Preparation method of PEDOT:PSS composite copper grid flexible transparent conductive film

Abstract

The present invention discloses a method for preparing a PEDOT:PSS composite copper grid flexible transparent conductive film, comprising the following steps: S1, cleaning a PET substrate; S2, adjusting a PEDOT:PSS solution; S3, spin-coating PEDOT:PSS; S4, annealing: removing the spin-coated PEDOT:PSS seed layer and annealing it in a vacuum drying oven to obtain a PEDOT:PSS film; S5, pre-sputtering a target material; S6, sputtering a Cu film on the PEDOT:PSS / PET substrate; and S7, preparing the copper grid composite conductive film. The present invention uses PEDOT:PSS / PET instead of PET as a substrate and uses PEDOT:PSS as a seed layer, which not only provides a good wetting effect for the growth of the Cu layer, but also leverages the inherent conductivity of PEDOT:PSS to enable the Cu layer and PEDOT:PSS layer to composite and exhibit superior optoelectronic properties. The entire process is simple, requiring no complex operations, and features high laser direct writing speed, high pattern flexibility, and the ability to freely adjust pattern parameters without being restricted by a mask, resulting in low production costs.

Description

Technical Field

[0001] The present invention belongs to the technical field of transparent conductive films, and in particular relates to a method for preparing a PEDOT:PSS composite copper grid flexible transparent conductive film. Background Art

[0002] As smart electronics, photovoltaics, and related new energy products move toward flexibility and transparency, flexible transparent conductive films are also developing, driven by growing market demand. Currently, traditional ITO transparent conductive films still dominate the market. However, the scarcity of indium makes their production cost high. Furthermore, ITO's inherent brittleness makes it prone to cracking, leading to film damage and reduced conductivity. These properties hinder ITO's widespread adoption in the future. Consequently, since the last century, alternatives to ITO have been continuously developed. Currently, silver nanowires, metal meshes, and composite conductive films are the most promising. Metal mesh flexible transparent conductive films are transparent conductive metal mesh films with periodic or random patterns on flexible substrates. The metal mesh's size, line width, and pattern can be adjusted to tailor optoelectronic properties according to application requirements. As a next-generation transparent conductive film, metal meshes offer excellent combined optoelectronic performance and excellent flexibility, making them a promising new generation of flexible transparent conductive films.

[0003] Methods for manufacturing metal meshes include photolithography, nanoimprint lithography, templated electrodeposition and imprint transfer (TEIT) processes, and laser direct writing. Photolithography and nanoimprint lithography can achieve high-precision control of the mesh pattern, but the production of high-performance metal meshes usually requires the prefabrication of high-precision templates, and the overall process is complex and costly. Templated electrodeposition and imprint transfer (TEIT) processes can produce high-performance metal meshes with remarkable smoothness, but the TEIT process often involves complex multiple transfer and peeling procedures, which can lead to low cost-effectiveness and poor repeatability in large-scale production.

[0004] The conductivity of the metal mesh transparent conductive film is mainly determined by the metal conductive layer. For the CuMesh conductive film, when PET is used as the substrate, the Cu film mainly grows in an island shape, so the photoelectric performance of the copper mesh prepared is poor.

[0005] Therefore, in order to solve the above technical problems, it is necessary to provide a method for preparing a PEDOT:PSS composite copper grid flexible transparent conductive film.

[0006] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the Invention

[0007] The object of the present invention is to provide a method for preparing a PEDOT:PSS composite copper grid flexible transparent conductive film, which can solve the problems raised in the background technology.

[0008] In order to achieve the above object, a specific embodiment of the present invention provides the following technical solutions:

[0009] A method for preparing a PEDOT:PSS composite copper grid flexible transparent conductive film comprises the following steps:

[0010] S1. PET substrate cleaning: The cut PET substrate is ultrasonically treated with acetone and anhydrous ethanol to remove organic matter and other impurities on the substrate surface. The PET substrate is transferred to deionized water, ultrasonicated again, and then dried. The dried PET substrate is stored;

[0011] S2, PEDOT:PSS solution adjustment: adding the first enhancing liquid to the PEDOT:PSS stock solution to improve the conductivity of the PEDOT:PSS film; using the second enhancing liquid to improve the interface contact between the PEDOT:PSS and the PET flexible substrate;

[0012] S3. Spin coating PEDOT:PSS: Place a drop of anhydrous ethanol on the cleaned glass, then slowly cover the PET substrate with the droplet until the liquid adsorption film substrate is spin-coated;

[0013] S4, annealing: taking out the spin-coated PEDOT:PSS seed layer and placing it in a vacuum drying oven for annealing to obtain a PEDOT:PSS film;

[0014] S5. Pre-sputtering of target material: Turn on the power of water cooling machine, close the gas regulating valve and the air release valve, turn on the vacuum pump switch, make the vacuum degree drop below 2Pa, turn the knob gas regulating valve to stabilize to about 4Pa, and keep it for 5 minutes to make the cavity filled with argon gas; turn on the DC power supply for sputtering;

[0015] S6. Sputtering a Cu film on a PEDOT:PSS / PET substrate: After pre-sputtering, move the sample to the sputtering position, adjust the spacing, set the sputtering power and sputtering time, and perform sputtering. After stopping sputtering, close the gas regulating valve and the vacuum pump handle in sequence, rotate the vent valve counterclockwise, and then remove the sample. After sputtering, transfer the sample to a drying oven for drying.

[0016] S7. Preparation of copper mesh composite conductive film: Import the mesh pattern to be directly written into the nanosecond pulse laser, set the parameters, place the film, and adjust the focal length, then start direct writing until the CuMesh / PEDOT:PSS composite transparent conductive film is obtained.

[0017] In one or more embodiments of the present invention, the first synergistic liquid includes ethylene glycol, and the ethylene glycol used in step S2 is added to the PEDOT:PSS stock solution in a volume fraction of 5%.

[0018] In one or more embodiments of the present invention, the second enhancement liquid includes isopropyl alcohol.

[0019] In one or more embodiments of the present invention, the second synergistic liquid in step S2 is diluted with isopropyl alcohol as a diluent, and the dilution ratio is 2:1.

[0020] In one or more embodiments of the present invention, the specific steps of S3 include:

[0021] S31, placing the glass covered with the substrate in the center of the spin coater suction cup and closing the cover;

[0022] S32. Adjust the spin coater to a spin coating speed of 700-900 rpm and a spin coating time of 30-75 s, and start the spin coater to gradually drip the PEDOT:PSS solution onto the PET substrate from the upper dripping port.

[0023] In one or more embodiments of the present invention, in step S4, the film is placed in a vacuum drying oven and annealed at a temperature of 120-180° C. for 8-20 min to obtain a PEDOT:PSS film.

[0024] In one or more embodiments of the present invention, in the step S5, the sputtering power is 300-500 W, and the sputtering time is 1.5-3.5 min.

[0025] In one or more embodiments of the present invention, in the step S6, during sputtering, the distance between the target and the substrate is adjusted to 9-11 cm, the sputtering power is 80-120 W, and the sputtering time is 1-5 min.

[0026] In one or more embodiments of the present invention, in the step S7, the laser energy density is 1.94-3.88 J / cm2, the scanning speed is 200-600 mm / s, and the direct writing is completed to obtain a CuMesh / PEDOT:PSS composite transparent conductive film.

[0027] Compared with the prior art, the method for preparing a PEDOT:PSS composite copper grid flexible transparent conductive film of the present invention has the following advantages:

[0028] 1) This application uses PEDOT:PSS / PET instead of PET as the substrate, and uses PEDOT:PSS as the seed layer, which not only provides a good wetting effect for the growth of the Cu layer, but also can make use of the conductive properties of PEDOT:PSS itself to make the Cu layer and PEDOT:PSS layer composite to exert better photoelectric performance.

[0029] 2) The entire process of this application is simple, does not require complicated operations, has a fast laser direct writing speed, is highly flexible in patterning, can adjust pattern parameters at will without being restricted by masks, and has a low preparation cost.

[0030] 3) This application uses spin coating to prepare thin films, which is simple and easy to control parameters. During spin coating, centrifugal force evenly distributes the solution on the substrate, forming a uniform, smooth film. It can be mass-produced with high reproducibility.

[0031] 4) The magnetron sputtering film structure used in this application is more compact and has a strong bonding force with the substrate, making it less likely to crack or peel off. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0033] Figure 1 This is a preparation flow chart of a method for preparing a PEDOT:PSS composite copper grid flexible transparent conductive film in one embodiment of the present invention; DETAILED DESCRIPTION

[0034] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0035] like Figure 1 As shown, a method for preparing a PEDOT:PSS composite copper grid flexible transparent conductive film in one embodiment of the present invention includes the following steps:

[0036] Prepare the following materials: PET film (thickness 50 μm), PEDOT:PSS (OE-000), ethylene glycol, isopropyl alcohol, anhydrous ethanol, acetone, deionized water, a Cu target with a diameter of 50 mm, and sputtering gas argon.

[0037] S1. PET substrate cleaning: Ultrasonicate the cut PET substrate in acetone for 10 minutes. Then, ultrasonicate for another 10 minutes in ethanol to remove organic matter and other impurities on the substrate surface. After the ultrasonication in ethanol is complete, transfer the PET substrate to deionized water and continue ultrasonicating for 5 minutes. Finally, transfer the PET substrate to a forced air drying oven for drying. After drying, place the PET substrate in a glass desiccator for storage.

[0038] S2. PEDOT:PSS solution adjustment: adding a first enhancing liquid to the PEDOT:PSS stock solution to improve the conductivity of the PEDOT:PSS film; using a second enhancing liquid to improve the interface contact between the PEDOT:PSS and the PET flexible substrate, thereby increasing adhesion and ensuring the reliability and stability of the film;

[0039] The first synergistic liquid includes ethylene glycol, and the ethylene glycol used in step S2 is added to the PEDOT:PSS stock solution in a volume fraction of 5%.

[0040] The second synergistic liquid includes isopropyl alcohol. The second synergistic liquid in step S2 is diluted with isopropyl alcohol as a diluent at a dilution ratio of 2:1.

[0041] Specifically, the conductivity of the original PEDOT:PSS solution is poor, so the PEDOT:PSS solution was adjusted. Through experiments, the optimal ethylene glycol addition amount of 5vol% was found to significantly improve the conductivity of PEDOT:PSS; as well as the optimal diluent and dilution ratio, namely PEDOT:PSS original solution: isopropyl alcohol = 2:1, to improve the interface contact with the PET flexible substrate and increase adhesion.

[0042] S3. Spin coating PEDOT:PSS: Place a drop of anhydrous ethanol on the cleaned glass, then slowly cover the PET substrate with the drop along one side. Use the surface tension between the liquid and the film to tightly adsorb the film substrate before spin coating.

[0043] S31, placing the glass covered with the substrate in the center of the spin coater suction cup and closing the device cover;

[0044] S32. Select a spin coating process, adjust the spin coater to a spin coating speed of 700-900 rpm and a spin coating time of 30-75 s, and start the process to gradually drip the PEDOT:PSS solution onto the PET substrate from the upper dripping port.

[0045] Preferably, the spin coating speed is 800 rpm and the spin coating time is 45 seconds. The spin coater is started and the PEDOT:PSS solution is gradually dripped onto the PET substrate from the upper dripping port. Spin coating is a key step in achieving uniform film thickness. The selection of a spin coating speed of 800 rpm and a spin coating time of 45 seconds ensures uniform coverage of the PEDOT:PSS on the PET substrate, resulting in a uniform and high-performance PEDOT:PSS film.

[0046] S4, annealing: taking out the spin-coated PEDOT:PSS seed layer and placing it in a vacuum drying oven for annealing to obtain a PEDOT:PSS film;

[0047] Further, the film is placed in a vacuum drying oven, the temperature is set at 120-180° C. for annealing, and the annealing time is set at 8-20 min to obtain a PEDOT:PSS film.

[0048] Preferably, the annealing process is performed in a vacuum drying oven at 150°C for 10 minutes. PEDOT:PSS films typically require annealing after spin coating to improve their conductivity and stability. Annealing at 155°C for 15 minutes yields excellent PEDOT:PSS substrate performance. This is because the higher annealing temperature improves the crystallinity and intermolecular interactions of the PEDOT molecules, enhancing the film's electron transport properties.

[0049] S5. Pre-sputtering of target material: Turn on the power of water cooler, close the gas regulating valve and the vent valve, turn on the vacuum pump switch, make the vacuum degree drop below 2Pa, turn the knob gas regulating valve to stabilize to about 4Pa, and keep it for 5 minutes to fill the cavity with argon gas; turn on the DC power supply for sputtering, the sputtering power is 300-500W, and the sputtering time is 1.5-3.5min;

[0050] Preferably, the sputtering power is 400 W and the sputtering time is 3 min.

[0051] S6. Sputtering Cu film on PEDOT:PSS / PET substrate: After pre-sputtering, move the sample to the sputtering position for sputtering. Adjust the distance between the target and the substrate to 9-11 cm, the sputtering power to 80-120 W, and the sputtering time to 1-5 min. The sputtering operation steps are similar to those in S5. After the sputtering work stops, close the gas regulating valve and the vacuum pump handle in sequence, rotate the exhaust valve counterclockwise, and then take out the sample. After sputtering, transfer it to a drying oven for drying.

[0052] Preferably, the distance between the target and the substrate is 10 cm, the sputtering power is 100 W, and the sputtering time is 2 min.

[0053] S7. Preparation of copper mesh composite conductive film: Import the CAD-drawn grid pattern (hexagonal shape, 300μm spacing, 30μm line width) into the nanosecond pulse laser. Use the laser's built-in software tools to fill the grid and set the parameters. Then save the grid pattern as a vlf file and open it in the working software. Place the film to be directly written on a two-axis workbench, adjust the laser's focal length, and begin direct writing until a CuMesh / PEDOT:PSS composite transparent conductive film is obtained.

[0054] Furthermore, during direct writing, the laser energy density of the nanosecond pulse laser was adjusted to 1.94-3.88 J / cm2, and the scanning speed was 200-600 mm / s. After the direct writing was completed, a CuMesh / PEDOT:PSS composite transparent conductive film was obtained.

[0055] Preferably, the laser energy density is 2.91 J / cm² and the scanning speed is 400 mm / s. Upon completion of the direct writing process, a CuMesh / PEDOT:PSS composite transparent conductive film is obtained. The FoM index of the CuMesh / PEDOT:PSS composite transparent conductive film prepared at a laser energy density of 2.91 J / cm² and a scanning speed of 400 mm / s reached a maximum of 414.6. At this point, the composite film achieved a transmittance of 85.8% and a sheet resistance of only 5.7 Ω / sq.

[0056] In this application, PEDOT:PSS / PET replaces PET as the substrate, and PEDOT:PSS is used as the seed layer, which not only provides a good wetting effect for the growth of the Cu layer, but also can make use of the conductive properties of PEDOT:PSS itself to make the Cu layer and PEDOT:PSS layer composite to exert better photoelectric performance.

[0057] The entire process of this application is simple, does not require complicated operations, has a high laser direct writing speed, high pattern flexibility, and can adjust pattern parameters at will without being restricted by masks. The preparation cost is low.

[0058] The spin coating method used in this application is relatively simple and easy to control parameters. During spin coating, centrifugal force evenly distributes the solution on the substrate, forming a uniform and smooth film. This uniformity is difficult to achieve with other methods, especially at low thicknesses.

[0059] The magnetron sputtering film structure used in this application is denser and has a strong bonding force with the substrate, making it less likely to crack or peel off.

[0060] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0061] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A method for preparing a PEDOT:PSS composite copper grid flexible transparent conductive film, characterized in that: The steps include: S1. PET substrate cleaning: The cut PET substrate is ultrasonically treated with acetone and anhydrous ethanol to remove organic matter and other impurities on the substrate surface. The PET substrate is transferred to deionized water, ultrasonicated again, and then dried. The dried PET substrate is stored; S2, PEDOT:PSS solution adjustment: adding the first enhancing liquid to the PEDOT:PSS stock solution to improve the conductivity of the PEDOT:PSS film; using the second enhancing liquid to improve the interface contact between the PEDOT:PSS and the PET flexible substrate; The first synergistic liquid includes ethylene glycol, which is added to the PEDOT:PSS stock solution at a volume fraction of 5%. The second synergistic liquid includes isopropyl alcohol, which is diluted with isopropyl alcohol at a dilution ratio of 2:

1. S3. Spin coating PEDOT:PSS: Place a drop of anhydrous ethanol on the cleaned glass, then slowly cover the PET substrate with the droplet until the liquid adsorption film substrate is spin-coated; S31, placing the glass covered with the substrate in the center of the spin coater suction cup and closing the cover; S32, adjust the spin coater to a spin coating speed of 800 rpm and a spin coating time of 45 s, and start the process to gradually drip the PEDOT:PSS solution onto the PET substrate from the upper dripping port; S4, annealing: take out the spin-coated PEDOT:PSS seed layer, place it in a vacuum drying oven, set the temperature to 150°C for annealing, and set the annealing time to 10 minutes to obtain a PEDOT:PSS film; S5. Pre-sputtering of target material: Turn on the power of water cooling machine, close the gas regulating valve and the air release valve, turn on the vacuum pump switch, make the vacuum degree drop below 2Pa, turn the knob gas regulating valve to stabilize to about 4Pa, and keep it for 5 minutes to make the cavity filled with argon gas, turn on the DC power supply for pre-sputtering; S6. Sputtering a Cu film on a PEDOT:PSS / PET substrate: After pre-sputtering, move the sample to the sputtering position, adjust the spacing, set the sputtering power and sputtering time, and perform sputtering. After stopping sputtering, close the gas regulating valve and the vacuum pump handle in sequence, rotate the vent valve counterclockwise, and then remove the sample. After sputtering, transfer to a drying oven for drying; S7. Preparation of copper mesh composite conductive film: Import the mesh pattern to be directly written into the nanosecond pulse laser, set the parameters, place the film and adjust the focal length, and then start direct writing until the CuMesh / PEDOT:PSS composite transparent conductive film is obtained.

2. The method for preparing a PEDOT:PSS composite copper grid flexible transparent conductive film according to claim 1, characterized in that: In the step S5, the sputtering power is 300-500 W, and the sputtering time is 1.5-3.5 min.

3. The method for preparing a PEDOT:PSS composite copper grid flexible transparent conductive film according to claim 2, characterized in that: In the step S6, during sputtering, the distance between the target and the substrate is adjusted to 9-11 cm, the sputtering power is 80-120 W, and the sputtering time is 1-5 min.

4. The method for preparing a PEDOT:PSS composite copper grid flexible transparent conductive film according to claim 3, characterized in that: In the step S7, the laser energy density is 1.94-3.88 J / cm2, the scanning speed is 200-600 mm / s, and the direct writing is completed to obtain a CuMesh / PEDOT:PSS composite transparent conductive film.

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