JP2010238957A - Photoelectric conversion element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photoelectric conversion element having a superior photoelectric conversion efficiency. <P>SOLUTION: The photoelectric conversion element P has a photoelectric conversion layer E that contains a conductive polymer d and an electron acceptor a between two electrodes Y formed on a substrate T. By using the photoelectric conversion element that has the conductive polymer d containing a polyselenophene derivative represented by a general formula (1), the superior photoelectric conversion efficiency is attained. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a photoelectric conversion element. Specifically, for example, the present invention relates to a photoelectric conversion element used for a solar cell element or an optical sensor element.

  A solar cell element is mentioned as a typical example of a device using a photoelectric conversion element. A photoelectric conversion element is called a photoelectric conversion layer in a solar cell element, and when classified roughly on the basis of a photoelectric conversion layer, an inorganic solar cell using an inorganic material such as Si or GaAs and an organic material such as a conductive polymer are used. Classified as organic solar cells.

  Examples of inorganic solar cell elements include silicon solar cell elements, etc., but they have a large number of problems such as lack of diversity and high cost because they are inorganic and have a large environmental load in the manufacturing process. Yes. In comparison, organic solar cell elements are attracting attention because they can solve the problems of inorganic solar cell elements such as low environmental load, diversity, and low cost.

Examples of organic solar cell elements include Schottky barrier solar cell elements that use a Schottky barrier generated between an organic semiconductor and a metal thin film, and dyes such as Ru supported on TiO ₂ , and dye increases with an electrolyte. Examples thereof include an organic thin-film solar cell element using an electron acceptor (hereinafter referred to as an electron transport layer) and a hole acceptor (hereinafter referred to as a hole transport layer) as a photovoltaic cell element and a photoelectric conversion layer.

  With a Schottky barrier solar cell element, an organic semiconductor and a metal thin film are joined together, and the difference between the work function of the metal and the electron affinity of the semiconductor appears in the semiconductor portion as a barrier (Schottky barrier). An element that undergoes electrification and separation when irradiated with light. However, the Schottky barrier solar cell element has a very low photoelectric conversion efficiency of 0.1% or less and is not practical.

  The dye-sensitized solar cell element is an element that undergoes electrification separation when the dye is excited by light irradiation and emits electrons. The dye-sensitized solar cell element achieves a photoelectric conversion efficiency as high as 10%, but expensive materials such as Ru dye and Pt electrode are required to obtain high efficiency. Recently, non-Ru dyes have been studied. For example, a structure similar to or similar to that of the polyselenophene derivative of the present invention can be seen (Patent Document 1), but high conversion efficiency is not obtained except for Ru dyes. Moreover, since a liquid electrolyte is used, it cannot be said that its long-term stability is excellent.

  On the other hand, organic thin-film solar cell elements are attracting attention because they are particularly easy to manufacture and low-cost compared to other solar cell elements. For example, a bilayer organic thin-film solar cell element in which a conductive polymer that also serves as an electron transporting layer and a hole transporting layer is laminated, and a conductive polymer compound that also serves as an electron transporting layer and a hole transporting layer are applied. Examples include bulk heterojunction type organic thin film solar cell elements.

Bilayer organic thin-film solar cell elements are those that cause photoelectric conversion by forming a pn junction at the interface between two layers by bonding an electron transport layer and a conductive polymer that also serves as a hole transport layer. is there. For example, a perylene derivative is used for the electron transport layer and copper phthalocyanine is used for the hole transport layer.
However, in order to prevent the recombination of carriers and observe the current, the film thickness needs to be about 20 nm. At this film thickness, light absorption is insufficient and the photoelectric conversion efficiency is 1% or less.

  On the other hand, the bulk heterojunction organic thin film solar cell element has a single layer structure of an electron transport layer and an electron hole transport layer in which a conductive polymer that also serves as a hole transport layer is mixed. Among them, the volume involved in photoelectric conversion can be increased by forming a pn junction at the molecular level. For example, a polythiophene derivative (poly-3-hexylthiophene-2,5-diyl (hereinafter referred to as P3HT)) is used as a conductive polymer (hole transport layer), and a fullerene derivative [6, 6] as an electron transport layer. Examples thereof include those using -phenyl-C61 butyric acid methyl ester (hereinafter referred to as PCBM) (Patent Document 2). This greatly improved the photoelectric conversion efficiency, but the conversion efficiency was still insufficient due to the low hole transport capability of P3HT.

JP 2005-135656 A JP 2006-245073 A

As described above, various studies have been made as organic thin-film solar cell elements. However, since P3HT, no conductive polymer (hole transport layer) with good characteristics was found, and electron transport ability was insufficient. It is not possible to expect a high photoelectric conversion efficiency with a solar cell. That is, it is indispensable to develop a conductive polymer (hole transport layer) having a high hole transport ability in order to improve the photoelectric conversion efficiency of the organic thin film solar cell element.
An object of the present invention is to provide a photoelectric conversion element having improved photoelectric conversion efficiency by having a conductive polymer having a high hole transport ability.

［式中ｎは５以上の整数を表す。Ｒ^１はヒドロキシル基、シアノ基、リン酸基、スルホン酸基、ハロゲン原子からなる群より選ばれ、Ｒ^２は置換基を有してもよい脂肪族炭化水素基、置換基を有してもよい芳香族炭化水素基、ポリオキシアルキレンアルキル（アリ−ル）エーテル基からなる群より選ばれる基であって、炭素数が１〜２０である基である。］ The inventors of the present invention have reached the present invention as a result of studies to achieve the above object.
That is, the present invention provides a photoelectric conversion layer having a photoelectric conversion layer (E) containing a conductive polymer (d) and an electron acceptor (a) between two electrodes (Y) formed on a substrate (T). It is a conversion element (P), Comprising: This electroconductive polymer (d) contains the polyselenophene derivative (D) shown by following General formula (1), The photoelectric conversion element (P) characterized by the above-mentioned. .

[Wherein n represents an integer of 5 or more. R ¹ is selected from the group consisting of a hydroxyl group, a cyano group, a phosphoric acid group, a sulfonic acid group, and a halogen atom, and R ² may have an aliphatic hydrocarbon group that may have a substituent or a substituent. It is a group selected from the group consisting of a good aromatic hydrocarbon group and polyoxyalkylene alkyl (aryl) ether group, and a group having 1 to 20 carbon atoms. ]

  In the present invention, by using a polyselenophene derivative as the conductive polymer (hole transport layer), the hole transport property is improved and high photoelectric conversion efficiency can be achieved.

It is a schematic sectional drawing which shows an example of the photoelectric conversion element of this invention.

(T) Substrate (Y) Electrode (i-1) Hole extraction layer (E) Photoelectric conversion layer (i-2) Electron extraction layer

  The photoelectric conversion element of the present invention is a photoelectric conversion in which a photoelectric conversion layer containing a conductive polymer containing a polyselenophene derivative (D) and an electron acceptor is provided between two electrodes formed on a substrate. It is an element.

The polyselenophene derivative (D) is represented by the general formula (1).
In the polyselenophene derivative (D), from the viewpoint of hole transportability, n (degree of polymerization) is preferably 5 or more, more preferably 5 to 1000, and still more preferably 100 to 500.
R ¹ is a group represented by a hydroxyl group, a cyano group, a phosphoric acid group, a sulfonic acid group, or a halogen atom, and R ² is a group having 1 to 20 carbon atoms and may have a substituent. They are an aliphatic hydrocarbon group, an aromatic hydrocarbon group which may have a substituent, and a polyoxyalkylene alkyl (aryl) ether group. Here, the aromatic hydrocarbon group includes a group having an aromatic ring other than a phenyl group and a group having an aromatic ring which is a heterocyclic ring. The polyoxyalkylene alkyl (aryl) ether group means a polyoxyalkylene alkyl ether group or a polyoxyalkylene aryl ether group.
Examples of the aliphatic hydrocarbon group which may have a substituent include n-butyl group, n-hexyl group, n-octyl group, n-nonyl group, 2-ethylhexyl group, 2-ethyloctyl group, 3- A cyanooctyl group, a 9-sulfonylnonyl group, etc. are mentioned.
Examples of the aromatic hydrocarbon group which may have a substituent include a phenyl group, a naphthyl group, a pyrene group, and a 4-methoxyphenyl group.
Examples of the polyoxyalkylene alkyl (aryl) ether group include a triethylene glycol methyl ether group and a tetrapropylene glycol ethyl ether group.
The phosphoric acid group and the sulfonic acid group are groups represented by the following general formulas (2) to (3), respectively.

Among these, R ¹ is preferably a halogen atom, and examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.
Among the above, R ² is preferably an aliphatic hydrocarbon group which may have a substituent.
In the formula, when n (degree of polymerization) is less than 5, or R ¹ and R ² are organic groups other than the above, or the hetero atom of the main chain aromatic five-membered ring is other than Se, a polyselenophene derivative ( This is not preferable because the hole transport property of D) is lowered.

  Preferable specific examples of the polyselenophene derivative (D) include, for example, compounds represented by the general formulas (4) to (8) described in the following examples.

Production Method of Polyselenophene Derivative (D) Tetrabromoselenophene is obtained by stirring a solution (for example, chloroform solution) containing 4 equivalents of bromine, for example, for 12 hours at 25 ° C. with respect to 1 equivalent of selenophene. A solution obtained by adding, for example, 2 equivalents of a reducing reagent (for example, zinc powder) to 1 equivalent of tetrabromoselenophene, for example, by refluxing for 12 hours, 3,4-dibromoselenophene is obtained. I can get it.
A 3,4-substituted selenophene can be obtained by separately performing the 3rd and 4th positions of this 3,4-dibromoselenophene, for example, by Grignard reaction, Williamson ether synthesis method, and fluorine substitution reaction.
A solution (for example, a tetrahydrofuran solution) in which 1 equivalent of a Grignard reagent and 0.02 equivalent of a nickel catalyst (for example, Ni (dppp) Cl ₂ ) is added to 1 equivalent of the 3,4-substituted selenophene, For example, the polyselenophene derivative (D) can be obtained by refluxing for 12 hours.
A specific manufacturing method may be performed by the method described in Chemistry of Materials, 2005, No. 17, pp. 3317-3319, or Journal of the American Chemical Society, 1995, No. 117, pp. 233-244. it can.

  The photoelectric conversion element of the present invention comprises a photoelectric conversion layer (E) containing a conductive polymer (d) and an electron acceptor (a) between two electrodes (Y) formed on a substrate (T). A photoelectric conversion element (P). As an example, FIG. 1 shows a schematic sectional view of a typical structure thereof. Details of each component will be described below.

(1) Substrate (T)
The substrate in the present invention will be described. The substrate may be either transparent or opaque, but a transparent substrate is desirable when the substrate surface is a photoreceptor. As this transparent substrate, a substrate excellent in moisture and gas barrier properties, solvent resistance, weather resistance and the like entering from the outside of the photoelectric conversion element is desirable. For example, a rigid plate such as quartz glass, a flexible resin such as a transparent resin film, etc. A substrate is mentioned. Furthermore, in the present invention, a flexible substrate is desirable from the viewpoint of excellent workability, low cost, and light weight. Examples of the transparent resin film include polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polystyrene, polyethylene, polyvinylidene fluoride, polyimide, and polymethyl methacrylate.

(2) Electrode (Y)
Then, the electrode in this invention is demonstrated.
The electrode may or may not be layered on the substrate (T), but is preferably layered. The electrode does not necessarily have translucency, but when the electrode is layered on the substrate (T), it is preferable that at least one of the electrodes has translucency. It is preferable that the electrode is composed of two layers and has two layers. Any electrode may be used as long as it has conductivity, and it is formed by sputtering, ion plating, or the like. As the light transmissive electrode, a metal thin film made of a conductive transparent material such as indium-tin composite oxide (ITO), fluorine-doped SnO ₂ (FTO), SnO ₂ is preferable, and as the light shielding electrode, an alkali metal, Metal thin films such as alkaline earth metals are preferred. Although the thickness of this electrode is not specifically limited, For example, it is about 80-100 nm.

(3) Photoelectric conversion layer (E)
Then, the photoelectric converting layer used for this invention is demonstrated. The photoelectric conversion layer in the present invention contains a conductive polymer (d) and an electron transport layer (electron acceptor) (a), and preferably also serves as a hole transport layer (hole acceptor) (s). A conductive polymer (d) and an electron transport layer (electron acceptor) (a).
The form of the conductive polymer (hole transport layer, hole acceptor) and electron transport layer (electron acceptor) contained is not particularly limited, but preferably an electron hole in which both are mixed. A single layer structure called a transport layer, that is, a bulk heterojunction. By adopting this structure, a pn junction at the molecular level becomes possible, and thus an effect of increasing the volume involved in photoelectric conversion can be obtained.
The photoelectric conversion layer (E) as described above can be obtained by removing the solvent from the mixed solution of the conductive polymer (d) and the electron acceptor (a).

In the present invention, the conductive polymer (d) (hole transport layer, hole acceptor) contains at least the polyselenophene derivative (D). By using this, hole transportability is improved, and high photoelectric conversion efficiency is obtained.
The reason is estimated as follows.
(I) The conductive polymer (d) (hole transport layer, hole acceptor) of the present invention has a small HOMO-LUMO gap of the conductive polymer from the viewpoint of the frontier orbit, and has a hole transfer speed. Big enough.
(Ii) The conductive polymer (d) (hole transport layer, hole acceptor) of the present invention has good compatibility with the electron transport layer and has sufficient bulk heterojunction.

  As explained above, the conductive polymer (d) is preferably one that functions as a hole transport layer (hole acceptor) (s), and a polyselenophene derivative is preferred. On the other hand, for the electron transport layer (electron acceptor (a)), fullerene derivatives such as [6,6] -phenyl-C61 butyric acid methyl ester (hereinafter referred to as PCBM) are exemplified.

  In the present invention, as the weight ratio of the conductive polymer (d) and the electron transport layer (electron acceptor) (a) used in the above-described photoelectric conversion layer, an electron hole transport layer having good electron transport ability is formed. Although not particularly limited, for example, (d) / (a) = 1/10 to 1 / 0.4 is preferable, and the mixing ratio is appropriately changed depending on the combination of other constituent material types. Things are preferable.

  The conductive polymer (d) may further contain a conductive polymer (d ′) other than the polyselenophene derivative (D). Examples of the conductive polymer (d ′) include polythiophene, polyfluorene, and the like. The weight ratio of the polyselenophene derivative (D) and the conductive polymer (d ′) is excellent in electron transport ability. Although it will not specifically limit if the electron hole transport layer which has has is formed, For example, (D) / (d ') = 20 / 0-16 / 4 is preferable, 18 / 2-17 / 3 is more preferable, It is preferable that the mixing ratio is appropriately changed depending on the combination of other constituent material types.

  In the present invention, the film thickness of the above-described photoelectric conversion layer is not particularly limited, and any film thickness may be used. However, if the film thickness is too thin, the film is short-circuited, and if it is too thick, the film resistance becomes high. Therefore, the film thickness used for a general photoelectric conversion element is preferable, for example, 20 to 800 nm.

  In the present invention, the method for forming the photoelectric conversion layer described above is not particularly limited as long as it can be uniformly formed in a predetermined film thickness, and any method may be used. For example, a spin coating method or a die coating method can be used.

  In the present invention, the number of the photoelectric conversion layers described above may be one layer or a plurality of layers, and is not particularly limited. For example, 1 to 5 layers are preferable.

(5) Other structure The other structure used for this invention is demonstrated. A charge extraction layer (i) may be formed in the photoelectric conversion element of the present invention for the purpose of promoting the movement of charges.
The compound and the number of layers are not particularly limited. For example, as the hole extraction layer (i-1), poly (styrene sulfonate) / poly (2,3-dihydrothieno [3,4- b] -1,4-dioxin) (hereinafter referred to as “PEDOT / PSS”) and the electron extraction layer (i-2) include titanium dioxide (hereinafter referred to as TiO _x ).

  When the photoelectric conversion element (P) of the present invention is used as a solar cell element (S), a conductive polymer (d) and an electron acceptor are interposed between two electrodes (Y) formed on the substrate (T). It is a solar cell element (S) which has the photoelectric converting layer (E) containing a body (a), and those structures etc. which were demonstrated by the said photoelectric converting element (P) are preferable.

  When the solar cell element (S) of the present invention is used as a tandem solar cell element (S1), those described for the solar cell element (S) are preferable. In addition, the number of stacked layers is not particularly limited. For example, the number of stacked layers is about 1 to 5, and the connection state of each solar cell element (S) may be either parallel or series. Are preferably in parallel, and in order to increase the voltage to be extracted, series is preferable.

  When the photoelectric conversion element (P) of the present invention is used as an optical sensor element (U), a conductive polymer (d) and an electron acceptor are interposed between two electrodes (Y) formed on a substrate (T). It is an optical sensor element (U) which has a photoelectric conversion layer (E) containing a body (a), and those structures etc. which were demonstrated by the said photoelectric conversion element (P) are preferable.

EXAMPLES Hereinafter, although an Example demonstrates this invention in more detail, this invention is not limited to this.
Hereinafter, unless otherwise specified, “parts” and “wt” mean “parts by weight” and% means% by weight.

(Production Example 1)
As a polyselenophene derivative, poly-3-cyano-4- (2-methoxyethoxy) selenophene-2,5-diyl [hereinafter referred to as PC (MOEO) S. Compound represented by general formula (4)] was synthesized.

Synthesis of PC (MOEO) S [general formula (4)] After 2.5 g of selenophene (manufactured by Aldrich Co.) was dissolved in 4 ml of chloroform, 4.32 ml of bromine (manufactured by Wako Pure Chemical Industries, Ltd.) was added for 30 minutes. And the solution was stirred at 50 ° C. for 24 hours. After adding 50 ml of chloroform and washing the organic layer three times with a 1 M sodium hydroxide aqueous solution, the organic layer was washed twice with a 1 M sodium thiosulfate aqueous solution. After drying with magnesium sulfate, the solvent was distilled off under reduced pressure and purified by silica gel column chromatography (developing solvent; n-hexane) to obtain 2,3,4,5-tribromoselenophene (hereinafter referred to as TriBS). 6.57 g was obtained. This synthesis method was based on the method described in Organic Synthesis, 1973, No. 5, pages 149-151.

  After suspending 2.50 g of zinc powder (manufactured by Wako Pure Chemical Industries, Ltd.) in a mixed solution of 2.7 ml of water and 11.0 ml of glacial acetic acid (manufactured by Wako Pure Chemical Industries, Ltd.), the solution was heated at 100 ° C. Stir for 2 hours. After cooling to 25 ° C., TriBS 6.57 g dissolved in 10 ml of chloroform was added and stirred at 100 ° C. for 6 hours. 50 ml of chloroform was added, and the organic layer was washed three times with a 1M aqueous potassium hydrogen carbonate solution. After drying with magnesium sulfate, the solvent was distilled off under reduced pressure, and the residue was purified by silica gel column chromatography (developing solvent: n-hexane) to obtain 4.90 g of 3,4-dibromoselenophene (hereinafter referred to as DBS). It was.

DBS 2.10 g, Zn (CN) ₂ 1.18 g (manufactured by Wako Pure Chemical Industries, Ltd.), Pd (PPh ₃ ) ₄ 0.35 g (manufactured by Wako Pure Chemical Industries, Ltd.) were added to 50 ml of DMF, and a reaction vessel was added. The inside was purged with nitrogen and stirred at 100 ° C. for 24 s. 60 ml of ethyl acetate was added, and the organic layer was washed 3 times with water. After drying with magnesium sulfate, the solvent was distilled off under reduced pressure, and the residue was purified by silica gel column chromatography (developing solvent; n-hexane) to give 1.55 g of 3-bromo-4-cyanoselenophene (hereinafter referred to as BCS). Got. This synthesis method was based on the method described in Journal of Organic Chemistry, 2000, No. 65, pages 7984-7899.

  After 0.6 g of NaH (manufactured by Wako Pure Chemical Industries, Ltd.) was suspended in 2.5 ml of DMF, the inside of the reaction vessel was purged with nitrogen and cooled to 0 ° C. 2.65 ml of 2-methoxyethanol (manufactured by Wako Pure Chemical Industries, Ltd.) was added dropwise over 30 minutes and stirred for 1 hour. 2.35 g of BCS and 0.14 g of CuBr (manufactured by Wako Pure Chemical Industries, Ltd.) were added to the reaction solution and stirred at 110 ° C. for 30 minutes. A 1M ammonium chloride aqueous solution was added, extracted with diethyl ether, and the organic layer was washed three times with a 1M ammonium chloride aqueous solution. After drying with magnesium sulfate, the solvent was distilled off under reduced pressure, and the residue was purified by silica gel column chromatography (developing solvent; n-hexane) to give 3-cyano-4 (2-methoxyethoxy) selenophene (hereinafter referred to as C (MOEO)). 1.33 g was obtained. This synthesis method was based on the method described in Chemistry of Materials, 2005, No. 17, pages 3317-3319.

  After 1.58 g of C (MOEO) S was dissolved in 70 ml of tetrahydrofuran, the inside of the reaction vessel was purged with nitrogen and cooled to 0 ° C. A solution prepared by dissolving 2.44 g of N-bromosuccinimide (manufactured by Wako Pure Chemical Industries, Ltd.) in 7 ml of tetrahydrofuran was added dropwise over 5 minutes, followed by stirring at 0 ° C. for 1 hour. 50 ml of n-hexane was added, the organic layer was washed twice with a 1 M sodium thiosulfate aqueous solution, and the organic layer was washed twice with saturated brine. After drying with magnesium sulfate, the solvent was distilled off under reduced pressure, and the residue was purified by silica gel column chromatography (developing solvent; n-hexane), and 2,5-dibromo-3-cyano-4- (2-methoxyethoxy) selenophene. 1.98 g (hereinafter referred to as DBC (MOEO) S) was obtained. This synthesis method was based on the method described in Journal of American chemical Society, 2006, No. 128, pages 10930-10933.

After dissolving 2.39 g of DBC (MOEO) S in 70 ml of tetrahydrofuran, the inside of the reaction vessel was purged with nitrogen, and 6.16 ml of methylmagnesium bromide (1M n-hexane solution) (manufactured by Tokyo Chemical Industry Co., Ltd.) was taken over 30 minutes. Then, the mixture was stirred at room temperature for 30 minutes. A suspension of 10 mg of Ni (dppp) Cl _{2 in} 10 ml of tetrahydrofuran was added dropwise over 5 minutes, and the mixture was stirred under reflux conditions for 12 hours. The mixture was cooled to 25 ° C., a mixed solution of 12 ml of 1M hydrochloric acid and 247 ml of methanol was added, and the precipitate was collected by filtration. Using a Soxhlet extractor, hexane and methanol were washed in this order and extracted with chloroform. Methanol was added, and the precipitate was collected by filtration to obtain 1.3 g of poly-3-cyano-4- (2-methoxyethoxy) selenophene-2,5-diyl (hereinafter referred to as PC (MOEO) S). This synthesis method is described in Chemistry of Materials, 2005, 17, pages 3317-3319, and Journal of American chemical Society, 1995, 117, 233-244, and Advanced Materials 11, 1999-2, 1999-2. And the method described in Macromolecules, 2001, 34, 4324-4333.

(Production Example 2)
As a polyselenophene derivative, poly-3-phosphonyl-4- (3-pyridinyl) selenophene-2,5-diyl (hereinafter referred to as PPPS, a compound represented by the general formula (5)) was synthesized.

Synthesis of PPPS (General Formula (5)) After 4.04 g of DBS (intermediate of Production Example 1) was dissolved in 5 ml of tetrahydrofuran, [1,3-bis (diphenylphosphino) propane] nickel (II) chloride ( In the following, 0.152 g (referred to as Ni (dppp) Cl ₂ ) (manufactured by Wako Pure Chemical Industries, Ltd.) was suspended, the inside of the reaction vessel was purged with nitrogen, and then 50 ml of pyridine magnesium bromide (1M THF solution) (3-bromo After dropwise adding 7.90 g of pyridine (manufactured by Wako Pure Chemical Industries, Ltd.) and 1.21 g of magnesium (manufactured by Wako Pure Chemical Industries, Ltd.) to 41 ml of THF solution and stirring for 20 hours at room temperature over 30 minutes. And stirred at room temperature for 40 hours. After adding 50 ml of n-hexane and neutralizing with 50 ml of 3M hydrochloric acid, the aqueous layer and the organic layer were separated by saturating the aqueous solution with magnesium sulfate, and an organic layer was obtained by liquid separation. After drying with magnesium sulfate, the solvent was distilled off under reduced pressure, and the residue was purified by silica gel column chromatography (developing solvent; n-hexane) to give 3-bromo-4- (3-pyridinyl) selenophene (hereinafter referred to as BPS). 0.79 g was obtained. This synthesis method was based on the methods described in Thin Solid Films, 2008, No. 516, pages 3978-3988, and Chemistry of Materials, 1994, No. 6, pages 640-649.

  2.87 g of BPS and 2.49 g of triethyl phosphite (manufactured by Wako Pure Chemical Industries, Ltd.) were mixed and stirred at 100 ° C. for 20 hours. The solution was cooled to 25 ° C. and purified by silica gel column chromatography (developing solvent; ethyl acetate) to obtain 1.86 g of 3-diethylphosphon-4- (3-pyridinyl) selenophene (hereinafter referred to as PEPS). This synthesis method was based on the method described in Synthesis, 2004, No. 5, pages 668-670.

  1.22 g of PEPS was added to 100 ml of 6 M hydrochloric acid aqueous solution, and the mixture was stirred at 100 ° C. for 10 hours. After adding 100 ml of ethyl acetate, the organic layer was separated and dried over magnesium sulfate, the solvent was distilled off under reduced pressure, the residue was purified by silica gel column chromatography (developing solvent; ethyl acetate), and 3-phosphonyl-4- ( 0.55 g of 3-pyridinyl) selenophene (hereinafter referred to as PPS) was obtained. This synthesis method was based on the method described in Tetrahedron Letters, 2007, No. 48, pages 4051-4054.

  After dissolving 1.98 g of PPS in 70 ml of tetrahydrofuran, the reaction vessel was purged with nitrogen and cooled to 0 ° C. A solution prepared by dissolving 2.44 g of N-bromosuccinimide (manufactured by Wako Pure Chemical Industries, Ltd.) in 7 ml of tetrahydrofuran was added dropwise over 5 minutes, followed by stirring at 0 ° C. for 1 hour. 50 ml of n-hexane was added, the organic layer was washed twice with a 1 M sodium thiosulfate aqueous solution, and the organic layer was washed twice with saturated brine. After drying with magnesium sulfate, the solvent was distilled off under reduced pressure, and the residue was purified by silica gel column chromatography (developing solvent; ethyl acetate), and 2,5-dibromo-3-phosphonyl-4- (3-pyridinyl) selenophene (hereinafter referred to as “separate”). (Referred to as DBPPS). This synthesis method was based on the method described in Journal of American chemical Society, 2006, No. 128, pages 10930-10933.

After 2.75 g of DBPPS was dissolved in 70 ml of tetrahydrofuran, the inside of the reaction vessel was purged with nitrogen, and 6.16 ml of methylmagnesium bromide (1M n-hexane solution) (manufactured by Tokyo Chemical Industry Co., Ltd.) was added dropwise over 30 minutes. And stirred at room temperature for 30 minutes. A suspension of 10 mg of Ni (dppp) Cl _{2 in} 10 ml of tetrahydrofuran was added dropwise over 5 minutes, and the mixture was stirred under reflux conditions for 12 hours. The mixture was cooled to 25 ° C., a mixed solution of 12 ml of 1M hydrochloric acid and 247 ml of methanol was added, and the precipitate was collected by filtration. Using a Soxhlet extractor, hexane and methanol were washed in this order and extracted with chloroform. Methanol was added and the precipitate was collected by filtration to obtain 1.5 g of poly-3-phosphonyl-4- (3-pyridinyl) selenophene-2,5-diyl (hereinafter referred to as PPPS). This synthesis method is described in Chemistry of Materials, 2005, 17, pages 3317-3319, and Journal of American chemical Society, 1995, 117, 233-244, and Advanced Materials 11, 1999-2, 1999-2. And the method described in Macromolecules, 2001, 34, 4324-4333.

(Production Example 3)
As a polyselenophene derivative, poly-3-sulfonyl-4-phenylselenophene-2,5-diyl (hereinafter referred to as PSPS, a compound represented by the general formula (6)) was synthesized.

Synthesis of PSPS (general formula (6)) After 4.04 g of DBS (intermediate of Production Example 1) was dissolved in 5 ml of tetrahydrofuran, [1,3-bis (diphenylphosphino) propane] nickel (II) chloride ( In the following, 0.152 g (referred to as Ni (dppp) Cl ₂ ) (manufactured by Wako Pure Chemical Industries, Ltd.) was suspended, the inside of the reaction vessel was purged with nitrogen, and then 50 ml of phenylmagnesium bromide (2M THF solution) (Tokyo Chemical ( Co., Ltd.) was added dropwise over 30 minutes, followed by stirring at room temperature for 40 hours. After adding 50 ml of n-hexane and neutralizing with 50 ml of 3M hydrochloric acid, the aqueous layer and the organic layer were separated by saturating the aqueous solution with magnesium sulfate, and an organic layer was obtained by liquid separation. After drying with magnesium sulfate, the solvent was distilled off under reduced pressure, and the residue was purified by silica gel column chromatography (developing solvent; n-hexane) to give 1.57 g of 3-bromo-4-phenylselenophene (hereinafter referred to as BPhS). Got. This synthesis method was based on the methods described in Thin Solid Films, 2008, No. 516, pages 3978-3988, and Chemistry of Materials, 1994, No. 6, pages 640-649.

  After 1.57 g of BPhS and 0.22 g of sodium hydrogen sulfite (manufactured by Wako Pure Chemical Industries, Ltd.) were dissolved in 4 ml of ion-exchanged water, sodium hydroxide having a concentration of 30% was added until the pH reached 7.6. After adding 0.045 g of CuCl, the mixture was stirred at 140 ° C. for 16 hours. After cooling to 40 ° C., the precipitate was filtered off and 0.75 ml of concentrated hydrochloric acid was added. Unreacted BPhS that had precipitated was removed by filtration, 1.2 g of potassium chloride (manufactured by Wako Pure Chemical Industries, Ltd.) was added, and the mixture was stirred at 100 ° C. for 1 hour. After standing at 5 ° C. for 16 hours, the precipitate was collected by filtration to obtain 1.05 g of 3-sulfonyl-4-phenylselenophene (hereinafter referred to as SPS). This synthesis method was based on the method described in Journal of Medicinal Chemistry, 1987, No. 30, pages 678-682.

  After 1.97 g of SPS was dissolved in 70 ml of tetrahydrofuran, the inside of the reaction vessel was purged with nitrogen and cooled to 0 ° C. A solution prepared by dissolving 2.44 g of N-bromosuccinimide (manufactured by Wako Pure Chemical Industries, Ltd.) in 7 ml of tetrahydrofuran was added dropwise over 5 minutes, followed by stirring at 0 ° C. for 1 hour. 50 ml of n-hexane was added, the organic layer was washed twice with a 1 M sodium thiosulfate aqueous solution, and the organic layer was washed twice with saturated brine. After drying with magnesium sulfate, the solvent was distilled off under reduced pressure, the residue was purified by silica gel column chromatography (developing solvent; ethyl acetate), and 2,5-dibromo-3-sulfonyl-4-phenylselenophene (hereinafter referred to as DBSPS). 2.06 g was obtained. This synthesis method was based on the method described in Journal of American chemical Society, 2006, No. 128, pages 10930-10933.

After dissolving 2.74 g of DBSPS in 70 ml of tetrahydrofuran, the inside of the reaction vessel was purged with nitrogen, and 6.16 ml of methylmagnesium bromide (1M n-hexane solution) (manufactured by Tokyo Chemical Industry Co., Ltd.) was added dropwise over 30 minutes. And stirred at room temperature for 30 minutes. A suspension of 10 mg of Ni (dppp) Cl _{2 in} 10 ml of tetrahydrofuran was added dropwise over 5 minutes, and the mixture was stirred under reflux conditions for 12 hours. The mixture was cooled to 25 ° C., a mixed solution of 12 ml of 1M hydrochloric acid and 247 ml of methanol was added, and the precipitate was collected by filtration. Using a Soxhlet extractor, hexane and methanol were washed in this order and extracted with chloroform. Methanol was added, and the precipitate was collected by filtration to obtain 1.4 g of poly-3-sulfonyl-4-phenylselenophene-2,5-diyl (hereinafter referred to as PSPS). This synthesis method is described in Chemistry of Materials, 2005, 17, pages 3317-3319, and Journal of American chemical Society, 1995, 117, 233-244, and Advanced Materials 11, 1999-2, 1999-2. And the method described in Macromolecules, 2001, 34, 4324-4333.

(Production Example 4)
As a polyselenophene derivative, poly-3-bromo-4- (2-ethylhexyl) selenophene-2,5-diyl (hereinafter referred to as PBEHS, a compound represented by the general formula (7)) was synthesized.

Synthesis of PBEHS (general formula (7)) After 4.04 g of DBS (intermediate of Production Example 1) was dissolved in 5 ml of tetrahydrofuran, [1,3-bis (diphenylphosphino) propane] nickel (II) chloride ( Thereafter, 0.152 g of Ni (dppp) Cl ₂ (manufactured by Wako Pure Chemical Industries, Ltd.) was suspended, the inside of the reaction vessel was purged with nitrogen, and then 57 ml of 2-ethylhexyl magnesium bromide (1M diethyl ether solution) ( Aldrich Co.) was added dropwise over 30 minutes and then stirred at room temperature for 40 hours. After adding 50 ml of n-hexane and neutralizing with 50 ml of 3M hydrochloric acid, the aqueous layer and the organic layer were separated by saturating the aqueous solution with magnesium sulfate, and an organic layer was obtained by liquid separation. After drying with magnesium sulfate, the solvent was distilled off under reduced pressure, and the residue was purified by silica gel column chromatography (developing solvent; n-hexane), and 3-bromo-4- (2-ethylhexyl) selenophene (hereinafter referred to as BEHS). 1.14 g was obtained. This synthesis method was based on the methods described in Thin Solid Films, 2008, No. 516, pages 3978-3988, and Chemistry of Materials, 1994, No. 6, pages 640-649.

  After dissolving BEHS (2.21 g) in tetrahydrofuran (70 ml), the reaction vessel was purged with nitrogen and cooled to 0 ° C. A solution prepared by dissolving 2.44 g of N-bromosuccinimide (manufactured by Wako Pure Chemical Industries, Ltd.) in 7 ml of tetrahydrofuran was added dropwise over 5 minutes, followed by stirring at 0 ° C. for 1 hour. 50 ml of n-hexane was added, the organic layer was washed twice with a 1 M sodium thiosulfate aqueous solution, and the organic layer was washed twice with saturated brine. After drying with magnesium sulfate, the solvent was distilled off under reduced pressure, the residue was purified by silica gel column chromatography (developing solvent; n-hexane), and 2,5-dibromo-3-bromo-4- (2-ethylhexyl) selenophene ( (Hereinafter referred to as TBEHS) 2.12 g was obtained. This synthesis method was based on the method described in Journal of American chemical Society, 2006, No. 128, pages 10930-10933.

After 2.96 g of TBEHS was dissolved in 70 ml of tetrahydrofuran, the inside of the reaction vessel was purged with nitrogen, and 6.16 ml of methylmagnesium bromide (1M n-hexane solution) (manufactured by Tokyo Chemical Industry Co., Ltd.) was added dropwise over 30 minutes. And stirred at room temperature for 30 minutes. A suspension of 10 mg of Ni (dppp) Cl _{2 in} 10 ml of tetrahydrofuran was added dropwise over 5 minutes, and the mixture was stirred under reflux conditions for 12 hours. The mixture was cooled to 25 ° C., a mixed solution of 12 ml of 1M hydrochloric acid and 247 ml of methanol was added, and the precipitate was collected by filtration. Using a Soxhlet extractor, hexane and methanol were washed in this order and extracted with chloroform. Methanol was added and the precipitate was collected by filtration to obtain 1.8 g of poly-3-bromo-4- (2-ethylhexyl) selenophene-2,5-diyl (hereinafter referred to as PBEHS). This synthesis method is described in Chemistry of Materials, 2005, 17, pages 3317-3319, and Journal of American chemical Society, 1995, 117, 233-244, and Advanced Materials 11, 1999-2, 1999-2. And the method described in Macromolecules, 2001, 34, 4324-4333.

(Production Example 5)
As a polyselenophene derivative, poly-3-hydroxy-4-hexylselenophene-2,5-diyl (hereinafter referred to as PHHS, a compound represented by the general formula (8)) was synthesized.

Synthesis of PHHS (General Formula (8)) After 4.04 g of DBS (intermediate of Production Example 1) was dissolved in 5 ml of tetrahydrofuran, [1,3-bis (diphenylphosphino) propane] nickel (II) chloride ( Hereafter, 0.152 g (referred to as Ni (dppp) Cl ₂ ) (Wako Pure Chemical Industries, Ltd.) was suspended, the inside of the reaction vessel was purged with nitrogen, and then n-hexylmagnesium bromide (1M n-hexane solution) 50 ml (Tokyo Chemical Industry Co., Ltd.) was added dropwise over 30 minutes, and then stirred at room temperature for 40 hours. After adding 50 ml of n-hexane and neutralizing with 50 ml of 3M hydrochloric acid, the aqueous layer and the organic layer were separated by saturating the aqueous solution with magnesium sulfate, and the organic layer was obtained by liquid separation. After drying with magnesium sulfate, the solvent was distilled off under reduced pressure, and the residue was purified by silica gel column chromatography (developing solvent; n-hexane), and 1.08 g of 3-bromo-4-hexylselenophene (hereinafter referred to as BHS) Got. This synthesis method was based on the methods described in Thin Solid Films, 2008, No. 516, pages 3978-3988, and Chemistry of Materials, 1994, No. 6, pages 640-649.

1.02 g of BHS and 0.11 g of magnesium were added to 3 ml of THF, and the inside of the reaction vessel was purged with nitrogen. Then, 0.06 g of BH ₃ (90% SMe ₂ solution) (manufactured by Aldrich Co., Ltd.) was added under reflux conditions. Stir for hours. After cooling to 25 ° C., 1 ml of water, 1.8 ml of 1M sodium hydroxide aqueous solution and 30% hydrogen peroxide aqueous solution were added in this order, and the mixture was stirred at 10 ° C. for 1 hour. Concentrated hydrochloric acid (1 ml) and ethyl acetate (50 ml) were added, the organic layer was separated, the organic layer was washed with saturated brine, dried over magnesium sulfate, the solvent was distilled off under reduced pressure, and silica gel column chromatography (developing solvent; n- (Hexane / ethyl acetate) to obtain 0.45 g of 3-hydroxy-4-hexylselenophene (hereinafter referred to as HHS). This synthesis method was based on the method described in Chemistry a European journal, 2003, No. 9, pages 1922-1932.

  After 2.02 g of HHS was dissolved in 70 ml of tetrahydrofuran, the inside of the reaction vessel was purged with nitrogen and cooled to 0 ° C. A solution prepared by dissolving 1.22 g of N-bromosuccinimide (manufactured by Wako Pure Chemical Industries, Ltd.) in 7 ml of tetrahydrofuran was added dropwise over 5 minutes, followed by stirring at 0 ° C. for 1 hour. 50 ml of n-hexane was added, the organic layer was washed twice with a 1 M sodium thiosulfate aqueous solution, and the organic layer was washed twice with saturated brine. After drying with magnesium sulfate, the solvent was distilled off under reduced pressure, and the residue was purified by silica gel column chromatography (developing solvent; n-hexane), and 2,5-dibromo-3-hydroxy-4-hexylselenophene (hereinafter referred to as DBHHS). 2.25 g was obtained. This synthesis method was based on the method described in Journal of American chemical Society, 2006, No. 128, pages 10930-10933.

After dissolving 2.40 g of DBHHS in 70 ml of tetrahydrofuran, the inside of the reaction vessel was purged with nitrogen, and 6.16 ml of methylmagnesium bromide (1M n-hexane solution) (manufactured by Tokyo Chemical Industry Co., Ltd.) was added dropwise over 30 minutes. And stirred at room temperature for 30 minutes. A suspension of 10 mg of Ni (dppp) Cl _{2 in} 10 ml of tetrahydrofuran was added dropwise over 5 minutes, and the mixture was stirred under reflux conditions for 12 hours. The mixture was cooled to 25 ° C., a mixed solution of 12 ml of 1M hydrochloric acid and 247 ml of methanol was added, and the precipitate was collected by filtration. Using a Soxhlet extractor, hexane and methanol were washed in this order and extracted with chloroform. Methanol was added, and the precipitate was collected by filtration to obtain 0.94 g of poly-3-hydroxy-4-hexylselenophene-2,5-diyl (hereinafter referred to as PHHS). This synthesis method is described in Chemistry of Materials, 2005, 17, pages 3317-3319, and Journal of American chemical Society, 1995, 117, 233-244, and Advanced Materials 11, 1999-2, 1999-2. And the method described in Macromolecules, 2001, 34, 4324-4333.

Example 1
(Creation of transparent electrode (Y))
As the transparent substrate and the transparent conductive film, a polyethylene terephthalate (hereinafter referred to as PET) film with an ITO film having a size of 25 mm square and a sheet resistance of 10 Ω / cm ⁻² was used. And after forming the mask of a predetermined shape on the ITO film | membrane, the ITO film | membrane was patterned by immersing this in 1N hydrochloric acid for 1 hour, and the transparent electrode was formed.

(Preparation of hole extraction layer (i-1))
1.3% by weight of poly (styrene sulfonate) / poly (2,3-dihydrothieno [3,4-b] -1, on a PET film on which a transparent electrode made of an ITO film is formed as described above. 4-dioxin) (hereinafter referred to as “PEDOT / PSS”) (product name: BaytronP, manufactured by Bayer), spin-coated at 120 ° C. for 30 minutes to form a PEDOT / PSS film having a thickness of about 100 nm. This was designated as a hole extraction layer (i-1).

(Creation of photoelectric conversion layer (E))
Furthermore, PC (MOEO) S (polyselenophene derivative synthesized in Production Example 1) / PCBM (manufactured by Frontier Carbon Co., Ltd.) (weight ratio is 1 / 0.5) is slightly larger than the PEDOT / PSS film. A mixed solution (PFHS: PCBM = 75 mg: 37.5 mg dissolved in 5.0 mL of chlorobenzene) was spin-coated on the hole extraction layer (i-1), and then, under nitrogen flow for 6 minutes 150 minutes Drying was performed at 0 ° C. to form a photoelectric conversion layer (E).

(Creation of electron extraction layer (i-2))
Furthermore, after spin-coating what melt | dissolved 10 microliters of titanium tetraisopropoxide (made by Wako Pure Chemical Industries, Ltd.) in 3 mL of ethanol as an electronic taking-out layer (i-2) on the photoelectric converting layer (E), Was allowed to stand for 30 minutes to cause hydrolysis to form a titanium dioxide (TiO _x ) layer.

(Create counter electrode)
Finally, an Al film having a thickness of 125 nm was formed as a counter electrode on the electron extraction layer (i-2) by vacuum deposition on the photoelectric conversion layer. The photoelectric conversion element (P-1) was manufactured as described above.

(Example 2)
A photoelectric conversion element (same as in Example 1) except that the PC (MOEO) S / PCBM mixed solution in Example 1 was replaced with a PPPS (polyselenophene derivative synthesized in Production Example 2) / PCBM mixed solution. P-2) was formed. As a specific mixed solution, a solution containing PPPS: PCBM = 75 mg: 37.5 mg in 5.0 mL of chlorobenzene was used.

Example 3
A photoelectric conversion element (same as in Example 1) except that the PC (MOEO) S / PCBM mixed solution in Example 1 was replaced with a PSPS (polyselenophene derivative synthesized in Production Example 3) / PCBM mixed solution. P-3) was formed. As a specific mixed solution, a solution containing PSPS: PCBM = 75 mg: 37.5 mg in 5.0 mL of chlorobenzene was used.

Example 4
A photoelectric conversion element (same as in Example 1) except that the PC (MOEO) S / PCBM mixed solution in Example 1 was replaced with a PBEHS (polyselenophene derivative synthesized in Production Example 4) / PCBM mixed solution. P-4) was formed. As a specific mixed solution, a solution containing PBEHS: PCBM = 75 mg: 37.5 mg in 5.0 mL of chlorobenzene was used.

(Example 5)
A photoelectric conversion element (same as in Example 1) except that the PC (MOEO) S / PCBM mixed solution in Example 1 was replaced with PHHS (polyselenophene derivative synthesized in Production Example 5) / PCBM mixed solution. P-5) was formed. As a specific mixed solution, a solution containing PHHS: PCBM = 75 mg: 37.5 mg in 5.0 mL of chlorobenzene was used.

(Comparative Example 1)
The PFHS / PCBM mixed solution in Example 1 was replaced with poly-3-hexylthiophene-2,5-diyl (hereinafter referred to as P3HT) (manufactured by Wako Pure Chemical Industries, Ltd., product name 0447746) / PCBM mixed solution. Formed a photoelectric conversion element (P′-1) in the same manner as in Example 1. As a specific mixed solution, a solution containing P3HT: PCBM = 75 mg: 37.5 mg in 5.0 mL of chlorobenzene was used.

(Evaluation method of photoelectric conversion element)
The photoelectric conversion element was measured by irradiating the photoelectric conversion element with simulated light (air passage amount AM1.5G, incident energy 100 mW / cm ² ) of a solar simulator (manufactured by Kansai Scientific Machinery Co., Ltd .: XES-502S). Irradiation conditions: Temperature 25 ° C

Using a KEITHLEY MODEL 2400 source meter, an I (current) -V (voltage) curve was measured, and I _sc (short circuit current), V _oc (open voltage), I _MAX (current at the maximum output point), V _MAX ( Voltage at the maximum output point).
Generally, the photoelectric conversion efficiency of a photoelectric conversion element is represented by the following formula.
Photoelectric conversion efficiency η = J _sc (short circuit current density) × V _oc (open circuit voltage) × ff (form factor) / incident energy Here, J _sc (short circuit current density) and ff (form factor) are obtained by the following equations. It was.
Form factor ff = (I _MAX × V _MAX ) / (I _sc × V _oc )
Short-circuit current density J _sc = I _sc / S (effective light receiving area)
However, S = 2.5 cm × 2.5 cm = 6.25 cm ²
The measurement results are shown in Table 1.

  From the above evaluation results, the polyselenophene derivative as the conductive polymer (hole acceptor, hole transport layer) in the present invention is different from the conventional conductive polymer (hole acceptor, hole transport layer). In comparison, it was proved to show excellent photoelectric conversion efficiency.

  The present invention is not limited to use as a solar cell, a color sensor, and the like, but can be widely applied to electronic devices and electronic components that include photoelectric conversion elements.

Claims (5)

A photoelectric conversion element (P) having a photoelectric conversion layer (E) containing a conductive polymer (d) and an electron acceptor (a) between two electrodes (Y) formed on a substrate (T). Then, the conductive polymer (d) contains a polyselenophene derivative (D) represented by the following general formula (1), a photoelectric conversion element (P).

[Wherein n represents an integer of 5 or more. R ¹ is selected from the group consisting of a hydroxyl group, a cyano group, a phosphoric acid group, a sulfonic acid group, and a halogen atom, and R ² has an aliphatic hydrocarbon group that may have a substituent and a substituent. It is a group selected from the group consisting of a good aromatic hydrocarbon group and a polyoxyalkylene alkyl (aryl) ether group, and a group having 1 to 20 carbon atoms. ] ^{2. The} photoelectric conversion element (P) according to claim 1, wherein in general formula (1), R ¹ is a halogen atom, and R ² is an aliphatic hydrocarbon group which may have a substituent.   It is a solar cell element (S), The photoelectric conversion element (P) of Claim 1 or 2.   The photoelectric conversion element (P) according to claim 3, wherein the solar cell element (S) is a tandem solar cell element (S1). It is a photo sensor element (U), The photoelectric conversion element (P) of any one of Claims 1-4.

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