JP2015050426A - Thermoelectric conversion element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable thermoelectric conversion element having a proper upper electrode.SOLUTION: A thermoelectric conversion element includes: a lower electrode formed on a substrate; a thermoelectric conversion layer formed to cover a part of the lower electrode; and an upper electrode formed along on the substrate spaced apart from the lower electrode and a surface of the thermoelectric conversion layer and provided so as to sandwich the thermoelectric conversion layer together with the lower electrode. In the cross-sectional shape of the thermoelectric conversion layer, a region facing the upper electrode and descending toward the substrate is tilted so as to be gradually spaced apart from an end part of the lower electrode in a conduction direction.

Description

  The present invention relates to a thermoelectric conversion element. Specifically, the present invention relates to a highly reliable thermoelectric conversion element having an appropriate upper electrode.

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 power generation element using a thermoelectric conversion element can be easily obtained without incurring operating costs by providing it at a site where heat is exhausted, such as an incinerator or various facilities in a factory.

  As a thermoelectric conversion module using such a thermoelectric conversion element, Patent Document 1 discloses that the cross-sectional shape of a wiring conductor that electrically connects thermoelectric conversion layers arranged on a substrate is rectangular or inverted trapezoidal. Thus, there is described a thermoelectric conversion module in which the positional deviation of the element and the gap between the joint portions are eliminated and the reliability is improved.

  Further, in Patent Document 2, in a thermoelectric conversion element, a ridge and / or apex of a rectangular parallelepiped thermoelectric conversion element body is chamfered, and the ridge and / or apex is covered with a film of silica or the like, thereby increasing the temperature. The thermoelectric conversion element which suppressed the characteristic fall under the environment is described.

Japanese Patent Laying-Open No. 2005-136075 JP 2009-32893 A

  As an example, the thermoelectric conversion element has a configuration in which a thermoelectric conversion layer containing a thermoelectric conversion material (or made of a thermoelectric conversion material) is sandwiched between electrode pairs, and a heat source is arranged on one electrode side, Electric power is generated by causing a temperature difference in the thermoelectric conversion layer between the heat source side and the opposite side.

As a thermoelectric conversion module in which a plurality of such thermoelectric conversion elements are connected in series, a lower electrode formed on the substrate surface, a thermoelectric conversion layer formed on the substrate covering a part of the lower electrode, A configuration in which thermoelectric conversion elements having an upper electrode formed on a thermoelectric conversion layer are arranged in a line and a lower electrode and an upper electrode of adjacent elements are connected is exemplified.
In this case, the upper electrode is connected to the lower electrode of the adjacent element, extends from the substrate so as to stand along the side surface of the thermoelectric conversion layer, and reaches the upper surface of the thermoelectric conversion layer. .

  However, in the conventional thermoelectric conversion element, the upper electrode cannot be properly formed, and a thin portion or a broken portion is generated, and the conductivity is reduced.

Furthermore, the thermoelectric conversion element can improve power generation efficiency, so that the temperature difference of the thermoelectric conversion layer in the direction between electrodes is large. Therefore, in order to perform efficient power generation, it is necessary to make the thermoelectric conversion layer a certain size in the direction between the electrodes and to make a temperature difference in this direction.
However, in this case, the upper electrode formed along the side surface of the thermoelectric conversion layer becomes longer, and it becomes more difficult to properly form the upper electrode.

  An object of the present invention is to solve such problems of the prior art, and in a thermoelectric conversion element having a substrate, a lower electrode, a thermoelectric conversion layer, and an upper electrode, there is no appropriate breakage or the like. It is an object of the present invention to provide a highly reliable thermoelectric conversion element that has an upper electrode and does not have a decrease in conductivity due to breakage of the upper electrode or the like.

In order to achieve such an object, the thermoelectric conversion element of the present invention comprises a substrate,
A lower electrode formed on the substrate;
A thermoelectric conversion layer formed on the substrate, covering a part of the lower electrode;
An upper electrode that is formed along the surface of the thermoelectric conversion layer rising from the substrate from a position separated from the lower electrode and then rising along the surface of the thermoelectric conversion layer. Have
Furthermore, the cross-sectional shape of the thermoelectric conversion layer in the energizing direction of the lower electrode and the upper electrode on the substrate faces the upper electrode, and the region descending toward the substrate is from the end of the lower electrode in the energizing direction, A thermoelectric conversion element characterized by having a shape that is gradually inclined to be separated.

In such a thermoelectric conversion element of the present invention, it is preferable that at least the upper surface of the thermoelectric conversion layer does not have a concave portion.
Further, when viewed in a direction perpendicular to the substrate, the upper electrode and the lower electrode have a region that overlaps, and the region in which the upper electrode and the lower electrode overlap is regarded as the upper surface of the thermoelectric conversion layer. preferable.
Moreover, it is preferable that a thermoelectric conversion layer has a plane area | region on an upper surface.
Moreover, it is preferable that the cross-sectional shape of the thermoelectric conversion layer is a trapezoid.
Moreover, it is preferable that the lower end of the end portion on the upper electrode side of the thermoelectric conversion layer in the energization direction is located on the substrate side with respect to the upper surface of the lower electrode.
Further, when the length of the thermoelectric conversion layer in the energizing direction is L1, and the height of the thermoelectric conversion layer from the substrate is L2, it is preferable that “L2 / L1> 0.05” is satisfied.
The thermoelectric conversion layer is preferably formed by dispersing a material having a thermoelectric conversion function in a resin material.
Furthermore, the resin material is preferably formed of a thermosetting resin or an ultraviolet curable resin.

  According to the present invention, in the thermoelectric conversion element having the substrate, the lower electrode, the thermoelectric conversion layer, and the upper electrode, the size (thickness) of the thermoelectric conversion layer between the lower electrode and the upper electrode is set. Even if the size is increased, a highly reliable thermoelectric conversion element having an appropriate upper electrode having no breakage, a thin film portion, or the like, and having no decrease in conductivity due to the breakage of the upper electrode or the like can be obtained.

It is a perspective view which shows notionally an example of the thermoelectric conversion element of this invention. It is a figure which shows notionally the II-II sectional view taken on the line of FIG. It is a figure which shows notionally the cross section of another example of the thermoelectric conversion element of this invention. It is a figure which shows notionally the cross section of another example of the thermoelectric conversion element of this invention. It is a figure which shows notionally the cross section of an example of the conventional thermoelectric conversion element. (A) And (B) is a figure which shows notionally an example of the shape of the upper surface of a thermoelectric conversion element.

  Hereinafter, the thermoelectric conversion element of the present invention will be described in detail based on a preferred embodiment shown in the accompanying drawings.

  1 and 2 conceptually show an example of the thermoelectric conversion element of the present invention. 1 is a perspective view, and FIG. 2 is a cross-sectional view taken along line II-II in FIG.

As shown in FIGS. 1 and 2, the thermoelectric conversion element 10 basically includes a substrate 12, a lower electrode 14, a thermoelectric conversion layer 16, and an upper electrode 18.
Specifically, the lower electrode 14 is formed on the substrate 12. The thermoelectric conversion layer 16 is formed on the substrate 12 so as to cover a part of the lower electrode 14. The upper electrode 18 extends from the position separated from the lower electrode 14 on the substrate 12 toward the lower electrode 14, rises from the substrate 12, and extends along the side surface and the upper surface of the thermoelectric conversion layer 16.

  In addition, in the thermoelectric conversion element 10 of the present invention, in addition to the illustrated components, the substrate 12 and the lower electrode 14, the substrate 12 and the thermoelectric conversion layer 16, and the substrate 12 and the upper portion, as necessary. A layer (film) such as an easy adhesion layer or an adhesion improving layer may be provided between the electrode 18, the lower electrode 14 and the thermoelectric conversion layer 16, or between the thermoelectric conversion layer 16 and the upper electrode 18. Moreover, in order to improve the formability and adhesion of each layer, surface modification treatment such as primer treatment or surface roughening treatment may be performed.

In the thermoelectric conversion element 10 of the present invention, the substrate 12 is a glass plate, a ceramic plate, a metal plate having an insulating layer on the surface, a plastic film, an aluminum sheet formed with an anodized film on the surface, etc. As long as the region where the thermoelectric conversion layer is formed) is insulative and has sufficient heat resistance against the formation of the electrodes and thermoelectric conversion layer 16 described later, materials made of various materials can be used.
Preferably, a plastic film is used for the substrate 12. By using a plastic film for the substrate 12, it is possible to reduce the weight and reduce the cost and to form a flexible thermoelectric conversion element 10 (that is, a flexible thermoelectric conversion module), which is preferable.

Specific examples of plastic films that can be used for the substrate 12 include polyethylene terephthalate, polyethylene isophthalate, polyethylene naphthalate, polybutylene terephthalate, poly (1,4-cyclohexylenedimethylene terephthalate), polyethylene-2,6- Polyester resin such as phthalenedicarboxylate, polyimide, polycarbonate, polypropylene, polyethersulfone, cycloolefin polymer, polyetheretherketone (PEEK), triacetylcellulose (TAC) resin, glass epoxy, liquid crystalline polyester, etc. A film (sheet-like material) is exemplified.
Further, as a material for forming the substrate 12, a copolymer of these resin materials or a mixture of these materials can be used.

  Among them, polyethylene terephthalate, polyethylene naphthalate, polyimide, polyether, etc., in addition to easy availability and economy, no dissolution by solvent, and formation of electrodes and thermoelectric conversion layer 16 by coating or printing is possible. Preferred examples include ether ketone, polycarbonate, glass epoxy, and liquid crystalline polyester. Among these, a film made of polyethylene terephthalate, polyethylene naphthalate, polyimide, polycarbonate or the like is particularly preferably exemplified.

What is necessary is just to set the thickness of the board | substrate 12 suitably according to the intensity | strength, flexibility, weight, size, etc. which are calculated | required by the thermoelectric conversion element 10. FIG.
Specifically, the thickness of the substrate 12 is preferably 5 to 1000 μm. Among these, from the viewpoint of flexibility and weight reduction, the thickness of the substrate 12 is more preferably 10 to 500 μm, and particularly preferably 10 to 250 μm.

A lower electrode 14 is formed on the substrate 12 (surface / main surface).
In the thermoelectric conversion element 10, electric power (electric energy) generated by heating or the like is taken out by connecting wiring to the lower electrode 14 and the upper electrode 18. Further, by arranging the thermoelectric conversion elements 10 as appropriate and electrically connecting the lower electrode 14 and the upper electrode 18 of the adjacent thermoelectric conversion elements 10, a plurality of the thermoelectric conversion elements 10 of the present invention, A thermoelectric conversion module connected in series can be formed.

The thickness and size of the lower electrode 14 may be set as appropriate according to the size of the thermoelectric conversion element 10 to be formed and the like so that the generated power can be reliably extracted without loss. It should be noted that the thickness of the lower electrode 14 is preferably 50 to 2000 nm in terms of obtaining sufficient electrical conductivity.
In the illustrated example, the lower electrode 14 has a rectangular shape, but various shapes such as a circular shape can be used in addition to the rectangular shape.

The lower electrode 14 can be formed of various materials as long as it has necessary conductivity.
Specifically, materials used as transparent electrodes in various devices such as metal materials such as copper, silver, gold, platinum, nickel, chromium, and copper alloys, and indium tin oxide (ITO) and zinc oxide (ZnO). Etc. are exemplified. Especially, copper, gold | metal | money, platinum, nickel, a copper alloy etc. are illustrated preferably, Gold, platinum, nickel is illustrated more preferably.
The lower electrode 14 is a layer made of a plurality of materials, such as a laminated structure of a chromium layer and a gold layer, in order to improve the adhesion of the electrode that substantially extracts electric power from the thermoelectric conversion layer 16 and outputs it to the outside. The structure formed by laminating (films) may be used.

A thermoelectric conversion layer 16 is formed on the substrate 12 so as to cover a part of the lower electrode 14.
The thermoelectric conversion element 10 has a difference in carrier density in this direction inside the thermoelectric conversion layer 16 due to a temperature difference in one direction due to heating by contact with a heat source, for example. , Power is generated. In the illustrated example, for example, a heat source is provided on the upper surface side of the thermoelectric conversion layer 16, and power is generated by generating a temperature difference between the upper electrode 18 and the lower electrode 14.

In the thermoelectric conversion element 10 of the present invention, the thermoelectric conversion layer 16 can use all the various configurations using known thermoelectric conversion materials.
Specifically, thermoelectric conversion materials such as conductive polymers, organic materials such as conductive nanocarbon materials, nanometal materials (metal-containing conductive nanomaterials), inorganic materials such as inorganic oxide semiconductors, etc. Materials can be used.

Examples of the conductive polymer include a polymer compound having a conjugated molecular structure (conjugated polymer). Here, the polymer having a conjugated molecular structure is a polymer having a structure in which single bonds and double bonds are alternately connected in a carbon-carbon bond on the main chain of the polymer.
Further, the conductive polymer used in the present invention is not necessarily a high molecular weight compound, and may be an oligomer compound.

Specific examples of the conjugated polymer include thiophene compounds, pyrrole compounds, aniline compounds, acetylene compounds, p-phenylene compounds, p-phenylene vinylene compounds, p-phenylene ethynylene compounds, p -Fluorenylene vinylene compound, polyacene compound, polyphenanthrene compound, metal phthalocyanine compound, p-xylylene compound, vinylene sulfide compound, m-phenylene compound, naphthalene vinylene compound, p-phenylene oxide compound And phenylene sulfide compounds, furan compounds, selenophene compounds, azo compounds, metal complex compounds, and the like. Further, a conjugated polymer having a repeating unit derived from this monomer using a derivative having a substituent introduced into these compounds as a monomer can also be used.
These may be used alone or in combination of two or more.

Specific examples of the conductive nanocarbon material include carbon nanotubes (hereinafter also referred to as CNT), carbon nanofibers, graphite, graphene, and carbon nanoparticles. 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.
The size of the conductive nano material may be nano size (less than 1 μm). Moreover, about the carbon nanotube, carbon nanofiber, etc. which are mentioned later, an average minor axis should just be nanosize (for example, an average minor axis is 500 nm or less).

Various known nano metal materials and inorganic oxide semiconductors can be used.
Specifically, Bi-Te materials, Bi-Se materials, Sb-Te materials, Pb-Te materials, Ge-Te materials, Bi-Sb materials, Zn-Sb materials, Co-Sb Material, Ag-Sb-Ge-Te material, Si-Ge material, Fe-Si material, Mg-Si material, Mn-Si material, Fe-O material, Zn-O material, Cu Examples include -O-based materials, Na-Co-O-based materials, Ti-Sr-O-based materials, Bi-Sr-Co-O-based materials, and the like. These may be used alone or in combination of two or more.

In the thermoelectric conversion element 10 of the present invention, a thermoelectric conversion layer 16 in which a thermoelectric conversion material as described above is dispersed in a binder (resin material) is preferably used.
Among these, the thermoelectric conversion layer 16 obtained by dispersing a conductive nanocarbon material in a binder is more preferably exemplified. Among them, the thermoelectric conversion layer 16 in which CNT is dispersed in a binder is particularly preferably exemplified in that high conductivity is obtained.

The CNT may be a single-wall CNT or a multi-wall CNT.
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.

When using CNT for the thermoelectric conversion layer 16, it is preferable to contain a dopant.
Various known dopants can be used. Specifically, alkali metal, hydrazine derivative, metal hydride (sodium borohydride, tetrabutylammonium borohydride, lithium aluminum hydride, etc.), polyethyleneimine, halogen (iodine, bromine, etc.), Lewis acid (PF ₅ , AsF ₅ and the like), protonic acid (hydrochloric and sulfuric), transition metal halide (FeCl _3, SnCl _4, etc.), an organic electron accepting material (tetracyanoquinodimethane (TCNQ) derivative, 2,3-dichloro Preferred examples include -5,6-dicyano-p-benzoquinone (DDQ) derivatives and the like. These may be used alone or in combination of two or more.
Among them, organic electron accepting substances such as polyethyleneimine, TCNQ derivatives, and DDQ derivatives are preferably exemplified in terms of material stability, compatibility with CNTs, and the like.

As the binder, various known non-conductive resin materials can be used.
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 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 polyester. Is exemplified.

Among these, thermosetting resins and ultraviolet curable resins are preferably used.
Various known materials can be used as the thermosetting resin. Specifically, epoxy resin, bisphenol A type epoxy resin, hydrogenated bisphenol A type epoxy resin, novolac type epoxy resin, polyalkylene ether type epoxy resin, cycloaliphatic type epoxy resin, phenol resin, melamine resin, thermosetting Examples include urethane resin, thermosetting imide resin, thermosetting polyamideimide, thermosetting silicone resin, urea resin, unsaturated polyester resin, urea resin, benzoguanamine resin, alkyd resin, cyanate resin and the like.

Various known UV curable resins can also be used. Specifically, a polymerizable oligomer or monomer having a (meth) acryloyl group such as urethane (meth) acrylate, epoxy (meth) acrylate, polyester (meth) acrylate, polyether (meth) acrylate, melamine (meth) acrylate, etc. Examples thereof include a resin obtained by polymerization and a resin obtained by polymerizing a polymerizable oligomer or monomer having a polymerizable vinyl group such as acrylic acid, acrylamide, acrylonitrile, and styrene. Further, these prepolymers may be used.
In the present invention, a photopolymerization initiator curing agent can be added to these polymerizable oligomers, monomers, and prepolymers, and additives such as sensitizers can be added as necessary.

Specific examples of such polymerizable monomers include trimethylolpropane tri (meth) acrylate, hexanediol (meth) acrylate, tripropylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, pentaerythritol tri ( Examples include (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, and the like. These may be used alone or in combination of two or more.
Specific examples of the polymerizable prepolymer include polyester acrylate, epoxy acrylate, urethane acrylate, and polyol acrylate photopolymerizable prepolymers. These may be used alone or in combination of two or more.

In both the thermosetting resin and the ultraviolet curable resin, a radical polymerization resin can be preferably used.
Although there is no restriction | limiting in particular as a radically polymerizable compound which can be utilized for this invention, Using a radically polymerizable compound which has 2 or more polymerizable groups in a molecule | numerator can form a crosslinked structure and is preferable from a viewpoint of hardening.
Specifically, divinylbenzene, acrylamide monomer, polyethylene glycol dimethacrylate (NK ester 1G, 2G, 3G, 4G, 9G, 14G, 23G), polyethylene glycol diacrylate (NK ester A-200, A-400, A -600, A-1000), neopentyl glycol dimethacrylate (NK ester 3PG, 9PG, APG-400, APG-700), neopentyl glycol diacrylate (NK ester APG-100, APG-200, APG-400, APG) -700) 1,6-hexanediol dimethacrylate (NK ester HD-N), 1,6-hexanediol diacrylate (NK ester A-HD-N), 1,9-nonanediol dimethacrylate (NK ester NOD) N,), 1,9-nonanediol diacrylate (NK ester A-NOD-N), 1,10-decanediol dimethacrylate (NK ester DOD), 1,10-decanediol diacrylate (NK ester A-DOD) ), Ethylene oxide modified bisphenol A dimethacrylate (NK ester BPE-80N, BPE-100N, BPE-200, BPE-500, BPE-900, BPE-1300N), ethylene oxide modified bisphenol A diacrylate (NK ester ABE-300) A-BPE-4, A-BPE-6, A-BPE-10, A-BPE-20, A-BPE-30), tricyclodecane dimethanol dimethacrylate (NK ester DCP), tricyclodecane dimethanol Diacrylate (NK Steal A-DCP), ethylene oxide modified isocyanuric acid triacrylate (NK ester A-9300), trimethylolpropane trimethacrylate (NK ester TMPT), trimethylolpropane triacrylate (NK ester A-TMPT), ethylene oxide modified trimethylol Propane triacrylate (NK ester A-TMPT-3EO), pentaerythritol tetraacrylate (NK ester A-TMMT), ditrimethylolpropane tetraacrylate (NK ester AD-TMP), dipentaerythritol hexaacrylate (NK ester A-DPH, Above, trade name of Shin-Nakamura Kogyo Co., Ltd.), 1,4-butanediol diacrylate (V # 195), trisacryloyloxyethyl phosphate (V #) 3PA, above, trade name of Osaka Organic Industry Co., Ltd.), vinyl modified polydimethylsiloxane at both ends (DMS-V00, DMS-V03, DMS-V05, DMS-V21, DMS-V22, DMS-V25, DMS-V31, DMS-) V33, DMS-V35, DMS-V41, DMS-V42, DMS-V46, DMS-V51, DMS-V52), side chain vinyl-modified polysiloxane (VDT-123, VDT-127, VDT-131, VDT-163, VDT-431, above, Gelest, Inc. trade name), methacryl-modified polydimethylsiloxane (X-22-164, X-22-164AS, X-22-164A, X-22-164B, X-22-) 164C, X-22-164E (Shin-Etsu Chemical Co., Ltd., trade name) and the like are exemplified, but are not limited thereto. It is not a thing.

  As will be described in detail later, the thermoelectric conversion layer 16 has a configuration in which a thermoelectric conversion material is dispersed using a thermosetting resin or an ultraviolet curable resin as a binder, so that the trapezoidal cross-sectional shape of the illustrated example (square pyramid shape). The thermoelectric conversion layer 16 having a desired shape, such as the thermoelectric conversion layer 16 having, can be formed stably.

In the present invention, a thermoplastic resin may be used as the binder of the thermoelectric conversion layer 16 for the purpose of controlling moldability.
Examples of the thermoplastic resin include polystyrene, acrylonitrile-butadiene-styrene (ABS) resin, acrylonitrile-styrene (AS) resin, methyl methacrylate-acrylonitrile-styrene resin, methyl methacrylate-acrylonitrile-butadiene-styrene resin, styrene-butadiene- Aromatic vinyl resins such as styrene block copolymers and styrene-ethylene-butylene-styrene block copolymers, polymethyl methacrylate, polymethyl acrylate, polymethacrylic acid, copolymers thereof, and acrylic rubber Acrylic resins, polyacrylonitrile, acrylonitrile-methyl acrylate resins, acrylonitrile-butadiene resins and other vinyl cyanide resins, imide group-containing vinyl resins, polyethylene, poly Lopylene, polyneoprene, polyisoprene, polybutene, polyisobutene, hydrogenated polyisobutene, polybutadiene, hydrogenated polybutadiene, ethylene-propylene-dicyclopentadiene copolymer, ethylene-propylene-ethylidene norbornene copolymer, ethylene-propylene copolymer, etc. Polyolefin resin, acid or acid anhydride modified polyolefin resin, epoxy modified polyolefin resin, acid or acid anhydride modified acrylic elastomer, epoxy modified acrylic elastomer, silicone rubber, fluororubber, natural rubber, polycarbonate, cyclic polyolefin, polyamide , Polyethylene terephthalate, polybutylene terephthalate, poly 1,4-cyclohexanedimethyl terephthalate, polyarylate, liquid crystalline polyester Fluorine resins such as polyphenylene ether, polyarylene sulfide, polysulfone, polyethersulfone, polyoxymethylene, polytetrafluoroethylene, fluorinated ethylene propylene, polychlorotrifluoroethylene, polyvinylidene fluoride and polyvinyl fluoride, poly Examples thereof include lactic acid, polyvinyl chloride, thermoplastic polyimide, thermoplastic polyamideimide, polyetherimide, polyetheretherketone, polyetherketoneketone, and polyetheramide.

In the thermoelectric conversion element 10 of the present invention, the amount ratio between the binder and the thermoelectric conversion material in the thermoelectric conversion layer 20 depends on the material used, the required thermoelectric conversion efficiency, the viscosity of the solution affecting the printing, the solid content concentration, and the like. It can be set as appropriate.
Specifically, the mass ratio of “thermoelectric conversion material / binder” is preferably 5/95 to 90/10, and more preferably 10/90 to 80/20.
By setting the amount ratio of the binder to the thermoelectric conversion material within the above range, preferable results are obtained in terms of power generation efficiency, moldability of the thermoelectric conversion layer 16, printability, productivity, and the like.
In the present invention, the binder (thermosetting resin, ultraviolet curable resin, thermoplastic resin, etc.) of the thermoelectric conversion layer 16 exemplified above may be used alone or in combination of two or more. .

Here, in the thermoelectric conversion element of the present invention, the thermoelectric conversion layer 16 faces the upper electrode 18 in the cross-sectional shape of the lower electrode 14 and the upper electrode 18 on the substrate 12 in the energization direction (arrow x direction in the figure). And the area | region descend | falling toward the board | substrate 12 has a shape which inclines so that it may space apart gradually from the edge part of the lower electrode 14 of an electricity supply direction.
In the illustrated example, the thermoelectric conversion layer 16 has a quadrangular pyramid shape, and as shown in FIG. 2, the cross-sectional shape in the energization direction is a trapezoid.
The shape of the thermoelectric conversion layer 16 will be described in detail later.

In the thermoelectric conversion element 10 of the present invention, the upper electrode 18 forms an electrode pair with the lower electrode 14 and is provided so as to sandwich the thermoelectric conversion layer 16 together with the lower electrode 14.
As shown in FIGS. 1 and 2, the upper electrode 18 is formed toward the lower electrode 14 (thermoelectric conversion layer 16) from a position separated from the lower electrode 14 on the substrate 12, and further rises from the substrate 12. The thermoelectric conversion layer 16 is formed so as to extend from the side surface to the upper surface.
In the illustrated example, the thermoelectric conversion element 10 is formed such that the upper electrode 18 and the lower electrode 14 have regions that overlap each other when viewed in a direction perpendicular to the substrate 12.

The upper electrode 18 may be formed of the same material as the lower electrode 14 described above.
In view of productivity, printability, and the like, the upper electrode 18 is preferably formed using a material obtained by dispersing conductive metal fine particles in a binder, such as silver paste.

  Similar to the lower electrode 14, the thickness and size of the upper electrode 18 may be set as appropriate according to the size of the thermoelectric conversion element 10 to be formed and the like so that the generated power can be reliably extracted without loss. In addition, the thickness of the upper electrode 18 is preferably 50 to 20000 nm in view of obtaining sufficient electrical conductivity.

In such a thermoelectric conversion element 10 of the present invention, the thermoelectric conversion layer 16 has a predetermined cross-section in the energization direction (the arrow x direction in the figure) between the lower electrode 14 and the upper electrode 18 on the substrate 12. . In other words, the thermoelectric conversion layer 16 has a predetermined shape on a cross section in the direction in which the lower electrode 14 and the upper electrode 18 are separated (the direction in which the upper electrode 18 extends) on the substrate 12.
Specifically, the thermoelectric conversion layer 16 faces the upper electrode 18 in a cross-sectional shape in the energization direction between the lower electrode 14 and the upper electrode 18 on the substrate 12 (hereinafter, also simply referred to as “cross-sectional shape in the energization direction”). The region descending toward the substrate 12 (region not parallel to the substrate 12) is from the end of the lower electrode 14 in the energization direction (specifically, the end opposite to the upper electrode 18). , And gradually inclined so as to be separated.

In other words, the cross-sectional shape of the thermoelectric conversion layer 16 in the energizing direction is such that the region facing the upper electrode 18 and descending toward the substrate 12 has an angle with respect to the substrate 12 of 90 ° or more (in the case of a curve, the tangent is 90 (No more)
Furthermore, in other words, the thermoelectric conversion layer 16 faces the upper electrode 18, and the region descending toward the substrate 12 is an inclined surface that gradually slopes away from the end of the lower electrode 14 in the energizing direction ( Including curved surfaces).

In the illustrated example, the thermoelectric conversion layer 16 has a quadrangular frustum shape. Therefore, as a preferred embodiment, the cross-sectional shape in the energization direction is a trapezoid.
Therefore, the cross-sectional shape of the region facing the upper electrode 18 and descending toward the substrate 12, that is, the region facing the upper electrode 18 on the side surface is the lower electrode 14 in the energization direction toward the lower substrate 12. Gradually away from the end of the. Therefore, in the thermoelectric conversion layer 16, the angle with respect to the substrate 12 is less than 90 ° in the region where the upper electrode 18 on the side surface faces.

  In the thermoelectric conversion element 10 of the present invention, since the thermoelectric conversion layer 16 has such a cross-sectional shape, the upper electrode 18 is prevented from being broken or thinned, and the electric conductivity due to the upper electrode 18 being broken or the like is reduced. The thermoelectric conversion element 10 having no deterioration and excellent reliability is realized.

In the conventional thermoelectric conversion element 10, as conceptually shown in FIG. 5, the thermoelectric conversion layer 70 has a quadrangular prism shape, and the cross-sectional shape in the energizing direction is rectangular or square.
Therefore, when the upper electrode 18 is formed, an electrode cannot be appropriately formed at the corner portion of the thermoelectric conversion layer 70, and the upper electrode 18 is broken at the corner portion. There is also a possibility that the electrode 18 is disconnected.

  On the other hand, as shown in Patent Document 2, the upper electrode 18 at the corners of the thermoelectric conversion layer 70 is suppressed by chamfering the ridges and / or vertices at the top of the quadrangular columnar thermoelectric conversion layer. it can.

However, in the quadrangular prism-shaped thermoelectric conversion layer 70 as shown in FIG. 5 and Patent Document 2, the side surface on which the upper electrode 18 needs to be formed is erected vertically to the substrate 12.
Here, as will be described later, the upper electrode 18 is preferably formed by a printing method using a silver paste or the like. At this time, if the formation surface of the upper electrode 18 in the thermoelectric conversion layer has a region perpendicular to the substrate 12, it is difficult to appropriately apply a material for the upper electrode 18 such as silver paste to the vertical region. Therefore, in this side surface, the upper electrode 18 is broken or a thin film portion or the like is generated, and the conductivity of the upper electrode 18 is lowered.
In particular, in order to obtain high power generation efficiency, as described above, the size of the thermoelectric conversion layer 16 between the lower electrode 14 and the upper electrode 18 (hereinafter, also referred to as “the thickness of the thermoelectric conversion layer 16”), It needs to be thick to some extent. In this case, if the formation surface of the upper electrode 18 in the thermoelectric conversion layer has a side surface perpendicular to the substrate 12, it is more appropriate to appropriately apply a material to be the upper electrode 18 such as a silver paste over the entire side surface. It becomes difficult.

On the other hand, the thermoelectric conversion element 10 of the present invention faces the upper electrode 18 in the cross-sectional shape in the energizing direction of the thermoelectric conversion layer 16 and descends toward the substrate 12 (hereinafter, for convenience, This region is also referred to as “formation side surface of the upper electrode 18” and is inclined so as to gradually move away from the end of the lower electrode 14 in the energizing direction (hereinafter, this shape is referred to as “predetermined shape” for convenience). Also called).
Therefore, in the thermoelectric conversion layer 16, the angle formed by the upper surface and the side surface on which the upper electrode 18 is formed can be made obtuse, so that when the upper electrode 18 is formed, the upper electrode 18 is prevented from being broken at the corner. it can. Further, since the side surface on which the upper electrode 18 is formed has a predetermined shape, the side surface on which the upper electrode 18 is formed has a planar shape when viewed from above in the direction perpendicular to the substrate 12. Therefore, even if the thermoelectric conversion layer 16 is thickened in order to improve the power generation efficiency, the side surface of the upper electrode 18 is properly formed without causing breakage or a thin film portion by a printing method using a silver paste or the like. The upper electrode 18 can be formed.
Therefore, according to the present invention, it is possible to stably obtain the highly reliable thermoelectric conversion element 10 that prevents a decrease in the conductivity of the upper electrode 18.

In the thermoelectric conversion element 10 of the present invention, the thermoelectric conversion layer 16 has a predetermined side surface on which the upper electrode 18 is formed in a cross-sectional shape in the energization direction at the center in the direction orthogonal to the energization direction (arrow y direction in the figure). Any shape is acceptable. In addition, when the length of the thermoelectric conversion layer 16 in the arrow y direction is not uniform, a cross section in the energization direction at the center of the position of the maximum length in the arrow y direction is used.
However, in the present invention, the thermoelectric conversion layer 16 has a predetermined shape on the side surface on which the upper electrode 18 is formed in a cross-sectional shape in the energizing direction in a region having a length of 80% or more in the arrow y direction including the center. Is preferred. In particular, the thermoelectric conversion layer 16 preferably has a predetermined shape on the side surface on which the upper electrode 18 is formed in the cross-sectional shape in the energization direction in the entire region in the direction of arrow y.

In the thermoelectric conversion element 10 of the present invention, the side surface on which the upper electrode 18 is formed may be inclined downward from the end of the lower electrode 14 toward the lower side. Therefore, in the cross-sectional shape in the energization direction, the angle formed by the upper surface and the side surface on which the upper electrode 18 is formed may be more than 90 °, but is preferably 95 to 120 °, and preferably 100 to 120 °. Particularly preferred. As a result, breakage of the upper wiring 18 at the corner from the upper surface to the side surface where the upper electrode 18 is formed can be more suitably prevented, and the upper electrode 18 can be formed more stably on the side surface where the thermoelectric conversion layer 16 is unnecessary. This is preferable in that it can be prevented from becoming large.
In addition, as in the thermoelectric conversion element shown in FIG. 3 to be described later, when one of the upper surface and the side surface on which the upper electrode 18 is formed is a curve or the like (the upper surface or the side surface is a curved surface), It is preferable that the tangent at the boundary with the formation side face is the above angle.

Here, the thermoelectric conversion layer 16 preferably satisfies “L2 / L1> 0.05” when the length in the energization direction is L1 and the height from the substrate 12 is L2.
As described above, in order to obtain good thermoelectric conversion efficiency, the thermoelectric conversion layer 16 preferably has a certain thickness. On the other hand, when the thermoelectric conversion layer 16 satisfies the above formula, in the thermoelectric conversion element 10, the thermoelectric conversion layer 16 can be suitably thickened, and the thermoelectric conversion element 10 having good thermoelectric conversion efficiency can be obtained. . Further, according to the present invention, since the side surface of the upper electrode 18 in the cross-sectional shape in the energizing direction has a predetermined shape, the upper electrode 18 can be stably and appropriately formed even if the thermoelectric conversion layer 16 is thick. .
Considering this point, “L2 / L1” is more preferably 0.08 or more.

  Moreover, specifically, the thickness L2 of the thermoelectric conversion layer 16 is preferably 1 to 2000 μm, and more preferably 10 to 1000 μm, in terms of stably obtaining good thermoelectric conversion efficiency.

Furthermore, the cross section S of the thermoelectric conversion layer 16 in the energizing direction preferably satisfies “(π × L1 × L2) / 2 <S <L1 × L2”.
Thereby, the formation side surface of the upper electrode 18 in the cross-sectional shape of the thermoelectric conversion layer 16 in the energizing direction can be more stably formed.

In the thermoelectric conversion element 10 of the present invention, various shapes other than the trapezoid as shown in FIGS. 1 and 2 can be used as the cross-sectional shape of the thermoelectric conversion layer 16.
For example, like the thermoelectric conversion layer 16a conceptually showing the cross-sectional shape in the energization direction in FIG. 3, the upper surface of the trapezoid may be a curved surface (the square-pyramidal trapezoidal thermoelectric conversion layer 16a having a curved upper surface). Or conversely, the cross-sectional shape in the energization direction may be a straight upper surface and a curved side surface. Furthermore, an elliptical cross-sectional shape (elliptical spherical thermoelectric conversion layer) may be used, such as a thermoelectric conversion layer 16b conceptually showing a cross-sectional shape in the energization direction in FIG.

Here, in many cases, the thermoelectric conversion element 10 (thermoelectric conversion module using the thermoelectric conversion element) of the present invention is arranged with the upper surface electrode 18 (on the side opposite to the substrate 12) on the thermoelectric conversion layer 16 facing the heat source.
Therefore, it is preferable that the thermoelectric conversion layer 16 has a planar region on the upper surface in terms of increasing the contact area between the heat source and the thermoelectric conversion element 10 (upper surface electrode 18). Especially, it is preferable that the thermoelectric conversion layer 16 has a plane area | region parallel to the board | substrate 12 on the upper surface.

Considering the above points, ease of molding, heat conduction efficiency, heat diffusion efficiency, and the like, the cross-sectional shape of the thermoelectric conversion layer 16 is preferably a trapezoid as shown in FIG.
For the same reason, the shape of the thermoelectric conversion layer 16 is preferably exemplified by a quadrangular pyramid shape as shown in FIG.

In consideration of the above points, it is advantageous that the planar area of the upper surface of the thermoelectric conversion layer 16 is wider.
Specifically, the planar area of the upper surface of the thermoelectric conversion layer 16 is smaller than the area of the thermoelectric conversion layer 16 in contact with the lower electrode 14 and is 80% or more of the area of the thermoelectric conversion layer 16 in contact with the lower electrode 14. Is preferred.

Here, in the thermoelectric conversion element 10 of this invention, it is preferable that the upper surface of the thermoelectric conversion layer 10 does not have a recessed part (area | region). Specifically, it is preferable that the upper surface of the thermoelectric conversion layer 10 does not have a partial concave portion as conceptually shown in FIG. 6A, and as conceptually shown in FIG. Moreover, it is preferable that the entire region is not concave.
That is, it is preferable that the upper surface of the thermoelectric conversion layer 10 has a planar shape as shown in FIG. 2, a convex shape as shown in FIGS. 3 and 4, a shape having only one convex portion on the plane, or the like.

  By not having a concave portion on the upper surface of the thermoelectric conversion layer 16, the upper electrode 18 can be appropriately formed on the upper surface of the thermoelectric conversion layer 10, and the contact area between the heat source and the thermoelectric conversion element 10 can be increased. This is preferable in terms of reducing the material for forming the upper electrode 18 and suppressing the generation of resistance.

Here, depending on the shape of the thermoelectric conversion layer, the upper surface may not be clear, that is, the inflection point between the upper surface and the side surface may not be clear.
For example, the thermoelectric conversion layer 16 whose cross-sectional shape in the energization direction is trapezoidal (square pyramid shape) as shown in FIG. Shape) of the thermoelectric conversion layer 16a is clear. On the other hand, in the thermoelectric conversion layer 16b having an elliptical cross-sectional shape in the energization direction shown in FIG. 4, the inflection point between the upper surface and the side surface is not clear, and it cannot be determined where the upper surface is.
In such a case, when viewed from the direction perpendicular to the substrate 12, the region where the lower electrode 14 and the upper electrode 18 overlap is regarded as the upper surface (defined as the upper surface), and the region is concave. Preferably there is no part.

On the other hand, as for the thermoelectric conversion layer 16, the lower end part (lower end surface) by the side of the upper electrode 18 is preferably located in the board | substrate 12 side rather than the upper surface of the lower electrode 14, as shown in FIGS.
As an example, when there is nothing on the surface of the substrate 12, the lower end portion on the upper electrode 18 side of the thermoelectric conversion layer 16 is preferably in contact with the surface of the substrate 12, for example. Further, when an easy adhesion layer is formed on the surface of the substrate 12 and the lower electrode 14 and the thermoelectric conversion layer 16 are formed thereon, the lower end portion on the upper electrode 18 side of the thermoelectric conversion layer 16 is, for example, an easy adhesion layer. It is preferred to contact the layer.
Thereby, the short circuit with the lower electrode 14 and the upper electrode 18 is prevented reliably, and the thermoelectric conversion element 10 which is more excellent in reliability can be obtained.

At this time, the length in the energization direction of the lower end portion on the upper electrode 18 side of the thermoelectric conversion layer 16 located on the substrate 12 side from the upper surface of the lower electrode 14 is the size of the thermoelectric conversion element 10 and the thickness of the lower electrode 14. Although it may be set appropriately according to the thickness, it is preferably about 0.5 to 5 mm.
This is preferable in that a short circuit between the upper electrode 18 and the lower electrode 14 can be prevented more reliably.

In addition, in this invention, if the shape of the thermoelectric conversion layer 16 can be maintained appropriately, the shape of side surfaces other than the formation side surface of the upper electrode 18 in the cross-sectional shape of an electricity supply direction is arbitrary.
Therefore, in the thermoelectric conversion layer 16 of the thermoelectric conversion element 10, the side surface other than the side surface on which the upper electrode 18 is formed in the cross-sectional shape in the energization direction may be perpendicular to the substrate 12 and toward the center of the thermoelectric conversion layer. In the downward direction, they may gradually approach each other or may be concave.

Hereinafter, an example of the manufacturing method of the thermoelectric conversion element 10 of this invention is shown.
First, the substrate 12 as described above is prepared, and the lower electrode 14 is formed on the surface thereof.
As a method for forming the lower electrode 14, various known methods for forming a metal film or the like can be used. Specifically, it contains a vapor phase film formation method (vapor phase deposition method) such as an ion plating method, a sputtering method, a vacuum vapor deposition method, a CVD method such as plasma CVD, or the above metal powder, a binder, and a solvent. The printing method using a metal paste etc. is illustrated.

Next, a thermoelectric conversion layer 16 is formed on the substrate 12 so as to cover a part of the lower electrode 14.
As a method of forming the thermoelectric conversion layer 16, a known method corresponding to the thermoelectric conversion material to be used can be used. Here, in the thermoelectric conversion element 10 of this invention, the printing method using the coating material formed by disperse | distributing the thermoelectric conversion material to resin used as a binder is utilized suitably.

That is, first, necessary components such as a thermoelectric conversion material and a resin material that becomes a binder are added, and the paste (ink) is mixed and dispersed using a known method such as an ultrasonic homogenizer, a mechanical homogenizer, or a ball mill. Prepare.
As described above, it is preferable to use a thermosetting resin or an ultraviolet curable resin as the binder. Furthermore, normally, these are added to a solvent and mixed and dispersed to prepare a paste. However, in the present invention, the paste may be adjusted without using a solvent or with a very small amount of solvent. preferable.

By using a thermosetting resin or ultraviolet curable resin as the binder, the thermoelectric conversion layer 16 can be formed by rapidly curing the resin material by heating or irradiating ultraviolet rays. The thermoelectric conversion layer 16 having a desired shape can be formed.
In particular, by using a thermosetting resin or an ultraviolet curable resin, and further reducing the amount of solvent-free or solvent, and preparing a paste that becomes the thermoelectric conversion layer 16, shrinkage due to evaporation of the solvent is eliminated or suppressed. Thus, the thermoelectric conversion layer 16 having a desired shape can be formed more stably.

In the preparation of the paste, when a solvent is used, the amount of the solvent is preferably 50% by mass or less based on the total mass of raw materials used for preparing the paste.
In addition, what is necessary is just to use the well-known solvent (organic solvent) which can melt | dissolve this according to the thermosetting resin and ultraviolet curing resin to be used.

In addition to the thermoelectric conversion material and the resin material, a dispersant and / or a crosslinking agent (curing agent) may be added to the paste forming the thermoelectric conversion layer 16 as necessary.
Dispersants include anionic surfactants: known materials such as sodium cholate, sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, alkylamines, pyrene derivatives, porphyrin derivatives, π-conjugated polymers, sodium polystyrene sulfonate, etc. Can be used. As the binder, known materials such as styrene polymer, acrylic polymer, polycarbonate, polyester, epoxy resin, siloxane polymer, polyvinyl alcohol, and gelatin can be used.

Specific examples of the crosslinking agent include silane compounds such as phenethyl trialkoxysilane, aminopropyltrialkoxysilane, glycidylpropyltrialkoxysilane, and tetraalkoxysilane; trimethylolmelamine, di (tri) amine derivatives, di (tri) Examples include known materials such as low-molecular crosslinking agents such as glycidyl derivatives, di (tri) carboxylic acid derivatives, and di (tri) acrylate derivatives; polymer crosslinking agents such as polyallylamine, polycarbodiimide, and polycation.
Furthermore, the paste may contain a surfactant, a slip agent, a thickener such as alumina or silica, and the like as necessary.

  Once the paste is prepared in this way, the paste is printed according to the thermoelectric conversion layer 16 to be formed by a known printing method such as stencil printing, screen printing, inkjet printing, gravure printing, flexographic printing, and the binder is cured. Thus, the thermoelectric conversion layer 16 is formed.

Here, the curing of the binder is preferably performed in two stages: a pre-curing process for slowly curing the binder and a main curing process for quickly curing the binder.
That is, by providing a pre-curing step for gently curing the binder, the viscosity and hardness of the printed paste is changed, and the paste is appropriately sagged to form the shape of the side surface on which the upper electrode 18 is formed. And Then, in the main curing step, the thermoelectric conversion layer 16 having a target shape can be obtained by fixing the shape of the thermoelectric conversion layer by quickly curing the binder.

In the pre-curing process for gently curing the binder, the heating temperature is lowered as compared with the main curing process if it is a thermosetting resin, and the amount of ultraviolet rays to be irradiated is compared with that in the main curing process if it is an ultraviolet curable resin. It may be reduced.
In addition, the pre-curing step is performed in the atmosphere (in the air atmosphere) that inhibits the polymerization reaction in order to suppress the curing of the binder, and the main curing step is performed in order to efficiently progress the binder curing (polymerization reaction). It is preferable to carry out in an inert atmosphere.
Furthermore, after the pre-curing step, heating (heating step) may be performed as necessary to change the viscosity and hardness of the paste to control the shape of the thermoelectric conversion layer 16. This heating step is particularly effective when an ultraviolet curable resin is used as the binder.

When the thermoelectric conversion layer 16 is formed, the upper electrode 18 is formed so as to reach from the side surface to the upper surface of the thermoelectric conversion layer 16 from a position separated from the lower electrode 14 (thermoelectric conversion layer 16) on the substrate 12.
The upper electrode 18 may be produced by a known method corresponding to the forming material or the like. As a preferred example, the upper electrode 18 is formed by a printing method using a paste containing conductive particles such as a silver paste. As the printing method, various known methods can be used as in the thermoelectric conversion layer 16.

In the above example, the paste that becomes the thermoelectric conversion layer 16 is applied by a printing method, and this paste is cured in two stages of pre-curing and main curing, so that the side surface on which the upper electrode 18 is formed has a cross-sectional shape in the energizing direction. A thermoelectric conversion layer 16 having a predetermined shape is formed.
However, in the thermoelectric conversion element of the present invention, the thermoelectric conversion layer 16 having a predetermined side surface in the cross-sectional shape in the energizing direction can be formed by various methods other than this. For example, by using a known method such as a printing method, a temporary thermoelectric conversion layer having a columnar shape or a rectangular column shape as shown in FIG. 5 is formed, and a known fine processing technique such as sandblasting, machining technique, laser etching or the like is used. The thermoelectric conversion layer 16 in which the side surface on which the upper electrode 18 is formed has a predetermined shape in the cross-sectional shape in the energizing direction may be used.

Such a thermoelectric conversion element 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 of the present invention has been described in detail, but the present invention is not limited to the above-described examples, and various modifications and changes may be made without departing from the scope of the present invention. Of course.

  Hereinafter, the thermoelectric conversion element of 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]
<Preparation of thermoelectric conversion material composition>
Chloroform 10 mL (liter) is added to 30 mg of poly (3-octylthiophene) (Regio Random, manufactured by Aldrich, weight average molecular weight 67400), and an ultrasonic cleaner (US-2, manufactured by Inoue Seieido Co., Ltd.), output 120W, indirect irradiation) was used to prepare a dispersant solution.
To this dispersant solution, 70 mg of single-walled carbon nanotubes (ASP-100F, manufactured by Hanwha) is added, and an ultrasonic homogenizer (VC-750, manufactured by SONICS & MATERIALS. Inc., using a tapered microchip (probe diameter 6.5 mm), output. 40W, direct irradiation, duty ratio 50%), ultrasonically dispersed at 30 ° C. for 30 minutes, and further ultrasonic cleaning machine (US-2, manufactured by Inoue Seieido Co., Ltd., output 120W, indirect irradiation) A carbon nanotube dispersion was prepared by ultrasonic dispersion at 30 ° C. for 60 minutes.
Further, this carbon nanotube dispersion was evaporated to dryness to prepare a conductive composition.

On the other hand, MEK (methyl ethyl ketone) 5.3 g,
5 g of liquid bisphenol A type epoxy resin (Epicoat 825, manufactured by Japan Epoxy Resin Co., Ltd., epoxy equivalent 176),
2 g of MEK varnish of phenol novolac resin containing triazine structure (Phenolite LA-7052, manufactured by Dainippon Ink & Chemicals, Inc., nonvolatile content 62%, nonvolatile phenolic hydroxyl group equivalent 120),
10.7 g of phenoxy resin MEK varnish (YP-50EK35, manufactured by Toto Kasei Co., Ltd., nonvolatile content 35%), and
0.053 g of 2-ethyl-4-methylimidazole was mixed and stirred to completely dissolve it to prepare a thermosetting resin composition.

  200 mg of this thermosetting resin composition is added to the previously prepared conductive composition, and using an ultrasonic cleaner (US-2, manufactured by Inoue Seieido Co., Ltd., output 120 W, indirect irradiation) at 30 ° C. for 10 minutes. Ultrasonic irradiation was performed to prepare a thermoelectric conversion material composition (paste).

<Preparation of thermoelectric conversion layer 16>
The lower electrode 14 and the thermoelectric conversion layer 16 were produced on the substrate 12 as follows.
A glass substrate having a size of 40 × 50 mm and a thickness of 1.1 mm was prepared as the substrate 12.
The substrate 12 was ultrasonically cleaned in isopropyl alcohol. Next, a metal mask having an opening 20 × 20 mm formed by etching was placed on the substrate 12. Using this metal mask, a lower electrode 14 made of a chromium layer and a gold layer was formed on the substrate 12 by laminating 100 nm of chromium and then 200 nm of gold by ion plating.

Next, a 2 mm thick metal mask having an opening 13 × 13 mm formed by laser processing was placed on the substrate 12.
Note that the metal mask has four sides parallel to the 20 × 20 mm lower electrode 14, one opposing side of the opening is in the center of the lower electrode 14, and the other opposing side is one side of 1 mm. The substrate was placed on the substrate 12 such that a part of the opening covered the lower electrode 14 and was located outside the lower electrode 14.
The opening of the metal mask is filled with the previously prepared thermoelectric conversion material composition, molded with a squeegee, the metal mask is removed, and the thermoelectric conversion material thermal composition that becomes the thermoelectric conversion layer 16 on the substrate 12 Printed.

The substrate 12 on which the thermoelectric conversion material thermal composition was printed was heated on a hot plate at 80 ° C. for 5 minutes in the atmosphere to perform a pre-curing process of the thermoelectric conversion material thermal composition.
Next, the substrate 12 having the thermoset of the thermoelectric conversion material that has been pre-cured is heated on a hot plate at 170 ° C. for 30 minutes in an inert gas atmosphere to perform the main curing step of the thermoelectric conversion material thermoset, A thermoelectric conversion layer 16 covering a part of the lower electrode 14 was formed on the substrate 12.
As confirmed by visual observation with a magnifying glass, the thermoelectric conversion layer 16 had a quadrangular frustum shape as shown in FIG.

  About the produced thermoelectric conversion layer 16, it was confirmed whether there existed a cross-sectional shape of an electricity supply direction, L2 / L1, and a concave part in the upper surface.

-Cross-sectional shape At the center of the direction perpendicular to the energizing direction (y direction), the thermoelectric conversion layer 16 is cut in the energizing direction using a plastic cutter, the cross-sectional shape is observed with a digital microscope, and the observed image is image-analyzed. Analyzed by software.
As a result, the cross-sectional shape of the thermoelectric conversion layer 16 was a trapezoid. That is, the thermoelectric conversion layer 16 has a predetermined shape (a shape in which the side surface of the upper electrode 18 is gradually inclined away from the end of the lower electrode 14 in the energization direction) in the cross-sectional shape in the energization direction. It was confirmed that the conditions of the thermoelectric conversion element 10 of the present invention were satisfied.
The cross-sectional shape is confirmed only at the center in the y direction. However, according to the formation of the thermoelectric conversion layer 16 using the printing method, if the cross section at the center in the y direction is the above shape, the cross sectional shape in the energization direction is substantially the same in the entire y direction. Conceivable. This is also shown from the confirmation of the appearance of the thermoelectric conversion layer 16.

・ L2 / L1
The height L2 of the thermoelectric conversion layer 16 from the substrate 12 was measured using a stylus type film thickness meter (XP-200, manufactured by Ambios Technology). Furthermore, the size L1 in the energizing direction of the thermoelectric conversion layer 16 was measured with a ruler.
As a result, L1 was 12 mm and L2 was 1.8 mm. That is, L2 / L1 is 0.15.

-Concave portion on the upper surface The upper surface of the thermoelectric conversion layer 16 was observed with a digital microscope, and the surface properties were analyzed using image software, and it was confirmed that there were no concave portions on the upper surface of the thermoelectric conversion layer 16. .

  A silver paste (conductive paste dotite “D-550”, manufactured by Fujikura Kasei Co., Ltd.) is used for the substrate 12 on which the lower electrode 14 and the thermoelectric conversion layer 16 are formed as described above, and is 10 μm thick by screen printing. The upper electrode 18 as shown in FIG. 1 extending from the substrate 12 to the side surface and the upper surface of the thermoelectric conversion layer 16 was formed to produce the thermoelectric conversion element 10 as shown in FIG.

[Example 2]
A photocurable resin composition was prepared with the following composition.
-N-vinylcaprolactam (V-CAP, manufactured by ISP) 23 parts by mass-Phenoxyethyl acrylate (SR399S, manufactured by Sartomer) 33.0 parts by mass-Dicyclopentanyloxyethyl acrylate (FA-512, Hitachi Chemical) (Made by Co., Ltd.) 5 parts by mass-Trimethylolpropane triacrylate (SR351S, manufactured by Sartomer) 5 parts by mass-1,6-hexanediol diacrylate (SR238F, manufactured by Sartomer) 3 parts by mass-2-Benzyl-2- Dimethylamino-1- (4-morpholinophenyl) -butan-1-one (IRGACURE 369, manufactured by BASF Japan Ltd.) 2 parts by mass Bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide (IRGAC URE 819 , BASF Japan Ltd.) 3 parts by mass ・ Isopropylthioxanthone (SPEEDCURE ITX, manufactured by Lambson) 3 masses

  200 mg of this photocurable resin composition was added to the conductive composition produced in the same manner as in Example 1, and a thermoelectric conversion material composition (paste) was prepared in the same manner as in Example 1.

  On the other hand, a substrate similar to that in Example 1 was prepared, and the lower electrode 14 was formed on the substrate 12 in the same manner as in Example 1. Next, the prepared thermoelectric conversion material composition was printed on the substrate 12 and the lower electrode 14 in the same manner as in Example 1.

The thermoelectric conversion material thermal composition printed on the substrate 12 was irradiated with ultraviolet rays of 0.5 J / cm ^{2 in} the atmosphere to perform a pre-curing process.
Subsequently, the thermoelectric conversion material composition which performed the pre-curing process was hold | maintained for 10 minutes at 80 degreeC, and the heating process was performed.
Further, the thermoelectric conversion material composition that has been subjected to the heating process is irradiated with 1 J / cm ² of ultraviolet light in an inert gas atmosphere to perform the main curing process, and the thermoelectric conversion layer 16 that covers a part of the lower electrode 14 is formed on the substrate. 12 was formed.
When the shape of the produced thermoelectric conversion layer 16 was confirmed in the same manner as in Example 1, it was the same quadrangular pyramid shape.

Furthermore, about the formed thermoelectric conversion layer 16, the cross-sectional shape of the electricity supply direction, L2 / L1, and the concave part of the upper surface were confirmed similarly to Example 1. FIG.
As a result, the cross-sectional shape in the energization direction is the same trapezoid as in Example 1, that is, the thermoelectric conversion layer 16 has a predetermined shape on the side surface on which the upper electrode 18 is formed in the cross-sectional shape in the energization direction. It was confirmed that the conditions of the thermoelectric conversion element 10 were satisfied.
L1 was 11 mm, L2 was 1.5 mm, and L2 / L1 was 0.14.
In addition, no concave portion was observed on the upper surface of the thermoelectric conversion layer 16.

  Furthermore, the upper electrode 18 was formed in the same manner as in Example 1 on the substrate 12 on which the lower electrode 14 and the thermoelectric conversion layer 16 were formed, and the thermoelectric conversion element 10 was manufactured.

[Example 3]
A carbon nanotube dispersion was prepared in the same manner as in Example 1 except that 10 mL of o-dichlorobenzene was used instead of 10 mL of chloroform in the preparation of the dispersant solution.
To this carbon nanotube dispersion, 200 mg of PC-Z type polycarbonate (Panlite TS-2020, manufactured by Teijin Kasei Co., Ltd.) is added as a binder and rotated using a self-revolving stirrer (ARE-250, manufactured by Shinky Corporation). A thermoelectric conversion material composition (paste) was prepared by stirring at several 2,000 rpm for 5 minutes.

On the other hand, a substrate similar to that in Example 1 was prepared, and the lower electrode 14 was formed on the substrate 12 in the same manner as in Example 1. Next, the prepared thermoelectric conversion material composition was printed on the substrate 12 and the lower electrode 14 in the same manner as in Example 1.
Furthermore, the thermoelectric conversion layer 16 which covers a part of the lower electrode 14 was formed on the substrate 12 by performing the pre-curing step and the main curing step in the same manner as in Example 1.
When the produced thermoelectric conversion layer 16 was confirmed in the same manner as in Example 1, the shape thereof was a quadrangular frustum shape having a concave portion on the upper surface.

Furthermore, about the formed thermoelectric conversion layer, the cross-sectional shape of the electricity supply direction, L2 / L1, and the concave part of the upper surface were confirmed similarly to Example 1.
As a result, the cross-sectional shape in the energizing direction is a trapezoidal shape having a recess in the upper base, that is, the thermoelectric conversion layer 16 has a predetermined shape on the side surface on which the upper electrode 18 is formed in the cross-sectional shape in the energizing direction. It was confirmed that the conditions of the thermoelectric conversion element 10 of the invention were satisfied.
L1 was 9 mm, L2 was 0.2 mm, and L2 / L1 was 0.02.
In addition, a concave portion was observed on the upper surface of the thermoelectric conversion layer.

  Further, the upper electrode was formed on the substrate 12 on which the lower electrode 14 and the thermoelectric conversion layer were formed in the same manner as in Example 1 to produce a thermoelectric conversion element.

[Comparative Example 1]
The lower electrode 14 and the thermoelectric conversion layer were formed on the substrate 12 in the same manner as in Example 1 except that the thermosetting conversion layer was formed by performing the main curing process from the beginning without performing the pre-curing process. The main curing process was 30 minutes.
When the produced thermoelectric conversion layer was confirmed similarly to Example 1, the shape was a rectangular parallelepiped.

Furthermore, about the formed thermoelectric conversion layer, the cross-sectional shape of the electricity supply direction, L2 / L1, and the concave part of the upper surface were confirmed similarly to Example 1.
As a result, the cross-sectional shape in the energization direction was a rectangle, and the angle formed between the upper surface and the side surface of the thermoelectric conversion layer and the angle formed between the side surface of the thermoelectric conversion layer and the substrate 12 were 90 °. That is, it was confirmed that this thermoelectric conversion layer does not satisfy the conditions of the thermoelectric conversion element 10 of the present invention in which the side surface on which the upper electrode 18 is formed is not a predetermined shape in the cross-sectional shape in the energization direction.
L1 was 12 mm, L2 was 1.8 mm, and L2 / L1 was 0.15.
In addition, no concave portion was observed on the upper surface of the thermoelectric conversion layer.

  Further, the upper electrode was formed on the substrate 12 on which the lower electrode 14 and the thermoelectric conversion layer were formed in the same manner as in Example 1 to produce a thermoelectric conversion element.

[Comparative Example 2]
The lower electrode 14 and the thermoelectric conversion layer were formed on the substrate 12 in the same manner as in Example 2 except that the thermosetting conversion layer was formed by performing the main curing process from the beginning without performing the pre-curing step and the heating step. . In addition, the irradiation amount of the ultraviolet rays in the main curing step was 1.5 J / cm ² .
When the produced thermoelectric conversion layer was confirmed similarly to Example 1, the shape was a rectangular parallelepiped.

Furthermore, about the formed thermoelectric conversion layer, the cross-sectional shape of the electricity supply direction, L2 / L1, and the concave part of the upper surface were confirmed similarly to Example 1.
As a result, the cross-sectional shape in the energization direction was a rectangle, and the angle formed between the upper surface and the side surface of the thermoelectric conversion layer and the angle formed between the side surface of the thermoelectric conversion layer and the substrate 12 were 90 °. That is, it was confirmed that this thermoelectric conversion layer does not satisfy the conditions of the thermoelectric conversion element 10 of the present invention in which the side surface on which the upper electrode 18 is formed is not a predetermined shape in the cross-sectional shape in the energization direction.
L1 was 12 mm, L2 was 1.7 mm, and L2 / L1 was 0.14.
In addition, no concave portion was observed on the upper surface of the thermoelectric conversion layer.

  Further, the upper electrode was formed on the substrate 12 on which the lower electrode 14 and the thermoelectric conversion layer were formed in the same manner as in Example 1 to produce a thermoelectric conversion element.

[Performance evaluation]
<Thermo-electromotive force>
When the substrate 12 is heated with a hot plate having a surface temperature of 80 ° C. for the produced thermoelectric conversion element 10, a voltage difference generated between the lower electrode 14 and the upper electrode 18 is expressed by a digital multimeter (R6581, manufactured by Advantest). Measured with

<Properties of upper electrode>
The upper electrode 18 of the produced thermoelectric conversion element 10 was observed with a digital microscope and analyzed using image software, thereby confirming the presence or absence of a fracture portion and a thin film portion of the upper electrode 18.
The case where either one of the fracture portion and the thin film portion is confirmed in the upper electrode 18 is indicated as “present”, and the case where neither the fracture portion or the thin film portion is confirmed in the upper electrode 18 is indicated as “none”. . If the upper electrode 18 does not have a rupture portion or a thin film portion, a high-performance thermoelectric conversion element having excellent electrical conductivity can be obtained.

<Evaluation of electrical conductivity>
At the end in the energizing direction, the resistance between the lower electrode 14 and the upper electrode 18 was measured with a digital multimeter (PC5000, manufactured by Sanwa Denki Keiki Co., Ltd.). A lower resistance value is more effective in forming the upper electrode 18, having a smaller degree of breakage, and excellent electrical conductivity.
The results are shown in the table below. In addition, an electromotive force and resistance value are shown by the relative value which normalized the numerical value of Example 1 as 1.
The results are shown in the table below.

As shown in the above table, in Examples 1 and 2 which are the thermoelectric conversion elements 10 of the present invention, the side surface on which the upper electrode 18 is formed has a predetermined shape in the cross-sectional shape of the thermoelectric conversion layer 16 in the energizing direction. For this reason, even when the thermoelectric conversion layer 16 has a thickness L2 / L1 of 0.15 and 0.12, the upper surface electrode 18 is properly formed without causing a rupture portion or a thin film portion. It has high reliability with no degradation of electrical conductivity caused by it. Moreover, since the thickness of the thermoelectric conversion layer 16 is sufficient in Examples 1 and 2, the thermoelectromotive force is also good.
On the other hand, since the thermoelectric conversion element of Example 3 has L2 / L1 of 0.02 and the thermoelectric conversion layer 16 is thin, the electromotive force is lower than that of Example 1 and the like, and the upper surface has a concave portion so that resistance is increased. However, since the side surface where the upper electrode 18 is formed has a predetermined shape in the cross-sectional shape in the energizing direction, the upper surface electrode 18 is properly formed without causing a rupture portion or a thin film portion, and the upper surface electrode 18 is broken. It has high reliability without any deterioration in the conductivity due to the above.
On the other hand, in the cross-sectional shape (rectangular shape) in the energization direction, both the comparative examples 1 and 2 in which the side surface of the upper electrode 18 does not have a predetermined shape have a broken portion or a thin film portion in the upper electrode 18, It is considered that the conductivity is reduced due to this. In addition, due to the decrease in conductivity, the thermoelectromotive force is low even though the element has the same thickness as in Examples 1 and 2 where L2 / L1 is 0.15 and 0.12.
From the above results, the effects of the present invention are clear.

DESCRIPTION OF SYMBOLS 10 Thermoelectric conversion element 12 Substrate 14 Lower electrode 16, 16a, 16b, 70 Thermoelectric conversion layer 18 Upper electrode

Claims (9)

A substrate,
A lower electrode formed on the substrate;
A thermoelectric conversion layer that covers a portion of the lower electrode and is formed on the substrate;
Provided so as to sandwich the thermoelectric conversion layer together with the lower electrode, which is formed along the surface of the thermoelectric conversion layer that rises from the substrate toward the lower electrode from a position separated from the lower electrode. An upper electrode,
Further, the cross-sectional shape of the thermoelectric conversion layer in the energizing direction between the lower electrode and the upper electrode on the substrate is such that the region facing the upper electrode and descending toward the substrate is the lower electrode in the energizing direction. A thermoelectric conversion element having a shape that inclines so as to be gradually separated from an end of the element.   The thermoelectric conversion element according to claim 1, wherein at least an upper surface of the thermoelectric conversion layer does not have a concave portion.   The upper electrode and the lower electrode have a region overlapping when viewed in a direction perpendicular to the substrate, and the region where the upper electrode and the lower electrode overlap is regarded as the upper surface of the thermoelectric conversion layer. Item 3. The thermoelectric conversion element according to Item 2.   The thermoelectric conversion element according to claim 1, wherein the thermoelectric conversion layer has a planar region on an upper surface.   The thermoelectric conversion element according to claim 1, wherein a cross-sectional shape of the thermoelectric conversion layer is a trapezoid.   The thermoelectric conversion element according to any one of claims 1 to 5, wherein a lower end of an end portion on the upper electrode side of the thermoelectric conversion layer in the energization direction is located closer to the substrate side than an upper surface of the lower electrode.   The length of the thermoelectric conversion layer in the energization direction is L1, and when the height of the thermoelectric conversion layer from the substrate is L2, any one of claims 1 to 6 satisfying "L2 / L1> 0.05". The thermoelectric conversion element according to item.   The thermoelectric conversion element according to any one of claims 1 to 7, wherein the thermoelectric conversion layer is formed by dispersing a material having a thermoelectric conversion function in a resin material.   The thermoelectric conversion element according to claim 8, wherein the resin material is formed of a thermosetting resin or an ultraviolet curable resin.