Method for manufacturing thermoelectric elements

Abstract

To provide a method for manufacturing a thermoelectric conversion element that has a thermoelectric element layer with excellent shape controllability and enables high integration.SOLUTION: A method for manufacturing a thermoelectric conversion element including a thermoelectric element layer made of a thermoelectric semiconductor composition containing a thermoelectric semiconductor material on a substrate includes the steps of providing a pattern frame having an opening on the substrate, filling the opening with the thermoelectric semiconductor composition, drying the thermoelectric semiconductor composition filled in the opening to form a thermoelectric element layer, and peeling the pattern frame from the substrate.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a thermoelectric conversion element.

Background Art

[0002] Conventionally, as one means for effectively using energy, there has been an apparatus that directly converts thermal energy and electrical energy with a thermoelectric conversion module having a thermoelectric effect such as the Seebeck effect or the Peltier effect. Among these, as the thermoelectric conversion element, the use of a so-called π-type thermoelectric conversion element is known. The π-type usually provides a pair of electrodes spaced apart from each other on a substrate. For example, a P-type thermoelectric element is provided on one electrode, and an N-type thermoelectric element is provided on the other electrode, also spaced apart from each other, and the upper surfaces of both thermoelectric elements are connected to the electrodes of the opposing substrate. Also, the use of a so-called in-plane type thermoelectric conversion element is known. The in-plane type is usually configured by arranging a plurality of thermoelectric elements so that N-type thermoelectric elements and P-type thermoelectric elements are alternately arranged, and connecting the electrodes below the thermoelectric elements in series, for example.

[0003] In recent years, there have been demands such as improvement of thermoelectric performance including thinning and high integration of thermoelectric conversion elements. In Patent Document 1, as the thermoelectric element layer, a method of forming a pattern of the thermoelectric element layer directly by using a thermoelectric semiconductor composition containing a resin or the like including the aspect of thinning by thinning is disclosed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in methods such as those described in Patent Document 1, where thermoelectric semiconductor compositions made of thermoelectric semiconductor materials, heat-resistant resins, etc., are directly formed as pattern layers on electrodes or substrates by screen printing, the shape control of the resulting thermoelectric element layer is insufficient. This can lead to bleeding at the edges of the thermoelectric element layer at the electrode interface or substrate interface, or the shape of the thermoelectric element layer may be distorted, making it impossible to control the shape to the desired form. For example, when constructing the aforementioned π-type thermoelectric conversion element, sufficient electrical and physical bonding may not be obtained between the upper surface of the resulting thermoelectric element layer and the electrode surface on the opposing substrate. In this case, thermal resistance may increase, and the thermoelectric performance inherent in the thermoelectric element layer may not be fully utilized. To obtain the desired power generation performance or cooling performance, it becomes necessary to increase the number of P-type thermoelectric element layer-N-type thermoelectric element layer pairs. Furthermore, when integrating π-type thermoelectric conversion elements to a high degree, the variation in resistance values ​​of each of the multiple P-type thermoelectric element layer-N-type thermoelectric element layer pairs may increase, or adjacent thermoelectric element layers may come into contact with each other. Similarly, when highly integrating the aforementioned in-plane type thermoelectric conversion element configuration, the edges of the P-type thermoelectric element layer and the edges of the N-type thermoelectric element layer may intersect with each other, making the interface unclear. This can lead to variations in the resistance values ​​of multiple P-type thermoelectric element layer-N-type thermoelectric element layer pairs, as well as variations in temperature differences or output between adjacent P-type and N-type thermoelectric element layer junctions.

[0006] In view of the above, the object of the present invention is to provide a method for manufacturing a thermoelectric conversion element that has a thermoelectric element layer with excellent shape controllability and is capable of high integration. [Means for solving the problem]

[0007] As a result of diligent research to solve the above problems, the present inventors have found a method for manufacturing a highly integrated thermoelectric conversion element having a thermoelectric element layer with excellent shape controllability by providing a pattern frame having spaced-out openings on a substrate, filling the openings with a thermoelectric semiconductor composition containing a thermoelectric semiconductor material, drying it to form a thermoelectric element layer, and then peeling the pattern frame from the substrate, thereby completing the present invention. In other words, the present invention provides the following (1) to (13). (1) A method for manufacturing a thermoelectric element, comprising a thermoelectric element layer made of a thermoelectric semiconductor composition containing a thermoelectric semiconductor material on a substrate, the method comprising the steps of: providing a pattern frame having openings on the substrate; filling the openings with the thermoelectric semiconductor composition; drying the thermoelectric semiconductor composition filled in the openings to form a thermoelectric element layer; and peeling the pattern frame off the substrate. (2) A method for manufacturing a thermoelectric element according to (1) above, further comprising the step of annealing the thermoelectric element layer. (3) The method for manufacturing a thermoelectric element as described in (2) above, wherein the temperature of the annealing treatment is 250 to 600°C. (4) A method for manufacturing a thermoelectric element according to (2) or (3) above, comprising the step of peeling off the chips constituting the thermoelectric element layer after the annealing treatment. (5) A method for manufacturing a thermoelectric element according to any one of (1) to (4) above, wherein the substrate is a polyimide film, a polyamide film, a polyetherimide film, a polyaramid film, or a polyamideimide film. (6) A method for manufacturing a thermoelectric element according to any one of (1) to (5) above, wherein the pattern frame includes stainless steel, copper, aluminum, or iron. (7) A method for manufacturing a thermoelectric element according to any one of (1) to (6) above, wherein the pattern frame includes a ferromagnetic material. (8) A method for manufacturing a thermoelectric element according to any one of (1) to (7) above, wherein the wall surface of the opening of the pattern frame includes a release layer. (9) A method for manufacturing a thermoelectric element according to any one of (1) to (8) above, comprising the step of fixing the pattern frame to the substrate using a magnet. (10) A method for manufacturing a thermoelectric element according to any one of (1) to (9) above, wherein the thermoelectric semiconductor composition further comprises a heat-resistant resin and an ionic liquid and / or an inorganic ionic compound. (11) A method for manufacturing a thermoelectric element according to any one of (1) to (10) above, wherein the thermoelectric semiconductor material is a bismuth-tellurium-based thermoelectric semiconductor material, a telluride-based thermoelectric semiconductor material, an antimony-tellurium-based thermoelectric semiconductor material, or a bismuth selenide-based thermoelectric semiconductor material. (12) The method for manufacturing a thermoelectric element according to (10), wherein the heat-resistant resin is a polyimide resin, a polyamide resin, a polyamide-imide resin, or an epoxy resin. (13) A method for manufacturing a thermoelectric element according to any one of (1) to (12) above, wherein the shape of the opening is one or more shapes selected from the group consisting of irregular shape, polyhedron shape, frustoconical shape, frustoelliptical shape, cylindrical shape, and elliptical cylindrical shape. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a method for manufacturing a thermoelectric conversion element that has a thermoelectric element layer with excellent shape controllability and is capable of high integration. [Brief explanation of the drawing]

[0009] [Figure 1] This is an explanatory diagram showing an example of the steps in order according to the method for manufacturing a thermoelectric element of the present invention. [Figure 2] This is a diagram illustrating an example of a pattern frame used in the manufacturing method of the thermoelectric conversion element of the present invention. [Figure 3] This is a cross-sectional view showing an example of a π-type thermoelectric element obtained by a process according to the manufacturing method of the thermoelectric element of the present invention. [Modes for carrying out the invention]

[0010] [Manufacturing method for thermoelectric conversion elements] The present invention relates to a method for manufacturing a thermoelectric conversion element, comprising a thermoelectric element layer made of a thermoelectric semiconductor composition containing a thermoelectric semiconductor material on a substrate, the method comprising the steps of: providing a pattern frame having openings on the substrate; filling the openings with the thermoelectric semiconductor composition; drying the thermoelectric semiconductor composition filled in the openings to form a thermoelectric element layer; and peeling the pattern frame from the substrate. In the method for manufacturing a thermoelectric conversion element of the present invention, a pattern frame having spaced-apart openings is provided on a substrate, a thermoelectric semiconductor composition containing a thermoelectric semiconductor material is filled into the openings, dried, and the pattern frame is peeled off the substrate, thereby forming a thermoelectric element layer with excellent shape controllability. The method for manufacturing a thermoelectric element of the present invention is preferably used in the configuration of a π-type thermoelectric element and an in-plane thermoelectric element. In the configuration of a π-type thermoelectric element, sufficient electrical and physical bonding is achieved between the upper surface of the obtained thermoelectric element layer and the electrode surface on the opposing substrate, suppressing an increase in thermal resistance and allowing the thermoelectric performance inherent in the thermoelectric element layer to be fully utilized. In addition, when integrating the configuration of a π-type thermoelectric element, the excellent shape controllability suppresses variations in the resistance values ​​of multiple P-type thermoelectric element layer-N-type thermoelectric element layer pairs, and prevents adjacent thermoelectric element layers from coming into contact with each other, thus enabling high integration. Furthermore, when integrating the configuration of in-plane thermoelectric elements, the excellent shape controllability prevents the edges of adjacent P-type thermoelectric element layers and N-type thermoelectric element layers from interlocking and obscuring the interface. This suppresses variations in the resistance values ​​of multiple P-type thermoelectric element layer-N-type thermoelectric element layer pairs, and stabilizes the temperature difference or output between each junction of adjacent P-type and N-type thermoelectric element layers, enabling high integration. On the other hand, even if the obtained thermoelectric element layer is directly transferred to another substrate having electrodes to form a π-type thermoelectric element or an in-plane thermoelectric element, or even if each chip constituting the thermoelectric element layer is placed on the electrodes of the substrate to form a π-type thermoelectric element or an in-plane thermoelectric element, the bonding properties with the electrode surface constituting the thermoelectric element are improved, suppressing the decrease in thermoelectric performance due to increased thermal resistance, and allowing the thermoelectric performance inherent in the thermoelectric element layer to be realized. As a result, the number of thermoelectric element layers required to obtain the desired thermoelectric performance can be reduced, leading to a reduction in manufacturing costs. At the same time, it leads to lower power consumption in cooling and higher output in power generation. In terms of integration, high integration is possible because a thermoelectric element layer with excellent shape controllability is used.

[0011] In this specification, "openings" refer to multiple openings spaced apart within the area of ​​the entire pattern frame, as described later. The planar shape of each opening (when the pattern frame on the substrate is viewed from above) extends to the substrate surface in the thickness (depth) direction of the pattern frame. For example, if the planar shape of an opening is rectangular, the shape of the opening is usually approximately a rectangular parallelepiped, although this may vary depending on the pattern frame formation or processing method. Similarly, if the planar shape of an opening is circular, the shape of the opening is usually approximately cylindrical. The shape of the openings in the pattern frame is not particularly limited, and any desired shape can be used, as described later. The method for manufacturing the thermoelectric conversion element of the present invention will be described below with reference to the figures.

[0012] Figure 1 is an explanatory diagram showing an example of the process according to the method for manufacturing a thermoelectric element of the present invention, in order of steps: (a) is a cross-sectional view showing a configuration in which a pattern frame is placed opposite another on a substrate; (b) is a cross-sectional view after the pattern frame has been formed on the substrate; (c) is a cross-sectional view after the thermoelectric element layer has been filled into the opening of the pattern frame; and (d) is a cross-sectional view showing a configuration in which the pattern frame is peeled off from the filled thermoelectric element layer to obtain only the thermoelectric element layer.

[0013] Figure 3 is a cross-sectional view showing an example of a π-type thermoelectric element obtained by a process according to the method for manufacturing a thermoelectric element of the present invention. Except for providing an electrode 12a on the substrate (on the substrate 11a in Figure 3) in Figure 1(a), an N-type thermoelectric element layer 14a and a P-type thermoelectric element layer 14b are formed by the same process as in Figures 1(b) to (d), and then a π-type thermoelectric element can be manufactured by joining the upper surfaces of the N-type thermoelectric element layer 14a and the P-type thermoelectric element layer 14b to the counter electrode 12b on the opposing substrate 11b.

[0014] <Pattern frame formation process> The pattern frame formation process is the process of providing a pattern frame on a substrate. For example, in Figure 1(a), a pattern frame 2 made of stainless steel 2' (described later), having an opening 3s, an opening 3, and an opening depth (pattern frame thickness) 3d, is placed opposite a substrate 1, and in Figure 1(b), the pattern frame 2 is provided on the substrate 1. In the present invention, the pattern frame may be provided by directly forming it on the substrate, but from the viewpoint of peeling the pattern frame from the substrate in the pattern frame peeling process described later, it is generally preferable to provide the pattern frame by placing and fixing a pre-formed pattern frame on the substrate.

[0015] (Pattern frame) In the method for manufacturing a thermoelectric conversion element of the present invention, a pattern frame having an opening is provided on a substrate.

[0016] Figure 2 is a diagram illustrating an example of a pattern frame used in the manufacturing method of the thermoelectric element of the present invention, where (a) is a plan view of the pattern frame and (b) is a cross-sectional view of the pattern frame when cut between A and A' in (a). The pattern frame 2 is made of stainless steel 2' and has an opening 3 with an opening 3s and an opening depth (pattern frame thickness) 3d.

[0017] The openings included within the pattern frame, as well as their arrangement, number, and dimensions, including the distance between the openings, are not particularly limited and are adjusted as appropriate according to the shape and arrangement of the thermoelectric element layer. The shape of the opening is not particularly limited, and any desired shape can be used. Preferably, it is one or more shapes selected from the group consisting of irregular shapes, polyhedrons, frustocones, frustoellipses, cylinders, and elliptic cylinders. Examples of polyhedrons include cubic, rectangular, and frustoconical shapes. Cubic, rectangular, frustoconical, and cylindrical shapes are more preferred because they facilitate the formation or processing of the pattern frame. Among these, rectangular and cubic shapes are even more preferred from the viewpoint of the shape of the thermoelectric element layer and its thermoelectric performance. In Figure 2, the opening 3s is square, and the opening 3 is approximately cubic (not shown), with a total of 4 × 4 openings and openings.

[0018] The materials used to construct the pattern frame include single metals such as copper, silver, iron, nickel, chromium, and aluminum, as well as alloys such as stainless steel and brass. Preferably, the material contains stainless steel, copper, aluminum, or iron. From the viewpoint of ease of forming the pattern frame, stainless steel and copper are more preferable. Stainless steel is referred to as SUS (Steel Special Use Stainless) in JIS and is defined as "an alloy steel in which iron is the main component and Cr and Ni are included for the purpose of improving corrosion resistance, and generally has a carbon content of 1.2% or less and a Cr content of 10.5% or more." Examples of stainless steel include ferritic stainless steel (such as SUS430 series in JIS standards) and austenitic stainless steel (such as SUS304 series and SUS316 series in JIS standards).

[0019] It is also preferable that the pattern frame contains a ferromagnetic material. This allows the pattern frame to be easily fixed with the substrate in between, for example, if a magnet is placed on the side of the substrate opposite to the pattern frame. Examples of ferromagnetic materials include iron, nickel, cobalt, and their alloys, as well as ferritic stainless steel. Furthermore, alloys of at least one element selected from iron, nickel, cobalt, manganese, and chromium with at least one element selected from platinum, palladium, iridium, ruthenium, and rhodium can be used. The properties of ferromagnetic materials can be altered by changing the composition, heat treatment, etc. Among these, ferritic stainless steel is preferred from the viewpoint of versatility, fixing strength, ease of attachment and detachment, damage to the substrate, and heat resistance. SUS430 is a preferred ferritic stainless steel. Furthermore, there are no particular restrictions on the magnet as long as no misalignment of the pattern frame occurs during the manufacturing of the thermoelectric element layer, but permanent magnets or electromagnets can be used. For example, as a permanent magnet, a ferrite magnet (composition: BaO·6Fe2O3, SrO·6Fe2O3, magnetic flux density 0.4 Wb / m) can be used. 2 ), neodymium magnet (composition: Nd2Fe 14 B, magnetic flux density 1.2 Wb / m 2 ), samarium magnet (composition: SmCo5, magnetic flux density 1.2 Wb / m²) 2 ), praseodymium magnets (PrCo5), samarium iron nitrogen magnets, etc., can be used. Among these, ferrite magnets and neodymium magnets are more preferred from the viewpoint of versatility, fixing strength, damage to the substrate, and heat resistance.

[0020] The pattern frame is formed from the aforementioned material. The method for forming the pattern frame is not particularly limited, but examples include processing the sheet-like material into a predetermined pattern shape beforehand by known physical or chemical treatments, mainly photolithography, or a combination thereof, as well as laser processing, electrical discharge machining, milling, computer numerical control machining, water jet machining, and punching. Alternatively, a method may be used to process a layer made of the above-mentioned material that does not have a pattern formed on it into a predetermined pattern shape by known physical or chemical treatments, mainly the above-mentioned photolithography method, or by using a combination of these methods, such as dry processes such as PVD (physical vapor deposition) such as vacuum deposition, sputtering, or ion plating, or dry processes such as CVD (chemical vapor deposition) such as thermal CVD or atomic layer deposition (ALD), or wet processes such as various coatings such as dip coating, spin coating, spray coating, gravure coating, die coating, or doctor blade method, or silver halide method. In the present invention, from the viewpoint of process simplicity and pattern accuracy, it is preferable to form a predetermined pattern on the sheet-like material by known chemical treatment mainly using photolithography, for example, by wet etching the patterned portion of the photoresist and removing the photoresist, or by laser processing.

[0021] The thickness of the pattern frame depends on the thickness of the thermoelectric element layer and is adjusted as appropriate, but is preferably 100 nm to 1000 μm, more preferably 1 to 600 μm, even more preferably 10 to 400 μm, and particularly preferably 10 to 300 μm. If the thickness of the pattern frame is within this range, it is easy to obtain a pattern frame with an opening shape that has excellent pattern accuracy.

[0022] (Release layer) It is preferable to include a release layer on the wall surface of the opening of the pattern frame used in the present invention. The release layer has the function of easily peeling the formed thermoelectric element layer from the pattern frame. In this specification, "wall surface of opening in pattern frame" means the wall surface of the pattern frame that constitutes each opening provided in the pattern frame.

[0023] The release agent constituting the release layer is not particularly limited, but examples include fluorine-based release agents (fluorine atom-containing compounds; e.g., fluorine oil, polytetrafluoroethylene, etc.), silicone-based release agents (silicone compounds; e.g., silicone oil, silicone wax, silicone resin, polyorganosiloxane having polyoxyalkylene units, etc.), wax-based release agents (waxes; e.g., plant waxes such as carnauba wax, animal waxes such as wool wax, paraffins such as paraffin wax, polyethylene wax, oxidized polyethylene wax, etc.), higher fatty acids or their salts (e.g., metal salts, etc.), higher fatty acid esters, higher fatty acid amides, mineral oil, etc. Among these, fluorine-based release agents and silicone-based release agents are preferred from the viewpoint of facilitating peeling after the formation of the thermoelectric element layer and after annealing treatment, and from the viewpoint of maintaining shape controllability of the thermoelectric element layer after peeling, and fluorine-based release agents are even more preferred from the viewpoint of peelability.

[0024] The thickness of the release layer is preferably 10 nm to 5 μm, more preferably 50 nm to 1 μm, and even more preferably 100 nm to 0.5 μm. When the thickness of the release layer is within this range, peeling after the formation of the thermoelectric element layer and after the annealing treatment becomes easier, and the shape controllability of the thermoelectric element layer after peeling is easily maintained.

[0025] The release layer is formed using the release agent described above. Methods for forming the release layer include various coating methods applied to the pattern frame, such as dip coating, spray coating, gravure coating, die coating, and doctor blade coating. The appropriate method is selected depending on the shape of the pattern frame, the properties of the release agent, etc.

[0026] <Pattern frame fixing process> In the method for manufacturing a thermoelectric conversion element of the present invention, it is preferable to include a step of fixing a pattern frame containing the ferromagnetic material to the substrate using the permanent magnet described above. The pattern frame can be fixed using known methods. For example, a pattern frame containing a ferromagnetic material can be fixed by placing it opposite a permanent magnet with a substrate in between. The permanent magnet is adjusted as appropriate depending on the type of ferromagnetic pattern frame, the substrate, and their thickness.

[0027] (substrate) In the thermoelectric conversion element of the present invention, a resin film that does not affect the decrease in electrical conductivity or increase in thermal conductivity of the thermoelectric element layer can be used as the substrate. Among these, polyimide film, polyamide film, polyetherimide film, polyaramid film, or polyamideimide film are preferred because they have excellent flexibility, maintain the performance of the thermoelectric element layer without thermal deformation even when a thin film of the thermoelectric element layer made of a thermoelectric semiconductor composition is annealed, and have high heat resistance and dimensional stability. Furthermore, polyimide film is particularly preferred because of its high versatility.

[0028] The thickness of the resin film is preferably 1 to 1000 μm, more preferably 5 to 500 μm, and even more preferably 10 to 100 μm, from the viewpoint of flexibility, heat resistance, and dimensional stability. Furthermore, the above resin film preferably has a 5% weight loss temperature of 300°C or higher, and more preferably 400°C or higher, as measured by thermogravimetric analysis. The heating dimensional change rate measured at 200°C in accordance with JIS K7133 (1999) is preferably 0.5% or less, and more preferably 0.3% or less. The linear expansion coefficient in the planar direction, as measured in accordance with JIS K7197 (2012), is 0.1 ppm·°C. -1 ~50 ppm·℃ -1 It is 0.1 ppm·℃ -1 ~30 ppm·℃ -1 It is preferable that it be so.

[0029] Furthermore, from the viewpoint of performing annealing at high temperatures, glass, silicon, ceramic, and metal can be used as substrates in the present invention. From the viewpoint of material cost and dimensional stability after heat treatment, the use of glass, silicon, and ceramic is more preferable. From the viewpoint of process and dimensional stability, the thickness of the substrate is preferably 100 to 1200 μm, more preferably 200 to 800 μm, and even more preferably 400 to 700 μm. Furthermore, electrodes, as described later, may be formed on the substrate, including the aforementioned resin film.

[0030] In the manufacturing method of the present invention, as described later, when the obtained thermoelectric element layer is used as a chip constituting the thermoelectric element layer, it is preferable to use a transfer substrate as the substrate. By using a transfer substrate, the obtained thermoelectric element layer can be transferred all at once onto, for example, an electrode on another substrate as a chip constituting the thermoelectric element layer. Examples of transfer substrates include glass, silicon, ceramic, metal, or plastic having a sacrificial layer. From the viewpoint of performing the annealing treatment at high temperatures, glass, silicon, ceramic, and metal are preferred, and from the viewpoint of adhesion to the sacrificial layer, material cost, and dimensional stability after heat treatment, glass, silicon, and ceramic are more preferred. From the viewpoint of process and dimensional stability, the thickness of the transfer substrate is preferably 100 to 1200 μm, more preferably 200 to 800 μm, and even more preferably 400 to 700 μm. The sacrificial layer is provided on the transfer substrate and has the function of easily peeling the obtained thermoelectric element layer from the transfer substrate as chips constituting the thermoelectric element layer. The material constituting the sacrificial layer is preferably a resin or a release agent. The resin is not particularly limited, but thermoplastic resins and curable resins can be used. The release agent constituting the sacrificial layer is not particularly limited, but examples include fluorine-based release agents (fluorine atom-containing compounds; for example, polytetrafluoroethylene, etc.), silicone-based release agents (silicone compounds; for example, silicone resins, polyorganosiloxanes having polyoxyalkylene units, etc.), higher fatty acids or their salts (for example, metal salts, etc.), higher fatty acid esters, higher fatty acid amides, etc. The thickness of the sacrificial layer is preferably 10 nm to 10 μm, more preferably 50 nm to 5 μm, and even more preferably 200 nm to 2 μm. When the thickness of the sacrificial layer is within this range, it becomes easier to peel off the thermoelectric element layer after annealing, and it is easier to maintain the thermoelectric performance of the chip of the thermoelectric element layer after peeling.

[0031] (Electrode formation process) The method for manufacturing the thermoelectric conversion element of the present invention may include an electrode formation step. The electrode formation step is a step of forming electrodes on a substrate. Examples of metal materials for the electrodes of thermoelectric conversion elements include copper, gold, nickel, aluminum, rhodium, platinum, chromium, palladium, stainless steel, molybdenum, tin, or alloys containing any of these metals. The thickness of the electrode layer is preferably 10 nm to 200 μm, more preferably 30 nm to 150 μm, and even more preferably 50 nm to 120 μm. If the thickness of the electrode layer is within the above range, the electrical conductivity will be high and the resistance low, and sufficient strength as an electrode can be obtained.

[0032] The electrodes are formed using the aforementioned metal material. Methods for forming electrodes include placing an electrode without a pattern on a substrate and then processing it into a predetermined pattern shape by known physical or chemical treatments, mainly photolithography, or by a combination of these methods; or by directly forming the electrode pattern using screen printing, inkjet printing, or the like. Methods for forming electrodes without pre-formed patterns include PVD (Physical Vapor Deposition) such as vacuum deposition, sputtering, and ion plating; dry processes such as CVD (Chemical Vapor Deposition) such as thermal CVD and atomic layer deposition (ALD); wet processes such as various coatings and electrodeposition methods such as dip coating, spin coating, spray coating, gravure coating, die coating, and doctor blade coating; silver halide method; electrolytic plating; electroless plating; and metal foil lamination, which are selected appropriately depending on the electrode material. In order to maintain thermoelectric performance, electrodes used in this invention require high conductivity and high thermal conductivity; therefore, it is preferable to use electrodes formed by plating or vacuum deposition. Vacuum deposition methods such as vacuum evaporation and sputtering, as well as electroplating and electroless plating, are preferred because they can easily achieve high conductivity and high thermal conductivity. Depending on the dimensions and dimensional accuracy requirements of the formed pattern, a hard mask such as a metal mask can be used to easily form the pattern.

[0033] <Thermoelectric semiconductor composition filling process> The thermoelectric semiconductor composition filling step is a step of filling the openings of the pattern frame on the substrate obtained in the pattern frame formation step with the thermoelectric semiconductor composition containing the thermoelectric semiconductor material. For example, in Figure 1(c), the step is to fill the openings 3s of the pattern frame 2 made of stainless steel 2' prepared in (b) with a thermoelectric semiconductor composition containing a P-type thermoelectric semiconductor material and a thermoelectric semiconductor composition containing an N-type thermoelectric semiconductor material into predetermined openings. Known methods for filling the openings of a pattern layer with a thermoelectric semiconductor composition include screen printing, flexographic printing, gravure printing, spin coating, die coating, spray coating, bar coating, doctor blade coating, and dispensing. From the viewpoint of filling accuracy and manufacturing efficiency, screen printing, stencil printing, and dispensing are preferred.

[0034] <Thermoelectric element layer formation process> The thermoelectric element layer formation step is a step of drying the thermoelectric semiconductor composition containing the thermoelectric semiconductor material filled in the thermoelectric semiconductor composition filling step to form a thermoelectric element layer. For example, in Figure 1(c), the thermoelectric semiconductor composition containing the P-type thermoelectric semiconductor material and the thermoelectric semiconductor composition containing the N-type thermoelectric semiconductor material filled in the opening 3 are dried to form a P-type thermoelectric element layer 4b and an N-type thermoelectric element layer 4a. As drying methods, conventionally known drying methods such as hot air drying, hot roll drying, infrared irradiation, etc. can be adopted. The heating temperature is usually 80 to 150 °C, and the heating time varies depending on the heating method, but is usually several seconds to several tens of minutes. When a solvent is used in the preparation of the thermoelectric semiconductor composition, the heating temperature is not particularly limited as long as it is within the temperature range capable of drying the used solvent.

[0035] (Thermoelectric element layer) The thermoelectric element layer used in the present invention (hereinafter sometimes referred to as "thin film of thermoelectric element layer") is composed of a thermoelectric semiconductor composition containing a thermoelectric semiconductor material. Preferably, it is composed of a thermoelectric semiconductor composition containing a thermoelectric semiconductor material (hereinafter sometimes referred to as "thermoelectric semiconductor fine particles"), a heat-resistant resin, and an ionic liquid and / or an inorganic ionic compound.

[0036] (Thermoelectric semiconductor material) The thermoelectric semiconductor material used in the present invention, that is, the thermoelectric semiconductor material contained in the thermoelectric element layer, is not particularly limited as long as it 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; ZnSb, Zn3Sb 2、 zinc-antimony-based thermoelectric semiconductor materials such as 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, FeVTiAl, and sulfide-based thermoelectric semiconductor materials such as TiS2 are used. Among these, bismuth-tellurium-based thermoelectric semiconductor materials, telluride-based thermoelectric semiconductor materials, antimony-tellurium-based thermoelectric semiconductor materials, or bismuth selenide-based thermoelectric semiconductor materials are preferred.

[0037] Furthermore, from the perspective of thermoelectric performance, it is more preferable that it is a bismuth-tellurium-based thermoelectric semiconductor material such as P-type bismuth telluride or N-type bismuth telluride. The P-type bismuth telluride has holes as carriers and a positive value for 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. When X is greater than 0 and less than or equal to 0.8, the Seebeck coefficient and electrical conductivity increase, and the characteristics as a P-type thermoelectric element are maintained, which is preferable. In addition, the N-type bismuth telluride has electrons as carriers and a negative value for the Seebeck coefficient. For example, Bi2Te 3-Y Se Y represented by is preferably used. In this case, Y is preferably 0 ≤ Y ≤ 3 (when Y = 0: Bi2Te3), more preferably 0 < Y ≤ 2.7. When Y is 0 or more and 3 or less, the Seebeck coefficient and electrical conductivity increase, and the characteristics as an N-type thermoelectric element are maintained, which is preferable.

[0038] The thermoelectric semiconductor fine particles used in the thermoelectric semiconductor composition are those obtained by pulverizing the above-described thermoelectric semiconductor material to a predetermined size using a pulverizing device or the like.

[0039] The blending amount of the thermoelectric semiconductor fine particles in the thermoelectric semiconductor composition is preferably 30 to 99% by mass. More preferably, it is 50 to 96% by mass, and still more preferably, it is 70 to 95% by mass. When the blending amount of the thermoelectric semiconductor fine particles is within the above range, the Seebeck coefficient (absolute value of the Peltier coefficient) is large, the decrease in electrical conductivity is suppressed, and only the thermal conductivity decreases, so that high thermoelectric performance is exhibited, and a film having sufficient film strength and flexibility is obtained, which is preferable.

[0040] The average particle size of the thermoelectric semiconductor fine 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 this range, uniform dispersion is easily achieved, and the electrical conductivity can be increased. The method for obtaining thermoelectric semiconductor fine particles by pulverizing the thermoelectric semiconductor material is not particularly limited, and the material can be pulverized to a predetermined size using known fine pulverization equipment such as a jet mill, ball mill, bead mill, colloid mill, or roller mill. The average particle size of the thermoelectric semiconductor nanoparticles was obtained by measuring with a laser diffraction particle size analyzer (Malvern Mastersizer 3000) and was taken as the median value of the particle size distribution.

[0041] Furthermore, it is preferable that the thermoelectric semiconductor nanoparticles are pre-heat-treated (the "heat treatment" referred to here is different from the "annealing treatment" performed in the annealing process as described in this invention). By performing the heat treatment, the crystallinity of the thermoelectric semiconductor nanoparticles is improved, and the surface oxide film of the thermoelectric semiconductor nanoparticles is removed, thereby increasing the Seebeck coefficient or Peltier coefficient of the thermoelectric conversion material and further improving the thermoelectric figure of merit. The heat treatment is not particularly limited, but it is preferable to perform it under an inert gas atmosphere such as nitrogen or argon, a reducing gas atmosphere such as hydrogen, or under vacuum conditions, with controlled gas flow rates, before preparing the thermoelectric semiconductor composition, so as not to adversely affect the thermoelectric semiconductor nanoparticles, and it is more preferable to perform it under a mixed gas atmosphere of an inert gas and a reducing gas. The specific temperature conditions depend on the thermoelectric semiconductor nanoparticles used, but it is generally preferable to perform the treatment at a temperature below the melting point of the nanoparticles, and at 100 to 1500°C for several minutes to several tens of hours.

[0042] (Heat-resistant resin) In the thermoelectric semiconductor composition used in the present invention, a heat-resistant resin is preferably used, from the viewpoint of performing an annealing treatment of the thermoelectric semiconductor material at a high temperature after forming the thermoelectric element layer. It acts as a binder between the thermoelectric semiconductor material (thermoelectric semiconductor nanoparticles), which can improve the flexibility of the thermoelectric conversion module and facilitate the formation of a thin film by coating, etc. The heat-resistant resin is not particularly limited, but a heat-resistant resin is preferred in which the mechanical strength and various physical properties such as thermal conductivity of the resin are not impaired when the thermoelectric semiconductor nanoparticles are grown in crystal form by annealing or the like in a thin film made of the thermoelectric semiconductor composition. The heat-resistant resin is preferably polyamide resin, polyamide-imide resin, polyimide resin, or epoxy resin, as these offer higher heat resistance and do not adversely affect the crystal growth of thermoelectric semiconductor nanoparticles in the thin film. Polyamide resin, polyamide-imide resin, or polyimide resin is more preferred due to its excellent flexibility. When a polyimide film is used as the substrate, as described later, polyimide resin is more preferred as the heat-resistant resin due to its adhesion to the polyimide film. In this invention, polyimide resin refers collectively to polyimide and its precursors.

[0043] The heat-resistant resin preferably has a decomposition temperature of 300°C or higher. If the decomposition temperature is within the above range, as will be described later, even when a thin film made of a thermoelectric semiconductor composition is annealed, the binder function is not lost and flexibility can be maintained.

[0044] Furthermore, the heat-resistant resin preferably has a mass loss rate of 10% or less at 300°C as determined by thermogravimetric analysis (TG), more preferably 5% or less, and even more preferably 1% or less. 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 flexibility of the thermoelectric element layer can be maintained without losing its function as a binder.

[0045] The amount of the heat-resistant resin in the thermoelectric semiconductor composition is 0.1 to 40% by mass, preferably 0.5 to 20% by mass, more preferably 1 to 20% by mass, and even more preferably 2 to 15% by mass. When the amount of the heat-resistant resin is within the above range, it functions as a binder for the thermoelectric semiconductor material, making it easier to form a thin film, and resulting in a film that achieves both high thermoelectric performance and film strength.

[0046] (Ionic liquid) The ionic liquid used in this invention is a molten salt composed of a combination of cations and anions, and is a salt that can exist as a liquid in any temperature range from -50 to 500°C. Ionic liquids have characteristics such as extremely low vapor pressure and nonvolatility, excellent thermal and electrochemical stability, low viscosity, and high ionic conductivity, and can effectively suppress the reduction of electrical conductivity between thermoelectric semiconductor nanoparticles when used as a conductivity enhancer. In addition, ionic liquids exhibit high polarity based on their aprotic ionic structure and have excellent compatibility with heat-resistant resins, which can make the electrical conductivity of the thermoelectric element layer uniform.

[0047] Ionic liquids that are known or commercially available can be used. For example, nitrogen-containing cyclic cation compounds and their derivatives such as pyridinium, pyrimidinium, pyrazolium, pyrrolidinium, piperidinium, and imidazolium; amine cations of tetraalkylammonium and their derivatives; phosphine cations and their derivatives such as phosphonium, trialkylsulfonium, and tetraalkylphosphonium; and cationic components such as lithium cations and their derivatives, and 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 - 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 - Examples include those composed of anionic components such as the following.

[0048] Among the above ionic liquids, from the viewpoint of high-temperature stability, compatibility with thermoelectric semiconductor nanoparticles and resins, and suppression of a decrease in electrical conductivity in the gaps between thermoelectric semiconductor nanoparticles, it is preferable that the cationic component of the ionic liquid contains at least one selected from pyridinium cations and their derivatives, and imidazolium cations and their derivatives. It is preferable that the anionic component of the ionic liquid contains a halide anion, and Cl - , Br - and I - It is even more preferable to include at least one selected from the following.

[0049] Specific examples of ionic liquids containing pyridinium cations and their derivatives as cationic components 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-butyl-4-methylpyridinium bromide, 1-butyl-4-methylpyridinium hexafluorophosphate, and 1-butyl-4-methylpyridinium iodide. Among these, 1-butyl-4-methylpyridinium bromide, 1-butyl-4-methylpyridinium hexafluorophosphate, and 1-butyl-4-methylpyridinium iodide are preferred.

[0050] Furthermore, specific examples of ionic liquids containing imidazolium cations and their derivatives 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-methyl Examples 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. Among these, [1-butyl-3-(2-hydroxyethyl)imidazolium bromide] and [1-butyl-3-(2-hydroxyethyl)imidazolium tetrafluoroborate] are preferred.

[0051] The above ionic liquid has an electrical conductivity of 10 -7 Preferably S / cm or more, 10 -6 It is more preferable that the electrical conductivity is S / cm or higher. If the electrical conductivity is within the above range, the conductive additive can effectively suppress the reduction in electrical conductivity between thermoelectric semiconductor nanoparticles.

[0052] Furthermore, it is preferable that the above-mentioned ionic liquid has a decomposition temperature of 300°C or higher. If the decomposition temperature is within the above range, the effect as a conductive additive can be maintained even when the thin film of the thermoelectric element layer made of the thermoelectric semiconductor composition is annealed, as will be described later.

[0053] Furthermore, the above-mentioned ionic liquid preferably has a mass loss rate of 10% or less at 300°C as determined by thermogravimetric analysis (TG), more preferably 5% or less, and even more preferably 1% or less. If the mass loss rate is within the above range, the effect as a conductive additive can be maintained even when the thin film of the thermoelectric element layer made of the thermoelectric semiconductor composition is annealed, as will be described later.

[0054] The amount of the ionic liquid in the thermoelectric semiconductor composition is preferably 0.01 to 50% by mass, more preferably 0.5 to 30% by mass, and even more preferably 1.0 to 20% by mass. If the amount of the ionic liquid is within the above range, the decrease in electrical conductivity is effectively suppressed, and a film with high thermoelectric performance can be obtained.

[0055] (Inorganic ionic compounds) The inorganic ionic compound used in this invention is a compound composed of at least a cation and anion. Since the inorganic ionic compound is a solid at room temperature, has a melting point in the temperature range of 400 to 900°C, and possesses characteristics such as high ionic conductivity, it can be used as a conductivity enhancer to suppress the reduction in electrical conductivity between thermoelectric semiconductor nanoparticles.

[0056] Metal cations are used as the cations. Examples of metal cations include alkali metal cations, alkaline earth metal cations, typical metal cations, and transition metal cations, with alkali metal cations or alkaline earth metal cations being more preferred. Examples of alkali metal cations include Li + kaNa + , K + , Rb + , Cs + and Fr + These are some examples. Examples of alkaline earth metal cations include Mg 2+ Ca 2+ Sr 2+ and Ba 2+ These are some examples.

[0057] Examples of the anion include F - , Cl - , Br - , I - , OH - , CN - , NO3 - , NO2 - , ClO - , ClO2 - , ClO3 - , ClO4 - , CrO4 2- , HSO4 - , SCN - , BF4 - , PF6 - and the like.

[0058] Known or commercially available inorganic ionic compounds can be used. For example, cation components such as potassium cation, sodium cation, or lithium cation, and Cl - , AlCl4 - , Al2Cl7 - , ClO4 - and other chloride ions, Br - and other bromide ions, I - and other iodide ions, BF4 - , PF6 - and other fluoride ions, F(HF) n - and other halide anions, NO3 - , OH<00​​​​​​​​​​​​It is even more preferable to include at least one selected from the following.

[0060] Specific examples of inorganic ionic compounds containing potassium cations as a cationic component include KBr, KI, KCl, KF, KOH, and K2CO3. Among these, KBr and KI are preferred. Specific examples of inorganic ionic compounds containing a sodium cation as a cationic component include NaBr, NaI, NaOH, NaF, and Na2CO3. Among these, NaBr and NaI are preferred. Specific examples of inorganic ionic compounds containing lithium cations as cationic components include LiF, LiOH, and LiNO3. Among these, LiF and LiOH are preferred.

[0061] The above inorganic ionic compound has an electrical conductivity of 10 -7 Preferably S / cm or more, 10 -6 It is more preferable that the electrical conductivity is S / cm or higher. If the electrical conductivity is within the above range, the conductive additive can effectively suppress the reduction in electrical conductivity between thermoelectric semiconductor nanoparticles.

[0062] Furthermore, it is preferable that the above-mentioned inorganic ionic compound 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 the thin film of the thermoelectric element layer made of the thermoelectric semiconductor composition is annealed, as will be described later.

[0063] Furthermore, the above-mentioned inorganic ionic compound preferably has a mass loss rate of 10% or less at 400°C as determined by thermogravimetric analysis (TG), more preferably 5% or less, and even more preferably 1% or less. If the mass loss rate is within the above range, the effect as a conductive additive can be maintained even when the thin film of the thermoelectric element layer made of the thermoelectric semiconductor composition is annealed, as will be described later.

[0064] The amount of the inorganic ionic compound in the thermoelectric semiconductor composition is preferably 0.01 to 50% by mass, more preferably 0.5 to 30% by mass, and even more preferably 1.0 to 10% by mass. If the amount of the inorganic ionic compound is within the above range, the decrease in electrical conductivity can be effectively suppressed, and as a result, a film with improved thermoelectric performance can be obtained. When an inorganic ionic compound and an ionic liquid are used in combination, the total amount of the inorganic ionic compound and the ionic liquid in the thermoelectric semiconductor composition is preferably 0.01 to 50% by mass, more preferably 0.5 to 30% by mass, and even more preferably 1.0 to 10% by mass.

[0065] (Other additives) The thermoelectric semiconductor composition used in the present invention may, in addition to the components mentioned above, optionally contain other additives such as dispersants, film-forming aids, light stabilizers, antioxidants, tackifiers, plasticizers, colorants, resin stabilizers, fillers, pigments, conductive fillers, conductive polymers, and curing agents. These additives can be used individually or in combination of two or more.

[0066] (Method for preparing thermoelectric semiconductor compositions) The method for preparing the thermoelectric semiconductor composition used in the present invention is not particularly limited. The thermoelectric semiconductor composition can be prepared by mixing and dispersing the thermoelectric semiconductor fine particles, the heat-resistant resin, the ionic liquid and / or inorganic ionic compound, the other additives as needed, and a solvent using known methods such as an ultrasonic homogenizer, spiral mixer, planetary mixer, disperser, or hybrid mixer. Examples of the aforementioned solvents include toluene, ethyl acetate, methyl ethyl ketone, alcohol, tetrahydrofuran, methylpyrrolidone, and ethyl cellosolve. These solvents may be used individually or in mixtures of two or more. The solid content concentration of the thermoelectric semiconductor composition is not particularly limited, as long as the composition has a viscosity suitable for coating.

[0067] A thin film of the thermoelectric element layer made of the thermoelectric semiconductor composition can be formed by filling the openings of the pattern frame used in the present invention with the thermoelectric semiconductor composition and drying it. By forming the thermoelectric element layer in this way, a thermoelectric element layer with excellent shape controllability that reflects the shape of the openings of the pattern layer can be obtained.

[0068] The thickness of the thin film of the thermoelectric element layer made of the thermoelectric semiconductor composition is not particularly limited, but from the viewpoint of thermoelectric performance and film strength, it is preferably 100 nm to 1000 μm, more preferably 1 to 600 μm, even more preferably 10 to 400 μm, and most preferably 10 to 300 μm.

[0069] <Pattern frame removal process> The pattern frame peeling step is a step in which only the pattern frame, which includes the thermoelectric element layer formed in the thermoelectric element layer formation step, is peeled off from the substrate. For example, in Figure 1(d), the P-type thermoelectric element layer 4b and N-type thermoelectric element layer 4a formed in the opening 3 are peeled off the pattern frame 2 made of stainless steel 2' from the substrate 1, leaving the P-type thermoelectric element layer 4b and N-type thermoelectric element layer 4a on the substrate 1. As for the peeling method, there are no particular restrictions as long as the shape of the thermoelectric element layer is not damaged or the surface of the thermoelectric element layer is only slightly damaged when the pattern frame is peeled off, and there is no decrease in thermoelectric performance. It can be carried out by known methods. Furthermore, the pattern frame peeling process may also be performed after the annealing process described later, if the above conditions are satisfied after peeling.

[0070] <Annealing process> In the manufacturing method of the present invention, it is preferable to include a step of annealing the thermoelectric element layer. The annealing process is a step in the thermoelectric semiconductor composition drying process in which the thermoelectric element layer is further heat-treated after drying. By performing the annealing process, the thermoelectric performance is stabilized, and the thermoelectric semiconductor fine particles in the thermoelectric element layer (thin film) can be grown crystallly, thereby further improving the thermoelectric performance.

[0071] The annealing process is not particularly limited, but is usually carried out under an inert gas atmosphere such as nitrogen or argon, a reducing gas atmosphere, or under vacuum conditions with controlled gas flow. The temperature of the annealing process depends on the heat-resistant resin, ionic liquid, inorganic ionic compound used, and the heat resistance temperature of the substrate, etc. When a substrate with high heat resistance such as the aforementioned glass, silicon, ceramic, or metal is used, the annealing process is usually carried out at 250 to 650°C for several minutes to several tens of hours, preferably at 250 to 600°C for several minutes to several tens of hours. Furthermore, when a resin film such as polyimide film, polyamide film, polyetherimide film, polyaramid film, or polyamideimide film is used as the substrate, the process is usually carried out at 100 to 450°C for several minutes to several tens of hours, preferably at 150 to 400°C for several minutes to several tens of hours, more preferably at 200 to 375°C for several minutes to several tens of hours, and even more preferably at 250 to 350°C for several minutes to several tens of hours.

[0072] <Thermoelectric element layer peeling process> The manufacturing method of the present invention may include a step of peeling off the chips constituting the thermoelectric element layer after the annealing treatment. The thermoelectric element layer peeling process involves annealing the thermoelectric element layer and then peeling it off the substrate as chips that constitute the thermoelectric element layer.

[0073] In the thermoelectric element layer peeling process, there are no particular restrictions on the method for peeling the chips constituting the thermoelectric element layer from the substrate, as long as it is a method that allows for peeling. It can be carried out by a known method, and the chips may be peeled directly from the substrate, or multiple chips constituting the thermoelectric element layer may be transferred collectively onto another substrate or onto the electrodes of another substrate using the aforementioned transfer substrate. This can be appropriately adjusted depending on the configuration of the thermoelectric conversion element.

[0074] The chips constituting the thermoelectric element layer have excellent shape controllability. From the viewpoint of improving thermoelectric performance, it is preferable to form them in a configuration used for π-type or in-plane type thermoelectric conversion elements, and to form them so that they are connected via electrodes. In this case, when constructing a π-type thermoelectric element, for example, a pair of electrodes spaced apart from each other are provided on a substrate, a chip constituting a P-type thermoelectric element layer is provided on one electrode, and a chip constituting an N-type thermoelectric element layer is provided on the other electrode, also spaced apart from each other, and the upper surfaces of the chips constituting both thermoelectric element layers are electrically connected in series to the electrodes on the opposing substrate. From the viewpoint of efficiently obtaining high thermoelectric performance, it is preferable to use multiple pairs of chips constituting a P-type thermoelectric element layer and chips constituting an N-type thermoelectric element layer, with the electrodes of the opposing substrates interposed, electrically connected in series. Similarly, when constructing an in-plane thermoelectric conversion element, for example, one electrode is provided on a substrate, and a chip constituting a P-type thermoelectric element layer and a chip constituting an N-type thermoelectric element layer are provided on the surface of the electrode, such that the sides of both chips (for example, the surfaces perpendicular to the substrate) are in contact with or separated from each other, and the electrodes are electrically connected in series in the in-plane direction of the substrate (including a pair of extraction electrodes). From the viewpoint of efficiently obtaining high thermoelectric performance, it is preferable that in this configuration, the same number of chips constituting P-type thermoelectric element layers and chips constituting N-type thermoelectric element layers are alternately electrically connected in series in the in-plane direction of the substrate with electrodes in between.

[0075] The method for manufacturing a thermoelectric element of the present invention makes it possible to improve the shape controllability of the thermoelectric element layer in a simple manner. The configuration of the thermoelectric element is preferably one used for π-type or in-plane type thermoelectric elements. In either configuration, high integration of the thermoelectric element can be achieved.

[0076] [Thermoelectric conversion element] A thermoelectric conversion element obtained by the manufacturing method of the present invention includes a thermoelectric element layer obtained by a method for manufacturing a thermoelectric conversion element which includes a thermoelectric element layer made of a thermoelectric semiconductor composition containing a thermoelectric semiconductor material on a substrate, comprising the steps of: providing a pattern frame having openings on the substrate; filling the openings with the thermoelectric semiconductor composition; drying the thermoelectric semiconductor composition filled in the openings to form a thermoelectric element layer; and peeling the pattern frame from the substrate.

[0077] (Thermoelectric element layer) The thermoelectric element layer of the thermoelectric conversion element obtained by the manufacturing method of the present invention has a concave upper surface. Since the thermoelectric element layer is formed by filling the openings of the pattern frame with a thermoelectric semiconductor composition containing a thermoelectric semiconductor material, and then removing volatile components in the thermoelectric semiconductor composition by drying, the surface of the thermoelectric element layer corresponding to the opening on the opposite side of the pattern frame from the substrate side is not flat but concave. For example, in Figure 1(d), the upper surfaces of the N-type thermoelectric element layer 4a and the P-type thermoelectric element layer 4b may be concave. The shape and dimensions of the concave depressions are not constant, as they depend on the viscosity, volatile components, and drying conditions of the thermoelectric semiconductor composition. However, typically, the concave depressions are 1-30% of the thickness of the thermoelectric element layer.

[0078] The thermoelectric element layer of the thermoelectric conversion element obtained by the manufacturing method of the present invention may have streaky abrasion marks on its side surface that extend in a direction intersecting the substrate. This is presumed to be because, since the thermoelectric element layer is formed by filling the opening of the pattern frame with a thermoelectric semiconductor composition containing a thermoelectric semiconductor material, then drying it to form the thermoelectric element layer, and then peeling the pattern frame off the substrate, when the pattern frame is peeled off, physical interactions such as friction occur at the interface between the wall surface inside the opening of the pattern frame and the side surface of the thermoelectric element layer, resulting in streaky abrasion marks extending in a direction intersecting the substrate on the side surface of the thermoelectric element layer obtained on the substrate after peeling. For example, in Figure 1(d), streaky abrasion marks extending in a direction intersecting the substrate occur on either the side surface of the N-type thermoelectric element layer 4a or the P-type thermoelectric element layer 4b. The length, width, and number of streaky abrasions are not constant, as they depend on the surface hardness, surface roughness, and peeling conditions (peeling direction, peeling speed, etc.) of the wall surface within the pattern frame opening. However, the length of streaky abrasions is typically between 100 nm and 500 μm. [Industrial applicability]

[0079] According to the thermoelectric element manufacturing method of the present invention, a highly integrated thermoelectric element having a thermoelectric element layer with excellent shape controllability can be obtained by a simple manufacturing method. At the same time, since variations in the resistance values ​​of each of the multiple P-type thermoelectric element layer-N-type thermoelectric element layer pairs can be suppressed, an improvement in manufacturing yield can be expected. Furthermore, the thermoelectric conversion element obtained by the manufacturing method of the thermoelectric conversion element of the present invention can be made thinner (smaller and lighter). By forming a module from the thermoelectric conversion element obtained by the above-described manufacturing method, it is conceivable that it can be applied to power generation applications that convert waste heat from various combustion furnaces such as factories, waste incinerators, and cement incinerators, as well as exhaust heat from combustion gases of automobiles and waste heat from electronic equipment into electricity. For cooling applications, it is conceivable that it can be applied to temperature control of various sensors in the field of electronic equipment, such as CPUs (Central Processing Units) used in smartphones and various computers, as well as image sensors such as CMOS (Complementary Metal Oxide Semiconductor Image Sensors) and CCDs (Charge Coupled Devices), and MEMS (Micro Electro Mechanical Systems) and other light-receiving elements. [Explanation of Symbols]

[0080] 1: Circuit board 2: Pattern frame 2': Stainless steel 3s: opening 3D: Opening depth (pattern frame thickness) 3: Opening 4a: N-type thermoelectric element layer 4b: P type thermoelectric element layer 11a: Circuit board 11b: Opposing substrate 12a: Electrode 12b: Counter electrode 14a: N-type thermoelectric element layer 14b: P-type thermoelectric element layer

Claims

1. A method for manufacturing a thermoelectric conversion element, comprising a thermoelectric element layer on a substrate made of a thermoelectric semiconductor composition containing a thermoelectric semiconductor material and a heat-resistant resin, A step of providing a pattern frame having an opening on the substrate, A step of filling the opening with the thermoelectric semiconductor composition, The steps include drying the thermoelectric semiconductor composition filled in the opening to form a thermoelectric element layer, and peeling the pattern frame from the substrate. The wall surface of the opening in the pattern frame includes a release layer. A method for manufacturing a thermoelectric conversion element.

2. Furthermore, the method for manufacturing a thermoelectric element according to claim 1, further comprising the step of annealing the thermoelectric element layer.

3. The method for manufacturing a thermoelectric element according to claim 2, wherein the temperature of the annealing treatment is 250 to 600°C.

4. A method for manufacturing a thermoelectric element according to claim 2 or 3, comprising the step of peeling off the chips constituting the thermoelectric element layer after the annealing treatment.

5. A method for manufacturing a thermoelectric element according to any one of claims 1 to 4, wherein the substrate is a polyimide film, a polyamide film, a polyetherimide film, a polyaramid film, or a polyamideimide film.

6. A method for manufacturing a thermoelectric element according to any one of claims 1 to 5, wherein the pattern frame comprises stainless steel, copper, aluminum, or iron.

7. A method for manufacturing a thermoelectric element according to any one of claims 1 to 6, wherein the pattern frame includes a ferromagnetic material.

8. A method for manufacturing a thermoelectric element according to any one of claims 1 to 7, comprising the step of fixing the pattern frame to the substrate using a magnet.

9. A method for manufacturing a thermoelectric element according to any one of claims 1 to 8, wherein the thermoelectric semiconductor composition further comprises an ionic liquid and / or an inorganic ionic compound.

10. A method for manufacturing a thermoelectric element according to any one of claims 1 to 9, wherein the thermoelectric semiconductor material is a bismuth-tellurium-based thermoelectric semiconductor material, a telluride-based thermoelectric semiconductor material, an antimony-tellurium-based thermoelectric semiconductor material, or a bismuth selenide-based thermoelectric semiconductor material.

11. A method for manufacturing a thermoelectric element according to any one of claims 1 to 10, wherein the heat-resistant resin is a polyimide resin, a polyamide resin, a polyamide-imide resin, or an epoxy resin.

12. A method for manufacturing a thermoelectric element according to any one of claims 1 to 11, wherein the shape of the opening is one or more shapes selected from the group consisting of irregular shape, polyhedron shape, frustoconical shape, frustoelliptical shape, cylindrical shape, and elliptical cylindrical shape.

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