JP2005159019A - Thermoelectric module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermoelectric module improved in temperature difference characteristics and heat absorbing characteristics. <P>SOLUTION: In the thermoelectric module equipped with a supporting substrate, the same number of n-type and p-type thermoelectric elements arrayed on the supporting substrate, wiring conductors for electrically connecting a plurality of the thermoelectric elements and external connecting terminals connected electrically to the wiring conductors, the specific resistance of the n-type thermoelectric element and that of the p-type thermoelectric element are specified so as to be different from each other. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a thermoelectric module used for temperature adjustment of a heating element such as a semiconductor laser or a refrigerator.

  Conventionally, a thermoelectric module using the Peltier effect has been used for cooling because a temperature difference is generated by passing an electric current, and one end generates heat and the other end absorbs heat. In particular, it is expected to be widely used for temperature control of laser diodes, portable refrigerators, thermostats, photodetectors, semiconductor manufacturing devices, and the like. In particular, since it is freon-free, vibration-free, and noise-free, it is expected to be used in household refrigerators and air conditioners.

This cooling thermoelectric module used near room temperature has a configuration in which a plurality of pairs of the same number of P-type and N-type thermoelectric elements are electrically connected in series, and the thermoelectric elements used there In general, A ₂ B ₃ type crystals (A is Bi and / or Sb, B is Te and / or Se) are generally used from the viewpoint of excellent cooling characteristics.

A solid solution of Bi ₂ Te ₃ (bismuth telluride) and Sb ₂ Te ₃ (antimony telluride) is used as a P-type thermoelectric element, and Bi ₂ Te ₃ and Bi ₂ Se ₃ (bismuth selenide) are used as N-type thermoelectric elements. Therefore, these A ₂ B ₃ type crystals (A is Bi and / or Sb, B is Te and / or Se) are widely used as thermoelectric elements.

These thermoelectric elements are formed from a thermoelectric crystal material, and their thermoelectric characteristics are expressed by a figure of merit. Here, the figure of merit Z is defined as Z = S ² / ρk, where the Seebeck coefficient is S, the resistivity is ρ, and the thermal conductivity is k, and when the thermoelectric crystal material is used as a thermoelectric element. It shows performance and efficiency. In other words, a thermoelectric module that is more excellent in cooling performance and efficiency is obtained as a material having a higher performance index is used for the N-type thermoelectric element and the P-type thermoelectric element.

  As a thermoelectric material with a high figure of merit, an ingot or crystal close to a single crystal with the crystal orientation aligned by a unidirectional solidification technique based on a known single crystal manufacturing technique such as the Bridgeman method, the pulling (CZ) method, or the zone melt method A melted material made of a body has been proposed (see Non-Patent Document 1).

  In addition, since the melted material has a problem of being easily chipped, a molten alloy obtained by melting and solidifying a mixed powder of Bi, Sb, Te, Se, etc. is pulverized from the viewpoint of increasing the processing yield when manufacturing the thermoelectric module. There has been proposed a sintered material obtained by obtaining an alloy powder and pressurizing and sintering the alloy powder by hot pressing or the like (see Patent Documents 2 and 3).

  In addition, thermoelectric modules are manufactured by thermoelectric elements manufactured using these sintered materials and smelting materials. From the viewpoint of increasing the figure of merit, processing yield, or improving the reliability of thermoelectric modules, smelting materials A thermoelectric module in which a sintered material is combined has also been proposed (see Patent Documents 4 and 5).

Furthermore, it has been reported that the performance of the thermoelectric module is further enhanced by using a single crystal material for the N-type thermoelectric element and a sintered material for the P-type thermoelectric element, and making the specific resistance of these thermoelectric elements substantially the same. (See Patent Document 6).
Thermoelectric semiconductors and their applications (Nikkan Kogyo Shimbun, p. 149) Japanese Patent Publication No. 8-32588 JP-A-1-106478 JP-A-8-148725 JP-A-11-26818 US Patent No. 5448109B1

  However, demands for improving the performance of thermoelectric modules are further increasing, and in particular, the required characteristics are diversifying. For example, in refrigerator applications, the amount of heat absorbed, that is, the heat absorption characteristics, is more important than the temperature difference between the upper and lower surfaces when a thermoelectric module is energized. For example, a temperature difference higher than the endothermic characteristic is required because it is necessary to maintain the temperature.

  However, with respect to these requirements, the methods described in Non-Patent Document 1 and Patent Documents 2 to 6 have limitations in improving performance, and both the endothermic characteristics and the maximum temperature difference increase according to the performance index. For this reason, module design with features for each required characteristic is still insufficient.

  Accordingly, an object of the present invention is to provide a thermoelectric module in which either endothermic characteristics or temperature difference characteristics are enhanced in response to these requirements.

  In the present invention, N-type thermoelectric elements and P-type thermoelectric elements having different thermoelectric characteristics manufactured by various methods are prepared in advance, thermoelectric modules are manufactured in various combinations, and the endothermic characteristics and temperature difference characteristics are examined. As a result, it is based on the knowledge that either the endothermic characteristic or the temperature difference characteristic of the thermoelectric module is improved by combining different specific resistances of the N-type and P-type thermoelectric elements.

  That is, the thermoelectric module of the present invention includes a support substrate, N-type and P-type thermoelectric elements arranged in the same number on the support substrate, a wiring conductor that electrically connects the plurality of thermoelectric elements in series, A thermoelectric module comprising an external connection terminal provided on the support substrate and electrically connected to the wiring conductor, wherein the N-type thermoelectric element and the P-type thermoelectric element have different specific resistances It is.

  The N-type thermoelectric element is made of a melted material, and the P-type thermoelectric element is made of a sintered material.

The output factor ((Seebeck coefficient) ² / specific resistance) of the P-type thermoelectric element and the P-type thermoelectric element is 4 × 10 ⁻³ W / mK ² or more.

  The specific resistance ratio (N-type / P-type) of the N-type thermoelectric element and the P-type thermoelectric element is 0.7 or more and 0.95 or less.

  The specific resistance ratio (N-type / P-type) of the N-type thermoelectric element and the P-type thermoelectric element is 1.05 or more and 1.30 or less.

  The N-type element is a rod-like crystal produced by unidirectional solidification.

  The P-type element is a sintered body having a particle size of 50 μm or less.

  As a result, it is possible to further improve the performance of the thermoelectric module, simultaneously increase the module strength, and at the same time increase the reliability.

  In the thermoelectric module of the present invention, it is possible to improve only the heat absorption characteristic or temperature difference characteristic of the thermoelectric module by providing a difference in specific resistance between the N-type thermoelectric element and the P-type thermoelectric element.

  Moreover, it consists of N type thermoelectric elements which consist of melting materials, and the effect mentioned above can be improved significantly by combining the P type thermoelectric element which consists of sintered materials.

  Moreover, a practical cooling characteristic can be expressed by making an output factor a certain value or more.

  Further, the maximum temperature difference of the thermoelectric module can be increased by controlling the specific resistance of the N-type thermoelectric element to be smaller than that of the P-type thermoelectric element.

  Further, by controlling the specific resistance of the N-type thermoelectric element to be larger than that of the P-type thermoelectric element, the heat absorption amount of the thermoelectric module can be increased.

  Furthermore, by using a rod-like crystal for the N-type thermoelectric element, the performance of the thermoelectric module can be further enhanced and at the same time the cost can be reduced.

  Furthermore, by using a thermoelectric element made of a fine sintered material for the P-type thermoelectric element, a thermoelectric module having particularly excellent endothermic characteristics or temperature difference characteristics in the cooling performance can be obtained.

  Hereinafter, embodiments of the present invention will be described in detail.

  As shown in FIG. 1, the present invention relates to a thermoelectric module in which specific resistances of an N-type thermoelectric element 5a and a P-type thermoelectric element 5b are different.

  The thermoelectric module of the present invention includes support substrates 1 and 2 made of ceramics such as alumina or insulating resin, and N-type thermoelectric elements 5a and P-type thermoelectric elements 5b arranged in the same number on the support substrates 1 and 2. Wiring conductors 3 and 4 for electrically connecting the plurality of thermoelectric elements in series, and external connection terminals 6 provided on the support substrates 1 and 2 and electrically connected to the wiring conductors 3 and 4 In the known thermoelectric module, the specific resistances of the N-type thermoelectric element 5a and the P-type thermoelectric element 5b are different.

  According to the present invention, the thermoelectric element can be produced by a known method.

  For example, it is obtained by slicing a thermoelectric material into a thickness in a direction in which it is sandwiched between thermoelectric modules, plating with Ni or Au in order to improve solderability, and then cutting into a desired shape.

  According to the present invention, as a method for producing thermoelectric elements having different specific resistances, pressure is applied during element production or single crystallization is performed to change the crystal orientation, or in the case of the N-type thermoelectric element 5a, iodine, bromine, etc. In the case of the P-type thermoelectric element 5b, the specific resistance can be adjusted by changing the addition rate of elements such as Te and Se.

  By making the specific resistances of the N-type thermoelectric element 5a and the P-type thermoelectric element 5b not equal, either the heat absorption amount or the temperature difference of the thermoelectric module can be improved as compared with the equivalent case.

  Here, the specific resistance is different from the case where the specific resistance of the thermoelectric material measured by the four probe method is sufficiently different from the accuracy of the measuring instrument. According to the present invention, the N-type thermoelectric element 5a And the difference in specific resistance between the P-type thermoelectric element 5b is 5% or more.

  A factor that can improve either the heat absorption amount or the temperature difference of the thermoelectric module by giving a difference in specific resistance in this way is not clear but is considered as follows.

  As for the carrier for transferring the heat of the thermoelectric semiconductor, the N-type thermoelectric element 5a is an electron and the P-type thermoelectric element 5b is a hole.

  Here, the hole movement is an apparent movement, and in the P-type thermoelectric element 5b, electrons move in the direction opposite to the heat movement.

  Therefore, the movement of heat when the thermoelectric module is energized is performed in the same direction as the direction of electrons in the N-type thermoelectric element 5a, but reverse to the direction of electrons in the P-type thermoelectric element 5b. Since the electrons themselves act as heat carriers, it is considered that the heat transfer of the N-type thermoelectric element 5a itself is rate-limiting with respect to the action of transferring heat, which is a substantial property of the thermoelectric module.

  At this time, if the specific resistance of the N-type thermoelectric element 5a is larger than the specific resistance of the P-type thermoelectric element 5b, that is, if the electric conductivity of the P-type thermoelectric element 5b is larger than that of the N-type thermoelectric element 5a, the P-type thermoelectric element It is considered that the carrier concentration of the N-type thermoelectric element 5a itself is smaller than that of 5b, and the N-type thermoelectric element 5a has a large thermoelectromotive force, that is, a Seebeck coefficient.

  Since the Seebeck coefficient dominates the heat absorption amount of the thermoelectric module, in this case, the heat absorption amount can be increased as compared with the case where the specific resistances of the P-type thermoelectric element 5b and the N-type thermoelectric element 5a are equivalent.

  Similarly, when the specific resistance of the N-type thermoelectric element 5a is smaller than that of the P-type thermoelectric element 5b, it is considered that the carrier concentration of the N-type thermoelectric element 5a is large, and Joule heating of the N-type thermoelectric element 5a itself can be suppressed. Therefore, it is considered that the temperature difference can be increased as compared with the case where the specific resistances of the P-type thermoelectric element 5b and the N-type thermoelectric element 5a are equivalent.

  In addition, according to the present invention, at this time, the number of N-type thermoelectric elements 5a and P-type thermoelectric elements 5b must be the same and joined in series. In the thermoelectric module, since the N-type thermoelectric element 5a and the P-type thermoelectric element 5b operate in pairs, if the number is not the same, elements that do not contribute to cooling remain, increasing Joule heat generation and reducing cooling performance.

  Further, when not in series, the wiring for joining becomes large and complicated, and this also increases the Joule heat generation, which is not preferable.

  The size of the thermoelectric element varies depending on the desired cooling performance and size, but in general cooling applications, the length and width are 0.4 to 2.0 mm, and the height is 0.3 to 3.0 mm is appropriate, and the electrode size is preferably 1.5 to 2.0 times the length of the element in order to improve the performance.

  Further, according to the present invention, in the thermoelectric module using the N-type made of the melted material and the P-type thermoelectric element 5b made of the sintered material, the specific resistances of the N-type thermoelectric element 5a and the P-type thermoelectric element 5b are different. Is particularly preferred.

  By using the N-type thermoelectric element 5a as a melting material in this way, the N-type thermoelectric element 5b is less affected by scattering of electron conduction due to grain boundaries, and thus the above-described effects are increased.

  According to the present invention, the melting material refers to all materials that melt and solidify the alloy in the cooling process, and naturally includes single crystal materials such as unidirectionally solidified materials.

  Further, the sintered material refers to all the polycrystalline materials obtained by pulverizing the melted material once or by pulverizing it in a cooling process, followed by pressure sintering with a hot press or the like.

Further, according to the present invention, the output factor ((Seebeck coefficient) ² / specific resistance) of the N-type thermoelectric element 5a and the P-type thermoelectric element 5b is preferably 4 × 10 ⁻³ W / mK ² or more. As the output factor is higher, the figure of merit tends to be larger. When the output factor is 4 or more, the effect of the present invention is enhanced.

  Moreover, although the performance of a thermoelectric module falls significantly in the element whose output factor is less than 4, there is no practical problem.

  Furthermore, according to the present invention, in order to increase the maximum temperature difference, the above-mentioned specific resistance ratio (N-type / P-type) between the N-type thermoelectric element 5a and the P-type thermoelectric element 5b is 0.7 or more and 0. It is preferable that it is 95 or less.

  Within such a range, the carrier concentration of the N-type thermoelectric element 5a described above can be increased, and the temperature difference of the thermoelectric module can be increased. In particular, 0.90 or less, further 0.85 or less is preferable for improving the temperature difference.

  At this time, if the specific resistance ratio is less than 0.7, the difference in specific resistance is too large, so that the above-described effects cannot be exhibited. If it is larger than 0.95, the effect of improving the temperature difference is reduced, which is not preferable.

  Here, the temperature difference refers to a temperature difference between the cooling surface and the heat radiating surface when the heat radiating surface of the thermoelectric module is energized at a constant temperature. According to the present invention, this temperature difference is expressed with the N-type thermoelectric element 5a. Compared with the case where the specific resistance of the P-type thermoelectric element 5b is made equal, it can be increased by 0.1 ° C. or more.

  Similarly, according to the present invention, in order to increase the amount of heat absorption, the specific resistance ratio (N-type / P-type) of the N-type thermoelectric element 5a and the P-type thermoelectric element 5b is 1.05 or more and 1.30 or less. It is preferable to make it. Within such a range, the carrier concentration of the N-type thermoelectric element 5a described above can be reduced, and the heat absorption amount of the thermoelectric module can be increased. In particular, 1.10 or more, and further 1.15 or more are preferable for increasing the endothermic amount.

  At this time, if the specific resistance ratio is larger than 1.30, the specific resistance difference is too large, and thus the above-described effects cannot be exhibited. If it is less than 1.05, the effect of increasing the endothermic amount is small, which is not preferable.

  Here, the endothermic amount is the same as the temperature difference characteristic described above, while energizing the heat dissipation surface to a maximum temperature while keeping the heat dissipation surface at a constant temperature, heating the cooling surface, and heat dissipation from the cooling surface. The amount of heating on the cooling surface when the temperature of the surface becomes constant can be measured using a heater or the like having the same shape as the cooling surface. According to the present invention, the endothermic amount can be improved by 5% or more as compared with the case where the specific resistance is equal in the modules having the same shape.

  In addition, according to the present invention, the N-type thermoelectric material is particularly preferably produced from a rod-like crystal produced by unidirectional solidification among the melted materials.

  By producing the N-type thermoelectric element 5a by high-performance unidirectional solidification, it is possible to enhance the performance of the thermoelectric module to the limit, and at the same time, the effect of enhancing the cooling performance of the thermoelectric module described above can be increased.

  Furthermore, by using a rod-shaped crystal body, it is possible to greatly reduce the number of man-hours for cutting and to suppress a reduction in processing yield, which is a defect of the melted material.

  Moreover, according to the present invention, it is desirable that the P-type thermoelectric element 5b is made of a sintered body having a particle size of 50 μm or less.

  When the particle size is 50 μm or less, the thermal conductivity decreases rapidly. A P-type sintered body having a low thermal conductivity can increase the difference in electronic conductivity and increase the effect of the difference in specific resistance due to the difference in thermal conductivity when combined with an N-type melted material. it can.

  The particle size of the P-type sintered material is particularly preferably 30 μm or less.

  In addition, such a sintered body having a small particle size has high strength and can improve the reliability of the thermoelectric module.

  In this way, the thermoelectric module in which the specific resistance of the N-type thermoelectric element 5a and the P-type thermoelectric element 5b is different from the thermoelectric module in the equivalent case, either the temperature difference characteristic or the endothermic characteristic in the cooling performance. Can be increased.

  As a result, the thermoelectric module according to the present invention is expected to be applied to laser diode cooling, semiconductor wafer cooling plates that require high temperature control, or household refrigerators, coolers, etc. that require high heat absorption characteristics. .

  Next, examples of the present invention will be described.

First, various N-type and P-type thermoelectric materials were produced. The production method prepared Bi, Te, Sb, Se metal powder with a purity of 99.99% or more, and SbI ₃ powder and SbBr ₃ powder as dopants for N-type thermoelectric elements. The N-type thermoelectric material was based on the Bi ₂ Te _2.85 Se _0.15 composition, and the amount of dopant was adjusted in order to adjust the specific resistance.

The P-type thermoelectric material was based on Bi _x Sb _2-x Te ₃ and the specific resistance was adjusted by changing x from 0.3 to 0.7.

  The raw materials were weighed to the desired composition, filled into a carbon crucible, and sealed with a lid. The molten alloy was produced by placing in a quartz tube and performing vacuum substitution in an argon atmosphere at 800 ° C. for 5 hours.

  The molten alloy was pulverized with a stamp mill in a glove box, passed through a sieve with 2 mm openings, and then pulverized with a small vibration mill using silicon nitride as a ball for 1 to 12 hours. The mixture was heated in a hydrogen stream for a period of time and subjected to reduction treatment to obtain a fine powder alloy powder.

  The powder was hot-pressed using a carbon die having a diameter of 20 mm to 10 mm to obtain a sintered body.

For the sintered body, a 2 × 3 × 15 mm rectangular parallelepiped is cut out so that the direction perpendicular to the pressing direction is the longitudinal direction, and the longitudinal Seebeck coefficient (S) is obtained using a commercially available Seebeck coefficient measuring device (ZEM device manufactured by Vacuum Riko). ) And specific resistance (ρ) were measured, and the output factor (S ² / ρ) was calculated.

  Similarly, slice the remainder of the sintered body at a thickness of 0.9 mm so that the pressing direction is the thickness direction, and after applying Ni electroless plating and Au plating, dicing into a shape of □ 0.65 mm The thermoelectric element was obtained.

  The production of a unidirectionally solidified material as a melting material will be described below.

  The produced alloy powder is placed on top of a carbon mold mold having a square shape and a cross-sectional shape of □ 0.65 and a cylindrical gap of 100 mm in length, and a vertical quartz tube is used as a furnace core tube. After melting at 700 ° C with a crystal growth device (Bridgeman method), filling the gap with the melt, cooling while moving the mold on the principle of the Bridgeman method, near the freezing point (about 600 ° C) Crystal growth was performed at a rate of 2 to 3 mm / H, and a long body made of a unidirectionally solidified thermoelectric crystal material of an N-type thermoelectric element 5a and a P-type thermoelectric element 5b was produced.

The obtained rod-shaped unidirectionally solidified thermoelectric crystal material was cut into 15 mm in the longitudinal direction, and the Seebeck coefficient (S) and specific resistance (ρ) were measured in the same manner to calculate the output factor (S ² / ρ).

  Furthermore, a thermoelectric element was produced using this rod-shaped unidirectionally solidified thermoelectric crystal material.

  First, the side surface of the unidirectionally solidified thermoelectric material was coated with a commercially available plating resist (acrylic resin), and then cut into a length of 0.9 mm with a dicing saw to produce a rectangular parallelepiped element.

  Electroless plating is performed on the obtained element, a Ni plating layer is formed so as to have a thickness of 5 to 10 μm, then Au plating with a thickness of 0.1 μm is applied, and then placed in an alkaline solution, and ultrasonic cleaning is performed. The plating layer adhering to the plating resist on the side surface of the element was removed, and a plating layer was formed only on the cut surface, thereby producing a thermoelectric element.

  As another method for producing the melted material, an ingot having a diameter of 30 was grown by a zone melt method using an infrared image furnace. The ingot was sliced perpendicular to the growth direction, a thermoelectric element was produced in the same manner as the sintered body, and thermoelectric characteristics were calculated.

  Using 23 each of the N-type and P-type thermoelectric elements obtained by the above manufacturing method, a grid-like arrangement using SnSb (95 to 5) solder paste on an alumina ceramic substrate with 6 × 8 mm copper wiring A thermoelectric module was obtained by arranging using jigs and heating and bonding to 250 to 280 ° C. with a ceramic heater.

  In the thermoelectric module, the cooling surface is joined to a heat sink whose temperature is adjusted to 27 ° C. via heat conductive grease, energized, and the temperature at the top of the cooling surface is measured with a 0.1 mm diameter K-type thermocouple. The temperature at which the difference between ° C. and the cooling surface temperature was the maximum was taken as the maximum temperature difference.

  Furthermore, in a state where power is supplied under the condition where the maximum temperature difference is obtained, the cooling surface is heated using a ceramic heater having the same shape as the cooling surface substrate, and the output of the ceramic heater when the cooling surface temperature reaches 27 ° C. The endothermic amount was obtained.

  Further, the obtained thermoelectric element was observed by a SEM for a fracture surface, and an average particle diameter was determined from about 300 particles by a line intercept method.

The results are also shown in Table 1.

  As is apparent from Table 1, the comparative examples No. 1 and No. 5 of the N-type thermoelectric element 5a and the P-type thermoelectric element 5b, which are outside the scope of the present invention, are equivalent. 8 to 11 and 28, 33, 42 and 45, the maximum temperature difference is 73.2 to 73.8 ° C. and the endothermic amount is 3.01 to 3.06 W, which is within the scope of the present invention. Example No. 5 in which the specific resistances of the N-type thermoelectric element 5a and the P-type thermoelectric element 5b are different. 1 to 7, 13 to 27, 29 to 32, 34 to 41, and 43, 44, 46 all have a maximum temperature difference of 74.3 ° C. or higher, or an endothermic amount of 3.10 W or higher. Either the maximum temperature difference or the endothermic amount of the module was improved.

  Sample No. 6 and 29 and 16 and 27 have the same specific resistance ratio, but the module characteristics indicate that the N-type thermoelectric element is preferably not melted but melted.

  In addition, it is preferable that the Seebeck coefficient is 4 or more in Sample No. 21-26.

  Further, it is preferable that the specific resistance ratio is 0.7 or more and 0.95 or less and that the specific resistance ratio is 1.05 or more and 1.30 or less. I understand from 1-20.

Further, it is preferable that the N-type element is a rod-shaped crystal produced by unidirectional solidification.
Sample No. It can be seen from 27 and 30.

  Further, it is preferable that the P-type element is a sintered body having a particle size of 50 μm or less. I understand from 38-39.

It is a perspective view which shows one Embodiment of the thermoelectric module of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 ... Support substrate 3, 4 ... Wiring conductor 5a ... N type thermoelectric element 5b ... P type thermoelectric element 6 ... External connection terminal

Claims (7)

A support substrate, N-type and P-type thermoelectric elements arranged in the same number on the support substrate, a wiring conductor that electrically connects the plurality of thermoelectric elements in series, and provided on the support substrate; A thermoelectric module comprising an external connection terminal electrically connected to a wiring conductor, wherein the N-type thermoelectric element and the P-type thermoelectric element have different specific resistances. The thermoelectric module according to claim 1, wherein the N-type thermoelectric element is made of a melted material, and the P-type thermoelectric element is made of a sintered material. 3. The thermoelectric module according to claim 1, wherein an output factor ((Seebeck coefficient) ² / specific resistance) of the P-type thermoelectric element and the P-type thermoelectric element is 4 × 10 ⁻³ W / mK ² or more. . 4. The thermoelectric module according to claim 1, wherein a ratio of specific resistance between the N-type thermoelectric element and the P-type thermoelectric element (N-type / P-type) is 0.7 or more and 0.95 or less. 5. . 4. The thermoelectric module according to claim 1, wherein a ratio of specific resistance between the N-type thermoelectric element and the P-type thermoelectric element (N-type / P-type) is 1.05 or more and 1.30 or less. 5. . The thermoelectric module according to claim 1, wherein the N-type element is a rod-like crystal produced by unidirectional solidification. The thermoelectric module according to claim 1, wherein the P-type element is a sintered body having a particle size of 50 μm or less.

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