Thermoelectric conversion module

Abstract

Provided is a thin thermoelectric conversion module that does not have a support substrate and a solder layer, wherein electrodes M1 or M2 that are shared between adjacent p-type thermoelectric conversion material chips 3p and n-type thermoelectric conversion material chips 3n are arranged (wired) directly onto upper / lower surfaces of the p-type thermoelectric conversion material chips 3p and n-type thermoelectric conversion material chips 3n so as to straddle opposite insulation layers L1, L2 that span gaps between the p-type thermoelectric conversion material chips 3p and n-type thermoelectric conversion material chips 3n.

Description

thermoelectric conversion module

[0001] The present invention relates to a thermoelectric conversion module.

[0002] 2. Description of the Related Art Conventionally, as one of the means for effectively utilizing energy, there has been a device that directly converts thermal energy into electrical energy and vice versa using a thermoelectric conversion module that has a thermoelectric effect such as the Seebeck effect or the Peltier effect.

[0003] Known examples of such thermoelectric conversion modules include so-called π-type thermoelectric conversion elements. A π-type thermoelectric conversion element has a pair of electrodes spaced apart from each other on a substrate. For example, the lower surface of a P-type thermoelectric element is mounted on one electrode, and the lower surface of an N-type thermoelectric element is mounted on the other electrode, also spaced apart from each other. The upper surfaces of both types of thermoelectric elements are connected to the same electrode on the opposing substrate. Typically, multiple such basic units are configured within both substrates, electrically connected in series and thermally connected in parallel. In recent years, in order to fully commercialize products using thermoelectric conversion modules including such π-type thermoelectric conversion elements, various demands have arisen, such as thinner thermoelectric conversion modules, reduced component materials, and improved reliability. For example, Patent Documents 1 and 2 disclose thermoelectric conversion modules using the aforementioned π-type thermoelectric conversion elements.

[0004] JP 2001-102643 A International Publication No. 2017 / 074003 A

[0005] However, the thermoelectric conversion module of Patent Document 1 is composed of a P-type element made of a P-type thermoelectric material, an N-type element made of an N-type thermoelectric material, and two substrates having metal electrodes capable of joining these dissimilar elements in pairs to form PN junction pairs, and since a substrate is used to support at least the metal electrodes and elements, no consideration is given to reducing the thickness of the thermoelectric conversion module, reducing the number of constituent materials, etc. Similarly, the thermoelectric conversion module of Patent Document 2 does not include a substrate that will serve as a support in the final configuration, but a contact thermal conduction layer is provided where the substrate would normally be placed, and this contact thermal conduction layer is made of the same type of aluminum nitride, silicon nitride, alumina, etc. as commonly used substrates and also functions as a support, so no consideration is given to reducing the thickness of the thermoelectric conversion module, reducing the number of constituent materials, etc.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a thin thermoelectric conversion module that does not have a support substrate or a solder layer.

[0007] As a result of extensive research aimed at solving the above problems, the present inventors discovered a thermoelectric conversion module configured such that a common electrode between adjacent chips of P-type thermoelectric conversion material and N-type thermoelectric conversion material is provided across an insulating layer disposed in the center of the electrode, thereby completing the present invention. That is, the present invention provides the following [1] to

[15] . [1] A thermoelectric conversion module including chips of P-type thermoelectric conversion material and chips of N-type thermoelectric conversion material arranged alternately and spaced apart, a first insulating layer, a second insulating layer, a first electrode, and a second electrode, wherein the first insulating layer is provided on a first surface side of the chip of P-type thermoelectric conversion material and a first surface side of the adjacent chip of N-type thermoelectric conversion material so as to straddle a gap between the chip of P-type thermoelectric conversion material and the adjacent chip of N-type thermoelectric conversion material, and the second insulating layer is provided on a second surface side of the chip of P-type thermoelectric conversion material and a second surface side of the adjacent chip of N-type thermoelectric conversion material so as to straddle a gap between the chip of P-type thermoelectric conversion material and the adjacent chip of N-type thermoelectric conversion material, and the first insulating layer and the second insulating layer are provided opposite each other with the gap interposed therebetween, and the chip of P-type thermoelectric conversion material and the chip of N-type thermoelectric conversion material are a first electrode provided on a first surface side of the P-type thermoelectric conversion material chip and on a first surface side of the N-type thermoelectric conversion material chip adjacent to the P-type thermoelectric conversion material chip and the N-type thermoelectric conversion material chip in an arrangement direction, with the first insulating layer interposed therebetween, and straddling the first insulating layer; and a second electrode provided on a second surface side of the N-type thermoelectric conversion material chip and on a second surface side of the P-type thermoelectric conversion material chip adjacent to the P-type thermoelectric conversion material chip and the N-type thermoelectric conversion material chip in an arrangement direction, with the second insulating layer interposed therebetween, and straddling the second insulating layer, electrically connected alternately in this order in the arrangement direction of the P-type thermoelectric conversion material chip and the N-type thermoelectric conversion material chip, and gaps defined between the first insulating layer, the second insulating layer, the P-type thermoelectric conversion material chip and the N-type thermoelectric conversion material chip are maintained.[2] The thermoelectric conversion module according to [1] above, wherein a first protective layer is provided on the first electrode and the first insulating layer, and a second protective layer is provided on the second electrode and the second insulating layer. [3] The thermoelectric conversion module according to [2] above, wherein heat dissipation layers are further provided on the first protective layer and the second protective layer. [4] The thermoelectric conversion module according to any one of [1] to [3] above, wherein a frame is provided around the thermoelectric conversion module. [5] The thermoelectric conversion module according to [4] above, wherein the frame is made of metal, ceramic, or resin. [6] The thermoelectric conversion module according to any one of [1] to [5] above, wherein the first insulating layer and the second insulating layer are each independently selected from polyimide resin, silicone resin, rubber-based resin, acrylic resin, olefin-based resin, maleimide resin, and epoxy resin. [7] The thermoelectric conversion module according to [2] or [3] above, wherein the first protective layer and the second protective layer are each independently selected from insulating resin and ceramic. [8] The thermoelectric conversion module according to [3] above, wherein the heat dissipation layer is selected from gold, silver, copper, nickel, tin, iron, chromium, platinum, palladium, rhodium, iridium, ruthenium, osmium, indium, zinc, molybdenum, manganese, titanium, aluminum, stainless steel, and brass. [9] The thermoelectric conversion module according to any one of [1] to [8] above, wherein the first insulating layer and the second insulating layer each independently have a thickness of 5 to 200 μm.

[10] The thermoelectric conversion module according to any one of [2], [3], and [7] above, wherein the first protective layer and the second protective layer each independently have a thickness of 5 to 300 μm.

[11] The thermoelectric conversion module according to [3] or [8] above, wherein the heat dissipation layer has a thickness of 5 to 550 μm.

[12] The thermoelectric conversion module according to any one of [1] to

[11] above, wherein the first electrode and the second electrode are each independently selected from gold, silver, copper, nickel, chromium, platinum, palladium, rhodium, molybdenum, aluminum, or an alloy containing any of these metals.

[13] The thermoelectric conversion module according to any one of [1] to

[12] above, wherein the first electrode and the second electrode are each independently formed of at least one film selected from the group consisting of a sputtered film, a vapor-deposited film, and a plated film.

[14] The thermoelectric conversion module according to any one of [1] to

[13] above, wherein the chip of P-type thermoelectric conversion material and the chip of N-type thermoelectric conversion material are made of a thermoelectric semiconductor composition.

[15] The thermoelectric conversion module according to

[14] above, wherein the thermoelectric semiconductor composition contains a thermoelectric semiconductor material, a resin, and one or both of an ionic liquid and an inorganic ionic compound.

[0008] According to the present invention, it is possible to provide a thin thermoelectric conversion module that does not have a support substrate or a solder layer.

[0009] 1A to 1C are cross-sectional configuration diagrams showing a first embodiment of a thermoelectric conversion module according to the present invention, a second embodiment of a thermoelectric conversion module according to the present invention, and a third embodiment of a thermoelectric conversion module according to the present invention.

[0010] [Thermoelectric Conversion Module] The thermoelectric conversion module of the present invention is a thermoelectric conversion module including chips of P-type thermoelectric conversion material and chips of N-type thermoelectric conversion material arranged alternately and spaced apart, a first insulating layer, a second insulating layer, a first electrode, and a second electrode, wherein the first insulating layer is provided on a first surface side of the chip of P-type thermoelectric conversion material and a first surface side of the adjacent chip of N-type thermoelectric conversion material so as to straddle a gap between the chip of P-type thermoelectric conversion material and the adjacent chip of N-type thermoelectric conversion material, the second insulating layer is provided on a second surface side of the chip of P-type thermoelectric conversion material and a second surface side of the adjacent chip of N-type thermoelectric conversion material so as to straddle a gap between the chip of P-type thermoelectric conversion material and the adjacent chip of N-type thermoelectric conversion material, and the first insulating layer and the second insulating layer are provided opposite each other with the gap interposed therebetween, and the chip of P-type thermoelectric conversion material and the chip of N-type thermoelectric conversion material are a first electrode provided on a first surface side of the P-type thermoelectric conversion material chip and on a first surface side of the N-type thermoelectric conversion material chip adjacent to the arrangement direction of the P-type thermoelectric conversion material chips and the N-type thermoelectric conversion material chips, with the first insulating layer interposed therebetween, and straddling the first insulating layer; and a second electrode provided on a second surface side of the N-type thermoelectric conversion material chip and on a second surface side of the P-type thermoelectric conversion material chip adjacent to the arrangement direction of the P-type thermoelectric conversion material chips and the N-type thermoelectric conversion material chips, with the second insulating layer interposed therebetween, and straddling the second insulating layer, the electrodes are electrically connected alternately in this order in the arrangement direction of the P-type thermoelectric conversion material chips and the N-type thermoelectric conversion material chips, and gaps defined between the first insulating layer, the second insulating layer, the P-type thermoelectric conversion material chips, and the N-type thermoelectric conversion material chips are maintained. In the thermoelectric conversion module of the present invention, the common electrodes for adjacent chips of P-type thermoelectric conversion material and chips of N-type thermoelectric conversion material are directly arranged (wired) on the top and bottom surfaces of the chips of P-type thermoelectric conversion material and the chips of N-type thermoelectric conversion material so as to straddle each other with an insulating layer placed in the center of the electrode interposed, thereby eliminating the need to provide the electrodes on a support substrate, making the support substrate and solder layer that were previously used unnecessary and enabling the thermoelectric conversion module to be made thinner.In this specification, the term "support substrate" refers to a substrate material used as a support for a thermoelectric conversion material, an electrode, or the like, and is not particularly limited, but examples thereof include glass, silicon, ceramics, resins, and the like that are commonly used in the thermoelectric field.

[0011] In this specification, the first insulating layer and the second insulating layer, the first electrode and the second electrode, the first protective layer and the second protective layer, and the first heat dissipation layer and the second heat dissipation layer may be simply referred to as "insulating layer," "electrode," "protective layer," and "heat dissipation layer," respectively. Furthermore, "chips of P-type thermoelectric conversion material and chips of N-type thermoelectric conversion material" may be simply referred to as "chips of thermoelectric conversion material" or "chips." The thermoelectric conversion module of the present invention will now be described with reference to the drawings.

[0012] FIG. 1 is a cross-sectional view showing a first embodiment of a thermoelectric conversion module of the present invention. The thermoelectric conversion module 1 includes chips 3p of P-type thermoelectric conversion material and chips 3n of N-type thermoelectric conversion material, which are alternately arranged at a distance from each other, a first insulating layer L1, a second insulating layer L2, a first electrode M1, and a second electrode M2. The first insulating layer L1 is formed on a first surface 3p of the chip 3p of the P-type thermoelectric conversion material. １ the first surface 3n of the chip 3n of N-type thermoelectric conversion material adjacent to the side １ The second insulating layer L2 is provided on the second surface 3p of the P-type thermoelectric conversion chip 3P so as to bridge the gap between the chip 3p of the P-type thermoelectric conversion material and the adjacent chip 3n of the N-type thermoelectric conversion material. ２ the second surface 3n of the chip 3n of N-type thermoelectric conversion material adjacent to the side ２ The first insulating layer L1 and the second insulating layer L2 are provided on the first surface 3p of the P-type thermoelectric conversion material chip 3p and the adjacent N-type thermoelectric conversion material chip 3n, so as to straddle the gap between the P-type thermoelectric conversion material chip 3p and the adjacent N-type thermoelectric conversion material chip 3n, and the first insulating layer L1 and the second insulating layer L2 are provided opposite to each other with the gap interposed therebetween, and the P-type thermoelectric conversion material chip 3p and the N-type thermoelectric conversion material chip 3n are provided on the first surface 3p of the P-type thermoelectric conversion material chip 3p and the adjacent N-type thermoelectric conversion material chip 3n, so as to straddle the gap between the P-type thermoelectric conversion material chip 3p and the adjacent N-type thermoelectric conversion material chip 3n. １ the first surface 3n of the chip 3n of N-type thermoelectric conversion material adjacent to the chip arrangement direction 4 １a first electrode M1 provided on the side of the N-type thermoelectric conversion material chip, with a first insulating layer L1 interposed therebetween, and further provided so as to straddle the first insulating layer L1; ２ the second surface 3p of the chip of P-type thermoelectric conversion material adjacent to the chip arrangement direction 4 ２ The first and second electrodes M1 and M2 are electrically connected alternately in this order in the chip arrangement direction 4, with a second insulating layer L2 interposed therebetween, and gaps are maintained between the first insulating layer L1, the second insulating layer L2, the chips 3p made of P-type thermoelectric conversion material, and the chips 3n made of N-type thermoelectric conversion material. Here, reference numeral 2 denotes a frame that also functions to seal the outer periphery of the thermoelectric conversion module. This embodiment does not have a supporting substrate or a solder layer used to bond the electrodes.

[0013] 2 is a cross-sectional view showing a second embodiment of a thermoelectric conversion module of the present invention. The thermoelectric conversion module 11 has a configuration similar to that of FIG. 1 , except that a first protective layer H1 is provided on the first electrode M1 and the first insulating layer L1, and a second protective layer H2 is provided on the second electrode M2 ​​and the second insulating layer L2. Reference numeral 12 denotes a contact hole for an extraction electrode. Naturally, this embodiment also does not have a support substrate or a solder layer used for joining the electrodes.

[0014] 3 is a cross-sectional view showing a third embodiment of a thermoelectric conversion module of the present invention. The thermoelectric conversion module 21 has a configuration similar to that of FIG. 2 , except that a first heat dissipation layer T1 is provided on the first protective layer H1 and a second heat dissipation layer T2 is provided on the second protective layer H2. Reference numeral 13 denotes an extraction electrode. Naturally, this embodiment also does not have a support substrate or a solder layer used for joining the electrodes.

[0015] (Insulating Layer) The thermoelectric conversion module of the present invention includes a first insulating layer and a second insulating layer. The insulating layers function to provide insulation between adjacent chips of P-type thermoelectric conversion material and chips of N-type thermoelectric conversion material, and to maintain a gap between chips of P-type thermoelectric conversion material and chips of N-type thermoelectric conversion material. The first insulating layer and the second insulating layer are not particularly limited, but are each independently preferably selected from polyimide resin, silicone resin, rubber-based resin, acrylic resin, olefin-based resin, maleimide resin, and epoxy resin.

[0016] The method for forming the insulating layer is preferably a method that does not fill the gaps between the chips of P-type thermoelectric conversion material and the chips of N-type thermoelectric conversion material, or the gaps around them. For example, known methods such as lamination can be used. The method for patterning the insulating layer is not particularly limited, and known methods can be used. For example, it is preferable to form contact holes by exposure-development treatment or laser irradiation so that the upper and lower surfaces of the chips of P-type thermoelectric conversion material and the chips of N-type thermoelectric conversion material are exposed. In the exposure-development treatment method, for example, when a photosensitive resin is used, a desired photomask for forming contact holes is inserted, and exposure is performed with ultraviolet light or the like, followed by processing using a developer or the like. In addition, in the case of laser irradiation, for example, processing methods using a carbon dioxide laser, ultraviolet laser, or the like can be used.

[0017] The thickness of each insulating layer is preferably 5 to 200 μm, more preferably 10 to 100 μm, and even more preferably 15 to 30 μm. When the thickness of the insulating layer is within this range, insulation between adjacent electrodes can be ensured and the thickness of the thermoelectric conversion module is not increased.

[0018] (Electrodes) The thermoelectric conversion module of the present invention includes a first electrode and a second electrode. The electrodes cover the insulating layer, the P-type thermoelectric conversion material chip, and the N-type conversion material chip so as to straddle the upper and lower surfaces thereof, and are not formed directly using a support substrate or the like. The electrode materials are each independently selected from gold, silver, copper, nickel, chromium, platinum, palladium, rhodium, molybdenum, aluminum, or an alloy containing any of these metals. The electrodes cover the insulating layer, the P-type thermoelectric conversion material chip, and the N-type conversion material chip so as to straddle the upper and lower surfaces thereof, and from the viewpoint of maintaining high thermoelectric performance, the electrodes are preferably formed of at least one film selected from the group consisting of a sputtered film, a vapor-deposited film, and a plated film.

[0019] Methods for patterning an electrode material to form an electrode include methods of processing into a predetermined pattern shape by known physical or chemical treatments, mainly photolithography, or a combination of these. Specific methods for processing into a predetermined pattern shape include, for example, a method of directly forming by exposure and development, a method of forming by etching after exposure and development, and a method of directly forming by laser processing. Among these, the method of directly forming by exposure and development is particularly preferred from the viewpoints of pattern accuracy and takt time.

[0020] The thickness of the electrode depends on the thickness of the insulating layer used, but is independently preferably 5 to 200 μm, more preferably 8 to 150 μm, and even more preferably 10 to 120 μm. When the electrode thickness is within the above range, the electrical conductivity is high and the resistance is low, and sufficient strength as an electrode can be obtained.

[0021] The thermoelectric conversion material chip used in the present invention is not particularly limited and may be made of a thermoelectric semiconductor material or a thin film made of a thermoelectric semiconductor composition. From the viewpoints of flexibility, thinness, and thermoelectric performance, it is preferable that the chip be made of a thin film made of a thermoelectric semiconductor composition containing a thermoelectric semiconductor material (hereinafter sometimes referred to as "thermoelectric semiconductor particles"), a resin, an ionic liquid, and / or an inorganic ionic compound. In this specification, the terms "thermoelectric conversion material" and "thermoelectric conversion material chip" are synonymous, and are also synonymous with "thermoelectric conversion material layer."

[0022] (Thermoelectric Semiconductor Material) The thermoelectric semiconductor material used in the thermoelectric conversion material chip is preferably pulverized to a predetermined size using, for example, a fine grinding device, and used as thermoelectric semiconductor particles (hereinafter, the thermoelectric semiconductor material may be referred to as "thermoelectric semiconductor particles"). The particle size of the thermoelectric semiconductor particles is preferably 10 nm to 100 μm, more preferably 20 nm to 50 μm, and even more preferably 30 nm to 30 μm. The average particle size of the thermoelectric semiconductor particles is obtained by measurement using a laser diffraction particle size analyzer (Malvern, Mastersizer 3000), and is taken as the median of the particle size distribution.

[0023] In the thermoelectric conversion material chips used in the present invention, the thermoelectric semiconductor materials constituting the P-type thermoelectric conversion material chips and the N-type thermoelectric conversion material chips are not particularly limited as long as they are materials that can generate thermoelectric power when a temperature difference is applied, and examples thereof include 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, Zn ３ Sb ２、 Zn ４ Sb ３ Zinc-antimony based thermoelectric semiconductor materials such as silicon-germanium based thermoelectric semiconductor materials such as silicon germanium; Bi ２ Se ３ Bismuth selenide-based thermoelectric semiconductor materials such as β-FeSi ２ , CrSi ２ , MnSi １．７３ , Mg ２ Silicide-based thermoelectric semiconductor materials such as Si; oxide-based thermoelectric semiconductor materials; Heusler materials such as FeVAl, FeVAlSi, and FeVTiAl; TiS ２ Sulfide-based thermoelectric semiconductor materials such as the above are used.

[0024] Among these, the thermoelectric semiconductor material used in the present invention is preferably a bismuth-tellurium-based thermoelectric semiconductor material such as P-type bismuth telluride or N-type bismuth telluride. The P-type bismuth telluride has positive holes as carriers and a positive Seebeck coefficient, for example, BiＸ Te ３ Sb ２－Ｘ In this case, X is preferably 0<X≦0.8, and more preferably 0.4≦X≦0.6. When X is greater than 0 and not greater than 0.8, the Seebeck coefficient and electrical conductivity are increased, and the properties as a P-type thermoelectric conversion material are maintained, which is preferable. In addition, the N-type bismuth telluride has electrons as carriers and a negative Seebeck coefficient, for example, Bi ２ Te ３－Ｙ Se Ｙ In this case, Y is preferably 0≦Y≦3 (when Y=0: Bi ２ Te ３ ) and more preferably 0.1<Y≦2.7. 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 maintained, which is preferable.

[0025] The content of the thermoelectric semiconductor particles in the thermoelectric semiconductor composition is preferably 30 to 99% by mass, more preferably 50 to 96% by mass, and even more preferably 70 to 95% by mass. When the content of the thermoelectric semiconductor particles is within the above range, the Seebeck coefficient (absolute value of the Peltier coefficient) is large, and a 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.

[0026] The thermoelectric semiconductor particles are preferably subjected to an annealing treatment (hereinafter, sometimes referred to as "annealing treatment A"). By performing annealing treatment A, the crystallinity of the thermoelectric semiconductor particles is improved, and further, the surface oxide film of the thermoelectric semiconductor particles is removed, thereby increasing the Seebeck coefficient (absolute value of the Peltier coefficient) of the thermoelectric conversion material and further improving the thermoelectric figure of merit.

[0027] (Resin) The resin used in the present invention has the effect of physically bonding the thermoelectric semiconductor material (thermoelectric semiconductor particles) together, and can increase the flexibility of the thermoelectric conversion module and facilitate the formation of a thin film by coating, etc. The resin is preferably a heat-resistant resin or a binder resin.

[0028] The heat-resistant resin maintains its various physical properties, such as mechanical strength and thermal conductivity, without being impaired when the thin film made of the thermoelectric semiconductor composition is annealed to cause crystal growth of the thermoelectric semiconductor particles. The heat-resistant resin is preferably a polyamide resin, a polyamideimide resin, a polyimide resin, or an epoxy resin, because it has higher heat resistance and does not adversely affect the crystal growth of the thermoelectric semiconductor particles in the thin film, and more preferably a polyamide resin, a polyamideimide resin, or a polyimide resin because it has excellent flexibility.

[0029] The heat-resistant 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 will be able to maintain flexibility even when a thin film made of the thermoelectric semiconductor composition is annealed, as will be described later.

[0030] Furthermore, the heat-resistant 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, the resin will not lose its function as a binder and the flexibility of the thermoelectric conversion material chip can be maintained, even when a thin film made of the thermoelectric semiconductor composition is annealed, as described below.

[0031] The content 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 content of the heat-resistant resin is within the above range, the resin functions as a binder for the thermoelectric semiconductor material, facilitating the formation of a thin film, and a film that achieves both high thermoelectric performance and film strength is obtained, and a resin portion is present on the outer surface of the chip of the thermoelectric conversion material.

[0032] The binder resin also facilitates peeling of the thermoelectric conversion material from the substrate, such as glass, alumina, or silicon, used in producing the chip after firing (annealing) treatment (corresponding to "annealing treatment B" described later, the same applies hereinafter).

[0033] The binder resin refers to a resin that decomposes at 90% by mass or more at the baking (annealing) temperature or higher, more preferably a resin that decomposes at 95% by mass or more, and particularly preferably a resin that decomposes at 99% by mass or more. Furthermore, a resin that maintains various physical properties such as mechanical strength and thermal conductivity without being impaired when a coating film (thin film) made of the thermoelectric semiconductor composition is subjected to a baking (annealing) treatment or the like to cause crystal growth of thermoelectric semiconductor particles is more preferred. When a resin that decomposes at 90% by mass or more at the baking (annealing) temperature or higher, i.e., a resin that decomposes at a temperature lower than the heat-resistant resin described above, is used as the binder resin, the binder resin is decomposed by baking, thereby reducing the content of the binder resin, which serves as an insulating component, in the baked body. This promotes crystal growth of the thermoelectric semiconductor particles in the thermoelectric semiconductor composition, thereby reducing voids in the thermoelectric conversion material layer and improving the filling rate. Whether or not a resin decomposes to a predetermined extent (e.g., 90% by mass) at or above the baking (annealing) temperature is determined by measuring the mass loss rate (the value obtained by dividing the mass after decomposition by the mass before decomposition) at the baking (annealing) temperature by thermogravimetry (TG).

[0034] Thermoplastic resins and curable resins can be used as such binder resins. Examples of thermoplastic resins include polyolefin resins such as polyethylene, polypropylene, polyisobutylene, and polymethylpentene; polycarbonate; thermoplastic polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polyvinyl polymers such as polystyrene, acrylonitrile-styrene copolymer, polyvinyl acetate, ethylene-vinyl acetate copolymer, vinyl chloride, polyvinylpyridine, polyvinyl alcohol, and polyvinylpyrrolidone; polyurethane; and cellulose derivatives such as ethyl cellulose. Examples of curable resins include thermosetting resins and photocurable resins. Examples of thermosetting resins include epoxy resins and phenolic resins. Examples of photocurable resins include photocurable acrylic resins, photocurable urethane resins, and photocurable epoxy resins. These resins may be used alone or in combination of two or more. Among these, from the viewpoint of the electrical resistivity of the thermoelectric conversion material in the thermoelectric conversion material layer, thermoplastic resins are preferred, polycarbonate and cellulose derivatives such as ethyl cellulose are more preferred, and polycarbonate is particularly preferred.

[0035] The binder resin is appropriately selected depending on the temperature of the firing (annealing) treatment of the thermoelectric semiconductor material in the firing (annealing) treatment step. From the viewpoint of the electrical resistivity of the thermoelectric conversion material in the thermoelectric conversion material layer, it is preferable to perform the firing (annealing) treatment at a temperature equal to or higher than the final decomposition temperature of the binder resin. In this specification, the "final decomposition temperature" refers to the temperature at which the mass loss rate at the firing (annealing) temperature measured by thermogravimetry (TG) is 100% (the mass after decomposition is 0% of the mass before decomposition).

[0036] The final decomposition temperature of the binder resin is usually 150 to 600° C., preferably 200 to 560° C., more preferably 220 to 460° C., and particularly preferably 240 to 360° C. If a binder resin having a final decomposition temperature within this range is used, it functions as a binder for the thermoelectric semiconductor material, facilitating the formation of a thin film during printing.

[0037] The content of the binder resin in the thermoelectric semiconductor composition is 0.1 to 40 mass%, preferably 0.5 to 20 mass%, more preferably 0.5 to 10 mass%, and particularly preferably 0.5 to 5 mass%. When the content of the binder resin is within the above range, the electrical resistivity of the thermoelectric conversion material in the thermoelectric conversion material layer can be reduced.

[0038] The content of the binder resin in the thermoelectric conversion material is preferably 0 to 10 mass %, more preferably 0 to 5 mass %, and particularly preferably 0 to 1 mass %. When the content of the binder resin in the thermoelectric conversion material is within the above range, the electrical resistivity of the thermoelectric conversion material in the thermoelectric conversion material layer can be reduced.

[0039] (Ionic Liquid) The ionic liquid that can be contained in the thermoelectric semiconductor composition is a molten salt formed by combining a cation and an anion, and refers to a salt that can exist in liquid form at any temperature range from -50°C to less than 400°C. In other words, an ionic liquid is an ionic compound having a melting point in the range of -50°C to less than 400°C. The melting point of the ionic liquid is preferably -25°C to 200°C, more preferably 0°C to 150°C. Ionic liquids have characteristics such as extremely low vapor pressure and nonvolatility, excellent thermal stability and electrochemical stability, low viscosity, and high ionic conductivity. Therefore, as a conductive additive, they can effectively suppress a decrease in electrical conductivity between thermoelectric semiconductor materials. Furthermore, ionic liquids exhibit high polarity due to their aprotic ionic structure and excellent compatibility with heat-resistant resins, thereby enabling the electrical conductivity of thermoelectric conversion materials to be uniform.

[0040] 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 Cl － ,Br －, I － , AlCl ４ － , Al ２ Cl ７ － , B.F. ４ － , P.F. ６ － , ClO ４ － , NO ３ － , C.H. ３ COO － , C.F. ３ COO － , C.H. ３ SO ３ － , C.F. ３ SO ３ － , (FSO ２ ) ２ N － , (CF ３ SO ２ ) ２ N － , (CF ３ SO ２ ) ３ C － , AsF ６ － , SbF ６ － , NbF ６ － , TaF ６ － , F(HF) ｎ － , (CN) ２ N － , C ４ F ９ SO ３ － , (C ２ F ５ SO ２ ) ２ N － , C ３ F ７ COO － , (CF ３ SO ２ ) (CF ３ CO)N － and an anion component such as the above.

[0041] Among the above-mentioned ionic liquids, from the viewpoints of high-temperature stability, compatibility with thermoelectric semiconductor materials and resins, suppression of a decrease in the electrical conductivity of the gaps between thermoelectric semiconductor materials, etc., 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.

[0042] As the ionic liquid in which the cationic component contains a pyridinium cation or a derivative thereof, 1-butyl-4-methylpyridinium bromide, 1-butylpyridinium bromide, and 1-butyl-4-methylpyridinium hexafluorophosphate are preferred.

[0043] Furthermore, as the ionic liquid in which the cationic component contains an imidazolium cation and a derivative thereof, [1-butyl-3-(2-hydroxyethyl)imidazolium bromide] and [1-butyl-3-(2-hydroxyethyl)imidazolium tetrafluoroborate] are preferred.

[0044] The ionic liquid preferably 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 a thin film made of the thermoelectric semiconductor composition is annealed, as will be described later.

[0045] The content of 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 20 mass %. When the content of the ionic liquid is within the above range, a decrease in electrical conductivity is effectively suppressed, and a film with high thermoelectric performance is obtained.

[0046] (Inorganic ionic compound) The inorganic ionic compound that can be contained in the thermoelectric semiconductor composition is a compound composed of at least a cation and an anion. Inorganic ionic compounds exist in a solid state over a wide temperature range from 400 to 900°C and have characteristics such as high ionic conductivity, so that they can act as a conductive additive to suppress a decrease in electrical conductivity between thermoelectric semiconductor materials.

[0047] The content 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. When the content 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% by mass, more preferably 0.5 to 30% by mass, and even more preferably 1.0 to 10% by mass.

[0048] Methods for applying the P-type and N-type thermoelectric semiconductor compositions 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 coating. When forming a patterned coating, methods such as screen printing, stencil printing, and slot die coating are preferably used, which allow for easy pattern formation using a screen plate with the desired pattern. The resulting coating is then dried to form a thin film. Conventional drying methods, such as hot air drying, hot roll drying, and infrared irradiation, can be used. The heating temperature is typically 80 to 150°C, and the heating time, although varying depending on the heating method, is typically several seconds to several tens of minutes. Furthermore, when a solvent is used in preparing the thermoelectric semiconductor composition, the heating temperature is not particularly limited as long as it is within a temperature range that can dry the solvent used.

[0049] The thickness of the thermoelectric conversion material chip is not particularly limited, but is preferably 100 nm to 1000 μm, more preferably 300 nm to 600 μm, and even more preferably 5 to 400 μm, from the viewpoint of thermoelectric performance and film strength.

[0050] The P-type thermoelectric conversion material chips and N-type thermoelectric conversion material chips made of the thermoelectric semiconductor composition are preferably further subjected to an annealing treatment (hereinafter, sometimes referred to as "annealing treatment B"). By performing annealing treatment B, the thermoelectric performance can be stabilized and the thermoelectric semiconductor particles in the thermoelectric conversion material chips can undergo crystal growth, thereby further improving the thermoelectric performance. Annealing treatment B is not particularly limited, but is usually performed in an inert gas atmosphere such as nitrogen or argon, a reducing gas atmosphere, or under vacuum conditions with a controlled gas flow rate, and is performed at 100 to 500°C for several minutes to several tens of hours, depending on the heat resistance temperature of the thermoelectric semiconductor composition used.

[0051] (Protective Layer) In the thermoelectric conversion module of the present invention, a first protective layer is preferably provided on the first electrode and the first insulating layer, and a second protective layer is preferably provided on the second electrode and the second insulating layer. The materials used for the first protective layer and the second protective layer are not particularly limited, and known materials can be used. The first protective layer and the second protective layer are each preferably independently selected from insulating resins and ceramics. Examples of insulating resins include polyimide resins, polyamide resins, phenolic resins, epoxy resins, maleimide resins, fluorine-based resins, polyester resins, polyurethane resins (particularly two-component curing resins of polyacrylic polyols, polyester polyols, polyether polyols, etc., and isocyanate compounds), acrylic resins, polycarbonate resins, vinyl chloride / vinyl acetate copolymers, polyvinyl butyral resins, and nitrocellulose resins; alkyl titanates; ethyleneimines; and the like. These may be used alone or in combination of two or more. Examples of ceramics include materials containing aluminum oxide (alumina), aluminum nitride, zirconium oxide (zirconia), silicon nitride, silicon carbide, etc. as their main components (50 mass % or more of the ceramics). In addition to the main components, rare earth compounds, for example, can also be added.

[0052] The protective layer can be formed by coating a protective layer-forming solution prepared by dissolving or dispersing the above-mentioned materials in an appropriate solvent by a known method, drying the resulting coating, and, if desired, heating or irradiating with light. Alternatively, a protective layer-forming film may be formed separately and laminated using a roll laminator or a flat press machine to form the protective layer. Lamination may be performed at room temperature or while heating.

[0053] The thicknesses of the first protective layer and the second protective layer are determined appropriately from the viewpoint of thermoelectric performance, and are each independently preferably 5 to 300 μm, more preferably 25 to 200 μm, and even more preferably 50 to 100 μm. When the first protective layer and the second protective layer are formed by coating, the thicknesses of the protective layers are each independently preferably 5 to 150 μm, more preferably 10 to 100 μm, and even more preferably 15 to 50 μm. When the first protective layer and the second protective layer are formed by lamination, the thicknesses of the protective layers are each independently preferably 20 to 300 μm, more preferably 40 to 200 μm, and even more preferably 50 to 100 μm.

[0054] (Heat Dissipation Layer) In the thermoelectric conversion module of the present invention, from the viewpoint of thermoelectric performance, it is preferable to further provide a heat dissipation layer on the first protective layer and the second protective layer. The materials used for the first heat dissipation layer and the second heat dissipation layer are not particularly limited, and known materials can be used. Preferably, each of the first heat dissipation layer and the second heat dissipation layer is independently selected from gold, silver, copper, nickel, tin, iron, chromium, platinum, palladium, rhodium, iridium, ruthenium, osmium, indium, zinc, molybdenum, manganese, titanium, aluminum, stainless steel, and brass.

[0055] The method for laminating the heat dissipation layer is not particularly limited, but includes 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 various coating methods such as dip coating, spin coating, spray coating, gravure coating, die coating, and doctor blade, as well as wet processes such as electrodeposition, silver halide plating, electroplating, and electroless plating. Furthermore, patterning of the heat dissipation layer can be performed using known physical or chemical processes, primarily photolithography, or a combination of these. The thermal conductivity of each heat dissipation layer is preferably 5 to 500 W / (m·K), more preferably 8 to 500 W / (m·K), even more preferably 10 to 450 W / (m·K), particularly preferably 12 to 420 W / (m·K), and most preferably 15 to 400 W / (m·K).

[0056] The thickness of the heat dissipation layer is determined appropriately from the viewpoint of thermoelectric performance, but is preferably 5 to 550 μm, more preferably 40 to 530 μm, and even more preferably 80 to 510 μm.

[0057] (Frame) A frame may be provided around the thermoelectric conversion module of the present invention. By providing a frame, sealing of the outer periphery of the thermoelectric conversion module is unnecessary. The frame is made of metal, ceramic, or resin. Metal or ceramic is preferable from the viewpoint of sealing performance. Resin is preferable from the viewpoint of weight reduction. Examples of metals include gold, silver, copper, nickel, chromium, platinum, palladium, rhodium, molybdenum, aluminum, iron, iron-nickel alloy, and phosphor bronze. Examples of ceramics include materials containing aluminum oxide (alumina), aluminum nitride, zirconium oxide (zirconia), silicon nitride, silicon carbide, or the like as their main component (50% by mass or more of the ceramic). In addition to the main component, rare earth compounds, for example, can also be added. Examples of resins include polyimide resin, polyamide resin, phenolic resin, epoxy resin, maleimide resin, and fluorine-based resin. When a resin is used, it may be a rigid material using a hard resin, or a flexible material using a flexible resin.

[0058] The thermoelectric conversion module of the present invention does not use a substrate or a solder layer as a support, which have been used conventionally, and therefore the thermoelectric conversion module can be made thin.

[0059] The thermoelectric conversion module of the present invention can be made thinner than conventional thermoelectric conversion modules, and is expected to lead to lighter weight, smaller size, and higher integration.

[0060] 1, 11, 21: Thermoelectric conversion module 2: Frame 3p: P-type thermoelectric conversion material chip 3n: N-type thermoelectric conversion material chip 3p １ : First surface 3p of chip 3p of P-type thermoelectric conversion material ２ : second surface 3n of chip 3p of P-type thermoelectric conversion material １ : First surface 3n of chip 3n of N-type thermoelectric conversion material ２: Second surface of chip 3n of N-type thermoelectric conversion material 4: Arrangement direction of chips L1: First insulating layer L2: Second insulating layer M1: First electrode M2: Second electrode H1: First protective layer H2: Second protective layer T1: First heat dissipation layer T2: Second heat dissipation layer 12: Contact hole for extraction electrode 13: Extraction electrode

Claims

1. A thermoelectric conversion module including chips of P-type thermoelectric conversion material and chips of N-type thermoelectric conversion material arranged alternately and spaced apart, a first insulating layer, a second insulating layer, a first electrode, and a second electrode, the first insulating layer is provided on a first surface side of the chip of the P-type thermoelectric conversion material and a first surface side of the adjacent chip of the N-type thermoelectric conversion material so as to span a gap between the chip of the P-type thermoelectric conversion material and the chip of the adjacent N-type thermoelectric conversion material; the second insulating layer is provided on a second surface side of the chip of the P-type thermoelectric conversion material and a second surface side of the adjacent chip of the N-type thermoelectric conversion material so as to span a gap between the chip of the P-type thermoelectric conversion material and the chip of the adjacent N-type thermoelectric conversion material; The first insulating layer and the second insulating layer are provided opposite to each other with the gap therebetween, The chip of the P-type thermoelectric conversion material and the chip of the N-type thermoelectric conversion material are a first electrode provided on a first surface side of the chip of the P-type thermoelectric conversion material and on a first surface side of the chip of the N-type thermoelectric conversion material adjacent to the chip of the P-type thermoelectric conversion material and the chip of the N-type thermoelectric conversion material in an arrangement direction of the chip of the P-type thermoelectric conversion material and the chip of the N-type thermoelectric conversion material, with the first insulating layer interposed therebetween, and further across the first insulating layer; a second electrode provided on a second surface side of the chip of the N-type thermoelectric conversion material and on a second surface side of the chip of the P-type thermoelectric conversion material adjacent to the chip of the P-type thermoelectric conversion material in an arrangement direction of the chip of the P-type thermoelectric conversion material and the chip of the N-type thermoelectric conversion material, with the second insulating layer interposed therebetween, and further across the second insulating layer; the P-type thermoelectric conversion material chips and the N-type thermoelectric conversion material chips are electrically connected in this order in an arrangement direction, A gap is maintained between the first insulating layer, the second insulating layer, the chip of P-type thermoelectric conversion material, and the chip of N-type thermoelectric conversion material. Thermoelectric conversion module.

2. 2. The thermoelectric conversion module according to claim 1, wherein a first protective layer is provided on the first electrode and the first insulating layer, and a second protective layer is provided on the second electrode and the second insulating layer.

3. The thermoelectric conversion module according to claim 2 , further comprising a heat dissipation layer provided on the first protective layer and on the second protective layer.

4. The thermoelectric conversion module according to any one of claims 1 to 3, wherein a frame is provided around the thermoelectric conversion module.

5. The thermoelectric conversion module according to claim 4 , wherein the frame is made of a metal, a ceramic, or a resin.

6. The thermoelectric conversion module according to any one of claims 1 to 3, wherein the first insulating layer and the second insulating layer are each independently selected from a polyimide resin, a silicone resin, a rubber-based resin, an acrylic resin, an olefin-based resin, a maleimide resin, and an epoxy resin.

7. 4. The thermoelectric conversion module according to claim 2, wherein the first protective layer and the second protective layer are each independently selected from an insulating resin and a ceramic.

8. 4. The thermoelectric conversion module according to claim 3, wherein the heat dissipation layer is selected from the group consisting of gold, silver, copper, nickel, tin, iron, chromium, platinum, palladium, rhodium, iridium, ruthenium, osmium, indium, zinc, molybdenum, manganese, titanium, aluminum, stainless steel, and brass.

9. 4. The thermoelectric conversion module according to claim 1, wherein the first insulating layer and the second insulating layer each independently have a thickness of 5 to 200 μm.

10. 4. The thermoelectric conversion module according to claim 2, wherein the first protective layer and the second protective layer each independently have a thickness of 5 to 300 μm.

11. 9. The thermoelectric conversion module according to claim 3, wherein the heat dissipation layer has a thickness of 5 to 550 μm.

12. The thermoelectric conversion module according to any one of claims 1 to 3, wherein the first electrode and the second electrode are each independently selected from gold, silver, copper, nickel, chromium, platinum, palladium, rhodium, molybdenum, aluminum, or an alloy containing any of these metals.

13. The thermoelectric conversion module according to any one of claims 1 to 3, wherein the first electrode and the second electrode are each independently formed of at least one film selected from the group consisting of a sputtered film, a vapor deposition film, and a plating film.

14. The thermoelectric conversion module according to any one of claims 1 to 3, wherein the chip of P-type thermoelectric conversion material and the chip of N-type thermoelectric conversion material are made of a thermoelectric semiconductor composition.

15. The thermoelectric conversion module according to claim 14 , wherein the thermoelectric semiconductor composition comprises a thermoelectric semiconductor material, a resin, and one or both of an ionic liquid and an inorganic ionic compound.