KR101614063B1 - New compound semiconductors and their application - Google Patents

Abstract

The present invention discloses a novel compound semiconductor which can be used for a thermoelectric material or the like and its application. The compound semiconductor according to the present invention can be represented by the following chemical formula (1).
≪ Formula 1 >
[Bi _{1 - x} M _x Cu _{1 - w} T _w O _{a - y} Se _{y b} Q1 _- Q2 _{z z]} [Cu ₂ Se _{+ c] d}
Wherein M is at least one selected from the group consisting of Ba, Sr, Ca, Mg, Cs, K, Na, Cd, Hg, Sn, Pb, Mn, Ga, In, Tl, As and Sb Wherein Q1 and Q2 are any one or two or more elements selected from the group consisting of S, Te, As, and Sb, T is any one or two or more elements selected from the transition metal elements, and 0 1, 0? W? 1, 0.2 <a <1.5, 0? Y <1.5, 0.2 <b <1.5, 0? Z <1.5, -1 <c <1, 0 <d.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel compound semiconductors,

The present invention relates to a novel compound semiconductor material which can be used for various applications such as a thermoelectric material and a solar cell, a method for producing the same, and a use thereof.

A compound semiconductor is a compound that is not a single element such as silicon or germanium but is operated as a semiconductor by combining two or more elements. Various kinds of compound semiconductors are currently being developed and used in various fields. Typically, a compound semiconductor can be used for a thermoelectric conversion element using a Peltier effect, a light emitting element such as a light emitting diode or a laser diode using a photoelectric conversion effect, and a solar cell.

First, solar cells are environmentally friendly in that they do not require a separate energy source in addition to sunlight existing in nature, and are being actively researched as a future alternative energy source. The solar cell is mainly composed of a silicon solar cell using a single element of silicon, a compound semiconductor solar cell using compound semiconductors, and a tandem solar cell in which two or more solar cells having different bandgap energies are stacked And the like.

Among them, a compound semiconductor solar cell uses a compound semiconductor for a light absorption layer which absorbs sunlight to generate an electron-hole pair. Particularly, III-V compound semiconductors such as GaAs, InP, GaAlAs and GaInAs, CdS, CdTe, II-VI compound semiconductors such as ZnS and the like, and I-III-VI compound semiconductors represented by CuInSe ₂ .

The photoabsorption layer of the solar cell is required to have excellent long-term electrical and optical stability, high photoelectric conversion efficiency, and easy control of the band gap energy or conduction type by a change in composition or doping. In addition, for commercialization, requirements such as manufacturing cost and yield must be satisfied. However, many conventional compound semiconductors fail to meet all of these requirements together.

The thermoelectric conversion element can be applied to thermoelectric conversion power generation, thermoelectric conversion cooling, and the like. In general, the N type thermoelectric semiconductor and the P type thermoelectric semiconductor are electrically connected in series and thermally connected in parallel. Among them, the thermoelectric conversion power generation is a type of power generation that converts thermal energy into electric energy by using the thermoelectric power generated by placing a temperature difference in the thermoelectric conversion element. The thermoelectric conversion cooling is a cooling type in which electric energy is converted into thermal energy by utilizing the effect that a temperature difference occurs at both ends when a direct current flows in both ends of the thermoelectric conversion element.

It can be said that the energy conversion efficiency of such a thermoelectric conversion element is generally dependent on ZT, which is a figure of merit of the thermoelectric conversion material. Here, ZT can be determined according to Seebeck coefficient, electric conductivity and thermal conductivity, and it can be said that the higher the ZT value, the better the thermoelectric conversion material.

Although a large number of thermoelectric conversion materials have been proposed so far, it can not be said that thermoelectric conversion materials having high thermoelectric conversion performance are sufficiently provided. In particular, recently, the field of application to thermoelectric conversion materials is gradually expanding, and temperature conditions may be different for each application field. However, since the thermoelectric conversion performance of the thermoelectric conversion material may vary depending on the temperature, the thermoelectric conversion performance of each thermoelectric conversion material needs to be optimized in the field to which the thermoelectric conversion material is applied. However, it can not be said that thermoelectric conversion materials having optimized performance over a wide and wide temperature range are properly prepared yet.

Accordingly, the present invention has been made to solve the above problems, and it is an object of the present invention to provide a compound semiconductor material which can be utilized for various purposes such as a thermoelectric conversion material of a thermoelectric conversion element and a solar cell, And a thermoelectric conversion element or a solar cell using the same.

Other objects and advantages of the present invention will become apparent from the following description, and it will be understood by those skilled in the art that the present invention is not limited thereto. It will also be readily apparent that the objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

In order to achieve the above object, the present inventor has succeeded in synthesizing a compound semiconductor represented by the following Chemical Formula 1 after repeated researches on compound semiconductors, and has succeeded in synthesizing the compound semiconductor in a thermoelectric conversion material of a thermoelectric conversion element, And thus the present invention has been completed.

&Lt; Formula 1 >

[Bi _{1 - x} M _x Cu _{1 - w} T _w O _{a - y} Se _{y b} Q1 _- Q2 _{z z]} [Cu ₂ Se _{+ c] d}

Wherein M is at least one selected from the group consisting of Ba, Sr, Ca, Mg, Cs, K, Na, Cd, Hg, Sn, Pb, Mn, Ga, In, Tl, As and Sb Wherein Q1 and Q2 are any one or two or more elements selected from the group consisting of S, Te, As, and Sb, T is any one or two or more elements selected from the transition metal elements, and 0 1, 0? W? 1, 0.2 <a <1.5, 0? Y <1.5, 0.2 <b <1.5, 0? Z <1.5, -1 <c <1, 0 <d.

Preferably, 0? X <0.2, 0 <w? 0.05, 0.9 <a <1.1, 0.9 <y <1.1, -0.5 <c <0.5.

Also preferably, in Formula 1 M, Q1, type of Q2 and x, w, a, y, b, z, c value is, at the same temperature _{Bi 1 - x M x Cu 1} - w T w O a _{- y} Q 1 _y Se _{b - z} Q 2 _z , and the error of the Seebeck coefficient of the compound represented by Cu _{2 + c} Se is controlled to be 0 uV / K to 170 uV / K.

Also preferably, y and z in Formula 1 are y = 0 and z = 0, respectively.

Further, preferably, the above formula (1) is represented by [Bi _{1 - x} M _x CuOSe] [Cu ₂ Se] _d .

Also preferably, M in the above formula (1) includes Pb.

Also preferably, the average crystal grain size is 50 nm to 50 mu m.

Also preferably, a heterointerface is formed on the interface of the grain.

According to another aspect of the present invention, there is provided a method for fabricating a compound semiconductor, comprising the steps of: preparing Bi ₂ O ₃ , Bi, Se, and Cu powders; One or two or more of these elements, or a powder of the oxide, and optionally further mixing powder selected from any one selected from transition metal elements or two or more elements or oxides thereof, A powder composed of any one or two or more elements selected from the group consisting of Ca, Mg, Cs, K, Na, Cd, Hg, Sn, Pb, Mn, Ga, In, To form a mixture; And pressing and sintering the mixture.

Also preferably, the method further includes a step of heat-treating the mixture before the pressure sintering step.

More preferably, the heat treatment step of the mixture is carried out by a solid phase reaction method.

Also preferably, the pressure sintering step is carried out by a pressure sintering method.

In addition, compound semiconductor manufacturing method according to another aspect of the present invention for achieving the above object is, in the general formula _{1 [Bi 1 - x M x} Cu 1 - w T w O a - y Q1 y Se b - z Q2 _z ]; mixing and heat-treating the powders to synthesize [Cu _{2 + c} Se]; And group the combined mixture of _{[Bi 1 - x M x Cu} 1 - w T w O a - - y Q1 y Se b z Q2 z] and [Cu _{2 + c} Se] powder, and a step of sintering.

Further _{preferably, [Bi 1 - x M x} Cu 1 - w T w O a - y Q1 y Se b - z Q2 z] and [Cu _{2 + c} Se] mixing step the powder is performed by a ball mill do.

According to another aspect of the present invention, there is provided a thermoelectric conversion device including the above-described compound semiconductor.

In order to achieve the above object, a solar cell according to the present invention includes the above-described compound semiconductor.

In order to achieve the above object, a bulk-type thermoelectric material according to the present invention includes the above-described compound semiconductor.

According to the present invention, a compound semiconductor material which can be used for a thermoelectric conversion element, a solar cell, or the like is provided.

In particular, the compound semiconductor according to the present invention can be used as another material in place of the conventional compound semiconductors or in addition to the conventional compound semiconductors.

Further, according to one aspect of the present invention, a compound semiconductor can be used as a thermoelectric conversion material of a thermoelectric conversion element. In this case, a high ZT value is ensured, and a thermoelectric conversion element having excellent thermoelectric conversion performance can be manufactured. Further, according to the present invention, a thermoelectric conversion material excellent in thermoelectric conversion performance over a wide temperature range can be provided.

In particular, the compound semiconductor according to the present invention can be used as a P-type thermoelectric conversion material.

According to another aspect of the present invention, a compound semiconductor can be used for a solar cell. In particular, the compound semiconductor according to the present invention can be used as a light absorbing layer of a solar cell.

In addition, according to another aspect of the present invention, a compound semiconductor may be used for an IR window, an infrared sensor, a magnetic device, a memory, etc., which selectively pass infrared rays.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate preferred embodiments of the invention and, together with the description of the invention given below, serve to further the understanding of the technical idea of the invention, And should not be construed as limiting.
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a schematic view showing a configuration in which a hetero interface is formed in a compound semiconductor according to an embodiment of the present invention. FIG.
2 is a flow chart schematically showing a method of manufacturing a compound semiconductor according to one aspect of the present invention.
3 is a flow chart schematically showing a method of manufacturing a compound semiconductor according to another aspect of the present invention.
4 is a graph showing the ZT values of the compound semiconductors according to the present invention and the comparative example according to the temperature change.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms, and the inventor should appropriately interpret the concepts of the terms appropriately It should be construed in accordance with the meaning and concept consistent with the technical idea of the present invention based on the principle that it can be defined.

Therefore, the embodiments described in the present specification and the configurations shown in the drawings are only the most preferred embodiments of the present invention and do not represent all the technical ideas of the present invention. Therefore, It is to be understood that equivalents and modifications are possible.

The present invention provides a novel compound semiconductor represented by the following formula (1).

&Lt; Formula 1 >

[Bi _{1 - x} M _x Cu _{1 - w} T _w O _{a - y} Se _{y b} Q1 _- Q2 _{z z]} [Cu ₂ Se _{+ c] d}

Wherein M is at least one selected from the group consisting of Ba, Sr, Ca, Mg, Cs, K, Na, Cd, Hg, Sn, Pb, Mn, Ga, In, Tl, As and Sb Wherein Q1 and Q2 are any one or two or more elements selected from the group consisting of S, Te, As, and Sb, T is any one or two or more elements selected from the transition metal elements, and 0 1, 0? W? 1, 0.2 <a <1.5, 0? Y <1.5, 0.2 <b <1.5, 0? Z <1.5, -1 <c <1, 0 <d.

Here, T is _{Bi 1 - x M x Cu 1} - w T w O a - y Q1 y Se b - in _z Q2 _z as a transition metal element for substituting a part of Cu sites, Co, Ag, Zn, Ni , Fe , Cr, or two or more of these elements. In this way, due to the structure in which a part of the Cu site is substituted with a transition metal element such as Co or Ag, the compound semiconductor according to the present invention can further improve the thermoelectric conversion performance. In particular, when the energy level of the d orbitals of the partially substituted transition metals is located within a few eV of the Fermi level, the density of state and entropy around the Fermi level increase, Can be increased. At this time, the energy level of the d orbitals of the transition metal is closer to the Fermi level, and the degree of increase of the Seebeck coefficient is improved. The carrier concentration of the compound semiconductor can be controlled by selecting the species of the substituted transition metal. Further, the substitution element improves the degree of scattering of the phonon as a point defect and can lower the thermal conductivity of the compound semiconductor.

Preferably, x in the above formula (1) is 0? X <0.2.

Also preferably, w in formula (1) is 0 < w? 0.05.

Preferably, a in the above formula (1) is 0.9 < a < 1.1.

Also preferably, in the above formula (1), y is 0.9 < y < 1.1.

Also, preferably, in the above formula (1), c is -0.5 < c < 0.5.

Particularly, the compound semiconductor according to the present invention can be configured in the form of containing different kinds of compound semiconductors. For _{example, [Bi 1 - x M x} Cu 1 - w T w O a - y Q1 y Se b - z Q2 z] a compound represented by the semiconductor material and the [Cu _{2 + c} Se] a compound represented by the with a semiconductor material, Can be included to constitute the compound semiconductor material according to the present invention.

Preferably, the compound semiconductor according to the present invention may be formed in a form in which a heterointerface is formed. That is, the compound semiconductor according to the present invention, [Bi _{1 - x} M _x Cu _{1 - w} T _w O _{a - y} Se _{y b} Q1 _- Q2 _{z z]} Grain (grain) and [Cu ₂₊ in the material expressed by _c Se] may be included, and heterogeneous interfaces may be formed at the boundaries of these different grains.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a schematic view showing a configuration in which a hetero interface is formed in a compound semiconductor according to an embodiment of the present invention. FIG.

1, a compound semiconductor according to the present invention includes a material represented by [Bi _{1 - x} M _x Cu _{1 -w} T _w O _ay Q 1 _y Se _bz Q 2 _z ] and a material represented by [Cu _{2 + c} Se] , And this kind of interface can effectively scatter phonons. In addition, in the compound semiconductor according to the present invention, a compound semiconductor material represented by Bi _{1 - x} M _x Cu _{1 - w} T _w O _{a - y} Q 1 _y Se _{b - z} Q 2 _z and Cu _{2 + c} Se Since the compound semiconductor materials have similar band gaps and hole carrier concentrations to each other, the hole carriers can pass well between the hetero interfaces. Therefore, the compound semiconductors according to the present invention are easy to have properties of high electrical conductivity and low thermal conductivity. Consequently, as a result, the thermoelectric conversion performance of the compound semiconductor according to the present invention can be effectively improved.

In addition, a compound semiconductor according to the present _{invention, Bi 1 - x M x Cu} 1 - w T w O a - y Q1 y Se b - a compound represented by the compound semiconductor material and a Cu _{2 + c} Se represented by _z Q2 _z Since the semiconductor material is included, the thermoelectric conversion performance can be optimized over a wider temperature range. For example, a Bi _1-x M _x CuOSe-based material has a high ZT value at around 500 ° C and a Cu ₂ Se-based material has a high ZT value at around 600 ° C. In the case of the compound semiconductor according to the present invention, Lt; RTI ID = 0.0 &gt; C, &lt; / RTI &gt;

Preferably, in the compound semiconductor according to the present invention, the sum of the Seebeck coefficient of the compound semiconductor material represented by the formula [Bi _{1 - x} M _x Cu _{1 - w} T _w O _ay Q 1 _y Se _bz Q 2 _z ] _{2 + c} Se] of the compound semiconducting material has a similar value at the same temperature. When compound semiconductors having a large difference in the Seebeck coefficient are mixed, the Seebeck coefficient of the mixture becomes similar to that of the compound semiconductor having a smaller Seebeck coefficient. This condition can be satisfied by controlling the types of M, Q1 and Q2 and the values of x, w, a, y, b, z and c in the above formula (1). In particular, the compound semiconductor according to the present invention, at the same temperature _{Bi 1 - x M x Cu 1} - w T w O a - y Q1 y Se b - z Q2 of the compound represented by the formula of _z Seebeck coefficient and Cu _{2 +} the error of the Seebeck coefficient of the compound represented by _c Se 0 uV / K to 170 such that the uV / K may be a M, Q1, and the type and x, w, a, y, b, z and c values of Q2 to be determined.

Preferably, the compound semiconductor according to the present invention has an average crystal grain size of 50 nm to 50 mu m for each grain included. According to this embodiment, the effect of reducing the phonon by the heterointerface can be further improved.

Preferably, in Formula 1, y and z may be y = 0 and z = 0, respectively. In this case, the formula (1) can be represented by the following formula.

[Bi _{1 - x} M _x Cu _{1 - w} T _w O _a Se _b ] [Cu _{2 + c} Se] _d

Preferably, w = 0, a = 1, b = 1, and c = 0 in the formula (1). In this case, the formula (1) can be represented by the following formula.

[Bi _{1 - x} M _x CuOSe] [Cu ₂ Se] _d

Also, preferably, M in Formula 1 may include Pb. In this case, the formula (1) can be represented by the following formula.

[Bi _{1 - x} Pb _x CuOSe] [Cu ₂ Se] _d

2 is a flow chart schematically showing a method of manufacturing a compound semiconductor according to one aspect of the present invention.

Referring to FIG. 2, a method of manufacturing a compound semiconductor according to the present invention includes a step S110 of forming a mixture by mixing raw materials constituting the formula 1, and a step S130 of pressing and sintering the mixture .

Here, the S110 step is, as a raw material constituting the above formula 1, Bi ₂ O _3, Bi, Se, and two of either or both selected from each powder, the group consisting of Te, S, As and Sb in Cu A powder of an element or an oxide of at least two species can be mixed.

Preferably, the step S110 may alternatively be performed by further mixing powder selected from any one of the transition metal elements or two or more of the elements or oxides thereof to form a mixture.

Here, the transition metal element to be mixed in step S110 may include Co, Ag, Zn, Ni, Fe, and Cr.

In addition, the step of S110 may be any one selected from the group consisting of Ba, Sr, Ca, Mg, Cs, K, Na, Cd, Hg, Sn, Pb, Mn, Ga, In, Powders of two or more of these elements or oxides thereof may be further mixed to form a mixture.

Preferably, the step S130 is performed by a spark plasma sintering (SPS) method or a hot press (HP) method. In the case of the compound semiconductors according to the present invention, when sintered by this pressure sintering method, high sintered density and corresponding electrical conductivity are easily obtained.

The pressure sintering step (S130) may be performed under a pressure condition of 30 MPa to 200 MPa. Further, the pressure sintering step (S130) may be performed under a temperature condition of 400 ° C to 650 ° C.

Also preferably, the method for producing a compound semiconductor according to the present invention may further include a step (S120) of heat-treating the mixture before press-sintering the mixture as shown in Fig. This heat treatment step (S120) can facilitate the reaction between the elements contained in the mixture. In this case, the heat treatment step (S120) may be performed at a temperature ranging from 400 ° C to 650 ° C for 1 hour to 24 hours.

Here, the heat treatment step (S120) may be performed by a solid state reaction (SSR) method. Even if the thermoelectric material having the same composition is used, the thermoelectric performance may be different depending on the heat treatment method. In the case of the compound semiconductor according to the present invention, when each raw material is reacted by the SSR method rather than another method, The thermoelectric performance of the produced compound semiconductor can be further improved.

In the case of compound semiconductors, there may be differences in the thermoelectric performance depending on the manufacturing method. The compound semiconductors according to the present invention are preferably manufactured by the above-described compound semiconductor manufacturing method. In this case, a high ZT value can be secured for the compound semiconductor, and in particular, it can be advantageous to secure a high ZT value in the temperature range of 100 ° C to 600 ° C.

However, the present invention is not necessarily limited to such a production method, and the compound semiconductor of Formula 1 may be produced by another manufacturing method.

3 is a flow chart schematically showing a method of manufacturing a compound semiconductor according to another aspect of the present invention.

3, a method for manufacturing a compound semiconductor according to the present invention, in Formula _{1 Bi 1 - x M x Cu} 1 - w T w O a - y Q1 y Se b - z Q2 z and Cu _{2 + c} Se is synthesized (S210). The synthesized Bi _{1 - x} M _x Cu _{1 - w} T _w O _{a - y} Q 1 _y Se _{b - z} Q _{2 z} and Cu _{2 + c} Se are mixed to form a mixture (S220) and sintering the mixture (S230).

Here, the step S210, ₁ Bi _{- x} M _x Cu _{1 - w} T _{w ay} Q1 O _y Se _{b -} For synthesizing the _{z Q2 z Bi 1 -x M x} Cu 1-w T w O ay Q1 _y Se _bz Q2 mixing each powder of the raw materials constituting the _z and synthesizing the phase and Cu _{2 + c} Se to heat treatment in order to include the step of mixing each powder of the raw materials constituting the Cu _{2 + c} Se and heat treatment have.

Preferably, the step S220 further comprises a step of mixing the Bi _{1 - x} M _x Cu _{1 - w} T _w O _{a - y} Q 1 _y Se _{b - z} Q 2 _z composite in powder form with the Cu _{2 + c} Se composite in powder form .

At this time, the step S220 may be performed by ball milling.

Also, preferably, the step S230 may be performed by a spark plasma sintering (SPS) method or a hot press (HP) method.

The thermoelectric conversion element according to the present invention may include the above-described compound semiconductor. That is, the compound semiconductor according to the present invention can be used as a thermoelectric conversion material of a thermoelectric conversion element. In particular, the thermoelectric conversion element according to the present invention can include the above-described compound semiconductor as a P-type thermoelectric material.

The compound semiconductor according to the present invention has a large value of ZT, which is a figure of merit of the thermoelectric conversion material. In addition, it has excellent heat transfer properties because of high Seebeck coefficient and electrical conductivity and low thermal conductivity. Therefore, the compound semiconductor according to the present invention can be usefully used for a thermoelectric conversion element in addition to a conventional thermoelectric conversion material or in addition to a conventional compound semiconductor.

Further, the compound semiconductor according to the present invention can be applied to a bulk thermoelectric conversion material. That is, the bulk thermoelectric material according to the present invention includes the compound semiconductors described above.

Further, the solar cell according to the present invention may include the above-described compound semiconductor. That is, the compound semiconductor according to the present invention can be used as a light absorbing layer of a solar cell, particularly a solar cell.

The solar cell can be manufactured in a structure in which a front transparent electrode, a buffer layer, a light absorbing layer, a back electrode, and a substrate are laminated sequentially from the side from which sunlight is incident. The substrate positioned at the lowest position may be made of glass, and the back electrode formed over the entire surface may be formed by depositing a metal such as Mo.

Then, the light absorbing layer can be formed by laminating the compound semiconductor according to the present invention on the back electrode by an electron beam evaporation method, a sol-gel method, or a PLD (Pulsed Laser Deposition) method. In the upper part of the light absorption layer, there may be a buffer layer which buffer the difference in lattice constant and the bandgap difference between the ZnO layer and the light absorption layer used as the front transparent electrode. Such a buffer layer may be formed by using a material such as CdS, For example, as shown in Fig. Next, a front transparent electrode may be formed by a method such as sputtering using a laminated film of ZnO, ZnO, and ITO on the buffer layer.

The solar cell according to the present invention can be variously modified. For example, a laminated solar cell in which solar cells using the compound semiconductor according to the present invention as a light absorbing layer are laminated can be produced. Other solar cells stacked in this manner can use silicon or other known compound semiconductor solar cells.

Further, by changing the band gap of the compound semiconductor of the present invention, a plurality of solar cells using compound semiconductors having different band gaps as the light absorbing layer may be laminated. The bandgap of the compound semiconductor according to the present invention can be controlled by changing the constituent elements of the compound, such as the composition ratio of Te.

Also, the compound semiconductor according to the present invention can be applied to an infrared window (IR window) or an infrared ray sensor for selectively passing infrared rays.

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. It should be understood, however, that the embodiments of the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. The embodiments of the present invention are provided to enable those skilled in the art to more fully understand the present invention.

Comparative Example  One

For the synthesis of Bi _{0 .95} Pb _{0 .05} CuOSe, 2.589 g of Bi ₂ O ₃ (Aldrich, 99.9%, 10 μm), 0.987 g of Bi (5N +, 99.999%, shot), Pb (Alfa Aesar, 99.9% ), 1.059 g of Cu (Aldrich, 99.7%, 3 m) and 1.316 g of Se (5N +, 99.999%, shot) were mixed well using an agate mortar. The mixed material was placed in a silica tube, vacuum-sealed, and heated at 600 ° C for 12 hours to obtain Bi _{0 .95} Pb _{0 .05} CuOSe powder.

Comparative Example  2

Cu ₂ Se powder was obtained in the same manner as in Comparative Example 1 using 1.271 g of Cu (Aldrich, 99.7%, 3 μm) and 0.790 g of Se (5N +, 99.999%, shot)

Example 1

In the same manner as in Comparative Examples 1 and 2 Bi _{0 .95} Pb _{0 .05} CuOSe and Cu ₂ Se were synthesized. Then, Bi _0.95 Pb _0.05 CuOSe powder and Cu ₂ Se powder were weighed according to the composition of [Bi _{0 .95} Pb _{0 .05} CuOSe] [Cu ₂ Se] _1.38 (d = 1.38) and the wet ZrO ₂ ball The mixture of Example 1 was prepared by milling and mixing using milling.

Example 2

In the same manner as in Comparative Examples 1 and 2 Bi _0.95 Pb _0.05 CuOSe and Cu ₂ Se were synthesized. Then, Bi _0.95 Pb _0.05 CuOSe powder and Cu ₂ Se powder were weighed according to the composition of [Bi _0.95 Pb _0.05 CuOSe] [Cu ₂ Se] _1.78 (d = 1.78) and pulverized and pulverized using an alumina mortar bowl for 10 minutes. The mixture of Example 2 was prepared by mixing.

Example 3

In the same manner as in Comparative Examples 1 and 2 Bi _0.95 Pb _0.05 CuOSe and Cu ₂ Se were synthesized. Then, Bi _0.95 Pb _0.05 CuOSe powder and Cu ₂ Se powder were weighed according to the composition of [Bi _0.95 Pb _0.05 CuOSe] [Cu ₂ Se] _3.21 (d = 3.21) and pulverized and pulverized using an alumina mortar bowl for 10 minutes. The mixture of Example 3 was prepared by mixing.

Example 4

In the same manner as in Comparative Examples 1 and 2 Bi _0.95 Pb _0.05 CuOSe and Cu ₂ Se were synthesized. Then, Bi _0.95 Pb _0.05 CuOSe powder and Cu ₂ Se powder were weighed according to the composition of [Bi _0.95 Pb _0.05 CuOSe] [Cu ₂ Se] _12.37 (d = 12.37) and pulverized and pulverized using an alumina mortar bowl for 10 minutes. The mixture of Example 4 was prepared by mixing.

Some of the samples of Comparative Examples 1 and 2 and Examples 1 to 4 synthesized by the above-mentioned method were charged into graphite molds each having a diameter of 12 mm and sintered under the conditions of 50 MPa, 600 ° C, and 5 minutes using SPS.

Electrical Conductivity and Seebeck coefficient were measured at predetermined temperature intervals using ZEM-3 (Ulvac-Rico, Inc.) for each of the samples sintered in this way to determine a power factor Factor (PF) was calculated and the thermal conductivity of each sample was measured using LFA457 (Netch). Then, the thermoelectric performance index ZT value of each sample was confirmed through the obtained measurement values.

Here, the electrical conductivity, the Seebeck coefficient, the thermal conductivity and the ZT value determined from the electrical conductivity, the Seebeck coefficient and the thermal conductivity measured for the samples of Comparative Example 1, Comparative Example 2 and Examples 1 to 4 are shown in Tables 1 to 6. That is, Tables 1 and 2 show measurement and confirmation results of Comparative Example 1 and Comparative Example 2, respectively, and Tables 3 to 6 show measurement and confirmation results of Examples 1 to 4.

On the other hand, the ZT value measurement results of Comparative Example 1, Comparative Example 2 and Examples 1 to 4 shown in Tables 1 to 6 are shown in FIG. 4 for convenience of comparison.

Referring to the results of Tables 1 to 6 and FIG. 4, the electrical conductivity of the compound semiconductors of Examples 1 to 4 shown in Tables 3 to 6 was significantly improved as compared with Bi _0.95 Pb _0.05 CuOSe of Comparative Example 1 shown in Table 1 And the thermal conductivity is almost the same. It can be seen that the ZT value of the compound semiconductor according to the embodiment of the present invention is greatly improved in a predetermined temperature range. In particular, FIG. 4 comparing the ZT values shows that the ZT value of the compound semiconductor according to the embodiment of the present invention is significantly improved in comparison with the ZT value of the compound semiconductor of Comparative Example 1 in the temperature range of 450 ° C or higher.

Compared with the Cu ₂ Se of Comparative Example 2 shown in Table 2, the thermal conductivity of the compound semiconductors of Examples 1 to 4 was remarkably lowered and the ZT value was also improved. In particular, FIG. 4 comparing the ZT values shows that the ZT values of the compound semiconductors according to Examples 1 to 4 of the present invention over the entire temperature measurement period are remarkably improved as compared with the compound semiconductors of Comparative Example 2 .

Therefore, from the above results, it can be seen that the thermoelectric conversion performance of the compound semiconductors according to the present invention is superior or at least similar in many aspects to the conventional compound semiconductors.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. It will be understood that various modifications and changes may be made without departing from the scope of the appended claims.

Claims (19)

1. A compound semiconductor represented by the following formula (1).
&Lt; Formula 1 >
[Bi _{1 - x} M _x Cu _{1 - w} T _w O _{a - y} Se _{y b} Q1 _- Q2 _{z z]} [Cu ₂ Se _{+ c] d}
Wherein M is at least one selected from the group consisting of Ba, Sr, Ca, Mg, Cs, K, Na, Cd, Hg, Sn, Pb, Mn, Ga, In, Tl, As and Sb Wherein Q1 and Q2 are any one or two or more elements selected from the group consisting of S, Te, As, and Sb, T is any one or two or more elements selected from the transition metal elements, and 0 1, 0? W? 1, 0.2 <a <1.5, 0? Y <1.5, 0.2 <b <1.5, 0? Z <1.5, -1 <c <1, 0 <d. The method according to claim 1,
Wherein x, w, a, y and c in the formula (1) are 0? X <0.2, 0 <w? 0.05, 0.9 <a <1.1, 0.9 <y <1.1 and -0.5 <c <0.5 Compound semiconductor. The method according to claim 1,
The Seebeck coefficient of the compound represented by _z Q2 _z of the Seebeck coefficient and the Cu _{2 + c} Se of the compound represented by the formula _{- x M x Cu 1 - -} w T w O a - y Q1 y Se b Bi 1 at the same temperature And the values of x, w, a, y, b, z and c of the M, Q1 and Q2 are controlled such that the error is from 0 uV / K to 170 uV / K. The method according to claim 1,
Y, w and z in the above formula (1) are y = 0, w = 0 and z = 0, respectively. The method according to claim 1,
(1) is represented by [Bi _{1 - x} M _x CuOSe] [Cu ₂ Se] _d . The method according to claim 1,
Wherein M in the formula (1) includes Pb. The method according to claim 1,
Wherein the average crystal grain size is 50 nm to 50 mu m. The method according to claim 1,
Wherein a heterointerface is formed. Bi ₂ O ₃ , Bi, Se, and Cu and powders composed of any one or two or more elements selected from the group consisting of Te, S, As, and Sb or oxides thereof, A powder selected from the group consisting of Ba, Sr, Ca, Mg, Cs, K, Na, Cd, Hg, Sn, Pb, Mn and Ga , In, Tl, As and Sb, or a powder of two or more elements or oxides thereof, to form a mixture; And
Pressing and sintering the mixture
The method of manufacturing a compound semiconductor according to claim 1, 10. The method of claim 9,
Further comprising a step of heat-treating the mixture before the pressure sintering step. 11. The method of claim 10,
Wherein the heat treatment step of the mixture is carried out by a solid phase reaction method. 10. The method of claim 9,
Wherein the pressure sintering step is performed by a discharge plasma sintering method or a hot press method. Bi _{1 - x} M _x Cu _{1 - w} T _w O _{a - y} Q 1 _y Se _{b - z} Q _{2 z} and Cu _{2 + c} Se;
Mixing to form a mixture _{z z} Q2 and Cu ₂ Se _{+ c} the combined _{Bi 1 - x M x Cu 1} - w T w O a - - y Q1 y Se b; And
Sintering the mixture
The method of manufacturing a compound semiconductor according to claim 1, 14. The method of claim 13,
Wherein said mixing step comprises mixing a powdered Bi _{1 - x} M _x Cu _{1 - w} T _w O _{a - y} Q 1 _y Se _{b - z} Q 2 _z with powdered Cu _{2 + c} Se, A method of manufacturing a semiconductor. 15. The method of claim 14,
Wherein the mixture forming step is performed by ball milling. A thermoelectric conversion element comprising the compound semiconductor according to any one of claims 1 to 8. A thermoelectric conversion element comprising a compound semiconductor according to any one of claims 1 to 8 as a P-type thermoelectric conversion material. 9. A solar cell comprising the compound semiconductor according to any one of claims 1 to 8. A bulk thermoelectric material comprising the compound semiconductor according to any one of claims 1 to 8.

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