JP2013098299A - Thermoelectric conversion material and thermoelectric conversion element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoelectric conversion material using an electroconductive polymer, capable of enhancing thermal conversion efficiency by significantly improving electric conductivity.SOLUTION: The thermoelectric conversion material, containing an electroconductive polymer, a carbon nano-tube, and an onium salt compound, has electrical conductivity anisotropy of 1.5 to 10. A material having enhanced thermal conversion characteristics is obtained as a result of the onium salt compound functioning as an excellent dopant by generating acid when a specific external energy is provided under a coexistence of the onium salt compound.

Description

  The present invention relates 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 power generation elements and Peltier elements. Thermoelectric power generation using thermoelectric conversion materials and thermoelectric conversion elements can directly convert thermal energy into electric power, does not require moving parts, and is used for wristwatches that operate at body temperature, power supplies for remote areas, power supplies for space, etc. ing.
Thermoelectric conversion materials are required to have good thermoelectric conversion efficiency, and inorganic materials are mainly used at present. However, these inorganic materials have problems that the material itself is expensive, contains harmful substances, and that the processing process for the thermoelectric conversion element is complicated. For this reason, research on organic thermoelectric conversion materials that can be manufactured at a relatively low cost and that can be easily processed such as film formation has been promoted, and thermoelectric conversion materials and elements using conductive polymers have been reported.

For example, Patent Document 1 is a thermoelectric element using a conductive polymer such as polyaniline, Patent Document 2 is a thermoelectric conversion material containing polythienylene vinylene, and Patent Documents 3 and 4 are doped with polyaniline. Each thermoelectric material is described. Patent Document 5 describes that a polyaniline is dissolved in an organic solvent and spin-coated on a substrate to form a thin film, and a thermoelectric material using the thin film, but the manufacturing process is complicated. Patent Document 6 describes a thermoelectric conversion material composed of a conductive polymer obtained by doping poly (3-alkylthiophene) with iodine, and is reported to exhibit practical thermoelectric conversion characteristics. Patent Document 7 discloses a thermoelectric conversion material made of a conductive polymer obtained by doping polyphenylene vinylene or alkoxy-substituted polyphenylene vinylene.
In addition, practical application of thermoelectric conversion materials to which nanocarbon materials such as carbon nanotubes are added as conductive materials has been studied.
However, these thermoelectric conversion materials still cannot be said to have sufficient thermoelectric conversion efficiency, and development of organic thermoelectric conversion materials having higher thermoelectric conversion efficiency is desired.

The figure of merit ZT of the thermoelectric conversion material is represented by the following formula (A), and it is important to improve the conductivity σ together with the thermoelectromotive force S for improving the performance.

Figure of merit ZT = S ² · σ · T / κ (A)
S (V / K): Thermoelectromotive force (Seebeck coefficient) σ (S / m): Conductivity
κ (W / mK): Thermal conductivity T (K): Absolute temperature

The conductive polymer can further improve the conductivity by orienting the polymer chain in a specific direction by a stretching process or the like to reduce the intermolecular distance (for example, Patent Documents 8 and 9). However, dopants commonly used for thermoelectric conversion materials are oxidizing agents and acidic compounds, which oxidize and aggregate conductive polymers and carbon nanotubes. Therefore, the film | membrane and sheet | seat obtained from the thermoelectric conversion material containing a dopant are weak and inferior in malleability, and it was easy to generate | occur | produce a fracture | rupture and a crack by extending | stretching.

JP 2010-95688 A JP 2009-71131 A JP 2001-326393 A JP 2000-323758 A JP 2002-100815 A JP 2003-332638 A JP 2003-332639 A JP 2005-105510 A JP 2006-114793 A

  The present invention is a thermoelectric conversion material using a conductive polymer and a carbon nanotube (hereinafter also referred to as CNT) as a conductive material, and the heat conversion efficiency is further improved by dramatically improving the conductivity. It is an object to provide a thermoelectric conversion material. Another object of the present invention is to provide a thermoelectric conversion element using the material and a thermoelectric power generation article using the thermoelectric power generation element.

  In view of the above problems, the present inventors have intensively studied a thermoelectric conversion material using a conductive polymer and CNT. As a result, it has been found that when a specific external energy is applied in the presence of an onium salt compound, the onium salt compound generates an acid and functions as an excellent dopant. Furthermore, the present inventors can suppress oxidation / aggregation of conductive polymers and CNTs in a more malleable state unless specific external energy is applied even in the presence of an onium salt compound. We paid attention to the possibility of material molding. As a result, if an onium salt compound is used as a dopant, it is possible to impart a desired conductivity anisotropy by molecular orientation by stretching, friction transfer, etc., and to further improve conductivity, and a material with improved thermoelectric conversion characteristics I found out that The present invention has been completed based on these findings.

That is, said subject was achieved by the following means.
<1> A thermoelectric conversion material containing a conductive polymer, a carbon nanotube, and an onium salt compound, and having a conductivity anisotropy of 1.5 to 10.
<2> The thermoelectric conversion material according to <1>, wherein the onium salt compound is a compound that generates an acid upon application of heat or active energy ray irradiation.
<3> The conductive polymer is a thiophene compound, a pyrrole compound, an aniline compound, an acetylene compound, a p-phenylene compound, a p-phenylene vinylene compound, a p-phenylene ethynylene compound, and these The thermoelectric conversion material according to <1> or <2>, which is a conjugated polymer having a repeating unit derived from at least one monomer selected from the group consisting of derivatives.
<4> The thermoelectric conversion material according to any one of <1> to <3>, which is provided with heat or active energy ray irradiation.
A thermoelectric conversion laminated body provided with a <5> base material and the thermoelectric conversion material according to any one of <1> to <4> provided on the base material.
The thermoelectric conversion laminated body as described in <5> whose <6> base material is a resin film.
<7> A thermoelectric conversion element using the thermoelectric conversion material according to any one of <1> to <4> or the thermoelectric conversion laminate according to <5> or <6>.
<8> The thermoelectric conversion element according to <7>, having an electrode.
<9> An article for thermoelectric power generation using the thermoelectric conversion element according to <7> or <8>.

  The thermoelectric conversion material of the present invention exhibits higher conductivity and is excellent in thermoelectric conversion performance. Moreover, since the thermoelectric conversion element and the article for thermoelectric power generation of the present invention use the thermoelectric conversion material of the present invention, they have excellent thermoelectric conversion performance.

It is a figure which shows typically an example of the thermoelectric conversion element of this invention. The arrows in FIG. 1 indicate the direction of the temperature difference applied when the element is used. It is a figure which shows typically an example of the thermoelectric conversion element of this invention. The arrows in FIG. 2 indicate the direction of the temperature difference applied when the element is used.

The thermoelectric conversion material of the present invention contains a conductive polymer, a carbon nanotube, and an onium salt compound, and has specific conductivity anisotropy. The thermoelectric conversion material of the present invention has improved conductivity due to the doping effect of the onium salt compound, and also has conductivity anisotropy, so that the conductivity is further improved and is excellent. The thermoelectric conversion characteristics are shown.
The thermoelectric conversion material of the present invention is usually simultaneously with the molding of a composition containing a conductive polymer, a carbon nanotube, an onium salt compound, and a solvent (hereinafter sometimes referred to as a composition for a thermoelectric conversion material). Alternatively, after forming, the conductive polymer is oriented to give desired conductivity anisotropy.
Hereinafter, although this invention is explained in full detail, this invention is not limited to these.

[Conductive polymer]
As the conductive polymer, a polymer compound having a conjugated molecular structure can be used. Here, the polymer having a conjugated molecular structure is a polymer having a structure in which single bonds and double bonds are alternately connected in a carbon-carbon bond on the main chain of the polymer.
Examples of such conjugated polymers include thiophene compounds, pyrrole compounds, aniline compounds, acetylene compounds, p-phenylene compounds, p-phenylene vinylene compounds, p-phenylene ethynylene compounds, p-full. Olenylene vinylene compound, polyacene compound, polyphenanthrene compound, metal phthalocyanine compound, p-xylylene compound, vinylene sulfide compound, m-phenylene compound, naphthalene vinylene compound, p-phenylene oxide compound, phenylene A conjugated polymer having a repeating unit derived from a sulfide compound, furan compound, selenophene compound, azo compound, metal complex compound, or a derivative obtained by introducing a substituent into these compounds. But It is below.

The substituent in the above derivative is not particularly limited, but is preferably selected and introduced in consideration of compatibility with other components and the type of medium used.
For example, when an organic solvent is used as a medium, an alkoxyalkyleneoxy group, an alkoxyalkyleneoxyalkyl group, a crown ether group, an aryl group, etc. are preferably used in addition to a linear, branched, or cyclic alkyl group, alkoxy group, or thioalkyl group. be able to. These groups may further have a substituent. The number of carbon atoms of the substituent is not particularly limited, but is preferably 1 to 12, more preferably 4 to 12, and particularly a long-chain alkyl group, alkoxy group or thioalkyl group having 6 to 12 carbon atoms. An alkoxyalkyleneoxy group and an alkoxyalkyleneoxyalkyl group are preferred.
When an aqueous medium is used, it is preferable to introduce a hydrophilic group such as a carboxylic acid group, a sulfonic acid group, a hydroxyl group, or a phosphoric acid group to the terminal of each monomer or the above substituent.
In addition, dialkylamino group, monoalkylamino group, amino group, carboxyl group, ester group, amide group, carbamate group, nitro group, cyano group, isocyanate group, isocyano group, halogen atom, perfluoroalkyl group, perfluoro An alkoxy group or the like can be introduced as a substituent, which is preferable.
The number of substituents that can be introduced is not particularly limited, and one or more substituents can be appropriately introduced in consideration of the dispersibility, compatibility, conductivity, and the like of the conductive polymer.

  Examples of the conjugated polymer having a repeating unit derived from a thiophene compound and a derivative thereof include polythiophene, a conjugated polymer including a repeating unit derived from a monomer having a substituent introduced into the thiophene ring, and a condensation containing a thiophene ring Examples thereof include conjugated polymers containing a repeating unit derived from a monomer having a polycyclic structure.

  Examples of the conjugated polymer containing a repeating unit derived from a monomer having a substituent introduced into a thiophene ring include poly-3-methylthiophene, poly-3-butylthiophene, poly-3-hexylthiophene, and poly-3-cyclohexyl. Thiophene, poly-3- (2′-ethylhexyl) thiophene, poly-3-octylthiophene, poly-3-dodecylthiophene, poly-3- (2′-methoxyethoxy) methylthiophene, poly-3- (methoxyethoxyethoxy) ) Poly-alkyl-substituted thiophenes such as methylthiophene, poly-3-methoxythiophene, poly-3-ethoxythiophene, poly-3-hexyloxythiophene, poly-3-cyclohexyloxythiophene, poly-3- (2'-) Ethylhexyloxy) thiophene, poly-3- Poly-alkoxy substituted thiophenes such as decyloxythiophene, poly-3-methoxy (diethyleneoxy) thiophene, poly-3-methoxy (triethyleneoxy) thiophene, poly- (3,4-ethylenedioxythiophene), poly- Poly-3-alkoxy-substituted-4-alkyl-substituted thiophenes such as 3-methoxy-4-methylthiophene, poly-3-hexyloxy-4-methylthiophene, poly-3-dodecyloxy-4-methylthiophene, poly- Examples thereof include poly-3-thioalkylthiophenes such as 3-thiohexylthiophene, poly-3-thiooctylthiophene, and poly-3-thiododecylthiophene.

  Of these, poly-3-alkylthiophenes and poly-3-alkoxythiophenes are preferable. Regarding polythiophene having a substituent at the 3-position, anisotropy occurs depending on the direction of bonding at the 2,5-position of the thiophene ring. In polymerization of 3-substituted thiophene, those in which the 2-positions of the thiophene ring are bonded to each other (HH conjugate: head-to-head), those in which the 2-position and 5-position are bonded (HT conjugate: head-to-tail) It becomes a mixture of those in which 5-positions are bonded (TT conjugate: tail-to-tail), but the higher the ratio of those in which 2-position and 5-position are bonded (HT conjugate), the more the polymer main chain The planarity is improved, a π-π stacking structure between polymers is easily formed, and it is preferable for facilitating the movement of charges. The proportion of these bonding modes can be measured by H-NMR. The proportion of the HT conjugate in which the 2-position and 5-position of the thiophene ring are bonded in the polymer is preferably 50% by mass or more, more preferably 70% by mass or more, and particularly preferably 90% by mass or more.

  More specifically, a conjugated polymer including a repeating unit derived from a monomer having a substituent introduced into a thiophene ring, and a conjugated polymer including a repeating unit derived from a monomer having a condensed polycyclic structure including a thiophene ring. The following compounds can be exemplified as: In the following formula, n represents an integer of 10 or more.

  Examples of the conjugated polymer having a repeating unit derived from a pyrrole compound and a derivative thereof include the following compounds. In the following formula, n represents an integer of 10 or more.

  Examples of the conjugated polymer having a repeating unit derived from an aniline compound and a derivative thereof include the following compounds. In the following formula, n represents an integer of 10 or more.

  Examples of the conjugated polymer having a repeating unit derived from an acetylene compound and a derivative thereof include the following compounds. In the following formula, n represents an integer of 10 or more.

  Examples of the conjugated polymer having a repeating unit derived from a p-phenylene compound and a derivative thereof include the following compounds. In the following formula, n represents an integer of 10 or more.

  Examples of the conjugated polymer having a repeating unit derived from a p-phenylene vinylene compound and derivatives thereof include the following compounds. In the following formula, n represents an integer of 10 or more.

  Examples of the conjugated polymer having a repeating unit derived from a p-phenylene ethynylene compound and a derivative thereof include the following compounds. In the following formula, n represents an integer of 10 or more.

  Examples of the conjugated polymer having a repeating unit derived from a compound other than the above and derivatives thereof include the following compounds. In the following formula, n represents an integer of 10 or more.

  Among the conjugated polymers, it is preferable to use a linear conjugated polymer. For example, in the case of a polythiophene polymer or a polypyrrole polymer, such a linear conjugated polymer is obtained by bonding the thiophene ring or pyrrole ring of each monomer at the 2,5-positions. In poly-p-phenylene polymer, poly-p-phenylene vinylene polymer, and poly-p-phenylene ethynylene polymer, the phenylene group of each monomer is bonded at the para position (1, 4 position). can get.

  The conductive polymer used in the present invention may have one or more of the above-mentioned repeating units (hereinafter, the monomer giving this repeating unit is also referred to as “first monomer (group)”). You may have in combination. Further, in addition to the first monomer, a repeating unit derived from a monomer having another structure (hereinafter referred to as “second monomer”) may be included. In the case of a polymer composed of a plurality of types of repeating units, it may be a block copolymer, a random copolymer, or a graft polymer.

  Examples of the second monomer having another structure used in combination with the first monomer include a fluorenylene group, a carbazole group, a dibenzo [b, d] silole group, a thieno [3,2-b] thiophene group, and a thieno [ 2,3-c] thiophene group, benzo [1,2-b; 4,5-b ′] dithiophene group, cyclopenta [2,1-b; 3,4-b ′] dithiophene group, pyrrolo [3,4] -C] pyrrole-1,4 (2H, 5H) -dione group, benzo [2,1,3] thiadiazole-4,8-diyl group, azo group, 1,4-phenylene group, 5H-dibenzo [b, d] Compounds having a silole group, a thiazole group, an imidazole group, a pyrrolo [3,4-c] pyrrole-1,4 (2H, 5H) -dione group, an oxadiazole group, a thiadiazole group, a triazole group, and the like of Derivatives obtained by introducing a substituent group to the compound and the like. Examples of the substituent to be introduced include the same substituents as described above.

  The conductive polymer used in the present invention has a total of 50% by mass or more of repeating units derived from one or more monomers selected from the first monomer group in the conductive polymer. Preferably, it is more preferably 70% by mass or more, and further preferably consists of only a repeating unit derived from one or more types of monomers selected from the first monomer group. Particularly preferred is a conjugated polymer comprising only a single repeating unit selected from the first monomer group.

  Among the first monomer group, a polythiophene polymer containing a repeating unit derived from a thiophene compound and / or a derivative thereof is more preferably used. In particular, a polythiophene polymer having a thiophene ring represented by the following structural formulas (1) to (5) or a thiophene ring-containing condensed aromatic ring structure as a repeating unit is preferable.

In the structural formulas (1) to (5), R ^{1 to} R ¹¹ are each independently a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, a perfluoroalkyl group, a perfluoroalkoxy group, an amino group, a thioether group, or polyethylene. An oxy group and an ester group are represented, Y represents a carbon atom or a nitrogen atom, and n represents an integer of 1 or 2. Moreover, * represents the connection part of each repeating unit.

The molecular weight of the conductive polymer is not particularly limited, and may be a high molecular weight oligomer or an oligomer having a lower molecular weight (for example, a weight average molecular weight of about 1000 to 10,000).
From the viewpoint of conductivity, the conductive polymer is preferably one that is not easily decomposed by acid, light, and heat. In order to obtain high conductivity, intramolecular carrier transmission and intermolecular carrier hopping through a long conjugated chain of a conductive polymer are required. For this purpose, the molecular weight of the conductive polymer is preferably large to some extent. From this viewpoint, the molecular weight of the conductive polymer used in the present invention is preferably 5000 or more in terms of weight average molecular weight, and is preferably 7000 to 300,000. It is more preferable that it is 8000-100,000. The weight average molecular weight can be measured by gel permeation chromatography (GPC).

These conductive polymers can be produced by polymerizing the above monomer as a constituent unit by a usual oxidative polymerization method.
Moreover, a commercial item can also be used, for example, the poly (3-hexyl thiophene-2,5-diyl) regioregular product made from an Aldrich company is mentioned.

  Although there is no restriction | limiting in particular in the glass transition temperature (Tg) of the conductive polymer used for this invention, Conductivity anisotropy is made more efficient by using the polymer whose Tg is 150 degrees C or less, Preferably it is 50-130 degreeC. Can be granted. Using a dynamic viscoelasticity measuring device (SII Nanotechnology, DMS6100), Tg is raised to minus 50 ° C. to 200 ° C. at a heating rate of 5 ° C./min. Measured. The temperature of the peak top on the highest temperature side of Tan δ of the measurement data is the value of Tg.

  The content of the conductive polymer in the thermoelectric conversion material of the present invention is preferably 30 to 90% by mass, more preferably 35 to 80% by mass, and more preferably 40 to 70% by mass in the total solid content. It is particularly preferred that

[carbon nanotube]
The carbon nanotube (CNT) includes a single-walled CNT in which a single carbon film (graphene sheet) is wound in a cylindrical shape, a double-walled CNT in which two graphene sheets are wound in a concentric shape, and a plurality of graphenes There is a multilayer CNT in which sheets are wound concentrically. In the present invention, single-walled CNTs, double-walled CNTs, and multilayered CNTs may be used alone, or two or more kinds may be used in combination. In particular, it is preferable to use single-walled CNT and double-walled CNT having excellent properties in terms of conductivity and semiconductor properties, and more preferably single-walled CNT.
Single-walled CNTs may be semiconducting or metallic, and both may be used in combination. When both semiconducting CNT and metallic CNT are used, the content ratio of both in the thermoelectric conversion material can be appropriately adjusted according to the application. The CNT may contain a metal or the like, or may contain a molecule such as fullerene. The thermoelectric conversion material of the present invention may contain nanocarbons such as carbon nanohorns, carbon nanocoils, and carbon nanobeads in addition to CNTs.

CNT can be produced by an arc discharge method, a chemical vapor deposition method (hereinafter referred to as a CVD method), a laser ablation method, or the like. The CNT used in the present invention may be obtained by any method, but is preferably obtained by an arc discharge method and a CVD method.
When producing CNTs, fullerene, graphite, and amorphous carbon are simultaneously generated as by-products, and catalyst metals such as nickel, iron, cobalt, and yttrium remain. In order to remove these impurities, purification is preferably performed. The method for purifying CNTs is not particularly limited, but acid treatment with nitric acid, sulfuric acid, etc., and ultrasonic treatment are effective for removing impurities. In addition, it is more preferable to perform separation and removal using a filter from the viewpoint of improving purity.

After purification, the obtained CNT can be used as it is. Moreover, since CNT is generally produced in a string shape, it may be cut into a desired length depending on the application. For example, when used for semiconductor applications, it is preferable to use CNT shorter than the distance between element electrodes in order to prevent short circuit between element electrodes. CNTs can be cut into short fibers by acid treatment with nitric acid, sulfuric acid or the like, ultrasonic treatment, freeze pulverization method or the like. In addition, it is also preferable to perform separation using a filter from the viewpoint of improving purity.
In the present invention, not only cut CNTs but also CNTs produced in the form of short fibers in advance can be used in the same manner. Such short fibrous CNTs, for example, form a catalytic metal such as iron or cobalt on a substrate and thermally decompose carbon compounds on the surface at 700 to 900 ° C. by CVD to grow CNTs in a vapor phase. Thus, a shape oriented in the direction perpendicular to the substrate surface is obtained. The short fiber CNTs thus produced can be taken out by a method such as peeling off from the substrate. In addition, the short fibrous CNTs can be obtained by supporting a catalytic metal on a porous support such as porous silicon or an anodic oxide film of alumina and growing the CNTs on the surface by the CVD method. Using oriented molecules such as iron phthalocyanine containing a catalytic metal in the molecule as a raw material and producing CNTs on a substrate by performing CVD in an argon / hydrogen gas flow, producing oriented short fiber CNTs You can also. Furthermore, it is also possible to obtain short fiber CNTs oriented on the SiC single crystal surface by an epitaxial growth method.

  The average length of the CNTs used in the present invention is not particularly limited, and can be appropriately selected according to the use of the composition. For example, when the conductive composition of the present invention is used for semiconductor applications, the average length of CNTs is 0.01 μm or more and 1000 μm from the viewpoints of manufacturability, film formability, conductivity, etc., depending on the distance between electrodes. Or less, more preferably 0.1 μm or more and 100 μm or less.

  The diameter of the CNT used in the present invention is not particularly limited, but is preferably 0.4 nm or more and 100 nm or less, more preferably 50 nm or less, and still more preferably, from the viewpoint of durability, transparency, film formability, conductivity, and the like. Is 15 nm or less.

  The content of CNT in the thermoelectric conversion material of the present invention is preferably 2 to 40% by mass, more preferably 5 to 35% by mass, and 8 to 30% by mass in the total solid content. Is particularly preferred.

[Onium salt compound]
The thermoelectric conversion material of the present invention contains an onium salt compound, and the onium salt compound can dramatically improve the conductivity of the thermoelectric conversion material. Although the details of the mechanism for improving the conductivity are not yet clear, the onium salt compound is activated by appropriately applying energy such as light and heat from the outside to the CNT and / or conductive polymer. And expresses oxidizing ability. It is considered that an acid is generated during the oxidation process, and the generated acid acts as a dopant. The dopant improves the conductivity because the conductive polymer and the charge transfer between the conductive polymer and the CNT become smoother.
In the conventional doping technique, an acid such as a protonic acid or a Lewis acid is used as a dopant. Therefore, when an acid is added to the composition for a thermoelectric conversion material, CNT and a conductive polymer aggregate, precipitate, and precipitate. . In such a composition, applicability | paintability and film-forming property were inferior, As a result, the electroconductivity of the thermoelectric conversion material obtained also fell. Further, the obtained film was fragile and inferior in malleability, and processing was limited.
The onium salt compound of the present invention is neutral and does not aggregate, precipitate, or precipitate CNTs or conductive polymers. It is also a compound that generates an acid when energy such as light and heat is applied, and the start timing of acid generation can be controlled. A composition for a thermoelectric conversion material can be prepared under conditions that do not generate an acid to prevent aggregation, and the composition can be molded while maintaining good dispersibility and coating properties. In addition, this molded product is more malleable, and even if the molecules are oriented by pulling or pressing such as stretching or friction transfer, breakage and cracking are unlikely to occur, and conductivity anisotropy should be imparted with high reproducibility. And yield is good. If doping is performed by appropriately applying energy after passing through these steps, a thermoelectric conversion material having high thermoelectric conversion characteristics associated with better conductivity can be prepared.

  The onium salt compound used in the present invention is preferably a compound having an oxidizing ability with respect to CNT and / or a conductive polymer. Furthermore, the onium salt compound used in the present invention is preferably a compound (acid generator) that generates an acid upon application of energy such as light or heat. Examples of the energy application method include irradiation with active energy rays and heating as described later.

  Examples of such onium salt compounds include sulfonium salts, iodonium salts, ammonium salts, carbonium salts, phosphonium salts, and the like. Of these, sulfonium salts, iodonium salts, ammonium salts and carbonium salts are preferable, sulfonium salts, iodonium salts and carbonium salts are more preferable, and sulfonium salts and iodonium salts are particularly preferable. Examples of the anion moiety constituting the salt include a strong acid counter anion.

  Specifically, compounds represented by the following general formulas (I) and (II) are used as sulfonium salts, compounds represented by the following general formula (III) are used as iodonium salts, and the following general formulas are used as ammonium salts. Examples of the compound represented by (IV) and the carbonium salt include compounds represented by the following general formula (V), which are preferably used in the present invention.

In the general formulas (I) to (V), R ^{21 to} R ²³ , R ^{25 to} R ²⁶ and R ^{31 to} R ³³ are each independently a linear, branched or cyclic alkyl group, an aralkyl group, an aryl group, Represents an aromatic heterocyclic group. R ^{27 to} R ³⁰ each independently represent a hydrogen atom, a linear, branched or cyclic alkyl group, an aralkyl group, an aryl group, an aromatic heterocyclic group, an alkoxy group, or an aryloxy group. R ²⁴ represents a linear, branched or cyclic alkylene group or an arylene group. R ^{21 to} R ³³ may further have a substituent. X ⁻ represents an anion of a strong acid.
Any two groups of ^R 21 ^{to R 23} in the general formula (I) is, ^{R 21} and ^{R 23} in the general formula (II) is, the ^{R 25} and ^{R 26} in formula (III), general formula (IV) Any two groups of R ^{27 to} R ³⁰ are bonded to any two groups of R ^{31 to} R ³³ in the general formula (V) to form an aliphatic ring, an aromatic ring, or a heterocyclic ring. May be.

In R ^{21 to} R ²³ and R ^{25 to} R ³³ , the linear or branched alkyl group is preferably an alkyl group having 1 to 20 carbon atoms, specifically, a methyl group, an ethyl group, a propyl group, n- A butyl group, a sec-butyl group, a t-butyl group, a hexyl group, an octyl group, a dodecyl group, and the like can be given.
The cyclic alkyl group is preferably an alkyl group having 3 to 20 carbon atoms, and specific examples include a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a bicyclooctyl group, a norbornyl group, an adamantyl group, and the like.
As the aralkyl group, an aralkyl group having 7 to 15 carbon atoms is preferable, and specific examples include a benzyl group and a phenethyl group.
As the aryl group, an aryl group having 6 to 20 carbon atoms is preferable, and specific examples include a phenyl group, a naphthyl group, an anthranyl group, a phenanthyl group, and a pyrenyl group.
Examples of the aromatic heterocyclic group include pyridyl group, pyrazole group, imidazole group, benzimidazole group, indole group, quinoline group, isoquinoline group, purine group, pyrimidine group, oxazole group, thiazole group, thiazine group and the like.

In R ^{27 to} R ³⁰ , the alkoxy group is preferably a linear or branched alkoxy group having 1 to 20 carbon atoms, specifically, a methoxy group, an ethoxy group, an iso-propoxy group, a butoxy group, or a hexyloxy group. Etc.
The aryloxy group is preferably an aryloxy group having 6 to 20 carbon atoms, and specific examples include a phenoxy group and a naphthyloxy group.

In R ²⁴ , the alkylene group is preferably an alkylene group having 2 to 20 carbon atoms, and specific examples include an ethylene group, a propylene group, a butylene group, and a hexylene group. The cyclic alkylene group is preferably a C 3-20 cyclic alkylene group, and specific examples include a cyclopentylene group, cyclohexylene, bicyclooctylene group, norbornylene group, adamantylene group and the like.
As the arylene group, an arylene group having 6 to 20 carbon atoms is preferable, and specific examples include a phenylene group, a naphthylene group, and an anthranylene group.

When R ^{21 to} R ³³ further have a substituent, the substituent is preferably an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a halogen atom (a fluorine atom, a chlorine atom, an iodine atom), Aryl group having 6 to 10 carbon atoms, aryloxy group having 6 to 10 carbon atoms, alkenyl group having 2 to 6 carbon atoms, cyano group, hydroxyl group, carboxy group, acyl group, alkoxycarbonyl group, alkylcarbonylalkyl group, aryl A carbonylalkyl group, a nitro group, an alkylsulfonyl group, a trifluoromethyl group, —S—R ^{41 and the} like can be mentioned. R ⁴¹ has the same meaning as R ²¹ .

X ⁻ is preferably an anion of an aryl sulfonic acid, an anion of a perfluoroalkyl sulfonic acid, an anion of a perhalogenated Lewis acid, an anion of a perfluoroalkylsulfonimide, a perhalogenate anion, or an alkyl or aryl borate anion. These may further have a substituent, and examples of the substituent include a fluoro group.
Specific examples of anions of aryl sulfonic acids include p-CH ₃ C ₆ H ₄ SO ₃ ⁻ , PhSO ₃ ⁻ , naphthalene sulfonic acid anions, naphthoquinone sulfonic acid anions, naphthalenedisulfonic acid anions, anthraquinone sulfonic acid anions Is mentioned.
Specific examples of the anion of perfluoroalkylsulfonic acid include CF ₃ SO ₃ ⁻ , C ₄ F ₉ SO ₃ ⁻ , and C ₈ F ₁₇ SO ₃ ^— .
Specific examples of the anion of the perhalogenated Lewis acid include PF ₆ ⁻ , SbF ₆ ⁻ , BF ₄ ⁻ , AsF ₆ ⁻ , and FeCl ₄ ⁻ .
Specific examples of the anion of perfluoroalkylsulfonimide include CF ₃ SO ₂ —N ^— SO ₂ CF ₃ and C ₄ F ₉ SO ₂ —N ^— SO ₂ C ₄ F ₉ .
Specific examples of the perhalogenate anion include ClO ₄ ⁻ , BrO ₄ ⁻ and IO ₄ ⁻ .
Specific examples of the alkyl or aryl borate anion include (C ₆ H ₅ ) ₄ B ⁻ , (C ₆ F ₅ ) ₄ B ⁻ , (p-CH ₃ C ₆ H ₄ ) ₄ B ⁻ , (C ₆ H _{4 F)} 4 B ^-, and the like.
X ^- is more preferably an anion of perhalogenated Lewis acid, a fluoro group is an alkyl or aryl borate anions were replaced, more preferably fluoro substituted aryl borate anions, particularly preferably a pentafluorophenyl borate anion.

  Specific examples of the onium salt are shown below, but the present invention is not limited thereto.

In the above specific examples, X ⁻ represents PF ₆ ⁻ , SbF ₆ ⁻ , CF ₃ SO ₃ ⁻ , CH ₃ PhSO ₃ ⁻ , BF ₄ ⁻ , (C ₆ H ₅ ) ₄ B ⁻ , RfSO ₃ ⁻ , ( C ₆ F ₅ ) ₄ B ⁻ , or an anion represented by the following formula

Rf represents a perfluoroalkyl group having an optional substituent.

  In the present invention, an onium salt compound represented by the following general formula (VI) or (VII) is particularly preferable.

In general formula (VI), Y represents a carbon atom or a sulfur atom, Ar ¹ represents an aryl group, and Ar ^{2 to} Ar ⁴ each independently represents an aryl group or an aromatic heterocyclic group. Ar ^{1 to} Ar ⁴ may be further substituted.
Ar ¹ is preferably a fluoro-substituted aryl group, more preferably a pentafluorophenyl group or a phenyl group substituted with at least one perfluoroalkyl group, and particularly preferably a pentafluorophenyl group.
The aryl group and aromatic heterocyclic group of Ar ^{2 to} Ar ^{4 have} the same meanings as the aryl group and aromatic heterocyclic group of R ^{21 to} R ²³ and R ^{25 to} R ³³ described above, preferably an aryl group. Yes, more preferably a phenyl group. These groups may be further substituted, and examples of the substituent include the above-described substituents R ^{21 to} R ³³ .

In General Formula (VII), Ar ¹ represents an aryl group, and Ar ⁵ and Ar ⁶ each independently represent an aryl group or an aromatic heterocyclic group. Ar ¹ , Ar ⁵ and Ar ⁶ may be further substituted.
Ar ¹ has the same meaning as Ar ^{1 in the} general formula (VI), and the preferred range is also the same.
Ar ⁵ and Ar ⁶ are synonymous with Ar ^{2 to} Ar ^{4 in} the general formula (VI), and preferred ranges thereof are also the same.

The said onium salt compound can be manufactured by normal chemical synthesis. Moreover, a commercially available reagent etc. can also be used.
One embodiment of the method for synthesizing the onium salt compound is shown below, but the present invention is not limited thereto. Other onium salts can be synthesized by the same method.
2.68 g of triphenylsulfonium bromide (manufactured by Tokyo Chemical Industry), 5.00 g of lithium tetrakis (pentafluorophenyl) borate-ethyl ether complex (manufactured by Tokyo Chemical Industry), and 146 ml of ethanol were placed in a 500 ml three-necked flask and 2 at room temperature. After stirring for a period of time, 200 ml of pure water is added, and the precipitated white solid is collected by filtration. By washing the white solid with pure water and ethanol and vacuum drying, 6.18 g of triphenylsulfonium tetrakis (pentafluorophenyl) borate can be obtained as an onium salt.

  An onium salt compound can be used individually by 1 type or in combination of 2 or more types. The content of the onium salt compound is preferably 1 part by mass or more, more preferably 2 to 50 parts by mass, and further preferably 5 to 40 parts by mass with respect to 100 parts by mass of the conductive polymer from the viewpoint of the doping effect. It is.

[Other dopants]
In addition to the above onium salt compounds, the thermoelectric conversion material according to the present invention includes oxidizing agents such as halogens, Lewis acids, proton acids, transition metal compounds, electrolyte anions, polyphosphoric acid, hydroxy compounds, carboxy compounds, sulfonic acids. You may contain acidic compounds, such as a compound. These oxidizing agents and acidic compounds are used in amounts that do not cause significant aggregation of the conductive polymer or CNT. Preferably, the total amount in the solid content of the thermoelectric conversion material is 0 to 10% by mass, and more preferably 0 to 5% by mass.

[Thermal excitation assist agent]
The thermoelectric conversion material of the present invention may contain a thermal excitation assist agent. By including a thermal excitation assist agent, the thermoelectromotive force can be further improved.
The thermal excitation assisting agent used for the thermoelectric conversion material of the present invention is a compound having a LUMO having a lower energy level than LUMO (Lowest Unoccupied Molecular Orbital) of a conductive polymer, Refers to a compound that does not form a doped level. On the other hand, the onium salt compound contained in the thermoelectric conversion material of the present invention is a dopant and a compound that forms a doped level in a conductive polymer.
Whether or not a doped level is formed in a conductive polymer can be evaluated by measuring an absorption spectrum. In the present invention, a compound that forms a doped level and a compound that does not form a doped level are evaluated by the following method. It means what was done.
-Evaluation method for the presence or absence of doped level formation-
The conductive polymer A before doping and the separate component B are mixed at a weight ratio of 1: 1, and the absorption spectrum of the thinned sample is observed. As a result, a new absorption peak different from the absorption peak of the conductive polymer A alone or the component B alone is generated, and this new absorption peak wavelength is longer than the absorption maximum wavelength of the conductive polymer A. In some cases, it is determined that a doping level has occurred. In this case, component B is defined as a dopant.

LUMO, a thermal excitation assist agent, has a lower energy level than LUMO of conductive polymer, and acceptor level of thermally excited electrons generated from HOMO (Highest Occupied Molecular Orbital) of conductive polymer. Function.
Furthermore, when the absolute value of the HOMO energy level of the conductive polymer and the absolute value of the LUMO energy level of the thermal excitation assisting agent satisfy the following formula (I), the thermoelectric conversion material is excellent in heat. Equipped with an electromotive force.

Formula (I)
0.1eV ≦ | HOMO of conductive polymer | − | LUMO of thermal excitation assist agent | ≦ 1.9eV

The above formula (I) represents the energy difference between the LUMO of the thermal excitation assist agent and the HOMO of the conductive polymer. When this is smaller than 0.1 eV (the LUMO energy level of the thermal excitation assist agent is a conductive polymer) The activation energy of the electron transfer between the HOMO (donor) of the conductive polymer and the LUMO (acceptor) of the thermal excitation assist agent is extremely small, including the case where the energy level is lower than the HOMO energy level of Aggregation occurs due to an oxidation-reduction reaction between the conductive polymer and the thermal excitation assist agent. As a result, the film formability of the material is deteriorated and the conductivity is deteriorated. Conversely, when the energy difference between the two orbits is larger than 1.9 eV, the energy difference becomes much larger than the thermal excitation energy, so that almost no thermally excited carriers are generated, that is, the effect of adding the thermal excitation assist agent Is almost gone. In order to improve the thermoelectromotive force of the thermoelectric conversion material, it is necessary that the energy difference between both orbits be within the range of the above formula (I).
Note that the HOMO and LUMO energy levels of the conductive polymer and the thermal excitation assist agent are as follows. For the HOMO energy level, a single coating film (glass substrate) of each component is prepared and the HOMO level is determined by photoelectron spectroscopy. The position can be measured. Regarding the LUMO level, the LUMO energy can be calculated by measuring the band gap using an ultraviolet-visible spectrophotometer and then adding it to the HOMO energy measured above. In the present invention, as the HOMO and LUMO energy levels of the conductive polymer and the thermal excitation assist agent, values measured and calculated by the method are used.

The thermal excitation assisting agent improves the thermal excitation efficiency and increases the number of thermally excited carriers, thereby improving the thermoelectromotive force of the material. This principle is different from that for improving the thermoelectric conversion performance by the doping effect of the conductive polymer.
The thermoelectric conversion material performs thermoelectric conversion using the Seebeck effect, and a performance index ZT represented by the following mathematical formula (A) is used as an index representing the thermoelectric conversion performance.

ZT = S ² · σ · T / κ (A)
S (V / K): Thermoelectromotive force (Seebeck coefficient) σ (S / m): Conductivity
κ (W / mK): Thermal conductivity T (K): Absolute temperature

  From the above formula (A), it can be seen that in order to improve the thermoelectric conversion performance of the thermoelectric conversion material, the Seebeck coefficient S and the conductivity σ of the material should be increased and the thermal conductivity κ should be decreased. The Seebeck coefficient is a thermoelectromotive force per 1 K absolute temperature.

  Thermoelectric conversion performance can be improved by increasing the Seebeck coefficient by using a thermal excitation assist agent. When the thermal excitation assist agent is used, the electrons generated by thermal excitation exist in the LUMO of the thermal excitation assist agent, which is the acceptor level, so the holes on the conductive polymer and the electrons on the thermal excitation assist agent And exist physically apart. Therefore, the doped level of the conductive polymer is less likely to be saturated with electrons generated by thermal excitation, and the Seebeck coefficient can be further increased.

  As the thermal excitation assist agent, a polymer containing at least one structure selected from a benzothiadiazole skeleton, a benzothiazole skeleton, a dithienosilol skeleton, a cyclopentadithiophene skeleton, a thienothiophene skeleton, a thiophene skeleton, a fluorene skeleton, and a phenylene vinylene skeleton Compounds, fullerene compounds, phthalocyanine compounds, perylene dicarboxyimide compounds, or tetracyanoquinodimethane compounds are preferred, and are from benzothiadiazole skeleton, benzothiazole skeleton, dithienosilole skeleton, cyclopentadithiophene skeleton, and thienothiophene skeleton. Polymer compound, fullerene compound, phthalocyanine compound, perylene dicarboxyimide compound, or tetracyanoquinodime containing at least one selected structure Emissions-based compounds are more preferable.

  Although the following can be illustrated as a specific example of the thermal excitation assist agent which satisfy | fills the above-mentioned characteristic, this invention is not limited to these. In the following exemplary compounds, n represents an integer (preferably an integer of 10 or more), and Me represents a methyl group.

In the thermoelectric conversion material of the present invention, the above thermal excitation assisting agent can be used alone or in combination of two or more.
The content of the thermal excitation assisting agent in the thermoelectric conversion material is preferably 0 to 40% by mass, more preferably 3 to 30% by mass, and 5 to 25% by mass in the total solid content. Is particularly preferred.

[solvent]
The thermoelectric conversion material of the present invention is usually a composition obtained by applying a composition for a thermoelectric conversion material to a substrate, forming a film, and imparting conductivity anisotropy after drying, or a composition for a thermoelectric conversion material The pellet made of this is friction-transferred onto a substrate and dried. Therefore, although it usually does not contain a solvent, the solvent derived from the composition may be contained to such an extent that the effects of the present invention are not impaired.
As a solvent which can be contained in the composition for thermoelectric conversion materials, water, an organic solvent, and these mixed solvents are mentioned, for example. Preferred are organic solvents, halogen solvents such as alcohol and chloroform, polar organic solvents such as DMF, NMP, and DMSO, aromatic solvents such as chlorobenzene, dichlorobenzene, benzene, toluene, xylene, and pyridine, cyclohexanone, and acetone Preferably, ketone solvents such as methyl ethyl ketone, ether solvents such as diethyl ether, THF, t-butyl methyl ether, dimethoxyethane, and diglyme are used.
In the thermoelectric conversion material of the present invention, the content of the solvent is preferably 10% by mass or less, and more preferably 0 to 5% by mass.

[Other ingredients]
The thermoelectric conversion material of the present invention may appropriately contain an antioxidant, a light stabilizer, a heat stabilizer, a plasticizer and the like in addition to the above components. The content of these components is preferably 5% by mass or less, and more preferably 0 to 2% by mass in the thermoelectric conversion material.
Antioxidants include Irganox 1010 (manufactured by Cigabi Nippon), Sumilizer GA-80 (manufactured by Sumitomo Chemical Co., Ltd.), Sumilizer GS (manufactured by Sumitomo Chemical Co., Ltd.), Sumilizer GM (Sumitomo Chemical Industries, Ltd.) Manufactured) and the like.
Examples of the light-resistant stabilizer include TINUVIN 234 (manufactured by BASF), CHIMASSORB 81 (manufactured by BASF), and Siasorb UV-3385 (manufactured by Sun Chemical).
IRGANOX 1726 (made by BASF) is mentioned as a heat stabilizer.
Examples of the plasticizer include Adeka Sizer RS (manufactured by Adeka).

[Thermoelectric conversion material]
The thermoelectric conversion material of the present invention is a thermoelectric conversion material composition prepared by mixing each component that can be contained in the material in a solvent, molded, and if necessary, dried to give conductivity anisotropy. Can be prepared. The molding preferably includes a step of forming a film by applying the composition for a thermoelectric conversion material on a substrate. Thereby, the thermoelectric conversion material of this invention can be obtained on the said base material. The conductivity anisotropy can be imparted by orienting the conductive polymer in a specific direction. Here, the conductivity anisotropy is a property in which the conductivity varies depending on the direction of measurement, and is a value measured and calculated by the method described in Examples described later. In the thermoelectric conversion material exhibiting conductivity anisotropy, the conductivity increases in the direction in which the conductive polymer is oriented. Therefore, the conductivity in a specific direction can be greatly improved as compared with a material made of the same material that does not exhibit conductivity anisotropy. The conductivity anisotropy can be imparted using techniques such as stretching treatment, friction transfer, rubbing alignment method, photo-alignment method, liquid crystal template alignment method, and the details will be described later.
The conductivity anisotropy is preferably imparted in a state where oxidation and aggregation of the conductive polymer and CNT are suppressed. Therefore, it is preferable not to apply external energy for doping until conductivity anisotropy is imparted to the material.
In the thermoelectric conversion material of the present invention, the conductivity anisotropy is 1.5 to 10, preferably 1.7 to 8, more preferably 2 to 7, and 2.3 to 6. More preferably it is.
There is no restriction | limiting in particular in the preparation method of the said composition for thermoelectric conversion materials, It can carry out under normal temperature normal pressure using a normal mixing apparatus etc. For example, each component may be prepared by dissolving or dispersing in a solvent by stirring and shaking. In addition, ultrasonic treatment may be performed to promote dissolution and dispersion.

[Thermoelectric conversion laminate]
The thermoelectric conversion laminated body of this invention is equipped with the base material and the thermoelectric conversion material of this invention provided on this base material at least. The thermoelectric conversion laminate of the present invention is formed into a film or a sheet by, for example, applying the above composition for a thermoelectric conversion material on a substrate, and dried as necessary, and then the conductivity anisotropy. Can be prepared. The thermoelectric conversion laminate of the present invention can also be obtained by preparing pellets made of the composition for thermoelectric conversion materials and imparting desired conductivity anisotropy by friction transfer onto the pellets. .

  The stretching process and friction transfer method, and the base materials (base materials used for preparing the thermoelectric conversion material and base materials constituting the thermoelectric conversion laminate) used for these will be described below.

(Extension process)
The stretching treatment for imparting conductivity anisotropy is not particularly limited as long as the conductivity anisotropy can be imparted, and may be uniaxial stretching or biaxial stretching. The stretching temperature is preferably Tg to (Tg + 50 ° C.), more preferably (Tg + 5 ° C.) to (Tg + 20 ° C.). A preferable draw ratio is 1.5 to 10 times, more preferably 2 to 6 times at least in one side. Since higher conductivity anisotropy is obtained when one of the stretching ratios is larger than the other, the smaller stretching ratio is preferably 1 to 5 times, more preferably 1 to 2 times, and the larger one. The draw ratio is preferably 1.5 to 10 times, more preferably 2 to 6 times. These stretching operations may be performed in one stage or in multiple stages. The stretching ratio here is the length after stretching when the length before stretching is 1 in the stretching direction.
Such stretching is preferably performed using a nip roll, a tenter or the like. Moreover, you may use the simultaneous biaxial stretching method as described in Unexamined-Japanese-Patent No. 2000-37772, Unexamined-Japanese-Patent No. 2001-113591, and Unexamined-Japanese-Patent No. 2002-103445.

  The stretching treatment can be performed by stretching a film or sheet formed by applying the composition for thermoelectric conversion material on the substrate together with the substrate. Thereby, the thermoelectric conversion material of this invention can be obtained on the extended base material. Moreover, the laminated body itself extended | stretched with the base material is used as a thermoelectric conversion laminated body of this invention.

(Friction transfer)
Friction transfer for imparting conductivity anisotropy can be performed by a normal method described in, for example, Japanese Patent Application Laid-Open No. 2008-150584. For example, a pellet having a smooth surface made of a composition for a thermoelectric conversion material is prepared, and the pellet is pressed against a substrate with a uniform pressure and moved. Thereby, the thermoelectric conversion material of this invention can be obtained on a base material. Moreover, it can use as a thermoelectric conversion laminated body of this invention combining the base material and the thermoelectric conversion material of this invention obtained on the base material. Conditions such as the force for pressing the pellet against the substrate and the moving speed of the pellet may be determined in advance by considering the properties of the pellet and the shape of the required material.

(Base material)
Although there is no restriction | limiting in particular in the base material in the thermoelectric conversion laminated body of this invention, When heating and light irradiation are performed after application | coating and film-forming, it is preferable to select the base material which is hard to be influenced by these irritation | stimulation. Examples of the substrate that can be used in the present invention include substrates such as glass, transparent ceramics, metals, and plastic films. Glass and transparent ceramics lack flexibility compared to metal and plastic films. Further, when the metal and the plastic film are compared in price, the plastic film is preferable because it is less expensive and has flexibility.
From such a viewpoint, as the base material of the present invention, a resin film is preferable, and in particular, a polyester resin (hereinafter, appropriately referred to as “polyester”), a polycycloolefin resin, a polyimide resin, a polycarbonate resin, Polyether resins and polysulfide resins are preferred. The polyester is preferably a linear saturated polyester synthesized from an aromatic dibasic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof.

  Specific examples of the resin film that can be used in the present invention include polyolefin resins such as high-density polyethylene, low-density polyethylene, linear low-density polyethylene, polypropylene, and polybutene, or modified products or derivatives thereof, general-purpose polystyrene, and impact-resistant polystyrene. , Acrylonitrile-styrene copolymers, butadiene-styrene copolymers, acrylonitrile-butadiene-styrene copolymers, polyamide resins such as polymethyl acrylate, nylon 6 and nylon 66, polycarbonate, acrylonitrile, modified products or derivatives thereof, etc. , Polyethylene terephthalate, polyethylene isophthalate, polyethylene naphthalate, polybutylene terephthalate, poly (1,4-cyclohexylenedimethylene terephthalate), polyethylene -2,6-phthalenedicarboxylate, polyester film such as polyester film of bisphenol A and iso and terephthalic acid, product name ZEONOR film (manufactured by ZEON Corporation), ARTON film (manufactured by JSR Corporation), Sumilite FS1700 (Sumitomo Bakelite Corporation) Polycycloolefin films such as product name, Kapton (made by Toray DuPont), Apical (made by Kaneka), Ubilex (made by Ube Industries), Pomilan (made by Arakawa Chemical Co., Ltd.), etc. Polyphenyls such as Pure Ace (manufactured by Teijin Chemicals), Elmec (manufactured by Kaneka), polyether ether ketone films such as the product name Sumilite FS1100 (manufactured by Sumitomo Bakelite), and polyphenyls such as the product name Torelina (manufactured by Toray Industries, Inc.) Sulfide film etc. And the like. Although it is appropriately selected depending on the use conditions and environment, commercially available polyethylene terephthalate, polyethylene naphthalate, various polyimides, polycarbonate films, and the like are preferable from the viewpoints of availability, preferably heat resistance of 100 ° C. or higher, economy, and effects. From the viewpoint of plasticity, polypropylene and polyethylene terephthalate are preferable.

The substrate may be a single layer made of a single material, or may have a structure of two or more layers made of different materials. Moreover, the base material which provided various electrode materials in the crimping | compression-bonding surface with a thermoelectric conversion material is also suitable as a base material of the thermoelectric conversion laminated body of this invention. As this electrode material, transparent electrodes such as ITO and ZnO, metal electrodes such as silver, copper, gold, and aluminum, carbon materials such as CNT and graphene, organic materials such as PEDOT / PSS, and the like can be used.
The thickness of the base material in the thermoelectric conversion laminate of the present invention is preferably 50 to 1000 μm, and more preferably 200 to 800 μm.

  The base material provided with the thermoelectric conversion material of the present invention after undergoing a conductivity anisotropy imparting process such as stretching or friction transfer can be used as it is as a base material of a thermoelectric conversion element described later. Further, after the treatment for imparting conductivity anisotropy, the thermoelectric conversion material obtained on the base material is transferred to another base material, and the base material on which the thermoelectric conversion material is transferred is used as a base material for a thermoelectric conversion element to be described later. It may be used as In that case, as the substrate to be transferred, the same substrate as described above can be used. From the viewpoint of suppressing defects in the thermoelectric conversion material, the transfer is preferably performed under heating at about 100 to 200 ° C.

It is preferable that the thermoelectric conversion material and the thermoelectric conversion laminate provided with conductivity anisotropy are heated or irradiated with active energy rays for doping. Thus, the material and laminated body obtained by providing external energy are especially preferable as the thermoelectric conversion material and thermoelectric conversion laminated body of the present invention. An acid is generated from the onium salt compound by heating or irradiation with active energy rays, and this acid protonates the conductive polymer, so that the conductive polymer is doped with a positive charge (p-type doping).
Active energy rays include radiation and electromagnetic waves, and radiation includes particle beams (high-speed particle beams) and electromagnetic radiation. Particle rays include alpha rays (α rays), beta rays (β rays), proton rays, electron rays (which accelerates electrons with an accelerator regardless of nuclear decay), charged particle rays such as deuteron rays, Examples of the electromagnetic radiation include gamma rays (γ rays) and X-rays (X rays, soft X rays). Examples of electromagnetic waves include radio waves, infrared rays, visible rays, ultraviolet rays (near ultraviolet rays, far ultraviolet rays, extreme ultraviolet rays), X-rays, and gamma rays. The line type used in the present invention is not particularly limited, and for example, an electromagnetic wave having a wavelength near the maximum absorption wavelength of the onium salt compound to be used may be appropriately selected.
Among these active energy rays, ultraviolet rays, visible rays, and infrared rays are preferable from the viewpoint of doping effect and safety, and ultraviolet rays are more preferable. Specifically, it is a light ray having a maximum absorption at 240 to 1100 nm, preferably 300 to 850 nm, more preferably 350 to 670 nm.

For irradiation with active energy rays, a radiation or electromagnetic wave irradiation device is used. The wavelength of the radiation or electromagnetic wave to be irradiated is not particularly limited, and a radiation or electromagnetic wave in a wavelength region corresponding to the sensitive wavelength of the onium salt compound to be used may be selected.
Equipment that can irradiate radiation or electromagnetic waves includes LED lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, deep UV lamps, low-pressure UV lamps and other mercury lamps, halide lamps, xenon flash lamps, metal halide lamps, ArF excimer lamps, and KrF excimer lamps. There are exposure apparatuses that use an excimer lamp, an extreme ultraviolet lamp, an electron beam, or an X-ray lamp as a light source. The ultraviolet irradiation can be performed using a normal ultraviolet irradiation apparatus, for example, a commercially available ultraviolet irradiation apparatus for curing / adhesion / exposure (USHIO Inc. SP9-250UB, etc.).
The exposure time and the amount of light may be appropriately selected in consideration of the type of onium salt compound to be used and the doping effect. Specifically, the light intensity is 10 mJ / cm ^{2 to} 10 J / cm ² , preferably 50 mJ / cm ^{2 to 5} J / cm ² .

  The doping by heat may be performed by heating the thermoelectric conversion material at a temperature higher than the temperature at which the onium salt compound generates acid. The heating temperature is preferably 50 ° C to 200 ° C, more preferably 70 ° C to 120 ° C. The heating time is preferably 5 minutes to 3 hours, more preferably 15 minutes to 1 hour.

[Thermoelectric conversion element]
The thermoelectric conversion material of the present invention has high thermoelectric conversion characteristics and can be suitably used as a material for a thermoelectric conversion element.
The thermoelectric conversion element of the present invention is not particularly limited as long as the thermoelectric conversion material of the present invention is used, and the configuration thereof is not particularly limited, and a base material, a thermoelectric conversion layer containing the thermoelectric conversion material of the present invention, It is preferable to have an electrode for electrically connecting them. Examples of the structure of the thermoelectric conversion element of the present invention include the structure of the element (1) shown in FIG. 1 and the element (2) shown in FIG. The element (1) shown in FIG. 1 includes a pair of electrodes including a first electrode (13) and a second electrode (15) on a first substrate (12), and the electrode of the present invention between the electrodes. An element comprising a layer (14) of thermoelectric conversion material. The second electrode (15) is disposed on the surface of the second base material (16), and the first base material (12) and the second base material (16) are arranged on the outer sides of the metal facing each other. A plate (17) is provided. In the element (2) shown in FIG. 2, a first electrode (23) and a second electrode (25) are disposed on a first base material (22), and a thermoelectric conversion material layer ( 24) is provided. 1 and 2, arrows indicate the direction of the temperature difference when the thermoelectric conversion element is used.

Although the shape and preparation method of a thermoelectric conversion layer are not specifically limited, It is preferable to use the thermoelectric conversion laminated body of this invention, and to use the thermoelectric conversion material contained in this as a thermoelectric conversion layer. As for the thermoelectric conversion laminated body used here, it is preferable that the thermoelectric conversion material of this invention is provided in the form of a film | membrane (film) on a base material, and this base material is functioned as said 1st base material (12, 22). . Therefore, in the thermoelectric conversion laminate of the present invention used for the thermoelectric conversion element of the present invention, the above-mentioned various electrode materials are provided on the surface of the base material (pressure contact surface with the thermoelectric conversion material), and the thermoelectric conversion of the present invention is further provided thereon. A structure provided with a material is preferable.
In the thermoelectric conversion laminate of the present invention, one surface of the thermoelectric conversion material is covered with a base material. When a thermoelectric conversion element is prepared using this, the base material (second base material) is also formed on the other surface. It is preferable to press the material (16, 26) from the viewpoint of protecting the film. Moreover, you may provide the said various electrode material previously in this 2nd base material (16) surface (crimp surface with a thermoelectric conversion material). Moreover, it is preferable to perform the crimping | compression-bonding with a 2nd base material and a thermoelectric conversion material by heating to about 100 to 200 degreeC from a viewpoint of adhesive improvement.

  In the thermoelectric conversion element of the present invention, the direction in which the thermoelectric conversion material of the present invention is disposed is not particularly limited. However, in the thermoelectric conversion element (2) of the form shown in FIG. 2, the first electrode (23) and the first electrode The direction of the shortest distance (straight line) connecting the two electrodes (25) and the direction showing the highest conductivity in the thermoelectric conversion material of the present invention (the arrangement direction of the thermoelectric conversion material, for example, if stretched) It is preferable to arrange the thermoelectric conversion material of the present invention so that the drawing direction and the transfer direction of the pellets in the case of friction transfer are parallel to each other.

In the thermoelectric conversion element of the present invention, the thickness of the thermoelectric conversion layer is preferably 0.1 to 1000 μm, and more preferably 1 to 100 μm. A thin film thickness is not preferable because it is difficult to provide a temperature difference and the resistance in the film increases.
Moreover, there is no restriction | limiting in particular in the thickness of a 1st and 2nd base material, Although it can select suitably according to a use purpose, it is preferable that it is 50-1000 micrometers, and it is preferable that it is 200-800 micrometers. If the substrate is too thin, the film is easily damaged by external impact.

  In general, in a thermoelectric conversion element, compared to a photoelectric conversion element such as an organic thin film solar cell element, the conversion layer may be applied and formed in one organic layer, and the element can be easily manufactured. In particular, when the thermoelectric conversion material of the present invention is used, it is possible to increase the film thickness by about 100 to 1000 times compared to the element for organic thin film solar cells, and the chemical stability against oxygen and moisture in the air is improved. To do.

  The thermoelectric conversion element of the present invention can be suitably used as a power generation element for an article for thermoelectric power generation. That is, the thermoelectric conversion element of the present invention can be suitably used for applications such as hot spring thermal power generation, wristwatch power supply, semiconductor drive power supply, small sensor power supply, solar thermal power generation, waste heat power generation and the like.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in more detail, this invention is not limited to them.

Preparation Example 1
10 mg of conductive polymers 1 to 8 shown below and 4 mg of CNT (ASP-100F, manufactured by Hanwha Nanotech) were added to 5 mL of orthodichlorobenzene, and dispersed in an ultrasonic water bath for 70 minutes. Thereafter, 4 mg of the following onium salt compound was added and sufficiently dissolved to prepare a mixed solution. This mixed solution was applied onto a polypropylene substrate (thickness: 400 μm) and dried under vacuum at room temperature for 12 hours to prepare a laminate having a 2.3 μm-thick thermoelectric conversion film on the polypropylene substrate.

The molecular weights of the conductive polymers 1 to 8 used are as follows.
Conductive polymer 1: weight average molecular weight = 87000
Conductive polymer 2: weight average molecular weight = 77000
Conductive polymer 3: weight average molecular weight = 103000
Conductive polymer 4: weight average molecular weight = 118000
Conductive polymer 5: weight average molecular weight = 95000
Conductive polymer 6: weight average molecular weight = 83000
Conductive polymer 7: weight average molecular weight = 109000
Conductive polymer 8: weight average molecular weight = 69000

The obtained film for thermoelectric conversion was stretched by the following method, and then this film was irradiated with ultraviolet rays (light quantity: 1.06 J / cm ² ) with an ultraviolet irradiation machine (ECS-401GX, manufactured by Eye Graphics Co., Ltd.) By performing doping, a thermoelectric conversion laminate in which a film-like thermoelectric conversion material was provided on the substrate was obtained. In addition, when the presence or absence of doping was measured by the following method, it was confirmed that all the compounds containing the onium salt compound were doped.

[Confirmation of doping]
Whether or not the thermoelectric conversion film was doped was determined by the following measurement.
The absorption spectrum of the film was measured in the wavelength region of 300 to 2000 nm. A new absorption peak appearing on the longer wavelength side than the main absorption of the undoped film is due to doping. When this absorption peak was observed, it was judged that it was doped as desired.

[Stretching]
The thermoelectric conversion film produced on the polypropylene substrate was stretched together with the substrate by an automatic uniaxial stretching machine (manufactured by Sentec Co., Ltd.). The stretching conditions were a chuck-to-chuck distance of 30 mm, a resin temperature of 170 ° C., a stretching speed of 15 mm / min, and a stretching distance of 120 mm (stretching ratio: 5 times). After stretching, the film temperature was cooled to 70 ° C. and taken out from the automatic uniaxial stretching machine.

Preparation Example 2
100 mg of the conductive polymers 1 to 3 and 40 mg of CNT (ASP-100F, manufactured by Hanwha Nanotech) were added to 38 mL of orthodichlorobenzene, and dispersed in an ultrasonic water bath for 70 minutes. Thereafter, 40 mg of the following onium salt compound was added and sufficiently dissolved to prepare a mixed solution. The solvent was distilled off by drying this mixed solution under reduced pressure at room temperature for 24 hours. Next, this solid was separated, packed into a mold, and molded into a pellet while being heated to 180 ° C. and compressed. The pellet was pressed and moved to a polypropylene substrate (thickness: 400 μm) heated to 140 ° C. with a uniform pressure to obtain a thermoelectric conversion laminate including a thermoelectric conversion film. The pressure was 1.4 MPa and the sweep rate was 50 cm / min. Thereafter, the thermoelectric conversion film was irradiated with ultraviolet rays (light quantity: 5.30 J / cm ² ) and doped to obtain a thermoelectric conversion laminate in which a film-like thermoelectric conversion material was provided on the substrate. In addition, when the presence or absence of doping was measured by the above method, it was confirmed that all the compounds containing the onium salt compound were doped.

Test Example About the thermoelectric conversion material which comprises the obtained thermoelectric conversion laminated body, the electrical conductivity anisotropy and the thermoelectric characteristic were roughly measured with the following method. The results of the materials prepared in Preparation Example 1 are shown in Table 1 below, and the results of the materials prepared in Preparation Example 2 are shown in Table 2 below.

[Measurement of conductivity anisotropy]
The thermoelectric conversion laminate obtained in the above Preparation Examples 1 and 2 is cut into a size of 4 cm × 4 cm, and a measuring instrument terminal is applied to the film-like thermoelectric conversion material constituting the laminate at room temperature. The surface resistivity (unit: Ω / □) was measured. Loresta EP (manufactured by Mitsubishi Chemical) was used as the measuring instrument, and ESP type was used as the probe. Subsequently, the film thickness (unit: m) of the thermoelectric conversion material was measured with a stylus type film thickness meter, and the conductivity σ (unit: S / cm) was measured from the reciprocal of the product of the surface resistivity and the film thickness. In the case of a film having anisotropy in conductivity, the conductivity varies depending on the direction. If most conductivity is high in a certain direction, its conductivity sigma _‖ therewith the direction of conductivity perpendicular is defined as sigma _⊥. At this time, the conductivity anisotropy X is defined as X = _σ‖ / _σ⊥ .
In addition, the maximum conductivity described in Tables 1 and 2 is calculated as a relative value of the value of _σσ .

[Measurement of thermoelectric properties]
The obtained thermoelectric conversion film was subjected to a Seebeck coefficient (unit: μV / K) and conductivity (unit: S / cm) at 100 ° C. using a thermoelectric property measuring device (OZawa Scientific Co., Ltd .: RZ2001i). evaluated. Subsequently, the thermal conductivity (unit: W / mK) was calculated using a thermal conductivity measuring device (Eihiro Seiki Co., Ltd .: HC-074). Using these values, a ZT value at 100 ° C. was calculated according to the above formula (A), and this value was used as a thermoelectric characteristic value. Note that the above-mentioned σ _‖ was adopted as the conductivity.

From the result of Table 1, electrical conductivity rose dramatically by containing an onium salt compound as a dopant, and the raise of the thermoelectric characteristic value was also remarkable (comparison of the comparative example 2 and Example 2). Further, it was found that the film can be stretched even at a stretch ratio as high as about 10 times, and desired conductivity anisotropy can be imparted. In Examples 1 to 14 in which the conductivity anisotropy is 1.5 or more, the maximum conductivity was higher and the thermoelectric characteristic value was superior to Comparative Examples 5 and 6 having a lower conductivity anisotropy. .
Further, from the results of Table 2, it can be seen that a significant improvement in the maximum conductivity is recognized not only by stretching but also by friction transfer, and shows a high thermoelectric characteristic value. That is, it has been found that the provision of a predetermined level of conductivity anisotropy greatly contributes to the improvement of conductivity.

DESCRIPTION OF SYMBOLS 1, 2 Thermoelectric conversion element 11, 17 Metal plate 12, 22 1st base material 13, 23 1st electrode 14, 24 Thermoelectric conversion layer 15, 25 2nd electrode 16, 26 2nd base material

Claims (9)

  A thermoelectric conversion material containing a conductive polymer, a carbon nanotube, and an onium salt compound, and having an electric conductivity anisotropy of 1.5 to 10.   The thermoelectric conversion material according to claim 1, wherein the onium salt compound is a compound that generates an acid upon application of heat or active energy ray irradiation.   The conductive polymer includes a thiophene compound, a pyrrole compound, an aniline compound, an acetylene compound, a p-phenylene compound, a p-phenylene vinylene compound, a p-phenylene ethynylene compound, and derivatives thereof. The thermoelectric conversion material according to claim 1 or 2, which is a conjugated polymer having a repeating unit derived from at least one monomer selected from the group.   The thermoelectric conversion material according to any one of claims 1 to 3, which is provided with heat or active energy ray irradiation.   The thermoelectric conversion laminated body provided with a base material and the thermoelectric conversion material of any one of Claims 1-4 provided on this base material.   The thermoelectric conversion laminated body of Claim 5 whose base material is a resin film.   The thermoelectric conversion element using the thermoelectric conversion material of any one of Claims 1-4, or the thermoelectric conversion laminated body of Claim 5 or 6.   The thermoelectric conversion element of Claim 7 which has an electrode.   An article for thermoelectric power generation using the thermoelectric conversion element according to claim 7 or 8.

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