JP2014107443A - Thermoelectric conversion device and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoelectric conversion device which can enhance thermoelectric conversion efficiency while including film p-type metal oxide semiconductor element and n-type metal oxide semiconductor element, and to provide a manufacturing method therefor.SOLUTION: In a thermoelectric conversion device 10 including a substrate 11, p-type metal oxide semiconductor elements 12a-12c and n-type metal oxide semiconductor elements 13a-13c arranged on the surface of the substrate 11 and connected in series, the p-type metal oxide semiconductor elements 12a-12c and n-type metal oxide semiconductor elements 13a-13c are film elements, the n-type metal oxide semiconductor elements 13a-13c are formed by spray coating, and have a porosity of 5% or less.

Description

The present invention relates to a thermoelectric conversion device including a base material, a p-type metal oxide semiconductor element and an n-type metal oxide semiconductor element that are arranged on the surface of the base material and connected in series, and a method for manufacturing the thermoelectric conversion device.

A thermoelectric conversion device including a p-type semiconductor element and an n-type semiconductor element connected in series includes a cooling device that converts electricity into heat using the Peltier effect, and a thermoelectric power generation device that converts heat into electricity using the Seebeck effect There is. This thermoelectric power generation device is attracting attention as a device that can effectively use waste heat generated in large-scale facilities such as thermal power plants and garbage incinerators, and other automobile engines and gas water heaters. In particular, by using a metal oxide having excellent heat resistance and the like for each semiconductor element, it is said that the usability under high temperature conditions is increased.

A conventional general thermoelectric converter will be described with reference to FIG. The thermoelectric conversion device 30 shown in FIG. 3 includes a pair of base materials 31 and 32 arranged in opposition to each other, and a plurality of them arranged alternately (for example, in a lattice shape in plan view) between the pair of base materials 31 and 32. The p-type semiconductor element 33 and the n-type semiconductor element 34 and the p-type semiconductor element 33 and the n-type semiconductor element 34 are stacked on the inner surface side of the pair of base materials 31 and 32 so as to be connected alternately and in series. A plurality of electrodes 35 are mainly provided. In this thermoelectric conversion device 30, for example, by arranging one base material 31 on the high temperature side and the other base material 32 on the low temperature side, an electromotive force is generated by the Seebeck effect and functions as a thermoelectric power generation device.

As described above, the conventional thermoelectric conversion device (power generation device) has a laminated structure, and generates power using the temperature difference between the front surface side and the back surface side (temperature difference between both substrates disposed opposite to each other). It becomes. Therefore, development of thermoelectric conversion devices having other structures is desired in order to cope with various usage environments. Under such circumstances, a thermoelectric conversion device in which an n-type semiconductor element and a p-type semiconductor element are formed in a film shape by a thermal spraying method on the surface of a plate-like body has been developed (see Patent Document 1). By disposing this thermoelectric conversion device as a heat radiating fin on the outer wall of the duct through which the heat source fluid flows, it is said that power can be generated using the temperature difference in the extending direction of the heat radiating fin.

JP 2001-28463 A

However, the thermoelectric conversion device in which each semiconductor element is formed into a film by thermal spraying has a disadvantage that the thermoelectric conversion efficiency is lower than that of the conventional laminated structure due to the element being in the form of a film. . Further, in Patent Document 1, there is no specific description such as the fact that each semiconductor element is formed of a metal oxide semiconductor, and other physical properties of the element obtained by thermal spraying conditions or thermal spraying, which is sufficient in terms of heat resistance and power generation efficiency. That's not true.

The present invention has been made in view of such circumstances, and includes a film-like p-type metal oxide semiconductor element and an n-type metal oxide semiconductor element, and a thermoelectric conversion apparatus capable of increasing thermoelectric conversion efficiency and a method for manufacturing the same. The purpose is to provide.

A thermoelectric conversion device according to a first invention that meets the above-described object is a base material, a p-type metal oxide semiconductor element and an n-type metal oxide semiconductor element that are disposed on the surface of the base material and connected in series. In a thermoelectric conversion device comprising:
The p-type metal oxide semiconductor element and the n-type metal oxide semiconductor element are film-like,
The n-type metal oxide semiconductor element is formed by thermal spraying, and the porosity of the n-type metal oxide semiconductor element is 5% or less.

In the thermoelectric conversion device according to the first aspect of the invention, the n-type metal oxide semiconductor element is densely formed by thermal spraying so that the porosity is 5% or less. Thus, by reducing the porosity of the n-type metal oxide semiconductor element, the electrical conductivity of the n-type metal oxide semiconductor element can be increased, and the thermoelectric conversion efficiency of the thermoelectric conversion device can be increased. Moreover, since the thermoelectric conversion device according to the first invention uses an oxide semiconductor for each element, it is excellent in heat resistance and the like. Since these elements are in a film form, the thermoelectric conversion apparatus is in a direction other than the thickness direction of the substrate. It is possible to convert the generated temperature difference into electric power.

In the thermoelectric conversion device according to the first invention, the p-type metal oxide semiconductor element is preferably formed by thermal spraying. Thus, by forming both the n-type metal oxide semiconductor element and the p-type metal oxide semiconductor element by thermal spraying, (1) the stacking time of each element can be shortened, and no bonding agent is required. Therefore, production efficiency can be increased. (2) Thermal stress and thermal strain that can occur between the substrate and the element can be reduced by controlling the spraying conditions. (3) Improve impact resistance. (4) Wide range of selection of shapes and materials, for example, each element can be formed on a tubular base material, (5) Easy manufacturing process automation, low cost and large size (6) An element obtained by thermal spraying has advantages such as lower thermal conductivity than a bulk element and can suppress a decrease in temperature gradient.

In the thermoelectric conversion device according to the first invention, the n-type metal oxide semiconductor element preferably contains aluminum-doped zinc oxide. Since aluminum-doped zinc oxide is particularly excellent in high-temperature stability and thermoelectric conversion characteristics, it is more suitable for use under high-temperature conditions such as thermal power plants and garbage incineration plants.

In the thermoelectric conversion device according to the first aspect of the invention, the p-type metal oxide semiconductor element preferably contains calcium cobaltate such as Ca ₃ Co ₄ O ₉ , Ca ₉ Co ₁₂ O ₂₈ , and Ca ₉ Co ₁₂ O _28. It is more preferable to contain. Since these calcium cobaltates, particularly Ca ₉ Co ₁₂ O ₂₈ are particularly excellent in high-temperature stability and thermoelectric conversion characteristics, they are more suitable for use under high-temperature conditions.

In the thermoelectric conversion device according to the first invention, it is preferable that the base material is made of ceramics. Heat resistance can be enhanced by using a ceramic substrate. Further, by using ceramics having low thermal conductivity, it is possible to maintain a temperature difference in each element, and as a result, it is possible to increase thermoelectric conversion efficiency.

In the thermoelectric conversion device according to the first invention, it is preferable that the p-type metal oxide semiconductor element and the n-type metal oxide semiconductor element are directly connected. Thus, by using a structure in which a p-type metal oxide semiconductor element and an n-type metal oxide semiconductor element are directly connected without using an electrode film or the like, manufacturing cost can be suppressed.

The thermoelectric conversion device according to the first invention may further include an electrode film that connects the p-type metal oxide semiconductor element and the n-type metal oxide semiconductor element, and the electrode film is formed by thermal spraying. preferable. Even when the electrode film is further provided as described above, the production efficiency can be improved by forming the electrode film by thermal spraying.

A method for manufacturing a thermoelectric conversion device according to a second invention that meets the above-described object includes a base material, a p-type metal oxide semiconductor element and an n-type metal oxide that are disposed on the surface of the base material and connected in series. In a method for manufacturing a thermoelectric conversion device comprising a semiconductor element,
Forming the n-type metal oxide semiconductor element in a film shape on the surface of the base material by spraying aluminum-doped zinc oxide particles;
The spraying temperature in the spraying is 2400 ° C. or more and 2800 ° C. or less, the spraying speed is 1800 m / s or more and 2000 m / s or less, and the spraying distance is 90 mm or more and 110 mm or less. By performing thermal spraying under such thermal spraying conditions, a film-like n-type metal oxide semiconductor element having a low porosity can be formed, and a thermoelectric conversion device with high thermoelectric conversion efficiency can be obtained.

According to the thermoelectric conversion device according to the first aspect of the present invention, the thermoelectric conversion efficiency can be increased while the film-like p-type metal oxide semiconductor element and the n-type metal oxide semiconductor element are provided. According to the method for manufacturing a thermoelectric conversion device according to the second invention, such a thermoelectric conversion device can be obtained.

(A) is a typical top view of the thermoelectric conversion apparatus which concerns on the 1st Embodiment of this invention, (B) is the AA arrow line typical end view. (A) is a typical top view of the thermoelectric conversion apparatus which concerns on the 2nd Embodiment of this invention, (B) is the BB arrow line typical end view. It is typical sectional drawing of the conventional thermoelectric conversion apparatus.

Next, embodiments of the present invention will be described with reference to the accompanying drawings.

<First Embodiment>
As shown in FIGS. 1A and 1B, a thermoelectric conversion device 10 according to the first embodiment of the present invention has a base material 11 and three film-like shapes disposed on the surface of the base material 11. P-type metal oxide semiconductor elements 12a to 12c and three film-like n-type metal oxide semiconductor elements 13a to 13c. Since the thermoelectric conversion device 10 uses an oxide semiconductor for each element, it is excellent in heat resistance and the like.

The substrate 11 is a flat plate having a rectangular shape in plan view. The material of the base material 11 is not particularly limited as long as it has a desired degree of strength, heat resistance, and the like, and examples thereof include metals, synthetic resins, and ceramics. Among these, ceramics are preferable. Heat resistance can be improved by using the ceramic base 11. In addition, by using ceramics having low thermal conductivity for the base material 11, it is possible to maintain the temperature difference in each element, and as a result, the thermoelectric conversion efficiency of the thermoelectric conversion device 10 can be increased. The base material 11 may have a single layer structure made of a single material or a multilayer structure in which a plurality of different materials are laminated. In the case of a multi-layer structure, it may be one in which a film is formed on the surface of ceramics as a base material.

It does not specifically limit as a size of the base material 11, It can set suitably according to a use environment. For example, the thickness can be 1 mm or more and 5 cm or less. When the thickness of the base material 11 is less than 1 mm, heat resistance, strength, and the like may be reduced. On the other hand, if the thickness exceeds 5 cm, the handleability and the like may be reduced.

Each of the p-type metal oxide semiconductor elements 12a to 12c is a substantially band-shaped element made of a metal oxide having p-type semiconductor characteristics. This specific planar shape is an elongated rectangular portion, and a portion extending in the opposite direction from the one end side portion and the other rear end side portion in both long sides of the rectangle in the direction perpendicular to the long side. (In FIG. 1 (A), it is a shape (substantially S-shape) consisting of an upper part of the right side of the rectangle and a part extending from the lower part of the left side of the rectangle.

The p-type metal oxide semiconductor elements 12 a to 12 c are arranged in parallel at substantially equal intervals along the width direction of the base material 11. Note that the p-type metal oxide semiconductor element 12 c arranged at the end (the right end in FIG. 1) functions as an extraction electrode, and the lead wire 15 is connected via the solder 14.

Each p-type metal oxide semiconductor element 12a-12c is formed by thermal spraying. This specific forming method will be described later as a method for manufacturing the thermoelectric conversion device 10.

The size of each of the p-type metal oxide semiconductor elements 12a to 12c is not particularly limited, and can be set as appropriate according to the usage environment. For example, the width (the width at the position where there is no extending portion) ) 5 mm or more and 5 cm or less and length 1 cm or more and 20 cm or less. Further, the thickness can be 50 μm or more and 1 mm or less, and preferably 100 μm or more and 500 μm or less. When the thickness is less than 50 μm, the electrical resistance may increase and the thermoelectric conversion efficiency may decrease. Conversely, if the thickness exceeds 1 mm, formation by thermal spraying may be difficult.

As the p-type metal oxide semiconductor constituting each of the p-type metal oxide semiconductor elements 12a to 12c, for example, CoO, NiO, FeO, Bi ₂ O ₃ , MoO ₂ , Cr ₂ O ₃ , SrCu ₂ O ₂ , CaO— _{al 2 O 3, Ca 3 Co} 4 O 9, Ca 9 Co 12 O 28 and the like. These can be used alone or in combination of two or more. Among these, calcium cobaltate such as Ca ₃ Co ₄ O ₉ and Ca ₉ Co ₁₂ O ₂₈ is preferable, and Ca ₉ Co ₁₂ O ₂₈ is more preferable. Since these calcium cobaltates, especially Ca ₉ Co ₁₂ O ₂₈ are particularly excellent in high-temperature stability and thermoelectric conversion characteristics, they are suitable for use under high-temperature conditions.

Each of the n-type metal oxide semiconductor elements 13a to 13c is a substantially band-shaped element made of a metal oxide having n-type semiconductor characteristics. This specific planar shape is an elongated rectangular portion, and a portion extending in the opposite direction from the one end side portion and the other rear end side portion in both long sides of the rectangle in the direction perpendicular to the long side. (In FIG. 1 (A), the mirror image shape of the p-type metal oxide semiconductor elements 12a-12c (substantially) which consists of the upper part of the left side of the rectangle and the lower part of the right side of the rectangle. Inverted S-shape).

Each of the n-type metal oxide semiconductor elements 13a to 13c is alternately arranged with the p-type metal oxide semiconductor elements 12a to 12c along the width direction of the base material 11 at substantially equal intervals and in parallel. Adjacent p-type metal oxide semiconductor elements (for example, p-type metal oxide semiconductor elements 12a) and n-type metal oxide semiconductor elements (for example, n-type metal oxide semiconductor elements 13a and 13b) are provided at both end portions. In FIG. 2, only the portions extending facing each other overlap so that the n-type metal oxide semiconductor elements 13a to 13c are on the upper side. As described above, the p-type metal oxide semiconductor elements 12a to 12c and the n-type metal oxide semiconductor elements 13a to 13c are overlapped (connected), so that the p-type metal oxide semiconductor elements 12a to 12c, The n-type metal oxide semiconductor elements 13a to 13c are directly and alternately connected in series. In this manner, the p-type metal oxide semiconductor elements 12a to 12c and the n-type metal oxide semiconductor elements 13a to 13c are directly connected without using an electrode film or the like, thereby reducing the manufacturing cost. be able to. The n-type metal oxide semiconductor element 13 a disposed at the end (left end in FIG. 1) functions as an extraction electrode, and the lead wire 17 is connected via the solder 16.

Each of the n-type metal oxide semiconductor elements 13a to 13c is formed by thermal spraying. This specific forming method will be described later as a method for manufacturing the thermoelectric conversion device 10.

The size of each of the n-type metal oxide semiconductor elements 13a to 13c is not particularly limited, and can be appropriately set according to the use environment or the like, but the length is p-type metal oxide semiconductor elements 12a to 12c. It is the same. Specifically, for example, the width (the width at the position where there is no extending portion) can be 5 mm or more and 5 cm or less and the length can be 1 cm or more and 20 cm or less. Further, the thickness can be 50 μm or more and 1 mm or less, and preferably 100 μm or more and 500 μm or less. When the thickness is less than 50 μm, the electrical resistance may increase and the thermoelectric conversion efficiency may decrease. Conversely, if the thickness exceeds 1 mm, formation by thermal spraying may be difficult.

Examples of the n-type metal oxide semiconductor constituting each of the n-type metal oxide semiconductor elements 13a to 13c include Ti (titanium), Zn (zinc), Sn (tin), Nb (niobium), In (indium), Y (Yttrium), La (lanthanum), Zr (zirconium), Sr (strontium), Ca (calcium), W (tungsten), etc. At least 1 sort (s) of oxide semiconductors can be mentioned. These oxide semiconductors may be doped with a nonmetal such as nitrogen or sulfur or a metal such as aluminum. Among these, ZnO (zinc oxide) is preferable, and aluminum-doped ZnO is more preferable. Aluminum-doped zinc oxide is particularly excellent in high-temperature stability and thermoelectric conversion characteristics, and is therefore more suitable for use under high-temperature conditions such as thermal power plants and garbage incineration plants.

Each of the n-type metal oxide semiconductor elements 13a to 13c has a porosity of 5% or less, preferably 4% or less. As described above, the porosity of the n-type metal oxide semiconductor elements 13a to 13c is lowered to form a dense element, whereby the electrical conductivity of the n-type metal oxide semiconductor elements 13a to 13c is increased, and the thermoelectric conversion device 10 Thermoelectric conversion efficiency can be increased. In addition, although it does not specifically limit as a minimum of this porosity, For example, when spraying conditions etc. are considered, it is 1%. Here, the “porosity” is obtained by cutting a film-like element using a precision cutter and filling the resin, and then polishing the cut surface (for example, using 1 μm diamond paste) and using a microscope (for example, 200 × magnification). ) And taking a picture of the cut surface, analyzing the image, and calculating the area of the pore portion (for example, black) in the entire area.

In the thermoelectric conversion device 10, for example, one end side (for example, the lower side in FIG. 1A) of each of the p-type metal oxide semiconductor elements 12a to 12c and the n-type metal oxide semiconductor elements 13a to 13c is used as a high-temperature heat source. The p-type metal oxide semiconductor elements 12a to 12c and the n-type metal oxide semiconductor elements 13a to 13c are arranged so that the other end side (for example, the upper side in FIG. 1A) is relatively low in temperature. Used. Examples of the high-temperature heat source include a chimney in a factory, a combustion device, a duct, a high-temperature heat medium, and the like. Further, the other end may be connected to a heat radiating fin or brought into contact with a cold water pipe or the like so as to increase the temperature gradient. By arranging in this way, an electromotive force is generated between the elements at both ends (between the p-type metal oxide semiconductor element 12c and the n-type metal oxide semiconductor element 13a) by the Seebeck effect, and the two lead wires 15 and 17 are arranged. Electric power can be obtained through the thermoelectric conversion device 10 as a thermoelectric power generation device. The thermoelectric conversion device 10 can also be used as a cooling device (Peltier cooler) by applying a voltage in reverse.

The thermoelectric conversion device 10 includes, for example, a step (1) of forming p-type metal oxide semiconductor elements 12a to 12c in a film shape on the surface of the substrate 11 by thermal spraying of p-type metal oxide semiconductor particles, and an n-type metal It can be obtained by a manufacturing method having a step (2) of forming n-type metal oxide semiconductor elements 13a to 13c in a film shape on the surface of the base material 11 by thermal spraying of oxide semiconductor particles in this order.

Process (1)
The p-type metal oxide semiconductor particles used in this step may be selected from materials corresponding to the p-type metal oxide semiconductor elements 12a to 12c. The p-type metal oxide semiconductor particles are usually used as a slurry using water or the like as a dispersion medium. As a thermal spraying method in this step, a known high-speed flame spraying method using a thermal spray gun can be suitably employed. The spraying temperature (frame temperature) at this time can be set to, for example, 1500 ° C. or more and 3000 ° C. or less. It is preferable that the thermal spraying is performed using a mask or the like corresponding to the element shape in order to form a film with a predetermined surface shape.

When the metal oxide constituting the p-type metal oxide semiconductor elements 12a to 12c is Ca ₉ Co ₁₂ O ₂₈ , Ca ₉ Co ₁₂ O ₂₈ particles are sprayed. In this case, it is preferable that the thermal spray coating obtained by the thermal spraying is fired to form p-type metal oxide semiconductor elements 12a to 12c. When high-speed flame spraying is performed, Ca ₃ Co ₂ O ₆ may be generated due to a decomposition reaction of Ca ₉ Co ₁₂ O ₂₈ . Ca ₃ Co ₂ O ₆ has a lower conversion efficiency than Ca ₉ Co ₁₂ O ₂₈ . Therefore, the thermoelectric conversion efficiency of the resulting thermoelectric conversion device can be increased by firing and regenerating Ca ₉ Co ₁₂ O ₂₈ . Note that the firing temperature is preferably 893 ° C. or more and 926 ° C. or less which becomes the phase of Ca ₉ Co ₁₂ O _{28 in} the CaO—CoO equilibrium diagram.

Process (2)
The n-type metal oxide semiconductor particles used in this step may be selected from materials corresponding to the n-type metal oxide semiconductor elements 13a to 13c. The n-type metal oxide semiconductor particles are usually used as a slurry using water or the like as a dispersion medium. As a thermal spraying method in this step, a known high-speed flame spraying method using a thermal spray gun can be suitably employed. The thermal spraying is preferably performed using a mask or the like corresponding to the element shape in order to form a film with a desired surface shape.

When the metal oxide constituting the n-type metal oxide semiconductor elements 13a to 13c is aluminum-doped zinc oxide, the aluminum-doped zinc oxide particles are sprayed. As described above, aluminum-doped zinc oxide is a good material that is particularly excellent in high-temperature stability and thermoelectric properties. However, aluminum-doped zinc oxide is an unsuitable material for thermal spraying due to its strong covalent bond and vapor pressure. Therefore, in order to form a thermal spray coating suitable as an element of a dense thermoelectric conversion device using aluminum-doped zinc oxide, it is preferable to optimize each condition (spraying temperature, thermal spraying speed and thermal spraying distance) at the time of thermal spraying.

As specific spraying conditions when using aluminum-doped zinc oxide particles, the spraying temperature is 2400 ° C. to 2800 ° C., the spraying speed (particle spraying speed) is 1800 m / s to 2000 m / s, and the spraying distance is 90 mm to 110 mm. The following is preferable. By setting the thermal spraying temperature to 2400 ° C. or higher, the particles are softened and a film having a large film thickness can be formed. However, when the spraying temperature exceeds 2800 ° C., the aluminum-doped zinc oxide particles evaporate due to overheating, and the film forming property is deteriorated. In addition, the occurrence of cracks on the coating surface can be suppressed by setting the spraying temperature to a relatively low temperature. In addition, by setting the spraying speed to 1800 m / s or more, the kinetic energy of the sprayed particles can be increased, and the adhesion to the substrate and the denseness can be increased. However, if the spraying speed exceeds 2000 m / s, the residence time in the frame is shortened and sufficient heating is not performed, so that the adhesion with the substrate is lowered. Furthermore, by setting the spraying distance to 90 mm or longer, the residence time in the frame becomes longer and sufficient heating can be performed, so that film forming properties (film forming properties with a large film thickness, adhesion to a substrate, etc.) Can be increased. However, when the spraying distance exceeds 110 mm, the aluminum-doped zinc oxide particles evaporate due to overheating, and the film forming property is deteriorated.

Here, the spraying temperature is a temperature measured at a position 50 mm from the tip of the spraying gun on the center line of the frame (spraying frame). This thermal spraying temperature can be adjusted by the mixing ratio of the fuel gas (kerosene etc.) and the combustion assisting gas (air + oxygen etc.) forming the frame. The spraying speed can be adjusted by the pressure at the time of supplying the combustion support gas. The spraying distance is the distance from the tip of the spray gun to the substrate.

After the step (1) and the step (2), the lead wires 15 and 17 are connected by the solders 14 and 16, and the thermoelectric conversion device 10 can be obtained.

<Second Embodiment>
As shown in FIGS. 2A and 2B, the thermoelectric conversion device 20 according to the second embodiment of the present invention includes a base material 11 and three film shapes disposed on the surface of the base material 11. P-type metal oxide semiconductor elements 22a to 22c, three film-like n-type metal oxide semiconductor elements 23a to 23c, and five electrode films 24. Since the base material 11 of the thermoelectric conversion device 20 is the same as that of the thermoelectric conversion device 10 of FIG. 1, the same number is attached | subjected and description is abbreviate | omitted.

Each p-type metal oxide semiconductor element 22a-22c and each n-type metal oxide semiconductor element 23a-23c are formed by thermal spraying. Moreover, the material and size of each p-type metal oxide semiconductor element 22a-22c and each n-type metal oxide semiconductor element 23a-23c are the same as that of the thermoelectric conversion apparatus 10 of FIG.

Each p-type metal oxide semiconductor element 22a-22c has a strip shape. In addition, the p-type metal oxide semiconductor elements 22 a to 22 c are arranged at substantially equal intervals and in parallel along the width direction of the base material 11. Note that the p-type metal oxide semiconductor element 22 c disposed at the end (the right end in FIG. 2) functions as an extraction electrode, and the lead wire 26 is connected via the solder 25.

Each n-type metal oxide semiconductor element 23a-23c has a strip shape. In addition, the n-type metal oxide semiconductor elements 23 a to 23 c are alternately arranged with the p-type metal oxide semiconductor elements 22 a to 22 c along the width direction of the base material 11 at substantially equal intervals and in parallel. . That is, the adjacent p-type metal oxide semiconductor elements 22a to 22c and the n-type metal oxide semiconductor elements 23a to 23c are arranged apart from each other (not in direct contact). Note that the n-type metal oxide semiconductor element 23 a disposed at the end (left end in FIG. 2) functions as an extraction electrode, and the lead wire 28 is connected via the solder 27.

Each electrode film 24 has a substantially rectangular shape. In addition, each electrode film 24 is formed so that the p-type metal oxide semiconductor elements 22a to 22c and the n-type metal oxide semiconductor elements 23a to 23c are alternately and in series connected to end portions of adjacent elements and It is laminated | stacked on the surface of the base material 11 exposed in the meantime.

The material of each electrode film 24 is not particularly limited as long as it has conductivity, and metals such as copper, silver, and platinum, carbon, and the like can be used. As a method for forming each electrode film 24, a known method such as a method of baking after printing or coating or a spraying method can be used, but a spraying method is preferable. By forming the electrode film 24 by thermal spraying, the production efficiency can be improved.

The thermoelectric conversion device 20 can be manufactured according to the method for manufacturing the thermoelectric conversion device 10 described above. The method of using the thermoelectric conversion device 20 is the same as that of the thermoelectric conversion device 10.

The present invention is not limited to the above-described embodiment, and the configuration thereof can be changed without changing the gist of the present invention. For example, the shape of the substrate is not limited to a flat plate shape, and may be a rod shape, a tubular shape, or the like. The number of each metal oxide semiconductor element can also be adjusted suitably. The p-type metal oxide semiconductor element may be formed by a method other than thermal spraying (for example, coating and firing).

Hereinafter, the contents of the present invention will be described more specifically with reference to examples and comparative examples.

[Example 1 and Comparative Examples 1-14]
A thermoelectric conversion device having the shape shown in FIG. 1 was prepared by the following procedure. Ceramic base material manufactured by Kurosaki Harima as base material, Ca ₉ Co ₁₂ O ₂₈ particles (powder) as p-type metal oxide semiconductor particles, and aluminum-doped zinc oxide particles manufactured by Hakusui Tech Co. as n-type metal oxide semiconductor particles. Using. Ca ₉ Co ₁₂ O ₂₈ particles were synthesized by a solid phase reaction method using Co ₃ O ₄ and CaCO ₃ as starting materials.

Ca ₉ Co ₁₂ O ₂₈ particles were dispersed in pure water to form a slurry, and a film was formed on the substrate surface by a high-speed flame spraying method. Note that thermal spraying was performed through a mask so as to obtain a desired shape. After film formation, baking was performed at 920 ° C. to obtain a p-type metal oxide semiconductor element. The frame temperature was about 2100 to 2600 ° C.

Next, aluminum-doped zinc oxide particles were dispersed in pure water to form a slurry, and a film was formed on the substrate surface by a high-speed flame spraying method to obtain an n-type metal oxide semiconductor element. Note that thermal spraying was performed through a mask so as to obtain a desired shape. In this way, a thermoelectric conversion device having the shape shown in FIG. 1 was obtained. In addition, the thermal spraying conditions of the aluminum-doped zinc oxide particles were changed as shown in Table 1 (other conditions were not changed), and the thermoelectric conversion devices of Examples and Comparative Examples were obtained.

The film thickness (μm) and porosity (%) of the n-type metal oxide semiconductor element in each obtained thermoelectric conversion device, and the power generation amount (10 ⁻⁹ W) of the thermoelectric conversion device were measured by the following methods. The measurement results are shown in Table 1.

(Film thickness and porosity)
After the film (n-type metal oxide semiconductor element) is reinforced by vacuum impregnation with an epoxy resin, it is cut and polished, and then the cut surface is observed and image analysis is performed using a laser microscope (manufactured by Keyence Corporation). Film thickness and porosity were determined.

(Electric-generating capacity)
In the thermoelectric conversion device, the surface that is one end side of each metal oxide semiconductor element (the surface below the base material 11 in FIG. 1A) is brought into contact with the heater to be the other end side of each metal oxide semiconductor element. The surface (the surface on the upper side of the substrate 11 in FIG. 1A) was brought into contact with the coolant. The heater was controlled at 800 ° C., the coolant was controlled at 150 ° C., and the power generation amount between the two lead wires was measured using a circuit tester at a temperature difference of 650 ° C.

As shown in Table 1, by increasing the spraying temperature, a thick film can be obtained, and the power generation tends to increase. However, if the sprayed particles (aluminum-doped zinc oxide particles) are overheated by slowing the spraying speed or increasing the spraying distance, the particles will evaporate in the frame and adhere to the substrate. It can be seen that the rate and the denseness of the resulting film (low porosity) are reduced. In addition, it can be seen that the high power generation amount has a low porosity of the film (n-type metal oxide semiconductor element), that is, a dense film. This is considered to be because the output factor P of the thermoelectric conversion material is expressed by P = S ² × σ (S: Seebeck coefficient, σ: electrical conductivity). That is, it is considered that by increasing the density of the element, the electrical conductivity (σ) increases and the power generation performance increases.

The thermoelectric conversion device according to the present invention can be used as a thermoelectric power generation device that uses waste heat or the like of a factory or an incineration plant, and can also be used as a cooling device that converts electricity into heat.

10: thermoelectric conversion device, 11: base material, 12a to 12c: p-type metal oxide semiconductor element, 13a to 13c: n-type metal oxide semiconductor element, 14: solder, 15: lead wire, 16: solder, 17: Lead wire, 20: thermoelectric conversion device, 22a to 22c: p-type metal oxide semiconductor device, 23a to 23c: n-type metal oxide semiconductor device, 24: electrode film, 25: solder, 26: lead wire, 27: solder , 28: Lead wire

Claims (8)

In a thermoelectric conversion device comprising a base material, and a p-type metal oxide semiconductor element and an n-type metal oxide semiconductor element that are disposed on the surface of the base material and connected in series,
The p-type metal oxide semiconductor element and the n-type metal oxide semiconductor element are film-like,
The n-type metal oxide semiconductor element is formed by thermal spraying, and the porosity of the n-type metal oxide semiconductor element is 5% or less. In the thermoelectric conversion device according to claim 1,
A thermoelectric conversion device, wherein the p-type metal oxide semiconductor element is formed by thermal spraying. In the thermoelectric conversion device according to claim 1 or 2,
The n-type metal oxide semiconductor element includes aluminum-doped zinc oxide. In the thermoelectric conversion apparatus of any one of Claims 1-3,
The p-type metal oxide semiconductor element includes Ca ₉ Co ₁₂ O ₂₈ . In the thermoelectric conversion apparatus of any one of Claims 1-4,
The thermoelectric conversion device, wherein the substrate is made of ceramics. In the thermoelectric conversion apparatus of any one of Claims 1-5,
The thermoelectric conversion device, wherein the p-type metal oxide semiconductor element and the n-type metal oxide semiconductor element are directly connected. In the thermoelectric conversion apparatus of any one of Claims 1-5,
An electrode film connecting the p-type metal oxide semiconductor element and the n-type metal oxide semiconductor element;
A thermoelectric conversion device, wherein the electrode film is formed by thermal spraying. In a method of manufacturing a thermoelectric conversion device comprising a base material, and a p-type metal oxide semiconductor element and an n-type metal oxide semiconductor element that are arranged on the surface of the base material and connected in series,
Forming the n-type metal oxide semiconductor element in a film shape on the surface of the base material by spraying aluminum-doped zinc oxide particles;
A method for manufacturing a thermoelectric conversion device, wherein a spraying temperature in the spraying is 2400 ° C. or more and 2800 ° C. or less, a spraying speed is 1800 m / s or more and 2000 m / s or less, and a spraying distance is 90 mm or more and 110 mm or less.

Images