JP6331251B2 - Composition for thermoelectric conversion element and use thereof - Google Patents

Description

The present invention relates to a composition for a thermoelectric conversion element, and a thermoelectric conversion film and a thermoelectric conversion element obtained by using the composition.

The thermoelectric conversion assembly element is an element that converts heat and electric power. The Seebeck effect is used, in which an electromotive force is generated when two different metals or semiconductors are joined and a temperature difference is generated between both ends. In order to obtain a large potential difference, a p-type semiconductor and an n-type semiconductor are used in combination.

The thermoelectric conversion element is used as a thermoelectric module in which a large number of elements are combined in a plate shape or a cylindrical shape. As the thermoelectric conversion element material, for example, from room temperature to 500K, bismuth
Tellurium (Bi-Te), lead / tellurium (Pb-Te) from room temperature to 800K, and silicon / germanium (Si-Ge) from room temperature to 1000K are used. Thermoelectric power generation using thermoelectric conversion elements is used as a power source for ground power generation and artificial satellites.

Thermoelectric conversion elements using these inorganic materials often contain rare elements or contain harmful substances. In addition, it is difficult to process, and has a problem that a thermoelectric conversion element having excellent flexibility due to its rigidity cannot be formed. For this reason, it is difficult to make it versatile, and researches using organic materials as heat conversion materials are underway. Among them, a conductive polymer is promising, a heat conversion element using polyaniline is disclosed in Patent Document 1, a heat conversion element using poly (3-alkylthiophene) is described in Patent Document 2, and polyphenylene vinylene is described in Patent Document 3. The heat conversion element used is also disclosed in Patent Document 4 as poly (3,4-ethylenedioxythiophene) (hereinafter referred to as “PEDOT”).
There are times. ) Are disclosed respectively.

However, the problem of thermoelectric conversion elements using these conductive polymers is that the Seebeck coefficient and the thermoelectric conversion efficiency index (ZT) are insufficient. In order to remedy this problem, the thermoelectric conversion efficiency index (Z
T) is improved.

In particular, a thiophene polymer represented by PEDOT is known as a hole transfer semiconductor having excellent conductivity. By adding a polymer electrolyte such as poly (styrene sulfonic acid) (PSS) to PEDOT, conductivity and water solubility are added as “dopants”, and a relatively high thermoelectric conversion efficiency index ( ZT) is known to show.

Further, by adding a polymer electrolyte such as poly (styrene sulfonic acid) (PSS) to PEDOT and adding a high-boiling solvent such as ethylene glycol, dimethyl sulfoxide, n-methylpyrrolidone or dimethylformamide, Conversion efficiency index (Z
There have been reports of further improving T) and applying it to thermoelectric conversion elements.

However, the conventional technology has a problem that the thermoelectric conversion efficiency index (ZT) is insufficient, and even with a high boiling point solvent, the volatilization of the solvent is inevitable, so the stability over time is insufficient and sufficient durability is obtained. There was a problem that was not possible.

JP 2000-323758 A JP 2003-332638 A JP 2003-332639 A JP2012-84821A

To solve the problems of thermoelectric conversion elements using inorganic materials and conventional conductive polymer materials, to provide thermoelectric conversion elements that are excellent in processability and flexibility and that have a high thermoelectric conversion efficiency index (ZT) It is.

The objective of this invention is providing the thermoelectric conversion composition containing the conductive polymer which is excellent in thermoelectric conversion performance, and is excellent in thermal stability and durability. Furthermore, it is providing the thermoelectric conversion film | membrane and thermoelectric conversion element which are excellent in thermoelectric conversion performance by using the said thermoelectric conversion composition.

As a result of intensive studies to solve the above problems, the present invention has a thermoelectric conversion composition containing a conductive polymer and a compound represented by the general formula [1] having excellent thermoelectric conversion performance and thermal stability. As a result of finding a composition having excellent durability and intensive research, the present invention has been achieved.

That is, the present invention relates to a thermoelectric conversion composition comprising a conductive polymer and any one of compounds represented by the following general formulas (1) to (3) .

In the present invention, the conductive polymer is a unit represented by a unit represented by the following general formula [2] and / or a unit represented by the following general formula [3] and / or the following general formula [3a]. It relates to the said thermoelectric conversion composition characterized by having.

General formula [2]

(Wherein R ¹ and R ² are independently of each other a hydrogen atom, a halogen atom, a substituted or unsubstituted aliphatic hydrocarbon group, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted fat, Heterocyclic group, substituted or unsubstituted aromatic heterocyclic group, cyano group, substituted or unsubstituted alkoxyl group, substituted or unsubstituted aryloxy group, substituted or unsubstituted alkylthio group, substituted or unsubstituted arylthio A group, a substituted amino group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkylsulfonyl group, or an arylsulfonyl group.)

(In the formula, R ³ and R ⁴ are independently of each other a hydrogen atom, a halogen atom, a substituted or unsubstituted aliphatic hydrocarbon group, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted fat, Heterocyclic group, substituted or unsubstituted aromatic heterocyclic group, cyano group, substituted or unsubstituted alkoxyl group, substituted or unsubstituted aryloxy group, substituted or unsubstituted alkylthio group, substituted or unsubstituted arylthio A group, a substituted amino group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkylsulfonyl group, or an arylsulfonyl group.)

  Moreover, this invention relates to the thermoelectric conversion film obtained using the said thermoelectric conversion composition.

  Moreover, this invention relates to the thermoelectric conversion element obtained using the said thermoelectric conversion composition.

The thermoelectric conversion composition of this invention is excellent in thermoelectric conversion performance, and is excellent in thermal stability and durability. Moreover, the thermoelectric conversion element of this invention is excellent in thermoelectric conversion performance, and can be used suitably for utilization of waste heat, such as a factory and a waste incineration plant.

  Hereinafter, the present invention will be described in detail.

Next, R ¹ and R ² in the general formula [2] are independently of each other a hydrogen atom, a halogen atom, a substituted or unsubstituted aliphatic hydrocarbon group, a substituted or unsubstituted aromatic hydrocarbon group,
A substituted or unsubstituted aliphatic heterocyclic group, a substituted or unsubstituted aromatic heterocyclic group, a cyano group, a substituted or unsubstituted alkoxyl group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted alkylthio group, A substituted or unsubstituted arylthio group, substituted amino group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, alkylsulfonyl group, or arylsulfonyl group is represented.

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

Here, the aliphatic hydrocarbon group refers to an aliphatic hydrocarbon group having 1 to 18 carbon atoms, and examples thereof include an alkyl group, an alkenyl group, an alkynyl group, and a cycloalkyl group.

Examples of the alkyl group include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, hexyl, heptyl, octyl, Decyl group, dodecyl group, pentadecyl group,
C1-C18 alkyl groups, such as an octadecyl group, are mentioned.

Examples of the alkenyl group include vinyl group, 1-propenyl group, 2-propenyl group, isopropenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 1-octenyl group,
Examples thereof include alkenyl groups having 2 to 18 carbon atoms such as 1-decenyl group and 1-octadecenyl group.

Examples of the alkynyl group include ethynyl group, 1-propynyl group, 2-propynyl group, 1
-Butynyl group, 2-butynyl group, 3-butynyl group, 1-octynyl group, 1-decynyl group,
C2-C18 alkynyl groups, such as 1-octadecynyl group, are mentioned.

Examples of the cycloalkyl group include cycloalkyl groups having 3 to 18 carbon atoms such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, and a cyclooctadecyl group.

Furthermore, examples of the aromatic hydrocarbon group include a single ring, a condensed ring, and a ring assembly hydrocarbon group.
Here, as the monocyclic aromatic hydrocarbon group, a phenyl group, an o-tolyl group, an m-tolyl group, p
1 to 6-18 carbon atoms such as -tolyl group, 2,4-xylyl group, p-cumenyl group and mesityl group
Valent monocyclic aromatic hydrocarbon group.

Examples of the condensed ring hydrocarbon group include 1-naphthyl group, 2-naphthyl group, 1-anthryl group, 2-anthryl group, 5-anthryl group, 1-phenanthryl group, 9-phenanthryl group, 1-acenaphthyl group, Examples thereof include condensed ring hydrocarbon groups having 10 to 18 carbon atoms such as 2-azurenyl group, 1-pyrenyl group and 2-triphenylyl group.

Examples of the ring assembly hydrocarbon group include ring assembly hydrocarbon groups having 12 to 18 carbon atoms such as an o-biphenylyl group, an m-biphenylyl group, and a p-biphenylyl group.

Examples of the aliphatic heterocyclic group include 2-pyrazolino group, piperidino group, morpholino group, 2
-C3-C18 aliphatic heterocyclic groups, such as a morpholinyl group.

Examples of the aromatic heterocyclic group include triazolyl group, 3-oxadiazolyl group, 2-furanyl group, 3-furanyl group, 2-furyl group, 3-furyl group, 2-thienyl group, 3-thienyl group, 1- Pyrrolyl group, 2-pyrrolyl group, 3-pyrrolyl group, 2-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-benzothienyl group, N-indolyl group, N-carbazolyl group, N
-An aromatic heterocyclic group having 2 to 18 carbon atoms such as an acridinyl group, a 2-thiophenyl group, a 3-thiophenyl group, a bipyridyl group, and a phenanthroyl group.

Moreover, as an alkoxyl group, C1-C8 alkoxyl groups, such as a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a tert-butoxy group, an octyloxy group, a tert-octyloxy group, are mentioned.

Examples of the aryloxy group include aryloxy groups having 6 to 14 carbon atoms such as phenoxy group, 4-tert-butylphenoxy group, 1-naphthyloxy group, 2-naphthyloxy group, and 9-anthryloxy group. .

Moreover, as an alkylthio group, a C1-C8 alkylthio group, such as a methylthio group, an ethylthio group, a tert- butylthio group, a hexylthio group, and an octylthio group, is mentioned.

As the arylthio group, a phenylthio group, 2-methylphenylthio group, 4-t
Examples thereof include an arylthio group having 6 to 14 carbon atoms such as an ert-butylphenylthio group.

The substituted amino group includes N-methylamino group, N-ethylamino group, N, N-diethylamino group, N, N-diisopropylamino group, N, N-dibutylamino 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) C2-C26 substituted amino such as amino group, bis [4- (4-methyl) biphenylyl] amino group, N-α-naphthyl-N-phenylamino group, N-β-naphthyl-N-phenylamino group Groups.

Moreover, as an acyl group, C2-C14 acyl groups, such as an acetyl group, a propionyl group, a pivaloyl group, a cyclohexyl carbonyl group, a benzoyl group, a toluoyl group, an anisoyl group, a cinnamoyl group, are mentioned.

Moreover, as an alkoxycarbonyl group, C2-C14 alkoxycarbonyl groups, such as a methoxycarbonyl group, an ethoxycarbonyl group, a benzyloxycarbonyl group, are mentioned.

Examples of the aryloxycarbonyl group include aryloxycarbonyl groups having 2 to 14 carbon atoms such as phenoxycarbonyl group and naphthyloxycarbonyl group.

Moreover, as an alkylsulfonyl group, C2-C14 alkylsulfonyl groups, such as a mesyl group, an ethylsulfonyl group, a propylsulfonyl group, are mentioned.

Moreover, as an arylsulfonyl group, C2-C14 arylsulfonyl groups, such as a benzenesulfonyl group and p-toluenesulfonyl group, are mentioned.

In R ¹ and R ² , an aliphatic hydrocarbon group, an aromatic hydrocarbon group, an aliphatic heterocyclic group, an aromatic heterocyclic group, an alkoxyl group, an aryloxy group, an alkylthio group, and an arylthio group are further substituted. It may be substituted by a group. Such substituents include halogen atoms, cyano groups, alkoxyl groups, aryloxy groups, alkylthio groups, arylthio groups, substituted amino groups, acyl groups, alkoxycarbonyl groups, aryloxycarbonyl groups, alkylsulfonyl groups, arylsulfonyl groups. Etc. Examples of these substituent groups include those described above.

Next, R ³ and R ⁴ in the general formula [3] and the general formula [3a] are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted aliphatic hydrocarbon group, a substituted or unsubstituted Aromatic hydrocarbon group, substituted or unsubstituted aliphatic heterocyclic group, substituted or unsubstituted aromatic heterocyclic group, cyano group, substituted or unsubstituted alkoxyl group, substituted or unsubstituted aryloxy group, substituted or It represents an unsubstituted alkylthio group, a substituted or unsubstituted arylthio group, a substituted amino group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkylsulfonyl group, or an arylsulfonyl group.

R ³ and R ⁴ in general formula [3] and general formula [3a], a halogen atom, a substituted or unsubstituted aliphatic hydrocarbon group, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted Aliphatic heterocyclic group, substituted or unsubstituted aromatic heterocyclic group, cyano group, substituted or unsubstituted alkoxyl group, substituted or unsubstituted aryloxy group, substituted or unsubstituted alkylthio group, substituted or unsubstituted An arylthio group, a substituted amino group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkylsulfonyl group, and an arylsulfonyl group are each a halogen atom in R ¹ and R ² , a substituted or unsubstituted aliphatic hydrocarbon, Group, substituted or unsubstituted aromatic hydrocarbon group, substituted or unsubstituted aliphatic heterocyclic group, Or an unsubstituted aromatic heterocyclic group, a cyano group, a substituted or unsubstituted alkoxyl group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted alkylthio group, a substituted or unsubstituted arylthio group, a substituted amino group, It is synonymous with an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkylsulfonyl group, and an arylsulfonyl group.

  Representative examples of the unit represented by the general formula [2], the general formula [3], and the unit represented by the general formula [3a] used in the present invention are shown in Table 2 below. It is not limited to a representative example.

  The conductive polymer of the present invention will be described below.

The conductive polymer contained in the thermoelectric conversion composition of the present invention is not particularly limited as long as it is a polymer having electrical conductivity. Examples thereof include polyacetylene, polyaniline, polypyrrole, polythiophene, polyparaphenylene, and polyphenylene vinylene. Moreover, these mixtures may be sufficient. Of these, polythiophene is preferable from the viewpoint of superior conductivity.

The polythiophene is not particularly limited as long as it has a thiophene skeleton unit (repeating unit). Moreover, as polythiophene, what was cationically charged in presence of a polyanion can be used, for example. Polythiophene has a general formula [2
], Units represented by general formula [3] and general formula [3a] can be used alone or in combination of two or more.

When the polythiophene has two or more units, the polythiophene becomes a copolymer. The polythiophene copolymer is not particularly limited with respect to its arrangement. For example, the copolymer which has a random copolymer and a block copolymer is mentioned.

The dopant that polythiophene can have is not particularly limited, but a polymer electrolyte is desirable from the viewpoint of imparting solubility to polythiophene. The polymer electrolyte preferably has an anion in the side chain or main chain. Examples of the polymer electrolyte include those having carboxylic acid and sulfonic acid. Among these, polystyrene sulfonic acid (PSS) is desirable from the viewpoint of solubility in water.

The conductive polymer is not particularly limited with respect to its production method. For example, a conventionally well-known thing is mentioned. Polythiophene as a conductive polymer can be produced, for example, by subjecting a monomer having a thiophene skeleton to chemical or electrochemical oxidative polymerization.

The monomer used in the production of polythiophene is not particularly limited as long as it is a compound having a thiophene skeleton. For example, the thing corresponding to the unit which has said thiophene skeleton is mentioned. Specific examples include 3,4-alkylenedioxythiophene. Examples of the alkylene group possessed by 3,4-alkylenedioxythiophene include an optionally substituted alkylene group having 1 to 18 carbon atoms. Specifically, for example,
Examples include 1,2-ethylene group, 1,3-propylene group, and 1,2-cyclohexylene group. Examples of the substituent include a sulfonate group, a sulfonate group, a hydroxy group, a carboxy group, an amino group, an amide group, and an imide group.

Moreover, a commercial item can be used as a conductive polymer. As a commercially available product of polythiophene, for example, the product name Baytron P (manufactured by Bayer) is supplied.
Mention may be made of stabilized dispersions of thiophene-containing polymers. The conductive polymers can be used alone or in combination of two or more.

The amount of the compound represented by the general formula [1] added to the conductive polymer is 0.1 parts by weight with respect to 100 parts by weight of the conductive polymer from the viewpoint of being excellent in conductivity and thermal stability. The above is preferable, more preferably 1 to 100 parts by weight, and still more preferably 20 to 50 parts by weight.

In addition to the conductive polymer and the compound represented by the general formula [1], the thermoelectric conversion composition of the present invention can further contain an additive as long as the effects of the present invention are not impaired. The additive is not particularly limited. For example, film forming agents, crosslinking agents, binders, dopants other than the compounds contained in the thermoelectric conversion composition of the present invention, matting agents, surfactants, coating aids, polymers for improving dimensional stability Lattice, thickener, thickener, viscosity modifier, hardener, antistatic agent, dye, pigment, antifoggant, lubricant, antioxidant, and adhesion promoter can be included. The additives can be used alone or in combination of two or more.

By further adding a solvent at the time of mixing, the film forming property can be enhanced. Examples of the solvent include water; alcohols such as methanol, ethanol, propanol, and isopropanol; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; and carbonic acid such as propylene carbonate, ethylene carbonate, vinylene carbonate, and methylpropyl carbonate. Esters; esters such as ethyl propionate, γ-butyrolactone, γ-valerolactone, δ-valerolactone, methyl acetate and ethyl acetate; ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether and glycol ether; And compounds in which a substituent such as fluorine is introduced. A solvent can be used individually or in combination of 2 types or more, respectively.

The thermoelectric conversion composition of the present invention is not particularly limited for its production. Conductive polymer, compound and additives that can be used as necessary are mixed by, for example, mechanical stirring by a kneader such as a roll, kneader, Banbury mixer, stirring by a stirrer, stirring using ultrasonic waves, etc. And a method for producing the thermoelectric conversion composition of the present invention. Moreover, when using a solvent, a thermoelectric conversion composition of this invention can be manufactured by mixing a conductive polymer and a compound using a bead mill and a three roll, for example.

The thermoelectric conversion composition of the present invention can be obtained as a water-based and / or solvent-based dispersion.

The base material to which the thermoelectric conversion composition of the present invention can be applied is not particularly limited. Examples of the base material include polyethylene terephthalate, polyethylene naphthalate, polyethersulfone, polyetherimide, polyetheretherketone, polyphenylene sulfide, polyarylate, polyimide, polyamide, polycarbonate, polyester, polystyrene, poly (vinyl acetal), and cellulose. Examples include triacetate, cellulose nitrate, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, glass, and silicon wafer.

One preferred embodiment is that the substrate is a flexible film support. The substrate may be transparent or opaque depending on the application.

  A method for producing the thermoelectric conversion film of the present invention on a substrate will be described below.

When the thermoelectric conversion film of the present invention is produced on a substrate, the production method includes, for example, an application step of applying the thermoelectric conversion composition on the substrate, and, if necessary, a thermoelectric conversion composition. And a drying method of forming a thermoelectric conversion film by drying.

An application process is a process of apply | coating a thermoelectric conversion composition on a base material, and forming the coating film of a thermoelectric conversion composition on a base material. In the coating process, as a method of coating the thermoelectric conversion composition on the substrate, for example, Langmuir Bromide (LB) film formation method, spin coating method, spray coating method, ink jet method, screen printing method, flexographic printing method, Examples include a dip method, a centrifugal molding method, an extrusion molding method, an injection molding method, an inflation molding method, and an optical pattern forming method.

In order to improve the thermoelectric conversion performance, fine particles made of an inorganic thermoelectric material may be added to the thermoelectric conversion composition of the present invention. Inorganic thermoelectric materials include Bi- (Te, Se) -based, Si-Ge-based,
Pb-Te system, GeTe-AgSbTe system, (Co, Ir, Ru) -Sb system, (Ca, S
r, Bi) Co ₂ O _{5 and the} like can be mentioned. Specifically, Bi ₂ Te ₃ , PbTe, A
gSbTe ₂ , GeTe, Sb ₂ Te ₃ , NaCo ₂ O ₄ , CaCoO ₃ , SrTiO ₃ , Z
_{nO, SiGe, FeSi 2, Ba} 8 Si 46, MnSi 1.73, ZnSb, Zn 4 Sb 3, Ge
Examples thereof include Fe ₃ CoSb ₁₂ and LaFe ₃ CoSb ₁₂ . At this time, impurities may be added to the inorganic thermoelectric material to control the polarity (p-type, n-type) and conductivity as a semiconductor.

A drying process is a process of drying the coating film of a thermoelectric conversion composition after an application | coating process, and forming a thermoelectric conversion film. In addition, a drying process can be provided as needed. When heating and drying a coating film in a drying process, it is preferable that temperature is 80-150 degreeC.

Since the thermoelectric conversion composition of the present invention is excellent in thermal stability, the temperature in the drying process can be increased, and the productivity is excellent.

When manufacturing the thermoelectric conversion element of this invention, the manufacturing method in particular is not restrict | limited. For example, a conventionally well-known thing is mentioned.

A thermoelectric conversion element can be produced by attaching two electrodes to a thermoelectric conversion film obtained using a thermoelectric conversion composition.

As the electrode, a metal, an alloy, and a semiconductor can be preferably used, but a metal and an alloy are preferable because of high conductivity, and gold, silver, copper, aluminum, and an alloy thereof are preferable.

The electrode can be formed by vacuum deposition, thermocompression bonding of a film having an electrode material foil or an electrode material film, application of a paste in which fine particles of the electrode material are dispersed, and the like. Among these, from the viewpoint that the process is simple, it is preferable to form an electrode by thermocompression bonding of a film having an electrode material foil or an electrode material film and application of a paste in which the electrode material is dispersed.

As a representative example of the positional relationship between the thermoelectric conversion film and the two electrodes, when electrodes are formed at both ends of the thermoelectric conversion film of the present invention, when the thermoelectric conversion film of the present invention is sandwiched between two electrodes, Of 2
One of them.

For example, after forming a thermoelectric conversion film on a substrate, a thermoelectric element in which electrodes are formed on both ends of the thermoelectric conversion film of the present invention can be created by applying a silver paste to both ends thereof. For example,
An electrode film is formed by applying a silver paste on a substrate, and the thermoelectric conversion film of the present invention is formed on the electrode film. A thermoelectric element in which the thermoelectric conversion film of the invention is sandwiched can be formed.

When electrodes are formed on both ends of the thermoelectric conversion film, it is easy to increase the distance between the two electrodes, and as a result, a large temperature difference can be generated between the two electrodes to perform thermoelectric conversion. .

When the thermoelectric conversion film of the present invention is sandwiched between two electrodes, it is difficult to increase the distance between the two electrodes. This is because it depends on the thickness of the thermoelectric conversion film. For this reason, 2
It is difficult to generate a large temperature difference between the two electrodes. However, since a temperature difference in a direction perpendicular to the base material can be used, it can be used in a form such as being attached to a heating element, which is preferable in terms of easy utilization of a large area of the heat source.

Further, it is possible to generate a high voltage by connecting thermoelectric elements in series, and it is possible to generate a large current by connecting them in parallel. It is also possible to connect two or more thermoelectric elements.

It is also effective to combine the thermoelectric element of the present invention with a thermoelectric element made of another thermoelectric material.
For example, as the inorganic thermoelectric material, Bi— (Te, Se), Si—Ge, Pb—Te, GeTe—AgSbTe, (Co, Ir, Ru) —Sb, (Ca, Sr, Bi) C
o ₂ O _{5 and the} like 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, SiG
e, FeSi ₂ , Ba ₈ Si ₄₆ , MnSi _1.73 , ZnSb, Zn ₄ Sb ₃ , GeFe ₃ CoS
b ₁₂ , LaFe ₃ CoSb _{12 and the} like. At this time, impurities may be added to the inorganic thermoelectric material to control the polarity (p-type, n-type) and conductivity. Examples of the organic thermoelectric material include polythiophene, polyaniline, polyacetylene, fullerene, and derivatives thereof.

When connecting a plurality of thermoelectric elements, they can be connected and used in a state of being integrated on one base material. At this time, it is preferable to combine a thermoelectric element made of a thermoelectric material exhibiting n-type polarity with the thermoelectric element of the present invention and connect them in series because it is easy to densely integrate the thermoelectric elements.

As for the thermoelectric conversion composition, it has been conventionally proposed to add a high boiling point solvent as a secondary dopant in order to increase the conductivity of the conductive polymer (for example, Patent Document 4). However, even if it is a high boiling point solvent, volatilization is unavoidable and the component composition tends to change. For this reason, when considering applying a composition containing a high-boiling solvent as an electrical / electronic material, such a composition may have unstable electrical characteristics. Further, since the organic solvent is flammable, there is a problem that reliability and safety are low and the application range is narrowed.

Conventionally, it is known that when a dopant is added to a conductive polymer, the conductivity of the conductive polymer is greatly improved by making the amount of the dopant extremely small. In general, the conductivity of the dopant itself is significantly lower than the conductivity of the conductive polymer after doping. For this reason, even if a dopant is added to the conductive polymer more than necessary, the conductivity of the composition containing the conductive polymer and a large amount of dopant is not improved as compared with the conductive polymer. The thermoelectric conversion figure of merit (ZT) decreases in the thermoelectric conversion element using the thermoelectric conversion composition.

In addition, it has been the conventional theory that mixing a large amount of a polymer electrolyte as a dopant in a conductive polymer significantly reduces the conductivity. For example, a polymer electrolyte such as PSS is added to PEDOT for the purpose of imparting conductivity. In this way, PE
It has been thought that mixing a large amount of a polymer electrolyte (salt) as a dopant with a conductive polymer such as DOT significantly reduces the conductivity. However, according to the present invention,
By adding the compound represented by the general formula [1] as a dopant to the conductive polymer, the conductivity of the conductive polymer can be improved, and as a result, an excellent thermoelectric conversion performance index (
ZT).

EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples at all. In the following description of Examples and Comparative Examples, parts represent parts by weight and% represents% by weight. “Mn” represents the number average molecular weight.

Synthesis example 1
In 57 ml of deionized water, 0.27 g of compound (21) in Table 3, 6.53 g of polystyrene sulfonic acid 18% aqueous solution (Mn: 70,000), 0.54 g of ammonium persulfate and 15 mg of iron sulfate (III) was added and stirred at room temperature for 24 hours to obtain an aqueous dispersion of the conductive resin (1) (solid content: 2.0%).

Synthesis Examples 2-7
Except for using the compounds (22) to (27) in Table 3 instead of the compound (21) in Table 3,
A conductive resin aqueous dispersion was obtained in the same manner as in Synthesis Example 1 (solid content: 2.0%).

Synthesis example 8
Instead of the compound (21) in Table 3, 1 of the compound (21) in Table 3 and the compound (25) in Table 3
A conductive resin aqueous dispersion was obtained in the same manner as in Synthesis Example 1 except that a 1 (molar ratio) mixture was used (solid content 2.0%).

Synthesis Example 9
Instead of compound (21) in Table 3, 1 of compound (21) in Table 3 and compound (26) in Table 3
A conductive resin aqueous dispersion was obtained in the same manner as in Synthesis Example 1 except that a 1 (molar ratio) mixture was used (solid content 2.0%).

Synthesis Example 10
Instead of compound (21) in Table 3, 1 of compound (21) in Table 3 and compound (30) in Table 3
A conductive resin aqueous dispersion was obtained in the same manner as in Synthesis Example 1 except that a 1 (molar ratio) mixture was used (solid content 2.0%).

Hereinafter, the conductive resins synthesized in Synthesis Examples 1 to 10 are shown in Table 4. In addition, in the conductive resin synthesized in Synthesis Examples 1 to 10, polystyrene sulfonic acid is mixed in a weight ratio 4.3 times that of the following polymer 1. N and m are positive integers from 1 to 100,000.

Here, the dimensionless thermoelectric figure of merit (ZT) and its derivation will be described. ZT is represented by the following formula.
ZT = (S ² · σ · T) / κ
Here, S is the Seebeck coefficient (V / K), σ is the conductivity (S · m), and κ is the thermal conductivity (W / (
m · K)). The thermal conductivity κ is expressed by the following formula.
κ = α ・ ρ ・ C
Where 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)).
Seebeck coefficient and electrical conductivity are ZEME-2 (manufactured by ULVAC-RIKO), thermal diffusivity is periodic heating method thermal diffusivity measuring device FTC-1 (manufactured by ULVAC-RIKO), specific heat capacity is differential scanning calorimeter DS
C6200 (manufactured by Seiko Instruments Inc.) was used, and the density was 1.45 (g /
ZT was calculated assuming that it was cm ³ ).

Example 1
Conductive polymer aqueous dispersion PEDOT / PSS (poly (3
, 4-Ethylenedioxy) -2,5-thiophene / polystyrene sulfonic acid, (Baye
r, BAYTRON P) 2.0 g, and the compound (1) in Table 1 of the present invention in the amount shown in Table 5 and 2-isopropyl alcohol 1.0 g were mixed, and this was mixed with a bar coater (No. 8).
) Was applied onto a PET plate and dried by heating at 100 ° C. for 3 minutes to obtain a thermoelectric conversion film (film thickness 30 μm). Table 5 shows the results of calculating ZT in an environment of 100 ° C. immediately after the production and after the endurance test (100 hours in an environment of 60 ° C.) for this thermoelectric conversion film.
Shown in
Moreover, this thermoelectric conversion film was cut out together with a base material in the strip shape of width 1mm x length 40mm, and was adhere | attached on the adhesive surface of the polyimide film which has an adhesion layer at intervals of 2 mm. Furthermore, a nickel foil (thickness 20 μm) forming a thermocouple and a thermocouple was cut into a strip shape having a width of 1 mm × a length of 40 mm and placed between the strip-like thermoelectric conversion films on the adhesive surface of the polyimide film. A unit thermocouple is formed by electrically connecting one end of the thermoelectric conversion film and one end of the nickel foil using the conductive paste Dotite D-500 (Fujikura Kasei Co., Ltd.) Ten pairs of unit thermocouples were provided on the polyimide film, and these unit thermocouples were connected in series to produce a thermoelectric conversion element.
A plurality of electrical connection portions arranged on one side of the thermoelectric conversion element were brought into contact with a heater as hot contacts, and a power generation experiment was performed at room temperature. When the hot junction temperature was 105 ° C., the other plurality of electrical connection portions, that is, the cold junction, was 25 ° C., which was almost the same as room temperature, and a sufficient temperature difference was obtained between the two contacts. Table 5 shows the maximum output power obtained from the current-voltage characteristics at this time.

Table 5

Example 2
As an aqueous dispersion of a conductive polymer, a polythiophene derivative (poly (thiophene-3- [2-
(2-methoxyethoxy) ethoxy] -2,5-diyl), sulfonated 2% in ethylene glyc
A thermoelectric conversion film and a thermoelectric conversion element were prepared and evaluated in the same manner as in Example 1 except that ol monobutyl ether / water, 3: 2, electronic grade (manufactured by Aldrch) was used. The results are shown in Table 6.

Table 6

Example 3
A thermoelectric conversion film and a thermoelectric conversion element were prepared and evaluated in the same manner as in Example 1 except that the conductive polymer (1) shown in Table 4 was used as the aqueous dispersion of the conductive polymer. The results are shown in Table 7.

Table 7

Example 4
Example The conductive polymer (1) shown in Table 4 was used as the aqueous dispersion of the conductive polymer, and the compound (2) shown in Table 1 was added instead of the compound (1) shown in Table 1. As in Example 1, a thermoelectric conversion film and a thermoelectric conversion element were prepared and evaluated. The results are shown in Table 7. The results are shown in Table 8.

Table 8

Example 5
Except that the conductive polymer (1) in Table 4 was used as the aqueous dispersion of the conductive polymer, and the compound (3) in Table 1 was added instead of the compound (1) in Table 1. As in Example 1, a thermoelectric conversion film and a thermoelectric conversion element were prepared and evaluated. The results are shown in Table 9.

Table 9

Examples 6-14
As the aqueous dispersion of the conductive polymer, the conductive polymer shown in Table 4 listed in Table 10 was used.
A thermoelectric conversion film and a thermoelectric conversion element were prepared and evaluated in the same manner as in Example 1 except that 0.025 g (50% based on the conductive polymer solid content) of the compound (1) therein was added. The results are shown in Table 10.

Table 10

Reference Example 15
As an aqueous dispersion liquid of the conductive polymer, using a table 4 of the conductive polymer (1), of compounds the following compounds in place of (1) (4) except for adding, as in Embodiment 1 A thermoelectric conversion film and a thermoelectric conversion element were prepared and evaluated. The results are shown in Table 11.

Table 11

Reference Example 16
As an aqueous dispersion liquid of the conductive polymer, using a table 4 of the conductive polymer (1), except that the following compound (5) was added in place of of compound (1), in the same manner as in Example 1 A thermoelectric conversion film and a thermoelectric conversion element were prepared and evaluated. The results are shown in Table 12.

Table 12

Reference Example 17
As an aqueous dispersion liquid of the conductive polymer, using a table 4 of the conductive polymer (1), except that the following compound (6) was added in place of of compound (1), in the same manner as in Example 1 A thermoelectric conversion film and a thermoelectric conversion element were prepared and evaluated. The results are shown in Table 13.

Table 13

Comparative Example 1
In Example 1, a thermoelectric conversion film and a thermoelectric conversion element were prepared and evaluated in the same manner as in Example 1 except that a conductive film was prepared using ethylene glycol instead of the compound (1) in Table 1. The results are shown in Table 14.

Table 14

As is apparent from Tables 5 to 13, the composition of the present invention obtained a higher ZT than the thermoelectric conversion film prepared in Comparative Example 1, and a result with high heat-resistant storage stability. . Table 5
As can be seen from FIG. 13, all the compositions of the present invention obtained a maximum output power higher than that of the thermoelectric conversion element prepared in Comparative Example 1.

As mentioned above, it turned out that the thermoelectric conversion composition containing the conductive polymer which is excellent in thermoelectric conversion performance and excellent in thermal stability is obtained by using the composition of this invention. Furthermore, it turned out that the thermoelectric conversion element which is excellent in thermoelectric conversion performance is obtained by using the composition of this invention.

Claims (4)

A thermoelectric conversion composition comprising a conductive polymer and any of the compounds represented by the following general formulas (1) to (3) .
The conductive polymer is a unit represented by the following general formula [2] and / or the following general formula [3
The thermoelectric conversion composition according to claim 1, comprising a unit represented by the following general formula [3a]:
General formula [2]


(Wherein R ¹ and R ² are independently of each other a hydrogen atom, a halogen atom, a substituted or unsubstituted aliphatic hydrocarbon group, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted fat, Heterocyclic group, substituted or unsubstituted aromatic heterocyclic group, cyano group, substituted or unsubstituted alkoxyl group, substituted or unsubstituted aryloxy group, substituted or unsubstituted alkylthio group, substituted or unsubstituted arylthio A group, a substituted amino group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkylsulfonyl group, or an arylsulfonyl group.)


(In the formula, R ³ and R ⁴ are independently of each other a hydrogen atom, a halogen atom, a substituted or unsubstituted aliphatic hydrocarbon group, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted fat, Heterocyclic group, substituted or unsubstituted aromatic heterocyclic group, cyano group, substituted or unsubstituted alkoxyl group, substituted or unsubstituted aryloxy group, substituted or unsubstituted alkylthio group, substituted or unsubstituted arylthio A group, a substituted amino group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkylsulfonyl group, or an arylsulfonyl group.)   The thermoelectric conversion film obtained using the thermoelectric conversion composition of Claim 1 or 2.   The thermoelectric conversion element obtained using the thermoelectric conversion composition of Claim 1 or 2.