JP7400384B2 - Thermoelectric conversion materials and thermoelectric conversion elements - Google Patents

Description

Embodiments of the present invention relate to a thermoelectric conversion material and a thermoelectric conversion element using the material.

Thermoelectric conversion materials that can mutually convert thermal energy and electrical energy are used in thermoelectric conversion elements such as thermoelectric generation elements and Peltier elements. A thermoelectric conversion element is an element that converts heat into electric power, and is constructed from a combination of semiconductors and metals. Typical thermoelectric conversion elements are classified into p-type semiconductor alone, n-type semiconductor alone, or a combination of p-type semiconductor and n-type semiconductor. Thermoelectric conversion elements utilize the Seebeck effect, which generates an electromotive force when heat is applied to create a temperature difference between both ends of a semiconductor. In order to obtain a larger potential difference, thermoelectric conversion elements generally use a combination of p-type semiconductor and n-type semiconductor as materials.

Further, the thermoelectric conversion element is used as a thermoelectric module formed by combining a large number of elements into a plate shape or a cylindrical shape. Thermal energy can be directly converted into electricity, and can be used, for example, as a power source for wristwatches powered by body temperature, terrestrial power generation, and satellite power generation. The performance of the thermoelectric conversion element depends on the performance of the thermoelectric conversion material, the durability of the module, and the like.

As described in Non-Patent Document 1, a dimensionless thermoelectric figure of merit (ZT) is used as an index representing the performance of thermoelectric conversion materials. Moreover, a power factor PF (=S ² ·σ) may be used as an index representing the performance of a thermoelectric conversion material.
The dimensionless thermoelectric figure of merit "ZT" is expressed by the following formula (1).
ZT=(S ²・σ・T)/κ Formula (1)
Here, S is the Seebeck coefficient (V/K), σ is the electrical conductivity (S·m), T is the absolute temperature (K), and κ is the thermal conductivity (W/(m·K)). The thermal conductivity κ is expressed by the following formula (2).
κ=α・ρ・C Formula (2)
Here, α is the thermal diffusivity (m ² /s), ρ is the density (kg/m ³ ), and C is the specific heat capacity (J/(kg·K)).
That is, in order to improve thermoelectric conversion performance (hereinafter also referred to as thermoelectric characteristics), it is important to improve the Seebeck coefficient or electrical conductivity, while decreasing the thermal conductivity.

Typical thermoelectric conversion materials include, for example, bismuth/tellurium (Bi-Te) from room temperature to 500K, lead/tellurium (Pb-Te) from room temperature to 800K, and silicon/tellurium (Pb-Te) from room temperature to 1000K. Inorganic materials such as germanium (Si--Ge) are used.

However, thermoelectric conversion materials including these inorganic materials often contain rare elements and are expensive, or may contain harmful substances. Furthermore, since inorganic materials have poor workability, the manufacturing process becomes complicated. Therefore, thermoelectric conversion materials containing inorganic materials require high manufacturing energy and manufacturing costs, making it difficult to generalize them. Furthermore, since inorganic materials are rigid, it is difficult to form flexible thermoelectric conversion elements that can be installed in non-planar shapes.

In response, studies are underway on thermoelectric conversion elements using organic materials instead of conventional inorganic materials. Organic materials have excellent moldability and greater flexibility than inorganic materials, so they are highly versatile within a temperature range in which they do not decompose themselves. Furthermore, since printing technology and the like can be easily utilized, it is more advantageous than inorganic materials in terms of manufacturing energy and manufacturing costs.

For example, Patent Document 1 discloses a thermoelectric conversion material containing a polymer dispersant having an organic dye skeleton and carbon nanotubes (CNT), and a thermoelectric conversion element using the same. Further, Patent Document 2 discloses a thermoelectric conversion material containing a conductive compound in which a polycyclic aromatic ring having carrier transport properties and a substituent containing an alkyl group are bonded, and a thermoelectric conversion element using the same. . However, in the invention of Patent Document 1, sufficient performance as a thermoelectric conversion element was not obtained. Further, in the invention of Patent Document 2, the electrical conductivity is as low as 10 ^-8 to 10 ^-7 S/cm, and it has not been possible to obtain a practical value as a thermoelectric conversion element.

International Publication No. 2015/050113 International Publication No. 2015/129877

Takenobu Kajikawa, “Thermoelectric Conversion Technology Handbook (First Edition)”, NTS Publishing, 19 pages.

The problem to be solved by the present invention is to provide a thermoelectric conversion material that can achieve both excellent Seebeck coefficient and conductivity, and a thermoelectric conversion element using the same.

The present inventors have conducted extensive research to solve the above problems, and as a result, have arrived at the present invention. That is, the present invention contains a compound (A) represented by general formula (1) and at least one conductive material (B) selected from the group consisting of carbon materials, metal materials, and conductive polymers. Regarding thermoelectric conversion materials.

[In general formula (1), R ₁ to R ₈ are each independently a hydrogen atom, a hydroxyl group, a halogen atom, a cyano group, a nitro group, a carboxyl group, a sodium sulfonate group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, substituted or unsubstituted aryloxy group, substituted or unsubstituted alkylthio group, substituted or unsubstituted arylthio group, substituted or unsubstituted aryl group, substituted or unsubstituted heterocyclic group, or , represents a substituted or unsubstituted amino group. Adjacent groups of R ₁ to R ₈ may be bonded to each other to form a ring. However, at least one of R ₁ to R ₈ is a group other than a hydrogen atom. ]

The present invention also relates to the thermoelectric conversion material, wherein the content of the compound (A) is 400% by mass or less based on the total amount of the conductive material (B).

The present invention also relates to the thermoelectric conversion material, in which the conductive material (B) contains at least one member selected from the group consisting of carbon nanotubes, Ketjen black, graphene nanoplates, and graphene.

Further, the present invention relates to the thermoelectric conversion material in which the conductive material (B) includes carbon nanotubes.

Further, the present invention relates to a thermoelectric conversion element having a thermoelectric conversion film containing the above-mentioned thermoelectric conversion material and an electrode, the thermoelectric conversion film and the above-mentioned electrode being electrically connected.

According to the present invention, it is possible to provide a thermoelectric conversion material that achieves both Seebeck coefficient and electrical conductivity. Furthermore, using the material, it is possible to provide a thermoelectric conversion element that exhibits excellent thermoelectric performance.

1 is a schematic diagram showing the structure of an example of a thermoelectric conversion element according to an embodiment of the present invention. FIG. 2 is a schematic diagram illustrating a method for measuring electromotive force of a thermoelectric conversion element according to an embodiment of the present invention.

<Thermoelectric conversion materials>
The thermoelectric conversion material of the present invention is characterized by containing a compound (A) and a conductive material (B), and is capable of achieving both a high Seebeck coefficient and conductivity, and exhibiting excellent thermoelectric performance. This is because holes or electrons (carriers) move efficiently from the compound (A) to the conductive material (B), and the holes or electrons (carriers) move within the conductive material, resulting in a high Seebeck coefficient. It is presumed that electrical conductivity can be obtained.
Embodiments of the present invention will be described in detail below.

<Compound (A)>

<Compound (A)>
The mechanism of thermoelectric conversion is thought to be as follows. Holes or electrons (carriers) are generated in the thermally excited compound (A), and the holes or electrons (carriers) move to the conductive material (B), increasing the potential difference within the conductive material (B). occurs and current flows. In other words, the more efficient the carrier movement between the compound (A) and the conductive material (B), the greater the potential difference within the conductive material (B), and the higher the Seebeck coefficient. Although the specific method for making carrier transfer efficient is not clearly understood, it is important to consider the closeness of the distance between the compound (A) and the conductive material (B) due to the affinity between the compound (A) and the conductive material (B). ), the length of the excited state (excitation lifetime) of compound (A), etc. are considered to have an influence.

Depending on factors such as the above conditions, a compound (A) that allows efficient carrier transfer between the compound (A) and the conductive material (B) is represented by the general formula (1). First, substituents R ₁ to R ₈ of general formula (1) will be explained.

Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

Examples of substituted or unsubstituted alkyl groups include carbon atoms such as methyl, ethyl, propyl, butyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, and stearyl groups. an unsubstituted alkyl group of numbers 1 to 30,
2-phenylisopropyl group, trichloromethyl group, trifluoromethyl group, benzyl group, α-phenoxybenzyl group, α,α-dimethylbenzyl group, α,α-methylphenylbenzyl group, α,α-bis(trifluoromethyl ) Substituted alkyl groups having 1 to 30 carbon atoms such as a benzyl group, a triphenylmethyl group, and an α-benzyloxybenzyl group.

Examples of substituted or unsubstituted alkoxy groups include unsubstituted alkoxy groups having 1 to 20 carbon atoms such as methoxy group, ethoxy group, propoxy group, butoxy group, tert-butoxy group, octyloxy group, and tert-octyloxy group. ,
Examples include substituted alkoxy groups having 1 to 20 carbon atoms such as 3,3,3-trifluoroethoxy group and benzyloxy group.

Examples of substituted or unsubstituted aryloxy groups include unsubstituted aryloxy groups having 6 to 20 carbon atoms, such as phenoxy group, 4-tert-butylphenoxy group, 1-naphthyloxy group, 2-naphthyloxy group, and 9-anthryloxy group. Examples include substituted aryloxy groups having 6 to 20 carbon atoms, such as a substituted aryloxy group, 4-nitrophenoxy group, 3-fluorophenoxy group, pentafluorophenoxy group, and 3-trifluoromethylphenoxy group.

Examples of substituted or unsubstituted alkylthio groups include unsubstituted alkylthio groups having 1 to 20 carbon atoms such as methylthio group, ethylthio group, tert-butylthio group, hexylthio group, and octylthio group, benzylthio group, and trifluoromethylthio group. Examples include substituted alkylthio groups having 1 to 20 carbon atoms.

Examples of substituted or unsubstituted arylthio groups include unsubstituted arylthio groups having 6 to 20 carbon atoms such as phenylthio group, 2-methylphenylthio group, and 4-tert-butylphenylthio group, 3-fluorophenylthio group, Examples include substituted arylthio groups having 6 to 20 carbon atoms such as pentafluorophenylthio group and 3-trifluoromethylphenylthio group.

Examples of substituted or unsubstituted aryl groups include phenyl group, o-tolyl group, m-tolyl group, p-tolyl group, 2,4-xylyl group, p-cumenyl group, mesityl group, 1-naphthyl group, Unsubstituted aryl groups having 6 to 30 carbon atoms such as 2-naphthyl group, 1-anthryl group, 9-phenanthryl group, 1-acenaphthyl group, 2-azlenyl group, 1-pyrenyl group, 2-triphenyl group, p- Cyanophenyl group, p-diphenylaminophenyl group, p-styrylphenyl group, 4-[(2-tolyl)ethenyl]phenyl group, 4-[(2,2-ditolyl)ethenyl]phenyl group, etc. with 6 or more carbon atoms Thirty substituted aryl groups are mentioned.

Examples of the substituted or unsubstituted heterocyclic group include 2-furyl group, 3-furyl group, 2-thienyl group, 3-thienyl group, 1-pyrrolyl group, 2-pyrrolyl group, 3-pyrrolyl group, 2-furyl group, Pyridyl group, 3-pyridyl group, 4-pyridyl group, 2-pyrazyl group, 2-oxazolyl group, 3-isoxazolyl group, 2-thiazolyl group, 3-isothiazolyl group, 2-imidazolyl group, 3-pyrazolyl group, 2- Quinolyl group, 3-quinolyl group, 4-quinolyl group, 5-quinolyl group, 6-quinolyl group, 7-quinolyl group, 8-quinolyl group, 1-isoquinolyl group, 2-quinoxalinyl group, 2-benzofuryl group, 2- Unsubstituted aromatic heterocyclic groups having 3 to 20 carbon atoms such as benzothienyl group, N-indolyl group, N-carbazolyl group, N-acridinyl group, 2-(5-phenyl)furyl group, 2-(5-phenyl group) ) Substituted aromatic heterocyclic groups having 3 to 20 carbon atoms such as thienyl group and 2-(3-cyano)pyridyl group are mentioned.

Examples of substituted or unsubstituted amino groups include amino groups, N-methylamino groups, N-ethylamino groups, N,N-diethylamino groups, N,N-diisopropylamino groups, and N,N-dibutylamino groups. group, N-benzylamino group, N,N-dibenzylamino group, N-phenylamino group, N-phenyl-N-methylamino group, N,N-diphenylamino group, N,N-bis(m-tolyl ) amino group, N,N-bis(p-tolyl)amino group, N,N-bis(p-biphenylyl)amino group, bis[4-(4-methyl)biphenylyl]amino group, Np-biphenylyl- N-phenylamino group, N-1-naphthyl-N-phenylamino group, N-2-naphthyl-N-phenylamino group, N-phenanthryl-N-phenylamino group, N,N-bis(m-fluorophenyl ) amino group, N,N-bis(3-(9-phenyl)carbazole)amino group, N,N-bis(p-cyanophenyl)amino group, bis[4-(1,1'-dimethylbenzyl)phenyl ] Examples include substituted amino groups having 1 to 30 carbon atoms such as amino groups.

Adjacent groups of R ₁ to R ₈ in general formula (1) may be bonded to each other to form a ring.
Specific examples of the compound (A) represented by the general formula (1) are listed in Tables 1 to 9. In the table, "C ₃ H ₇ " represents a propyl group.

Only one type of compound (A) may be used, or two or more types may be used simultaneously.

The lifetime of the triplet excited state of compound (A) is preferably 1 μs or more, more preferably 100 μs or more, more preferably 1 ms or more, and even more preferably 100 ms or more.

The intersystem cross rate constant, which is an index of the rate of intersystem transfer from the singlet excited state to the triplet excited state, is preferably 10 ⁶ s ^-1 or more, more preferably 10 ⁷ s ^-1 or more, and more It is preferably 10 ⁸ s ^-1 or more, more preferably 10 ⁹ s ^-1 or more, and even more preferably 10 ¹⁰ s ^-1 or more and 10 ¹¹ s ^-1 or less.

The quantum yield, which is an index of the efficiency of intersystem transfer from the singlet excited state to the triplet excited state, is preferably 0.5 or more, more preferably 0.6 or more, and even more preferably 0.7 or more. It is particularly preferably 0.8 or more, and even more preferably 0.9 or more. Note that the upper limit of the quantum yield is 1.

Further, for the efficiency of carrier movement in the above mechanism, it is preferable that the distance between the compound (A) and the conductive material (B) is short. Therefore, it is preferable that the two have excellent affinity. For example, when the conductive material (B) has a π plane such as CNT, the compound (A) is preferably a compound having an aromatic ring, a heterocycle, or an acidic functional group.

Further, in order to promote surface adsorption and uniformity to the conductive material (B) and further increase the molecular proportion, the molecular weight of the compound (A) is preferably small. The molecular weight is preferably 2,000 or less, more preferably 1,000 or less.

<Conductive material (B)>
The conductive material (B) contributes to improving conductivity. Conductivity can be improved by increasing the content of the conductive material (B).
The conductive material (B) is not particularly limited as long as it has conductivity (carbon material, metal material, conductive polymer, etc.). For example, carbon materials include graphite, carbon nanotubes, carbon black, and graphene. (including graphene nanoplates), etc. Metal materials include gold, silver, copper, nickel, chromium, palladium, rhodium, ruthenium, indium, silicon, aluminum, tungsten, molybdenum, germanium, gallium, platinum, etc. Examples include metal powder, ZnSe, CdS, InP, GaN, SiC, SiGe, alloys thereof, and composite powders thereof. Further, fine particles having a nucleus and a substance different from the nucleus substance coated therein, specifically, for example, silver-coated copper powder having a copper nucleus and coating the surface with silver may be mentioned. In addition, powders of metal oxides such as silver oxide, indium oxide, tin oxide, zinc oxide, ruthenium oxide, ITO (tin-doped indium oxide), AZO (aluminum-doped zinc oxide), and GZO (gallium-doped zinc oxide), Examples include powders whose surfaces are coated with these metal oxides, and examples of conductive polymers include PEDOT/PSS (composite of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonic acid), polyaniline, and polyacetylene. , polypyrrole, polythiophene, polyparaphenylene, and the like.
One type of conductive material may be used, or two or more types may be used in combination.

The shape of the conductive material (B) is not particularly limited, and amorphous shapes, aggregate shapes, scale shapes, microcrystal shapes, spherical shapes, flake shapes, wire shapes, etc. can be used as appropriate.

From the viewpoint of achieving both Seebeck coefficient and electrical conductivity, at least one selected from the group consisting of carbon nanotubes, carbon black, and graphene (including graphene nanoplates) is preferable, carbon nanotubes are more preferable, and carbon nanotubes are particularly preferable. It is a layered carbon nanotube.

Examples of carbon materials include flaky graphite such as CMX, UP-5, UP-10, UP-20, UP-35N, CSSP, CSPE, CSP, CP, CB-150, and CB- manufactured by Nippon Graphite Industries. 100, ACP, ACP-1000, ACB-50, ACB-100, ACB-150, SP-10, SP-20, J-SP, SP-270, HOP, GR-60, LEP, F#1, F# 2, F#3, BF-3AK, FBF, BF-15AK, CBR, CPB-6S, CPB-3, 96L, 96L-3, K-3, SC-120, SC-60 manufactured by Chuetsu Graphite Industries Co., Ltd. , HLP, CP-150, SB-1, EC1500, EC1000, EC500, EC300, EC100, EC50 manufactured by Ito Graphite Industries, 10099M, PB-99 manufactured by Nishimura Graphite Co., Ltd., and the like. Examples of the spherical natural graphite include CGC-20, CGC-50, CGB-20, and CGB-50 manufactured by Nippon Graphite Industries. Examples of the earthy graphite include Blue P, AP, AOP, and P#1 manufactured by Nippon Graphite Industries Co., Ltd., and APR, K-5, AP-2000, AP-6, 300F, and 150F manufactured by Chuetsu Graphite Co., Ltd. Examples of artificial graphite include PAG-60, PAG-80, PAG-120, PAG-5, HAG-10W, HAG-150 manufactured by Nippon Graphite Industries, and G-4AK, G-6S, G- manufactured by Chuetsu Graphite Co., Ltd. 3G-150, G-30, G-80, G-50, SMF, EMF, SFF, SFF-80B, SS-100, BSP-15AK, BSP-100AK, WF-15C, SGP-100 manufactured by SEC Carbon , SGP-50, SGP-25, SGP-15, SGP-5, SGP-1, SGO-100, SGO-50, SGO-25, SGO-15, SGO-5, SGO-1, SGX-100, SGX -50, SGX-25, SGX-15, SGX-5, and SGX-1.

Commercially available conductive carbon fibers and carbon nanotubes include vapor grown carbon fibers such as VGCF manufactured by Showa Denko, EC1.5 and EC1.5-P manufactured by Meijo Nano Carbon, TUBALL manufactured by OCSiAl, and Zeon Nano. Examples include single-walled carbon nanotubes such as ZEONANO manufactured by Technology Corporation, FloTube9000, FloTube7000, and FloTube2000 manufactured by CNano, NC7000 manufactured by Nanocyl, and 100T and 200P manufactured by Knano.

Commercially available carbon blacks include, for example, Toka Black #4300, #4400, #4500, #5500 manufactured by Tokai Carbon, Printex L manufactured by Degussa, Raven 7000, 5750, 5250, 5000ULTRAIII, 5000ULTRA manufactured by Columbian, Conductex SC ULTRA, Conductex 975 ULTRA, PUERBLACK100, 115, 205, Mitsubishi Chemical #2350, #2400B, #2600B, #3050B, #3030B, #3230B, #3350B, #3400B, #5 400B, made by Cabot MONARCH1400, 1300, 900, Vulcan Ketjen black such as 600JD, electrochemical Examples include acetylene black such as Denka Black, Denka Black HS-100, and FX-35 manufactured by Kogyo Co., Ltd. These are not particularly limited.

Further, the compound (A) contributes to improving the Seebeck coefficient in the thermoelectric conversion material. The Seebeck coefficient can be improved by increasing the content of compound (A), but since increasing the content of compound (A) increases the insulation property and decreases the conductivity, the relationship between the Seebeck coefficient and the conductivity is From the viewpoint of coexistence, the upper limit of the content of the compound (A) is preferably 400% by mass or less, more preferably 200% by mass or less, and 120% by mass or less based on the total amount of the carbon material (B). It is more preferable, and particularly preferably 100% by mass or less. Moreover, the lower limit is preferably 5% by mass or more, more preferably 20% by mass or more.

In order to maintain thermoelectric properties, the thermoelectric conversion material of the present invention preferably does not contain a compound that generates radicals, and more preferably consists only of the compound (A) and the conductive material (B). From the viewpoint of processing and film formation, other components may be included as necessary.

(solvent)
The solvent is used as a medium when mixing the compound (A) and the conductive material (B), and makes it possible to improve coating properties by forming an ink. The solvent that can be used is not particularly limited as long as it can dissolve or disperse the conductive material (B) and the compound (A) well, and examples include organic solvents and water, and two or more types may be used in combination.
Examples of organic solvents include methanol, ethanol, propanol, butanol, ethylene glycol methyl ether, diethylene glycol methyl ether, terpineol, dihydroterpineol, 2,4-diethyl-1,5-pentanediol, 1,3-butylene glycol, iso Bornylcyclohexanol, ethylene glycol, 1,3-propanediol, 1,4-butanediol, diethylene glycol, triethylene glycol, glycerin, polyethylene glycol, polypropylene glycol, trifluoroethanol, m-cresol, and thiodiglycol, etc. Alcohols, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, ethers such as tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, hydrocarbons such as hexane, heptane, octane, benzene, toluene, xylene, cumene It can be appropriately selected from aromatics such as ethyl acetate, esters such as ethyl acetate, butyl acetate, N-methylpyrrolidone, etc., as required.
N-methylpyrrolidone is particularly preferred as the solvent for dispersing the compound (A) and the conductive material (B).

(Auxiliary agent)
Usable auxiliaries are not particularly limited, and include, for example, lactams, alcohols, amino alcohols, carboxylic acids, acid anhydrides, and ionic liquids. Specific examples are as follows.
Lactams: pyrrolidone, caprolactam, N-methylcaprolactam, N-octylpyrrolidone, etc.
Alcohols: sucrose, glucose, fructose, lactose, sorbitol, mannitol, xylitol, etc.
Amino alcohols: diethanolamine, triethanolamine, etc.
Carboxylic acids: 2-furancarboxylic acid, 3-furancarboxylic acid, dichloroacetic acid, trifluoroacetic acid, etc.
Acid anhydrides: acetic anhydride, propionic anhydride, acrylic anhydride, methacrylic anhydride, benzoic anhydride, succinic anhydride, maleic anhydride, itaconic anhydride, glutaric anhydride, phthalic anhydride, tetrahydrophthalic anhydride, hexahydro Phthalic anhydride (also known as cyclohexane-1,2-dicarboxylic anhydride), trimellitic anhydride, hexahydro trimellitic anhydride, pyromellitic anhydride, himic anhydride, biphenyltetracarboxylic anhydride, 1,2,3 , 4-butanetetracarboxylic anhydride, naphthalenetetracarboxylic anhydride, and 9,9-fluorenylidene bisphthalic anhydride. Copolymers made by copolymerizing maleic anhydride with other vinyl monomers, such as styrene-maleic anhydride copolymers, ethylene-maleic anhydride copolymers, isobutylene-maleic anhydride copolymers, and alkyl vinyl ether-maleic anhydride copolymers.

From the viewpoint of electrical conductivity and thermoelectric properties, it is preferable to use at least one of lactams and alcohols as the auxiliary agent. The content of the auxiliary agent is preferably in the range of 0.1 to 30% by mass, more preferably in the range of 1 to 10% by mass, and even more preferably in the range of 1 to 5% by mass, based on the total mass of the thermoelectric conversion material. . By setting the content of the auxiliary agent to 0.1% by mass or more, the effect of improving conductivity and thermoelectric properties can be easily obtained. Moreover, when the content of the auxiliary agent is 50% by mass or less, deterioration of the film physical properties can be suppressed.

(resin)
The thermoelectric conversion material of the present invention may contain a resin for the purpose of adjusting film formability and film strength, etc., to the extent that it does not affect conductivity and thermoelectric properties.
The resin may be any resin as long as it is compatible with or mixed and dispersed in each component of the thermoelectric conversion material. Either thermosetting resin or thermoplastic resin may be used. Specific examples of usable resins include polyester resin, polyimide resin, polyamide resin, fluororesin, vinyl resin, epoxy resin, xylene resin, aramid resin, polyurethane resin, polyurea resin, melamine resin, phenol resin, polyether resin, and acrylic. Examples include resins, acrylamide resins, and copolymer resins thereof. Although not particularly limited, in one embodiment, it is preferable to use at least one selected from the group consisting of polyurethane resins, polyether resins, acrylic resins, and acrylamide resins.

From the viewpoint of conductivity, the content of the resin is preferably in the range of 0 to 90% by mass, more preferably in the range of 0 to 50% by mass, based on the total mass of the compound (A) and the conductive material (B). Preferably, the range is from 0 to 20% by mass, more preferably.

(Inorganic thermoelectric conversion material)
The thermoelectric conversion material of the present invention may contain an inorganic thermoelectric conversion material as necessary in order to improve thermoelectric conversion performance. Examples of inorganic thermoelectric materials include Bi-(Te, Se) based, Si-Ge based, Mg-Si based, Pb-Te based, GeTe-AgSbTe based, (Co, Ir, Ru)-Sb based, (Ca, Examples include Sr, Bi)Co ₂ O ₅ systems, and the like. More specifically, _{Bi2Te3 , PbTe} , _AgSbTe2 , GeTe, _{Sb2Te3 , NaCo2O4} , _{CaCoO3 , SrTiO3} , ZnO, SiGe, _Mg2Si , _FeSi2 , _Ba8Si46 , At least one selected from the group consisting of MnSi _1.73 , ZnSb, Zn ₄ Sb ₃ , GeFe ₃ CoSb ₁₂ , and LaFe ₃ CoSb ₁₂ can be used. At this time, impurities may be added to the inorganic thermoelectric conversion material to control the polarity (p-type, n-type) and conductivity. When using an inorganic thermoelectric conversion material, the amount used is adjusted within a range that does not affect film formability or film strength.

The method for producing a thermoelectric conversion dispersion liquid is not particularly limited as long as a thermoelectric conversion dispersion liquid that satisfies the conditions of the present invention is obtained, and can be appropriately selected. For example, it can be obtained by mixing a thermoelectric conversion material, a dispersion medium, and other components as necessary, and then dispersing the mixture using a disperser or ultrasonic waves.

There are no particular restrictions on the dispersion machine; for example, kneaders, attritors, ball mills, sand mills using glass beads or zirconia beads, media dispersion machines such as Scandex, Eiger mills, paint conditioners, paint shakers, colloid mills, etc. can be used. can do.

<Thermoelectric conversion element>
The thermoelectric conversion element of the present invention includes a thermoelectric conversion film formed using the thermoelectric conversion material and an electrode, and the thermoelectric conversion film and the electrode are electrically connected to each other. Thermoelectric conversion films have excellent heat resistance and flexibility in addition to conductivity and thermoelectric properties. Therefore, a high quality thermoelectric conversion element can be easily manufactured.

The thermoelectric conversion film may be a film obtained by applying a thermoelectric conversion material onto a base material. Since the thermoelectric conversion material has excellent moldability, it is easy to obtain a good film by a coating method. A wet film forming method is mainly used to form a thermoelectric conversion film. Specifically, spin coat method, spray method, roller coat method, gravure coat method, die coat method, comma coat method, roll coat method, curtain coat method, bar coat method, inkjet method, dispenser method, silk screen printing, flexographic method. Examples include methods using various means such as printing. The method can be appropriately selected from the above methods depending on the thickness to be applied, the viscosity of the material, etc.

The thickness of the thermoelectric conversion film is not particularly limited, but as described later, it has a thickness of at least a certain level so that a temperature difference can be generated and transmitted in the thickness direction or surface direction of the thermoelectric conversion film. It is preferable that it be formed as follows. From the viewpoint of thermoelectric properties, the thickness of the thermoelectric conversion film is preferably in the range of 0.1 to 200 μm, preferably in the range of 1 to 100 μm, and more preferably in the range of 1 to 50 μm.

The base material is not particularly limited, but includes plastic films made of materials such as nonwoven fabric, paper, polyethylene, polyethylene terephthalate (PET), polyethylene naphthalate, polyether sulfone, polypropylene, polyimide, polycarbonate, and cellulose triacetate. Alternatively, glass or the like can be used.

Various treatments can be performed on the surface of the base material for the purpose of improving the adhesion between the base material and the thermoelectric conversion film. Specifically, prior to applying the thermoelectric conversion material, UV ozone treatment, corona treatment, plasma treatment, or adhesion promoting treatment may be performed.

The thermoelectric conversion element according to the embodiment of the present invention can be constructed by applying techniques well known in the art, except that it is constructed using the thermoelectric conversion material described above. A more specific configuration of the thermoelectric conversion element and its manufacturing method will be explained.

In the thermoelectric conversion element, a thermoelectric conversion film and an electrode are electrically connected. Here, "electrically connected" means that they are connected to each other or that they are in a state where electricity can be passed through other constituent members such as wires.

The material of the electrode can be selected from metals, alloys, and semiconductors. In one embodiment, metals and alloys are preferable because it is preferable that the conductivity is high and the contact resistance of the thermoelectric conversion film is low. As a specific example, the electrode preferably contains at least one member selected from the group consisting of gold, silver, copper, and aluminum. More preferably, the electrode contains silver.

The electrode can be formed by a method such as a vacuum evaporation method, thermocompression bonding of an electrode material foil or a film having an electrode material film, or application of a paste in which fine particles of the electrode material are dispersed. From the viewpoint of a simple process, a method using thermocompression bonding of an electrode material foil or a film having an electrode material film, or a method using a paste in which the electrode material is dispersed is preferable.

Typical examples of the structure of a thermoelectric conversion element include (1) a structure in which electrodes are formed at both ends of the thermoelectric conversion film according to the present invention; It is roughly divided into a structure in which a thermoelectric conversion film is sandwiched between two electrodes.
For example, a thermoelectric conversion element having the structure (1) above can be obtained by forming a thermoelectric conversion film on a base material and then applying silver paste to both ends of the film to form first and second electrodes. be able to. In the thermoelectric conversion element in which electrodes are formed at both ends of the thermoelectric conversion film in this way, it is easy to increase the distance between the two electrodes. Therefore, it is easy to generate a large temperature difference between the two electrodes and perform thermoelectric conversion efficiently.

The thermoelectric conversion element having the structure (2) above can be produced, for example, by applying silver paste onto a base material to form a first electrode, forming the thermoelectric conversion film of the present invention on top of that, and then forming a first electrode on top of the first electrode. It can be obtained by coating a silver paste to form the second electrode. In the thermoelectric conversion element in which the thermoelectric conversion film of the present invention is sandwiched between two electrodes as described above, it is difficult to increase the distance between the two electrodes. Therefore, it is difficult to generate a large temperature difference between the two electrodes, but it is possible to increase the temperature difference by increasing the thickness of the thermoelectric conversion film. Further, since the thermoelectric conversion element having such a structure can utilize the temperature difference in the direction perpendicular to the base material, it can be used in a form where it is attached to a heating element. Therefore, it is preferable in that a large area of the heat source can be easily utilized.

Thermoelectric conversion elements can generate a high voltage by connecting them in series, and can generate a large current by connecting them in parallel. Moreover, the thermoelectric conversion element may be one in which two or more thermoelectric conversion elements are connected. According to the present invention, since the thermoelectric conversion element has excellent flexibility, it is possible to follow and suitably install a heat source having a non-planar shape.

In one embodiment, it is also effective to combine the thermoelectric conversion element of the present invention with a thermoelectric conversion element made of another thermoelectric material. For example, as inorganic thermoelectric materials, Bi-(Te, Se) based, Si-Ge based, Mg-Si based, Pb-Te based, GeTe-AgSbTe based, (Co, Ir, Ru)-Sb based, (Ca, Sr, Bi)Co ₂ O ₅ type, etc. can be mentioned, and specifically, Bi ₂ Te ₃ , PbTe, AgSbTe ₂ , GeTe, Sb ₂ Te ₃ , NaCo ₂ O ₄ , CaCoO ₃ , SrTiO ₃ , ZnO , SiGe, Mg ₂ Si, FeSi ₂ , Ba ₈ Si ₄₆ , MnSi _1.73 , ZnSb, Zn ₄ Sb ₃ , GeFe ₃ CoSb ₁₂ , LaFe ₃ CoSb ₁₂ and the like. I can do it. At this time, impurities may be added to the inorganic thermoelectric material to control its polarity (p-type, n-type) and conductivity. In addition, at least one selected from the group consisting of polythiophene, polyaniline, polyacetylene, fullerene, and derivatives thereof can be used as the organic thermoelectric material. When combining other thermoelectric conversion elements made of these materials, it is preferable to manufacture the other thermoelectric conversion elements within a range that does not impair the flexibility of the element.

Hereinafter, the present invention will be explained in more detail with reference to experimental examples. In addition, in the examples, "part" means "part by mass" and "%" means "% by mass", respectively. Further, NMP represents N-methylpyrrolidone.

<Method for measuring mass average molecular weight (Mw)>
Mw was measured using GPC (gel permeation chromatography) "HPC-8020" manufactured by Tosoh Corporation. The measurement in the present invention uses two "LF-604" columns (manufactured by Showa Denko K.K.: GPC column for rapid analysis: 6 mm ID x 150 mm size) connected in series, and the developing solvent (eluent) is THF (tetrahydrofuran). ), a flow rate of 0.6 ml/min, and a column temperature of 40°C. The mass average molecular weight (Mw) was determined using polystyrene as a standard substance.

<Synthesis of polymers with organic dyes introduced into the side chains>
(Synthesis example 1: dye-introduced polymer 1)
With reference to paragraphs [0074] and [0075] of International Publication No. 2015/050113, it is an acrylic polymer with a mass average molecular weight (Mw) of about 21,000 and a perylene skeleton introduced into the side chain represented by the structure below. A dye-introduced polymer 1 was obtained.

<Synthesis of resin components>
(Synthesis example 2: resin 1)
A polyester polyol obtained from terephthalic acid, adipic acid, and 3-methyl-1,5-pentanediol (manufactured by Kuraray Co., Ltd.) was placed in a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen introduction tube. "Kuraray Polyol P-2011", 455.5 parts of Mn=2,011), 16.5 parts of dimethylolbutanoic acid, 105.2 parts of isophorone diisocyanate, and 140 parts of toluene were charged and reacted at 90°C for 3 hours under nitrogen atmosphere. , 360 parts of toluene was added to this to obtain a urethane prepolymer solution having isocyanate groups. Next, 19.9 parts of isophoronediamine, 0.63 parts of di-n-butylamine, 294.5 parts of 2-propanol, and 335.5 parts of toluene were mixed with the obtained urethane prepolymer solution having isocyanate groups. After adding 969.5 parts and reacting at 50°C for 3 hours and 70°C for 2 hours, vacuum drying was performed at 100°C to obtain Resin 1, which is a urethane urea resin with a mass average molecular weight (Mw) of 61,000. Obtained.

(Synthesis example 3: resin 2)
Pripol 1009 (manufactured by Croda Japan Co., Ltd., acid value 194 mg KOH/ g), 5.24 parts of 5-hydroxyisophthalic acid (manufactured by Sugai Chemical Co., Ltd., hereinafter also referred to as "5-HIPA") as a polybasic acid compound having a phenolic hydroxyl group, and a polyamine compound having 36 carbon atoms. 82.84 parts of Priamine 1074 (manufactured by Croda Japan Co., Ltd., acid value 210 KOHmg/g) and 4.74 parts of toluene were added, and while stirring, the temperature was raised to 220°C and dehydrated while distilling off water. continued to react. Sampling was performed every hour to confirm that the mass average molecular weight was 50,000, and after cooling, Resin 2, which is a phenolic hydroxyl group-containing polyamide resin having Mw of 50,432, was obtained.

<Synthesis of compound (A)>

(Synthesis example 4: A13)
5 parts of phenanthroline (manufactured by Tokyo Chemical Industry Co., Ltd.) and 100 parts of 67% nitric acid (manufactured by Tokyo Chemical Industry Co., Ltd.) were placed in a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen introduction tube, and a nitrogen atmosphere was placed. The mixture was reacted at 100° C. for 3 hours. After cooling, the mixture was poured into 3000 parts of water, and the precipitated solids were collected by filtration and purified by column chromatography to obtain 0.5 parts of A13.

(Synthesis example 5: A35)
In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen inlet tube, add 1 part of 4,7-dihydroxy-1,10-phenanthroline (manufactured by Tokyo Kasei Kogyo Co., Ltd.) and bromobenzene (Tokyo Kasei Kogyo Co., Ltd.). (manufactured by Tokyo Chemical Industry Co., Ltd.), 2 parts of potassium hydroxide (manufactured by Tokyo Kasei Kogyo Co., Ltd.), and 200 parts of ethanol, and reacted at 50° C. for 12 hours under a nitrogen atmosphere. After cooling, the mixture was dried using an evaporator and purified using column chromatography to obtain 0.59 parts of A35.

(Synthesis example 6: A34)
A34 was produced in the same manner as in Synthesis Example 5, except that 4,7-dihydroxy-1,10-phenanthroline and bromobenzene were changed to 9-dihydroxy-1,10-phenanthroline and 2-bromo-2-methylpropane. Obtained.

(Synthesis example 7: A38)
A38 was obtained in the same manner as Synthesis Example 5 except that bromobenzene was changed to 2-bromoethyl ethyl ether.

(Synthesis example 8: A41)
In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen introduction tube, 5 parts of 4,7-dibromo-1,10-phenanthroline (manufactured by Tokyo Kasei Kogyo Co., Ltd.) and mercaptoethane (manufactured by Tokyo Kasei Kogyo Co., Ltd.) were added. (manufactured by Tokyo Kasei Kogyo Co., Ltd.), 1 part of sodium hydroxide (manufactured by Tokyo Kasei Kogyo Co., Ltd.), and 100 parts of DMF were added, and the mixture was reacted at 80° C. for 3 hours under a nitrogen atmosphere. After cooling, a solid was obtained by washing with water and filtration. It was purified by column chromatography to obtain 3.7 parts of A41.

(Synthesis example 9: A42)
A42 was obtained in the same manner as Synthesis Example 8, except that 4,7-dibromo-1,10-phenanthroline and mercaptoethane were changed to 3,6-dibromo-1,10-phenanthroline and 4-mercaptopyridine. .

(Synthesis example 10: A114)
A114 was obtained in the same manner as Synthesis Example 8 except that 4,7-dibromo-1,10-phenanthroline and mercaptoethane were changed to 3-bromo-1,10-phenanthroline and mercaptobenzene.

(Synthesis Example 11: A115)
A115 was obtained in the same manner as Synthesis Example 8, except that 4,7-dibromo-1,10-phenanthroline and mercaptoethane were changed to 3-bromo-1,10-phenanthroline and 4-fluorobenzenethiol.

(Synthesis example 12: A53)
In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen inlet tube, 2 parts of 3,8-dibromo-1,10-phenanthroline (manufactured by Tokyo Kasei Kogyo Co., Ltd.) and phenylboronic acid (Tokyo Kasei Kogyo Co., Ltd.) were added. (manufactured by Tokyo Chemical Industry Co., Ltd.) 2 parts, tetrakis(triphenylphosphine) palladium (0) (manufactured by Tokyo Chemical Industry Co., Ltd.) 0.25 parts, potassium carbonate (manufactured by Tokyo Chemical Industry Co., Ltd.) 3 parts, water 30 parts, ethanol 5 parts, toluene 100 parts 1 part was charged and reacted at 100°C for 3 hours under nitrogen atmosphere. After cooling, the mixture was dried using an evaporator and purified using column chromatography to obtain 0.29 parts of A53.

(Synthesis example 13: A54)
A54 was obtained in the same manner as Synthesis Example 12, except that 3,8-dibromo-1,10-phenanthroline and phenylboronic acid were changed to 3-bromo-1,10-phenanthroline and 1-naphthaleneboronic acid. .

(Synthesis example 14: A56)
Same as Synthesis Example 12 except that 3,8-dibromo-1,10-phenanthroline and phenylboronic acid were changed to 3,8-dibromo-1,10-phenanthroline and 4-(trifluoromethyl)phenylboronic acid. A56 was obtained by the method.

(Synthesis example 15: A60)
A60 was produced in the same manner as Synthesis Example 12, except that 3,8-dibromo-1,10-phenanthroline and phenylboronic acid were changed to 4,7-dibromo-1,10-phenanthroline and 3-pyridylboronic acid. Obtained.

(Synthesis example 16: A62)
A62 was obtained in the same manner as Synthesis Example 12, except that 3,8-dibromo-1,10-phenanthroline and phenylboronic acid were changed to 3-bromo-1,10-phenanthroline and 3-pyridylboronic acid. .

(Synthesis example 17: A65)
A65 was obtained in the same manner as Synthesis Example 12, except that 3,8-dibromo-1,10-phenanthroline and phenylboronic acid were changed to 4,7-dibromo-1,10-phenanthroline and 2-furylboronic acid. Ta.

(Synthesis example 18: A68)
A68 was produced in the same manner as Synthesis Example 12, except that 3,8-dibromo-1,10-phenanthroline and phenylboronic acid were changed to 3,8-dibromo-1,10-phenanthroline and 2-thiopheneboronic acid. Obtained.

(Synthesis example 19: A71)
A71 was produced in the same manner as Synthesis Example 12, except that 3,8-dibromo-1,10-phenanthroline and phenylboronic acid were changed to 3,8-dibromo-1,10-phenanthroline and 2-thiopheneboronic acid. Obtained.

(Synthesis example 20: A74)
Same method as Synthesis Example 12 except that 3,8-dibromo-1,10-phenanthroline and phenylboronic acid were changed to 4,7-dibromo-1,10-phenanthroline and 9-ethylcarbazole-3-boronic acid. So I got A74.

(Synthesis Example 21: A110)
3,8-dibromo-1,10-phenanthroline to 3,5,6,8-tetrabromo-1,10-phenanthroline, phenylboronic acid to 4-biphenylboronic acid, 9-anthraceneboronic acid, 2-furylboronic acid and A110 was obtained in the same manner as in Synthesis Example 12, except that the mixture was changed to a mixture of benzo[b]thiophene-2-boronic acid.

(Synthesis example 22: A75)
A reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen introduction tube was charged with 0.5 parts of magnesium (manufactured by Tokyo Kasei Kogyo Co., Ltd.) and 20 parts of THF, and stirred at 25° C. under a nitrogen atmosphere. 0.1 part of iodine (manufactured by Tokyo Kasei Kogyo Co., Ltd.), 2.5 parts of 3-bromo-1,10-phenanthroline, and 100 ml of THF were placed in a dropping device, and the mixture was added dropwise and stirred for 6 hours. Then, 2.5 parts of 3-bromo-1,10-phenanthroline and 0.3 parts of [1,2-bis(diphenylphosphino)ethane]dichloronickel(II) (manufactured by Sigma-Aldrich) were added, and the mixture was heated at 60°C. The reaction was allowed to proceed for 12 hours. After cooling, the mixture was dried using an evaporator and purified using column chromatography to obtain 0.98 parts of A75.

(Synthesis example 23: A82)
In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen introduction tube, 3 parts of 3-bromo-1,10-phenanthroline (manufactured by Tokyo Kasei Kogyo Co., Ltd.) and dipropylamine (manufactured by Tokyo Kasei Kogyo Co., Ltd.) were added. ) 1.57 parts, palladium(II) acetate (manufactured by Tokyo Kasei Kogyo Co., Ltd.) 0.13 parts, tri-tert-butylphosphine (manufactured by Tokyo Kasei Kogyo Co., Ltd.) 0.18 parts, tert-butoxy sodium (manufactured by Tokyo Kasei Kogyo Co., Ltd.) ) and 50 parts of toluene were charged, and the mixture was reacted at 70°C for 5 hours under a nitrogen atmosphere. After cooling, it was washed with water and methanol, and a solid was obtained by filtration. It was purified by column chromatography to obtain 1.39 parts of A82.

(Synthesis example 24: A89)
A89 was obtained in the same manner as Synthesis Example 12, except that 3-bromo-1,10-phenanthroline and dipropylamine were changed to 7-dibromo-1,10-phenanthroline and p,p'-ditolylamine. .

(Synthesis example 25: A109)
3-Bromo-1,10-phenanthroline and dipropylamine to a mixture of 2,3,4,5,6,7,8,9-octabromo-1,10-phenanthroline and piperidine, pyrrole and dimethylamine. A109 was obtained in the same manner as in Synthesis Example 12 except for the following changes.

<Manufacture of thermoelectric conversion materials>
[Example 1]
(Dispersion liquid 1)
0.4 parts of 1,10-phenanthroline (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.4 parts of GNP (graphene nanoplatelets "xGNP-M-5" manufactured by XGS Sciences), and 79.2 parts of NMP were weighed and mixed. . Furthermore, 140 parts of zirconia beads (φ1.25 mm) were added, and after shaking with Scandex for 4 hours, the zirconia beads were removed by filtration to obtain a dispersion liquid 1 of thermoelectric conversion material.

[Examples 2 to 72, Comparative Example 1]
(Dispersions 2-72, 101)
Dispersions 2 to 72 and 101 of thermoelectric conversion materials were obtained in the same manner as in the manufacturing method of Dispersion 1, except that the types and amounts of the materials were changed as shown in Table 10.

The materials listed in Table 10 used in addition to those described in the above synthesis examples are shown below.
Compound (A)
A1: 2,9-dimethyl-5-picrylamino-1,10-phenanthroline (manufactured by Tokyo Chemical Industry Co., Ltd.)
A3: 4,7-dibromo-1,10-phenanthroline (manufactured by Tokyo Chemical Industry Co., Ltd.)
A4: 3-bromo-1,10-phenanthroline (manufactured by Tokyo Kasei Kogyo Co., Ltd.)
A5: 2-bromo-1,10-phenanthroline (manufactured by Tokyo Kasei Kogyo Co., Ltd.)
A6: 2-chloro-1,10-phenanthroline (manufactured by Tokyo Kasei Kogyo Co., Ltd.)
A7: 5-chloro-1,10-phenanthroline (manufactured by Tokyo Kasei Kogyo Co., Ltd.)
A8: 4,7-dichloro-1,10-phenanthroline (manufactured by Tokyo Chemical Industry Co., Ltd.)
A9: 2,9-dichloro-1,10-phenanthroline (manufactured by Tokyo Chemical Industry Co., Ltd.)
A10: 3,5,6,8-tetrabromo-1,10-phenanthroline (manufactured by Tokyo Chemical Industry Co., Ltd.)
A11: 4,7-dihydroxy-1,10-phenanthroline (manufactured by Tokyo Kasei Kogyo Co., Ltd.)
A17: 1,10-phenanthroline-2-carboxylic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
A20: 5-methyl-1,10-phenanthroline hydrate (manufactured by Tokyo Kasei Kogyo Co., Ltd.)
A21: 4,7-dimethyl-1,10-phenanthroline hydrate (manufactured by Tokyo Kasei Kogyo Co., Ltd.)
A22: 2,9-dimethyl-1,10-phenanthroline hydrate (manufactured by Tokyo Kasei Kogyo Co., Ltd.)
A23: 5,6-dimethyl-1,10-phenanthroline hydrate (manufactured by Tokyo Kasei Kogyo Co., Ltd.)
A24: 2-methyl-1,10-phenanthroline hydrate (manufactured by Tokyo Kasei Kogyo Co., Ltd.)
A26: 3,4,7,8-tetramethyl-1,10-phenanthroline hydrate (manufactured by Tokyo Chemical Industry Co., Ltd.)
A27: 2,9-dibutyl-1,10-phenanthroline (manufactured by Tokyo Kasei Kogyo Co., Ltd.)
A46: 2,9-diphenyl-1,10-phenanthroline (manufactured by Tokyo Kasei Kogyo Co., Ltd.)
A48: Bathophenanthroline (manufactured by Tokyo Kasei Kogyo Co., Ltd.)
A49: Bathocuproine (manufactured by Tokyo Kasei Kogyo Co., Ltd.)
A51: Bathophenanthroline disulfonic acid disodium hydrate (manufactured by Tokyo Kasei Kogyo Co., Ltd.)
A78: 5-amino-1,10-phenanthroline (manufactured by Tokyo Chemical Industry Co., Ltd.)
A103: Bathocuproin disulfonate disodium (manufactured by Tokyo Kasei Kogyo Co., Ltd.)
A104: 2,9-dibutyl-5-picrylamino-1,10-phenanthroline (manufactured by Tokyo Chemical Industry Co., Ltd.)
A105: (1S)-3-(1,10-phenanthrolin-2-yl)-2'-phenyl-[1,1'-binaphthalene]-2-ol (manufactured by Tokyo Kasei Kogyo Co., Ltd.)
A106: Dipyrido[3,2-a:2',3'-c]phenazine (manufactured by Tokyo Kasei Kogyo Co., Ltd.)
A112: 2-cyano-1,10-phenanthroline (manufactured by ATK CHEMICAL)
A113: 3-benzyl-1,10-phenanthroline

Conductive material (B)
GNP (graphene nanoplatelet “xGNP-M-5” manufactured by XGS Sciences)
CB (Lion Ketjen Black "EC-300J")
Graphite (expanded graphite SMF manufactured by Chuetsu Graphite Co., Ltd.)
MWCNT (Multi-walled carbon nanotube “Knanos100P” manufactured by KUMHO PETROCHEMICAL)
SWCNT (Single-walled carbon nanotube "TUBALL" manufactured by OCSiAl)
PEDOT/PSS “Clevios PH1000” manufactured by Heraeus
Ag powder “FA-D-5” manufactured by DOWA
Cu powder manufactured by DOWA “2.5μm-Type A”

Resin Resin 3 Polymethyl methacrylate resin (NeoCryl B-728 manufactured by Kusumoto Kasei Co., Ltd.)

<Evaluation of thermoelectric conversion materials>
The obtained dispersions 1 to 72 and 101 were coated onto a 75 μm thick PET film, which is a sheet-like base material, using an applicator, and then heated and dried at 120°C for 30 minutes to coat the PET film on the PET base material. A laminate having a thermoelectric conversion film with a thickness of 5 μm was obtained. The coating suitability of the dispersion when applied to a substrate was evaluated according to the method shown below. Furthermore, the conductivity (electrical conductivity) and Seebeck coefficient of the obtained laminate having the thermoelectric conversion film (hereinafter also referred to as coating film) were evaluated according to the following method. The results are shown in Table 10.

(Electrical conductivity (resistivity))
The obtained laminate was cut into a size of 2.5 cm x 5 cm, and the conductivity was measured using a four-probe method using Loresta GX MCP-T700 (manufactured by Mitsubishi Chemical Analytech) in accordance with JIS-K7194. . Table 10 shows relative values when the conductivity of Comparative Example 1 is set to 1.

(Seebeck coefficient)
The obtained laminate was cut into a size of 3 mm x 10 mm, and the Seebeck coefficient (μV/K) at 80° C. was measured using ZEM-3LW manufactured by Advance Riko Co., Ltd. When the absolute value of the Seebeck coefficient in Comparative Example 1 is set to 1, Table 10 shows the relative values to the absolute value of the Seebeck coefficient in each Example.

(Coating suitability)
The coating suitability of the dispersion liquid was evaluated using a grind gauge (groove depth 50 μm).
◎: No streaks or coarse particles due to coarse particles of 10 μm or more (very good)
○: There are streaks and coarse particles due to coarse particles of 10 μm or more, but no streaks or coarse particles due to coarse particles of 20 μm or more (good)
△: There are streaks and coarse particles due to coarse particles of 20 μm or more, but no streaks or coarse particles due to coarse particles of 30 μm or more (usable)
×: There are streaks or coarse particles due to coarse particles of 30 μm or more (unusable)

As shown in Table 10, the thermoelectric conversion material of the present invention exhibited high electrical conductivity and Seebeck coefficient.
Further, all of the dispersions containing the thermoelectric conversion material of the present invention exhibited good coating suitability (coating film condition). On the other hand, Comparative Example 1 using dye-introduced polymer 1 showed low electrical conductivity and Seebeck coefficient.

<Manufacture of thermoelectric conversion elements>
[Example 73]
(Thermoelectric conversion element 1)
Dispersion 1 prepared in Example 1 was applied onto a PET film with a thickness of 50 μm to produce five conductive layers each having a thickness of 20 μm and a shape of 5 mm × 30 mm, spaced apart by 10 mm (reference numbers in FIG. 1). 2). Next, four silver circuits (electrodes) having a thickness of 10 μm and a shape of 5 mm x 33 mm were fabricated using silver paste so that each conductive layer was connected in series (see reference numeral 3 in FIG. 1). ), a thermoelectric conversion element 1 was obtained. As the silver paste, REXALPHA RA FS 074 manufactured by Toyochem Co., Ltd. was used.

[Examples 74 to 144, Comparative Example 2]
(Thermoelectric conversion elements 2 to 72, 101)
Thermoelectric conversion elements 2 to 72 and 101 were obtained in the same manner as thermoelectric conversion element 1, except that dispersion liquid 1 used in thermoelectric conversion element 1 was changed to the dispersion liquid shown in Table 11.
<Evaluation of thermoelectric conversion element>
The electromotive force of the obtained thermoelectric conversion element was evaluated as follows. The results are shown in Table 11.

(Measurement of electromotive force)
Bend each thermoelectric conversion element so that the thermoelectric conversion film and silver circuit are on the inside (along line AA' shown in Figure 2), and place it in that state on a hot plate heated to 100°C. did. The degree of bending was adjusted so that the distance between BB' in FIG. 2 was 10 mm. The sample bent as described above was placed on a hot plate, and the electromotive force between the coating films was measured using a voltmeter 10 minutes later. The measurements were carried out at room temperature (20°C). The thermoelectric properties were evaluated from the measured values according to the following criteria.
◎: Electromotive force is 1 mV or more (good)
〇: Electromotive force is 500μV or more and less than 1mV (practical possible)
×: Electromotive force is less than 500 μV (defective)

As shown in Table 11, the thermoelectric conversion element of the present invention had superior thermoelectric properties compared to the thermoelectric conversion element of Comparative Example 2. From the above, according to the embodiments of the present invention, it is possible to realize a thermoelectric conversion material having excellent Seebeck coefficient and conductivity, and exhibiting a high PF and excellent thermoelectric properties, and a highly efficient thermoelectric conversion element can be realized. I know it can be achieved.

The thermoelectric conversion material according to the embodiment of the present invention has both electrical conductivity and Seebeck coefficient, and also has excellent thermoelectric properties, so the above material can be used to provide a high-performance thermoelectric conversion element.

1: Base material 2: Thermoelectric conversion film 3: Circuit 10: Thermoelectric conversion element test sample 20: Hot plate

Claims (3)

Containing a compound (A) represented by general formula (1) and at least one conductive material (B) selected from the group consisting of carbon materials, metal materials, and conductive polymers ,
The content of the compound (A) is 400% by mass or less based on the total amount of the conductive material (B),
A thermoelectric conversion material, wherein the conductive material (B) contains at least one member selected from the group consisting of carbon nanotubes, Ketjenblack, graphene nanoplates, and graphene .
[In general formula (1), R ₁ to R ₈ are each independently a hydrogen atom, a hydroxyl group, a halogen atom, a cyano group, a nitro group, a carboxyl group, a sodium sulfonate group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, substituted or unsubstituted aryloxy group, substituted or unsubstituted alkylthio group, substituted or unsubstituted arylthio group, substituted or unsubstituted aryl group, substituted or unsubstituted heterocyclic group, or , represents a substituted or unsubstituted amino group. Adjacent groups of R ₁ to R ₈ may be bonded to each other to form a ring. However, at least one of R ₁ to R ₈ is a group other than a hydrogen atom. ] The thermoelectric conversion material according to claim 1 , wherein the conductive material (B) includes carbon nanotubes. A thermoelectric conversion element comprising a thermoelectric conversion film comprising the thermoelectric conversion material according to claim 1 or 2 and an electrode, the thermoelectric conversion film and the electrode being electrically connected.