Sb7Te / Te doped Bi0.5Sb1.5Te3 thermoelectric thin film and preparation method thereof

Abstract

This invention provides an Sb7Te / Te-doped Bi 0.5 Sb 1.5 This invention relates to the field of thermoelectric thin film technology and its preparation method. The invention utilizes radio frequency sputtering to achieve Sb7Te / Te-doped Bi on a polyimide substrate. 0.5 Sb 1.5 This invention relates to the preparation of Te3 thermoelectric thin films. By adjusting the substrate temperature and sputtering power during the magnetron sputtering process, thin films with high crystallinity and effective doping of the second phase (Te and Sb7Te) are obtained. Significant interface scattering effects and a substantial increase in conductivity are observed, resulting in bismuth telluride-based thin films with excellent thermoelectric properties. This invention uses flexible polyimide as a substrate to prepare Sb7Te / Te-doped Bi... 0.5 Sb 1.5 Te3 thermoelectric films have good flexibility, making them better suited for wearable devices.

Description

Technical Field

[0001] This invention relates to the field of thermoelectric thin film technology, and more particularly to an Sb7Te / Te-doped Bi. 0.5 Sb 1.5 Te3 thermoelectric thin film and its preparation method. Background Technology

[0002] Thermoelectric technology is an all-solid-state energy conversion technology that utilizes the Seebeck effect of materials to convert heat energy into electrical energy under conditions of temperature difference between two ends. It boasts advantages such as simple structure, robustness, durability, no moving parts, and zero noise, and has already been applied in aerospace, marine thermoelectric power generation, and waste heat recovery. It also shows great promise in hot areas such as solar energy utilization, wearable electronics, and sensing. With the advancement of science and technology, high-tech fields such as wearable electronics and sensors have placed new demands on thermoelectric technology, namely, excellent flexibility. Traditional inorganic thermoelectric materials are highly rigid, but combining them with flexible substrates can achieve flexibility.

[0003] In recent years, the excellent properties of commercially available bismuth telluride-based thermoelectric materials have attracted the interest of both academia and industry. Among them, Bi... 0.5 Sb 1.5 Te3 is an effective p-type thermoelectric material and a hexagonal layered compound. If Bi... 0.5 Sb 1.5 If Te3 is made into a two-dimensional thin film material and its room temperature performance is improved, it will be more beneficial to practical wearable devices. Summary of the Invention

[0004] The purpose of this invention is to provide an Sb7Te / Te-doped Bi 0.5 Sb 1.5 Te3 thermoelectric thin films and their preparation methods, including the Sb7Te / Te-doped Bi provided by this invention. 0.5 Sb 1.5 Te3 thermoelectric thin films have excellent thermoelectric properties, making them better suited for wearable devices.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides an Sb7Te / Te-doped Bi 0.5 Sb 1.5 The method for preparing Te3 thermoelectric thin films includes the following steps:

[0007] Bi was sequentially sputtered onto the surface of a flexible polyimide substrate using radio frequency magnetron sputtering. 0.5 Sb 1.5 Te 3+x Alloy target, second sputtering Sb metal target and third sputtering Bi 0.5Sb 1.5 Te 3+x Alloy target, to obtain Sb7Te / Te-doped Bi 0.5 Sb 1.5 Te3 thermoelectric thin film;

[0008] The temperature of the flexible polyimide substrate during the radio frequency magnetron sputtering process is 300–450°C, the power of the first and third sputterings is independently 40–80 W, and the power of the second sputtering is 30–40 W; the Bi 0.5 Sb 1.5 Te 3+x In alloy targets, 0.1≤x≤0.3.

[0009] Preferably, the Bi 0.5 Sb 1.5 Te 3+x The distance between the alloy target and the flexible polyimide substrate is 120–140 mm, and the distance between the Sb metal target and the flexible polyimide substrate is 140–160 mm.

[0010] Preferably, the first sputtering time is 30-45 min, the second sputtering time is 1-5 min, and the third sputtering time is 30-45 min.

[0011] Preferably, the working gas pressure of the radio frequency magnetron sputtering is 0.5 to 1 Pa.

[0012] Preferably, the Bi 0.5 Sb 1.5 Te 3+x The preparation of the alloy target includes the following steps:

[0013] Bi, Sb, and Te were mixed in a molar ratio of Bi:Sb:Te of 0.5:1.5:(3.15-3.35) and ball-milled to obtain an alloy powder. The alloy powder was then subjected to a first hot pressing to obtain Bi. 0.5 Sb 1.5 Te 3+x Alloy target, where 0.1 ≤ x ≤ 0.3.

[0014] Preferably, the temperature of the first hot pressing is 400-500℃, the pressure is 40-60MPa, and the time is 30-40min.

[0015] Preferably, the preparation of the Sb metal target includes the following steps:

[0016] Sb metal is ball-milled to obtain metal powder; the metal powder is then subjected to a second hot pressing to obtain an Sb metal target.

[0017] Preferably, the temperature of the second hot pressing is 400-500℃, the pressure is 40-60MPa, and the time is 30-40min.

[0018] Preferably, before the first sputtering, the flexible polyimide substrate is further cleaned and dried.

[0019] This invention provides a Sb7Te / Te-doped bismuth telluride-based thin film material prepared by the preparation method described above, comprising Bi 0.5 Sb 1.5 Te3 and doping in Bi 0.5 Sb 1.5 Te in Te3 and Sb7Te.

[0020] This invention provides an Sb7Te / Te-doped Bi 0.5 Sb 1.5 The method for preparing Te3 thermoelectric thin films includes the following steps: using radio frequency magnetron sputtering, Bi is sequentially sputtered onto the surface of a flexible polyimide substrate. 0.5 Sb 1.5 Te 3+x Alloy target, second sputtering Sb metal target and third sputtering Bi 0.5 Sb 1.5 Te 3+x Alloy target, to obtain Sb7Te / Te-doped Bi 0.5 Sb 1.5 Te3 thermoelectric thin film; the temperature of the flexible polyimide substrate during the radio frequency magnetron sputtering process is 300-450°C, the power of the first and third sputterings is independently 40-80W, and the power of the second sputtering is 30-40W; the Bi 0.5 Sb 1.5 Te 3+x In alloy targets, 0.1≤x≤0.3.

[0021] This invention achieves Sb7Te / Te-doped Bi on a polyimide substrate using radio frequency sputtering. 0.5 Sb 1.5 The present invention prepares a bismuth telluride-based thin film with excellent thermoelectric properties by adjusting the substrate temperature and sputtering power during the magnetron sputtering process. The film has high crystallinity and is effectively doped with a second phase (referring to Te and Sb7Te). The interface scattering effect is obvious and the conductivity is greatly improved.

[0022] This invention uses flexible polyimide as a substrate to prepare Sb7Te / Te-doped Bi. 0.5 Sb 1.5 Te3 thermoelectric films have good flexibility, making them better suited for wearable devices. Attached Figure Description

[0023] Figure 1 The XRD pattern of the thin film prepared in Comparative Example 1;

[0024] Figure 2 The XRD pattern of the thin film prepared in Example 1;

[0025] Figure 3 SEM image of the thin film prepared in Comparative Example 2;

[0026] Figure 4 SEM image of the thin film prepared in Example 1;

[0027] Figure 5 This is a SEM image of the thin film prepared in Example 2. Detailed Implementation

[0028] This invention provides an Sb7Te / Te-doped Bi 0.5 Sb 1.5 The method for preparing Te3 thermoelectric thin films includes the following steps:

[0029] Bi was sequentially sputtered onto the surface of a flexible polyimide substrate using radio frequency magnetron sputtering. 0.5 Sb 1.5 Te 3+x Alloy target, second sputtering Sb metal target and third sputtering Bi 0.5 Sb 1.5 Te 3+x Alloy target, to obtain Sb7Te / Te-doped Bi 0.5 Sb 1.5 Te3 thermoelectric thin film;

[0030] The temperature of the flexible polyimide substrate during the radio frequency magnetron sputtering process is 300–450°C, the power of the first and third sputterings is independently 40–80 W, and the power of the second sputtering is 30–40 W; the Bi 0.5 Sb 1.5 Te 3+x In alloy targets, 0.1≤x≤0.3.

[0031] Unless otherwise specified, all materials and equipment used in this invention are commercially available products in the field.

[0032] In this invention, the Bi 0.5 Sb 1.5 Te 3+x The preparation of the alloy target preferably includes the following steps:

[0033] Bi, Sb, and Te were mixed in a molar ratio of Bi:Sb:Te of 0.5:1.5:(3.15-3.35) and ball-milled to obtain an alloy powder. The alloy powder was then subjected to a first hot pressing to obtain Bi. 0.5 Sb 1.5 Te 3+x Alloy target, where 0.1 ≤ x ≤ 0.3.

[0034] In this invention, the molar purity of the metals Bi, Sb, and Te is preferably above 99.999%. In this invention, the ball milling speed is preferably 6000–8000 r / min, more preferably 7000–7500 r / min; the time is preferably 20–30 h, more preferably 24–26 h. In this invention, the ball milling is preferably carried out in a stainless steel ball mill jar.

[0035] In this invention, the temperature of the first hot pressing is preferably 400-500°C, more preferably 450-500°C; the pressure of the first hot pressing is preferably 40-60 MPa, more preferably 45 MPa; and the time of the first hot pressing is preferably 30-40 min, more preferably 35 min.

[0036] In this invention, the preparation of the Sb metal target includes the following steps: ball milling of metal Sb to obtain metal powder; and hot pressing of the metal powder to obtain the Sb metal target.

[0037] In this invention, the temperature of the second hot pressing is preferably 400-500°C, more preferably 450-500°C; the pressure of the second hot pressing is preferably 40-60 MPa, more preferably 60 MPa; and the time of the second hot pressing is preferably 30-40 min, more preferably 40 min.

[0038] The present invention does not have any special requirements on the source of the flexible polyimide substrate; any commercially available flexible polyimide known in the art is acceptable.

[0039] Before sputtering, the flexible polyimide substrate is preferably cleaned and dried. In this invention, the cleaning preferably includes ultrasonically cleaning the flexible polyimide substrate sequentially with alcohol and deionized water. This invention does not have special requirements for the power and time of the ultrasonic cleaning; the goal is simply to clean the substrate thoroughly. In this invention, the drying is preferably performed using high-purity nitrogen gas.

[0040] This invention uses flexible polyimide as a substrate to prepare Sb7Te / Te-doped Bi. 0.5 Sb 1.5 Te3 thermoelectric films have good flexibility, making them better suited for wearable devices.

[0041] This invention utilizes radio frequency magnetron sputtering to sequentially sputter Bi onto the surface of a flexible polyimide substrate. 0.5 Sb 1.5 Te 3+x Alloy target, second sputtering Sb metal target and third sputtering Bi 0.5 Sb 1.5 Te 3+x Alloy target, to obtain Sb7Te / Te-doped Bi 0.5 Sb 1.5 Te3 thermoelectric thin film.

[0042] This invention does not impose special requirements on the implementation process of each sputtering step; implementation processes well known in the art can be used. Specifically, this invention preferably uses Bi... 0.5 Sb 1.5 Te 3+x The alloy target and the Sb metal target are installed in the vacuum chamber of the magnetron sputtering equipment, and both targets are connected to the RF power supply. The substrate is mounted on the sample stage, and the vacuum chamber of the vacuum magnetron sputtering equipment is closed. The distance between the two targets and the substrate is adjusted. The mechanical pump and the molecular pump are turned on sequentially to evacuate to 1×10⁻⁶. -3 Pa; Introduce 60 sccm of high-purity argon gas, adjust the working pressure, and pre-sputter for 3-5 minutes; then begin sputtering coating.

[0043] In this invention, the temperature of the flexible polyimide substrate during the radio frequency magnetron sputtering process is 300–450°C, preferably 350–450°C, and more preferably 380–420°C; the power of the first sputtering and the third sputtering are independently 40–80W, preferably 45–55W; the power of the second sputtering is 30–40W, preferably 33–37W, and specifically 30W in the embodiments of this invention.

[0044] In this invention, the Bi 0.5 Sb 1.5 Te 3+x The distance between the alloy target and the flexible polyimide substrate is preferably 120-140 mm, more preferably 120-130 mm; the distance between the Sb metal target and the flexible polyimide substrate is preferably 140-160 mm, more preferably 150-160 mm.

[0045] In this invention, the first sputtering time is preferably 30-45 min, more preferably 35-40 min; the second sputtering time is preferably 1-5 min, more preferably 2-4 min; and the third sputtering time is preferably 30-45 min, more preferably 35-40 min.

[0046] In this invention, the working gas pressure of the radio frequency magnetron sputtering is preferably 0.5 to 1 Pa, more preferably 0.7 to 0.8 Pa.

[0047] This invention provides Sb7Te / Te-doped Bi prepared by the preparation method described above. 0.5 Sb 1.5 Te3 thermoelectric thin films, including Bi 0.5 Sb 1.5 Te3 and doping in Bi 0.5 Sb 1.5 Te in Te3 and Sb7Te.

[0048] This invention achieves Sb7Te / Te-doped Bi on a polyimide substrate using radio frequency sputtering. 0.5 Sb 1.5 The present invention prepares a Te3 thermoelectric thin film by adjusting the substrate temperature and sputtering power in the magnetron sputtering process, resulting in a thin film with high crystallinity and effective doping of the second phase (referring to Te and Sb7Te), obvious interface scattering effect, and significantly improved electrical conductivity, thus preparing a bismuth telluride-based thin film with excellent thermoelectric properties.

[0049] The following examples illustrate the Sb7Te / Te-doped Bi provided by the present invention. 0.5 Sb 1.5 The Te3 thermoelectric thin film and its preparation method are described in detail, but they should not be construed as limiting the scope of protection of this invention.

[0050] Comparative Example 1

[0051] (1) Metal Bi, metal Sb and metal Te with a molar purity of 99.999% were mixed in a stainless steel ball mill jar at a molar ratio of Bi:Sb:Te = 0.5:1.5:3.35 and ball milled for 26 hours at a speed of 7500 r / min to obtain alloy mixed powder.

[0052] (2) The alloy powder mixture is placed in a hot press mold and hot-pressed at a pressure of 45 MPa, a temperature of 500°C, and a time of 35 min to obtain Bi. 0.5 Sb 1.5 Te 3+x (0.1≤x≤0.3) alloy target;

[0053] (3) Change Bi 0.5 Sb 1.5 Te 3+x (0.1≤x≤0.3) The alloy target is installed in the vacuum chamber of the magnetron sputtering equipment, and the target positions are all connected to the radio frequency power supply;

[0054] (4) Before vacuum magnetron sputtering, the flexible polyimide is pretreated. The pretreatment process is as follows: the substrate is placed in a beaker containing alcohol and deionized water in sequence, and ultrasonically cleaned for 20 minutes at 50W power. Then, the substrate is dried with high-purity nitrogen to obtain a clean polyimide substrate.

[0055] (5) Mount the cleaned polyimide substrate onto the sample stage and close the vacuum chamber of the vacuum magnetron sputtering device;

[0056] (6) Adjust Bi 0.5 Sb 1.5 Te 3+x The distance between the alloy target and the polyimide substrate is 130 mm;

[0057] (7) Turn on the mechanical pump and molecular pump in sequence to evacuate to 1×10⁻⁶. -3 Pa;

[0058] (8) Introduce 60 sccm of high-purity argon gas, adjust the working pressure to 0.7 Pa, use RF magnetron sputtering power of 45 W for the alloy target, pre-sputter for 3 min, the deposition temperature is 350 °C, the deposition time is 70 min, and a thin film is obtained.

[0059] The composition and structure of the sputtered film of Comparative Example 1 were analyzed using X-ray diffraction. Analysis of the diffraction images showed that the prepared film mainly exhibited Bi composition. 0.5 Sb 1.5 The Te3 phase contains a significant excess of Te phase, such as Figure 1 As shown.

[0060] Comparative Example 2

[0061] (1) Metallic Bi, metallic Sb, and metallic Te with a molar purity of 99.999% were mixed in a stainless steel ball mill jar at a molar ratio of Bi:Sb:Te = 0.5:1.5:3.15 and ball milled for 24 hours at a speed of 7000 r / min to obtain alloy mixed powder; Metallic Sb with a molar purity of 99.999% was mixed in a stainless steel ball mill jar and ball milled for 26 hours at a speed of 7500 r / min to obtain metal powder;

[0062] (2) The alloy powder mixture is placed in a hot press mold and hot-pressed at a pressure of 45 MPa, a temperature of 450 °C, and a time of 35 min to obtain Bi. 0.5 Sb 1.5 Te 3+x(0.1≤x≤0.3) alloy target; the metal powder is placed in a hot pressing mold and hot pressed at a pressure of 60MPa, a temperature of 400℃, and a time of 40min to obtain an Sb metal target;

[0063] (3) Change Bi 0.5 Sb 1.5 Te 3+x (0.1≤x≤0.3) The alloy target and the Sb metal target are installed in the vacuum chamber of the magnetron sputtering equipment, and the target positions are connected to the radio frequency power supply.

[0064] (4) Before vacuum magnetron sputtering, the flexible polyimide is pretreated. The pretreatment process is as follows: the substrate is placed in a beaker containing alcohol and deionized water in sequence, and ultrasonically cleaned for 20 minutes at 50W power. Then, the substrate is dried with high-purity nitrogen to obtain a clean polyimide substrate.

[0065] (5) Mount the cleaned polyimide substrate onto the sample stage and close the vacuum chamber of the vacuum magnetron sputtering device;

[0066] (6) Adjust Bi 0.5 Sb 1.5 Te 3+x The distance between the alloy target and the polyimide substrate is 120 mm, and the distance between the Sb metal target and the flexible polyimide substrate is adjusted to 160 mm.

[0067] (7) Turn on the mechanical pump and molecular pump in sequence to evacuate to 1×10⁻⁶. -3 Pa;

[0068] (8) Introduce 60 sccm of high-purity argon gas, adjust the working pressure to 0.7 Pa, and sequentially sputter Bi on the surface of the flexible polyimide substrate. 0.5 Sb 1.5 Te 3+x Alloy target, second sputtering Sb metal target and third sputtering Bi 0.5 Sb 1.5 Te 3+x Alloy target, Bi 0.5 Sb 1.5 Te 3+x The alloy target was sputtered with a power of 20W using radio frequency magnetron sputtering, and the Sb metal target was sputtered with a power of 20W using radio frequency magnetron sputtering. The pre-sputtering time was 5 minutes, the deposition temperature was 200℃, the first sputtering time was 45 minutes, the second sputtering time was 2 minutes, and the third sputtering time was 45 minutes, resulting in a thin film.

[0069] The surface morphology of the thin film in Comparative Example 2 was observed using a scanning electron microscope, and the results are as follows: Figure 3As shown, the grains are small with many grain boundaries, and the film quality is obviously low and the distribution is uneven, indicating that the sputtering power and deposition temperature are not suitable, which directly reduces the film quality.

[0070] Example 1

[0071] (1) Metallic Bi, metallic Sb, and metallic Te with a molar purity of 99.999% were mixed in a stainless steel ball mill jar at a molar ratio of Bi:Sb:Te = 0.5:1.5:3.15 and ball milled for 24 hours at a speed of 7000 r / min to obtain alloy mixed powder; Metallic Sb with a molar purity of 99.999% was mixed in a stainless steel ball mill jar and ball milled for 26 hours at a speed of 7500 r / min to obtain metal powder;

[0072] (2) The alloy powder mixture is placed in a hot press mold and hot-pressed at a pressure of 45 MPa, a temperature of 450 °C, and a time of 35 min to obtain Bi. 0.5 Sb 1.5 Te 3+x (0.1≤x≤0.3) alloy target; the metal powder is placed in a hot press mold and hot-pressed at a pressure of 60MPa, a temperature of 500℃, and a time of 40min to obtain an Sb metal target;

[0073] (3) Change Bi 0.5 Sb 1.5 Te 3+x (0.1≤x≤0.3) The alloy target and the Sb metal target are installed in the vacuum chamber of the magnetron sputtering equipment, and the target positions are connected to the radio frequency power supply.

[0074] (4) Before vacuum magnetron sputtering, the flexible polyimide is pretreated. The pretreatment process is as follows: the substrate is placed in a beaker containing alcohol and deionized water in sequence, and ultrasonically cleaned for 20 minutes at 50W power. Then, the substrate is dried with high-purity nitrogen to obtain a clean polyimide substrate.

[0075] (5) Mount the cleaned polyimide substrate onto the sample stage and close the vacuum chamber of the vacuum magnetron sputtering device;

[0076] (6) Adjust Bi 0.5 Sb 1.5 Te 3+x The distance between the alloy target and the polyimide substrate is 120 mm, and the distance between the Sb metal target and the flexible polyimide substrate is adjusted to 160 mm.

[0077] (7) Turn on the mechanical pump and molecular pump in sequence to evacuate to 1×10⁻⁶. -3 Pa;

[0078] (8) Introduce 60 sccm of high-purity argon gas, adjust the working pressure to 0.7 Pa, and sequentially sputter Bi on the surface of the flexible polyimide substrate. 0.5 Sb 1.5 Te 3+x Alloy target, second sputtering Sb metal target and third sputtering Bi 0.5 Sb 1.5 Te 3+x Alloy target, Bi 0.5 Sb 1.5 Te 3+x The alloy target was sputtered with a power of 55W using radio frequency magnetron sputtering, and the Sb metal target was sputtered with a power of 30W using radio frequency magnetron sputtering. The pre-sputtering time was 5 minutes, the deposition temperature was 400℃, the first sputtering time was 45 minutes, the second sputtering time was 2 minutes, and the third sputtering time was 45 minutes, resulting in a thin film.

[0079] The composition and structure of the film sputtered in Example 1 were analyzed using X-ray diffraction. Analysis of the diffraction images confirmed that the main component of the prepared film was Bi. 0.5 Sb 1.5 The Te3 phase contains a significant excess of both Te and Sb7Te phases, such as... Figure 2 As shown. Compared with the XRD of Comparative Example 1, the Te phase content is reduced, and an additional Sb7Te phase is generated, proving that the addition of Sb successfully reacts with Te. The surface morphology of the film of Example 1 was observed by scanning electron microscopy. The grains are small and there are many grain boundaries, such as... Figure 4 As shown.

[0080] Example 2

[0081] (1) Metallic Bi, metallic Sb, and metallic Te with a molar purity of 99.999% were mixed in a stainless steel ball mill jar at a molar ratio of Bi:Sb:Te = 0.5:1.5:3.15 and ball milled for 24 hours at a speed of 7000 r / min to obtain alloy mixed powder; metallic Sb with a molar purity of 99.999% was mixed in a stainless steel ball mill jar and ball milled for 26 hours at a speed of 7500 r / min to obtain metal powder;

[0082] (2) The alloy powder mixture is placed in a hot press mold and hot-pressed at a pressure of 45 MPa, a temperature of 450 °C, and a time of 35 min to obtain Bi. 0.5 Sb 1.5 Te 3+x(0.1≤x≤0.3) alloy target; the metal powder is placed in a hot pressing mold and hot pressed at a pressure of 60MPa, a temperature of 500℃, and a time of 40min to obtain an Sb metal target;

[0083] (3) Change Bi 0.5 Sb 1.5 Te 3+x (0.1≤x≤0.3) The alloy target and the Sb metal target are installed in the vacuum chamber of the magnetron sputtering equipment, and the target positions are connected to the radio frequency power supply.

[0084] (4) Before vacuum magnetron sputtering, the flexible polyimide is pretreated. The pretreatment process is as follows: the substrate is placed in a beaker containing alcohol and deionized water in sequence, and ultrasonically cleaned for 20 minutes at 50W power. Then, the substrate is dried with high-purity nitrogen to obtain a clean polyimide substrate.

[0085] (5) Mount the cleaned polyimide substrate onto the sample stage and close the vacuum chamber of the vacuum magnetron sputtering device;

[0086] (6) Adjust Bi 0.5 Sb 1.5 Te 3+x The distance between the alloy target and the polyimide substrate is 120 mm, and the distance between the Sb metal target and the flexible polyimide substrate is adjusted to 160 mm.

[0087] (7) Turn on the mechanical pump and molecular pump in sequence to evacuate to 1×10⁻⁶. -3 Pa;

[0088] (8) Introduce 60 sccm of high-purity argon gas, adjust the working pressure to 0.8 Pa, and sequentially sputter Bi on the surface of the flexible polyimide substrate. 0.5 Sb 1.5 Te 3+x Alloy target, second sputtering Sb metal target and third sputtering Bi 0.5 Sb 1.5 Te 3+x Alloy target, Bi 0.5 Sb 1.5 Te 3+x The alloy target was sputtered with a power of 55W using radio frequency magnetron sputtering, and the Sb metal target was sputtered with a power of 30W using radio frequency magnetron sputtering. The pre-sputtering time was 5 minutes, the deposition temperature was 450℃, the first sputtering time was 45 minutes, the second sputtering time was 2 minutes, and the third sputtering time was 45 minutes, resulting in a thin film.

[0089] The surface morphology of the thin film in Example 2 was observed using a scanning electron microscope. The film surface was very smooth and dense, showing a hexagonal lamellar structure with enlarged grains and obvious grain boundaries. Figure 5 As shown.

[0090] The room temperature thermoelectric properties of the films prepared in the examples and comparative examples were tested, and the results are shown in Table 1.

[0091] Table 1. Thermoelectric properties of the embodiments and comparative examples at room temperature.

[0092] sample Seebeck coefficient (μV / K) Electrical conductivity (S / m) <![CDATA[Power factor (μW / cm / K 2 )]]> Comparative Example 1 220.26 <![CDATA[6.14×10 3 ]]> 2.98 Comparative Example 2 210.70 <![CDATA[6.91×10 3 ]]> 3.07 Example 1 153.22 <![CDATA[2.20×10 4 ]]> 5.16 Example 2 187.18 <![CDATA[7.97×10 4 ]]> 27.92

[0093] Note: Thermoelectric performance is usually characterized by the dimensionless thermoelectric figure of merit ZT, where ZT = α²σ / κ, where α is the Seebeck coefficient, σ is the electrical conductivity, κ is the thermal conductivity, and α²σ is the power factor.

[0094] As shown in Table 1, the Sb7Te / Te doped Bi in Examples 1 and 2 are... 0.5 Sb 1.5 The thermoelectric properties of the Te3 thin film gradually improve with increasing temperature. The power factor of the thin film prepared in Example 1 is 5.16 μW / cm / K at room temperature. 2 The power factor of the thin film prepared in Example 2 is 27.92 μW / cm / K. 2 This indicates that it has excellent thermoelectric properties. In contrast, the thin films of Comparative Example 1 and Comparative Example 2 have very low electrical conductivity, and therefore poor thermoelectric properties.

[0095] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A Sb7Te / Te-doped Bi 0.5 Sb 1.5 The method for preparing Te3 thermoelectric thin films includes the following steps: Bi was sequentially sputtered onto the surface of a flexible polyimide substrate using radio frequency magnetron sputtering. 0.5 Sb 1.5 Te 3+x Alloy target, second sputtering Sb metal target and third sputtering Bi 0.5 Sb 1.5 Te 3+x Alloy target, to obtain Sb7Te / Te-doped Bi 0.5 Sb 1.5 Te3 thermoelectric thin film; The temperature of the flexible polyimide substrate during the radio frequency magnetron sputtering process is 300–450°C, the power of the first and third sputterings is independently 40–80 W, and the power of the second sputtering is 30–40 W; the Bi 0.5 Sb 1.5 Te 3+x In alloy targets, 0.1≤x≤0.

3.

2. The preparation method according to claim 1, characterized in that, The Bi 0.5 Sb 1.5 Te 3+x The distance between the alloy target and the flexible polyimide substrate is 120–140 mm, and the distance between the Sb metal target and the flexible polyimide substrate is 140–160 mm.

3. The preparation method according to claim 1, characterized in that, The first sputtering time is 30-45 minutes, the second sputtering time is 1-5 minutes, and the third sputtering time is 30-45 minutes.

4. The preparation method according to claim 1 or 3, characterized in that, The working gas pressure of the radio frequency magnetron sputtering is 0.5 to 1 Pa.

5. The preparation method according to claim 1 or 2, characterized in that, The Bi 0.5 Sb 1.5 Te 3+x The preparation of the alloy target includes the following steps: Bi, Sb, and Te were mixed in a molar ratio of Bi:Sb:Te of 0.5:1.5:(3.15-3.35) and ball-milled to obtain an alloy powder. The alloy powder was then subjected to a first hot pressing to obtain Bi. 0.5 Sb 1.5 Te 3+x Alloy target, where 0.1 ≤ x ≤ 0.

3.

6. The preparation method according to claim 5, characterized in that, The temperature of the first hot pressing is 400-500℃, the pressure is 40-60MPa, and the time is 30-40min.

7. The preparation method according to claim 1 or 2, characterized in that, The preparation of the Sb metal target includes the following steps: Sb metal is ball-milled to obtain metal powder; the metal powder is then subjected to a second hot pressing to obtain an Sb metal target.

8. The preparation method according to claim 7, characterized in that, The second hot pressing is performed at a temperature of 400–500°C, a pressure of 40–60 MPa, and a time of 30–40 min.

9. The preparation method according to claim 1 or 3, characterized in that, Prior to the first sputtering, the flexible polyimide substrate is also cleaned and dried.

10. The Sb7Te / Te-doped bismuth telluride-based thin film material prepared by the preparation method according to any one of claims 1 to 9, comprising Bi 0.5 Sb 1.5 Te3 and doping in Bi 0.5 Sb 1.5 Te in Te3 and Sb7Te.

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