Preparation method of flexible thermoelectric thin film material
By embedding the micron-scale powder of bismuth telluride into the polyimide flexible matrix and using solution spin coating to prepare flexible thermoelectric film materials, the mechanical performance limitations and complex preparation processes of traditional bismuth telluride materials when applied in flexible electronic equipment are solved, and the flexibility of materials and the innovation of thermal management solutions is achieved.
Patent Information
- Application Number
- CN202411662364.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-20
- Publication Date
- 2025-04-15
AI Technical Summary
Traditional rigid bismuth telluride thermoelectric materials are prone to cracking or failure when used in flexible electronic devices and wearable devices, and the preparation process is complex and costly, which limits its promotion in large-scale commercial applications.
By combining the micron-scale powder of bismuth telluride with the flexible matrix polyimide, flexible thermoelectric film materials are prepared by solution spin coating, simplifying the preparation process and reducing costs, and adapting to complex curved surfaces and deformation environments.
It has realized the flexibility of bismuth telluride materials, breaking the limitations of traditional thermoelectric materials in application scenarios, and providing innovative thermal management solutions for flexible electronic products, with commercial and technical value.
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Figure CN119836212A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of thermoelectric materials, and in particular relates to a method for preparing a flexible thermoelectric thin film material. Background Art
[0002] Bismuth telluride is one of the most widely used thermoelectric materials, mainly used in thermoelectric power generation and thermoelectric refrigeration devices. Its excellent thermoelectric performance, especially the high thermoelectric figure of merit near room temperature, makes it one of the best choices in the medium and low temperature range. In traditional applications, bismuth telluride usually exists in the form of bulk materials, which are prepared by complex processes such as high-temperature sintering or crystal growth. Such rigid materials are widely used in power management, temperature control systems, local thermal management and other fields. However, with the development of electronic products towards flexibility, portability and wearable devices, traditional rigid thermoelectric materials have gradually exposed some limitations such as mechanical performance limitations, complex preparation processes, high integration difficulties, and limited application scenarios. Thermoelectric materials such as bismuth telluride are usually rigid or brittle, which makes it difficult to adapt to the requirements of modern flexible electronic devices for material flexibility. Emerging fields such as wearable devices, smart clothing, and flexible sensors require materials to maintain stable performance when bent, stretched or even twisted, while traditional bulk bismuth telluride materials are prone to cracking or failure in such applications. At the same time, traditional bismuth telluride thermoelectric materials are mostly prepared by high-temperature sintering or crystal growth technology. These processes require high energy consumption, high cost, and strict requirements on equipment and process control. They are not suitable for large-scale, low-cost manufacturing, which limits the promotion of this material in large-scale commercial applications. In addition, rigid bismuth telluride materials are difficult to integrate with flexible electronic devices, especially in miniaturized or micro-miniaturized applications. The rigidity of the material makes it difficult to adhere or combine tightly on complex shapes or surfaces, affecting the performance and reliability of the device. Therefore, although bismuth telluride materials perform well in the traditional thermoelectric field, their rigidity limits their widespread application in fields such as smart wearable devices and flexible energy management devices.
[0003] Therefore, the existing technology urgently needs a composite material that can not only maintain the efficient thermoelectric conversion performance of bismuth telluride but also work stably in complex and flexible structures to meet the growing demand in the field of flexible electronic devices and wearable technology. Summary of the invention
[0004] The present invention is to solve the above problems and provides a method for preparing a flexible thermoelectric thin film material. The flexible thermoelectric material is prepared by combining bismuth telluride micron powder with a flexible matrix polyimide and adopting a solution spin coating method. During the preparation process, the preparation process is simplified as much as possible, and it is easy to mass produce at low cost.
[0005] The specific technical solutions of the present invention are as follows:
[0006] In the first aspect of the present invention, a method for preparing a flexible thermoelectric thin film material is provided, comprising the following steps: preparing bismuth telluride micron-sized powder and a polyamic acid (PAA) solution with a concentration of 15-20wt%, respectively, uniformly dispersing the bismuth telluride powder in the polyamic acid (PAA) solution and fully mixing, and adding a silane coupling agent surfactant to obtain a uniformly mixed solution; then coating the mixed solution on a silicon wafer substrate, controlling the film thickness by spin coating to obtain a composite film, and heating and curing at a certain temperature to convert PAA into PI (polyimide) to obtain a flexible thermoelectric thin film composite material. The specific steps are as follows:
[0007] 1) mixing three single-element raw materials of Sb, Bi and Te, melting them in vacuum to obtain an ingot, and then crushing and ball-milling them to obtain bismuth telluride micron-sized powder;
[0008] 2) dissolving the polyamic acid precursor in DMAc to obtain a PAA solution with a concentration of 15-20 wt %, and stirring the mixture evenly;
[0009] 3) uniformly dispersing bismuth telluride powder in a polyimide matrix and fully mixing, and adding a silane coupling agent surfactant to obtain a uniformly mixed solution;
[0010] 4) coating the mixed solution onto a silicon wafer substrate, controlling the film thickness by spin coating to obtain a uniform composite film, and heating and curing it at a certain temperature to convert PAA into PI to obtain a flexible thermoelectric thin film composite material.
[0011] Preferably, in step 1), the molar ratio of the three single-substance raw materials Bi, Sb and Te is 0.4:1.6:3; and the purity of the three single-substance raw materials Bi, Sb and Te is 99.999%.
[0012] The operation of vacuum melting to obtain an ingot is as follows: the three elements of Bi, Sb and Te are mixed and placed in a graphite crucible, the graphite crucible is placed in a quartz tube, the quartz tube is evacuated and packaged for vacuum melting. The vacuum melting conditions are as follows: under a vacuum degree of 0.01Pa, the temperature is increased to 700-800℃ at a rate of 10℃ / min, and the temperature is kept for at least 6h before cooling to room temperature.
[0013] During the pulverization, ball milling is used in an argon protection environment, the rotation speed is set to 300-400 rpm, and the ball milling time is 10-60 minutes to form micron-sized bismuth telluride powder.
[0014] Preferably, in step 2), the preparation method of 15-20 wt% polyamic acid (PAA) solution is as follows: dissolving polyamic acid precursor in DMAc, heating and stirring to form a PAA solution with a concentration of 15-20 wt%. The stirring and heating conditions are: stirring the solution at 60° C. for 2 hours with a magnetic stirrer to ensure that the solution is evenly dispersed and free of particles.
[0015] Preferably, in step 3), the process conditions for uniformly dispersing the bismuth telluride powder in the polyamic acid (PAA) solution and fully mixing are as follows: adding micron-sized bismuth telluride powder to the PAA solution at a mass ratio of 5 to 20% wt%, and using ultrasonic treatment for 30 to 60 minutes to ensure that the bismuth telluride powder is uniformly dispersed in the solution to avoid particle aggregation.
[0016] Preferably, the silane coupling agent surfactant is selected from aminosilane, and the amount of the silane coupling agent surfactant added is 0.5% to 2% of the powder mass. After adding the silane coupling agent surfactant, in order to ensure that the solution is mixed evenly, it needs to be stirred at room temperature for 1 hour.
[0017] Preferably, in step 4), when preparing the composite material, the rotation speed is 1500-3000 rpm, and the duration is 30 seconds to obtain a uniform composite film. Then the coated film composite material is heated at 80°C for 1 hour to evaporate the solvent; after the solvent evaporates, the material is further heated to 150-200°C and maintained for 2-4 hours to convert PAA into PI, thereby achieving complete curing of the polyimide matrix and obtaining a flexible thermoelectric film composite material.
[0018] The second aspect of the present invention provides a flexible thermoelectric thin film material prepared by the above method.
[0019] Functions and Effects of the Invention
[0020] The present invention aims to address the defect that most existing bismuth telluride system materials exist in a rigid form, which limits their application in emerging fields such as wearable devices and flexible electronic devices. By embedding micron-scale bismuth telluride powder into a flexible matrix such as polyimide, the flexibility of bismuth telluride materials is achieved, breaking the limitations of traditional thermoelectric materials in application scenarios, and providing an innovative thermoelectric management solution for flexible electronic products, which has certain commercial and technical value. DETAILED DESCRIPTION
[0021] The present invention is described in detail below in conjunction with the embodiments and the accompanying drawings. However, the following embodiments should not be considered as limiting the scope of the present invention.
[0022] Example 1
[0023] Figure 1 This is a preparation method of a flexible thermoelectric thin film material, and the specific steps are as follows:
[0024] (1) According to the molar ratio of Bi, Sb and Te of 0.4:1.6:3, weigh 3000g of pure tellurium, bismuth and antimony element particles as the matrix material and put them into a quartz tube, evacuate until the pressure in the tube is less than 2Pa and seal it. Then put the quartz tube into a tubular heating furnace, set the temperature to 730℃, and heat it to 730℃ at a rate of 10℃ / min under a vacuum of 0.01Pa, keep it warm for at least 6h, and cool it outside the furnace. The high-temperature synthesized material was ball-milled for 60min under an argon protection environment at a speed of 300rpm, and sieved to obtain micron-sized bismuth telluride-based powder.
[0025] (2) 9-12 kg of polyamic acid precursor was dissolved in DMAc, and the solution was stirred at 60° C. for 2 hours using a magnetic stirrer to ensure that the solution was evenly dispersed and free of particles, thereby obtaining 60 kg of a PAA solution having a concentration of 15-20 wt %.
[0026] (3) Add micron-sized bismuth telluride powder to the PAA solution at a mass ratio of 5wt%, and use ultrasonic treatment for 30 to 60 minutes to ensure that the bismuth telluride powder is evenly dispersed in the solution to avoid particle aggregation. Then add 15g of silane coupling agent surfactant and stir at room temperature for 1 hour to ensure that the solution is evenly mixed.
[0027] (4) The rotation speed is 1500 rpm, and the duration is 30 seconds to obtain a uniform composite film. The coated film composite material is then heated at 80°C for 1 hour to evaporate the solvent; after the solvent evaporates, the material is further heated to 150°C and maintained for 4 hours to convert PAA into PI, thereby achieving complete curing of the polyimide matrix and obtaining a flexible thermoelectric film composite material.
[0028] Example 2
[0029] The preparation method of flexible thermoelectric thin film material can be found in Figure 1 , the specific steps are as follows:
[0030] (1) According to the molar ratio of Bi, Sb and Te raw materials of 0.4:1.6:3, weigh 3000g of pure tellurium, bismuth and antimony element particles as the matrix material and put them into a quartz tube, evacuate until the pressure in the tube is less than 2Pa and seal it. Then put the quartz tube into a tubular heating furnace, set the temperature to 730℃, and heat it to 730℃ at a rate of 10℃ / min under a vacuum of 0.01Pa, keep it warm for at least 6h, and cool it outside the furnace. The high-temperature synthesized material was ball-milled for 30min under an argon protection environment at a speed of 400rpm, and sieved to obtain micron-sized bismuth telluride-based powder.
[0031] (2) 3.75-5 kg of polyamic acid precursor was dissolved in DMAc, and the solution was stirred at 60° C. for 2 hours using a magnetic stirrer to ensure that the solution was evenly dispersed and free of particles, thereby obtaining 25 kg of a PAA solution having a concentration of 15-20 wt %.
[0032] (3) Add micron-sized bismuth telluride powder to the PAA solution at a mass ratio of 12 wt%, and use ultrasonic treatment for 30 to 60 minutes to ensure that the bismuth telluride powder is evenly dispersed in the solution to avoid particle aggregation. Then add 36 g of silane coupling agent surfactant and stir at room temperature for 1 hour to ensure that the solution is evenly mixed.
[0033] (4) The rotation speed is 2300 rpm, and the duration is 30 seconds to obtain a uniform composite film. The coated film composite material is then heated at 80°C for 1 hour to evaporate the solvent; after the solvent evaporates, the material is further heated to 200°C and maintained for 2 hours to convert PAA into PI, thereby achieving complete curing of the polyimide matrix and obtaining a flexible thermoelectric film composite material.
[0034] Example 3
[0035] The preparation method of flexible thermoelectric thin film material can be found in Figure 1 , the specific steps are as follows:
[0036] (1) According to the molar ratio of Bi, Sb and Te raw materials of 0.4:1.6:3, weigh 3000g of pure tellurium, bismuth and antimony element particles as the matrix material and put them into a quartz tube, evacuate until the pressure in the tube is less than 2Pa and seal it. Then put the quartz tube into a tubular heating furnace, set the temperature to 730℃, and heat it to 730℃ at a rate of 10℃ / min under a vacuum of 0.01Pa, keep it warm for at least 6h, and cool it outside the furnace. The high-temperature synthesized material was ball-milled for 30min under an argon protection environment at a speed of 400rpm, and sieved to obtain micron-sized bismuth telluride-based powder.
[0037] (2) 2.25-3 kg of polyamic acid precursor was dissolved in DMAc, and the solution was stirred at 60° C. for 2 hours using a magnetic stirrer to ensure that the solution was evenly dispersed and free of particles, thereby obtaining 15 kg of a PAA solution having a concentration of 15-20 wt %.
[0038] (3) Add micron-sized bismuth telluride powder to the PAA solution at a mass ratio of 20wt%, and use ultrasonic treatment for 30 to 60 minutes to ensure that the bismuth telluride powder is evenly dispersed in the solution to avoid particle aggregation. Then add 60g of silane coupling agent surfactant and stir at room temperature for 1 hour to ensure that the solution is evenly mixed.
[0039] (4) The rotation speed is 3000 rpm, and the duration is 30 seconds to obtain a uniform composite film. The coated film composite material is then heated at 80°C for 1 hour to evaporate the solvent; after the solvent evaporates, the material is further heated to 200°C and maintained for 2 hours to convert PAA into PI, thereby achieving complete curing of the polyimide matrix and obtaining a flexible thermoelectric film composite material.
[0040] The present invention achieves flexibility of the material by embedding micron-sized bismuth telluride powder into a flexible matrix such as polyimide, breaking the limitations of traditional thermoelectric materials in application scenarios, and especially providing an innovative thermal management solution for flexible electronic products, which has certain commercial and technical value.
[0041] In terms of preparation technology, flexible thermoelectric materials are prepared by solution spin coating, which has the advantages of simplified process, low cost and easy large-scale production. It can also adapt to complex curved surfaces and deformation environments, effectively expanding the application prospects of materials and thermoelectric devices.
[0042] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.
Claims
1. A method for preparing a flexible thermoelectric thin film material, characterized in that: The method comprises the following steps: preparing bismuth telluride micron-sized powder and polyamic acid (PAA) solution with a concentration of 15-20wt% respectively, uniformly dispersing the bismuth telluride powder in the polyamic acid (PAA) solution and fully mixing the mixture, and adding a silane coupling agent surfactant to obtain a uniformly mixed solution; then coating the mixed solution on a silicon wafer substrate, controlling the film thickness by spin coating to obtain a composite film, and heating and curing the mixture at a certain temperature to convert the PAA into PI polyimide to obtain a flexible thermoelectric film composite material.
2. The method for preparing a flexible thermoelectric thin film material according to claim 1, characterized in that: in, The preparation method of bismuth telluride micron powder is as follows: three single material raw materials, Sb, Bi and Te, are mixed and then melted in vacuum to obtain an ingot, which is then crushed and ball-milled to obtain bismuth telluride micron powder. The molar ratio of the three single-substance raw materials Bi, Sb and Te is 0.4:1.6:3; the purity of the three single-substance raw materials Bi, Sb and Te is 99.999%.
3. The method for preparing a flexible thermoelectric thin film material according to claim 2, characterized in that: in, The operation of obtaining the ingot by vacuum melting is as follows: the three elements of Bi, Sb and Te are mixed and placed in a graphite crucible, the graphite crucible is placed in a quartz tube, the quartz tube is evacuated and then packaged for vacuum melting, and the vacuum melting conditions are as follows: under a vacuum degree of 0.01 Pa, the temperature is increased to 700-800°C at a rate of 10°C / min, and the temperature is kept for at least 6 hours and then cooled to room temperature; During the pulverization, ball milling is used in an argon protection environment, the rotation speed is set to 300-400 rpm, and the ball milling time is 10-60 minutes to form micron-sized bismuth telluride powder.
4. The method for preparing a flexible thermoelectric thin film material according to claim 1, characterized in that: in, The preparation method of a polyamic acid PAA solution with a concentration of 15 to 20 wt% is as follows: dissolve a polyamic acid precursor in DMAc, heat and stir to form a PAA solution with a concentration of 15 to 20 wt%; wherein the stirring and heating conditions are: stir the solution at 60°C with a magnetic stirrer for 2 hours to ensure that the solution is evenly dispersed and free of particles.
5. The method for preparing a flexible thermoelectric thin film material according to claim 1, characterized in that: in, The process conditions for uniformly dispersing bismuth telluride powder in the PAA solution and fully mixing the powder are as follows: adding micron-sized bismuth telluride powder to the PAA solution at a mass ratio of 5 to 20% wt%, and using ultrasonic treatment for 30 to 60 minutes to ensure that the bismuth telluride powder is uniformly dispersed in the solution and avoid particle aggregation.
6. The method for preparing a flexible thermoelectric thin film material according to claim 1, characterized in that: in, The silane coupling agent surfactant is selected from aminosilane, and the addition amount of the silane coupling agent surfactant is 0.5% to 2% of the mass of the bismuth telluride micron powder; after adding the silane coupling agent surfactant, in order to ensure uniform mixing of the solution, stirring is required at room temperature for 1 hour.
7. The method for preparing a flexible thermoelectric thin film material according to claim 1, characterized in that: in, When preparing the composite material, the rotation speed is 1500-3000 rpm and the duration is 30 seconds to obtain a uniform composite film; then the coated film composite material is heated at 80°C for 1 hour to evaporate the solvent; after the solvent evaporates, the material is further heated to 150-200°C and maintained for 2-4 hours to convert PAA into PI, thereby achieving complete curing of the polyimide matrix and obtaining a flexible thermoelectric thin film composite material.
8. A flexible thermoelectric thin film material, characterized in that: The method is prepared by any one of claims 1 to 7.