Conductive polymer solution and its uses

Abstract

To provide a self-doped conducting polymer solution with a work function suitable for a hole transport layer.SOLUTION: A conducting polymer solution comprises 0.01-10 wt.% of a polythiophene (A) obtained by polymerization of a compound represented by the general formula (3), and a metal oxo acid salt (B).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a conductive polymer solution and its use. [Background technology]

[0002] In recent years, in the fields of organic solar cells and organic EL devices, transparent electrodes have been used, such as indium tin oxide (ITO) electrodes and fluorine-doped tin oxide (FTO) electrodes. However, the work function of ITO electrodes is shallow, at approximately 4.6 eV, and this tends to create an energy level difference between the electrode and the active layer. Therefore, it is common to ensure smooth charge transfer by placing the anode electrode adjacent to the hole transport layer.

[0003] As such a hole transport layer, for example, Non-Patent Document 1 describes the use of PEDOT:PSS in the hole transport layer of an organic solar cell. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Nature Materials, volume 4, pages 864-868 (2005) Summary of the Invention [Problem to be solved by the invention]

[0005] PEDOT:PSS has a work function of approximately 5.0 eV, which is close to the energy level of the active layer. However, in order to achieve high conductivity with PEDOT:PSS, it is necessary to treat it with ethylene glycol or other materials. Furthermore, because PEDOT:PSS is an aqueous dispersion, it is difficult to apply it to, for example, the inkjet coating process that is currently the mainstream in the manufacturing process of organic solar cells.

[0006] Known self-doped conductive polymers (e.g., sulfonated polyaniline, PEDOT-S, etc.) have substituents (sulfo groups, sulfonate groups, etc.) that combine water solubility and doping properties in the polymer backbone, either directly or via a spacer. Such materials have high conductivity and, because they are water soluble, are not restricted by the manufacturing equipment. However, the self-doped conductive polymers themselves have a smaller work function than PEDOT:PSS, making them unsuitable as a hole transport layer adjacent to an ITO electrode.

[0007] That is, an object of one aspect of the present invention is to provide a self-doping conductive polymer solution having a work function suitable for a hole transport layer. [Means for solving the problem]

[0008] One aspect of the present invention relates to a conductive polymer solution, a conductive polymer membrane, and a method for producing the conductive polymer membrane, as described below.

[0009] [1] A conductive polymer solution containing 0.01 to 10% by weight of a polythiophene (A) containing at least one structural unit selected from the group consisting of a structural unit represented by the following general formula (1) and a structural unit represented by the following general formula (2), and a metal oxoacid salt (B).

[0010] [ka]

[0011] In general formula (1), M represents a hydrogen ion, an alkali metal ion, an ammonium ion, an organic ammonium ion, or a quaternary ammonium cation. In general formulas (1) and (2), R 2 represents a hydrogen atom, a methyl group, an ethyl group, a linear or branched alkyl group having 3 to 6 carbon atoms, or a fluorine atom, m represents an integer of 1 to 10, and n represents 0 or 1. [2] The conductive polymer solution according to [1], wherein the content of the metal oxoacid salt (B) is 0.001 to 20% by weight.

[0012] [3] The conductive polymer solution according to [1] or [2], wherein the metal oxoacid salt (B) is at least one selected from the group consisting of molybdates, vanadates, and tungstates.

[0013] [4] The conductive polymer solution according to any one of [1] to [3], which contains at least one solvent (C) selected from the group consisting of water, alcohols, and aprotic polar organic solvents.

[0014] [5] The conductive polymer solution according to [4], which has a pH of 2 to 12.

[0015] [6] A method for producing a conductive polymer film, comprising applying the conductive polymer solution according to any one of [1] to [5] to a substrate and then drying it.

[0016] [7] A conductive polymer film comprising a polythiophene (A) containing at least one structural unit selected from the group consisting of a structural unit represented by the following general formula (1) and a structural unit represented by the following general formula (2), and a metal oxide (B'), wherein the content of the metal oxide (B') is 0.1 to 10 parts by weight per part by weight of the polythiophene (A), and the conductive polymer film has a conductivity of 1 to 1,000 S / cm.

[0017] [ka]

[0018] In the general formula (1), M represents a hydrogen ion, an alkali metal ion, an ammonium ion, an organic ammonium ion, or a quaternary ammonium cation. In the general formulas (1) and (2), R 2 represents a hydrogen atom, a methyl group, an ethyl group, a linear or branched alkyl group having 3 to 6 carbon atoms, or a fluorine atom, m represents an integer of 1 to 10, and n represents 0 or 1. [Effects of the Invention]

[0019] According to one aspect of the present invention, a self-doping conductive polymer solution having a work function suitable for a hole transport layer can be provided. DETAILED DESCRIPTION OF THE INVENTION

[0020] An embodiment of the present invention will be described in detail below. In this specification, unless otherwise specified, "A to B" representing a range of numerical values ​​means "A or more and B or less."

[0021] The present embodiment is a conductive polymer solution containing 0.01 to 10% by weight of a polythiophene (A) containing at least one structural unit selected from the group consisting of a structural unit represented by the following general formula (1) and a structural unit represented by the following general formula (2), and a metal oxoacid salt (B).

[0022] [ka]

[0023] In general formula (1), M represents a hydrogen ion, an alkali metal ion, an ammonium ion, an organic ammonium ion, or a quaternary ammonium cation. In general formulas (1) and (2), R 2 represents a hydrogen atom, a methyl group, an ethyl group, a linear or branched alkyl group having 3 to 6 carbon atoms, or a fluorine atom, m represents an integer of 1 to 10, and n represents 0 or 1. In the general formula (1), M represents a hydrogen ion, an alkali metal ion, an ammonium ion, an organic ammonium ion, or a quaternary ammonium cation.

[0024] In addition, in the general formulas (1) and (2), R 2 represents a hydrogen atom, a methyl group, an ethyl group, a linear or branched alkyl group having 3 to 6 carbon atoms, or a fluorine atom.

[0025] The linear or branched alkyl group having 3 to 6 carbon atoms is not particularly limited, but examples thereof include an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, a cyclopentyl group, an n-hexyl group, a 2-ethylbutyl group, and a cyclohexyl group.

[0026] The aforementioned R 2 In terms of film-forming properties, it is preferable that the group be a hydrogen atom, a methyl group, an ethyl group, or a fluorine atom.

[0027] In the general formulas (1) and (2), m represents an integer of 1 to 10, and from the viewpoint of film-forming properties, it is preferably an integer of 1 to 6, more preferably an integer of 1 to 4, and even more preferably 2 or 3.

[0028] In the general formulas (1) and (2), n represents 0 or 1, and n is preferably 1 in terms of excellent conductivity.

[0029] The structural unit represented by the general formula (2) represents the doped state of the structural unit represented by the general formula (1).

[0030] Dopants that cause an insulator-metal transition through doping can be divided into acceptors and donors. The former enters the vicinity of the polymer chain of a conductive polymer through doping and removes π electrons from the conjugated system of the main chain. As a result, positive charges (holes) are injected into the main chain, and so they are also called p-type dopants. Conversely, the latter donates electrons to the conjugated system of the main chain, and these electrons move through the conjugated system of the main chain, so they are also called n-type dopants.

[0031] The polythiophene (A) of this embodiment can be produced by polymerizing a thiophene monomer represented by the following general formula (3) in water or an alcohol solvent in the presence of an oxidizing agent, followed by acid treatment as needed. If necessary, the process can be combined with other procedures such as solvent washing, reprecipitation, centrifugal sedimentation, ultrafiltration, dialysis, and ion exchange resin treatment.

[0032] [ka]

[0033] [In general formula (3), R 2 , m, and n are R in the general formulas (1) and (2). 2 , m, and n have the same definition. M represents a hydrogen ion or a metal ion. The metal ion represented by M in the general formula (3) is not particularly limited, but examples thereof include transition metal ions (such as iron ions, chromium ions, manganese ions, cobalt ions, nickel ions, and copper ions), alkali metal ions (such as lithium ions, potassium ions, sodium ions, rubidium ions, and cesium ions), and alkaline earth metal ions (such as magnesium ions, calcium ions, and strontium ions).

[0034] When the polymer obtained after polymerization of the thiophene monomer represented by the general formula (3) is a metal salt (included in the polythiophene (A) of the present embodiment), the obtained metal salt polymer may be treated with an acid to convert M to a hydrogen ion. The polythiophene (A) of the present embodiment also includes the polymer in which M is a hydrogen ion.

[0035] The thiophene monomer represented by the general formula (3) is not particularly limited, but specific examples thereof include 6-(2,3-dihydro-thieno[3,4-b][1,4]dioxin-2-yl)hexane-1-sulfonic acid, sodium 6-(2,3-dihydro-thieno[3,4-b][1,4]dioxin-2-yl)hexane-1-sulfonate, lithium 6-(2,3-dihydro-thieno[3,4-b][1,4]dioxin-2-yl)hexane-1-sulfonate, and 6-(2,3-dihydro-thieno[3,4-b][1,4]dioxin-2-yl)hexane-1-sulfonate. Potassium hexane-1-sulfonate, 8-(2,3-dihydro-thieno[3,4-b][1,4]dioxin-2-yl)octane-1-sulfonic acid, sodium 8-(2,3-dihydro-thieno[3,4-b][1,4]dioxin-2-yl)octane-1-sulfonate, and potassium 8-(2,3-dihydro-thieno[3,4-b][1,4]dioxin-2-yl)octane-1-sulfonate, sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-propanesulfonate, 3-[( Potassium 2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-propanesulfonate, sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonate, sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-ethyl-1-propanesulfonate, sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-propyl-1- Sodium propanesulfonate, sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-butyl-1-propanesulfonate, sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-pentyl-1-propanesulfonate, sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-hexyl-1-propanesulfonate, sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-hexyl-1-propanesulfonate, sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-isopropyl-1-propanesulfonate, sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-isobutyl-1-propanesulfonate, sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-isopentyl-1-propanesulfonate, sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]- Sodium 1-fluoro-1-propanesulfonate, potassium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonate, 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonic acid, ammonium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonate, Triethylammonium Hydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonate, Sodium 4-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-butanesulfonate, Potassium 4-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-butanesulfonate, 4-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]- Examples include sodium 1-methyl-1-butanesulfonate, potassium 4-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-butanesulfonate, sodium 4-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-fluoro-1-butanesulfonate, and potassium 4-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-fluoro-1-butanesulfonate.

[0036] The polythiophene (A) used in this embodiment may be synthesized based on publicly known information.

[0037] Furthermore, in the polythiophene (A) produced as described above, in which M is a hydrogen ion, the polythiophene (A) may be allowed to interact with a compound capable of forming an ion pair with the sulfonic acid group. Examples of compounds capable of forming an ion pair with the sulfonic acid group include, but are not limited to, alkali metal compounds, ammonia, organic amine compounds, and quaternary ammonium salts. These compounds react with the sulfonic acid group of the polythiophene (A) in which M is a hydrogen ion to form an alkali metal ion salt, ammonium ion salt, organic ammonium ion salt, or quaternary ammonium ion salt of the polythiophene (A). The salts thus formed are also included in the polythiophene (A) of this embodiment.

[0038] The alkali metal compound is not particularly limited, but examples thereof include alkali metal salt compounds (e.g., lithium chloride, potassium chloride, sodium chloride, rubidium chloride, cesium chloride, lithium bromide, potassium bromide, sodium bromide, rubidium bromide, cesium bromide, etc.) and alkali metal hydroxides (e.g., lithium hydroxide, potassium hydroxide, sodium hydroxide, rubidium hydroxide, cesium hydroxide, etc.).

[0039] By adding the alkali metal compound to the conductive polymer solution of this embodiment, polythiophene (A) can be prepared as an alkali metal ion salt. The alkali metal ion is not particularly limited, but examples thereof include lithium ion, potassium ion, sodium ion, rubidium ion, and cesium ion.

[0040] The organic amine compound is not particularly limited, and examples thereof include primary, secondary, or tertiary organic amine compounds having a total carbon number of 1 to 30. More specific examples thereof include methylamine, dimethylamine, trimethylamine, ethylamine, triethylamine, normal-propylamine, isopropylamine, normal-butylamine, hexylamine, aminoethanol (ethanolamine), dimethylaminoethanol, methylaminoethanol, diethanolamine, N-methyldiethanolamine, triethanolamine, 3-amino-1,2-propanediol, 3-methylamino-1,2-propanediol, 3-dimethylamino-1,2-propanediol, 1,4-butanediamine, tributylamine, triisobutylamine, tripentylamine, triisopentylamine, trihexylamine, triisohexylamine, trioctylamine, triisooctylamine, imidazole, N-methylimidazole, 1,2-dimethylimidazole, pyridine, picoline, and lutidine.

[0041] By adding the organic amine compound to the conductive polymer solution of this embodiment, the organic amine compound reacts with the polythiophene (A) to form an organic ammonium ion, thereby preparing the polythiophene (A) as an organic ammonium ion salt. The organic ammonium ion is not particularly limited, but examples thereof include primary, secondary, and tertiary organic ammonium ions having a total carbon number of 1 to 30. More specifically, examples thereof include methylammonium, dimethylammonium, trimethylammonium, ethylammonium, triethylammonium, n-propylammonium, isopropylammonium, n-butylammonium, hexylammonium, 2-hydroxyethylammonium, N,N-dimethyl-N-(2-hydroxyethyl)ammonium, N-methyl-N-(2-hydroxyethyl)ammonium, di(2-hydroxyethyl)ammonium, and N-methyl-N,N-di(2-hydroxyethyl)ammonium. ammonium, N,N,N-tri(2-hydroxyethyl)ammonium, 2,3-dihydroxypropylammonium, N-methyl-N-(2,3-dihydroxypropyl)ammonium, N,N-dimethyl-N-(2,3-dihydroxypropyl)ammonium, 1,4-butanediammonium, tributylammonium, triisobutylammonium, tripentylammonium, triisopentylammonium, trihexylammonium, triisohexylammonium, trioctylammonium, triisooctylammonium, imidazole cation, N-methylimidazole cation, 1,2-dimethylimidazole cation, pyridinium ion, picolinium ion, and lutidinium ion.

[0042] The quaternary ammonium salt is not particularly limited, but examples thereof include tetramethylammonium chloride, tetraethylammonium chloride, tetra-normal-propylammonium chloride, tetra-normal-butylammonium chloride, and tetra-normal-hexylammonium chloride.

[0043] By adding the quaternary ammonium salt to the conductive polymer solution of one embodiment of the present invention, the quaternary ammonium salt reacts with the polythiophene (A) to form a quaternary ammonium ion, thereby preparing the polythiophene (A) as a quaternary ammonium ion salt. The quaternary ammonium ion is not particularly limited, but examples thereof include tetramethylammonium ion, tetraethylammonium ion, tetra-n-propylammonium ion, tetra-n-butylammonium ion, and tetra-n-hexylammonium ion.

[0044] In producing the conductive polymer solution of this embodiment, the amount of the compound capable of forming an ion pair with the sulfonic acid group added is preferably 0.001 to 10 parts by weight of the compound capable of forming an ion pair with the sulfonic acid group of the polythiophene (A) relative to 1 part by weight of the polythiophene (A) (wherein M is a hydrogen ion), and from the viewpoint of obtaining a high work function, the amount is preferably 0.001 to 5 parts by weight, and more preferably 0.01 to 1 part by weight.

[0045] In the conductive polymer solution of this embodiment, the content of the polythiophene (A) containing at least one structural unit selected from the group consisting of the structural unit represented by the general formula (1) and the structural unit represented by the general formula (2) is characterized by being 0.01 to 10% by weight, but from the viewpoint of obtaining a high work function, it is preferably 0.05 to 8% by weight, and more preferably 0.1 to 7% by weight.

[0046] The metal oxoacid salt (B) contained in the conductive polymer solution of this embodiment is not particularly limited, but is preferably at least one selected from the group consisting of ferrates, cuprates, chromates, cobaltates, manganates, titanates, molybdates, vanadates, and tungstates, and more preferably at least one selected from the group consisting of molybdates, vanadates, and tungstates. Ferrates include, for example, potassium ferrate. Cuprates include, for example, potassium cuprate. Chromates include, for example, chromate or ammonium chromate. Cobaltates include, for example, lithium cobaltate. Manganates include, for example, ammonium manganate or ammonium permanganate. Titanates include, for example, lithium titanate. Molybdates include, for example, ammonium molybdate. Vanadates include, for example, ammonium vanadate. Tungstates include, for example, ammonium tungstate.

[0047] In the conductive polymer solution of this embodiment, the content of the metal oxoacid salt (B) is preferably 0.001 to 20% by weight, and from the viewpoint of obtaining a high work function, it is more preferably 0.01 to 20% by weight, and even more preferably 0.1 to 20% by weight.

[0048] In the conductive polymer solution of this embodiment, the content of the metal oxo acid salt (B) is preferably 0.1 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, and even more preferably 0.1 to 2 parts by weight, per part by weight of the polythiophene (A). Conductive polymer films formed using a conductive polymer solution containing polythiophene (A) and metal oxo acid salt (B) at such a content ratio tend to be good, uniform films. The conductive polymer film will be described later.

[0049] The solvent (C) of the conductive polymer solution of this embodiment is not particularly limited, but may be at least one selected from the group consisting of water, alcohol, and aprotic polar organic solvent, and is preferably water. In particular, a conductive polymer solution in which the solvent (C) is water is also referred to as a conductive polymer aqueous solution.

[0050] Examples of alcohols include methanol, ethanol, propanol, butanol, methoxyethanol, ethoxyethanol, butoxyethanol, and ethylene glycol.

[0051] Examples of the aprotic polar organic solvent include dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, and 1-methyl-2-pyrrolidone.

[0052] The solvent (C) may be a mixed solvent of water and an alcohol and / or an aprotic polar organic solvent. In this case, the content of the alcohol and / or the aprotic polar organic solvent in the conductive polymer solution is preferably 0.001 to 20% by weight, more preferably 0.01 to 15% by weight, and even more preferably 0.1 to 10% by weight, from the viewpoint of excellent operability.

[0053] The conductive polymer solution of this embodiment preferably has a pH in the range of 2.0 to 12.0, more preferably 2.0 to 10.5, and even more preferably 3.0 to 7.0, in order to provide excellent dispersibility in the solvent (C). The pH can be controlled, for example, by adding a compound capable of forming an ion pair with the sulfonic acid group (e.g., a basic substance such as sodium hydroxide) to the conductive polymer solution. The pH may be measured, for example, using the method specified in JIS Z8802:2011. The pH ranges indicated above are values ​​measured at a sample temperature of 25°C.

[0054] The conductive polymer solution of the present embodiment may contain a component (D) other than those described above. The component (D) is not particularly limited, but examples thereof include a binder and a surfactant.

[0055] The binder is not particularly limited, but examples thereof include polyvinyl alcohol, polyvinylpyrrolidone, cellulose, water-soluble polyester resin compounds, water-soluble polyurethane resin compounds, and mixtures of polyhydric alcohols and organic acids having two or more carboxyl groups.

[0056] Examples of the water-soluble polyester resin compound include polyethylene terephthalate, polytrimethylene terephthalate, etc. The water-soluble polyester resin compound may be a self-emulsifying type or a reinforced emulsifying type, but is preferably a self-emulsifying water-soluble polyester resin compound from the viewpoint of water resistance and solvent resistance.

[0057] Examples of the water-soluble polyester resin compound include those readily available commercially, such as those manufactured by Toyobo Co., Ltd. under the trade name Vylonal (registered trademark), those manufactured by Takamatsu Oil & Fats Co., Ltd. under the trade name PES RESIN, those manufactured by Goo Chemical Co., Ltd. under the trade name PLASCOAT (registered trademark), those manufactured by Toagosei Co., Ltd. under the trade name ARON MELT (registered trademark), those manufactured by Takamatsu Oil & Fats Co., Ltd. under the trade name PES RESIN A, and those manufactured by DIC Corporation under the trade name WATERZOL (registered trademark).

[0058] The water-soluble polyester resin compounds may be used alone or in combination of two or more.

[0059] The water-soluble polyurethane resin compound is mainly used in industrial applications as a urethane resin emulsion, and may be a self-emulsifying type or a reinforced emulsifying type. However, from the viewpoint of water resistance and solvent resistance, a self-emulsifying water-soluble polyurethane resin compound is preferable. Examples of the self-emulsifying type include an anionic type, a cationic type, and a nonionic type, and any of them may be used. Furthermore, the water-soluble polyurethane resin compound is not particularly limited, but examples thereof include a polyether type, a polyester type, and a polycarbonate type.

[0060] Examples of water-soluble polyurethane resin compounds that can be easily obtained commercially include those manufactured by Sanyo Chemical Industries, Ltd. under the trade names U-Coat (registered trademark), Permarin (registered trademark), and Euplen (registered trademark), those manufactured by Kusumoto Chemicals Co., Ltd. under the trade name NeoRez (registered trademark), those manufactured by ADEKA Corporation under the trade name Adeka Bontiter (registered trademark), those manufactured by Meisei Chemical Industry Co., Ltd. under the trade name Pascol (registered trademark), and those manufactured by DIC Corporation under the trade name Hydran (registered trademark).

[0061] The water-soluble polyurethane resin compounds can be used alone or in combination of two or more.

[0062] The polyhydric alcohol is not particularly limited, but examples thereof include erythritol and pentaerythritol.

[0063] The organic acid having two or more carboxyl groups is not particularly limited, but examples thereof include adipic acid and phthalic acid.

[0064] The surfactant is not particularly limited, but examples thereof include anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants, fluorine-based surfactants, and silicone-based surfactants, and more preferably at least one selected from the group consisting of nonionic surfactants and amphoteric surfactants.

[0065] The anionic surfactant is not particularly limited, but examples thereof include sodium lauryl alcohol sulfate and sodium dodecylbenzenesulfonate.

[0066] The cationic surfactant is not particularly limited, but a commercially available product can be used, or a commonly known product can be separately produced and used.

[0067] The nonionic surfactant is not particularly limited, but examples thereof include polyethylene glycol surfactants, acetylene glycol surfactants, polyhydric alcohol surfactants, and polymeric nonionic surfactants.

[0068] The polyethylene glycol surfactant is not particularly limited, but examples thereof include higher alcohol ethylene oxide adducts, alkylphenol ethylene oxide adducts, fatty acid ethylene oxide adducts, polyhydric alcohol fatty acid ester ethylene oxide adducts, higher alkylamine ethylene oxide adducts, ethylene oxide adducts of fats and oils, and polypropylene glycol ethylene oxide adducts.

[0069] The acetylene glycol surfactant is not particularly limited, but examples thereof include 2,4,7,9-tetramethyl-5-decyne-4,7-diol, Surfynol (registered trademark) (manufactured by Air Products Co., Ltd.), and Olfine (registered trademark) (manufactured by Nissin Chemical Industry Co., Ltd.).

[0070] The polyhydric alcohol surfactant is not particularly limited, but examples thereof include fatty acid esters of glycerol, fatty acid esters of pentaerythritol, fatty acid esters of sorbitol and sorbitan, fatty acid esters of sucrose, alkyl ethers of higher alcohols, and fatty acid amides of alkanolamines.

[0071] The amphoteric surfactant is not particularly limited, but examples thereof include betaine-type amphoteric surfactants, such as alkyl dimethyl betaine, lauryl dimethyl betaine, stearyl dimethyl betaine, and lauryl dihydroxyethyl betaine.

[0072] The fluorine-based surfactant is not particularly limited as long as it has a perfluoroalkyl group, and examples thereof include PLASCOAT (registered trademark) RY-2, perfluoroalkane, perfluoroalkylcarboxylic acid, perfluoroalkylsulfonic acid, and perfluoroalkylethylene oxide adducts.

[0073] The silicone surfactant is not particularly limited, but examples thereof include polyether-modified polydimethylsiloxane, polyetherester-modified polydimethylsiloxane, hydroxyl group-containing polyether-modified polydimethylsiloxane, acrylic group-containing polyether-modified polydimethylsiloxane, acrylic group-containing polyester-modified polydimethylsiloxane, perfluoropolyether-modified polydimethylsiloxane, perfluoropolyester-modified polydimethylsiloxane, and silicone-modified acrylic compounds.

[0074] The fluorine-based surfactant or silicone-based surfactant is effective as a leveling agent to improve the flatness of the coating film of the conductive polymer solution.

[0075] In the conductive polymer solution of the present embodiment, the content of the aforementioned component (D) is preferably 0.001 to 20% by weight, and from the viewpoint of excellent operability, it is more preferably 0.01 to 15% by weight, and even more preferably 0.1 to 10% by weight.

[0076] The method for preparing the conductive polymer solution of this embodiment is not particularly limited, and examples include a method in which a solution or solid of the polythiophene (A) of this embodiment, a metal oxoacid salt (B), and, if necessary, a solvent (C) are mixed together and homogenized by stirring, etc. In this case, other additives (e.g., component (D)) may be added as necessary before mixing and preparation, or a conductive polymer solution containing the polythiophene (A) and the metal oxoacid salt (B) may be first prepared, and then the other additives may be added and mixed to prepare the solution.

[0077] The temperature at which the mixture is mixed is not particularly limited, but may be, for example, room temperature or heated, preferably 0°C or higher and 100°C or lower.

[0078] The atmosphere in which the mixture is mixed is not particularly limited, but may be air or an inert gas.

[0079] When mixing the conductive polymer solution of this embodiment, in addition to a general mixing and dissolving operation using a stirrer tip or a stirring blade, ultrasonic irradiation or homogenization treatment (for example, using a mechanical homogenizer, ultrasonic homogenizer, high-pressure homogenizer, etc.) may be performed. When homogenization treatment is performed, it is preferable to perform it at a low temperature to prevent thermal degradation of the polymer.

[0080] The concentration of the conductive polymer solution of this embodiment may be adjusted by the blending ratio, or may be adjusted by concentrating the solution after blending. The concentrating method may be a method of distilling off the solvent (C) under reduced pressure, or a method using an ultrafiltration membrane.

[0081] In the conductive polymer solution of this embodiment, the particle size of the solids is not particularly limited, but the smaller the particle size, the better the water solubility, which is also desirable from the viewpoints of conductivity and uniform film formation during film formation. For example, when the solids concentration of a conductive polymer solution prepared at room temperature or under heating is 10 wt % or less, the particle size (D50) of the solids is preferably 0.02 μm or less.

[0082] The viscosity (20° C.) of the conductive polymer solution of this embodiment is preferably 200 mPa·s or less, more preferably 100 mPa·s or less, and even more preferably 50 mPa·s or less.

[0083] The conductive polymer film of this embodiment can be formed using the conductive polymer solution of this embodiment. A method for forming the conductive polymer film of this embodiment (a method for producing a conductive polymer film) includes a method comprising the steps of applying the conductive polymer solution of this embodiment to a substrate and then drying the solution. The conductive polymer film of this embodiment obtained by this production method is a film comprising a polythiophene (A) containing at least one structural unit selected from the group consisting of a structural unit represented by the general formula (1) and a structural unit represented by the general formula (2), and a metal oxide (B').

[0084] The metal oxide (B') is derived from the metal oxoacid salt (B) contained in the conductive polymer solution of this embodiment, because the metal oxoacid salt (B) is oxidized to the metal oxide (B') in the drying step. The metal oxide (B') contained in the conductive polymer film of this embodiment is not particularly limited, and examples thereof include iron oxide (e.g., iron(I) oxide, iron(II) oxide), copper oxide (e.g., copper(I) oxide, copper(II) oxide), chromium oxide (e.g., chromium(II), chromium(III), chromium(IV) oxide), cobalt oxide (e.g., cobalt(II), cobalt(III) oxide), manganese oxide (e.g., manganese(II), manganese(III), manganese(IV) oxide), titanium oxide (e.g., titanium(IV) oxide), molybdenum oxide (e.g., molybdenum(VI) oxide), vanadium oxide (e.g., vanadium(II) oxide), and tungsten oxide (e.g., tungsten(VI) oxide). Among these, molybdenum oxide (e.g., molybdenum(VI) oxide), vanadium oxide (e.g., vanadium(II) oxide), or tungsten oxide (e.g., tungsten(VI) oxide) is preferred in that it provides a work function suitable for an ITO electrode. Metal oxide (B') may contain two or more of these.

[0085] In the conductive polymer film of this embodiment, the content of the metal oxide (B') is 0.1 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, and even more preferably 0.1 to 2 parts by weight, per part by weight of the polythiophene (A). With such a content ratio, the conductive polymer film containing the polythiophene (A) and the metal oxide (B') tends to be a good, uniform film.

[0086] The drying atmosphere may be air, an inert gas, a vacuum, or a reduced pressure, but from the viewpoint of preventing deterioration of the conductive polymer film, an inert gas such as nitrogen or argon is preferred.

[0087] The substrate is not particularly limited, but examples thereof include glass, plastic, polyester, polyacrylate, polycarbonate, metal oxide, ceramic, and resist substrate.

[0088] The application method is not particularly limited, but examples thereof include casting, dipping, bar coating, roll coating, gravure coating, flexographic printing, spray coating, spin coating, and inkjet printing.

[0089] The drying temperature for the coating film is not particularly limited as long as a uniform conductive polymer film can be obtained, but is preferably in the range of room temperature to 300° C., more preferably in the range of room temperature to 250° C., and even more preferably in the range of room temperature to 200° C. Room temperature may be, for example, 25° C.

[0090] The thickness of the conductive polymer film is not particularly limited, but is preferably 10 -2 ~10 2 The surface resistivity of the conductive polymer film is not particularly limited, but is preferably in the range of 1 to 10 9 A range of Ω / □ is preferred.

[0091] The conductivity of the conductive polymer film obtained in this embodiment may be 0.01 to 1000 S / cm, preferably 0.1 to 1000 S / cm, and more preferably 1 to 1000 S / cm, in the film state (electrical conductivity).

[0092] The conductive polymer film of this embodiment can be used, for example, as an antistatic agent, a solid electrolyte for an electrolytic capacitor, a conductive paint, an electrochromic element, an electrode material, a thermoelectric conversion material, a transparent conductive film, a chemical sensor, and an actuator. In particular, it is extremely useful as a hole transport layer for an ITO electrode used in an organic solar cell, an organic EL element, and the like. The conductive polymer film of this embodiment can be used as a hole transport layer having a work function suitable for being adjacent to an ITO electrode.

[0093] Furthermore, the conductive polymer film of this embodiment can provide a hole transport layer suitable for organic solar cells and the like. Therefore, when used in organic solar cells, it can contribute to improving the efficiency of clean energy production. This can contribute to achieving goals such as Goal 7 "Affordable and Clean Energy" of the Sustainable Development Goals (SDGs).

[0094] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Example]

[0095] The conductivity and work function of the conductive polymer film described below are as follows: Measurement was carried out according to the following method.

[0096] [Method for producing conductive polymer films] Specifically, 0.1 mL of the conductive polymer solution of the Examples described below was applied to a 25 mm square alkali-free glass plate by spin coating at 1000 rpm for 10 seconds, and then heated on a hot plate in the atmosphere at 140°C for 15 minutes to obtain a conductive polymer film.

[0097] [Thickness measurement of conductive polymer film] Device: BRUKER DEKTAK XT The conductive polymer film prepared by the above-mentioned method was cut at intervals of 6.25 mm in the x direction and 6.25 mm in the y direction to expose the glass portion, and the film thickness at nine measurement points was measured in an atmosphere of 25°C and 50% RH.

[0098] [Measurement of surface resistivity of conductive polymer film] Equipment: Mitsubishi Chemical Loresta GP MCP-T600 Using a surface resistance measuring instrument, Loresta GP MCP-T600, and a measurement probe as an ASP, the surface resistivity was measured at nine measurement points at intervals of 6.25 mm in the x direction and 6.25 mm in the y direction in an atmosphere of 25°C and 50% RH.

[0099] [Conductivity measurement of conductive polymer films] The conductivity was calculated from the film thickness and surface resistivity of the conductive polymer film measured by the above-mentioned measuring method according to the following formula. Conductivity [S / cm]=10 4 / (Surface resistivity [Ω / □]×film thickness [μm]) [Method for measuring work function] Using the film prepared by the above-described method for preparing a conductive polymer film, the work function value of the conductive polymer film was calculated from the spectrum obtained by ultraviolet photoelectron spectroscopy according to the following formula. Work function [eV] = Energy of irradiated ultraviolet light [21.22 eV] - Measured energy range [eV] Example 1 (Preparation and Evaluation of Conductive Polymer Solution) To 98.5 g of pure water, 1.0 g of 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonic acid polymer (a conductive polymer consisting of structural units represented by the following formulas (6) and (7), with a number-average molecular weight of approximately 7,000; hereinafter referred to as "A1 polymer"), prepared according to a conventionally known manufacturing method, and 0.5 g of ammonium molybdate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added, followed by chip stirring to prepare a conductive polymer solution A1 (the conductive polymer solution of this embodiment, hereinafter abbreviated as A1). The pH (25°C) of A1 was 4.5. The conductivity and work function of a film prepared using the conductive polymer solution A1 were measured according to the above-described methods. The conductivity of the film was 25 S / cm. The work function of the film was 4.91 eV. The ammonium molybdate was oxidized to molybdenum oxide by heating and baking during film formation.

[0100] [ka]

[0101] Example 2 (Preparation and Evaluation of Conductive Polymer Solution) 1.0 g of the A1 polymer and 1.0 g of ammonium molybdate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added to 98.0 g of pure water, followed by chip stirring to prepare conductive polymer solution A2 (the conductive polymer solution of this embodiment, hereinafter abbreviated as A2). The pH (25°C) of A2 was 4.8. The conductivity and work function of a film prepared using the conductive polymer solution A2 were measured according to the above-mentioned methods. The conductivity of the film was 8.7 S / cm. The work function of the film was 4.94 eV. Note that the ammonium molybdate was oxidized to molybdenum oxide by heating and baking during film formation.

[0102] Example 3 (Preparation and Evaluation of Conductive Polymer Solution) 1.0 g of the A1 polymer and 0.5 g of ammonium vanadate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added to 98.5 g of pure water, followed by chip stirring to prepare conductive polymer solution A3 (the conductive polymer solution of this embodiment, hereinafter abbreviated as A3). The pH (25°C) of A3 was 5.1. The conductivity and work function of a film prepared using the conductive polymer solution A3 were measured according to the above-mentioned methods. The conductivity of the film was 89 S / cm. The work function of the film was 4.95 eV. Note that the ammonium vanadate was oxidized to vanadium oxide by heating and baking during film formation.

[0103] Example 4 (Preparation and Evaluation of Conductive Polymer Solution) 1.0 g of the A1 polymer and 0.5 g of ammonium tungstate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added to 98.5 g of pure water, followed by chip stirring to prepare conductive polymer solution A4 (the conductive polymer solution of this embodiment, hereinafter abbreviated as A4). The pH (25°C) of A4 was 4.8. The conductivity and work function of a film prepared using the conductive polymer solution A4 were measured according to the above-mentioned methods. The conductivity of the film was 155 S / cm. The work function of the film was 4.90 eV. Note that the ammonium tungstate was oxidized to tungsten oxide by heating and baking during film formation.

[0104] Reference example 1 1.0 g of the A1 polymer and 0.2 g of 28% aqueous ammonia solution were added to 98.8 g of pure water, followed by chip stirring to prepare conductive polymer solution A5 (hereinafter abbreviated as A5). The pH (25°C) of A5 was 3.2. The conductivity and work function of a film prepared using the conductive polymer solution A5 were measured according to the above-mentioned methods. The conductivity of the film was 220 S / cm. The work function of the film was 4.48 eV.

[0105] The results of each example and reference example are summarized in Table 1 below.

[0106] [Table 1]

[0107] As shown in Table 1, the films according to Examples 1 to 4, which used the conductive polymer solution of the present embodiment containing a metal oxoacid salt, exhibited higher work functions than the film according to Reference Example 1, which used a conductive polymer solution not containing a metal oxoacid salt. [Industrial Applicability]

[0108] The present invention can be used in, for example, organic solar cells.

Claims

1. 0.01 to 10% by weight of a polythiophene (A) containing at least one structural unit selected from the group consisting of a structural unit represented by the following general formula (1) and a structural unit represented by the following general formula (2), and (B) a metal oxoacid salt which is at least one selected from the group consisting of molybdates, vanadates, and tungstates, The conductive polymer solution contains the metal oxoacid salt (B) in an amount of 0.1 to 2 parts by weight per 1 part by weight of the polythiophene (A). 【Chemistry 1】 [In general formula (1), M represents a hydrogen ion, an alkali metal ion, an ammonium ion, an organic ammonium ion, or a quaternary ammonium cation. In general formulas (1) and (2), R ２ represents a hydrogen atom, a methyl group, an ethyl group, a linear or branched alkyl group having 3 to 6 carbon atoms, or a fluorine atom, m represents an integer of 1 to 10, and n represents 0 or 1.

2. 2. The conductive polymer solution according to claim 1, wherein the content of the metal oxoacid salt (B) is 0.001 to 20% by weight.

3. 3. The conductive polymer solution according to claim 1, further comprising at least one solvent (C) selected from the group consisting of water, alcohols, and aprotic polar organic solvents.

4. 4. The conductive polymer solution according to claim 3, wherein the pH is 2 to 12.

5. A method for producing a conductive polymer film, comprising applying the conductive polymer solution according to any one of claims 1 to 4 to a substrate and then drying the applied conductive polymer solution.

6. A polythiophene (A) containing at least one structural unit selected from the group consisting of a structural unit represented by the following general formula (1) and a structural unit represented by the following general formula (2), and a metal oxide (B') which is at least one selected from the group consisting of molybdenum oxide, vanadium oxide, and tungsten oxide, the content of the metal oxide (B') is 0.1 to 2 parts by weight per 1 part by weight of the polythiophene (A), A conductive polymer film having a conductivity of 1 to 1000 S / cm. 【Chemistry 2】 [In general formula (1), M represents a hydrogen ion, an alkali metal ion, an ammonium ion, an organic ammonium ion, or a quaternary ammonium cation. In general formulas (1) and (2), R ２ represents a hydrogen atom, a methyl group, an ethyl group, a linear or branched alkyl group having 3 to 6 carbon atoms, or a fluorine atom, m represents an integer of 1 to 10, and n represents 0 or 1.

Images