Method for manufacturing ion liquid functionalized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) film with adjustable work function

Abstract

This invention discloses a method for manufacturing an ionic liquid-functionalized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) thin film with adjustable work function, comprising: a pretreatment step, in which methanol is added to a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) solution to obtain a pretreatment liquid; a film forming step, in which the pretreatment solution is coated onto a substrate using a doctor blade to obtain a first-stage thin film; a film treatment step, in which DMSO is coated onto the first-stage thin film using a doctor blade and then the DMSO is washed away to obtain a second-stage thin film; and an ionic liquid treatment step, in which an aqueous solution of an ionic liquid is coated onto the second-stage thin film using a doctor blade and then the ionic solution is washed away to obtain an ionic liquid-functionalized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) thin film, which not only has good mechanical stability, but also good conductivity and can achieve a changeable work function by using different ionic liquids.

Description

Technical Field

[0001] This invention relates to a method for manufacturing a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) film, and more particularly to a method for manufacturing an ionic liquid-functionalized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) film with adjustable work function. Background Technology

[0002] Poly(3,4-ethylenedioxythiophene) (PEDOT) is a conductive polymer that is considered a strong candidate to replace current metal oxides due to its combination of the mechanical properties of a polymer structure and the conductive properties of a conjugated structure.

[0003] The processing of PEDOT typically involves adding poly(styrenesulfonate) (PSS) as a counteracting anionic stabilizer to poly(3,4-ethylenedioxythiophene), resulting in a stable PEDOT:PSS aqueous dispersion for use in liquid processes. However, when the hydrophobic PEDOT is coated with the hydrophilic PSS, a core-shell structure is formed, resulting in a PSS-rich layer on the surface of the film, comprising approximately 10% of the total thickness, leading to reduced conductivity.

[0004] There have been many methods for removing poly(styrene sulfonic acid) from the molecular surface of poly(3,4-ethylenedioxythiophene), including treatment with organic solvents, acid treatment, and ionic liquid treatment.

[0005] Previous studies have shown that adding polar organic solvents such as dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), and tetrahydrofuran (THF) to aqueous solutions of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) can increase conductivity, and the cohesive strength of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) can also be changed depending on the type of polar solution added.

[0006] Further research indicates that post-treatment of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) with DMSO or EG (ethylene glycol) significantly enhances conductivity. Conversely, treatment with common organic solvents such as ethanol, isopropanol (IPA), acetonitrile (ACN), and THF does not significantly alter conductivity. However, when poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) films are treated simultaneously with these organic solvents and water, conductivity is significantly enhanced. This is presumably because this treatment weakens the electrostatic attraction between the poly(3,4-ethylenedioxythiophene) and poly(styrenesulfonic acid) chains, separating the poly(styrenesulfonic acid) shell. This change causes a conformational rearrangement of poly(3,4-ethylenedioxythiophene).

[0007] Previous studies have also found that immersing poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) films in strong acids can enhance their conductivity. When poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) films are treated with strong acids capable of self-proton decomposition, the strong acid dissociates into positively charged cations and negatively charged anions. These two types of ions can stabilize the separation state of the positively charged poly(3,4-ethylenedioxythiophene) and negatively charged poly(styrenesulfonic acid) chains, reducing the electrostatic interaction between the poly(3,4-ethylenedioxythiophene) and poly(styrenesulfonic acid) chains and thus reducing phase separation. This alters the molecular structure of poly(3,4-ethylenedioxythiophene) and significantly improves the conductivity of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid). However, strong acid treatment poses risks to human health and the environment, hindering commercial applications.

[0008] In recent years, there have also been studies on using ionic liquids to treat poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid), separating poly(3,4-ethylenedioxythiophene) and poly(styrenesulfonic acid) through ion exchange. Because ionic liquids have the characteristics of both organic and inorganic salts, such as good chemical stability, low flammability, low vapor pressure and low volatility, they are suitable for processing.

[0009] However, when ionic liquids are mixed with poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid), gelation occurs. Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) liquids treated with ionic liquids will produce particle or solution aggregation during coating, which is a huge obstacle to the coating and film formation process. Summary of the Invention

[0010] Therefore, the object of the present invention is to provide a method for manufacturing an ionic liquid-functionalized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) film with an adjustable work function, which can avoid the gelation phenomenon that occurs when poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) is treated with ionic liquid, and manufacture an ionic liquid-functionalized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) film with an adjustable work function and high conductivity.

[0011] The present invention addresses the problems of existing technologies by providing a method for manufacturing an ionic liquid-functionalized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) thin film with adjustable work function. The method includes: a pretreatment step, in which methanol is added to a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) solution to obtain a pretreatment liquid; a film-forming step, in which the pretreatment solution is coated onto a substrate using a doctor blade and subjected to annealing treatment to obtain a first-stage thin film; and a film treatment step, in which DMSO is coated onto the first-stage thin film using a doctor blade to obtain a DMSO-treated first-stage thin film. The first-stage film, after being treated with DMSO, is annealed and then rinsed with methanol to remove the DMSO, resulting in a second-stage film. The second-stage film undergoes an ionic liquid treatment step, in which deionized water is added to an ionic liquid, and the mixture is ultrasonically vibrated to obtain an ionic liquid aqueous solution. This aqueous solution is then coated onto the second-stage film using a doctor blade to obtain an ionic liquid-treated film. The ionic liquid-treated film is annealed and then rinsed with deionized water to remove the ionic liquid, resulting in an ionic liquid-functionalized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) film.

[0012] In one embodiment of the present invention, a method for manufacturing an ionic liquid-functionalized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) film is provided. In the pretreatment step, the pretreatment liquid is composed of 80 vol% poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) solution and 20 vol% methanol.

[0013] In one embodiment of the present invention, a method for manufacturing an ionic liquid-functionalized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) film is provided, wherein the annealing treatment is performed at 110°C.

[0014] In one embodiment of the present invention, a method for manufacturing an ionic liquid-functionalized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) film is provided, wherein the blade coating process is performed under the conditions of a gap of 0.2 mm, a blade angle of 45°, and a blade speed of 5 cm / min.

[0015] In one embodiment of the present invention, a method for manufacturing an ionic liquid-functionalized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) thin film is provided, wherein the substrate in the film-forming step is a glass substrate or a polyethylene phthalate substrate.

[0016] In one embodiment of the present invention, a method for manufacturing an ionic liquid-functionalized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) film is provided, wherein the annealing treatment time in the film-forming step is 5 minutes.

[0017] In one embodiment of the present invention, a method for manufacturing an ionic liquid-functionalized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) film is provided, wherein the annealing treatment time in the film processing step is 10 minutes.

[0018] In one embodiment of the present invention, a method for manufacturing an ionic liquid-functionalized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) film is provided, wherein the annealing treatment time in the ionic liquid processing step is 10 minutes.

[0019] The technical means employed in the manufacturing method of the ionic liquid-functionalized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) film of the present invention can avoid the gelation phenomenon that occurs when pretreating poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) with ionic liquid, and obtain a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) film with ionic liquid surface functionalization. Moreover, the ionic liquid-functionalized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) film has good conductivity and can achieve a changeable work function by using different ionic liquids. Attached Figure Description

[0020] Figure 1 A flowchart illustrating a method for manufacturing an ionic liquid-functionalized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) film according to an embodiment of the present invention.

[0021] Figure label:

[0022] S1: Pre-processing steps

[0023] S2: Film Forming Steps

[0024] S3: Membrane treatment steps

[0025] S4: Ionic liquid treatment steps. Detailed Implementation

[0026] The following is based on the appendix Figure 1 This description illustrates one embodiment of the present invention. This description is not intended to limit the embodiments of the present invention, but rather to provide one possible example of the invention.

[0027] like Figure 1 As shown, a method for manufacturing an ionic liquid-functionalized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) thin film according to an embodiment of the present invention includes: a pretreatment step S1, a film forming step S2, a film treatment step S3, and an ionic liquid treatment step S4.

[0028] like Figure 1 As shown in the pretreatment step S1, methanol is added to a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) solution, and the mixture is treated with ultrasonic vibration to obtain a pretreatment liquid.

[0029] like Figure 1 As shown in film-forming step S2, the pretreatment solution is coated onto the substrate with a doctor blade, and the substrate is then annealed to obtain the first-stage film.

[0030] In the film-forming step S2, the inventors of this invention added methanol to the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) solution to accelerate the drying of the film and weaken the interaction between poly(3,4-ethylenedioxythiophene) and poly(styrenesulfonic acid), thereby improving the ion exchange effect described later.

[0031] like Figure 1 As shown in the membrane treatment step S3, DMSO is coated onto the first-stage film with a doctor blade to obtain the first-stage film after DMSO treatment. The first-stage film after DMSO treatment is then annealed and the surface is washed with methanol to remove DMSO, thus obtaining the second-stage film.

[0032] In the membrane treatment step S3, a portion of the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) / methanol membrane is removed by treating it with DMSO, and the electrostatic interaction between PEDOT and PSS is weakened by the masking effect of DMSO to improve the ion exchange effect described later.

[0033] like Figure 1 As shown in step S4 of the ionic liquid treatment, deionized water is added to the ionic liquid and then ultrasonically oscillated to obtain an ionic liquid aqueous solution. The ionic liquid aqueous solution is then coated onto the second-stage film with a doctor blade to obtain an ionic liquid treated film. The ionic liquid treated film is then annealed and rinsed with deionized water to remove the ionic liquid, resulting in an ionic liquid functionalized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) film.

[0034] In the ionic liquid treatment step S4, treating the second-stage film with an ionic liquid can replace poly(3,4-ethylenedioxythiophene) and poly(styrene sulfonic acid) through ion exchange between the anions and cations of the ionic liquid, and transform the poly(3,4-ethylenedioxythiophene) chain from its coiled benzoyl structure to a quinoid structure to improve charge conductivity. The surface layer of ionic liquid and poly(styrene sulfonic acid) can then be washed away with deionized water to obtain an ionic liquid-functionalized poly(3,4-ethylenedioxythiophene):poly(styrene sulfonic acid) film with good conductivity.

[0035] Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonic acid) films manufactured using the doctor blade coating method typically form a poly(styrene sulfonic acid)-rich layer of about 12 mm thickness on the surface of the film. Therefore, ionic liquids can effectively react with poly(styrene sulfonic acid), and deionized water can efficiently remove poly(styrene sulfonic acid) from the film.

[0036] According to an embodiment of the present invention, a method for manufacturing an ionic liquid-functionalized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) film is provided, wherein in the pretreatment step, the pretreatment liquid is composed of 80 vol% poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) solution and 20 vol% methanol.

[0037] This composition achieves the desired effect of accelerated drying, thereby improving the uniformity of poly(3,4-ethylenedioxythiophene) in the first-stage film.

[0038] According to an embodiment of the present invention, a method for manufacturing an ionic liquid-functionalized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) film, wherein the annealing treatment is performed at 110°C.

[0039] By setting the temperature in this way, a suitable temperature can be provided to promote solvent drying without affecting the film formation process.

[0040] According to an embodiment of the present invention, a method for manufacturing an ionic liquid-functionalized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) film is used, wherein the blade coating process is performed under conditions of a gap of 0.2 mm, a blade angle of 45°, and a blade speed of 5 cm / min.

[0041] Based on the above conditions, a high-quality film can be formed by the blade coating method.

[0042] According to an embodiment of the present invention, a method for manufacturing an ionic liquid-functionalized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) thin film is provided, wherein in the film-forming step, the substrate is a glass substrate or a polyethylene phthalate substrate.

[0043] According to an embodiment of the present invention, in a method for manufacturing an ionic liquid-functionalized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) film, the annealing treatment time in the film-forming step is 5 minutes.

[0044] According to an embodiment of the present invention, in a method for manufacturing an ionic liquid-functionalized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) film, the annealing treatment time in the film processing step is 10 minutes.

[0045] According to an embodiment of the present invention, in a method for manufacturing an ionic liquid-functionalized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) film, the annealing time in the ionic liquid processing step is 10 minutes.

[0046] By setting the annealing time in this way, a suitable temperature can be provided to promote solvent drying without affecting the film formation process.

[0047] In the embodiments of the present invention, the ionic liquid in the ionic liquid treatment step is 1-ethyl-3-methylimidazolium ethyl sulfate, 1-ethyl-3-methylimidazolium dicyanamide salt, or 1-ethyl-3-methylimidazolium thiocyanate.

[0048] By using ionic liquids of 1-ethyl-3-methylimidazolium ethyl sulfate, 1-ethyl-3-methylimidazolium dicyanamide, or 1-ethyl-3-methylimidazolium thiocyanate to treat the second-stage film, the work function of the film can be adjusted to be increased or decreased.

[0049] The work function of the thin film can be obtained by scanning with Kelvin probe force microscopy (KPFM) and ultraviolet photoelectron spectroscopy (UPS). In the embodiments of the present invention, the untreated thin film and the thin film treated with three ionic liquids were scanned respectively, and the results are shown in Table 1.

[0050] Table 1: Scanning results of untreated films and films treated with the three ionic liquids

[0051]

[0052]

[0053] As shown in Table 1, compared with the untreated poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) film, different ionic liquid treatments can significantly change the surface work function of the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) film. This change may be caused by the ion exchange interaction between the ionic liquid and poly(3,4-ethylenedioxythiophene). The difference in the interaction force between the anion and poly(3,4-ethylenedioxythiophene) and the difference in the dipole moment and electron push-pull ability of the anion leads to a change in the surface charge dissipation ability of poly(3,4-ethylenedioxythiophene), thus resulting in a difference in the work function.

[0054] According to the technical method of the present invention, the gelation phenomenon that occurs when treating poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) with ionic liquid can be avoided, resulting in an ionic liquid-functionalized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) film with ionic liquid surface functionalization. Due to its good mechanical stability and good conductivity, it can provide electrodes with large surface area for applications such as triboelectric nanogenerators. Triboelectric nanogenerators provide electrostatically polarized charges on the surface of the electrodes, which can be generated by friction or contact. By using different ionic liquids in the manufacturing method of the present invention, the work function of the ionic liquid-functionalized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) film can be changed, maximizing the difference in work function between the electrode layer and the triboelectric dielectric layer, thereby improving the output performance of the triboelectric nanogenerator.

[0055] The above description and illustration are merely illustrative of preferred embodiments of the present invention. Those skilled in the art can make other modifications based on the following defined claims and the above description, but these modifications should still be within the spirit of the invention and the scope of the invention.

Claims

1. A method for manufacturing an ionic liquid-functionalized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) thin film with adjustable work function, characterized in that, Include: The pretreatment step involves adding methanol to a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) solution to obtain a pretreatment liquid. In the film-forming step, the pretreatment liquid is coated onto the substrate with a doctor blade and then annealed to obtain the first-stage film. The membrane treatment steps involve coating DMSO onto the first-stage film using a doctor blade to obtain a DMSO-treated first-stage film, annealing the DMSO-treated first-stage film, and then washing the surface with methanol to remove the DMSO, resulting in a second-stage film; and The ionic liquid treatment process involves adding deionized water to the ionic liquid and then subjecting it to ultrasonic oscillation to obtain an ionic liquid aqueous solution. The ionic liquid aqueous solution is then coated onto the second-stage film using a doctor blade to obtain an ionic liquid-treated film. The ionic liquid-treated film is then annealed and rinsed with deionized water to remove the ionic liquid, resulting in an ionic liquid-functionalized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) film.

2. The method for manufacturing an ionic liquid-functionalized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) thin film as described in claim 1, characterized in that, In the pretreatment step, the pretreatment liquid is composed of 80 vol% poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) solution and 20 vol% methanol.

3. The method for manufacturing an ionic liquid-functionalized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) thin film as described in claim 1, characterized in that, The annealing process is performed at 110°C.

4. The method for manufacturing an ionic liquid-functionalized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) thin film as described in claim 1, characterized in that, The blade coating process is carried out under the conditions of a gap of 0.2 mm, a blade angle of 45°, and a blade speed of 5 cm / min.

5. The method for manufacturing an ionic liquid-functionalized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) thin film as described in claim 1, characterized in that, In the film-forming step, the substrate is a glass substrate or a polyethylene phthalate substrate.

6. The method for manufacturing an ionic liquid-functionalized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) thin film as described in claim 1, characterized in that, In the film-forming step, the annealing time is 5 minutes.

7. The method for manufacturing an ionic liquid-functionalized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) film as described in claim 1, characterized in that, In the membrane treatment step, the annealing time is 10 minutes.

8. The method for manufacturing an ionic liquid-functionalized poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) thin film as described in claim 1, characterized in that, In the ionic liquid treatment step, the annealing treatment time is 10 minutes.

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