Thermoelectric material and thermoelectric module including the same

Abstract

The present disclosure relates to a thermoelectric material. The thermoelectric material includes: a lower portion from the bottom surface of the thermoelectric material to a position of 30% of the average thickness of the thermoelectric material and having an average carbon atom content of 40 at% or more of the thermoelectric material; and an upper portion corresponding to the remaining 70% of the average thickness of the thermoelectric material and having an average carbon atom content of 20 at% or less of the thermoelectric material.

Description

[0001] Cross - reference to related applications

[0002] This application claims priority to Korean Patent Application No. 10 - 2019 - 0161991, filed with the Korean Intellectual Property Office on December 6, 2019, which is incorporated herein by reference. Technical field

[0003] The present disclosure relates to a thermoelectric material and a thermoelectric module including the thermoelectric material. Background art

[0004] A thermoelectric module utilizes the Seebeck effect that generates thermoelectric power through a temperature difference between its opposite sides. Generally, a conventional thermoelectric module is made by thermo - forming or pressure - forming thermoelectric semiconductor particles on a bulk substrate. Therefore, it is difficult to apply to a curved substrate. Since it is difficult to change the shape after being fixed once, after the thermoelectric material is made, it is attached to a separate flexible substrate to form a horizontal - structured thermoelectric module shape suitable for a thin - film structure and applied.

[0005] Specifically, when a thermoelectric material is formed by sintering through heat treatment at a high temperature (above 350 °C) and / or high pressure, the flexible substrate is easily deformed by heat during sintering, so there is a problem that integrity cannot be ensured.

[0006] Therefore, there are laser sintering, electromagnetic sintering, and plasma sintering that can sinter even at low temperatures. Laser sintering is not suitable for mass production, electromagnetic sintering is difficult to perform selective sintering and it is difficult to manufacture a dense thin film with high electrical conductivity due to the reflection of electromagnetic waves, and plasma sintering is difficult to maintain a high - energy plasma and the processing efficiency of expensive equipment is low.

[0007] Therefore, research and development of thermoelectric materials that can be directly applied to a flexible substrate to prevent thermal deformation of the substrate and research on thermoelectric materials with excellent adhesion to the substrate and thermoelectric performance are underway. Summary of the invention

[0008] The present disclosure is proposed to solve the problems that occur in the prior art while perfectly maintaining the advantages achieved by the prior art.

[0009] Embodiments of the present disclosure provide a thermoelectric material manufactured by using photo - sintering with xenon white light instead of high - temperature and / or high - pressure sintering, and a thermoelectric module including the thermoelectric material. Different from conventional sintered materials, the upper part of the thermoelectric material serves as a thermoelectric material to provide excellent thermoelectric performance and the lower part includes a carbon - based adhesive to improve the adhesion to the substrate.

[0010] The technical problems to be solved by the concept of the present invention are not limited to the above problems, and those skilled in the art of the present disclosure will clearly understand any other technical problems not mentioned herein according to the following description.

[0011] According to an embodiment of the present disclosure, a thermoelectric material includes: a lower part, from the bottom surface of the thermoelectric material to a position of 30% of the average thickness of the thermoelectric material and the average carbon atom content is 40 at% or more of the thermoelectric material; and an upper part, corresponding to the remaining 70% of the average thickness of the thermoelectric material and the average carbon atom content is 20 at% or less of the thermoelectric material.

[0012] In addition, according to an embodiment of the present disclosure, a thermoelectric module includes a lower substrate, a plurality of electrodes formed on the lower substrate, a plurality of thermoelectric materials formed to connect the plurality of electrodes respectively, and an upper substrate disposed facing the lower substrate. Description of the Drawings

[0013] According to the following detailed description in conjunction with the accompanying drawings, the above and other objects, features, and advantages of the present disclosure will become more apparent, wherein:

[0014] Figure 1 is a view showing the surface of the microstructure of the thermoelectric material of Example 1 taken by a scanning electron microscope (SEM) according to Experimental Example 1;

[0015] Figure 2 is a view showing the cross-section of the microstructure of the thermoelectric material of Example 1 taken by a scanning electron microscope (SEM) according to Experimental Example 1;

[0016] Figure 3 is a graph showing the result of the adhesive content (average carbon atom content) of the thermoelectric material of Example 1 measured by EDS according to the thickness distribution in Experimental Example 1;

[0017] Figure 4 is a view showing the surface of the microstructure of the thermoelectric material of Comparative Example 1 according to Experimental Example 1 taken by a scanning electron microscope (SEM);

[0018] Figure 5 is a view showing the surface of the microstructure of the thermoelectric material of Comparative Example 2 according to Experimental Example 1 taken by a scanning electron microscope (SEM);

[0019] Figure 6 is a view showing the surface of the microstructure of the thermoelectric material of Comparative Example 3 according to Experimental Example 1 taken by a scanning electron microscope (SEM);

[0020] Figure 7 is a view showing a schematic diagram of the screen printing principle of a thermoelectric module manufactured according to an embodiment of the present disclosure;

[0021] Figure 8 This is a view showing the state after manufacturing the thermoelectric module (without the upper substrate) of Manufacturing Example 1. Detailed Description

[0022] Hereinafter, the present disclosure will be described in detail.

[0023] An embodiment of the present disclosure provides a thermoelectric material.

[0024] The thermoelectric material includes: a lower part having a thickness up to 30% of the average thickness of the thermoelectric material from the bottom surface and an average carbon atom content of 40 at% or more of the thermoelectric material; and an upper part having a thickness corresponding to the remaining 70% of the average thickness of the thermoelectric material and an average carbon atom content of 20 at% or less of the thermoelectric material.

[0025] The average content of carbon atoms (at%) in the thermoelectric material is the content based on the total number of atoms included in the thermoelectric material. In the thermoelectric material, the average content of carbon atoms contained in the lower part can be 40 at% to 60 at%, preferably, the average content of carbon atoms is 40 at% to 50 at%. When the average content of carbon atoms contained in the lower part of the thermoelectric material is less than 40 at% of the thermoelectric material, there is a problem that the adhesion force of the thermoelectric material to the substrate decreases. In addition, when the average content of carbon atoms is more than 60 at%, the thermoelectric performance of the thermoelectric material may decrease due to an excessive amount of binder.

[0026] In addition, in the thermoelectric material, the average content of carbon atoms contained in the upper part can be 1 at% to 20 at%, preferably, the average content of carbon atoms is 5 at% to 20 at%.

[0027] When the average content of carbon atoms contained in the upper part of the thermoelectric material is more than 20 at% of the thermoelectric material, the content of the binder in the thermoelectric material increases, and thus there is a problem that the thermoelectric performance decreases.

[0028] The content of carbon atoms contained in the thermoelectric material can be measured by using Scanning Electron Microscopy - Energy Dispersive Spectrometry (SEM - EDS) for the position of the thermoelectric material (by thickness distribution), and the obtained result value is the average content of carbon atoms according to the position.

[0029] The average thickness of the thermoelectric material refers to the average of the thickness of the thickest part and the thinnest part of the bottom surface of the thermoelectric material.

[0030] The method of measuring the thickness of the thermoelectric material can be used without limitation as long as it is a well-known method for measuring the thickness of the thermoelectric material. For example, the thickness of the thermoelectric material can be measured using a vernier caliper or can be measured from the SEM cross-sectional view, but it is not limited thereto.

[0031] The thermoelectric material can be formed by photo-sintering. For example, the thermoelectric material can be photo-sintered by irradiating xenon white light with an energy of 5 J / cm 2 to 15 J / cm 2 for 1 / 1000 to 1 / 100 seconds at an applied voltage of 200 V to 400 V. Different from the conventional thermal sintering under high temperature and high pressure, since the thermoelectric material is formed by photo-sintering at room temperature and normal pressure, the thermoelectric material has a microstructure different from that of the conventional thermoelectric material. Specifically, the average content of carbon atoms (i.e., the binder content) is adjusted according to the thickness distribution inside the thermoelectric material, thereby improving the adhesion to the substrate while improving the thermoelectric performance.

[0032] In the thermoelectric material, the average content of carbon atoms contained in the lower part (the position from the bottom surface to 30% of the average thickness of the thermoelectric material) can be more than twice the average content of carbon atoms contained in the upper part (the remaining part corresponding to 70% of the average thickness of the thermoelectric material). When the above range is satisfied, the thermoelectric performance of the thermoelectric material is improved while the adhesion to the substrate is improved.

[0033] The average thickness of the thermoelectric material can be 10 μm to 40 μm, specifically, it can be 10 μm to 35 μm, and more specifically, it can be 15 μm to 30 μm. When the average thickness of the thermoelectric material is less than 10 μm, the thermoelectric performance may be reduced. When the average thickness of the thermoelectric material is greater than 40 μm, brittleness of the thermoelectric material may occur, resulting in a decrease in the adhesion to the substrate.

[0034] The thermoelectric material can include a P-type thermoelectric material and an N-type thermoelectric material. That is, the thermoelectric material can be a P-type thermoelectric material or an N-type thermoelectric material.

[0035] The thermoelectric material can be the thermoelectric material used in the thermoelectric module. Specifically, the thermoelectric material can be the thermoelectric material used in the flexible thermoelectric module.

[0036] The embodiments of the present disclosure also provide a thermoelectric module.

[0037] The thermoelectric module can include a lower substrate, a plurality of electrodes formed on the lower substrate, a plurality of thermoelectric materials formed to be respectively connected to the plurality of electrodes, and an upper substrate disposed facing the lower substrate.

[0038] The lower substrate can be a flexible substrate. For example, the lower substrate can include at least one selected from the group consisting of polyethylene terephthalate (PET), polyimide (PI), polycarbonate (PC), and polyacrylonitrile (PAN). In particular, since the thermoelectric material is formed by photo-sintering at room temperature and the lower substrate will not be deformed by heat, the lower substrate can use a flexible material.

[0039] Each electrode can include at least one selected from the group consisting of copper (Cu), nickel (Ni), carbon (C), titanium (Ti), tungsten (W), silver (Ag), platinum (Pt), palladium (Pd), and aluminum (Al).

[0040] As described above, a thermoelectric material is formed by photo-sintering to provide a flexible thermoelectric module, and the thermoelectric material can be formed on the lower substrate and / or the electrode by screen printing. As described above, the thermoelectric material formed by screen printing can have various patterns on the substrate as Figure 7 shown and can be directly formed on the flexible substrate to provide a flexible thermoelectric module.

[0041] The ink composition for forming the thermoelectric material by screen printing can include a powder for a thermoelectric semiconductor device and a binder including a polyester resin.

[0042] The powder for the thermoelectric semiconductor device can include at least one powder selected from the group consisting of Bi-Te based alloy powder, Pb-Te based alloy powder, Si-Ge based alloy powder, Fe-Si based alloy powder, and Co-Sb based alloy powder. Specifically, the powder for the thermoelectric semiconductor device can include Bi 2-y Sb y Te 3-z Se z (0 ≤ y ≤ 2, 0 ≤ z ≤ 1), and can have various compositions according to N-type or P-type thermoelectric materials.

[0043] For example, the powder for an N-type thermoelectric semiconductor device can mainly include Bi2Te3, for example, it can include Bi2(Te,Se)3 (where the Se element is a doping element). In addition, the powder for a P-type thermoelectric semiconductor device can mainly include Sb2Te3, for example, it can include (Sb,Bi)2(Te,Se)3 (where part of Sb can be replaced by Bi).

[0044] The powder for the thermoelectric semiconductor device can be manufactured by various methods as follows, but not limited thereto.

[0045] For example, powders for thermoelectric semiconductor devices can be manufactured using the following methods: the method using an ampule (placing the raw materials in a quartz tube or a metal ampule and vacuum-sealing them for heat treatment), the arc melting method (placing the raw materials in a chamber and releasing an arc in an inert gas atmosphere to melt the raw materials to form a sample), the solid-state reaction method (performing heat treatment after sufficiently mixing the powders for hard processing or sintering after processing the mixed powders after heat treatment), the metal flux method (placing the raw materials and an element that provides an atmosphere for the raw materials to sufficiently grow into crystals at high temperature in a crucible and performing heat treatment at high temperature to grow into crystals), the Bridgeman method (placing the raw materials in a crucible, heating one end of the crucible to a high temperature until the raw materials melt, then slowly moving the high-temperature region to locally melt the sample, and passing the entire sample through the high-temperature region to grow into crystals), the zone melting method (forming the raw materials in the form of a seed rod and a feed rod, then locally heating to a high temperature to melt the sample, and slowly pulling up the melted part to grow into crystals), the vapor transport method (placing the raw materials in the lower part of a quartz tube, heating the raw materials while maintaining a low temperature in the upper part of the quartz tube, causing the raw materials to evaporate accordingly, so that a solid-phase reaction occurs at a low temperature and grows into crystals), or the mechanical alloying method (placing the raw material powder and steel balls in a hard alloy material jar and rotating, and the steel balls mechanically impact the raw material powder to alloy the raw material powder).

[0046] Depending on the materials of the ink composition, the thermoelectric material can be a P-type thermoelectric material or an N-type thermoelectric material.

[0047] Based on 100 parts by weight of the powder for thermoelectric semiconductor devices, the ink composition can include 5 to 20 parts by weight of a binder. Preferably, it can include 8 to 17 parts by weight of a binder. When the content of the binder is less than 5 parts by weight based on 100 parts by weight of the powder for thermoelectric semiconductor devices, the adhesion to the lower substrate may decrease, and when the amount of the binder is greater than 20 parts by weight, the thermoelectric performance may decrease.

[0048] In addition, the ink composition can further include a solvent, and the solvent can be used without limitation as long as it can disperse the powder and the binder for thermoelectric semiconductor devices. For example, the solvent can include carbitol acetate, etc.

[0049] Based on 100 parts by weight of the powder for a thermoelectric semiconductor device, 5 to 20 parts by weight of a solvent may be included. When the solvent content in the ink composition is less than 5 parts by weight based on 100 parts by weight of the powder for a thermoelectric semiconductor device, the dispersibility of the powder for a thermoelectric semiconductor device and the binder is reduced, and when it is greater than 20 parts by weight, it is not suitable for screen printing.

[0050] The binder including a polyester resin may further include a polyvinylpyrrolidone resin. The polyvinylpyrrolidone resin is included in the ink composition and is used to improve the adhesion between the thermoelectric material and the lower substrate.

[0051] The ink composition may include the polyester resin and the polyvinylpyrrolidone resin in a weight ratio of 0.5:1 to 10:1. Preferably, the polyester resin and the polyvinylpyrrolidone resin may be included in a weight ratio of 1:1 to 5:1. When the weight ratio of the polyester resin and the polyvinylpyrrolidone resin is less than 0.5:1, the thermoelectric performance may be excessively reduced compared to the adhesion, and when the weight ratio of the polyester resin and the polyvinylpyrrolidone resin is greater than 10:1, the adhesion to the substrate is reduced.

[0052] In addition, the ink composition may be an ink composition for a thermoelectric material.

[0053] The upper substrate may be made of the same material as the lower substrate. Accordingly, the manufactured thermoelectric module may be flexible. After photo-sintering the thermoelectric material, the upper substrate may be laminated on the upper end to form insulation.

[0054] Since the thermoelectric module manufactured as described above is flexible, the thermoelectric module may be formed into various flexible shapes.

[0055] Embodiments of the present disclosure also provide a method of manufacturing a thermoelectric module.

[0056] The method of manufacturing a thermoelectric module includes: forming a plurality of electrodes on a lower substrate; forming a thermoelectric material using an ink composition to connect the plurality of electrodes respectively; performing photo-sintering on the thermoelectric material; and after photo-sintering, laminating an upper substrate to face the lower substrate.

[0057] The lower substrate, the electrodes, the ink composition, the thermoelectric material, and the upper substrate may be the same as those described above.

[0058] A plurality of electrodes may be formed on the lower substrate using an electrode paste by screen printing. Accordingly, a plurality of electrodes may be patterned on the lower substrate, and the patterns may have various types.

[0059] The electrode paste may include at least one selected from the group including copper (Cu), nickel (Ni), carbon (C), titanium (Ti), tungsten (W), silver (Ag), platinum (Pt), palladium (Pd), and aluminum (Al), and various electrode pastes may be used as long as the electrode paste is for screen printing.

[0060] Next, an ink composition may be used to form a thermoelectric material on the lower substrate by screen printing to connect a plurality of electrodes respectively. Here, the thermoelectric material may be formed only on the lower substrate, but a part thereof may be formed on the electrodes to connect the plurality of electrodes.

[0061] The photo-sintering of the thermoelectric material may be performed at room temperature and / or normal pressure. Specifically, the photo-sintering may include irradiating xenon white light having an energy of 5 J / cm 2 to 15 J / cm 2 at an applied voltage of 200 V to 400 V. The time for irradiating the xenon white light may be from 1 / 1000 to 1 / 100 second. As described above, due to the photo-sintering, it has excellent penetration ability through instantaneous light pulses and enables the thermoelectric material to be sintered at room temperature in a very short time. Therefore, large-area processing can be achieved at low temperature, and it is suitable for high-speed sintering by the roll-to-roll (R2R) method.

[0062] After the photo-sintering, a conventional method of laminating the upper substrate to face the lower substrate may be used without limitation as long as it is a conventional method for screen printing materials.

[0063] The upper substrate may include a release layer on one of its surfaces. Specifically, the method may further include: removing the release layer before laminating the upper substrate, mounting the upper substrate on the lower substrate corresponding to the electrode pattern, and then pressing the upper substrate and the lower substrate using high-temperature hot pressing.

[0064] Hereinafter, the present disclosure will be described in detail with reference to the following examples. However, the following examples are only for illustrating the present disclosure and the present disclosure is not limited to the following examples.

[0065] <Manufacturing Examples 1 to 8>

[0066] An ink composition having the following composition in Table 1 was manufactured by the following method.

[0067] Using Bi 2-y Sb y Te 3-z Se z(0 ≤ y ≤ 2, 0 ≤ z ≤ 1) Thermoelectric particles are used to manufacture N-type or P-type ink compositions. Here, Bi2Te3 (Alfa Aesar Co., Ltd.) is used as the powder for N-type thermoelectric semiconductor devices and Sb2Te3 (Alfa Aesar Co., Ltd.) is used as the powder for P-type thermoelectric semiconductor devices. The powdered and pure powders for N-type or P-type thermoelectric semiconductor devices are mixed with a binder resin (polyester resin and / or polyvinylidene resin (Alfa Aesar Co., Ltd.)). Then, a dispersant (Alfa Aesar Co., Ltd.) is added to uniformly disperse the binder resin and the powder for the thermoelectric semiconductor device. Carbitol acetate (Alfa Aesar Co., Ltd.) is added as a solvent to adjust the viscosity and printability of the composition.

[0068] The finally manufactured ink composition is dispersed using a planetary mixer or a Thinky mixer. Then, an ink composition (slurry) for thermoelectric materials is manufactured by thoroughly stirring using a three-roll mill.

[0069] Table 1

[0070]

[0071] <Example 1>

[0072] An electrode pattern is formed on a polyimide (PI) substrate using a copper paste for electrodes, and then the N-type ink composition of Production Example 5 and the P-type ink composition of Production Example 8 are alternately screen-printed to have a height of 25 μm. The ink composition is filtered using a SUS 200 mesh before screen printing to achieve uniform dispersion.

[0073] The screen-printed electrodes and thermoelectric materials are dried in a convection oven at 130 °C for 10 minutes, and then xenon light irradiation is performed for 1 / 1000 second using a Pulse Forge 1300 (xenon light irradiation device, NovaCentrix Corporation) at an applied voltage of 350 V with an energy of 12 J / cm 2 to perform photo-sintering.

[0074] A pre-fabricated polyimide (PI) substrate as the upper substrate is laminated by high-temperature hot pressing to manufacture a thermoelectric module.

[0075] <Comparative Example 1>

[0076] A ribbon made of a thermoelectric material is manufactured using a rapid solidification process (RPS). The manufactured ribbon is formed into powder by ball milling, and then powder with a size below 50 μm is produced using a sieve shaker.

[0077] Next, the manufactured powder is placed into a mold made of graphite and a sintered body is formed using a Spark Plasma Sintering (SPS) method or a hot pressing method. At this time, the process conditions are 400 °C to 500 °C and the pressure is 20 MPa. The manufactured sintered body is cut into granular form using wire cutting technology.

[0078] <Comparative Example 2>

[0079] 1 wt% of ethyl cellulose and terpineol are mixed with the thermoelectric material, and 10 wt% to 15 wt% of a binder resin is added to manufacture a thermoelectric material slurry. Then, a sintered body is manufactured by sintering at 400 °C to 450 °C.

[0080] <Comparative Example 3>

[0081] A slurry using poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) as the thermoelectric material is manufactured and sintered at 400 °C to 450 °C to manufacture a sintered body.

[0082] <Experimental Example 1>

[0083] Figure 1 (Surface view) and Figure 2 (Cross-sectional view) are respectively photos of the surface and cross-section of the microstructure of the thermoelectric material of Example 1 taken using a scanning electron microscope (SEM). Figure 3 Shows the results of the thickness distribution of the binder content (average carbon atom content) of the thermoelectric material after photo-sintering measured using EDS.

[0084] Figures 4 to 6 Are photos of the surfaces of the microstructures of the thermoelectric materials of Comparative Examples 1 to 3 taken using a scanning electron microscope (SEM).

[0085] Refer to Figure 1 and Figure 2, when observing the microstructure of the thermoelectric material of Example 1 after sintering, it was confirmed that the inhomogeneous microstructure (round-shaped structure and microparticles (grains) within the structure, etc.) caused by high-energy aggregation resulted in excellent phonon scattering effect, and the adhesion force to the substrate was excellent due to the adhesive remaining at the lower part of the thermoelectric material. When the adhesive content was further increased at the upper part, the thermoelectric performance decreased. Therefore, it was found that the thermoelectric material of the embodiment of the present disclosure was suitable for a microstructure with an increasing adhesive content from the upper part to the lower part.

[0086] Meanwhile, in the case of Comparative Example 1, the thermoelectric material could be sintered, but high temperature / high pressure conditions were required. In the case of Comparative Example 2, high temperature and long sintering conditions were required. However, in the case of the thermoelectric material of Example 1 according to the present disclosure, the desired microstructure of the thermoelectric material could be obtained in a very short time. Therefore, it was confirmed that the thermoelectric performance and the adhesion force to the flexible substrate were excellent. In addition, in the case of the thermoelectric module of Example 1 according to the present disclosure, even without adding the organic thermoelectric material for adhering the substrate as described in Comparative Example 3, a flexible thermoelectric module could be manufactured through a simple process.

[0087] <Experimental Example 2>

[0088] The thermoelectric materials manufactured using the ink compositions according to Manufacturing Examples 1 to 8 were subjected to photo-sintering under the same conditions as in Example 1, and then the measurement results of conductivity, thermal conductivity, Seebeck coefficient, ZT value, and adhesion strength are shown in Table 2 below.

[0089] 1. Conductivity: Measured using Keithley 2700.

[0090] 2. Thermal conductivity: Measured using the thermal conductivity device (TPS M1) of Hot disk Co., Ltd.

[0091] 3. Seebeck coefficient / Performance index (ZT): While measuring the k-type temperature, voltage, and resistance, the conductivity was measured using Keithley 2700.

[0092] Seebeck coefficient = (Voltage at the high-temperature part - Voltage at the low-temperature part) / (Temperature at the high-temperature part - Temperature at the low-temperature part).

[0093] Performance index = (Square of the Seebeck coefficient × Temperature) / (Thermal conductivity × Resistance).

[0094] 4. Adhesion strength: Based on ASTM D3359, after forming a grid with 100 squares using only a cross-cut kit, a translucent tape from 3M Co., Ltd. was adhered, and then the desorption rate was evaluated.

[0095] 5B: The cut surface is clean and the square is not separated from the grid.

[0096] 4B: Small pieces of the coating (less than 5% of the grid area) are separated at the intersections.

[0097] 3B: Small pieces of the coating (greater than 5% and less than 15% of the grid area) are separated along the edges at the intersections of the cut part.

[0098] 2B: A part of the cut edge of the coating and the square (greater than 15% and less than 35% of the grid area) are separated.

[0099] 1B: The cut edge of the coating is significantly peeled off and a rectangle (greater than 35% and less than 65% of the grid area) is separated.

[0100] 0B: Peeled off and separated more than 1B (more than 65% of the grid area).

[0101] Table 2

[0102]

[0103] In Comparative Example 1, a high ZT value can be ensured, but it cannot be bonded to the substrate. In Comparative Example 2, it is difficult to ensure the thermoelectric performance index due to the low sintering temperature, and it cannot be bonded to the substrate. In Comparative Example 3, some bonding performance is ensured by the PEDOT:PSS component, but the bonding strength is very weak and it is not suitable for use as a thermoelectric module.

[0104] It was confirmed that the photo-sintered thermoelectric material manufactured from the ink compositions according to Production Examples 1 to 8 has a thermoelectric performance as high as 0.288, has a high thermoelectric performance (ZT) compared with conventional materials, and has excellent bonding strength.

[0105] Embodiments of the present disclosure can prevent thermal deformation of the flexible substrate by a photo-sintering method using xenon white light. Therefore, different from the conventional sintering method by heat treatment, the thermoelectric material can be directly applied to the flexible substrate, thereby providing a flexible thermoelectric module through simple and rapid processing.

[0106] In addition, the thermoelectric material of the embodiments of the present disclosure can adjust the adhesive content according to the thickness distribution of the thermoelectric material. Therefore, the upper part serves as a thermoelectric material, while the lower part includes a carbon (C)-based adhesive to improve the adhesion to the substrate.

[0107] In the foregoing, although the present disclosure has been described with reference to exemplary embodiments and the accompanying drawings, the present disclosure is not limited thereto. Without departing from the spirit and scope of the present disclosure claimed in the appended claims, those skilled in the art to which the present disclosure pertains can make various modifications and changes to the present disclosure.

Claims

1. A thermoelectric material, comprising: a lower portion, from the bottom surface of the thermoelectric material to a position of 30% of the average thickness of the thermoelectric material and the average carbon atom content being 40 at% to 60 at% of the thermoelectric material; and an upper portion, corresponding to the remaining 70% of the average thickness of the thermoelectric material and the average carbon atom content being 20 at% or less of the thermoelectric material.

2. The thermoelectric material according to claim 1, wherein the average thickness is 10 μm to 40 μm.

3. The thermoelectric material according to claim 1, wherein the average carbon atom content contained in the upper portion is 1 at% to 20 at% of the thermoelectric material.

4. The thermoelectric material according to claim 1, wherein the average thickness is 10 μm to 40 μm; and the average carbon atom content contained in the upper portion is 1 at% to 20 at% of the thermoelectric material.

5. The thermoelectric material according to claim 1, wherein the thermoelectric material includes a P-type thermoelectric material and an N-type thermoelectric material.

6. The thermoelectric material according to claim 1, wherein The thermoelectric material is photo-sintered by irradiating xenon white light having an energy of 5 J / cm 2 to 15 J / cm 2 for 1 / 1000 to 1 / 100 second at an applied voltage of 200 V to 400 V.

7. A thermoelectric module, comprising: a lower substrate; a plurality of electrodes formed on the lower substrate; a thermoelectric material formed to connect the plurality of electrodes respectively, the thermoelectric material including: a lower portion, from the bottom surface of the thermoelectric material to a position of 30% of the average thickness of the thermoelectric material and the average carbon atom content being 40 at% to 60 at% of the thermoelectric material; and an upper portion, corresponding to the remaining 70% of the average thickness of the thermoelectric material and the average carbon atom content being 20 at% or less of the thermoelectric material; and an upper substrate disposed facing the lower substrate.

8. The thermoelectric module according to claim 7, wherein the lower substrate includes at least one selected from the group consisting of polyethylene terephthalate (PET), polyimide (PI), polycarbonate (PC), and polyacrylonitrile (PAN).

9. The thermoelectric module according to claim 7, wherein the plurality of electrodes include electrodes formed of at least one selected from the group consisting of copper (Cu), nickel (Ni), carbon (C), titanium (Ti), tungsten (W), silver (Ag), platinum (Pt), palladium (Pd), and aluminum (Al).

10. The thermoelectric module according to claim 7, wherein the thermoelectric material includes a P-type thermoelectric material and an N-type thermoelectric material, and the P-type thermoelectric material and the N-type thermoelectric material are alternately formed.

11. The thermoelectric module according to claim 7, wherein the upper substrate is formed of the same material as the lower substrate.

12. The thermoelectric module according to claim 7, wherein The thermoelectric material is photo-sintered by irradiating xenon white light having an energy of 5 J / cm 2 to 15 J / cm 2 for 1 / 1000 to 1 / 100 second at an applied voltage of 200 V to 400 V.

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