JPWO2016068054A1 - Thermoelectric conversion element and thermoelectric conversion module - Google Patents

Abstract

By sandwiching the thermoelectric conversion layer with a substrate having a high heat conduction part and a low heat conduction part, a temperature difference is generated in the surface direction of the thermoelectric conversion layer, and the thermoelectric conversion layer contains a nanocarbon material and an organic acid. element. Accordingly, a thermoelectric conversion element having good thermoelectric conversion performance and excellent electrical stability, and a thermoelectric conversion module using the thermoelectric conversion element are provided.

Description

  The present invention relates to a thermoelectric conversion element and a thermoelectric conversion module. Specifically, the present invention relates to a thermoelectric conversion element and a thermoelectric conversion module that are excellent in thermoelectric conversion performance and electrical stability.

Thermoelectric conversion materials that can mutually convert thermal energy and electrical energy are used in thermoelectric conversion elements such as power generation elements and Peltier elements that generate electricity by heat.
The thermoelectric conversion element can convert heat energy directly into electric power, and has an advantage that a movable part is not required. For this reason, a thermoelectric conversion module (power generation device) formed by connecting a plurality of thermoelectric conversion elements is provided in a portion where heat is exhausted, such as an incinerator or various facilities in a factory, so that it is not necessary to incur operation costs and is simple. Can get power.

A thermoelectric conversion element generally has an electrode on a plate-like substrate, a thermoelectric conversion layer (power generation layer) on the electrode, and a plate-like electrode on the thermoelectric conversion layer. It has the composition which becomes. Such a thermoelectric conversion element is also called a uni leg type thermoelectric conversion element.
That is, in a normal thermoelectric conversion element, a thermoelectric conversion layer is sandwiched between electrodes in the thickness direction, a temperature difference is generated in the thickness direction of the thermoelectric conversion layer, and heat energy is converted into electric energy.

On the other hand, in Patent Documents 1 and 2, a temperature difference is caused in the surface direction of the thermoelectric conversion layer using a substrate having a high heat conduction portion and a low heat conduction portion, not in the thickness direction of the thermoelectric conversion layer. A thermoelectric conversion element that converts thermal energy into electrical energy is described.
Specifically, in Patent Document 1, a flexible film substrate composed of two types of materials having different thermal conductivities is provided on both surfaces of a thermoelectric conversion layer formed of a P-type material and an N-type material. A thermoelectric conversion element is described in which materials having different thermal conductivities are arranged on the outer surface of the substrate and at positions opposite to the energizing direction.

  Patent Document 2 discloses a sheet-like first insulating portion, a sheet-like second insulating portion, a first end portion for taking out a thermoelectromotive force accommodated between both insulating portions, and A plate-like thermoelectric conversion layer having a second end, and a first insulating portion that is disposed between the thermoelectric conversion layer and the first insulating portion and covers the first insulating portion side of the first end. Covering the second insulating portion side of the second end portion of the plate-like member, which is disposed between the first high thermal conductivity portion having a higher thermal conductivity than the plate-like member and the second insulating portion, An element having a second high thermal conductivity portion having a higher thermal conductivity than the second insulating portion is described.

  Such a thermoelectric conversion element generates a temperature difference in the surface direction of the thermoelectric conversion layer by a high heat conduction portion provided on the substrate, and converts the heat energy into electric energy. Therefore, even with a thin thermoelectric conversion layer, the distance at which the temperature difference occurs can be lengthened and efficient power generation can be performed. Furthermore, since the thermoelectric conversion layer can be formed into a sheet, a thermoelectric conversion module that is excellent in flexibility and easy to install on a curved surface or the like can be obtained.

Japanese Patent No. 3981738 JP 2011-35203 A

In a thermoelectric conversion element that uses a substrate having such a high heat conduction part and a low heat conduction part and generates a temperature difference in the surface direction of the thermoelectric conversion layer to convert thermal energy into electric energy, the thermoelectric conversion layer can be made thin. Hereinafter, such a thermoelectric conversion element is also referred to as an “in plane type thermoelectric conversion element”.
In consideration of this point, it is preferable that the in-plane type thermoelectric conversion element is formed with a thermoelectric conversion layer by using printing or a coating method in terms of productivity and cost. Furthermore, when the thermoelectric conversion layer is formed by printing or coating, it is preferable to use an organic material as the thermoelectric conversion material.

Nanocarbon materials such as carbon nanotubes and graphene are known as organic materials that can obtain good thermoelectric conversion characteristics.
Moreover, when forming a thermoelectric conversion layer using a nanocarbon material, in order to acquire favorable thermoelectric conversion performance, it is preferable to use a dopant (doping agent).

However, according to studies by the present inventors, when a thermoelectric conversion layer is formed using a nanocarbon material, sufficient thermoelectric conversion performance may not be obtained depending on the type of dopant.
Also, in-plane type thermoelectric conversion elements having a thermoelectric conversion layer made of doped nanocarbon material, even if good thermoelectric conversion performance is obtained, the stability of the resistance value of the element is low. In many cases, the performance is insufficient and the performance deteriorates with time. In addition, as a result of further studies on this point, the present inventors have found that an in-plane type thermoelectric conversion element having a thermoelectric conversion layer made of a doped nanocarbon material is electrically stable due to corrosion of the electrode by a dopant. It was also found that sex was impaired.

  An object of the present invention is to solve such problems of the prior art, and to use a substrate having a thermoelectric conversion layer made of a nanocarbon material and having a high heat conduction part and a low heat conduction part. Therefore, in the thermoelectric conversion element that generates a temperature difference in the surface direction of the thermoelectric conversion layer and converts the heat energy into electric energy, the thermoelectric conversion element has good thermoelectric conversion performance and is also excellent in electrical stability. And it is providing the thermoelectric conversion module using this thermoelectric conversion element.

In order to achieve this object, the thermoelectric conversion element of the present invention includes a substrate having a first high thermal conductivity portion having a thermal conductivity higher than that of other regions in at least a part of the surface direction,
A thermoelectric conversion layer containing a nanocarbon material and an organic acid, formed on the substrate;
A low thermal conductive layer formed on the thermoelectric conversion layer;
A second high thermal conductivity portion provided in the low thermal conductivity layer, having a thermal conductivity higher than that of the low thermal conductivity layer and not completely overlapping with the first high thermal conductivity portion in the plane direction;
A thermoelectric conversion element comprising a pair of electrodes connected to the thermoelectric conversion layer so as to sandwich the thermoelectric conversion layer in a plane direction is provided.

In such a thermoelectric conversion element of the present invention, the nanocarbon material is preferably a carbon nanotube.
The nanocarbon material is preferably a single-walled carbon nanotube.
The organic acid is preferably a carboxylic acid.
The organic acid is preferably an aromatic carboxylic acid.
Moreover, it is preferable that the boiling point of an organic acid is 200 degreeC or more.
Moreover, it is preferable that melting | fusing point of an organic acid is 100 degreeC or more.
The organic acid is preferably an organic acid polymer.
Furthermore, the organic acid polymer is preferably a polysaccharide or a derivative thereof.

  The thermoelectric conversion module of the present invention provides a thermoelectric conversion module formed by connecting a plurality of the thermoelectric conversion elements of the present invention in series.

  Such a thermoelectric conversion element and thermoelectric conversion module of the present invention have excellent thermoelectric conversion performance, and are excellent in electrical stability because corrosion of electrodes and the like can be prevented.

1A is a top view conceptually showing an example of the thermoelectric conversion element of the present invention, FIG. 1B is a front view conceptually showing an example of the thermoelectric conversion element of the present invention, and FIG. ) Is a bottom view conceptually showing an example of the thermoelectric conversion element of the present invention. 2A to 2C are conceptual diagrams for explaining another example of the thermoelectric conversion element of the present invention. FIG. 3A to FIG. 3D are conceptual diagrams for explaining an example of the thermoelectric conversion module of the present invention. FIG. 4A is a conceptual diagram showing another example of the substrate used in the thermoelectric conversion element of the present invention, and FIG. 4B shows another example of the substrate used in the thermoelectric conversion module of the present invention. It is a conceptual diagram. It is a conceptual diagram for demonstrating the thermoelectric conversion element produced in the Example of this invention.

Hereinafter, the thermoelectric conversion element and the thermoelectric conversion module of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.
In addition, in this specification, the numerical value range represented using "to" includes the numerical value described before and behind "to" as a lower limit and an upper limit.

  FIG. 1A to FIG. 1C conceptually show an example of the thermoelectric conversion element of the present invention. 1A is a top view, FIG. 1B is a front view, and FIG. 1C is a bottom view. The top view is a view of the thermoelectric conversion element as viewed from above the sheet of FIG. A front view is the figure which looked at the thermoelectric conversion element from surface directions, such as a substrate mentioned below. The bottom view is a view of the thermoelectric conversion element as viewed from the lower side of FIG. 1B.

As shown in FIGS. 1A to 1C, the thermoelectric conversion element 10 basically includes a first substrate 12, a thermoelectric conversion layer 16, an adhesive layer 18, a second substrate 20, The first electrode 26 and the second electrode 28 are included.
Specifically, the thermoelectric conversion layer 16 is formed on the surface of the first substrate 12. Further, on the surface of the first substrate 12, the first electrode 26 and the second electrode 28 (electrode pair) are connected to the thermoelectric conversion layer 16 so as to sandwich the thermoelectric conversion layer 16 in the substrate surface direction of the first substrate 12. It is formed. Furthermore, an adhesive layer 18 is provided so as to cover the first substrate 12, the thermoelectric conversion layer 16, the first electrode 26, and the second electrode 28, and the second substrate 20 is attached to the adhesive layer 18.
Hereinafter, the substrate surface direction of the first substrate 12 is also simply referred to as “surface direction”.

As shown in FIGS. 1A to 1C, the first substrate 12 includes a low thermal conductivity portion 12a and a high thermal conductivity portion 12b having a higher thermal conductivity than the low thermal conductivity portion 12a. Similarly, the 2nd board | substrate 20 also has the high heat conduction part 20b whose heat conductivity is higher than the low heat conduction part 20a and the low heat conduction part 20a. In the thermoelectric conversion element 10, the first substrate 12 is the substrate in the present invention, the high heat conduction portion 12b of the first substrate 12 is the first high heat conduction portion in the present invention, and the low heat conduction portion 20a of the second substrate 20 is the present invention. The high heat conduction portion 20b of the second substrate 20 corresponds to the second high heat conduction portion in the present invention.
In the thermoelectric conversion element 10, the two substrates are arranged such that their high heat conduction portions are located at different positions in the separation direction of the first electrode 26 and the second electrode 28. The separation direction between the first electrode 26 and the second electrode 28 is the energization direction.
The thermoelectric conversion element 10 has the 2nd board | substrate 20 stuck by the adhesion layer 18 as a preferable aspect, and also the 1st board | substrate 12 and the 2nd board | substrate 20 have both a low heat conduction part and a high heat conduction part. . The thermoelectric conversion element 10 has a configuration in which two substrates having a high heat conduction portion and a low heat conduction portion are used, and the high heat conduction portions of the two substrates are located at different positions in the plane direction, and the thermoelectric conversion layer is sandwiched between the two substrates. Have
That is, the thermoelectric conversion element 10 is the above-described in-plane type thermoelectric conversion element, and in the illustrated example, a substrate having a low thermal conductivity portion and a high thermal conductivity portion having higher thermal conductivity than the low thermal conductivity portion is used. Thus, a temperature difference can be generated in the surface direction of the thermoelectric conversion layer 16 to convert thermal energy into electric energy.

  In addition, the high heat conduction part or the low heat conduction part in the present invention indicates that the thermal conductivity is high or low with respect to an adjacent layer (adjacent high heat conduction part or low heat conduction part). The ratio of the thermal conductivity between the high heat conduction part and the low heat conduction part is preferably 100: 1 or more, more preferably 500: 1 or more, and still more preferably 1000: 1 or more.

  In the illustrated thermoelectric conversion element 10, the first substrate 12 and the second substrate 20 have the same configuration except for the arrangement position and the orientation of the front and back surfaces and the surface direction (substrate surface direction). Therefore, in the following description, the first substrate 12 will be described as a representative example, unless the first substrate 12 and the second substrate 20 need to be distinguished.

In the illustrated thermoelectric conversion element 10, the first substrate 12 (second substrate 20) covers a region on one half of one surface of the plate-like material that becomes the low thermal conduction portion 12 a (low thermal conduction portion 20 a). It has a configuration in which the high heat conduction part 12b (high heat conduction part 20b) is laminated. In other words, in the first substrate 12, the high thermal conductivity portion 12 b is provided so as to cover the low thermal conductivity portion 12 a, that is, the half surface of the first substrate 12.
Accordingly, on one surface of the first substrate 12, a half region in the surface direction is the low heat conduction portion 12a, and the other half region is the high heat conduction portion 12b. In addition, the other surface of the first substrate 12 is the low thermal conductive portion 12a. In the thermoelectric conversion element 10, the surface of the first substrate 12 on the side where the high heat conduction portion 12 b of the low heat conduction portion 12 a is not formed becomes the formation surface of the thermoelectric conversion layer 16.

  In addition, in the thermoelectric conversion element of this invention, the 1st board | substrate 12 can utilize various structures other than the structure formed by laminating | stacking a high heat conduction part on the surface of a low heat conduction part. For example, as conceptually shown in FIG. 4 (A), the first substrate has a concave portion formed in a half region of one surface of the plate-like material that becomes the low heat conducting portion 12a, The structure which incorporates the high heat conductive part 12b so that may become uniform may be sufficient.

The low heat conduction part 12a has insulation properties such as a film made of a resin material (polymer material) such as a glass plate, a ceramic plate, and a plastic film, and is suitable for the formation of the thermoelectric conversion layer 16, the first electrode 26, and the like. Any material having various heat resistances can be used as long as it has sufficient heat resistance.
Preferably, a film made of a resin material is used for the low thermal conductive portion 12a. By using a film (sheet-like / plate-like) made of a resin material for the low thermal conductive portion 12a, it is possible to reduce the weight and cost and to form the thermoelectric conversion element 10 having flexibility, which is preferable.

Specific examples of the resin material that can be used for the low thermal conductive portion 12a include polyethylene terephthalate, polyethylene isophthalate, polyethylene naphthalate, polybutylene terephthalate, poly (1,4-cyclohexylenedimethylene terephthalate), polyethylene-2, Polyester resins such as 6-phthalenedicarboxylate, polyimide, polycarbonate, polypropylene, polyethersulfone, cycloolefin polymer, polyetheretherketone (PEEK), triacetylcellulose (TAC) resin, glass epoxy, liquid crystalline polyester, etc. Is exemplified.
Among them, a film made of polyimide, polyethylene terephthalate, polyethylene naphthalate, or the like is suitably used in terms of thermal conductivity, heat resistance, solvent resistance, availability, economy, and the like.

As long as the high heat conductive part 12b has a heat conductivity higher than the low heat conductive part 12a, the film and metal foil which consist of various materials are illustrated.
Specifically, various metals such as gold, silver, copper, and aluminum are exemplified in terms of thermal conductivity and the like. Among these, copper and aluminum are preferably used in terms of thermal conductivity, economy, and the like.

In the present invention, the thickness of the first substrate 12, the thickness of the low thermal conductive portion 12a, the thickness of the high thermal conductive portion 12b, etc. are the same as the forming material of the high thermal conductive portion 12b and the low thermal conductive portion 12a. What is necessary is just to set suitably according to a magnitude | size. In addition, the thickness of the 1st board | substrate 12 is the thickness of the low heat conductive part 12a of the area | region which does not have the high heat conductive part 12b. According to the study by the present inventors, the thickness of the first substrate 12 is preferably 2 to 100 μm, and more preferably 2 to 50 μm.
In addition, the size in the surface direction of the first substrate 12, the area ratio in the surface direction of the high heat conduction portion 12 b in the first substrate 12, and the like are the material for forming the low heat conduction portion 12 a and the high heat conduction portion 12 b, and the size of the thermoelectric conversion element 10. What is necessary is just to set suitably according to this. The size and area ratio in the surface direction are the size and area ratio when viewed from the direction orthogonal to the substrate surface.

Furthermore, the position of the first substrate 12 in the surface direction of the high thermal conductive portion 12b is not limited to the illustrated example, and various positions can be used.
For example, in the 1st board | substrate 12, the high heat conductive part 12b may be included in the low heat conductive part 12a in the surface direction. Alternatively, a part of the high heat conduction unit 12b may be located at the end of the first substrate 12 in the plane direction, and the other region may be included in the low heat conduction unit 12a.
Further, the first substrate 12 may have a plurality of high heat conducting portions 12b in the surface direction.

In addition, the thermoelectric conversion element 10 shown to FIG. 1 (A)-FIG.1 (C) is the 1st board | substrate 12 and the 1st board | substrate as a preferable aspect which tends to produce the temperature difference between the 1st board | substrate 12 and the 2nd board | substrate 20. In the two substrates 20, the high heat conduction part 12 b and the high heat conduction part 20 b are both positioned outside in the stacking direction.
However, the present invention may have a configuration in which the first substrate 12 and the second substrate 20 both have the high heat conduction portion 12b and the high heat conduction portion 20b located inside in the stacking direction. Alternatively, the first substrate 12 may be configured such that the high heat conductive portion 12b is positioned outside in the stacking direction, and the second substrate 20 is positioned such that the high heat conductive portion 20b is positioned inside in the stacking direction.
In the configuration in which the high heat conduction part is formed of a conductive material such as metal and the high heat conduction part is disposed inside the stacking direction, the high heat conduction part, the first electrode 26, the second electrode 28, and In a case where at least one of the thermoelectric conversion layers 16 is electrically connected, in order to ensure insulation between the high heat conduction portion and at least one of the first electrode 26, the second electrode 28, and the thermoelectric conversion layer 16. In addition, an insulating layer may be provided therebetween.

In the thermoelectric conversion element 10, the thermoelectric conversion layer 16 is formed on the surface where the entire surface of the first substrate 12 is the low thermal conductive portion 12 a.
In addition, the second substrate 20 is provided on the thermoelectric conversion layer 16 via the adhesive layer 18. The second substrate 20 is provided with the surface of the low heat conductive portion 20 a on which the high heat conductive portion 20 b is not formed facing the thermoelectric conversion layer 16.
The high thermal conductive portions 12b and 20b of both the substrates are arranged so as to efficiently generate a temperature difference in the surface direction of the thermoelectric conversion layer 16. That is, it is preferable that the high heat conductive portions 12b and 20b of both the substrates are arranged at different positions in the plane direction with respect to the thermoelectric conversion layer 16, and the boundary between the low heat conductive portion and the high heat conductive portion of both the substrates is More preferably, the conversion layer 16 is provided so as to coincide with the center of the surface direction, and it is further preferable that the boundary is spaced apart in the electrode separation direction.
The thermoelectric conversion layer 16 is connected to an electrode pair including the first electrode 26 and the second electrode 28 so as to be sandwiched in the surface direction.

For example, a thermoelectric conversion element generates a temperature difference due to heating due to contact with a heat source or the like, and accordingly, in the thermoelectric conversion layer, a difference occurs in the carrier density in the direction of the temperature difference in accordance with the temperature difference. Will occur.
For example, a heat source is provided on the first substrate 12 side, and a temperature difference is generated between the high heat conductive portion 12b of the first substrate 12 and the high heat conductive portion 20b of the second substrate 20, thereby causing the inside of the thermoelectric conversion layer 16 to be inside. Therefore, a difference occurs in the carrier density in the direction of the temperature difference, and power is generated. Further, by connecting wiring to the first electrode 26 and the second electrode 28, electric power (electric energy) generated by heating is taken out.

In the thermoelectric conversion element 10 of the present invention, the thermoelectric conversion layer 16 contains a nanocarbon material such as carbon nanotube or graphene, and an organic acid. Hereinafter, the carbon nanotube is also referred to as “CNT”.
In the thermoelectric conversion element 10 of the present invention, the thermoelectric conversion layer 16 contains a nanocarbon material and an organic acid, so that it has good thermoelectric conversion performance and also prevents corrosion of the first electrode 26, the second electrode 28, and the like. Thus, the thermoelectric conversion element 10 having excellent electrical stability is realized. In the present invention, the electrical stability is the temporal stability of the resistance of the thermoelectric conversion element 10.

As described above, an in-plane type thermoelectric conversion element that performs thermoelectric conversion by generating a temperature difference in the surface direction of the thermoelectric conversion layer using a substrate having a high heat conduction portion and a low heat conduction portion is provided with a thermoelectric conversion layer. Can be thin. Therefore, in consideration of productivity and cost, it is advantageous to form the thermoelectric conversion layer by a printing method or a coating method.
An organic material can be considered as a thermoelectric conversion material suitable for forming a thermoelectric conversion layer by a printing method or a coating method. Among these, nanocarbon materials such as CNT and graphene are known as materials having good thermoelectric conversion characteristics.

When a nanocarbon material is used for the thermoelectric conversion layer, doping is preferably performed. Further, it is well known that an acid is used as a dopant in a semiconductor device.
However, according to the study by the present inventors, when a nanocarbon material is used for the thermoelectric conversion layer, the thermoelectric conversion performance cannot often be improved depending on the type of dopant, and a good thermoelectric property can be obtained. Even if conversion performance is obtained, the electrical stability of the thermoelectric conversion element is often low due to corrosion of the electrode.

On the other hand, according to the study by the present inventors, by using an organic acid, particularly a carboxylic acid, as a dopant, the organic acid functions as a proton acid (p-type dopant) having a low acidity, thereby providing conductivity. Can be improved.
In addition, the organic acid tends to stay on the surface of the nanocarbon material and functions as a weak potential receiving layer on the surface of the nanocarbon material. Therefore, by using an organic acid as a dopant, the thermal excitation efficiency at the interface of the nanocarbon material is promoted to improve the thermal power, and as a result, high thermoelectric conversion performance is obtained. Furthermore, in the thermoelectric conversion element, the electric conductivity of the thermoelectric conversion layer and the thermoelectromotive force are in a trade-off relationship, but organic acids, particularly carboxylic acids, especially aromatic carboxylic acids or organic carboxylic acid polymers are used as dopants. By using, it is possible to obtain both conductivity and thermoelectromotive force by the action mechanism.
In addition, the organic acid has low acidity and remains on the surface of the nanocarbon material as described above. Therefore, the corrosion of the electrode, which is low in corrosivity and causes an increase in resistance, can be prevented, so that a thermoelectric conversion element with good electrical stability can be obtained.

As described above, in the thermoelectric conversion element 10 of the present invention, the thermoelectric conversion layer 16 contains a nanocarbon material and an organic acid.
Specific examples of the nanocarbon material include CNT, carbon nanofiber, graphite, graphene, and carbon nanoparticle. These may be used alone or in combination of two or more.
Among these, CNT is preferably used for the reason that the thermoelectric characteristics are better.

A CNT is 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 graphene sheets in a concentric circle There are multi-walled CNTs wound in a shape. 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 composition can be appropriately adjusted according to the use of the composition. The CNT may contain a metal or the like, or may contain a molecule such as fullerene.

  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. Specifically, although it depends on the distance between the electrodes, the average length of the CNT is preferably 0.01 to 2000 μm, more preferably 0.1 to 1000 μm from the viewpoints of manufacturability, film formability, conductivity, and the like. 1 to 1000 μm is particularly preferable.

Although the diameter of CNT used by this invention is not specifically limited, From viewpoints of durability, transparency, film-forming property, electroconductivity, etc., 0.4-100 nm is preferable, 50 nm or less is more preferable, and 15 nm or less is especially preferable.
In particular, when single-walled CNT is used, 0.5 to 2.2 nm is preferable, and 1.0 to 2.2 nm is more preferable.

  CNTs contained in the obtained conductive composition may contain defective CNTs. Such CNT defects are preferably reduced in order to reduce the conductivity of the composition. The amount of CNT defects in the composition can be estimated by the ratio G / D of the G-band and D-band of the Raman spectrum. It can be estimated that the higher the G / D ratio, the less the amount of defects, the CNT material. In the present invention, the G / D ratio of the composition is preferably 10 or more, and more preferably 30 or more.

Also, CNTs modified or treated with CNTs can be used. Modification or treatment methods include a method of including a ferrocene derivative or nitrogen-substituted fullerene (azafullerene), a method of doping an alkali metal (such as potassium) or a metal element (such as indium) into the CNT by an ion doping method, or CNT in a vacuum. The method etc. which heat this are illustrated.
When CNT is used, in addition to single-walled CNT and multi-walled CNT, nanocarbon such as carbon nanohorn, carbon nanocoil, carbon nanobead, graphite, graphene, and amorphous carbon may be included.

As described above, the thermoelectric conversion layer 16 includes an organic acid in addition to such a nanocarbon material.
Organic acid is a general term for organic compounds that exhibit acidity, and specifically includes carboxylic acid, sulfonic acid, sulfinic acid, sulfenic acid, phenol, enol, thiol, phosphonic acid, phosphoric acid, boronic acid, imidoic acid. , A low molecular organic acid compound having a functional group showing acidity, such as hydrazone acid, hydroxymic acid, hydroxysamic acid, etc., a low molecular organic acid compound having at least one functional group showing hydrophobicity and a hydrophobic group, or An organic acid polymer having at least one functional group showing acidity in the molecule and having a repeating unit structure. Hereinafter, the functional group showing acidity is also referred to as “acidic functional group”.
The acidic functional group may have any known structure, for example, carboxyl group, thiocarboxyl group, dithiocarboxyl group, mercaptocarbonyl group, hydroperoxy group, sulfo group, sulfino group, sulfeno group, phenolic hydroxyl group, Examples include a thiol group, a phosphate group, a phosphinico group, a phosphono group, a selenono group, a selenino group, a seleneno group, an arsinico group, an arsono group, a boronic acid group, and a boranoic acid group. Among these acidic functional groups, a carboxyl group, a phosphate group, a sulfo group, a thiol group, a phenolic hydroxyl group, and a boronic acid group are more excellent in the effect of the present invention that thermoelectric conversion performance and / or electrical stability is high. Is more preferable, and a carboxyl group is more preferable.

The number of acidic functional groups contained in the organic acid is not particularly limited as long as at least one acidic functional group is contained per molecule of the organic acid, but a plurality of acidic functional groups may be contained. The preferred range of the number of acidic functional groups in the organic acid is preferably 1-10, more preferably 1-6.
When a plurality of acidic functional groups are included in one organic acid molecule, the plurality of acidic functional groups may be the same or different from each other.

  In the present invention, the organic acid includes so-called anhydrides (organic acid anhydrides). An organic acid anhydride is a compound having a bond in which two acyl groups share an oxygen atom.

As described above, the organic acid may be an organic acid polymer having at least one acidic functional group in the molecule and a repeating unit structure. Examples of the organic acid polymer include polyvinyl sulfonic acid, polyvinyl phosphonic acid, polystyrene sulfonic acid, styrene / styrene phosphonic acid copolymer, polylactic acid, carboxymethyl cellulose, carboxyethyl cellulose, xanthan gum, carrageenan, pectin, polygalacturonic acid, alginic acid, Examples thereof include chondroitin sulfate, dermatan sulfate, heparan sulfate, hyaluronic acid, keratan sulfate, mucoitin sulfate, caronic acid, carrageenan, carboxymethyl chitin, carboxyvinyl polymer, polyacrylic acid, and acrylic acid / alkyl methacrylate copolymer. Moreover, what modified polysaccharide, protein, a synthetic polymer, etc. with acidic groups, such as a carboxy group, a carboxyalkyl group, a sulfo group, and a phosphate group is also contained. A part or all of the acidic groups of the polymer may be a salt such as a sodium salt, a potassium salt, or an ammonium salt.
Although there is no restriction | limiting in particular in the weight average molecular weight of the organic acid polymer used for this invention, 5000-10,000,000 are preferable and 10,000-5,000,000 are more preferable. In the present invention, the weight average molecular weight may be measured by gel permeation chromatography (GPC).

The boiling point of the organic acid is not particularly limited, but in consideration of handleability and use as a thermoelectric conversion element, it is preferably 200 ° C. or higher, and the effect of the present invention that thermoelectric conversion performance and / or electrical stability is high is more excellent. In this respect, 220 ° C. or higher is more preferable.
This boiling point is intended to be a boiling point at 1 atmosphere, and is measured by, for example, an atmospheric pressure distillation test method according to JIS 2254, and the initial boiling point is used as the boiling point.
The melting point of the organic acid is not particularly limited, but it is preferably a solid acid in consideration of the use as a thermoelectric conversion element, and is preferably 100 ° C. or higher, more preferably 110 ° C. or higher, from the viewpoint of handleability, and thermoelectric conversion 120 degreeC or more is further more preferable at the point which the effect of this invention that performance and / or electrical stability are high is more excellent. The upper limit is not particularly limited, but is preferably 300 ° C. or less from the viewpoint of handleability.
The melting point was measured according to JIS-0064, for example, using a differential scanning calorimeter manufactured by Perkin Elmer, product name: DSC7, and 10 mg of a sample was heated and melted under a nitrogen stream at a flow rate of 50 mL / min. After solidifying by cooling at a rate of 10 ° C./min, the melting peak temperature when the temperature is subsequently increased at a rate of 10 ° C./min is used.

The low molecular organic acid is preferably represented by the following general formula (1) in that the effect of the present invention that thermoelectric conversion performance and / or electrical stability is high is more excellent.
(A) mR- (B) n General formula (1)
In the general formula (1), A represents one or more selected from a carboxyl group, a sulfo group, and a phosphate group, and is preferably a carboxyl group. A plurality of A may be the same or different.
In the general formula (1), B represents one or more selected from an alkyl group having 1 to 6 carbon atoms, an alkenyl group, an alkyl ether group, and a hydroxyl group, and 1 selected from an alkyl group, an alkyl ether group, and a hydroxyl group. The above is preferable. A plurality of B may be the same or different.
In general formula (1), R represents an m + n-valent aliphatic group having 1 to 10 carbon atoms or an m + n-valent aromatic group having 6 to 20 carbon atoms, and an m + n-valent aliphatic group having 1 to 6 carbon atoms or It is preferably an m + n-valent aromatic group having 6 to 16 carbon atoms, more preferably an m + n-valent aromatic group having 6 to 16 carbon atoms, and an m + n-valent aromatic group having 6 to 10 carbon atoms. More preferably. When R is an m + n-valent aliphatic group, the aliphatic group may have a linear structure, a branched structure, or a cyclic structure. When R is an m + n-valent aromatic group, the aromatic group may be a monocyclic structure or a polycyclic structure.
In the general formula (1), some or all of the hydrogen atoms of B and R are other atoms (for example, fluorine atom, chlorine atom, bromine atom, iodine atom, etc.) or functional groups (for example, hydroxyl group, amino group) , A mercapto group, a cyano group, a perfluoro group, etc.).
In the general formula (1), m represents an integer of 1 or more, preferably an integer of 1 to 5, more preferably an integer of 1 to 3, and further preferably 1 or 2.
In the general formula (1), n represents an integer of 0 or more, preferably an integer of 0 to 2, and more preferably an integer of 0 to 1.

Hereinafter, the carboxylic acid (compound having a carboxyl group) will be described in detail.
Examples of the carboxylic acid include aliphatic carboxylic acids (aliphatic carboxylic acid compounds) and aromatic carboxylic acids (aromatic carboxylic acid compounds), and aromatic carboxylic acids are more preferable.
Although the number of carboxyl groups contained in the carboxylic acid is not particularly limited, 1 to 6 is preferable, and 1 to 3 is preferable in that the effect of the present invention that thermoelectric conversion performance and / or electrical stability is high is more excellent. More preferred.
Examples of aliphatic carboxylic acids include monocarboxylic acids, dicarboxylic acids, and tricarboxylic acids. Examples of monocarboxylic acids include formic acid, acetic acid, valeric acid, glycolic acid, lactic acid, propionic acid, cyclohexanecarboxylic acid, and deoxycholic acid. , Cholic acid, lithocholic acid, dihydroabietic acid, abietic acid, neoabietic acid, parastrinic acid, levopimaric acid, dihydroabietic acid, tetrahydroabietic acid, etc., and dicarboxylic acids include oxalic acid, malonic acid, succinic acid, Examples thereof include tartaric acid, malic acid, maleic acid, fumaric acid, dichlorohexanedicarboxylic acid, and examples of tricarboxylic acid include citric acid.
The aromatic carboxylic acid is a compound in which one or more carboxyl groups (—COOH) are directly bonded to the aromatic ring (Ar). As an aromatic ring, well-known aromatic rings, such as a benzene ring, a naphthalene ring, a pyrene ring, are mentioned, A monocyclic structure or a polycyclic structure may be sufficient. In addition, the aromatic ring may be substituted with a functional group other than the carboxyl group (for example, a hydroxyl group, an alkyl group, etc.).
Examples of the aromatic carboxylic acid include benzoic acid, salicylic acid, p-hydroxybenzoic acid, o-, m-, or p-toluic acid, o-, m-, or p-methoxybenzoic acid, 1-naphthoic acid, Aromatic monocarboxylic acids such as 1-pyrenecarboxylic acid and pyrenebutanoic acid; aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid; and aromatic tricarboxylic acids such as trimesic acid.
As the carboxylic acid, derivatives and salts of these compounds can also be used.

In the present invention, sulfonic acid (a compound having a sulfo group) is also preferably used as the organic acid.
Examples of the sulfonic acid include aliphatic sulfonic acid (octylsulfonic acid, decylsulfonic acid), benzenesulfonic acid, alkylbenzenesulfonic acid (toluenesulfonic acid, xylenesulfonic acid, dodecylbenzenesulfonic acid), naphthalenesulfonic acid, alkylnaphthalenesulfonic acid ( Methyl naphthalene sulfonic acid, dodecyl naphthalene sulfonic acid), polyoxyalkylene alkyl ether sulfonic acid and the like.
As the sulfonic acid, derivatives and salts of these compounds can also be used.

Furthermore, in the present invention, phosphoric acid (compound having a phosphoric acid group) is also preferably used as the organic acid.
Examples of phosphoric acid include phenylphosphonic acid, methylphenylphosphonic acid, decylphosphonic acid, and methylenediphosphonic acid. Derivatives and salts of these compounds can also be used.

Although there is no restriction | limiting in particular in content of the organic acid in the thermoelectric conversion layer 16, 0.001-20 are preferable with the mass ratio of organic acid / nanocarbon material, 0.005-10 are more preferable, 0.01-5 Is more preferable.
By making the content of organic acid 0.001 or more by mass ratio of organic acid / nanocarbon material, it is preferable in that the effect of adding organic acid is sufficiently obtained and high thermoelectric conversion performance is obtained. .
In addition, when the organic acid content is 20 or less in terms of the mass ratio of organic acid / nanocarbon material, a thermoelectric conversion element with higher electrical stability can be obtained, and wiring corrosion can be more suitably prevented. Is preferable.

In the thermoelectric conversion element 10 of the present invention, the thermoelectric conversion layer 16 may contain a resin material as a binder, if necessary.
Various known non-conductive resin materials (polymers) can be used as the resin material.
Specifically, various known resin materials such as vinyl compounds, (meth) acrylate compounds, carbonate compounds, ester compounds, epoxy compounds, siloxane compounds, and gelatin can be used.
More specifically, examples of the vinyl compound include polystyrene, polyvinyl naphthalene, polyvinyl acetate, polyvinyl phenol, and polyvinyl butyral. Examples of the (meth) acrylate compound include polymethyl (meth) acrylate, polyethyl (meth) acrylate, polyphenoxy (poly) ethylene glycol (meth) acrylate, polybenzyl (meth) acrylate and the like. Examples of the carbonate compound include bisphenol Z-type polycarbonate and bisphenol C-type polycarbonate. As the ester compound, amorphous polyester is exemplified.
Preferred examples include polystyrene, polyvinyl butyral, (meth) acrylate compounds, carbonate compounds and ester compounds, and more preferred are polyvinyl butyral, polyphenoxy (poly) ethylene glycol (meth) acrylate, polybenzyl (meth) acrylate, and amorphous. An example is a reactive polyester.

In the thermoelectric conversion layer 16 in which the thermoelectric conversion material is dispersed in the resin material, the content of the resin material in the thermoelectric conversion layer 16 is determined depending on the material used, the required thermoelectric conversion efficiency, the viscosity of the solution and the solid content concentration affecting printing. It may be set as appropriate according to the above.
Specifically, the content of the resin material is preferably 0.5 to 10, more preferably 0.5 to 5, and still more preferably 1 to 4 in terms of the mass ratio of the resin material / nanocarbon material.
By setting the content of the resin material to 0.5 or more by mass ratio with the nanocarbon material, it is preferable in terms of shape retention property, economic efficiency, and the like of the thermoelectric conversion layer 16.
Moreover, it is preferable at the point that the electroconductivity is made high and the thermoelectric conversion element with higher thermoelectric conversion performance is obtained by making content of a resin material into 10 or less by mass ratio with a nanocarbon material.

In the thermoelectric conversion element 10 of the present invention, the thermoelectric conversion layer 16 may contain a surfactant as necessary.
As the surfactant, any known surfactant can be used as long as it has a function of dispersing a nanocarbon material such as CNT. More specifically, various surfactants can be used as long as they have a group that dissolves in water, a polar solvent, or a mixture of water and a polar solvent and adsorbs CNTs.
Accordingly, the surfactant may be ionic or nonionic. The ionic surfactant may be any of cationic, anionic and amphoteric.
Examples of the anionic surfactant include alkylbenzene sulfonates such as dodecylbenzene sulfonic acid, aromatic sulfonic acid surfactants such as dodecyl phenyl ether sulfonate, monosoap anionic surfactants, ether sulfates Surfactants, phosphate surfactants and carboxylic acid surfactants such as sodium deoxycholate and sodium cholate, carboxymethylcellulose and salts thereof (sodium salt, ammonium salt, etc.), ammonium polystyrene sulfonate, Examples thereof include water-soluble polymers such as polystyrene sulfonate sodium salt.
Examples of the cationic surfactant include alkylamine salts and quaternary ammonium salts. Examples of amphoteric surfactants include alkylbetaine surfactants and amine oxide surfactants.
Furthermore, nonionic surfactants include sugar ester surfactants such as sorbitan fatty acid esters, fatty acid ester surfactants such as polyoxyethylene resin acid esters, ether surfactants such as polyoxyethylene alkyl ethers, etc. Is exemplified.
Among these, ionic surfactants are preferably used, and among them, cholate and deoxycholate are preferably used.

When the thermoelectric conversion layer 16 contains a surfactant, the content is preferably low. Specifically, the surfactant / nanocarbon material mass ratio is preferably 5 or less, more preferably 2 or less.
By setting the content of the surfactant to 5 or less by mass ratio with the nanocarbon material, it is preferable in that higher thermoelectric conversion performance can be obtained.

  In addition, the thermoelectric conversion layer 16 mainly composed of CNT and a surfactant may have an antifoaming agent, a drying inhibitor, a fungicide, and the like as necessary.

  In the thermoelectric conversion element 10 of the present invention, the thickness of the thermoelectric conversion layer 16, the size in the surface direction, the area ratio in the surface direction with respect to the substrate, etc. Accordingly, it may be set appropriately.

In the example shown in FIGS. 1A to 1C, the thermoelectric conversion layer 16 has a rectangular parallelepiped shape, but in the thermoelectric conversion element of the present invention, various shapes can be used for the thermoelectric conversion layer 16. is there.
For example, the thermoelectric conversion layer may have a quadrangular pyramid shape or the like. Alternatively, it may be a columnar shape, a prism shape other than a square shape, a truncated cone, a truncated pyramid, an indefinite shape, or the like.

A first electrode 26 and a second electrode 28 are provided on the surface of the first substrate 12 so as to sandwich the thermoelectric conversion layer 16 in the surface direction.
In the thermoelectric conversion element 10, the first electrode 26 and the second electrode 28 rise from the first substrate 12 at the end of the thermoelectric conversion layer 16, as shown in FIGS. The thermoelectric conversion layer 16 has a shape extending from the side surface to the vicinity of the end of the upper surface.

In addition, in the thermoelectric conversion element of this invention, the shape of the 1st electrode 26 and the 2nd electrode 28 is not limited to the shape shown by FIG. 1 (A)-FIG. Various shapes can be used as long as they are connected to the conversion layer 16.
For example, as conceptually shown in FIG. 2A, the end portions of the plate-like first electrode 30 and the second electrode 32 formed on the surface of the first substrate 12 are connected to the thermoelectric conversion layer 16. The structure which covers may be sufficient. The configuration shown in FIG. 1B and the like can be manufactured by forming the first electrode 26 and the second electrode 28 after forming the thermoelectric conversion layer on the surface of the first substrate 12. On the other hand, the configuration shown in FIG. 2A can be manufactured by forming the thermoelectric conversion layer 16 after first forming the first electrode 30 and the second electrode 32 on the surface of the first substrate 12. .
Further, as conceptually shown in FIG. 2 (B), the structure shown in FIG. 2 (A) is further connected to the first electrode 30 and the second electrode 32, and from the side surface of the thermoelectric conversion layer 16 to the upper surface. The structure which has the auxiliary electrodes 30a and 32a which contact | connects to the edge part vicinity may be sufficient.
Further, as conceptually shown in FIG. 2C, the first electrode 34 and the second electrode 36 may be in contact with the side surface of the thermoelectric conversion layer 16.

The first electrode 26 and the second electrode 28 can be formed of various materials as long as they have a necessary conductivity.
Specifically, various materials such as copper, silver, gold, platinum, nickel, aluminum, constantan, chromium, indium, iron, copper alloy, and other devices such as indium tin oxide (ITO) and zinc oxide (ZnO) Examples include materials used as transparent electrodes. Among these, copper, gold, silver, platinum, nickel, copper alloy, aluminum, constantan and the like are preferably exemplified, and copper, gold, silver, platinum and nickel are more preferably exemplified.

  In addition, the thickness, size, shape, and the like of the first electrode 26 and the second electrode 28 may be appropriately set according to the thickness, size, shape, the size of the thermoelectric conversion element 10, etc. of the thermoelectric conversion layer 16. Good.

  The thermoelectric conversion element 10 of the illustrated example has an adhesive layer 18 on the first substrate 12 so as to cover the thermoelectric conversion layer 16 and the first electrode 26 and the second electrode 28, and the adhesive substrate 18 includes the second substrate 20. Is pasted.

The forming material of the adhesive layer 18 is affixed according to the forming material of the first substrate 12 (low heat conduction part 12a), the second substrate 20 (low heat conduction part 20a), the first electrode 26 and the second electrode 28, and the like. A variety of wearable items are available.
Specific examples include acrylic resins, urethane resins, silicone resins, epoxy resins, rubber, EVA (Ethylene Vinyl Acetate Copolymer), α-olefin polyvinyl alcohol, polyvinyl butyral, polyvinyl pyrrolidone, gelatin, starch, and the like. Moreover, you may form the adhesion layer 18 using a commercially available double-sided tape and an adhesive film.

  The thickness of the adhesive layer 18 is such that sufficient adhesion can be obtained according to the forming material of the adhesive layer 18, the forming material and size of the first substrate 12 and the second substrate 20, and the thermoelectric conversion layer 16. What is necessary is just to set suitably the thickness which can fill the level | step difference resulting from.

  In addition, the thermoelectric conversion element of this invention makes the thermoelectric conversion layer, the 1st electrode, and the 2nd electrode the same height, and does not use an adhesion layer, but on the thermoelectric conversion layer, the 1st electrode, and the 2nd electrode. The second substrate may be laminated, and the first substrate, the thermoelectric conversion layer, the first electrode, the second electrode, and the second substrate may be fixed to each other by a known method. The fixing method at this time may be self-adhesion of each member.

In the illustrated thermoelectric conversion element 10, the high thermal conductive portion 12 b of the first substrate 12 and the high thermal conductive portion 20 b of the second substrate 20 face each other in the inter-electrode direction and abut the end portions thereof. Arranged at different positions.
In addition to this, various configurations can be used for the thermoelectric conversion element of the present invention.
For example, in the example shown in FIGS. 1A to 1C, the high heat conduction portion 12b of the first substrate 12 is moved to the right side in the drawing, and the high heat conduction portion 20b of the second substrate 20 is moved to the left side in the drawing. Then, in the surface direction, both high heat conducting portions may be separated in the inter-electrode direction. Specifically, the high heat conductive portion 12b of the first substrate 12 and the high heat conductive portion 20b of the second substrate 20 are in the plane direction of the thermoelectric conversion layer 16 in the direction in which the first electrode 26 and the second electrode 28 are separated from each other. The size is preferably 10% to 90% apart, more preferably 10% to 50% apart in the direction between the electrodes.
On the other hand, in the example shown in FIGS. 1A to 1C, the high heat conduction portion 12b of the first substrate 12 is moved to the left side in the drawing, and the high heat conduction portion 20b of the second substrate 20 is moved to the right side in the drawing. By moving, a part of the high thermal conductivity portions of both substrates may overlap in the plane direction.

Alternatively, a circular high heat conduction portion is formed on the first substrate, a square high heat conduction portion of the same size is formed on the second substrate, and both the substrates are arranged so that the centers of both high heat conduction portions coincide in the plane direction. You may arrange. Even in this configuration, although the distance is short, since the end (periphery) positions of the two high heat conducting portions are different in the surface direction, a temperature difference in the surface direction is generated in the thermoelectric conversion layer, and a temperature difference is generated in the thickness direction. Efficient power generation is possible compared to thermoelectric conversion elements. In addition, the circle and square of the same size are a circle and a square in which the diameter and the length of one side coincide.
That is, in the present invention, various configurations can be used for the first substrate and the second substrate as long as the high thermal conductivity portions do not completely overlap in the plane direction between the first substrate and the second substrate. In other words, when the first substrate and the second substrate are viewed from the direction perpendicular to the substrate surface, various configurations can be used as long as the high thermal conductivity portions of the first substrate and the second substrate do not completely overlap. is there.

  In the thermoelectric conversion element of the present invention, the low heat conduction layer and the second high heat conduction part are not limited to the low heat conduction part 20a and the high heat conduction part 20b constituting the second substrate 20, and the low heat conduction layer and the low heat conduction layer Provided with a second high thermal conductivity portion that has a higher thermal conductivity than the low thermal conductivity layer, and the first high thermal conductivity portion and the second high thermal conductivity portion do not completely overlap in the plane direction. Configuration is available. In other words, the low thermal conductivity layer and the second high thermal conductivity portion include the low thermal conductivity layer provided with the second high thermal conductivity portion and having a lower thermal conductivity than the high thermal conductivity portion, and the first high thermal conductivity portion and the first high thermal conductivity portion Various configurations can be used as long as the two high heat conducting portions do not completely overlap in the surface direction.

For example, an insulating layer (insulating layer) may be formed on the adhesive layer 18 as a low thermal conductive layer, and a second high thermal conductive portion similar to the high thermal conductive portion 20b described above may be provided thereon.
At this time, the insulating layer may be formed by a known method. As an example, a method of forming an insulating layer made of an insulating material such as a resin by a coating method or sticking a film (sheet), a method of forming an insulating layer by vapor deposition of a metal oxide, or the like is exemplified.

Further, in the configuration shown in FIG. 2C, the first electrode 34 and the second electrode 36 having a thickness that does not cause a step with respect to the thermoelectric conversion layer 16 are formed, and this thermoelectric conversion layer 16 is not provided with an adhesive layer. An insulating layer may be formed on the first electrode 34 and the second electrode 36 in the same manner as described above, and a second high heat conductive portion similar to the high heat conductive portion 20b may be provided on the insulating layer. .
Alternatively, in the configuration shown in FIG. 1A to FIG. 1C and the like, the adhesive layer 18 is not provided, and the thermoelectric conversion layer 16 and the first electrode 26 and the second electrode 28 are covered, and a step is formed. An insulating layer may be formed in the same manner as described above so as to be buried, and a second high heat conductive portion similar to the high heat conductive portion 20b may be provided on the insulating layer.

Furthermore, in the example shown in FIGS. 1 (A) to 1 (C), when the adhesive layer 18 has an insulating property, the adhesive layer 18 is used as the low thermal conductive layer without providing the low thermal conductive portion 20a. A second high heat conduction part similar to the high heat conduction part 20 b may be provided on the adhesive layer 18. In this case, if necessary, a layer that covers the whole may be provided so that the adhesiveness of the adhesive layer 18 does not become a problem, or a layer that covers a region where the adhesive layer 18 is exposed may be provided. .
Or when the adhesion layer 18 has insulation, the adhesion layer 18 is made into a low heat conductive layer, the layer which covers the adhesion layer 18 is provided, and the 2nd high heat conduction part similar to the high heat conduction part 20b is provided on this layer. May be provided.

  In the present invention, having insulation means that the insulation resistance per element when the layer is formed is 0.1 MΩ or more.

FIG. 3A to FIG. 3D conceptually show an example of the thermoelectric conversion module of the present invention in which a plurality of such thermoelectric conversion elements 10 of the present invention are connected in series. 3A to 3C are top views and FIG. 3D is a front view.
In this example, each of the first substrate 12A and the second substrate 20A has a rectangular plate-like high heat conductive portion that extends in one direction on the surface of a rectangular plate-like low heat conductive material, and a side that contacts the low heat conductive portion of the square pillar. Are arranged in the direction orthogonal to the extending direction of the quadrangular prism at equal intervals.
That is, in the first substrate 12A and the second substrate 20A, the entire surface of one surface is a low heat conductive portion, and the other surface is a low heat conductive portion and a high heat conductive portion extending in one direction. The structure is alternately formed in the orthogonal direction at equal intervals (see FIGS. 3A, 3C, and 3D).
Also in this example, the first substrate (second substrate) can use various configurations other than the configuration in which the high thermal conductivity portion is placed on the surface of the low thermal conductivity portion. For example, as conceptually shown in FIG. 4B, the first substrate is placed in one direction (a direction perpendicular to the paper surface of FIG. 4B) on the rectangular plate-like low heat conduction portion 12a. The groove extending in the direction perpendicular to the extending direction may be formed at equal intervals with the groove width, and the high heat conducting portion 12b may be incorporated in the groove.

As shown in FIG. 3B, the thermoelectric conversion layer 16 has a rectangular surface shape, and the entire surface of the first substrate 12A is formed on the surface on the side that is the low heat conductive portion 12a, and the low heat conductive portion 12a and the high heat conductive portion 12b. The boundary and the center of are aligned in the plane direction. 3B, the first substrate 12A is in a state where FIG. 3D is reversed upside down in the vertical direction in the drawing.
The lateral size of the thermoelectric conversion layer 16 in FIG. 3B is set between 0.5 times and less than 2.0 times the width of the high heat conduction portion 12b. Hereinafter, the horizontal direction in FIG. 3B is also simply referred to as “horizontal direction”. That is, the horizontal direction is an alternate arrangement direction of the low heat conduction portions 12a and the high heat conduction portions 12b.
The thermoelectric conversion layer 16 is formed at equal intervals every other boundary with respect to the boundary between the low thermal conductivity portion 12a and the high thermal conductivity portion 12b in the lateral direction. That is, the thermoelectric conversion layer 16 is formed at equal intervals with the same center as the distance of twice the width of the high thermal conductive portion 12b.
Further, the thermoelectric conversion layers 16 are two-dimensionally formed so that the rows of the thermoelectric conversion layers 16 arranged at equal intervals in the horizontal direction are arranged at equal intervals in the vertical direction of FIG. . Hereinafter, the vertical direction in FIG. 3B is also simply referred to as “vertical direction”. That is, the up and down direction is the extending direction of the low heat conduction portion 12a and the high heat conduction portion 12b.
Furthermore, as shown in FIG. 3B, the arrangement in the horizontal direction of the thermoelectric conversion layers 16 is shifted in the horizontal direction by the width of the high thermal conduction portion 12b in the columns adjacent in the vertical direction. In other words, in the rows adjacent in the vertical direction, the thermoelectric conversion layers 16 are alternately formed with the horizontal centers corresponding to the widths of the high heat conduction portions 12b.

The thermoelectric conversion layers 16 are connected in series by the first electrode 26 (second electrode 28). Specifically, as shown in FIG. 3B, in the arrangement of the thermoelectric conversion layers 16 in the horizontal direction in the drawing, the first electrode 26 is provided so as to sandwich each thermoelectric conversion layer 16 in the horizontal direction. Thereby, the thermoelectric conversion layers 16 arranged in the lateral direction are connected in series by the first electrode 26. In FIG. 3B, the first electrode 26 is shaded to clarify the configuration.
At the ends of the rows in the horizontal direction of the thermoelectric conversion layers 16, the thermoelectric conversion layers 16 in rows adjacent in the vertical direction are connected by the first electrode 26. The connection of the thermoelectric conversion layer 16 in the vertical direction by the first electrode 26 at the end of the horizontal row is such that the thermoelectric conversion layer 16 at one end is connected to the thermoelectric conversion layer 16 at the same end of the upper row. The thermoelectric conversion layer 16 at the other end is connected to the thermoelectric conversion layer 16 at the same end in the lower row.
Thereby, all the thermoelectric conversion layers 16 are connected in series like the one line | wire folded in multiple times in the horizontal direction.

As conceptually shown in FIG. 3A, on the thermoelectric conversion layer 16 and the first electrode 26, the entire surface of the second substrate 20A is on the side where the low heat conductive portion 20a is located, and the low heat conductive portion. The second substrate 20A is laminated such that the boundary between 12a and the high thermal conductivity portion 12b coincides with the first substrate 12A. This stacking is performed so that the high thermal conductive portion 12b of the first substrate 12A and the high thermal conductive portion 20b of the second substrate 20A are alternated.
Although not shown, the adhesive layer 18 is formed on the thermoelectric conversion layer 16 and the first electrode 26 so as to cover the entire surface of the first substrate 12A prior to the lamination of the second substrate 20A.

Therefore, the low heat conduction part 12a of the first substrate 12A and the region of the second substrate 20A only with the high heat conduction part 20b are aligned in the plane direction and face each other, and the high heat conduction part 12b of the first substrate 12A and the second substrate 20A The region of only the low heat conducting portion 20a faces the surface direction in alignment.
Thereby, the thermoelectric conversion module of this invention formed by connecting two or more thermoelectric conversion elements 10 of this invention in series is comprised.

Here, as described above, in the horizontal arrangement of the thermoelectric conversion layers 16, in the columns adjacent in the vertical direction, the horizontal center line of the thermoelectric conversion layers 16 is the high heat conduction portion 12b (that is, the high heat conduction portion 20b). This is formed by shifting in the horizontal direction by the width of. In other words, in the rows adjacent in the vertical direction, the thermoelectric conversion layers 16 are formed so that the horizontal center lines of the thermoelectric conversion layers 16 are staggered by the width of the high thermal conductivity portion 12b.
For this reason, the thermoelectric conversion layers 16 connected in series as a single folded line have all the thermoelectric conversion layers 16 in the flow in one direction of the connection direction, and one half of the thermoelectric conversion layers 16 is the high thermal conductivity of the first substrate 12A. The portion 12b faces the region of the second substrate 20A only of the low heat conduction portion 20a, and the other half faces the region of only the low heat conduction portion 12a of the first substrate 12A and the high heat conduction portion 20b of the second substrate 20A. .
For example, when viewed in the serial connection direction from the top to the bottom of FIG. 3B, as shown in FIGS. 3A to 3C, all the thermoelectric conversion layers 16 are upstream. Half of the first substrate 12A faces the region of only the high thermal conductivity portion 12b and the second substrate 20A of the low thermal conductivity portion 20a, and the half of the downstream side of the first substrate 12A of the region of only the low thermal conductivity portion 12a and the second substrate 20A. It faces the high heat conduction part 20b.
Therefore, when the heat source is arranged on the first substrate 12A side or the second substrate 20A side, the heat flow direction relative to the connection direction, that is, the flow direction of the generated electricity is the same in all the thermoelectric conversion layers 16 connected in series. And the thermoelectric conversion module can generate electricity properly.

  Below, an example of the manufacturing method of the thermoelectric conversion module shown to FIG. 3 (A)-FIG. 3 (D) is demonstrated. In addition, a thermoelectric conversion element can be manufactured according to the manufacturing method of this thermoelectric conversion module.

  First, a first substrate 12A (first substrate 12) having a low thermal conductivity portion 12a and a high thermal conductivity portion 12b, and a second substrate 20A (second substrate 20) having a low thermal conductivity portion 20a and a high thermal conductivity portion 20b are prepared. .

The first substrate 12A and the second substrate 20A may be manufactured by a known method using photolithography, etching, film formation technology, or the like.
For example, it can be formed by etching one side of a copper polyimide film in which copper is laminated on both sides of polyimide, and etching the other side so as to form a high heat conduction part pattern. In addition, a sheet-like material serving as a low heat conduction portion is prepared, and a belt-like high heat conduction portion is adhered to the sheet-like material in a direction orthogonal to the extending direction at equal intervals with the width of the belt. What is necessary is just to produce 12A and the 2nd board | substrate 20A.
Commercially available products can also be used for the first substrate 12A and the second substrate 20A.

Next, the thermoelectric conversion layer 16 is formed.
As a method for forming the thermoelectric conversion layer 16, as an example, a component such as a nanocarbon material such as CNT and an organic acid, and a resin material or a surfactant added as necessary to a solvent such as water or an organic solvent. A dissolved or dispersed CNT dispersion is prepared. A method of patterning and forming the thermoelectric conversion layer 16 by patterning the CNT dispersion liquid, applying it to the first substrate 12A, and drying or further curing the resin material or the like is exemplified.
Alternatively, a CNT film containing an organic acid is formed on the filter by filtering a CNT dispersion containing the same nanocarbon material and organic acid through a filter. The CNT film formed on the filter is peeled off from the filter to form a CNT thin film. If necessary, excess liquid is sucked out using filter paper or the like, and the CNT thin film is placed on the first substrate 12A in a wet state, and is shaped as necessary. Furthermore, a method of patterning the thermoelectric conversion layer 16 by drying a wet CNT thin film or further curing a resin material or the like can also be used.
Preparation of a CNT dispersion containing a nanocarbon material may be performed by a known method. In this regard, the method described below is also the same.

As another method, a similar CNT dispersion containing no organic acid is prepared. By filtering this CNT dispersion with a filter, a CNT film is formed on the filter. The CNT thin film formed on the filter is peeled off from the filter and dried to produce a CNT thin film. After immersing this CNT thin film in a solution containing an organic acid, if necessary, excess liquid is sucked using a filter paper or the like, and the CNT thin film is placed on the first substrate 12A in a wet state and molded as necessary. Furthermore, a method of patterning the thermoelectric conversion layer 16 by drying a wet CNT thin film or further curing a resin material or the like can also be used.
As another method, a similar CNT dispersion containing no organic acid is prepared, and this CNT dispersion is patterned on the first substrate 12A and applied and dried. Next, the thin film is impregnated with the organic acid by immersing the first substrate 12A in a solution containing the organic acid. Further, the thin film impregnated with the organic acid may be formed by patterning the thermoelectric conversion layer containing the organic acid by drying or further curing the resin material.
In these methods, the immersion time in the solution containing the organic acid may be appropriately set according to the concentration of the organic acid in the solution, the type of the organic acid, the composition of the thermoelectric conversion layer, and the like.

As another method, a thin film, a lump, a fibrous material or the like containing a nanocarbon material and an organic acid is produced in the same manner as the two methods.
These are crushed and dispersed in a resin material or solvent to prepare a coating solution. The coating solution is patterned and applied to the first substrate 12A, and dried or further cured to cure the resin material. A method of forming layer 16 is illustrated.

As a method of applying the CNT dispersion by patterning, a known method can be used.
As an example, a method of pattern printing a CNT dispersion liquid or the like on the first substrate 12A by a printing method is exemplified. As the printing method, various known printing methods such as screen printing, metal mask printing, gravure printing, flexographic printing, offset printing, and inkjet printing can be used.
Further, it is also possible to use a method in which a mold or mask is provided at a predetermined position on the first substrate 12A, and a CNT dispersion liquid or paste is applied by patterning using the mold or mask.

Further, instead of patterning and applying the CNT dispersion liquid, etc., after applying and drying the CNT dispersion liquid and paste on the entire surface of the first substrate 12A, etching such as laser engraving, sandblasting, electron beam method, plasma etching, etc. A method of forming the thermoelectric conversion layer 16 by patterning by removing unnecessary portions can be used.
Note that etching may be performed using a mask formed using photolithography, a metal mask, or the like, if necessary.

Next, the first electrode 26 and the second electrode 28 are formed so as to sandwich the thermoelectric conversion layer 16 in the plane direction.
The formation of the first electrode 26 and the second electrode 28 is performed by vapor deposition, printing, adhesion to a substrate via an adhesive / adhesive, etc., depending on the material for forming the first electrode 26 and the second electrode 28, etc. What is necessary is just to perform by a well-known method. Examples of the printing method include screen printing, metal mask printing, ink jet printing, and the like.
The electrode pattern may be formed using a mask during vapor deposition or printing, and may be formed by patterning by a known method such as etching, sandblasting, laser engraving, or electron beam method after the electrode is formed on the surface.
As described above, the first electrode 26 and the second electrode 28 may be formed prior to the formation of the thermoelectric conversion layer 16.

Next, the adhesive layer 18 is formed so as to cover the entire surface of the first substrate 12A and cover the thermoelectric conversion layer 16, the first electrode 26, and the second electrode 28.
The adhesive layer 18 may be formed by a known method such as a coating method depending on the material for forming the adhesive layer 18. Moreover, as described above, the adhesive layer 18 may be formed using a double-sided tape or an adhesive film.

Furthermore, the prepared second substrate 20A is attached to the thermoelectric conversion layer 16 with the side where the high heat conduction portion 20b is not formed, and the thermoelectric conversion module (thermoelectric conversion element 10) is manufactured.
Alternatively, instead of forming the adhesive layer 18 on the first substrate 12A, the adhesive layer 18 is formed on the surface of the second substrate 20A where the high thermal conductive portion 20b is not formed, and is adhered to the first substrate 12A. Thus, a thermoelectric conversion module (thermoelectric conversion element 10) may be manufactured.

Such a thermoelectric conversion element and thermoelectric conversion module of the present invention can be used for various applications.
Examples include various power generation applications such as hot spring thermal generators, solar thermal generators, waste heat generators, and other devices (devices) such as wristwatch power supplies, semiconductor drive power supplies, and small sensor power supplies. The Moreover, as a use of the thermoelectric conversion element of this invention, sensor element uses, such as a thermal sensor and a thermocouple, are illustrated besides a power generation use.

  As described above, the thermoelectric conversion element and the thermoelectric conversion module of the present invention have been described in detail. However, the present invention is not limited to the above-described examples, and various improvements and modifications may be made without departing from the gist of the present invention. Of course it is good.

  Hereinafter, the present invention will be described in more detail with reference to specific examples of the present invention. However, the present invention is not limited to the following examples.

[Example 1]
A thermoelectric conversion element conceptually shown in FIG. 5 was produced.
60 mg of single-walled CNT (manufactured by Meijo Nanocarbon Co., Ltd.) is added to 60 mL (liter) of 2-butanone, and stirred at 18000 rpm for 5 minutes using a mechanical homogenizer (manufactured by SMT Co., Ltd., High Flex Homogenizer) to disperse the CNT. Liquid A was obtained.
The obtained CNT dispersion A was filtered through a membrane filter (material: PTFE (polytetrafluoroethylene), pore diameter: 1 μm) to form a CNT film on the membrane filter. The CNT film was peeled from the membrane filter and dried on a hot plate at 145 ° C. to obtain a CNT thin film A.

On the other hand, a copper polyimide film having a thickness of 70 μm and a thickness of 30 × 10 mm bonded to one surface of a polyimide film having a thickness of 75 μm and 30 × 66 mm was prepared as the first substrate 12. The copper polyimide film has a middle line in the longitudinal direction of the polyimide film as a base line (one-dot chain line), and one long side coincides with the base line, and a copper foil is attached.
Furthermore, electrodes 26 and 28 having a width of 6 mm, a length of 30 mm, and a thickness of 200 nm were formed by depositing gold on the surface of the first substrate 12 on which the copper foil was not adhered. The electrodes 26 and 28 are aligned in the longitudinal direction of the first substrate 12 with a 6 × 6 mm gap in the center of the first substrate 12 with the center in the width direction coinciding with the center in the short direction of the first substrate 12. Arranged to be symmetrical. Note that a chromium layer having a thickness of 50 nm was previously formed as an underlayer on the electrode forming portion on the first substrate 12.
Furthermore, as the second substrate 20, a copper polyimide film was prepared in which a 70 μm thick, 30 × 10 mm copper foil was bonded to one side of a 75 μm thick, 30 × 50 mm polyimide film. This copper polyimide film also has a copper foil attached so that the middle line in the longitudinal direction of the polyimide film is a base line (one-dot chain line) and one long side coincides with the base line.
In such a 1st board | substrate 12 and the 2nd board | substrate 20 (copper polyimide film), a copper foil becomes a high heat conductive part, and the area | region only of the polyimide film in which copper foil is not stuck becomes a low heat conductive part.

The previously prepared CNT thin film A was immersed in an ethanol solution of benzoic acid having a concentration of 5 mM / L (liter) for 16 hours. Hereinafter, an ethanol solution of benzoic acid is also referred to as “benzoic acid ethanol solution”.
After excess solution was blotted with filter paper from the CNT thin film A immersed in the benzoic acid ethanol solution, the CNT thin film A was placed in the center of the electrode formation surface of the first substrate 12 in a wet state. The first substrate 12 on which the CNT thin film A was placed was dried at 145 ° C. on a hot plate, whereby the CNT thin film A was adhered and fixed, and the thermoelectric conversion layer 16 having an average thickness of 15 μm was produced.
The CNT thin film A was formed in a wet state to 10 × 10 mm, and placed so that the center 6 × 6 mm region of the first substrate 12 sandwiched between the electrodes was the center. Therefore, the thermoelectric conversion layer 16 is in a state where both end portions 2 mm in the longitudinal direction of the first substrate 12 are placed on the electrodes 26 and 28.

On the other hand, a double-sided tape (adhesive transfer tape 8146-1, 3M) having a thickness of 25 μm was adhered as the adhesive layer 18 to the surface of the second substrate 20 that was a polyimide film.
The adhesive layer 18 is formed so that the first substrate 12 and the second substrate 20 have the same base line, and the first substrate 12 and the second substrate 20 have a high thermal conductivity portion and a low thermal conductivity portion alternated. It laminated | stacked and stuck toward the 1st board | substrate 12 side. As a result, an in-plane type thermoelectric conversion element as shown in FIG. 5 was produced.

[Example 2]
A thermoelectric conversion element was produced in the same manner as in Example 1 except that in the immersion of the CNT thin film A, an ethanol solution of 1-naphthoic acid having a concentration of 5 mM / L was used instead of the benzoic acid ethanol solution.

[Example 3]
A thermoelectric conversion element was produced in the same manner as in Example 1 except that in the immersion of the CNT thin film A, a 2-butanone solution of 1-pyrenecarboxylic acid having a concentration of 5 mM / L was used instead of the ethanolic benzoate solution. .

[Example 4]
A thermoelectric conversion element was produced in the same manner as in Example 1 except that in the immersion of the CNT thin film A, an ethanol solution of trimesic acid having a concentration of 5 mM / L was used instead of the benzoic acid ethanol solution.

[Example 5]
A thermoelectric conversion element was produced in the same manner as in Example 1 except that in the immersion of the CNT thin film A, an acetic acid aqueous solution having a concentration of 5 mM / L was used instead of the benzoic acid ethanol solution.

[Example 6]
A thermoelectric conversion element was produced in the same manner as in Example 1 except that in the immersion of the CNT thin film A, a propionic acid aqueous solution (5 mM) having a concentration of 5 mM / L was used instead of the benzoic acid ethanol solution.

[Example 7]
A thermoelectric conversion element was produced in the same manner as in Example 1 except that in the immersion of the CNT thin film A, an ethanol solution of cyclohexanecarboxylic acid having a concentration of 5 mM / L was used instead of the benzoic acid ethanol solution.

[Example 8]
A thermoelectric conversion element was produced in the same manner as in Example 1 except that in the immersion of the CNT thin film A, a succinic acid aqueous solution having a concentration of 5 mM / L was used instead of the benzoic acid ethanol solution.

[Example 9]
A thermoelectric conversion element was produced in the same manner as in Example 1 except that in the immersion of the CNT thin film A, an adipic acid aqueous solution having a concentration of 5 mM / L was used instead of the benzoic acid ethanol solution.

[Example 10]
A thermoelectric conversion element was produced in the same manner as in Example 1 except that in the immersion of the CNT thin film A, a succinic acid aqueous solution having a concentration of 5 mM / L was used instead of the benzoic acid ethanol solution.

[Example 11]
A thermoelectric conversion layer was obtained in the same manner as in Example 1 except that in the immersion of the CNT thin film A, a phenylphosphonic acid aqueous solution having a concentration of 5 mM / L was used instead of the benzoic acid ethanol solution. Further, a thermoelectric conversion element was produced in the same manner as in Example 1.

[Example 12]
A thermoelectric conversion element was produced in the same manner as in Example 1 except that a p-toluenesulfonic acid / monohydrate aqueous solution having a concentration of 5 mM / L was used instead of the benzoic acid ethanol solution in the immersion of the CNT thin film A. did.

[Example 13]
A thermoelectric conversion element was produced in the same manner as in Example 1 except that in the immersion of the CNT thin film A, an ethanol solution of p-hydroxybenzoic acid having a concentration of 5 mM / L was used instead of the benzoic acid ethanol solution.

[Example 14]
A thermoelectric conversion element was produced in the same manner as in Example 1 except that in the immersion of the CNT thin film A, an ethanol solution of camphorsulfonic acid having a concentration of 5 mM / L was used instead of the benzoic acid ethanol solution.

[Comparative Example 1]
A thermoelectric conversion element was produced in the same manner as in Example 1 except that the CNT thin film A produced in Example 1 was used as it was as the thermoelectric conversion layer without being immersed in the benzoic acid ethanol solution. That is, the thermoelectric conversion layer of this thermoelectric conversion element does not contain an organic acid.

[Comparative Example 2]
A thermoelectric conversion element was produced in the same manner as in Example 1 except that, in the immersion of the CNT thin film A, a hydrochloric acid aqueous solution having a concentration of 5 mM / L was used instead of the benzoic acid ethanol solution.

  About the produced thermoelectric conversion elements of Examples 1 to 14 and Comparative Examples 1 and 2, the thermoelectric conversion performance and the electrical stability of the elements were evaluated.

[Evaluation of thermoelectric conversion performance]
<Measurement of conductivity>
The conductivity of the thermoelectric conversion layer 16 of the thermoelectric conversion element produced in each example and comparative example was measured in the form before the second substrate 20 was attached.
The measurement is performed using a low resistivity meter (Mitsubishi Chemical Analytech, Loresta GP), measuring the surface resistivity (unit: Ω / □), and using the average thickness (unit: cm) of the thermoelectric conversion layer 16. The electrical conductivity (S / cm) was calculated from the following formula.
(Conductivity) = 1 / ((Surface resistivity) × (Average thickness))
In Examples 1 to 14 and Comparative Examples 1 and 2, since the amount of CNT is the same, the average thickness of the thermoelectric conversion layer 16 is substantially uniform.
<Measurement of Seebeck coefficient>
The Seebeck coefficient S is related to the temperature difference ΔT applied to the substance, the voltage V generated when the temperature difference is applied, and the following equation.
S = V / ΔT
The thermoelectric conversion elements produced in each example and comparative example were placed on a hot plate with the first substrate 12 side down, and a temperature control Peltier element was placed on the second substrate 20. By keeping the temperature of the hot plate constant at 100 ° C. and decreasing the temperature of the Peltier element, a temperature difference ΔT of 5 ° C. and 10 ° C. between the first substrate 12 and the second substrate 20 of the thermoelectric conversion element. The voltage V when each temperature difference was applied was measured, and the Seebeck coefficient S (unit: μV / K) was estimated by calculating the proportionality coefficient between each temperature difference and the voltage.

<Evaluation of conductivity>
The normalized conductivity of each example and comparative example was calculated by the following formula and evaluated as follows.
Normalized conductivity = (conductivity of each example or comparative example) / (conductivity of comparative example 1)
A: Normalized conductivity is 1.5 or more B: Normalized conductivity is 1.3 or more and less than 1.5 C: Normalized conductivity is 1.1 or more and less than 1.3 D: Normalized conductivity is Less than 1.1 A is most excellent in conductivity and inferior in performance in the order of A, B, C and D.

<Evaluation of thermoelectromotive force>
The normalized Seebeck coefficient of each example and comparative example was calculated by the following formula and evaluated as follows.
Normalized Seebeck coefficient = (Seebeck coefficient of each example or comparative example) / (Seebeck coefficient of comparative example 1)
A: Normalized Seebeck coefficient is 0.9 or more B: Normalized Seebeck coefficient is 0.7 or more and less than 0.9 C: Normalized Seebeck coefficient is 0.5 or more and less than 0.7 D: Normalized Seebeck coefficient is Less than 0.5 A is the best thermoelectromotive force, and the performance is in the order of A, B, C, D.

<Power factor>
From the obtained value, the power factor (PF) was calculated using the following formula.
PF = S ² × σ [W / K ² · m]
The normalized PF coefficient of each example and comparative example was calculated by the following formula and evaluated as follows.
Normalized PF coefficient = (PF of each example or comparative example) / (PF of comparative example 1)
A: Standardized PF is 1.5 or more B: Standardized PF is 1.3 or more and less than 1.5 C: Standardized PF is 1.1 or more and less than 1.3 D: Standardized PF is less than 1.1 A is the best, and the performance is in the order of A, B, C, D.

[Evaluation of device electrical stability]
The resistance [Ω] of the thermoelectric conversion element produced in each example and comparative example was measured immediately after production and after 7 days using a low resistivity meter (Loresta GP, manufactured by Mitsubishi Chemical Analytech). Electrical stability was evaluated using the ratio of resistance values (resistance change rate) as an index.
Resistance change rate = resistance value (7 days after device fabrication) / resistance value (immediately after device fabrication)
The rate of change in resistance was evaluated as follows.
A: Less than 1.1 B: 1.1 or more, less than 1.5 C: 1.5 or more, less than 2 D: 2 or more A is the most excellent in electrical stability and stable in the order of A, B, C, D Inferior to sex.
The results are shown in Table 1.

As is apparent from Table 1, Examples 1 to 14 obtained by impregnating the single-walled CNT thin film with an organic acid solution were found to have excellent thermoelectric conversion performance and excellent electrical stability of the thermoelectric conversion element. .
Especially, Examples 1-10 and 13 using carboxylic acid showed the more excellent effect, and especially the aromatic carboxylic acid of Examples 1-4, 13 showed the further outstanding effect.
In addition, when Examples 1 to 10 and 13 are compared, Examples (Examples 1 to 4, 7 to 10 and 13) in which the melting point of the carboxylic acid is 100 ° C. or higher or the boiling point is 200 ° C. or higher have more excellent effects. Examples where the melting point of the carboxylic acid is 100 ° C. or higher and the boiling point is 200 ° C. or higher (Examples 1 to 4, 8 to 10 and 13) showed further excellent effects.
In Comparative Example 2, it was observed that the electrode was partially corroded by hydrochloric acid after evaluation of electrical stability.

[Example 15]
In the immersion of the CNT thin film A, a thermoelectric conversion element was prepared in the same manner as in Example 1, except that an aqueous poly (4-styrenesulfonic acid) solution having a concentration of 0.2 w / v% was used instead of the benzoic acid ethanol solution. Produced.

[Example 16]
A thermoelectric conversion element was produced in the same manner as in Example 1 except that in the immersion of the CNT thin film A, a poly (vinylphosphonic acid) aqueous solution having a concentration of 5 mM / L was used instead of the benzoic acid ethanol solution.

About the produced thermoelectric conversion element, similarly to Example 1 etc., the thermoelectric conversion performance and the electrical stability of the element were evaluated.
The results are shown in Table 2 below. The organic acids used in Examples 15 and 16 were unclear in both melting point and boiling point.

As is apparent from Table 2, it was confirmed that even when an organic acid polymer (polymer acid) was used as the organic acid, the thermoelectric conversion performance was excellent, and in particular, the electrical stability was excellent.

[Example 17]
Single-walled CNT (manufactured by Meijo Nanocarbon Co., Ltd.) 5 mg and benzoic acid 15 mg are added to 20 mL of ethanol, and stirred at 18000 rpm for 5 minutes using a mechanical homogenizer (Teraoka High Flex Homogenizer) to disperse CNTs. Liquid B was obtained.
The obtained CNT dispersion B was filtered through a membrane filter (material: PTFE, pore size: 1 μm) to form a CNT film on the membrane filter.
The CNT film was peeled off from the membrane filter, and excess solution was blotted with a filter paper to obtain a wet CNT thin film B.
The in-plane type thermoelectric conversion element as shown in FIG. 5 is the same as in Example 1 except that the wet CNT thin film B is placed on the first substrate 12 to form the thermoelectric conversion layer 16. Was made. The average thickness of the thermoelectric conversion layer 16 was 17 μm.

[Example 18]
In the preparation of the CNT dispersion B, a thermoelectric conversion element was obtained in the same manner as in Example 17 except that 20 mg of 1-naphthoic acid was used instead of 15 mg of benzoic acid, and 20 mL of 2-butanone was used instead of 20 mL of ethanol. Was made.

About the produced thermoelectric conversion element, similarly to Example 1 etc., the thermoelectric conversion performance and the electrical stability of the element were evaluated.
The results are shown in Table 3 below.

As is apparent from Table 3, even when a thermoelectric conversion layer forming material is produced using the CNT coating solution B in which single-walled CNT and an organic acid are added together, and the thermoelectric conversion layer is formed, the thermoelectric conversion performance and electrical It was confirmed that a thermoelectric conversion element excellent in stability was obtained.

[Example 19]
A CNT thin film B was produced in the same manner as in Example 18.
50 mg of the produced CNT thin film B and 150 mg of polystyrene (manufactured by Wako Pure Chemical Industries, degree of polymerization 2000) are put into 20 mL of o-dichlorobenzene, and 18000 rpm, 5 using a mechanical homogenizer (High Flex homogenizer manufactured by Terraoka). Stir for a minute. Furthermore, using a high-speed swirling thin film dispersion method (Filmix, manufactured by Primix Co., Ltd.), a stirring process was performed at a peripheral speed of 30 m / s for 5 minutes to obtain a CNT dispersion C.

A 10 × 10 mm mold is placed on the first substrate 12 on which the same electrode as in Example 1 is formed, and the produced CNT dispersion C is poured into the mold and dried at 200 ° C. to obtain 10 × 10 mm. Thus, a thermoelectric conversion layer 16 having a thickness of 12 μm was formed. The thermoelectric conversion layer 16 was formed at the same position as in Example 1.
Thereafter, in-plane type thermoelectric conversion elements as shown in FIG. 5 were produced in the same manner as in Example 1.

[Example 20]
In the preparation of CNT dispersion B, a CNT thin film was prepared in the same manner as in Example 18 except that 29 mg of 1-pyrenecarboxylic acid was used instead of 20 mg of 1-naphthoic acid.
A thermoelectric conversion element was produced in the same manner as in Example 19 except that the CNT dispersion C was prepared using this CNT thin film.

[Comparative Example 3]
A thermoelectric conversion element was produced in the same manner as in Example 19 except that 1-naphthoic acid was not used.

About the produced thermoelectric conversion element, the thermoelectric conversion performance and the electrical stability of the element were evaluated similarly to Example 1 etc. except having used the value of the comparative example 3 as a comparative example at the time of normalization.
The results are shown in Table 4 below. The boiling point of 1-pyrenecarboxylic acid was unknown.

As is clear from Table 4, it was confirmed that a thermoelectric conversion element having excellent thermoelectric conversion performance and electrical stability was obtained even when a binder was used in addition to single-walled CNT and organic acid.

[Example 21]
In the preparation of CNT dispersion B, Example 17 except that 5 mg of scaly graphene (XG, manufactured by Sciences) was used instead of 5 mg of single-walled CNT, and 20 mg of 1-naphthoic acid was used instead of 15 mg of benzoic acid. In the same manner as above, CNT dispersion B was obtained.
A thermoelectric conversion element was produced in the same manner as in Example 17 except that this CNT dispersion B was used.

[Example 22]
In the preparation of CNT dispersion B, the same procedure as in Example 17 was carried out except that 5 mg of multilayer CNT (manufactured by SWeNT) was used instead of 5 mg of single-walled CNT, and 20 mg of 1-naphthoic acid was used instead of 15 mg of benzoic acid. Thus, CNT dispersion B was obtained.
A thermoelectric conversion element was produced in the same manner as in Example 17 except that this CNT dispersion B was used.

[Comparative Example 4]
In the preparation of the CNT dispersion B, a CNT dispersion B was obtained in the same manner as in Example 21 except that 20 mg of 1-naphthoic acid was not used.
A thermoelectric conversion element was produced in the same manner as in Example 21 except that this CNT dispersion B was used. That is, this thermoelectric conversion layer does not contain an organic acid.

[Comparative Example 5]
In the preparation of CNT dispersion B, CNT dispersion B was obtained in the same manner as in Example 22 except that 20 mg of 1-naphthoic acid was not used.
A thermoelectric conversion element was produced in the same manner as in Example 22 except that this CNT dispersion B was used. That is, this thermoelectric conversion layer does not contain an organic acid.

About the produced thermoelectric conversion element, Example 21 uses the value of Comparative Example 4 as a comparative example at the time of normalization, Example 22 uses the value of Comparative Example 5 as a comparative example at the time of normalization, and Comparative Example 4 Is the same as in Example 1 except that the value of Comparative Example 4 is used as a comparative example at the time of standardization, and the value of Comparative Example 5 is used as the comparative example at the time of standardization. The conversion performance and the electrical stability of the device were evaluated.
The results are shown in Table 5 below.

As can be seen from Table 5, the thermoelectric conversion layer has an organic acid, so that in the case where graphene or multilayer CNT is used as the nanocarbon material instead of the single-walled CNT, the thermoelectric conversion performance and electrical stability are improved. It was confirmed that an excellent thermoelectric conversion element was obtained.

[Example 23]
To 20 mL of water, 500 mg of CNT (manufactured by Meijo Nanocarbon Co., Ltd.) and 1500 mg of sodium deoxycholate were added.
This solution was dispersed for 7 minutes using a bladed homogenizer. The obtained dispersion was further subjected to a stirring treatment at a peripheral speed of 30 m / s for 5 minutes using a high-speed rotating thin film dispersion method (Filmix, manufactured by Primics) to obtain CNT dispersion D.

A first substrate 12A and a second substrate 20A in which copper stripes having a width of 0.5 mm and a thickness of 70 μm were formed on one surface of a polyimide film having a thickness of 25 μm and 15 × 12 cm were prepared (FIG. 3). (See (A) to FIG. 3 (D)).
1785 patterns of CNT dispersion D of 0.5 × 1 mm were formed by screen printing on a 6 × 6 cm region of the surface of the first substrate 12A, which is the low thermal conductive portion 12a. Note that the pattern of the CNT dispersion D was formed so that the boundary between the high heat conduction part and the low heat conduction part (the boundary of the copper stripe) coincides with the center of the pattern of 0.5 × 1 mm.
The first substrate 12A on which the pattern of the CNT dispersion D was formed was heated on a hot plate at 50 ° C. for 30 minutes, and further heated at 130 ° C. for 2.5 hours to dry the CNT dispersion D.
Next, the first substrate 12A was immersed in ethanol for 14 hours. The first substrate 12A immersed in ethanol was heated at 50 ° C. for 30 minutes on a hot plate, and further heated at 130 ° C. for 150 minutes to dry the CNT dispersion D.

The first substrate 12A immersed and dried in ethanol was immersed in an ethanol solution of 1-naphthoic acid having a concentration of 5 mM / L for 16 hours.
The first substrate 12A immersed in an ethanol solution of 1-naphthoic acid was heated on a hot plate at 50 ° C. for 30 minutes, and further heated at 130 ° C. for 2.5 hours to dry the CNT dispersion D. Eight thermoelectric conversion layers 16 were formed. The average thickness of the thermoelectric conversion layer 16 was 5 μm.

  Next, 1785 thermoelectric conversion layers 16 were connected in series with a gold first electrode 26 having a thickness of 200 nm (see FIG. 3B). The first electrode 26 was formed by vacuum vapor deposition using a mask.

On the other hand, a double-sided tape (adhesive transfer tape 8146-1, 3M) having a thickness of 25 μm was stuck as the adhesive layer 18 on the surface of the second substrate 20A, which is the low thermal conductive portion 20a.
This double-sided tape was affixed so as to cover the thermoelectric conversion layer 16 and the first electrode 26 to produce a thermoelectric conversion module as shown in FIGS. 3 (A) to 3 (D). In the second substrate 20A, the center of the thermoelectric conversion layer 16 and the boundary of the copper stripe coincide with each other, the extending direction of the copper stripe coincides with the first substrate 12A, and the first substrate in the plane direction It stuck so that 12A and a copper stripe might not overlap.

The produced thermoelectric conversion module was placed on the hot plate with the first substrate 12 side down, and a Peltier element for temperature control was installed on the second substrate 20.
A temperature difference of 10 ° C. was made between the first substrate 12 and the second substrate 20 of the thermoelectric conversion module by keeping the temperature of the hot plate constant at 100 ° C. and decreasing the temperature of the Peltier element.
As a result, it was confirmed that an output of 30 μW was obtained.

[Example 24]
(Preparation of dispersion)
Sodium deoxycholate 1200 mg (manufactured by Tokyo Kasei Kogyo Co., Ltd.) was dissolved in 16 mL of water, and 400 mg of single-walled CNT (EC, Meijo Nanocarbon Co., Ltd., average CNT length of 1 μm or more) was added. This composition was mixed for 7 minutes using a mechanical homogenizer (manufactured by SMT Co., Ltd., HIGH-FLEX HOMOGENiZER HF93) to obtain a preliminary mixture. Using the thin film swirl type high speed mixer “Filmix 40-40” (manufactured by Primics), the obtained preliminary mixture was placed in a thermostatic layer at 10 ° C. for 2 minutes at a peripheral speed of 10 m / sec, and then a peripheral speed of 40 m / The dispersion treatment was performed by the high-speed swirling thin film dispersion method for 5 minutes in sec. 100 mg of carboxymethylcellulose sodium salt (manufactured by Aldrich, high viscosity product) was added to the obtained dispersion composition, and mixed for 2 minutes at 2000 rpm with a rotating / revolving mixer (Shinky, manufactured by Aritori Kentaro), 2 at 2200 rpm. CNT dispersion liquid E was prepared by degassing for a minute.

(Production of thermoelectric conversion element)
A 10 mm × 10 mm pattern was formed by metal mask printing using the CNT dispersion E in the center of the electrode formation surface of the first substrate 12 and dried at 50 ° C. for 30 minutes and 120 ° C. for 30 minutes. After being immersed in ethanol for 1 hour, it was dried at 50 ° C. for 30 minutes and at 120 ° C. for 2.5 hours. The printed pattern was placed so that the 6 × 6 mm area at the center of the first substrate 12 sandwiched between the electrodes was centered. Therefore, the thermoelectric conversion layer 16 is in a state where both end portions 2 mm in the longitudinal direction of the first substrate 12 are placed on the electrodes 26 and 28.
On the other hand, a double-sided tape (adhesive transfer tape 8146-1, 3M) having a thickness of 25 μm was adhered as the adhesive layer 18 to the surface of the second substrate 20 that was a polyimide film.
The adhesive layer 18 is formed so that the first substrate 12 and the second substrate 20 have the same base line, and the first substrate 12 and the second substrate 20 have a high thermal conductivity portion and a low thermal conductivity portion. It laminated | stacked and stuck toward the 1st board | substrate 12 side. As a result, an in-plane type thermoelectric conversion element as shown in FIG. 5 was produced.

(Production of thermoelectric conversion module)
A first substrate 12A and a second substrate 20A in which copper stripes having a width of 0.5 mm and a thickness of 70 μm were formed on one surface of a polyimide film having a thickness of 25 μm and 15 × 12 cm were prepared (FIG. 3). (See (A) to FIG. 3 (D)).
1785 patterns of 0.5 × 1 mm CNT dispersion liquid E were formed by screen printing on a 6 × 6 cm region of the surface of the first substrate 12A, which is the low thermal conductive portion 12a. Note that the pattern of the CNT dispersion E was formed so that the boundary between the high heat conduction part and the low heat conduction part (the boundary of the copper stripe) coincided with the center of the pattern of 0.5 × 1 mm.
The first substrate 12A on which the pattern of the CNT dispersion E was formed was heated on a hot plate at 50 ° C. for 30 minutes and at 120 ° C. for 30 minutes. After being immersed in ethanol for 1 hour, the printed pattern formed with the CNT dispersion E was obtained by heating at 50 ° C. for 30 minutes and at 130 ° C. for 2.5 hours.
Next, 1785 thermoelectric conversion layers 16 were connected in series with a first electrode 26 of nickel having a thickness of 1 μm (see FIG. 3B). The first electrode 26 was formed by vacuum vapor deposition using a mask.
On the other hand, a double-sided tape (adhesive transfer tape 8146-1, 3M) having a thickness of 25 μm was stuck as the adhesive layer 18 on the surface of the second substrate 20A, which is the low thermal conductive portion 20a.
This double-sided tape was affixed so as to cover the thermoelectric conversion layer 16 and the first electrode 26 to produce a thermoelectric conversion module as shown in FIGS. 3 (A) to 3 (D). In the second substrate 20A, the center of the thermoelectric conversion layer 16 and the boundary of the copper stripe coincide with each other, the extending direction of the copper stripe coincides with the first substrate 12A, and the first substrate in the plane direction It stuck so that 12A and a copper stripe might not overlap.

[Example 25]
A thermoelectric conversion element and a thermoelectric conversion module were obtained by following the same procedure as in Example 24 except that 100 mg of sodium carboxymethylcellulose was changed to 100 mg of alginic acid (non-swellable, manufactured by Wako Pure Chemical Industries, Ltd.).

[Example 26]
A thermoelectric conversion element and a thermoelectric conversion module were obtained in the same manner as in Example 24 except that 100 mg of carboxymethyl cellulose sodium salt was changed to xanthan gum (manufactured by Tokyo Chemical Industry Co., Ltd.).

[Example 27]
A thermoelectric conversion element and a thermoelectric conversion module were obtained according to the same procedure as in Example 24 except that 100 mg of sodium carboxymethylcellulose was changed to dihydroabietic acid (manufactured by Wako Pure Chemical Industries, Ltd.).

[Example 28]
Carboxymethylcellulose sodium salt 100 mg (manufactured by Aldrich, high-viscosity product) and sodium deoxycholate 1200 mg (manufactured by Tokyo Chemical Industry Co., Ltd.) are dissolved in 16 mL of water, and 400 mg of single-walled CNTs (average length of EC and CNT manufactured by Meijo Nanocarbon Co., Ltd.) 1 μm or more) was added. This composition was mixed for 7 minutes using a mechanical homogenizer (manufactured by SMT Co., Ltd., HIGH-FLEX HOMOGENiZER HF93) to obtain a preliminary mixture. Using the thin film swirl type high speed mixer “Filmix 40-40” (manufactured by Primics), the obtained preliminary mixture was placed in a thermostatic layer at 10 ° C. for 2 minutes at a peripheral speed of 10 m / sec, and then a peripheral speed of 39 m / Dispersion treatment was performed by a high-speed rotating thin film dispersion method for 30 seconds at sec and 270 seconds at 40 m / sec. The obtained dispersion composition was mixed at 2000 rpm for 2 minutes with a rotating / revolving mixer (Shinky Corp., Aritori Nertaro), and degassed at 2200 rpm for 2 minutes to obtain CNT dispersion F. Thereafter, in the same manner as in Example 24, a thermoelectric conversion element and a thermoelectric conversion module were obtained.

[Comparative Example 6]
In Example 24, a thermoelectric conversion element and a thermoelectric conversion module were obtained according to the same procedure as Example 24 except that carboxymethylcellulose sodium salt was not added.

[Evaluation of thermoelectric conversion element]
About the thermoelectric conversion element produced in Examples 24-28 and the comparative example 6, except using the value of the comparative example 6 as a comparative example at the time of normalization, it is the same as Example 1 etc., and thermoelectric conversion performance and electrical Stability was evaluated. The results are shown in Table 6.

[Evaluation of thermoelectric conversion module]
About the thermoelectric conversion module produced in Examples 24-28 and the comparative example 6, the output was measured similarly to Example 23 grade | etc.,. The results are shown in Table 7.

  In the above examples, the mass ratio of the organic acid / nanocarbon material of the thermoelectric conversion layer was measured by spectrophotometry or thermogravimetric-differential thermal analysis. As a result, it was confirmed in all Examples that the mass ratio of the organic acid / nanocarbon material of the thermoelectric conversion layer was in the range of 0.005 to 1.

  It can be suitably used for a power generation device or the like.

DESCRIPTION OF SYMBOLS 10 Thermoelectric conversion element 12, 12A 1st board | substrate 12a, 20a Low heat conduction part 12b, 20b High heat conduction part 16 Thermoelectric conversion layer 18 Adhesion layer 20, 20A 2nd board | substrate 26,30,34 1st electrode 28,32,36 2nd electrode

Claims (10)

A substrate having a first high thermal conductivity portion having a thermal conductivity higher than that of other regions in at least a part of the surface direction;
A thermoelectric conversion layer containing a nanocarbon material and an organic acid formed on the substrate;
A low thermal conductive layer formed on the thermoelectric conversion layer;
A second high thermal conductivity portion provided in the low thermal conductivity layer, having a thermal conductivity higher than that of the low thermal conductivity layer and not completely overlapping with the first high thermal conductivity portion in the plane direction;
A thermoelectric conversion element comprising: a pair of electrodes connected to the thermoelectric conversion layer so as to sandwich the thermoelectric conversion layer in a plane direction.   The thermoelectric conversion element according to claim 1, wherein the nanocarbon material is a carbon nanotube.   The thermoelectric conversion element according to claim 2, wherein the nanocarbon material is a single-walled carbon nanotube.   The thermoelectric conversion element according to claim 1, wherein the organic acid is a carboxylic acid.   The thermoelectric conversion element according to claim 4, wherein the organic acid is an aromatic carboxylic acid.   The thermoelectric conversion element of any one of Claims 1-5 whose boiling point of the said organic acid is 200 degreeC or more.   The thermoelectric conversion element according to claim 1, wherein the organic acid has a melting point of 100 ° C. or higher.   The thermoelectric conversion element according to claim 1, wherein the organic acid is an organic acid polymer.   The thermoelectric conversion element according to claim 8, wherein the organic acid polymer is a polysaccharide or a derivative thereof.   The thermoelectric conversion module formed by connecting the thermoelectric conversion element of any one of Claims 1-9 in multiple numbers in series.