Thermoelectric conversion module

Abstract

To provide a thermoelectric conversion module that improves heat transfer efficiency by efficiently transferring heat applied from the outside and obtains high electromotive force.SOLUTION: A thermoelectric conversion module includes a support, and a thermoelectric element layer in which P-type thermoelectric elements and N-type thermoelectric elements formed on a support are alternately arranged, and adjacent P-type thermoelectric elements and N-type thermoelectric elements are electrically arranged such that electrons move in the direction of the arrangement, and the thermoelectric element layer is made of a coating film, and the thickness difference tdif in the cross section of at least one of the P-type thermoelectric element and the N-type thermoelectric element along the direction perpendicular to the direction of the arrangement is 50 um or less.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a thermoelectric conversion module, and more particularly to a flexible thermoelectric conversion module. [Background technology]

[0002] Thermoelectric power generation and Peltier cooling are well-known energy conversion technologies that utilize thermoelectric conversion. Thermoelectric power generation utilizes the Seebeck effect to convert thermal energy into electrical energy. This technology does not require significant costs to operate the thermoelectric conversion elements required for thermoelectric conversion, and has therefore attracted considerable attention as an energy-saving technology that can recover unused waste heat energy generated from fossil fuels used in buildings, factories, and other facilities as electrical energy. Peltier cooling, in contrast to thermoelectric power generation, utilizes the Peltier effect to convert electrical energy into thermal energy. This technology is used, for example, in wine coolers and portable mini-refrigerators. This technology is also used as a means of cooling the CPUs used in computers and as a means of temperature control for components and devices that require precise temperature control (e.g., semiconductor laser oscillators for optical communications).

[0003] For example, Patent Document 1 discloses a thermoelectric module (a so-called π-type thermoelectric module) that is provided with a support substrate and a plurality of thermoelectric elements arranged on the support substrate, the thermoelectric elements being arranged in pairs, and that is composed of N-type thermoelectric elements and P-type thermoelectric elements made of a sintered body, and that the difference in height between the thermoelectric element with the greatest height and the thermoelectric element with the smallest height (height difference between the thermoelectric elements) is 20 μm or less, with the aim of improving thermoelectric performance, yield, reliability, and productivity.

[0004] Furthermore, for example, Patent Document 2 discloses a thermoelectric conversion element (a so-called π-type thermoelectric conversion element) that includes a plurality of thermoelectric conversion elements made of a thermoelectric conversion material joined to a first electrode layer and a second electrode layer by a joining material, with the aim of suppressing the force that the joining material reservoir presses the thermoelectric conversion elements apart and ensuring a conductive cross-sectional area between the thermoelectric conversion elements, and in which the difference between the maximum and minimum heights of the plurality of thermoelectric conversion elements (heights between the thermoelectric elements) is set to 0.02 millimeters or less.

[0005] Meanwhile, thermoelectric conversion elements known as in-plane types have also been proposed. In-plane type thermoelectric conversion elements are thermoelectric conversion elements configured to generate a temperature difference in the plane direction of the thermoelectric element layer and convert thermal energy into electrical energy. In-plane type thermoelectric conversion elements can expand the length over which the temperature difference occurs in the plane direction, so they can generate thermoelectric power efficiently even with a thin thermoelectric conversion layer. Furthermore, by making the thermoelectric conversion layer thin, the entire element can be made thin and flexible. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-34605 [Patent Document 2] Japanese Patent Application Publication No. 2006-303017 Summary of the Invention [Problem to be solved by the invention]

[0007] In recent years, as thermoelectric conversion elements have become more widespread, there has been a demand for their use in a variety of environments. In particular, in-plane type thermoelectric conversion elements are generally thin, so their use environments are expanding further, and there is a demand for them to be usable in a variety of environments. However, in terms of increasing the electromotive force, there is still room for improvement in the thermoelectric conversion module having the in-plane type thermoelectric conversion element.

[0008] In view of the above problems, an object of the present invention is to provide a thermoelectric conversion module that can efficiently transfer heat applied from the outside, thereby improving heat transfer efficiency and generating a high electromotive force. [Means for solving the problem]

[0009] As a result of extensive research into solving the above problems, the present inventors have found that in an in-plane type thermoelectric conversion element, the difference in thickness t within the thermoelectric element is not the difference in thickness between elements. dif , especially, the gauge element thickness t of the P-type thermoelectric element and the N-type thermoelectric element ga The thickness difference t within the thermoelectric element with the larger dif The present inventors have found that the above problems can be solved by adjusting the amount of hydroxybenzoates to fall within a predetermined range, and have completed the present invention. That is, the present invention provides the following [1] to [4]. [1] A thermoelectric element layer comprising a support, and P-type thermoelectric elements and N-type thermoelectric elements formed on the support and arranged alternately, with adjacent P-type thermoelectric elements and N-type thermoelectric elements electrically connected so that electrons move in the direction of the arrangement, wherein the thermoelectric element layer is made of a coating film, and a thickness difference t defined by the following (1) to (4) in a cross section of at least one of the P-type thermoelectric elements and the N-type thermoelectric elements along a direction perpendicular to the direction of the arrangement: dif However, this thermoelectric conversion module is less than 50um. (1) The thickness profile of the thermoelectric element in the cross section is measured using a stylus surface profiler. (2) From the measured thickness profile, the average thickness of the central portion of the thermoelectric element excluding both ends is calculated, and the calculated average thickness is defined as the average element thickness t av Here, when the length of the boundary line between the thermoelectric element and the support in the cross section is L, and a line segment of length 2 / 3L is defined as a central line segment, excluding a line segment extending from one end of the boundary line inward to 1 / 6L and a line segment from the other end of the boundary line inward to 1 / 6L from the boundary line of length L, the central portion refers to a region of the thermoelectric element sandwiched between line segments extending from both ends of the central line segment in a direction perpendicular to the main surface of the support. (3) From the measured thickness profile, the maximum value of the thickness of the thermoelectric element is detected, and the detected maximum value of the thickness is referred to as the maximum thickness t max Let's say. (4) The thickness difference t dif The maximum thickness t max and the average thickness of the element t av The difference between (t dif =t max -t av ) [2] A thermoelectric element layer comprising a support, and P-type thermoelectric elements and N-type thermoelectric elements formed on the support and arranged alternately, with adjacent P-type thermoelectric elements and N-type thermoelectric elements electrically connected so that electrons move in the direction of the arrangement, wherein the thermoelectric element layer is made of a thermoelectric semiconductor composition containing thermoelectric semiconductor particles and a resin, and wherein at least one of the P-type thermoelectric elements and the N-type thermoelectric elements has a thickness difference t defined by the following (1) to (4) in a cross section taken along a direction perpendicular to the direction of the arrangement: dif However, this thermoelectric conversion module is less than 50um. (1) The thickness profile of the thermoelectric element in the cross section is measured using a stylus surface profiler. (2) From the measured thickness profile, the average thickness of the central portion of the thermoelectric element excluding both ends is calculated, and the calculated average thickness is defined as the average element thickness t av Here, when the length of the boundary line between the thermoelectric element and the support in the cross section is L, and a line segment of length 2 / 3L is defined as a central line segment, excluding a line segment extending from one end of the boundary line inward to 1 / 6L and a line segment from the other end of the boundary line inward to 1 / 6L from the boundary line of length L, the central portion refers to a region of the thermoelectric element sandwiched between line segments extending from both ends of the central line segment in a direction perpendicular to the main surface of the support. (3) From the measured thickness profile, the maximum value of the thickness of the thermoelectric element is detected, and the detected maximum value of the thickness is referred to as the maximum thickness t max Let's say. (4) The thickness difference t dif The maximum thickness t max and the average thickness of the element t av The difference between (tdif =t max -t av ) [3] The gauge element thickness t of the P-type thermoelectric element ga and the gauge element thickness t of the N-type thermoelectric element ga and the thickness of the gauge element of the P-type thermoelectric element and the N-type thermoelectric element is t ga The thickness difference t of the thermoelectric element with the larger dif The thermoelectric conversion module according to the above [1] or [2], wherein the thickness is 50 μm or less. [4] The gauge element thickness t of the P-type thermoelectric element ga and the gauge element thickness t of the N-type thermoelectric element ga and the thickness difference t dif The thermoelectric conversion module according to the above [1] or [2], wherein the thickness is 50 μm or less. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a thermoelectric conversion module that can efficiently transfer heat applied from the outside, thereby improving heat transfer efficiency and generating a high electromotive force. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a partial cross-sectional view showing the configuration of a thermoelectric conversion module according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic plan view of a support on which electrodes are provided in a predetermined arrangement pattern. [Figure 3] FIG. 2 is a plan view showing an arrangement pattern of P-type thermoelectric elements and N-type thermoelectric elements provided on one main surface side of a support body having electrodes. [Figure 4] FIG. 2 is a plan view showing an arrangement pattern of a first high thermal conductivity layer provided on the main surface side of a support body including P-type thermoelectric elements and N-type thermoelectric elements. [Figure 5] 3. FIG. 4 is a partial cross-sectional view of the thermoelectric conversion module taken along the line indicated by the reference symbol III-III in FIG. [Figure 6A]FIG. 1 is a diagram for explaining an example of a process for forming a thermoelectric element layer (part 1). [Figure 6B] FIG. 10 is a diagram for explaining an example of a process for forming a thermoelectric element layer (part 2). [Figure 6C] FIG. 6C is a perspective view for explaining the printing plate in FIGS. 6A and 6B. [Figure 7A] FIG. 1 is a diagram illustrating the printing plate for forming N-type thermoelectric elements used in Comparative Examples 2 to 4. [Figure 7B] FIG. 7B is a perspective view illustrating the printing plate for forming N-type thermoelectric elements in FIG. 7A. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention (hereinafter, sometimes referred to as "the present embodiment") will be described. In this specification, "the thickness of A is different from the thickness of B" means that the thickness of one of A and B is 0.900 times or less or 1.111 times or more the thickness of the other. In addition, in this specification, "the thickness of A and the thickness of B are equal" means that the thickness of one of A and B is more than 0.900 times but less than 1.111 times the thickness of the other. In addition, in this specification, "the thickness of A is greater than the thickness of B" means that the thickness of A is 1.111 times the thickness of B or more. Furthermore, in this specification, "the thickness of A is smaller than the thickness of B" means that the thickness of A is 0.900 times the thickness of B or less.

[0013] [Thermoelectric conversion module configuration] A thermoelectric conversion module according to an embodiment of the present invention comprises a support body, a thermoelectric element layer in which P-type thermoelectric elements and N-type thermoelectric elements formed on the support body are arranged alternately and adjacent P-type and N-type thermoelectric elements are electrically connected so that electrons move in the direction of the arrangement, and, if necessary, further comprises electrodes that electrically connect the P-type and N-type thermoelectric elements that constitute the thermoelectric element layer, a coating layer that covers the surface of the thermoelectric element layer, and a high thermal conductivity layer provided on the surface of the coating layer opposite the thermoelectric element layer. Here, the thermoelectric element layer satisfies at least one of the following conditions: (1) it is made of a coating film; and (2) it is made of a thermoelectric semiconductor composition containing thermoelectric semiconductor particles and a resin, and is formed by coating such as screen printing.

[0014] Hereinafter, the configuration of a thermoelectric conversion module according to an embodiment of the present invention will be described with reference to the drawings. The drawings are all schematic and may be exaggerated to facilitate understanding. FIG. 1 is a partial cross-sectional view showing the configuration of a thermoelectric conversion module according to an embodiment of the present invention. This is a partial cross-sectional view of a thermoelectric conversion module 1A near the center thereof, taken along the line IV-IV in FIG. 4 (described later). As shown in FIG. 1, the thermoelectric conversion module 1A includes a support 2 on which electrodes 3 having a predetermined pattern are formed. The support 2 also includes a thermoelectric element layer 6 formed on one main surface (the main surface on the electrode 3 side) of the support 2, the thermoelectric element layer 6 including P-type thermoelectric elements 5 and N-type thermoelectric elements 4, a first coating layer 81 stacked on the surface of the thermoelectric element layer 6 opposite the support 2, a first high thermal conductivity layer 91 stacked on the surface of the first coating layer 81 opposite the thermoelectric element layer 6, a second coating layer 82 stacked on the other main surface of the support 2, and a second high thermal conductivity layer 92 stacked on the surface of the second coating layer 82 opposite the thermoelectric element layer 6. In this embodiment, the support 2 is a substrate that remains when the thermoelectric conversion module is mounted. In the following description, the first coating layer and the second coating layer may be collectively referred to as the "coating layer." Furthermore, the first high thermal conductivity layer and the second high thermal conductivity layer may be collectively referred to as the "high thermal conductivity layer."

[0015] Fig. 2 is a schematic plan view of a support body on which electrodes are arranged in a predetermined arrangement pattern. As shown in Fig. 2, the electrode 3 arranged on one main surface of the rectangular support body 2 has a plurality of first electrode portions 3a (connecting electrode portions) for electrically connecting each of the rows of thermoelectric element layers 6 arranged in a plurality of rows, two second electrode portions 3b (electromotive force output electrode portions) for external connection that serve as terminals for extracting thermoelectric power from the thermoelectric element layer 6 or applying voltage to the thermoelectric element layer 6, and a large number of third electrode portions 3c for electrically connecting the P-type thermoelectric elements 5 and N-type thermoelectric elements 4 arranged alternately in rows. Each of the electrode portions 3a to 3c is arranged in an island-like manner.

[0016] FIG. 3 is a plan view showing an arrangement pattern of P-type thermoelectric elements and N-type thermoelectric elements provided on one main surface of a support body having electrodes. As shown in FIG. 3 , multiple rows of thermoelectric element layers 6, each consisting of a P-type thermoelectric element 5 and an N-type thermoelectric element 4, are arranged side by side. In each row of thermoelectric element layers 6, a third electrode portion 3c is arranged so as to overlap the junction of adjacent thermoelectric elements 4, 5, excluding the end portions. A first electrode portion 3a is arranged so as to contact one end of each row of thermoelectric element layers 6. The first electrode portion 3a electrically connects the P-type thermoelectric element 5 or N-type thermoelectric element 4 at one end of a row of a certain thermoelectric element layer 6 to the N-type thermoelectric element 4 or P-type thermoelectric element 5 at one end of a row of the next thermoelectric element layer 6. Similarly, the other end of each row of thermoelectric element layers 6 is electrically connected to the end of the row of the next thermoelectric element layer 6 by the first electrode portion 3a. The thermoelectric elements 4, 5 at one end of the rows of thermoelectric element layers 6 located at both ends are each connected to the second electrode portion 3b. In this way, the P-type thermoelectric elements 5 and N-type thermoelectric elements 4 arranged two-dimensionally on the support 2 are electrically connected in series by each electrode portion 3a to 3c, and as a result, a current path is formed that snakes on the main surface of the support 2.

[0017] The shapes of the P-type thermoelectric elements 5 and the N-type thermoelectric elements 4 are not particularly limited, but a rectangular shape is preferred because it allows for easy alternating arrangement of the P-type thermoelectric elements 5 and the N-type thermoelectric elements 4 while electrically connecting adjacent thermoelectric element layers 6. The rectangular thermoelectric elements 4, 5 preferably have short sides in the direction Y of the arrangement of the thermoelectric elements 4, 5 and long sides in the direction Z perpendicular to the direction Y of the arrangement of the thermoelectric elements 4, 5. This shape of the thermoelectric elements 4, 5 increases the number of repetitions of the P-type thermoelectric elements 5 and the N-type thermoelectric elements 4 per area, while also increasing the width of the strip-like rows of the arranged P-type thermoelectric elements 5 and the N-type thermoelectric elements 4, and thus improving thermoelectric efficiency. The length of the short sides of the rectangular thermoelectric elements 4, 5 is preferably 0.3 to 3 mm, more preferably 0.5 to 2 mm. The length of the long sides is preferably 2 to 20 mm, more preferably 4 to 15 mm. Here, the "direction Z perpendicular to the direction Y of arrangement of the thermoelectric elements 4 and 5" refers to a direction perpendicular to the direction Y of arrangement of the thermoelectric elements 4 and 5 in a plan view according to the plan view of Figure 3, and is usually the application direction Z when applying a thermoelectric semiconductor composition (coating liquid) onto a support in the "step of forming a thermoelectric element layer 6" described below.

[0018] FIG. 4 is a diagram showing an arrangement pattern of a first high thermal conductivity layer provided on the main surface side of a support body including P-type thermoelectric elements and N-type thermoelectric elements. In FIG. 4, the first covering layer 81 is omitted for ease of understanding. As shown in FIG. 4 , the first highly thermally conductive layer 91 is formed in a plurality of stripes that intersect with the rows of the thermoelectric element layers 6. The first highly thermally conductive layer 91 covers every other junction between the P-type thermoelectric element 5 and the N-type thermoelectric element 4. The second highly thermally conductive layer 92 is also formed in a plurality of stripes that intersect with the rows of the thermoelectric element layers 6. Although not shown in FIG. 4 , the second highly thermally conductive layer 92 is disposed at a position that corresponds to the junction between the thermoelectric elements 4, 5 that is not covered by the first highly thermally conductive layer 91 when viewed from a direction perpendicular to the main surface of the support 2. As a result, in a vertical cross section in the arrangement direction of the striped highly thermally conductive layers 91, 92, the first highly thermally conductive layer 91 and the second highly thermally conductive layer 92 are disposed alternately with respect to the thermoelectric element layers 6. In addition, in the direction perpendicular to the main surface of the support 2, the widthwise end of the first high thermal conductivity layer 91 and the widthwise end of the second high thermal conductivity layer 92 may coincide, overlap, or be separated.

[0019] 2 and 3, the number of third electrode units 3c is 42 (=7 units × 6 rows), the number of first electrode units 3a is 5, and the number of P-type thermoelectric elements 5 and N-type thermoelectric elements 4 is 24 (=4 units × 6 rows). Also, in FIG. 4, the number of first high thermal conductive layers 91 is four, but these numbers can be changed as appropriate. The size and position of each electrode unit 3 can also be changed as appropriate. Also, in FIG. 2, the two second electrode units 3b are arranged so as to contact one side of the support body 2, but this is not limited thereto, and the two second electrode units 3b can be arranged so as to contact different sides of the support body 2 depending on the application field and usage environment of the thermoelectric conversion module, etc.

[0020] In the above embodiment, no layer is provided in the region on the coating layer where the high thermal conductivity layer is not provided, but a member such as a low thermal conductivity layer may be provided. In this case, the coating layer can function not only as a high thermal conductivity layer but also as a fixing material for the member such as the low thermal conductivity layer. From the viewpoint of improving the thermoelectric conversion performance of the thermoelectric conversion module, it is preferable that the thermal conductivity of the low thermal conductivity layer is lower than that of the high thermal conductivity layer. In addition, when no layer is provided in the region of the coating layer where the high thermal conductivity layer is not provided, as in the above embodiment, and the coating layer is exposed, the air is present instead of the low thermal conductivity layer. Since the thermal conductivity of the air is very low, for example, about 0.02 W / (m·K), the thermoelectric conversion performance can be equal to or better than that when a low thermal conductivity layer is provided.

[0021] FIG. 5 is a partial cross-sectional view of the thermoelectric conversion module taken along the line indicated by the reference symbol III-III in FIG. The cross section 50 shown in Figure 5 is a cross section of the support 2 and the thermoelectric elements 4 and 5 along a direction (coating direction Z in Figure 3) perpendicular to the arrangement direction of the thermoelectric elements 4 and 5 (i.e., the direction of electron movement in the thermoelectric element layer 6). The line indicated by the symbol III-III in Fig. 3 is a line that runs along the center of the length in the direction Y of the second thermoelectric element 4, 5 from the right in Fig. 3. In other words, the cross section of the thermoelectric elements 4, 5 in Fig. 5 is a cross section when cut in the Z direction so as to pass through the center of the length of the thermoelectric elements 4, 5 in the direction Y (Fig. 3).

[0022] The gauge element thickness t of the P-type thermoelectric element 5 and the N-type thermoelectric element 4 ga When the thickness difference t dif It is preferable to reduce the gauge element thickness t ga When the thickness difference t between the P-type thermoelectric element 5 and the N-type thermoelectric element 4 is equal to 1 / 2, there is no preferential heat transfer as described above. dif It is also preferable to make small. Here, the gauge element thickness t ga is the thickness of the thermoelectric element, which is obtained by measuring the thickness of the thermoelectric element at one point with a thickness gauge and subtracting the thickness of the support from the measured thickness. Here, the gauge element thickness t gaThe calculation of is carried out as follows, for example, as shown in the examples described later. First, the gauge element thickness t ga The thickness measurement is performed on three thermoelectric element layer-attached supports, and the average of the first average values ​​for the three thermoelectric element layer-attached supports is calculated as the second average value. The second average value is used as the gauge element thickness t ga Let's say. The gauge element thickness t ga The thickness gauge used for the measurement is not particularly limited, and examples thereof include commercially available products such as Digital Indicator PC-465J manufactured by Teclock Corporation.

[0023] Gauge element thickness t of P-type thermoelectric element and N-type thermoelectric element ga There is no particular limitation on the value of t , and as mentioned above, both may have the same thickness or different thicknesses. From the viewpoint of flexibility and material cost, the gauge element thickness t ga The thickness is preferably 0.1 to 300 μm, and more preferably 1 to 200 μm.

[0024] When the thermoelectric element layer is formed by the screen printing method as described below, the thermoelectric element formed later (the N-type thermoelectric element 4 in FIGS. 6A and 6B) usually has a larger gauge element thickness than the thermoelectric element formed earlier (the P-type thermoelectric element 5 in FIGS. 6A and 6B). ga becomes larger. The formation of the thermoelectric element layer by screen printing will be described below. First, as shown in FIG. 6A , a printing plate 60 is placed above the support 2, and a thermoelectric semiconductor composition (coating liquid) is applied to the support 2 through openings (holes) 61 in the printing plate 60 and dried, thereby forming one of the P-type thermoelectric elements 5 and the N-type thermoelectric elements 4 (P-type thermoelectric element 5 in FIG. 6A ) on the support 2. Next, as shown in FIG. 6B , the printing plate 60 is placed above the support 2 so as not to crush the thermoelectric element already formed on the support 2 (P-type thermoelectric element 5 in FIG. 6B ). The thermoelectric semiconductor composition (coating liquid) is applied to the support 2 through openings (holes) 61 in the printing plate 60 and dried, thereby forming the other of the P-type thermoelectric elements 5 and the N-type thermoelectric elements 4 (N-type thermoelectric element 4 in FIG. 6B ) on the support 2. Thereafter, an annealing treatment is performed. Here, the direction in which the thermoelectric semiconductor composition is applied (application direction Z) is preferably perpendicular to the arrangement direction Y of the thermoelectric elements 4 and 5. As described above, when the thermoelectric elements are rectangular, it is preferable that the thermoelectric elements have their long sides in a direction Z perpendicular to the direction Y in which the thermoelectric elements 4, 5 are arranged. In this case, if the thermoelectric semiconductor composition is applied in the direction Y in which the thermoelectric elements 4, 5 are arranged, the squeegee may easily get caught on the long sides of the rectangular pattern on the printing plate, which may cause problems with application. By setting the application direction Z to the direction Z perpendicular to the long sides of the thermoelectric elements 4, 5, i.e., the direction Y in which the thermoelectric elements 4, 5 are arranged, this problem can be avoided and application can be made easier.

[0025] Hereafter, the thickness difference t dif The wording required to define this will be explained using Figure 5. In Figure 5, the interface between the thermoelectric elements 4, 5 and the support 2 is defined as boundary line 51, and the length of boundary line 51 is defined as L. Furthermore, a line segment 52 extending from one end P of boundary line 51 to 1 / 6L inward and a line segment 53 extending from the other end Q of boundary line 51 to 1 / 6L inward are excluded from boundary line 51 of length L, and a line segment 54 with a length of 2 / 3L is defined as central line segment 54. Furthermore, a region of thermoelectric elements 4, 5 sandwiched between line segments 55, 56 extending from both ends 54a, 54b of central line segment 54 in the direction perpendicular to the support main surface 2a is defined as central region 57. Furthermore, the region from line segment 55 to one end P is defined as end 58, and the region from line segment 56 to one end Q is defined as end 59.

[0026] Hereinafter, the thickness difference t defined in the present invention dif The calculation of is explained with reference to FIG. (1) First, the thickness profile of the thermoelectric elements 4 and 5 in the cross section of FIG. 5 is measured using a stylus surface profilometer. Here, the thickness profile is measured over the entire cross-section (ie, the central portion 57 and both end portions 58, 59). The stylus surface profilometer used to measure the thickness profile is not particularly limited, and examples thereof include commercially available products such as Dectak150 manufactured by ULVAC, Inc. The frequency of thickness measurement in the thickness profile is not particularly limited, but is preferably greater than every 1 μm (every less than 1 μm) in order to obtain a more accurate thickness profile. The thickness profile is measured, for example, as shown in the examples described later. First, thickness profile measurement is performed on five thermoelectric elements randomly selected from the plurality of thermoelectric elements on one substrate with a thermoelectric element layer, and this thickness profile measurement is performed on three substrates with a thermoelectric element layer. In other words, 15 thickness profiles are obtained. In this specification, a "substrate with a thermoelectric element layer" refers to a unit including a substrate as a support and a thermoelectric element layer, and corresponds to the "thermoelectric conversion module" of the present invention. (2) Next, from the measured thickness profile, the average thickness of the central portion 57 of the thermoelectric elements 4 and 5, excluding both end portions 58 and 59, is calculated for each thickness profile, and the calculated average thickness is defined as the element average thickness t av Let's say. (3) Furthermore, from the measured thickness profile, the maximum thickness values ​​of the thermoelectric elements 4 and 5 are detected for each thickness profile, and the detected maximum thickness values ​​are designated as maximum thickness t max Let's say. (4) Finally, the maximum thickness t max and the average element thickness t av The difference between (t dif =t max -t av) for each thickness profile, and first, the maximum thickness t max and the average element thickness t av The average of the differences between the thickness profiles (i.e., the average of the five differences obtained from the five thickness profiles) was calculated and set as the first average value, and further, the average of the three first average values ​​for the three thermoelectric element layer-attached substrates (i.e., the average of the 15 differences obtained from the 15 thickness profiles) was calculated and set as the second average value, and the second average value was used as the thickness difference t dif Let's say. Here, the thickness profiles were measured for three substrates with thermoelectric element layers, but if only two substrates with thermoelectric element layers are obtained, the thickness profiles for the two substrates with thermoelectric element layers are measured and the second average value is calculated in the same manner as above, and if only one substrate with thermoelectric element layers is obtained, the first average value is used as the second average value.

[0027] In the thermoelectric element layer of the thermoelectric conversion module of the present invention, i.e., in-plane type thermoelectric element layer in which P-type thermoelectric elements and N-type thermoelectric elements are alternately formed by coating such as screen printing, the thickness difference t within at least one of the P-type thermoelectric elements and the N-type thermoelectric elements is dif By making the thickness 50 μm or less, heat applied from the outside can be efficiently transferred to the thermoelectric element layer, improving the heat transfer efficiency between the thermoelectric element layer and the outside of the thermoelectric module, and increasing the electromotive force.

[0028] Thickness difference t dif There is no particular limitation on the thickness as long as it is 50 μm or less, but it is preferably 40 μm or less, more preferably 30 μm or less, and even more preferably 20 μm or less. Here, the thickness difference t dif In order to further reduce the thickness of the thermoelectric element, the thickness difference t that occurred during formation may be reduced by pressing or grinding. dif may be corrected (i.e., the maximum thickness t max The viscosity of the thermoelectric semiconductor composition (coating liquid) is adjusted to achieve the maximum thickness t max may be made smaller. In addition, from the viewpoint of further improving the electromotive force, the gauge element thickness t ga and the average element thickness t av It is preferable to increase the absolute value of

[0029] The thermoelectric element layer in the thermoelectric conversion module of the present invention is formed by coating. When coating is performed by a screen printing method using a printing plate having a rectangular opening (hole), as in the examples described later, the cross section of the thermoelectric element usually has a maximum thickness t at the end 59 on the coating end point side, as shown in FIG. max This tendency is remarkable when the length of the rectangular opening in the coating direction is long, for example, 2 mm or more.

[0030] Each component of the thermoelectric conversion module 1A will be described in detail below. <Support> The support supports at least the thermoelectric element layer. The support may be a support for temporary fixation that is removed after the thermoelectric element layer is applied to another member, or may be a substrate that ultimately remains in the thermoelectric conversion module. The support may support electrodes and the like in addition to the thermoelectric element layer, and the substrate may further support a coating layer, a high thermal conductivity layer, and the like. As the support, a plastic film is preferably used, which does not affect the decrease in the electrical conductivity or the increase in the thermal conductivity of the thermoelectric element layer, is easily removable even when used for temporary fixation, and has excellent flexibility. When the support is used as a substrate, polyimide film, polyamide film, polyetherimide film, polyaramid film, or polyamideimide film is preferred because it can maintain the performance of the thermoelectric element layer without thermal deformation even when a thin film made of the thermoelectric semiconductor composition described below is annealed, and has high heat resistance and dimensional stability. Furthermore, polyimide film is particularly preferred because of its high versatility. The substrate may have an adhesive layer for bonding to the thermoelectric element layer on the surface facing the thermoelectric element layer.

[0031] The thickness of the plastic film used as the support is preferably from 1 to 1,000 μm, more preferably from 10 to 500 μm, and even more preferably from 20 to 100 μm, from the viewpoints of flexibility, heat resistance, and dimensional stability. The film preferably has a decomposition temperature of 300° C. or higher.

[0032] By using a plastic film as the substrate and forming other layers thinly, the entire thermoelectric conversion module can be made into a thin, flexible sheet.

[0033] <Thermoelectric element layer> In the thermoelectric element layer, P-type thermoelectric elements and N-type thermoelectric elements are arranged alternately, and adjacent P-type and N-type thermoelectric elements are electrically connected so that electrons move in the direction of the arrangement. Here, adjacent P-type and N-type thermoelectric elements are preferably electrically connected at the side surfaces of the elements, for example, as shown in FIG. Furthermore, the thermoelectric element layer satisfies at least one of the following: (1) it is made of a coating film; and (2) it is made of a thermoelectric semiconductor composition containing thermoelectric semiconductor particles and a resin. The thermoelectric semiconductor composition preferably contains thermoelectric semiconductor particles, a resin, and one or both of an ionic liquid and an inorganic ionic compound.

[0034] (Thermoelectric semiconductor particles) The thermoelectric semiconductor particles used in the thermoelectric element layer are preferably prepared by pulverizing a thermoelectric semiconductor material to a predetermined size using a fine grinding device or the like.

[0035] As materials constituting the P-type thermoelectric element and the N-type thermoelectric element, there is no particular limitation as long as the material can generate a thermoelectromotive force by applying a temperature difference. For example, bismuth-tellurium-based thermoelectric semiconductor materials such as P-type bismuth telluride and N-type bismuth telluride; telluride-based thermoelectric semiconductor materials such as GeTe and PbTe; antimony-tellurium-based thermoelectric semiconductor materials; zinc-antimony-based thermoelectric semiconductor materials such as ZnSb, Zn3Sb2, and Zn4Sb3; silicon-germanium-based thermoelectric semiconductor materials such as SiGe; bismuth selenide-based thermoelectric semiconductor materials such as Bi2Se3; β-FeSi2, CrSi2, MnSi 1.73 , silicide-based thermoelectric semiconductor materials such as Mg2Si; oxide-based thermoelectric semiconductor materials; Heusler materials such as FeVAl, FeVAlSi, and FeVTiAl; sulfide-based thermoelectric semiconductor materials such as TiS2; skutterudite materials; and the like are used. These may be used alone or in combination of two or more. Among these, from the viewpoint of not containing rare metals with unstable supply due to geopolitical problems, silicide-based thermoelectric semiconductor materials are preferable, and from the viewpoint of facilitating the functioning of the thermoelectric conversion module in a high-temperature environment, skutterudite materials are preferable.

[0036] Also, from the viewpoint of high thermoelectric conversion performance in a low-temperature environment, the thermoelectric semiconductor material is preferably a bismuth-tellurium-based thermoelectric semiconductor material such as P-type bismuth telluride or N-type bismuth telluride. P-type bismuth telluride has holes as carriers and a positive value of the Seebeck coefficient. For example, Bi X Te3Sb 2-X represented by is preferably used. In this case, X is preferably 0 < X ≤ 0.8, more preferably 0.4 ≤ X ≤ 0.6. It is preferable that X is greater than 0 and less than or equal to 0.8 because the Seebeck coefficient and the electrical conductivity increase and the characteristics as a P-type thermoelectric conversion material are maintained. Also, N-type bismuth telluride has electrons as carriers and a negative value of the Seebeck coefficient. For example, Bi2Te 3-Y Se YIn this case, Y is preferably 0≦Y≦3 (when Y=0, it is Bi2Te3). When Y is 0 or more and 3 or less, the Seebeck coefficient and electrical conductivity become large, and the properties as an N-type thermoelectric conversion material are preferably maintained.

[0037] The amount of thermoelectric semiconductor particles in the thermoelectric semiconductor composition is preferably 30 to 99% by mass, more preferably 50 to 98% by mass, and even more preferably 70 to 97% by mass. When the amount of thermoelectric semiconductor particles is within the above range, the Seebeck coefficient (absolute value of the Peltier coefficient) is large, and the decrease in electrical conductivity is suppressed, with only the thermal conductivity decreasing, so that a film exhibiting high thermoelectric performance and having sufficient film strength and flexibility is obtained, which is preferable.

[0038] The average particle size of the thermoelectric semiconductor particles is preferably 10 nm to 200 μm, more preferably 10 nm to 30 μm, even more preferably 50 nm to 10 μm, and particularly preferably 1 to 6 μm. Within the above range, uniform dispersion is facilitated, and electrical conductivity can be increased. The method for pulverizing a thermoelectric semiconductor material to obtain thermoelectric semiconductor particles is not particularly limited, and the material may be pulverized to a predetermined size using a known fine pulverizing device such as a jet mill, ball mill, bead mill, colloid mill, conical mill, disk mill, edge mill, flour mill, hammer mill, pellet mill, Willy mill, or roller mill. The average particle size of the thermoelectric semiconductor particles was obtained by measurement using a laser diffraction particle size analyzer (Malvern, Mastersizer 3000) and was taken as the median value of the particle size distribution.

[0039] The thermoelectric semiconductor particles are preferably annealed (hereinafter, sometimes referred to as "annealing treatment A"). Annealing treatment A improves the crystallinity of the thermoelectric semiconductor particles and removes the surface oxide film of the thermoelectric semiconductor particles, thereby increasing the Seebeck coefficient (absolute value of the Peltier coefficient) of the thermoelectric conversion material and further improving the thermoelectric figure of merit. Annealing treatment A is not particularly limited, but is preferably performed before preparing the thermoelectric semiconductor composition in an inert gas atmosphere such as nitrogen or argon, a reducing gas atmosphere such as hydrogen, or a vacuum condition with a controlled gas flow rate, so as not to adversely affect the thermoelectric semiconductor particles. Annealing treatment A is more preferably performed in a mixed gas atmosphere of an inert gas and a reducing gas. The specific temperature conditions depend on the thermoelectric semiconductor particles used, but it is usually preferable to perform the treatment at a temperature below the melting point of the particles, at 100 to 1500°C, for several minutes to several tens of hours.

[0040] (resin) The resin contained in the thermoelectric element layer acts as a binder between the thermoelectric semiconductor particles to improve the printability and film strength of the thermoelectric conversion material. Although there are no particular limitations on the resin, it is preferable to use a resin that maintains its mechanical strength, thermal conductivity, and other physical properties as a resin when the thermoelectric semiconductor particles are crystallized by annealing a thin film made of the thermoelectric semiconductor composition. Examples of resins include polyamide resins, polyamideimide resins, polyimide resins, polyetherimide resins, polybenzoxazole resins, polybenzimidazole resins, epoxy resins, and copolymers having the chemical structures of these resins. The resins may be used alone or in combination of two or more. Among these, polyamide resins, polyamideimide resins, polyimide resins, and epoxy resins are preferred because they have high heat resistance and do not adversely affect the crystal growth of thermoelectric semiconductor particles in the thin film. Polyamide resins, polyamideimide resins, and polyimide resins are more preferred because they have superior heat resistance. When a polyimide film is used as the support, polyimide resins are more preferred because of their adhesion to the polyimide film. In this specification, polyimide resin collectively refers to polyimides and their precursors (e.g., polyamic acids).

[0041] The resin preferably has a decomposition temperature of 300° C. or higher. If the decomposition temperature is within the above range, the resin will not lose its function as a binder and the film strength of the thermoelectric conversion material can be maintained even when a thin film made of the thermoelectric semiconductor composition is annealed, as described below.

[0042] Furthermore, the resin preferably has a mass loss rate of 10% or less, more preferably 5% or less, and even more preferably 1% or less at 300°C as measured by thermogravimetry (TG). If the mass loss rate is within the above range, as will be described later, even when a thin film made of the thermoelectric semiconductor composition is annealed, the resin can maintain its function as a binder and maintain the film strength of the thermoelectric conversion material.

[0043] The amount of resin blended in the thermoelectric semiconductor composition is preferably 0.1 to 40 mass%, more preferably 0.5 to 20 mass%, and even more preferably 0.7 to 20 mass%. When the amount of resin blended is within the above range, a film that combines high thermoelectric performance with printability and film strength is easily obtained.

[0044] (ionic liquid) The ionic liquid contained in the thermoelectric element layer is a molten salt formed by combining a cation and anion, and is a salt that can exist in liquid form over a wide temperature range from -50 to less than 400°C. Ionic liquids are characterized by extremely low vapor pressure, nonvolatility, excellent thermal and electrochemical stability, low viscosity, and high ionic conductivity. As a conductive additive, they can effectively suppress a decrease in electrical conductivity between thermoelectric semiconductor particles. In addition, ionic liquids exhibit high polarity due to their aprotic ionic structure and excellent compatibility with resins, allowing them to achieve a uniform electrical conductivity in thermoelectric conversion materials.

[0045] The ionic liquid may be a known or commercially available one. For example, a nitrogen-containing cyclic cationic compound such as pyridinium, pyrimidinium, pyrazolium, pyrrolidinium, piperidinium, or imidazolium, or a derivative thereof; a tetraalkylammonium-based amine-based cation and a derivative thereof; a phosphine-based cation such as phosphonium, trialkylsulfonium, or tetraalkylphosphonium, or a derivative thereof; a lithium cation and a derivative thereof; or a mixture of a cation component and a Cl cation. - , Br - , I - , AlCl4 - , Al2Cl7 - , BF4 - , PF6 - , ClO4 - , NO3 - , CH3COO - , CF3COO - , CH3SO3 - , CF3SO3 - , (FSO2)2N - , (CF3SO2)2N - , (CF3SO2)3C - , AsF6 - , SbF6 - , NbF6 - , TaF6 - , F(HF) n - , (CN)2N - , C4F9SO3 - , (C2F5SO2)2N -, C3F7COO - , (CF3SO2)(CF3CO)N - and an anion component such as the above.

[0046] Among the above-mentioned ionic liquids, from the viewpoints of high-temperature stability, compatibility with thermoelectric semiconductor particles and resins, and suppression of a decrease in the electrical conductivity in the gaps between thermoelectric semiconductor particles, it is preferred that the cationic component of the ionic liquid contains at least one selected from pyridinium cations and derivatives thereof, and imidazolium cations and derivatives thereof.

[0047] Specific examples of ionic liquids in which the cationic component contains a pyridinium cation and its derivatives include 4-methyl-butylpyridinium chloride, 3-methyl-butylpyridinium chloride, 4-methyl-hexylpyridinium chloride, 3-methyl-hexylpyridinium chloride, 4-methyl-octylpyridinium chloride, 3-methyl-octylpyridinium chloride, 3,4-dimethyl-butylpyridinium chloride, 3,5-dimethyl-butylpyridinium chloride, 4-methyl-butylpyridinium tetrafluoroborate, 4-methyl-butylpyridinium hexafluorophosphate, 1-butylpyridinium bromide (N-butylpyridinium bromide), 1-butyl-4-methylpyridinium bromide, 1-butyl-4-methylpyridinium hexafluorophosphate, etc. These may be used alone or in combination of two or more. Among these, 1-butylpyridinium bromide, 1-butyl-4-methylpyridinium bromide, and 1-butyl-4-methylpyridinium hexafluorophosphate are preferred.

[0048] Specific examples of ionic liquids in which the cation component contains an imidazolium cation or a derivative thereof include [1-butyl-3-(2-hydroxyethyl)imidazolium bromide], [1-butyl-3-(2-hydroxyethyl)imidazolium tetrafluoroborate], 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium chloride, 1-hexyl-3-methylimidazolium chloride, 1-octyl-3-methylimidazolium chloride, 1-decyl-3-methylimidazolium chloride, and 1-decyl-3-methylimidazolium chloride. Examples of suitable imidazolium bromide include imidazolium bromide, 1-dodecyl-3-methylimidazolium chloride, 1-tetradecyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-hexyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-methyl-3-butylimidazolium methyl sulfate, and 1,3-dibutylimidazolium methyl sulfate. These may be used alone or in combination of two or more. Among these, 1-butyl-3-(2-hydroxyethyl)imidazolium bromide and 1-butyl-3-(2-hydroxyethyl)imidazolium tetrafluoroborate are preferred.

[0049] The above ionic liquid has an electrical conductivity of 10 -7 If the ionic conductivity is in the above range, the thermoelectric semiconductor material can effectively suppress a decrease in electrical conductivity between the thermoelectric semiconductor particles as a conductive additive.

[0050] The ionic liquid preferably has a decomposition temperature of 300° C. or higher. If the decomposition temperature is within the above range, the ionic liquid can maintain its effect as a conductive additive even when a thin film made of the thermoelectric semiconductor composition is annealed, as described below.

[0051] Furthermore, the ionic liquid preferably has a mass loss rate of 10% or less, more preferably 5% or less, and even more preferably 1% or less at 300°C as measured by thermogravimetry (TG). If the mass loss rate is within the above range, the ionic liquid can maintain its effectiveness as a conductive additive even when a thin film made of the thermoelectric semiconductor composition is annealed, as described below.

[0052] The amount of ionic liquid in the thermoelectric semiconductor composition is preferably 0.01 to 50 mass%, more preferably 0.5 to 30 mass%, and even more preferably 1.0 to 20 mass%. When the amount of ionic liquid is within the above range, a decrease in electrical conductivity is effectively suppressed, and a film with high thermoelectric performance is obtained.

[0053] (inorganic ionic compounds) The inorganic ionic compound contained in the thermoelectric element layer is a compound composed of at least cations and anions. The inorganic ionic compound exists in a solid state over a wide temperature range from 400 to 900°C and has characteristics such as high ionic conductivity, so it can act as a conductive additive to suppress a decrease in electrical conductivity between thermoelectric semiconductor particles.

[0054] As the cation constituting the inorganic ionic compound, a metal cation is used. Examples of metal cations include alkali metal cations, alkaline earth metal cations, typical metal cations and transition metal cations, with alkali metal cations and alkaline earth metal cations being more preferred. Examples of alkali metal cations include Li + , Na + , K. + , Rb + , Cs + and Fr + etc. Examples of alkaline earth metal cations include Mg 2+ , Ca 2+ , Sr 2+ and Ba 2+ etc.

[0055] Examples of the anion constituting the inorganic ionic compound include F - , Cl - , Br - , I - , O.H. - , C.N. - , NO3 - , NO2 - , ClO - , ClO2 - , ClO3 - , ClO4 - , CrO4 2- , HSO4 - , SCN - , BF4 - , PF6 - etc.

[0056] The inorganic ionic compound contained in the thermoelectric element layer may be a known or commercially available one. For example, a cationic component such as potassium cation, sodium cation, or lithium cation and a Cl - , AlCl4 - , Al2Cl7 - , ClO4 - Chloride ions such as Br - bromide ions, such as I - Iodide ions such as BF4 - , PF6 - Fluoride ions such as F(HF) n - Halide anions such as NO3 - , O.H. - , C.N. - and an anion component such as the above.

[0057] Among the inorganic ionic compounds described above, from the viewpoints of high-temperature stability, compatibility with thermoelectric semiconductor particles and resin, and suppression of a decrease in the electrical conductivity of the gaps between thermoelectric semiconductor particles, it is preferable that the cationic component of the inorganic ionic compound contains at least one selected from potassium, sodium, and lithium. Also, it is preferable that the anionic component of the inorganic ionic compound contains a halide anion, and Cl - , Br - , and I- It is more preferable that the composition contains at least one selected from the following:

[0058] Specific examples of inorganic ionic compounds whose cationic component contains potassium cations include KBr, KI, KCl, KF, KOH, and K2CO3. These may be used alone or in combination of two or more. Among these, KBr and KI are preferred. Specific examples of inorganic ionic compounds whose cationic component contains a sodium cation include NaBr, NaI, NaOH, NaF, and Na2CO3. These may be used alone or in combination of two or more. Among these, NaBr and NaI are preferred. Specific examples of inorganic ionic compounds whose cationic component contains lithium cations include LiF, LiOH, LiNO3, etc. These may be used alone or in combination of two or more. Among these, LiF and LiOH are preferred.

[0059] The above inorganic ionic compounds have an electrical conductivity of 10 -7 S / cm or more is preferable, and 10 -6 If the electrical conductivity is in the above range, the conductive additive can effectively suppress a decrease in electrical conductivity between thermoelectric semiconductor particles.

[0060] The inorganic ionic compound preferably has a decomposition temperature of 400° C. or higher. If the decomposition temperature is within the above range, the effect as a conductive additive can be maintained even when a thin film made of the thermoelectric semiconductor composition is annealed, as described below.

[0061] Furthermore, the inorganic ionic compound preferably exhibits a mass loss rate of 10% or less, more preferably 5% or less, and even more preferably 1% or less at 400°C as measured by thermogravimetry (TG). If the mass loss rate is within the above range, the compound can maintain its effectiveness as a conductive additive even when a thin film made of the thermoelectric semiconductor composition is annealed, as described below.

[0062] The amount of the inorganic ionic compound in the thermoelectric semiconductor composition is preferably 0.01 to 50 mass%, more preferably 0.5 to 30 mass%, and even more preferably 1.0 to 10 mass%. If the amount of the inorganic ionic compound is within the above range, a decrease in electrical conductivity can be effectively suppressed, resulting in a film with improved thermoelectric performance. When an inorganic ionic compound and an ionic liquid are used in combination, the total content of the inorganic ionic compound and the ionic liquid in the thermoelectric semiconductor composition is preferably 0.01 to 50 mass%, more preferably 0.5 to 30 mass%, and even more preferably 1.0 to 10 mass%.

[0063] <Electrode> The electrodes are provided to electrically connect the P-type and N-type thermoelectric elements that make up the thermoelectric element layer, or to electrically connect the thermoelectric element layer to the outside. Various electrode materials can be used for the electrodes. From the viewpoint of connection stability and thermoelectric performance, it is preferable to use a metal material with high conductivity. Preferred electrode materials include gold, silver, nickel, copper, alloys of these metals, and laminates of these metals or alloys. The thickness of the electrode is preferably 1 μm to 50 μm, more preferably 2.5 μm to 30 μm, and even more preferably 3 μm to 20 μm. When the electrode thickness is within the above range, the electrical conductivity is high and the resistance is low, and the total electrical resistance value of the thermoelectric element layer can be kept low. In addition, sufficient strength as an electrode can be obtained. Furthermore, the volume of the electrode can be increased, and even if the metal elements constituting the electrode diffuse into the thermoelectric element during use, deterioration of the electrode performance can be suppressed. Furthermore, the electrode is easily embedded in the thermoelectric element layer, the surface smoothness of the thermoelectric conversion module is maintained, and the thermoelectric performance tends to be stable.

[0064] <High thermal conductivity layer> The high thermal conductivity layer has excellent thermal conductivity and its thermal conductivity is higher than that of the coating layer. The high thermal conductivity layer preferably has a thermal conductivity of 5 to 500 W / (m·K), more preferably 15 to 420 W / (m·K), and even more preferably 300 to 420 W / (m·K). The material constituting the high thermal conductivity layer is not particularly limited as long as it has a high thermal conductivity, but is preferably a metal, more preferably any one of copper, aluminum, silver, and nickel, even more preferably any one of copper, aluminum, and silver, and even more preferably any one of copper and aluminum. The high thermal conductivity layer is arranged in a pattern such as stripes, lattices, honeycombs, combs, or a matrix. This makes it easier to generate a temperature difference in the surface direction of the thermoelectric conversion module, and by exposing the boundary between the P-type and N-type thermoelectric elements, heat exchange with the outside is efficient. As a result, the electromotive force performance, heat generation performance, and heat absorption performance of the thermoelectric conversion module can be improved. As also explained in Figure 4, it is preferable that the first high thermal conductivity layer is arranged on one side of the thermoelectric element layer so as to cover every other junction between the P-type thermoelectric element and the N-type thermoelectric element, and the second high thermal conductivity layer is arranged at a position corresponding to the junction of the thermoelectric element that is not covered by the first high thermal conductivity layer when viewed from a direction perpendicular to the main surface of the support (substrate), and that the first high thermal conductivity layer and the second high thermal conductivity layer are arranged alternately with respect to the thermoelectric element layer in a vertical cross section in the arrangement direction of the high thermal conductivity layers. From the viewpoints of flexibility, heat dissipation, and dimensional stability, the thickness of the high thermal conductive layer is preferably 40 to 550 μm, more preferably 60 to 530 μm, and even more preferably 80 to 510 μm. When two high thermal conductive layers, first high thermal conductive layer 91 and second high thermal conductive layer 92, are provided, they may be made of the same material or different materials and may have the same thickness or different thicknesses.

[0065] <Coating layer> The covering layer is disposed so as to cover the thermoelectric element layer. By disposing the covering layer in this manner, it is not necessary to form the covering layer in a pattern, which results in excellent productivity. Furthermore, if a member such as a low thermal conductive layer is not provided in an area of ​​the thermoelectric element layer where the high thermal conductive layer is not provided, the thermoelectric element layer would be exposed if the covering layer did not cover the thermoelectric element layer. However, by covering the thermoelectric element layer with the covering layer, the thermoelectric element layer can be protected in areas where the high thermal conductive layer is not present.

[0066] When two coating layers are provided, such as the first coating layer 81 and the second coating layer 82 described above, these may be made of the same material or different materials.

[0067] The second covering layer 82 laminated on the surface of the support 2 (substrate) opposite to the surface on the thermoelectric element layer 6 side may be a single layer or may have a multi-layer configuration. Also, the second covering layer 82 may be eliminated from the thermoelectric conversion module, and a second highly thermally conductive layer may be provided directly on the back surface of the support 2.

[0068] When a single-layer coating layer is used, it is preferable that the coating layer itself has adhesive properties and can adhere and fix the high thermal conductivity layer to the thermoelectric element layer. Furthermore, if this single-layer coating layer itself is a sealing layer, and as described below, it is a layer having a water vapor permeability within a predetermined range or a layer made of a composition containing a polyolefin resin, the coating layer covers the thermoelectric element layer and functions as a member that seals the thermoelectric element layer, which is more preferable. Using a single-layer coating layer reduces the number of layers in the thermoelectric conversion module, thereby simplifying the configuration of the thermoelectric conversion module and simplifying the manufacturing process of the thermoelectric conversion module. Furthermore, the overall thickness of the coating layer can be reduced, thereby increasing the efficiency of heat exchange between the high thermal conductivity layer and the thermoelectric element layer.

[0069] When a thermoelectric conversion module has a covering layer including multiple layers, there is an advantage in that it is easy to allocate multiple functions to each layer, such as the function of adhering the high thermal conductivity layer and the thermoelectric element layer, and the function of sealing. For example, by imparting gas barrier properties to the auxiliary substrate layer described below as an intermediate layer and providing an inner layer and an outer layer as adhesive layers on both sides of the auxiliary substrate layer, it is possible to easily achieve both the gas barrier function and the adhesive function. In this case, if at least one of the inner layer and the outer layer also serves as a sealing layer, the gas barrier property of the auxiliary substrate layer and the sealing property of the inner layer and / or the outer layer as sealing layers can be expected to improve the durability of the thermoelectric conversion module. When a thermoelectric conversion module has a first covering layer 81, the thickness difference t of the thermoelectric elements dif The reason for this is that the thickness difference t dif It is presumed that the large size of the coating layer reduces the adhesiveness between the coating layer and the thermoelectric element layer, inhibiting heat conduction between the thermoelectric element layer and the outside air.

[0070] The total thickness of the coating layer is preferably 1 to 200 μm, more preferably 5 to 175 μm, from the viewpoint of efficient heat conduction between the high thermal conductivity layer and the thermoelectric element layer.

[0071] The thermoelectric conversion module according to this embodiment can improve heat transfer efficiency by efficiently transferring heat applied from the outside, and can obtain a high electromotive force. Furthermore, this embodiment is a preferable configuration because it can efficiently generate a temperature difference within the surface of the thermoelectric conversion module by providing two high thermal conductivity layers, the first high thermal conductivity layer 91 and the second high thermal conductivity layer 92. However, for example, in cases where it is desired to increase the area of ​​the thermoelectric conversion module or to simplify the configuration of the thermoelectric conversion module as much as possible, it is also possible to omit the second high thermal conductivity layer 92.

[0072] [Method of manufacturing thermoelectric conversion modules] In one example of a method for manufacturing a thermoelectric conversion module according to this embodiment, a coating layer is formed on a thermoelectric element layer, and a high thermal conductivity layer is formed in a pattern on a portion of one surface of the coating layer. More specifically, the method includes the steps of preparing a support 2 having electrodes 3 arranged in a pattern as shown in Fig. 2, forming a thermoelectric element layer 6 consisting of P-type thermoelectric elements 5 and N-type thermoelectric elements 4 on one surface of the support 2 as shown in Fig. 3, forming a first coating layer 81 on the surface of the thermoelectric element layer 6, forming a first high thermal conductivity layer 91 on at least a portion of the surface of the first coating layer 81 as shown in Fig. 4, and forming a second high thermal conductivity layer 92 on the other surface of the support 2. Each step will be explained below in order with reference to the drawings.

[0073] <Step of Preparing a Support on Which Electrodes Are Formed> In a method for manufacturing a thermoelectric conversion module, for example, as shown in FIG. 2, first, a support 2 is prepared, on one main surface of which an electrode 3 having a predetermined pattern is formed. To prepare a support having an electrode 3 formed thereon, an electrode may be formed on the support 2 using the electrode material described above. Methods for forming an electrode on a support include a method in which an electrode without a pattern is provided on the support, and then processed into a predetermined pattern by known physical or chemical treatments, primarily photolithography (e.g., wet etching), or a combination of these, or a method in which an electrode pattern is directly formed by screen printing, inkjet printing, or the like. Examples of methods for forming electrodes without patterns include dry processes such as PVD (physical vapor deposition) methods such as vacuum deposition, sputtering, and ion plating, or CVD (chemical vapor deposition) methods such as thermal CVD and atomic layer deposition (ALD), or wet processes such as various coating methods and electrodeposition methods such as dip coating, spin coating, spray coating, gravure coating, die coating, and doctor blade methods, silver halide plating, electrolytic plating, electroless plating, and metal foil lamination, and the like, and these methods are selected appropriately depending on the material of the electrode.

[0074] <Step of forming thermoelectric element layer> Next, as shown in FIG. 3 , a thermoelectric element layer 6 consisting of P-type thermoelectric elements 5 and N-type thermoelectric elements 4 is formed on one main surface of the support 2 on which the electrodes 3 are arranged in a pattern, using a thermoelectric semiconductor composition. The thermoelectric element layer 6 is formed, for example, by applying a varnish, ink, or the like, in which the materials of the thermoelectric semiconductor composition described above are dissolved or dispersed in a solvent, to the support. Methods for applying the thermoelectric semiconductor composition to the support include, but are not limited to, well-known methods such as screen printing, flexographic printing, gravure printing, spin coating, dip coating, die coating, spray coating, bar coating, and doctor blade. When forming a patterned coating film, screen printing is preferably used, as it allows for easy pattern formation using a screen plate (printing plate) having the desired pattern. Specific embodiments for forming a thermoelectric element layer by screen printing are as described above. The resulting coating film is then dried to form a thin film. Conventional drying methods, such as hot air drying, heated roll drying, and infrared irradiation, can be used to dry the coating film. The heating temperature during drying can be in the range of 80 to 150°C. The heating time during drying varies depending on the heating method, but can be from several seconds to several tens of minutes. Furthermore, when the thermoelectric semiconductor composition is prepared using a solvent, the heating temperature for drying the coating film of this composition is not particularly limited as long as it is within a temperature range that can dry the solvent used. The resulting coating film may be further subjected to an annealing treatment under the same conditions as in the annealing treatment A described above. After the thermoelectric element layer is formed, it may be peeled off from the support 2 and replaced with, for example, another support (substrate) having low heat resistance.

[0075] <Step of forming first coating layer> Next, a first covering layer 81 is formed on the surface of the thermoelectric element layer 6 opposite the support 2. The covering layer can be formed by a known method. The covering layer may be formed directly on the surface of the thermoelectric element layer, or may be formed by attaching a covering layer previously formed on a release sheet to the thermoelectric element layer and transferring the covering layer to the thermoelectric element layer.

[0076] When the coating layer is composed of multiple layers, a coating layer containing multiple layers may be prepared in advance and attached to the thermoelectric element layer, or each layer constituting the multiple layers may be sequentially stacked on the thermoelectric element layer to form a coating layer composed of multiple layers on the thermoelectric element layer.

[0077] <Step of forming first high thermal conductive layer> A first highly thermally conductive layer 91 is formed on at least a portion of the surface of the first covering layer 81. The first highly thermally conductive layer 91 may be provided on the covering layer 81 formed on the thermoelectric element layer 6, or the first highly thermally conductive layer 91 may be provided on the covering layer 81, and then the covering layer 81 with the first highly thermally conductive layer 91 may be provided on the support 2.

[0078] <Step of forming second high thermal conductive layer> A second high thermal conductivity layer 92 is formed on a portion of the other surface of the support 2. In this case, the second high thermal conductivity layer 92 may be formed after the second covering layer 82 is formed on the support 2, or the second covering layer 82 with the second high thermal conductivity layer 92 may be formed on the other surface of the support 2. By using a support on which the second high thermal conductivity layer 92 is directly formed by vapor deposition, sputtering, printing, or the like, it is possible to obtain a thermoelectric conversion module in which a high thermal conductivity layer is provided in direct contact with the support. [Example]

[0079] Next, specific examples of the present invention will be described, but the present invention is not limited to these examples in any way. The thickness difference evaluation and electromotive force evaluation in the examples and comparative examples described below were carried out in the following manner.

[0080] [Thickness difference evaluation] The thickness of the thermoelectric elements formed on the thermoelectric element-attached substrate after the P-type and N-type thermoelectric elements were arranged but before annealing treatment was performed was measured at one point using a thickness gauge (Teclock Corporation, Digital Indicator PC-465J), and the thickness of the thermoelectric element was determined by subtracting the thickness of the substrate (50 μm) from the measured thickness. To determine the thickness of the thermoelectric element, first, thickness measurements were performed on five thermoelectric elements randomly selected from the multiple thermoelectric elements on one thermoelectric element layer-attached substrate, and a first average value was calculated as the average of the measured values ​​of the five thermoelectric elements. Such thickness measurements were performed on three thermoelectric element layer-attached substrates, and the average of the three first average values ​​for the three thermoelectric element layer-attached substrates was calculated as a second average value, and the second average value was used as the gauge element thickness t ga It was decided.

[0081] Next, a substrate with thermoelectric elements similar to the above-mentioned substrate with thermoelectric element layer was attached to a glass plate (length 100 mm × width 100 mm × thickness 0.7 mm), and the thickness of the gauge element of the P-type thermoelectric element and the N-type thermoelectric element was t ga The element with a larger gauge element thickness t ga An element having a larger thickness is also referred to as a "thicker element.") (Examples 1 to 5 and Comparative Examples 1 to 4: N-type thermoelectric element, Example 6: P-type thermoelectric element) The thickness profile of the cross section along the direction perpendicular to the arrangement direction of the thermoelectric elements (the application direction of the coating liquid (P) and coating liquid (N) described below) was measured using a stylus surface profilometer (Dectak150, manufactured by ULVAC, Inc.). The measurement frequency was every 0.4 μm. The measurement site was a part where no electrodes were provided. The average thickness at the center of the thermoelectric element excluding both ends was calculated, and the average of the calculated thicknesses was taken as the average element thickness t av The central portion is the region defined as above. The thickness profile was first measured for five thermoelectric elements randomly selected from the plurality of thermoelectric elements on one substrate with a thermoelectric element layer. As a result, the average thickness t av Such thickness profile measurements were carried out on three substrates with thermoelectric element layers. As a result, the average thickness t avFurthermore, from the 15 thickness profiles measured, the maximum thickness of the thermoelectric element (thickest part) was detected for each thickness profile, and the maximum detected thickness was taken as the maximum thickness t max As a result, the maximum thickness of 15 max Furthermore, the maximum thickness t max and the average element thickness t av The average of the differences between the thickness profiles was calculated for the five thermoelectric elements selected at random, and was designated as the first average value (i.e., the average of the five differences obtained from the five thickness profiles). Such calculation was performed for the three thermoelectric element layer-attached substrates, and the average of the three first average values ​​for the three thermoelectric element layer-attached substrates was calculated to be the second average value (i.e., the average of the 15 differences obtained from the 15 thickness profiles). The second average value was used as the thickness difference t dif The results are shown in Table 1.

[0082] [Electromotive force evaluation] For the thermoelectric conversion modules produced in the examples and comparative examples, the electromotive force between the extraction electrodes was measured using a digital high tester (manufactured by Hioki E.E. Corporation, model number: 3801-50) with a temperature difference of 20°C applied between the hot plate and the water-cooled chiller (the set temperatures of the hot plate and the water-cooled chiller were adjusted so that the temperature difference was 20°C). An electromotive force between the extraction electrodes of 0.4 V or more was evaluated as (◯: acceptable), and an electromotive force of less than 0.4 V was evaluated as (×: poor). The electromotive force was measured by placing thermocouples on both sides of the fabricated thermoelectric conversion module and measuring the actual temperature difference between the high-temperature side and the low-temperature side. If the measured temperature difference did not match 20°C and there was a difference within ±5°C, the electromotive force measured as above was corrected based on the proportional relationship between electromotive force and temperature difference to be equivalent to 20°C. The results are shown in Table 1.

[0083] [Fabrication of thermoelectric conversion module] Example 1 (Production of thermoelectric semiconductor particles) P-type bismuth telluride Bi, a bismuth-tellurium-based thermoelectric semiconductor material 0.4 Te3Sb 1.6(manufactured by Kojundo Chemical Laboratory, particle size: 90 μm) was pulverized in a nitrogen gas atmosphere using a planetary ball mill (manufactured by Fritsch Japan, Premium line P-7) to produce thermoelectric semiconductor particles T1 with an average particle size of 2.5 μm. In addition, N-type bismuth telluride Bi2Te3 (manufactured by Kojundo Chemical Laboratory, particle size: 90 μm), a bismuth-tellurium-based thermoelectric semiconductor material, was pulverized in the same manner as above to produce thermoelectric semiconductor particles T2 with an average particle size of 2.5 μm. The average particle sizes of T1 and T2 were obtained by measuring the particle size distribution of the pulverized thermoelectric semiconductor particles using a laser diffraction particle size analyzer (Malvern, Mastersizer 3000).

[0084] (Preparation of Thermoelectric Semiconductor Composition) A coating liquid (P) consisting of a thermoelectric semiconductor composition was prepared by mixing and dispersing 94.6 parts by mass of the obtained fine particles T1 of the P-type bismuth-tellurium thermoelectric semiconductor material, 2.9 parts by mass (solid content equivalent) of a polyamideimide solution (manufactured by Arakawa Chemical Industries, Ltd., product name: Comporacene AI301, solvent: N-methylpyrrolidone, solid content: 18% by mass) as a resin, and 2.5 parts by mass of N-butylpyridinium bromide as an ionic liquid. Furthermore, a coating liquid (N) consisting of a thermoelectric semiconductor composition was prepared by mixing and dispersing 95.0 parts by mass of the obtained N-type bismuth-tellurium-based thermoelectric semiconductor material fine particles T2, 2.7 parts by mass (solid content equivalent) of a polyamideimide solution (manufactured by Arakawa Chemical Industries, Ltd., product name: Comporacene AI301, solvent: N-methylpyrrolidone, solid content: 18% by mass) as a resin, and 2.3 parts by mass of N-butylpyridinium bromide as an ionic liquid.

[0085] (Electrode formation and placement) A substrate was fabricated by the following procedure, with electrodes provided in the arrangement pattern according to the above-mentioned Figures 2 and 3. Note that the above-mentioned Figures 2 and 3 show conceptually the arrangement of the electrodes and thermoelectric elements, and the number of electrodes and thermoelectric elements actually fabricated differs. First, a polyimide film substrate with copper foil attached (manufactured by Ube Exsymo Co., Ltd., product name: Upicel N, polyimide substrate thickness: 50 μm, copper foil thickness: 9 μm) was prepared. The copper foil on this polyimide film substrate was then wet-etched using a ferric chloride solution to form electrodes arranged in a pattern corresponding to the arrangement of the P-type and N-type thermoelectric elements described below. The electrodes were formed with a size of 550 μm × 6 mm so as to straddle the boundaries between adjacent P-type and N-type thermoelectric elements in the arrangement of the thermoelectric elements described below. A nickel layer (thickness: 3 μm) was selectively laminated on the patterned copper foil by electroless plating, and then a gold layer (thickness: 400 nm) was selectively laminated on the nickel layer by electroless plating to form electrodes.

[0086] (Formation of thermoelectric element layer) The coating solution (P) prepared above was applied onto the polyimide film on which the electrodes had been formed by screen printing using a printing plate for forming P-type thermoelectric elements, which had a plate thickness of 30 μm and openings of 1 mm × 6 mm, with the application direction Z being perpendicular to the arrangement direction Y of the thermoelectric elements, and the film was dried at a temperature of 150°C for 10 minutes in an argon atmosphere to form a thin film (see Figure 6A and Figure 6C (the printing plate 60 in Figure 6C has three openings (holes) 61 for the sake of clarity, but the number of openings (holes) 61 is not limited to this)). Next, similarly, the coating solution (N) prepared above was applied onto the polyimide film by screen printing using a printing plate for forming N-type thermoelectric elements, which had a plate thickness of 30 μm and an opening of 1 mm × 6 mm, with the application direction being the perpendicular direction Z to the arrangement direction Y of the thermoelectric elements, and the film was dried at a temperature of 150°C for 10 minutes in an argon atmosphere to form a thin film (see FIGS. 6B and 6C). Furthermore, the obtained thin films were heated at a rate of 5 K / min in an atmosphere of a mixed gas of hydrogen and argon (hydrogen:argon = 3% by volume:97% by volume), and held at 325°C for 30 minutes, performing an annealing treatment after thin film formation, thereby causing crystal growth of the fine particles of the thermoelectric semiconductor material and producing P-type and N-type thermoelectric elements.

[0087] (Arrangement of thermoelectric elements) Coating solution (P) and coating solution (N) were applied to electrodes on a polyimide film substrate to form alternating 1 mm x 6 mm P-type thermoelectric elements and 1 mm x 6 mm N-type thermoelectric elements. P-type and N-type thermoelectric elements were paired adjacently, with a 6 mm edge in contact. In this way, a thermoelectric element layer was fabricated in which 380 pairs of P-type and N-type thermoelectric elements were electrically connected in series within the surface of the polyimide film substrate, in an arrangement similar to that of the thermoelectric elements in Figure 3. This allows electrons to move within the thermoelectric element layer consisting of P-type and N-type thermoelectric elements in the direction of the thermoelectric element arrangement. The thermoelectric element layer has a folded structure. Ten rows were arranged, each consisting of 38 pairs of P-type and N-type thermoelectric elements. The spacing between each row of the thermoelectric element layer is 1 mm, the connecting electrodes of each row of the thermoelectric element layer are 0.55 mm x 13 mm, and the electromotive force extracting electrodes are 12.775 mm x 6 mm. The gauge element thickness of the N-type thermoelectric element is t ga The thickness of the gauge element of the P-type thermoelectric element is t ga It was bigger than that.

[0088] (Formation of coating layer and high thermal conductivity layer) An aluminum-deposited PET film (manufactured by Mitsubishi Shindoh Co., Ltd., thickness: 12 μm) was used as the insulating layer, and an adhesive layer (manufactured by Somar Co., Ltd., product name: EP-0002EF-01MB, thickness: 25 μm) was laminated on both sides to form a covering layer. The lamination was performed at a temperature of 50°C. A stripe-shaped high-thermal-conductivity layer (C1020, thickness: 200 μm, width: 1 mm, length: 100 mm, spacing: 1 mm, thermal conductivity: 398 (W / m K)) made of a highly thermally conductive material (copper foil) was placed on the top surface (surface of the thermoelectric element layer) of the fabricated substrate with a thermoelectric element layer via the above-mentioned coating layer. Also, a stripe-shaped high-thermal-conductivity layer (C1020, thickness: 200 μm, width: 1 mm, length: 100 mm, spacing: 1 mm, thermal conductivity: 398 (W / m K)) made of a highly thermally conductive material (copper foil) was placed on the bottom surface (the surface of the substrate opposite the thermoelectric element layer) of the substrate with a thermoelectric element layer via a single adhesive coating layer (manufactured by Somar, product name: EP-0002EF-01MB, thickness: 25 μm). The stripe-shaped high-thermal-conductivity layer was alternately placed above (the surface of the thermoelectric element) and below (the surface of the substrate opposite the thermoelectric element layer) the area where the P-type and N-type thermoelectric elements were adjacent. The covering layer provided on the surface of the substrate with the thermoelectric element layer was arranged so that the aluminum-deposited surface of the aluminum-deposited PET film was located farther from the thermoelectric element layer. The lamination of the cover layer onto the thermoelectric element layer, the lamination of the adhesive layer onto the substrate, and the lamination of the high thermal conductivity layer onto the cover layer and adhesive layer were all carried out at a temperature of 80°C. Thereafter, the thermoelectric conversion module was left standing in an environment at 150° C. for 30 minutes to harden the adhesive layer, thereby obtaining a thermoelectric conversion module.

[0089] <Example 2> A thermoelectric conversion module was fabricated in the same manner as in Example 1, except that a printing plate for forming N-type thermoelectric elements having a thickness of 50 μm was used instead of the printing plate for forming N-type thermoelectric elements having a thickness of 30 μm in Example 1, and the same measurements and evaluations were carried out. ga The thickness of the gauge element of the P-type thermoelectric element is t ga It was bigger than that.

[0090] Example 3 A thermoelectric conversion module was fabricated in the same manner as in Example 1, except that a printing plate for forming N-type thermoelectric elements having a thickness of 110 μm was used instead of the printing plate for forming N-type thermoelectric elements having a thickness of 30 μm in Example 1, and the same measurements and evaluations were carried out. ga The thickness of the gauge element of the P-type thermoelectric element is tga It was bigger than that.

[0091] Example 4 A thermoelectric conversion module was fabricated in the same manner as in Example 1, except that a printing plate for forming P-type thermoelectric elements having a thickness of 80 μm was used instead of the printing plate for forming P-type thermoelectric elements having a thickness of 30 μm in Example 1, and the same measurements and evaluations were carried out. ga The thickness of the gauge element of the P-type thermoelectric element is t ga It was bigger than that.

[0092] <Example 5> A thermoelectric conversion module was fabricated in the same manner as in Example 1, except that a printing plate for forming P-type thermoelectric elements having a thickness of 80 μm and a printing plate for forming N-type thermoelectric elements having a thickness of 50 μm were used instead of the printing plate for forming P-type thermoelectric elements having a thickness of 30 μm and the printing plate for forming N-type thermoelectric elements having a thickness of 30 μm in Example 1. The gauge element thickness t ga The thickness of the gauge element of the P-type thermoelectric element is t ga It was bigger than that.

[0093] Example 6 A thermoelectric conversion module was fabricated in the same manner as in Example 1, except that the P-type thermoelectric element was printed after the N-type thermoelectric element, instead of after the P-type thermoelectric element in Example 1. The same measurements and evaluations were carried out. ga The thickness of the gauge element of the N-type thermoelectric element is t ga It was bigger than that.

[0094] <Comparative Example 1> A thermoelectric conversion module was fabricated in the same manner as in Example 1, except that a printing plate for forming P-type thermoelectric elements having a thickness of 150 μm and a printing plate for forming N-type thermoelectric elements having a thickness of 50 μm were used instead of the printing plate for forming P-type thermoelectric elements having a thickness of 30 μm and the printing plate for forming N-type thermoelectric elements having a thickness of 30 μm in Example 1. The gauge element thickness tga The thickness of the gauge element of the P-type thermoelectric element is t ga It was bigger than that.

[0095] <Comparative Example 2> In Example 1, instead of using a printing plate for forming P-type thermoelectric elements having a plate thickness of 30 μm and a printing plate for forming N-type thermoelectric elements having a plate thickness of 30 μm, a printing plate for forming P-type thermoelectric elements having a plate thickness of 150 μm and a printing plate for forming N-type thermoelectric elements having a plate thickness of 30 μm were used. However, the present invention is not limited to this. Furthermore, a thermoelectric conversion module was fabricated in the same manner as in Example 1, except that a printing plate 70 for forming N-type thermoelectric elements, as shown in FIG. 7B (used by inverting it 180° with respect to the coating direction Z), was used, which had a plate thickness T of 180 μm and had voids (grooves) 70A with a height H of 130 μm formed so that the already formed P-type thermoelectric elements could fit in. The gauge element thickness t ga The thickness of the gauge element of the P-type thermoelectric element is t ga It was bigger than that.

[0096] <Comparative Example 3> In Example 1, instead of using a printing plate for forming P-type thermoelectric elements having a thickness of 30 μm and an opening of 1 mm×6 mm, and a printing plate for forming N-type thermoelectric elements having a thickness of 30 μm, a printing plate for forming P-type thermoelectric elements having a thickness of 150 μm and an opening of 0.8 mm×6 mm, and a printing plate for forming N-type thermoelectric elements having a thickness T of 180 μm and having a void portion (groove) 70A with a height H of 130 μm formed so that the already formed P-type thermoelectric elements can be fitted, as shown in FIGS. 7A and 7B, were used. A thermoelectric conversion module was fabricated in the same manner as in Example 1, and similar measurements and evaluations were performed. Note that the gauge element thickness t of the N-type thermoelectric elements was ga The thickness of the gauge element of the P-type thermoelectric element is t ga It was bigger than that.

[0097] <Comparative Example 4> In Example 1, instead of using a printing plate for forming P-type thermoelectric elements having a thickness of 30 μm and an opening of 1 mm×6 mm, and a printing plate for forming N-type thermoelectric elements having a thickness of 30 μm and an opening of 1 mm×6 mm, a printing plate for forming P-type thermoelectric elements having a thickness of 150 μm and an opening of 0.8 mm×6 mm, and a printing plate for forming N-type thermoelectric elements having a thickness T of 180 μm, an opening (hole) 70B of 0.8 mm×6 mm, and a void (groove) 70A with a height H of 130 μm so that an already formed P-type thermoelectric element can be fitted, as shown in FIGS. 7A and 7B, were used. A thermoelectric conversion module was fabricated in the same manner as in Example 1, and similar measurements and evaluations were performed. Note that the gauge element thickness t of the N-type thermoelectric elements was ga The thickness of the gauge element of the P-type thermoelectric element is t ga It was bigger than that.

[0098] [Table 1]

[0099] From Table 1, in the thermoelectric conversion modules of Comparative Examples 1 to 4, the thickness difference t dif In contrast, in the thermoelectric conversion modules of Examples 1 to 6, the thickness difference t dif Because the thickness was 50 μm or less, a high electromotive force was obtained (0.40 V or more: evaluation: Good).

[0100] 1A, 1B: Thermoelectric conversion module 2:Support 2a: Support main surface 3: Electrode 3a: First electrode part (connecting electrode part) 3b: Second electrode part (electrode part for taking out electromotive force) 3c: Third electrode part 4: N-type thermoelectric element 5: P-type thermoelectric element 6: Thermoelectric element layer 50: Cross section 51: Borderline 52: Line segment 53: Line segment 54: Center line 54a:edge 54b: Edge 55: Line segment 56: Line segment 57: Central part 58: Edge 59: Edge 60: Printing version (screen version) 61: Opening (hole) 70: Printing version (screen version) 70A: Gap (groove) 70B: Opening (hole) 81:First coating layer 82:Second coating layer 91: First high thermal conductive layer 92: Second high thermal conductive layer H: Height P: One end Q: The other end T: Plate thickness t av : Average element thickness t max : Maximum thickness Y: Direction of thermoelectric element arrangement Z: Application direction

Claims

1. A support; a thermoelectric element layer in which P-type thermoelectric elements and N-type thermoelectric elements formed on the support are alternately arranged, and adjacent P-type thermoelectric elements and N-type thermoelectric elements are electrically connected so that electrons move in the direction of the arrangement, the thermoelectric element layer is made of a coating film, A thickness difference t defined by the following (1) to (4) in a cross section of at least one of the P-type thermoelectric element and the N-type thermoelectric element along a direction perpendicular to the arrangement direction. ｄｉｆ is 20 μm or less (excluding 14 to 17 μm), The gauge element thickness t of the P-type thermoelectric element ｇａ and the gauge element thickness t of the N-type thermoelectric element ｇａ Unlike The gauge element thickness t of the P-type thermoelectric element and the N-type thermoelectric element ｇａ The thickness difference t of the thermoelectric element having the larger ｄｉｆ A thermoelectric conversion module having a thickness of 20 μm or less (excluding 14 to 17 μm). (1) The thickness profile of the thermoelectric element in the cross section is measured using a stylus surface profiler. (2) From the measured thickness profile, the average thickness at the center of the thermoelectric element excluding both ends is calculated, and the calculated average thickness is defined as the average element thickness t ａｖ Here, when the length of the boundary line between the thermoelectric element and the support in the cross section is L, and a line segment of length 2 / 3L is defined as a central line segment, excluding a line segment extending from one end of the boundary line inward to 1 / 6L and a line segment from the other end of the boundary line inward to 1 / 6L from the boundary line of length L, the central portion refers to a region of the thermoelectric element sandwiched between line segments extending from both ends of the central line segment in a direction perpendicular to the main surface of the support. (3) From the measured thickness profile, the maximum thickness of the thermoelectric element is detected, and the detected maximum thickness is designated as the maximum thickness t ｍａｘ Let's say. (4) The thickness difference t ｄｉｆ the maximum thickness t ｍａｘ and the average element thickness t ａｖ The difference between (t ｄｉｆ = t ｍａｘ -t ａｖ )

2. A support; a thermoelectric element layer in which P-type thermoelectric elements and N-type thermoelectric elements formed on the support are alternately arranged, and adjacent P-type thermoelectric elements and N-type thermoelectric elements are electrically connected so that electrons move in the direction of the arrangement, the thermoelectric element layer is made of a thermoelectric semiconductor composition containing thermoelectric semiconductor particles and a resin; A thickness difference t defined by the following (1) to (4) in a cross section of at least one of the P-type thermoelectric element and the N-type thermoelectric element along a direction perpendicular to the arrangement direction. ｄｉｆ is 20 μm or less (excluding 14 to 17 μm), The gauge element thickness t of the P-type thermoelectric element ｇａ and the gauge element thickness t of the N-type thermoelectric element ｇａ Unlike The gauge element thickness t of the P-type thermoelectric element and the N-type thermoelectric element ｇａ The thickness difference t of the thermoelectric element having the larger ｄｉｆ A thermoelectric conversion module having a thickness of 20 μm or less (excluding 14 to 17 μm). (1) The thickness profile of the thermoelectric element in the cross section is measured using a stylus surface profiler. (2) From the measured thickness profile, the average thickness at the center of the thermoelectric element excluding both ends is calculated, and the calculated average thickness is defined as the average element thickness t ａｖ Here, when the length of the boundary line between the thermoelectric element and the support in the cross section is L, and a line segment of length 2 / 3L is defined as a central line segment, excluding a line segment extending from one end of the boundary line inward to 1 / 6L and a line segment from the other end of the boundary line inward to 1 / 6L from the boundary line of length L, the central portion refers to a region of the thermoelectric element sandwiched between line segments extending from both ends of the central line segment in a direction perpendicular to the main surface of the support. (3) From the measured thickness profile, the maximum thickness of the thermoelectric element is detected, and the detected maximum thickness is designated as the maximum thickness t ｍａｘ Let's say. (4) The thickness difference t ｄｉｆ the maximum thickness t ｍａｘ and the average element thickness t ａｖ The difference between (t ｄｉｆ = t ｍａｘ -t ａｖ )

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