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

Abstract

The invention discloses a bismuth telluride-based thermoelectric element, a bismuth telluride-based thermoelectric device and a preparation method of the bismuth telluride-based thermoelectric element and the bismuth telluride-based thermoelectric device, and relates to the technical field of thermoelectricity, the bismuth telluride-based thermoelectric element comprises a bismuth telluride-based thermoelectric material layer and a barrier layer located on one surface of the bismuth telluride-based thermoelectric material layer, and the barrier layer comprises a nickel-iron alloy. When Sn-based solder is adopted to weld an electrode on the bismuth telluride-based thermoelectric element provided by the invention, the barrier layer comprising the nickel-iron alloy can effectively inhibit the Te element in the bismuth telluride-based thermoelectric material from diffusing into the welding layer to form a Sn-Te intermetallic compound with the Sn in the welding layer; and the interface contact resistivity of less than 1 mu omega.cm < 2 > and a thinner interface reaction layer are arranged between the barrier layer comprising the nickel-iron alloy and the bismuth telluride-based thermoelectric material layer. The barrier layer comprising the ferro-nickel alloy has huge application value in thermoelectric device packaging.

Description

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] Thermoelectric conversion technology based on semiconductor materials is a "green" technology that can realize the direct conversion between thermal energy and electrical energy, and plays an important role in saving energy and alleviating global warming. Thermoelectric devices have the advantages of no mechanical moving parts, no noise, no greenhouse gas emissions, good stability, high reliability, compact structure, and fast response. They have been successfully integrated into human production and life, and have been widely used in the automotive industry, industrial waste heat recovery, deep space exploration, medical and health care, and consumer electronics. Thermoelectric devices include thermoelectric power generation devices and thermoelectric cooling devices, which are usually packaged by P-type or N-type semiconductor materials, metallization layers, solders, metal electrodes, etc.

[0003] Bismuth telluride is the best thermoelectric material at room temperature (20℃-150℃). Sn-based solder is usually used to weld bismuth telluride to electrodes to form a path. Due to the high temperature during welding, bismuth telluride will directly contact the solder and will undergo severe chemical reactions. The tellurium (Te) element will quickly diffuse into the tin-based solder layer at the welding temperature to form a brittle and porous Sn-Te intermetallic compound, which will increase the contact resistance and thermal resistance, reduce the mechanical connection strength, and reduce the thermoelectric conversion efficiency and service life of the thermoelectric device, and even cause the device welding failure. Therefore, it is necessary to select suitable interface materials and connection processes to reduce contact resistance, increase connection strength, and improve device performance. At present, electroplating, chemical plating, magnetron sputtering, sintering, arc spraying and other processes are usually used to metallize the surface of bismuth telluride to form a barrier layer to avoid the above problems caused by direct contact between solder and thermoelectric materials during welding. Commonly used barrier layer materials include Ni, Mo, Ti, Co and other metals 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, resulting in a sudden increase in the interface contact resistivity, which seriously affects 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 prior art still needs to be improved and developed. Summary of the invention

[0005] 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.

[0006] The technical solution of the present invention is as follows:

[0007] 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.

[0008] Optionally, the barrier layer has a thickness of 2-10 μm.

[0009] Optionally, the mass content of iron in the nickel-iron alloy is 15%-48%.

[0010] 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.

[0011] 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.

[0012] A second aspect of the present invention provides a bismuth telluride-based thermoelectric device, 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 away from the bismuth telluride-based thermoelectric material layer through the welding layer.

[0013] Optionally, the electrode layer comprises metal or metal alloy.

[0014] 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:

[0015] providing a bismuth telluride-based thermoelectric material layer;

[0016] forming a barrier layer on the bismuth telluride-based thermoelectric material layer;

[0017] A welding layer and an electrode layer are formed on the barrier layer by welding.

[0018] Optionally, the barrier layer is formed on the bismuth telluride-based thermoelectric material layer by electroplating, and the electroplating solution used in the electroplating includes components with the following concentrations:

[0019] FeSO 4 7H 2 O 15g / L, NiSO 4 6H 2 O 100-140g / L, NiCl 2 6H 2 O 10-25g / L, H 3 BO 315-25g / L, brightener 1-5g / L, wetting agent 0.1-1g / L, antioxidant 1-3g / L.

[0020] Optionally, before forming the barrier layer on the bismuth telluride-based thermoelectric material layer, the method further comprises the following steps:

[0021] 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.

[0022] Beneficial effect: The bismuth telluride-based thermoelectric element provided by the present 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. When a Sn-based solder is used to weld electrodes on the bismuth telluride-based thermoelectric element, the barrier layer comprising 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, and the barrier layer comprising 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 the packaging of thermoelectric devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the structure of a bismuth telluride-based thermoelectric device in an embodiment of the present invention.

[0024] Figure 2 Schematic diagram of the preparation process of bismuth telluride-based thermoelectric devices in an embodiment of the present invention.

[0025] Figure 3 This is a cross-sectional SEM image of the bismuth telluride-based thermoelectric device prepared in Example 1 of the present invention.

[0026] Figure 4 This is a graph showing the initial interface contact resistivity test results of the bismuth telluride-based thermoelectric device prepared in Example 1 of the present invention.

[0027] Figure 5 This 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.

[0028] Figure 6 This is a graph showing the test results of the interface contact resistivity of the bismuth telluride-based thermoelectric device prepared in Example 1 of the present invention after aging at 150° C. for 7 days.

[0029] Figure 7 This is a graph showing the initial interface contact resistivity test results of the bismuth telluride-based thermoelectric device prepared in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0030] The present invention provides a bismuth telluride-based thermoelectric element, a bismuth telluride-based thermoelectric device and a preparation method thereof. In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0031] 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.

[0032] 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.

[0033] 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 the 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 Sn-Te intermetallic compounds with the Sn in the welding layer. And 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 interface reaction layer. In addition, compared with the single metal Ni or Ni-Co alloy barrier layer, the NiFe alloy barrier layer has low production cost and high efficiency, and Fe has low price and good thermal and electrical conductivity, which can reduce the cost of the barrier layer material. The present invention uses the NiFe alloy barrier layer in the thermoelectric device package, which has great commercial application value.

[0034] In some embodiments, the bismuth telluride-based thermoelectric material layer includes Bi 2 Te 3-x Se x , where 0≤x<1.

[0035] 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, etc. This thickness can fully inhibit the Te element in the bismuth telluride-based thermoelectric material from diffusing into the solder layer composed of the Sn-based solder.

[0036] 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 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 a low cost.

[0037] 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 3MPa, and the bismuth telluride-based thermoelectric material layer and the NiFe alloy barrier layer have a low connection strength, 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 is greater than 5 MPa, which can ensure that the device has sufficient 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 about 12 MPa, and the bismuth telluride-based thermoelectric material layer and the NiFe alloy barrier layer have the highest connection strength.

[0038] The embodiment of the present invention further provides a bismuth telluride-based thermoelectric device, which includes the bismuth telluride-based thermoelectric element described in the embodiment of the present invention, 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. Figure 1As shown, the bismuth telluride-based thermoelectric device includes a bismuth telluride-based thermoelectric material layer 1, a barrier layer 2, a welding layer 3 and an electrode layer 4 which are stacked in sequence. The bismuth telluride-based thermoelectric device includes a bismuth telluride-based thermoelectric refrigeration device and a bismuth telluride-based thermoelectric power generation device. For bismuth telluride-based thermoelectric refrigeration devices, the interface contact resistivity, connection strength and the cooling temperature difference of the device are important indicators for measuring the performance of thermoelectric refrigeration devices, and are also the key to determining whether the device can serve for a long time. In the embodiment of the present invention, the bismuth telluride-based thermoelectric material layer and the barrier layer have a low interface contact resistivity and 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.

[0039] In the present invention, the bismuth telluride-based thermoelectric device may further include a ceramic substrate and external metal leads.

[0040] In some embodiments, the electrode layer includes a metal or a metal alloy. In some specific embodiments, the metal includes Cu, Al or Ni, etc., but is not limited thereto, and the metal alloy is an alloy composed of at least two of Cu, Al and Ni, but is not limited thereto. As an example, the metal alloy can be a CuAl alloy, a CuNi alloy, an AlNi alloy, etc.

[0041] The present invention also provides a method for preparing the bismuth telluride-based thermoelectric device according to the present invention, wherein: Figure 2 As shown, the steps include:

[0042] S1. providing a bismuth telluride-based thermoelectric material layer;

[0043] S2, forming a NiFe alloy barrier layer on the bismuth telluride-based thermoelectric material layer;

[0044] S3. Forming a welding layer and an electrode layer on the NiFe alloy barrier layer by welding.

[0045] 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 well reduce the lattice mismatch, thereby increasing the diffusion barrier energy, inhibiting the diffusion across the body lattice, and thus 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 Sn in the welding layer, and 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 interface reaction layer. In addition, compared with the single metal Ni or Ni-Co alloy barrier layer, the NiFe alloy barrier layer has low production cost and high efficiency, and Fe has low price and good thermal and electrical conductivity, which can reduce the cost of the barrier layer material. The NiFe alloy barrier layer used in the present invention has great commercial application value in thermoelectric device packaging.

[0046] Existing preparation methods such as sintering to prepare the barrier layer will result in uncontrollable thickness of the barrier layer. Arc spraying and other methods have a thicker barrier layer and use a higher temperature, which is more expensive and easily causes a serious diffusion reaction between the barrier layer and the bismuth telluride-based thermoelectric material, resulting in defects such as holes and cracks, and a larger interface contact resistivity. The present invention uses an electroplating method to prepare the barrier layer, which has a more uniform thickness, does not require high temperature, has a lower cost, is simpler in process, and is easier to commercialize.

[0047] 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:

[0048] 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. The surface roughness can form 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.

[0049] 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 (with water as solvent) used in the electroplating includes the following components in concentration:

[0050] FeSO 4 7H 2 O 15g / L, NiSO 4 6H 2 O 100-140g / L, NiCl 2 6H 2 O 10-25g / L, H 3 BO 3 15-25g / L, brightener 1-5g / L, wetting agent 0.1-1g / L, antioxidant 1-3g / L.

[0051] In this embodiment, the above-mentioned electroplating solution is used to form a NiFe alloy barrier layer by electroplating on the surface of the bismuth telluride-based thermoelectric material layer having a roughness (1.0-5.0 μm).

[0052] In some embodiments, the brightening agent comprises saccharin sodium (C6 H 4 SO 2 NNaCO·2H 2 O), but not limited thereto.

[0053] In some embodiments, the lubricant includes sodium lauryl sulfate, but is not limited thereto.

[0054] In some embodiments, the antioxidant comprises vitamin C (C 6 H 8 O 6 ), but are not limited to them.

[0055] In step S3, in some embodiments, the solder used for welding is a tin-based solder, specifically Sn 95 Sb 5 solder.

[0056] The following describes it in detail through specific embodiments.

[0057] Example 1

[0058] This embodiment provides a method for preparing a bismuth telluride-based thermoelectric cooling device, comprising the following steps:

[0059] Provide N-type Bi with a thickness of 1mm and a diameter of 30mm 2 Te 2.7 Se 0.3 Wafer;

[0060] The N-type Bi 2 Te 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 Bi 2 Te 2.7 Se 0.3 One surface of the wafer was sandblasted to obtain an N-type Bi with a surface roughness of 2.5 μm. 2 Te 2.7 Se 0.3 Wafer (one surface has a roughness of 2.5 μm).

[0061] A plating solution is provided, wherein the plating solution uses water as a solvent and comprises components in the following concentrations:

[0062] FeSO 4 7H 2 O 15g / L, NiSO 4 6H 2 O 120g / L, NiCl 2 6H 2 O 18g / L, H3 BO 3 20g / L, C 6 H 4 SO 2 NNaCO·2H 2 O 3g / L, sodium dodecyl sulfate 0.5g / L, C 6 H 8 O 6 2g / L.

[0063] The surface roughness of N-type Bi 2 Te 2.7 Se 0.3 The chip is placed in the plating solution. 2 Te 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 , a NiFe alloy coating with a thickness of 2 μm is formed, the mass content of Fe in the NiFe alloy coating is 21.71%, and the NiFe alloy coating is the NiFe alloy barrier layer.

[0064] Sn 95 Sb 5 The bismuth telluride-based thermoelectric cooling device was obtained by soldering a Cu electrode with a thickness of 80 μm to the NiFe alloy barrier layer to form a solder layer and an electrode layer. 95 Sb 5 The solder forms a solder layer with a thickness of 40 μm between the Cu electrode and the NiFe alloy barrier layer.

[0065] Test: The bismuth telluride-based thermoelectric cooling device prepared in Example 1 was subjected to a cross-sectional SEM test. The results are as follows: Figure 3 As shown in FIG. 1 , 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 Bi 2 Te 2.7 Se 0.3 The Te element diffused in the wafer reacts with the Ni element diffused in the NiFe alloy barrier layer, and the reaction product is mainly a Ni-Te compound.

[0066] 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 Bi 2 Te 2.7 Se 0.3The contact resistance between the NiFe alloy barrier layer and the NiFe alloy barrier layer, the NiFe alloy barrier layer and the welding layer, the welding layer and the Cu electrode, and the bulk resistance of the NiFe alloy barrier layer (compared to the Bi 2 Te 2.7 Se 0.3 The contact resistance between the NiFe alloy barrier layer 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 as follows: Figure 4 As shown, the initial interface contact resistivity is less than 1μΩ·cm 2 .

[0067] 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 were as follows: Figure 5 and 6 As shown; 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 .

[0068] Example 2

[0069] This embodiment provides a method for preparing a bismuth telluride-based thermoelectric cooling device, comprising the steps of:

[0070] Provide N-type Bi with a thickness of 1mm and a diameter of 30mm 2 Te 2.7 Se 0.3 Wafer;

[0071] The N-type Bi 2 Te 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 Bi 2 Te 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 Bi wafer with a surface roughness of 2.5 μm was obtained. 2 Te 2.7 Se 0.3 Wafer (one surface has a roughness of 2.5 μm).

[0072] A plating solution is provided, which differs from the plating solution in Example 1 only in that: FeSO 4 7H 2 O concentration is 35g / L, and other components and concentrations remain unchanged.

[0073] The surface roughness of N-type Bi 2 Te 2.7 Se 0.3 The chip is placed in the plating solution. 2 Te 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.

[0074] Sn 95 Sb 5 The bismuth telluride-based thermoelectric cooling device is obtained by soldering a Cu electrode layer with a thickness of 80 μm to the NiFe alloy barrier layer to form a solder layer and an electrode layer. 95 Sb 5 The solder forms a solder layer with a thickness of 40 μm between the Cu electrode and the NiFe alloy barrier layer.

[0075] Test: The interface contact resistivity test of the bismuth telluride-based thermoelectric cooling device in Example 2 was performed, and the initial interface contact resistivity was 3.36 μΩcm 2 .

[0076] Comparative Example 1

[0077] This comparative example provides a bismuth telluride-based thermoelectric refrigeration device, comprising the steps of:

[0078] Provide N-type Bi with a thickness of 1mm and a diameter of 30mm 2 Te 2.7 Se 0.3 Wafer;

[0079] The N-type Bi 2 Te 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 Bi 2 Te 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 Bi wafer with a surface roughness of 2.5 μm was obtained. 2 Te 2.7 Se 0.3 Wafer (one surface has a roughness of 2.5 μm).

[0080] A plating solution is provided, which differs from the plating solution in Example 1 only in that FeSO is not added 4 7H 2O, other ingredients and concentrations remain unchanged.

[0081] The surface roughness of N-type Bi 2 Te 2.7 Se 0.3 The chip is placed in the plating solution. 2 Te 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, and the Ni plating layer is a Ni barrier layer.

[0082] Sn 95 Sb 5 Solder (melting point is 240℃), and solder the Cu electrode layer with a thickness of 80μm to the Ni barrier layer to form a solder layer and an electrode layer to obtain a bismuth telluride-based thermoelectric cooling device, Sn 95 Sb 5 The solder forms a solder layer with a thickness of 40 μm between the Cu electrode and the Ni barrier layer.

[0083] The interface contact resistivity test of the bismuth telluride-based thermoelectric refrigeration device prepared in Comparative Example 1 was performed. The results are as follows: Figure 7 As shown, the initial interface contact resistivity of the bismuth telluride-based thermoelectric refrigeration device prepared in Comparative Example 1 is 5.88 μΩ·cm 2 .

[0084] 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 (like Figure 4 As shown in FIG. 2 , 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 cooling device in Comparative Example 1 is 5.88 μΩ·cm 2 (like Figure 7 As shown). 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% has the best connection stability and lower interface contact resistivity with the bismuth telluride-based thermoelectric material layer.

[0085] In summary, the bismuth telluride-based thermoelectric element provided by the present 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. When a Sn-based solder is used to weld electrodes on the bismuth telluride-based thermoelectric element, the barrier layer comprising a NiFe 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, and the barrier layer comprising a 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.

[0086] It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, 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 15g / L, NiSO 4 6H 2 O 100-140g / L, NiCl 2 6H 2 O 10-25g / L, H 3 BO 3 15-25g / L, brightener 1-5g / L, wetting agent 0.1-1g / L, antioxidant 1-3g / 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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