Thermoelectric conversion element

Abstract

The first thermoelectric conversion module of the thermoelectric conversion element includes: a first substrate having a first main surface and a second main surface; a first electrode provided on the first main surface, a first n-type thermoelectric conversion layer, a first p-type thermoelectric conversion layer in contact with the first n-type thermoelectric conversion layer, and a second electrode, and a sealing layer provided on the first main surface. Each of the pair of thin plate members of the thermoelectric conversion element includes a first high heat conduction portion, a second high heat conduction portion, and a low heat conduction portion. The first electrode, the first n-type thermoelectric conversion layer, the first p-type thermoelectric conversion layer, and the second electrode are arranged in this order along the arrangement direction. The first electrode overlaps with the first high heat conduction portion of the thin plate member, the second electrode overlaps with the second high heat conduction portion of the thin plate member, and the first contact portion between the first n-type thermoelectric conversion layer and the first p-type thermoelectric conversion layer overlaps with the low heat conduction portion of the thin plate member.

Description

Technical Field

[0001] The disclosure of the present application relates to a thermoelectric conversion element. Background Art

[0002] In order to implement power generation using geothermal heat or waste heat from factories, etc., a thermoelectric conversion element is sometimes used. The following Patent Document 1 discloses the following solution: A flexible substrate having a pattern layer composed of a resin layer and a metal layer is provided on both surfaces of a thermoelectric conversion module having a P-type thermoelectric element member and an N-type thermoelectric element member. In the following Patent Document 1, the metal layer included in one flexible substrate overlaps with one electrode included in the thermoelectric conversion module, and the metal layer included in the other flexible substrate overlaps with the other electrode included in the thermoelectric conversion module. In the above solution, by setting one flexible substrate to a high temperature state and the other flexible substrate to a low temperature state, a temperature difference is generated in the plane direction of the thermoelectric conversion module. Thereby, an electromotive force is generated in the thermoelectric conversion module.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent No. 4895293 Gazette Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] In the above thermoelectric conversion element, further improvement in thermoelectric conversion efficiency is required. Therefore, an object of one aspect of the disclosure of the present application is to provide a thermoelectric conversion element capable of improving thermoelectric conversion efficiency.

[0008] Means for Solving the Problems

[0009] A thermoelectric conversion element according to one aspect of the disclosure of the present application is as follows.

[0010] [1]A thermoelectric conversion element includes a first thermoelectric conversion module and a pair of thin plate members sandwiching the first thermoelectric conversion module. In this thermoelectric conversion element, the first thermoelectric conversion module includes: a first substrate having a first main surface and a second main surface on the opposite side of the first main surface; a first electrode provided on the first main surface, a first n-type thermoelectric conversion layer electrically connected to the first electrode, a first p-type thermoelectric conversion layer in contact with the first n-type thermoelectric conversion layer, and a second electrode electrically connected to the first p-type thermoelectric conversion layer; and a sealing layer provided on the first main surface and covering the first electrode, the first n-type thermoelectric conversion layer, the first p-type thermoelectric conversion layer, and the second electrode. Each of the pair of thin plate members includes a first high heat conduction portion, a second high heat conduction portion, and a low heat conduction portion. The first electrode, the first n-type thermoelectric conversion layer, the first p-type thermoelectric conversion layer, and the second electrode are arranged in sequence along an arrangement direction orthogonal to the thickness direction of the first substrate. The first electrode overlaps with the first high heat conduction portion of each of the pair of thin plate members in the thickness direction, the second electrode overlaps with the second high heat conduction portion of each of the pair of thin plate members in the thickness direction, and the first contact portion between the first n-type thermoelectric conversion layer and the first p-type thermoelectric conversion layer overlaps with the low heat conduction portion of each of the pair of thin plate members in the thickness direction.

[0011] [2]The thermoelectric conversion element according to [1], further including a second thermoelectric conversion module located on the side opposite to the first thermoelectric conversion module across one of the pair of thin plate members in the thickness direction. The second thermoelectric conversion module includes: a second substrate having a third main surface on the first thermoelectric conversion module side in the thickness direction and a fourth main surface on the opposite side of the third main surface; a third electrode provided on the fourth main surface, a second n-type thermoelectric conversion layer electrically connected to the third electrode, a second p-type thermoelectric conversion layer in contact with the second n-type thermoelectric conversion layer, and a fourth electrode electrically connected to the second p-type thermoelectric conversion layer; and a second sealing layer provided on the fourth main surface and covering the third electrode, the second n-type thermoelectric conversion layer, the second p-type thermoelectric conversion layer, and the fourth electrode.

[0012] [3]The thermoelectric conversion element according to [2], wherein the third electrode overlaps with the first high heat conduction portion of each of the pair of thin plate members and the first electrode in the thickness direction, the fourth electrode overlaps with the second high heat conduction portion of each of the pair of thin plate members and the second electrode in the thickness direction, and the second contact portion between the second n-type thermoelectric conversion layer and the second p-type thermoelectric conversion layer overlaps with the low heat conduction portion of each of the pair of thin plate members in the thickness direction.

[0013] [4]The thermoelectric conversion element according to [2], wherein the third electrode overlaps with the second high heat conduction portions and the second electrodes of the pair of thin plate members in the thickness direction, the fourth electrode overlaps with the first high heat conduction portions and the first electrodes of the pair of thin plate members in the thickness direction, and the second contact portion between the second n-type thermoelectric conversion layer and the second p-type thermoelectric conversion layer overlaps with the low heat conduction portions of the pair of thin plate members in the thickness direction.

[0014] [5]The thermoelectric conversion element according to any one of [2] to [4], wherein the second thermoelectric conversion module is electrically connected to the first thermoelectric conversion module.

[0015] [6]The thermoelectric conversion element according to any one of [2] to [5], wherein the second sealing layer forms the outermost surface on the fourth main surface.

[0016] [7]The thermoelectric conversion element according to any one of [2] to [5], further comprising a thin plate member provided separately with respect to the pair of thin plate members, and the separately provided thin plate member is located on the side opposite to the first thermoelectric conversion module with the second thermoelectric conversion module interposed therebetween in the thickness direction.

[0017] [8]The thermoelectric conversion element according to any one of [1] to [7], wherein the heat conductivity of the low heat conduction portion is 0.2 W / mK or less.

[0018] [9]The thermoelectric conversion element according to [8], wherein the heat conductivity of the low heat conduction portion is 0.08 W / mK or less.

[0019]

[10] The thermoelectric conversion element according to any one of [1] to [9], wherein the heat conductivity of the first high heat conduction portion and the second high heat conduction portion is 5 W / mK or more.

[0020]

[11] The thermoelectric conversion element according to any one of [1] to

[10] , wherein the heat conductivity of the first electrode and the second electrode is 5 W / mK or more.

[0021]

[12] The thermoelectric conversion element according to any one of [1] to

[11] , wherein the substrate exhibits flexibility.

[0022]

[13] The thermoelectric conversion element according to any one of [1] to

[12] , wherein the interval from the first high heat conduction portion to the first contact portion along the arrangement direction is 5 times or more the length of the first high heat conduction portion along the thickness direction, and the interval from the first high heat conduction portion to the second contact portion along the arrangement direction is 5 times or more the length of the first high heat conduction portion along the thickness direction.

[0023] Advantages of the Invention

[0024] According to one aspect of the disclosure of the present application, a thermoelectric conversion element capable of improving thermoelectric conversion efficiency can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic cross-sectional view showing the thermoelectric conversion element of the present embodiment.

[0026] Figure 2 is an extraction Figure 1 of a part of the figure.

[0027] Figure 3 is a schematic cross-sectional view showing the thermoelectric conversion element of the first modification.

[0028] Figure 4 is a schematic cross-sectional view showing the thermoelectric conversion element of the second modification.

[0029] Figure 5 is a schematic cross-sectional view showing the first simulation condition.

[0030] Figure 6 (a) and (b) of are graphs showing the first simulation result.

[0031] Figure 7 is a schematic cross-sectional view showing the second simulation condition.

[0032] Figure 8 is a graph showing the second simulation result.

[0033] Figure 9 is a schematic cross-sectional view showing the third simulation condition.

[0034] Figure 10 is a graph showing the third simulation result.

[0035] Figure 11 (a) of is a schematic cross-sectional view of the thermoelectric conversion element of the first reference example, Figure 11 (b) of is a schematic cross-sectional view of the thermoelectric conversion element of the second reference example. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0036] Hereinafter, an embodiment of one aspect of the disclosure of the present application will be described in detail with reference to the drawings. In the following description, the same elements or elements having the same function are denoted by the same reference numerals, and redundant description is omitted. The terms "same" and similar terms in this specification are not limited to "exactly the same".

[0037] First, with reference to Figure 1 and Figure 2 the structure of the thermoelectric conversion element of the present embodiment will be described. Figure 1 is a schematic cross-sectional view showing the thermoelectric conversion element of the present embodiment. Figure 2 is an extractionFigure 1 a figure formed by a part of Figure 1 The thermoelectric conversion element 1 shown is an element capable of generating electricity by supplying heat from the outside. The thermoelectric conversion element 1 is, for example, an element that converts heat into electricity using the temperature difference inside it. The thermoelectric conversion element 1 is a so-called in-plane type element. Therefore, the thermoelectric conversion element 1 tends to be excellent in processability and flexibility compared to, for example, a π-type element (a cross-plane type element). Therefore, the thermoelectric conversion element 1 can be arranged, for example, along the side surface of a cylindrical tube or the like used for recovering waste heat from a factory. That is, the thermoelectric conversion element 1 can be easily arranged at various positions. Therefore, the thermoelectric conversion element 1 is used, for example, as a power source for a sensor for a plant using waste heat. Moreover, the contact resistance between the thermoelectric conversion material and the electrode included in the thermoelectric conversion element 1 also tends to be lower than that of a π-type module. Hereinafter, the temperature of each component of the thermoelectric conversion element 1 is measured under the condition of natural convection of air.

[0038] The thermoelectric conversion element 1 includes thermoelectric conversion modules 2A and 2B and thin plate members 3A and 3B. The thermoelectric conversion modules 2A and 2B and the thin plate members 3A and 3B are alternately laminated. In the present embodiment, the thin plate member 3A, the thermoelectric conversion module 2A (first thermoelectric conversion module), the thin plate member 3B, and the thermoelectric conversion module 2B (second thermoelectric conversion module) are arranged in this order. The thermoelectric conversion modules 2A and 2B have the same shape as each other, and the thin plate members 3A and 3B have the same shape as each other. That is, the thermoelectric conversion modules 2A and 2B have the same components as each other, and the thin plate members 3A and 3B have the same components as each other. The lamination direction of the thermoelectric conversion modules 2A and 2B and the thin plate members 3A and 3B corresponds to the direction along the thickness of the thermoelectric conversion modules 2A and 2B and the thin plate members 3A and 3B. Hereinafter, the direction along the thickness of the thermoelectric conversion modules 2A and 2B and the thin plate members 3A and 3B is only represented as the thickness direction D1. Observation from the thickness direction D1 corresponds to a top view. In Figure 2 FIG. shows the thermoelectric conversion module 2A and a pair of thin plate members 3A and 3B that sandwich the thermoelectric conversion module 2A. The thermoelectric conversion element according to one aspect of the present disclosure may include Figure 2 the structure shown.

[0039] The thermoelectric conversion module 2A is a thermoelectric conversion part in the thermoelectric conversion element 1, and has a substrate 11 (first substrate), electrodes 12 and 13 (first and second electrodes), an element part 14, and a sealing layer 15 (first sealing layer).

[0040] The substrate 11 is, for example, a thin plate member made of a resin exhibiting heat resistance and flexibility, and has a substantially flat plate shape. The resin constituting the substrate 11 is, for example, a (meth)acrylic resin, a (meth)acrylonitrile resin, a polyamide resin, a polycarbonate resin, a polyether resin, a polyester resin, an epoxy resin, a silicone oxane resin, a polyimide resin, a polysulfone resin, etc. The thickness of the substrate 11 is, for example, 5 μm or more and 50 μm or less. The thermal conductivity of the substrate 11 is, for example, 0.1 W / mK (equivalent to 0.1 watt per meter per (Kelvin) degree and 0.1 W×m -1 ×K -1 ) or more and 0.3 W / mK or less. By the thermal conductivity of the substrate 11 being 0.3 W / mK or less, a temperature difference can be generated inside the element portion 14. The substrate 11 has a main surface 11a (first main surface) and a main surface 11b (second main surface) located on the opposite side of the main surface 11a. The main surfaces 11a and 11b are surfaces that intersect with the direction along the thickness of the substrate 11. The shapes of the main surfaces 11a and 11b are not particularly limited, and are, for example, polygons, circles, ellipses, etc.

[0041] The electrode 12 is a member constituting the terminal included in the thermoelectric conversion element 1, and is a conductor provided on the main surface 11a of the substrate 11. The electrode 12 is, for example, a conductor made of metal, alloy, or conductive resin. When the electrode 12 is made of metal or alloy, the electrode 12 is formed on the substrate 11 by various dry methods, for example. The dry method is, for example, a physical vapor deposition method (PVD method), patterning of a metal foil or alloy foil, etc. The electrode 12 can be formed using a nano paste in which metal particles are dispersed, etc. The shape of the electrode 12 in a plan view is not particularly limited, and is, for example, a polygon, a circle, an ellipse, etc. The thickness of the electrode 12 is, for example, 6 μm or more and 70 μm or less. The thermal conductivity of the electrode 12 is, for example, 5 W / mK or more. In this case, the electrode 12 tends to be easily heated from the outside. The thermal conductivity of the electrode 12 can be, for example, 30 W / mK or more.

[0042] Similarly to the electrode 12, the electrode 13 is a member constituting the terminal included in the thermoelectric conversion element 1, and is a conductor provided on the main surface 11a of the substrate 11. The electrode 13 is separated from the electrode 12. The electrode 13 is formed simultaneously with the electrode 12. Therefore, the electrode 13 is made of the same material as the electrode 12. The shape of the electrode 13 in a plan view is not particularly limited, and is, for example, a polygon, a circle, an ellipse, etc. Similarly to the electrode 12, the thermal conductivity of the electrode 13 is, for example, 5 W / mK or more. The thermal conductivity of the electrode 13 can be, for example, 30 W / mK or more.

[0043] The element part 14 is a component that performs thermoelectric conversion in the thermoelectric conversion element 1. The shape of the element part 14 in a plan view is not particularly limited, and for example, it is a polygon, a circle, an ellipse, or the like. The element part 14 has an n-type thermoelectric conversion layer 14a and a p-type thermoelectric conversion layer 14b. In the present embodiment, the n-type thermoelectric conversion layer 14a and the p-type thermoelectric conversion layer 14b have the same shape as each other, but this is not limiting.

[0044] The n-type thermoelectric conversion layer 14a is provided on the main surface 11a of the substrate 11 and is electrically connected to the electrode 12. In the present embodiment, the n-type thermoelectric conversion layer 14a is located between the electrodes 12 and 13 and is in contact with the electrode 12. The n-type thermoelectric conversion layer 14a covers a part of the electrode 12. The n-type thermoelectric conversion layer 14a is, for example, an n-type semiconductor layer. The n-type thermoelectric conversion layer 14a, for example, contains a composite of an inorganic substance and an organic substance, or a composite of a plurality of organic substances. The inorganic substance is, for example, titanium sulfide (TiS2), bismuth telluride (Bi2Te3), skutterudite, nickel (Ni), or the like. The organic substance is, for example, an n-type single-walled carbon nanotube (SWCNT), tetrathiafulvalene-tetracyano-p-quinodimethane (TTF-TCNQ), or the like. The n-type thermoelectric conversion layer 14a is formed, for example, by various dry methods or wet methods. The wet method is, for example, a doctor blade coating method, a dip coating method, a spray coating method, a spin coating method, an inkjet method, or the like. The thickness of the n-type thermoelectric conversion layer 14a is, for example, 9 μm or more and 200 μm or less. The thermal conductivity of the n-type thermoelectric conversion layer 14a is, for example, 0.01 W / mK or more and 0.5 W / mK or less. In this case, a temperature gradient can be easily formed inside the n-type thermoelectric conversion layer 14a. The thickness of the n-type thermoelectric conversion layer 14a corresponds to the thickness of the portion that does not overlap with the electrode 12 in the thickness direction D1.

[0045] The p-type thermoelectric conversion layer 14b is provided on the main surface 11a of the substrate 11 and is in contact with the n-type thermoelectric conversion layer 14a. In the present embodiment, the p-type thermoelectric conversion layer 14b is located between the electrodes 12 and 13 and is on the side opposite to the electrode 12 with the n-type thermoelectric conversion layer 14a interposed therebetween. The p-type thermoelectric conversion layer 14b covers a part of the electrode 13 and is in contact with this part. The p-type thermoelectric conversion layer 14b is, for example, a p-type semiconductor layer. The p-type thermoelectric conversion layer 14b, for example, contains carbon nanotubes and a conductive polymer different from the carbon nanotubes. The carbon nanotubes are, for example, p-type SWCNTs or the like. The conductive polymer is, for example, poly(3,4-ethylenedioxythiophene) (PEDOT), polystyrenesulfonic acid (PSS), or the like. In the p-type thermoelectric conversion layer 14b, the carbon nanotubes and the conductive polymer may aggregate. In the p-type thermoelectric conversion layer 14b, a porous structure in which the carbon nanotubes are bound to each other by the conductive polymer may be included.

[0046] Similar to the n-type thermoelectric conversion layer 14a, the p-type thermoelectric conversion layer 14b is formed, for example, by various dry processes or wet processes. The thickness of the p-type thermoelectric conversion layer 14b is, for example, 9 μm or more and 200 μm or less. The thermal conductivity of the p-type thermoelectric conversion layer 14b is, for example, 0.01 W / mK or more and 0.5 W / mK or less. In this case, a temperature gradient can be easily formed inside the p-type thermoelectric conversion layer 14b. The thickness of the p-type thermoelectric conversion layer 14b corresponds to the thickness of the portion that does not overlap with the electrodes 13 in the thickness direction D1.

[0047] The sealing layer 15 is a resin layer that protects the electrodes 12 and 13, the n-type thermoelectric conversion layer 14a, and the p-type thermoelectric conversion layer 14b. The sealing layer 15 is provided on the main surface 11a and covers the electrodes 12 and 13, the n-type thermoelectric conversion layer 14a, and the p-type thermoelectric conversion layer 14b. The resin constituting the sealing layer 15 is, for example, a (meth)acrylic resin, a (meth)acrylonitrile resin, a polyamide resin, a polycarbonate resin, a polyether resin, a polyester resin, an epoxy resin, a silicone resin, a polyimide resin, a polysulfone resin, or the like. The thickness of the sealing layer 15 is, for example, 50 μm or more and 200 μm or less, and is smaller than the intervals S1 and S2 described later. The thermal conductivity of the sealing layer 15 is, for example, 0.1 W / mK or more and 0.5 W / mK or less.

[0048] The electrodes 12, the n-type thermoelectric conversion layer 14a, the p-type thermoelectric conversion layer 14b, and the electrode 13 are arranged in this order along the arrangement direction D2 orthogonal to the thickness direction D1. Therefore, the electrode 12 is located on one end side of the thermoelectric conversion element 1 in the arrangement direction D2, and the electrode 13 is located on the other end side of the thermoelectric conversion element 1 in the arrangement direction D2. Therefore, in view of the difference in the thermal conductivity of the respective components of the thermoelectric conversion element 1, for example, when the thermoelectric conversion element 1 is heated from the substrate 11 side, the temperature of the portion of the n-type thermoelectric conversion layer 14a that tends to contact the electrode 12 becomes the highest, and the temperature of the portion of the p-type thermoelectric conversion layer 14b that tends to contact the electrode 13 becomes the highest. The temperature of the contact portion CP between the n-type thermoelectric conversion layer 14a and the p-type thermoelectric conversion layer 14b tends to become the lowest. Therefore, a temperature gradient can be generated along the arrangement direction D2 in each of the n-type thermoelectric conversion layer 14a and the p-type thermoelectric conversion layer 14b. In a plan view, the contact portion CP extends, for example, in a direction intersecting both the thickness direction D1 and the arrangement direction D2. In a plan view, the contact portion CP may be linear, may be wavy, or may be circular arc-shaped.

[0049] The length of the n-type thermoelectric conversion layer 14a along the alignment direction D2 is longer than the length of the sealing layer 15 along the thickness direction D1. The length of the n-type thermoelectric conversion layer 14a along the alignment direction D2 is, for example, 5 times or more, or 10 times or more the length of the sealing layer 15 along the thickness direction D1. As described above, the thermal conductivity of the sealing layer 15 is, for example, 0.1 W / mK or more and 0.5 W / mK or less. Therefore, for example, with respect to the heat conducted from the electrode 12 to the sealing layer 15, it is easier to reach the upper surface 15a of the sealing layer 15 than the contact portion CP. In other words, it is difficult for the contact portion CP to be heat-transferred via the sealing layer 15. Instead, the heat of the contact portion CP tends to be released to the outside via the sealing layer 15.

[0050] Similar to the thermoelectric conversion module 2A, the thermoelectric conversion module 2B is a thermoelectric conversion portion in the thermoelectric conversion element 1. As described above, since the thermoelectric conversion modules 2A and 2B have the same constituent elements, the thermoelectric conversion module 2B also has a substrate 11 (second substrate), an electrode 12 (third electrode), an electrode 13 (fourth electrode), an element portion 14, and a sealing layer 15 (second sealing layer). In the thermoelectric conversion element 1, the sealing layer 15 constitutes the outermost layer located on the main surface 11a of the substrate 11 (on the fourth main surface). In the present embodiment, this outermost layer is composed only of the sealing layer 15.

[0051] In the thermoelectric conversion modules 2A and 2B, the electrodes 12 overlap each other in the thickness direction D1, the electrodes 13 overlap each other in the thickness direction D1, the n-type thermoelectric conversion layers 14a overlap each other in the thickness direction D1, and the p-type thermoelectric conversion layers 14b overlap each other in the thickness direction D1. In the present embodiment, the thermoelectric conversion module 2A is electrically connected to the thermoelectric conversion module 2B, but it is not limited thereto. When the thermoelectric conversion module 2A and the thermoelectric conversion module 2B are electrically connected, the thermoelectric conversion modules 2A and 2B may be in a series connection relationship or a parallel connection relationship.

[0052] The thin plate member 3A is a member disposed between the thermoelectric conversion module 2A and the heat source, and is provided on the main surface 11b of the substrate 11. Therefore, the heat generated from the heat source is conducted to the thermoelectric conversion module 2A via the thin plate member 3A. The thin plate member 3A has a first high thermal conductivity portion 21, a second high thermal conductivity portion 22, and a low thermal conductivity portion 23.

[0053] The first high heat conduction part 21 and the second high heat conduction part 22 are parts that exhibit a higher heat conductivity than the low heat conduction part 23 and are separated from each other. The first high heat conduction part 21 overlaps with the electrode 12 in the thickness direction D1, and the second high heat conduction part 22 overlaps with the electrode 13 in the thickness direction D1. The shapes of the first high heat conduction part 21 and the second high heat conduction part 22 in plan view are not particularly limited, and for example, they are polygons, circles, ellipses, etc. In plan view, the shape of the first high heat conduction part 21 and the shape of the electrode 12 may be the same as or different from each other. Similarly, in plan view, the shape of the second high heat conduction part 22 and the shape of the electrode 13 may be the same as or different from each other. Each of the first high heat conduction part 21 and the second high heat conduction part 22 contains, for example, a metal (such as silver, copper, aluminum, etc.), carbon, etc. Each of the first high heat conduction part 21 and the second high heat conduction part 22 may contain ceramics such as boron nitride and aluminum nitride that exhibit high heat conductivity. The heat conductivity of each of the first high heat conduction part 21 and the second high heat conduction part 22 is, for example, 5 W / mK or more and 400 W / mK or less. Thereby, when heating the thin plate member 3A, heat is transferred well to the electrode 12 and the electrode 13 via the first high heat conduction part 21 and the second high heat conduction part 22, respectively.

[0054] From the viewpoint of improving the heat transfer efficiency from the first high heat conduction part 21 to the electrode 12, in plan view, the electrode 12 may be located at a position more inward than the edge of the first high heat conduction part 21, and the edge of the electrode 12 and the edge of the first high heat conduction part 21 may completely overlap. Similarly, in plan view, the electrode 13 may be located at a position more inward than the edge of the second high heat conduction part 22, and the edge of the electrode 13 and the edge of the second high heat conduction part 22 may completely overlap. From the viewpoint of expanding the temperature gradient along the arrangement direction D2 inside the n-type thermoelectric conversion layer 14a, the first high heat conduction part 21 may be located on the end side in the arrangement direction D2 that is closer to the electrode 12. That is, in plan view, the edge of the first high heat conduction part 21 on the above-mentioned end side may be located on the outer side compared to the edge of the electrode 12 on the above-mentioned end side. Similarly, the second high heat conduction part 22 may be located on the other end side in the arrangement direction D2 that is closer to the electrode 13.

[0055] The length T1 of the first high heat conduction part 21 in the thickness direction D1 is, for example, 50 μm or more and 500 μm or less. When viewed from above, the interval S1 from the first high heat conduction part 21 (the contact part of the first high heat conduction part 21 and the low heat conduction part 23) to the contact part CP in the arrangement direction D2 is, for example, 5 times or more, or 10 times or more, the length T1 of the first high heat conduction part 21. In this case, a temperature gradient inside the n-type thermoelectric conversion layer 14a in the arrangement direction D2 can be generated well. Similarly, the length T2 of the second high heat conduction part 22 in the thickness direction D1 is, for example, 50 μm or more and 500 μm or less. When viewed from above, the interval S2 from the second high heat conduction part 22 (the contact part of the second high heat conduction part 22 and the low heat conduction part 23) to the contact part CP in the arrangement direction D2 is, for example, 5 times or more, or 10 times or more, the length T2 of the second high heat conduction part 22. In this case, a temperature gradient inside the p-type thermoelectric conversion layer 14b in the arrangement direction D2 can be generated well. Depending on the length T1 of the first high heat conduction part 21, the interval S1 can be 5 times or more, can be 10 times or more, and can be 20 times or less the length T1. Similarly, the interval S2 can be 5 times or more, can be 10 times or more, and can be 20 times or less the length T2. For example, when the length T1 is 100 μm or more and 200 μm or less, the interval S1 is preferably 5 times or more, and more preferably 10 times or more, the length T1.

[0056] The low heat conduction part 23 is a part showing a lower heat conductivity than the first high heat conduction part 21 and the second high heat conduction part 22, and is the main part of the thin plate member 3. The low heat conduction part 23 overlaps at least the contact part CP in the thickness direction D1 and covers most of the main surface 11b. In the present embodiment, the low heat conduction part 23 overlaps most of the n-type thermoelectric conversion layer 14a and the p-type thermoelectric conversion layer 14b in addition to the contact part CP in the thickness direction D1. The low heat conduction part 23 fills the gap between the first high heat conduction part 21 and the second high heat conduction part 22 in the arrangement direction D2. The low heat conduction part 23 contains, for example, cellulose nanofibers (CNF), silica aerogel, etc. The low heat conduction part 23 can be a foam.

[0057] The heat conductivity of the low heat conduction part 23 is significantly lower than that of the first high heat conduction part 21 and the second high heat conduction part 22, and is, for example, 0.01 W / mK or more and 0.2 W / mK or less. Thus, when the thin plate member 3A is heated, the portion on the main surface 11a of the thermoelectric conversion module 2A that overlaps with the low heat conduction part 23 is difficult to be heated. Therefore, since the contact part CP and its vicinity are difficult to be heated, each of the temperature gradients in the n-type thermoelectric conversion layer 14a and the p-type thermoelectric conversion layer 14b along the arrangement direction D2 can be generated favorably. From the viewpoint of generating the above temperature gradient more favorably, the heat conductivity of the low heat conduction part 23 can be 0.08 W / mK or less.

[0058] The thin plate member 3A is formed directly on the main surface 11b, for example. In this case, each of the first high heat conduction part 21, the second high heat conduction part 22, and the low heat conduction part 23 is formed by various dry methods or wet methods. Alternatively, the thin plate member 3A can be attached to the main surface 11b using an adhesive (not shown). The adhesive is, for example, (meth)acrylic resin, (meth)acrylonitrile resin, polyamide resin, polycarbonate resin, polyether resin, polyester resin, epoxy resin, silicone resin, polyimide resin, polysulfone resin, or the like. The heat conductivity of the adhesive is, for example, at the same level as that of the substrate 11.

[0059] The thin plate member 3B is a member disposed between the thermoelectric conversion modules 2A and 2B in the thickness direction D1. The thin plate member 3B is provided on the sealing layer 15 of the thermoelectric conversion module 2A and on the main surface 11b (the third main surface) of the substrate 11 of the thermoelectric conversion module 2B. The thin plate member 3B is formed directly on the main surface 11b of the substrate 11 of the thermoelectric conversion module 2B, for example. In this case, the thin plate member 3B is attached to the sealing layer 15 of the thermoelectric conversion module 2A using an adhesive (not shown). Alternatively, the thin plate member 3B is attached to both the thermoelectric conversion modules 2A and 2B using an adhesive (not shown).

[0060] As described above, since the thin plate members 3A and 3B have the same constituent elements, the thin plate member 3B also has the first high heat conduction portion 21, the second high heat conduction portion 22, and the low heat conduction portion 23. The first high heat conduction portion 21 of the thin plate member 3B is located between the electrodes 12 of the thermoelectric conversion modules 2A and 2B in the thickness direction D1, and the second high heat conduction portion 22 of the thin plate member 3B is located between the electrodes 13 of the thermoelectric conversion modules 2A and 2B in the thickness direction D1. Therefore, when the thin plate member 3A is heated, heat is transferred well from the electrode 12 of the thermoelectric conversion module 2A to the electrode 12 of the thermoelectric conversion module 2B via the first high heat conduction portion 21 of the thin plate member 3B. When the thin plate member 3A is heated, heat is transferred well from the electrode 13 of the thermoelectric conversion module 2A to the electrode 13 of the thermoelectric conversion module 2B via the second high heat conduction portion 22 of the thin plate member 3B.

[0061] On the other hand, the low heat conduction portion 23 of the thin plate member 3B is located at least between the contact portions CP of the element portions 14 of the thermoelectric conversion modules 2A and 2B in the thickness direction D1. Therefore, when the thin plate member 3A is heated, heat transfer from the element portion 14 of the thermoelectric conversion module 2A to the element portion 14 of the thermoelectric conversion module 2B is well suppressed by the low heat conduction portion 23 of the thin plate member 3B.

[0062] Summarizing the above description, in the thermoelectric conversion element 1, the electrodes 12 of the thermoelectric conversion modules 2A and 2B overlap with the first high heat conduction portions 21 of the thin plate members 3A and 3B in the thickness direction D1, and the electrodes 13 of the thermoelectric conversion modules 2A and 2B overlap with the second high heat conduction portions 22 of the thin plate members 3A and 3B in the thickness direction D1. The contact portion CP (first contact portion) between the n-type thermoelectric conversion layer 14a (first n-type thermoelectric conversion layer) and the p-type thermoelectric conversion layer 14b (first p-type thermoelectric conversion layer) in the thermoelectric conversion module 2A and the contact portion CP (second contact portion) between the n-type thermoelectric conversion layer 14a (second n-type thermoelectric conversion layer) and the p-type thermoelectric conversion layer 14b (second p-type thermoelectric conversion layer) in the thermoelectric conversion module 2B overlap with the low heat conduction portion 23 of the thin plate members 3A and 3B in the thickness direction D1.

[0063] The thermoelectric conversion element 1 may further have a structure other than the above. For example, the thermoelectric conversion element 1 may include wirings for electrically connecting the thermoelectric conversion modules 2A and 2B, wirings for electrically connecting other thermoelectric conversion elements, wirings for extracting electric power to an external circuit, and the like.

[0064] In the thermoelectric conversion module 2A of the thermoelectric conversion element 1 of the embodiment described above, the electrode 12 overlaps with the first high heat conduction portion 21 in the thickness direction D1, the electrode 13 overlaps with the second high heat conduction portion 22 in the thickness direction D1, and the contact portion CP between the n-type thermoelectric conversion layer 14a and the p-type thermoelectric conversion layer 14b overlaps with the low heat conduction portion 23 in the thickness direction D1. Thus, when the thermoelectric conversion module 2A is heated from the side of the thin plate member 3A, in the n-type thermoelectric conversion layer 14a, the temperature tends to be the lowest at the contact portion CP and the highest at the portion closest to the electrode 12. Similarly, in the p-type thermoelectric conversion layer 14b, the temperature tends to be the lowest at the contact portion CP and the highest at the portion closest to the electrode 13. In this case, for example, compared with setting one electrode side to a high temperature state and the other electrode side to a low temperature state in the arrangement direction D2, the temperature gradients of both the n-type thermoelectric conversion layer 14a and the p-type thermoelectric conversion layer 14b in the arrangement direction D2 tend to become larger. In other words, compared with setting one electrode side to a high temperature state and the other electrode side to a low temperature state in the arrangement direction D2, the temperature differences between the two ends of the n-type thermoelectric conversion layer 14a and the temperature differences between the two ends of the p-type thermoelectric conversion layer 14b in the arrangement direction tend to expand. Therefore, according to the thermoelectric conversion element 1 of the present embodiment, the thermoelectric conversion efficiency can be improved.

[0065] Moreover, in the present embodiment, in each of the thermoelectric conversion modules 2A and 2B, the electrode 12 overlaps with the first high heat conduction portion 21 of the thin plate members 3A and 3B in the thickness direction D1, the electrode 13 overlaps with the second high heat conduction portion 22 of the thin plate members 3A and 3B in the thickness direction D1, and the contact portion CP overlaps with the low heat conduction portion 23 of the thin plate members 3A and 3B in the thickness direction D1. Thus, also in the thermoelectric conversion module 2B, in the n-type thermoelectric conversion layer 14a, the temperature tends to be the lowest at the contact portion CP and the highest at the portion closest to the electrode 12. In the p-type thermoelectric conversion layer 14b, the temperature tends to be the lowest at the contact portion CP and the highest at the portion closest to the electrode 13. Thereby, the temperature gradients within the element portion 14 in each of the thermoelectric conversion modules 2A and 2B stacked along the thickness direction D1 tend to expand. Therefore, according to the thermoelectric conversion element 1 of the present embodiment, it is possible to achieve both a further improvement in the thermoelectric conversion efficiency of the thermoelectric conversion element 1 and miniaturization in a top view.

[0066] In the present embodiment, the thermoelectric conversion module 2A may be electrically connected to the thermoelectric conversion module 2B. In this case, the electromotive force or current capacity of the thermoelectric conversion element 1 can be increased.

[0067] In the present embodiment, the sealing layer 15 of the thermoelectric conversion module 2B constitutes the outermost surface located on the main surface 11a. In this case, it is likely to be able to maintain the temperature gradient of the element portion 14 in the thermoelectric conversion module 2B.

[0068] In the present embodiment, the thermal conductivity of the low thermal conductivity portion 23 can be 0.2 W / mK or less. In this case, it is possible to satisfactorily enlarge the temperature difference between both ends of each of the n-type thermoelectric conversion layer 14a and the p-type thermoelectric conversion layer 14b in the arrangement direction D2. When the thermal conductivity of the low thermal conductivity portion 23 is 0.08 W / mK or less, the above temperature difference can be enlarged more satisfactorily.

[0069] In the present embodiment, the thermal conductivity of the first high thermal conductivity portion 21 and the second high thermal conductivity portion 22 can be 5 W / mK or more. In this case, it is possible to satisfactorily enlarge the temperature difference between both ends of each of the n-type thermoelectric conversion layer 14a and the p-type thermoelectric conversion layer 14b in the arrangement direction D2.

[0070] In the present embodiment, the thermal conductivity of the electrodes 12 and 13 can be 5 W / mK or more. In this case, it is possible to satisfactorily enlarge the temperature difference between both ends of each of the n-type thermoelectric conversion layer 14a and the p-type thermoelectric conversion layer 14b in the arrangement direction D2.

[0071] In the present embodiment, the substrate 11 exhibits flexibility. Therefore, the thermoelectric conversion element 1 can exhibit flexibility. Thus, for example, the thermoelectric conversion element 1 can be easily disposed along the surface of a cylindrical tube. That is, the limitation on the mounting position of the thermoelectric conversion element 1 can be alleviated.

[0072] In the present embodiment, the interval S1 from the first high thermal conductivity portion 21 to the contact portion CP along the arrangement direction D2 is 5 times or more, or 10 times or more the length T1 of the first high thermal conductivity portion 21 along the thickness direction D1, and the interval S2 from the second high thermal conductivity portion 22 to the contact portion CP along the arrangement direction D2 is 5 times or more, or 10 times or more the length T2 of the second high thermal conductivity portion 22 along the thickness direction D1. Therefore, it is possible to satisfactorily enlarge the temperature difference between both ends of each of the n-type thermoelectric conversion layer 14a and the p-type thermoelectric conversion layer 14b in the arrangement direction D2.

[0073] Hereinafter, with reference to Figure 3 and Figure 4 a modification of the above embodiment will be described.

[0074] Figure 3 is a schematic cross-sectional view of a thermoelectric conversion element according to a first modification. As Figure 3As shown, the thermoelectric conversion element 1A of the first modified example has, in addition to the structure of the thermoelectric conversion element 1, a thin plate member 3C provided separately from the thin plate members 3A and 3B. The thin plate member 3C is located on the side opposite to the thermoelectric conversion module 2A across the thermoelectric conversion module 2B in the thickness direction D1. Therefore, the thermoelectric conversion module 2B is sandwiched between the thin plate members 3B and 3C in the thickness direction D1. The thin plate member 3C is configured as a part of the outermost layer of the thermoelectric conversion element 1A.

[0075] The thin plate member 3C has the same constituent elements as the thin plate members 3A and 3B. That is, the thin plate member 3C has a first high heat conduction part 21, a second high heat conduction part 22, and a low heat conduction part 23. The first high heat conduction part 21 of the thin plate member 3C overlaps with the electrodes 12 of the thermoelectric conversion modules 2A and 2B and the first high heat conduction part 21 of the thin plate members 3A and 3B in the thickness direction D1. The second high heat conduction part 22 of the thin plate member 3C overlaps with the electrodes 13 of the thermoelectric conversion modules 2A and 2B and the second high heat conduction part 22 of the thin plate members 3A and 3B in the thickness direction D1.

[0076] In the first modified example described above, the same operational effects as those of the above-described embodiment are also obtained.

[0077] Figure 4 is a schematic cross-sectional view of the thermoelectric conversion element of the second modified example. As Figure 4 shown, the thermoelectric conversion element 1B of the second modified example includes thermoelectric conversion modules 2C to 2E and thin plate members 3D to 3F. In this second modified example, the thermoelectric conversion modules 2C to 2E are electrically connected to each other, but it is not limited thereto.

[0078] Each of the thermoelectric conversion modules 2C to 2E has a substrate 11, a plurality of element parts 14, a sealing layer 15, and a plurality of electrodes 16. The element parts 14 and the electrodes 16 provided on the substrate 11 and covered by the sealing layer 15 are alternately arranged in the arrangement direction D2. Therefore, a part of the plurality of electrodes 16 is in contact with both the n-type thermoelectric conversion layer 14a and the p-type thermoelectric conversion layer 14b. In the thermoelectric conversion element 1B, the n-type thermoelectric conversion layer 14a and the p-type thermoelectric conversion layer 14b are alternately laminated along the thickness direction D1. Therefore, for example, the electrodes 16 that are only in contact with the n-type thermoelectric conversion layer 14a and the electrodes 16 that are only in contact with the p-type thermoelectric conversion layer 14b are alternately laminated along the thickness direction D1. The electrode 16 is a conductor corresponding to the electrode 12 or the electrode 13 in the above-described embodiment.

[0079] The thin plate member 3D is located on one side of the thermoelectric conversion module 2C in the thickness direction D1. The thin plate member 3E is located on the other side of the thermoelectric conversion module 2C in the thickness direction D1 (and on one side of the thermoelectric conversion module 2D) and is located between the thermoelectric conversion modules 2C and 2D. The thin plate member 3F is located on the other side of the thermoelectric conversion module 2D in the thickness direction D1 (and on one side of the thermoelectric conversion module 2E) and is located between the thermoelectric conversion modules 2D and 2E. The thin plate members 3D to 3F include a low heat conduction portion 23 and a high heat conduction portion 24. The high heat conduction portion 24 is a portion that overlaps with the electrode 16 in the thickness direction D1. The high heat conduction portion 24 corresponds to the first high heat conduction portion 21 or the second high heat conduction portion 22 in the above-described embodiment.

[0080] From the viewpoint of improving the heat transfer efficiency from the high heat conduction portion 24 to the electrode 16, in a plan view, the electrode 16 may be located at a position more inward than the edge of the high heat conduction portion 24, and the edge of the electrode 16 and the edge of the high heat conduction portion 24 may completely overlap. From the viewpoint of expanding the temperature gradient along the arrangement direction D2 inside each element portion 14, in a plan view, the high heat conduction portion 24 may be located at a position more inward than the edge of the electrode 16 that is in contact with both the n-type thermoelectric conversion layer 14a and the p-type thermoelectric conversion layer 14b.

[0081] In the second modification described above, the same operational effects as those of the above-described embodiment and the above-described first modification are also obtained.

[0082] Hereinafter, the results obtained by simulating the temperature change inside the element when the position or characteristics of the constituent elements included in the thermoelectric conversion element are changed will be described. In each of the following simulations, a two-dimensional model is set. When performing the following simulations, an EXCEL model obtained by differentially applying the basic differential equation of two-dimensional heat conduction was used. The finite volume method was applied as the differential method.

[0083] Figure 5 It is a schematic cross-sectional view showing the first simulation conditions. As Figure 5 shown, similar to the thin plate member 3 of the above-described embodiment, the model 30 in the first simulation includes high heat conduction portions 31 and 32 and a low heat conduction portion 33. The high heat conduction portion 31 is exposed on one side in the thickness direction D1 and is located at one end of the model 30 in the arrangement direction D2. The high heat conduction portion 32 is exposed on the other side in the thickness direction D1 and is located at the other end of the model 30 in the arrangement direction D2. In the model 30, the dimensions of the high heat conduction portions 31 and 32 along the thickness direction D1 are set to be the same. The low heat conduction portion 33 has a thin plate shape with a thickness of 1 mm and is set to be integrated with the high heat conduction portions 31 and 32. The thermal conductivity of the high heat conduction portions 31 and 32 is set to 398 W / mK, and the thermal conductivity of the low heat conduction portion 33 is set to 0.3 W / mK.

[0084] In the model 30, the interval between the high heat conduction parts 31 and 32 along the arrangement direction D2 is set as interval X (mm), and the interval between the high heat conduction parts 31 and 32 along the thickness direction D1 is set as interval Y (mm) (interval Y is less than 1). When the interval X is 0 mm, the edge 31a on the center side of the high heat conduction part 31 in the arrangement direction D2 overlaps with the edge 32a on the center side of the high heat conduction part 32 in the arrangement direction D2 in the thickness direction D1. When the interval Y is 0 mm, the edge 31b on the center side of the high heat conduction part 31 in the thickness direction D1 overlaps with the edge 32b on the center side of the high heat conduction part 32 in the thickness direction D1 in the arrangement direction D2.

[0085] Two temperature evaluation points 34 and 35 are set in the model 30. The temperature evaluation point 34 is located on the edge 31a on the center side of the high heat conduction part 31 in the thickness direction D1 and at the center of the interval Y. Therefore, when the interval Y is 0 mm, the temperature evaluation point 34 overlaps with the intersection of the edges 31a and 31b. The temperature evaluation point 35 is located on the edge 32a on the center side of the high heat conduction part 32 in the thickness direction D1 and at the center of the interval Y. Therefore, when the interval Y is 0 mm, the temperature evaluation point 35 overlaps with the intersection of the edges 32a and 32b.

[0086] In the thickness direction D1, one side of the model 30 is set as the heat source side, and the other side of the model 30 is set as the air side. In the first simulation, the temperature of the heat source side is set to 70 °C, and the air side is set to room temperature (23 °C). In the first simulation, the surface 30b of the model 30 on the heat source side in the thickness direction D1 is heated by natural convection, and the surface 30a of the model 30 on the air side in the thickness direction D1 is cooled by natural convection.

[0087] Figure 6 (a) and (b) are graphs showing the results of the first simulation. Figure 6 (a) is a graph showing the change in the temperature difference between the temperature evaluation points 34 and 35 when the interval X changes. In Figure 6 (a), the horizontal axis shows the interval X, and the vertical axis shows the temperature difference between the temperature evaluation points 34 and 35. The plot 41 shows the simulation results when the interval Y is 0 mm, the plot 42 shows the simulation results when the interval Y is 0.1 mm, the plot 43 shows the simulation results when the interval Y is 0.2 mm, the plot 44 shows the simulation results when the interval Y is 0.3 mm, the plot 45 shows the simulation results when the interval Y is 0.4 mm, and the plot 46 shows the simulation results when the interval Y is 0.5 mm. As Figure 6As shown in (a), under the condition that the interval X is 1 mm or less, regardless of the value of the interval Y, the larger the interval X becomes, the larger the temperature difference between the temperature evaluation points 34 and 35 becomes. Under the condition that the interval X is more than 1 mm and less than 2 mm, even if the interval X becomes larger, it is difficult for the above temperature difference to become larger. Moreover, under the condition that the interval X is 2 mm or more, regardless of the value of the interval Y, even if the interval X becomes larger, the above temperature difference hardly changes. From this, it is taught that: for example, when the interval between the first high heat conduction part 21 and the second high heat conduction part 22 in the arrangement direction D2 in the thin plate member 3 of the above embodiment is set to 2 mm or more, the interval between the first high heat conduction part 21 and the second high heat conduction part 22 in the thickness direction D1 can be ignored.

[0088] Figure 6 (b) is a graph showing the change in the temperature difference between the temperature evaluation points 34 and 35 when the interval Y changes. In Figure 6 (b), the horizontal axis shows the interval Y, and the vertical axis shows the temperature difference between the temperature evaluation points 34 and 35. The plot 47 shows the simulation result when the interval X is 0 mm, and the plot 48 shows the simulation result when the interval X is 10 mm. As Figure 6 (b) shows, regardless of the value of the interval X, the shorter the interval Y is, the larger the temperature difference between the temperature evaluation points 34 and 35 becomes. From this, the following tendency is taught: for example, in the model 30, the shorter the interval Y between the high heat conduction parts 31 and 32 in the thickness direction D1 is, the larger the above temperature difference becomes.

[0089] Figure 7 is a schematic cross-sectional view showing the second simulation condition. As Figure 7 shown, similar to the above model 30, the model 50 in the second simulation includes high heat conduction parts 51 and 52 and a low heat conduction part 53. The positions where the high heat conduction parts 51 and 52 and the low heat conduction part 53 are provided in the model 50 and their heat conductivities are the same as those of the model 30. In the model 50, the interval between the high heat conduction parts 51 and 52 along the arrangement direction D2 is set to 2 mm. The length of the high heat conduction part 51 along the thickness direction D1 is set to Z mm, and the length of the high heat conduction part 52 along the thickness direction D1 is set to 1 - Z mm. The temperature condition around the model 50 is set to be the same as that in the first simulation.

[0090] Two temperature evaluation points 54 and 55 are set in the model 50. The temperature evaluation point 54 is located at the intersection of the center-side edge 51a of the high heat conduction part 51 along the arrangement direction D2 and the center-side edge 51b of the high heat conduction part 51 along the thickness direction D1. The temperature evaluation point 55 is located at the intersection of the center-side edge 52a of the high heat conduction part 52 along the arrangement direction D2 and the center-side edge 52b of the high heat conduction part 52 along the thickness direction D1.

[0091] Figure 8 is a graph showing the second simulation result, showing the change in the temperature difference between the temperature evaluation points 54 and 55 when the length of the high thermal conductivity portion 51 along the thickness direction D1 is changed. In Figure 8 it, the horizontal axis shows the length Z, and the vertical axis shows the temperature difference between the temperature evaluation points 54 and 55. As Figure 8 shown, the greater the length of the high thermal conductivity portion 51 on the heat source side in the thickness direction D1 along the thickness direction D1, the greater the above-mentioned temperature difference becomes. From this result, it is taught that: when expanding the temperature difference between the temperature evaluation points 54 and 55 in the arrangement direction D2 in the model 50, it is effective to increase the thickness of the high thermal conductivity portion located on the heat source side as much as possible.

[0092] Figure 9 is a schematic cross-sectional view showing the third simulation condition. The model used in the third simulation is configured as follows: Based on the first and second simulation results, it is presumed that the temperature difference is most generated in the arrangement direction D2. Specifically, as Figure 9 shown, the model 60 in the third simulation includes a high thermal conductivity portion 61 and a low thermal conductivity portion 62. The high thermal conductivity portion 61 and the low thermal conductivity portion 62 are arranged in order along the arrangement direction D2 and are integrated with each other. The dimensions of the high thermal conductivity portion 61 and the low thermal conductivity portion 62 along the thickness direction D1 are 1 mm. The thermal conductivity of the high thermal conductivity portion 61 is set to 398 W / mK.

[0093] In the thickness direction D1, one side of the model 60 is set as the heat source side, and the other side of the model 60 is set as the air side. In the third simulation, different from the first simulation, the temperature of the heat source side is set to 100 °C. On the other hand, the conditions on the air side are the same as those in the first simulation.

[0094] A temperature evaluation point 63 is set on the surface 60a of the model 60 in the model 60. The temperature evaluation point 63 is located on the low thermal conductivity portion 62 that is 2 mm away from the contact portion 64 along the arrangement direction D2. The contact portion 64 is the contact portion between the high thermal conductivity portion 61 and the low thermal conductivity portion 62. Therefore, the temperature of the temperature evaluation point 63 shows the temperature of the surface 60a when the model 60 is heated (more specifically, the temperature of the surface 60a composed of the low thermal conductivity portion 62).

[0095] Figure 10 is a graph showing the third simulation result, showing the temperature change of the temperature evaluation point 63 when the thermal conductivity of the low thermal conductivity portion 62 is changed. In Figure 10 it, the horizontal axis shows the thermal conductivity of the low thermal conductivity portion 62, and the vertical axis shows the temperature of the temperature evaluation point 63. As Figure 10As shown, the smaller the thermal conductivity of the low thermal conductivity portion 62, the lower the temperature of the temperature evaluation point 63 becomes. When the thermal conductivity of the low thermal conductivity portion 62 is 0.2 W / mK, the temperature difference between the heat source and the temperature evaluation point 63 becomes approximately 8°C. When the thermal conductivity of the low thermal conductivity portion 62 is 0.08 W / mK, the temperature difference between the heat source and the temperature evaluation point 63 becomes approximately 15°C. On the other hand, when the thermal conductivity of the low thermal conductivity portion 62 is 30 W / mK or more, the temperature difference between the heat source and the temperature evaluation point 63 becomes substantially 0. From this, it is taught that: for example, when the thermal conductivity of the low thermal conductivity portion 23 included in the thin plate member 3 is 0.2 W / mK or less, the low thermal conductivity portion 23 tends to exhibit good heat insulation properties, and when the thermal conductivity of the low thermal conductivity portion 23 is 0.08 W / mK or less, the low thermal conductivity portion 23 tends to exhibit better heat insulation properties.

[0096] Next, the simulation results of the maximum temperature difference within the element portion when the structure of the thermoelectric conversion element is changed will be described. Figure 11 (a) of is a schematic cross-sectional view of the thermoelectric conversion element of the first reference example, Figure 11 and (b) of is a schematic cross-sectional view of the thermoelectric conversion element of the second reference example.

[0097] Figure 11 The thermoelectric conversion element 101 shown in (a) of includes a thermoelectric conversion module 2A and thin plate members 3A-1 and 103-1. The thin plate member 3A-1 is a member having the same shape as the thin plate member 3, and includes a first high thermal conductivity portion 21-1, a second high thermal conductivity portion 22-1, and a low thermal conductivity portion 23-1. The thicknesses (lengths along the thickness direction D1) of the thin plate members 3A and 3A-1 may be different from each other. The thin plate member 103-1 includes a high thermal conductivity portion 110-1 and a low thermal conductivity portion 120-1 provided on the sealing layer 15 of the thermoelectric conversion module 2A. The high thermal conductivity portion 110-1 is a portion provided to improve the heat dissipation of the n-type thermoelectric conversion layer 14a and the p-type thermoelectric conversion layer 14b, and overlaps with the contact portion CP in the thickness direction D1. The center of the high thermal conductivity portion 110-1 in the arrangement direction D2 overlaps with the contact portion CP in the thickness direction D1. The low thermal conductivity portion 120-1 is a thin plate member provided to reduce the heat dissipation around the electrodes 12 and 13 and their surroundings. The low thermal conductivity portion 120-1 surrounds the high thermal conductivity portion 110-1 in a direction orthogonal to the thickness direction D1, and overlaps with the electrodes 12 and 13, the first high thermal conductivity portion 21-1, and the second high thermal conductivity portion 22-1 in the thickness direction D1. The lengths of the high thermal conductivity portion 110-1 and the low thermal conductivity portion 120-1 along the thickness direction D1 are set to be the same.

[0098] Figure 11The thermoelectric conversion element 201 shown in (b) includes thermoelectric conversion modules 2A and 202, and thin plate members 3A-2, 3B-2, and 103-2. In the thermoelectric conversion element 201, the thin plate member 3A-2, the thermoelectric conversion module 2A, the thin plate member 103-2, the thermoelectric conversion module 202, and the thin plate member 3B-2 are laminated in this order. The thin plate members 3A-2 and 3B-2 are members having the same shape as the thin plate members 3A and 3A-1, and include a first high heat conduction portion 21-2, a second high heat conduction portion 22-2, and a low heat conduction portion 23-2. That is, the thin plate members 3A-2 and 3B-2 have the same shape or substantially the same shape as each other. The thicknesses (lengths along the thickness direction D1) of the thin plate members 3A-2 and 3B-2 and the thicknesses (lengths along the thickness direction D1) of the thin plate members 3A and 3A-1 may be different from each other. The thin plate member 103-2 is a member having the same shape as the thin plate member 103-1, and includes a high heat conduction portion 110-2 and a low heat conduction portion 120-2. The thicknesses (lengths along the thickness direction D1) of the thin plate members 103-1 and 103-2 may be different from each other.

[0099] The thermoelectric conversion module 202 includes a substrate 11, an electrode 212, an n-type thermoelectric conversion layer 14a, a p-type thermoelectric conversion layer 14b, and a sealing layer 15. The electrode 212 overlaps with the contact portion CP of the thermoelectric conversion module 2A and the high heat conduction portion 110-2 of the thin plate member 103-2 in the thickness direction D1. Therefore, when the thermoelectric conversion element 201 is heated from the thin plate member 3A-2 side in the thickness direction D1, the electrode 212 is mainly heated by the heat transferred through the element portion 14 of the thermoelectric conversion module 2A and the high heat conduction portion 110-2. In the arrangement direction D2, an n-type thermoelectric conversion layer 14a is provided on one end side of the electrode 212, and a p-type thermoelectric conversion layer 14b is provided on the other end side of the electrode 212. In the thermoelectric conversion module 202, the n-type thermoelectric conversion layer 14a and the p-type thermoelectric conversion layer 14b are separated from each other.

[0100] In this simulation, in the thermoelectric conversion elements 1, 101, and 201, the length of the substrate 11 along the thickness direction D1 is set to 50 μm, the length of the thin plate members 3A and 3B along the thickness direction D1 is set to 300 μm, the length of the thin plate members 3A-1 and 103-1 along the thickness direction D1 is set to 400 μm, and the length of the thin plate members 3A-2, 3B-2, and 103-2 along the thickness direction D1 is set to 200 μm. The lengths of the electrodes 12, 13, and 212 along the thickness direction D1 are set to 25 μm, the lengths of the n-type thermoelectric conversion layer 14a and the p-type thermoelectric conversion layer 14b along the thickness direction D1 are set to 100 μm, the maximum length of the sealing layer 15 along the thickness direction D1 is set to 150 μm, the lengths of the first high heat conduction portion 21, the second high heat conduction portion 22, and the low heat conduction portion 23 along the thickness direction D1 are set to 300 μm, the lengths of the first high heat conduction portion 21-1, the second high heat conduction portion 22-1, and the low heat conduction portion 23-1 along the thickness direction D1 are set to 400 μm, and the lengths of the first high heat conduction portion 21-2, the second high heat conduction portion 22-2, and the low heat conduction portion 23-2 along the thickness direction D1 are set to 200 μm. Also, the lengths of the high heat conduction portion 110-1 and the low heat conduction portion 120-1 along the thickness direction D1 are set to 400 μm, and the lengths of the high heat conduction portion 110-2 and the low heat conduction portion 120-2 along the thickness direction D1 are set to 300 μm.

[0101] Moreover, the lengths of the thermoelectric conversion modules 2A, 2B, and 202, and the thin plate members 3A, 3A-1, 3A-2, 3B, 3B-2, 103-1, and 103-2 along the arrangement direction D2 are set to 15 mm, the lengths of the electrodes 12, 13, and 212 along the arrangement direction D2 are set to 3 mm, the lengths of the n-type thermoelectric conversion layer 14a and the p-type thermoelectric conversion layer 14b along the arrangement direction D2 are set to 2.5 mm, and the lengths of the first high heat conduction portions 21, 21-1, and 21-2 and the second high heat conduction portions 22, 22-1, and 22-2 along the arrangement direction D2 are set to 3 mm. Also, the lengths of the high heat conduction portions 110-1 and 110-2 along the arrangement direction D2 are set to 3 mm.

[0102] In this simulation, in the thermoelectric conversion elements 1, 101, and 201, the thermal conductivity of the substrate 11 and the sealing layer 15 is set to 0.3 W / mK, the thermal conductivity of the electrodes 12, 13, and 212 is set to 398 W / mK, the thermal conductivity of the n-type thermoelectric conversion layer 14a and the p-type thermoelectric conversion layer 14b is set to 0.5 W / mK, the thermal conductivity of the first high thermal conductivity portions 21, 21-1, 21-2 and the second high thermal conductivity portions 22, 22-1, 22-2 is set to 5 W / mK, and the thermal conductivity of the low thermal conductivity portions 23, 23-1, 23-2 is set to 0.05 W / mK. The thermal conductivity of the high thermal conductivity portions 110-1 and 110-2 is set to 5 W / mK, and the thermal conductivity of the low thermal conductivity portions 120-1 and 120-2 is set to 0.05 W / mK.

[0103] In the thermoelectric conversion elements 1, 101, and 201, in the same manner as in the above-described third simulation, the temperature on the heat source side is set to 100°C, and the air side is set to room temperature (23°C). The temperature of the exposed surfaces of the thin plate members 3A, 3A-1, and 3A-2 that intersect the thickness direction D1 is also set to 100°C.

[0104] In the thermoelectric conversion elements 1, 101, and 201 set to the above conditions, the maximum temperature difference of the element portion 14 was simulated. In the thermoelectric conversion element 201, the maximum temperature difference of one of the n-type thermoelectric conversion layer 14a and the p-type thermoelectric conversion layer 14b was simulated. As a result, in the thermoelectric conversion element 1, the maximum temperature difference of the element portion 14 of the thermoelectric conversion module 2A was 3.193°C, and the maximum temperature difference of the element portion 14 of the thermoelectric conversion module 2B was 6.628°C. The maximum temperature difference of the element portion 14 of the thermoelectric conversion element 101 was 4.909°C. In the thermoelectric conversion element 201, the maximum temperature difference of the element portion 14 of the thermoelectric conversion module 2A was 2.793°C, and the maximum temperature difference of the thermoelectric conversion module 202 was 1.168°C. Therefore, the total temperature difference of the thermoelectric conversion element 1 was 9.821°C, and the total temperature difference of the thermoelectric conversion element 201 was 3.961°C.

[0105] Based on the above results, it is taught that: compared with the structure of the thermoelectric conversion element 1, the structure including the thermoelectric conversion element 101 and in which a plurality of thermoelectric conversion modules are stacked in the thickness direction (for example, the thermoelectric conversion element 201) tends to have a lower thermoelectric conversion efficiency. In other words, it is taught that: compared with the structure of the thermoelectric conversion element 1, the power generation ability per unit area of the structure including the thermoelectric conversion element 101 and in which a plurality of thermoelectric conversion modules are stacked in the thickness direction (for example, the thermoelectric conversion element 201) tends to be lower.

[0106] The thermoelectric conversion element of the disclosure of the present application is not limited to the above-described embodiments and the above-described modified examples, and various modifications can be made other than these. For example, by appropriately combining the above-described embodiment and the above-described second modified example, a plurality of element portions along the arrangement direction can be provided on the substrate. The above-described first modified example and the above-described second modified example can be appropriately combined.

[0107] In the above-described embodiment and the above-described second modified example, the outermost layer is composed only of the sealing layer, but it is not limited thereto. For example, the outermost layer can be composed of the sealing layer and a member different from the sealing layer. Alternatively, the outermost layer can be composed of other thin plate members formed of low heat conduction portions.

[0108] In the above-described embodiment and the above-described modified examples, the electrodes are formed simultaneously, but it is not limited thereto.

[0109] Description of Reference Numerals

[0110] 1, 1A, 1B, 101, 201... thermoelectric conversion element; 2A to 2E, 202... thermoelectric conversion module; 3A to 3F, 3A-1, 3A-2, 3B-2, 103-1, 103-2... thin plate member; 11... substrate; 11a, 11b... main surface; 12, 13, 16, 212... electrode; 14... element portion; 14a... n-type thermoelectric conversion layer; 14b... p-type thermoelectric conversion layer; 15... sealing layer; 21, 21-1, 21-2... first high heat conduction portion; 22, 22-1, 22-2... second high heat conduction portion; 23, 23-1, 23-2... low heat conduction portion; 24... high heat conduction portion; 110-1, 110-2... high heat conduction portion; 120-1, 120-2... low heat conduction portion; CP... contact portion; S1, S2... interval; T1... length of the first high heat conduction portion; T2... length of the second high heat conduction portion.

Claims

1. A thermoelectric conversion element comprising a first thermoelectric conversion module and a pair of thin plate members sandwiching the first thermoelectric conversion module. In the thermoelectric conversion element, the first thermoelectric conversion module includes: a first substrate having a first main surface and a second main surface on the opposite side of the first main surface; a first electrode provided on the first main surface, a first n-type thermoelectric conversion layer electrically connected to the first electrode, a first p-type thermoelectric conversion layer in contact with the first n-type thermoelectric conversion layer, and a second electrode electrically connected to the first p-type thermoelectric conversion layer; and a sealing layer provided on the first main surface and covering the first electrode, the first n-type thermoelectric conversion layer, the first p-type thermoelectric conversion layer, and the second electrode, each of the pair of thin plate members includes a first high heat conduction portion, a second high heat conduction portion, and a low heat conduction portion, the first electrode, the first n-type thermoelectric conversion layer, the first p-type thermoelectric conversion layer, and the second electrode are sequentially arranged along an arrangement direction orthogonal to the thickness direction of the first substrate, the first electrode overlaps with the first high heat conduction portion of each of the pair of thin plate members in the thickness direction, the second electrode overlaps with the second high heat conduction portion of each of the pair of thin plate members in the thickness direction, a first contact portion between the first n-type thermoelectric conversion layer and the first p-type thermoelectric conversion layer overlaps with the low heat conduction portion of each of the pair of thin plate members in the thickness direction.

2. The thermoelectric conversion element according to claim 1, further comprising a second thermoelectric conversion module located on a side opposite to the first thermoelectric conversion module across one of the pair of thin plate members sandwiching the pair of thin plate members in the thickness direction, the second thermoelectric conversion module includes: a second substrate having a third main surface on the first thermoelectric conversion module side in the thickness direction and a fourth main surface on the opposite side of the third main surface; a third electrode provided on the fourth main surface, a second n-type thermoelectric conversion layer electrically connected to the third electrode, a second p-type thermoelectric conversion layer in contact with the second n-type thermoelectric conversion layer, and a fourth electrode electrically connected to the second p-type thermoelectric conversion layer; and a second sealing layer provided on the fourth main surface and covering the third electrode, the second n-type thermoelectric conversion layer, the second p-type thermoelectric conversion layer, and the fourth electrode.

3. The thermoelectric conversion element according to claim 2, wherein the third electrode overlaps with the first high heat conduction portion of each of the pair of thin plate members and the first electrode in the thickness direction, the fourth electrode overlaps with the second high heat conduction portion of each of the pair of thin plate members and the second electrode in the thickness direction, a second contact portion between the second n-type thermoelectric conversion layer and the second p-type thermoelectric conversion layer overlaps with the low heat conduction portion of each of the pair of thin plate members in the thickness direction.

4. The thermoelectric conversion element according to claim 2, wherein The third electrode overlaps with the second high heat conduction portions and the second electrodes of the pair of thin plate members in the thickness direction. The fourth electrode overlaps with the first high heat conduction portions and the first electrodes of the pair of thin plate members in the thickness direction. The second contact portion between the second n-type thermoelectric conversion layer and the second p-type thermoelectric conversion layer overlaps with the low heat conduction portions of the pair of thin plate members in the thickness direction.

5. The thermoelectric conversion element according to any one of claims 2 to 4, wherein The second thermoelectric conversion module is electrically connected to the first thermoelectric conversion module.

6. The thermoelectric conversion element according to any one of claims 2 to 4, wherein The second sealing layer constitutes the outermost surface located on the fourth main surface.

7. The thermoelectric conversion element according to any one of claims 2 to 4, further comprising a thin plate member provided separately from the pair of thin plate members, The separately provided thin plate member is located on the side opposite to the first thermoelectric conversion module with the second thermoelectric conversion module interposed therebetween in the thickness direction.

8. The thermoelectric conversion element according to any one of claims 1 to 4, wherein The heat conductivity of the low heat conduction portion is 0.2 W / mK or less.

9. The thermoelectric conversion element according to claim 8, wherein The heat conductivity of the low heat conduction portion is 0.08 W / mK or less.

10. The thermoelectric conversion element according to any one of claims 1 to 4, wherein The heat conductivities of the first high heat conduction portion and the second high heat conduction portion are 5 W / mK or more.

11. The thermoelectric conversion element according to any one of claims 1 to 4, wherein The heat conductivities of the first electrode and the second electrode are 5 W / mK or more.

12. The thermoelectric conversion element according to any one of claims 1 to 4, wherein The substrate exhibits flexibility.

13. The thermoelectric conversion element according to any one of claims 1 to 4, wherein The interval from the first high heat conduction portion to the first contact portion along the arrangement direction is 5 times or more the length of the first high heat conduction portion along the thickness direction, The interval from the second high heat conduction portion to the first contact portion along the arrangement direction is 5 times or more the length of the second high heat conduction portion along the thickness direction.

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