown in FIG. The solar cell element 100 of FIG. 1 includes an electrode 120 and an electrode 160, and an active layer 140. Furthermore, as shown in FIG. 1, the solar cell element according to this embodiment may include at least one of a substrate 110 and buffer layers 130 and 150. In FIG. 1, the electrode 120 is an electrode that collects holes (hereinafter also referred to as an anode), and the electrode 160 is an electrode that collects electrons (hereinafter also referred to as a cathode). is there. Of course, in another embodiment according to the present invention, the anode 120 and the cathode 160 may be reversed, and in this case, the buffer layer 130 and the buffer layer 150 may be reversed. Hereinafter, each of these parts will be described.

<Active layer (140)>
The active layer 140 of the solar cell element 100 according to the present embodiment includes the aforementioned polymer and an n-type semiconductor material. Hereinafter, the n-type semiconductor material (electron-accepting compound) compound (I) and compound (II) will be described in detail. In the present embodiment, the polymer functions as a p-type semiconductor material. In the present embodiment, the active layer 140 may include a plurality of types of p-type semiconductor materials. Similarly, in the present embodiment, the active layer 140 may include a plurality of types of n-type semiconductor materials.

<N-type semiconductor material>
Examples of the n-type semiconductor material compound included in the active layer of the photoelectric conversion element according to the embodiment include a phthalocyanine derivative, a fullerene derivative, a boron-containing polymer, and poly (benzobisimidazobenzophenanthroline) as a type semiconductor material (electron-accepting compound). Among them, fullerene derivatives are preferable, and specific examples of fullerene derivatives include 1 ′, 1 ″, 4 ′, 4 ″ -Tetrahydro-di [1,4] methanaphathaleno [1, 2: 2 ′, 3 ′, 56, ₆₀ : 2 ″, 3 ″] [5,6] fullrene-C ₆₀ (indene-C ₆₀ bis adduct; IC60BA), [6,6] -Phenyl C ₆₁ butyric acid methyl ester (PC60BM), [6,6] -Ph enyl C ₇₁ butyric acid methyl ester (PC70BM), Dihyrdonaptyl-based [60] fullerene biducts (NC60BA, Dihydrodonatyl-based [70]

<Configuration and structure of active layer>
In order to efficiently transfer electrons from an electron donor (p-type semiconductor) to an electron acceptor (n-type semiconductor), the LUMO energy level is related to the p-type semiconductor material and the n-type semiconductor material. is important. Specifically, the LUMO energy level of the p-type semiconductor material is preferably higher than the LUMO energy level of the n-type semiconductor material by a predetermined energy. In other words, it is preferable that the electron affinity of the p-type semiconductor material is larger than the electron affinity of the n-type semiconductor material by a predetermined energy.

  If the LUMO energy level of the n-type semiconductor material is too high, electron movement is difficult to occur, and thus the short-circuit current (Jsc) of the photoelectric conversion element 100 tends to be low. On the other hand, the open circuit voltage (Voc) of the photoelectric conversion element 100 is determined by the difference between the HOMO energy level of the p-type semiconductor material and the LUMO energy level of the n-type semiconductor material. Therefore, when the LUMO of the n-type semiconductor material is too low, Voc tends to be low. That is, in order to achieve higher conversion efficiency, it is not necessary to simply select an n-type semiconductor material having a high or low LUMO energy level.

  In the aforementioned polymer, the LUMO energy level can be adjusted by selecting the substituent. That is, compounds having various energy levels can be obtained by changing substituents of two types of monomers constituting the copolymer. In order to obtain monomers having various substituents, well-known techniques such as esterification, etherification, and cross coupling can be used.

  However, a suitable combination of a p-type semiconductor material and an n-type semiconductor material is not determined based solely on the LUMO energy level and the HOMO energy level.

  As described above, the active layer 140 of the photoelectric conversion element 100 according to this embodiment includes the polymer that is a p-type semiconductor material and an n-type semiconductor material. In the solar cell element 100, light is absorbed by the active layer 140, charge separation occurs at the interface between the p-type semiconductor and the n-type semiconductor, and the generated electron holes and hole electrons are extracted from the electrodes 120 and 160. . The thickness of the active layer is not particularly limited, but the thickness of the active layer is preferably 10 nm to 1000 nm, and more preferably 50 nm to 350 nm. When the thickness of the active layer is 10 nm or more, the uniformity of the layer is maintained, and it becomes difficult to cause a short circuit. Further, when the thickness of the active layer is 1000 nm or less, the internal resistance can be reduced, and further, the distance between the electrodes can be shortened so that the charge diffusion can be improved.

  Specific structures of the active layer include a thin film stack type in which a p-type semiconductor layer and an n-type semiconductor layer are stacked, and a bulk heterojunction type in which a p-type semiconductor material and an n-type semiconductor material are mixed. . The thin film stacked active layer may have a layer (i layer) in which a p-type semiconductor material and an n-type semiconductor material are mixed between a p-type semiconductor layer and an n-type semiconductor layer. In particular, the photoelectric conversion element 100 according to this embodiment preferably includes a bulk heterojunction active layer 140 in which a p-type semiconductor material and an n-type semiconductor material are mixed.

  The bulk heterojunction active layer contains a p-type semiconductor material and an n-type semiconductor material. In the active layer, the p-type semiconductor and the n-type semiconductor are phase-separated from each other. When the active layer absorbs light, positive charges (holes) and negative charges (electrons) are separated at these phase interfaces and transported to the electrodes through the semiconductor. In the bulk heterojunction active layer, the phase separation structure has an influence on the light absorption process, the exciton diffusion process, the exciton dissociation process (charge generation process), the carrier transport process, and the like. Therefore, in order to increase the photoelectric conversion efficiency of the photoelectric conversion element, it is necessary to optimize the phase separation structure between the p-type semiconductor and the n-type semiconductor in the active layer.

<Method for forming active layer>
Although there is no restriction | limiting in particular in the formation method of the active layer 140, It is preferable to form by wet coating methods, such as a spin coat method, an inkjet method, a doctor blade method, a drop casting method. In this case, a semiconductor material, a solvent in which the polymer and the n-type semiconductor are soluble are selected, a coating liquid containing the polymer and the n-type semiconductor compound is prepared, and the coating liquid is applied to Layer 140 is formed.

  The type of the solvent is not particularly limited as long as it can dissolve the semiconductor material uniformly. For example, aliphatic hydrocarbons such as hexane, heptane, octane, isooctane, nonane, decane; toluene, xylene, chlorobenzene, orthodi Aromatic hydrocarbons such as chlorobenzene; lower alcohols such as methanol, ethanol, and propanol; ketones such as acetone, methyl ethyl ketone, cyclopentanone, and cyclohexanone; esters such as ethyl acetate, butyl acetate, and methyl lactate; chloroform, chloride Halogen hydrocarbons such as methylene, dichloroethane, trichloroethane, and trichloroethylene; ethers such as ethyl ether, tetrahydrofuran, and dioxane; amides such as dimethylformamide and dimethylacetamide It can be selected.

<Additive to active layer coating solution>
Patent Document 3 describes that when a bulk heterojunction active layer is formed by a coating method, photoelectric conversion efficiency may be improved by adding a low molecular weight compound to the coating solution. A plurality of factors can be considered as the mechanism by which the phase separation structure is optimized by the additive and the photoelectric conversion efficiency is improved. The present inventor considered that one of the factors is that aggregation of p-type semiconductor materials or n-type semiconductor materials is suppressed by the presence of the additive. That is, when there is no additive, the solvent of the active layer coating liquid (ink) usually evaporates immediately after coating. At this time, the p-type semiconductor and the n-type semiconductor remaining as residual components can each form a large aggregate. In such a case, since the junction area (area of the interface) between the p-type semiconductor and the n-type semiconductor is reduced, the charge generation efficiency can be reduced.

  On the other hand, when an ink containing an additive is applied, the additive remains for a while after the solvent volatilizes. That is, since the additive is present around the p-type semiconductor, the n-type semiconductor, or both of them, aggregation of the p-type semiconductor and / or the n-type semiconductor can be prevented. It is considered that the additive evaporates at a very slow speed under normal temperature and pressure after ink application. Although the p-type semiconductor material and the n-type semiconductor material are considered to aggregate as the additive evaporates, the aggregate formed by the p-type semiconductor material and the n-type semiconductor material because the remaining additive prevents aggregation. Is considered to be smaller. As a result, a phase separation structure having a large junction area between the p-type semiconductor and the n-type semiconductor and higher charge generation efficiency can be formed in the active layer.

  Based on the mechanism of action described above, the present inventor considered that the boiling point of the additive greatly affects the effect. That is, it is preferable that the additive remains in the active layer for a while after the main solvent of the ink volatilizes. From this viewpoint, the boiling point of the additive is preferably higher than the main solvent of the ink. Since the boiling points of chlorobenzene and orthodichlorobenzene often used as the main solvent of the ink are 131 ° C. and 181 ° C., respectively, the boiling point of the additive at normal pressure (1000 hPa) is preferably higher than these. From the same viewpoint, the vapor pressure of the additive is preferably lower than the vapor pressure of the main solvent of the ink at normal temperature (25 ° C.).

  On the other hand, when the boiling point of the additive is too high, it is assumed that the amount of the additive remaining inside the active layer increases without completely leaving the active layer even after the photoelectric conversion element is manufactured. In such a case, the increase in impurities may cause a decrease in mobility, that is, a decrease in photoelectric conversion efficiency. Therefore, it is also preferable that the boiling point of the additive is not too high.

  From the above viewpoint, the boiling point of the additive at normal pressure is 10 ° C. or more and 200 ° C. or less than the boiling point of the main solvent. Preferably, 50 ° C. or more and 100 ° C. is more preferable than the boiling point of the main solvent. If the boiling point of the additive is too low, the n-type semiconductor material tends to aggregate particularly when the ink is dried, the morphology of the active layer becomes large, and the surface can be uneven. Further, it is preferable that the additive is liquid at normal temperature (25 ° C.) from the viewpoint of easy ink preparation. When the additive is solid at room temperature, it may be difficult to dissolve the additive in the main solvent at the time of ink preparation, or it may take a long stirring time even if it can be dissolved. However, if the additive is liquid, such a concern is not necessary.

  However, in order to optimize the phase separation structure, not only the boiling point of the additive but also the compatibility of the additive with the p-type semiconductor material and the n-type semiconductor material to be used is important. That is, since the additive can interact with the p-type semiconductor material and the n-type semiconductor material, the crystallinity of the p-type semiconductor material and the n-type semiconductor material can change depending on the structure of the additive, for example.

  Examples of the additive include an alkane having a substituent and an aromatic compound such as naphthalene having a substituent. Examples of substituents include aldehyde groups, oxo groups, hydroxy groups, alkoxy groups, thiol groups, thioalkyl groups, carboxyl groups, ester groups, amine groups, amide groups, fluoro groups, chloro groups, bromo groups, iodo groups, halogen groups, Nitrile group, epoxy group, aromatic group, arylalkyl group and the like. There may be one or more, for example two, substituents. A preferred substituent for the alkane is a thiol group or an iodo group. Moreover, as a substituent which an aromatic compound like naphthalene has, Preferably, they are a bromo group or a chloro group. Since the additive preferably has a high boiling point as described above, the alkane has preferably 6 or more carbon atoms, more preferably 8 or more. Further, since the additive is preferably liquid at normal temperature as described above, the carbon number of the alkane is preferably 14 or less, and more preferably 12 or less.

The amount of the additive contained in the ink (active layer coating solution) is more preferably 0.1% by weight or more and 10% by weight or more based on the whole ink. Further, it is more preferably 0.5% by weight or more and 3% by weight or less based on the whole ink. When the amount of the additive is within this range, a preferable phase separation structure can be obtained while reducing the additive remaining in the active layer.
As described above, by applying the ink (coating liquid) containing the polymer and n-type semiconductor containing the repeating unit represented by the formulas (1) to (24) and the additive, that is, by the coating method, The active layer 140 of the solar cell element 100 according to the present embodiment can be formed.

<Electrodes (120, 160)>
The electrodes 120 and 160 according to the present embodiment have a function of collecting holes or electrons generated when the active layer 140 absorbs light. Therefore, one electrode 120 is preferably an electrode suitable for collecting electrons, and the other electrode 160 is preferably an electrode suitable for collecting holes.

  At least one of the pair of electrodes 120 and 160 is preferably translucent, and both may be translucent. Translucency means that sunlight passes through 40% or more. In addition, it is preferable that the translucent electrode transmits sunlight by 70% or more in order to allow light to reach the active layer 140 through the transparent electrode. The light transmittance can be measured with a normal spectrophotometer, and can be an average transmittance for visible light (400 nm to 800 nm), for example.

  Specific examples of the materials for the electrodes 120 and 160 will be given below. But at least one of the electrode 120 and the electrode 160 may be comprised with the some material, for example, may be comprised by the laminated structure of two or more layers. In addition, characteristics (electric characteristics, wetting characteristics, etc.) may be improved by performing a surface treatment on the materials listed below.

<Electrode (cathode) 120 suitable for collecting electrons>
An electrode (cathode) suitable for collecting electrons is generally an electrode made of a conductive material having a work function lower than that of an anode. Such a cathode 120 can smoothly extract electrons generated in the active layer 140.

  Examples of the material of the cathode 120 include, for example, metals such as lithium, sodium, potassium, cesium, calcium and magnesium and alloys thereof; inorganic salts such as lithium fluoride and cesium fluoride; nickel oxide, aluminum oxide, lithium oxide and Examples thereof include metal oxides such as cesium oxide. Since these materials have a low work function, they are preferable as materials for the cathode 120.

  Further, the cathode 120 may be provided with a buffer layer 130 between the cathode 120 and the active layer 140. For example, when an n-type semiconductor such as titania having conductivity is used as the buffer layer 130, a material having a high work function can also be used as the material of the cathode 120. From the viewpoint of electrode protection, the cathode 120 is preferably made of a metal such as platinum, gold, silver, copper, iron, tin, aluminum, and indium, or an alloy using these metals.

  When the cathode electrode is a transparent electrode, a light-transmitting conductive metal oxide such as ITO, zinc oxide or tin oxide is preferably used as the cathode material, and ITO is particularly preferably used.

  The film thickness of the cathode 120 is not particularly limited, but is 10 nm or more and 10 μm or less, preferably 50 nm or more and 500 nm or less. If the film thickness of the cathode 120 is too thin, the sheet resistance increases, and if it is too thick, the light transmittance decreases. When the cathode 120 is a transparent electrode, it is preferable to select a film thickness so that both high light transmittance and low sheet resistance can be obtained. The sheet resistance of the cathode 120 is not particularly limited, but is 500Ω / □ or less, preferably 200Ω / □ or less. Although there is no restriction on the lower limit, it is usually 1Ω / □ or more. From the viewpoint of extracting a larger current, the sheet resistance is preferably small.

  Examples of the method for forming the cathode 120 include a vacuum film formation method such as vapor deposition and sputtering, and a method for forming a film by applying an ink containing nanoparticles and a precursor.

<Electrode (anode) 160 suitable for collecting holes>
An electrode (anode) suitable for collecting holes is generally an electrode made of a conductive material having a work function higher than that of the cathode. Such an anode 160 can smoothly extract holes generated in the active layer 140.

  Examples of the material of the anode 160 include metals such as gold, platinum, silver, chromium, cobalt, and alloys thereof. These materials are preferred because they have a high work function. These materials include conductive polymer materials such as PEDOT / PSS in which polythiophene derivatives are doped with polystyrene sulfonic acid, and metal oxides with high work functions such as molybdenum oxide, vanadium oxide, nickel oxide, and copper oxide. Since a thing can be laminated | stacked, it is preferable. For example, a buffer layer 150 made of such a conductive polymer and metal oxide can be provided between the active layer 140 and the anode 160. On the other hand, the conductive polymer material itself can be used as the material of the anode 160. Examples of the conductive polymer material include the above-described PEDOT / PSS, materials obtained by doping polypyrrole, polyaniline, and the like with iodine or the like.

  When the anode electrode is a transparent electrode, a light-transmitting conductive metal oxide such as ITO, zinc oxide, or tin oxide is preferably used as the material for the anode 160, and in particular, ITO is preferably used. .

  The thickness of the anode 160 is not particularly limited, but is 10 nm or more and 1 μm or less, preferably 50 nm or more and 300 nm or less. If the film thickness of the anode 120 is too thin, the sheet resistance increases, and if it is too thick, the light transmittance decreases. When the anode 120 is a transparent electrode, it is preferable to select a film thickness so that both high light transmittance and low sheet resistance can be obtained. The sheet resistance 120 of the anode is not particularly limited, but is usually 1Ω / □ or more and 500Ω / □ or less, preferably 200Ω / □ or less. From the viewpoint of extracting a larger current, the sheet resistance is preferably small.

  A method for forming the anode 160 includes a vacuum film formation method such as vapor deposition and sputtering, and a method for forming a film by applying ink containing nanoparticles and a precursor. Here, the precursor is a compound that is converted into a material suitable for the anode 160 by performing a conversion treatment after coating.

<Buffer layer (130, 150)>
The solar cell element 100 according to the present embodiment can further include one or more buffer layers in addition to the pair of electrodes 120 and 160 and the active layer 140 disposed therebetween. The buffer layer can be classified into an electron extraction layer 130 and a hole extraction layer 150. In general, the electron extraction layer 130 is disposed between the active layer 140 and the cathode 120, and the hole extraction layer 150 is disposed between the active layer 140 and the cathode 160.

<Hole extraction layer (150)>
The material of the hole extraction layer 150 is not particularly limited as long as it can improve the efficiency of extracting holes from the active layer 140 to the anode 160. Specifically, a conductive polymer obtained by doping polythiophene, polypyrrole, polyacetylene, triphenylenediamine polypyrrole, polyaniline, or the like with a doping material such as at least one of sulfonic acid and iodine can be given. Among them, a conductive polymer doped with sulfonic acid is preferable, and PEDOT: PSS in which a polythiophene derivative is doped with polystyrene sulfonic acid is more preferable.

  In addition, a metal oxide having a high work function such as molybdenum oxide, vanadium oxide, nickel oxide, or copper oxide can also be used for the hole extraction layer 150. A thin film such as a metal may be used alone as the hole extraction layer 150. Further, a thin film such as a metal and the above conductive polymer can be combined to be used as the hole extraction layer 150.

  The thickness of the hole extraction layer is not particularly limited, but is usually 1 nm or more and 200 nm or less. Preferably it is 5 nm or more, and 100 nm or less is more preferable. If it is too thin, the uniformity is not sufficient and a short circuit tends to occur, and if it is too thick, the resistance value tends to increase and it becomes difficult to extract holes.

<Electron extraction layer (130)>
The material of the electron extraction layer 130 is not particularly limited as long as the efficiency of extracting electrons from the active layer 140 to the cathode 120 can be improved. The electron extraction layer material is roughly divided into an inorganic compound and an organic compound. As the electron extraction layer, only one of these materials or both materials may be used. For example, a stacked body of an inorganic compound layer and an organic compound layer may be used as the electron extraction layer 130.

  Examples of inorganic compound materials used for the electron extraction layer include 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). desirable. As the alkali metal salt, lithium fluoride, sodium fluoride, potassium fluoride, cesium fluoride, cesium carbonate and the like are desirable. One reason why such a material is desirable is that when combined with a cathode such as ITO, the work function of the cathode is reduced and the voltage applied to the inside of the solar cell element is increased.

  When an alkali metal salt is used as a material for the electron extraction layer 130, the electron extraction layer 130 can be formed using a vacuum film formation method such as vacuum deposition or sputtering. In particular, it is desirable to form the electron extraction layer 130 by vacuum deposition using resistance heating. In this case, the film thickness is 0.1 nm or more and 50 nm or less, preferably 20 nm or less. If the electron extraction layer 130 is too thin, the effect of improving the electron extraction efficiency is not sufficient, and if it is too thick, the electron extraction layer 130 acts as a series resistance component, which tends to impair the characteristics of the device.

  When titanium oxide TiOx is used as the material for the electron extraction layer 130, the electron extraction layer 130 can be formed using a vacuum film formation method such as sputtering. However, it is more desirable to form a film using a coating method. For example, the electron extraction layer 130 made of titanium oxide can be formed according to the sol-gel method described in Non-Patent Document 4. The film thickness is usually 0.1 nm or more and 100 nm, preferably 5 nm or more and 50 nm or less. If the electron extraction layer 130 is too thin, the effect of improving the electron extraction efficiency is not sufficient, and if it is too thick, the electron extraction layer 130 acts as a series resistance component, which tends to impair the characteristics of the device.

  When zinc oxide ZnO is used as the material of the electron extraction layer 130, a vacuum film formation method such as a sputtering method can be used. However, it is desirable to form the electron extraction layer 150 using a coating method. For example, the electron extraction layer 130 made of zinc oxide can be formed according to the sol-gel method described in Non-Patent Document 5. The film thickness is usually 0.1 nm or more and 400 nm or less. Moreover, 1 nm or more and 50 nm or less are more preferable. If the electron extraction layer 130 is too thin, the effect of improving the electron extraction efficiency is not sufficient, and if it is too thick, the electron extraction layer 130 acts as a series resistance component, which tends to impair the characteristics of the device.

Examples of the organic compound material used as the electron extraction layer 130 include bathocuproin (BCP), bathophenanthrene (Bphen), (8-hydroxyquinolinato) aluminum (Alq3), boron compound, oxadiazole compound, benzimidazole compound, Examples thereof include, but are not limited to, naphthalenetetracarboxylic anhydride (NTCDA), perylenetetracarboxylic anhydride (PTCDA), phosphine oxide compounds, phosphine sulfide compounds, and conductive polymers. Moreover, you may dope metals, such as an alkali metal or alkaline-earth metal, with respect to the above organic compound materials.
When an organic compound is used as the electron extraction layer 130, the thickness of the electron extraction layer 130 is usually 0.5 nm or more and 500 m or less, more preferably 1 nm or more and 100 nm or less. If the electron extraction layer 130 is too thin, the effect of improving the electron extraction efficiency is not sufficient, and if it is too thick, the electron extraction layer 130 acts as a series resistance component, which tends to impair the characteristics of the device.

  When the electron extraction layer 130 is formed using a plurality of materials, the entire thickness of the electron extraction layer 130 is usually 0.1 nm or more, usually 100 nm or less, more preferably 60 nm or less. If the electron extraction layer 130 is too thin, the effect of improving the electron extraction efficiency is not sufficient, and if it is too thick, the electron extraction layer 130 is too thin.

<Method for forming buffer layer>
There is no restriction | limiting in the formation method of the buffer layers 130 and 150. Although several methods for forming a film have been described above, in general, when a material having sublimation properties is used, a vacuum film forming method such as a vacuum evaporation method can be used. In addition, when a material soluble in a solvent is used, a wet coating method such as spin coating or ink jet can be used.

<Substrate (110)>
The solar cell element 100 according to the present embodiment has a substrate 110 that is normally a support. That is, the electrodes 120 and 160, the active layer 140, and the buffer layers 130 and 150 are formed on the substrate 100. The material of the substrate 110 (substrate material) is arbitrary as long as the effects of the present embodiment are not significantly impaired. Preferable examples of the substrate material include inorganic materials such as quartz, glass, sapphire, and titania; polyethylene terephthalate, polyethylene naphthalate, polyethersulfone, polyimide, nylon, polystyrene, polyvinyl alcohol, ethylene vinyl alcohol copolymer, fluorine Resin films, polyolefins such as vinyl chloride and polyethylene, cellulose, polyvinylidene chloride, aramid, polyphenylene sulfide, polyurethane, polycarbonate, polyarylate, polynorbornene, epoxy resin and other organic materials; paper, synthetic paper and other paper materials; stainless steel, Examples thereof include composite materials such as those obtained by coating or laminating a surface of a metal such as titanium or aluminum to impart insulation. Examples of the glass include soda glass, blue plate glass, and alkali-free glass. As for the glass material, alkali-free glass is preferred because it is better that there are fewer ions eluted from the glass.

  There is no restriction | limiting in the shape of a board | substrate, For example, shapes, such as a board, a film, a sheet | seat, can be used. There is no limitation on the thickness of the substrate. However, it is preferably 5 μm or more, especially 20 μm or more, and usually 20 mm or less, especially 10 mm or less. If the substrate is too thin, the strength of the solar cell element may be insufficient, and if the substrate is too thick, the cost may be increased or the weight may be increased. In the case where the substrate is glass, if it is too thin, the mechanical strength is reduced and the substrate is liable to break. Therefore, it is preferably 0.01 mm or more, more preferably 0.1 mm or more. Moreover, since a weight will become heavy when too thick, 10 mm or less is preferable and 3 mm or less is more preferable.

<Method for Manufacturing Solar Cell Element 100>
The photoelectric conversion element 100 according to this embodiment can be formed by sequentially forming the electrode 120, the active layer 140, and the electrode 160 on the substrate 110 by the method as described above. In the case of providing the buffer layers 130 and 150, the electrode 120, the buffer layer 130, the active layer 140, the buffer layer 150, and the electrode 160 may be sequentially formed on the substrate 110.

  Furthermore, it is preferable to perform a heat treatment (annealing treatment) on a stacked body obtained by sequentially forming at least the electrode 120, the active layer 140, and the electrode 160 on the substrate 110. By performing the annealing treatment, the thermal stability and durability of the photoelectric conversion element 100 may be improved. One reason for this is considered to be that the adhesion between the layers can be improved by the annealing treatment. The heating temperature is usually 200 ° C. or lower, preferably 180 ° C. or lower, more preferably 150 ° C. or lower. Moreover, heating temperature is 50 degreeC or more normally, Preferably it is 80 degreeC or more. If the temperature is too low, the adhesion may not be sufficiently improved. If the temperature is too high, for example, the compound contained in the active layer 140 may be thermally decomposed. The annealing treatment can also be performed by heating at a plurality of temperatures in a stepwise manner at a plurality of different temperatures.

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

  The thin film solar cell according to the embodiment can be manufactured using any method. For example, according to a well-known technique, a solar cell in which the surface of the organic thin-film solar cell according to the embodiment is covered with an appropriate protective material can be manufactured in order to improve weather resistance. Examples of the protective material include a weather-resistant protective film, an ultraviolet cut film, a gas barrier film, a getter material film, and a sealing material.

<Organic / inorganic hybrid solar cell>
The organic-inorganic hybrid solar cell has the same element configuration as that of the above-described organic solar cell, but uses an organic-inorganic perovskite for the active layer instead of the P-type and N-type organic semiconductors of the active layer of the organic thin-film solar cell. It is a solar cell characterized by using the aforementioned polymer for the hole extraction layer. Light is absorbed by the active layer (organic / inorganic perovskite) 140, charge separation occurs, and generated electrons and holes are taken out from the electrodes 120 and 160. A buffer layer similar to the organic thin film solar cell described above can be used.

The organic / inorganic perovskite used for the active layer was selected from at least one of the following structures.
CH ₃ NH ₄ MX ₃ where M = Pd, Sn; X = I, Br, Cl

  The active layer can be formed by vacuum deposition of the above compound or its precursor, or by applying the above compound or its precursor dissolved in a solvent, followed by heating and drying. A mixture of methylammonium halide and lead halide or tin halide can be used as the precursor.

  Typically, the organic inorganic perovskite or its precursor mixture is dissolved in a solvent and applied in a single step, and a lead halide or tin halide solution is applied as a precursor and dried. There is a method of forming an active layer by applying a methylammonium halide solution and drying by heating.

  The type of the solvent is not particularly limited as long as the material can be uniformly dissolved. For example, lower alcohols such as methanol, ethanol, propanol, ethylene glycol, methoxyethanol; acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, etc. Ketones; esters such as ethyl acetate, butyl acetate and methyl lactate; ethers such as ethyl ether, tetrahydrofuran and dioxane; amides such as dimethylformamide and dimethylacetamide.

  The thickness of the active layer is not particularly limited, but the thickness of the active layer is preferably 10 nm to 1000 nm, and more preferably 50 nm to 600 nm. When the thickness of the active layer is 10 nm or more, the uniformity of the layer is maintained, and it becomes difficult to cause a short circuit. Further, when the thickness of the active layer is 1000 nm or less, the internal resistance can be reduced, and further, the distance between the electrodes can be shortened so that the charge diffusion can be improved.

  As the buffer layer between the active layer (organic-inorganic hybrid) and the hole extraction electrode in the organic / inorganic hybrid solar cell, the polymer can be dissolved in a solvent and used as the hole extraction layer 150 by various coating methods.

  The thickness of the hole extraction layer is not particularly limited, but is usually 1 nm or more and 100 nm or less. Preferably it is 2 nm or more, and 50 nm or less is more preferable. If it is too thin, the uniformity is not sufficient and a short circuit tends to occur, and if it is too thick, the resistance value tends to increase and it becomes difficult to extract holes.

  Others can be formed by the same method as the organic thin film solar cell.

  EXAMPLES Hereinafter, although an Example is shown and this invention is demonstrated concretely, this invention is not limited to a following example.

Synthesis Example An example of the synthesis route of the monomer constituting the acceptor unit in the polymer is as follows.
Below, the specific synthesis example of the monomer according to this method is shown.

Compound AM2 Synthesis Compound (AM1) 16.878 g (0.0906 mol) was measured in a four-neck flask, equipped with a thermometer, a CO ₂ introduction reflux tube, and a dropping funnel. After that, 400 ml of anhydrous THF was added. The dropping funnel was charged with 126 ml of 1.6M n-butyllithium in hexane. The flask was cooled to −78 ° C. with a dry ice / acetone bath, and the solution was added dropwise. After the dropwise addition, a reaction time of 2 hours at that temperature, while the temperature, introducing CO ₂ from the CO ₂ inlet tube, was bubbled for 6 hours.

The reaction mixture was poured into water, acidified with hydrochloric acid, extracted with ethyl acetate, and washed with an aqueous NaCl solution three times. The organic layer was dried over anhydrous magnesium sulfate, and the solvent was removed under reduced pressure to obtain a solid. This product was washed with chloroform to obtain 13.678 g (59.4%) of an ocher solid of compound AM2. The NMR spectrum of the obtained compound was measured with a JNM-GSX270 type nuclear magnetic resonance apparatus manufactured by JEOL Ltd.
¹ H-NMR (270 Mhz, CD ₃ OD) ∂: 4.27-4.21 (m, 2H), 4.21 to 4.16 (m, 2H), 4.99 (s, 1H);
¹³ C-NMR (CD ₃ OD) 166.88, 165, 73, 148.74, 147.31, 142.69, 131, 37

Synthesis of Compound AM3a 2.309 g (0.0100 mol) of Compound (AM2) was measured in a three-necked flask, equipped with a thermometer, an N ₂ introduction reflux tube and a dropping funnel, and a rotator was added to flow nitrogen and create a nitrogen atmosphere. Thereafter, 30 ml of anhydrous toluene and a few drops of anhydrous DMF were added. In addition, 5.152 g (0.0401 mol) of ogisyl chloride was dissolved in 5 ml of anhydrous toluene and slowly dropped at room temperature in the dropping funnel, and after the generation of gas had stopped, the reaction was carried out by heating under reflux for 2 hours. Under reduced pressure, the solvent and excess ogizayl chloride were removed. Toluene (50 ml) was added to the residue and dissolved.

  On the other hand, a four-necked flask equipped with a thermometer, a reflux tube with an argon introduction tube, and a dropping funnel was used as an argon atmosphere, and then 1.754 g (0.011 mol) of 1,2-diethylhydrazine · 2HCl and 4,452 g (0. 04) The flask was placed in the flask, and the toluene solution was put into the dropping funnel and dropped at room temperature. After the dropping, the reaction was allowed to proceed for 12 hours at the solvent reflux temperature. The post-reaction mixture was poured into ice water and extracted with toluene.

The organic layer was dried over anhydrous magnesium sulfate and the solvent was removed under reduced pressure. The obtained reaction product was purified by column chromatography (silica gel; developing solvent toluene: ethyl acetate = 3: 1) to obtain 1.202 g (yield: 42.6%) of a solid of Compound MA3a.
¹ H-NMR (270 Mhz, CDCl ₃ ) ∂: 4.35 to 4.31 (m, 2H), 4.26 to 4.14 (m, 6H), 1.28 (6H, t, J = 6. 92),
¹³ C-NMR (CDCl ₃ ) 155.15, 155.07, 147.57, 143.19, 142.66, 131.06, 40.27, 39.78, 33.08, 32.91, 13. 06, 13.01

Synthesis of Compound MA3b Synthesis was performed in the same manner as Compound AM3a, except that phenylhydrazine was used instead of 1,2-diethylhydrazine · 2HCl. A solid of compound AM3b was obtained with a yield of 45.1%.

Synthesis of Compound MA3c The compound MA3c was synthesized in the same manner as Compound AM3a, except that 6-bromohexylhydrazine hydrochloride was used instead of 1,2-diethylhydrazine · 2HCl. A solid of compound AM3c was obtained with a yield of 30.5%.

Compound AM4a synthesis thermometer, reflux tube with argon inlet tube, and four-necked flask equipped with a dropping funnel were placed in an argon atmosphere, then compound AM3a (1.957 g, 0.00693 mol) and CHCl ₃ (20 ml) were added, and the dropping funnel was added. M-chloroperbenzoic acid (1.661 g, 72 w%) was dissolved in CHCl ₃ (20 ml) and placed in a dropping funnel, and the flask was cooled to −40 ° C. and added dropwise. After dropping, the temperature was returned to room temperature in 30 minutes and then reacted at room temperature for 3 hours. Thereafter, the solvent was removed under reduced pressure. To the obtained reaction product, 20 ml of acetic anhydride was added, heated, and reacted at a solvent reflux temperature for 20 minutes. After removing the solvent under reduced pressure, the residue was purified by column chromatography (silica gel; developing solvent hexane: toluene = 1: 1) to obtain 1.529 g (yield: 78.7%) of Compound AM4a as a solid.
¹ H-NMR (270 Mhz, CDCl ₃ ): 8.21 (1H, d, J = 2.64 Hz), 7.46 (1 H, d, J = 2.64 Hz), 4.27 (4H, q , J = 6.8 Hz), 1.34 (3H, t, J = 6.92 Hz), 1.33 (3H, t, J = 6.92 Hz).
¹³ C-NMR (CDCl ₃ ); 155.06, 154.06, 146.91, 141.10, 137.08, 126.24, 112, 40.23, 39.71, 9.08, 112.525 ,, 40.25, 39.75, 12.93

Synthesis of Compound AM4b The compound AM4b was synthesized in the same manner as Compound AM4a, except that Compound AM3b was used instead of Compound AM3a. A solid of compound AM4b was obtained with a yield of 48.3%.

Synthesis of Compound A4c The compound A4c was synthesized in the same manner as Compound AM4a, except that Compound AM3c was used instead of Compound AM3a. A solid of compound AM4c was obtained with a yield of 37.8%.

Synthesis of dibromo-substituted monomer A1a Compound AM4a (1.377 g, 0.0491 mol) and 14 ml of anhydrous DMF were added to a three-necked flask equipped with a reflux tube, a dropping funnel and a rotor, and 2.185 g (0.0123 mlol) of N-bromosuccinimide was added. ) Was dissolved in 14 ml of anhydrous DMF and placed in a dropping funnel. The solution was added dropwise at room temperature, and reacted at room temperature for 1 day after the addition. An aqueous sodium thiosulfate solution was added and the mixture was treated for 30 minutes, extracted with chloroform, washed twice with water and once with an aqueous NaCl solution, and then the organic layer was dried over anhydrous magnesium. The solvent was concentrated under reduced pressure, and the residue was purified by column chromatography (silica gel, chloroform: toluene = 2: 1) to obtain 1.804 g (yield 83.9%) of A1a yellow solid.

¹ H-NMR (270 Mhz, CDCI ₃ ) 4.23, (2H, q, J = 6.92 Hz), 4.44 (2H, q, J = 6.92 Hz), 1.31 (3H, t, J = 6.92 Hz), 1.30 (3H, t, J = 6.92 Hz).
¹³ C-NMR (CDCl ₃ ) 155.06, 153.94, 149.52, 140.13, 139.56, 127.70, 105.18, 99.14, 40.91, 40.31, 13. 21, 13.13

A1b was synthesized in the same manner as Compound A1a, except that Compound AM4b was used instead of Compound AM4a. A yellow solid of A1b was obtained with a yield of 65.1%.

Synthesis of A1c Synthesis was performed in the same manner as for compound A1a, except that compound AM4c was used instead of compound AM4a. A yellow solid of A1c was obtained with a yield of 58.3%.

Other examples of the synthesis route of the monomer constituting the acceptor unit in the polymer are as follows.
Below, the specific synthesis example of the monomer according to this method is shown.

Synthesis of Compound AM6a Compound (AM5, purchased from Tokyo Chemical Industry Co., Ltd.) 1.115 gg (0.00648 mol) was measured in a three-necked flask, equipped with a thermometer, N ₂ introduction reflux tube and dropping funnel, and put a rotor. Then, after flowing nitrogen to make a nitrogen atmosphere, 15 ml of anhydrous toluene and several drops of anhydrous DMF were added. Further, in the dropping funnel, 3.356 g (0.0261 mol) of ogisyl chloride was dissolved in 5 ml of anhydrous toluene and slowly dropped at room temperature, and after the generation of gas was stopped, the reaction was carried out at 90 ° C. for 2 hours. Under reduced pressure, the solvent and excess ogizayl chloride were removed. 1,2-Diethylhydrazine.2HCl (90 wt%, 1.135 g (0,0642)) and toluene (5 ml) were added to the residue, and a reflux tube with an argon introduction tube and a dropping funnel were attached to the residue, and then triethylamine was added. 1.447 g (0.0143 mol) was dissolved in 15 ml of toluene, placed in a dropping funnel and added dropwise at room temperature. After the dropwise addition, the reaction was allowed to proceed for 12 hours at the solvent reflux temperature. The post-reaction mixture was poured into ice water and extracted with toluene. The organic layer was dried over anhydrous magnesium sulfate and the solvent was removed under reduced pressure. The obtained reaction product was purified by column chromatography (silica gel; developing solvent chloroform: ethyl acetate = 2: 1) to obtain 0.808 g (yield 55.6%) of a pale pinkish white solid of Compound A5a.

¹ H-NMR (270 Mhz, CDCl ₃ ): 8.26 (2H, s), 4.15 (4H, q, J = 7.03 Hz), 1,24 (6H, t, J = 6.09 HZ) .
¹³ C-NMR (CD3Cl3) 156.34, 131.42, 130.63, 39.75, 12.90

Synthesis of Compound AM6b The compound AM6b was synthesized in the same manner as Compound AM6a, except that phenylhydrazine was used instead of 1,2-diethylhydrazine · 2HCl. A solid of compound AM6b was obtained with a yield of 39.5%.

Synthesis of Compound AM6c The compound AM6c was synthesized in the same manner as Compound AM6a, except that 6-bromohexylhydrazine hydrochloride was used instead of 1,2-diethylhydrazine · 2HCl. A solid of compound AM6c was obtained with a yield of 43.2%.

Synthesis of Compound AM7 Measure 5.800 g (0.0337 mol) of Compound (AM6a) in a three-necked flask, and equip it with a thermometer, an N2 introduction reflux pipe and a dropping funnel. Add 58 ml of glacial acetic acid and stir. Thereto, 10.5 ml of bromine was slowly dropped from a dropping funnel at room temperature, and the mixture was allowed to react at room temperature for 4 days. Then, about 10% NaHSO ₃ aqueous solution was added until the color disappeared. Filtered and washed the precipitate with water. This precipitate was vacuum-dried at 80 ° C. for 3 hours to obtain 76.948 g (63.6%) of Compound AM.
¹³ C-NMR (CDCl ₃ ) 162.71, 136.09, 115.28

Synthesis of Compound A2a 3.308 g (0.0100 mol) of Compound (AM5) was measured in a three-necked flask, equipped with a thermometer, an N ₂ introduction reflux tube and a dropping funnel, and a rotator was added to flow nitrogen and create a nitrogen atmosphere Thereafter, 30 ml of anhydrous toluene and a few drops of anhydrous DMF were added. Further, in the dropping funnel, 10.309 g (0.0809 mol) of ogisyl chloride was dissolved in 20 ml of anhydrous toluene and slowly dropped at room temperature, and after the generation of gas was stopped, the reaction was carried out at 90 ° C. for 2 hours. Under reduced pressure, the solvent and excess ogizayl chloride were removed. To this residue, 1,2-diethylhydrazine · 2HCl (90 wt%, 1.750 g) and toluene (20 ml) were added, and a reflux tube with an argon inlet tube and a dropping funnel were attached to the residue. 0.022 mol) was dissolved in 20 ml of toluene, placed in a dropping funnel and added dropwise at room temperature. After the dropwise addition, the reaction was allowed to proceed for 12 hours at the solvent reflux temperature. The post-reaction mixture was poured into ice water and extracted with toluene. The organic layer was dried over anhydrous magnesium sulfate and the solvent was removed under reduced pressure. The obtained reaction product was purified by column chromatography (silica gel; developing solvent chloroform: ethyl acetate = 2: 1) to obtain 3.000 g (yield 78.3%) of a light yellowish white solid of Compound A2a. .

¹ H-NMR (270 Mhz, CDCl ₃ ) ∂: 4.08 (4H, q, J = 7.14 Hz), 1,23 (6H, t, J = 6.09 HZ).
¹³ C-NMR (CDCl ₃ ) 154.98, 127.81, 118.25, 39.9, 12.80

Synthesis of Compound A2b The compound A2b was synthesized in the same manner as Compound A2a, except that phenylhydrazine was used instead of 2-diethylhydrazine · 2HCl. A solid of compound A2b was obtained with a yield of 39.5%.

Synthesis of Compound AM6c The compound AM6c was synthesized in the same manner as Compound A2a except that 6- bromohexylhydrazine hydrochloride was used instead of 1,2-diethylhydrazine · 2HCl. A solid of compound A2c was obtained with a yield of 43.2%.

The monomer constituting the donor unit in the polymer was synthesized according to the literature.
First, monomer MD1 was prepared according to Jiuanhui Hou et al. Macromolecules, 2008, Vol. 41, 6012, monomer MD2 was prepared according to the method of Yongye Liang et al. Am. Chem. Soc. 2009 Vol. 131, no. 22, 7792-7799.

The monomer MD3 was purchased from 1-meter and used.

The polymer (P1) was synthesized by the following method.

  Under a nitrogen atmosphere, a three-necked flask equipped with a three-way cock was charged with distanyl-substituted monomer MD1 (0.633 g, 0.701 mmol), dibromo-substituted monomer (0.307 g, 0.701 mmol) and 0.040 g of tetrakis (triflic). Enylphosphine) palladium (catalyst) was measured. While flowing argon through the three-way cock into the three-necked flask, a reflux tube equipped with an argon inlet tube was attached to the three-necked flask. Then, the dropping funnel was equipped so that air might not enter into the flask. The reason why the operation was performed in a nitrogen atmosphere or an argon atmosphere is that the catalyst was deactivated by oxygen when air was mixed in the flask. However, the argon inlet tube was connected to a vacuum line so that the argon atmosphere and the vacuum could be switched.

  Next, the three-way cock is closed, the inside of the flask is evacuated, and argon is introduced again. This operation was repeated three times.

  While flowing argon into the flask, 16 ml of deaerated anhydrous toluene and 4 ml of anhydrous DMF were introduced from a three-way cock attached to the flask with a syringe to dissolve the raw material, and then the three-necked flask was heated in an oil bath. The mixture was reacted at reflux temperature for 12 hours and cooled to room temperature.

  Under nitrogen atmosphere, 0.064 g of trimethylphenyltin was measured as an end-capping agent, dissolved in 4 ml of degassed anhydrous toluene, introduced into the flask with a syringe, and then heated to reflux for 2 hours. After cooling to room temperature, 0.061 g of bromobenzene was measured under nitrogen as another end-capping agent, dissolved in 4 ml of degassed anhydrous toluene, introduced into the flask with a syringe, and heated to reflux. Went for hours. After cooling to room temperature, the reaction solution was added dropwise to 500 ml of methanol with stirring to precipitate a polymer. The precipitate was filtered through a glass filter, dissolved in chloroform, and the catalyst was removed with a celite column. After concentrating the solvent with an evaporator, methanol was added and stirred well, followed by filtration using a glass filter to obtain a solid. This solid was vacuum-dried at 80 ° C. for 4 hours to obtain a glossy polymer.

  Purification was performed in the order of ethyl acetate, hexane, and toluene using a Soxhlet extractor. Thereafter, evaluation was performed using a toluene extract component (yield 92.6%).

¹ H-NMR (270 Mhz, CDCl ₃ ) ∂: 7.9 to 6.85 (m), 4.55 to 4.17 (road), 3.4 to 2.75 (Broad), 1.87 to 0 .6 (m).

In the NMR spectrum, peaks of aromatic protons of the benzodithiophene ring and the side chain thiophene ring were observed at ∂ 6.35 to 7.9 ppm, and CH bonded to N at 4.55 to 4.17 (broad). ₂ corresponds to a peak corresponding to CH ₂ having a side chain thiophene ring bond at 3.4 to 2.75 pm, and all peaks corresponding to an alkyl group are observed at 0.6 to 1.87 ppm. It was confirmed that it was the target polymer.

  When the weight average molecular weight in terms of polystyrene was measured by GPC (HPCL: CBM20 manufactured by Shimadzu Corporation, column: Sodex (registered trademark) K-504 manufactured by Showa Denko KK), it was 38000. Moreover, it was Mw / Mn = 2.5.

When the UV-vis absorption spectrum (A2000 manufactured by Shimadzu Corporation) was measured, the maximum absorption peak (λ _max ) was 560 nm in the chloroform solution.

The polymer (P2) was synthesized by the following method.

  The same procedure as in Example 1 was performed except that MD2 was used instead of the di (trialkylstannyl) -substituted monomer MD1. A glossy solid polymer was obtained. The yield of toluene extract was 84%.

¹ H-NMR (270 Mhz, CDCl ₃ ): 8.0-6.8 (m), 4.55-3.9 (road), 1.9-0.6 (m).

In the NMR spectrum, peaks of aromatic protons of the benzodithiophene ring and the side chain thiophene ring are observed at 6.8 to 8.0 ppm, and bonded to N and O at 4.55 to 3.9 (broad). All peaks corresponding to alkyl groups were observed over 0.6 to 1.9 ppm of the peak corresponding to the CH ₂ peak, confirming that it was the target polymer.

  When the weight average molecular weight in terms of polystyrene was measured by GPC, it was 24,000. Moreover, it was Mw / Mn = 2.8.

  When the UV-vis absorption spectrum was measured, the maximum absorption peak in a chloroform solution was 554 nm.

The polymer (P3) was synthesized by the following method.
A glossy solid polymer was obtained in the same manner as in Example 1 except that MD3 was used instead of the di (trialkylstannyl) -substituted monomer MD1. The yield of toluene extract was 84%.
¹ H-NMR (270 Mhz, CDCl ₃ ): 8.0 to 6.8 (m), 4.55 to 4.15 (road), 1.9 to 0.6 (m).

In the NMR spectrum, peaks of aromatic protons of benzodithiophene ring and side chain thiophene ring are observed at 6.8 to 8.0 ppm, and CH bonded to N at 4.55 to 4.15 (broad). All peaks corresponding to alkyl groups were observed over peaks corresponding to ₂ and 3.6 to 2.75 pm 0.6 to 1.9 ppm, confirming that the polymer was the target polymer.

  It was 22000 when the polystyrene conversion weight average molecular weight was measured by GPC. Moreover, it was Mw / Mn = 2.8.

  When the UV-vis absorption spectrum was measured, the maximum absorption peak in the chloroform solution was 581 nm.

Polymer (P4) was synthesized by the following method.
A glossy solid polymer was obtained in the same manner as in Example 3 except that dibromo-substituted monomer A1b was used instead of dibromo-substituted monomer A1a. The yield of toluene extract was 56%.
NMR (JNM-GSX270 manufactured by JEOL, ¹ H-NMR, 270 Mhz, CDCl ₃ ) ∂: 7.8 to 6.9 (road), 3.9 to 3.5 (road), 3.2 to 2.6 (Broad), 2.1-0.6 (m).

  In the NMR spectrum, a peak of ∂-7.8 to 6.9 ppm thiophene ring and an aromatic proton of a phenyl group is seen, and all peaks corresponding to alkyl groups are observed as broad peaks over 0.6 to 2.1 ppm. It was confirmed that it was the target polymer.

  When the weight average molecular weight in terms of polystyrene was measured by GPC, it was 21,000. Moreover, it was Mw / Mn = 2.7.

  When the UV-vis absorption spectrum was measured, the absorption peak in the chloroform solution was 587 nm.

The polymer (P5) was synthesized by the following method.

A glossy solid polymer was obtained in the same manner as in Example 1 except that the dibromo-substituted monomer A1c was used instead of the dibromo-substituted monomer A1a. The yield of toluene extract was 75%.
¹ H-NMR (270 Mhz, CDCl ₃ ) ∂: 8.2 to 6.35 (road), 4.5 to 4.15 (road), 3.9 to 3.5 (road), 3.2 to 2 .6 (broad), 2.3-0.6 (m).

In the NMR spectrum, peaks of aromatic protons of the benzodithiophene ring and the side chain thiophene ring are seen at 6.35 to 8.2 ppm, corresponding to CH ₂ bonded to N at 4.5 to 4.15. peak corresponding peaks, peaks corresponding to CH ₂ bound to Br to 3.5～4.0Pm, the CH ₂ was thiophene ring binding side chain 3.2 to 2.6 (broad) that is, zero. All peaks corresponding to alkyl groups were observed over 6 to 2.3 ppm as broad peaks, confirming that it was the target polymer.

  It was 19500 when the polystyrene equivalent weight average molecular weight was measured by GPC. Moreover, it was Mw / Mn = 2.8.

  When the UV-vis absorption spectrum was measured, the maximum absorption peak in the chloroform solution was 545 nm.

Polymer (P6) was synthesized by the following method.

A glossy solid polymer was obtained in the same manner as in Example 1 except that dibromo-substituted monomer A2a was used instead of dibromo-substituted monomer A1a. In a Soxhlet extractor, purification was performed in the order of ethyl acetate, hexane, toluene, and o-dichlorobenzene. Thereafter, extracted components of toluene and dichlorobenzene (yield 76%) were used for evaluation.
NMR (JNM-GSX270 manufactured by JEOL, ¹ H-NMR, 270 Mhz, CDCl ₃ ) ∂: 7.9 to 6.85 (m), 4.3 to 3.9 (broad), 3.4 to 2.75 (Broad), 1.87-0.6 (m).

In the NMR spectrum, aromatic proton peaks of benzodithiophene ring and side chain thiophene ring are observed at ∂6.35 to 7.9 ppm, and CH bonded to N at 4.3 to 3.9 (broad). ₂ peaks, peaks corresponding to CH ₂ bonded with a side chain thiophene ring at 3.4 to 2.75 pm, and peaks corresponding to alkyl groups were observed over 0.6 to 1.87 ppm, It was confirmed that the target polymer.

  When the weight average molecular weight in terms of polystyrene was measured by GPC, it was 36000. Moreover, it was Mw / Mn = 2.5.

  When the UV-vis absorption spectrum was measured, the maximum absorption peak in the chloroform solution was 515 nm.

The polymer (P7) was synthesized by the following method.

  A glossy solid polymer was obtained in the same manner as in Example 6 except that MD2 was used instead of the di (trialkylstannyl) -substituted monomer MD1. The yield of toluene extract was 81%. Thereafter, toluene extracted components were used for evaluation.

¹ H-NMR (270 Mhz, CDCl ₃ ): 8.0 to 6.8 (m), 4.3 to 3.8 (road), 1.9 to 0.6 (m).

In the NMR spectrum, peaks of aromatic protons in the benzodithiophene ring and the side chain thiophene ring are observed at 6.8 to 8.0 ppm, and bonded to N and O at 4.3 to 3.8 (road). All the peaks corresponding to alkyl groups were observed over the CH ₂ peak of 0.6 to 1.9 ppm, confirming that the polymer was the target polymer.

  It was 22000 when the polystyrene conversion weight average molecular weight was measured by GPC. Moreover, it was Mw / Mn = 2.7.

  When the UV-vis absorption spectrum was measured, the maximum absorption peak in the chloroform solution was 503 nm.

The polymer (P8) was synthesized by the following method.

  A glossy solid polymer was obtained in the same manner as in Example 6 except that MD3 was used in place of the di (trialkylstannyl) -substituted monomer MD1. The yield of toluene extract was 46%. Thereafter, toluene extracted components were used for evaluation.

¹ H-NMR (270 Mhz, CDCl ₃ ) ∂: 8.0 to 6.8 (m), 4.2 to 3.9 (road), 3.5 to 2.75 (Broad), 1.9 to 0 .6 (m).

In the NMR spectrum, aromatic proton peaks of benzodithiophene ring and side chain thiophene ring are observed at 6.8 to 8.0 ppm, and CH bonded to N at 4.55 to 3.9 (broad). ₂ peaks, peaks corresponding to CH ₂ having a side chain thiophene ring bond at 3.6 to 2.75 pm, and peaks corresponding to alkyl groups were observed over 0.6 to 1.9 ppm. The polymer was confirmed.

  When the weight average molecular weight in terms of polystyrene was measured by GPC, it was 24,000. Moreover, it was Mw / Mn = 2.8.

  When the UV-vis absorption spectrum was measured, the maximum absorption peak in the chloroform solution was 548 nm.

The polymer (P9) was synthesized by the following method.

  A glossy solid polymer was obtained in the same manner as in Example 8 except that dibromo-substituted monomer A2b was used instead of dibromo-substituted monomer A2a. The yield of toluene extract was 48%.

¹ H-NMR (270 Mhz, CDCl ₃ ) ∂: 7.8 to 6.9 (road), 2.1 to 0.6 (m).

  In the NMR spectrum, a peak of ∂-7.8 to 6.9 ppm thiophene ring and an aromatic proton of a phenyl group is seen, and all peaks corresponding to alkyl groups are observed as broad peaks over 0.6 to 2.1 ppm. It was confirmed that it was the target polymer.

  When the weight average molecular weight in terms of polystyrene was measured by GPC, it was 23,000. Moreover, it was Mw / Mn = 2.9.

  When the UV-vis absorption spectrum was measured, the maximum absorption peak in the chloroform solution was 551 nm.

A polymer (P10) was synthesized by the following method.

  A glossy solid polymer was obtained in the same manner as in Example 8 except that dibromo-substituted monomer A1c was used instead of dibromo-substituted monomer A1a. The yield of toluene extract was 37%.

¹ H-NMR (270 Mhz, CDCl ₃ ) ∂: 8.2-6.35 (road), 4.5-4.15 (road), 4.2-3.5 (road), 3.2-2 .6 (broad), 2.3-0.6 (m).

In the NMR spectrum, peaks of aromatic protons of benzodithiophene ring and side chain thiophene ring are observed at 6.35 to 8.2 ppm, and CH ₂ bonded to N and Br at 4.3 to 3.5 pm. All peaks corresponding to alkyl groups and 0.6 to 2.3 ppm corresponding to alkyl groups were observed as broad peaks, confirming that it was the target polymer.

  It was 18500 when the polystyrene conversion weight average molecular weight was measured by GPC. Moreover, it was Mw / Mn = 2.1.

  When the UV-vis absorption spectrum was measured, the maximum absorption peak in the chloroform solution was 545 nm.

The polymer (P11) was synthesized by the following method.

  A glossy solid polymer was obtained in the same manner as in Example 2 except that dibromo-substituted monomer A1a and A1c (molar ratio A1a: A1c = 9: 1) were used instead of dibromo-substituted monomer A1a. The yield of toluene extract was 75%.

¹ H-NMR (270 Mhz, CDCl ₃ ) ∂: 8.2 to 6.35 (road), 4.5 to 4.15 (road), 3.9 to 3.5 (road), 3.2 to 2 .6 (broad), 2.3-0.6 (m).

In the NMR spectrum, peaks of aromatic protons of the benzodithiophene ring and the side chain thiophene ring were observed at 6.35 to 8.2 ppm, and a peak bonded to N at 4.5 to 4.15. A peak corresponding to CH ₂ bonded to N and Br at 5 to 3.5 pm, and a peak corresponding to CH ₂ bonded to a thiophene ring of a side chain at 3.2 to 2.6 (broad) is 0.6 to 2 All peaks corresponding to alkyl groups over 3 ppm were observed as broad peaks, confirming that it was the target polymer.

  When the weight average molecular weight in terms of polystyrene was measured by GPC, it was 19000. Moreover, it was Mw / Mn = 2.5.

  When the UV-vis absorption spectrum was measured, the maximum absorption peak in the chloroform solution was 504 nm.

The polymer (P12) was synthesized by the following method.

  The same procedure as in Example 8 was performed except that dibromo-substituted monomers A2a and A2c (molar ratio A2a: A2c = 9: 1) were used instead of dibromo-substituted monomer A2a.

¹ H-NMR (270 Mhz, CDCl ₃ ) ∂: 8.2-6.35 (road), 4.5-4.15 (road), 4.2-3.5 (road), 3.2-2 .6 (broad), 2.3-0.6 (m).

In the NMR spectrum, peaks of aromatic protons of the benzodithiophene ring and the side chain thiophene ring are observed at 6.35 to 8.2 ppm. Peaks corresponding to CH ₂ bound to N, a peak corresponding to the CH ₂ bonded to N and Br in 4.2～3.5Pm, the peak corresponding to the alkyl group over 0.6~2.3ppm all It was observed as a broad peak, confirming that it was the target polymer.

Preparation of organic thin film solar cell element < Preparation of active layer coating solution S0>
The polymers P1 to P12 which are p-type semiconductor materials are mixed with [70] PCBM which is an n-type semiconductor material so that the weight ratio is 1: 2, so that the mixture has a concentration of 2.0% by weight. It was dissolved in chlorobenzene in a nitrogen atmosphere. Moreover, 1,8-diiodooctane was added so that it might become the ratio of 3 weight% of the whole solution, and it stirred and mixed at the temperature of 120 degreeC using the hot stirrer for 1 hour. The solution after stirring and mixing was cooled to room temperature, and then filtered through a 0.20 μm polytetrafluoroethylene (PTFE) filter to obtain an active layer coating solution for each polymer.

<Production of solar cell element>
A glass substrate patterned with an indium tin oxide (ITO) transparent conductive film is cleaned in the order of ultrasonic cleaning with a surfactant, water with ultrapure water, and ultrasonic cleaning with ultrapure water, and then dried with nitrogen blow. And dried by heating at 120 ° C. in the air for 5 minutes. Finally, ultraviolet ozone cleaning was performed on the substrate. On this substrate, a 2% solution of diethylzinc diethoxyethane (made by Showa Denko Co., Ltd.), which is a precursor of zinc oxide, was applied as an electron extraction layer by spin coating in a nitrogen atmosphere. Heated in air for 10 minutes on a hot plate. The film thickness of the electron extraction layer was about 20 nm.

  An active layer having a thickness of about 90 nm was formed on the substrate on which the electron extraction layer was formed by spin-coating each polymer active layer coating solution at a rate of 600 rpm in a nitrogen atmosphere. Thereafter, vanadium oxide having an average film thickness of 2 nm was sequentially formed as a hole extraction layer, and silver having a film thickness of 100 nm was further sequentially formed as an electrode layer by a resistance heating vacuum deposition method. Thus, a 1 cm square solar cell element was produced.

A glass substrate on which a photocrosslinked indium tin oxide (ITO) transparent conductive film of an active layer using polymers P5, P10, P11, and P12 is patterned is subjected to ultrasonic cleaning with a surfactant, water with ultrapure water, After cleaning in the order of ultrasonic cleaning with pure water, it was dried with nitrogen blow, and heated and dried in air at 120 ° C. for 5 minutes. Finally, ultraviolet ozone cleaning was performed on the substrate. On this substrate, a 2% solution of diethylzinc diethoxyethane (made by Showa Denko Co., Ltd.), which is a precursor of zinc oxide, was applied as an electron extraction layer by spin coating in a nitrogen atmosphere. Heated in air for 10 minutes on a hot plate. The film thickness of the electron extraction layer was about 20 nm.

The active layer coating solution of polymer (P5, P10, P11 and P12) is spin-coated at a speed of 600 rpm on the substrate on which the hole extraction layer is formed in a nitrogen atmosphere to form an active layer having a thickness of about 90 nm. Formed. Photocrosslinking was performed by irradiation with UV light (254 nm, 1.9 mW / cm ² ) for 10 minutes in an argon atmosphere.

  Thereafter, vanadium oxide having an average film thickness of 2 nm was sequentially formed as a hole extraction layer, and silver having a film thickness of 100 nm was further sequentially formed as an electrode layer by a resistance heating vacuum deposition method. Thus, a 1 cm square solar cell element was produced.

Production of organic / inorganic hybrid solar cell element < Production of active layer coating solution S0>
PbI ₂ and CH ₃ NH ₄ I were mixed at a molar ratio of 1: 1 and dissolved in dimethylformamide (DMF) in a nitrogen atmosphere so that the mixture had a concentration of 40.0% by weight. The mixture was 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 0.45 μm polytetrafluoroethylene (PTFE) filter to obtain an active layer coating solution.

<Preparation of hole extraction layer coating solution S1>
Polymers P1 to P10, which are p-type semiconductor materials, and one type of comparative polymer were dissolved in chlorobenzene in a nitrogen atmosphere so as to have a concentration of 1.0% by weight. The mixture was 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 polytetrafluoroethylene (PTFE) filter to obtain a hole extraction layer coating solution for each polymer.

<Production of organic-inorganic hybrid solar cell element>
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, followed by nitrogen blowing. It dried and heat-dried at 120 degreeC in air | atmosphere for 5 minutes. Finally, ultraviolet ozone cleaning was performed on the substrate. On this substrate, an ethanol solution of titanium diisopropoxide bis (acetylacetone) was spin-coated, and then heated at 450 ° C. for 30 minutes to cool. The substrate was immersed in an aqueous solution of titanium chloride (TiCl 4) at 70 ° C. for 30 minutes, washed and dried, and then heated in air at 500 ° C. for 20 minutes to form a buffer layer (electron extraction layer) having a thickness of about 20 nm. .

    An active layer coating solution of perovskite (CH 3 NH 4 PI 3) is spin-coated at a rate of 600 rpm in a nitrogen atmosphere on a substrate on which an electron extraction layer has been formed, and dried at 60 ° C. for about 30 minutes, whereby an active having a thickness of about 300 nm is obtained. A layer was formed. Thereafter, a hole extraction layer coating solution prepared from a polymer synthesized as a hole extraction layer was spin-coated at 2000 rpm for 60 seconds to form a hole extraction layer. As an electrode layer, gold having a thickness of 100 nm was sequentially formed by a resistance heating vacuum deposition method. Thus, a 1 cm square organic-inorganic hybrid solar cell element was produced.

[Comparative Example 1]
Dissolve 180 mg of 2,2,7.7-tetrakis (N, N-di-p-methoxyphenylamine) 9,9-bifluorene (Spiro-OMeTAD) in dichlorobenzene. Then, 37.5 μL of a solution in which 170 mg of Li-bis (trifluoromethanesulfonyl) imito was dissolved in acetonitrile was added, and further 17.5 μL of 4-t-butylpyridine was further added to prepare a hole extraction layer coating solution. did. This solution was spin-coated at 3000 rpm for 30 seconds to form a hole extraction layer.

[Comparative Example 2]
This was prepared in the same manner as in Example 16 except that poly (3-hexylthiophene) (P3HT) was used as the polymer.

After the polymers P5, P10, P11 , and P12 are applied as photocrosslinked hole transport layers of the hole transport layer using the polymers P5, P10, P11, and P12, UV light (254 nm, 1.9 mW / cm ^{2) in} an argon atmosphere. ) Was irradiated for 10 minutes to produce a solar cell by the same method as in Example 16, except that photocrosslinking was performed.

Evaluation of solar cell element A 1 cm square metal mask is attached to the photoelectric conversion element produced above, and an air mass (AM) 1.5G and an irradiance of 100 mW / cm ² are used as an irradiation light source. Asahi SPECTR solar simulator-IVP0605 is used. The current-voltage characteristics between the ITO electrode or FTO electrode and the silver electrode were measured. Table 1 shows the measurement results of the organic thin film solar cell, and Table 2 shows the measurement results of the organic-inorganic hybrid electrode.

Simple heat resistance test The bulk hetero-type organic thin film solar cells produced in Examples 14 and 15 were sealed with glass, then heated on a hot plate in a nitrogen atmosphere at 90 for 15 minutes, and then cooled to room temperature. Was evaluated again. Table 3 shows the deterioration rate as the deterioration rate.

  The organic-inorganic hybrid solar cell element was also heated on a hot plate at 90 for 15 minutes in a nitrogen atmosphere, then cooled to room temperature, and the above solar cell was evaluated again. The deterioration rate was as shown in Table 4 with the result as the deterioration rate.

  From the results in Table 1, it was confirmed that the polymer according to the embodiment can be used for a bulk hetero type organic thin film solar cell.

  Further, from the results of Table 2, when the polymer according to the embodiment is used for an organic-inorganic hybrid solar cell, the power generation efficiency may not be comparable to the comparative example, but the polymer according to the actual form functions sufficiently as a hole extraction layer. It became clear. Furthermore, the results in Table 4 revealed that the deterioration rate was equal to or higher than that of the comparative example. It was also confirmed that the power generation performance was higher for the polymer of Comparative Example 2.

  Moreover, it turned out that the tolerance with respect to the heat | fever of a solar cell is improved significantly by crosslinking using the polymer by embodiment from the result of Table 3.

  As described above, the present embodiment has provided a novel polymer and has found that the resistance to heat is greatly improved by crosslinking as a hole extraction layer of an organic thin film solar cell and an organic-inorganic hybrid.

DESCRIPTION OF SYMBOLS 100 Solar cell element 110 Board | substrate 120,160 Electrode 130,150 Buffer layer 140 Active layer

Claims (8)

The following formulas (1) to (4):
Wherein R ¹ and R ² are each independently hydrogen, unsubstituted alkyl group, substituted alkyl group, unsubstituted alkoxy group, substituted alkoxy group, unsubstituted acyl group, substituted acyl group, unsubstituted aryl group, substituted aryl A group selected from the group consisting of a group, an unsubstituted heteroaryl group, and a substituted heteroaryl group, wherein R ¹ and R ² are not simultaneously hydrogen and X ¹ and X ² are each independently O, S, and An atom selected from the group consisting of Se;
Ar is a divalent unsubstituted conjugated unsaturated bond group or a substituted conjugated unsaturated bond group)
A polymer comprising at least one repeating unit selected from the group consisting of:   The total number of moles of repeating units contained in the polymer. The polymer of Claim 1 whose ratio of the repeating unit represented by said Formula (1)-Formula (4) is 50 mol% or more. The polymer according to claim 1 or 2, wherein a terminal group of the main chain of the polymer is a crosslinking group, or any of R ¹ , R ² , and Ar contains a crosslinking group. The following formulas (1A) to (4A):
(Where
R ¹ and R ² are each independently hydrogen, unsubstituted alkyl group, substituted alkyl group, unsubstituted alkoxy group, substituted alkoxy group, unsubstituted acyl group, substituted acyl group, unsubstituted aryl group, substituted aryl group, unsubstituted A group selected from the group consisting of a heteroaryl group and a substituted heteroaryl group, wherein R ¹ and R ² are not simultaneously hydrogen and X ¹ and X ² are each independently a group consisting of O, S, and Se An atom selected from
Ar is a divalent unsubstituted conjugated unsaturated bond group or a substituted conjugated unsaturated bond group,
Each R ^{t is} independently a terminal group, at least one R ^t is a bridging group,
p is a number of 2 or more. )
The polymer of Claim 3 represented by these. The following formulas (1B) to (4B):
(Where
R ¹ , R ² , R ¹ ′ and R ² ′ are each independently hydrogen, unsubstituted alkyl group, substituted alkyl group, unsubstituted alkoxy group, substituted alkoxy group, unsubstituted acyl group, substituted acyl group, unsubstituted aryl group , A substituted aryl group, an unsubstituted heteroaryl group, and a substituted heteroaryl group, provided that R ¹ and R ² are not hydrogen at the same time,
X ¹ , X ² , X ¹ ′ and X ² ′ are each independently an atom selected from the group consisting of O, S and Se;
Ar and Ar ′ are each independently a divalent unsubstituted conjugated unsaturated bond group or a substituted conjugated unsaturated bond group,
q and q ′ are numbers satisfying 0.01 ≦ q / (q + q ′) ≦ 0.5. )
The polymer of Claim 3 represented by these.   The solar cell characterized by including the polymer of any one of Claims 1-5.   A bulk hetero-type organic thin-film solar cell comprising an active layer containing the polymer according to claim 1 as an electron donor and a fullerene derivative as an electron acceptor.   An organic-inorganic hybrid solar cell comprising: a hole transport layer containing the polymer according to claim 1; and a photoelectric conversion layer containing an organic-inorganic perovskite structure.