JP2006196727A - Thermoelectric conversion device and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly practical thermoelectric conversion device having an improved thermoelectric conversion efficiency. <P>SOLUTION: This thermoelectric conversion device 20 comprises a wire array, wherein linear bodies 22 of a thermoelectric conversion material having a thickness corresponding to a diameter of 0.1 μm-1 μm are integrated, and an insulator 21 which has a thermal conductivity lower than that of the thermoelectric conversion material and surrounds each of the linear bodies 22. The ZT value of the thermoelectric conversion device 20 become larger, because the thermal conductivity of the linear bodies 22 of the thermoelectric conversion material is reduced under the influence of the surrounding insulator 21. The figure of merit of the thermoelectric conversion device 20 formed of a conventional thermoelectric conversion material is greatly improved by the order of several tens percent or more by only changing the manufacturing method and the structure of the thermoelectric conversion device 20. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a thermoelectric conversion element having a thermoelectric conversion function and a method for manufacturing the thermoelectric conversion element, and in particular, to improve the conversion efficiency of the thermoelectric conversion element.

  The thermoelectric conversion element has a power generation function based on the Seebeck effect and a thermoelectric cooling function based on the opposite Peltier effect. The thermoelectric conversion device configured using this thermoelectric conversion element increases the thermoelectric conversion efficiency by combining a plurality of thermoelectric conversion elements. For example, FIG. 16A (partially broken perspective view) and FIG. b) As shown in (sectional view), thermoelectric conversion elements made of P-type semiconductor 11 and thermoelectric conversion elements made of N-type semiconductor 12 are alternately arranged in the vertical and horizontal directions, and all of these elements are electrically connected. Adjacent elements in each column are connected alternately with the lower metal electrode 13 and the upper metal electrode 14 so as to be connected in series, and further, one of the elements at both ends of each column is adjacent to the element on the right side, The other is connected to the element in the column adjacent to the left side by the lower metal electrode 13 or the upper metal electrode 14 respectively.

In the junction between the N-type semiconductor 12 and the metal electrode, when current flows from the N-type semiconductor 12 to the metal electrode, it is cooled by the Peltier effect, and conversely, when current flows from the metal electrode to the N-type semiconductor 12, Heated with the same effect. On the other hand, at the junction between the P-type semiconductor 11 and the metal electrode, on the contrary, when the current flows from the P-type semiconductor 11 to the metal electrode, it is warmed, and when the current flows from the metal electrode to the P-type semiconductor 11. Chilled.
Therefore, when a direct current is passed through each element of the thermoelectric conversion device 10 through the lead wire 17, the temperature decreases on the side of the upper metal electrode 14 where the current flows in the order of the N-type semiconductor 12, the upper metal electrode 14, and the P-type semiconductor 11. The endothermic substrate 16 bonded to the upper metal electrode 14 takes heat from the surroundings. On the other hand, on the side of the lower metal electrode 13 through which current flows in the order of the P-type semiconductor 11, the lower metal electrode 13, and the N-type semiconductor 12, the temperature rises, and the heat dissipation substrate 15 joined to the lower metal electrode 13 To release heat.

Each of the thermoelectric conversion elements 11 and 12 has a cross-sectional area of 2 mm square and a height of about 1 to 2.5 mm. The heat dissipation substrate 15 and the heat absorption substrate 16 of the thermoelectric conversion device 10 combined with the thermoelectric conversion elements. Has a surface area of about 2 cm × 2 cm.
Currently, thermoelectric conversion devices are used in wine cellars, small refrigerators, and the like, and miniaturized ones are used for temperature control of semiconductor lasers for optical communication.
As materials having thermoelectric conversion performance, bismuth (Bi) -based and bismuth tellurium (BiTe) -based semiconductors are known. Among them, BiTe-based materials have relatively high thermoelectric conversion efficiency at room temperature, and are commercially available. Used in many thermoelectric conversion devices.

Moreover, it is said from the theoretical calculation that when the thermoelectric conversion material is made into a nanowire (quantum wire), the thermoelectric conversion index is increased as compared with the thermoelectric conversion material in the bulk state. Based on the above, a large number of holes having a diameter of 0.5 nm to 15 nm are formed in a thin film of silicon or germanium (or oxides thereof) having a thickness of 1 nm to 100 μm, and a thermoelectric conversion material is introduced into the holes to form nanowires. Manufacturing a thermoelectric conversion element is described.
JP 2004-193526 A

However, although the thermoelectric conversion device has excellent aspects such as no vibration and operation noise, and cooling and heating so that temperature control is easy, the thermoelectric conversion efficiency is such as solar cells. There is a significant need for improvement.
The conversion efficiency of the thermoelectric conversion element is represented by a figure of merit Z shown in the following formula (1).
Z = α ² / ρk (unit: 1 / absolute temperature (K)) (1)
Here, α: Seebeck coefficient, ρ: electrical resistivity, k: thermal conductivity. In actual use, the performance is expressed by multiplying both sides of the equation (1) by the absolute temperature T and using ZT (Dimensionless Performance Index) shown in the following equation (2).
ZT = (α ² / ρk) T (2)
This ZT≈1 is regarded as a standard for practical use, and the ZT of the BiTe thermoelectric conversion element has reached approximately 1. If ZT can be increased to about 1.5, it will be possible to commercialize a vending machine using a thermoelectric conversion element, and if ZT is further increased, commercial refrigerators and household refrigerators are expected to be commercialized.

However, since the 1960s when BiTe-based materials were developed, various developments have been continued with a great deal of effort and funding. Almost no performance has been obtained, and the figure of merit Z has improved by no more than about 50%.
In addition, in the case of the thermoelectric conversion element converted into a nanowire described in Patent Document 1, since only a thin film can be formed, it is difficult to maintain a temperature difference between one surface of the thin film and the other surface, Poor utility.

  The present invention has been made to solve such conventional problems, and has an object to provide a thermoelectric conversion element with improved thermoelectric conversion efficiency and high practicality, and to provide a manufacturing method thereof.

In the present invention, a wire array in which linear bodies of thermoelectric conversion material having a diameter corresponding to a diameter of 0.1 μm to 1 mm are integrated, and a thermoelectric conversion material surrounding each of the linear bodies A thermoelectric conversion element is composed of an insulator having a lower thermal conductivity.
In this thermoelectric conversion element, the thermal conductivity of the linear body of the thermoelectric conversion material decreases due to the influence of the surrounding insulator, and therefore the ZT value of the thermoelectric conversion element increases.

In the thermoelectric conversion element of the present invention, the insulator is a porous structure in which a plurality of through holes are formed, and a thermoelectric conversion material is filled in the through holes of the insulator.
Therefore, the thermoelectric conversion material is linearized by filling the through holes of the insulator.

In the thermoelectric conversion element of the present invention, the porosity of the porous structure is set to 10 to 90%.
By limiting the porosity of the porous structure, it is possible to reduce the thermal conductivity while avoiding a decrease in the output density of the thermoelectric conversion element.

Further, in the present invention, in the production of the thermoelectric conversion element, the thermoelectric conversion material is melted and formed of an insulator having a lower thermal conductivity than the thermoelectric conversion material, and has a size corresponding to a diameter of 0.1 μm to 1 mm. A porous structure having a plurality of through holes is immersed, and the through holes of the porous structure are filled with a thermoelectric conversion material.
When the diameter of the through hole of the porous structure is small, pressure is applied to the molten thermoelectric conversion material, and the thermoelectric conversion material is pressed into the through hole.

In the present invention, in the production of the thermoelectric conversion element, the powder of the thermoelectric conversion material is formed of an insulator having a thermal conductivity lower than that of the thermoelectric conversion material and has a plurality of sizes corresponding to a diameter of 0.1 μm to 1 mm. It introduce | transduces into the said through-hole of the porous structure which has a through-hole, and heat and pressure are added, and the thermoelectric conversion material is integrated with the porous structure.
Conventionally, the hot press method used for manufacturing the bulk thermoelectric conversion element can be applied to the manufacture of the thermoelectric conversion element of the present invention.

Further, in the present invention, in the production of the thermoelectric conversion element, a linear body of a thermoelectric conversion material having a diameter corresponding to a diameter of 0.1 μm to 1 mm is formed, and a plurality of the linear bodies and the thermoelectric conversion material are heated. It is combined with a polymer material with low conductivity.
According to this method, the thermoelectric conversion element can be manufactured without exposing the polymer material to a high temperature.

According to the present invention, the performance index of a thermoelectric conversion element composed of a conventional thermoelectric conversion material is greatly improved to the order of several tens of percent or more simply by changing the manufacturing method and structure of the thermoelectric conversion element. Can be made.
Therefore, by increasing the conversion efficiency, it is possible to reduce the size of the element, reduce power consumption, reduce the temperature to reach cooling, etc., and use a thermoelectric conversion element as a thermoelectric cooling element or power generation element. The range can be expanded.

(First embodiment)
FIG. 1 shows the overall structure of a thermoelectric conversion element 20 in the first embodiment of the present invention. This thermoelectric conversion element 20 is composed of a glass capillary plate 21 in which a large number of through holes are formed at equal intervals, and Bi22 of a thermoelectric conversion material filled in each hole. The periphery of Bi formed into a wire shape by filling the through hole is surrounded by glass having a low thermal conductivity, which is a material of the glass capillary plate 21.

As shown in FIG. 2, the glass capillary plate 21 is made of lead glass with low thermal conductivity and high workability, and a large number of through holes 23 having a diameter of micron order are formed at equal intervals. Hamamatsu Photonics And are available commercially from US company Barr. Here, a glass capillary plate 21 having a diameter of the through hole 23 of 25 μm and an open area ratio (area ratio occupied by the hole) of 55% is used.
For example, Bi is melted and filled in the through holes 23 of the glass caprary plate 21. Details of this manufacturing method will be described later.

  The outer shape of the thermoelectric conversion element 20 is formed by shaping the depth (d) and width (w) of the surface where the end face of the Bi wire is exposed (that is, the electrode bonding surface) to 2 mm and the height (h) to 2 mm. In this thermoelectric conversion element 20, thousands of Bi wires 22 having a diameter of 25 μm and a length of 2 mm are integrated. FIG. 3 shows an enlarged array of Bi wires 22 appearing on the electrode bonding surface. The area ratio between Bi and the glass part at the electrode bonding surface is 55:45.

  When the thermal conductivity k of the Bi wire having a diameter of 25 μm included in the thermoelectric conversion element 20 is measured, it shows a value of 4.7 (W / mK) at room temperature (300 K). The thermal conductivity k of the glass capillary plate 21 is 0.6 (W / mK). On the other hand, the thermal conductivity k of bulk Bi at room temperature is 8.8 (W / mK).

Thus, by surrounding the Bi wire (microwire) thinned so that the diameter becomes micro order with a material having a low thermal conductivity k, the effective thermal conductivity k of the Bi microwire is Lower than in the bulk state. Such a phenomenon is observed in a wire having a diameter of 1 mm or less.
As shown in FIG. 4, this is considered because the heat flow of the Bi microwire 22 is dragged by the heat flow of the glass capillary plate 21 having a low thermal conductivity, as indicated by an arrow.
FIG. 5 shows the results of measuring the temperature dependence of the thermal conductivity k in bulk Bi and Bi microwire with a diameter of 25 μm. As is clear from this figure, the lower the temperature, the greater the effect of reducing the thermal conductivity in the Bi microwire.

FIG. 6 shows a change in the thermal conductivity k when the diameter of the Bi microwire is changed. The Bi microwire having a diameter of 10 μm is formed using the glass caprary plate 21 having a through hole diameter of 10 μm and a hole area ratio of 55%, as in the case of the diameter of 25 μm. In the obtained thermoelectric conversion element of 2 mm × 2 mm × 2 mm, tens of thousands of Bi microwires having a diameter of 10 μm and a length of 2 mm are integrated. In addition, the Bi microwire having a diameter of 1 μm is made by using the glass capillary plate 21 having a through hole diameter of 1 μm and an aperture ratio of 55%. Millions of Bi microwires having a diameter of 1 μm and a length of 2 mm are integrated in the obtained thermoelectric conversion element having an external shape of 2 mm × 2 mm × 2 mm.
As apparent from FIG. 6, the effective thermal conductivity k decreases as the diameter of the Bi microwire decreases. This is because the smaller the diameter of the Bi microwire, the stronger the influence of the surrounding heat flow.

On the other hand, the electrical resistivity ρ of Bi microwire is 1.3 μΩm at room temperature, which is no different from bulk Bi. Further, the Seebeck coefficient α of Bi microwire is also −60 μV / K, which is the same as that of bulk Bi.
Therefore, when Bi is made into a microwire, in Expression (2), α and ρ are the same and k is reduced, so that the value of ZT is improved.

FIG. 7 shows a comparison between the ZT value of a thermoelectric conversion element in which Bi wire arrays of various diameters are formed on a glass capillary plate and the ZT value of a thermoelectric conversion element made of bulk Bi. However, T = 300K.
A thermoelectric conversion element composed of a Bi wire array has a ZT value that is doubled when the wire diameter is 25 μm, and 2.3 times when a wire diameter is 10 μm, compared to a thermoelectric conversion element composed of bulk Bi. In addition, when the wire diameter is 1 μm, it is increased 3.7 times.

  However, since Bi used here is a basic base material of a thermoelectric conversion element and is not a material with a high figure of merit, the ZT value itself of a thermoelectric conversion element composed of a Bi wire array is not so good. However, the result of this Bi is that the thermoelectric conversion material is made into a microwire and the periphery thereof is surrounded by an insulating material having a low thermal conductivity, so that the effective thermal conductivity of the thermoelectric conversion material can be lowered. It shows that the ZT value of the thermoelectric conversion element can be improved if the thermoelectric conversion element is constituted by a wire array of conversion materials.

Next, a description will be given of the case where the micro-wire conversion of the thermoelectric conversion material is applied to a BiTe-based material that boasts the highest thermoelectric conversion performance near room temperature.
FIG. 8 shows parameters of a bulk BiTe-based polycrystal produced by a normal hot press. The p-type has a composition of (Bi, Sb) ₂ Te ₃ and the n-type has a composition of Bi ₂ (Te, Sb) ₃ .
FIG. 9 shows the thermal conductivity k of the microwire when this BiTe-based material is wire-arrayed using a glass capillary plate having a porosity of 55%, as in the case of Bi.

  Based on this value, the figure of merit Z of a thermoelectric conversion element composed of a wire array of BiTe-based material and ZT at T = 300K are calculated as shown in FIG. That is, when the wire diameter is set to 25 μm, the ZT value can be 1.26 that is 1.5 times that of the bulk state, and when the wire diameter is set to 10 μm, it is 1.7 times that of the bulk state. .42 can be realized, and when the wire diameter is set to 1 μm, 1.62 which is 1.9 times the bulk state can be realized.

Further, the thermal conductivity k of the microwire of the thermoelectric conversion material is also related to the aperture ratio of the glass caprary plate. FIG. 11 (a) shows the thermal conductivity k of Bi microwires when Bi is wire-arrayed using glass caprary plates with a hole opening rate of 25% in diameter of 70%, 55% and 30%. FIG. 11 (b) shows the thermal conductivity k of BiTe microwires when BiTe-based materials are wire-arrayed using the same glass capillary plate.
As is clear from FIG. 11, the effective thermal conductivity k of the microwire decreases as the aperture ratio of the glass caprary plate decreases.

  However, if the hole area ratio of the glass capillary plate is reduced, the material portion related to electrical conduction is reduced, and the output density as a thermoelectric conversion element is reduced. Therefore, the hole area ratio is desirably 10% or more, and desirably 90% or less from the viewpoint of realizing effective reduction of the thermal conductivity k. In practice, it is preferable to set the open efficiency around 50% in consideration of both.

  Here, lead glass with a thermal conductivity of 0.6 (W / mK) is used as the insulating material surrounding the microwire of the thermoelectric conversion material, but other insulating materials with low thermal conductivity are used. You can also For example, as shown in FIG. 12, since the thermal conductivity of the polymer material is lower than that of lead glass, the effective thermal conductivity can be obtained by surrounding the microwire of the thermoelectric conversion material using these polymer materials. Can be further reduced.

As the thermoelectric conversion material, not only Bi and BiTe-based materials but also various materials such as a thermoelectric conversion material that functions effectively at a temperature of about 400 ° C. and BiSb that functions effectively at low temperatures can be used.
Although the thermoelectric conversion element having a length, width, and height of 2 mm × 2 mm × 2 mm has been described here, the outer shape of the thermoelectric conversion element can be set to an arbitrary shape depending on the shaping.

Thus, this thermoelectric conversion element is composed of a wire array in which wires of thermoelectric conversion materials having a diameter of the order of microns are integrated, and an insulator having low thermal conductivity surrounding each wire, The ZT value of the thermoelectric conversion element is improved due to the decrease in effective thermal conductivity of each wire.
The decrease in thermal conductivity decreases the heat output per unit volume. However, in this thermoelectric conversion element, a large temperature difference is caused at both ends of the thermoelectric conversion element due to the decrease in thermal conductivity. Will increase.
Moreover, since the circumference | surroundings of each wire of the thermoelectric conversion material are surrounded by the insulator, they are not cut off in the middle even though they are thinned.

(Second Embodiment)
In the second embodiment of the present invention, a method for manufacturing the thermoelectric conversion element of the first embodiment will be described.

(Method using high pressure)
First, a glass capillary plate 21 shown in FIG. 2 is prepared in advance, which is formed of glass with low thermal conductivity and has micron-order holes. Next, as shown in FIG. 13, the thermoelectric conversion material 31 is melted in the reaction furnace 32, and the glass capillary plate 21 is submerged therein. Next, pressure is applied to the dissolved thermoelectric conversion material 31 via gas or liquid, and the dissolved thermoelectric conversion material 31 is pressed into the holes 23 of the glass capillary plate 21. When the diameter of the hole 23 of the glass capillary plate 21 is 100 μm, the thermoelectric conversion material 31 can be pressed into the hole 23 at a pressure of 1 atm or less, but the necessary pressure increases as the diameter of the hole 23 decreases. In the case of a diameter of 1 μm, a pressure of about 250 atm is required to press-fit the thermoelectric conversion material 31 into all the holes 23.

FIG. 14A shows a state in which the ingot of the thermoelectric conversion material including the glass capillary plate that has been subjected to the press-fitting process is cooled to room temperature and taken out from the reactor. FIG. 14B shows the ingot. The cross section of the glass capillary plate which the micro wire of the thermoelectric conversion material which cut out from FIG.
A necessary portion is cut out from this ingot and polished, and excess thermoelectric conversion material is removed and shaped into a required shape, thereby having an outer shape as shown in FIG. 1 and an electrode joint surface as shown in FIG. A thermoelectric conversion element is obtained. FIG. 15 shows an enlarged end portion of one wire having a diameter of 25 μm that appears on the electrode joint surface of the thermoelectric conversion element.
By such a method, a thermoelectric conversion element having a cross-sectional area of 2 mm square and a height of about 1 to 2.5 mm, which is used for a normal thermoelectric conversion device, can be produced.

(Method using powder material)
The glass capillary plate 21 of FIG. 2 is prepared, and a powder of a thermoelectric conversion material having a particle diameter sufficiently smaller than the diameter of the hole 23 formed in the glass capillary plate 21 is prepared. Next, this powder material is introduced into the hole 23 of the glass capillary plate 21, and high temperature and high pressure are applied from the outside of the glass capillary plate by hot pressing to wire the thermoelectric conversion material and to integrate with the glass capillary plate. Let The temperature and pressure at this time are set in the same manner as in the conventional method for forming a bulk element using a hot press method.
A portion where the wire array of thermoelectric conversion material is formed is cut out from the obtained molded body, polished, and shaped into a required shape to obtain a thermoelectric conversion element.

(How to bundle wires)
When surrounding the microwire of the thermoelectric conversion material using a polymer material that cannot be processed at a high temperature, the microwire of the thermoelectric conversion material is prepared in advance, and the bundle of microwires is solidified with the polymer material.
For that purpose, by preparing a jig with a hole corresponding to the desired diameter, placing the melted thermoelectric conversion material on one side of this jig, and cooling the liquid thermoelectric conversion material through the hole of the jig Turn into a wire. At this time, in order to pass through the holes, pressure is applied to the dissolved thermoelectric conversion material as necessary.
When the microwire of the thermoelectric conversion material is obtained in this manner, the bundle of microwires is immersed in a liquefied polymer material, and then the polymer material is solidified and combined to obtain a thermoelectric conversion element.

  When producing a thermoelectric conversion element by these methods, if the diameter of the microwire is smaller than 0.1 μm, a very high pressure is required for thinning, and the production becomes extremely difficult. Therefore, as for the thickness of each wire which comprises the wire array of a thermoelectric conversion element, it is desirable to set a diameter to 0.1 micrometer or more practically. In addition, the upper limit of the thickness of each wire needs to be set to a diameter of 1 mm or less in order to reduce the effective thermal conductivity. In this case, if about 100 wires having a diameter of 1 mm are integrated in a thermoelectric conversion element having a cross section of 12 mm × 12 mm, the hole area ratio (or the area ratio of the thermoelectric conversion material at the electrode bonding surface) can be maintained at 55%.

Note that the cross section of the microwire need not be limited to a circle, and may be a rectangle, a triangle, or the like. Therefore, the hole of the glass capillary plate or the hole of the jig may be a square or a triangle.
The outer shape of the thermoelectric conversion element can be changed to any shape depending on the shaping method, but shaping is easier if the height (h in FIG. 1) is set to 1 mm or more.
In addition, when there is a thermoelectric conversion material that can be formed into a wire array at a temperature that does not damage the polymer material, the capillary plate may be composed of a polymer material such as acrylic or polyethylene instead of the glass capillary plate.

  The thermoelectric conversion element of the present invention can be widely used for optical communication semiconductor lasers, high-performance CPU cooling elements, waste heat power generation elements, superconducting application devices, etc. by improving thermoelectric conversion performance. .

The figure which shows the external shape of the thermoelectric conversion element in the 1st Embodiment of this invention The figure which shows the glass capillary plate used in the 1st Embodiment of this invention The figure which shows the electrode joint surface of the thermoelectric conversion element in the 1st Embodiment of this invention The figure explaining the flow of the heat | fever in the microwire contained in the thermoelectric conversion element in the 1st Embodiment of this invention The figure which contrasted the temperature dependence of the thermal conductivity of Bi wire contained in the thermoelectric conversion element in the 1st Embodiment of this invention, and bulk Bi. The figure which shows the heat conductivity when the diameter of the Bi wire contained in the thermoelectric conversion element in the 1st Embodiment of this invention is changed. The figure which shows ZT value when changing the diameter of the Bi wire contained in the thermoelectric conversion element in the 1st Embodiment of this invention. The figure which shows the parameter of bulk BiTe type thermoelectric conversion material The figure which shows thermal conductivity when the diameter of the BiTe wire contained in the thermoelectric conversion element in the 1st Embodiment of this invention is changed. The figure which shows Z value and ZT value when changing the diameter of the BiTe wire contained in the thermoelectric conversion element in the 1st Embodiment of this invention. The figure which shows the heat conductivity when changing the aperture ratio of the thermoelectric conversion element in the 1st Embodiment of this invention. The figure which shows the heat conductivity of the polymeric material used with the thermoelectric conversion element in the 1st Embodiment of this invention. The figure explaining the manufacturing method of the thermoelectric conversion element in the 2nd Embodiment of this invention The figure which shows the longitudinal cross-section (b) of the ingot (a) manufactured with the manufacturing method in the 2nd Embodiment of this invention, and the glass capillary plate cut out from the ingot The figure which shows one wire end part which appeared on the electrode joint surface of the thermoelectric conversion element manufactured with the manufacturing method in the 2nd Embodiment of this invention. The figure which shows the structure of the conventional thermoelectric conversion apparatus which combined the thermoelectric conversion element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Thermoelectric conversion apparatus 11 P-type semiconductor 12 N-type semiconductor 13 Lower metal electrode 14 Upper metal electrode 15 Heat dissipation board 16 Endothermic board 17 Lead wire 20 Thermoelectric conversion element 21 Glass capry plate 22 Bi microwire 23 Through-hole 31 Thermoelectric conversion material 32 reactor

Claims (6)

  A wire array in which linear bodies of thermoelectric conversion materials having a diameter corresponding to a diameter of 0.1 μm to 1 mm are integrated, and an insulator having a lower thermal conductivity than the thermoelectric conversion materials surrounding each of the linear bodies A thermoelectric conversion element composed of   The thermoelectric conversion element according to claim 1, wherein the insulator has a porous structure in which a plurality of through holes are formed, and the thermoelectric conversion material is filled in the through holes of the insulator. Conversion element.   It is a thermoelectric conversion element of Claim 2, Comprising: The thermoelectric conversion element whose porosity of the said insulator is 10 to 90%.   While the thermoelectric conversion material is melted, a porous structure having a plurality of through-holes having a diameter corresponding to a diameter of 0.1 μm to 1 mm formed by an insulator having a lower thermal conductivity than the thermoelectric conversion material is immersed. A method for producing a thermoelectric conversion element, wherein the thermoelectric conversion material is filled in a through hole of the porous structure.   The thermoelectric conversion material powder is formed in the through-hole of the porous structure having a plurality of through-holes having a diameter corresponding to a diameter of 0.1 μm to 1 mm, which is formed of an insulator having a lower thermal conductivity than the thermoelectric conversion material. A method for producing a thermoelectric conversion element, comprising introducing and applying heat and pressure to integrate the thermoelectric conversion material with the porous structure. A linear body of a thermoelectric conversion material having a diameter corresponding to a diameter of 0.1 μm to 1 mm is formed, and a plurality of the linear bodies are combined with a polymer material having a lower thermal conductivity than the thermoelectric conversion material. The manufacturing method of the thermoelectric conversion element characterized by the above-mentioned.