JP2010147379A - Thermoelectric conversion material and thermoelectric conversion element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermoelectric conversion material and a thermoelectric conversion element that have high electrical conductivity, low thermal conductivity, and high efficiency. <P>SOLUTION: The thermoelectric conversion material includes a plurality of linear structures 20 of carbon elements, and thermal conductivity decrease substances 22 included in the linear structures 20 and decreasing the thermal conductivity of the linear structures 20. Consequently, the thermoelectric conversion material can decrease the thermal conductivity of the linear structures 20 while maintaining the electrical conductivity that the linear structures 20 have, and also has a high figure ZT of merit and high efficiency. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a thermoelectric conversion material and a thermoelectric conversion element.

  Technology that converts heat into electric power, that is, thermoelectric conversion technology, is positioned as an important technology for the prevention of global warming because waste heat from industrial and consumer products can be used effectively as electric power.

  A thermoelectric conversion device generally has a structure in which P-type and N-type semiconductor thermoelectric conversion materials are sandwiched between electrodes. In order for the thermoelectric conversion material to be highly efficient, a dimensionless figure of merit called ZT needs to be large. In order to increase the figure of merit ZT, it is necessary to 1) have a high Seebeck coefficient, 2) have a high electrical conductivity, and 3) have a low thermal conductivity, especially 2) and 3 ) Often conflict.

In order to satisfy both high electrical conductivity and low thermal conductivity at the same time, an attempt has been made to inhibit phonon conduction in a material in which thermal conduction is mainly phonon conduction. One method is to make the material nanostructured. By making the material nanostructured, phonons are scattered at the interface of the nanostructure, and heat conduction can be reduced.
JP 2004-087714 A JP 2005-183528 A

  However, when the material is nanostructured, it often inhibits electrical conduction at the same time. For this reason, it is difficult to satisfy high electrical conductivity and low thermal conductivity at the same time, and no thermoelectric conversion material having a sufficiently high figure of merit ZT has been obtained at present.

  An object of the present invention is to provide a highly efficient thermoelectric conversion material and thermoelectric conversion element having high electrical conductivity and low thermal conductivity.

  According to one aspect of the embodiment, a plurality of linear structures of carbon elements and a thermal conductivity-decreasing substance that is included in the plurality of linear structures and decreases the thermal conductivity of the linear structures. A thermoelectric conversion material is provided.

  Further, according to another aspect of the embodiment, a plurality of linear structures of carbon elements and a thermal conductivity decrease that is included in the plurality of linear structures and decreases the thermal conductivity of the linear structures. A thermoelectric conversion element having a thermoelectric conversion material film formed of a thermoelectric conversion material having a substance and a pair of electrodes sandwiching the thermoelectric conversion material film is provided.

  According to still another aspect of the embodiment, a plurality of linear structures of carbon elements and a thermal conductivity that is included in the plurality of linear structures and lowers the thermal conductivity of the linear structures. A p-type first thermoelectric conversion material film formed of a thermoelectric conversion material having a reducing substance, a plurality of linear structures of carbon elements, and a plurality of the linear structures, and the linear structure An n-type second thermoelectric conversion material film formed of a thermoelectric conversion material having a thermal conductivity lowering substance that lowers the thermal conductivity of the body, and formed on one surface side of the first thermoelectric conversion material film The first electrode formed, the second electrode formed on one surface side of the second thermoelectric conversion material film, the other of the first thermoelectric conversion material film and the second thermoelectric conversion material film There is provided a thermoelectric conversion element having a third electrode formed on the surface side.

  According to the disclosed thermoelectric conversion material, it is possible to reduce the thermal conductivity of the carbon element linear structure while maintaining the high electric conductivity of the carbon element linear structure. Thereby, a highly efficient thermoelectric conversion material having a large figure of merit ZT can be realized. Moreover, a thermoelectric conversion element with high thermoelectric conversion efficiency is realizable by forming a thermoelectric conversion element using this thermoelectric conversion material.

[First Embodiment]
A thermoelectric conversion material and a thermoelectric conversion element according to the first embodiment will be described with reference to FIGS.

  FIG. 1 is a schematic cross-sectional view showing the structure of the thermoelectric conversion element according to the present embodiment. FIG. 2 is a schematic view showing the structure of the thermoelectric conversion material of the thermoelectric conversion element according to the present embodiment. 3 and 4 are process cross-sectional views illustrating the method for manufacturing the thermoelectric conversion element according to the present embodiment. FIG. 5 is a schematic cross-sectional view showing a thermoelectric conversion element and a manufacturing method thereof according to a modification of the present embodiment.

  First, the structure of the thermoelectric conversion element according to the present embodiment will be described with reference to FIGS. 1 and 2.

  As shown in FIG. 1, the thermoelectric conversion element has a thermoelectric conversion material film 12p formed of a p-type semiconductor thermoelectric conversion material, and a thermoelectric conversion material film 12n formed of an n-type semiconductor thermoelectric conversion material. ing. The thermoelectric conversion material film 12 p is sandwiched between the electrode 10 and the electrode 14. The thermoelectric conversion material 12n is sandwiched between an electrode 10 and a common electrode 10 that sandwich the thermoelectric conversion material film 12p.

  When the electrode 10 side of this thermoelectric conversion element is arranged in the high temperature part and the electrodes 14 and 16 side are arranged in the low temperature part, the electrode 14 is placed in the positive direction between the electrode 10 side and the electrode 14 side of the thermoelectric conversion material film 12p. An electromotive force is generated. Further, an electromotive force with the electrode 16 in the negative direction is generated between the electrode 10 side and the electrode 16 side of the thermoelectric conversion material film 12n (Seebeck effect). Thereby, electric power is supplied from the electrodes 14 and 16 to the outside. Conversely, when a voltage is applied between the electrode 10 and the electrodes 14 and 16, one electrode side is heated and the other electrode side is cooled (Peltier effect).

  In the thermoelectric conversion element according to the present embodiment, in the thermoelectric conversion element as shown in FIG. 1, the thermoelectric conversion material forming the thermoelectric conversion material films 12p and 12n has the structure shown in FIG. That is, the thermoelectric conversion material of the thermoelectric conversion element according to the present embodiment has a plurality of carbon nanotubes 20 oriented in the same direction. Each carbon nanotube contains a fullerene 22 to form a so-called peapod.

  The carbon nanotube 20 is a substance that is extremely excellent in electrical conductivity and thermal conductivity. The structure in which the fullerene 22 is included in the carbon nanotube 20 does not change the structure of the carbon nanotube 20 itself, and does not significantly hinder electric conduction. On the other hand, since fullerenes 22 which are different materials are adjacent to the carbon nanotubes 20, phonons propagating through the carbon nanotubes are effectively scattered by the influence of the fullerenes 22, and the thermal conductivity is large (less than several percent). Until). Thereby, the thermoelectric conversion material which has high electrical conductivity and low thermal conductivity and has a high figure of merit ZT can be formed.

  The carbon nanotubes 20 exhibit p-type and n-type conductivity types by adding appropriate impurities. Therefore, by forming the thermoelectric conversion material films 12p and 12n of the thermoelectric conversion element shown in FIG. 1 with the thermoelectric conversion material according to the present embodiment, a highly efficient thermoelectric conversion element can be realized.

  The carbon nanotube 20 may be a single-walled carbon nanotube or a multi-walled carbon nanotube. However, since the decrease in thermal conductivity due to the fullerene 22 is brought to the innermost tube adjacent to the fullerene 22, if the number of layers is increased too much, the effect of decreasing the thermal conductivity in the entire carbon nanotube 20 cannot be obtained sufficiently. From this point of view, it is desirable that the carbon nanotubes have a smaller number of layers, such as a single layer, two layers, or three layers.

  The substance included in the carbon nanotube 20 is not particularly limited as long as it is a substance that does not easily disturb the electrical characteristics of the carbon nanotube 20 and can reduce the thermal conductivity by scattering phonons propagating through the carbon nanotube. It is not something. In this embodiment, fullerene 22 is illustrated as an example. In the present specification, a substance that does not easily disturb the electrical characteristics of the carbon nanotube 20 and that scatters phonons propagating through the carbon nanotube and decreases thermal conductivity may be referred to as a “thermal conductivity decreasing substance”. is there.

  Although FIG. 2 shows a case where fullerenes 22 are formed in a row in each carbon nanotube 20, a plurality of rows of fullerenes 22 may be formed in each carbon nanotube 20.

In addition, the fullerene 22 is not only a typical C ₆₀ fullerene having 60 carbon atoms, but also a higher-order fullerene having more than 60 carbon atoms such as 70, 80, 82, 84 carbon atoms. It may be. Further, the fullerene 22 may be an atomic inclusion fullerene (also referred to as “metal inclusion fullerene”). An atomic inclusion fullerene is an atom such as Gd (gadolinium), La (lanthanum), Sc (scandium), Y (yttrium), Tb (terbium), Dy (dysprosium), Er (erbium), etc. in these fullerenes. One or more. In this specification, all of these are comprehensively expressed as “fullerene”.

  The reason why the fullerene 22 can be used as the thermal conductivity lowering substance is thought to be because the fullerene 22 (row) is not a continuous body unlike the carbon nanotube 20 and the conduction form of phonon is different from the carbon nanotube 20.

  Next, the manufacturing method of the thermoelectric conversion element according to the present embodiment will be explained with reference to FIGS.

  First, a substrate 30 is prepared as a base for growing the carbon nanotubes 20. As the substrate 30, a semiconductor substrate such as a silicon substrate, an alumina (sapphire) substrate, an MgO substrate, a glass substrate, or the like can be used. In addition, a thin film may be formed on these substrates. For example, a silicon substrate having a silicon oxide film with a thickness of about 300 nm can be used.

  Next, an Al (aluminum) film having a thickness of, for example, 5 nm and an Fe (iron) film having a thickness of, for example, 2.5 nm are deposited on the substrate 30 by, for example, sputtering, and the catalyst metal having a Fe / Al laminated structure is deposited. A film 32 is formed (FIG. 3A).

  In addition to the Fe / Al film, the catalytic metal film 32 is Fe, Co (cobalt), Ni (nickel), Au (gold), Ag (silver), Pt (platinum), or an alloy containing at least one of these materials. Alternatively, a single layer film may be used. In addition to the metal film, metal fine particles prepared by controlling the size in advance using a differential mobility analyzer (DMA) or the like may be used as the catalyst. In this case, the metal species may be the same as in the case of the thin film.

Further, as the base film of these catalyst metals, Mo (molybdenum), Ti (titanium), Hf (hafnium), Zr (zirconium), Nb (niobium), V (vanadium), TaN (tantalum nitride), TiSi _x (titanium Silicide), Al (aluminum), Al ₂ O ₃ (aluminum oxide), TiO _x (titanium oxide), Ta (tantalum), W (tungsten), Cu (copper), Au (gold), Pt (platinum), Pd A film of (palladium), TiN (titanium nitride), or an alloy film containing at least one of these materials may be formed. For example, in addition to the above-described Fe / Al laminated structure, a Co (2.6 nm) / TiN (5 nm) laminated structure or the like can be applied. When metal fine particles are used, for example, a laminated structure such as Co (average diameter: 3.8 nm) / TiN (5 nm) can be applied.

  Next, the carbon nanotubes 20 are grown on the substrate 30 by, for example, a thermal CVD method using the catalytic metal film 32 as a catalyst. The growth conditions of the carbon nanotube are, for example, using a mixed gas of acetylene / argon diluted with hydrogen as a source gas (acetylene: argon = 1: 9, ratio of the mixed gas to the total gas amount: 18%). The total gas pressure is 1 kPa, the substrate temperature is 590 ° C., and the growth time is 90 minutes. Thereby, a multi-walled carbon nanotube having two layers and a length of about 1 mm can be grown. The carbon nanotubes may be formed by other film forming methods such as a hot filament CVD method and a remote plasma CVD method. The growing carbon nanotube may be a single-walled carbon nanotube. Moreover, as a carbon raw material, you may use hydrocarbons, such as methane and ethylene other than acetylene, alcohols, such as ethanol and methanol.

  Thus, a plurality of carbon nanotubes 20 aligned in the normal direction of the substrate 30 (vertical alignment) are formed on the substrate 30 (FIG. 3B).

  Next, the substrate temperature is set to, for example, 550 ° C. while the substrate 30 on which the carbon nanotubes 20 are grown is placed in the reaction furnace of the CVD apparatus, and oxygen is introduced into the reaction furnace at a pressure of, for example, 1 kPa. By performing an oxidation treatment for about 10 minutes in this state, an opening (not shown) is formed at the tip of the carbon nanotube 20 or a part of the side wall.

  Next, a fullerene placed in a crucible is placed beside the substrate 30 in the reaction furnace of the CVD apparatus, heated to 500 to 600 ° C. by vacuum sealing, and left for several hours. Thereby, the fullerene put in the crucible is sublimated and enters the inside of the carbon nanotube 20 from the opening. In this way, carbon nanotubes 20 in which fullerenes 22 are encapsulated, so-called peapods, are formed (FIG. 3C).

  Next, predetermined impurities are ion-implanted into the carbon nanotubes 20 by, for example, ion implantation, and the carbon nanotubes 20 are given p-type or n-type conductivity. For example, boron or the like can be applied as the p-type impurity. As the n-type impurity, for example, nitrogen, phosphorus, or the like can be used.

  In this way, a substrate 30p having a thermoelectric conversion material film 12p formed of p-type carbon nanotubes 20 and a substrate 30n having a thermoelectric conversion material film 12n formed of n-type carbon nanotubes 20 are prepared ( FIG. 4 (a)).

  Next, a conductive adhesive 34 p such as silver paste is applied on the thermoelectric conversion material film 12 p, and a metal substrate 40 such as Cu (copper) is bonded onto the conductive adhesive 34. Similarly, a conductive adhesive 34n such as silver paste is applied on the thermoelectric conversion material film 12n, and a metal substrate 42 such as Cu (copper) is bonded on the conductive adhesive 36 (FIG. 4B). ).

  Next, the substrate 30p is peeled from the thermoelectric conversion material film 12p. Similarly, the substrate 30n is peeled from the thermoelectric conversion material film 12n.

  Next, the conductive adhesive 36p is applied on the peeling surface of the substrate 30p of the thermoelectric conversion material film 12p, and the conductive adhesive 36n is applied on the peeling surface of the substrate 30n of the thermoelectric conversion material film 12n, and then conductive bonding is performed. A metal substrate 44 such as Cu (copper) is bonded onto the agents 36p and 36n (FIG. 4C).

  Thus, the electrode 10 is formed by the metal substrate 44, the electrode 14 is formed by the metal substrate 40, and the electrode 16 is formed by the metal substrate 42, and the thermoelectric conversion material film 12 p is sandwiched between the electrode 10 and the electrode 14. The thermoelectric conversion element according to the present embodiment in which the thermoelectric conversion material film 12n is sandwiched between the thermoelectric conversion material film 12n and the thermoelectric conversion material film 16 is completed.

  For example, as shown in FIG. 5, if a plurality of the basic structures shown in FIG. 4C are connected in series via the electrodes of the metal substrate 46 by the same technique, a thermoelectric conversion element having a desired electromotive force is formed. can do. The basic structures shown in FIG. 4C may be arranged in a matrix.

  As described above, according to the present embodiment, since the thermoelectric conversion material including the carbon nanotube including the thermal conductivity reducing substance that reduces the thermal conductivity of the carbon nanotube is formed, the high electrical conductivity of the carbon nanotube is maintained. However, the thermal conductivity can be reduced. Thereby, a highly efficient thermoelectric conversion material having a high figure of merit ZT can be realized. Moreover, a thermoelectric conversion element with high thermoelectric conversion efficiency is realizable by forming a thermoelectric conversion element using this thermoelectric conversion material.

[Second Embodiment]
A thermoelectric conversion material and a thermoelectric conversion element according to the second embodiment will be described with reference to FIGS.

  FIG. 6 is a schematic cross-sectional view showing the structure of the thermoelectric conversion material of the thermoelectric conversion element according to the present embodiment. FIG. 7 is a process cross-sectional view illustrating the method for manufacturing the thermoelectric conversion element according to the present embodiment.

  First, the structure of the thermoelectric conversion material according to the present embodiment will be described with reference to FIG.

  As shown in FIG. 6, the thermoelectric conversion material according to the present embodiment uses molybdenum oxide 24 instead of fullerene 22 as a thermal conductivity decreasing substance included in the carbon nanotube 20.

  As described above, the substance included in the carbon nanotube 20 is a substance that does not obstruct the electrical characteristics of the carbon nanotube 20 and that can scatter phonons propagating through the carbon nanotube and reduce thermal conductivity. For example, the fullerene 22 is not limited. Molybdenum oxide is an insulating material that can be encapsulated in the carbon nanotubes 20 and is a substance that does not obstruct the electrical characteristics of the carbon nanotubes 20, so it is applied as a thermal conductivity lowering substance that is encapsulated in the carbon nanotubes 20. can do.

  The thermoelectric conversion material by this embodiment is applicable to the thermoelectric conversion element shown, for example in FIG.1 and FIG.6 similarly to the thermoelectric conversion material by 1st Embodiment.

  Next, the manufacturing method of the thermoelectric conversion element according to the present embodiment will be explained with reference to FIG.

  First, for example, the carbon nanotubes 20 are formed on the substrate 30 in the same manner as the manufacturing method of the thermoelectric conversion element according to the first embodiment shown in FIGS. 3A to 3B (FIG. 7A). .

  Next, the substrate temperature is set to, for example, 550 ° C. while the substrate 30 on which the carbon nanotubes 20 are grown is placed in the reaction furnace of the CVD apparatus, and oxygen is introduced into the reaction furnace at a pressure of, for example, 1 kPa. By performing an oxidation treatment for about 10 minutes in this state, an opening (not shown) is formed at the tip of the carbon nanotube 20 or a part of the side wall.

  At this time, if the molybdenum powder placed in the crucible is placed beside the substrate 30, an opening is formed in the carbon nanotube 20, and at the same time, the sublimated and oxidized molybdenum enters the carbon nanotube 20. Thereby, the carbon nanotube 20 including the molybdenum oxide 24 is formed (FIG. 7B).

  Thereafter, the thermoelectric conversion element is completed in the same manner as the manufacturing method of the thermoelectric conversion element according to the first embodiment shown in FIGS. 4A to 4C, for example.

  As described above, according to the present embodiment, since the thermoelectric conversion material including the carbon nanotube including the thermal conductivity reducing substance that reduces the thermal conductivity of the carbon nanotube is formed, the high electrical conductivity of the carbon nanotube is maintained. However, the thermal conductivity can be reduced. Thereby, a highly efficient thermoelectric conversion material having a high figure of merit ZT can be realized. Moreover, a thermoelectric conversion element with high thermoelectric conversion efficiency is realizable by forming a thermoelectric conversion element using this thermoelectric conversion material.

[Third Embodiment]
A thermoelectric conversion material and a thermoelectric conversion element according to the third embodiment will be described with reference to FIGS. 8 and 9.

  FIG. 8 is a schematic view showing the structure of the thermoelectric conversion material of the thermoelectric conversion element according to the present embodiment. FIG. 9 is a process cross-sectional view illustrating the method for manufacturing the thermoelectric conversion element according to the present embodiment.

  First, the structure of the thermoelectric conversion material according to the present embodiment will be described with reference to FIG.

  As shown in FIG. 8, the thermoelectric conversion material according to the present embodiment is obtained by embedding carbon nanotubes 20 with a filling layer 26 formed of a thermal conductivity lowering substance. The carbon nanotubes 20 contain a thermal conductivity lowering substance as in the first and second embodiments. Here, as an example, the carbon nanotubes 20 in which the fullerenes 22 are encapsulated are shown, but the thermal conductivity reducing substance encapsulated in the carbon nanotubes 20 is not limited to this.

  In addition to the inside of the carbon nanotube 20, the thermal conductivity of the carbon nanotube 20 can be more effectively lowered by disposing a substance having a reduced thermal conductivity around the carbon nanotube 20.

  For example, in the case of the double-walled carbon nanotube 20, the effect of lowering the thermal conductivity with respect to the innermost carbon nanotube can be obtained just by encapsulating the substance having a reduced thermal conductivity, but the outer carbon nanotube has its effect. The effect is not obtained. The thermal conductivity of the outermost carbon nanotube can also be reduced by disposing a thermal conductivity reducing substance around the carbon nanotube 20. However, also in this embodiment, it is desirable that the number of the carbon nanotubes is small, such as a single layer, two layers, or three layers.

  The material of the filling layer 26 provided around the carbon nanotubes 20 is a substance that hardly disturbs the electrical characteristics of the carbon nanotubes 20 like the substance contained therein, and scatters phonons propagating through the carbon nanotubes to lower the thermal conductivity. The substance is not particularly limited as long as it can be used.

  Examples of the thermal conductivity lowering substance provided around the carbon nanotube 20 include a semiconductor material, an insulating material, and a resin material.

As semiconductor materials, oxide semiconductors such as ZnO, SrTiO ₃ , InGaZnO ₄ , Al _x Zn _1-x O _y , SrTi _1-x Nb _x O _y , Si, GaAs, GaN, InP, Ge, SiGe, etc. are applied. can do.

  As the insulating material, molybdenum oxide, silicon oxide, SiOC, porous silica, porous SiOC, SOG, aluminum oxide, ceramics, or the like can be used.

  As the resin material, silicone, acrylic resin, vinyl chloride resin, polypropylene, polycarbonate, PET resin, vinylidene chloride resin, fluororesin (PTEE), elastomer, or the like can be used.

  Next, the manufacturing method of the thermoelectric conversion element according to the present embodiment will be explained with reference to FIG.

  First, for example, in the same manner as the manufacturing method of the thermoelectric conversion element according to the first embodiment shown in FIGS. 3A to 3C, the carbon nanotubes 20 including the fullerenes 22 are formed on the substrate 30 (see FIG. 3A). FIG. 9A). Note that the material having a reduced thermal conductivity included in the carbon nanotube 20 may not be the fullerene 22.

  Next, SOG (Spin On Glass) is applied by, eg, spin coating. Thereby, the gap between the carbon nanotubes 20 is filled with the SOG.

  Next, the substrate 30 coated with SOG is baked to cure the SOG. Thus, the filling layer 26 made of SOG is formed around the carbon nanotubes 20 (FIG. 9B).

  Thereafter, the thermoelectric conversion element is completed in the same manner as the manufacturing method of the thermoelectric conversion element according to the first embodiment shown in FIGS. 4A to 4C, for example.

  As described above, according to the present embodiment, the carbon nanotube containing the thermal conductivity decreasing material that decreases the thermal conductivity of the carbon nanotube is formed in the thermal conductivity decreasing material that decreases the thermal conductivity of the carbon nanotube. Since the thermoelectric conversion material is formed, the thermal conductivity can be lowered while maintaining the high electrical conductivity of the carbon nanotube. Thereby, a highly efficient thermoelectric conversion material having a high figure of merit ZT can be realized. Moreover, a thermoelectric conversion element with high thermoelectric conversion efficiency is realizable by forming a thermoelectric conversion element using this thermoelectric conversion material.

[Modified Embodiment]
The present invention is not limited to the above embodiment, and various modifications are possible.

  For example, in the first embodiment, fullerene is exemplified as the thermal conductivity decreasing substance included in the carbon nanotube, and molybdenum oxide is exemplified in the second embodiment. However, the thermal conductivity decreasing substance included in the carbon nanotube is limited to this. It is not something.

As the thermal conductivity lowering substance included in the carbon nanotube 20, a semiconductor material or other insulating material can be applied in addition to fullerene and molybdenum oxide. For example, semiconductor materials include oxide semiconductors such as ZnO, SrTiO ₃ , InGaZnO ₄ , Al _x Zn _1-x O _y , SrTi _1-x Nb _x O _y , Si, GaAs, GaN, InP, Ge, SiGe, and the like. Can be applied. As the insulating material, silicon oxide, SiOC, porous silica, porous SiOC, SOG, aluminum oxide, or the like can be used. From the viewpoint of introduction into the carbon nanotube, it is desirable that the thermal conductivity-decreasing substance encapsulated in the carbon nanotube is a material that can be sublimated at a temperature at which the carbon nanotube is not destroyed.

  Moreover, although the thermoelectric conversion material using a carbon nanotube was shown in the said embodiment, you may form a thermoelectric conversion material using the linear structure of another carbon element. Examples of the carbon element linear structure include carbon nanowires, carbon rods, and carbon fibers in addition to carbon nanotubes. These linear structures are the same as the carbon nanotubes except that their sizes are different. The present invention can also be applied to a sheet-like structure using these linear structures.

  Moreover, in the said embodiment, although the thermoelectric conversion material which orientated the carbon nanotube in one direction was shown, it does not necessarily need to orient in one direction. For example, the thermoelectric conversion material may be formed by dispersing carbon nanotubes encapsulating a thermal conductivity lowering substance in a packed layer of the thermal conductivity lowering substance.

  In this case, first, a resin before curing is prepared in a container, and a carbon nanotube powder encapsulating a preformed heat conductivity reducing substance is put in the container. The carbon nanotubes can be uniformly mixed with the resin by stirring or ultrasonic waves. If necessary, an additive such as a surfactant may be added to the resin. Thereafter, by curing the resin with heat or ultraviolet rays, it is possible to form a thermoelectric conversion material in which the carbon nanotubes encapsulating the thermal conductivity reducing substance are dispersed. Instead of the resin material in which the carbon nanotubes are dispersed, other thermal conductivity lowering substances described in the above embodiments such as SOG may be used.

  Further, the constituent materials and manufacturing conditions disclosed in the above embodiment are not limited to the disclosed contents, and can be appropriately changed according to the purpose and the like.

  The disclosed heat conduction conversion element can be used for various purposes as a power supply source in an environment where heat is generated or as a cooling device. The application of the disclosed thermoelectric conversion element is not particularly limited, and examples thereof include wireless / mobile phone base stations, servers / personal computers, automobiles, artificial satellites, buildings, and the like.

FIG. 1 is a schematic cross-sectional view showing the structure of the thermoelectric conversion element according to the first embodiment. FIG. 2 is a schematic view showing the structure of the thermoelectric conversion material of the thermoelectric conversion element according to the first embodiment. FIG. 3 is a process cross-sectional view (part 1) illustrating the method for manufacturing the thermoelectric conversion element according to the first embodiment. FIG. 4 is a process cross-sectional view (part 2) illustrating the method for manufacturing the thermoelectric conversion element according to the first embodiment. FIG. 5 is a schematic cross-sectional view showing a thermoelectric conversion element and a manufacturing method thereof according to a modification of the first embodiment. FIG. 6 is a schematic view showing the structure of the thermoelectric conversion material of the thermoelectric conversion element according to the second embodiment. FIG. 7 is a process cross-sectional view illustrating the method for manufacturing the thermoelectric conversion element according to the second embodiment. FIG. 8 is a schematic view showing the structure of the thermoelectric conversion material of the thermoelectric conversion element according to the third embodiment. FIG. 9 is a process cross-sectional view illustrating the method for manufacturing the thermoelectric conversion element according to the third embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 14, 16 ... Electrode 12n, 12p ... Thermoelectric conversion material film 20 ... Carbon nanotube 22 ... Fullerene 24 ... Molybdenum oxide 26 ... Filling layer 30 ... Substrate 32 ... Catalyst metal film 34n, 34p, 36n, 36p ... Conductive adhesive 40, 42, 44, 46 ... metal substrate

Claims (7)

A plurality of linear structures of carbon elements;
A thermoelectric conversion material comprising: a thermal conductivity reducing substance that is included in the plurality of linear structures and decreases the thermal conductivity of the linear structures. The thermoelectric conversion material according to claim 1,
The plurality of linear structures are oriented in the same direction. A thermoelectric conversion material, wherein: In the thermoelectric conversion material according to claim 1 or 2,
The linear structure has a single-layer structure, a two-layer structure, or a three-layer structure. In the thermoelectric conversion material according to any one of claims 1 to 3,
A thermoelectric conversion material further comprising a packed layer of a thermal conductivity lowering substance formed between the plurality of linear structures. In the thermoelectric conversion material according to any one of claims 1 to 4,
The thermoelectric conversion material, wherein the thermal conductivity-decreasing substance contained in the linear structure is fullerene. A thermoelectric element formed of a thermoelectric conversion material having a plurality of linear structures of carbon elements and a thermal conductivity-decreasing substance included in the plurality of linear structures and reducing the thermal conductivity of the linear structures. A conversion material film;
A thermoelectric conversion element comprising: a pair of electrodes that sandwich the thermoelectric conversion material film. P formed of a thermoelectric conversion material having a plurality of linear structures of carbon elements and a thermal conductivity reducing substance included in the plurality of linear structures and reducing the thermal conductivity of the linear structures. A first thermoelectric conversion material film of a mold;
N formed by a thermoelectric conversion material having a plurality of linear structures of carbon elements and a thermal conductivity reducing substance included in the plurality of linear structures and reducing the thermal conductivity of the linear structures. A second thermoelectric conversion material film of the mold;
A first electrode formed on one surface side of the first thermoelectric conversion material film;
A second electrode formed on one surface side of the second thermoelectric conversion material film;
A thermoelectric conversion element comprising: a third electrode formed on the other surface side of the first thermoelectric conversion material film and the second thermoelectric conversion material film.

Images