Thermoelectric device and preparation method thereof

Abstract

The invention provides a thermoelectric device and a preparation method thereof, and belongs to the field of preparation processes. The method includes configuring a thermoelectric structure printing raw material; printing the thermoelectric structure by using the prepared thermoelectric structure printing raw material and adopting a 3D printing ink direct writing technology; preparing a heat conduction material, a heat insulation material, a heat absorption material and a reflection material, and printing a heat conduction structure, a heat insulation structure, a heat absorption structure and a reflection structure by using the prepared heat conduction material, heat insulation material, heat absorption material and reflection material through a 3D printing ink direct writing technology; and assembling the 3D printed thermoelectric structure, the heat conduction structure, the heat insulation structure, the heat absorption structure and the reflecting material into the thermoelectric device. In addition, the invention also provides the thermoelectric device prepared by the method. According to the method, the manufacturing process is simplified, waste of raw materials is reduced, fine structures can be manufactured, and the method has wide application prospects. All the structures are prepared and formed through the 3D printing technology.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy collection structure design and preparation process thereof, and in particular relates to a thermoelectric device and a preparation method thereof. Background Art

[0002] With climate change and population growth, people need more and more energy in their daily lives, but the resources on earth are limited, so it is necessary to develop some new energy sources to meet future energy needs. Thermal energy is a clean energy source and is everywhere. Using thermoelectric conversion technology, the temperature difference can be converted into a voltage difference. Collecting the waste heat generated in the natural environment and human activities will be a huge source of energy.

[0003] Traditional manufacturing of thermoelectric generators is a challenging and tedious task. They are usually manufactured through processes such as hot pressing, spark plasma sintering and zone melting. These processes usually involve high temperatures and are cumbersome to operate, so they consume energy and time. The sintered structure is also blocky and rigid, making it difficult to manufacture fine and complex structures, and a large amount of raw materials are wasted, which is not conducive to the widespread manufacturing and application of thermoelectric power generation. Therefore, in order to achieve high-precision three-dimensional structures, simplify the manufacturing process, and achieve multi-material combination, additive manufacturing technology has become a very promising processing technology. Additive manufacturing, commonly known as 3D printing, is a method for rapid prototyping of complex geometric shapes. It involves depositing raw materials in a layer-by-layer manner, and the process parameters are determined by computer-controlled algorithms. Because it has minimal need for reprocessing, negligible waste, and is applicable to a variety of materials, in theory, various materials can be configured into rheological inks and printed into complex structures, which greatly reduces the difficulty of manufacturing thermoelectric devices and increases the complexity of the structure.

[0004] There are currently few publicly reported technologies for 3D printing of thermoelectric materials, and the main possible problems are: 1. The manufacture of thermoelectric devices requires the inclusion of multiple materials, such as N-type thermoelectric materials, P-type thermoelectric materials, electrode materials, etc. The 3D printing of thermoelectric devices requires the coordinated printing of multiple materials, which is relatively difficult; 2. 3D printing ink direct writing technology is a better way to print functional materials. Using this technology, the functional materials need to be configured into printable inks with rheological properties. The various materials of thermoelectric devices need to be adjusted in proportion to meet printing requirements, and continuous adjustment and improvement are required; 3. The ability to achieve three-dimensional structures is an advantage of 3D printing, but during the printing of three-dimensional structures, the ink may not solidify in time in the suspended area, resulting in collapse. Therefore, how to successfully print three-dimensional structures also requires careful design. Summary of the invention

[0005] The purpose of the present invention is to provide a thermoelectric device and a method for preparing the same, and to realize a new structure through different structural layers of 3D printing to improve the output performance of the thermoelectric structure. The thermoelectric material is configured into printable ink through the additive manufacturing method of direct ink writing by 3D printing, thereby avoiding the cumbersome process of traditional thermoelectric device manufacturing, and designing a sophisticated new structure, thereby solving the technical problems of application defects of traditional processes and material waste in the prior art.

[0006] In order to solve the above technical problems, the specific technical solutions of the present invention are as follows:

[0007] A method for preparing a thermoelectric device comprises the following steps:

[0008] Step S1: configuring raw materials for thermoelectric structure printing, wherein the raw materials for thermoelectric structure printing include support materials, N-type 3D printing thermoelectric ink, and P-type 3D printing thermoelectric ink;

[0009] Step S2: using the configured thermoelectric structure printing raw materials to print the thermoelectric structure using 3D printing ink direct writing technology; the thermoelectric structure includes a support structure, an N-type planar thermoelectric structure, a P-type thermoelectric planar structure, a three-dimensional N-type thermoelectric leg, a three-dimensional P-type thermoelectric leg and an electrode connection part;

[0010] Step S3: heat treating the 3D printed thermoelectric structure;

[0011] Step S4: configuring a thermal conductive material, and using the configured thermal conductive material to print a thermal conductive structure using a 3D printing ink direct writing technology;

[0012] Step S5: configuring a heat insulation material, and using the configured heat insulation material to print a heat insulation structure using a 3D printing ink direct writing technology;

[0013] Step S6: configuring a heat absorbing material, and using the configured heat absorbing material to print a heat absorbing structure using a 3D printing ink direct writing technology;

[0014] Step S7: configuring a reflective material, and using the configured reflective material to print a reflective structure using a 3D printing ink direct writing technology;

[0015] Step S8: Assemble the 3D printed thermoelectric structure, heat-conducting structure, heat-insulating structure, heat-absorbing structure and reflective material into a thermoelectric device.

[0016] Furthermore, step S1 includes the following steps:

[0017] Step S11: preparing the support material: uniformly mixing polydimethylsiloxane (PDMS1700) and a cross-linking agent at a mass ratio of 10:1 to obtain the support material; and transferring the support material to a barrel required for 3D printing;

[0018] Step S12: preparing epoxy resin base liquid: using 2-ethyl-4-methyl-1H-imidazole-1-propionitrile (EMIP) as a catalyst, accounting for 1% by mass; using polypropylene glycol diglycidyl ether (PPGDGE) and bisphenol F diglycidyl ether (BPFDGE) uniformly mixed in a mass ratio of 1:1 as liquid epoxy resin, accounting for 60.4% of the total mass; using methylhexahydrophthalic anhydride (MHHPA) as a curing agent, accounting for 38.6% by mass; uniformly mixing the catalyst, liquid epoxy resin and curing agent to obtain an epoxy resin base liquid;

[0019] Step S13: Configuring N-type 3D printed thermoelectric ink: using bismuth telluride Bi2Te 2.7 Se 0.3 As N-type thermoelectric powder, the mass ratio of N-type thermoelectric powder to epoxy resin base liquid is 5:1, and volatile diluent n-butyl acetate is added for dilution; a ball mill is used at a speed of 400r / min for 4 hours to mix the thermoelectric ink evenly to obtain N-type 3D printing thermoelectric ink; the N-type thermoelectric ink is transferred to the barrel required for 3D printing, and a vacuum stirring degassing machine is used for degassing;

[0020] Step S14: Prepare P-type 3D printing thermoelectric ink: use antimony telluride Sb2Te3 as P-type thermoelectric powder, make the mass ratio of P-type thermoelectric powder to epoxy resin base liquid 6:1, add volatile diluent n-butyl acetate to dilute; use a ball mill at a speed of 400r / min for 4h to mix the thermoelectric ink evenly to obtain P-type 3D printing thermoelectric ink; transfer the P-type thermoelectric ink to the barrel required for 3D printing, and use a vacuum stirring degassing machine for degassing.

[0021] Further, step S2 includes the following steps:

[0022] Step S21: On the glass substrate, 7 support structures are printed using support materials; the support structures are 35 mm long, 1.5 mm wide, and 1.3 mm high. The support structures are evenly printed on the glass substrate with a gap of 6 mm between the long sides;

[0023] Step S22: using N-type 3D printing thermoelectric ink to print an N-type planar thermoelectric structure; the length of the N-type planar thermoelectric structure is 6 mm, the width is 2 mm, and the height is 0.3 mm; the N-type planar thermoelectric structure is printed in the gap of the support structure, and the long side of the N-type planar thermoelectric structure is perpendicular to the long side of the support structure; perpendicular to the long side direction of the support structure, the N-type planar thermoelectric structure and the P-type thermoelectric planar structure are alternately printed in the gap of the support structure; parallel to the long side direction of the support structure, the N-type planar thermoelectric structure and the P-type thermoelectric planar structure are alternately printed in the gap of the support structure, and the N-type planar thermoelectric structure and the P-type thermoelectric planar structure are spaced by the width of the support structure, that is, 1.5 mm;

[0024] Step S23: using P-type 3D printing thermoelectric ink to print a P-type planar thermoelectric structure; the length of the P-type planar thermoelectric structure is 6 mm, the width is 2 mm, and the height is 0.3 mm; the P-type planar thermoelectric structure is printed in the gap of the support structure, and the long side of the P-type planar thermoelectric structure is perpendicular to the long side of the support structure; perpendicular to the long side direction of the support structure, the P-type planar thermoelectric structure and the N-type thermoelectric planar structure are alternately printed in the gap of the support structure; parallel to the long side direction of the support structure, the N-type planar thermoelectric structure and the P-type thermoelectric planar structure are alternately printed in the gap of the support structure;

[0025] Step S24: Print the N-type thermoelectric legs using N-type 3D printing thermoelectric ink; the length of the N-type thermoelectric legs is 2 mm, the width is 2 mm, and the height is 1 mm; the N-type thermoelectric legs are printed on the N-type planar thermoelectric structure or the P-type planar thermoelectric structure above the planar structure, close to the support structure, the N-type thermoelectric legs and the P-type thermoelectric legs are alternately printed on both sides of the support structure, and the P-type thermoelectric legs 22 and the N-type thermoelectric legs 23 in the gap of the support structure form a Π-type structure with the P-type planar thermoelectric structure 21 or the N-type planar thermoelectric structure 24 below

[0026] Step S25: Print the P-type thermoelectric legs using P-type 3D printing thermoelectric ink; the length, width and height of the N-type thermoelectric legs are 2 mm; the P-type thermoelectric legs are printed on the N-type planar thermoelectric structure or the P-type planar thermoelectric structure above the planar structure, close to the support structure, and the P-type thermoelectric legs and the N-type thermoelectric legs are alternately printed on both sides of the support structure;

[0027] Step S26: using N-type 3D printing thermoelectric ink to print the electrode connection part, the length of the electrode connection part is 5.5 mm, the width is 2 mm, and the height is 0.3 mm; the electrode connection part includes a top electrode and a bottom electrode; printing the top electrode above the support structure, so that the top electrode crosses the support structure, connecting the N-type thermoelectric legs and the P-type thermoelectric legs on both sides of the support structure, so that it forms a Π-type structure with the N-type thermoelectric legs and the P-type thermoelectric legs; printing the bottom electrode on the substrate, so that the bottom electrode connects the N-type planar thermoelectric structure and the P-type planar thermoelectric structure at the edge of each row to form a series connection;

[0028] Further, step S4 includes the following steps:

[0029] Step S41: The thermal conductive material is composed of polydimethylsiloxane (PDMS184) and boron nitride; polydimethylsiloxane (PDMS184) with a mass ratio of 70% and boron nitride with a mass ratio of 30% are mixed and stirred evenly to obtain a thermal conductive material, and the thermal conductive material is transferred to a barrel required for 3D printing;

[0030] Step S42: Use the configured thermal conductive material and adopt the 3D printing ink direct writing technology to print multiple rectangular thermal conductive structures with a length of 35 mm, a width of 6 mm, and a height of 2 mm; and perform a heat treatment at 70 degrees Celsius for 1 hour on the 3D printed rectangular thermal conductive structures.

[0031] Further, step S5 includes the following steps:

[0032] Step S51: The thermal insulation material is composed of silica aerogel and PVA aqueous solution. The silica aerogel particle size is 800 mesh, with a mass ratio of 10%, and the PVA aqueous solution has a mass ratio of 90%, wherein the PVA aqueous solution is 12.5% ​​by mass of PVA dissolved in water at 90 degrees Celsius; the silica aerogel and PVA aqueous solution are mixed and stirred evenly to obtain a thermal insulation material, and the thermal insulation material is transferred to the barrel required for 3D printing;

[0033] Step S52: Use the configured insulation material and adopt 3D printing ink direct writing technology to print multiple rectangular insulation structures with a length of 35 mm, a width of 6 mm, and a height of 2 mm; and heat treat the 3D printed rectangular insulation structures at 70 degrees Celsius for 1 hour.

[0034] Further, step S6 includes the following steps:

[0035] Step S61: The heat-absorbing material is composed of carbon black and polydimethylsiloxane (PDMS184), and the polydimethylsiloxane (PDMS184) is 91.5% by mass and the carbon black is 8.5% by mass. The mixed slurry is stirred evenly to obtain the heat-absorbing material, and the heat-absorbing material is transferred to the barrel required for 3D printing;

[0036] Step S62: Use the configured heat absorbing material and adopt 3D printing ink direct writing technology to print multiple rectangular heat absorbing structures with a length of 35 mm, a width of 6 mm, and a height of 0.3 mm; heat treat the 3D printed rectangular heat absorbing structures at 70 degrees Celsius for 1 hour.

[0037] Further, step S7 includes the following steps:

[0038] Step S71: the reflective material is composed of silica aerogel and PVA aqueous solution; wherein the silica aerogel particle size is 800 mesh, the mass proportion is 10%, the mass proportion of the PVA aqueous solution is 90%, and the PVA aqueous solution is 12.5% ​​by mass of PVA dissolved in water at 90 degrees Celsius; the silica aerogel and the PVA aqueous solution are mixed into a slurry and stirred evenly to obtain a reflective material, and the reflective material is transferred to a barrel required for 3D printing;

[0039] Step S72: Use the configured reflective material and adopt 3D printing ink direct writing technology to print multiple rectangular reflective structures with a length of 35 mm, a width of 6 mm, and a height of 0.3 mm; heat treat the 3D printed rectangular reflective structures at 70 degrees Celsius for 1 hour.

[0040] Further, step S8 includes the following steps:

[0041] The 3D printed heat-conducting structure and heat-insulating structure are placed alternately side by side, and the thermoelectric structure is placed above the heat-conducting structure and the heat-insulating structure; the heat-conducting structure and the heat-insulating structure are both located directly below the supporting structure; the heat-absorbing structure and the reflective structure are placed above the thermoelectric structure; the heat-absorbing structure and the reflective structure are placed alternately side by side, the heat-absorbing structure is connected to the top electrode of the thermoelectric structure, and the reflective structure is located at the gap between the top electrodes, so as to form a thermoelectric device.

[0042] In addition, the present invention also provides a thermoelectric device prepared by the method for preparing a thermoelectric device, wherein the thermoelectric device comprises a reflective and heat-absorbing layer, a thermoelectric structure, and a heat-conducting and heat-insulating layer.

[0043] Furthermore, the heat-conducting and heat-insulating layers are composed of a heat-conducting structure and a heat-insulating structure; a plurality of heat-conducting structures and a plurality of heat-insulating structures are alternately placed side by side in the long side direction;

[0044] The thermoelectric structure is composed of a P-type planar thermoelectric structure, a P-type thermoelectric leg, an N-type thermoelectric leg, an N-type planar thermoelectric structure, a support structure, a bottom electrode and a top electrode; a plurality of support structures are arranged side by side in a spaced manner in the long side direction, the length of the support structure is 35 mm, the width is 1.5 mm, the height is 1.3 mm, and the gap is 6 mm; the length of the P-type planar thermoelectric structure is 6 mm, the width is 2 mm, and the height is 0.3 mm; the length of the N-type planar thermoelectric structure is 6 mm, the width is 2 mm, and the height is 0.3 mm; the length of the P-type thermoelectric leg is 2 mm, the width is 2 mm, and the height is 1 mm; the length of the N-type thermoelectric leg is 2 mm, the width is 2 mm, and the height is 1 mm; the P-type planar thermoelectric structure and the N-type planar thermoelectric structure are alternately arranged in the gap of the support structure, and the long side widths of the P-type planar thermoelectric structure and the N-type planar thermoelectric structure are exactly equal to the gap width of the support structure; the long sides of the P-type planar thermoelectric structure and the N-type planar thermoelectric structure are perpendicular to the long sides of the support structure, and are arranged in several rows;

[0045] The P-type thermoelectric legs and the N-type thermoelectric legs are located above the N-type planar thermoelectric structure or the P-type planar thermoelectric structure, close to the support structure, the N-type thermoelectric legs and the P-type thermoelectric legs are alternately arranged on both sides of the support structure, and the P-type thermoelectric legs and the N-type thermoelectric legs in the gap of the support structure form a Π-type structure with the P-type planar thermoelectric structure or the N-type planar thermoelectric structure below;

[0046] The bottom electrode connects the edge N-type planar structure of each row with the P-type planar structure to form a series connection; the top electrode spans the support structure, connecting the P-type thermoelectric legs and the N-type thermoelectric legs on both sides of the support structure to form a Π-type structure with the N-type thermoelectric legs and the P-type thermoelectric legs;

[0047] A thermoelectric structure is placed above the heat-conducting and heat-insulating layers, so that the heat-conducting structure and the heat-insulating structure are both located directly below the supporting structure;

[0048] A reflective and heat-absorbing layer is placed above the thermoelectric structure; the reflective and heat-absorbing layer is composed of a heat-absorbing structure and a reflective structure, and multiple heat-absorbing structures and multiple reflective structures are placed alternately side by side; the heat-absorbing structure is connected to the top electrode of the thermoelectric structure, and the reflective structure is located at the interval between the two top electrodes.

[0049] Compared with the prior art, the present invention has the following beneficial technical effects:

[0050] 1) The present invention realizes the rapid preparation of thermoelectric devices using 3D printing ink direct writing technology, which solves the shortcomings of traditional manufacturing processes such as cumbersome operations, high waste of raw materials, and difficulty in manufacturing fine structures; 2) The structure of the heat-conducting layer and the heat-insulating layer designed in the present invention can transfer the planar temperature difference on one side of the skin to the hot end and the cold end of the thermoelectric device, establish a temperature difference on one side of the plane, and achieve the purpose of improving output; 3) The structure of the heat-absorbing layer and the reflective layer designed in the present invention can achieve the purpose of absorbing and reflecting sunlight, thereby increasing the temperature of the hot end of the thermoelectric device and reducing the temperature of the cold end, establishing a three-dimensional temperature difference, and achieving the purpose of improving output; 4) The overall structure of the present invention is combined to simultaneously establish a temperature difference based on one side of the skin plane, as well as a three-dimensional temperature difference for absorbing and reflecting sunlight, thereby achieving the purpose of achieving multi-stage temperature difference and improving the output performance of wearable thermoelectrics. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0052] Figure 1 This is the 3D-printed thermoelectric device of the present invention.

[0053] Figure 2 (a) is a printed image of the heat-conducting structure of the present invention, (b) is a printed image of the heat-insulating structure of the present invention, (c) is a printed image of the heat-absorbing structure of the present invention, and (d) is a printed image of the reflective structure of the present invention.

[0054] Figure 3This is a physical picture of the thermoelectric device printed by the present invention.

[0055] Figure 4 It is a schematic diagram of the overall structure of the thermoelectric device of the present invention.

[0056] Figure 5 It is a schematic diagram of the heat absorption structure and the reflection structure of the present invention.

[0057] Figure 6 Schematic diagram of the thermoelectric structure of the present invention.

[0058] Figure 7 It is a schematic diagram of the heat conducting structure and the heat insulating structure of the present invention.

[0059] Figure 8 Schematic diagram of a cross section of a thermoelectric device of the present invention.

[0060] Fig. 9 This is a schematic diagram of the temperature difference achieved by the thermoelectric device of the present invention and the current generated by the temperature difference.

[0061] Fig.10 This is the test data diagram of the heat absorption structure and the reflection structure.

[0062] Fig.11 This is the test data diagram of the thermal conductive structure and the thermal insulation structure.

[0063] Explanation of marks in the figure: 1. Reflection and heat absorption layer; 2. Thermoelectric structure; 3. Heat conduction and insulation layer; 11. Heat absorption structure; 12. Reflection structure; 21. P-type thermoelectric plane structure; 22. P-type thermoelectric leg; 23. N-type thermoelectric leg; 24. N-type thermoelectric plane structure; 25. Support structure; 26. Bottom electrode; 27. Top electrode; 31. Insulation structure; 32. Heat conduction structure. DETAILED DESCRIPTION

[0064] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0065] The present invention proposes a method for preparing a thermoelectric device, which prepares the thermoelectric device by printing different structural layers using multi-material collaborative 3D printing technology. The method comprises the following steps:

[0066] Step S1: configuring raw materials for thermoelectric structure printing, wherein the raw materials for thermoelectric structure printing include support material, N-type 3D printing thermoelectric ink, P-type 3D printing thermoelectric ink and epoxy resin base liquid.

[0067] Specifically, step S1 includes the following steps:

[0068] Step S11: preparing the support material: uniformly mixing polydimethylsiloxane (PDMS1700) and a cross-linking agent at a mass ratio of 10:1 to obtain the support material; and transferring the support material to a barrel required for 3D printing.

[0069] Step S12: preparing epoxy resin base liquid: using 2-ethyl-4-methyl-1H-imidazole-1-propionitrile (EMIP) as a catalyst, accounting for 1% by mass; using polypropylene glycol diglycidyl ether (PPGDGE) and bisphenol F diglycidyl ether (BPFDGE) uniformly mixed in a mass ratio of 1:1 as liquid epoxy resin, accounting for 60.4% by total mass; using methyl hexahydrophthalic anhydride (MHHPA) as a curing agent, accounting for 38.6% by mass. The catalyst, liquid epoxy resin and curing agent are uniformly mixed to obtain epoxy resin base liquid.

[0070] Step S13: Configuring N-type 3D printed thermoelectric ink: using bismuth telluride Bi2Te 2.7 Se 0.3 (particle size 1250 mesh) as N-type thermoelectric powder, make the mass ratio of N-type thermoelectric powder to epoxy resin base liquid 5:1, add volatile diluent n-butyl acetate to dilute. Use a ball mill at a speed of 400r / min for 4h to mix the thermoelectric ink evenly to obtain N-type 3D printing thermoelectric ink. Transfer the N-type thermoelectric ink to the barrel required for 3D printing, and use a vacuum stirring degassing machine for degassing.

[0071] Step S14: Prepare P-type 3D printing thermoelectric ink: Use antimony telluride Sb2Te3 (particle size 1250 mesh) as P-type thermoelectric powder, make the mass ratio of P-type thermoelectric powder to epoxy resin base liquid 6:1, and add volatile diluent n-butyl acetate to dilute. Use a ball mill at a speed of 400r / min for 4h to mix the thermoelectric ink evenly to obtain P-type 3D printing thermoelectric ink. Transfer the P-type thermoelectric ink to the barrel required for 3D printing, and use a vacuum stirring degassing machine for degassing.

[0072] Step S2: Use the configured thermoelectric structure printing raw materials to print the thermoelectric structure using 3D printing ink direct writing technology, such as Figure 1 As shown, the thermoelectric structure includes a supporting structure, an N-type planar thermoelectric structure, a P-type thermoelectric planar structure, a three-dimensional N-type thermoelectric leg, a three-dimensional P-type thermoelectric leg and an electrode connecting part.

[0073] Specifically, step S2 includes the following steps:

[0074] Step S21: On the glass substrate, 7 support structures are printed using support materials; the support structures are 35 mm long, 1.5 mm wide, and 1.3 mm high. The support structures are evenly printed on the glass substrate with a gap of 6 mm between the long sides.

[0075] Step S22: Use N-type 3D printing thermoelectric ink to print the N-type planar thermoelectric structure; the length of the N-type planar thermoelectric structure is 6mm, the width is 2mm, and the height is 0.3mm. The N-type planar thermoelectric structure is printed in the gap of the support structure, and the long side of the N-type planar thermoelectric structure is perpendicular to the long side of the support structure, and the length of the long side of the N-type planar thermoelectric structure is exactly equal to the gap of the support structure. Perpendicular to the long side direction of the support structure, the N-type planar thermoelectric structure and the P-type thermoelectric planar structure are printed alternately in the gap of the support structure. Parallel to the long side direction of the support structure, the N-type planar thermoelectric structure and the P-type thermoelectric planar structure are printed alternately in the gap of the support structure, and the N-type planar thermoelectric structure and the P-type thermoelectric planar structure are separated by the width of the support structure, that is, the interval is 1.5mm.

[0076] Step S23: Use P-type 3D printing thermoelectric ink to print a P-type planar thermoelectric structure; the length of the P-type planar thermoelectric structure is 6mm, the width is 2mm, and the height is 0.3mm. The P-type planar thermoelectric structure is printed in the gap of the support structure, and the long side of the P-type planar thermoelectric structure is perpendicular to the long side of the support structure, and the length of the long side of the P-type planar thermoelectric structure is exactly equal to the gap of the support structure. Perpendicular to the long side direction of the support structure, the P-type planar thermoelectric structure and the N-type thermoelectric planar structure are printed alternately in the gap of the support structure. Parallel to the long side direction of the support structure, the N-type planar thermoelectric structure and the P-type thermoelectric planar structure are printed alternately in the gap of the support structure.

[0077] In the long side direction of the vertical support structure and the long side direction of the parallel support structure, the printed N-type planar thermoelectric structures and P-type planar thermoelectric structures are combined into 8 rows each.

[0078] Step S24: Use N-type 3D printing thermoelectric ink to print N-type thermoelectric legs; the length of the N-type thermoelectric legs is 2 mm, the width is 2 mm, and the height is 1 mm. The N-type thermoelectric legs are printed above the N-type planar thermoelectric structure or the P-type planar thermoelectric structure, close to the supporting structure. The N-type thermoelectric legs and the P-type thermoelectric legs are alternately printed on both sides of the supporting structure. The P-type thermoelectric legs 22 and the N-type thermoelectric legs 23 in the gap of the supporting structure form a Π-type structure with the P-type planar thermoelectric structure 21 or the N-type planar thermoelectric structure 24 below.

[0079] Step S25: Use P-type 3D printing thermoelectric ink to print P-type thermoelectric legs; the length of the N-type thermoelectric legs is 2 mm, the width is 2 mm, and the height is 1 mm. The P-type thermoelectric legs are printed on the N-type planar thermoelectric structure or the P-type planar thermoelectric structure above the planar structure, close to the supporting structure, and the P-type thermoelectric legs and the N-type thermoelectric legs are alternately printed on both sides of the supporting structure. The P-type thermoelectric legs 22 and the N-type thermoelectric legs 23 in the gap of the supporting structure form a Π-type structure with the P-type planar thermoelectric structure 21 or the N-type planar thermoelectric structure 24 below.

[0080] Step S26: Use N-type 3D printing thermoelectric ink to print the electrode connection part, the electrode connection part includes a top electrode and a bottom electrode, and the length of the electrode connection part is 5.5mm, the width is 2mm, and the height is 0.3mm. The electrode connection part connects the N-type planar thermoelectric structure and the P-type planar thermoelectric structure. Print the top electrode above the support structure so that the top electrode spans the support structure, connects the N-type thermoelectric legs and the P-type thermoelectric legs on both sides of the support structure, and forms a Π-type structure with the N-type thermoelectric legs and the P-type thermoelectric legs. Print the bottom electrode on the substrate so that the bottom electrode connects the N-type planar thermoelectric structure and the P-type planar thermoelectric structure at the edge of each row to form a series connection.

[0081] Step S3: performing heat treatment on the 3D printed thermoelectric structure.

[0082] Specifically, the 3D printed thermoelectric structure was first pretreated at 120 degrees Celsius for 2 hours, and then heat treated at 350 degrees Celsius for 4 hours in a nitrogen environment using a muffle furnace.

[0083] Step S4: configuring a thermal conductive material, and using the configured thermal conductive material to print a thermal conductive structure using a 3D printing ink direct writing technology.

[0084] Specifically, step S41: the thermal conductive material is composed of polydimethylsiloxane (PDMS184) and boron nitride. The polydimethylsiloxane (PDMS184) is 70% by mass, and the boron nitride is 30% by mass. The mixed slurry is stirred evenly to obtain the thermal conductive material, and the thermal conductive material is transferred to the barrel required for 3D printing.

[0085] Step S42: Use the configured thermal conductive material and adopt 3D printing ink direct writing technology to print multiple rectangular thermal conductive structures with a length of 35 mm, a width of 6 mm, and a height of 2 mm, such as Figure 2 (a) shows that the 3D printed rectangular thermal conductive structure was heat treated at 70 degrees Celsius for 1 hour.

[0086] Step S5: configuring thermal insulation materials, and using the configured thermal insulation materials to print a thermal insulation structure using 3D printing ink direct writing technology.

[0087] Specifically, step S51: the thermal insulation material is composed of silica aerogel and PVA aqueous solution. The silica aerogel particle size is 800 mesh, the mass ratio is 10%, and the mass ratio of the PVA aqueous solution is 90%, wherein the PVA aqueous solution is 12.5% ​​by mass of PVA dissolved in water at 90 degrees Celsius. The silica aerogel and PVA aqueous solution are mixed and stirred evenly to obtain a thermal insulation material, and the thermal insulation material is transferred to the barrel required for 3D printing.

[0088] Step S52: Use the configured insulation material and adopt 3D printing ink direct writing technology to print multiple rectangular insulation structures with a length of 35 mm, a width of 6 mm, and a height of 2 mm, such as Figure 2 (b) The 3D printed rectangular thermal insulation structure was heat treated at 70 degrees Celsius for 1 hour.

[0089] Step S6: configuring a heat absorbing material, and using the configured heat absorbing material to print a heat absorbing structure using a 3D printing ink direct writing technology.

[0090] Specifically, step S61: the heat-absorbing material is composed of carbon black and polydimethylsiloxane (PDMS184), and the mixed slurry of polydimethylsiloxane (PDMS184) with a mass proportion of 91.5% and carbon black with a mass proportion of 8.5% is stirred evenly to obtain the heat-absorbing material, and the heat-absorbing material is transferred to the barrel required for 3D printing.

[0091] Step S62: Use the configured heat absorbing material and adopt 3D printing ink direct writing technology to print multiple rectangular heat absorbing structures with a length of 35 mm, a width of 6 mm, and a height of 0.3 mm, such as Figure 2 (c) The 3D printed rectangular heat-absorbing structure was heat treated at 70 degrees Celsius for 1 hour.

[0092] Step S7: configuring a reflective material, and using the configured reflective material to print a reflective structure using a 3D printing ink direct writing technology.

[0093] Specifically, step S71: the reflective material is composed of silica aerogel and PVA aqueous solution; wherein the silica aerogel particle size is 800 mesh, the mass ratio is 10%, the mass ratio of the PVA aqueous solution is 90%, and the PVA aqueous solution is 12.5% ​​by mass of PVA dissolved in water at 90 degrees Celsius. The silica aerogel and PVA aqueous solution are mixed into a slurry and stirred evenly to obtain a reflective material, and the reflective material is transferred to a barrel required for 3D printing.

[0094] Step S72: Use the configured reflective material and adopt 3D printing ink direct writing technology to print multiple cuboid reflective structures with a length of 35 mm, a width of 6 mm, and a height of 0.3 mm, such as Figure 2As shown in (d), the 3D printed cuboid reflective structure was heat treated at 70 degrees Celsius for 1 hour.

[0095] Step S8: Assemble the 3D printed thermoelectric structure, heat-conducting structure, heat-insulating structure, heat-absorbing structure and reflective material into a thermoelectric device.

[0096] Specifically, the 3D printed heat-conducting structure and heat-insulating structure are placed alternately side by side, and the thermoelectric structure is placed above the heat-conducting structure and the heat-insulating structure. The heat-conducting structure and the heat-insulating structure are both located directly below the support structure. A heat-absorbing structure and a reflective structure are placed above the thermoelectric structure; the heat-absorbing structure and the reflective structure are placed alternately side by side, the heat-absorbing structure is connected to the top electrode of the thermoelectric structure, and the reflective structure is located at the interval of the top electrode to form a thermoelectric device. The actual picture of the thermoelectric device is shown in the figure below. Figure 3 .

[0097] The present invention also provides a thermoelectric device prepared by the above-mentioned thermoelectric device preparation method, such as Figure 4-7 As shown, the thermoelectric device includes a reflective and heat-absorbing layer 1 , a thermoelectric structure 2 and a heat-conducting and heat-insulating layer 3 .

[0098] The heat conducting and heat insulating layer 3 is composed of a heat conducting structure 32 and a heat insulating structure 31. A plurality of heat conducting structures 32 and a plurality of heat insulating structures 31 are alternately placed side by side in the long side direction.

[0099] The thermoelectric structure 2 is composed of a P-type planar thermoelectric structure 21, a P-type thermoelectric leg 22, an N-type thermoelectric leg 23, an N-type planar thermoelectric structure 24, a support structure 25, a bottom electrode 26 and a top electrode 27. Multiple support structures are placed side by side in the long side direction, the support structure 25 is 35 mm long, 1.5 mm wide, 1.3 mm high, and 6 mm in gap; the P-type planar thermoelectric structure 21 is 6 mm long, 2 mm wide, and 0.3 mm high; the N-type planar thermoelectric structure 24 is 6 mm long, 2 mm wide, and 0.3 mm high; the P-type thermoelectric leg 22 is 2 mm long, 2 mm wide, and 1 mm high; the N-type thermoelectric leg 23 is 2 mm long, 2 mm wide, and 1 mm high. The P-type planar thermoelectric structures 21 and the N-type planar thermoelectric structures 24 are alternately arranged in the gap of the support structure 25, and the long side widths of the P-type planar thermoelectric structures 21 and the N-type planar thermoelectric structures 24 are exactly equal to the gap width of the support structure; the long sides of the P-type planar thermoelectric structures 21 and the N-type planar thermoelectric structures 24 are perpendicular to the long sides of the support structure 25, and are arranged in several rows.

[0100] The P-type thermoelectric leg 22 and the N-type thermoelectric leg 23 are located above the N-type planar thermoelectric structure or the P-type planar thermoelectric structure, close to the supporting structure, and the N-type thermoelectric leg and the P-type thermoelectric leg are alternately arranged on both sides of the supporting structure. The P-type thermoelectric leg 22 and the N-type thermoelectric leg 23 in the gap of the supporting structure form a Π-type structure with the P-type planar thermoelectric structure 21 or the N-type planar thermoelectric structure 24 below.

[0101] The bottom electrode 26 connects the edge N-type planar structure and the P-type planar structure of each row to form a series connection; the top electrode 27 spans the support structure, connecting the P-type thermoelectric leg 22 and the N-type thermoelectric leg 23 on both sides of the support structure to form a Π-type structure with the N-type thermoelectric leg and the P-type thermoelectric leg.

[0102] The thermoelectric structure 2 is placed above the heat-conducting and heat-insulating layer 3, so that the heat-conducting structure and the heat-insulating structure are both located directly below the supporting structure.

[0103] A reflective and heat absorbing layer 1 is placed above the thermoelectric structure 2. The reflective and heat absorbing layer 1 is composed of a heat absorbing structure 11 and a reflective structure 12, and a plurality of heat absorbing structures 11 and a plurality of reflective structures 12 are placed alternately side by side. The heat absorbing structure 11 is connected to the top electrode 27 of the thermoelectric structure, and the reflective structure 12 is located at the interval between the two top electrodes.

[0104] Further, Figure 8 The cross-sectional diagram of the thermoelectric device shows the connection relationship between the various parts. The heat absorption structure 11 can absorb sunlight to increase the temperature of the hot end, the reflection structure 12 can reflect sunlight to reduce the temperature of the cold end, the insulation structure 31 can isolate part of the temperature conduction, and the heat conduction structure 32 can conduct the temperature to achieve the purpose of temperature difference. The temperature difference and current diagram of the thermoelectric device is shown in the figure. Fig. 9 As shown, according to the principle of thermoelectric power generation, the majority carriers in N-type thermoelectric and P-type thermoelectric materials will move from high temperature to low temperature, and the temperature difference formed by the thermoelectric device can form the following Fig. 9 Continuous current.

[0105] In order to verify the function of the thermoelectric device, the performance tests of each structure will be carried out as follows:

[0106] To test the performance of the printed heat-absorbing and reflective structures, we used a solar simulated light source to irradiate the heat-absorbing and reflective structures under a certain sunlight intensity, and placed temperature sensors under the heat-absorbing and reflective structures to test their temperature changes. The test results are as follows: Fig.10 As shown, the results show that the heat-absorbing structure can absorb sunlight to increase the temperature, and the reflective structure can reflect sunlight to lower the temperature. The combination of the two can achieve a temperature difference.

[0107] The performance test of the printed thermal insulation structure and thermal conductive structure was carried out by using a heating plate to test the thermal insulation structure and thermal conductive structure from room temperature to 70 degrees Celsius, and placing temperature sensors on the thermal insulation structure and thermal conductive structure to test their temperature changes. The test results are as follows: Fig.11 As shown, the results show that the thermal insulation structure can realize the function of suppressing temperature, the thermal conductive structure can realize the energy supply of temperature transmission, and the combination of the two can realize the temperature difference.

[0108] In the performance test of the planar printed thermoelectric device, the printed thermoelectric structure was placed on a heating table with a temperature of 37 degrees Celsius; then the printed thermal conductive structure, thermal insulation structure, heat absorbing structure and reflective structure were added, and a solar simulated light source was used to irradiate with a sunlight intensity, producing a maximum output of 22mV. Due to heat diffusion, the output slowly decreased over time. In contrast, when the planar thermoelectric structure is directly heated, the thermal conductive structure, heat absorbing structure, heat absorbing structure and reflective structure are not added. Since there is no temperature difference between the cold end and the hot end, the output is zero. Therefore, the above results prove that adding this structure can produce multiple temperature differences, which can be used to increase the thermoelectric output.

[0109] For the performance test of the three-dimensional printed thermoelectric device, the printed thermoelectric structure was placed on a heating table with a temperature of 37 degrees Celsius. Then, a thermal conductive structure and a thermal insulating structure were added, and the test output was 25.9mV. A heat absorbing structure and a reflective structure were added, and a solar energy simulation light source was used for irradiation with strong sunlight. The output voltage was 70.1mV, indicating that this design structure can achieve multiple temperature differences and achieve the function of improving the thermoelectric output performance.

[0110] The above test results show that the present invention realizes the rapid preparation of 3D printing of thermoelectric devices, and the heat insulation structure and the heat conduction structure establish a temperature difference by isolating the temperature to the cold end of the thermoelectric device and conducting the temperature to the hot end of the thermoelectric device, thereby improving the output performance of the thermoelectric device, while the heat absorption structure and the reflective structure establish a temperature difference by absorbing sunlight to the hot end of the thermoelectric device and reflecting sunlight to the cold end of the thermoelectric generator, thereby improving the output performance of the thermoelectric device.

[0111] The thermoelectric device prepared by the present invention can be used to improve the output performance of wearable thermoelectric generators. It is made through 3D printing technology, which simplifies the operation process and reduces the waste of raw materials. In addition, a unique structure of the thermoelectric device is designed, and a temperature difference on the skin side can be established through a heat-conducting structure and a heat-insulating structure. The heat-absorbing structure and the reflective structure can increase the temperature difference between the skin side and the ambient side, thereby achieving the purpose of improving the output performance of the thermoelectric generator. It can be used to supply energy to wearable sensing equipment, realize a self-powered wearable sensing system, and reduce its dependence on batteries.

[0112] It is to be understood that the present invention is described by some embodiments, and it is known to those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the scope of protection of the present invention.

Claims

1. A method for preparing a thermoelectric device, characterized in that: The steps include: Step S1: configuring raw materials for thermoelectric structure printing, wherein the raw materials for thermoelectric structure printing include support materials, N-type 3D printing thermoelectric ink, and P-type 3D printing thermoelectric ink; Step S2: using the configured thermoelectric structure printing raw materials to print the thermoelectric structure using 3D printing ink direct writing technology; the thermoelectric structure includes a support structure, an N-type planar thermoelectric structure, a P-type thermoelectric planar structure, a three-dimensional N-type thermoelectric leg, a three-dimensional P-type thermoelectric leg and an electrode connection part; Step S3: heat treating the 3D printed thermoelectric structure; Step S4: configuring a thermal conductive material, and using the configured thermal conductive material to print a thermal conductive structure using a 3D printing ink direct writing technology; Step S5: configuring a heat insulation material, and using the configured heat insulation material to print a heat insulation structure using a 3D printing ink direct writing technology; Step S6: configuring a heat absorbing material, and using the configured heat absorbing material to print a heat absorbing structure using a 3D printing ink direct writing technology; Step S7: configuring a reflective material, and using the configured reflective material to print a reflective structure using a 3D printing ink direct writing technology; Step S8: Assemble the 3D printed thermoelectric structure, heat-conducting structure, heat-insulating structure, heat-absorbing structure and reflective material into a thermoelectric device.

2. The method for preparing a thermoelectric device according to claim 1, characterized in that: Step S1 includes the following steps: Step S11: preparing the support material: uniformly mixing polydimethylsiloxane (PDMS1700) and a cross-linking agent at a mass ratio of 10:1 to obtain the support material; and transferring the support material to a barrel required for 3D printing; Step S12: preparing epoxy resin base liquid: using 2-ethyl-4-methyl-1H-imidazole-1-propionitrile (EMIP) as a catalyst, accounting for 1% by mass; using polypropylene glycol diglycidyl ether (PPGDGE) and bisphenol F diglycidyl ether (BPFDGE) uniformly mixed in a mass ratio of 1:1 as liquid epoxy resin, accounting for 60.4% of the total mass; using methylhexahydrophthalic anhydride (MHHPA) as a curing agent, accounting for 38.6% by mass; uniformly mixing the catalyst, liquid epoxy resin and curing agent to obtain an epoxy resin base liquid; Step S13: Configuring N-type 3D printed thermoelectric ink: using bismuth telluride Bi2Te 2.7 Se 0.3 As N-type thermoelectric powder, the mass ratio of N-type thermoelectric powder to epoxy resin base liquid is 5:1, and volatile diluent n-butyl acetate is added for dilution; a ball mill is used at a speed of 400r / min for 4 hours to mix the thermoelectric ink evenly to obtain N-type 3D printing thermoelectric ink; the N-type thermoelectric ink is transferred to the barrel required for 3D printing, and a vacuum stirring degassing machine is used for degassing; Step S14: Prepare P-type 3D printing thermoelectric ink: use antimony telluride Sb2Te3 as P-type thermoelectric powder, make the mass ratio of P-type thermoelectric powder to epoxy resin base liquid 6:1, add volatile diluent n-butyl acetate to dilute; use a ball mill at a speed of 400r / min for 4h to mix the thermoelectric ink evenly to obtain P-type 3D printing thermoelectric ink; transfer the P-type thermoelectric ink to the barrel required for 3D printing, and use a vacuum stirring degassing machine for degassing.

3. The method for preparing a thermoelectric device according to claim 1, characterized in that: Step S2 includes the following steps: Step S21: Printing a support structure on a glass substrate using a support material; the support structure is 35 mm long, 1.5 mm wide, and 1.3 mm high; the support structure is evenly printed on the glass substrate with a gap of 6 mm between the long sides; Step S22: using N-type 3D printing thermoelectric ink to print an N-type planar thermoelectric structure; the length of the N-type planar thermoelectric structure is 6 mm, the width is 2 mm, and the height is 0.3 mm; the N-type planar thermoelectric structure is printed in the gap of the support structure, and the long side of the N-type planar thermoelectric structure is perpendicular to the long side of the support structure; In the long side direction of the vertical support structure, the N-type planar thermoelectric structure and the P-type planar thermoelectric structure are alternately printed in the gap of the support structure; In the direction of the long side of the support structure, the N-type planar thermoelectric structure and the P-type planar thermoelectric structure are alternately printed in the gap between the support structures, and the interval between the N-type planar thermoelectric structure and the P-type planar thermoelectric structure is the width of the support structure, that is, the interval is 1.5 mm; Step S23: using P-type 3D printing thermoelectric ink to print a P-type planar thermoelectric structure; the length of the P-type planar thermoelectric structure is 6 mm, the width is 2 mm, and the height is 0.3 mm; the P-type planar thermoelectric structure is printed in the gap of the support structure, and the long side of the P-type planar thermoelectric structure is perpendicular to the long side of the support structure; In the direction perpendicular to the long side of the support structure, the P-type planar thermoelectric structure and the N-type planar thermoelectric structure are alternately printed in the gap between the support structures; in the direction parallel to the long side of the support structure, the N-type planar thermoelectric structure and the P-type planar thermoelectric structure are alternately printed in the gap between the support structures; Step S24: using N-type 3D printing thermoelectric ink to print N-type thermoelectric legs; the length of the N-type thermoelectric legs is 2 mm, the width is 2 mm, and the height is 1 mm; the N-type thermoelectric legs are printed above the N-type planar thermoelectric structure or the P-type planar thermoelectric structure, close to the support structure, the N-type thermoelectric legs and the P-type thermoelectric legs are alternately printed on both sides of the support structure, and the P-type thermoelectric legs (22) and the N-type thermoelectric legs (23) in the gap of the support structure form a Π-type structure with the P-type planar thermoelectric structure (21) or the N-type planar thermoelectric structure (24) below; Step S25: Print the P-type thermoelectric legs using P-type 3D printing thermoelectric ink; the length, width and height of the N-type thermoelectric legs are 2 mm; the P-type thermoelectric legs are printed on the N-type planar thermoelectric structure or the P-type planar thermoelectric structure above the planar structure, close to the support structure, and the P-type thermoelectric legs and the N-type thermoelectric legs are alternately printed on both sides of the support structure; Step S26: Use N-type 3D printed thermoelectric ink to print the electrode connection part, the length of the electrode connection part is 5.5 mm, the width is 2 mm, and the height is 0.3 mm; the electrode connection part includes a top electrode and a bottom electrode; print the top electrode above the support structure so that the top electrode spans the support structure and connects the N-type thermoelectric legs and the P-type thermoelectric legs on both sides of the support structure to form a Π-type structure with the N-type thermoelectric legs and the P-type thermoelectric legs; print the bottom electrode on the substrate so that the bottom electrode connects the N-type planar thermoelectric structure and the P-type planar thermoelectric structure at the edge of each row to form a series connection.

4. The method for preparing a thermoelectric device according to claim 1, characterized in that: Step S4 includes the following steps: Step S41: The thermal conductive material is composed of polydimethylsiloxane (PDMS184) and boron nitride; polydimethylsiloxane (PDMS184) with a mass ratio of 70% and boron nitride with a mass ratio of 30% are mixed and stirred evenly to obtain a thermal conductive material, and the thermal conductive material is transferred to a barrel required for 3D printing; Step S42: Use the configured thermal conductive material and adopt the 3D printing ink direct writing technology to print multiple rectangular thermal conductive structures with a length of 35 mm, a width of 6 mm, and a height of 2 mm; and perform a heat treatment at 70 degrees Celsius for 1 hour on the 3D printed rectangular thermal conductive structures.

5. The method for preparing a thermoelectric device according to claim 1, characterized in that: Step S5 includes the following steps: Step S51: The thermal insulation material is composed of silica aerogel and PVA aqueous solution; the silica aerogel particle size is 800 mesh, the mass ratio is 10%, and the mass ratio of the PVA aqueous solution is 90%, wherein the PVA aqueous solution is 12.5% ​​by mass of PVA dissolved in water at 90 degrees Celsius; the silica aerogel and PVA aqueous solution are mixed and stirred evenly to obtain a thermal insulation material, and the thermal insulation material is transferred to a barrel required for 3D printing; Step S52: Use the configured insulation material and adopt 3D printing ink direct writing technology to print multiple rectangular insulation structures with a length of 35 mm, a width of 6 mm, and a height of 2 mm; heat treat the 3D printed rectangular insulation structures at 70 degrees Celsius for 1 hour.

6. The method for preparing a thermoelectric device according to claim 1, characterized in that: Step S6 includes the following steps: Step S61: The heat-absorbing material is composed of carbon black and polydimethylsiloxane (PDMS184), and the polydimethylsiloxane (PDMS184) is 91.5% by mass and the carbon black is 8.5% by mass. The mixed slurry is stirred evenly to obtain the heat-absorbing material, and the heat-absorbing material is transferred to the barrel required for 3D printing; Step S62: Use the configured heat absorbing material and adopt 3D printing ink direct writing technology to print multiple rectangular heat absorbing structures with a length of 35 mm, a width of 6 mm, and a height of 0.3 mm; heat treat the 3D printed rectangular heat absorbing structures at 70 degrees Celsius for 1 hour.

7. The method for preparing a thermoelectric device according to claim 1, characterized in that: Step S7 includes the following steps: Step S71: the reflective material is composed of silica aerogel and PVA aqueous solution; wherein the silica aerogel particle size is 800 mesh, the mass proportion is 10%, the mass proportion of the PVA aqueous solution is 90%, and the PVA aqueous solution is 12.5% ​​by mass of PVA dissolved in water at 90 degrees Celsius; the silica aerogel and the PVA aqueous solution are mixed into a slurry and stirred evenly to obtain a reflective material, and the reflective material is transferred to a barrel required for 3D printing; Step S72: Use the configured reflective material and adopt 3D printing ink direct writing technology to print multiple rectangular reflective structures with a length of 35 mm, a width of 6 mm, and a height of 0.3 mm; heat treat the 3D printed rectangular reflective structures at 70 degrees Celsius for 1 hour.

8. The method for preparing a thermoelectric device according to claim 1, characterized in that: Step S8 includes the following steps: Place the 3D printed heat-conducting structure and heat-insulating structure side by side and alternately, and place the thermoelectric structure above the heat-conducting structure and the heat-insulating structure; make sure that the heat-conducting structure and the heat-insulating structure are both located directly below the support structure; A heat absorbing structure and a reflective structure are placed above the thermoelectric structure; the heat absorbing structure and the reflective structure are placed alternately side by side, the heat absorbing structure is connected to the top electrode of the thermoelectric structure, and the reflective structure is located at the interval of the top electrode to form a thermoelectric device.

9. A thermoelectric device, characterized in that: The thermoelectric device is prepared by the method for preparing a thermoelectric device according to any one of claims 1 to 8, and comprises a reflective and heat-absorbing layer (1), a thermoelectric structure (2) and a heat-conducting and heat-insulating layer (3).

10. The thermoelectric device according to claim 9, characterized in that The heat-conducting and heat-insulating layer (3) is composed of a heat-conducting structure (32) and a heat-insulating structure (31); a plurality of heat-conducting structures (32) and a plurality of heat-insulating structures (31) are alternately arranged side by side in the long side direction; The thermoelectric structure (2) is composed of a P-type planar thermoelectric structure (21), a P-type thermoelectric leg (22), an N-type thermoelectric leg (23), an N-type planar thermoelectric structure (24), a support structure (25), a bottom electrode (26) and a top electrode (27); the plurality of support structures are arranged side by side and spaced apart in the long side direction, the support structure (25) is 35 mm long, 1.5 mm wide, 1.3 mm high and has a gap of 6 mm; the P-type planar thermoelectric structure (21) is 6 mm long, 2 mm wide and 0.3 mm high; the N-type planar thermoelectric structure (24) is 6 mm long, 2 mm wide and 1.3 mm high 0.3mm; the length of the P-type thermoelectric leg (22) is 2mm, the width is 2mm, and the height is 1mm; the length of the N-type thermoelectric leg (23) is 2mm, the width is 2mm, and the height is 1mm; the P-type planar thermoelectric structure (21) and the N-type planar thermoelectric structure (24) are alternately arranged in the gap of the support structure (25), and the long side widths of the P-type planar thermoelectric structure (21) and the N-type planar thermoelectric structure (24) are exactly equal to the gap width of the support structure; the long sides of the P-type planar thermoelectric structure (21) and the N-type planar thermoelectric structure (24) are perpendicular to the long sides of the support structure (25), and are arranged in several rows; The P-type thermoelectric legs (22) and the N-type thermoelectric legs (23) are located above the N-type planar thermoelectric structure or the P-type planar thermoelectric structure, close to the support structure, the N-type thermoelectric legs and the P-type thermoelectric legs are alternately arranged on both sides of the support structure, and the P-type thermoelectric legs (22) and the N-type thermoelectric legs (23) in the gap of the support structure form a Π-type structure with the P-type planar thermoelectric structure (21) or the N-type planar thermoelectric structure (24) below; The bottom electrode (26) connects the edge N-type planar structure and the P-type planar structure of each row to form a series connection; the top electrode (27) spans the support structure and connects the P-type thermoelectric legs (22) and the N-type thermoelectric legs (23) on both sides of the support structure to form a Π-type structure with the N-type thermoelectric legs and the P-type thermoelectric legs; A thermoelectric structure (2) is placed above the heat-conducting and heat-insulating layer (3), so that the heat-conducting structure and the heat-insulating structure are both located directly below the supporting structure; A reflective and heat-absorbing layer (1) is placed above the thermoelectric structure (2); the reflective and heat-absorbing layer (1) is composed of a heat-absorbing structure (11) and a reflective structure (12), and a plurality of heat-absorbing structures (11) and a plurality of reflective structures (12) are placed alternately side by side; the heat-absorbing structure (11) is connected to the top electrode (27) of the thermoelectric structure, and the reflective structure (12) is located at the interval between the two top electrodes.

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