High-conductivity PEDOT: PSS film and preparation method thereof

Abstract

The invention belongs to the technical field of conductive films, and particularly relates to a high-conductivity PEDOT: PSS film and a preparation method thereof.The preparation method comprises the steps that a PEDOT: PSS aqueous solution and an additive are mixed, and PEDOT: PSS micelles are pretreated through the additive; the additive is prepared from one or more of triethylamine, N-methyl pyrrolidone, dichloromethane, dimethyl sulfoxide, normal hexane and cyclohexane; preparing a PEDOT: PSS basic film from the treated PEDOT: PSS aqueous solution; carrying out surface treatment on the PEDOT: PSS basic film by using sulfuric acid; and the PEDOT: PSS base film after surface treatment is washed with water to obtain the PEDOT: PSS film, so that the conductivity of the PEDOT: PSS film can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of conductive films, and more specifically, to a PEDOT:PSS film with high conductivity and a preparation method thereof. Background Art

[0002] PEDOT:PSS (Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)) film is the most successful conductive polymer so far. It has good conductivity, flexibility and light transmittance. It can be dispersed in water and can be solution processed. It is one of the most commonly used interface layer materials. However, if it is used as an independent electrode to completely replace ITO and metal, its conductivity is not enough. The conductivity of PEDOT:PSS film directly obtained by spin coating from aqueous solution is less than 1 S / cm, which limits the wider application of PEDOT:PSS film. Summary of the invention

[0003] The present application is provided to solve the above defects in the prior art. A high-conductivity PEDOT:PSS film and a preparation method thereof are needed to improve the conductivity of the PEDOT:PSS film.

[0004] In a first aspect of the present application, a method for preparing a PEDOT:PSS film with high conductivity is provided, the preparation method comprising: mixing a PEDOT:PSS aqueous solution and an additive, pretreating PEDOT:PSS micelles with the additive, the additive comprising one or more of triethylamine, N-methylpyrrolidone, dichloromethane, dimethyl sulfoxide, n-hexane and cyclohexane; preparing a PEDOT:PSS base film from the treated PEDOT:PSS aqueous solution; surface treating the PEDOT:PSS base film with sulfuric acid; and washing the surface-treated PEDOT:PSS base film with water to obtain a flexible PEDOT:PSS film.

[0005] In a second aspect of the present application, a PEDOT:PSS film obtained by the preparation method described in any embodiment of the present application is provided.

[0006] The highly conductive PEDOT:PSS film and its preparation method provided in each embodiment of the present application utilize additives and sulfuric acid to synergistically treat the PEDOT:PSS film, and on the basis of increasing the micelle size, further weaken the interaction between PEDOT and PSS, and remove part of the PSS, so that the finally obtained PEDOT:PSS film can have a higher conductivity; transparent paper electrodes are prepared with good light transmittance and conductivity; they can be used for electrode materials, etc., and as an electrode material, they have the potential to replace ITO electrodes and may become a new generation of electrode materials for flexible organic solar cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] In the drawings, which are not necessarily drawn to scale, the same reference numerals may describe similar parts in different views. The same reference numerals with letter suffixes or different letter suffixes may represent different instances of similar parts. The accompanying drawings generally illustrate various embodiments by way of example and not limitation, and together with the specification and claims, are used to illustrate the embodiments applied for. When appropriate, the same reference numerals are used throughout the drawings to refer to the same or similar parts. Such embodiments are illustrative and are not intended to be exhaustive or exclusive embodiments of the present apparatus or method.

[0008] Figure 1 Surface morphology of a PEDOT:PSS base film according to an embodiment of the present application is shown, wherein (a) represents a PEDOT:PSS base film obtained from a comparative sample, and (b) represents a PEDOT:PSS base film treated with n-hexane; Figure 2 A comparison chart showing the sizes of PEDOT:PSS micelles of a comparative sample and different additives according to an embodiment of the present application. DETAILED DESCRIPTION

[0009] In order to enable those skilled in the art to better understand the technical solution of the present application, the present application is described in detail below in conjunction with the accompanying drawings and specific implementation examples. The embodiments of the present application are further described in detail below in conjunction with the accompanying drawings and specific implementation examples, but are not intended to limit the present application.

[0010] The words "first", "second" and similar words used in this application do not indicate any order, quantity or importance, but are only used to distinguish. The words "include" or "comprise" and similar words mean that the elements before the word include the elements listed after the word, and do not exclude the possibility of including other elements.

[0011] According to an embodiment of the present application, a method for preparing a PEDOT:PSS film with high conductivity is provided, the preparation method comprising: mixing a PEDOT:PSS aqueous solution and an additive, pretreating micelles in the PEDOT:PSS aqueous solution with the additive, the additive comprising one or more of triethylamine, N-methylpyrrolidone, dichloromethane, dimethyl sulfoxide, n-hexane and cyclohexane; preparing a PEDOT:PSS base film from the treated PEDOT:PSS aqueous solution; surface treating the PEDOT:PSS base film with sulfuric acid; and washing the surface-treated PEDOT:PSS base film with water to obtain a PEDOT:PSS film.

[0012] The solvent of the PEDOT:PSS aqueous solution is water, and the solid solution in the PEDOT:PSS aqueous solution is a mixture of 3,4-ethylenedioxythiophene (Poly(3,4-ethylenedioxythiophene)) and poly(styrenesulfonate) (Poly(styrenesulfonate)). The PEDOT:PSS film finally obtained is a flexible film.

[0013] First, the micelle size can be increased by additive treatment to make the PEDOT chain more stretched, and then sulfuric acid treatment can reduce the interaction between PEDOT and PSS. Through such synergistic effect, the square resistance of the PEDOT:PSS film can be further reduced.

[0014] After sulfuric acid treatment, water washing can remove water-soluble non-conductive PSS to improve the conductivity.

[0015] In some embodiments, the additive includes one or more of dichloromethane, n-hexane and cyclohexane. Or the additive includes triethylamine, or the additive includes N-methylpyrrolidone and dimethyl sulfoxide. Different additives have different properties and different amounts of them entering into PEDOT:PSS micelles.

[0016] During the additive treatment, dichloromethane, n-hexane and cyclohexane can enter the micelles better and increase the size of the micelles. The effect after acid treatment is better, that is, the square resistance after acid treatment is smaller and the conductivity is higher.

[0017] During the additive treatment, triethylamine enters the micelle in a smaller amount than dichloromethane, n-hexane and cyclohexane, and increases the size of the micelle to a smaller extent. There is a large interaction between alkaline triethylamine and acidic PSS, which can assist in the removal of PSS by water washing, so the sheet resistance of the PEDOT:PSS base film before acid treatment is extremely large, but the effect after acid treatment is better, that is, the sheet resistance after acid treatment is smaller and the conductivity is high.

[0018] N-methylpyrrolidone and dimethyl sulfoxide are polar and can loosen the interaction between PEDOT and PSS. Therefore, the square resistance of the PEDOT:PSS base film before acid treatment is small, and the amount entering the micelle is small. After acid treatment, the square resistance is greatly improved, and the final conductivity is not very high.

[0019] In contrast, some other reagents do not have good effects. For example, during the additive treatment, the amount of tetrahydrofuran and acetone entering the micelles is small, and the micelle size is not changed much. The square resistance of the PEDOT:PSS base film before acid treatment is extremely large, and the improvement of the square resistance after acid treatment is relatively small. Another example is ethanol. During the additive treatment, ethanol did not enter the micelles, and the micelle size was not changed much. The square resistance of the PEDOT:PSS base film before acid treatment is extremely large, and the improvement of the square resistance after acid treatment is relatively small.

[0020] Therefore, only when a large amount of additives enter the PEDOT:PSS micelles during the treatment process and cooperate with the treatment of sulfuric acid can the square resistance be reduced to a large extent and the conductivity be improved.

[0021] In some embodiments, the volume ratio of the PEDOT:PSS aqueous solution to the additive is 4-8: 1. Preferably, the volume ratio of the PEDOT:PSS aqueous solution to the additive is 5-7: 1; further preferably, the volume ratio of the PEDOT:PSS aqueous solution to the additive is 6: 1.

[0022] In some embodiments, the solid solute in the PEDOT:PSS aqueous solution is PEDOT:PSS, and the mass fraction of the solid solute in the PEDOT:PSS aqueous solution is 1.3-1.7%.

[0023] In some embodiments, the concentration of sulfuric acid is 0.5-5 mol / L.

[0024] In some embodiments, surface treating the PEDOT:PSS base film with sulfuric acid comprises: immersing the PEDOT:PSS base film in a sulfuric acid solution. Preferably, the immersion time in the sulfuric acid solution is 1-5 seconds. Preferably, the immersion time in the sulfuric acid solution is 2-4 seconds.

[0025] In some embodiments, the PEDOT:PSS base film is surface treated with sulfuric acid once or twice in succession. In some embodiments, the PEDOT:PSS base film is first washed by immersion in water before the second sulfuric acid treatment. After two acid treatments, the sheet resistance of the PEDOT:PSS base film can be further reduced.

[0026] In some embodiments, stirring or ultrasonic treatment is performed during the treatment of micelles in the PEDOT:PSS aqueous solution with additives to promote the additives to enter the PEDOT:PSS micelles.

[0027] In some embodiments, the PEDOT:PSS micelles are treated with the additive for 10-20 hours.

[0028] In some embodiments, the method for preparing a PEDOT:PSS base film from a treated PEDOT:PSS aqueous solution comprises: coating the treated PEDOT:PSS aqueous solution on a glass substrate, and drying and shaping to obtain a PEDOT:PSS base film.

[0029] In some embodiments, before coating the treated PEDOT:PSS aqueous solution on the glass substrate, the glass substrate is pretreated, and the pretreatment method includes: sequentially cleaning, drying, and sterilizing the glass substrate.

[0030] According to an embodiment of the present application, a PEDOT:PSS film obtained by the preparation method described in any embodiment of the present application is also provided.

[0031] Example 1 (1) According to the ratio of PEDOT:PSS to additives of 180 μL:20 μL, triethylamine, N-methylpyrrolidone, dichloromethane, dimethyl sulfoxide, n-hexane and cyclohexane were added to nine identical PEDOT:PSS aqueous solutions, respectively. In addition, control samples and blank samples were set. The control samples included ethanol, tetrahydrofuran and acetone, respectively. No additives were added to the blank samples. The blank samples and PEDOT:PSS aqueous solutions corresponding to the different additives were obtained. The solution was placed on a magnetic stirrer, and the speed of the magnetic stirrer was set to the fourth gear for 16 h.

[0032] (2) Glass substrate cleaning and surface treatment Use a laboratory glass cutter to take enough 1.5 cm × 1.5 cm glass substrates. First, insert the glass into the bracket in turn, then put it into a 500 mL beaker, add deionized water and glass cleaning solution, seal it with tin foil, and ultrasonically clean it for 60 min. Then, use deionized water to ultrasonically clean for 10 min to remove the residual cleaning solution, and repeat two to three times. Finally, use acetone and ethanol to ultrasonically clean for 10 min in turn. After cleaning, put the glass piece in an oven to dry. After the glass piece is dry, put the glass substrate into a UV ozone cleaner for 10 min to improve the wettability of the glass substrate surface and facilitate film formation.

[0033] (3) Preparation of PEDOT:PSS film In this experiment, the PEDOT:PSS film was prepared by spin coating. The specific operation was as follows: a glass substrate was placed on a coater and sucked; 20 μL of the blank sample, the control sample and the PEDOT:PSS aqueous solution corresponding to different additives were taken with a pipette and dropped in the middle of the corresponding glass substrate; tweezers were used to evenly spread the solution on the glass substrate; the coater was started, the spin coating speed was 1500 r / min, and the film was rotated for 30 s; then the PEDOT:PSS base film was dried and fixed at 150 °C for 20 min to obtain the PEDOT:PSS base films corresponding to the control sample and different additives.

[0034] The surface morphology of the blank sample, the control sample and the PEDOT:PSS base film corresponding to n-hexane was detected using an atomic force microscope (AFM). The results are as follows: Figure 1 As shown, through Figure 1 It can be obtained that the size of the PEDOT:PSS micelles in the PEDOT:PSS base film after treatment with n-hexane increases, indicating that n-hexane can enter the PEDOT:PSS micelles.

[0035] The sizes of PEDOT:PSS micelles of blank samples, control samples and PEDOT:PSS base films corresponding to different additives were measured by Zeta potential and nanoparticle size analyzer. The results are as follows: Figure 2 As shown, through Figure 2 It can be seen that the addition of ethanol, acetone, dimethyl sulfoxide, tetrahydrofuran, N-methylpyrrolidone and triethylamine has little effect on the size of PEDOT:PSS micelles. Cyclohexane, n-hexane and dichloromethane have a greater effect on the size of PEDOT:PSS micelles, indicating that cyclohexane, n-hexane and dichloromethane can enter the micelles well and increase the size of PEDOT:PSS micelles; ethanol does not enter the PEDOT:PSS micelles; triethylamine, tetrahydrofuran, N-methylpyrrolidone, acetone, and dimethyl sulfoxide enter the PEDOT:PSS micelles in small amounts.

[0036] (4) The surface of the control sample and the PEDOT:PSS base film corresponding to different additives were treated with 0.5 mol / L sulfuric acid. The PEDOT:PSS base film was picked up with tweezers and immersed in sulfuric acid for 3 seconds and then immersed in deionized water for 3 seconds to wash away the residual sulfuric acid. The treated PEDOT:PSS base film was dried at 150 °C and its resistance was measured using a four-probe square resistance tester. After that, it was acid-washed once and the above steps were repeated to obtain the blank sample, the control sample and the PEDOT:PSS film corresponding to different additives.

[0037] Table 1 Sheet resistance of PEDOT:PSS films with different additives in 0.5 mol / L sulfuric acid (Ω) In Table 1, the square resistance of the PEDOT:PSS base film before acid treatment corresponding to the blank sample, control sample, triethylamine, ethanol, tetrahydrofuran and acetone is greater than 3250Ω, which is greater than the range of the four-probe square resistance tester, so it is not shown. It can be seen from Table 1 that the square resistance of the PEDOT:PSS film obtained after acid treatment with triethylamine, dichloromethane, n-hexane and cyclohexane is less than 90Ω. Although the square resistance of the PEDOT:PSS base film before acid treatment with triethylamine is large, it synergizes with PSS during the acid treatment, so the square resistance after treatment is small. The square resistance of the PEDOT:PSS base film before acid treatment with N-methylpyrrolidone and dimethyl sulfoxide is small, and after sulfuric acid treatment, the obtained square resistance is further reduced.

[0038] PEDOT:PSS films obtained with different additives were used to prepare transparent paper electrodes on flexible substrates. The transmittance and conductivity of the electrodes were measured, and it was found that the conductive effect was close to that of ITO electrodes, indicating that it has the potential to replace ITO electrodes.

[0039] Example 2 The same as (1), (2), (3) and (4) of Example 1, except that the concentration of sulfuric acid in step (4) was treated under the conditions of 5 mol / L, 2 mol / L and 1 mol / L, respectively, to obtain the results of Table 2, Table 3 and Table 4, respectively.

[0040] It can be seen from Table 3, Table 3 and Table 4 that different sulfuric acid concentrations can have a good effect of reducing the square resistance. Triethylamine, dichloromethane, cyclohexane and n-hexane have better square resistance effects on PEDOT:PSS films at different sulfuric acid concentrations.

[0041] In addition, although exemplary embodiments have been described herein, the scope includes any and all embodiments based on the present application with equivalent elements, modifications, omissions, combinations (e.g., various embodiments intersecting schemes), adaptations or changes. The elements in the claims are to be interpreted broadly based on the language adopted in the claims, and are not limited to the examples described in this specification or during the practice of this application, and the examples are to be interpreted as non-exclusive. Therefore, this specification and examples are intended to be considered as examples only, and the true scope and spirit are indicated by the following claims and the full scope of their equivalents.

[0042] The above description is intended to be illustrative rather than restrictive. For example, the above examples (or one or more schemes thereof) may be used in combination with each other. For example, a person of ordinary skill in the art may use other embodiments when reading the above description. In addition, in the above-mentioned specific embodiments, various features may be grouped together to simplify the present application. This should not be interpreted as an intention that a feature of an application that does not require protection is necessary for any claim. On the contrary, the subject matter of the present application may be less than all the features of an embodiment of a particular application. Thus, the following claims are incorporated herein in the specific embodiments as examples or embodiments, wherein each claim is independently a separate embodiment, and it is considered that these embodiments may be combined with each other in various combinations or arrangements. The scope of the present invention should be determined with reference to the appended claims and the full scope of equivalent forms granted by these claims.

[0043] The above embodiments are only exemplary embodiments of the present application and are not intended to limit the present invention. The protection scope of the present invention is defined by the claims. Those skilled in the art may make various modifications or equivalent substitutions to the present invention within the essence and protection scope of the present application, and such modifications or equivalent substitutions shall also be deemed to fall within the protection scope of the present invention.

Claims

1. A method for preparing a high-conductivity PEDOT:PSS film, characterized in that: The preparation method comprises: mixing a PEDOT:PSS aqueous solution and an additive, pre-treating PEDOT:PSS micelles with the additive, wherein the additive comprises one or more of triethylamine, N-methylpyrrolidone, dichloromethane, dimethyl sulfoxide, n-hexane and cyclohexane; preparing a PEDOT:PSS basic film with the treated PEDOT:PSS aqueous solution; surface treating the PEDOT:PSS basic film with sulfuric acid; and washing the surface-treated PEDOT:PSS basic film with water to obtain a PEDOT:PSS film.

2. The preparation method according to claim 1, characterized in that: The additive includes one or more of dichloromethane, n-hexane and cyclohexane, or the additive includes triethylamine, or the additive includes N-methylpyrrolidone, dichloromethane and dimethyl sulfoxide.

3. The preparation method according to claim 1, characterized in that: The volume ratio of the PEDOT:PSS aqueous solution to the additive is 4-8:1; the solid solute in the PEDOT:PSS aqueous solution is PEDOT:PSS, and the mass fraction of the solid solute in the PEDOT:PSS aqueous solution is 1.3-1.7%.

4. The preparation method according to claim 1, characterized in that: The concentration of sulfuric acid is 0.5-5 mol / L.

5. The preparation method according to claim 1, characterized in that: The surface treatment of the PEDOT:PSS base film using sulfuric acid includes: immersing the PEDOT:PSS base film in a sulfuric acid solution.

6. The preparation method according to claim 1, characterized in that: The number of times the PEDOT:PSS base film is surface treated with sulfuric acid is one time or two times in succession.

7. The preparation method according to claim 1, characterized in that: The PEDOT:PSS micelles are treated with stirring or ultrasound during the treatment with the additives.

8. The preparation method according to claim 1, characterized in that: The time for treating PEDOT:PSS micelles with additives is 10-20 hours.

9. The preparation method according to claim 1, characterized in that: The method for preparing a PEDOT:PSS basic film from a treated PEDOT:PSS aqueous solution comprises: coating the treated PEDOT:PSS aqueous solution on a glass substrate, and drying and shaping to obtain a PEDOT:PSS basic film.

10. A PEDOT:PSS film prepared by the preparation method according to any one of claims 1 to 9.

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