JP2017162911A - Method of manufacturing thermoelectric conversion element and thermoelectric conversion element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a thermoelectric conversion element and a thermoelectric conversion element capable of reducing an internal resistance in a direction perpendicular to a plane.SOLUTION: The method of manufacturing a thermoelectric conversion element having a thermoelectric conversion capability on the basis of a temperature difference in a direction perpendicular to a plane includes a bonding step of bonding a first electrode layer and a second electrode layer with a solution containing a conductive polymer having thermoelectric conversion performance. In the bonding step, a thermoelectric conversion layer is molded by bringing the first electrode layer and the second electrode layer, which are solid phases, into contact with the solution that is a liquid phase.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for manufacturing a thermoelectric conversion element and a thermoelectric conversion element.

  In recent years, energy harvesting has attracted attention in response to growing environmental problems. Energy harvesting means harvesting minute energy from the surrounding environment and converting it into electricity. Of the energy converted into electric power in this energy harvesting, thermoelectric power generation, which is power generation that converts thermal energy into electrical energy, has a long life, less environmental load, no moving parts, maintenance-free, etc. It has attracted attention because of its features.

  Non-Patent Document 1 describes a thermoelectric conversion element in which a conductive film made of a conductive material having thermoelectric conversion performance is stacked on a substrate, and a metal film is stacked on the conductive film. Non-Patent Document 2 describes a thermoelectric conversion element in which an Ag electrode is formed on a substrate and a film is formed on the Ag electrode with a conductive material having thermoelectric conversion performance.

International Publication No. 2009/029393

Qingshuo Wei, et al. , “Thermoelectric power enhancement of PEDOT: PSS in high-humidity conditions”, Applied Physics Express 7, 031601 (2014) Y. Suzuki, et al. , “Fabrication and Characterization of Flexible Thermoelectric Devices Town Energy Harvesting”, Yamaguchi Tokyo University of Science, 11th Advanced Materials Research Institute Joint Symposium, March 10, 2014, Proceedings 33

  The thermoelectric conversion elements described in Non-Patent Document 1 and Non-Patent Document 2 are in-plane thermoelectric conversion elements in which the direction of heat flow is the in-plane direction with respect to the substrate. On the other hand, from the viewpoint of improving the output of the thermoelectric conversion element, a surface direct thermoelectric conversion element having a heat flow direction perpendicular to the substrate (perpendicular direction) is expected. In FIG. 2 of Patent Document 1, a surface direct thermoelectric conversion element is described.

  Regarding the surface direct thermoelectric conversion element, as described in Non-Patent Document 1, a surface direct thermoelectric conversion element in which a conductive film made of a conductive material having thermoelectric conversion performance and an electrode are joined was examined. However, the thermoelectric conversion element has a problem of high internal resistance.

  Then, an object of this invention is to provide the manufacturing method and thermoelectric conversion element of a thermoelectric conversion element which can reduce internal resistance of a surface normal direction.

  With regard to the above problems, the present inventors have intensively studied. As a result, when the thermoelectric conversion layer is bonded to the electrode in the state of a conductive film that is a solid phase as in the conventional method of manufacturing a thermoelectric conversion element, the interfacial contact resistance between the conductive film and the electrode is high. It has been found that the internal resistance of the thermoelectric conversion element is increased. Based on the result, when joining the electrode layer with a solution containing a conductive polymer having thermoelectric conversion ability, the thermoelectric conversion layer is maintained by keeping the solution in a liquid state and contacting with the solid phase electrode layer. It was found that the interface contact resistance between the electrode and the electrode can be reduced, and the internal resistance in the direction perpendicular to the surface can be reduced.

The present invention provides the following methods (1) to (15) for producing a thermoelectric conversion element and thermoelectric conversion elements.
(1) A bonding step of bonding the first electrode layer and the second electrode layer using a solution containing a conductive polymer having thermoelectric conversion performance, wherein the first electrode that is a solid phase in the bonding step The manufacturing method of the thermoelectric conversion element which has the thermoelectric conversion capability based on the temperature difference of a perpendicular direction which makes a layer and a 2nd electrode layer and the solution which is a liquid phase contact, and forms a thermoelectric conversion layer.
(2) The method for manufacturing a thermoelectric conversion element according to (1), wherein in the joining step, at least one of the first electrode layer and the second electrode layer is placed.
(3) The method for producing a thermoelectric conversion element according to (1) or (2), wherein the liquid phase state of the solution is maintained in the joining step.
(4) The method for producing a thermoelectric conversion element according to (3), wherein the solution is a dispersion containing particles having a conductive polymer in the core.
(5) The method for producing a thermoelectric conversion element according to (3) or (4), wherein the liquid phase retention time of the solution is 1 minute to 2 hours.
(6) The method for manufacturing a thermoelectric conversion element according to any one of (3) to (5), wherein in the bonding step, the liquid phase solution is dried after the liquid phase state of the solution is maintained.
(7) The method for producing a thermoelectric conversion element according to (6), wherein the drying temperature is 40 to 150 ° C. and the drying time is 2 to 15 hours.
(8) The step of laminating the first electrode layer on the first substrate and / or the step of laminating the second substrate on the second electrode layer, the method according to any one of (1) to (7) A method for manufacturing a thermoelectric conversion element.
(9) A thermoelectric conversion element, in which a first electrode layer, a thermoelectric conversion layer containing a conductive polymer having thermoelectric conversion performance, and a second electrode layer are laminated in this order, and the first electrode layer Contact resistance per unit area at the first interface between the first electrode and the thermoelectric conversion layer is less than 0.013 Ω / mm ² , and per unit area at the second interface between the second electrode layer and the thermoelectric conversion layer. The interfacial contact resistance is less than 0.013 Ω / mm ² and has a thermoelectric conversion capability based on a temperature difference in the direction perpendicular to the surface.
(10) The thermoelectric conversion element according to (9), wherein the conductive polymer having thermoelectric conversion performance is a conductive polymer containing an organic conductive polymer constituting a conductive aggregate and a dopant.
(11) The thermoelectric conversion element according to (10), wherein both the first electrode layer and the second electrode layer are in contact with the same conductive aggregate.
(12) The thermoelectric conversion element according to any one of (9) to (11), wherein the thermoelectric conversion layer has a thickness of 0.1 μm to 100 μm.
(13) The thermoelectric device according to any one of (9) to (12), wherein the first electrode layer is stacked on the first substrate and / or the second substrate is stacked on the second electrode layer. Conversion element.
(14) A wearable terminal equipped with the thermoelectric conversion element according to any one of (9) to (13).
(15) A bonding step of bonding the first electrode layer and the second electrode layer using a solution containing a conductive polymer having thermoelectric conversion ability, wherein the first electrode which is a solid phase in the bonding step The layer and the second electrode layer are brought into contact with the liquid phase solution to form a thermoelectric conversion layer, whereby the interface contact resistance at the first interface between the thermoelectric conversion layer, the second electrode layer, and the thermoelectric A method for reducing the internal resistance of a thermoelectric conversion element having a thermoelectric conversion capability based on a temperature difference in a direction perpendicular to the surface, which reduces an interface contact resistance at a second interface with the conversion layer.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method and thermoelectric conversion element of a thermoelectric conversion element which can reduce internal resistance of a perpendicular direction can be provided.

It is a schematic diagram explaining a liquid phase solid phase joining, (a) is a schematic diagram which shows the state in which the solution used for thermoelectric conversion layer shaping | molding of the thermoelectric conversion element is a liquid phase state, (b) is a liquid phase solid phase joining. It is a schematic diagram which shows the state which the electrode layer and the conductive aggregate contacted by. It is sectional drawing which shows the structure of the thermoelectric conversion element of this embodiment. It is process drawing which shows the manufacturing process of the thermoelectric conversion element which concerns on this embodiment. 2 is a graph showing heat cycle characteristics of the thermoelectric conversion element of Example 1. FIG. 5 is a graph showing heat cycle characteristics of the thermoelectric conversion element of Comparative Example 1. It is a schematic diagram which shows the structure of the measurement system which evaluates a thermoelectric conversion element. It is a graph which shows the output characteristic of the thermoelectric conversion module using the thermoelectric conversion element of Example 1 and Comparative Example 1. 3 is a graph showing heat cycle characteristics of a thermoelectric conversion module using the thermoelectric conversion element of Example 1. FIG. 3 is a graph showing heat cycle characteristics of a thermoelectric conversion module using the thermoelectric conversion element of Example 1. FIG. 3 is a graph showing heat cycle characteristics of a thermoelectric conversion module using the thermoelectric conversion element of Example 1. FIG. (A) is the microscope picture which shows the result of having observed the thermoelectric conversion element of Example 1 with the atomic force microscope, (b) is the microscope picture which shows the result of having observed the thermoelectric conversion element of the comparative example 1 with the atomic force microscope. is there. (A) is a microscope picture which shows the result of having observed the thermoelectric conversion element of Example 1 with the electric force microscope, (b) is a microscope picture which shows the result of having observed the thermoelectric conversion element of the comparative example 1 with the electric force microscope. 10 is a process diagram illustrating a manufacturing process of the thermoelectric conversion element of Comparative Example 1. FIG. It is a schematic diagram explaining a solid phase joining, (a) is a schematic diagram which shows the state in which the solution which shape | molds a thermoelectric conversion layer is a liquid phase, (b) is the state where the solution became the thermoelectric conversion layer of the solid phase. (C) is a schematic diagram showing a state in which an electrode layer is laminated on a solid-state thermoelectric conversion layer.

  Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the object of the present invention.

(Method for manufacturing thermoelectric conversion element)
The manufacturing method of the thermoelectric conversion element of the present embodiment includes a bonding step of bonding the first electrode layer and the second electrode layer with a solution containing a conductive polymer having thermoelectric conversion performance. In the bonding step, This is a manufacturing method in which a thermoelectric conversion layer is formed by bringing a first electrode layer and a second electrode layer that are solid phases into contact with a solution that is in a liquid phase state.

  One of the technical features of this production method is that a solution containing a conductive polymer having thermoelectric conversion performance is brought into contact with the first electrode layer and the second electrode layer that are solid phases in a liquid phase state. The point is that "phase solid phase bonding" is performed. When a solution containing a conductive polymer with thermoelectric conversion performance is in a liquid phase state and bonded to a solid phase electrode layer in a liquid phase solid phase, the state of dispersion and aggregation of the conductive polymer in the solution becomes conductive. It tends to be in a good state. Thus, by performing liquid phase solid phase bonding, the interface contact resistance between the thermoelectric conversion layer and the electrode can be reduced, and a thermoelectric conversion element having a low internal resistance in the perpendicular direction can be formed.

  The difference between the method for manufacturing the thermoelectric conversion element of the present embodiment and the method for manufacturing the conventional thermoelectric conversion element will be described below using a case where PEDOT-PSS is used as the conductive polymer as an example. In a conventional method for producing a thermoelectric conversion element, a solution containing a conductive polymer having thermoelectric conversion performance is applied and dried to form a conductive film, and the conductive film and the electrode are bonded. Here, as shown in FIG. 14, the conductive film in the solid state formed before joining to the electrode is composed of a conductive aggregate formed of organic conductive polymer PEDOT by PSS as a dopant. It is considered that a shape covered with the formed insulating portion is formed and solidified. For this reason, even if the said electrically conductive film and an electrode are joined, an insulation site | part (PSS aggregation part) will intervene between a conductive aggregate (PEDOT aggregation part) and an electrode, and a thermoelectric conversion layer (conductive film) The present inventor has inferred that the interface contact resistance between the electrode and the electrode increases.

On the other hand, as shown in FIG. 1, in this production method, a solution containing a conductive polymer is brought into contact with an electrode layer that is a solid phase in a liquid phase state. As shown in FIG. 1A, in the solution, the organic conductive polymer 3a (for example, PEDOT) and the dopant 3b (for example, PSS) constituting the conductive aggregate are in a dispersed state, and then the organic conductive polymer is used. Conductive polymer 3a and dopant 3b are aggregated to form a conductive aggregate (core part) composed of organic conductive polymer 3a, and insulating site (shell part) where dopant 3b covers the conductive aggregate (core part) It is considered that a core-shell type structure (coupling structure) micelle (particle) is formed. Thus, the said solution containing a conductive polymer turns into a dispersion liquid which contains the particle | grains which have a conductive polymer in a core part in a dispersed state. Here, since the solution containing the conductive polymer 3 having the core-shell structure is in a liquid phase state, the micelle is flexible, and the electrode layers 2 and 4 are conductive aggregates that are aggregated portions of PEDOT. It becomes possible to touch. Thus, the inventor has inferred that the interface contact resistance between the thermoelectric conversion layer and the electrode can be lowered.
FIG. 1 is a diagram conceptualizing one embodiment of the dispersion / aggregation state of the conductive polymer in the solution, and the dispersion state of the conductive polymer in the solution is not limited to such an embodiment. . In addition, the above description describes PEDOT-PSS as an example, and the conductive polymer is not limited to PEDOT-PSS, but is limited to containing a core-shell type conductive polymer. Not a thing.

In this embodiment, the liquid phase state means a liquid phase, but (1) a part of the solution is softened, (2) a part of the solution is semi-solid, (3) It may be in a gel state.
Furthermore, a state where a part of the solvent is volatilized by preliminary drying or the like may be used. In the present invention, a liquid phase state is a state in which a solvent or a dispersion medium is contained in a conductive polymer serving as a thermoelectric conversion layer.

  In the bonding step, it is preferable to place at least one of the first electrode layer and the second electrode layer. Since the solution containing the conductive polymer is in a liquid phase state, for example, (1) the electrode layer is pressed hydraulically or pneumatically, (2) a vacuum laminator is used, and (3) the substrate on which the electrode layer is installed. The first electrode layer, the second electrode, and the conductive aggregate that is the aggregated portion of PEDOT can be more reliably brought into contact with each other by a known method such as bonding by its own weight. In order to suppress voids in the thermoelectric conversion element due to (1) deformation of the substrate due to press pressure and (2) rapid drying of the solvent or dispersion medium under vacuum, the mounting method is as follows. A method of bonding by the weight of the installed substrate is preferable. In addition, as long as it can shape | mold so that it may function as a thermoelectric conversion element, about the mounting method, it is not restrict | limited to the said method.

  In the joining step, it is preferable to maintain the liquid phase state of the solution. By maintaining the liquid phase state of the solution, the dispersion state of the conductive polymer in the solution tends to be better. Thereby, it exists in the tendency for the electroconductivity of a thermoelectric conversion layer to improve. In particular, when the conductive polymer is a conductive polymer that forms a core-shell structure (coupling structure) such as PEDOT-PSS, a highly conductive conductive aggregate is formed in the solution. When the conductive aggregate and the electrode layer are connected, the interface contact resistance tends to be reduced.

  The liquid phase state holding time of the solution is preferably 1 minute to 2 hours. When the retention time in the liquid phase state is 1 minute to 2 hours, the dispersion state of the conductive polymer in the solution tends to be better. More preferably, it is 1 minute-1 hour, More preferably, it is 1 minute-0.5 hour.

  In the joining step, it is preferable to dry the solution in the liquid phase state after maintaining the liquid phase state of the solution. Thereby, it exists in the tendency which can form a thermoelectric conversion layer in the state which the electroconductive part and electrode layer in a solution connected reliably.

  The drying temperature is preferably 40 to 150 ° C. The drying time is preferably 2 to 15 hours. In addition, since the drying temperature and the drying time vary depending on the size of the thermoelectric conversion element to be molded, the drying temperature and the drying time may be outside the above ranges.

  In the present embodiment, it is preferable to include a step of laminating the first electrode layer on the first substrate and / or a step of laminating the second substrate on the second electrode layer. By laminating the substrates, the thermoelectric conversion layer and the electrode layer can be protected. In addition, after laminating | stacking a 1st electrode layer and a 1st board | substrate previously, you may carry out liquid phase solid-phase joining. The same applies to the connection between the second electrode layer and the second substrate.

(solution)
The solution used in the production method of the present embodiment preferably contains a solvent such as water, an organic solvent, or a mixed solvent thereof, and a conductive polymer having thermoelectric conversion ability. The solvent will be described later.

(Conductive polymer with thermoelectric conversion ability)
In the present embodiment, the conductive polymer having thermoelectric conversion ability may be a p-type conductive polymer or an n-type conductive polymer. As the p-type conductive polymer or the n-type conductive polymer, an organic conductive polymer constituting a conductive aggregate such as a π-conjugated conductive polymer or a σ-conjugated conductive polymer, and a dopant are used. The combination is mentioned. In the case of a p-type conductive polymer, for example, a π-conjugated conductive polymer is a donor molecule, and a dopant is an acceptor molecule. On the other hand, in the case of an n-type conductive polymer, for example, a π-conjugated conductive polymer is an acceptor molecule, and a dopant is a donor molecule.

  The π-conjugated conductive polymer is not particularly limited as long as it is an organic polymer including a main chain composed of a π-conjugated system. The π-conjugated conductive polymer is preferably a π-conjugated heterocyclic compound or a derivative of a π-conjugated heterocyclic compound because of compound stability and high conductivity.

  Examples of the π-conjugated conductive polymer include aliphatic conjugated polyacetylene, polyacene, polyazulene, aromatic conjugated polyphenylene, heterocyclic conjugated polypyrrole, polythiophene, polyisothianaphthene, and heteroatom-containing polyaniline. , Polythienylene vinylene, mixed conjugated poly (phenylene vinylene), double chain conjugated system having a plurality of conjugated chains in the molecule, derivatives of these conductive polymers, and conjugated high There may be mentioned at least one selected from the group consisting of conductive composites which are polymers obtained by grafting or block copolymerizing molecular chains with saturated polymers.

From the viewpoint of stability in air, polypyrrole, polythiophene and polyaniline or derivatives thereof are preferable, polythiophene, polyaniline, or derivatives thereof (that is, polythiophene, polyaniline, polythiophene derivatives, and polyaniline derivatives) are more preferable, and polythiophene. Or a polythiophene derivative is still more preferable.
The π-conjugated conductive polymer can obtain sufficient conductivity and compatibility with the binder resin even if it is not substituted, but in order to further improve the conductivity and / or compatibility, an alkyl group, a carboxy group It is preferable to introduce a functional group such as a sulfo group, an alkoxy group, or a hydroxy group into the π-conjugated conductive polymer.

As a specific example of the π-conjugated conductive polymer,
Polypyrrole: polypyrrole, poly (N-methylpyrrole), poly (3-methylpyrrole), poly (3-ethylpyrrole), poly (3-n-propylpyrrole), poly (3-butylpyrrole), poly (3 -Octylpyrrole), poly (3-decylpyrrole), poly (3-dodecylpyrrole), poly (3,4-dimethylpyrrole), poly (3,4-dibutylpyrrole), poly (3-carboxypyrrole), poly (3-methyl-4-carboxypyrrole), poly (3-methyl-4-carboxyethylpyrrole), poly (3-methyl-4-carboxybutylpyrrole), poly (3-hydroxypyrrole), poly (3-methoxy Pyrrole), poly (3-ethoxypyrrole), poly (3-butoxypyrrole), poly (3-methyl-4-hexyloxy) Roll),
Polythiophenes: poly (thiophene), poly (3-methylthiophene), poly (3-ethylthiophene), poly (3-propylthiophene), poly (3-butylthiophene), poly (3-hexylthiophene), poly ( 3-heptylthiophene), poly (3-octylthiophene), poly (3-decylthiophene), poly (3-dodecylthiophene), poly (3-octadecylthiophene), poly (3-bromothiophene), poly (3- Chlorothiophene), poly (3-iodothiophene), poly (3-cyanothiophene), poly (3-phenylthiophene), poly (3,4-dimethylthiophene), poly (3,4-dibutylthiophene), poly ( 3-hydroxythiophene), poly (3-methoxythiophene), poly (3-ethoxythio) ), Poly (3-butoxythiophene), poly (3-hexyloxythiophene), poly (3-heptyloxythiophene), poly (3-octyloxythiophene), poly (3-decyloxythiophene), poly ( 3-dodecyloxythiophene), poly (3-octadecyloxythiophene), poly (3-methyl-4-methoxythiophene), poly (3,4-ethylenedioxythiophene) (PEDOT), poly (3-methyl-4 -Ethoxythiophene), poly (3-carboxythiophene), poly (3-methyl-4-carboxythiophene), poly (3-methyl-4-carboxyethylthiophene), poly (3-methyl-4-carboxybutylthiophene) ,
Polyanilines: Polyaniline, poly (2-methylaniline), poly (3-isobutylaniline), poly (2-aniline sulfonic acid), poly (3-aniline sulfonic acid), and the like.

  Examples of the σ-conjugated conductive polymer include poly (methylphenylsilane), poly (methylpropylsilane), poly (phenyl-p-biphenylsilane), poly (dihexylsilane), and the like.

  The dopant is not particularly limited as long as it functions as an acceptor molecule or a donor molecule, but it is preferable to use a polymer dopant having an anion group (also referred to as “polyanion dopant”). By using a π-conjugated conductive polymer in combination with a polymer dopant having an anionic group, it is possible to expect the effects of high conductivity, improved stability over time of conductivity, and improved water resistance in a laminated state. Examples of the polyanion dopant include at least one of substituted or unsubstituted polyalkylene, substituted or unsubstituted polyalkenylene, substituted or unsubstituted polyimide, substituted or unsubstituted polyamide, and substituted or unsubstituted polyester. Examples thereof include a polymer having a structure and a structural unit having an anionic group.

The anionic group of the polyanion _{^{dopant, -O-SO 3 - X +}} , -SO 3 - X +, -COO - X + (. X + is the hydrogen ion in each of the formulas, represents an alkali metal ion), and the like. Among these, from the viewpoint of doping ability of organic conductive polymer _{^{compound, -SO 3 - X +, -COO}} - X + are preferable.

  Among the polyanion dopants, from the viewpoint of solvent solubility and conductivity, a copolymer containing alkylsulfonic acid, a polyisoprenesulfonic acid, a copolymer containing polyisoprenesulfonic acid, polysulfoethyl methacrylate, and polysulfoethyl methacrylate are used. Copolymer containing, poly (4-sulfobutyl methacrylate), copolymer containing poly (4-sulfobutyl methacrylate), polymethallyloxybenzenesulfonic acid, copolymer containing polymethallyloxybenzenesulfonic acid, polystyrene A sulfonic acid (PSS), a copolymer containing polystyrene sulfonic acid, and the like are preferable.

  The alkyl sulfonic acid in the copolymer containing the alkyl sulfonic acid is preferably a linear alkyl sulfonic acid that is easily doped into a conductive polymer from the structural viewpoint. Moreover, a C1-C15 alkylsulfonic acid is preferable from the ease of being doped, A C1-C5 alkylsulfonic acid is more preferable, A C1-C3 alkylsulfonic acid is still more preferable. Preferable specific examples of the alkylsulfonic acid include methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, butanesulfonic acid, and pentanesulfonic acid.

  The dopant is preferably polystyrene sulfonic acid (PSS) or polyvinyl sulfonic acid (PVS), and more preferably PSS, from the viewpoint of stability when doped.

  Specific examples of the combination of a donor molecule and an acceptor molecule as a p-type conductive polymer include polyethylene dioxythiophene / polystyrene sulfonic acid (PEDOT / PSS), polyethylene dioxythiophene / polyvinyl sulfonic acid (PEDOT / PVS), sulfone. Preferred examples include polyaniline (PAS), polyethylenedioxythiophene / p-toluenesulfonic acid ester (tosylate) (PEDOT / TOS), and PEDOT / PSS is preferred. It is also preferable to use PAS in which polyaniline is doped with camphor-sulfonic acid (CSA). In this case, it is preferable to use m-cresol as a solvent.

  The degree of polymerization of the polyanion dopant is preferably in the range of 10 to 100,000 monomer units, and more preferably in the range of 50 to 10,000 from the viewpoint of solvent solubility and conductivity.

  The content of the polyanion dopant is preferably in the range of 0.1 to 10 mol, and more preferably in the range of 1 to 7 mol, with respect to 1 mol of the organic conductive polymer. Here, the number of moles is defined by the number of structural units derived from a monomer containing an anionic group that forms a polyanion dopant and the number of structural units derived from a monomer such as pyrrole, thiophene, or aniline that forms an organic conductive polymer. When the content of the polyanion dopant is 0.1 mol or more with respect to 1 mol of the organic conductive polymer, the doping effect on the organic conductive polymer is increased, and the conductivity is sufficiently exhibited. In addition, the dispersibility and solubility in the solvent are increased, and it is easy to obtain a uniform dispersion. Further, when the content of the polyanion dopant is 10 mol or less with respect to 1 mol of the organic conductive polymer, a large amount of the organic conductive polymer can be contained, and sufficient conductivity can be easily obtained.

(solvent)
The solvent used for the solution is preferably water, an organic solvent, or a mixed solvent thereof. Examples of organic solvents include aprotic polar solvents (DMSO (dimethyl sulfoxide), DMF (N, N-dimethylformamide), NMP (N-methyl-2-pyrrolidone), etc.), aliphatic halogen solvents (dichloromethane). , Chloroform, carbon tetrachloride, ethane dichloride, trichloroethylene, trichloroethane, tetrachloroethylene, etc.), aromatic halogen solvents (chlorobenzene, dichlorobenzene, etc.), aromatic non-halogen solvents (benzene, toluene, xylene, mesitylene, tetralin, tetra) Methyl benzene, pyridine, etc.), ketone solvents (cyclohexanone, acetone, methyl ethyl ketone, etc.), ether solvents (diethyl ether, tetrahydrofuran (THF), t-butyl methyl ether, dimethoxyethane, diglyme) ), Alcohol solvents (alcohols (ethanol, ethylene glycol, etc.) and the like.

(Thermoelectric conversion element)
In the thermoelectric conversion element of this embodiment, a first electrode layer, a thermoelectric conversion layer containing a conductive polymer, and a second electrode layer are laminated in this order, and the first electrode layer and the thermoelectric conversion layer The interfacial contact resistance at the first interface per unit area is less than 0.013 Ω / mm ² , and the interfacial contact resistance at the second interface between the second electrode layer and the thermoelectric conversion layer is It is less than 0.013Ω / mm ² .

  FIG. 2 is a cross-sectional view of the thermoelectric conversion element of this embodiment. As shown in FIG. 2, the thermoelectric conversion element 10 includes a first substrate 1, a first electrode layer 2, a thermoelectric conversion layer 3 containing a conductive polymer, a second electrode layer 4, and a second substrate 5 stacked in this order. ing. A first interface A is formed between the first electrode layer 2 and the thermoelectric conversion layer 3, and a second interface B is formed between the second electrode layer 4 and the thermoelectric conversion layer 3.

The interface contact resistance per unit area in the first interface A and the interface contact resistance per unit area in the second interface B are each 0.013 Ω / mm ² . Thus, the internal resistance of the surface direct thermoelectric conversion element is reduced by the low contact resistance value at the interface between the electrode layer and the thermoelectric conversion layer. The interface contact resistance per unit area in the first interface A and the second interface B is independently preferably 0.007Ω / mm ² or less, more preferably 0.003Ω / mm ² or less.

  The thermoelectric conversion layer 3 preferably has a structure in which an organic conductive polymer and a dopant in a conductive polymer having thermoelectric conversion capability are coupled. Further, the organic conductive polymer may form a conductive core layer (conductive aggregate), and the shell layer may be formed so that the periphery of the conductive core layer is covered with the dopant. When the shell layer containing the dopant covers the conductive core layer, in the conventional manufacturing method, the contact between the electrode layer and the conductive core layer is inhibited, and the internal resistance is increased. However, according to the manufacturing method of the present embodiment, the electrode layer and the conductive aggregate (conductive property) are used in order to bring the electrode layer into contact with the solution containing the conductive polymer having thermoelectric conversion capability by liquid phase solid phase bonding. The core layer) is connected, the interface contact resistance is reduced as compared with the conventional case, and the internal resistance of the thermoelectric conversion element is reduced.

  Both the first electrode layer and the second electrode layer are preferably in contact with the same conductive aggregate. When the first and second electrode layers are in contact with the same conductive aggregate, the internal resistance of the thermoelectric conversion element tends to be reduced. In addition, when several electroconductive aggregates are connected within the thermoelectric conversion layer, the electrode layer should just be in contact with one of the electroconductive aggregates.

  The thickness of the thermoelectric conversion layer is preferably 0.1 μm to 100 μm. Since the thermoelectric conversion layer contains a conductive polymer, if the thickness is in the range, the thermoelectric conversion layer tends to be a flexible thermoelectric conversion element. The thickness of the thermoelectric conversion layer is more preferably 1 μm to 80 μm, still more preferably 5 μm to 40 μm. For example, when the thermoelectric conversion element is not used for a flexible application, the thickness of the thermoelectric conversion layer may be thicker than the range.

(Electrode layer)
The metal which comprises the 1st electrode layer and 2nd electrode layer in this embodiment is not specifically limited, The 1st electrode layer and the 2nd electrode layer may be comprised from the same metal, and may not be comprised. Examples of the metal used for the first electrode layer 2 and the second electrode layer 4 include Ag, Au, Pt, Cu, Al, Zn, Ni, Mg, Rh, Ir, W, Co, Ru, In, Os, Fe, Pd, Ta, Nb, Cr, Ga, Pb, Re, V, Hf, Zr, Ti, Sn, Mn and the like can be mentioned. Of these, Ag, Au, Pt, Cu, Al, Zn, and Ni are preferable, and Ag, Au, Pt, and Ni are more preferable. Moreover, these may be used independently and may use 2 or more types together.

  In the said metal, since interface contact resistance with a thermoelectric conversion layer becomes small, it is preferable to use a metal with a large work function. Specifically, it is preferable to use a metal having a work function of 3.0 eV or more, more preferably a metal having a work function of 3.5 eV or more, and further using a metal having a work function of 4.0 eV or more. preferable. Moreover, the upper limit of a work function is not specifically limited, For example, 6 eV or less may be sufficient. The metal work function can be measured by a photoelectron emission method.

Further, the resistivity of the metal is not particularly limited, for example, can be used ones ^{0.1 × 10 -8 Ωm~100 × 10 -8} Ωm, better low metal resistivity, Since the interface contact resistance with the thermoelectric conversion layer 2 of the said metal becomes small, it is preferable to use a metal with low resistivity. In this respect, it is preferable to use a metal having a resistivity of 30 × 10 ⁻⁸ Ωm or less, more preferable to use a metal having a resistivity of 10 × 10 ⁻⁸ Ωm or less, and a resistivity of 5 ×. It is more preferable to use a metal that is 10 ⁻⁸ Ωm or less. In addition, the resistivity of a metal can be measured by the four probe method.

  The layer thicknesses of the first electrode layer and the second electrode layer are not limited, and may be, for example, 0.01 to 200 μm. If the layer thickness is too small, the interface contact resistance with the thermoelectric conversion layer increases. In view of the tendency, it is preferably 0.1 μm or more, more preferably 1 μm or more, and further preferably 5 μm or more. On the other hand, if the layer thickness is too large, the cost tends to be too high. From these viewpoints, the thicknesses of the first electrode layer 1 and the second electrode layer 2 are preferably 50 μm or less, more preferably 30 μm or less, and further preferably 15 μm or less.

(substrate)
Although the material of the board | substrate (1st board | substrate, 2nd board | substrate) in this embodiment is not specifically limited, An insulating material is preferable. Examples of such materials include polyimide resins, polyamide resins, epoxy resins, methacrylic resins, polysulfone resins, vinyl chloride resins (for example, polyvinyl chloride), polyester resins (for example, polyethylene terephthalate), and the like. An organic insulating material such as SiO ₂ , Al ₂ O ₃ , TiO ₂ , Ta ₂ O ₅ , and ZrO ₂ can be used. Among these, it is preferable to use a polyimide resin or a polyamide resin because of excellent flexibility and heat resistance. These may be used alone or in combination of two or more. By using a substrate material that is excellent in flexibility, a flexible thermoelectric conversion element can be realized.

  The thickness of the substrate is preferably 1 μm to 200 μm. If the thickness of the substrate is within this range, it tends to be a flexible thermoelectric conversion element. The thickness of the substrate is more preferably 10 μm to 125 μm, still more preferably 10 μm to 25 μm. Note that, for example, when the thermoelectric conversion element is not used for a flexible application, the thickness of the substrate may be thicker than the range.

  The thermoelectric conversion element of this embodiment can generate power even if the temperature difference is around 1K. Therefore, it can be preferably used as a power source for a wearable terminal continuously worn on the user's human body as a power source that does not require charging and is advantageous for downsizing.

(Internal resistance reduction method)
The method for reducing the internal resistance of the thermoelectric conversion element of the present embodiment includes a joining step of joining the first electrode layer and the second electrode layer using a solution containing a conductive polymer having thermoelectric conversion ability, In the bonding step, the first electrode layer and the second electrode layer that are solid phases are brought into contact with the solution that is a liquid phase to form a thermoelectric conversion layer, thereby forming a first interface between the thermoelectric conversion layer and the thermoelectric conversion layer. In this method, the interface contact resistance and the interface contact resistance at the second interface between the second electrode layer and the thermoelectric conversion layer are reduced.
Thereby, the internal resistance of the thermoelectric conversion element can be reduced.

Examples of the present invention will be described in detail below, but the present invention is not limited to the following examples.
<Example 1>
As shown in FIG. 3, first, a first substrate 1 made of polyimide is prepared. This first substrate 1 is placed in a beaker containing ethanol, placed in an ultrasonic cleaning machine in a state immersed in ethanol, and subjected to ultrasonic waves for 30 minutes. Washing was performed (S1). A silver paste was printed on the cleaned first substrate 1 by a screen printer and dried at 120 ° C. for 1 hour to form the first electrode layer 2 on the first substrate 1 (S2). A silver paste was printed on the second substrate 5 cleaned in the same manner by a screen printing machine and dried at 120 ° C. for 1 hour to form the second electrode layer 4 on the second substrate 5 (S3). About the sample after 1st electrode layer 2 formation, masking was performed using the Kapton tape (trademark) (S4).

Next, in a screw tube bottle washed with ethanol and pure water, PEDOT: PSS (Clevios ^™ : PH1000, manufactured by Heraeus) and dimethyl sulfoxide (DMSO) (manufactured by SIGMA-ALDRICH, 472301-100ML), PEDOT: PSS and DMSO were added together with a stir bar so that the ratio was 20: 1. Then, the lid was closed, and the mixture was placed on a stirrer, and the screw tube bottle was covered with aluminum foil so that no light was applied, and stirring was performed with a stirrer for 1 hour. During this 1 hour of stirring, plasma hydrophilic treatment (17 kV) is performed using an atmospheric pressure helium plasma apparatus on each electrode forming side (only one side) of the first substrate 1 and the second substrate 5 where the masking is completed. , 8.0 L / min) (S5).

During the stirring for 1 hour, the first substrate 1 on which masking was completed was attached to the petri dish with Kapton tape. Then, casting was performed using a solution containing PEDOT: PSS that had been agitated to 1.0 μL / mm ² (S6). While the solution containing PEDOT: PSS is in a liquid phase state, the second substrate 5 on which the second electrode layer 4 is formed is placed on the solution so that the second electrode layer 4 faces the first electrode layer 2. The sample in this state was placed on a petri dish and kept in a liquid phase for 1 minute. Thereafter, the sample was placed on a hot plate (set temperature: 40 ° C.) and dried for 15 hours (S7). At this time, the petri dish was covered with aluminum foil so that light did not hit the sample.

  Immediately after the drying for 15 hours, the sample was put in a vacuum dryer, and vacuuming was performed first. While vacuuming, vacuum drying was performed at 110 ° C. for 2 hours (S8). After drying, when the temperature inside the dryer was lower than 40 ° C., vacuum drying was performed again at 150 ° C. for 2 hours (S9).

  After drying at 150 ° C. for 2 hours, the sample was taken out when the temperature in the dryer became 34 ° C. or lower. The thermoelectric conversion element which consists of the 1st board | substrate 1, the 2nd electrode layer 2, the thermoelectric conversion layer 3 which consists of PEDOT: PSS, the 2nd electrode layer 4, and the 2nd board | substrate 5 by the above operation was produced (S10). In addition, the layer thickness of the 1st electrode layer 2 and the 2nd electrode layer 4 was 12.9 micrometers, respectively, and the thickness of the thermoelectric conversion layer 3 was 5.6 micrometers.

<Comparative Example 1>
FIG. 13 is a flowchart showing a manufacturing process of the thermoelectric conversion element according to Comparative Example 1. As shown in FIG. 13, first, a substrate made of polyimide was prepared, and this substrate was put into a beaker containing ethanol, placed in an ultrasonic cleaner while immersed in ethanol, and subjected to ultrasonic cleaning for 30 minutes (S11). ). A silver paste was printed on the cleaned substrate with a screen printer and dried at 120 ° C. for 1 hour to form the first electrode layer 2 on the substrate 1 (S12). About the sample after 1st electrode layer formation, masking was performed using the Kapton tape (trademark) (S13).

Next, in a screw tube bottle washed with ethanol and pure water, PEDOT: PSS (Clevios ^™ : PH1000, manufactured by Heraeus) and dimethyl sulfoxide (DMSO) (manufactured by SIGMA-ALDRICH, 472301-100ML), PEDOT: PSS and DMSO were added together with a stir bar so that the ratio was 20: 1. Then, the lid was closed, and the mixture was placed on a stirrer, and the screw tube bottle was covered with aluminum foil so that no light was applied, and stirring was performed with a stirrer for 1 hour.

During the stirring for 1 hour, plasma hydrophilic treatment (conditions of 17 kV, 8.0 L / min) was performed on the substrate on which masking was completed (S14), and then the substrate was attached to the petri dish with Kapton tape. Then, casting was performed using a solution containing PEDOT: PSS that had been agitated to 1.0 μL / mm ² (S15). The sample in this state was placed on a petri dish and placed on a hot plate (set temperature: 40 ° C.) and dried for 15 hours. At this time, the petri dish was covered with an aluminum foil so that light did not strike the sample (S16).

  Immediately after the drying for 15 hours, the sample was put in a vacuum dryer, and vacuuming was performed first. While vacuuming, vacuum drying was performed at 110 ° C. for 2 hours (S17). After drying, when the temperature in the dryer fell below 40 ° C, vacuum drying was performed again at 150 ° C for 2 hours (S18).

  After drying at 150 ° C. for 2 hours, the sample was taken out when the temperature in the dryer became 34 ° C. or lower. And Ag paste was printed on the said thermoelectric conversion layer with the screen printer, and it was made to dry at 120 degreeC for 1 hour, and the 2nd electrode layer was created (S18). The thermoelectric conversion element which consists of a board | substrate, the 1st electrode layer, the thermoelectric conversion layer which consists of PEDOT: PSS, and the 2nd electrode layer by the above operation was created. The thickness of the first electrode layer was 16.5 μm, and the thickness of the thermoelectric conversion layer was 6.6 μm.

<Evaluation 1>
A plurality of samples (a pair) prepared by the manufacturing method described in Example 1 and Comparative Example 1 were left to return to room temperature after heating at 120 ° C. for 1 hour, and then the resistance was measured. This process was defined as one cycle, and a heat resistance test was performed in which heating and cooling were performed under the same conditions and measurement of resistance was repeated. The results are shown in FIGS.

  As can be seen from the results in FIG. 4, all of the samples (No. 1 to No. 6) produced by the manufacturing method of Example 1 remained at a resistance value of about 0.3Ω even when the number of cycles increased. , Confirmed to have good thermal stability. On the other hand, as can be seen from the results of FIG. 5, the contact resistance of the plurality of samples (No. 7 to No. 10) produced by the manufacturing method of Comparative Example 1 is significantly higher than that of the sample of Example 1. It was confirmed that the contact resistance increased to 40Ω at the sixth cycle every time the heat cycle was repeated. No. 7-No. In the sample No. 9, the electrode of the element cracked due to heating, and measurement was impossible. It was found that the shrinkage of the thermoelectric conversion layer due to heating caused cracks in the silver electrode.

<Evaluation 2>
The output characteristics of the thermoelectric conversion module including the thermoelectric conversion elements manufactured in Example 1 and Comparative Example 1 were evaluated by the measurement system shown in FIG.
Measurement system shown in Figure 6, a sample 20 to be measured has a heating portion 22 of copper block heated by a heater 21 having a hot side thermocouple T _H, the low-temperature-side thermocouple T _L water cooling The measurement is performed by a voltmeter (digital multimeter (DMM)) 25 and an ammeter (DMM) 26 using a load resistance RL, sandwiched between a cooling portion 24 made of a copper block cooled by a device 23. The lead wires 27 and 28 are insulated using polyimide so as not to contact the copper blocks of the heating portion 22 and the cooling portion 24. In order to improve the thermal contact between the sample 20, the heating part 22 and the copper block of the cooling part 24, heat conductive grease was applied.
Various conditions of Example 1 and Comparative Example 1 are as follows.
Number of elements N = 7
Thickness of the element of Example 1 = 31.4 μm, Thickness of the element of Comparative Example 1 = 39.6 μm
(The thickness of the element was the sum of the thicknesses of the thermoelectric conversion layer, the first electrode layer, and the second electrode layer.)
Element width = 5 mm
Effective length L of element = 6mm
(The width and effective length of the element were the width and effective length of the thermoelectric conversion layer.)
Conductivity σ (resistivity ρ = 1 / σ) = 600 S / cm

The results are shown in FIG. In FIG. 7, a graph a shows the relationship between the current I and the output P of the thermoelectric conversion module made of the thermoelectric conversion element manufactured in Example 1, and a graph b shows the thermoelectric conversion made by the thermoelectric conversion element manufactured in Comparative Example 1. The relationship between the electric current I and the output P of a conversion module is shown. Moreover, the graph of c is the relationship between the electric current I and the voltage V of the thermoelectric conversion module which consists of the thermoelectric conversion element produced in Example 1, The graph of d is a thermoelectric conversion module which consists of the thermoelectric conversion element produced in the comparative example 1. The relationship between current I and voltage V is shown. The following formulas are used to calculate the theoretical values of the open circuit voltage V ₀ , the short circuit current I ₀ , the internal resistance R ₀ , and the maximum output P _max shown in Table 1.

From the results of FIG. 7 and Table 1, in the thermoelectric conversion module using the thermoelectric conversion element of Example 1, the resistance is reduced and the output is improved compared to the thermoelectric conversion module using the thermoelectric conversion element of Comparative Example 1. Was confirmed. Thus, in Example 1 in which the electrode was bonded when the solution used to form the thermoelectric conversion layer was in a liquid phase state, the electrode was bonded when the thermoelectric conversion layer was in a solid phase state. Compared to 1, the interface contact resistance between the electrode and the thermoelectric conversion layer is small, and the power loss is small. The theoretical value of the internal resistance _R0 is much lower than the measured value. The main cause is considered as follows. In a conductive polymer such as PEDOT: PSS, electrons are delocalized along the conjugated system, and thus high electrical conductivity is exhibited. However, in the perpendicular direction, the PEDOT: PSS molecular chain has a stacking structure due to π-π interaction, and the distance between the conductive PEDOT chains becomes long, so that the electric conductivity of the perpendicular plane is in the in-plane direction. Is estimated to be lower.

<Evaluation 3>
The output characteristics in the heat cycle (high temperature side 60 ° C., low temperature side 20 ° C.) of the thermoelectric conversion elements produced in the above examples were evaluated. The open-circuit voltage V ₀ of these thermoelectric conversion elements was adjusted so as to be a temperature difference ΔT = 1.0K considered for practical use. FIG. 8 shows the open circuit voltage, and FIGS. 9 and 10 show the internal resistance.

  From the results of FIGS. 9 to 10, it was confirmed that the internal resistance changed substantially from about 6.4Ω, the maximum output Pmax was maintained at 0.47 μW, and high stability was obtained.

<Evaluation 4>
The electrical characteristics of the surface of the thermoelectric conversion layer from which the second electrode was peeled off in the thermoelectric conversion element of Example 1 and the surface of the conductive film layer before the second electrode was laminated in the thermoelectric conversion element of Comparative Example 1 FIG. 11 shows the results of observation with an atomic force microscope (AFM mode) (MFP-3D-Origin AFM, manufactured by Oxford Instruments). Moreover, the result of having observed these surfaces with the electric force microscope (EFM mode) (The Oxford Instruments company make, MFP-3D-Origin) is shown in FIG. While the surface of the conductive film of Comparative Example 1 shown in FIG. 12B (surface joined to the electrode) is uniformly smoothed, the conductive film of Example 1 shown in FIG. It was confirmed that the surface (surface joined to the electrode) has large irregularities. From these results, the convex part which is not seen in the conductive film surface of the comparative example 1 in the surface of the conductive film of Example 1 suggests that PEDOT which is an electroconductive aggregate is obvious. it is conceivable that.

<Evaluation 5>
In order to measure the interface contact resistance in the thermoelectric conversion element of Example 1, a substrate coated with a release agent was prepared. The first electrode layer and the release agent-coated substrate are liquid phase solid-phase bonded in the same manner as in Example 1, and the laminate having the first electrode layer and the thermoelectric conversion layer is formed by peeling the release agent-coated substrate after bonding. Got. Terminals (one on the first electrode layer side and the other on the thermoelectric conversion layer side) were attached to both ends of the laminate, and a constant current source was connected between the terminals to allow a constant current to flow through the laminate. Using the potential at the terminal position on the electrode layer side as a reference, the potential was measured by applying a probe to a position away from the terminal. The position of the probe was moved in the direction of the thermoelectric conversion layer, and the potential at each position was measured. From the potential difference and current value generated at the interface between the electrode layer and the thermoelectric conversion layer, the interface contact resistance per unit area of the interface (first interface) of the laminate that is a part of the thermoelectric conversion element of Example 1 Was found to be in the range of 0.00007 to 0.013 Ω / mm ² . Similarly, a laminate having the second electrode layer and the thermoelectric conversion layer was obtained, and the interface contact resistance per unit area of the interface (second interface) between the second electrode layer and the thermoelectric conversion layer was also obtained. However, the range was 0.00007 to 0.013 Ω / mm ² . On the other hand, when the interfacial contact resistance of the thermoelectric conversion element of Comparative Example 1 was determined in the same manner as in Example 1, it was higher than 0.013 Ω / mm ² and significantly increased compared to Example 1 (0.107 Ω). / mm ² ).

DESCRIPTION OF SYMBOLS 1 Board | substrate 2 1st electrode layer 3 Thermoelectric conversion layer 4 2nd electrode layer 5 Board | substrate

Claims (15)

A bonding step of bonding the first electrode layer and the second electrode layer using a solution containing a conductive polymer having thermoelectric conversion ability;
In the joining step, the first electrode layer and the second electrode layer that are solid phases and the solution that is a liquid phase are brought into contact with each other to form a thermoelectric conversion layer. A method for producing a thermoelectric conversion element having conversion ability.   The method for manufacturing a thermoelectric conversion element according to claim 1, wherein at least one of the first electrode layer and the second electrode layer is placed in the joining step.   The method for manufacturing a thermoelectric conversion element according to claim 1, wherein the liquid phase state of the solution is maintained in the joining step.   The manufacturing method of the thermoelectric conversion element of Claim 3 whose said solution is a dispersion liquid containing the particle | grains which have the said conductive polymer in a core part.   The manufacturing method of the thermoelectric conversion element of Claim 3 or 4 whose liquid phase holding time of the said solution is 1 minute-2 hours.   The method for manufacturing a thermoelectric conversion element according to any one of claims 3 to 5, wherein, in the joining step, the solution is dried after the liquid phase state of the solution is maintained.   The method for producing a thermoelectric conversion element according to claim 6, wherein the drying temperature is 40 to 150 ° C. and the drying time is 2 to 15 hours.   The thermoelectric device according to any one of claims 1 to 7, comprising a step of laminating the first electrode layer on the first substrate and / or a step of laminating the second substrate on the second electrode layer. A method for manufacturing a conversion element. A thermoelectric conversion element,
The first electrode layer, the thermoelectric conversion layer containing a conductive polymer having thermoelectric conversion performance, and the second electrode layer are laminated in this order,
The interface contact resistance per unit area at the first interface between the first electrode layer and the thermoelectric conversion layer is less than 0.013 Ω / mm ² ;
The interface contact resistance per unit area at the second interface between the second electrode layer and the thermoelectric conversion layer is less than 0.013 Ω / mm ² and has a thermoelectric conversion capability based on a temperature difference in the perpendicular direction. Thermoelectric conversion element.   The thermoelectric conversion element according to claim 9, wherein the conductive polymer having thermoelectric conversion performance includes an organic conductive polymer constituting a conductive aggregate and a dopant.   The thermoelectric conversion element according to claim 10, wherein both the first electrode layer and the second electrode layer are in contact with the same conductive aggregate.   The thermoelectric conversion element as described in any one of Claims 9-11 whose thickness of the said thermoelectric conversion layer is 0.1 micrometer-100 micrometers.   The thermoelectric conversion according to any one of claims 9 to 12, wherein the first electrode layer is laminated on the first substrate and / or the second substrate is laminated on the second electrode layer. element.   A wearable terminal on which the thermoelectric conversion element according to any one of claims 9 to 13 is mounted. A bonding step of bonding the first electrode layer and the second electrode layer using a solution containing a conductive polymer having thermoelectric conversion ability;
In the bonding step, the first electrode layer and the second electrode layer that are solid phases are brought into contact with the solution that is a liquid phase to form a thermoelectric conversion layer,
An interface contact resistance at the first interface between the thermoelectric conversion layer and an interface contact resistance at the second interface between the second electrode layer and the thermoelectric conversion layer is reduced. The internal resistance reduction method of the thermoelectric conversion element which has the thermoelectric conversion capability based.