Design and fabrication of stretchable conformal thermoelectric devices based on high performance thin film materials

Abstract

This invention relates to the design and fabrication method of a stretchable and shapeable thermoelectric device based on high-performance thin-film materials. First, a regular "paper-cut structure" array pattern is cut into a substrate thin-film material. Then, high-performance p-type and n-type thermoelectric materials are deposited sequentially on the substrate. Finally, electrode materials are deposited to connect the p-type and n-type thermoelectric materials in series. The thin-film thermoelectric device based on the paper-cut structure of this invention can transform from a two-dimensional planar structure to a three-dimensional structure under external force, changing the heat conduction within the device from a planar direction to a vertical direction, maximizing the utilization of the temperature difference between the heat source and the environment, and improving the device's power generation performance. Due to the three-dimensional network structure of the device itself, the cold end of the device can effectively exchange heat with the environment without the need for an additional heat dissipation module. The device structure of this invention is ingeniously designed, with strong compatibility in the fabrication process, and has significant application prospects in the field of wearable self-powered devices.

Description

[0001] This invention belongs to the field of thin-film thermoelectric device technology, specifically relating to the design and fabrication method of a stretchable and shapeable thermoelectric device based on high-performance thin-film materials. Background Technology

[0002] With the advent of the 5G era and the rapid development of network transmission technology, people hope to link all human information through various sensors to achieve "human network connectivity" and monitor human health and behavior in real time. It is predicted that with the increasing aging of the population, the demand for electronic skin devices and chips in establishing wireless health monitoring will grow significantly; by 2025, the global market is expected to reach $1.7 billion. However, how to provide a continuous and stable power supply to microelectronic devices in the Internet of Things (IoT) is a major challenge, and the application and development of thermoelectric generators (TEGs) has become one of the most promising solutions. Most traditional thermoelectric devices are rigid, and their energy conversion efficiency on non-planar heat sources is too low, making them unsuitable for wearable applications. Therefore, there is an urgent need to develop lightweight TEGs with stretching and / or deformation capabilities, enabling them to have good thermal contact with non-planar heat sources without affecting their power generation performance. To achieve this goal, highly flexible organic thermoelectric materials have great application potential; however, these materials have poor thermoelectric properties (low ZT value and conductivity), limiting the power generation performance of the devices. Therefore, using high-performance inorganic thermoelectric materials is a reasonable solution to obtain flexible TEGs with excellent output performance. However, the mechanical rigidity and fragility of traditional inorganic thermoelectric materials hinder their application in flexible thermoelectric devices.

[0003] One direct and effective solution is to employ an island-bridge structure, integrating the bulk n-type and p-type thermoelectric arms together using flexible electrodes such as serpentine electrodes and liquid metal, and encapsulating them with a stretchable elastic substrate. This achieves a device with stretchability that integrates rigid, high-performance inorganic materials. In indoor environments, the temperature difference between human skin and the environment is typically around 10°C. However, due to the low thermal resistance of these devices along the temperature gradient direction, the temperature difference established on the thermoelectric material is only 1–2°C, severely limiting the output power of TEGs under practical operating conditions. Furthermore, thin-film TEGs fabricated on flexible substrates, due to their small size, light weight, and flexibility, can easily adhere to the skin surface and generate electricity using body heat. However, these devices are typically in-plane structures, with heat flow transported along the plane, perpendicular to the actual temperature gradient direction. Therefore, the heat absorption and dissipation structures of the device must be designed, introducing additional interfacial thermal resistance that reduces the device's power generation efficiency. This also further increases the device's weight and volume, which is detrimental to wearable applications. Therefore, achieving good thermal contact between the device and the heat source while ensuring that the heat transfer direction of the thin-film TEGs is the same as the direction of the temperature gradient under actual use conditions is crucial for wearable applications of thermoelectric devices. Zhou et al. reported a flexible TEG inspired by a "leaf" that can directly exchange heat with the environment without an additional heat dissipation module. However, this "leaf" structure TEG lacks flexibility and is difficult to maintain performance during human movement (Advanced Science 2021, 2004947, 1-9). Similarly, a stretchable TEG with a "Lego-like" structure was recently reported, in which prefabricated planar thermoelectric device units are arranged vertically and electrically connected using liquid metal. However, it can only be stretched or bent in one direction and cannot adapt to complex body surfaces (Science Advances 2021, 7, (7), 1-9). Summary of the Invention

[0004] To address the aforementioned problems in the existing technology, this invention provides a design and fabrication method for a stretchable and shapeable thermoelectric device based on high-performance thin film materials.

[0005] The stretchable and shapeable thermoelectric device of this invention is a three-dimensional stretchable thin-film TEG based on a paper-cut structure, which enables the integration of non-stretchable inorganic thermoelectric materials into a stretchable and shapeable device. Under external force, the stretchable and shapeable TEG of this invention transforms from a thin film into a three-dimensional shapeable structure. On one hand, the direction of heat transfer in the TEG changes from in-plane to perpendicular to the plane, aligning with the actual temperature gradient direction, thus improving the device's power generation efficiency. On the other hand, its inherent three-dimensional network structure allows for effective heat exchange between the cold end of the device and the environment, increasing the effective temperature difference between the two ends of the thermoelectric arm and enhancing the device's power generation performance. Furthermore, because the shape of the stretchable and shapeable TEG is variable, it can achieve close contact with non-planar heat sources. The paper-cut structure stretchable TEG of this invention possesses ultra-light weight, high power density, and excellent mechanical reliability, maintaining reliable contact with the skin during human movement without performance loss, and has broad application prospects in body temperature power generation technology.

[0006] The technical solution adopted in this invention is as follows:

[0007] A method for designing and fabricating a stretchable and shapeable thermoelectric device based on high-performance thin film materials includes the following steps:

[0008] (1) Cut out a regular "paper-cut structure" array pattern on the substrate thin film material;

[0009] (2) First deposit p-type thermoelectric material on the substrate after cutting in step (1), then deposit n-type thermoelectric material;

[0010] Electrode material is then deposited on the thin film material after the deposition of the thermoelectric material to connect the p-type thermoelectric material and the n-type thermoelectric material in series.

[0011] The order of operations in steps (1) and (2) can be reversed. That is, p-type thermoelectric material, n-type thermoelectric material and electrode material are deposited sequentially on the substrate thin film material first, and then the whole film is cut.

[0012] In step (1), the substrate film material is a flexible substrate; preferably, the substrate film material is polyimide or fiber paper.

[0013] In step (1), the cutting method is femtosecond laser cutting. Alternatively, a laser cutting machine, a blade cutting machine, or a utility knife can also be used for cutting.

[0014] The structural parameters of the "paper-cut structure" array pattern include cutting length x, cutting interval y, cutting spacing z, characteristic angle θ, and tensile strain ε;

[0015] The relationship between the characteristic angle θ and the tensile strain ε is as follows:

[0016]

[0017] When the characteristic angle reaches its maximum value, the tensile strain also reaches its peak value (ε). MAX ).

[0018] ε MAX The following formula is used to calculate:

[0019]

[0020] Where R1 = x / y, R2 = x / z.

[0021] The relationship between the effective projected area A and the geometric area A0 of the "paper-cut structure" array pattern is expressed as follows:

[0022]

[0023] Along the same column, the cutting length at one end is x / 2, and the cutting interval at the other end is y / 2.

[0024] In step (2), the p-type thermoelectric film is preferably a p-type-Sb2Te3-based thermoelectric film, and the n-type thermoelectric film is preferably an n-type-Bi2Te3-based thermoelectric film.

[0025] The p-type and n-type thermoelectric materials are deposited using a mask-assisted magnetron sputtering deposition method. Alternatively, thermal evaporation, electron beam evaporation, screen printing, or other methods can also be used to deposit the thermoelectric materials.

[0026] In step (2), the electrode material is preferably a Cu / Ti electrode material. First, Ti is deposited, and then Cu is deposited, in order to reduce the contact resistance between the metal film and the thermoelectric material.

[0027] The electrode material is deposited using a mask-assisted magnetron sputtering deposition method. Alternatively, thermal evaporation, electron beam evaporation, or screen printing can also be used to deposit the electrode material.

[0028] The beneficial effects of this invention are as follows:

[0029] The present invention describes a method for designing and fabricating a stretchable and shapeable thermoelectric device based on high-performance thin-film materials. This involves first cutting a regular "paper-cut structure" array pattern onto a substrate thin-film material, then depositing p-type and n-type thermoelectric materials sequentially on the cut substrate, and finally depositing electrode materials on the thin-film material after the thermoelectric materials are deposited, thus connecting the p-type and n-type thermoelectric materials in series. This is because the inventors, through extensive creative work, discovered, inspired by the traditional Chinese art of paper-cutting, that by designing a "paper-cut structure" with a regular array pattern on the thin-film material, a transformation from a thin film to a three-dimensional stretchable structure can be achieved. The stretchability of this three-dimensional structure originates from the structure rather than the constituent materials. Even inelastic materials can be used to fabricate stretchable devices. Therefore, it is possible to integrate non-stretchable inorganic thermoelectric materials into stretchable and shapeable devices. The three-dimensional stretchable thin-film TEG based on a paper-cut structure described in this invention can easily transform from a two-dimensional to a three-dimensional stretchable structure under external force. This changes the heat transfer direction of the device from in-plane to perpendicular to the device, maximizing the utilization of the temperature difference between the heat source and the environment and improving the device's power generation performance. Due to the device's inherent three-dimensional network structure, the cold end of the device can effectively exchange heat with the environment without the need for an additional heat dissipation module. The stretchable TEG based on the paper-cut structure described in this invention has ultra-light weight, high power density, and excellent mechanical reliability. It maintains reliable contact with the skin during human movement without performance loss, and has broad application prospects in body heat power generation technology. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the stretchable and shapeable thermoelectric device based on high-performance thin film material described in Example 1;

[0032] Figure 2 This is a process flow diagram of the fabrication process of the stretchable and shapeable thermoelectric device described in Example 1;

[0033] Figure 3a , 3b These are detailed structural diagrams of the "paper-cut structure" before and after stretching, respectively.

[0034] Figure 4This is a schematic diagram showing the design details of the functional material layer (including p-type thermoelectric material, n-type thermoelectric material, and electrode material) described in Example 1.

[0035] Figure 5 XRD patterns of p-type thermoelectric material Sb2Te3 and n-type thermoelectric material Bi2Te3;

[0036] Figures 6a-6c The surface and cross-sectional morphologies of p-type thermoelectric materials, n-type thermoelectric materials, and Cu / Ti electrodes are shown respectively.

[0037] Figure 7 a-7d is a schematic diagram showing the change of thermoelectric properties of p-type and n-type thermoelectric materials with temperature;

[0038] Figure 8 Detailed design diagram of a single pair of thermoelectric devices;

[0039] Figure 9a A temperature distribution map in the TEG model simulated using the finite element method;

[0040] Figure 9b The graph shows the relationship between the output voltage of the TEG model and the thermal conductivity of p-type and n-type thermoelectric materials.

[0041] Figure 9c The relationship between the temperature difference and output voltage at both ends of the thermoelectric arm of the TEG model and the contact area is shown in the inset (the voltage distribution of a single pair of TEG models is shown).

[0042] Figure 10a The power generation performance of TEG with paper-cut structure at different hot end temperatures;

[0043] Figure 10b This is a schematic diagram showing the changes in open-circuit voltage density and maximum power density as a function of hot-end temperature.

[0044] Figure 11a The output voltage of the TEG device with and without air cooling is shown as a function of stretch ratio under cylindrical and planar heat sources (the bottom shows a side view of the mechanical response of the paper-cut TEG at various stretch ratios).

[0045] Figure 11b The output performance of the TEG in the paper-cut structure under cylindrical, conical, and spherical heat sources;

[0046] Figure 11c Output performance under cylindrical, conical, and spherical heat sources;

[0047] Figures 12a-12c The durability tests were conducted on the TEG paper-cut structure after undergoing multiple strain cycles with a bending radius of 5 mm, a torsion angle of 45°, and a tensile value of 15%. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0049] Example 1

[0050] This embodiment provides a design and fabrication method for stretchable and shapeable thermoelectric devices based on high-performance thin film materials, such as... Figure 1 and Figure 2 As shown, it includes the following steps:

[0051] (1) Using polyimide or fiber paper as a substrate, a regular "paper-cut structure" array pattern is cut out on the substrate film material using a femtosecond laser; the femtosecond laser is an ultrafast pulse laser with a wavelength of 343-1064nm and a pulse width of 200fs-500ps. Figure 3a , 3b As shown, the structural parameters of the "paper-cut structure" array pattern include cutting length x, cutting interval y, cutting spacing z, characteristic angle θ, and tensile strain ε; in this embodiment, cutting length x = 4mm, cutting interval y = 2mm, and cutting spacing z = 1mm;

[0052] The relationship between the characteristic angle θ and the tensile strain ε is as follows:

[0053]

[0054] When the characteristic angle reaches its maximum value, the tensile strain also reaches its peak value (ε). MAX );

[0055] ε MAX The following formula is used to calculate:

[0056]

[0057] Where R1 = x / y, R2 = x / z; R1 and R2 are both dimensionless parameters determined by the characteristics of the cutting pattern; therefore, by increasing the value of R1 and / or decreasing the value of R2, the maximum tensile strain of the paper-cut structure can be further increased.

[0058] The effective area of ​​the paper-cut structure can be obtained by formula (3), which will be used to calculate the power density of the TEG based on the paper-cut structure. The relationship between the projected effective area A of the "paper-cut structure" array pattern and the geometric area A0 is expressed as follows:

[0059]

[0060] In this case, along the same column, the cutting length at one end is x / 2, and the cutting interval at the other end is y / 2; for example... Figure 3a In the first column on the left, the short solid line at the top indicates a cutting length of x / 2, and the uncut section at the bottom of the same column indicates a cutting interval of y / 2. Adjacent cuts are initially neutrally symmetrical, and the number of complete tangents between them is not fixed (≧0). The purpose of this arrangement is to connect the deposited functional material layers in an S-shape (electrically connected).

[0061] (2) Using a mask-assisted magnetron sputtering deposition method, first deposit p-type thermoelectric material Sb2Te3 on the substrate cut in step (1), and then deposit n-type thermoelectric material Sb2Te3; then using a mask-assisted magnetron sputtering deposition method, first deposit Ti electrode material on the thin film material after the thermoelectric material is deposited, and then deposit Cu electrode material, so as to connect the p-type thermoelectric material and the n-type thermoelectric material in series.

[0062] The deposition conditions of the functional material layers (including p-type thermoelectric materials, n-type thermoelectric materials and electrode materials) are shown in Table 1.

[0063] Table 1 - Deposition parameters of functional material layers

[0064]

[0065]

[0066] Furthermore, such as Figure 4 As shown, the deposited functional material layer (including p-type thermoelectric material, n-type thermoelectric material, and electrode material) is inclined relative to the cutting line (dashed line). This is designed to ensure better thermal contact between the hot end of the device and the heat source during actual use, thereby increasing the effective temperature difference between the two ends of the thermoelectric arm and optimizing the point output performance of the TEG. Furthermore, the corners of the functional material layer are chamfered to ensure a more uniform stress distribution within the thin film during mechanical deformation, thus improving the device's mechanical reliability.

[0067] like Figure 5 The XRD patterns of p-type thermoelectric material Sb₂Te₃ and n-type thermoelectric material Bi₂Te₃ are shown. As can be seen from the figures, for the Sb₂Te₃ sample, the peaks along the (0 1 5), (1 0 10), and (1 1 0) directions are stronger than the other peaks. The Bi₂Te₃ sample, on the other hand, shows strong preferential growth along the (0 1 5) plane. These strong and sharp peaks confirm the high crystallinity of the thermoelectric film.

[0068] Surface and cross-sectional morphologies of p-type thermoelectric materials, n-type thermoelectric materials, and Cu / Ti electrodes are as follows: Figures 6a-6c As shown, the film thicknesses are 3.54, 3.46, and 3.98 μm, respectively. The Seebeck coefficient (S), conductivity (σ), and power factor (PF) of p-Sb₂Te₃ and n-Bi₂Te₃ films as a function of temperature are illustrated in the figure. Figure 7 In sections a and 7c, at room temperature, the S of p-Sb₂Te₃ is approximately 146.3 μV / K, while the S of n-Bi₂Te₃ film is -159.6 μV / K; the measured σ of p-Sb₂Te₃ film is approximately 4.73 × 10⁻⁶. 4 The measured value of σ for the S / m n-Bi2Te3 thin film is 5.31 × 10⁻⁶. 4 S / m. Figure 7 Figures b and 7d show the in-plane thermal conductivity (κ) and thermoelectric figure of merit (ZT) of the samples. The κ value of the Sb₂Te₃ film (approximately 0.46 W / m·K) fluctuates slightly and increases with increasing temperature, while the κ value of the Bi₂Te₃ film ranges between 0.67 and 0.92 W / m·K. Compared to the corresponding bulk materials, the κ values ​​of the film materials are much lower, and the microscale effect of the film plays an important role in reducing κ. Based on the above results, the ZT values ​​of p-Sb₂Te₃ and n-Bi₂Te₃ films are calculated to be 0.68 and 0.61, respectively.

[0069] In all cases, the theoretical open-circuit voltage (V) of TEG OC All of these can be estimated using the following formula:

[0070] V OC =N×(S) p -S n )×ΔT (4)

[0071] Where N is the number of thermoelectric arms, S p and S n These are the Seebeck coefficients of the p-type and n-type thermoelectric thin films, respectively. It should be noted that ΔT is the temperature difference across the thermoelectric arm, not the temperature difference applied across the thermoelectric device. ΔT depends not only on the heat flux into the device but also on the thermal resistance of the TEG. Therefore, to investigate the effect of the thermal conductivity κ of Sb₂Te₃ and Bi₂Te₃ thin films on the device V… OC To investigate the effects of thermal conductivity, finite element simulation analysis was conducted to simulate the temperature and potential distribution of the TEG as a function of the thin film thermal conductivity. A pair of thermoelectric arms (including electrodes, p-type thermoelectric material, n-type thermoelectric material, PI substrate, and heat source) in the TEG based on planar paper cutting was created. Detailed parameters and boundary conditions of the model are as follows: Figure 8 As shown, where Figure 8 a, Figure 8Figures b show detailed model designs of the single pair of thermoelectric devices as observed from different perspectives. A heater (copper block, arc-shaped) is placed at the bottom of the PI substrate as a heat source, and the temperature is set to 350K (constant temperature). It is assumed that there is no contact resistance or contact thermal resistance. The boundary conditions for the remaining surfaces are air convection, with a convection coefficient of 5 W / K. -1 ·m -2 The ambient temperature was 293.15 K. The material properties are shown in Table 2.

[0072] Table 2: Set values ​​for material properties in finite element analysis

[0073]

[0074] The finite element method simulated the temperature distribution in the TEG model, such as Figure 9a As shown, a temperature difference of 36°C was established on the thermoelectric arm. Figure 9b The study demonstrates that the VOC of the TEG model increases with the thermal conductivity of the thermoelectric material, specifically as the κ of the Sb₂Te₃ and Bi₂Te₃ films decreases. Furthermore, the invention also investigates the effect of the contact area with the heat source on the output voltage of the paper-cutting TEG; simulation results are shown below. Figure 9c As shown, the temperature difference between the two ends of the thermoelectric arm increases sharply with the increase of the heated area, and then gradually stabilizes; the voltage shows a similar result. With the increase of the thermal contact area, the heat flux flowing through the thermoelectric device increases, and ΔT also increases accordingly. Therefore, increasing the contact area between the device and the heat source can further enhance the voltage of the TEG based on the paper-cut structure. OC .

[0075] As mentioned above, the TEG based on the paper-cut structure exhibits excellent adaptability to various surfaces. At a diameter of 50 mm and a temperature (T... hot The power generation performance of the TEG was measured under a cylindrical heat source with a temperature range of 35-60℃. The ambient temperature (T) was measured during the test. air The temperature was 24.2℃. Based on paper-cut TEG, which is stretched to form a 3D mesh structure, heat can be dissipated directly through convection at the cold end of the paper-cut TEG without the need for an additional heat sink. The test results at a wind speed of 2.5 m / s and a stretch ratio of 15% are shown in Figure 10(a, b). Open-circuit voltage (VOC) and maximum output power (P) are also shown. max With T hot It increases with the increase of T. hot At 60℃, the paper-cutting TEG generates an open-circuit voltage of 201mV and an output power of 7.64μW. The effective area of ​​the device with a stretch ratio of 15% is calculated to be 2.32cm² using formula (3). 2 Therefore, in T hot At 60℃, the open-circuit voltage density is 86.451 mV / cm².2 The power generation density is approximately 3.293 μW / cm³. 2 .

[0076] Thanks to its thin-film deposition process and unique paper-cut structure design, TEG is extremely lightweight, weighing only 29 milligrams. Figure 10b In the middle, both open-circuit voltage density and power generation density increase with T. hot It rises with the increase of T hot At 60℃, the highest open-circuit voltage density is 6.712 V / g, and the maximum power generation density is 255.395 μW / g. It can be predicted that when the mass increases to 150 mg or the area exceeds 11.57 cm², the voltage will increase further. 2 At this time, the VOC and power of the stretchable TEG based on the paper-cut structure can reach ~1V and ~38μW, respectively. In this case, even without a step-up transformer, it can directly power electronic devices in the "Human Body Network," thereby reducing energy loss and production costs during the DC-DC boost conversion process. The paper-cut TEG has the highest power density compared to other similar devices and does not require an additional heat sink during device operation. Furthermore, the paper-cut TEG assembled from high-performance inorganic thermoelectric materials of this invention can be easily bent, twisted, and even stretched, which is difficult to achieve with other flexible TEGs.

[0077] To investigate the adaptability of the paper-cut structure-based TEG to various surfaces, the output voltage of the TEG was measured under planar and bending heat sources and various stretch ratios. During the testing process, T... hot Set to 60℃, with a forced air cooling fan speed of 2.5 m / s. For example... Figure 11a As shown, under a bent heat source, the voltage of a slightly stretched TEG in its initial state is approximately 134 mV. When the TEG is stretched to 15%, the voltage increases significantly to 212 mV, and changes only slightly with further longitudinal stretching to 45%. One of the main reasons is the TEG's unique cut design, which changes the heat transfer direction from lateral to longitudinal. Furthermore, the 3D mesh structure facilitates heat dissipation at the cold end, leading to an increase in ΔT. Similar results can be observed in tests without additional scattering modules, but the output voltage is much lower in this case. Additionally, under forced air cooling conditions, the voltage of the TEG stretched to 15% under a planar heat source is only 127 mV. The TEG achieves a higher output voltage under a bent heat source because the stretched TEG attached to the curved surface has a force towards the central axis, causing the substrate to make close contact with the surface, thereby increasing the contact area between the TEG and the heat source.

[0078] The output voltage of the TEG under cylindrical, conical, and spherical heat sources was tested using beakers, conical flasks, and round-bottom flasks filled with hot water. The dimensions of the glass containers are listed in Table 3, and the results are as follows: Figure 11bAs shown. Under almost identical test conditions (heat source temperatures of 60.4℃, 61.8℃, and 61.4℃), the output voltages of the TEG were 264.3mV, 279.5mV, and 276.1mV, respectively. Since the paper-cutting TEG maintained good contact with the heat source, there was no significant difference in the output performance of the TEG based on various heat source surface shapes. Figure 11c As shown, the paper-cut TEG, when worn on the arm, achieves a voltage of 54 mV, and the calculated output power of the device is 0.58 μW. The output voltage density is then calculated to be 1 mV / pair, which is superior to the performance of existing wearable TEGs. Since wind speeds during human movement are typically around 0-2.5 m / s, the wearable TEG proposed in this invention shows promise for harnessing body heat to power wearable electronic devices.

[0079] Table 3 - Specifications of the glass containers used

[0080]

[0081] Reliability that can adapt to complex real-world deformations is crucial for flexible TEGs. To investigate the mechanical properties of paper-cut TEGs, the changes in internal resistance during bending, torsion, and tension were monitored. The results are as follows: Figures 12a-12c As shown. Figure 12a The results show that the resistance of the paper-cut structure TEG remains stable after undergoing 1000 consecutive bends (bending radius of 5mm), with an internal resistance change of less than 2%. Figure 12b The results show that by rotating one end of the paper-cutting structure TEG at a 45° twist angle, after 1000 cycles of twisting, the change in internal resistance is within 1%, which is negligible. Using the linear elastic limit of human skin as a reference, stretchable devices should maintain function at stretch ratios up to 15%. Figure 12c The results showed the change in internal resistance over 1000 cycles under extreme tensile strain of 15%, with the device's internal resistance increasing by 13%. Because the paper-cut structure maintains very low stress while experiencing large tensile strain, it can also protect the functional membrane to some extent under complex deformation. Furthermore, the invention effectively reduces stress concentration in the film by introducing chamfering at the corners of the functional material layer. Therefore, the paper-cut structure-based TEG demonstrates excellent flexibility and reliability for wearable applications.

[0082] Example 2

[0083] The only difference between this embodiment and Embodiment 1 is that in step (1), a regular "paper-cut structure" array pattern is drawn on the substrate material using a craft knife. All other operations are exactly the same as in Embodiment 1.

[0084] Example 3

[0085] The only difference between this embodiment and Embodiment 1 is that in step (1), a regular "paper-cut structure" array pattern is drawn on the substrate material using a blade cutter. All other operations are exactly the same as in Embodiment 1.

[0086] Example 4

[0087] The only difference between this embodiment and Embodiment 1 is that in step (1), the substrate used is fiber paper (70g A4 paper). All other operations are exactly the same as in Embodiment 1.

[0088] Example 5

[0089] The only difference between this embodiment and Embodiment 1 is that in step (2), n-type thermoelectric material is deposited first, followed by p-type thermoelectric material. All other operations are exactly the same as in Embodiment 1.

[0090] Example 6

[0091] The only difference between this embodiment and Embodiment 1 is that, in step (2), the p-type thermoelectric material deposited on the cut substrate is Bi. 0.5 Sb 1.5 Te3, the deposited n-type thermoelectric material is Bi 0.5 Te 2.7 Se 0.3 The process used was magnetron sputtering, and the deposition parameters are shown in Table 4.

[0092] Table 4 - Deposition parameters of functional material layers

[0093]

[0094] The deposited film was annealed at 300°C for 30 minutes under a nitrogen atmosphere to improve its thermoelectric properties. All other operations were exactly the same as in Example 1.

[0095] Example 7

[0096] The only difference between this embodiment and Embodiment 1 is that in step (2), the electrode material is a platinum electrode, the process used is magnetron sputtering, the deposition power is 120W, the gas pressure is 1.2Pa, the substrate temperature during deposition is room temperature, and the deposition time is 1h. All other operations are exactly the same as in Embodiment 1.

[0097] Example 8

[0098] The difference between this embodiment and Example 1 is only that in step (2), the thermoelectric material film is prepared by screen printing, specifically by fully mixing Bi2Te3 powder, organic binder, dispersant, solvent, and Te-nano solder to prepare Bi2Te3 printing paste. The organic binder is prepared by mixing ethyl cellulose (1g), butyl carbitol acetate (9g), and dibutyl phthalate (2g) under heating and stirring (300rpm) at 80°C until the ethyl cellulose is completely dissolved. It determines the viscosity and rheology of the paste and affects the resolution of the printed film. Tween 80 is used as a dispersant, and butyl carbitol acetate is used as a solvent to adjust the viscosity of the paste. Using the thiol-diamine co-solvent method, Te powder (1g) is dissolved in a co-solvent of ethanethiol (2mL) and ethylenediamine (8mL) at room temperature to prepare Te-nano solder. Stirring is continued until a deep purple solution is produced. Then, acetonitrile (50 mL) was added for sedimentation, and the mixture was centrifuged (10000 rpm, 10 min) to obtain Te-nano solder. Bi2Te3 powder, organic binder, dispersant, and solvent accounted for 80 wt%, 14 wt%, 1 wt%, and 5 wt% of the slurry, respectively. Based on this, Te-nano solder was added to different slurries. The prepared printing slurry was printed onto the PI substrate obtained in step (1) using screen printing technology. Then, it was dried at 150°C for 60 min to slowly remove the solvent from the printed film, and sintered at 400°C for 30 min under N2 atmosphere to obtain the target printed Bi2Te3 film. The Bi2Te3 powder in the above printing process was replaced with an equal amount of Sb2Te3 powder, and the same preparation process was used to obtain the target printed Sb2Te3 film. All other operations were exactly the same as in Example 1.

[0099] Example 9

[0100] The difference between this embodiment and Embodiment 1 is only that in step (2), the thermoelectric material is deposited using mask-assisted electron beam evaporation. Bi₂Te₃ particles and Sb₂Te₃ particles are heated by an electron beam to condense and form a target thin film on the substrate, with the substrate temperature controlled at 350°C and the deposition rate at 10 A / s. In step (2), the electrode material is deposited using mask-assisted thermal evaporation, with the substrate temperature controlled at 350°C and the deposition rate at 10 A / s. All other operations are exactly the same as in Example 1.

[0101] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for fabricating a stretchable and shapeable thermoelectric device based on high-performance thin film materials, characterized in that, Includes the following steps: (1) Cut out a regular "paper-cut structure" array pattern on the substrate thin film material; (2) First deposit p-type thermoelectric material on the substrate cut in step (1), then deposit n-type thermoelectric material; Electrode material is then deposited on the thin film material after the thermoelectric material is deposited, so as to connect the p-type thermoelectric material and the n-type thermoelectric material in series. The structural parameters of the "paper-cut structure" array pattern include cutting length x, cutting interval y, cutting spacing z, characteristic angle θ, and tensile strain ε; The relationship between the characteristic angle θ and the tensile strain ε is as follows: When the characteristic angle reaches its maximum value, the tensile strain also reaches its peak value ε. MAX ; ε MAX The following formula is used to calculate: Where R1 = x / y, R2 = x / z; The relationship between the effective projected area A and the geometric area A0 of the "paper-cut structure" array pattern is expressed as follows: 。 2. The method for fabricating a stretchable and shapeable thermoelectric device based on high-performance thin film materials according to claim 1, characterized in that, In step (1), the substrate thin film material is a flexible substrate.

3. The method for fabricating a stretchable and shapeable thermoelectric device based on high-performance thin film materials according to claim 1, characterized in that, In step (1), the cutting method is femtosecond laser cutting.

4. The method for fabricating a stretchable and shapeable thermoelectric device based on high-performance thin film materials according to claim 1, characterized in that, Along the same column, the cutting length at one end is x / 2, and the cutting interval at the other end is y / 2.

5. The method for fabricating a stretchable and shapeable thermoelectric device based on high-performance thin film materials according to claim 1, characterized in that, In step (2), the p-type thermoelectric material is Sb2Te3 and the n-type thermoelectric material is Bi2Te3.

6. The method for fabricating a stretchable and shapeable thermoelectric device based on high-performance thin film materials according to claim 5, characterized in that, The p-type thermoelectric material and the n-type thermoelectric material are deposited using a mask-assisted magnetron sputtering deposition method.

7. The method for fabricating a stretchable and shapeable thermoelectric device based on high-performance thin film materials according to claim 1, characterized in that, In step (2), the electrode material is Cu / Ti electrode material.

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