Integrated flexible thermoelectric device with thermal rectification structure and preparation method and application thereof

Abstract

The invention discloses an integrated flexible thermoelectric device with a thermal rectification structure and a preparation method and application thereof, the integrated flexible thermoelectric device comprises a plurality of fan-shaped central electrodes, a first gap is arranged between adjacent central electrodes to form a circular structure, a plurality of units are arranged outside the circular structure, a second gap is arranged between every two units, and the first gap is communicated with the second gap. The first gap is communicated with the second gap, each unit comprises a P-type thermoelectric leg, an N-type thermoelectric leg and an outer electrode, the P-type thermoelectric leg and the N-type thermoelectric leg are fan-shaped, a third gap is arranged between the P-type thermoelectric leg and the N-type thermoelectric leg, and the outer electrodes are arranged at the arc-shaped positions of the P-type thermoelectric leg and the N-type thermoelectric leg. The alternative connection among the P-type thermoelectric leg, the N-type thermoelectric leg and the electrode is continuous and uninterrupted, the use of a metal electrode in a traditional thermoelectric device is avoided, and a connection node between the thermoelectric leg and the metal connection electrode in the traditional thermoelectric device is eliminated, so that the contact resistance and the contact thermal resistance caused by the connection node are eliminated, and the service life of the thermoelectric device is prolonged. And the temperature difference between the two ends of the thermoelectric leg is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermoelectric devices, and in particular relates to an integrated flexible thermoelectric device with a thermal rectification structure, a preparation method and an application thereof. Background Art

[0002] Thermoelectric devices (TEGs) can convert heat into electricity through the traditional π-shaped leg structure and can be widely used to recover industrial waste heat, vehicle exhaust waste heat and even human waste heat. They have the advantages of all-solid-state, simple system, low cost and reliable performance. Therefore, the development of high-performance TEGs as a new type of green energy can alleviate the pressure caused by energy shortages and environmental pollution, which has aroused great interest among researchers.

[0003] Flexible TEG can be closely attached to various heat sources, including planar heat sources and curved heat sources such as the human body, to minimize heat loss and increase the output power of TEG. Therefore, the development of flexible TEG has attracted widespread attention from researchers. There are usually two strategies for developing flexible thermoelectric devices: one is to manufacture rigid inorganic thermoelectric modules on flexible substrates; the other is to explore new flexible thermoelectric materials, such as organic materials and organic-inorganic composite materials to manufacture thermoelectric modules. However, these traditional TEGs are usually manufactured by connecting P-type and N-type thermoelectric modules in series through metal electrodes. Due to the mismatch between the work function of the electrode material and the thermoelectric material, the contact resistance (contact thermal resistance) at the connection node between the metal electrode and the thermoelectric material occupies a large part of the device's internal resistance (thermal resistance), which seriously damages the output power / output power density of the TEG. At the same time, due to the stress concentration that is easy to occur at the electrode connection node, the flexibility of traditional thermoelectric devices will also be reduced. As reported by Lee et al., the contact resistance at the connection node plays a dominant role in the total internal resistance of its TEG, accounting for about 77% of the total internal resistance of the device. Cho and colleagues experimentally demonstrated that contact resistance at the nodes caused a loss of about 7% in the output power density of their TEG.

[0004] In addition to being affected by the internal resistance of the TEG, the output power / output power density of the TEG is also closely related to the integration of the TEG. A TEG with a high integration will produce greater energy collection efficiency from a limited heat source surface, because the output performance of the TEG is closely related to the number of PN thermoelectric modules. However, conventional solution doping methods (immersion, drop coating, and brush printing techniques) are not suitable for manufacturing highly integrated TEGs, because the capillary effect of the solvent and the thermoelectric material in conventional solution doping causes the resolution of the PN interface prepared using the conventional solution doping method (the interface width between the P-type region and the N-type region) to be greater than 100μm. Summary of the invention

[0005] In order to overcome the technical problem in the prior art that the interface width between the P-type region and the N-type region is greater than 100μm, resulting in contact resistance (contact thermal resistance) caused by the electrode connection node of the thermoelectric device, the purpose of the present invention is to provide an integrated flexible thermoelectric device with a thermal rectification structure and a preparation method and application. The method can increase the temperature difference between the two ends of the thermoelectric device and reduce the internal resistance of the thermoelectric device. At the same time, P and N thermoelectric modules with narrow interfaces (about 7μm) are prepared by steam doping, which improves the device integration and optimizes the output performance of the thermoelectric device.

[0006] In order to overcome the problems in the prior art, the technical solution adopted by the present invention is as follows:

[0007] An integrated flexible organic thermoelectric device with a thermal rectification structure includes a plurality of fan-shaped central electrodes, a first gap is arranged between adjacent central electrodes to form a circular structure, a plurality of units are arranged outside the circular structure, a second gap is arranged between each unit, the first gap is connected to the second gap, each unit includes a P-type thermoelectric leg, an N-type thermoelectric leg and an external electrode, the P-type thermoelectric leg and the N-type thermoelectric leg are fan-shaped, and a third gap is arranged between the P-type thermoelectric leg and the N-type thermoelectric leg, and an external electrode is arranged at the arc of the P-type thermoelectric leg and the N-type thermoelectric leg.

[0008] Furthermore, the P-type thermoelectric leg, the N-type thermoelectric leg, the outer electrode and the center electrode are made of the same material.

[0009] Furthermore, the shapes of the P-type thermoelectric legs and the N-type thermoelectric legs are trapezoidal, fan-shaped or triangular.

[0010] Furthermore, the ends of the P-type thermoelectric legs and the N-type thermoelectric legs close to the central electrode (2) are hot ends, and hole arrays are arranged at the hot ends of the P-type thermoelectric legs (4) and the N-type thermoelectric legs (5).

[0011] A method for preparing an integrated flexible organic thermoelectric device with a thermal rectification structure comprises the following steps:

[0012] 1) The flexible thermoelectric film is cut to produce a fan-shaped ring structure with 14 pairs of pn legs;

[0013] 2) The dopant is doped on the fan-shaped ring structure by steam doping to prepare P-type and N-type thermoelectric legs respectively, and the P-type and N-type thermoelectric legs are connected in series to obtain an integrated flexible organic thermoelectric device with a thermal rectification structure.

[0014] Further, the temperature of steam doping is 25°C-300°C, the time of steam doping is 0.5-10h, and the steam doping is performed in a closed environment;

[0015] The materials of flexible thermoelectric films include organic thermoelectric materials and inorganic thermoelectric materials.

[0016] Furthermore, the organic thermoelectric material is one or more of carbon nanotubes, graphene, poly (3,4-ethylenedioxythiophene), 3-hexyl-substituted polythiophene, polypyrrole, and polyaniline film;

[0017] The inorganic thermoelectric material is one or more of bismuth telluride, antimony telluride, MXene, silver selenide and tin selenide.

[0018] Furthermore, the dopant includes a P-type dopant and an N-type dopant.

[0019] Further, the P-type dopant is 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanodimethyl-p-benzoquinone, 2-fluoro-7,7,8,8-tetracyanoquinodimethane, ferric chloride, iodine or hexameric trimethylcyclopropane;

[0020] The N-type dopant is polyethyleneimine, diethylenetriamine, ethylenediamine, 1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzimidazole, triphenyl phosphate, 1,3-bis(diphenylphosphino)propane, ethylenediamine, ethylenediaminetetraacetic acid, 1,8-diazabicyclo[5.4.0]undec-7-ene, 1,5,7-triazidobicyclo(4.4.0)dec-5-ene, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene or tetramethylguanidine.

[0021] An integrated flexible organic thermoelectric device with a thermal rectification structure is used in full-spectrum solar energy conversion, wearable energy harvesting devices, and medium and low temperature waste heat recovery.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] In the present invention, the P-type thermoelectric legs, N-type thermoelectric legs and electrodes are completely made of the same flexible thermoelectric material, and the alternating connection between the P-type thermoelectric legs, N-type thermoelectric legs and electrodes is continuous and uninterrupted, avoiding the use of metal electrodes in traditional thermoelectric devices, eliminating the connection nodes between the thermoelectric legs and the metal connection electrodes in traditional thermoelectric devices, thereby eliminating the contact resistance and contact thermal resistance caused by the connection nodes, reducing the internal resistance of the thermoelectric device, and increasing the temperature difference between the two ends of the thermoelectric legs. The interface width of the P and N thermoelectric modules prepared by the steam doping method of the present invention is only about 7μm, which improves the device integration and optimizes the output performance of the thermoelectric device.

[0024] Furthermore, the P-type and N-type thermoelectric legs have a thermal rectification structure with asymmetric shapes of the cold and hot ends, which improves the temperature difference between the two ends of the thermoelectric device and the output power / power density.

[0025] The integrated flexible thermoelectric device with a thermal rectification structure of the present invention can be used as a solar energy conversion device and a waste heat recovery device, and can also be used in a wearable energy collection device. Compared with traditional thermal wearable thermoelectric devices, it has a higher temperature difference and provides higher output performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the structure of an "all-in-one" thermoelectric device (SP-TEG / w-hr) with a thermal rectification structure;

[0027] Figure 2 It is a schematic diagram of the structure of a conventional thermoelectric device (Con-TEG);

[0028] Figure 3 Schematic diagram of P and N thermoelectric modules prepared by steam doping and electron microscope image of PN interface;

[0029] Figure 4 The internal resistance comparison diagram of the "integrated" thermoelectric device with thermal rectification structure (SP-TEG / w-hr) and the traditional thermoelectric device (Con-TEG); (a) is Con-TEG, (b) is SP-TEG / w-hr;

[0030] Figure 5 The infrared thermal images and output performance comparison diagram of the "integrated" thermoelectric device with a thermal rectification structure (SP-TEG / w-hr) and the "integrated" traditional thermoelectric device with a thermal rectification structure (Con-TEG) ​​under the same heat input (light intensity); wherein, (a) is Con-TEG, (b) is SP-TEG / w-hr, (c) is the voltage variation curve of Con-TEG and SP-TEG / w-hr over time, and (d) is the current variation curve of Con-TEG and SP-TEG / w-hr over time;

[0031] Figure 6 The conductivity stability of the "integrated" thermoelectric device with a thermal rectification structure (SP-TEG / w-hr) and the traditional thermoelectric device (Con-TEG) ​​under repeated bending cycles with a bending radius of about 0.7 cm; (a) is a schematic diagram, and (b) is the conductivity stability;

[0032] Figure 7 Optical image of an "all-in-one" thermoelectric device with a thermal rectification structure (SP-TEG / w-hr) used as a wearable device;

[0033] Figure 8The diagram shows the schematic diagram and performance output diagram of an "integrated" thermoelectric device (SP-TEG / w-hr) with a thermal rectification structure used as a highly integrated waste heat recovery cup holder; (a) is, (b) is a diagram showing the temperature changing with time, (c) is a diagram showing the voltage changing with time, (d) is a schematic diagram showing the voltage boosting through a boost module, (e) is a schematic diagram showing the driving of an LED lamp, (f) is a schematic diagram showing the electrochromic glass, and (g) is a schematic diagram showing the driving of an electronic thermometer.

[0034] Fig. 9 It is a schematic diagram of the structure of an "all-in-one" thermoelectric device (SP-TEG / w-hr) with a rectangular planar thermal rectification structure;

[0035] Fig.10 It is a schematic diagram of the structure of an "integrated" thermoelectric device (SP-TEG / w-hr) with a folded three-dimensional thermal rectification structure;

[0036] In the figure, 1 is the outer electrode, 2 is the center electrode, 3 is the copper foil, 4 is the P-type thermoelectric leg, 5 is the N-type thermoelectric leg, 6 is the hot end, and 7 is the cold end. DETAILED DESCRIPTION

[0037] The present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. It should be noted that after reading the content of the present invention, those skilled in the art may make various changes and modifications to the present invention, and these equivalent situations also fall within the scope defined by the claims described in the present invention.

[0038] The preparation of "one-piece" thermoelectric devices (SP-TEG) ​​without connection nodes is an effective strategy to avoid contact resistance (contact thermal resistance) at the electrode connection nodes. Compared with the traditional π-leg structure TEG, the "one-piece" flexible thermoelectric device without connection nodes has better flexibility and durability. In addition, the introduction of the thermal rectification structure can effectively increase the temperature difference between the two ends of the device. The "one-piece" structure reduces the internal resistance of the device and improves the output power / output power density of the thermoelectric device. The interface width of the P and N thermoelectric modules prepared by the steam doping method is only about 7μm, which improves the device integration and further optimizes and improves the output performance of the thermoelectric device.

[0039] See also Figure 1The present invention discloses an "integrated" flexible organic thermoelectric device with a thermal rectification structure, comprising a plurality of fan-shaped central electrodes 2, the central electrodes 2 being arranged at intervals, that is, a first gap being arranged between adjacent central electrodes 2 to form a circular structure, a plurality of units being arranged outside the circular structure, a second gap being arranged between each unit, the first gap being connected to the second gap, each unit comprising a P-type thermoelectric leg 4, an N-type thermoelectric leg 5 and an external electrode 1, the P-type thermoelectric leg 4 and the N-type thermoelectric leg 5 being fan-shaped, and a third gap being arranged between the P-type thermoelectric leg 4 and the N-type thermoelectric leg 5, an external electrode 1 being arranged at the arc between the P-type thermoelectric leg 4 and the N-type thermoelectric leg 5, one end of each unit close to the external electrode 1 being a cold end, and one end close to the central electrode 2 being a hot end. The alternating continuous and uninterrupted connection between the P-type thermoelectric leg 4, the N-type thermoelectric leg 5, the outer electrode 1 and the central electrode 2 avoids the use of metal electrodes in traditional thermoelectric devices, eliminates the connection nodes between the thermoelectric legs and the metal connection electrodes in traditional thermoelectric devices, thereby eliminating the contact resistance and contact thermal resistance caused by the connection nodes, reducing the internal resistance of the thermoelectric device, and increasing the temperature difference between the two ends of the thermoelectric legs. Among them, the P-type thermoelectric leg 4 and the N-type thermoelectric leg 5 have a thermal rectification structure with asymmetric shapes of the cold end and the hot end, which increases the temperature difference between the two ends of the thermoelectric device and the output power / power density.

[0040] The P-type thermoelectric leg 4, the N-type thermoelectric leg 5, the outer electrode 1 and the central electrode 2 are completely made of the same flexible thermoelectric material.

[0041] The P-type thermoelectric leg 4 and the N-type thermoelectric leg 5 include asymmetric cold and hot ends, and the shapes can be trapezoidal, fan-shaped, triangular and other variable-section thermal rectification structures. The hot end parts of the P-type thermoelectric leg 4 and the N-type thermoelectric leg 5 can also be designed with hole arrays and other methods to reduce heat flow.

[0042] One of the units is not provided with an external electrode 1, and the P-type thermoelectric leg 4 of the unit without the external electrode 1 is connected to the positive pole of the instrument, and the N-type thermoelectric leg 5 is connected to the negative pole of the instrument. External electrodes 1 are alternately and discontinuously provided on the outside of all other units.

[0043] The present invention provides a method for preparing an "integrated" flexible organic thermoelectric device with a thermal rectification structure, comprising the following steps:

[0044] 1) The flexible thermoelectric film was manually cut by cutting, knife engraving, wire cutting and laser engraving to produce a ring-shaped "integrated" thermoelectric device with an inner diameter of 36 mm and an outer diameter of 88 mm. The ring-shaped "integrated" thermoelectric device includes 14 pairs of pn legs and a fan-shaped structure with a height of 14 mm.

[0045] Among them, the material of the flexible thermoelectric film includes organic thermoelectric materials, such as carbon nanotubes, graphene, poly 3,4-ethylenedioxythiophene (PEDOT), 3-hexyl substituted polythiophene (P3HT), polypyrrole, polyaniline film, etc., one or more thereof; it also includes inorganic thermoelectric materials, such as bismuth telluride (Bi2Te3), antimony telluride (Sb2Te3), MXene, silver selenide (Ag2Se) and tin selenide (SnSe), etc., one or more thereof.

[0046] 2) Then, the dopant is added by steam doping to prepare P-type and N-type thermoelectric legs on the fan-shaped ring structure respectively, and the P-type and N-type thermoelectric legs are connected in series to obtain an "integrated" thermoelectric device with a narrow PN interface of a thermal rectification structure.

[0047] The mass of the dopant is 0.0001 g-10 g, the temperature of steam doping is 25° C.-300° C., the time of steam doping is 0.5-10 h, and the environment of steam doping is in a closed container.

[0048] The dopant includes a P-type dopant and an N-type dopant, wherein the P-type dopant is 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanodimethyl-p-benzoquinone (F4TCNQ), 2-fluoro-7,7,8,8-tetracyanoquinodimethane (FTCNQ), ferric chloride (FeCl3), iodine (I2) or hexameric trimethylcyclopropane (CN6CP), etc. The N-type dopant is polyethyleneimine (PEI), diethylenetriamine (DETA), 1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzimidazole (N-DMBI), triphenyl phosphate (TPP), 1,3-bis(diphenylphosphino)propane (d-TPP), EDA (ethylenediamine, Ethylenediamine), ethylenediaminetetraacetic acid (EDTA), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,5,7-triazidobicyclo(4.4.0)dec-5-ene (TBD), 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (Me-TBD) or tetramethylguanidine (TMG) and the like.

[0049] An "integrated" flexible organic thermoelectric device with a thermal rectification structure as described above is used in full-spectrum solar energy conversion, wearable energy collection devices, and medium and low temperature waste heat recovery.

[0050] Covering the thermoelectric legs of an "integrated" thermoelectric device with a thermal rectification structure with a shielding layer (metal sheet or nylon cloth, etc.) can be used to develop full-spectrum solar energy and convert energy that cannot be effectively utilized by photovoltaic cells into electrical energy.

[0051] Integrating "all-in-one" thermoelectric devices with thermal rectification structures into clothing can be used in wearable energy harvesting devices, providing higher output performance compared to traditional thermal wearable thermoelectric devices.

[0052] The "integrated" thermoelectric device with a thermal rectification structure is integrated into containers such as medium and low temperature waste heat pipes to achieve high integration, so as to achieve sufficient electrical energy output to meet the electricity needs of small power equipment.

[0053] Example 1

[0054] (1) Using a multi-walled carbon nanotube film prepared by chemical vapor deposition as a raw material, the multi-walled carbon nanotube film is cut into a hollow circular pattern with a radius of 2.7 cm, which is composed of 8 pairs of fan-shaped thermoelectric legs, 8 fan-shaped central electrodes and 7 fan-shaped outer electrodes. Figure 1 As shown, the fan-shaped thermoelectric leg has a thermal rectification structure, the inner arc (hot end) length of the fan-shaped thermoelectric leg is 0.15 cm, the outer arc (cold end) length is 0.95 cm, the width between the inner arc and the outer arc (thermoelectric leg length) is 1.65 cm, the width of the 7 outer electrodes is 0.15 cm (that is, the width between the inner arc and the outer arc of the outer electrode), the inner arc length is 0.95 cm, the outer arc length is 1 cm, and the 8 center electrodes are fan-shaped with a radius of 0.9 cm and a central angle of 44°, ensuring that a gap greater than 0.05 cm is left between adjacent center electrodes, and the thermoelectric legs and electrodes are connected in series alternately and continuously in a manner of thermoelectric leg-center electrode-thermoelectric leg-outer electrode-thermoelectric leg-······.

[0055] (2) The eight pairs of fan-shaped thermoelectric legs in the hollow circular pattern obtained in step (1) are shielded with polyethylene terephthalate (PET) at intervals, and 0.1 g of P-type dopant F4TCNQ is used for doping at 120°C for 30 min in a sealed glass container to obtain a P-type thermoelectric leg; in a sealed glass container, the center of the PET is rotated 22.5° to shield the P-type thermoelectric leg, and 0.2 g of N-type dopant PEI is used for doping at 120°C for 30 min to obtain an N-type thermoelectric leg; the device is taken out and placed in a vacuum oven at 50°C for drying for 2 h to obtain an "integrated" flexible thermoelectric device with a thermal rectification structure consisting of alternating P-type thermoelectric legs and N-type thermoelectric legs in series, denoted as SP-TEG / w-hr, such as Figure 1 As shown, from Figure 1 It can be seen that SP-TEG / w-hr is completely composed of the same material, carbon nanotube film, which avoids the existence of metal electrode connection nodes and eliminates contact resistance (contact thermal resistance). The design of the fan-shaped ring thermal rectification structure makes the cold end have a larger heat dissipation area.

[0056] like Figure 3 As shown, from Figure 3It can be seen that the resolution of the P and N interfaces prepared by steam doping is high, and the width of the P and N interfaces is only about 7μm.

[0057] The photoelectric conversion performance was tested under different light intensities. The results are as follows: Figure 5 As shown in (a), (b), (c) and (d), from Figure 5 It can be seen that SP-TEG / w-hr has a larger temperature difference and higher output power.

[0058] The bending cycle test was carried out for 1000 times. The results are as follows Figure 6 As shown in (a) and (b), from Figure 6 It can be seen that the "integrated" thermoelectric device has better flexibility, and the conductivity G remains basically unchanged during 1000 bending cycles.

[0059] Comparative Example 1

[0060] Conventional thermoelectric devices (Con-TEG) ​​used for comparison; e.g. Figure 2 As shown, 8 pairs of rectangular thermoelectric legs with a width of 0.15 cm and a length of 1.8 cm are connected in series by copper foil with a length of 0.94 cm and a width of 0.15 cm and silver paste according to similar dimensions, and then PET is used to shield the thermoelectric legs at intervals. In a closed glass container, 0.1 g of a P-type dopant F4TCNQ is used to dope for 30 min at 120°C to obtain a P-type thermoelectric leg; the PET center is rotated 22.5° to shield the P-type doped P-type thermoelectric leg, and in a closed glass container, 0.2 g of an N-type dopant PEI is used to dope for 30 min at 120°C to obtain an N-type thermoelectric leg; the device is taken out and placed in a vacuum oven at 50°C for drying for 2 hours to obtain a traditional thermoelectric device consisting of P-type and N-type thermoelectric legs alternately connected in series, as shown in FIG. Figure 2 As shown, from Figure 2 It can be seen that Con-TEG has an obvious connection node between the metal electrode and the thermoelectric leg.

[0061] like Figure 4 As shown in (a) and (b), from Figure 4 It can be seen that the connection nodes in the integrated thermoelectric device in this embodiment 1 make the resistance and thermal resistance of the device lower, so as to have a greater output power density. The resistance of embodiment 1 is lower than the resistance of the device in comparative example 1.

[0062] The present invention provides an application of the "integrated" thermoelectric device with a thermal rectification structure in a solar energy conversion device, a wearable energy collection device, and a medium and low temperature waste heat recovery device, as follows:

[0063] The "integrated" flexible thermoelectric device (SP-TEG / w-hr) with a thermal rectification structure obtained in Example 1 was placed under sunlight with the thermoelectric legs covered with tin foil, and can be used to convert solar energy into thermal energy and then into electrical energy. It can be seen that the device of the present invention can be used as a solar energy conversion device.

[0064] The "integrated" flexible thermoelectric device (SP-TEG / w-hr) with a thermal rectification structure obtained in Example 1 is integrated with clothing, the thermoelectric legs are woven into the fabric of the clothing, and the central electrode is exposed to sunlight. It can be used in a wearable energy collection device. Compared with traditional thermal wearable thermoelectric devices, it has a higher temperature difference and provides higher output performance. At a temperature difference of 60K, the maximum output power of the "integrated" thermoelectric device is 120μW.

[0065] like Figure 7 As shown, from Figure 7 It can be seen that the "integrated" thermoelectric device with a thermal rectification structure can convert solar energy into electrical energy when worn on the human body. It has a larger temperature difference than the traditional wearable hotspot device that uses human body temperature as the heat source, at about 600W / m 2 The output voltage is about 7.9mV under sunlight.

[0066] Ten "integrated" thermoelectric devices SP-TEG and an aluminum cylinder (radius 29 mm, height 30 mm) are assembled into a Lego-like thermoelectric cup holder. The "integrated" thermoelectric device is assembled on the aluminum cylinder piece by piece, and the distance between the two pieces is about 3 mm. SP-TEG uses silver glue in series to obtain an "integrated" device shape with a thermal rectification structure in which the thermoelectric legs and electrodes are alternately connected in series, or the flexible thermoelectric material is directly printed or deposited on the preset shape of the mask plate by (3D) printing, chemical deposition and magnetron sputtering to form an "integrated" thermoelectric device frame (shaped like a ring, rectangle and folded shape, etc.) with a thermal rectification structure in which the thermoelectric legs and electrodes are alternately connected in series. The thermoelectric generator used for water cup waste heat recovery can drive LED lights, electrochromic glass and electronic thermometers after being combined with a boost module (BQ25504). It can be seen that the device of the present invention can be used as a waste heat recovery device.

[0067] like Figure 8 As shown in (a), (b), (c), (d), (e), (f) and (g), from Figure 8 It can be seen that the "integrated" thermoelectric device with a thermal rectification structure can be used for waste heat recovery of low-temperature heat sources. After adding 96°C hot water, the device output voltage is about 598mV. After being boosted by a booster module, the voltage can be stabilized at 4.25V. It can be used to drive LED lights (Figure (e)), electrochromic glass (Figure (f)) and electronic thermometers (Figure (g)).

[0068] Example 2

[0069] (1) Graphene was deposited into a 6.9 cm long and 3 cm wide hollow rectangular film by electrochemical deposition, specifically, three pairs of isosceles trapezoidal thermoelectric legs with an upper base (hot end) width of 0.3 cm, a lower base (cold end) width of 0.9 cm, and a height (thermoelectric leg length) of 3 cm, and five isosceles trapezoidal electrodes (three of which were isosceles trapezoids with an upper base of 0.84 cm, a lower base of 0.9 cm, and a height of 0.3 cm, and the other two were isosceles trapezoids with an upper base of 0.3 cm, a lower base of 0.36 cm, and a height of 0.3 cm) connected in series alternately to form a rectangular plane (the thermoelectric legs were arranged in parallel, and the electrodes connected the upper and lower bases of adjacent thermoelectric legs in series in sequence, and the overall shape was a hollow rectangle, as shown in FIG. Fig. 9 The "integrated" device pattern of all-graphene with a thermal rectification structure is shaped like Fig. 9 shown.

[0070] (2) The thermoelectric legs of the "integrated" device pattern (shape) obtained in step (1) are shielded with polyPET, and 0.15 g of P-type dopant FTCNQ is used for doping for 50 min at 180° C. in a sealed glass container to obtain P-type thermoelectric legs; the PET is removed and the FTCNQ-doped P-type thermoelectric legs are shielded again, and 0.05 g of N-type dopant N-DMBI is used for doping for 45 min at 190° C. in a sealed glass container to obtain N-type thermoelectric legs; the device is taken out and placed in a vacuum oven at 50° C. for drying for 6 h to obtain a rectangular planar "integrated" flexible thermoelectric device with a thermal rectification structure consisting of P-type and N-type thermoelectric legs alternately connected in series.

[0071] Example 3

[0072] (1) CNT / PEODT slurry was printed on a polytetrafluoroethylene substrate by 3D printing to form a zigzag thin film thermoelectric material with a thickness of 10 μm and a length of 10 cm, wherein along the length direction of the film, 10 trapezoids with an upper base (hot end) width of 0.25 cm, a lower base (cold end) width of 0.6 cm, and a height (thermoelectric leg length) of 1 cm were continuously formed in such a way that the upper bases of adjacent isosceles trapezoids were connected to each other and the lower bases were connected to each other, as shown in FIG. Fig.10 shown.

[0073] (2) The 10 isosceles trapezoids of the zigzag thin-film thermoelectric material obtained in step (1) are alternately shielded with PET, and then 0.3 g of a P-type dopant C6CP is doped for 20 min in a sealed glass container under heating conditions at 90° C. to obtain a P-type thermoelectric leg; the PET is removed and the P-type thermoelectric leg obtained by C6CP doping is shielded again, and 0.25 g of an N-type dopant DBU is doped for 40 min in a sealed glass container under heating conditions at 90° C. to obtain an N-type thermoelectric leg; and then the thermoelectric leg is placed in a vacuum oven at 50° C. and dried for 4 h, and the trapezoidal thermoelectric legs are rotated (folded) into an angle of 60° with the upper base or the lower base as the axis, as shown in FIG. Fig.10 As shown, a folded three-dimensional "integrated" flexible thermoelectric device with a thermal rectification structure is obtained, which is composed of P-type and N-type thermoelectric legs alternately connected in series.

[0074] Example 4

[0075] (1) Using poly (3,4-ethylenedioxythiophene) as raw material, a multi-walled carbon nanotube film was cut into a hollow circular pattern with a radius of 2.7 cm, which consisted of 8 pairs of fan-shaped thermoelectric legs, 8 fan-shaped central electrodes, and 7 fan-shaped outer electrodes. Figure 1 As shown, the fan-shaped thermoelectric leg has a thermal rectification structure, the inner arc (hot end) length of the fan-shaped thermoelectric leg is 0.15 cm, the outer arc (cold end) length is 0.95 cm, the width between the inner arc and the outer arc (thermoelectric leg length) is 1.65 cm, the width of the 7 outer electrodes is 0.15 cm (that is, the width between the inner arc and the outer arc of the outer electrode), the inner arc length is 0.95 cm, the outer arc length is 1 cm, and the 8 center electrodes are fan-shaped with a radius of 0.9 cm and a central angle of 44°, ensuring that a gap greater than 0.05 cm is left between adjacent center electrodes, and the thermoelectric legs and electrodes are connected in series alternately and continuously in a manner of thermoelectric leg-center electrode-thermoelectric leg-outer electrode-thermoelectric leg-······.

[0076] (2) The eight pairs of fan-shaped thermoelectric legs in the hollow circular pattern obtained in step (1) are shielded with polyethylene terephthalate (PET) at intervals, and 0.1 g of P-type dopant FTCNQ is used for doping at 120°C for 30 min in a sealed glass container to obtain P-type thermoelectric legs; in a sealed glass container, the center of the PET is rotated 22.5° to shield the P-type thermoelectric legs, and 0.2 g of N-type dopant DETA is used for doping at 120°C for 30 min to obtain N-type thermoelectric legs; the device is taken out and placed in a vacuum oven at 50°C for drying for 2 h to obtain an "integrated" flexible thermoelectric device with a thermal rectification structure consisting of P-type thermoelectric legs and N-type thermoelectric legs alternately connected in series.

[0077] Example 5

[0078] (1) Using 3-hexyl-substituted polythiophene as raw material, a multi-walled carbon nanotube film was cut into a hollow circular pattern with a radius of 2.7 cm, which consisted of 8 pairs of fan-shaped thermoelectric legs, 8 fan-shaped central electrodes, and 7 fan-shaped outer electrodes. Figure 1 As shown, the fan-shaped thermoelectric leg has a thermal rectification structure, the inner arc (hot end) length of the fan-shaped thermoelectric leg is 0.15 cm, the outer arc (cold end) length is 0.95 cm, the width between the inner arc and the outer arc (thermoelectric leg length) is 1.65 cm, the width of the 7 outer electrodes is 0.15 cm (that is, the width between the inner arc and the outer arc of the outer electrode), the inner arc length is 0.95 cm, the outer arc length is 1 cm, and the 8 center electrodes are fan-shaped with a radius of 0.9 cm and a central angle of 44°, ensuring that a gap greater than 0.05 cm is left between adjacent center electrodes, and the thermoelectric legs and electrodes are connected in series alternately and continuously in a manner of thermoelectric leg-center electrode-thermoelectric leg-outer electrode-thermoelectric leg-······.

[0079] (2) The eight pairs of fan-shaped thermoelectric legs in the hollow circular pattern obtained in step (1) are shielded with polyethylene terephthalate (PET) at intervals, and 0.1 g of P-type dopant FeCl3 is used for doping at 120°C for 30 min in a sealed glass container to obtain P-type thermoelectric legs; in a sealed glass container, the center of the PET is rotated 22.5° to shield the P-type thermoelectric legs, and 0.2 g of N-type dopant N-DMBI is used for doping at 120°C for 30 min to obtain N-type thermoelectric legs; the device is taken out and placed in a vacuum oven at 50°C for drying for 2 h to obtain an "integrated" flexible thermoelectric device with a thermal rectification structure consisting of P-type thermoelectric legs and N-type thermoelectric legs alternately connected in series.

[0080] Example 6

[0081] (1) Using a polypyrrole and polyaniline mixture film as the raw material, the multi-walled carbon nanotube film was cut into a hollow circular pattern with a radius of 2.7 cm, which consisted of 8 pairs of fan-shaped thermoelectric legs, 8 fan-shaped central electrodes, and 7 fan-shaped outer electrodes. Figure 1 As shown, the fan-shaped thermoelectric leg has a thermal rectification structure, the inner arc (hot end) length of the fan-shaped thermoelectric leg is 0.15 cm, the outer arc (cold end) length is 0.95 cm, the width between the inner arc and the outer arc (thermoelectric leg length) is 1.65 cm, the width of the 7 outer electrodes is 0.15 cm (that is, the width between the inner arc and the outer arc of the outer electrode), the inner arc length is 0.95 cm, the outer arc length is 1 cm, and the 8 center electrodes are fan-shaped with a radius of 0.9 cm and a central angle of 44°, ensuring that a gap greater than 0.05 cm is left between adjacent center electrodes, and the thermoelectric legs and electrodes are connected in series alternately and continuously in a manner of thermoelectric leg-center electrode-thermoelectric leg-outer electrode-thermoelectric leg-······.

[0082] (2) The eight pairs of fan-shaped thermoelectric legs in the hollow circular pattern obtained in step (1) are shielded with polyethylene terephthalate (PET) at intervals, and 0.1 g of P-type dopant I2 is doped for 30 min at 120°C in a sealed glass container to obtain P-type thermoelectric legs; in a sealed glass container, the center of the PET is rotated 22.5° to shield the P-type thermoelectric legs, and 0.2 g of N-type dopant ethylenediamine is doped for 30 min at 120°C to obtain N-type thermoelectric legs; the device is taken out and placed in a vacuum oven at 50°C for drying for 2 h to obtain an "integrated" flexible thermoelectric device with a thermal rectification structure consisting of P-type thermoelectric legs and N-type thermoelectric legs alternately connected in series.

[0083] Example 7

[0084] (1) Same as Example 4;

[0085] (2) The eight pairs of fan-shaped thermoelectric legs in the hollow circular pattern obtained in step (1) are shielded with polyethylene terephthalate (PET) at intervals, and 0.1 g of a P-type dopant CN6CP is used for doping for 30 min at 120°C in a sealed glass container to obtain a P-type thermoelectric leg; in a sealed glass container, the center of the PET is rotated 22.5° to shield the P-type thermoelectric leg, and 0.2 g of an N-type dopant TPP is used for doping for 30 min at 120°C to obtain an N-type thermoelectric leg; the device is taken out and placed in a vacuum oven at 50°C for drying for 2 h to obtain an "integrated" flexible thermoelectric device with a thermal rectification structure consisting of P-type thermoelectric legs and N-type thermoelectric legs alternately connected in series.

[0086] Example 8

[0087] (1) Same as Example 4;

[0088] (2) The eight pairs of fan-shaped thermoelectric legs in the hollow circular pattern obtained in step (1) are shielded with polyethylene terephthalate (PET) at intervals, and 0.1 g of a P-type dopant CN6CP is used for doping for 30 min at 120°C in a sealed glass container to obtain a P-type thermoelectric leg; in a sealed glass container, the center of the PET is rotated 22.5° to shield the P-type thermoelectric leg, and 0.2 g of an N-type dopant d-TPP is used for doping for 30 min at 120°C to obtain an N-type thermoelectric leg; the device is taken out and placed in a vacuum oven at 50°C for drying for 2 h to obtain an "integrated" flexible thermoelectric device with a thermal rectification structure consisting of P-type thermoelectric legs and N-type thermoelectric legs alternately connected in series.

[0089] Example 10

[0090] (1) Same as Example 4;

[0091] (2) The eight pairs of fan-shaped thermoelectric legs in the hollow circular pattern obtained in step (1) are shielded with polyethylene terephthalate (PET) at intervals, and 0.1 g of a P-type dopant CN6CP is used for doping for 30 min at 120°C in a sealed glass container to obtain a P-type thermoelectric leg; in a sealed glass container, the center of the PET is rotated 22.5° to shield the P-type thermoelectric leg, and 0.2 g of an N-type dopant EDA is used for doping for 30 min at 120°C to obtain an N-type thermoelectric leg; the device is taken out and placed in a vacuum oven at 50°C for drying for 2 h to obtain an "integrated" flexible thermoelectric device with a thermal rectification structure consisting of P-type thermoelectric legs and N-type thermoelectric legs alternately connected in series.

[0092] Embodiment 11

[0093] (1) Same as Example 4;

[0094] (2) The eight pairs of fan-shaped thermoelectric legs in the hollow circular pattern obtained in step (1) are shielded with polyethylene terephthalate (PET) at intervals, and 0.1 g of a P-type dopant CN6CP is used for doping for 30 min at 120°C in a sealed glass container to obtain a P-type thermoelectric leg; in a sealed glass container, the center of the PET is rotated 22.5° to shield the P-type thermoelectric leg, and 0.2 g of an N-type dopant EDTA is used for doping for 30 min at 120°C to obtain an N-type thermoelectric leg; the device is taken out and placed in a vacuum oven at 50°C for drying for 2 h to obtain an "integrated" flexible thermoelectric device with a thermal rectification structure consisting of P-type thermoelectric legs and N-type thermoelectric legs alternately connected in series.

[0095] Example 12

[0096] (1) Same as Example 4;

[0097] (2) The eight pairs of fan-shaped thermoelectric legs in the hollow circular pattern obtained in step (1) are shielded with polyethylene terephthalate (PET) at intervals, and 0.1 g of a P-type dopant CN6CP is used for doping for 30 min at 120°C in a sealed glass container to obtain a P-type thermoelectric leg; in a sealed glass container, the center of the PET is rotated 22.5° to shield the P-type thermoelectric leg, and 0.2 g of an N-type dopant DBU is used for doping for 30 min at 120°C to obtain an N-type thermoelectric leg; the device is taken out and placed in a vacuum oven at 50°C for drying for 2 h to obtain an "integrated" flexible thermoelectric device with a thermal rectification structure consisting of P-type thermoelectric legs and N-type thermoelectric legs alternately connected in series.

[0098] Example 13

[0099] (1) Same as Example 4;

[0100] (2) The eight pairs of fan-shaped thermoelectric legs in the hollow circular pattern obtained in step (1) are shielded with polyethylene terephthalate (PET) at intervals, and 0.1 g of a P-type dopant CN6CP is used for doping for 30 min at 120°C in a sealed glass container to obtain a P-type thermoelectric leg; in a sealed glass container, the center of the PET is rotated 22.5° to shield the P-type thermoelectric leg, and 0.2 g of an N-type dopant TBD is used for doping for 30 min at 120°C to obtain an N-type thermoelectric leg; the device is taken out and placed in a vacuum oven at 50°C for drying for 2 h to obtain an "integrated" flexible thermoelectric device with a thermal rectification structure consisting of P-type thermoelectric legs and N-type thermoelectric legs alternately connected in series.

[0101] Embodiment 14

[0102] (1) Same as Example 4;

[0103] (2) The eight pairs of fan-shaped thermoelectric legs in the hollow circular pattern obtained in step (1) are shielded with polyethylene terephthalate (PET) at intervals, and 0.1 g of a P-type dopant CN6CP is used for doping for 30 min at 120°C in a sealed glass container to obtain a P-type thermoelectric leg; in a sealed glass container, the center of the PET is rotated 22.5° to shield the P-type thermoelectric leg, and 0.2 g of an N-type dopant Me-TBD is used for doping for 30 min at 120°C to obtain an N-type thermoelectric leg; the device is taken out and placed in a vacuum oven at 50°C for drying for 2 h to obtain an "integrated" flexible thermoelectric device with a thermal rectification structure consisting of P-type thermoelectric legs and N-type thermoelectric legs alternately connected in series.

[0104] Embodiment 15

[0105] (1) Same as Example 4;

[0106] (2) The eight pairs of fan-shaped thermoelectric legs in the hollow circular pattern obtained in step (1) are shielded with polyethylene terephthalate (PET) at intervals, and 0.1 g of a P-type dopant CN6CP is used for doping for 30 min at 120°C in a sealed glass container to obtain a P-type thermoelectric leg; in a sealed glass container, the center of the PET is rotated 22.5° to shield the P-type thermoelectric leg, and 0.2 g of an N-type dopant TMG is used for doping for 30 min at 120°C to obtain an N-type thermoelectric leg; the device is taken out and placed in a vacuum oven at 50°C for drying for 2 h to obtain an "integrated" flexible thermoelectric device with a thermal rectification structure consisting of P-type thermoelectric legs and N-type thermoelectric legs alternately connected in series.

[0107] The "integrated" thermoelectric device (SP-TEG) ​​with a thermal rectification structure prepared by carbon nanotube film in the present invention is an effective measure to avoid the contact resistance and contact thermal resistance caused by the electrode connection nodes in traditional thermoelectric devices. In traditional thermoelectric devices, due to the mismatch in work function between the electrode material and the thermoelectric material, it is difficult to transmit current and heat flow at the heterogeneous interface of different materials, so that the contact resistance and contact thermal resistance at the electrode connection node occupy a large part of the internal resistance of the device. The structure of the "integrated" thermoelectric device (SP-TEG) ​​is composed of the same thermoelectric material without interruption, eliminating the metal electrode connection node and the contact resistance and contact thermal resistance caused by the connection node, thereby reducing the internal resistance of the device, increasing the temperature difference between the two ends of the thermoelectric device, and ultimately increasing the output power of the device. Where E is the open circuit voltage, I is the circuit current, and R in is the internal resistance of the device, R L is the load resistor), the output power of the "integrated" thermoelectric device with a thermal rectification structure is 4.5 times that of traditional thermoelectric devices. In addition, the removal of heavy metal connecting electrodes can greatly improve the (mass) power output density of the thermoelectric device ( Where m is the mass of the thermoelectric device), the mass output power density of the "integrated" thermoelectric device with a thermal rectification structure is 83 times that of traditional thermoelectric devices. The "integrated" thermoelectric device without metal electrode connection nodes also avoids the problem of stress concentration at the electrode connection of traditional thermoelectric devices, which makes the device less flexible. The conductivity of the device did not change significantly during 1,000 cycles with a bending radius of about 0.7 cm.

[0108] The introduction of the thermal rectification structure in the "all-in-one" thermoelectric device (SP-TEG) ​​with thermal rectification structure can effectively increase the temperature difference between the two ends of the thermoelectric device, thereby increasing the output power of the thermoelectric device. Where S p , S n and ΔT are the Seebeck coefficients of P and N type thermoelectric materials and the temperature difference between the two ends of the thermoelectric device, respectively). The effect of the thermal rectification structure mainly comes from two aspects. First, according to Fourier's heat transfer law ( Where A is the heat transfer area, κ is the thermal conductivity, δ is the length of the thermoelectric leg, and ΔT is the temperature difference). The hot end cross-sectional area of ​​the thermoelectric leg is reduced, the heat flow input is reduced, and the cold end temperature is reduced, thereby increasing the temperature difference between the two ends of the thermoelectric leg. The second is based on the convection heat transfer characteristics (φ = hS (TT w ), where h is the convective heat transfer coefficient, S is the convective heat dissipation area, T w is the ambient temperature, T is the temperature), increasing the heat dissipation area of ​​the cold end and reducing the temperature of the cold end, thereby increasing the temperature difference between the two ends of the thermoelectric leg.

[0109] The steam doping method adopted can effectively alleviate the problem of difficult control of the P and N interfaces caused by solution penetration due to capillary action in conventional solution doping. The steam doping method adopted in the present invention can prepare narrow interface P and N thermoelectric modules with P and N interfaces within 7μm, which lays a foundation for the preparation of highly integrated integrated thermoelectric devices.

[0110] The above description is only for the best embodiment of the present invention, but it should not be understood as limiting the claims. The present invention is not limited to the above embodiments, and its specific structure is allowed to be changed. However, all changes made within the protection scope of the independent claims of the present invention are within the protection scope of the present invention.

[0111] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

Claims

1. An integrated flexible organic thermoelectric device with a thermal rectification structure, characterized in that: The invention comprises a plurality of fan-shaped central electrodes (2), a first gap is arranged between adjacent central electrodes (2), so as to form a circular structure, a plurality of units are arranged outside the circular structure, a second gap is arranged between each unit, the first gap is connected with the second gap, each unit comprises a P-type thermoelectric leg (4), an N-type thermoelectric leg (5) and an external electrode (1), the P-type thermoelectric leg (4) and the N-type thermoelectric leg (5) are fan-shaped, a third gap is arranged between the P-type thermoelectric leg (4) and the N-type thermoelectric leg (5), and the external electrode (1) is arranged at the arc between the P-type thermoelectric leg (4) and the N-type thermoelectric leg (5).

2. The integrated flexible organic thermoelectric device with a thermal rectification structure according to claim 1, characterized in that: The P-type thermoelectric leg (4), the N-type thermoelectric leg (5), the outer electrode (1) and the central electrode (2) are made of the same material.

3. The integrated flexible organic thermoelectric device with a thermal rectification structure according to claim 1, characterized in that: The shapes of the P-type thermoelectric leg (4) and the N-type thermoelectric leg (5) are trapezoidal, fan-shaped or triangular.

4. The integrated flexible organic thermoelectric device with a thermal rectification structure according to claim 1, characterized in that: One end of the P-type thermoelectric leg (4) and the N-type thermoelectric leg (5) close to the central electrode (2) is a hot end, and a hole array is arranged at the hot end of the P-type thermoelectric leg (4) and the N-type thermoelectric leg (5).

5. A method for preparing an integrated flexible organic thermoelectric device with a thermal rectification structure, characterized in that: The following steps are involved: 1) The flexible thermoelectric film is cut to produce a fan-shaped ring structure with 14 pairs of pn legs; 2) The dopant is doped on the fan-shaped ring structure by steam doping to prepare P-type and N-type thermoelectric legs respectively, and the P-type and N-type thermoelectric legs are connected in series to obtain an integrated flexible organic thermoelectric device with a thermal rectification structure.

6. The method for preparing an integrated flexible organic thermoelectric device with a thermal rectification structure according to claim 5, characterized in that: The temperature of steam doping is 25℃-300℃, the time of steam doping is 0.5-10h, and the steam doping is carried out in a closed environment; The materials of flexible thermoelectric films include organic thermoelectric materials and inorganic thermoelectric materials.

7. The method for preparing an integrated flexible organic thermoelectric device with a thermal rectification structure according to claim 5, characterized in that: The organic thermoelectric material is one or more of carbon nanotubes, graphene, poly(3,4-ethylenedioxythiophene), 3-hexyl-substituted polythiophene), polypyrrole, and polyaniline film; The inorganic thermoelectric material is one or more of bismuth telluride, antimony telluride, MXene, silver selenide and tin selenide.

8. The method for preparing an integrated flexible organic thermoelectric device with a thermal rectification structure according to claim 5, characterized in that: The dopant includes a P-type dopant and an N-type dopant.

9. The method for preparing an integrated flexible organic thermoelectric device with a thermal rectification structure according to claim 8, characterized in that: The P-type dopant is 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanodimethyl-p-benzoquinone, 2-fluoro-7,7,8,8-tetracyanoquinodimethane, ferric chloride, iodine or hexameric trimethylcyclopropane; The N-type dopant is polyethyleneimine, diethylenetriamine, ethylenediamine, 1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzimidazole, triphenyl phosphate, 1,3-bis(diphenylphosphino)propane, ethylenediamine, ethylenediaminetetraacetic acid, 1,8-diazabicyclo[5.4.0]undec-7-ene, 1,5,7-triazidobicyclo(4.4.0)dec-5-ene, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene or tetramethylguanidine.

10. An application of an integrated flexible organic thermoelectric device with a thermal rectification structure as claimed in any one of claims 1 to 4 in full-spectrum solar energy conversion, wearable energy collection devices and medium and low temperature waste heat recovery.

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