A high-density domain structure flexible silver telluride film with reversible regulation of thermoelectric performance and a preparation method thereof

Abstract

This invention belongs to the field of thermoelectric thin film technology, specifically relating to the preparation of a high-density domain-structured flexible silver telluride thin film and its reversible thermoelectric performance control method. The film possesses a high-density strip-like domain structure with numerous twins and stacking faults. The high-density domain boundaries provide a large number of ultra-highly active sites, allowing for wide-range reversible control of thermoelectric performance through simple post-processing methods, such as oxidation annealing, chemical and physical deposition of nano-metal particles. The high-density domain-structured silver telluride thin film prepared by this invention uses a silver film prepared by magnetron sputtering as a precursor, reacting it with tellurium vapor in a tube furnace to generate a dense thin film. The preparation method is simple, low-cost, highly reproducible, and operates at a low reaction temperature, making it suitable for large-scale preparation and compatible with flexible substrates such as polyimide. The high thermoelectric performance and reversible control characteristics of this film are of great significance for applications in high-performance flexible thermoelectric generators and multifunctional sensors.

Description

Technical Field

[0001] This invention belongs to the field of thermoelectric thin film technology, specifically relating to the preparation of a high-density domain structure flexible silver telluride thin film and its reversible thermoelectric performance control method. Background Technology

[0002] In the face of the current energy crisis, thermoelectric materials have attracted much attention due to their ability to convert heat energy into electrical energy. Among them, thermoelectric thin film materials, with their flexibility and small size, are applied in fields such as waste heat collection in irregular structures, flexible wearable devices, and electronic skin. Currently, thermoelectric thin film materials are mainly divided into organic and inorganic thermoelectric thin film materials. Organic thermoelectric thin film materials are usually composed of polymer materials and have the advantages of low cost, light weight, and good flexibility, but their thermoelectric performance and stability are relatively poor. Inorganic thermoelectric thin film materials, on the other hand, usually have high thermoelectric performance but also intrinsic brittleness. Therefore, the development of high-performance flexible inorganic thermoelectric thin film materials remains a challenge. In recent years, superionic conductor thermoelectric materials Ag2 (S, Se, Te) have become a research hotspot in thermoelectric thin film materials due to their metal-like ductility, plastic deformation ability, and phonon liquid-electron crystal characteristics.

[0003] Current research on silver telluride thin films reveals significant gaps in thermoelectric performance compared to bulk materials. Most silver telluride thin films are prepared using silver telluride nanowires or solution reaction methods, resulting in poor crystallinity and mobility. Furthermore, traditional thermoelectric materials exhibit fixed properties, failing to adapt to dynamically changing energy demands. Reversible thermoelectric performance adjustment allows for real-time regulation of power generation efficiency based on energy requirements. Therefore, there is an urgent need to develop a novel method for preparing high-performance flexible silver telluride thin films with reversibly adjustable thermoelectric properties. Summary of the Invention

[0004] To address the aforementioned technical problems, the present invention aims to provide a high-density domain structure flexible silver telluride thin film with reversibly tunable thermoelectric properties and its preparation method. The thermoelectric properties of this film far exceed those of silver telluride thin films reported in the literature, with a wide and reversible performance tuning range. It has significant application value in fields such as thermoelectric engines, flexible wearable devices, and electronic skin, and provides a template for wide-range reversible tuning of thermoelectric materials.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows: A high-density domain-structured flexible silver telluride thin film with reversibly tunable thermoelectric properties is characterized in that: the film is entirely composed of strip-shaped domain structures with a density of 0.0005~10 domains / μm. 2 It contains a large number of twins and stacking faults, with a film thickness of 0.2~2μm and strip-shaped domain structures with a width of 0.1~10μm and a length of 1~200μm.

[0006] The high-density domain-structured flexible silver telluride thin film with reversibly tunable thermoelectric properties is characterized by: an atomic ratio of Ag:Te of 66~69:34~31, and an ultra-high carrier mobility of 5000~9000 cm⁻¹. 2 / V s, power factor 9~25μW cm -1 K -2 .

[0007] The high-density domain-structured flexible silver telluride thin film with reversibly tunable thermoelectric properties is characterized in that: the thermoelectric properties of the high-density domain-structured silver telluride can be reversibly tunable through oxidation annealing, with an annealing temperature of 100~400℃, an annealing time of 0.5~4h, and an adjustable carrier concentration range of 0.7~4×10⁻⁶. 18 cm -3 Electrical conductivity adjustable from 500 to 2600 S / cm, and mobility adjustable from 4000 to 6500 cm⁻¹. 2 / V s, Seebeck coefficient -80~-130μV / K.

[0008] The reversible control is characterized in that: after oxidation annealing, the high-density domain structure silver telluride film can be reversibly restored to its original thermoelectric properties before oxidation annealing by annealing in a reducing atmosphere, with an annealing temperature of 200~400℃ and an annealing time of 0.5~4h.

[0009] The high-density domain-structured flexible silver telluride thin film with reversibly tunable thermoelectric properties is characterized by the reversible tunability of its thermoelectric properties through solution disproportionation reaction or magnetron deposition of nano-metal particles on the film surface. For example, it can be reacted with an acetone solution of tetra(acetonitrile)copper(I)hexafluorophosphate at 50°C for 0.5-20 minutes, or gold, silver, copper, platinum, nickel, and other nano-metal particles can be deposited by magnetron sputtering at room temperature for 5-60 seconds, with a DC current power of 10-20 W, a gas pressure of 0.2-2 Pa, and an adjustable carrier concentration range of 0.7-3.5 × 10⁻⁶. 18 cm -3 Electrical conductivity adjustable from 700 to 3000 S / cm, and mobility adjustable from 5000 to 9000 cm⁻¹. 2 / V s, Seebeck coefficient -100~-130μV / K.

[0010] The reversible regulation is characterized in that: after the thermoelectric properties of the high-density domain structure silver telluride film are regulated by depositing nano-metal particles on the surface, the surface nano-metal particles can be removed by dilute hydrochloric acid or other solutions to reversibly restore the original thermoelectric properties before regulation, with a concentration of 5~20% and a time of 1min~5min.

[0011] The high-density domain structure flexible silver telluride thin film with reversibly tunable thermoelectric properties is characterized by the fact that the large number of highly active sites provided by high-density domain boundaries, twin boundaries, and stacking faults are the key to achieving reversibly tunable high thermoelectric properties.

[0012] The high-density domain-structured flexible silver telluride thin film with reversibly tunable thermoelectric properties is characterized in that: the high-density domain-structured silver telluride thin film is prepared by magnetron sputtering on a flexible or rigid substrate to serve as a precursor, and then reacted with Te vapor in a tube furnace. The specific preparation steps are as follows: (1) Substrate cleaning The polyimide, quartz wafer, or silicon wafer is ultrasonically cleaned in sequence with acetone, ethanol, and deionized water for 20-40 minutes, and then dried with nitrogen before use.

[0013] (2) Preparation of precursor silver film After pre-sputtering the silver target for 10–30 minutes, the cleaned substrate is placed on a stainless steel sample stage and then placed into the magnetron sputtering system chamber, with a background vacuum of 1–5 × 10⁻⁶. -5 Pa, working gas pressure 0.2~2Pa, sputtering temperature at room temperature, sputtering time 6min~50min, DC sputtering power 30~90W, sample stage rotation speed 10~20r / min, silver film thickness 0.2~2μm.

[0014] (3) Tubular furnace tellurization reaction Weigh 20-200 mg of high-purity tellurium powder and place it at the left end of the tube furnace. Then, fix the prepared silver film attached to the substrate onto a glass slide, with the silver film side up, and place it at the right end of the tube furnace, 7-10 cm apart. The background vacuum degree is 1-5 × 10⁻⁶. -4 At a working pressure of 20-30 Pa, argon gas at 30-50 sccm is introduced from the left side as a carrier gas, while a mechanical pump is connected to the right side to remove the carrier gas. The carrier gas is kept open throughout the process. During heating, the temperature is first increased to 300-400℃ at a rate of 10-20℃ / min, and then increased to 400-500℃ at a rate of 3-5℃ / min. A temperature difference of 50℃ is maintained between the two heating stages. After holding at this temperature for 10-30 minutes, the temperature is cooled with the furnace to obtain a uniform and dense high-density domain-structured silver telluride thin film.

[0015] The method for preparing a high-density domain structure flexible silver telluride thin film with reversibly tunable thermoelectric properties has a low preparation temperature, is compatible with flexible polyimide substrates, and is free from substrate effects.

[0016] The thin film of this invention possesses a high-density strip-like domain structure with numerous twins and stacking faults. The high-density domain boundaries provide a large number of ultra-highly active sites, allowing for wide-range reversible control of thermoelectric properties through simple post-processing methods, such as oxidation annealing, chemical and physical deposition of nanoscale metal particles. The high-density domain-structured silver telluride thin film prepared by this invention uses a silver film prepared by magnetron sputtering as a precursor, reacting it with tellurium vapor in a tube furnace to form a dense film. The preparation method is simple, low-cost, highly reproducible, and operates at a low reaction temperature, making it suitable for large-scale preparation and compatible with flexible substrates such as polyimide. The high thermoelectric properties and reversible controllability of this film are of great significance for applications in high-performance flexible thermoelectric generators and multifunctional sensors.

[0017] The design concept of this invention is as follows: The preparation of silver telluride thin films often exhibits relatively low thermoelectric properties due to the influence of the preparation method. To obtain high-performance silver telluride thin films, a preparation method similar to the bulk preparation process was designed. Silver telluride thin films were prepared by tellingurization of a precursor silver film in a tube furnace. The reaction was thorough, and the transition from a high-temperature phase to a low-temperature phase generated compressive stress, resulting in a large number of strip-shaped domain boundaries, deformation twins, and stacking faults. These phenomena, while scattering phonons, exhibit weak scattering of charge carriers, thus achieving ultra-high mobility. Simultaneously, these domain boundaries, deformation twins, and stacking faults also provide a large number of high-density active sites, which undergo charge transfer under the influence of oxygen, nano-metal particles, and other substances, thereby reversibly modulating the thermoelectric properties.

[0018] The advantages and beneficial effects of this invention are as follows: 1. The method for preparing high-density domain structure silver telluride thin films of the present invention is simple, has a low preparation temperature, is not affected by substrate effects, and is compatible with flexible substrates.

[0019] 2. This invention prepares a silver telluride thin film with high-density domain boundaries, twin boundaries, stacking faults, and other highly active sites through the tellurization reaction of a precursor silver film, exhibiting an ultra-high carrier mobility of 5000~9000 cm⁻¹. 2 / V s, power factor 9~25μWcm -1 K -2 .

[0020] 3. This invention enables reversible control of thermoelectric properties over a wide range by oxidative annealing and chemical or physical deposition of nano-metal particles on high-density domain-structured silver telluride thin films. Attached Figure Description

[0021] Figure 1 These are the electron backscattering diffraction (EBSD) analysis results of the strip-like domain structure in the silver telluride thin film prepared in this invention.

[0022] Figure 2These are the results of high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) analysis of the twin structure in the silver telluride thin film prepared in this invention.

[0023] Figure 3 These are the results of high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) analysis of the stacking faults and nanotwin structures in the silver telluride thin film prepared in this invention.

[0024] Figure 4 This is a schematic diagram of the tubular furnace tellurization reaction in the preparation of silver telluride thin films according to the present invention.

[0025] Figure 5 This invention presents the analysis results of the thermoelectric properties of silver telluride thin films prepared by this invention as a function of oxidation annealing temperature and their reversible controllability.

[0026] Figure 6 This invention presents the results of the analysis of the thermoelectric properties of silver telluride thin films prepared by the present invention as a function of disproportionation reaction and Cu deposition time, and the results of reversible controllability.

[0027] Figure 7 This invention presents the results of the analysis of the thermoelectric properties of silver telluride thin films prepared by the present invention as a function of magnetron sputtering deposition time of Cu, and the results of reversible controllability.

[0028] Figure 8 The results are obtained by scanning electron microscopy (SEM) analysis of columnar silver telluride thin films prepared in Example 6 of this invention using a method inconsistent with the preparation method of this invention. Detailed Implementation

[0029] In the specific implementation process, the precursor silver film prepared by magnetron sputtering in this invention undergoes a full tellurization reaction with tellurium vapor in a tube furnace to prepare a high-density strip-shaped domain structure silver telluride thin film with high thermoelectric performance. The film thickness is 0.2~2μm, the strip-shaped domain structure is 0.1~10 μm wide and 1~200 μm long, and the atomic ratio is Ag:Te=66~69:34~31. Simultaneously, due to the presence of highly active sites such as high-density domain boundaries, twins, and stacking faults, the film can undergo charge transfer under the influence of substances such as oxygen and nano-metal particles. Furthermore, when the modulating substances are removed by means of reduction annealing, acid treatment, etc., the charge will transfer again in reverse, thus achieving reversible control.

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0031] Example 1 This invention discloses a method for preparing a high-density domain-structured flexible silver telluride thin film and its reversible thermoelectric property control, illustrated by an example of reversible control via oxidation annealing. The high-density domain-structured silver telluride thin film is prepared by magnetron sputtering on a flexible or rigid substrate, using a silver film as a precursor, followed by reaction with Te vapor in a tube furnace. Figure 1 The EBSD analysis results of the thin film show that it is entirely composed of strip-like domain structures with a density of 0.0005–10 domains / μm. 2 The strip-like domain structures are 0.1–10 μm wide and 1–200 μm long; further microstructural analysis revealed the presence of multi-scale twins (such as…). Figure 2 and Figure 3 As shown, the two crystal planes are arranged in a mirror-symmetric manner along the twin plane) and stacking faults (such as... Figure 3 As shown, an abnormal atomic layer stacking (size 1nm~10μm) is introduced into the normal stacking sequence of the crystal, with the smallest size being only 3 atomic layers (less than 1nm). The specific steps include: (1) Substrate cleaning 16mm area 2 The flat polyimide substrate (Kapton HN) was ultrasonically cleaned with acetone, ethanol and deionized water for 25 minutes in sequence, and then dried with nitrogen for later use.

[0032] (2) Preparation of precursor silver film After 30 minutes of pre-sputtering on the silver target, the cleaned substrate was placed on a stainless steel sample stage and then placed into the magnetron sputtering system chamber with a background vacuum of 5 × 10⁻⁶. -5 Pa, working gas pressure 0.68 Pa, sputtering temperature room temperature, sputtering time 25 min, DC sputtering power 90 W, sample stage speed 20 r / min, silver film thickness 0.8 μm.

[0033] (3) Tubular furnace tellurization reaction like Figure 4 As shown, 100 mg of high-purity tellurium powder was weighed and placed at the left end of the tube furnace. Then, the edges of the prepared silver film attached to the substrate were fixed to the glass slide using polyimide high-temperature tape (Shenzhen Runhai Electronics Co., Ltd. RH8423). The silver film was placed face up at the right end of the tube furnace, with a 7 cm distance between the tellurium powder and the silver film. The background vacuum was 5 × 10⁻⁶. -4 Argon gas at 40 sccm was introduced from the left side as the carrier gas, while a mechanical pump was connected to the right side to remove the carrier gas. The working pressure was 28 Pa, and the carrier gas was kept open throughout the process. During tubular furnace heating, the temperature was first increased to 400℃ at a rate of 15℃ / min, then increased to 450℃ at a rate of 5℃ / min. After holding at this temperature for 20 min, the furnace was cooled to room temperature, resulting in a high-density domain-structured silver telluride film with a thickness of 0.98 μm, a Seebeck coefficient of -115 μv / k, and a carrier concentration of -0.79 × 10⁻⁶.18 cm -3 The conductivity is 741 S cm. -1 The migration rate was 5867 cm. 2 / V s.

[0034] The atomic ratio of the domain-structured silver telluride thin film is Ag:Te = 68:32.

[0035] The thermoelectric properties are then reversibly controlled by oxidation annealing (in air), such as... Figure 5 As shown, with the annealing temperature increasing from 100℃ to 300℃, the carrier concentration and conductivity increase significantly, the Seebeck coefficient and migration initially increase and then decrease, and the thermoelectric power factor increases significantly. After annealing at 300℃ for 0.5h, the Seebeck coefficient is -90μv / k and the carrier concentration is -3.25×10⁻⁶. 18 cm -3 The conductivity is 2313 S / cm. -1 The mobility is 4442 cm. 2 / V s. Furthermore, annealing at 300℃ for 2 hours in a reducing atmosphere (a hydrogen-argon mixture with a volume content of 5% H2) restores the silver telluride film to its original state, with a Seebeck coefficient of -107 μV / k and a carrier concentration of -0.739 × 10⁻⁶. 18 cm -3 The conductivity is 621 S / cm. -1 The mobility is 5246 cm. 2 / V s. All thin film properties were characterized by measuring the Seebeck coefficient of the thin films using a Seebeck coefficient tester, and measuring conductivity, mobility, and carrier concentration using a Hall effect testing system (van der Bauer method).

[0036] Example 2 The silver telluride thin film prepared in Example 1 differs in that the reversible control method after preparation involves placing the silver telluride thin film in an acetone solution of 20 mmol / L tetra(acetonitrile)copper(I)hexafluorophosphate at 50°C for 5 min, 10 min, and 20 min. During this reaction, monovalent copper ions undergo a disproportionation reaction to generate divalent copper ions and elemental copper. The thermoelectric properties of the silver telluride thin film after Cu deposition are improved compared to the original silver telluride thin film. Figure 6 As shown, the mobility, in particular, exceeds the values ​​reported in the literature for silver telluride (the Seebeck coefficient of the sample treated for 5 min is -106 μV / K, and the carrier concentration is -1.91 × 10⁻⁶). 18 cm -3 The conductivity is 2442 S / cm. -1 The migration rate is 7962 cm. 2 / V s), but the thermoelectric performance began to decline with increasing reaction time (the Seebeck coefficient of the sample treated for 20 min was -121 μV / K, and the carrier concentration was -1.06 × 10⁻⁶). 18 cm -3 The conductivity is 1062 Scm -1 The migration rate is 6277 cm. 2 Similarly, after immersing in 5% dilute hydrochloric acid at room temperature for 3 minutes to remove surface copper, the silver telluride film returned to its original state (the Seebeck coefficient of the hydrochloric acid-treated sample was -102 μV / K, and the carrier concentration was -0.7 × 10⁻⁶). 18 cm -3 The conductivity is 608 S cm⁻¹ -1 The mobility is 5412 cm. 2 / V s).

[0037] Example 3 The silver telluride thin film prepared in Example 1 differs in that the reversible control method after preparation involves depositing copper nanoparticles on the surface of the silver telluride thin film using magnetron sputtering at room temperature. A DC power supply with a power of 15W and a background vacuum of 5×10⁻⁶ is used. -5 Pa, working air pressure 0.65Pa, such as Figure 7 As shown, with the deposition time increasing from 5 s to 40 s, the conductivity and carrier concentration continuously increase, while the Seebeck coefficient and mobility change relatively little. Therefore, the thermoelectric power factor is significantly improved (the Seebeck coefficient of the sample with a deposition time of 40 s is -86 μV / K, and the carrier concentration is -2.86 × 10⁻⁶). 18 cm -3 The conductivity is 2871 S / cm. -1 The mobility is 6263 cm. 2 Similarly, after immersing the silver telluride film in 5% dilute hydrochloric acid at room temperature for 3 min to remove the surface copper nanoparticles, the silver telluride film returned to its original state (the Seebeck coefficient of the hydrochloric acid-treated sample was -113 μV / K, and the carrier concentration was -0.862 × 10⁻⁶). 18 cm -3 The conductivity is 737 S cm. -1 The migration rate was 5333 cm. 2 / V s).

[0038] Example 4 The implementation steps (process and conditions) are the same as in Example 1, except that the tubular furnace heating is first applied at a heating rate of 15°C / min to 450°C, then at 5°C / min to 500°C, held at that temperature for 20 min, and then cooled to room temperature with the furnace. This yields a high-density domain-structured silver telluride film with a thickness of 0.98 μm, a Seebeck coefficient of -110 μV / K, and a carrier concentration of -0.773 × 10⁻⁶. 18 cm -3 The conductivity is 686 S cm⁻¹ -1 The migration rate was 5533 cm. 2 / V s.

[0039] The film is entirely composed of strip-like domain structures with a density of 0.0005~10 domains / μm. 2 The strip-shaped domain structure is 0.1~10μm wide and 1~200μm long; further microstructure analysis revealed the presence of multi-scale twins and stacking faults (size 1nm~10μm), with the smallest size being only 3 atomic layers (less than 1nm).

[0040] The atomic ratio of the domain-structured silver telluride thin film is Ag:Te = 67.8:32.2.

[0041] Example 5 The implementation steps (process and conditions) are the same as in Example 1, except that the sputtering time during silver film preparation is 10 min, the silver film thickness is 320 nm, the silver telluride film thickness is 400 nm, the Seebeck coefficient is -121 μV / K, and the carrier concentration is -0.835 × 10⁻⁶. 18 cm -3 The conductivity is 729 S cm. -1 The migration rate is 5447 cm. 2 / V s.

[0042] The film is entirely composed of strip-like domain structures with a density of 0.0005~10 domains / μm. 2 The strip-shaped domain structure is 0.1~10μm wide and 1~200μm long; further microstructure analysis revealed the presence of multi-scale twins and stacking faults (size 1nm~10μm), with the smallest size being only 3 atomic layers (less than 1nm).

[0043] The atomic ratio of the domain-structured silver telluride thin film is Ag:Te = 66.4:33.6.

[0044] Example 6 The implementation steps (process and conditions) are the same as in Example 1, except that the tellurium powder and silver film are heated independently in different temperature zones. In the tube furnace heating, the zone containing the silver film is first heated to 450°C at a heating rate of 15°C / min and held for 75 minutes. After 64 minutes, when the temperature of the silver film zone reaches 450°C, the temperature of the tellurium powder zone is heated to 400°C at a heating rate of 15°C / min and held for 15 minutes before being cooled with the furnace, resulting in the following... Figure 8 The columnar silver telluride thin film shown has a length of 0.5–1 μm and a width of 100–500 nm. It exhibits numerous pores and poor film continuity, with an atomic ratio of Ag:Te = 68.4:31.6. Its Seebeck coefficient is -99 μV / K, and its carrier concentration is -0.823 × 10⁻⁶. 18 cm -3 The conductivity is 426 S cm⁻¹ -1 The migration rate is 3236 cm. 2 / V s. Meanwhile, the Seebeck coefficient after annealing at 300℃ for 2 hours in air was -95 μv / k, and the carrier concentration was -2.88 × 10⁻⁶. 18 cm -3 The conductivity is 1121 Scm -1 The migration rate is 2427 cm. 2 / V s, columnar silver telluride films without domain structures have significantly lower performance than silver telluride films with domain structures, and their performance cannot be reversibly controlled.

[0045] The results show that the high-density domain structure flexible silver telluride thin film with reversible thermoelectric performance of the present invention has excellent thermoelectric performance, a wide adjustable range, reversible control, and good repeatability. It can meet the different thermoelectric performance requirements of various complex application scenarios, such as power generation, cooling and sensing in oxygen-containing environments. At the same time, its reversible controllability is expected to be applied to functional devices such as flexible sensors, such as as a resettable oxygen sensor, which has good industrial application prospects and basic scientific research value.

[0046] The above description is only a preferred embodiment of the present invention and is not intended to limit the ideas of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-density domain structure flexible silver telluride thin film with reversibly tunable thermoelectric properties, characterized in that: The film is entirely composed of strip-like domain structures with a density of 0.0005~10 domains / μm. 2 (Preferred concentration: 0.1~10 particles / μm) 2 More preferably 5~10 per μm 2 The film thickness is 0.2~2μm, the strip domain structure is 0.1~10μm wide and 1~200μm long; the atomic ratio of the domain structure silver telluride film is Ag:Te=66~69:34~31 (preferably 67~68:33~32, more preferably 68:32).

2. The thin film as described in claim 1, characterized in that: It contains multi-scale twins and stacking faults (size 1nm~10μm) and exhibits ultra-high carrier mobility of 5000~9000 cm⁻¹. 2 / V s, power factor 9~25μW cm -1 K -2 .

3. The thin film as described in claim 1, characterized in that: High-density domain-structured silver telluride can have its thermoelectric properties (Seebeck coefficient, carrier concentration, conductivity, and mobility) reversibly controlled by oxidative annealing (conducted in an oxygen-containing atmosphere with an oxygen volume content of 1%–100% (preferably 5%–40%, more preferably 20%–30%), and the remaining gas being nitrogen or one or more inert gases, such as air). The annealing temperature is 100–400 °C, the annealing time is 0.5–4 h, and the adjustable range of carrier concentration is 0.7–4 × 10⁻⁶. 18 cm -3 Electrical conductivity adjustable from 500 to 2600 S / cm, and mobility adjustable from 4000 to 6500 cm⁻¹. 2 / V s, Seebeck coefficient -80~-130μV / K.

4. The thin film as described in claim 3, characterized in that: After oxidation annealing, high-density domain-structured silver telluride films can be reversibly restored to their original thermoelectric properties before oxidation annealing by annealing in a reducing atmosphere (containing hydrogen with a hydrogen volume content of 1% to 100% (preferably 5% to 20%, more preferably 5% to 10%), and the remaining gas can be one or more of nitrogen or inert gases). The annealing temperature is 200 to 400°C and the annealing time is 0.5 to 4 hours.

5. The high-density domain structure flexible silver telluride thin film with reversibly tunable thermoelectric properties as described in claim 1, characterized in that: High-density domain structure silver telluride can have its thermoelectric properties reversibly modulated by depositing nano-metal particles on the surface of thin films via solution disproportionation reaction or magnetron deposition. For example, solution disproportionation reaction: contact with an acetone solution of tetra(acetonitrile)copper(I)hexafluorophosphate (10 mmol / L~30 mmol / L) at 40℃~60℃ for 0.5 min~20 min; Magnetron sputtering of one or more nano-metal particles, such as gold, silver, copper, platinum, and nickel, at room temperature. The magnetron sputtering time is 5 s to 60 s, the DC current power of the magnetron sputtering target is 10 W to 20 W, the gas pressure is 0.2 to 2 Pa, and the carrier concentration is adjustable from 0.7 to 3.5 × 10⁻⁶. 18 cm -3 The conductivity is adjustable from 700 to 3000 S / cm, and the mobility is adjustable from 5000 to 9000 cm. 2 / V s, Seebeck coefficient -100~-130μV / K.

6. The thin film as described in claim 5, characterized in that: After high-density domain-structured silver telluride thin films are deposited with nano-metal particles on the surface to regulate their thermoelectric properties, the surface nano-metal particles can be removed by immersion in dilute hydrochloric acid or other solutions at room temperature, and the original thermoelectric properties before regulation can be reversibly restored. The mass concentration of dilute hydrochloric acid is 5~20%, and the immersion time is 1min~5min.

7. The high-density domain structure flexible silver telluride thin film with reversibly tunable thermoelectric properties as described in any one of claims 1 to 6, characterized in that: High-density domain boundaries, twin boundaries, and stacking faults provide a large number of highly active sites, which are key to achieving reversible control of high thermoelectric performance. It has a low preparation temperature, is compatible with flexible polyimide substrates, and is not affected by substrate effects.

8. A method for preparing a high-density domain structure flexible silver telluride thin film with reversibly tunable thermoelectric properties as described in any one of claims 1-7, characterized in that: High-density domain-structured silver telluride thin films are prepared by magnetron sputtering onto flexible substrates (such as polyimide) or rigid substrates (such as quartz wafers or silicon wafers) to create a silver film as a precursor, which is then reacted with Te vapor in a tube furnace. The specific preparation steps are as follows: (1) Substrate cleaning The substrate was ultrasonically cleaned sequentially with acetone, ethanol and deionized water for 20-40 minutes, and then dried for later use. (2) Preparation of precursor silver film A silver film with a thickness of 0.2~2μm (preferably 0.8~1.2μm, more preferably 1μm) is sputtered onto the substrate using a silver target. (3) Tubular furnace tellurization reaction Weigh 20-200 mg of high-purity tellurium powder and place it at the left end of a tube furnace. Then, fix the prepared silver film attached to the substrate onto a glass slide, with the silver film facing upwards, and place it at the right end of the tube furnace. The distance between the tellurium powder and the silver film should be 5-12 cm (preferably 7-10 cm, more preferably 8-9 cm). The background vacuum degree should be 1-5 × 10⁻⁶. -4 Argon gas at a pressure of 20-60 sccm (preferably 30-50 sccm, more preferably 35-45 sccm) is introduced from the left side of the tubular furnace to act as a carrier gas, while a mechanical pump is connected to the right side to remove the carrier gas. The working pressure is 10-40 Pa (preferably 20-30 Pa, more preferably 24-28 Pa), and the carrier gas is kept open throughout the process. When heating in the tubular furnace, the temperature is first raised to 300-500℃ (preferably 350-450℃, more preferably 350-450℃) at a heating rate of 5-25℃ / min (preferably 10-20℃ / min, more preferably 14-16℃ / min). The temperature is preferably 380~420℃, then heated to 350~550℃ (preferably 400~500℃, more preferably 430~470℃) at a rate of 1~10℃ / min (preferably 3~7℃ / min, more preferably 4~6℃ / min). A temperature difference of 30-100℃ (preferably 40~80℃, more preferably 45~50℃) is maintained between the two heating stages. The temperature is held for 5~40min (preferably 10~30min, more preferably 15~25min) and then cooled in the furnace to obtain a uniform and dense high-density domain structure silver telluride film.

9. The preparation method according to claim 8, characterized in that: The specific process for preparing the precursor silver film in step (2) is as follows: After pre-sputtering the silver target for 10–30 minutes, the cleaned substrate is placed on the sample stage and then placed into the magnetron sputtering system chamber, with a background vacuum of 1–5 × 10⁻⁶. -5 Pa, working gas pressure 0.2~2Pa, sputtering temperature at room temperature, sputtering time 6min~50min, DC sputtering power 30~90W, sample stage rotation speed 10~20r / min, silver film thickness 0.2~2μm.

10. The preparation method according to claim 8, characterized in that: Base area 1~25mm 2 .

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