A thermoelectric conversion device and its preparation method, and a thermoelectric conversion system

Abstract

The present invention provides a thermoelectric conversion device and a preparation method thereof, and a thermoelectric conversion system. The thermoelectric conversion device comprises: a first electrode; a P-type element and an N-type element electrically connected to the first electrode; a second electrode located on the side of the P-type element and the N-type element away from the first electrode; the P-type element comprises a plurality of P-type sublayer regions, and for any one of the P-type sublayer regions, the surface area of ​​the P-type sublayer region facing the first electrode is smaller than the surface area of ​​the P-type sublayer region facing the second electrode; and / or, the N-type element comprises a plurality of N-type sublayer regions, and for any one of the N-type sublayer regions, the surface area of ​​the N-type sublayer region facing the first electrode is smaller than the surface area of ​​the N-type sublayer region facing the second electrode. The thermoelectric conversion device improves the thermoelectric conversion efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of thermoelectric conversion, and in particular to a thermoelectric conversion device and a preparation method thereof, and a thermoelectric conversion system. Background Art

[0002] Thermoelectric materials are a kind of pollution-free green energy material that directly converts heat energy and electrical energy through the thermoelectric effect. Thermoelectric materials use temperature difference to generate electricity without mechanical parts and chemical reactions. They also use voltage difference to cool without compressors or refrigerants such as Freon. Devices made of thermoelectric materials are ideal vibration-free, noise-free, leak-free, small-sized, and environmentally friendly power supplies and refrigerators. In recent years, they have been widely used in industrial waste heat, geothermal power generation, clean energy wind and solar heat and power cogeneration (such as distributed energy storage systems, compressed air energy storage, cold and heat storage systems, etc.), smart buildings and communities, deep space exploration (such as Galileo isotope heating / electricity), deep sea exploration (quiet power supply / heat for submersibles), and heat dissipation of microelectronics and optoelectronic devices.

[0003] Thermoelectric conversion efficiency is a key intrinsic parameter for measuring the thermoelectric conversion capacity of materials. How to regulate and improve the thermoelectric conversion efficiency is the basis for the optimal design and application of thermoelectric materials, devices and systems. It is also a bottleneck problem that restricts the research and development of thermoelectric materials, device and system optimization and application. It seriously restricts the development of new thermoelectric materials and devices, efficient and intelligent utilization of energy, aerospace thermoelectric management, energy-saving smart cities, distributed energy supply and storage technologies at this stage.

[0004] At present, the thermoelectric conversion efficiency of thermoelectric conversion devices is generally low (ZT≈1), and the application of thermoelectric conversion devices and systems is greatly limited. Summary of the invention

[0005] Therefore, the present invention provides a thermoelectric conversion device and a preparation method thereof, and a thermoelectric conversion system to improve the thermoelectric conversion efficiency of the thermoelectric conversion device.

[0006] The present invention provides a thermoelectric conversion device, comprising: a first electrode; a P-type element and an N-type element electrically connected to the first electrode; a second electrode respectively located on the side of the P-type element and the N-type element away from the first electrode; the P-type element comprises a plurality of P-type sublayer regions stacked in a direction from the second electrode to the first electrode, and for any one of the P-type sublayer regions, the surface area of ​​the P-type sublayer region facing the first electrode is smaller than the surface area of ​​the P-type sublayer region facing the second electrode; and / or the N-type element comprises a plurality of N-type sublayer regions stacked in a direction from the second electrode to the first electrode, and for any one of the N-type sublayer regions, the surface area of ​​the N-type sublayer region facing the first electrode is smaller than the surface area of ​​the N-type sublayer region facing the second electrode.

[0007] Optionally, the several P-type sublayer regions include the first P-type sublayer region to the Mth P-type sublayer region, M is an integer greater than or equal to 2, the k+1th P-type sublayer region is located on the surface of the kth P-type sublayer region facing away from the second electrode, k is an integer greater than or equal to 1 and less than or equal to M-1; the area of ​​the kth P-type sublayer region facing the first electrode is greater than or equal to the area of ​​the k+1th P-type sublayer region facing the first electrode.

[0008] Optionally, the thickness of the kth P-type sublayer region is less than or equal to the thickness of the k+1th P-type sublayer region.

[0009] Optionally, the several N-type sublayer regions include the first N-type sublayer region to the Q-th N-type sublayer region, Q is an integer greater than or equal to 2, the j+1-th N-type sublayer region is located on the surface of the j-th N-type sublayer region facing away from the second electrode, j is an integer greater than or equal to 1 and less than or equal to Q-1; the area of ​​the j-th N-type sublayer region facing the first electrode is greater than or equal to the area of ​​the j+1-th N-type sublayer region facing the first electrode.

[0010] Optionally, the thickness of the j-th N-type sub-layer region is less than or equal to the thickness of the j+1-th N-type sub-layer region.

[0011] Optionally, the thickness of each P-type sublayer region is 5 nanometers to 1 mm; the thickness of each N-type sublayer region is 5 nanometers to 1 mm.

[0012] Optionally, the top and bottom surfaces of the P-type sublayer region are circular, or the top and bottom surfaces of the P-type sublayer region are rectangular; the top and bottom surfaces of the N-type sublayer region are circular, or the top and bottom surfaces of the N-type sublayer region are rectangular.

[0013] Optionally, for any P-type sublayer region, the angle between the bottom surface and the side wall of the P-type sublayer region is 2.5 degrees to 87.5 degrees; for any N-type sublayer region, the angle between the bottom surface and the side wall of the N-type sublayer region is 2.5 degrees to 87.5 degrees.

[0014] The present invention also provides a method for preparing a thermoelectric conversion device, comprising: providing a first electrode and a second electrode; forming a P-type element and an N-type element, wherein the P-type element has a first side and a second side relative to each other, and the N-type element has a third side and a fourth side relative to each other; the P-type element comprises a plurality of P-type sublayer regions stacked in a direction from the first side to the second side, and for any one of the P-type sublayer regions, a surface area of ​​the P-type sublayer region facing the second side is smaller than a surface area of ​​the P-type sublayer region facing the first side; and / or the N-type element comprises a plurality of N-type sublayer regions stacked in a direction from the third side to the fourth side, and a surface area of ​​the N-type sublayer region facing the fourth side is smaller than a surface area of ​​the N-type sublayer region facing the third side; and arranging the P-type element and the N-type element between the first electrode and the second electrode, with a portion of the second electrode located on the first side of the P-type element, a portion of the second electrode located on the third side of the N-type element, and the first electrode located on the second side of the P-type element and on the fourth side of the N-type element.

[0015] The present invention also provides a thermoelectric conversion system, comprising the thermoelectric conversion device of the present invention.

[0016] The technical solution of the present invention has the following beneficial effects:

[0017] In the thermoelectric conversion device provided by the technical solution of the present invention, for any P-type sublayer region, the surface area of ​​the P-type sublayer region facing the first electrode is smaller than the surface area of ​​the P-type sublayer region facing the second electrode; and / or, for any N-type sublayer region, the surface area of ​​the N-type sublayer region facing the first electrode is smaller than the surface area of ​​the N-type sublayer region facing the second electrode. When the surface area of ​​the P-type sublayer region facing the first electrode is smaller than the surface area of ​​the P-type sublayer region facing the second electrode, the P-type element presents a microscopically asymmetric layered stacking structure, so that each layer of the P-type sublayer region of the P-type element has a thermal rectification effect, that is, the heat flow from the surface of the P-type sublayer region facing the first electrode to the surface of the P-type sublayer region facing the second electrode is smaller than the heat flow from the surface of the P-type sublayer region facing the second electrode to the surface of the P-type sublayer region facing the first electrode. The thermal rectification effect of the P-type sublayer region reduces the effective thermal conductivity of the P-type sublayer region, reduces the effective thermal conductivity of the P-type element, and significantly increases the temperature difference between the two ends of the P-type element. When the surface area of ​​the N-type sublayer region facing the first electrode is smaller than the surface area of ​​the N-type sublayer region facing the second electrode, the N-type element presents a microscopically asymmetric layered stacking structure, so that each N-type sublayer region of the N-type element has a thermal rectification effect, that is, the heat flow from the surface of the N-type sublayer region facing the first electrode to the surface of the N-type sublayer region facing the second electrode is smaller than the heat flow from the surface of the N-type sublayer region facing the second electrode to the surface of the N-type sublayer region facing the first electrode. The thermal rectification effect of the N-type sublayer region reduces the effective thermal conductivity of the N-type sublayer region, reduces the effective thermal conductivity of the N-type element, and significantly increases the temperature difference between the two ends of the N-type element. Secondly, the structural asymmetry of the P-type sublayer region regulates the number of carrier charges and improves the Seebeck coefficient of the P-type element. The structural asymmetry of the N-type sublayer region regulates the number of carrier charges and improves the Seebeck coefficient of the N-type element. Since the effective thermal conductivity of the P-type element is reduced and the Seebeck coefficient is increased, the thermoelectric figure of merit of the P-type element is improved, and / or the effective thermal conductivity of the N-type element is reduced and the Seebeck coefficient is increased, the thermoelectric figure of merit of the N-type element is improved, thereby significantly improving the cooling (heating) efficiency or temperature difference power generation efficiency, and the thermoelectric conversion efficiency is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 A schematic diagram of the structure of a thermoelectric conversion device provided by one embodiment of the present invention;

[0020] Figure 2 A cross-sectional view of an N-type element provided by an embodiment of the present invention;

[0021] Figure 3 A cross-sectional view of an N-type element provided by another embodiment of the present invention;

[0022] Figure 4 A top view of an N-type component is provided for one embodiment of the present invention;

[0023] Figure 5 A top view of an N-type component provided by another embodiment of the present invention. DETAILED DESCRIPTION

[0024] The thermoelectric conversion efficiency of thermoelectric materials is generally measured by the thermoelectric figure of merit ZT, which is defined as: Among them, S is the Seekbeck coefficient, σ is the material conductivity, ρ is the material resistivity, κ is the material thermal conductivity, △U is the voltage difference caused by the temperature difference at both ends of the material, △T is the temperature difference at both ends of the material, and T is the absolute temperature.

[0025] At present, the main method is to improve the thermoelectric figure of merit of the material by changing the internal micro-nanostructure or doping concentration of the material, reducing the thermal conductivity of the material, increasing the electrical conductivity and Seebeck coefficient of the material. This type of method involves material type matching, doping concentration, defect control, etc. At present, it is still difficult to break through the improvement of thermoelectric conversion efficiency.

[0026] On this basis, the present invention provides a thermoelectric conversion device, wherein a P-type element comprises a plurality of P-type sub-layer regions stacked in a direction from a second electrode to a first electrode, and for any P-type sub-layer region, the surface area of ​​the P-type sub-layer region facing the first electrode is smaller than the surface area of ​​the P-type sub-layer region facing the second electrode; and / or an N-type element comprises a plurality of N-type sub-layer regions stacked in a direction from a second electrode to a first electrode, and for any N-type sub-layer region, the surface area of ​​the N-type sub-layer region facing the first electrode is smaller than the surface area of ​​the N-type sub-layer region facing the second electrode. The thermoelectric conversion device improves the thermoelectric conversion efficiency.

[0027] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. 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.

[0028] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0029] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0030] Example 1

[0031] The present invention provides a thermoelectric conversion device, referring to Figure 1 ,include:

[0032] A first electrode 100;

[0033] A P-type element 110 and an N-type element 120 electrically connected to the first electrode 100;

[0034] A second electrode 130 located at a side of the P-type element 110 and the N-type element 120 away from the first electrode 100;

[0035] The P-type element 110 includes a plurality of P-type sub-layer regions 1101 stacked in the direction from the second electrode 130 to the first electrode 100, and for any one of the P-type sub-layer regions 1101, the surface area of ​​the P-type sub-layer region 1101 facing the first electrode 100 is smaller than the surface area of ​​the P-type sub-layer region 1101 facing the second electrode 130; and, the N-type element 120 includes a plurality of N-type sub-layer regions 1201 stacked in the direction from the second electrode 130 to the first electrode 100, and for any one of the N-type sub-layer regions 1201, the surface area of ​​the N-type sub-layer region 1201 facing the first electrode 100 is smaller than the surface area of ​​the N-type sub-layer region 1201 facing the second electrode 130.

[0036] The several P-type sublayer regions 1101 include the first P-type sublayer region to the Mth P-type sublayer region, M is an integer greater than or equal to 2, the k+1th P-type sublayer region is located on the side surface of the kth P-type sublayer region away from the second electrode, and k is an integer greater than or equal to 1 and less than or equal to M-1.

[0037] It should be noted that the number of layers of the P-type sublayer region can be limited according to actual needs.

[0038] The several N-type sublayer regions 1201 include the first N-type sublayer region to the Q-th N-type sublayer region, Q is an integer greater than or equal to 2, the j+1-th N-type sublayer region is located on the side surface of the j-th N-type sublayer region away from the second electrode, and j is an integer greater than or equal to 1 and less than or equal to Q-1.

[0039] It should be noted that, in other examples, the number of layers of the N-type sub-layer region can be limited according to actual needs.

[0040] In this embodiment, the surface area of ​​the P-type sublayer region 1101 facing the first electrode 100 is smaller than the surface area of ​​the P-type sublayer region 1101 facing the second electrode 130, so that the P-type element 110 presents a microscopically asymmetric layered stacking structure, so that each layer of the P-type sublayer region 1101 of the P-type element 110 has a thermal rectification effect, that is, the heat flow from the surface of the P-type sublayer region 1101 facing the first electrode 100 to the surface of the P-type sublayer region 1101 facing the second electrode 130 is smaller than the heat flow from the surface of the P-type sublayer region 1101 facing the second electrode 130 to the surface of the P-type sublayer region 1101 facing the first electrode 100. The thermal rectification effect of the P-type sublayer region 1101 reduces the effective thermal conductivity of the P-type sublayer region 1101, reduces the effective thermal conductivity of the P-type element 110, and significantly increases the temperature difference between the two ends of the P-type element 110. When the surface area of ​​the N-type sublayer region 1201 facing the first electrode 100 is smaller than the surface area of ​​the N-type sublayer region 1201 facing the second electrode 130, the N-type element 120 presents a microscopically asymmetric layered stacking structure, so that each layer of the N-type sublayer region 1201 of the N-type element 120 has a thermal rectification effect, that is, the heat flow from the surface of the N-type sublayer region 1201 facing the first electrode 100 to the surface of the N-type sublayer region 1201 facing the second electrode 130 is smaller than the heat flow from the surface of the N-type sublayer region 1201 facing the second electrode 130 to the surface of the N-type sublayer region 1201 facing the first electrode 100. The thermal rectification effect of the N-type sublayer region 1201 reduces the effective thermal conductivity of the N-type sublayer region 1201, reduces the effective thermal conductivity of the N-type element 120, and significantly increases the temperature difference between the two ends of the N-type element 120. Secondly, the structural asymmetry of the P-type sublayer region 1101 regulates the number of carrier charges and improves the Seebeck coefficient of the P-type element 110. The structural asymmetry of the N-type sublayer region 1201 regulates the number of carrier charges and improves the Seebeck coefficient of the N-type element 120. Since the effective thermal conductivity of the P-type element 110 is reduced and the Seebeck coefficient is increased, the thermoelectric figure of merit of the P-type element 110 is improved, and / or the effective thermal conductivity of the N-type element 120 is reduced and the Seebeck coefficient is increased, the thermoelectric figure of merit of the N-type element 120 is improved, thereby significantly improving the cooling (heating) efficiency or the temperature difference power generation efficiency, and the thermoelectric conversion efficiency is improved.

[0041] It should be noted that the rectifying effect of the P-type sublayer region 1101 is positively correlated with the asymmetric structure of the P-type sublayer region 1101, that is, the greater the difference between the surface area of ​​the P-type sublayer region 1101 facing the first electrode 100 and the surface area of ​​the P-type sublayer region 1101 facing away from the first electrode 100, the more obvious the rectifying effect of the P-type sublayer region 1101. The microstructure size of each layer of the P-type sublayer region 1101 can be optimized according to the actual situation and the preparation process. The effective thermal conductivity and heat flow of the P-type element 110 are directional regulated by superposition of multiple layers of the asymmetric structure of the P-type sublayer region 1101. In addition, under the condition of a micro-nano asymmetric structure, the number of carrier charges in each layer of the P-type sublayer region 1101 will be reduced due to the filtering and current limiting of the P-type sublayer region 1101, thereby increasing the Seebeck coefficient of each layer of the P-type sublayer region 1101, and the Seebeck coefficient of the P-type element 110 is increased after the multiple layers are superimposed.

[0042] The rectifying effect of the N-type sublayer region 1201 is positively correlated with the asymmetric structure of the N-type sublayer region 1201, that is, the greater the difference between the surface area of ​​the N-type sublayer region 1201 facing the first electrode 100 and the surface area of ​​the N-type sublayer region 1201 facing away from the first electrode 100, the more obvious the rectifying effect of the N-type sublayer region 1201. The microscopic structure size of each layer of the N-type sublayer region 1201 can be optimized according to the actual situation and the preparation process. The effective thermal conductivity and heat flow of the N-type element 120 are directional regulated by superimposing multiple layers of the N-type sublayer region 1201 with an asymmetric structure. In addition, under the condition of a micro-nano asymmetric structure, the number of carrier charges in each layer of the N-type sublayer region 1201 will be reduced due to the filtering and current limiting of the N-type sublayer region 1201, thereby increasing the Seebeck coefficient of each layer of the N-type sublayer region 1201, and the Seebeck coefficient of the N-type element 120 is increased after the multiple layers are superimposed.

[0043] The area of ​​the kth P-type sublayer region facing the first electrode is greater than or equal to the area of ​​the k+1th P-type sublayer region facing the first electrode.

[0044] In this embodiment, it is taken as an example that the area of ​​the kth P-type sublayer region facing the first electrode is equal to the area of ​​the k+1th P-type sublayer region facing the first electrode.

[0045] In other embodiments, the area of ​​the kth P-type sublayer region facing the first electrode is greater than the area of ​​the k+1th P-type sublayer region facing the first electrode, so that the thermal rectification effect of the P-type element is further improved. The area of ​​the first P-type sublayer region facing the first electrode decreases to the area of ​​the Mth P-type sublayer region facing the first electrode.

[0046] The thickness of the kth P-type sublayer region is less than or equal to the thickness of the k+1th P-type sublayer region.

[0047] In this embodiment, it is taken as an example that the thickness of the kth P-type sub-layer region is equal to the thickness of the k+1th P-type sub-layer region.

[0048] In other embodiments, the thickness of the kth P-type sublayer region is less than the thickness of the k+1th P-type sublayer region, so that the thermal rectification effect of the P-type element is further improved. The thickness of the first P-type sublayer region to the Mth P-type sublayer region increases gradually.

[0049] In a specific embodiment, the thickness of the first P-type sublayer region increases to the M-th P-type sublayer region, and the area of ​​the first P-type sublayer region facing the first electrode decreases to the M-th P-type sublayer region facing the first electrode. This effectively improves the thermal rectification effect of the P-type sublayer region.

[0050] In one embodiment, for any P-type sublayer region, the angle between the bottom surface and the sidewall of the P-type sublayer region is 2.5 degrees to 87.5 degrees, for example, 10 degrees, 20 degrees, 30 degrees, 40 degrees, 50 degrees, 60 degrees, 70 degrees or 80 degrees.

[0051] The area of ​​the j-th N-type sub-layer region facing the first electrode is greater than or equal to the area of ​​the j+1-th N-type sub-layer region facing the first electrode.

[0052] In this embodiment, reference Figure 2 , taking as an example that the area of ​​the j-th N-type sublayer region facing the first electrode is equal to the area of ​​the j+1-th N-type sublayer region facing the first electrode.

[0053] In other embodiments, reference Figure 3 The N-type element includes a plurality of N-type sub-layer regions 1201a, and the area of ​​the j-th N-type sub-layer region facing the first electrode is larger than the area of ​​the j+1-th N-type sub-layer region facing the first electrode, so that the thermal rectification effect of the N-type element is further improved. The area of ​​the first N-type sub-layer region facing the first electrode decreases gradually to the area of ​​the Q-th N-type sub-layer region facing the first electrode.

[0054] The thickness of the j-th N-type sub-layer region is less than or equal to the thickness of the j+1-th N-type sub-layer region.

[0055] In this embodiment, it is taken as an example that the thickness of the j-th N-type sub-layer region is equal to the thickness of the j+1-th N-type sub-layer region.

[0056] In other embodiments, the thickness of the jth N-type sub-layer region is less than the thickness of the j+1th N-type sub-layer region, so that the thermal rectification effect of the N-type element is further improved. The thickness of the first N-type sub-layer region increases gradually to the thickness of the Qth N-type sub-layer region.

[0057] In a specific embodiment, the thickness of the first N-type sub-layer region increases to the thickness of the Q-th N-type sub-layer region, and the area of ​​the first N-type sub-layer region facing the first electrode decreases to the area of ​​the Q-th N-type sub-layer region facing the first electrode. This effectively improves the thermal rectification effect of the N-type element.

[0058] In one embodiment, for any N-type sub-layer region, an angle between a bottom surface and a sidewall of the N-type sub-layer region is 2.5 degrees to 87.5 degrees.

[0059] The thickness of each P-type sublayer region is 5 nanometers to 1 mm, such as 10 nanometers, 50 nanometers, 100 nanometers, 1 micrometer, 10 micrometers, 100 micrometers or 1 millimeter; the thickness of each N-type sublayer region is 5 nanometers to 1 mm, such as 10 nanometers, 50 nanometers, 100 nanometers, 1 micrometer, 10 micrometers, 100 micrometers or 1 millimeter. Preferably, the thickness of each P-type sublayer region is less than or equal to 100 micrometers, and the thickness of each N-type sublayer region is less than or equal to 100 micrometers. The smaller the thickness of each P-type sublayer and the smaller the thickness of each N-type sublayer, the better the thermal rectification effect.

[0060] refer to Figure 4 , the top and bottom surfaces of the N-type sublayer region 1201 are rectangular, or, referring to Figure 5 , the top and bottom surfaces of the N-type sublayer region 1201c are circular.

[0061] The top and bottom surfaces of the N-type sublayer region 1201 are circular, or the top and bottom surfaces of the P-type sublayer region are rectangular.

[0062] Example 2

[0063] This embodiment provides a thermoelectric conversion device. The difference between the thermoelectric conversion device of this embodiment and the thermoelectric conversion device of Embodiment 1 is that: for any P-type sublayer region, the surface area of ​​the P-type sublayer region facing the first electrode is smaller than the surface area of ​​the P-type sublayer region facing the second electrode; or, for any N-type sublayer region, the surface area of ​​the N-type sublayer region facing the first electrode is smaller than the surface area of ​​the N-type sublayer region facing the second electrode 130.

[0064] The same contents between this embodiment and embodiment 1 will not be described in detail.

[0065] Example 3

[0066] This embodiment provides a method for preparing a thermoelectric conversion device, comprising:

[0067] S1: providing a first electrode and a second electrode;

[0068] S2: forming a P-type element and an N-type element, wherein the P-type element has a first side and a second side opposite to each other, and the N-type element has a third side and a fourth side opposite to each other;

[0069] The P-type element comprises a plurality of P-type sub-layer regions stacked in a direction from the first side to the second side, and for any one of the P-type sub-layer regions, a surface area of ​​the P-type sub-layer region facing the second side is smaller than a surface area of ​​the P-type sub-layer region facing the first side; and / or, the N-type element comprises a plurality of N-type sub-layer regions stacked in a direction from the third side to the fourth side, and a surface area of ​​the N-type sub-layer region facing the fourth side is smaller than a surface area of ​​the N-type sub-layer region facing the third side;

[0070] S3: The P-type element and the N-type element are arranged between a first electrode and a second electrode, wherein a portion of the second electrode is located on a first side of the P-type element, a portion of the second electrode is located on a third side of the N-type element, and the first electrode is located on a second side of the P-type element and a fourth side of the N-type element.

[0071] Example 4

[0072] This embodiment provides a thermoelectric conversion system, including: the above-mentioned thermoelectric conversion device.

[0073] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A thermoelectric conversion device, characterized in that: include: a first electrode; A P-type element and an N-type element electrically connected to the first electrode; A second electrode located respectively at a side of the P-type element and the N-type element away from the first electrode; The P-type element includes a plurality of P-type sublayer regions stacked in a direction from the second electrode to the first electrode, and for any one of the P-type sublayer regions, a surface area of ​​the P-type sublayer region facing the first electrode is smaller than a surface area of ​​the P-type sublayer region facing the second electrode, and the materials of the plurality of P-type sublayer regions are the same; and / or, the N-type element includes a plurality of N-type sublayer regions stacked in a direction from the second electrode to the first electrode, and for any one of the N-type sublayer regions, a surface area of ​​the N-type sublayer region facing the first electrode is smaller than a surface area of ​​the N-type sublayer region facing the first electrode. The surface area of ​​the N-type sublayer region facing the second electrode, and the materials of several N-type sublayer regions are the same; the several P-type sublayer regions include the first P-type sublayer region to the M-th P-type sublayer region, M is an integer greater than or equal to 2, the k+1-th P-type sublayer region is located on the surface of the k-th P-type sublayer region away from the second electrode, k is an integer greater than or equal to 1 and less than or equal to M-1; the area of ​​the k-th P-type sublayer region facing the first electrode is greater than or equal to the area of ​​the k+1-th P-type sublayer region facing the first electrode.

2. The thermoelectric conversion device according to claim 1, characterized in that , the thickness of the kth P-type sublayer region is less than or equal to the thickness of the k+1th P-type sublayer region.

3. The thermoelectric conversion device according to claim 1, characterized in that: The several N-type sublayer regions include the first N-type sublayer region to the Q-th N-type sublayer region, Q is an integer greater than or equal to 2, the j+1-th N-type sublayer region is located on the surface of the j-th N-type sublayer region facing away from the second electrode, j is an integer greater than or equal to 1 and less than or equal to Q-1; the area of ​​the j-th N-type sublayer region facing the first electrode is greater than or equal to the area of ​​the j+1-th N-type sublayer region facing the first electrode.

4. The thermoelectric conversion device according to claim 3, characterized in that: The thickness of the j-th N-type sub-layer region is less than or equal to the thickness of the j+1-th N-type sub-layer region.

5. The thermoelectric conversion device according to any one of claims 1 to 4, characterized in that: The thickness of each P-type sublayer region is 5nm to 1mm; the thickness of each N-type sublayer region is 5nm to 1mm.

6. The thermoelectric conversion device according to any one of claims 1 to 4, characterized in that: The top surface and the bottom surface of the P-type sublayer region are circular, or the top surface and the bottom surface of the P-type sublayer region are rectangular; The top surface and the bottom surface of the N-type sublayer region are circular, or the top surface and the bottom surface of the N-type sublayer region are rectangular.

7. The thermoelectric conversion device according to any one of claims 1 to 4, characterized in that: For any P-type sublayer region, the angle between the bottom surface and the side wall of the P-type sublayer region is 2.5 degrees to 87.5 degrees; for any N-type sublayer region, the angle between the bottom surface and the side wall of the N-type sublayer region is 2.5 degrees to 87.5 degrees.

8. A method for preparing a thermoelectric conversion device, characterized in that: include: providing a first electrode and a second electrode; forming a P-type element and an N-type element, the P-type element having a first side and a second side opposite to each other, and the N-type element having a third side and a fourth side opposite to each other; The P-type element includes a plurality of P-type sublayer regions stacked in a direction from the first side to the second side, and for any one of the P-type sublayer regions, the surface area of ​​the P-type sublayer region facing the second side is smaller than the surface area of ​​the P-type sublayer region facing the first side, and the materials of the plurality of P-type sublayer regions are the same; and / or, the N-type element includes a plurality of N-type sublayer regions stacked in a direction from the third side and the fourth side, the surface area of ​​the N-type sublayer region facing the fourth side is smaller than the surface area of ​​the N-type sublayer region facing the third side, and the materials of the plurality of N-type sublayer regions are the same; the plurality of P-type sublayer regions include the first P-type sublayer region to the Mth P-type sublayer region, M is an integer greater than or equal to 2, the k+1th P-type sublayer region is located on a side of the kth P-type sublayer region away from the second electrode, k is an integer greater than or equal to 1 and less than or equal to M-1; the area of ​​the kth P-type sublayer region facing the first electrode is greater than or equal to the area of ​​the k+1th P-type sublayer region facing the first electrode; The P-type element and the N-type element are arranged between a first electrode and a second electrode, part of the second electrode is located on a first side of the P-type element, part of the second electrode is located on a third side of the N-type element, and the first electrode is located on a second side of the P-type element and a fourth side of the N-type element.

9. A thermoelectric conversion system, characterized in that: include: The thermoelectric conversion device according to any one of claims 1 to 7.

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