A high thermoelectric performance PEDOT:PSS / CNTs thermoelectric composite film and a preparation method thereof

Abstract

The application belongs to the technical field of thermoelectric material preparation, in particular, relates to a high-thermoelectric-performance PEDOT:PSS / CNTs thermoelectric composite film and a preparation method thereof. The application uniformly mixes PEDOT:PSS and CNTs to obtain a mixed solution; the mixed solution is coated on a substrate to obtain a PEDOT:PSS / CNTs composite film; and the PEDOT:PSS / CNTs composite film is subjected to surface treatment by using an ionic liquid methanol solution, so that the PEDOT:PSS / CNTs thermoelectric composite film is obtained. The application obtains the high-thermoelectric-performance PEDOT:PSS / CNTs thermoelectric film through two-step operations of a physical blending method and ionic liquid surface treatment, the preparation method is simple, the thermoelectric performance is significantly improved, and the obtained PEDOT:PSS / CNTs thermoelectric film has relatively high electrical conductivity and Seebeck coefficient, and has relatively high power factor.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of thermoelectric material preparation, and particularly relates to a high-thermoelectric-performance PEDOT:PSS / CNTs thermoelectric composite film and a preparation method thereof. BACKGROUND

[0002] Thermoelectric technology uses efficient thermoelectric materials to convert collected heat into electrical energy, providing a huge green energy source for human society. Inorganic thermoelectric materials have the advantages of excellent thermoelectric performance, but have the disadvantages of fragile texture and high content of toxic heavy metals; while organic thermoelectric materials have the advantages of low cost, supporting processing and solution production, but have the disadvantage of poor thermoelectric performance. For example, PEDOT:PSS materials have outstanding advantages in terms of electrical conductivity and film-forming property, and are highly concerned in the fields of organic electronic research and application.

[0003] At present, there are various methods to improve the thermoelectric performance of PEDOT system, such as doping, side chain engineering and multi-component composite strategy. In addition to the above methods, the performance of PEDOT can also be improved by simple post-processing methods. In recent years, the post-processing methods of PEDOT include acid-base treatment, inorganic salt solution treatment and polar solvent treatment. The thermoelectric performance of PEDOT can be improved by changing its phase separation structure and conformation. However, these post-processing schemes usually involve complex processing steps, and some steps may even require toxic and harmful chemicals, which may constitute an obstacle to the large-scale production and application of PEDOT. Therefore, it is very necessary to develop a new method to enhance the thermoelectric performance of PEDOT:PSS (poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonic acid)) film. SUMMARY

[0004] The purpose of the present application is to provide a high-thermoelectric-performance PEDOT:PSS / CNTs thermoelectric composite film and a preparation method thereof, and the obtained film has higher electrical conductivity and Seebeck coefficient, so as to solve the problems existing in the prior art.

[0005] To achieve the above-mentioned purpose, the present application provides the following solutions.

[0006] One of the technical solutions of the present application provides a preparation method of a high-thermoelectric-performance PEDOT:PSS / CNTs thermoelectric composite film, and the steps include:

[0007] mixing PEDOT:PSS aqueous solution and carbon nanotubes (CNTs) uniformly to obtain a mixed solution;

[0008] coating the mixed solution on a substrate to obtain a PEDOT:PSS / CNTs composite film;

[0009] The PEDOT:PSS / CNTs composite film is surface treated with an ionic liquid methanol solution, to obtain the PEDOT:PSS / CNTs thermoelectric composite film.

[0010] Further, the PEDOT:PSS aqueous solution is Clevios PH1000.

[0011] Further, the volume concentration of CNTs in the mixed solution is 10-50%, preferably 40-50%.

[0012] Further, the substrate is a glass sheet, a silicon wafer or a PET substrate.

[0013] Further, the coating amount is 0.02 mL / cm 2 .

[0014] Further, the volume concentration of the ionic liquid in the ionic liquid methanol solution is 10-50%, preferably 20-50%.

[0015] Further, the ionic liquid is 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIM-BF4), 1-allyl-3-methylimidazolium tetrafluoroborate (AMIM BF4) or 1-allyl-3-methylimidazolium bis(trifluoromethanesulfonyl) imide (AMIM NTF2).

[0016] Further, the amount of the ionic liquid methanol solution used is 0.02 mL / cm 2 .

[0017] Further, the surface treatment step comprises:

[0018] The ionic liquid methanol solution is added dropwise on the surface of the PEDOT:PSS / CNTs composite film, and after standing, spin coating is performed.

[0019] Preferably, the standing time is 10 min.

[0020] Preferably, the spin coating parameters are: the first step speed of the spin coater is 1000 rpm, the time is 30 seconds, and the acceleration is 100 rpm s -1 , the second step speed of the spin coater is 5000 rpm, the time is 30 seconds, and the acceleration is 1000 rpm s -1 .

[0021] Further, it also comprises, after surface treatment, standing at 60°C for 10 min, cooling, washing with ethanol at least once, and then drying at 60°C for 30 min.

[0022] The second technical scheme of the present application provides a high thermoelectric performance PEDOT:PSS / CNTs thermoelectric composite film prepared by the above preparation method.

[0023] The PEDOT:PSS / CNTs thermoelectric composite film of the present application is prepared by compounding PEDOT:PSS and CNTs through a physical blending method, and then performing surface treatment by using an ionic liquid methanol solution, and has high electrical conductivity and Seebeck coefficient. The PEDOT:PSS / CNTs thermoelectric composite film has high electrical conductivity due to two factors, one is the carrier concentration, and the other is the conductive structure. In the first step, CNTs are added to the PEDOT:PSS aqueous solution through the physical blending method, and as the amount of CNTs mixed in increases, the electrical conductivity of the composite film increases. CNTs have a conjugated polyene structure, and the π electrons exhibit strong delocalization, which forms a new conjugated system with the π electrons on the thiophene ring backbone through π-π conjugation, and forms a carrier transport channel, which is conducive to improving the transport of carriers, thereby improving the electrical conductivity of the composite. When the content of CNTs is 50%, the electrical conductivity of the sample decreases to 90.1 S cm -1 , which is mainly due to the uneven dispersion of CNTs, which blocks the connection between the PEDOT molecular chains, resulting in a downward trend of the electrical conductivity of the composite. In the second step, the ionic liquid (IL) treatment can adjust the oxidation level, and the ionic liquid EMIM-BF4 acts as a secondary dopant, and the interaction between PEDOT and PSS is weakened by the ionic liquid treatment, which induces the phase separation between PEDOT and PSS, and part of the Tos is removed in the subsequent washing process, and the conductive network structure is further optimized, so that the electrical conductivity is increased.

[0024] The third technical scheme of the present application provides a method for maintaining stable Seebeck coefficient while improving the electrical conductivity and power factor of the PEDOT:PSS / CNTs film, which comprises the following steps:

[0025] mixing PEDOT:PSS aqueous solution and CNTs uniformly to obtain a mixed solution;

[0026] coating the mixed solution on a substrate to obtain a PEDOT:PSS / CNTs composite film;

[0027] performing surface treatment on the PEDOT:PSS / CNTs composite film by using an ionic liquid methanol solution, to obtain the PEDOT:PSS / CNTs thermoelectric composite film.

[0028] The present application discloses the following technical effects:

[0029] The application provides a high thermoelectric performance PEDOT:PSS / CNTs thermoelectric composite film, a PEDOT:PSS / CNTs composite film is prepared by a first step of using a physical blending method, compared with a PEDOT:PSS material, the Seebeck coefficient and the conductivity are increased; a second step of ion liquid treatment can significantly improve the conductivity, while maintaining the relative stability of the Seebeck coefficient; the obtained PEDOT:PSS / CNTs thermoelectric film has higher conductivity and Seebeck coefficient, and has higher power factor.

[0030] The application composites organic thermoelectric materials with inorganic micro-nano materials, and prepares organic thermoelectric materials with better comprehensive performance, and the improvement strategy can be introduced into other material systems, and thus the performance of the other material systems is improved.

[0031] The application obtains the high thermoelectric performance PEDOT:PSS / CNTs thermoelectric film by two steps of a physical blending method and ion liquid surface treatment, the preparation method is simple, the thermoelectric performance is significantly improved, the used EMIM-BF4 ion liquid is a green solvent, has the advantages of low volatility, stability and easy recovery, compared with strong acid, strong base or other toxic reagents used in traditional methods, has the advantages of simple and safe operation. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings in the following description are only some embodiments of the application, and for those skilled in the art, other drawings can be obtained from these drawings without creative labor.

[0033] Figure 1 The conductivity of the PEDOT:PSS film in Comparative Example 1 and the PEDOT:PSS / CNTs composite film in Examples 1-5;

[0034] Figure 2 The Seebeck coefficient of the PEDOT:PSS film in Comparative Example 1 and the PEDOT:PSS / CNTs composite film in Examples 1-5;

[0035] Figure 3 The power factor of the PEDOT:PSS film in Comparative Example 1 and the PEDOT:PSS / CNTs composite film in Examples 1-5;

[0036] Figure 4Seebeck coefficient of the PEDOT:PSS / CNTs composite film and the high thermoelectric performance PEDOT:PSS / CNTs thermoelectric composite film in Example 1, and the high thermoelectric performance PEDOT:PSS / CNTs thermoelectric composite films in Examples 6 to 7;

[0037] Figure 5 Seebeck coefficient of the PEDOT:PSS / CNTs composite film and the high thermoelectric performance PEDOT:PSS / CNTs thermoelectric composite film in Example 1, and the high thermoelectric performance PEDOT:PSS / CNTs thermoelectric composite films in Examples 6 to 7;

[0038] Figure 6 Power factor of the PEDOT:PSS / CNTs composite film and the high thermoelectric performance PEDOT:PSS / CNTs thermoelectric composite film in Example 1, and the high thermoelectric performance PEDOT:PSS / CNTs thermoelectric composite films in Examples 6 to 7. DETAILED DESCRIPTION

[0039] Various illustrative embodiments of the present application are now described in detail below. The embodiments discussed herein should not be taken as indicative of all embodiments of the present application, but rather exemplary of certain aspects, features and implementations of the present application.

[0040] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. Additionally, the use of the term "about" in the present application is intended to mean that the value is within a standard range of error for the particular measurement. In any statement of value or range of values, the term "about" is intended to encompass intermediate values and ranges that are within the standard range of error for the particular measurement. The upper and lower limits of these smaller ranges can independently be included or excluded from the range.

[0041] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application. All documents mentioned herein are incorporated by reference to disclose and describe the methods and / or materials in connection with which the documents are cited. In case of conflict between the present specification and any document incorporated by reference, the present specification will control.

[0042] Various modifications and changes can be made to the specific embodiments of the present application described herein without departing from the scope or spirit of the application. Other embodiments of the application will be apparent to those of ordinary skill in the art from the description and examples presented herein. The description and examples presented herein are illustrative only and should not be considered to narrow the scope of the application in any way. Those of ordinary skill in the art will recognize, or be able to ascertain, using no more than routine experimentation, many equivalents to the specific embodiments described herein. The scope of the application is not to be limited by the specific descriptions and examples given above.

[0043] As used herein, the terms "comprise", "include", "have", "contain", and the like are open-ended terms, i.e., meaning "including but not limited to".

[0044] The raw materials and reagents used in the embodiments of the present application are commercially available products.

[0045] The PEDOT:PSS aqueous solution used in the embodiments of the present application is provided by Hekster Company, and the trade name is Clevios PH1000, wherein the weight ratio of PEDOT and PSS is 1:2.5, and the concentration is 1.3wt%.

[0046] The substrate used in the embodiments of the present application is a glass sheet, and it is necessary to note that the substrate is a carrier of the thin film in the present application, and the same technical effects can be achieved when other substrates (silicon wafer or PET substrate) defined in the present application are used, and therefore, they can be equally replaced based on their roles in the present application.

[0047] The ionic liquid used in the embodiments of the present application is 1-ethyl-3-methyl imidazole tetrafluoroborate (EMIM-BF4), and it is necessary to note that based on the role of the ionic liquid in the present application, the three kinds of ionic liquids defined in the present application can be equally replaced among 1-ethyl-3-methyl imidazole tetrafluoroborate (EMIM-BF4), 1-allyl-3-methyl imidazole tetrafluoroborate (AMIM BF4) and 1-allyl-3-methyl imidazole bis(trifluoromethanesulfonyl) imidazolium (AMIM NTF2).

[0048] Example 1

[0049] The preparation steps of the high-thermoelectric-performance PEDOT:PSS / CNTs thermoelectric composite thin film are as follows:

[0050] S1, after mixing the PEDOT:PSS aqueous solution (Clevios PH1000) and CNTs, continuously stirring for 12 hours using a magnetic stirrer, a uniform mixed solution with a CNTs volume concentration of 40% is configured;

[0051] S2, a glass sheet is selected as the substrate, and the glass sheet (1cm x 1cm) is ultrasonically cleaned with deionized water, acetone and isopropanol for 15 minutes, and then the surface of the glass sheet is blown dry using a nitrogen gun, and the glass sheet is laid flat in a culture dish, and the glass sheet is treated by oxygen plasma at a power of 80W and an oxygen flow rate of 0.3-0.4mbar for 10 minutes, and the clean substrate is stored in the culture dish for standby;

[0052] S3, the glass substrate obtained in step S2 is taken out and placed in a mask plate, and the mask plate is placed in an inorganic evaporation chamber to prepare a chromium-gold electrode; the evaporation rate of the chromium (Cr) electrode is The evaporation film thickness is 4 nm; the evaporation rate of the gold (Au) electrode is The evaporation film thickness is 30 nm; after evaporation, the sample is taken out, the glass sheet is removed with tweezers, and placed in a clean culture dish for use;

[0053] S4, the glass sheet with the chromium-gold electrode is treated with oxygen plasma at a power of 100 W and an oxygen flow rate of 0.3-0.4 mbar for 10 minutes, and then placed at the center of a spin coater, 20 μL of the mixed solution obtained in step S1 is taken with a pipette and uniformly coated on the surface of the glass sheet, and then placed in a vacuum oven at 50°C for drying, to obtain a PEDOT:PSS / CNTs composite film with a CNTs volume concentration of 40%;

[0054] S5, prepare a 20% EMIM BF4 methanol solution: at room temperature, dissolve EMIM BF4 in methanol, and ultrasonically oscillate the prepared solution for 24 hours to form a uniform solution;

[0055] S6, spin-coat 20 μL of the EMIM BF4 methanol solution on the PEDOT / CNTs composite film, and start the spin coater for two-step film spinning; the first step of the spin coater is at a speed of 1000 rpm for 30 seconds, with an acceleration of 100 rpm s -1 The second step of the spin coater is at a speed of 5000 rpm for 30 seconds, with an acceleration of 1000 rpm s -1 After spin-coating, the sample is placed on a hot stage at 60°C for 10 minutes, and naturally cooled, then washed with anhydrous ethanol 3 times to remove the residual EMIM-BF4 on the surface, and then placed on a hot stage at 60°C for drying for 30 minutes, to obtain a film treated with a 20% EMIM BF4 methanol solution, which is denoted as a high-thermoelectric-performance PEDOT:PSS / CNTs thermoelectric composite film.

[0056] Example 2

[0057] Compared with Example 1, the only difference is that the volume concentration of CNTs in the mixed solution in step S1 is 50%.

[0058] Example 3

[0059] Compared with Example 1, the only difference is that the volume concentration of CNTs in the mixed solution in step S1 is 10%.

[0060] Example 4

[0061] The difference compared with Example 1 is only that the volume concentration of CNTs in the mixed solution in step S1 is 20%.

[0062] Example 5

[0063] The difference compared with Example 1 is only that the volume concentration of CNTs in the mixed solution in step S1 is 30%.

[0064] Example 6

[0065] The difference compared with Example 1 is only that the volume concentration of CNTs in the mixed solution in step S1 is 30%.

[0066] Example 7

[0067] The difference compared with Example 1 is only that the volume concentration of CNTs in the mixed solution in step S1 is 30%.

[0068] Comparative Example 1

[0069] The preparation steps of the PEDOT:PSS film are as follows:

[0070] S1, select a glass sheet as a substrate, and clean the glass sheet (1 cm x 1 cm) with deionized water, acetone, and isopropanol for 15 minutes, then blow dry the surface of the glass sheet with a nitrogen gun, and lay it flat on a culture dish, and treat the glass sheet with oxygen plasma at a power of 80 W and an oxygen flow rate of 0.3-0.4 mbar for 10 minutes, and store the clean substrate in the culture dish for use;

[0071] S2, take out the glass sheet substrate obtained in step S1 and place it in a mask plate, and place the mask plate in the inner cavity of the inorganic evaporation, and prepare a chromium-gold electrode; the evaporation rate of the chromium (Cr) electrode is the evaporation film thickness is 4 nm; the evaporation rate of the gold (Au) electrode is the evaporation film thickness is 30 nm; after evaporation, take out the sample, remove the glass sheet with tweezers, and place it in a clean culture dish for use;

[0072] S3, treat the glass sheet with chromium-gold electrode with oxygen plasma at a power of 100 W and an oxygen flow rate of 0.3-0.4 mbar for 10 minutes, and place it at the center of the spin coater after cleaning, and use a pipette to take 20 μL of PEDOT:PSS to evenly cover the surface of the glass sheet, and start the spin coater to spin the film by two-step method, the first step of the spin coater is 1000 rpm, the time is 30 seconds, and the acceleration is 100 rpm s -1The second step of the glue machine is 5000 rpm, the time is 30 seconds, and the acceleration is 1000 rpm s -1 , and then dried in a vacuum oven at 50°C to obtain a PEDOT:PSS film.

[0073] Test example

[0074] The conductivity, Seebeck coefficient and power factor of the PEDOT:PSS film in Comparative Example 1, the PEDOT:PSS / CNTs composite films in Examples 1 to 7 and the PEDOT:PSS / CNTs thermoelectric composite films in Examples 1 to 7 were tested. The results are as follows: Figures 1-6 shown.

[0075] Figure 1 is the electrical conductivity of the PEDOT:PSS film in Comparative Example 1 and the PEDOT:PSS / CNTs composite films in Examples 1 to 5; Figure 2 is the Seebeck coefficient of the PEDOT:PSS film in Comparative Example 1 and the PEDOT:PSS / CNTs composite films in Examples 1 to 5; Figure 3 The power factors of the PEDOT:PSS film in Comparative Example 1 and the PEDOT:PSS / CNTs composite films in Examples 1 to 5 are shown in FIG. In the figure, the abscissa represents the volume concentration of CNTs in the mixed solution when the composite films were prepared in Examples and Comparative Examples.

[0076] Depend on Figures 1-3 It can be seen that at room temperature, the conductivity of the PEDOT:PSS film in Comparative Example 1 (CNTs addition amount is 0) is 7.5S cm -1 , the Seebeck coefficient is 17.7μV K -1 As the amount of CNTs added increases, the conductivity of the composite film increases. In Examples 3 to 5, the addition amount of CNTs is 10%, 20%, and 30%, respectively. The conductivity, Seebeck coefficient, and power factor are all improved. The conductivity is 22.3, 33.2, and 49.9 S cm, respectively. -1 ( Figure 1 ), and the Seebeck coefficients are 21.9 μV K -1 , 28.8μV K -1 、34.9μV K -1 ( Figure 2 When the volume concentration of CNTs is 10% (Example 3), the power factor is 1.08 μW m -1 K -2 , continue to increase the CNTs content to 30% (Example 5), the power factor gradually increases ( Figure 3). In summary, the PEDOT:PSS / CNTs thermoelectric composite film of Example 1 with a CNTs volume concentration of 40% has the best thermoelectric performance, with an electrical conductivity of 177.5 S cm -1 S cm -1 , a Seebeck coefficient of 40.2 μW m -1 K -2 , and a corresponding power factor of 28.71 μW m -1 K -2 .

[0077] Figure 4 is the electrical conductivity of the PEDOT:PSS / CNTs composite film and the high thermoelectric performance PEDOT:PSS / CNTs thermoelectric composite film of Example 1, the high thermoelectric performance PEDOT:PSS / CNTs thermoelectric composite film of Examples 6-7, Figure 5 is the Seebeck coefficient of the PEDOT:PSS / CNTs composite film and the high thermoelectric performance PEDOT:PSS / CNTs thermoelectric composite film of Example 1, the high thermoelectric performance PEDOT:PSS / CNTs thermoelectric composite film of Examples 6-7, Figure 6 is the power factor of the PEDOT:PSS / CNTs composite film and the high thermoelectric performance PEDOT:PSS / CNTs thermoelectric composite film of Example 1, the high thermoelectric performance PEDOT:PSS / CNTs thermoelectric composite film of Examples 6-7. In the figures, the abscissa is the volume fraction of the EMIM BF4methanol solution used to prepare the composite film of the examples and comparative examples.

[0078] It can be seen from Figures 4-6 that the electrical conductivity of the PEDOT:PSS / CNTs composite film at room temperature is 177.5 S cm -1 , and the electrical conductivity is improved after surface treatment with the EMIM BF4methanol solution. In Examples 6-7, when the PEDOT:PSS / CNTs composite film is surface treated with 10% and 50% EMIM BF4methanol solution, respectively, the electrical conductivity is improved to 282.9 S cm -1 and 373.1 S cm -1 ( Figure 4 ), respectively; the Seebeck coefficient of the high thermoelectric performance PEDOT:PSS / CNTs thermoelectric composite film of Example 1 and Examples 6-7 fluctuates within a small range between 42 μV K -1 and 46 μV K -1 ( Figure 5 ); and the power factor of the PEDOT:PSS / CNTs composite film (28.71 μW m -1 K -2) compared with the PEDOT:PSS / CNTs composite film, the power factor of the PEDOT:PSS / CNTs thermoelectric composite film of Example 6 and Example 7 is increased to 51.86 μW m -1 K -2 and 74.65 μW m -1 K -2 ( Figure 6 ), respectively. -1 The PEDOT:PSS / CNTs thermoelectric composite film of Example 1 has the best effect, and the conductivity is increased to 465.2 S cm -1 , the Seebeck coefficient changes little and remains stable, and the power factor is 95.96 μW m -2 K , which is more than three times the power factor of the PEDOT:PSS / CNTs composite film.

[0079] The above-described examples are only used to describe the preferred modes of the present application, and do not limit the scope of the present application. Various modifications and improvements to the technical solutions of the present application made by those skilled in the art without departing from the design spirit of the present application shall fall within the protection scope of the present application.

Claims

1. A method for preparing a high thermoelectric performance PEDOT:PSS / CNTs thermoelectric composite film, characterized in that the steps include: The PEDOT:PSS aqueous solution and CNTs were mixed uniformly to obtain a mixed solution; coating the mixed solution on a substrate to obtain a PEDOT:PSS / CNTs composite film; Surface treatment of the PEDOT:PSS / CNTs composite film is performed using an ionic liquid methanol solution to obtain the PEDOT:PSS / CNTs thermoelectric composite film; The volume concentration of the ionic liquid in the ionic liquid methanol solution is 10-50%; the ionic liquid is 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-allyl-3-methylimidazolium tetrafluoroborate or 1-allyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide; the amount of the ionic liquid methanol solution is 0.02 mL / cm 2 .

2. The preparation method according to claim 1, wherein The volume concentration of CNTs in the mixed solution is 10-50%.

3. The preparation method according to claim 1, wherein The substrate is a glass sheet, a silicon sheet or a PET substrate; the coating amount is 0.02 mL / cm 2 .

4. The preparation method according to claim 1, wherein The surface treatment step includes: dripping the ionic liquid methanol solution onto the surface of the PEDOT:PSS / CNTs composite film, allowing it to stand and then spin coating.

5. The preparation method according to claim 4, wherein The standing time is 10 min; the spin coating parameters are: the first step speed of the spin coater is 1000 rpm, the time is 30 seconds, and the acceleration is 100 rpm s -1 The second step of the glue machine is 5000 rpm, the time is 30 seconds, and the acceleration is 1000 rpm s -1 .

6. The preparation method according to claim 1, wherein The method further includes standing the surface at 60° C. for 10 minutes after the surface treatment, cooling the surface, rinsing the surface at least once with ethanol, and then drying the surface at 60° C. for 30 minutes.

7. A PEDOT:PSS / CNTs thermoelectric composite film with high thermoelectric performance prepared by the preparation method according to any one of claims 1 to 6.

8. A method for improving the conductivity and power factor of PEDOT:PSS / CNTs films while maintaining a stable Seebeck coefficient, characterized in that: The high thermoelectric performance PEDOT:PSS / CNTs thermoelectric composite film according to claim 7 is used, and the steps include: The PEDOT:PSS aqueous solution and CNTs were mixed uniformly to obtain a mixed solution; coating the mixed solution on a substrate to obtain a PEDOT:PSS / CNTs composite film; The PEDOT:PSS / CNTs composite film is surface treated by using an ionic liquid methanol solution to obtain the PEDOT:PSS / CNTs thermoelectric composite film.

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