Bismuth-telluride-based thermoelectric element, bismuth-telluride-based thermoelectric device, and preparation method therefor

Abstract

The present invention relates to the technical field of thermoelectricity. Disclosed are a bismuth-telluride-based thermoelectric element, a bismuth-telluride-based thermoelectric device and a preparation method therefor. The bismuth-telluride-based thermoelectric element comprises a bismuth-telluride-based thermoelectric material layer and a barrier layer, which is located on one surface of the bismuth-telluride-based thermoelectric material layer, wherein the barrier layer comprises a nickel-iron alloy. When an Sn-based solder is used to weld an electrode on the bismuth-telluride-based thermoelectric element provided in the present invention, the barrier layer comprising a nickel-iron alloy can effectively inhibit the diffusion of Te in the bismuth-telluride-based thermoelectric material into a welding layer to form an Sn-Te intermetallic compound with Sn in the welding layer, and a relatively thin interfacial reaction layer having an interface contact resistivity of less than 1 μΩ•cm2 is provided between the barrier layer comprising a nickel-iron alloy and the bismuth-telluride-based thermoelectric material layer. The barrier layer comprising a nickel-iron alloy used in the present invention has a great application value in the packaging of thermoelectric devices.

Description

Bismuth telluride-based thermoelectric element, bismuth telluride-based thermoelectric device and preparation method thereof Technical Field

[0001] The present invention relates to the field of thermoelectric technology, and in particular to a bismuth telluride-based thermoelectric element, a bismuth telluride-based thermoelectric device and a preparation method thereof. Background Art

[0002] Semiconductor-based thermoelectric conversion technology is a "green" technology that enables direct conversion between heat and electricity, playing a vital role in energy conservation and mitigating global warming. Thermoelectric devices, with their advantages of no moving parts, no noise, no greenhouse gas emissions, excellent stability, high reliability, compact structure, and fast response, have been successfully integrated into human production and life, finding widespread application in the automotive industry, industrial waste heat recovery, deep space exploration, healthcare, and consumer electronics. Thermoelectric devices, including thermoelectric power generation devices and thermoelectric cooling devices, are typically packaged from P-type or N-type semiconductor materials, metallization layers, solder, and metal electrodes.

[0003] Bismuth telluride is the best thermoelectric material at room temperature (20°C-150°C). Sn-based solder is typically used to weld bismuth telluride to electrodes to form a path. However, due to the high temperature during welding, direct contact between bismuth telluride and the solder will result in severe chemical reactions, and the tellurium (Te) element will rapidly diffuse into the tin-based solder layer at the welding temperature, forming a brittle and porous Sn-Te intermetallic compound. This increases contact and thermal resistance, reduces mechanical connection strength, and reduces the thermoelectric conversion efficiency and service life of thermoelectric devices, and may even lead to device welding failure. Therefore, it is necessary to select appropriate interface materials and connection processes to reduce contact resistance, improve connection strength, and enhance device performance. Currently, processes such as electroplating, chemical plating, magnetron sputtering, sintering, and arc spraying are commonly used to metallize the bismuth telluride surface to form a barrier layer to avoid the above-mentioned problems caused by direct contact between solder and thermoelectric materials during welding. Commonly used barrier layer materials include metals such as Ni, Mo, Ti, Co, and their alloys. Although using Ni as a barrier layer can effectively control the serious diffusion of elements in bismuth telluride and solder, defects such as holes and cracks will appear at the interface after long-term aging, causing a sudden increase in the interface contact resistivity, seriously affecting the reliability of the device. In addition, the interface contact resistivity between the existing Ni barrier layer and bismuth telluride is usually 5-10μΩ·cm 2 , still needs to be further reduced.

[0004] Therefore, the existing technology still needs to be improved and developed.

[0005] Summary of the Invention

[0006] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a bismuth telluride-based thermoelectric element, a bismuth telluride-based thermoelectric device and a preparation method thereof, aiming to solve the problem that the interface contact resistivity between the existing Ni barrier layer and the bismuth telluride-based thermoelectric material layer needs to be further reduced.

[0007] The technical solutions of the present invention are as follows:

[0008] According to a first aspect of the present invention, a bismuth telluride-based thermoelectric element is provided, comprising a bismuth telluride-based thermoelectric material layer and a barrier layer located on a surface of the bismuth telluride-based thermoelectric material layer, wherein the barrier layer comprises a nickel-iron alloy.

[0009] Optionally, the barrier layer has a thickness of 2-10 μm.

[0010] Optionally, the mass content of iron in the nickel-iron alloy is 15%-48%.

[0011] Optionally, the surface roughness of the bismuth telluride-based thermoelectric material layer on a side close to the barrier layer is 1.0-5.0 μm.

[0012] Optionally, the surface roughness of the bismuth telluride-based thermoelectric material layer on a side close to the barrier layer is 2.0-3.0 μm.

[0013] In a second aspect of the present invention, a bismuth telluride-based thermoelectric device is provided, which includes the bismuth telluride-based thermoelectric element as described above, a welding layer and an electrode layer, wherein the electrode layer is bonded to the surface of the barrier layer facing away from the bismuth telluride-based thermoelectric material layer through the welding layer.

[0014] Optionally, the electrode layer comprises metal or metal alloy.

[0015] A third aspect of the present invention provides a method for preparing the bismuth telluride-based thermoelectric device as described above, comprising the steps of:

[0016] providing a bismuth telluride-based thermoelectric material layer;

[0017] forming a barrier layer on the bismuth telluride-based thermoelectric material layer;

[0018] A welding layer and an electrode layer are formed on the barrier layer by welding.

[0019] Optionally, a barrier layer is formed on the bismuth telluride-based thermoelectric material layer by electroplating, and the electroplating solution used in the electroplating comprises components with the following concentrations:

[0020] FeSO4·7H2O 15g / L, NiSO4·6H2O 100-140g / L, NiCl2·6H2O 10-25g / L, H3BO3 15-25g / L, brightener 1-5g / L, wetting agent 0.1-1g / L, antioxidant 1-3g / L.

[0021] Optionally, before forming the barrier layer on the bismuth telluride-based thermoelectric material layer, the method further comprises the following steps:

[0022] The bismuth telluride-based thermoelectric material layer is processed by sandblasting or chemical etching so that the surface roughness of one surface of the bismuth telluride-based thermoelectric material layer is 1.0-5.0 μm.

[0023] Beneficial effects: The bismuth telluride-based thermoelectric element provided by the present invention includes a bismuth telluride-based thermoelectric material layer and a barrier layer located on a surface of the bismuth telluride-based thermoelectric material layer, wherein the barrier layer includes a nickel-iron alloy. When a Sn-based solder is used to weld electrodes on this bismuth telluride-based thermoelectric element, the barrier layer including the nickel-iron alloy can effectively inhibit the Te element in the bismuth telluride-based thermoelectric material from diffusing into the welding layer and forming a Sn-Te intermetallic compound with the Sn in the welding layer. In addition, the barrier layer including the nickel-iron alloy and the bismuth telluride-based thermoelectric material layer have an extremely low interface contact resistivity (less than 1 μΩ·cm 2 ) and a thinner interface reaction layer. The barrier layer of the nickel-iron alloy used in the present invention has great application value in thermoelectric device packaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG1 is a schematic structural diagram of a bismuth telluride-based thermoelectric device according to an embodiment of the present invention.

[0025] FIG2 is a schematic diagram of the preparation process of a bismuth telluride-based thermoelectric device according to an embodiment of the present invention.

[0026] FIG3 is a cross-sectional SEM image of the bismuth telluride-based thermoelectric device prepared in Example 1 of the present invention.

[0027] FIG4 is a graph showing the test results of the initial interface contact resistivity of the bismuth telluride-based thermoelectric device prepared in Example 1 of the present invention.

[0028] FIG5 is a cross-sectional SEM image of the bismuth telluride-based thermoelectric device prepared in Example 1 of the present invention after aging at 150° C. for 7 days.

[0029] FIG6 is a graph showing the interface contact resistivity test results of the bismuth telluride-based thermoelectric device prepared in Example 1 of the present invention after aging at 150° C. for 7 days.

[0030] FIG7 is a graph showing the test results of the initial interface contact resistivity of the bismuth telluride-based thermoelectric device prepared in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0031] The present invention provides a bismuth telluride-based thermoelectric element, a bismuth telluride-based thermoelectric device, and a method for preparing the same. To clarify the objectives, technical solutions, and advantages of the present invention, the present invention is described in further detail below. It should be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention.

[0032] Unless otherwise defined, all technical terms and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0033] An embodiment of the present invention provides a bismuth telluride-based thermoelectric element, which includes a bismuth telluride-based thermoelectric material layer and a barrier layer located on a surface of the bismuth telluride-based thermoelectric material layer, wherein the barrier layer includes a nickel-iron alloy.

[0034] The bismuth telluride-based thermoelectric element provided in an embodiment of the present invention includes a bismuth telluride-based thermoelectric material layer and a barrier layer located on a surface of the bismuth telluride-based thermoelectric material layer, wherein the barrier layer includes a nickel-iron alloy, that is, a NiFe alloy barrier layer. When using Sn-based solder to weld electrodes on this bismuth telluride-based thermoelectric element, the NiFe alloy barrier layer can effectively reduce the lattice mismatch, thereby increasing the diffusion barrier energy, inhibiting diffusion across the body lattice, and further effectively inhibiting the Te element in the bismuth telluride-based thermoelectric material from diffusing into the welding layer and forming a Sn-Te intermetallic compound with the Sn in the welding layer. Moreover, there is an extremely low interface contact resistivity (less than 1μΩ·cm) between the NiFe alloy barrier layer and the bismuth telluride-based thermoelectric material layer. 2 ) and a thin interfacial reaction layer. Furthermore, compared to single-metal Ni or Ni-Co alloy barrier layers, NiFe alloy barrier layers offer low production costs and high efficiency. Furthermore, Fe is inexpensive and has excellent thermal and electrical conductivity, which can reduce the cost of barrier layer materials. The present invention's use of NiFe alloy barrier layers in thermoelectric device packaging has significant commercial application value.

[0035] In some embodiments, the bismuth telluride-based thermoelectric material layer includes Bi2Te 3-x Se x , where 0≤x<1.

[0036] In some embodiments, the barrier layer has a thickness of 2-10 μm. For example, the barrier layer has a thickness of 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm. This thickness can sufficiently inhibit the diffusion of Te in the bismuth telluride-based thermoelectric material into the solder layer formed of the Sn-based solder.

[0037] In some embodiments, the mass content of Fe in the NiFe alloy is 15%-48%. In some specific embodiments, the mass content of Fe in the NiFe alloy is 15%-25%. For example, the mass content of Fe in the NiFe alloy is 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 28%, 30%, 32%, 35%, 38%, 40%, 42%, 45% or 48%, etc. When Fe is at this mass content, it can ensure that the Te element in the bismuth telluride-based thermoelectric material layer cannot diffuse into the welding layer composed of the Sn-based solder, and the barrier layer and the bismuth telluride-based thermoelectric material layer have extremely low interface contact resistivity while ensuring that the barrier layer has low cost.

[0038] In some embodiments, the surface roughness of the bismuth telluride-based thermoelectric material layer on the side close to the barrier layer is 1.0-5.0 μm. In some specific embodiments, the surface roughness of the bismuth telluride-based thermoelectric material layer on the side close to the barrier layer is 2.0-3.0 μm. For example, the surface roughness is 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5 or 5.0 μm, etc. In this embodiment, by regulating the surface roughness of the bismuth telluride-based thermoelectric material layer, an anchoring effect is formed to improve the connection strength between the bismuth telluride-based thermoelectric material layer and the NiFe alloy barrier layer. Through experimental tests, it was found that when the roughness is less than 1 μm or greater than 5 μm, the shear strength of the NiFe alloy barrier layer in the bismuth telluride-based thermoelectric element is lower than 3 MPa, and the connection strength between the bismuth telluride-based thermoelectric material layer and the NiFe alloy barrier layer is low, which seriously affects the reliability of the device. When the roughness is 1.0-5.0 μm, the shear strength of the NiFe alloy barrier layer in the bismuth telluride-based thermoelectric element exceeds 5 MPa, ensuring sufficient device reliability. Furthermore, when the roughness is 2-3 μm, the shear strength of the NiFe alloy barrier layer in the bismuth telluride-based thermoelectric element is approximately 12 MPa, indicating the highest connection strength between the bismuth telluride-based thermoelectric material layer and the NiFe alloy barrier layer.

[0039] An embodiment of the present invention also provides a bismuth telluride-based thermoelectric device, comprising the bismuth telluride-based thermoelectric element described above in the embodiment of the present invention, a welding layer, and an electrode layer. The electrode layer is bonded to the surface of the barrier layer facing away from the bismuth telluride-based thermoelectric material layer via the welding layer. Specifically, as shown in Figure 1, the bismuth telluride-based thermoelectric device comprises a bismuth telluride-based thermoelectric material layer 1, a barrier layer 2, a welding layer 3, and an electrode layer 4, stacked in sequence. The bismuth telluride-based thermoelectric device includes a bismuth telluride-based thermoelectric cooling device and a bismuth telluride-based thermoelectric power generation device. For bismuth telluride-based thermoelectric cooling devices, interfacial contact resistivity, connection strength, and the device's cooling temperature difference are important performance indicators and key factors in determining the device's long-term service life. In the embodiment of the present invention, the interfacial contact resistivity between the bismuth telluride-based thermoelectric material layer and the barrier layer is low and has sufficient connection strength, and the bismuth telluride-based thermoelectric material has a high cooling temperature difference. Therefore, the bismuth telluride-based thermoelectric refrigeration device has good performance indicators and can achieve long-term service.

[0040] In the present invention, the bismuth telluride-based thermoelectric device may further include a ceramic substrate and external metal leads.

[0041] In some embodiments, the electrode layer comprises a metal or a metal alloy. In some specific embodiments, the metal comprises, but is not limited to, Cu, Al, or Ni. The metal alloy is an alloy composed of at least two of Cu, Al, and Ni, but is not limited to these. For example, the metal alloy may be a CuAl alloy, a CuNi alloy, an AlNi alloy, or the like.

[0042] The present invention also provides a method for preparing the bismuth telluride-based thermoelectric device according to the embodiment of the present invention, as shown in FIG2 , including the steps of:

[0043] S1. providing a bismuth telluride-based thermoelectric material layer;

[0044] S2, forming a NiFe alloy barrier layer on the bismuth telluride-based thermoelectric material layer;

[0045] S3. Forming a welding layer and an electrode layer on the NiFe alloy barrier layer by welding.

[0046] In this embodiment, before welding the electrode layer on the bismuth telluride-based thermoelectric material layer, a NiFe alloy barrier layer is first formed. The NiFe alloy barrier layer can effectively reduce the lattice mismatch, thereby increasing the diffusion barrier energy and inhibiting the diffusion across the bulk lattice, thereby effectively inhibiting the Te element in the bismuth telluride-based thermoelectric material from diffusing into the welding layer and forming a Sn-Te intermetallic compound with the Sn in the welding layer. In addition, the NiFe alloy barrier layer and the bismuth telluride-based thermoelectric material layer have an extremely low interface contact resistivity (less than 1 μΩ·cm). 2) and a thin interfacial reaction layer. Furthermore, compared to single-metal Ni or Ni-Co alloy barrier layers, NiFe alloy barrier layers offer low production costs and high efficiency. Furthermore, Fe is inexpensive and has excellent thermal and electrical conductivity, which can reduce the cost of barrier layer materials. The NiFe alloy barrier layer employed in the present invention has significant commercial application value in thermoelectric device packaging.

[0047] Existing barrier layer preparation methods, such as sintering, result in uncontrollable barrier layer thickness. Arc spraying and other methods produce thicker barrier layers at higher temperatures, resulting in high costs and a high risk of severe diffusion reactions between the barrier layer and the bismuth telluride-based thermoelectric material, leading to defects such as holes and cracks and high interfacial contact resistivity. The present invention utilizes electroplating to prepare the barrier layer, resulting in a more uniform barrier layer thickness, no high temperatures required, lower costs, and a simpler process, making it more commercially viable.

[0048] In some embodiments, before forming the welding layer and the barrier layer on the bismuth telluride-based thermoelectric material layer, the method further includes the following steps:

[0049] The bismuth telluride-based thermoelectric material layer is treated by sandblasting or chemical etching to achieve a surface roughness of 1.0-5.0 μm on one surface of the bismuth telluride-based thermoelectric material layer. This surface roughness can create an anchoring effect between the bismuth telluride-based thermoelectric material layer and the NiFe alloy barrier layer, thereby improving the connection strength between the bismuth telluride-based thermoelectric material layer and the NiFe alloy barrier layer.

[0050] In step S2, in some embodiments, a NiFe alloy barrier layer is formed on the bismuth telluride-based thermoelectric material layer by electroplating, and the electroplating solution (using water as a solvent) used in the electroplating comprises the following components in concentrations:

[0051] FeSO4·7H2O 15g / L, NiSO4·6H2O 100-140g / L, NiCl2·6H2O 10-25g / L, H3BO3 15-25g / L, brightener 1-5g / L, wetting agent 0.1-1g / L, antioxidant 1-3g / L.

[0052] In this embodiment, the above-mentioned electroplating solution is used to form a NiFe alloy barrier layer on the surface of the bismuth telluride-based thermoelectric material layer having a roughness (1.0-5.0 μm) by electroplating.

[0053] In some embodiments, the brightening agent includes sodium saccharin (C6H4SO2NNaCO·2H2O), but is not limited thereto.

[0054] In some embodiments, the lubricant includes sodium lauryl sulfate, but is not limited thereto.

[0055] In some embodiments, the antioxidant includes vitamin C (C6H8O6), but is not limited thereto.

[0056] In step S3, in some embodiments, the solder used for welding is a tin-based solder, specifically Sn 95 Sb5 solder.

[0057] The following describes it in detail through specific examples.

[0058] Example 1

[0059] This embodiment provides a method for preparing a bismuth telluride-based thermoelectric cooling device, comprising the following steps:

[0060] Provide N-type Bi2Te with a thickness of 1mm and a diameter of 30mm 2.7 Se 0.3 Chip;

[0061] The N-type Bi2Te 2.7 Se 0.3 The wafer was placed in a sandblasting machine with a pressure of 4.8 MPa. Alumina powder with a particle size of 150 mesh was used to blast the N-type Bi2Te 2.7 Se 0.3 One surface of the wafer was sandblasted to obtain an N-type Bi2Te with a surface roughness of 2.5 μm. 2.7 Se 0.3 Wafer (one surface has a roughness of 2.5 μm).

[0062] An electroplating solution is provided, wherein the electroplating solution uses water as a solvent and includes the following components in the following concentrations:

[0063] FeSO4·7H2O 15g / L, NiSO4·6H2O 120g / L, NiCl2·6H2O 18g / L, H3BO320g / L, C6H4SO2NNaCO·2H2O 3g / L, sodium lauryl sulfate 0.5g / L, C6H8O62g / L.

[0064] N-type Bi2Te with a surface roughness of 2.5 μm 2.7 Se 0.3 The wafer is placed in the plating solution, and the N-type Bi2Te 2.7 Se 0.3 Electroplating is performed on the rough surface of the wafer. The electroplating process parameters are: temperature 50°C, current 2A / dm 2 , forming a NiFe alloy coating with a thickness of 2 μm, the mass content of Fe in the NiFe alloy coating is 21.71%, and the NiFe alloy coating is a NiFe alloy barrier layer.

[0065] Sn95 Sb5 solder (melting point is 240℃) is used to weld a Cu electrode with a thickness of 80μm to the NiFe alloy barrier layer to form a welding layer and an electrode layer to obtain a bismuth telluride-based thermoelectric cooling device. 95 The Sb5 solder forms a solder layer with a thickness of 40 μm between the Cu electrode and the NiFe alloy barrier layer.

[0066] Test: The cross-sectional SEM test of the bismuth telluride-based thermoelectric cooling device prepared in Example 1 was performed. The results are shown in Figure 3. The interface boundaries between the layers are clear, and the thickness of the initial interface reaction layer is about 0.5 μm. It can be seen that in the present invention, the interface reaction layer between the NiFe alloy barrier layer and the bismuth telluride-based thermoelectric material is relatively thin. The initial interface reaction layer is mainly composed of Bi2Te 2.7 Se 0.3 The Te element diffused in the wafer reacts with the Ni element diffused in the NiFe alloy barrier layer to form a reaction product, and the reaction product is mainly a Ni-Te compound.

[0067] The interface contact resistivity of the bismuth telluride-based thermoelectric refrigeration device prepared in Example 1 was tested, specifically the total interface contact resistivity (the same below), including Bi2Te 2.7 Se 0.3 The contact resistance between the NiFe alloy barrier layer and the NiFe alloy barrier layer, the NiFe alloy barrier layer and the solder layer, the solder layer and the Cu electrode, and the bulk resistance of the NiFe alloy barrier layer (compared to Bi2Te 2.7 Se 0.3 The contact resistance between the interface and the NiFe alloy barrier layer is small, and the contact resistance between the other layers and the bulk resistance of the NiFe alloy barrier layer are extremely small. The measured initial interface contact resistivity is shown in Figure 4. The initial interface contact resistivity is less than 1μΩ·cm 2 .

[0068] The bismuth telluride-based thermoelectric cooling device prepared in Example 1 was placed in an environment at 150°C and aged for 7 days. A cross-sectional SEM test and an interface contact resistivity test were performed. The results are shown in Figures 5 and 6, respectively. The SEM results show that there are no defects such as holes and cracks at the interface. The interface contact resistivity test shows that the interface contact resistivity of the bismuth telluride-based thermoelectric cooling device is 0.94μΩ·cm 2 .

[0069] Example 2

[0070] This embodiment provides a method for preparing a bismuth telluride-based thermoelectric cooling device, comprising the steps of:

[0071] Provide N-type Bi2Te with a thickness of 1mm and a diameter of 30mm 2.7 Se 0.3 Chip;

[0072] The N-type Bi2Te 2.7 Se 0.3 The wafer was placed in a sandblasting machine with a pressure of 4.8 MPa. Alumina powder with a particle size of 150 mesh was used to blast the N-type Bi2Te 2.7 Se 0.3 One surface of the wafer was sandblasted, then cleaned with alcohol ultrasonic wave and deionized water, and an N-type Bi2Te with a surface roughness of 2.5 μm was obtained. 2.7 Se 0.3 Wafer (one surface has a roughness of 2.5 μm).

[0073] A plating solution is provided, which differs from the plating solution in Example 1 only in that the concentration of FeSO4·7H2O is 35 g / L, and the other components and concentrations remain unchanged.

[0074] N-type Bi2Te with a surface roughness of 2.5 μm 2.7 Se 0.3 The wafer is placed in the plating solution, and the N-type Bi2Te 2.7 Se 0.3 Electroplating is performed on the rough surface of the wafer to form a NiFe alloy coating with a thickness of 4 μm. The mass content of Fe in the NiFe alloy coating is 47.72%. The NiFe alloy coating is a NiFe alloy barrier layer.

[0075] Sn 95 Sb5 solder (melting point is 240℃) is used to weld a Cu electrode layer with a thickness of 80μm to the NiFe alloy barrier layer to form a welding layer and an electrode layer to obtain a bismuth telluride-based thermoelectric cooling device. 95 The Sb5 solder forms a solder layer with a thickness of 40 μm between the Cu electrode and the NiFe alloy barrier layer.

[0076] Test: The interface contact resistivity of the bismuth telluride-based thermoelectric cooling device in Example 2 was tested. The initial interface contact resistivity was 3.36 μΩcm. 2 .

[0077] Comparative Example 1

[0078] This comparative example provides a bismuth telluride-based thermoelectric refrigeration device, comprising the steps of:

[0079] Provide N-type Bi2Te with a thickness of 1mm and a diameter of 30mm 2.7 Se 0.3 Chip;

[0080] The N-type Bi2Te 2.7 Se 0.3The wafer was placed in a sandblasting machine with a pressure of 4.8 MPa and alumina powder with a particle size of 150 mesh was used to blast the N-type Bi2Te 2.7 Se 0.3 One surface of the wafer was sandblasted, then cleaned with alcohol ultrasonic wave and deionized water, and an N-type Bi2Te with a surface roughness of 2.5 μm was obtained. 2.7 Se 0.3 Wafer (one surface has a roughness of 2.5 μm).

[0081] A plating solution is provided, which differs from the plating solution in Example 1 only in that FeSO4·7H2O is not added, and other components and concentrations remain unchanged.

[0082] N-type Bi2Te with a surface roughness of 2.5 μm 2.7 Se 0.3 The wafer is placed in the plating solution, and the N-type Bi2Te 2.7 Se 0.3 Electroplating is performed on the rough surface of the wafer to form a Ni plating layer with a thickness of 2 μm, which serves as a Ni barrier layer.

[0083] Sn 95 Sb5 solder (melting point is 240℃) is used to weld a Cu electrode layer with a thickness of 80μm to the Ni barrier layer to form a welding layer and an electrode layer to obtain a bismuth telluride-based thermoelectric cooling device. 95 The Sb5 solder forms a solder layer with a thickness of 40 μm between the Cu electrode and the Ni barrier layer.

[0084] The interface contact resistivity of the bismuth telluride-based thermoelectric cooling device prepared in Comparative Example 1 was tested. The results are shown in FIG7 . The initial interface contact resistivity of the bismuth telluride-based thermoelectric cooling device prepared in Comparative Example 1 is 5.88 μΩ·cm 2 .

[0085] From the test results of Example 1, Example 2 and Comparative Example 1, it can be seen that the initial interface contact resistivity of the bismuth telluride-based thermoelectric refrigeration device in Example 1 is less than 1 μΩ·cm 2 (As shown in FIG4 ), the initial interface contact resistivity of the bismuth telluride-based thermoelectric cooling device in Example 2 is 3.36 μΩ·cm 2 The initial interface contact resistivity of the bismuth telluride-based thermoelectric refrigeration device in Comparative Example 1 is 5.88 μΩ·cm 2(As shown in Figure 7). Therefore, the above results show that compared with the Ni barrier layer, the interface contact resistivity between the NiFe alloy barrier layer and the bismuth telluride-based thermoelectric material layer in the present invention is lower. And the resistivity between the NiFe alloy barrier layer and the bismuth telluride-based thermoelectric material layer increases with the increase of Fe content; at the same time, the increase of Fe content will also increase the stress of the NiFe barrier layer, thereby affecting the interface connection quality and causing the interface contact resistivity to increase. In Example 1, the NiFe alloy barrier layer with an Fe content of approximately 20% and the bismuth telluride-based thermoelectric material layer have the best connection stability and lower interface contact resistivity.

[0086] In summary, the bismuth telluride-based thermoelectric element provided by the present invention includes a bismuth telluride-based thermoelectric material layer and a barrier layer located on a surface of the bismuth telluride-based thermoelectric material layer, wherein the barrier layer includes a nickel-iron alloy. When a Sn-based solder is used to weld electrodes to this bismuth telluride-based thermoelectric element, the barrier layer including the NiFe alloy can effectively inhibit the Te element in the bismuth telluride-based thermoelectric material from diffusing into the solder layer and forming a Sn-Te intermetallic compound with the Sn in the solder layer. In addition, the barrier layer including the NiFe alloy and the bismuth telluride-based thermoelectric material layer have an extremely low interface contact resistivity (less than 1 μΩ·cm 2 ) and a thin interface reaction layer. The barrier layer of the NiFe alloy used in the present invention has great application value for thermoelectric device packaging.

[0087] It should be understood that the application of the present invention is not limited to the above examples. For those skilled in the art, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A bismuth telluride-based thermoelectric element, It is characterized in that The invention comprises a bismuth telluride-based thermoelectric material layer and a barrier layer located on a surface of the bismuth telluride-based thermoelectric material layer, wherein the barrier layer comprises a nickel-iron alloy.

2. The bismuth telluride-based thermoelectric element according to claim 1, It is characterized in that The thickness of the barrier layer is 2-10 μm.

3. The bismuth telluride-based thermoelectric element according to claim 1, It is characterized in that The mass content of iron in the nickel-iron alloy is 15%-48%.

4. The bismuth telluride-based thermoelectric element according to claim 1, It is characterized in that The surface roughness of the bismuth telluride-based thermoelectric material layer on a side close to the barrier layer is 1.0-5.0 μm.

5. The bismuth telluride-based thermoelectric element according to claim 4, It is characterized in that The surface roughness of the bismuth telluride-based thermoelectric material layer on a side close to the barrier layer is 2.0-3.0 μm.

6. A bismuth telluride-based thermoelectric device, It is characterized in that The invention comprises the bismuth telluride-based thermoelectric element according to any one of claims 1 to 5, a welding layer and an electrode layer, wherein the electrode layer is bonded to the surface of the barrier layer on the side away from the bismuth telluride-based thermoelectric material layer through the welding layer.

7. The bismuth telluride-based thermoelectric device according to claim 6, It is characterized in that The electrode layer includes a metal or a metal alloy.

8. A method for preparing a bismuth telluride-based thermoelectric device according to any one of claims 6 to 7, It is characterized in that Includes steps: providing a bismuth telluride-based thermoelectric material layer; forming a barrier layer on the bismuth telluride-based thermoelectric material layer; A welding layer and an electrode layer are formed on the barrier layer by welding.

9. The preparation method according to claim 8, It is characterized in that The barrier layer is formed on the bismuth telluride-based thermoelectric material layer by electroplating, and the electroplating solution used in the electroplating includes the following components in concentration: FeSO 4 ·7H 2 O 15 g / L, NiSO 4 ·6H 2 O 100 - 140 g / L, NiCl 2 ·6H 2 O 10 - 25 g / L, H 3 BO 3 15 - 25 g / L, brightener 1 - 5 g / L, wetting agent 0.1 - 1 g / L, antioxidant 1 - 3 g / L.

10. The preparation method according to claim 8, It is characterized in that Before forming the barrier layer on the bismuth telluride-based thermoelectric material layer, the method further comprises the following steps: The bismuth telluride-based thermoelectric material layer is processed by sandblasting or chemical etching so that the surface roughness of one surface of the bismuth telluride-based thermoelectric material layer is 1.0-5.0 μm.

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