Patent Description:
Recently, effective utilization of exhaust heat that is generated in the process of using primary energy has become an important subject with an increased interest in energy problems, along with the use of renewable energy. An energy amount of the exhaust heat occupies approximately <NUM>% of the primary energy, and most thereof is generated in a wide range of places such as a plant, an industrial infrastructure, consumer products, and mobility.

There are technologies for reusing various exhaust heats, and among them, a thermoelectric conversion system using a Seebeck effect in which a material generates a voltage by a temperature difference is known. The thermoelectric conversion system is not provided with a driving unit such as a turbine, and thus, has scalability and can be downsized, and is suitable for heat recovery for a wide range of temperatures. For this reason, the thermoelectric conversion system is a technology that can be applied to power generation using a thermal source in a limited narrow space such as an automobile, and can be applied to energy harvesting using environmental heat as a power source.

Recently, it has been considered that such energy harvesting is applied as a sensor power source for IoT. In order to operate a sensor, it is necessary to operate a low-power IC for controlling a sensor. However, the power specification thereof is approximately <NUM> uW, a voltage necessary for start is approximately <NUM> mV, and a voltage necessary for a normal operation is approximately <NUM> mV. In general, such power is minute, but in the case of IoT application, it is necessary to downsize the entire sensor module combined with the power source, and according to such needs, there is a limitation in the power source to be a supply source.

A downsized thermoelectric conversion module has been considered as a solution to such problems. The thermoelectric conversion module has a structure in which an N-type thermoelectric conversion material and a P-type thermoelectric conversion material are electrically connected in series by an electrode, and are disposed in parallel to a heat flow.

Examples of a technology relevant to the thermoelectric conversion module include <CIT>.

In <CIT>, a film-shaped substrate that contains two or more types of materials having different thermal conductivities and has flexibility is provided on both surfaces of a thermoelectric conversion module including a P-type thermoelectric element that is a thin film containing a P-type material and an N-type thermoelectric element that is a thin film containing an N-type material, and a material having a high thermal conductivity is positioned on a part of the outer surface of the substrate.

In the thermoelectric conversion module, it is convenient to install the module such that the maximum surface of the module is in contact with the thermal source, but heat is released in a vertical direction of the thermoelectric conversion module, and thus, it is difficult to generate a heat flow in an in-plane direction of the thermoelectric conversion module. <CIT> discloses a thermoelectric conversion element and method of manufacturing a thermoelectric conversion element. <CIT> discloses a thermoelectric conversion module. <CIT> discloses a thermoelectric element and a thermoelectric module including said thermoelectric element.

An object of the invention is to efficiently generate a heat flow in an in-plane direction of a thermoelectric conversion module, in a thermoelectric conversion element.

A thermoelectric conversion element of one aspect of the invention is a thermoelectric conversion element converting heat into electricity by using a temperature difference, the element including: a substrate; a thermoelectric layer including a P-type thermoelectric layer and an N-type thermoelectric layer; an insulating portion provided on both surfaces of the thermoelectric layer; a heat releasing portion provided above the thermoelectric layer; and a heat receiving portion provided below the thermoelectric layer, in which a heat flow is generated such that the heat flow toward a direction perpendicular to a surface of the substrate is inhibited and is directed toward a direction parallel to the surface of the substrate to pass through the thermoelectric layer, by interfacial thermal resistance existing on an interface between the thermoelectric layer and the insulating portion.

A thermoelectric conversion element of one aspect of the invention is a thermoelectric conversion element converting heat into electricity by using a temperature difference, the element including: a substrate; a thermoelectric layer including a P-type thermoelectric layer and an N-type thermoelectric layer; an insulating portion provided on both surfaces of the thermoelectric layer; a heat releasing portion provided above the thermoelectric layer; and a heat receiving portion provided below the thermoelectric layer, in which the thermoelectric layer includes a multi-layer film in which a first thermoelectric conversion material layer and a second thermoelectric conversion material layer containing a material different from that of the first thermoelectric conversion material layer are alternately laminated, and a heat flow is generated such that the heat flow toward a direction perpendicular to a surface of the substrate is inhibited and is directed toward a direction parallel to the surface of the substrate to pass through the thermoelectric layer, by the multi-layer film.

According to one aspect of the invention, a heat flow can be efficiently generated in an in-plane direction of a thermoelectric conversion module, in a thermoelectric conversion element.

In the following embodiments, for the sake of convenience, the description will be divided into a plurality of sections or embodiments, as necessary, but unless otherwise specified, such sections or embodiments are relevant to each other, and one section or embodiment is in a relationship of a modification example, a detail, a supplemental description, and the like with a part or all of the other section or embodiment.

In addition, in the following embodiments, in the case of describing the number of components and the like (including the number of pieces, a numerical value, an amount, a range, and the like), unless otherwise specified or obviously limited to a specific number in principle, the number is not limited to the specific number, and may be a number greater or less than or equal to the specific number.

Further, in the following embodiments, it is obvious that constituents (also including a component step and the like) are not necessarily essential, unless otherwise specified or considered as obviously essential in principle. Similarly, in the following embodiments, in the case of describing the shape, a positional relationship, or the like of the constituents and the like, unless otherwise specified or considered as not obvious in principle, the shape includes a shape that is substantially approximated to or similar to the shape or the like. The same also applies to the numerical value and the range described above.

Hereinafter, the embodiments of the invention will be described in detail, with reference to the drawings. Note that, in all of the drawings for illustrating the embodiments, the same reference numerals will be applied to members having the same function, and the repeated description thereof will be omitted. In addition, in the following embodiments, unless necessary, the description of the same or similar parts will not be repeated in principle.

In addition, in the following embodiments, in the case of representing a range by A to B, unless otherwise specified, it is indicated that the range is greater than or equal to A and less than or equal to B.

First, the configuration of a general π-type thermoelectric conversion element will be described with reference to <FIG>.

As illustrated in <FIG>, a π-type thermoelectric conversion element <NUM> has a heat releasing structure <NUM> on a low-temperature thermal source side, and has a heat receiving structure <NUM> on a high-temperature thermal source side. A thermoelectric layer <NUM> including a P-type thermoelectric layer <NUM> and an N-type thermoelectric layer <NUM> is provided between a pair of substrates <NUM> through an electrode <NUM>.

In a case where a heat flow flows in a heat flow direction of an arrow in <FIG>, a heat flow amount thereof is converted into power, and a voltage is generated between the electrodes. A power conversion efficiency and a power density (a power generation amount per unit area, W/m<NUM>) of a thermoelectric conversion module are set by ZT that is a material performance index of a thermoelectric conversion material and a temperature difference that is applied to the thermoelectric conversion module.

Specifically, a conversion efficiency η is represented by Expression <NUM> described below, and output P is represented by Expression <NUM> described below. [Expression <NUM>] <MAT> [Expression <NUM>] <MAT>.

Here, Q is a heat flow amount, ZT = αT/κ is defined, α is an output factor (S<NUM>/ρ), S is a Seebeck coefficient, and ρ is an electricity resistivity. In addition, κ = κph + κel is defined, and κph and κel are a lattice thermal conductivity and an electron thermal conductivity, respectively. T is set to an absolute temperature, the temperature of a high-temperature portion is set to TH, the temperature of a low-temperature portion is set to TL, a temperature difference is set to ΔT = TH - TL, and an average temperature is set to Tave = (TH + TL)/<NUM>.

As described above, in a case where a temperature difference is suitably ensured, the conversion efficiency is improved by increasing the performance index ZT of the thermoelectric conversion material. In addition, it is found that the power density is improved by increasing both of the performance index ZT and the output factor α.

On the other hand, examples of an approach to the improvement of the output of the module include a method for maximizing Q by optimizing a module structure. In the π-type thermoelectric conversion module, the height of the thermoelectric conversion material is designed to be high, in order to improve Q. In addition, from the viewpoint of reliability, a size of approximately <NUM> × <NUM> with a large sectional area is the mainstream.

Such a module has been developed in order to recover the exhaust heat of an automobile. On the other hand, there are needs for thinning and downsizing in IoT application, and thus, a method in which heat flows in the plane of a thin film is adopted as a method for handling the heat flow amount Q. In the case of a downsized thermoelectric conversion module, it is extremely difficult to draw the heat flow into the plane of the thin film, and various methods have been proposed.

In particular, it is convenient to install the module such that the maximum surface of the module is in contact with the thermal source, but heat is released in a vertical direction of the module, and thus, it is difficult to generate the heatflow in an in-plane direction of the module. Simultaneously, as shown in <FIG>, power of <NUM> uW which is a specification required in the IoT application, and it is difficult to satisfy a specification starting voltage of approximately <NUM> mV or approximately <NUM> mV.

As described above, in the π-type thermoelectric conversion element <NUM> illustrated in <FIG>, a heat transfer direction from the thermal source is parallel to a voltage generation direction. In structure, bulk is necessary for a temperature difference. As a result thereof, a strong stress is applied, and the reliability decreases.

Therefore, a structure in which the heat flow flows into the thermoelectric material installed on the plane from the thermal source (a structure in which the heat transfer direction from the thermal source is vertical to the voltage generation direction) is required.

A thermoelectric conversion element of a first example will be described with reference to <FIG>.

In the thermoelectric conversion element of the first example, a heat flow is efficiently generated in-plane direction of a thermoelectric conversion module. In the first example, the heat flow is efficiently generated in a thermoelectric conversion material layer of a downsized thermoelectric conversion module, and as a solution for preventing heat releasing toward a direction perpendicular to the maximum surface of the downsized thermoelectric conversion module, the thermoelectric conversion material layer is formed into a multi-layer film including a thermoelectric conversion material A layer and a thermoelectric conversion material B layer, and the dimension is adjusted. As a result thereof, as illustrated in <FIG>, the heat flow toward the direction perpendicular to the surface is inhibited by the effect of interfacial thermal resistance between the thermoelectric conversion material A layer and the thermoelectric conversion material B layer. As a result thereof, the heat flow can be generated in the thermoelectric conversion material layer.

A mechanism in which such a result is acquired will be described in detail, with reference to <FIG>. Here, <FIG> is a schematic view of a plane type thermoelectric conversion module <NUM> configuring a typical thermoelectric conversion element. <FIG> is a conceptual diagram of a state in which the heat flow is generated in the plane type thermoelectric conversion module <NUM>. <FIG> is a conceptual diagram relevant to a heat flow direction in a case where the heat flow flows in the multi-layer film.

As illustrated in <FIG>, the thermoelectric conversion module <NUM> includes a heat receiving portion <NUM> and a heat releasing portion <NUM> having a high thermal conductivity, an insulating portion <NUM> having a low thermal conductivity, and a thermoelectric layer <NUM> having a thermal conductivity that is lower than that of the heat receiving portion <NUM> and is higher than that of the insulating portion <NUM>.

Further, in a case where the thermal source is on the lower side of the plane type thermoelectric conversion module <NUM>, and the upper side of the plane type thermoelectric conversion module <NUM> is air-cooled or water-cooled, broadly, the heat flux is generated toward the upper side from the lower side of the plane type thermoelectric conversion module <NUM>.

In such a situation, the state of a heat flux in the vicinity of the heat receiving portion <NUM> is illustrated in <FIG>. A heat flow <NUM> that is a part of a heat flow <NUM> toward the upper side through the heat receiving portion <NUM> having a high thermal conductivity flows in an in-plane direction of the plane type thermoelectric conversion module <NUM> by changing the direction to flow along the thermoelectric layer <NUM> having a higher thermal conductivity than that of the insulating portion <NUM>.

The present inventors have found that the conversion of the heat flow direction is caused not only by a difference in the thermal conductivities but also as a result on which the effect of the interfacial thermal resistance is reflected. In the first example, the material of the optimal insulating portion <NUM> and the thermoelectric layer <NUM> in which the effect of the interfacial thermal resistance can be actively utilized is used. In addition, the multi-layer film is formed as a preferred structure for allowing the effect of the interfacial thermal resistance to be more significantly exhibited, and the effect is considered.

As illustrated in <FIG>, the thermoelectric layer <NUM> is formed into a multi-layer structure including a thermoelectric conversion material A layer <NUM> and a thermoelectric conversion material B layer <NUM>, and the heat flow direction is changed on the interface between the thermoelectric conversion material A layer <NUM> and the thermoelectric conversion material B layer <NUM>. Specifically, the heat flow direction is changed to a heat flow direction <NUM> from a heat flow direction <NUM> on the interface between the thermoelectric conversion material A layer <NUM> and the thermoelectric conversion material B layer <NUM>. As described above, it can be said that having the multi-layer structure is more preferred means for the conversion of the heat flow direction in which the interfacial thermal resistance is utilized.

As described above, power that is generated by the heat flow generated in the plane of the plane type thermoelectric conversion module <NUM> has a dimension in which a power generation amount is maximized or is greater than a desired voltage.

According to the first example, a downsized thermoelectric conversion module for IoT having <NUM> × <NUM> and a thickness of less than <NUM> can be provided.

In particular, as schematically shown in <FIG>, a power generation element that is thin and downsized such as <NUM> × <NUM> but is greater than <NUM> uW can be provided by the number of interfaces for acquiring the effect of the optimal interfacial thermal resistance. Here, <FIG> is a graph showing a voltage generation amount, and <FIG> is a graph showing a temperature difference.

As described above, the thermoelectric conversion module <NUM> of the first example illustrated in <FIG> is a thermoelectric conversion element converting heat into electricity by using a temperature difference. The thermoelectric conversion module <NUM> includes the thermoelectric layer <NUM>, the insulating portion <NUM> provided on both surfaces of the thermoelectric layer <NUM>, the heat releasing portion <NUM> provided above the thermoelectric layer <NUM>, and the heat receiving portion <NUM> provided below the thermoelectric layer <NUM>. The thermoelectric layer <NUM>, for example, includes a P-type thermoelectric layer and an N-type thermoelectric layer provided on the substrate (for example, refer to <FIG>).

The thermoelectric layer <NUM> includes the multi-layer film in which a first thermoelectric conversion material layer (the thermoelectric conversion material A layer <NUM>) and a second thermoelectric conversion material layer (the thermoelectric conversion material B layer <NUM>) containing a material different from that of the first thermoelectric conversion material layer (the thermoelectric conversion material A layer <NUM>) are alternately laminated. The heat flow is generated such that the heat flow toward the direction perpendicular to the surface of the substrate is inhibited and is directed toward a direction parallel to the surface of the substrate to pass through the thermoelectric layer <NUM>, by the multi-layer film.

The interfacial thermal resistance exists between the first thermoelectric conversion material layer and the second thermoelectric conversion material layer, and the heat flow toward the direction parallel to the surface of the substrate is generated by the interfacial thermal resistance.

As illustrated in <FIG>, the thermoelectric layer <NUM>, for example, is configured such that the P-type thermoelectric layer and the N-type thermoelectric layer are alternately disposed in the direction parallel to the surface of the substrate, and each of the P-type thermoelectric layer and the N-type thermoelectric layer includes the multi-layer film in which the first thermoelectric conversion material layer (the thermoelectric conversion material A layer <NUM>) and the second thermoelectric conversion material layer (the thermoelectric conversion material B layer <NUM>) are alternately laminated. The heat releasing portion <NUM> and the heat receiving portion <NUM> have a thermal conductivity greater than the thermal conductivity of the insulating portion <NUM>.

Next, the thermoelectric conversion material will be described.

For example, the first thermoelectric conversion material layer (the thermoelectric conversion material A layer <NUM>) contains a Fe-based full-Heusler alloy, and the second thermoelectric conversion material layer (the thermoelectric conversion material B layer <NUM>) contains silicon.

For example, the number of laminations of the first thermoelectric conversion material layer and the second thermoelectric conversion material layer configuring the multi-layer film is in a range of <NUM> to <NUM>.

For example, a length (L) and a width (W) that are the dimension of the first thermoelectric conversion material layer and the second thermoelectric conversion material layer are in a relationship of W ≥ <NUM> and L ≤ <NUM>.

For example, the length (L) and the width (W) that are the dimension of the first thermoelectric conversion material layer and the second thermoelectric conversion material layer have a value in a range represented by two sets of L = <NUM> and W ≥ <NUM> and W ≥ <NUM> and L = <NUM>.

The present inventors have adopted the Fe-based full-Heusler alloy as the thermoelectric conversion material A layer <NUM> of the first example. The Fe-based full-Heusler alloy indicates an alloy in which an atom A is iron, in alloys having an L2<NUM> type crystalline structure represented by A<NUM> BC.

In such an alloy, atoms B and C are set to a suitable element, and thus, the alloy can be modulated to both of an N-type thermoelectric conversion material and a P-type thermoelectric conversion material. In addition, the thermoelectric conversion material B layer contains the Fe-based full-Heusler alloy, and Si or a BiTe material. Si or the BiTe material can also be modulated to both of the N-type thermoelectric conversion material and the P-type thermoelectric conversion material, in accordance with the type of additive element.

The core portion of the downsized thermoelectric conversion module <NUM> includes the heat receiving portion <NUM>, the insulating portion <NUM>, the thermoelectric conversion material A layer <NUM>, and the thermoelectric conversion material B layer <NUM>. The heat receiving portion <NUM> contains copper. The insulating portion <NUM> contains SiO<NUM>, AlO<NUM>, or polyimide.

In the dimension of each of the thermoelectric conversion material A layer <NUM> and the thermoelectric conversion material B layer <NUM>, the thickness of the thin film is dA and dB, the width is W, and the length is L. In addition, d = dA + dB is defined.

In a case where the thickness of the multi-layer film including the thermoelectric conversion material A layer <NUM> and the thermoelectric conversion material B layer <NUM> is D, the number N of laminations is defined as D/d. In the dimension of the heat receiving portion <NUM>, the thickness is d2, the width is W, and the length is l2.

Such a dimension is adjusted, and the effect of the interfacial thermal resistance of the thermoelectric conversion material A layer <NUM> and the thermoelectric conversion material B layer <NUM> is incorporated, and thus, the size of the heat flow is calculated. In a calculation method, a thermal diffusion equation is analyzed by a finite element method. The effect of the interfacial thermal resistance is incorporated by assuming a model in which virtual thermal resistance exists in an infinitely small thickness.

It is found that in a case where the multi-layer film including the thermoelectric conversion material A layer <NUM> and the thermoelectric conversion material B layer <NUM> is incorporated, a temperature distribution is obliquely generated, and an in-plane heat flux is generated in the thermoelectric conversion material layer (for example, refer to <FIG>).

Results of plotting the power generation amount in a case where the thickness D of the multi-layer film is fixed to <NUM> and d is modulated to <NUM> from <NUM> by such an in-plane heat flow, with respect to the number N of laminations, are shown in <FIG>. In <FIG>, six curves plotted with respect to each dimension of L and W are shown.

In <FIG>, it is found that the power generation amount is greater than <NUM>µW in several conditions. For example, it is found that in a case where the number N of laminations is <NUM> to <NUM>, the power generation amount of greater than <NUM>µW can be provided, in a condition of (L, W) = (<NUM>, <NUM>) (<NUM>, <NUM>) and (<NUM>, <NUM>).

In addition, results of calculating a voltage from the obtained heat flux and of plotting the voltage with respect to W and L are shown in <FIG>.

From <FIG>, it is found that in a case where a voltage of <NUM> mV to be a specification is obtained, there is a dimensional constraint of W ≥ <NUM> and L ≤ <NUM>. In addition, it is found that in a case where a voltage of <NUM> mV to be a specification is obtained, a dimensional constraint in which W and L are a dimension in a region represented by two sets of a combination of W ≥ <NUM> and L = <NUM> and a combination of W ≥ <NUM> and L = <NUM>.

As described above, the form of the module obtained on the basis of the dimension obtained by calculation is as illustrated in <FIG>, and the details thereof will be described below. Second example.

A thermoelectric conversion element of a second example will be described with reference to <FIG>.

As illustrated in <FIG>, a plane type thermoelectric conversion module <NUM> configuring a thermoelectric conversion element includes a heat receiving portion <NUM> and a heat releasing portion <NUM> having a high thermal conductivity, an insulating portion <NUM> having a low thermal conductivity, and a thermoelectric layer <NUM> having a thermal conductivity that is lower than that of the heat receiving portion <NUM> and is higher than that of the insulating portion <NUM>.

Further, in a case where a thermal source is on the lower side of the plane type thermoelectric conversion module <NUM>, and the upper side of the plane type thermoelectric conversion module <NUM> is air-cooled or water-cooled, broadly, a heat flux is generated from the lower side toward the upper side of the plane type thermoelectric conversion module <NUM>.

In <FIG>, a gray scale represents a temperature, and a low temperature is represented in the order from a high gray scale of a high temperature toward a low gray scale of a low temperature.

As illustrated in <FIG>, it is found that the gray scale obliquely represented from the heat releasing portion <NUM> toward the heat receiving portion <NUM>, and a temperature gradient is also obliquely represented. The result thereof indicates that a temperature difference is generated in the plane of the module, and the heat flow is generated, in the plane type thermoelectric conversion module <NUM>. In particular, it is expected that a temperature difference in the thermoelectric layer <NUM> is schematically illustrated as a plot of <FIG>. Here, in <FIG>, a horizontal axis represents a position, and a vertical axis represents a temperature.

The results of calculating an in-plane heat flow in the plane type thermoelectric conversion module <NUM> with respect to a case where the effect of interfacial thermal resistance is incorporated and a case where the effect of the interfacial thermal resistance is not incorporated are illustrated in <FIG>, respectively. Here, <FIG> illustrates a case where the effect of the interfacial thermal resistance is incorporated, and <FIG> illustrates a case where the effect of the interfacial thermal resistance is not incorporated.

<FIG> is the result of calculating an interfacial thermal resistance ratio with a combination of a Fe-based full-Heusler alloy and SiO<NUM>. A gray scale in <FIG> represents the intensity of the heat flux, and in <FIG>, it is found that the intensity of the heat flux is high in the vicinity of the thermoelectric layer <NUM>. The physical meaning of such a result indicates that heat is not capable of being excellently transferred to the insulating portion <NUM> from the thermoelectric layer <NUM>, and the heat flow is generated in the plane of the thermoelectric layer <NUM>, by the effect of the interfacial thermal resistance.

On the other hand, in <FIG>, a similar heat flux is not generated. In a comparison between <FIG>, it is found that in the case of selecting a combination of the thermoelectric layer <NUM> and the insulating portion <NUM> in which the effect of the interfacial thermal resistance is strongly exhibited, the direction of the heat flow is converted into an in-plane direction, and a desired temperature difference is generated in the plane type thermoelectric conversion module <NUM>.

Note that, the effect is more significantly exhibited in the multi-layer film in which the number of interfaces is large (refer to <FIG>).

As described above, the thermoelectric conversion module <NUM> of the second example illustrated in <FIG> is a thermoelectric conversion element converting heat into electricity by using a temperature difference. The thermoelectric conversion module <NUM> includes the insulating portion <NUM> provided on both surfaces of the thermoelectric layer <NUM>, the heat releasing portion <NUM> provided above the thermoelectric layer <NUM>, and the heat receiving portion <NUM> provided below the thermoelectric layer <NUM>. The thermoelectric layer <NUM>, for example, includes the P-type thermoelectric layer and the N-type thermoelectric layer provided on the substrate (for example, refer to <FIG>).

A heat flow is generated such that the heat flow toward a direction perpendicular to the surface of the substrate is inhibited and is directed toward a direction parallel to the surface of the substrate to pass through the thermoelectric layer <NUM>, by the interfacial thermal resistance existing on the interface between the thermoelectric layer <NUM> and the insulating portion <NUM>. The heat flow is generated in the plane of the interface between the thermoelectric layer <NUM> and the insulating portion <NUM> by the interfacial thermal resistance.

For example, the interfacial thermal resistance is adjusted to a value corresponding to a junction between a metal and an amorphous material, and thus, the heat flow is generated in the plane of the interface between the thermoelectric layer <NUM> and the insulating portion <NUM>.

A difference is generated in effective interfacial thermal resistance, in accordance with the direction of the heat flow, in a junction portion of two layers having different Young's moduli. In other words, a temperature difference is maintained. In a case where the interfacial thermal resistance is adjusted to the value corresponding to the junction between a metal/an amorphous material, a heat amount is generated in the plane.

A thermoelectric conversion element of a first embodiment will be described with reference to <FIG>.

As illustrated in <FIG>, a thermoelectric conversion element <NUM> of the first embodiment has a heat releasing structure <NUM> on a low-temperature thermal source side, and has a heat receiving structure <NUM> on a high-temperature thermal source side. A thermoelectric layer <NUM> including a P-type thermoelectric layer <NUM> and an N-type thermoelectric layer <NUM> is provided between a pair of substrates <NUM> through an electrode <NUM>. In the thermoelectric layer <NUM>, the P-type thermoelectric layer <NUM> and the N-type thermoelectric layer <NUM> are alternately disposed in a direction parallel to the surface of the substrate <NUM>. Then, an insulating portion <NUM> is disposed in the upper portion and the lower portion of the thermoelectric layer <NUM>.

Further, a heat releasing portion <NUM> and a heat receiving portion <NUM> containing a material having a thermal conductivity greater than that of the insulating portion <NUM> are disposed in at least a part of the upper portion and the lower portion of the thermoelectric layer <NUM>.

The heat releasing portion <NUM> and the heat receiving portion <NUM> are disposed in facing positions with respect to the center line in the direction parallel to the surface of the thermoelectric layer <NUM>.

In <FIG>, the heat releasing portion <NUM> is on the upper side in the drawing and is air-cooled or water-cooled, and it is assumed that the thermal source is on the lower side in the drawing. In the plane type thermoelectric conversion module, the P-type thermoelectric layer <NUM> and the N-type thermoelectric layer <NUM> are disposed to be in contact with each other in the same plane such that the P-type thermoelectric layer <NUM> and the N-type thermoelectric layer <NUM> can be connected in an electrically excellent state, and the insulating portions <NUM> are disposed to interposing the thermoelectric layer <NUM> therebetween.

Further, the heat receiving portion <NUM> and the heat releasing portion <NUM>, for example, are disposed to be point-symmetric with respect to the center point of the P-type thermoelectric layer <NUM>. Then, in the adjacent N-type thermoelectric layers <NUM>, the heat receiving portion <NUM> and the heat releasing portion <NUM> are disposed to be line-symmetric with respect to the P-type thermoelectric layer <NUM>.

At this time, in consideration of an effect relevant to the conversion of a heat flux, various heat receiving portions <NUM> and heat releasing portions <NUM> are considered. <FIG> is a birds-eye view and a top view of the structure in the sectional view illustrated in <FIG>.

As described above, structures in which the same effect can be obtained, as with patterns A and B illustrated in <FIG>, are considered. In the plane type thermoelectric conversion module, the P-type thermoelectric layer <NUM> and the N-type thermoelectric layer <NUM> are disposed to be in contact with each other in the same plane such that the P-type thermoelectric layer <NUM> and the N-type thermoelectric layer <NUM> can be connected in an electrically excellent state.

In particular, in the thermoelectric conversion element <NUM> illustrated in the pattern B of <FIG>, a part of the heat receiving portion <NUM> is positioned inside the thermoelectric layer <NUM>, and a part of the heat releasing portion <NUM> is positioned inside the thermoelectric layer <NUM>. A heat flow from the heat receiving portion <NUM> passes through the thermoelectric layer <NUM> in the direction parallel to the surface of the substrate <NUM> and is guided to the heat releasing portion <NUM>. As described above, as with the pattern B of <FIG>, it is naturally assumed that even in a case where the heat releasing portion <NUM> and the heat receiving portion <NUM> are in contact with the P-type thermoelectric layer <NUM> and the N-type thermoelectric layer <NUM>, respectively, the same effect can be obtained.

According to the configuration described above, in the thermoelectric conversion element <NUM> of the first embodiment, a heat flow is generated in the direction parallel to the surface of the substrate <NUM> by the heat releasing portion <NUM> and the heat receiving portion <NUM>, and thus, a voltage drop direction can be planarized. Accordingly, the thinning of the thermoelectric conversion module can be attained.

Next, a method for manufacturing a thermoelectric conversion material and a module will be described.

A desired method for obtaining the configuration of the thermoelectric conversion material has been described. For example, a method for forming a film on an insulator substrate by a magnetron sputtering method is desirable.

At this time, the film is formed in ultra-high vacuum. There is a method in which the substrate is not overheated, and the growth of the thin film is controlled such that a desired crystalline structure is obtained by an Ar partial pressure and sputtering power. Further, a desired pattern is formed by lithography, and a thermoelectric conversion module is formed.

At this time, a coating type film formation method may be used as a method for forming an insulating portion. In addition, a P-type thermoelectric conversion layer and an N-type thermoelectric conversion layer may be prepared on substrates, respectively, and then, two substrates may be bonded.

In this example, a Fe<NUM>TiSi-based full-Heusler alloy was adopted in a thermoelectric conversion material A layer, and Si was adopted in a thermoelectric conversion material B layer. Composition adjustment was performed such that the materials became an N-type thermoelectric conversion material and a P-type thermoelectric conversion material.

In the thermoelectric conversion material A layer, an alloy was adopted in which Fe, Ti, and Si were a main component, and composition adjustment was performed in the vicinity of an atomic weight ratio of Fe : Ti : Si = <NUM> (at%) : <NUM> (at%) : <NUM> (at%). Ti was substituted with approximately <NUM> at% of V to be the N-type thermoelectric conversion material, and Si was substituted with approximately <NUM> at% of Al to be the P-type thermoelectric conversion material.

In addition, in the thermoelectric conversion material B layer, phosphorus was added to be N-type Si, and boron was added to be P-type Si. In the thermoelectric conversion material layers, first, the N-type thermoelectric conversion material layer was formed on the insulator substrate passivated by an insulating layer, on which a heat receiving portion was formed in advance by lithography.

The magnetron sputtering method was used as a film formation method, and the film was formed in ultra-high vacuum. A multi-layer film was also formed as a part of the atmosphere. The thermoelectric conversion material layer after the film formation was formed into a desired shape by lithography.

An opening portion for the P-type thermoelectric conversion material layer was provided by applying and developing a resist after the film formation using the lithography. The P-type thermoelectric conversion material layer was formed as with the N-type thermoelectric conversion material layer by filling the opening portion.

Claim 1:
A thermoelectric conversion element converting heat into electricity by using a temperature difference, the element comprising:
a substrate (<NUM>);
a thermoelectric layer (<NUM>) having a first surface and a second surface and including a P-type thermoelectric layer and an N-type thermoelectric layer;
an insulating portion (<NUM>) provided on the first surface and the second surface of the thermoelectric layer (<NUM>);
a heat releasing portion (<NUM>) provided above the thermoelectric layer (<NUM>); and
a heat receiving portion (<NUM>) provided below the thermoelectric layer (<NUM>);
wherein a heat flow is generated such that the heat flow toward a direction perpendicular to a surface of the substrate (<NUM>) is inhibited and is directed toward a direction parallel to the surface of the substrate (<NUM>) to pass through the thermoelectric layer (<NUM>), by interfacial thermal resistance existing on an interface between the thermoelectric layer (<NUM>) and the insulating portion (<NUM>);
characterised in that a part of the heat receiving portion (<NUM>) is positioned inside the thermoelectric layer (<NUM>);
a part of the heat releasing portion (<NUM>) is positioned inside the thermoelectric layer (<NUM>); and
the heat flow from the heat receiving portion (<NUM>) passes through the thermoelectric layer (<NUM>) in the direction parallel to the surface of the substrate (<NUM>) and is guided to the heat releasing portion (<NUM>).