Silver selenide nanowire ink and method of making, silver selenide thermoelectric film, thermoelectric device

Abstract

The application belongs to the technical field of silver selenide nanowire ink, and particularly relates to a silver selenide nanowire ink and a preparation method thereof, a silver selenide thermoelectric film and a thermoelectric device. The first aspect of the application provides a silver selenide nanowire ink, which comprises a mixture of silver selenide nanowires, a varnish and isophorone solvent; the mass ratio of the silver selenide nanowires, the varnish and the isophorone solvent is (5:2.5:2.5) to (5.5:2:2.5). The application provides the silver selenide nanowire ink, in which silver selenide nanowires are dispersed in a mixed solution of the varnish and the isophorone solvent as a conductive substance. The silver selenide nanowires are dispersed in the varnish to form a conductive path, and the isophorone solvent and the varnish synergistically act to form a flexible and good conductive film layer after the silver selenide nanowire ink is solidified. By adjusting the mass ratio of the silver selenide nanowires, the varnish and the isophorone, the overall performance of the silver selenide nanowire ink can be adjusted.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of silver selenide nanowire ink, and particularly relates to a silver selenide nanowire ink and a preparation method thereof, a silver selenide thermoelectric film and a thermoelectric device. BACKGROUND

[0002] Traditional thermoelectric generators (TEGs) are hard and brittle, which is difficult to meet the requirements of wearable electronic devices for flexibility. Therefore, in the past decade, flexible thermoelectric generators have attracted great attention from academia and industry. The research in this field mainly focuses on improving the flexibility of the material while not affecting the thermoelectric performance of the material. At present, conductive polymers, inorganic semiconductors and carbon materials have been tried to be used to manufacture flexible TEGs. Among them, inorganic semiconductors have the best thermoelectric performance, but their flexibility is poor. On the contrary, conductive polymers are very flexible, but their thermoelectric performance is poor. Therefore, researchers prepare conductive polymer / inorganic semiconductor composites to obtain thermoelectric generators with good flexibility and thermoelectric performance, but most of the experimental results are not ideal. For example, Wang et al. prepared a flexible PEDOT / Bi2Te3 composite film with good performance, but the process involved is complex, and the thermoelectric performance and flexibility need to be improved. Some researchers also prepared thermoelectric materials with good performance on a flexible substrate to obtain a flexible TEG, for example, Bi 0.4 Sb 1.6 Te3 / Te on a polyimide film, which has good thermoelectric performance but poor flexibility. In addition, the element Te is toxic and has less storage on the earth.

[0003] Silver selenide (Ag2Se) involves elements with relatively low prices and more storage on the earth, and has a high power factor and a low thermal conductivity at room temperature, which is one of the candidate substitutes for commercial Bi2Te3. Some researchers have tried to prepare flexible TEGs based on silver selenide. For example, Ding et al. and Lu et al. prepared TEGs on nylon cloth based on Ag2Se or its composite materials by using the method of filtration. Although the prepared thin film has good thermoelectric performance and certain flexibility, its flexibility still needs to be improved. SUMMARY

[0004] To solve the problem of the unsatisfactory thermoelectric performance and flexibility of the thin film prepared by the existing silver selenide nanowire ink, the application provides a silver selenide nanowire ink and a preparation method thereof, a silver selenide thermoelectric film and a thermoelectric device.

[0005] To achieve the above application purposes, the technical solutions adopted by the application are as follows:

[0006] The first aspect of the application provides a silver selenide nanowire ink, comprising a mixture of silver selenide nanowires, light oil and isophorone solvent; the mass ratio of silver selenide nanowires, light oil and isophorone solvent is (5:2.5:2.5) to (5.5:2:2.5).

[0007] The application provides a silver selenide nanowire ink, in which silver selenide nanowires are dispersed in a mixed solution of light oil and isophorone solvent as a conductive substance. The light oil is a synthetic resin that can be cured under certain conditions. The silver selenide nanowires and isophorone solvent are dispersed in the light oil to form a conductive path. The isophorone solvent and light oil work together to form a flexible conductive film layer after the silver selenide nanowire ink is cured. By adjusting the mass ratio of silver selenide nanowires, light oil and isophorone, the overall performance of the silver selenide nanowire ink can be further adjusted, such as improving the printing performance, improving the conductive performance and improving the flexibility of the conductive film layer formed after curing.

[0008] The second aspect of the application provides a preparation method of a silver selenide nanowire ink, comprising the following steps:

[0009] Each component is obtained according to the components of the silver selenide nanowire ink described above.

[0010] Each component is mixed and treated to obtain the silver selenide nanowire ink.

[0011] The preparation method of the silver selenide nanowire ink provided in the embodiments of the application mixes silver selenide nanowires, light oil and isophorone solvent in a certain proportion, and through mixing and blending treatment, the silver selenide nanowires and isophorone solvent are dispersed in the light oil and are wrapped by the light oil, so that a silver selenide nanowire ink with good printing performance and conductivity can be obtained.

[0012] The third aspect of the application provides a silver selenide thermoelectric film, which comprises a silver selenide thermoelectric film formed by the silver selenide nanowire ink described above on a substrate.

[0013] Compared with traditional silver selenide thermoelectric films, the silver selenide thermoelectric film provided in the embodiments of the application has excellent electrical performance and flexibility.

[0014] The fourth aspect of the application provides a thermoelectric device, which comprises at least one electric heating leg formed by the silver selenide nanowire ink described above.

[0015] Due to the good conductivity and flexibility of the silver selenide thermoelectric film described above, it can be applied to thermoelectric devices to improve the wearability and electrical performance of the thermoelectric devices. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1A flow chart of preparation of a silver selenide thermoelectric film and device is provided for the embodiment of the present application.

[0017] Figure 2 A schematic diagram of a thermoelectric device is provided for the embodiment of the present application.

[0018] Figure 3 A physical diagram of a thermoelectric device is provided for the embodiment of the present application.

[0019] Figure 4 A Seebeck coefficient of an Ag2Se film in a temperature range of 300K to 420K is provided for the embodiment of the present application.

[0020] Figure 5 An electrical conductivity of an Ag2Se film in a temperature range of 300K to 420K is provided for the embodiment of the present application.

[0021] Figure 6 A power factor of an Ag2Se film in a temperature range of 300K to 420K is provided for the embodiment of the present application.

[0022] Figure 7 A change of resistance ratio with bending times when the bending radius is 9mm is provided for the embodiment of the present application.

[0023] Figure 8 A change of resistance ratio with bending times when the bending radius is 7mm is provided for the embodiment of the present application.

[0024] Figure 9 A schematic diagram of a thermoelectric performance measuring instrument is provided for the embodiment of the present application.

[0025] Figure 10 An open circuit voltage of output under different temperature differences is provided for the embodiment of the present application. DETAILED DESCRIPTION

[0026] In order to make the technical problems, technical solutions and beneficial effects to be solved in the present application more clear and explicit, the present application will be further described in detail in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

[0027] In the present application, the term "and / or" describes the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B can mean that A exists alone, A and B exist together, and B exists alone. Wherein A and B can be singular or plural. The character " / " generally represents an "or" relationship between the associated objects before and after it.

[0028] In this application, "at least one" means one or more, "multiple" means two or more. "At least one of the following" or the like means any combination of the items, including a single item or any combination of multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can mean a, b, c, a-b (i.e. a and b), a-c, b-c, or a-b-c, where a, b, and c can be single or multiple.

[0029] It should be understood that the size of the sequence number of the above-mentioned processes in various embodiments of the present application does not mean the order of execution, and part or all of the steps can be executed in parallel or in sequence, and the execution order of the processes should be determined according to their functions and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0030] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0031] The weight of the related components mentioned in the embodiments of the present application can not only refer to the specific content of each component, but also represent the weight ratio relationship between each component, therefore, as long as the content of the related components in the embodiments of the present application is enlarged or reduced in proportion, it is within the scope disclosed in the embodiments of the present application. Specifically, the mass mentioned in the embodiments of the present application can be μg, mg, g, kg and other mass units commonly known in the chemical field.

[0032] The terms "first", "second" are only used for description purposes, to distinguish objects such as substances from each other, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. For example, without departing from the scope of the embodiments of the present application, the first XX can also be called the second XX, and similarly, the second XX can also be called the first XX. Therefore, the features limited by "first" and "second" can explicitly or implicitly include one or more of the features.

[0033] The first aspect of the embodiments of the present application provides a silver selenide nanowire ink, which comprises a mixture of silver selenide nanowires, photo oil and isophorone solvent; the mass ratio of silver selenide nanowires, photo oil and isophorone solvent is (5:2.5:2.5)~(5.5:2:2.5).

[0034] The selenium silver nanowire ink provided by the embodiments of the present application disperses selenium silver nanowires in a mixed solution of photo oil and isophorone solvent as a conductive substance. In a first aspect, the photo oil is a synthetic resin that can be cured under certain conditions, and the selenium silver nanowires and isophorone solvent are dispersed in the photo oil to form a conductive path. The isophorone solvent and photo oil synergistically act to form a flexible and good conductive film layer after the selenium silver nanowire ink is cured. In a second aspect, by adjusting the mass ratio of the selenium silver nanowires, photo oil, and isophorone, the overall performance of the selenium silver nanowire ink can be further adjusted, for example, to improve the printing performance, improve the conductive performance, and improve the flexibility of the conductive film layer formed after curing. Specifically, the mass ratio of the selenium silver nanowires, photo oil, and isophorone solvent includes but is not limited to 5:2.5:2.5, 5.1:2.5:2.4, 5.2:2.5:2.3, 5.3:2.5:2.2, 5.4:2.5:2.1, and 5.5:2:2.5.

[0035] In some embodiments, to further improve the flexibility of the selenium silver nanowire ink, in other embodiments, the photo oil includes a vinyl chloride resin, a resin No. 28-2, and a curing agent, and the mass percentages of the components of the photo oil and the isophorone are as follows:

[0036]

[0037] The photo oil provided by the embodiments of the present application includes a vinyl chloride resin, a vinyl chloride resin, a curing agent, and isophorone mixed to form a three-dimensional network structure. The selenium silver nanowires are dispersed in the three-dimensional network structure to form a conductive path. The isophorone solvent and the vinyl chloride resin, resin No. 28-2, synergistically act to form a flexible and good conductive film layer after the selenium silver nanowire ink is cured. By adjusting the mass ratio of the vinyl chloride resin, resin No. 28-2, curing agent, and isophorone, the overall performance of the selenium silver nanowire ink can be adjusted, for example, to improve the printing performance, improve the conductive performance, and improve the flexibility of the conductive film layer formed after curing.

[0038] The second aspect of the embodiments of the present application provides a preparation method of a selenium silver nanowire ink, including the following steps:

[0039] Step S10: Obtain each component according to the components contained in the selenium silver nanowire ink described above.

[0040] Step S20: Mix the components to obtain the selenium silver nanowire ink.

[0041] The preparation method of the silver selenide nanowire ink provided by the embodiment of the application can mix silver selenide nanowires, photo oil and isophorone solvent according to a certain proportion, and through mixing and blending treatment, the silver selenide nanowires and the isophorone solvent can be dispersed in the photo oil and wrapped by the photo oil, so that the silver selenide nanowire ink with good printing performance and conductivity can be obtained.

[0042] In some embodiments, in order to improve the conductivity of the silver selenide nanowire ink, the silver selenide nanowire powder in the step S10 can be prepared according to the method comprising the following steps:

[0043] The step S31: mixing and treating the selenium nanowires and the first solvent to obtain a first solution;

[0044] The step S32: mixing and treating AgNO3, a second solvent and a reducing agent to obtain a second solution containing elemental silver through a reduction reaction, wherein the reducing agent comprises any one of ascorbic acid or glucose;

[0045] The step S33: mixing and treating the first solution and the second solution to obtain a third solution containing silver selenide nanowires through an oxidation reaction;

[0046] The step S34: removing impurities and drying the third solution to obtain the silver selenide nanowire powder.

[0047] The embodiment of the application provides a preparation method of silver selenide nanowire powder, which mainly comprises four steps. In the first step, the selenium nanowires and the first solvent are mixed and treated, wherein the first solvent comprises ethylene glycol and can dissolve the selenium nanowires, so as to facilitate the subsequent preparation of the silver selenide nanowire powder. In the second step, AgNO3, the second solvent and the reducing agent are mixed and treated, and a second solution containing elemental silver is obtained through a reduction reaction. In the third step, the first solution and the second solution are mixed and treated, the elemental silver in the second solution will be oxidized with the selenium nanowires in the first solution to generate a third solution containing silver selenide nanowires. In the fourth step, the third solution is treated to remove impurities and dry, and the silver selenide nanowire powder in a dark gray precipitate is obtained. The silver selenide nanowire powder prepared by the preparation method has high purity and good electrical performance.

[0048] In some embodiments, the mass ratio of selenium nanowires, AgNO3, and glucose is (1:4:14) to (1:6:16). The mass ratio of selenium nanowires, AgNO3, and glucose can be 1:4.6875:14.6, but is not limited to this. In some embodiments, the mass ratio of selenium nanowires, AgNO3, and ascorbic acid is (1:4:14) to (1:6:16). The mass ratio of selenium nanowires, AgNO3, and ascorbic acid can be 1:4.6875:14.1, but is not limited to this. By adjusting the mass ratio of AgNO3 and the reducing agent (ascorbic acid or glucose), the AgNO3 and the reducing agent can react fully to avoid subsequent side reactions and the generation of other impurities. By adjusting the ratio of AgNO3 and selenium nanowires, the content of the final silver selenide nanowire powder can be controlled.

[0049] In some embodiments, to improve the conductivity of silver selenide nanowire ink, the method further includes the following step of preparing selenium nanowires:

[0050] Step S41: Mix SeO2, β-cyclodextrin and the third solvent to obtain the fourth solution;

[0051] Step S42: Mix ascorbic acid and the fourth solvent to obtain the fifth solution;

[0052] Step S43: Mix the fourth and fifth solutions and reduce them to obtain a sixth solution containing selenium nanowires;

[0053] Step S44: The sixth solution is purified and dried to obtain selenium nanowire powder.

[0054] The method for preparing selenium nanowire powder provided in this application mainly includes four steps. First, SeO2, β-cyclodextrin, and a third solvent are mixed. The third solvent includes deionized water, which dissolves SeO2 and β-cyclodextrin. β-cyclodextrin promotes the uniform dispersion of SeO2 in the third solvent, facilitating the subsequent preparation of selenium nanowire powder. Second, ascorbic acid and a fourth solvent are mixed. The third solvent includes deionized water, which dissolves ascorbic acid. Third, the fourth and fifth solutions are mixed. The SeO2 in the fourth solution reacts with the ascorbic acid in the fifth solution to generate a sixth solution containing selenium nanowires. Fourth, the sixth solution is purified and dried to obtain a dark red precipitate of selenium nanowires. Using SeO2, β-cyclodextrin, and ascorbic acid as raw materials, this method prepares selenium nanowire powder with high purity, making it suitable as a raw material for the subsequent preparation of silver selenide nanowires.

[0055] In some embodiments, the mass ratio of SeO2, β-cyclodextrin, the sum of the third solvent and the fourth solvent, ascorbic acid is 1:1:1.5:200. By adjusting the ratio of SeO2, β-cyclodextrin and the sum of the third solvent and the fourth solvent, SeO2 can be uniformly distributed in the third solvent and the fourth solvent. If the amount of β-cyclodextrin is too small, it cannot fully play a role on the surface of the selenium source. If the amount of β-cyclodextrin is too large, it will affect the concentration of the solution, making it difficult to control the subsequent reaction and causing waste. By adjusting the ratio of the reducing agent and SeO2, some side reactions can be avoided. Specifically, if the concentration of the reducing agent is too large, it will cause further side reactions to occur and cause waste of the reducing agent. If the concentration of the reducing agent is too small, it cannot completely reduce the selenium source in the solution.

[0056] In some embodiments, the reducing agent includes ascorbic acid or glucose, the first solvent is ethylene glycol, and the second solvent, the third solvent and the fourth solvent are deionized water, please refer to Figure 1 The preparation method of the silver selenide nanowire ink provided by the embodiments of the present application includes the following steps:

[0057] Step S41: mixing SeO2, β-cyclodextrin and deionized water to obtain a fourth solution;

[0058] Step S42: mixing ascorbic acid and deionized water to obtain a fifth solution;

[0059] Step S43: mixing the fourth solution and the fifth solution to obtain a sixth solution containing selenium nanowires by reaction;

[0060] Step S44: removing impurities and drying the sixth solution to obtain selenium nanowire powder.

[0061] Step S31: mixing selenium nanowire powder (obtained in step S44) and ethylene glycol to obtain a first solution;

[0062] Step S32: mixing AgNO3, deionized water and ascorbic acid to obtain a second solution containing elemental silver by reduction reaction;

[0063] Step S33: mixing the first solution and the second solution to obtain a third solution containing silver selenide nanowires by reaction;

[0064] Step S34: removing impurities and drying the third solution to obtain silver selenide nanowire powder.

[0065] Step S10: obtaining each component according to the mass ratio of silver selenide nanowire powder (obtained in step S34) to light oil and isophorone solvent (5:2.5:2.5)~(5.5:2:2.5);

[0066] Step S20: mixing the components to obtain the silver selenide nanowire ink.

[0067] The preparation steps of the silver selenide nanowire ink provided in the embodiments of the present application mainly include ten steps. In the first step, SeO2, β-cyclodextrin and a third solvent are mixed, wherein the third solvent includes deionized water soluble SeO2 and β-cyclodextrin, and the β-cyclodextrin acts as a surfactant to promote the uniform dispersion of SeO2 in the third solvent, so as to facilitate the subsequent preparation of selenium nanowire powder. In the second step, ascorbic acid is added to a fourth solvent for mixing, and the fourth solvent includes deionized water soluble ascorbic acid. In the third step, the fourth solution and a fifth solution are mixed, and the SeO2 in the fourth solution will react with the ascorbic acid in the fifth solution to generate a sixth solution containing selenium nanowires. In the fourth step, the sixth solution is subjected to impurity removal and drying treatment to obtain dark red precipitate of selenium nanowires. The selenium nanowires are prepared from SeO2, β-cyclodextrin and ascorbic acid, and the preparation process is simple and low in cost. The selenium nanowire powder prepared by the preparation method has high purity, so as to be used as a raw material for the subsequent preparation of silver selenide nanowires. In the fifth step, the selenium nanowires are mixed with a first solvent, wherein the first solvent includes ethylene glycol soluble selenium nanowires, so as to facilitate the subsequent preparation of silver selenide nanowire powder. In the sixth step, AgNO3, a second solvent and a reducing agent are mixed, and a reduction reaction is performed to obtain a second solution containing elemental silver. In the seventh step, the first solution and the second solution are mixed, and the elemental silver in the second solution will react with the selenium nanowires in the first solution to generate a third solution containing silver selenide nanowires. In the eighth step, the third solution is subjected to impurity removal and drying treatment to obtain dark gray precipitate of silver selenide nanowires. In the ninth step, by adjusting the mass ratio of the silver selenide nanowires, the photo oil and the isophorone, the overall performance of the silver selenide nanowire ink can be adjusted, for example, the printing performance can be improved, the conductivity can be improved, and the flexibility of the conductive film layer formed after curing can be improved. In the tenth step, the final target product (silver selenide nanowire ink) is obtained by mixing.

[0068] The third aspect of the embodiments of the present application provides a silver selenide thermoelectric film, which is formed by the above-mentioned silver selenide nanowire ink on a substrate.

[0069] Compared with the traditional silver selenide thermoelectric film, the silver selenide thermoelectric film provided in the embodiments of the present application has excellent electrical performance and flexibility. Further, when the bending radius of the silver selenide thermoelectric film is 7-9 mm, the silver selenide thermoelectric film can be bent 1000-5000 times, and the resistance change of the silver selenide thermoelectric film is 3-12%, which is small. The specific resistance change and bending times are shown in the following table. Figure 1 As shown in the figure, a specific pattern of film is prepared by screen printing and sintering annealing at 140°C to prepare a thermoelectric film.

[0070] The fourth aspect of the embodiment of the present application provides a thermoelectric device, which comprises at least one electric heating leg formed by the silver selenide nanowire ink.

[0071] The silver selenide thermoelectric film has good electrical conductivity and flexibility, and can be applied to a thermoelectric device to improve the wearability and electrical performance of the thermoelectric device.

[0072] In some embodiments, the electric heating legs are connected in series through liquid metal to form a conductive circuit, electrodes are arranged at both ends of the conductive circuit, and the width of the electric heating leg is 5-7 mm and the length is 25-30 mm. For details, refer to Figure 1 The thermoelectric prototype device is prepared by screen printing and annealing. For details, refer to Figure 2 and Figure 3 As shown in the figure, the thermoelectric device comprises five electric heating legs, the electric heating legs are connected in series through liquid metal to form a conductive circuit, the electrodes are arranged at both ends of the conductive circuit, the width of the electric heating leg is 5 mm, and the length is 25 mm. It should be noted that Figure 3 The water mark is a polydimethylsiloxane (PDMS) encapsulant.

[0073] To enable the above-mentioned implementation details and operations of the present application to be clearly understood by those skilled in the art, and the performance of the silver selenide nanowire ink and the preparation method, the silver selenide thermoelectric film, and the thermoelectric device is significantly improved, the following multiple embodiments are used to illustrate the above technical solutions.

[0074] Embodiment 1

[0075] The embodiment provides a silver selenide nanowire ink, which comprises a mixture of silver selenide nanowires, varnish, and isophorone solvent; and the mass ratio of the silver selenide nanowires, the varnish, and the isophorone solvent is 5.5:2:2.5.

[0076] Embodiment 2

[0077] The embodiment provides a preparation method of the silver selenide nanowire ink in Embodiment 1. For details, refer to Figure 1 As shown in the figure, the preparation method comprises the following steps:

[0078] Step S41: Specifically, 1 g of SeO2 and 1 g of β-cyclodextrin are added to a conical flask containing 200 mL of deionized water and stirred for 20 min to obtain solution 1.

[0079] Step S42: 1.5 g of ascorbic acid is added to another conical flask containing 200 mL of deionized water, and stirring is performed to obtain solution 2.

[0080] Step S43: Next, solution 1 was added dropwise into solution 2 and stirring was continued for 5 hours.

[0081] Step S44: Subsequently, the dark red precipitate was obtained by washing with deionized water and ethanol several times and centrifugation. The final product was obtained after the precipitate was left to stand in anhydrous ethanol for 48 hours. The product was dried by centrifugation to obtain selenium nanowires (Se NWs) powder.

[0082] Step S31: 0.32 g of Se NWs (obtained in step S44) were dispersed in 320 mL of ethylene glycol.

[0083] Step S32: 1.5 g of AgN03 and 4.5 g of ascorbic acid were separately dissolved in 15 mL of deionized water and stirred for 5 min to obtain a solution.

[0084] Step S33: Then, the AgN03 solution (obtained in step S32) was added dropwise into the Se NWs under vigorous stirring. Subsequently, the ascorbic acid solution obtained was added dropwise.

[0085] Step S34: After 6 h of reaction, the dark gray precipitate was centrifuged and washed several times with deionized water and anhydrous ethanol. Finally, the precipitate was dried in a vacuum oven at 40 °C.

[0086] Step S10 The components were obtained according to the mass ratio of silver selenide nanowires (obtained in step S34), photo oil and isophorone solvent as 5:2.5:2.5.

[0087] Step S20: The uniform Ag2Se ink was finally obtained by manual stirring and placing in a planetary stirrer several times with the components (obtained in step S10).

[0088] Example 3

[0089] The present example provides a silver selenide nanowire ink, which comprises a mixture of silver selenide nanowires and photo oil, isophorone solvent; the mass ratio of silver selenide nanowires and photo oil, isophorone solvent is 5.2:2.5:2.3.

[0090] Example 4

[0091] The present example provides a preparation method of the silver selenide nanowire ink in Example 3. Please refer to Figure 1 as shown, comprising the following steps:

[0092] Step S41: The specific steps are to add 1 g of Se02 and 1 g of β-cyclodextrin into a conical flask containing 200 mL of deionized water and stir for 20 min to obtain solution 1.

[0093] Step S42: 1.5 g of ascorbic acid was added to another conical flask containing 200 mL of deionized water and stirred to obtain solution 2.

[0094] Step S43: Next, solution 1 was added dropwise to solution 2 and stirring was continued for 5 hours.

[0095] Step S44: Subsequently, the dark red precipitate was obtained by washing with deionized water and ethanol several times and centrifugation. The final product was obtained after the precipitate was left to stand in anhydrous ethanol for 48 hours. The product was dried by centrifugation to obtain selenium nanowire (Se NWs) powder.

[0096] Step S31: 0.32 g of Se NWs (obtained in step S44) was dispersed in 320 mL of ethylene glycol.

[0097] Step S32: 1.5 g of AgN03 and 4.67 g of glucose were dissolved in 15 mL of deionized water, respectively, and stirred for 5 min to obtain a solution.

[0098] Step S33: Then, the above AgN03 solution (obtained in step S32) was added dropwise into the Se NWs under vigorous stirring. Subsequently, the ascorbic acid solution obtained was added dropwise.

[0099] Step S34: After 6 h of reaction, the dark gray precipitate was centrifuged and washed several times with deionized water and anhydrous ethanol. Finally, the precipitate was dried in a vacuum oven at 40°C.

[0100] Step S10: The components were obtained according to the mass ratio of silver selenide nanowires (obtained in step S34), light oil, and isophorone solvent as 5.2:2.5:2.3.

[0101] Step S20: The components (obtained in step S10) were finally obtained by manual stirring and stirring in a planetary mixer several times to obtain a uniform Ag2Se ink.

[0102] Example 5

[0103] The present example provides a silver selenide nanowire ink, which comprises a mixture of silver selenide nanowires and light oil, isophorone solvent; the mass ratio of silver selenide nanowires and light oil, isophorone solvent is 5.3:2.5:2.2.

[0104] Example 6

[0105] The present example provides a preparation method of the silver selenide nanowire ink in Example 3. Please refer to Figure 1 as shown, comprising the following steps:

[0106] Step S41: The specific steps are to add 1 g of SeO2 and 1 g of β-cyclodextrin into a conical flask containing 200 mL of deionized water and stir for 20 min to obtain solution 1.

[0107] Step S42: 1.5 g of ascorbic acid is added to another conical flask containing 200 mL of deionized water, and stirring is performed to obtain solution 2.

[0108] Step S43: Next, solution 1 is added dropwise into solution 2 and stirring is continued for 5 hours.

[0109] Step S44: Subsequently, multiple washing and centrifugation are performed using deionized water and ethanol to obtain a dark red precipitate. The precipitate is placed in anhydrous ethanol for 48 hours to obtain the final product. After centrifugal drying of the product, selenium nanowire (Se NWs) powder is obtained.

[0110] Step S31: 0.32 g of Se NWs (obtained in step S44) is dispersed in 320 mL of ethylene glycol.

[0111] Step S32: 1.5 g of AgNO3 and 4.5 g of ascorbic acid are respectively dissolved in 15 mL of deionized water and stirred for 5 min to obtain a solution.

[0112] Step S33: Then, the above AgNO3 solution (obtained in step S32) is added dropwise into the Se NWs under vigorous stirring. Subsequently, the resulting ascorbic acid solution is added dropwise.

[0113] Step S34: After 6 h of reaction, the dark gray precipitate is centrifuged and washed multiple times using deionized water and anhydrous ethanol. Finally, the precipitate is dried in a vacuum oven at 40°C.

[0114] Step S10: The components are obtained according to the mass ratio of silver selenide nanowires (obtained in step S34), light oil, and isophorone solvent as 5.3:2.5:2.2.

[0115] Step S20: The components (obtained in step S10) are subjected to multiple manual stirring and stirring in a planetary mixer to finally obtain a uniform Ag2Se ink.

[0116] Example 7

[0117] The present example provides a silver selenide nanowire ink, which comprises a mixture of silver selenide nanowires and light oil, isophorone solvent; the mass ratio of silver selenide nanowires to light oil, isophorone solvent is 5.5:2:2.5.

[0118] Example 8

[0119] The present example provides a preparation method of the silver selenide nanowire ink in Example 3. Please refer toFigure 1 as shown, comprising the steps of:

[0120] Step S41 : The specific steps are to add 1 g of Se02 and 1 g of β-cyclodextrin into a conical flask containing 200 mL of deionized water and stir for 20 min to obtain solution 1.

[0121] Step S42: 1.5 g of ascorbic acid is added to another conical flask containing 200 mL of deionized water, and stirring is obtained to obtain solution 2. Next, solution 1 is added dropwise to solution 2 and stirring is continued for 5 hours.

[0122] Step S43: Subsequently, multiple washing and centrifugation are performed using deionized water and ethanol to obtain a dark red precipitate.

[0123] Step S44: The precipitate is placed in anhydrous ethanol and left to stand for 48 hours to obtain the final product. After centrifugal drying of the product, selenium nanowire (Se NWs) powder is obtained.

[0124] Step S31 : 0.32 g of Se NWs (obtained in step S44) is dispersed in 320 mL of ethylene glycol.

[0125] Step S32: 1.5 g of AgN03 and 4.5 g of ascorbic acid are respectively dissolved in 15 mL of deionized water and stirred for 5 min to obtain a solution.

[0126] Step S33: Then, under vigorous stirring, the above AgN03 solution (obtained in step S32) is added dropwise to the Se NWs. Subsequently, the resulting ascorbic acid solution is added dropwise.

[0127] Step S34: After 6 h of reaction, the dark gray precipitate is centrifuged and washed multiple times using deionized water and anhydrous ethanol. Finally, the precipitate is dried in a vacuum oven at 40 degrees.

[0128] Step S10: The components are obtained according to the mass ratio of silver selenide nanowire (obtained in step S34), varnish, and isophorone solvent being 5.5:2:2.5.

[0129] Step S20: The components (obtained in step S10) are subjected to multiple manual stirring and stirring in a planetary mixer, and finally a uniform Ag2Se ink is obtained.

[0130] Example 9

[0131] This example provides a silver selenide thermoelectric film. The silver selenide nanowire ink in Example 2 is used to form a silver selenide thermoelectric film on paper. Specifically, a film of a specific pattern is prepared by screen printing and sintering annealing at 140°C to prepare a thermoelectric film, which is used for thermoelectric performance and flexibility testing.

[0132] Example 10

[0133] A silver selenide thermoelectric thin film was prepared in this example. The silver selenide nanowire ink in Example 4 was used to form a silver selenide thermoelectric thin film on paper. Specifically, a thin film of a specific pattern was prepared by screen printing and sintering annealing at 140°C to prepare a thermoelectric thin film, which was used for thermoelectric performance and flexibility tests.

[0134] Example 11

[0135] A silver selenide thermoelectric thin film was prepared in this example. The silver selenide nanowire ink in Example 6 was used to form a silver selenide thermoelectric thin film on paper. Specifically, a thin film of a specific pattern was prepared by screen printing and sintering annealing at 140°C to prepare a thermoelectric thin film, which was used for thermoelectric performance and flexibility tests.

[0136] Example 12

[0137] A silver selenide thermoelectric thin film was prepared in this example. The silver selenide nanowire ink in Example 6 was used to form a silver selenide thermoelectric thin film on paper. Specifically, a thin film of a specific pattern was prepared by screen printing and sintering annealing at 140°C to prepare a thermoelectric thin film, which was used for thermoelectric performance and flexibility tests.

[0138] Example 13

[0139] A thermoelectric device was prepared in this example. At least one heating leg was formed from the silver selenide nanowire ink in Example 1. The thermoelectric device was prepared by screen printing and annealing to prepare a thermoelectric prototype device, as shown in the schematic and physical device below Figure 2 and Figure 3 The device had 5 legs, each leg having a width of 5 mm and a length of 25 mm, and was connected in series using liquid metal and was led out by copper wire. Finally, the thermoelectric device was encapsulated using PDMS.

[0140] Comparative Example 1

[0141] Cu2Se / polyimide thermoelectric thin film.

[0142] Comparative Example 2

[0143] Ag2Se / nylon cloth thermoelectric thin film.

[0144] Comparative Example 3

[0145] Ag2Te / paper thermoelectric thin film.

[0146] Comparative Example 4

[0147] Bi2Te3 / paper thermoelectric thin film.

[0148] Comparative Example 5

[0149] Ag2Se / paper thermoelectric film.

[0150] Comparative Example 6

[0151] Ag2Se / paper thermoelectric film.

[0152] Performance test

[0153] (1) In order to test the thermoelectric performance of the silver selenide film, the Seebeck coefficient (S), electrical conductivity (σ) and power factor (PF) of the silver selenide film were tested in detail.

[0154] Figure 4 A Seebeck coefficient of an Ag2Se film in the temperature range of 300K to 420K is provided for Example 2 of the present application. Among them, the Seebeck coefficient and the electrical conductivity are tested as a function of temperature, and the average value is shown in the figure. At room temperature, the Seebeck coefficient is -145.4 μV / K, and as the temperature increases from 301K to 400K, the absolute value of S gradually increases. But when the temperature continues to rise from 400K to 420K, the absolute value of the Seebeck coefficient rapidly decreases from about -161 μV / K to -127.9 μV / K.

[0155] Figure 5 The electrical conductivity of an Ag2Se film in the temperature range of 300K to 420K is provided for Example 2 of the present application. Among them, the electrical conductivity of the silver selenide film is 509.1 S / cm at 301K, and as the temperature increases from 301K to 400K, the electrical conductivity rapidly increases, reaching a maximum value of 1253.8 S / cm at 400K Figure 5 . However, when the temperature rises to 420K, the electrical conductivity sharply decreases to 638.2 S / cm.

[0156] Figure 6 The power factor of an Ag2Se film in the temperature range of 300K to 420K is provided for Example 2 of the present application. Among them, the power factor (PF) of the silver selenide sample at room temperature is 1075.8 μW / m·K 2 , and as the temperature increases, the PF rapidly increases, reaching a peak value of 3250.9 μW / m·K 2 at 400K, which is close to the maximum power factor of 3500 μW / m·K 2 of the silver selenide bulk film reported so far. Subsequently, when the temperature continues to increase, reaching 420K, the power factor sharply decreases to 1043.5 μW / m·K 2 . Figure 6

[0157] ​(2) The resistance and bending performance test was conducted on the thin film prepared by printing the ink in Examples 2, 4, 6 and 8 on the substrate and annealing, and the thermoelectric thin film in Comparative Examples 1 to 6. The results are shown in Table 1.

[0158] Table 1 Comparison of flexibility of flexible thermoelectric material

[0159]

[0160] Figure 7 The application provides a change of resistance ratio with bending times when the bending radius is 9mm. Figure 8 The application provides a change of resistance ratio with bending times when the bending radius is 7mm. The resistance changes of Examples 2, 4, 6 and 8 are relatively small, the bending radius is relatively large, and the bending times are relatively many. Compared with the traditional silver selenide thermoelectric thin film, the silver selenide thermoelectric thin film provided by the application has excellent electrical performance and flexibility.

[0161] (3) Next, the output voltage of the thermoelectric generator in Example 13 was tested by using a self-built instrument, and the circuit diagram is shown in Figure 9 . The experimental results are shown in Figure 10 . The results show that the open circuit voltage of the device is proportional to the temperature difference. When the temperature difference is 60K, the open circuit voltage is about 21mV.

[0162] The above only describes the preferred embodiments of the application and is not intended to limit the application. Any modification, equivalent replacement and improvement made within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. A silver selenide nanowire ink, characterized by, The silver selenide nanowire ink comprises a mixture of silver selenide nanowire, light oil, first isophorone, and the mass ratio of the silver selenide nanowire, light oil, and first isophorone is (5:2.5:2.5)-(5.5:2:2.5). The light oil comprises chloroethylene resin, No. 28-2 resin, curing agent, and second isophorone, and the light oil comprises the following components in the following mass percentages: Chloroethylene resin 35-39%; No. 28-2 resin 13-16%; Curing agent 42-45%; Second isophorone 4-6%.

2. A method of preparing a silver selenide nanowire ink, characterized by, The silver selenide nanowire ink comprises the following steps: Obtaining each component from the components contained in the silver selenide nanowire ink according to claim 1; Mixing the components to obtain the silver selenide nanowire ink.

3. The preparation method of silver selenide nanowire ink as described in claim 2, characterized in that, The silver selenide nanowire powder preparation step further comprises the following steps: Mixing selenium nanowire and a first solvent to obtain a first solution; Mixing AgNO3, a second solvent, and a reducing agent to obtain a second solution containing elemental silver by reduction reaction, wherein the reducing agent comprises any one of ascorbic acid or glucose; Mixing the first solution and the second solution to obtain a third solution containing silver selenide nanowire by oxidation reaction; Impurity removal and drying treatment of the third solution to obtain the silver selenide nanowire.

4. The method for preparing silver selenide nanowire ink as described in claim 3, characterized in that, The mass ratio of the selenium nanowire, AgNO3, and glucose is (1:4:14)-(1:6:16); Or / and, the mass ratio of the selenium nanowire, AgNO3, and ascorbic acid is (1:4:14)-(1:6:16).

5. The method for preparing silver selenide nanowire ink as described in claim 3 or 4, characterized in that, The silver selenide nanowire powder preparation step further comprises the following steps: Mixing SeO2, β-cyclodextrin, and a third solvent to obtain a fourth solution; Mixing ascorbic acid and the fourth solvent to obtain a fifth solution; Mixing the fourth solution and the fifth solution to obtain a sixth solution containing selenium nanowire by reduction reaction; Impurity removal and drying treatment of the sixth solution to obtain the selenium nanowire powder.

6. The method for preparing silver selenide nanowire ink as described in claim 5, characterized in that, The mass ratio of SeO2, β-cyclodextrin, the third solvent, the fourth solvent, and ascorbic acid is 1:1:1.5:

200.

7. A silver selenide thermoelectric film, characterized by, The silver selenide thermoelectric film formed by curing the silver selenide nanowire ink according to claim 1 on a substrate.

8. A thermoelectric device, characterized by, The silver selenide nanowire ink according to claim 1 is cured to form at least one electric heating leg.

9. The thermoelectric device as described in claim 8, characterized in that, The electric heating legs are connected in series by liquid metal to form a conductive circuit, and lead-out electrodes are arranged at both ends of the conductive circuit; Or / and, the width of the electric heating leg is 5-7 mm, and the length is 25-30 mm.

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