KR20160078648A - Organic-inorganic hybrid thermoelectric material comprising bismuth telluride and polymer of bulk type and the method for preparation thereof - Google Patents

Abstract

The present invention provides a bulk-type organic-inorganic hybrid thermoelectric material including Bi_2Te_3 and polymer. According to the bulk-type organic-inorganic hybrid thermoelectric material of the present invention, polymer and Bi_2Te_3 are physically and chemically combined with each other, so that the electric and thermal properties are changed, thereby improving the thermoelectric figure of merit. In addition, the bulk-type organic-inorganic hybrid thermoelectric material has a property suitable to a thermoelectric field as a thermoelectric material. In advance, Bi_2Te_3 powder is prepared through a method for preparing a bulk-type organic-inorganic hybrid thermoelectric material, so that the firing temperature for preparing a final organic-inorganic hybrid thermoelectric material is reduced to be prepared in a bulk-type.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an organic-inorganic hybrid thermoelectric material including a bulk type Bi2Te3 and a polymer, and a method of manufacturing the same,

The present invention relates to an organic / inorganic hybrid thermoelectric material including bulk type Bi ₂ Te ₃ and a polymer, and a method for producing the same.

Recently, demand for energy recycling is increasing rapidly. In addition, due to the generation of carbon dioxide resulting from the use of fossil fuels, many unexpected changes such as global warming are occurring. Thermal power generation technology capable of generating electric energy from waste heat for recycling waste heat energy and suppressing the generation of carbon dioxide is suggested as a good alternative to such a problem.

Unlike conventional power generation technologies, thermoelectric power generation technology can directly convert thermal energy into electric energy in a solid state, and has advantages of quietness, long life, easy maintenance, and no generation of carbon dioxide. In addition, the power generation capacity can be expanded to various capacities from micro watts to megawatts. It can be applied to a wide variety of applications such as an isolated power source for a remote island, a military power source for a field, a distributed power source using an incinerator waste heat outside an urban area, and a biomedical power source using heat.

Thermoelectric generators are collectively referred to as technologies for converting waste heat generated in various industrial and living environments into electromotive force through thermoelectric elements. That is, heat energy is converted into electric energy using the Seebeck effect. The energy conversion efficiency of the thermoelectric element depends on the performance index (ZT) of the thermoelectric material. The performance index of the thermoelectric material, that is, the thermoelectric performance index is proportional to the temperature T and can be determined by the heat transfer coefficient (?), The electric conductivity (?) And the Seebeck coefficient (?) Of each thermoelectric material One).

(1) ZT =? ² ? T /?

(ZT is the thermoelectric performance index, α is the whiteness factor, σ is the electrical conductivity, T is the temperature, and κ is the thermal conductivity.)

Generally, there is a problem that the inorganic thermoelectric material has a high whitening coefficient, high electrical conductivity, and high thermal conductivity. Further, although the organic thermoelectric material has the advantage of low thermal conductivity, there is a problem that the electric conductivity is insufficient. By hybridizing the inorganic thermoelectric material and the organic thermoelectric material having the advantages and disadvantages as described above, it is possible to simultaneously develop the properties of the organic thermoelectric material and the inorganic thermoelectric material to simultaneously exhibit low thermal conductivity, high whitening coefficient, Research on thermoelectric materials is underway.

As an example of hybridizing the organic thermoelectric material and the inorganic thermoelectric material as described above, B. Zhang et al. Disclosed a paper in which a PEDOT: PSS polymer and a Bi ₂ Te ₃ thermoelectric material were combined in a thin film form. However, the complex of the polymer and the inorganic thermoelectric material has only a physical bond between the organic material and the inorganic material, so that it is difficult to change the electrical and thermal properties, and the thermoelectric performance index is as low as 0.1 or less.

Further, the thermoelectric material has the following problems in the form of a thin film.

)은 소재의 두께(l)에 반비례하므로 박막 형태의 경우 벌크 형태에 비해 열전발전에 필요한 온도차가 빠른 속도로 없어질 수 있다. Thin film thermoelectric materials can show low thermal conductivity when compared with bulk form,

) Is inversely proportional to the thickness (1) of the material, so that the temperature difference required for the thermoelectric power generation can be rapidly eliminated in the case of the thin film type as compared with the bulk type.

Therefore, the thin film type is difficult to apply to the field of thermoelectric power generation, and is suitable for the thermoelectric cooling field.

Accordingly, the present inventors have been studying organic-inorganic hybrid thermoelectric materials that can be applied to the field of thermoelectric power generation and have excellent thermoelectric performance indexes, and have found that bulk-type Bi ₂ Te ₃ and organic / inorganic hybrid thermoelectric materials And found out that the thermoelectric properties of the organic / inorganic hybrid thermoelectric material are excellent, and completed the present invention.

An object of the present invention is to provide an organic / inorganic hybrid thermoelectric material which can be applied to the field of thermoelectric power generation and has an excellent thermoelectric performance index.

In order to achieve the above object,

An organic / inorganic hybrid thermoelectric material including bulk type Bi ₂ Te ₃ and a polymer is provided.

In addition,

Preparing a polymer powder (step 1);

A step of producing Bi ₂ Te ₃ powder by gas phase reduction of Bi-Te hydrate (step 2);

(Step 3) of preparing the Bi ₂ Te ₃ / polymer mixture powder by mixing the polymer powder prepared in steps 1 and 2 and the Bi ₂ Te ₃ powder; And

And sintering the Bi ₂ Te ₃ / polymer mixture powder prepared in the step 3 (step 4); and a process for producing an organic / inorganic hybrid thermoelectric material containing a polymer and Bi ₂ Te _{3 in} bulk form .

In the bulk organic-inorganic hybrid thermoelectric material according to the present invention, the polymer and Bi ₂ Te ₃ are physically and chemically bonded to change the electrical and thermal properties of the material, ultimately improving the thermoelectric performance index. In addition, it is a bulk type organic / inorganic hybrid thermoelectric material and exhibits properties suitable for the field of thermoelectric power generation. In addition, the method for producing a bulk organic-inorganic hybrid thermoelectric material according to the present invention can produce a Bi ₂ Te ₃ powder through a gas phase reduction method, thereby lowering a sintering temperature for producing a final organic / inorganic hybrid thermoelectric material, .

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a process flow diagram of a method for producing an organic / inorganic hybrid thermoelectric material including Bi ₂ Te ₃ and a polymer according to the present invention;
2 is a schematic view showing an example of a method for producing an organic / inorganic hybrid thermoelectric material containing Bi ₂ Te ₃ and a polymer according to the present invention;
Figs. 3 to 5 are X-ray diffraction (XRD) results of the bulk organic-inorganic hybrid thermoelectric material prepared in Examples 1 to 6 and the Bi ₂ Te ₃ thermoelectric material of Comparative Example 1 according to the present invention;
6 is a photograph of a bulk organic-inorganic hybrid thermoelectric material prepared in Examples 1, 3 and 5 according to the present invention and a Bi ₂ Te ₃ thermoelectric material of Comparative Example 1 observed under an optical microscope;
7 is a graph showing resistivities of the organic-inorganic hybrid thermoelectric material in bulk form and the Bi ₂ Te ₃ thermoelectric material of Comparative Example 1 produced in Examples 1, 3 and 5 according to the present invention ;
8 is a graph showing the whiteness coefficients of the organic-inorganic hybrid thermoelectric material in the bulk form and the Bi ₂ Te ₃ thermoelectric material prepared in Example 1, Example 3 and Example 5 according to the present invention, ego;
9 is a graph showing the power factor of the organic / inorganic hybrid thermoelectric material in bulk form and the Bi ₂ Te ₃ thermoelectric material of Comparative Example 1 produced in Examples 1, 3 and 5 according to the present invention ;
10 is a graph showing the thermal conductivities of the organic-inorganic hybrid thermoelectric material in the bulk form and the Bi ₂ Te ₃ thermoelectric material of Comparative Example 1 produced in Examples 1, 3 and 5 according to the present invention ego;
11 shows the thermoelectric performance indexes of the organic / inorganic hybrid thermoelectric materials prepared in Examples 1, 3 and 5 according to the present invention and the thermoelectric properties of Bi ₂ Te ₃ thermoelectric materials of Comparative Example 1 Graph.

The present invention

An organic / inorganic hybrid thermoelectric material including bulk type Bi ₂ Te ₃ and a polymer is provided.

Hereinafter, the organic / inorganic hybrid thermoelectric material according to the present invention will be described in detail.

The organic / inorganic hybrid thermoelectric material according to the present invention is characterized by being in a bulk form. In terms of bulk characteristics, superior compatibility with conventional organic / inorganic hybrid thermoelectric materials in a thin film form can be provided.

)은 소재의 두께(l)에 반비례하므로 박막 형태의 경우 벌크 형태에 비해 열전발전에 필요한 온도차가 빠른 속도로 없어질 수 있다. 따라서 박막 형태의 경우, 열전발전 분야에는 적용하기 어려운 형태이다. 반면, 본 발명에 따른 벌크 형태의 유ㆍ무기 하이브리드 열전재료는 박막 형태에 비하여 두꺼운 두께로 인해 온도차를 안정적으로 유지할 수 있으므로 열전발전 분야에 더욱 적합한 특징이 있다. 또한, 본 발명에 따른 유ㆍ무기 하이브리드 열전재료는 더욱 우수한 열전성능지수를 나타낸다.
In addition, a conventional thin film thermoelectric material can show a low thermal conductivity when compared with a bulk form,

) Is inversely proportional to the thickness (1) of the material, so that the temperature difference required for the thermoelectric power generation can be rapidly eliminated in the case of the thin film type as compared with the bulk type. Therefore, in the case of the thin film type, it is difficult to apply to the field of thermoelectric power generation. On the other hand, the bulk organic-inorganic hybrid thermoelectric material according to the present invention is more suitable for the thermoelectric power generation because the temperature difference can be stably maintained due to the thick thickness compared to the thin film type. Further, the organic / inorganic hybrid thermoelectric material according to the present invention exhibits a further excellent thermoelectric performance index.

The organic / inorganic hybrid thermoelectric material according to the present invention preferably has a form in which chemical bonding and physical bonding coexist.

The organic / inorganic hybrid thermoelectric material according to the present invention is preferably a form in which chemical and physical bonding coexist unlike the conventional organic / inorganic hybrid thermoelectric material consisting only of physical bonding between an organic material and an inorganic material. Due to such chemical and physical bonding, the electrical and thermal properties of the material can be changed at the same time. Thus, the organic / inorganic hybrid thermoelectric material can have electrical properties superior to conventional organic / inorganic hybrid thermoelectric materials, and the thermal conductivity of the material can be reduced due to phonon scattering in the polymer, and ultimately the thermoelectric performance index do.

In addition, the organic-inorganic hybrid thermoelectric material is preferably a rhombohedral (rhombohedral) structure. By having a rhombohydral structure such as pure Bi ₂ Te ₃ , it can be structurally stable and exhibit excellent electrical conductivity in bulk phase implementation.

Furthermore, the density of the organic / inorganic hybrid thermoelectric material is preferably 10% to 30% lower than the density of the pure Bi ₂ Te ₃ thermoelectric material. If the density of the organic / inorganic hybrid thermoelectric material is as low as less than 10% of the density of the pure Bi ₂ Te ₃ thermoelectric material, the reduction rate of the thermal conductivity is small. When the density of the organic / inorganic hybrid thermoelectric material is more than 30% There is a falling problem. Due to the low density, the thermal conductivity of the organic / inorganic hybrid thermoelectric material according to the present invention is low.

In addition, referring to Experimental Example 3, the organic / inorganic hybrid thermoelectric material can exhibit the best thermoelectric performance index when used in a temperature range of 50 to 300 ° C.

In the organic / inorganic hybrid thermoelectric material according to the present invention, the polymer may be poly (3,4-ethylenedioxythiophene), polyaniline, polypyrrole, But are not limited to, conjugated polymers such as polyparaphenylene, polyphenylenevinylene, poly (3-hexylthiophene), and derivatives thereof .

As a specific example, the organic / inorganic hybrid thermoelectric material including polypyrrole as the polymer may exhibit the best thermoelectric performance index when it is used in a temperature range of 100 ° C to 170 ° C, and the polymer may contain polyaniline- In the case of an inorganic hybrid thermoelectric material, it can exhibit the best thermoelectric performance index when it is used in a temperature range of 130 ° C to 200 ° C. The hybrid thermoelectric material can exhibit the best thermoelectric performance index when used in a temperature range of 150 to 250 ° C.

In addition,

Preparing a polymer powder (step 1);

A step of producing Bi ₂ Te ₃ powder by gas phase reduction of Bi-Te hydrate (step 2);

(Step 3) of preparing the Bi ₂ Te ₃ / polymer mixture powder by mixing the polymer powder prepared in steps 1 and 2 and the Bi ₂ Te ₃ powder; And

And sintering the Bi ₂ Te ₃ / polymer mixture powder prepared in the step 3 (step 4); and a process for producing an organic / inorganic hybrid thermoelectric material containing a polymer and Bi ₂ Te _{3 in} bulk form .

Hereinafter, the method for manufacturing the organic / inorganic hybrid thermoelectric material according to the present invention will be described in detail for each step.

At this time, the flow of the process for producing the organic / inorganic hybrid thermoelectric material according to the present invention is schematically shown in the process flow chart of FIG. 1,

Hereinafter, the method for manufacturing the organic / inorganic hybrid thermoelectric material according to the present invention will be described in detail with reference to the flow chart of FIG.

First, in the method for producing an organic / inorganic hybrid thermoelectric material according to the present invention, step 1 is a step of preparing a polymer powder.

In the step 1, the polymer powder is prepared as the organic thermoelectric material of the organic / inorganic hybrid thermoelectric material.

Specifically, the polymer of step 1 may be selected from the group consisting of poly (3,4-ethylenedioxythiophene), polyaniline, polypyrrole, polyparaphenylene, poly But are not limited to, conjugated polymers such as poly (phenylenevinylene), poly (3-hexylthiophene) and derivatives thereof.

The preparation of the polymer powder in the step 1 is, as a concrete example,

The solvent of the solution in which the polymer is dispersed is evaporated to obtain a dried polymer, and then the polymer powder is pulverized to prepare a polymer powder.

At this time, it is preferable that the evaporation is carried out at a temperature of 50 ° C to 100 ° C for 2 hours to 5 hours with stirring. If the above evaporation is carried out at a temperature lower than 50 ° C, the dispersion solvent may not evaporate. If the temperature exceeds 100 ° C, the recovery of the polymer is lowered and water can not be used as a hot water solution.

Next, in the method for producing an organic / inorganic hybrid thermoelectric material according to the present invention, Step 2 is a step of producing Bi ₂ Te ₃ powder by reducing the Bi-Te hydrate by gas phase.

The step 2 is a Bi-Te by gas phase reduction hydrate comprising the steps of preparing a Bi ₂ Te ₃ powder, a gas phase through the reduction method to prepare a Bi ₂ Te ₃ powder because the final organic and inorganic hybrid thermal sintering temperature for the production of material Can be manufactured in a bulk form.

Conventionally, the liquid phase but using a reduction method mainly to prepare a Bi ₂ Te ₃ powder, in this case, but a problem with increasing the sintering temperature for the size is to large manufacturing an organic and inorganic hybrid thermoelectric material further the powder, in the present invention, Bi ₂ Te ₃ powder is produced by the gas phase reduction method, the size of the powder is reduced and the sintering temperature for producing the organic / inorganic hybrid thermoelectric material can be lowered later.

Specifically, the Bi-Te hydrate of the step 2 may be prepared by dissolving the Bi precursor and the Te precursor in an aqueous acid solution. The acid aqueous solution may be, but not limited to, hydrochloric acid, nitric acid, sulfuric acid, and aqua regia.

The gas phase reduction in step 2 is preferably carried out in a hydrogen atmosphere at a temperature of 350 ° C to 450 ° C for 5 hours to 10 hours. If the gas phase reduction of step 2 is carried out at a temperature of less than 350 ° C, Bi-Te hydrate may not be reduced, and if carried out at a temperature exceeding 450 ° C, The sintering temperature is high.

Next, in the method for producing an organic / inorganic hybrid thermoelectric material according to the present invention, the step 3 is a step of mixing the polymer powder prepared in the above step 1 and step 2 and the Bi ₂ Te ₃ powder to prepare a Bi ₂ Te ₃ / .

Specifically, the mixing of step 3 may be performed including milling, and the milling may be performed by a planetary mill process. Also, the planetary milling process may be performed for 7 to 12 hours. Polymer powders and Bi ₂ Te ₃ powder can be uniformly mixed by mixing, milling and milling through a planetary mill process.

The Bi ₂ Te ₃ / polymer blend powder of step 3 is preferably blended at a ratio of 1 wt% to 10 wt% with respect to the Bi ₂ Te ₃ powder. If the Bi ₂ Te ₃ / polymer blend powder of step 3 contains less than 1% by weight of the polymer powder relative to the Bi ₂ Te ₃ powder, the electrical conductivity is similar to that of pure Bi ₂ Te ₃ , However, if it contains more than 10% by weight, the effect of reducing the thermal conductivity can be obtained, but the density is low and the electrical conductivity is lowered and the machinability is deteriorated.

Next, in the method for producing an organic / inorganic hybrid thermoelectric material according to the present invention, Step 4 is a step of sintering the Bi ₂ Te ₃ / polymer mixture powder prepared in Step 3.

In step 4, the Bi ₂ Te ₃ / polymer blend powder prepared in step 3 is sintered to form an organic / inorganic hybrid thermoelectric material including Bi ₂ Te ₃ and a polymer.

Conventionally, there is a problem that it is difficult to produce a bulk type compound due to the high melting point of Bi ₂ Te ₃ produced by the liquid phase reduction method. In the present invention, the Bi ₂ Te ₃ powder is produced by the gas phase reduction method of step 2, thereby lowering the sintering temperature to produce a bulk organic / inorganic hybrid thermoelectric material.

Specifically, the sintering in step 4 is preferably performed by a discharge plasma method. By sintering by the discharge plasma method as described above, a bulk shape can be easily produced.

As a specific example, as shown in FIG. 2, the discharge plasma method may be carried out by charging a powder into a graphite mold to produce a cylindrical bulk-organic-inorganic hybrid thermoelectric material.

In addition, the sintering of step 4 is preferably performed at a temperature of 300 ° C to 400 ° C for 2 minutes to 5 minutes. If the sintering of step 4 is carried out at a temperature of less than 300 캜, the sintering density is low, resulting in poor machinability and low electrical conductivity. If the temperature is higher than 400 DEG C, the effect of decomposing the polymer and reducing the thermal conductivity can not be obtained.

)은 소재의 두께(l)에 반비례하므로 박막 형태의 경우 벌크 형태에 비해 열전발전에 필요한 온도차가 빠른 속도로 없어질 수 있다. 따라서 박막 형태의 경우, 열전발전 분야에는 적용하기 어렵고 열전냉각 분야에 적합한 구조이며, 본 발명에서 제시하는 벌크 형태의 유ㆍ무기 하이브리드 열전재료는 열전발전 분야에 용이하게 사용될 수 있다.As described above, in the method for producing an organic / inorganic hybrid thermoelectric material according to the present invention, a bulk organic / inorganic hybrid thermoelectric material (Bi ₂ Te ₃ - polymer) can be obtained through Bi ₂ Te ₃ which can be sintered at a low temperature As a manufacturing method, it provides superior compatibility with existing thin film type organic / inorganic composite thermoelectric materials due to its bulk shape characteristics. Thin film thermoelectric materials can show low thermal conductivity when compared with bulk thermoelectric materials,

) Is inversely proportional to the thickness (1) of the material, so that the temperature difference required for the thermoelectric power generation can be rapidly eliminated in the case of the thin film type as compared with the bulk type. Therefore, in the case of the thin film type, it is difficult to apply to the field of thermoelectric power generation and is suitable for the thermoelectric cooling field. The bulk organic-inorganic hybrid thermoelectric material proposed in the present invention can be easily used in the field of thermoelectric power generation.

In addition, the organic-inorganic hybrid thermoelectric material according to the present invention has a form in which chemical and physical bonds coexist unlike conventional organic / inorganic hybrid thermoelectric materials formed by physical bonding between an organic material and an inorganic material. Due to such chemical and physical bonding, the electrical and thermal properties of the material can be changed at the same time. Accordingly, the organic / inorganic hybrid thermoelectric material according to the present invention can have electrical properties superior to conventional organic / inorganic hybrid thermoelectric materials, and the thermal conductivity of the material can be reduced due to phonon scattering in the polymer, The figure of merit improves.

Hereinafter, examples and experimental examples of the present invention will be described in more detail.

However, the following Examples and Experimental Examples are merely illustrative of the present invention, and the present invention is not limited by the following Examples and Experimental Examples.

Example 1 Production of organic / inorganic hybrid thermoelectric material 1

Step 1: The dispersion solution in which poly (3,4-ethylenedioxythiophene) (PEDOT) is dispersed is evaporated through a hot water bath at 90 DEG C for 3 hours A polymer powder was prepared by obtaining a dried polymer product and pulverizing it.

Step 2: dissolving the Bi and Te in a nitric acid aqueous solution to form a Bi-Te hydrate and heated after drying at a temperature and a hydrogen atmosphere at 350 ℃ 6 hours to prepare a Bi ₂ Te ₃ powder.

Step 3: Bi ₂ Te ₃ / polymer (Bi ₂ Te ₃ / PEDOT) mixture powder was prepared by mixing the polymer (PEDOT) powder and Bi ₂ Te ₃ powder prepared in steps 1 and 2, ₂ < / RTI > Te ₃ powder.

Step 4: The Bi ₂ Te ₃ / polymer blend powder prepared in step 3 was sintered at 350 ° C. for 5 minutes by the discharge plasma method.

In the discharge plasma sintering process, powder was charged into a graphite mold to prepare a cylindrical bulk organic-inorganic hybrid thermoelectric material (Bi ₂ Te ₃ -PEDOT).

Example 2: Production of organic / inorganic hybrid thermoelectric material 2

Inorganic hybrid thermoelectric material (Bi ₂ Te ₃ - _{2) was prepared in the} same manner as in Example 1, except that the weight of the polymer powder was adjusted to 2.5% by weight of the Bi ₂ Te ₃ powder in the step 3 of Example 1, PEDOT).

≪ Example 3 > Production of organic / inorganic hybrid thermoelectric material 3

An organic / inorganic hybrid thermoelectric material (Bi ₂ Te ₃ -polyaniline) was prepared in the same manner as in Example 1 except that polyaniline was prepared as a polymer in step 1 of Example 1 and polyaniline powder was used .

Example 4: Production of organic / inorganic hybrid thermoelectric material 3

Inorganic hybrid thermoelectric material (Bi ₂ Te ₃ - _{2) was obtained in the} same manner as in Example 3, except that the weight of the polymer powder was adjusted to 2.5% by weight of the Bi ₂ Te ₃ powder in the step 3 of Example 3, polyaniline.

Example 5 Production of organic / inorganic hybrid thermoelectric material 5

An organic-inorganic hybrid thermoelectric material (Bi ₂ Te ₃ -polypyrrole) was prepared in the same manner as in Example 1 except that polypyrrole was prepared as a polymer in Step 1 of Example 1 and polypyrrole powder was used .

Example 6: Production of organic / inorganic hybrid thermoelectric material 6

Inorganic hybrid thermoelectric material (Bi ₂ Te ₃ - _{2) was prepared in the} same manner as in Example 5, except that the weight of the polymer powder was adjusted to 2.5% by weight of the Bi ₂ Te ₃ powder in the step 3 of Example 5, polypyrrole.

≪ Comparative Example 1 &

Step 1: prepare a Bi ₂ Te ₃ and Bi powder was dissolved by heating in Bi-Te form a hydrate and this temperature and hydrogen atmosphere at 350 ℃ dried for 6 hours to Te in an aqueous nitric acid solution.

Step 2: The Bi ₂ Te ₃ powder prepared in the step 2 was sintered at 350 ° C. for 5 minutes by a discharge plasma method.

In the discharge plasma sintering process, powder was charged into a graphite mold to prepare a cylindrical bulk type Bi ₂ Te ₃ thermoelectric material.

Experimental Example 1 X-ray diffraction analysis

In order to confirm the crystal structure of the organic / inorganic hybrid thermoelectric material according to the present invention, the bulk organic-inorganic hybrid thermoelectric materials (Bi ₂ Te ₃ -PEDOT, Bi ₂ Te ₃ -polyaniline , Bi ₂ Te ₃ -polypyrrole) and the Bi ₂ Te ₃ thermoelectric material of Comparative Example 1 were subjected to X-ray diffraction analysis (XRD, Rigaku, D / MAX-2500) .

As shown in FIGS. 3 to 5, it can be confirmed that the organic-inorganic hybrid thermoelectric materials according to the present invention have a rhombohedral structure such as pure Bi ₂ Te ₃ . Particularly, it can be observed that the main peak appearing at about 27.5 DEG moves depending on the amount of polymer injected. This means that some of the elements of the polymer chemically react with Bi ₂ Te ₃ , which can predict changes in the physical properties (electrical and thermal properties) of the material.

<Experimental Example 2> Observation under an optical microscope

In order to confirm the surface shape and density of the organic / inorganic hybrid thermoelectric material according to the present invention, the bulk organic / inorganic hybrid thermoelectric material (Bi ₂ Te ₃ - PEDOT, Bi ₂ Te ₃ -polyaniline, Bi ₂ Te ₃ -polypyrrole) and the Bi ₂ Te ₃ thermoelectric material of Comparative Example 1 were observed with an optical microscope (OM, Nikkon, Eclips 90i) and the density was measured by the Archimedes method. The results are shown in Fig. 6 and Table 1 below.

As shown in FIG. 6, the organic / inorganic hybrid thermoelectric materials according to the present invention were observed to have shapes expected to be polymers on the surface as compared with Comparative Example 1 which is a pure Bi ₂ Te ₃ thermoelectric material.

In addition, since the density of the three polymers used in organic / inorganic hybrid thermoelectric materials according to the present invention is about 1 g / cm ³ (about 1/7 of the density of Bi ₂ Te ₃ , see Table 1) As shown in Fig. 1, it was confirmed that the density of the organic-inorganic hybrid thermoelectric material into which the polymer was injected was smaller than that of the pure Bi ₂ Te ₃ thermoelectric material. It can be expected that the polymers can perform phonon scattering action in the organic / inorganic hybrid thermoelectric material and the thermal conductivity of the material is lowered because the density is lowered.

Comparative Example 1
(Bi ₂ Te ₃ ) Bi ₂ Te ₃ - Hybrid Thermoelectric Materials PEDOT (% by weight) Polyaniline (% by weight) Polypyrrole (% by weight) 2.5 5.0 2.5 5.0 2.5 5.0 density
(g / cm ³⁾ 7.719 6.362 5.783 6.647 6.143 6.550 6.466

&Lt; Experimental Example 3 > Measurement of thermoelectric property

In order to confirm the thermoelectric properties of the organic-inorganic hybrid thermoelectric material according to the present invention, the bulk organic-inorganic hybrid thermoelectric material (Bi ₂ Te ₃ -PEDOT, manufactured by the above-described Example 1, Example 3, Electrical properties measurement (Linseis, LSR-3) and laser flash analysis (LFA, Netzsch, LFA447) of Bi ₂ Te ₃ -polyaniline, Bi ₂ Te ₃ -polypyrrole and Comparative Example 1 Bi ₂ Te ₃ thermoelectric materials The results are shown in Figs. 7 to 10, and the thermoelectric performance index was calculated based on the results. The results are shown in Fig. 11 .

As shown in FIGS. 7 to 10, it was observed that the bulk organic-inorganic hybrid thermoelectric materials according to the present invention exhibited a change in electrical resistance, Seebeck coefficient, and thermal conductivity when compared with pure Bi ₂ Te ₃ . This can be attributed to the chemical and physical change of the thermoelectric material due to the polymer injection (the chemical reaction between Bi ₂ Te ₃ and the constituent elements of the polymer, the density reduction, and the phonon scattering effect of the polymer). The power factor (α ² / ρ), which reflects both the electrical resistance and the Seebeck coefficient, has been lowered to 30% to 50% of the pure Bi ₂ Te ₃ thermoelectric material due to polymer injection. However, It provides a higher value compared to.

It was confirmed that the thermal conductivity decreased to 50% to 60% of the pure Bi ₂ Te ₃ thermoelectric material. In the case of thermal conductivity, thermal conductivity is lower than 1.0 Wm ^-1 K ^-1 at a temperature of 50 ° C to 300 ° C. Particularly, an organic / inorganic hybrid thermoelectric material using polypyrrole and polyaniline has a thermal conductivity And showed a thermal conductivity of 0.75 Wm ^-1 K ^-1 at a temperature of 150 ° C.

As shown in FIG. 11, the thermoelectric performance index of the bulk organic-inorganic hybrid thermoelectric materials according to the present invention will be described. The bulk organic-inorganic hybrid thermoelectric materials have a thermal conductivity at a temperature of 50 to 300 DEG C, And the figure shows the thermoelectric performance index (figure of merit, ZT) of 0.8.

Particularly, the organic / inorganic hybrid thermoelectric material using polypyrrole exhibited a thermoelectric performance index of 0.7 or more at a temperature of 100 to 200 캜.

As described above, the organic-inorganic hybrid thermoelectric materials in the bulk form according to the present invention provide better thermoelectric performance index to organic / inorganic hybrid thermoelectric materials including Bi ₂ Te ₃ and polymers in the past, It can provide higher compatibility with the thin film type organic-inorganic hybrid thermoelectric material.

Claims (16)

An organic / inorganic hybrid thermoelectric material including bulk type Bi ₂ Te ₃ and a polymer.
The method according to claim 1,
Wherein the organic / inorganic hybrid thermoelectric material is a form in which chemical bonding and physical bonding coexist.
The method according to claim 1,
Wherein the organic / inorganic hybrid thermoelectric material has a rhombohedral structure. &Lt; RTI ID = 0.0 &gt; 11. &lt; / RTI &gt;
The method according to claim 1,
Wherein the density of the organic / inorganic hybrid thermoelectric material is 10% to 30% lower than the density of the pure Bi ₂ Te ₃ thermoelectric material.
The method according to claim 1,
Wherein the organic / inorganic hybrid thermoelectric material is used in a temperature range of 50 占 폚 to 300 占 폚.
The method according to claim 1,
The polymer may be selected from the group consisting of poly (3,4-ethylenedioxythiophene), polyaniline, polypyrrole, polyparaphenylene, polyphenylenevinylene Wherein the thermoelectric material is a conjugated polymer selected from the group consisting of poly (3-hexylthiophene), poly (3-hexylthiophene) and derivatives thereof.
Preparing a polymer powder (step 1);
A step of producing Bi ₂ Te ₃ powder by gas phase reduction of Bi-Te hydrate (step 2);
(Step 3) of preparing the Bi ₂ Te ₃ / polymer mixture powder by mixing the polymer powder prepared in steps 1 and 2 and the Bi ₂ Te ₃ powder; And
And sintering the Bi ₂ Te ₃ / polymer blend powder prepared in the step 3 (step 4), and a method for producing an organic / inorganic hybrid thermoelectric material including a bulk Bi ₂ Te ₃ and a polymer.
8. The method of claim 7,
The polymer of step 1 may be selected from the group consisting of poly (3,4-ethylenedioxythiophene), polyaniline, polypyrrole, polyparaphenylene, Inorganic hybrid thermoelectric material characterized in that it is a conjugated polymer selected from the group consisting of polyphenylenevinylene, poly (3-hexylthiophene), and derivatives thereof. &Lt; / RTI &gt;
8. The method of claim 7,
In preparation of the polymer powder in the step 1,
A process for producing an organic / inorganic hybrid thermoelectric material, which comprises drying a polymeric dry material by evaporating a solvent of a solution in which a polymer is dispersed, and pulverizing the polymeric dry powder to prepare a polymer powder.
10. The method of claim 9,
Wherein the evaporation is carried out at a temperature of 50 ° C to 100 ° C for 2 hours to 5 hours with hot water.
8. The method of claim 7,
Wherein the Bi-Te hydrate of step 2 is prepared by dissolving a Bi precursor and a Te precursor in an aqueous acid solution.
12. The method of claim 11,
Wherein the acid aqueous solution contains one kind of acid selected from the group consisting of hydrochloric acid, nitric acid, sulfuric acid and water.
8. The method of claim 7,
Wherein the gas phase reduction in step (2) is performed in a hydrogen atmosphere at a temperature of 350 ° C to 450 ° C for 5 hours to 10 hours.
8. The method of claim 7,
Wherein the Bi ₂ Te ₃ / polymer blend powder of step 3 is mixed at a ratio of 1 wt% to 10 wt% relative to the Bi ₂ Te ₃ powder of the polymer powder.
8. The method of claim 7,
Wherein the sintering of step 4 is performed by a discharge plasma method.
8. The method of claim 7,
Wherein the sintering of step 4 is performed at a temperature of 300 ° C to 400 ° C for 2 minutes to 5 minutes.

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