An ultra-high preferentially oriented flexible Cu x Se thermoelectric thin film and its preparation method and application

Abstract

The present invention discloses an ultra-high preferentially oriented flexible Cu x Se thermoelectric film and its preparation method and application, wherein the ultra-high preferential orientation flexible Cu x The preparation method of Se thermoelectric film includes the following steps: providing a flexible substrate; using Cu2Se alloy target and Cu target to perform magnetron co-sputtering on the flexible substrate, and then performing heat treatment to prepare ultra-high preferential orientation flexible Cu x Se thermoelectric film, wherein the value of x ranges from 0.5 to 2.5. The present invention adopts Cu2Se alloy target and Cu target, and uses magnetron co-sputtering method to prepare flexible Cu with ultra-high (0l0) orientation and excellent thermoelectric performance on a high temperature resistant flexible substrate. x Se thermoelectric film. The preparation method provided by the present invention is simple to operate, low in cost, and easy to control the composition and growth orientation of the thermoelectric film. The prepared flexible Cu x Se thermoelectric films have high quality, good thermoelectric performance, good repeatability, and can be produced on a large scale industrially.

Description

Technical Field

[0001] The present invention relates to the field of thermoelectric materials, and in particular to an ultra-high preferentially oriented flexible Cu x Se thermoelectric thin film and its preparation method and application. Background Art

[0002] Thermoelectric materials are functional materials that can directly convert heat and electricity. Thermoelectric devices fabricated from them are widely used in fields such as semiconductor power generation and refrigeration. In recent years, the rapid development of miniaturized semiconductor devices and wearable electronics has driven the miniaturization, micro-manufacturing, and flexibility of thermoelectric materials and devices. Among them, thermoelectric thin films fabricated from inorganic materials offer promising applications in portable and wearable devices due to their small size, light weight, and ease of miniaturization. Consequently, they have become a cutting-edge research topic in the field of thermoelectric technology. Cuprous selenide (Cu2Se) is a non-toxic thermoelectric material with excellent thermoelectric properties. Existing studies have shown that the thermoelectric figure of merit of bulk Cu2Se has exceeded 2.0, making it one of the thermoelectric material systems with the highest thermoelectric figure of merit currently available. Clearly, Cu2Se offers significant advantages over conventional commercially available thermoelectric materials in terms of both thermoelectric performance and manufacturing cost. Therefore, obtaining high-quality Cu2Se thermoelectric thin films is a cutting-edge research topic in this field.

[0003] Because both Cu and Se are easily oxidized, vacuum deposition is a suitable method for preparing Cu2Se thin films. However, due to the significant differences in physical properties between Cu and Se, controlling the composition of the thin film material presents significant challenges. Consequently, the thermoelectric performance of current Cu2Se thin films remains relatively low compared to their bulk counterparts, requiring further optimization of composition and microstructure to achieve improved performance.

[0004] Therefore, the existing technology still needs to be improved and developed. Summary of the Invention

[0005] In view of the above-mentioned deficiencies in the prior art, the present invention aims to provide an ultra-high preferentially oriented flexible Cu x Se thermoelectric thin films and their preparation methods and applications are intended to solve the problem that the thermoelectric performance of existing Cu2Se thin films is still lower than that of their bulk materials.

[0006] The technical solutions of the present invention are as follows:

[0007] The first aspect of the present invention provides an ultra-high preferentially oriented flexible Cu x A method for preparing a Se thermoelectric thin film, comprising the steps of:

[0008] providing a flexible substrate;

[0009] The ultra-high preferential orientation flexible Cu is prepared by magnetron co-sputtering on the flexible substrate using Cu2Se alloy target and Cu target, and then heat-treating. x Se thermoelectric thin film, wherein the value of x ranges from 0.5 to 2.5.

[0010] Optionally, the flexible substrate is selected from one of a polyimide flexible substrate, a molybdenum metal flexible substrate, and a platinum metal flexible substrate.

[0011] Optionally, the ultra-high preferentially oriented flexible Cu x The thickness of the Se thermoelectric film is 50nm~10μm.

[0012] Optionally, the step of performing magnetron co-sputtering on the flexible substrate using a Cu2Se alloy target and a Cu target specifically includes:

[0013] During magnetron sputtering of the flexible substrate using a Cu2Se alloy target, the Cu target is turned on for magnetron co-sputtering. The time for magnetron sputtering of the flexible substrate using a Cu2Se alloy target is 1 to 600 minutes, and the time for turning on the Cu target for magnetron co-sputtering is 1 to 200 minutes.

[0014] Optionally, the sputtering power of the Cu2Se alloy target is 55W, and the sputtering power of the Cu target is 15W.

[0015] Optionally, during the magnetron co-sputtering process, the bottom vacuum is lower than 1×10 -4 ~8×10 -4 Pa, the working vacuum is 0.1~1Pa, and the Ar flow rate is 10~100sccm.

[0016] Optionally, the heat treatment temperature is 100-400° C., and the heat treatment time is 30 minutes.

[0017] Optionally, the heat treatment temperature is 300°C.

[0018] The second aspect of the present invention provides an ultra-high preferentially oriented flexible Cu x Se thermoelectric film, wherein the preparation method of the present invention is used to prepare the film, wherein the value range of x is 0.5 to 2.5, and the Cu x The Se thermoelectric thin film has a (0l0) orientation.

[0019] The third aspect of the present invention provides an ultra-high preferentially oriented flexible Cu x Application of Se thermoelectric thin films in the preparation of thermoelectric devices.

[0020] Beneficial effect: The present invention provides an ultra-high preferentially oriented flexible Cu x Se thermoelectric film and its preparation method and application, the present invention adopts Cu2Se alloy target and Cu target, uses magnetron co-sputtering method to prepare flexible Cu with ultra-high (0l0) orientation and excellent thermoelectric performance on high temperature resistant flexible substrate x Se thermoelectric film. The preparation method provided by the present invention is simple to operate, low in cost, and easy to control the composition and growth orientation of the thermoelectric film. The ultra-high preferred orientation flexible Cu x Se thermoelectric films have high quality, good thermoelectric performance, good repeatability, and can be produced on a large scale industrially. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The ultra-high preferentially oriented flexible Cu in the embodiment of the present invention x Schematic diagram of the preparation of Se thermoelectric thin film.

[0022] Figure 2 1 is the XRD pattern of the thermoelectric thin film in Examples 1-6 of the present invention.

[0023] Figure 3 Graph showing the conductivity test results of the thermoelectric films in Examples 1-6 of the present invention.

[0024] Figure 4 Graph showing the Seebeck coefficient test results of the thermoelectric films in Examples 1-6 of the present invention.

[0025] Figure 5 Graph showing the power factor test results of the thermoelectric films in Examples 1-6 of the present invention. DETAILED DESCRIPTION

[0026] The present invention provides an ultra-high preferred orientation flexible Cu x Se thermoelectric thin film and its preparation method and application, in order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate the present invention and are not intended to limit the present invention.

[0027] Unless otherwise defined, all technical terms and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0028] Since Cu and Se are both easily oxidized substances, vacuum deposition technology is a more suitable method for preparing Cu2Se thin films. However, due to the large difference in physical properties between Cu and Se, there are great difficulties in regulating the composition of thin film materials. Therefore, the thermoelectric performance of current Cu2Se thin films is still lower than that of bulk materials, and further optimization of composition and microstructure is needed to achieve performance improvement. Based on this, the embodiment of the present invention provides an ultra-high preferential orientation flexible Cu2Se thin film. x Preparation method of Se thermoelectric thin film, such as Figure 1 As shown, wherein the steps include:

[0029] S1. providing a flexible substrate;

[0030] S2, using Cu2Se alloy target and Cu target, magnetron co-sputtering on the flexible substrate, and then heat treatment to prepare the ultra-high preferential orientation flexible Cu x Se thermoelectric thin film, wherein the value of x ranges from 0.5 to 2.5.

[0031] In this embodiment, Cu2Se alloy target and Cu target are used to prepare flexible Cu with ultra-high (0l0) orientation and excellent thermoelectric performance on a high temperature resistant flexible substrate by magnetron co-sputtering method. x Se thermoelectric film. The preparation method provided by the present invention is simple to operate, low in cost, and easy to control the composition and growth orientation of the thermoelectric film. The ultra-high preferred orientation flexible Cu x Se thermoelectric films have high quality, good thermoelectric performance, good repeatability, and can be produced on a large scale industrially.

[0032] In step S1, in one embodiment, the flexible substrate is selected from a polyimide flexible substrate, a molybdenum metal flexible substrate, and a platinum metal flexible substrate. Preferably, the flexible substrate is a polyimide flexible substrate, which can withstand temperatures of 300°C, facilitating subsequent high-temperature heat treatment.

[0033] In step S2, since the melting point of the Se target is very low and it will be deformed by heat after magnetron sputtering, the Se target is very easy to break during the magnetron sputtering process using the Se target, and it is very easy to volatilize again during the magnetron sputtering process of Se, and the content is difficult to control. This embodiment uses a Cu2Se alloy target. During the magnetron sputtering process, the Cu2Se alloy target will not break, and during the magnetron sputtering process of Cu2Se, Cu2Se is not easy to volatilize again, which is beneficial to the preparation of high-quality thermoelectric films and the control of film composition. At the same time, the regulation of the thermoelectric film components is achieved by co-sputtering of Cu. Therefore, the present invention uses a Cu2Se alloy target and a Cu target to carry out magnetron co-sputtering, and can achieve the final preparation of Cux The composition of Cu and Se in the Se thermoelectric film is close to that of the Cu2Se alloy target. Then, heat treatment is used to achieve the Cu x Regulation of the microstructure of Se thermoelectric films to improve Cu x The crystallinity of Se thermoelectric thin films makes Cu x Se thermoelectric film has a stronger (0l0) orientation, and finally an ultra-high preferred orientation flexible Cu x Se thermoelectric thin film solves the problem of difficulty in regulating the composition of thin film materials in the prior art due to the large difference in physical properties between Cu and Se.

[0034] In one embodiment, the ultra-high preferentially oriented flexible Cu x The thickness of the Se thermoelectric film is 50nm~10μm.

[0035] In one embodiment, the step of performing magnetron co-sputtering on the flexible substrate using a Cu2Se alloy target and a Cu target specifically includes:

[0036] In the process of magnetron sputtering on the flexible substrate using the Cu2Se alloy target, the Cu target is turned on for magnetron co-sputtering, the time of magnetron sputtering on the flexible substrate using the Cu2Se alloy target is 1 to 600 minutes, and the time of turning on the Cu target for magnetron co-sputtering is 1 to 200 minutes. In this embodiment, the Cu target is turned on for magnetron co-sputtering at a certain time point in the middle process of magnetron sputtering of the Cu2Se alloy target on the flexible substrate (the present invention does not limit the specific time point of turning on the Cu target, and it can be adjusted according to actual needs). By adjusting the time of magnetron co-sputtering of the Cu target, the ultra-high preferential orientation flexible Cu is controlled. x The thickness of Se thermoelectric film can be further controlled by ultra-high preferential orientation flexible Cu x The ratio of Cu and Se in the Se thermoelectric film. Of course, according to actual needs, the Cu2Se alloy target and the Cu target can also be turned on at the same time for magnetron co-sputtering.

[0037] In one embodiment, the sputtering power of the Cu2Se alloy target is 55W, and the sputtering power of the Cu target is 15W.

[0038] In one embodiment, during the magnetron co-sputtering process, the bottom vacuum is less than 1×10 -4 ~8×10 -4 Pa, working vacuum is 0.1~1Pa, Ar flow rate is 10~100sccm. This parameter is more conducive to ultra-high preferential orientation of high-quality flexible Cu x Preparation of Se thermoelectric thin films.

[0039] In one embodiment, the heat treatment temperature is 100-400°C and the heat treatment time is 30 minutes. Heat treatment can improve the ultra-high preferred orientation flexible Cu x The crystallinity of Se thermoelectric thin films makes ultra-high preferential orientation flexible Cu x Se thermoelectric film has a stronger (0l0) orientation, and the inventors unexpectedly found that ultra-high preferential orientation flexible Cu x Se thermoelectric films are more conducive to the transmission of high-energy electrons in the (0l0) direction.

[0040] In one embodiment, the heat treatment temperature is 300°C and the heat treatment time is 30 minutes. x Se thermoelectric thin films have better high-energy electron transport performance in the (0l0) direction.

[0041] The embodiment of the present invention also provides an ultra-high preferred orientation flexible Cu x Se thermoelectric film, wherein the method of the embodiment of the present invention is used to prepare the film, wherein the value of x ranges from 0.5 to 2.5, and the ultra-high preferential orientation flexible Cu x Se thermoelectric thin film has (0l0) orientation. x Se thermoelectric thin films have excellent high-energy electron transport performance, relatively good Seebeck coefficient and power factor.

[0042] The embodiment of the present invention also provides an ultra-high preferential orientation flexible Cu x The application of Se thermoelectric thin films in the preparation of thermoelectric devices. The thermoelectric devices can be used in the fields of semiconductor power generation, refrigeration, etc.

[0043] The present invention will be further described below with reference to specific examples.

[0044] Example 1

[0045] The Cu2Se alloy target and Cu target were used to carry out magnetron co-sputtering on polyimide flexible substrate (the parameters were set as follows: bottom vacuum was less than 8×10 -4 Pa, working vacuum is 0.5Pa, Ar flow rate is 40sccm, sputtering power of Cu2Se alloy target is 55W, sputtering power of Cu target is 15W, sputtering time of Cu2Se alloy target is 30min, co-sputtering time of Cu target is 3min), and then heat treated at 300℃ for 30min to prepare ultra-high preferential orientation flexible Cu 1.99 Se thermoelectric thin film.

[0046] Example 2

[0047] The Cu2Se alloy target and Cu target were used to carry out magnetron co-sputtering on polyimide flexible substrate (the parameters were set as follows: bottom vacuum was less than 8×10 -4 Pa, working vacuum is 0.5Pa, Ar flow rate is 40sccm, sputtering power of Cu2Se alloy target is 55W, sputtering power of Cu target is 15W, sputtering time of Cu2Se alloy target is 30min, co-sputtering time of Cu target is 5min), and then heat treated at 300℃ for 30min to prepare ultra-high preferential orientation flexible Cu 2.05 Se thermoelectric thin film.

[0048] Example 3

[0049] The Cu2Se alloy target and Cu target were used to carry out magnetron co-sputtering on polyimide flexible substrate (the parameters were set as follows: bottom vacuum was less than 8×10 -4 Pa, working vacuum is 0.5Pa, Ar flow rate is 40sccm, sputtering power of Cu2Se alloy target is 55W, sputtering power of Cu target is 15W, sputtering time of Cu2Se alloy target is 30min, co-sputtering time of Cu target is 7min), and then heat treated at 300℃ for 30min to prepare ultra-high preferential orientation flexible Cu 2.17 Se thermoelectric thin film.

[0050] Example 4

[0051] The Cu2Se alloy target and Cu target were used to carry out magnetron co-sputtering on polyimide flexible substrate (the parameters were set as follows: bottom vacuum was less than 8×10 -4 Pa, working vacuum is 0.5Pa, Ar flow rate is 40sccm, sputtering power of Cu2Se alloy target is 55W, sputtering power of Cu target is 15W, sputtering time of Cu2Se alloy target is 30min, co-sputtering time of Cu target is 9min), and then heat treated at 300℃ for 30min to prepare ultra-high preferential orientation flexible Cu 2.20 Se thermoelectric thin film.

[0052] Example 5

[0053] The Cu2Se alloy target and Cu target were used to carry out magnetron co-sputtering on polyimide flexible substrate (the parameters were set as follows: bottom vacuum was less than 8×10 -4Pa, working vacuum is 0.5Pa, Ar flow rate is 40sccm, sputtering power of Cu2Se alloy target is 55W, sputtering power of Cu target is 15W, sputtering time of Cu2Se alloy target is 30min, co-sputtering time of Cu target is 11min), and then heat treated at 300℃ for 30min to prepare ultra-high preferential orientation flexible Cu 2.26 Se thermoelectric thin film.

[0054] Example 6

[0055] The Cu2Se alloy target and Cu target were used to carry out magnetron co-sputtering on polyimide flexible substrate (the parameters were set as follows: bottom vacuum was less than 8×10 -4 Pa, working vacuum is 0.5Pa, Ar flow rate is 40sccm, sputtering power of Cu2Se alloy target is 55W, sputtering power of Cu target is 15W, sputtering time of Cu2Se alloy target is 30min, co-sputtering time of Cu target is 13min), and then heat treated at 300℃ for 30min to prepare ultra-high preferential orientation flexible Cu 2.31 Se thermoelectric thin film.

[0056] test

[0057] The thermoelectric films prepared in Examples 1-6 were subjected to XRD tests, and the results were as follows: Figure 2 As shown, it can be found that the thermoelectric films prepared in Examples 1-6 have sharp peaks, good crystal structure, no impurity peaks, and ultra-high (0l0) orientation.

[0058] It should be noted that the working efficiency of thermoelectric devices mainly depends on the thermoelectric figure of merit zT of thermoelectric materials, zT = (S 2 σ / κ)T, where S, σ and κ are the Seebeck coefficient, electrical conductivity and thermal conductivity (including carrier thermal conductivity κ) respectively. e and lattice thermal conductivity κ l ), T is the service temperature of the device.

[0059] Therefore, the thermoelectric performance tests (including conductivity, Seebeck coefficient, and power factor) of the thermoelectric films prepared in Examples 1-6 were carried out. The results are as follows: Figure 3-5 shown. Figure 3 is the conductivity test result, Figure 3 It can be seen that with the increase of Cu content, the flexible Cu x The electrical conductivity of Se thermoelectric thin films gradually decreases; Figure 4 is the Seebeck coefficient test result, Figure 4 It can be seen that the Seebeck coefficient is positive, and the flexible Cu prepared in the embodiment of the present invention xSe thermoelectric film is p-type, and with the increase of Cu content, the flexible Cu x The Seebeck coefficient of Se thermoelectric film gradually increases; Figure 5 The power factor test results are as follows: x In Se thermoelectric thin films, when x is 2.17-2.26, it has a better power factor.

[0060] Based on the above test results, it can be seen that the preparation method provided by the present invention can prepare ultra-high preferential orientation flexible Cu with excellent thermoelectric performance. x Se thermoelectric film solves the problem that the thermoelectric performance of existing Cu2Se films is still lower than that of their bulk materials.

[0061] In summary, the present invention provides an ultra-high preferential orientation flexible Cu x Se thermoelectric film and its preparation method and application, the present invention adopts Cu2Se alloy target and Cu target, uses magnetron co-sputtering method to prepare flexible Cu with ultra-high (0l0) orientation and excellent thermoelectric performance on high temperature resistant flexible substrate x Se thermoelectric film. Using Cu2Se alloy target, during the magnetron sputtering process, the Cu2Se alloy target will not break, and during the magnetron sputtering process of Cu2Se, Cu2Se is not easy to volatilize again, which is conducive to the preparation of high-quality thermoelectric films and the control of film composition. At the same time, the thermoelectric film composition can be regulated by co-sputtering of Cu. Therefore, the present invention uses Cu2Se alloy target and Cu target for magnetron co-sputtering, and can achieve the final preparation of Cu x The composition of Cu and Se in the Se thermoelectric film is close to that of the Cu2Se alloy target. Then, heat treatment is used to achieve the Cu x Regulation of the microstructure of Se thermoelectric films to improve Cu x The crystallinity of Se thermoelectric thin films makes Cu x Se thermoelectric film has a stronger (0l0) orientation, and finally an ultra-high preferred orientation flexible Cu x Se thermoelectric film. The preparation method provided by the present invention is simple to operate, low in cost, and easy to control the composition and growth orientation of the thermoelectric film. The ultra-high preferred orientation flexible Cu x Se thermoelectric films have high quality, good thermoelectric performance, good repeatability, and can be produced on a large scale industrially.

[0062] It should be understood that the application of the present invention is not limited to the above examples. For those skilled in the art, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. An ultra-high preferentially oriented flexible Cu x The method for preparing a Se thermoelectric thin film is characterized in that: Including steps: providing a flexible substrate; The ultra-high preferentially oriented flexible Cu substrate is prepared by magnetron co-sputtering on the flexible substrate using Cu2Se alloy target and Cu target, and then heat-treating. x Se thermoelectric film, wherein the value of x ranges from 0.5 to 2.5, the Cu x Se thermoelectric film has (0 l 0) Orientation.

2. The ultra-high preferentially oriented flexible Cu according to claim 1 x The method for preparing a Se thermoelectric thin film is characterized in that: The flexible substrate is selected from one of a polyimide flexible substrate, a molybdenum metal flexible substrate, and a platinum metal flexible substrate.

3. The ultra-high preferentially oriented flexible Cu according to claim 1 x The method for preparing a Se thermoelectric thin film is characterized in that: The ultra-high preferentially oriented flexible Cu x The thickness of the Se thermoelectric film is 50nm~10μm.

4. The ultra-high preferentially oriented flexible Cu according to claim 1 x The method for preparing a Se thermoelectric thin film is characterized in that: The step of performing magnetron co-sputtering on the flexible substrate using a Cu2Se alloy target and a Cu target specifically includes: In the process of magnetron sputtering on the flexible substrate using the Cu2Se alloy target, the Cu target is turned on for magnetron co-sputtering. The time for magnetron sputtering on the flexible substrate using the Cu2Se alloy target is 1~600min, and the time for turning on the Cu target for magnetron co-sputtering is 1~200min.

5. The ultra-high preferentially oriented flexible Cu according to claim 1 x The method for preparing a Se thermoelectric thin film is characterized in that: The sputtering power of the Cu2Se alloy target is 55W, and the sputtering power of the Cu target is 15W.

6. The ultra-high preferentially oriented flexible Cu according to claim 1 x The method for preparing a Se thermoelectric thin film is characterized in that: During the magnetron co-sputtering process, the bottom vacuum is less than 1×10 -4 ~8×10 -4 Pa, the working vacuum is 0.1~1Pa, and the Ar flow rate is 10~100sccm.

7. The ultra-high preferentially oriented flexible Cu according to claim 1 x The method for preparing a Se thermoelectric thin film is characterized in that: The heat treatment temperature is 100-400° C., and the heat treatment time is 30 minutes.

8. The ultra-high preferentially oriented flexible Cu according to claim 1 x The method for preparing a Se thermoelectric thin film is characterized in that: The heat treatment temperature is 300°C.

9. An ultra-high preferentially oriented flexible Cu x Se thermoelectric thin film, characterized in that It is prepared by the preparation method according to any one of claims 1 to 8, wherein the value range of x is 0.5 to 2.5, and the Cu x Se thermoelectric film has (0 l 0) Orientation.

10. An ultra-high preferentially oriented flexible Cu as claimed in claim 9 x Application of Se thermoelectric thin films in the preparation of thermoelectric devices.

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