A three-dimensional thermoelectric device based on double-sided screen printing and its preparation method

Abstract

The present invention discloses a three-dimensional thermoelectric device based on double-sided screen printing and a preparation method thereof, which belongs to the field of new energy device technology. The device is obtained by folding a two-dimensional layout structure multiple times. The two-dimensional layout structure is a double-sided structure prepared by using a screen printing process on a substrate. Each side structure includes a bottom electrode layer, an N-type thermoelectric material layer, a P-type thermoelectric material layer and a top electrode layer in sequence, all of which are array structures; the N-type thermoelectric legs and the P-type thermoelectric legs are alternately arranged, and the N-type thermoelectric legs, the P-type thermoelectric legs and the top electrode unit structure all have overlapping areas with the bottom electrode units; through multiple folding, the two-dimensional layout structure is folded into a three-dimensional thermoelectric device, which can realize three-dimensional collection of heat flow and make full use of the limited substrate area. It has the advantages of high output power density, compact structure, high integration and small occupied area, and is particularly suitable for wearable scenarios.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy devices, and in particular relates to a three-dimensional thermoelectric device based on double-sided screen printing and a preparation method thereof. Background Art

[0002] Thermoelectric devices convert industrial and domestic waste heat into electrical energy through the Seebeck effect. They have the advantages of requiring no mechanical input, no light restrictions, and no user intervention. Therefore, they are generally more stable and reliable and are an effective solution to alleviate energy and environmental problems.

[0003] In recent years, the rapid development of micro- and nanofabrication technologies has driven the miniaturization, multifunctionality, and integration of electronic products, reducing power consumption from milliwatts (mW) to microwatts (μW) and even nanowatts (nW). Even with conversion efficiency below 1%, the temperature difference between the human body and the environment is sufficient to drive thermoelectric devices to generate electricity, powering a variety of electronic devices. Thermoelectric devices have the potential to replace batteries as efficient power sources in wearable applications, avoiding the application limitations caused by frequent charging, regular maintenance and replacement, and environmental pollution.

[0004] Many flexible film-based thermoelectric devices are designed as planar structures, with thermoelectric legs and metal interconnects placed on a flexible substrate to collect in-plane heat flow. However, this in-plane heat collection configuration does not align with the direction of heat flow between the human body and the environment (i.e., perpendicular to the plane), making it ineffective in collecting body heat. Furthermore, the temperature difference between body temperature and the environment is small, resulting in a low output of thermoelectric devices.

[0005] Therefore, it is necessary to propose a highly integrated thermoelectric device that can collect heat flow between the human body and the environment to provide new ideas for wearable scenarios. Summary of the Invention

[0006] In response to the problem that existing planar thermoelectric devices cannot effectively collect body heat, the present invention provides a three-dimensional thermoelectric device based on double-sided screen printing and a preparation method thereof. Multiple folding is used to obtain a highly integrated three-dimensional thermoelectric device, which realizes three-dimensional collection of heat flow and is particularly suitable for wearable scenarios.

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

[0008] A three-dimensional thermoelectric device based on double-sided screen printing is obtained by folding a two-dimensional layout structure multiple times; the two-dimensional layout structure is a double-sided structure prepared by a screen printing process on a substrate, with the structures on both sides being identical, and each side structure including, in order, a bottom electrode layer, an N-type thermoelectric material layer, a P-type thermoelectric material layer, and a top electrode layer;

[0009] The bottom electrode layer is an array of 4m×2n isolated bottom electrode units; the N-type thermoelectric material layer is an array of m×n isolated N-type thermoelectric legs; the P-type thermoelectric material layer is an array of m×n isolated P-type thermoelectric legs; the top electrode layer is an array of (2m+1)×2n isolated top electrode units;

[0010] The N-type thermoelectric legs and the P-type thermoelectric legs are alternately arranged to form a 2m×2n double-grid structure array; in each row of the double-grid structure array, two sides of the N-type thermoelectric legs respectively have overlapping regions with two bottom electrode units, and two sides of the P-type thermoelectric legs respectively have overlapping regions with two bottom electrode units. The top electrode unit is located in the area between the adjacent N-type thermoelectric legs and the P-type thermoelectric legs, and has overlapping regions with the N-type thermoelectric legs and the P-type thermoelectric legs. There is also an overlapping region with the bottom electrode unit overlapping one side of the N-type thermoelectric leg, and there is an overlapping region with the bottom electrode unit overlapping one side of the P-type thermoelectric leg, so that the adjacent N-type thermoelectric legs and P-type thermoelectric legs in each row are electrically interconnected;

[0011] The top electrode units in adjacent rows in the top electrode layer are connected end to end, thereby forming an electrical interconnection area with a serpentine structure in each side structure;

[0012] By folding multiple times, the two-dimensional layout structure is folded into a three-dimensional thermoelectric device formed by stacking 2m×2n layers of thermoelectric units. Each layer of thermoelectric units contains an N-type thermoelectric leg or a P-type thermoelectric leg.

[0013] Furthermore, the substrate is a polyimide film with a thickness of 15 to 50 μm; and the materials of the bottom electrode layer and the top electrode layer are silver.

[0014] Furthermore, electrical interconnection of the double-sided structure is achieved by providing through holes in the top electrode layer.

[0015] Furthermore, during the multiple folding processes, polyimide films are introduced to insulate adjacent layers of thermoelectric units.

[0016] Furthermore, by changing the area of ​​the overlapping region between the N-type thermoelectric leg and the bottom electrode unit, as well as the area of ​​the overlapping region between the P-type thermoelectric leg and the bottom electrode unit, the contact resistance between the bottom electrode layer and the N-type thermoelectric material layer and the P-type thermoelectric material layer is adjusted, thereby adjusting the internal resistance of the three-dimensional thermoelectric device.

[0017] Furthermore, m and n are both positive integers.

[0018] The method for preparing a three-dimensional thermoelectric device based on double-sided screen printing comprises the following steps:

[0019] Step 1: preparing a thermoelectric ink base liquid, and preparing an N-type thermoelectric ink and a P-type thermoelectric ink based on the thermoelectric ink base liquid;

[0020] Step 2: Pre-drill through holes on the substrate;

[0021] Step 3: Place a screen with a bottom electrode unit pattern on both sides of the substrate, and use a screen printing process to print a conductive silver paste on both sides of the substrate, and pre-curing to obtain a bottom electrode layer;

[0022] Step 4: Place a screen with a P-type thermoelectric leg pattern on both sides of the substrate treated in step 3, and use a screen printing process to print P-type thermoelectric ink on the bottom electrode layer, and obtain a P-type thermoelectric material layer after pre-curing;

[0023] Step 5: Place screens with N-type thermoelectric leg patterns on both sides of the substrate treated in step 4, and use a screen printing process to print N-type thermoelectric ink on the bottom electrode layer, and pre-curing to obtain an N-type thermoelectric material layer;

[0024] Step 6: heat-treating the substrate after the treatment in step 5, and then placing a screen with a top electrode unit pattern on both sides of the substrate. Using a screen printing process, a stretchable silver paste is printed on both sides of the substrate. After pre-curing, a top electrode layer is obtained, thereby obtaining a two-dimensional layout structure.

[0025] Step 7: Partially encapsulate the two-dimensional layout structure using a base material, and fold the encapsulated two-dimensional layout structure into a three-dimensional layered structure through multiple folding, thereby obtaining a three-dimensional thermoelectric device based on double-sided screen printing.

[0026] Furthermore, a specific process of the multiple folding is:

[0027] First, the gaps between adjacent rows in the two-dimensional layout structure are used as creases, and each row is folded in the same direction to form a long strip structure; then, the midline of the top electrode unit in the long strip structure is used as a crease, and each thermoelectric unit is folded in two directions in different directions to form a three-dimensional layered structure.

[0028] Furthermore, another specific process of the multiple folding is:

[0029] First, the gaps between adjacent rows in the two-dimensional layout structure are partially cut to ensure that the adjacent rows are connected end to end; then, starting from the first row, with the midline of the top electrode unit as the crease, each thermoelectric unit is folded in half in different directions in turn to form a three-dimensional layered structure unit; the three-dimensional layered structure unit of the first row is folded to the second row, and the thermoelectric units of the second row are continued to be folded in half in different directions in turn until all rows of thermoelectric units are folded in half to form a three-dimensional layered structure.

[0030] Furthermore, the three-dimensional thermoelectric device includes a hot end and a cold end. Specifically, the fold of the top electrode unit on the same side of each layer of thermoelectric units is the hot end, and the fold of the top electrode unit on the opposite side is the cold end.

[0031] Furthermore, the thermoelectric ink base liquid is obtained by mixing a catalyst, an adhesive and a curing agent in a mass percentage of 1: (50-60): (40-50).

[0032] Furthermore, the N-type thermoelectric ink is obtained by mixing a thermoelectric ink base liquid with an N-type thermoelectric powder in a mass percentage of 1: (4.5-5.4).

[0033] Furthermore, the P-type thermoelectric ink is obtained by mixing a thermoelectric ink base liquid with a P-type thermoelectric powder in a mass percentage of 1: (5.5-6.5).

[0034] Furthermore, the heat treatment conditions in step 6 are: heating at 320-380° C. for 3.5-4.5 hours in a nitrogen or rare gas environment.

[0035] Furthermore, the pre-curing conditions of the conductive silver paste and the stretchable silver paste are: drying at 120-150° C. for 10-30 minutes.

[0036] Furthermore, the pre-curing conditions of the N-type thermoelectric ink and the P-type thermoelectric ink are: drying at 90-120° C. for 30-60 minutes.

[0037] Furthermore, in the multi-layer screen printing process of steps 3 to 6, positioning is performed by setting alignment marks.

[0038] The beneficial effects of the present invention are:

[0039] 1. The present invention proposes a three-dimensional thermoelectric device based on double-sided screen printing and a method for preparing the same. By folding the two-dimensional layout structure obtained by screen printing multiple times into a three-dimensional thermoelectric device, the device can achieve three-dimensional heat flow collection. The device is particularly suitable for wearable scenarios, where heat flow between the human body and the environment is collected. To fully utilize the limited substrate area, screen printing is performed on both sides of the substrate, and through-hole electrical interconnection is used to connect all thermoelectric units in series to achieve increased output power. Therefore, the three-dimensional thermoelectric device of the present invention has the advantages of high output power density, compact structure, high integration, and small footprint.

[0040] 2. The three-dimensional thermoelectric device of the present invention is prepared by screen printing technology, which has the characteristics of low cost and easy large-scale production;

[0041] 3. The present invention performs joint heat treatment on the bottom electrode layer, the N-type thermoelectric material layer and the P-type thermoelectric material layer, which helps to reduce the contact resistance between the bottom electrode layer and the N-type thermoelectric material layer and the P-type thermoelectric material layer, and by reasonably designing the area of ​​the overlapping region between the N-type thermoelectric leg and the bottom electrode unit, as well as the area of ​​the overlapping region between the P-type thermoelectric leg and the bottom electrode unit, the internal resistance of the three-dimensional thermoelectric device is adjusted to improve the output power density of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 Schematic diagram of the principle of a three-dimensional thermoelectric device based on double-sided screen printing proposed in Example 1 of the present invention;

[0043] Figure 2 Schematic diagram of a double-sided multi-layer printing structure of a two-dimensional layout structure in Example 1 of the present invention;

[0044] Figure 3 is a schematic diagram of the multiple folding technology proposed in Example 2 of the present invention;

[0045] Figure 4 1 is a step-by-step schematic diagram of the preparation process of the two-dimensional layout structure in Example 2 of the present invention; wherein (a) is step 2; (b) is step 3; (c) is step 4; (d) is step 5; (e) is step 6; and (f) is step 7;

[0046] Figure 5 Schematic diagram of the two-dimensional layout structure after packaging in Example 2 of the present invention; wherein (a) is the front side; (b) is the back side;

[0047] Figure 6 is a schematic diagram of the strip structure in Example 2 of the present invention;

[0048] Figure 7 is a schematic diagram of a three-dimensional layered structure in Example 2 of the present invention;

[0049] Figure 8 3D thermoelectric device based on double-sided screen printing in Example 3 of the present invention is characterized by open circuit voltage, open circuit power and temperature difference;

[0050] Figure 9 is a schematic diagram of the multiple folding technology proposed in Example 4 of the present invention;

[0051] The descriptions of the symbols in the accompanying drawings are as follows:

[0052] A0 is a polyimide substrate, A1-1 is a front bottom silver electrode layer, A1-2 is a front N-type thermoelectric material layer, A1-3 is a front P-type thermoelectric material layer, A1-4 is a front top silver electrode layer, A2-1 is a back bottom silver electrode layer, A2-2 is a back N-type thermoelectric material layer, A2-3 is a back P-type thermoelectric material layer, and A2-4 is a back top silver electrode layer. DETAILED DESCRIPTION

[0053] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Although limited embodiments are described below, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0054] Example 1

[0055] This embodiment provides a three-dimensional thermoelectric device based on double-sided screen printing, such as Figure 1 As shown, it is obtained by folding the two-dimensional layout structure multiple times, with one side of the three-dimensional thermoelectric device as the hot end and the other side as the cold end.

[0056] The two-dimensional layout structure is a double-sided structure prepared by screen printing on a substrate. The structures on both sides are the same, and each side structure includes a bottom electrode layer, an N-type thermoelectric material layer, a P-type thermoelectric material layer and a top electrode layer in sequence.

[0057] This embodiment uses a 15 μm thick polyimide film as the base material, and the materials of the bottom electrode layer and the top electrode layer are silver. Then, the two-dimensional layout structure is as follows: Figure 2 As shown, it is composed of the front top silver electrode layer A1-4, the front P-type thermoelectric material layer A1-3, the front N-type thermoelectric material layer A1-2, the front bottom silver electrode layer A1-1, the polyimide substrate A0, the back bottom silver electrode layer A2-1, the back N-type thermoelectric material layer A2-2, the back P-type thermoelectric material layer A2-3 and the back top silver electrode layer A2-4.

[0058] The bottom electrode layer is an array composed of 4m×2n isolated bottom electrode units; the N-type thermoelectric material layer is an array composed of m×n isolated N-type thermoelectric legs; the P-type thermoelectric material layer is an array composed of m×n isolated P-type thermoelectric legs; and the top electrode layer is an array composed of (2m+1)×2n isolated top electrode units.

[0059] In this embodiment, m and n are 6 and 3 respectively; the size of the two-dimensional layout structure is 180.5 mm × 75 mm; the size of each bottom electrode unit is 10 mm × 1.25 mm; the size of each N-type thermoelectric leg and each P-type thermoelectric leg is 10.5 mm × 10 mm, and the spacing between adjacent N-type thermoelectric legs and P-type thermoelectric legs is 4 mm; the size of each top electrode unit is 10 mm × 6.5 mm.

[0060] The N-type thermoelectric legs and the P-type thermoelectric legs are alternately arranged to form a 2m×2n double-grid structure array; in each row of the double-grid structure array, there are overlapping areas on both sides of the N-type thermoelectric legs and the two bottom electrode units, and there are overlapping areas on both sides of the P-type thermoelectric legs and the two bottom electrode units, and the sizes of the two overlapping areas are both 10mm×0.5mm; the top electrode unit is located in the area between the adjacent N-type thermoelectric legs and the P-type thermoelectric legs, and has overlapping areas with the N-type thermoelectric legs and the P-type thermoelectric legs, as well as overlapping areas with the bottom electrode units overlapping one side of the N-type thermoelectric legs and the bottom electrode units overlapping one side of the P-type thermoelectric legs, so that the adjacent N-type thermoelectric legs and P-type thermoelectric legs in each row are electrically interconnected; wherein, the size of the overlapping area between the top electrode unit and a single bottom electrode unit is 10mm×0.75mm.

[0061] The top electrode units in adjacent rows in the top electrode layer are connected end to end, thereby forming an electrical interconnection area of ​​a serpentine bending structure in each side structure. The electrical interconnection of the double-sided structure is achieved by setting through holes in the top electrode layer.

[0062] Through multiple folding, the two-dimensional structure is folded into a three-dimensional thermoelectric device consisting of 2m×2n layers of thermoelectric units. Each layer of thermoelectric units contains either an N-type thermoelectric leg or a P-type thermoelectric leg. During the multiple folding process, a polyimide film is introduced to insulate adjacent layers of thermoelectric units.

[0063] Based on the Seebeck effect, the current inside the N-type thermoelectric leg flows from the cold end to the hot end, and the current inside the P-type thermoelectric leg flows from the hot end to the cold end. Figure 1 The arrows on the N-type and P-type thermoelectric legs represent the current flow when the temperature gradient shown in the figure is applied. By forming a three-dimensional thermoelectric device through multiple folding techniques and applying a heat source, a continuous current will flow within the device.

[0064] Example 2

[0065] This embodiment provides a method for preparing a three-dimensional thermoelectric device based on double-sided screen printing as described in Example 1. The process is as follows: Figure 4 As shown, the specific steps include:

[0066] Step 1: Mix a catalyst, an adhesive, and a curing agent in a mass ratio of 1:60.4:38.6 to obtain a thermoelectric ink base liquid; wherein the catalyst is an amine catalyst or an imidazole catalyst; the adhesive is a variety of epoxy resins; and the curing agent is an aromatic amine, dicyandiamide, a resol resin, or an acid anhydride. In this embodiment, the catalyst is specifically 1-cyanoethyl-2-ethyl-4-methylimidazole, the adhesive is specifically a mixture of bisphenol F epoxy resin and polypropylene glycol diglycidyl ether in a mass ratio of 1:1.2, and the curing agent is specifically methylhexahydrophthalic anhydride.

[0067] Step 2: N-type thermoelectric powder and P-type thermoelectric powder are mixed with the base liquid obtained in step 1, respectively, wherein the mass ratio of N-type thermoelectric powder to thermoelectric ink base liquid is 5:1, and the mass ratio of P-type thermoelectric powder to thermoelectric ink base liquid is 6:1, and an electric stirrer is used to stir at a speed of 1000 r / min to prepare N-type thermoelectric ink and P-type thermoelectric ink; in this embodiment, the N-type thermoelectric powder is specifically Bi2Te 2.7 Se 0.3 , the P-type thermoelectric powder specifically uses Sb2Te3;

[0068] Step 3: Figure 4 As shown in (a), a through hole is previously punched in a polyimide film with a thickness of 15 μm;

[0069] Step 4: Figure 4 As shown in (b), a 100-mesh screen is used to print conductive silver paste on both sides of the polyimide film treated in step 3, and then the film is placed in a blast drying oven for drying at a temperature of 150°C for 10 minutes to obtain a bottom electrode layer.

[0070] Step 5: Figure 4 As shown in (c), a 100-mesh screen is used to print P-type thermoelectric ink on both sides of the polyimide film treated in step 4 to form a P-type thermoelectric leg array. The overlapping area between each bottom electrode unit and the P-type thermoelectric leg is 10 mm × 0.5 mm. The film is then dried in a forced air drying oven at 120°C for 30 min to obtain a P-type thermoelectric material layer.

[0071] Step 6: Figure 4 As shown in (d), a 100-mesh screen is used to print N-type thermoelectric ink on both sides of the polyimide film treated in step 5 to form an N-type thermoelectric leg array. The overlapping area between each bottom electrode unit and the N-type thermoelectric leg is 10 mm × 0.5 mm. The film is then dried in a forced air drying oven at 120°C for 30 min to obtain an N-type thermoelectric material layer.

[0072] Step 7: Figure 4As shown in (e), the polyimide film treated in step 6 is placed in a muffle furnace for heat treatment. The process is first evacuated and then filled with pure nitrogen. The above operation is repeated three times to ensure that the air in the oven is completely exhausted and a nitrogen environment is formed. The temperature is maintained at 350°C and the heat treatment is continued for 4 hours, so that the printed P-type thermoelectric legs and N-type thermoelectric legs have good electrical conductivity and thermoelectric properties.

[0073] Step 8: Figure 4 As shown in (f), a 300-mesh screen is used to print stretchable silver paste on both sides of the polyimide film treated in step 7. The overlapping area between each top electrode unit and the bottom electrode unit is 10 mm × 0.75 mm. The film is then dried in a forced air drying oven at 150°C for 10 min to obtain a top electrode layer, thereby obtaining a two-dimensional layout structure. The through-holes drilled in step 3 are located in the top electrode unit in the first row and first column of the two-dimensional layout structure.

[0074] Step 9: Figure 5 As shown, additional polyimide tape is used to partially encapsulate the two-dimensional layout structure. Specifically, one side of the two-dimensional layout structure is fully encapsulated, and the other side is only encapsulated with the last row to ensure insulation during the folding process.

[0075] Step 10: Figure 3 The multiple folding technology shown folds the packaged two-dimensional layout structure into a three-dimensional layered structure, thereby obtaining a three-dimensional thermoelectric device based on double-sided screen printing. Specifically:

[0076] like Figure 6 As shown, the gaps between adjacent rows in the two-dimensional layout structure are used as creases, and each row is folded in the same direction to form a long strip structure; Figure 7 As shown, with the center line of the top electrode unit in the long strip structure as the fold, each thermoelectric unit is folded in two directions to form a three-dimensional layered structure with a volume of 2.2425 cm 3 .

[0077] Example 3

[0078] In this example, the following performance tests were performed on the three-dimensional thermoelectric device based on double-sided screen printing prepared in Example 2:

[0079] 1. Test method:

[0080] In this embodiment, an electrochemical workstation is used for testing. Specifically, a heating platform and a semiconductor refrigeration plate are used as the controllable heat source and cold source of the three-dimensional thermoelectric device respectively. A dual-input K-type thermometer (GM1312) is used to measure the temperature changes at the hot and cold ends of the three-dimensional thermoelectric device, and the real-time temperature difference is read. When the temperature difference reaches the required test value of 50°C, the open circuit voltage of the three-dimensional thermoelectric device at this time is recorded and input into the electrochemical workstation. The electrochemical workstation applies different currents to the three-dimensional thermoelectric device, specifically to the front and back sides of the first layer of thermoelectric units or the last layer of thermoelectric units in the three-dimensional layered structure, through Figure 5 The two-dimensional layout structure shown shows the flow of current in the three-dimensional thermoelectric device. It can be seen that after the current flows through all the thermoelectric units on both the front and back sides, the output voltage and power of the three-dimensional thermoelectric device are obtained under different load conditions.

[0081] 2. Test results:

[0082] The relationship curves of open circuit voltage, open circuit power and temperature difference of the three-dimensional thermoelectric device based on double-sided screen printing prepared in Example 2 are as follows: Figure 8 As shown in the figure, when the temperature difference between the hot and cold ends of the three-dimensional thermoelectric device increases from 0°C to 50°C, the open circuit voltage increases from 0mV to 725mV. 2 / r, where U is the open circuit voltage of the three-dimensional thermoelectric device and r is the measured internal resistance of the three-dimensional thermoelectric device. It can be seen that its power increases from 0 to 120μW. Since the volume of the three-dimensional thermoelectric device is 2.2425cm 3 , and then the power density of the three-dimensional thermoelectric device is calculated to be 53.5μW / cm 3 It can be seen that the three-dimensional thermoelectric device based on double-sided screen printing prepared in Example 2 has the advantages of high output power density, compact structure, high integration, and small occupied area.

[0083] Example 4

[0084] This embodiment provides another method for preparing the three-dimensional thermoelectric device based on double-sided screen printing described in Example 1. Compared with Example 2, the only difference is that the multiple folding technology in step 10 is adjusted as follows: Figure 9 As shown, specifically:

[0085] First, the gaps between adjacent rows in the two-dimensional layout structure are partially trimmed to ensure that adjacent rows are connected end to end. Then, starting from the first row, each thermoelectric unit is folded in half in different directions using the midline of the top electrode unit as the crease to form a three-dimensional layered structure unit. The three-dimensional layered structure unit of the first row is folded to the second row, and the thermoelectric units of the second row are folded in half in different directions until all rows of thermoelectric units are folded in half to form a three-dimensional layered structure.

[0086] The other preparation processes are exactly the same.

[0087] Compared with Example 2, the hot end and cold end of each layer of the thermoelectric unit in the three-dimensional thermoelectric device based on double-sided screen printing obtained in this embodiment can be directly in contact with the environment, avoiding heat loss through the substrate, increasing the temperature difference between the two ends of the thermoelectric unit, and thus improving the output of the thermoelectric device.

[0088] The above embodiments only illustrate the principles and advantages of the present invention, and are not intended to limit the present invention. They are only for helping to understand the principles of the present invention. The scope of protection of the present invention is not limited to the above configurations and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the disclosed technology without departing from the essence of the present invention, but they are still within the scope of protection of the present invention.

Claims

1. A three-dimensional thermoelectric device based on double-sided screen printing, characterized in that: The two-dimensional layout structure is obtained by folding the two-dimensional layout structure multiple times; the two-dimensional layout structure is a double-sided structure prepared by a screen printing process on a substrate, the structures on both sides are the same, and each side structure includes a bottom electrode layer, an N-type thermoelectric material layer, a P-type thermoelectric material layer and a top electrode layer in sequence; The bottom electrode layer is an array composed of 4m×2n isolated bottom electrode units; the N-type thermoelectric material layer is an array composed of m×n isolated N-type thermoelectric legs; The P-type thermoelectric material layer is an array of m×n isolated P-type thermoelectric legs; the top electrode layer is an array of (2m+1)×2n isolated top electrode units; The N-type thermoelectric legs and the P-type thermoelectric legs are alternately arranged to form a 2m×2n double-grid structure array; in each row of the double-grid structure array, two sides of the N-type thermoelectric legs respectively have overlapping regions with two bottom electrode units, and two sides of the P-type thermoelectric legs respectively have overlapping regions with two bottom electrode units. The top electrode unit is located in the area between the adjacent N-type thermoelectric legs and the P-type thermoelectric legs, and has overlapping regions with the N-type thermoelectric legs and the P-type thermoelectric legs. There is also an overlapping region with the bottom electrode unit overlapping one side of the N-type thermoelectric leg, and there is an overlapping region with the bottom electrode unit overlapping one side of the P-type thermoelectric leg, so that the adjacent N-type thermoelectric legs and P-type thermoelectric legs in each row are electrically interconnected; The top electrode units in adjacent rows in the top electrode layer are connected end to end to form an electrical interconnection region with a serpentine bending structure in each side structure; By folding multiple times, the two-dimensional layout structure is folded into a three-dimensional thermoelectric device formed by stacking 2m×2n layers of thermoelectric units. Each layer of thermoelectric units contains an N-type thermoelectric leg or a P-type thermoelectric leg.

2. The three-dimensional thermoelectric device based on double-sided screen printing according to claim 1, characterized in that: The substrate is a polyimide film with a thickness of 15 to 50 μm; the materials of the bottom electrode layer and the top electrode layer are silver.

3. The three-dimensional thermoelectric device based on double-sided screen printing according to claim 2, characterized in that: The electrical interconnection of the double-sided structure is achieved by providing through holes in the top electrode layer.

4. The three-dimensional thermoelectric device based on double-sided screen printing according to claim 3, characterized in that: During the multiple folding process, polyimide films are introduced to insulate adjacent layers of thermoelectric units.

5. The three-dimensional thermoelectric device based on double-sided screen printing according to any one of claims 1 to 4, characterized in that: By changing the area of ​​the overlapping region between the N-type thermoelectric leg and the bottom electrode unit, as well as the area of ​​the overlapping region between the P-type thermoelectric leg and the bottom electrode unit, the contact resistance between the bottom electrode layer and the N-type thermoelectric material layer and the P-type thermoelectric material layer is adjusted, thereby adjusting the internal resistance of the three-dimensional thermoelectric device.

6. A method for preparing a three-dimensional thermoelectric device based on double-sided screen printing, characterized in that: The following steps are involved: Step 1: preparing a thermoelectric ink base liquid, and preparing an N-type thermoelectric ink and a P-type thermoelectric ink based on the thermoelectric ink base liquid; Step 2: Pre-drill through holes on the substrate; Step 3: Place a screen with a bottom electrode unit pattern on both sides of the substrate, and use a screen printing process to print a conductive silver paste on both sides of the substrate, and pre-curing to obtain a bottom electrode layer; Step 4: Place a screen with a P-type thermoelectric leg pattern on both sides of the substrate treated in step 3, and use a screen printing process to print P-type thermoelectric ink on the bottom electrode layer, and obtain a P-type thermoelectric material layer after pre-curing; Step 5: Place screens with N-type thermoelectric leg patterns on both sides of the substrate treated in step 4, and use a screen printing process to print N-type thermoelectric ink on the bottom electrode layer, and pre-curing to obtain an N-type thermoelectric material layer; Step 6: heat-treating the substrate after the treatment in step 5, and then placing a screen with a top electrode unit pattern on both sides of the substrate. Using a screen printing process, a stretchable silver paste is printed on both sides of the substrate. After pre-curing, a top electrode layer is obtained, thereby obtaining a two-dimensional layout structure. Step 7: Partially encapsulate the two-dimensional layout structure with a base material, and fold the encapsulated two-dimensional layout structure into a three-dimensional layered structure through multiple folding, thereby obtaining the three-dimensional thermoelectric device based on double-sided screen printing as described in claim 4.

7. The method for preparing a three-dimensional thermoelectric device based on double-sided screen printing according to claim 6, characterized in that: A specific process of the multiple folding is: First, the gaps between adjacent rows in the two-dimensional layout structure are used as creases, and each row is folded in the same direction to form a long strip structure; then, the midline of the top electrode unit in the long strip structure is used as a crease, and each thermoelectric unit is folded in two directions in different directions to form a three-dimensional layered structure.

8. The method for preparing a three-dimensional thermoelectric device based on double-sided screen printing according to claim 6, characterized in that: Another specific process of the multiple folding is: First, the gaps between adjacent rows in the two-dimensional layout structure are partially cut to ensure that the adjacent rows are connected end to end; then, starting from the first row, with the midline of the top electrode unit as the crease, each thermoelectric unit is folded in half in different directions in turn to form a three-dimensional layered structure unit; the three-dimensional layered structure unit of the first row is folded to the second row, and the thermoelectric units of the second row are continued to be folded in half in different directions in turn until all rows of thermoelectric units are folded in half to form a three-dimensional layered structure.

9. The method for preparing a three-dimensional thermoelectric device based on double-sided screen printing according to claim 6, characterized in that: The three-dimensional thermoelectric device includes a hot end and a cold end. Specifically, the fold of the top electrode unit on the same side of each layer of thermoelectric units is the hot end, and the fold of the top electrode unit on the opposite side is the cold end.

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