KR20100131282A - Thermoelectric device and method for manufacturing the same - Google Patents

Abstract

PURPOSE: A thermoelectric device and a method for manufacturing the same are provided to be used for electronic appliances or waste heat generators by improving a thermoelectric power factor. CONSTITUTION: A plurality of nano-structures(10) contains magnetic materials. The nano-structures are expanded to the X-axis direction. A thermoelectric unit(20) is closely arranged to the nano-structures. The thermoelectric unit is capable of being substituted as the surface of the nano-structures. The electric conductivity of the nano-structures is higher than that of the thermoelectric unit.

Description

Thermoelectric device and manufacturing method thereof {THERMOELECTRIC DEVICE AND METHOD FOR MANUFACTURING THE SAME}

The present invention relates to a thermoelectric device and a method of manufacturing the same. More specifically, the present invention relates to a thermoelectric device having improved thermoelectric efficiency using a nanostructure and a method of manufacturing the same.

Research into thermoelectric elements that convert heat into electricity is being actively conducted. The Seebeck effect in which electromotive force is generated by the temperature difference may be used to convert heat into electricity in a thermoelectric element.

Bismuth telluride (BiTe) or antimony telluride (SbTe) is used as a material of the thermoelectric element. Since bismuth telluride (BiTe) or antimony telluride (SbTe) is excellent in conductivity and thermal power, it is widely used as a material for thermoelectric devices.

It is intended to provide a thermoelectric device having improved thermoelectric efficiency by using a nanostructure. It is also an object of the present invention to provide a method of manufacturing a thermoelectric device.

A thermoelectric device according to an embodiment of the present invention includes: i) a material of high conductivity, a plurality of nanostructures extending in one direction, and ii) a thermoelectric material in contact with at least one of the plurality of nanostructures. do.

The thermoelectric material may be formed to be substituted on the surface of the nanostructure. The thermoelectric material forms a base layer, and the plurality of nanostructures may be embedded in the base layer. The thermoelectric material may include one or more materials selected from the group consisting of bismuth telluride (BiTe), antimony telluride (SbTe), silicon, silicon germanium (SiGe), and semiconductor oxide. Materials of high conductivity include nickel (Ni), copper (Cu), cobalt (Co), iron (Fe), silver (Ag), gold (Au), molybdenum (Mo), tin (Sn), and alloys thereof. It may include one or more elements selected from the group. The high conductivity material includes a high concentration doped semiconductor material, and the semiconductor material may be one or more materials selected from the group consisting of chalcogenide-based materials, Si, SiGe, BiTe, and SbTe.

Nanostructures can be nanorods, nanotubes or nanowires. The electrical conductivity of the material may be 0.09 × 10 ⁶ / cm · to 0.6 × 10 ⁶ / cm ·. The material may further comprise a magnetic material.

Method for manufacturing a thermoelectric device according to an embodiment of the present invention, i) providing a plurality of nanostructures comprising a material of high electroconductivity, extending in one direction, ii) at least one nanostructure of the plurality of nanostructures Providing a contacting thermoelectric material, iii) aligning the plurality of nanostructures in one direction, and iv) sintering the aligned plurality of nanostructures.

In the aligning of the plurality of nanostructures in one direction, the nanostructures may be aligned in one direction by applying a magnetic field to the plurality of nanostructures. In the providing of the thermoelectric material, the surface of the plurality of nanostructures may be replaced with a thermoelectric material by mutual reaction with metal ions included in the plating solution by immersing the plurality of nanostructures in the plating solution. Metal ion may include ions tellurium (Te ^{2 +).} Metal ion may further contains antimony ions (Sb ^{3 +)} ions or bismuth (Bi ^{+ 3).}

In the providing of the plurality of nanostructures, the plurality of nanostructures may be manufactured by growing in one direction in the plating solution. The plurality of nanostructures may be manufactured by growing through openings formed in a nano template.

Thermoelectric devices with improved thermoelectric power factors can be fabricated. Therefore, the thermoelectric device may be used in an electronic device or a waste heat generator to greatly improve the thermoelectric conversion efficiency. In addition, since the thermoelectric device can be manufactured using a simple method, the manufacturing cost of the thermoelectric device can be reduced.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a,” “an,” and “the” include plural forms as well, unless the phrases clearly indicate the opposite. As used herein, the term "comprising" embodies a particular characteristic, region, integer, step, operation, element, and / or component, and other specific characteristics, region, integer, step, operation, element, component, and / or group. It does not exclude the presence or addition of.

Terms indicating relative space such as "below" and "above" may be used to more easily explain the relationship of one part to another part shown in the drawings. These terms are intended to include other meanings or operations of the device in use with the meanings intended in the figures. For example, turning the device in the figure upside down, some parts described as being "below" of the other parts are described as being "above" the other parts. Thus, the exemplary term "below" encompasses both up and down directions. The device can be rotated 90 degrees or at other angles, the terms representing relative space being interpreted accordingly.

Unless defined otherwise, all terms including technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. Commonly defined terms used are additionally interpreted to have a meaning consistent with the related technical literature and the presently disclosed contents, and are not interpreted in an ideal or very formal sense unless defined.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

1 schematically shows a thermoelectric device 100 according to a first embodiment of the invention. The structure of the thermoelectric device 100 of FIG. 1 is merely for illustrating the present invention, and the present invention is not limited thereto. Therefore, the thermoelectric device 100 of FIG. 1 may be modified in another form.

As shown in FIG. 1, the thermoelectric device 100 includes nanostructures 10 and a thermoelectric material 20. The nanostructure 10 extends in one direction, that is, along the x-axis direction. The nanostructure 10 includes a material of high conductivity. Here, the material may include nickel (Ni), cobalt (Co), copper (Cu), iron (Fe), silver (Ag), gold (Au), molybdenum (Mo), tin (Sn) or alloys thereof. Can be.

내지 0.6×10⁶/cm· 일 수 있다. 물질의 전기전도도가 너무 작은 경우, 나노 구조체(10)를 통한 전류의 이송 효율이 저하되므로, 열전 디바이스(100)의 효율이 저하된다. 또한, 물질의 전기전도도가 너무 큰 경우, 소재 비용이 증가한다.The electrical conductivity of the aforementioned materials is 0.09 × 10 ⁶ / cm

To 0.6 × 10 ⁶ / cm ·. If the electrical conductivity of the material is too small, the transfer efficiency of the current through the nano-structure 10 is lowered, the efficiency of the thermoelectric device 100 is lowered. In addition, if the electrical conductivity of the material is too large, the material cost increases.

In addition, the aforementioned material may include a high concentration doped semiconductor material. Here, Si, SiGe, BiTe or SbTe may be used as the semiconductor material. In this case, the nanostructure 10 may be manufactured using a gas phase-liquid-solid phase (VLS) method or a wet electrolytic etching method.

In addition, the aforementioned material may include a chalcogenide-based material. Examples of chalcogenide materials include BiSb or SnTe. The chalcogenide material responds well to external stimuli such as electric energy, heat energy, and light energy, and thus is suitable for use as the aforementioned material.

The nanostructure 10 may further include a magnetic material. In this case, the nanostructures 10 may be aligned in one direction by applying a magnetic field before sintering the nanostructures 10. Meanwhile, even if the nanostructure 10 does not contain a magnetic material, the nanostructures 10 may be aligned by using a Langmuir-Blodgett (LB) method.

1 illustrates a nano-rod shaped nanostructure 10, the shape of the nanostructure 10 may be variously modified. Therefore, the nanostructure 10 may be formed of nanotubes or nanowires.

As shown in FIG. 1, the thermoelectric material 20 is in contact with the nanostructures 10. More specifically, the surfaces of the nanostructures 10 are formed by substitution with the thermoelectric material 20. Therefore, the core-shell nanostructures 10 may be manufactured. The thermoelectric material 20 may be provided in powder form.

As the material of the thermoelectric material 20, a compound semiconductor such as bismuth telluride (BiTe) or antimony telluride (SbTe), a semiconductor oxide, or the like may be used. In addition, as a material of the thermoelectric material 20, elements of Group 4B such as silicon or silicon germanium (SiGe) may be used. Since the above materials are excellent in thermoelectric conversion efficiency, they are suitable for use as the thermoelectric material 20.

Since the thermoelectric device 100 extends along the x-axis direction, the thermoelectric device 100 has directivity in one direction. Therefore, the current can be efficiently transferred along the x-axis direction. Since the electrical conductivity of the nanostructure 10 is higher than that of the thermoelectric material 20, current flows well through the nanostructure 10.

2 schematically shows a thermoelectric device 200 according to a second embodiment of the present invention. Since the structure of the thermoelectric device 200 of FIG. 2 is similar to that of the thermoelectric device 100 of FIG. 1, the same reference numerals are used for the same parts, and a detailed description thereof will be omitted.

As shown in FIG. 2, a base layer 13 made of a thermoelectric material is formed inside the thermoelectric device 200. The plurality of nanostructures 10 are embedded in the matrix 13. That is, the thermoelectric device 200 may be manufactured by embedding the plurality of nanostructures 10 in the matrix 13 made of a thermoelectric material and sintering them.

3 is a flowchart schematically illustrating a method of manufacturing the thermoelectric device 100 of FIG. 1. The method of manufacturing the thermoelectric device 100 of FIG. 3 is merely for illustrating the present invention, and the present invention is not limited thereto. Accordingly, the thermoelectric device 100 may be manufactured using other methods.

As shown in FIG. 3, the method of manufacturing the thermoelectric device 100 includes: i) providing nanostructures extending in one direction (S10), ii) providing thermoelectric material in contact with the nanostructures (S20), iii) aligning the nanostructures in one direction (S30), and iv) sintering the aligned nanostructures (S40). In addition, the method of manufacturing the thermoelectric device 100 may further include other necessary steps. Hereinafter, each detailed step of FIG. 2 will be described in more detail.

FIG. 4 schematically shows a nano template 12 for manufacturing nanostructures 10 (shown in FIG. 1, below) in step S10 of FIG. 3. The manufacturing method of such nanostructures 10 is merely to illustrate the present invention, but the present invention is not limited thereto. Therefore, the nanostructures 10 may be manufactured using other methods.

As shown in FIG. 4, nanostructures 10 are manufactured using a nano template 12 made of anodized aluminum oxide (AAO). One surface of the nano template 12 is deposited by copper (Cu) by sputtering and used as the seed layer 14. After the nanostructures 10 are grown from the seed layer 14 through the opening 121, the nanostructures 10 are separated from the nano template 12 and used. Here, the nanostructures 10 grow in the direction in which the opening 121 is formed. Therefore, since the nanostructures 10 having directivity can be manufactured, it is suitable to use the nanostructures 10 in the thermoelectric device 100 (shown in FIG. 1) requiring current transfer in one direction.

5 schematically shows an electrochemical device 300 for forming a nanostructure. The structure of the electrochemical device 300 of FIG. 5 is merely for illustrating the present invention, and the present invention is not limited thereto. Therefore, the structure of the electrochemical device 300 may be modified in other forms.

As shown in FIG. 5, the electrochemical device 200 includes three electrodes 12, 32, and 34. The three electrodes 12, 32, 36 act as cathode, anode and reference electrodes, respectively. Here, the cathode functions as a working electrode, and the anode functions as a counter electrode.

Ag / AgCl was used as a reference electrode 34 connected to the voltmeter 38, and a nano template 12 (shown in FIG. 4, below) was used as the cathode. In addition, platinum is used as the anode 32 connected to the ammeter 36. In the plating bath 30, a plating solution S containing metal ions is prepared. For example, when the nanostructure 10 is formed of nickel, a plating solution S containing nickel ions is prepared.

As shown in FIG. 5, the opening 121 of the nano-template 12 is formed by an electrochemical action between the seed layer 14 and the plating solution S deposited on the nano-template 12 by applying a power source 31. The nanostructure 10 is grown through (shown in FIG. 2).

After the nanostructure 10 is formed through the above-described method, the nanostructures 10 are manufactured by removing the seed layer 14 by mechanical polishing and dissolving the nano template 12 in a sodium hydroxide solution.

Referring back to FIG. 3, in step S20, a thermoelectric material in contact with the nanostructures 10 is provided. For example, the surface of the nanostructures 10 may be plated with a thermoelectric material.

6 is a diagram schematically illustrating a plating process of the nanostructures 10. The plating process of the nanostructures 10 of FIG. 6 is merely to illustrate the present invention, but the present invention is not limited thereto. Therefore, the plating process of the nanostructures 10 may be modified in various forms.

As shown in FIG. 6, the plating bath 40 includes nitric acid (N). And nitric acid (N) includes a metal ion, such as bismuth ions (Bi ^{3 +)} ion, and tellurium (Te ^{2 +).} Although not shown in FIG. 6, nitric acid (N) may include antimony ions and tellurium ions as metal ions.

When the nanostructures 10 are supported on nitric acid (N), galvanic displacement deposition occurs on the surfaces of the nanostructures 10. That is, the galvanic substitution reaction occurs due to the electrochemical potential difference between the components of the plating solution and the components of the nanostructures 10. Therefore, the surfaces of the nanostructures 10 may be replaced with BiTe or SbTe by interacting with metal ions. Through this manufacturing method, resistance at the interface between the nanostructures 10 and the thermoelectric material may be minimized. In particular, when the nanostructure 10 includes a metal, the nanostructure 10 is surface treated to prevent the formation of an oxide film on the surface of the nanostructure 10.

Through the aforementioned method, the nanostructure 10 covered with a thermoelectric material such as BiTe or SbTe may be obtained. As a result, a nanoshell 10 having a core shell structure, that is, a thermoelectric material formed in the shell portion, is manufactured.

3, in step S30, the nanostructures 10 covered with the thermoelectric material 20 are aligned in one direction. That is, since the nanostructures 10 are made of metal, applying the magnetic field may align the nanostructures 10 in one direction.

7 schematically illustrates a method of aligning nanostructures 10 in one direction. The alignment method of the nanostructures 10 of FIG. 7 is for illustration only, and the present invention is not limited thereto. Thus, other methods may be used to align the nanostructures 10.

A magnetic field is applied to the nanostructures 10 while dispersing the nanostructures 10 in a vacuum chamber (not shown) through a spraying method or the like. Therefore, the dispersed nanostructures 10 are aligned in one direction by a magnetic field.

That is, as shown in FIG. 7, the nanostructures 10 are located between the magnets 60 disposed on both sides thereof. Since the nanostructures 10 are made of metal, the nanostructures 10 are aligned in the x-axis direction by a magnetic field generated by the magnets 60.

Since the thermoelectric material 12 is made of a semiconductor material, it is hardly affected by the magnetic field. Therefore, the nanostructures 10 are well dispersed by the magnetic field, while the thermoelectric material 12 is not affected by the magnetic field.

3, finally, in step S40, the aligned nanostructures 10 (shown in FIG. 7) are sintered. The nanostructures 10 may be molded and sintered to produce a bulk thermoelectric device 100 (shown in FIG. 1). The nanostructures 10 may be sintered using a common sintering method, or using a hot press method or spark plasma sintering.

Hereinafter, the present invention will be described in more detail with reference to experimental examples. Such experimental examples of the present invention are merely for illustrating the present invention, and the present invention is not limited thereto.

Experimental Example  One

Nanowires made of nickel were prepared. Nanowires was immersed in a nitric acid solution containing the antimony ions (Sb ^{3 +)} ion, and tellurium (Te ^{2 +).}

Experimental Example  2

Nanowires made of nickel were prepared. Nanowires was immersed in a nitric acid solution containing bismuth ions (Bi ^{3 +)} ion, and tellurium (Te ^{2 +).}

Experimental Example  Experiment result of 1

Nickel on the surface of the nanowires was replaced with antimony telluride (SbTe). Thus, nanowires with a surface covered with antimony telluride (SbTe) were produced.

8 shows a scanning electron microscope (SEM) photograph of the surface of a nanowire prepared according to Experimental Example 1 of the present invention.

As shown in FIG. 8, antimony telluride (SbTe) formed of fine wires on the surface of the nanowires was observed. In addition, the surface components of the nanowires were analyzed using energy dispersive X-ray (EDX), and 31.91 wt% nickel (Ni), 22.09 wt% antimony (Sb) and 41.19 wt% tellurium (Te) This was measured. Therefore, it was confirmed that the surface of the nanowires was partially substituted with antimony telluride (SbTe).

Experimental Example  2 experimental results

The nickel component on the surface of the nanowires was replaced with bismuth telluride (BiTe). Thus, nanowires with a surface covered with bismuth telluride (BiTe) were produced.

9 shows a scanning electron micrograph of the surface of a nanowire prepared according to Experimental Example 2 of the present invention.

As shown in FIG. 9, bismuth telluride (BiTe) formed on the surface of the nanowires was observed. In addition, the surface components of the nanowires were analyzed by using energy dispersive X-ray (EDX). As a result, 4.23 wt% nickel (Ni), 43.44 wt% bismuth (Bi), and 50.89 wt% tellurium (Te) This was measured. Therefore, it was confirmed that the surface of the nanowire was partially substituted with bismuth telluride (BiTe).

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, Of course.

1 is a schematic diagram of a thermoelectric device according to a first embodiment of the present invention.

2 is a schematic diagram of a thermoelectric device according to a second embodiment of the present invention.

3 is a schematic flowchart of a method of manufacturing the thermoelectric device of FIG. 1.

4 is a schematic diagram of a nano template for manufacturing nanostructures.

5 is a schematic diagram of an electrochemical device for forming nanostructures.

6 is a view schematically illustrating a plating process of nanostructures.

7 is a schematic view illustrating a method of aligning nanostructures in one direction.

8 is a scanning electron micrograph of the surface of a nanowire prepared according to Experimental Example 1 of the present invention.

9 is a scanning electron micrograph of the surface of the nanowire prepared according to Experimental Example 2 of the present invention.

.

Claims (16)

A plurality of nanostructures comprising a material of high electroconductivity, extending in one direction, and Thermoelectric material in contact with one or more nanostructures of the plurality of nanostructures Thermoelectric device comprising a. The method of claim 1, The thermoelectric material is formed on the surface of the nano-structure substituted thermoelectric device. The method of claim 1, And the thermoelectric material forms a matrix, and the plurality of nanostructures are embedded in the matrix. The method of claim 1, The thermoelectric material includes at least one material selected from the group consisting of bismuth telluride (BiTe), antimony telluride (SbTe), silicon, silicon germanium (SiGe) and semiconductor oxide. The method of claim 1, The material of the high conductivity is nickel (Ni), copper (Cu), cobalt (Co), iron (Fe), silver (Ag), gold (Au), molybdenum (Mo), tin (Sn) and alloys thereof A thermoelectric device comprising at least one element selected from the group consisting of. The method of claim 1, The high conductivity material includes a highly doped semiconductor material, and the semiconductor material is at least one material selected from the group consisting of chalcogenide-based materials, Si, SiGe, BiTe, and SbTe. The method of claim 1, The nanostructures are nanorods, nanotubes or nanowires. The method of claim 1, The thermal conductivity of the material is 0.09 × 10 ⁶ / cm · to 0.6 × 10 ⁶ / cm ·. The method of claim 1, The material further comprises a magnetic material. Providing a plurality of nanostructures comprising a material of high electroconductivity and extending in one direction, Providing a thermoelectric material in contact with one or more nanostructures of the plurality of nanostructures, Aligning the plurality of nanostructures in one direction, and Sintering the aligned plurality of nanostructures Method of manufacturing a thermoelectric device comprising a. The method of claim 10, And in the aligning of the plurality of nanostructures in one direction, applying a magnetic field to the plurality of nanostructures to align the nanostructures in one direction. The method of claim 10, The providing of the thermoelectric material may include: a thermoelectric device for submerging the plurality of nanostructures in a plating solution to replace the surfaces of the plurality of nanostructures with a thermoelectric material by mutual reaction with metal ions included in the plating solution. Method of preparation. The method of claim 12, The metal ions method for manufacturing a thermoelectric device comprising a tellurium ions (Te ^{2 +).} The method of claim 13, The metal ions method of producing a thermal transfer device further comprises an antimony ions (Sb ^{3 +)} ions or bismuth (Bi ^{+ 3).} The method of claim 10, In the providing of the plurality of nanostructures, the plurality of nanostructures are produced by growing in one direction in a plating solution. The method of claim 15, The nanostructures are manufactured by growing through openings formed in a nano template.

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