PEDOT: PSS electrode curved surface film forming method based on asymmetric spin-coating method

Abstract

The invention discloses a curved surface film forming method of a PEDOT: PSS electrode based on an asymmetric spin-coating method. The curved surface film forming method comprises the following steps: S1, obtaining a clean substrate; s2, a PEDOT: PSS solution is measured, and the measured PEDOT: PSS solution is dropped on the inner wall of the substrate; s3, enabling the PEDOT: PSS solution to be completely coated in the inner wall of the substrate; s4, performing centrifugal spin-coating on the substrate through a centrifugal machine; s5, after centrifugal spin coating is completed, the substrate is taken out through tweezers, and the film forming condition is observed; s6, the substrate is placed on a constant-temperature heating platform, and the liquid is evaporated to dryness so that the film can be formed; and S7, testing the test index of the film forming result on the inner wall of the substrate after film coating is completed. According to the curved surface film forming method of the PEDOT: PSS electrode based on the asymmetric spin-coating method, the conductive problem of the PEDOT: PSS electrode can be improved, a device is protected, meanwhile, the device has the anti-static performance and the EMI shielding performance, and therefore the stability of the device is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of conductive polymer functional materials, and in particular relates to a curved surface film forming method of a PEDOT:PSS electrode based on an asymmetric spin coating method. Background Art

[0002] With the development of industry, more and more types of flexible electronic devices are appearing in our lives, and the surface of electronic devices is often covered with protective surface coatings. However, since the devices coated with ordinary coatings have poor conductivity and single functions, the devices have poor functions in terms of electrical signal transmission. Among them, taking the film formation on curved substrates as an example, the film preparation on curved substrates is quite different from that on flat surfaces. It is necessary to pay attention to stress concentration and other issues while ensuring that the film covers the entire surface, and then make corresponding improvements to the film formation method for specific curved surfaces, so as to form a uniform and smooth conductive film.

[0003] The current film forming methods are mainly: physical vapor deposition, chemical vapor deposition, spray thermal decomposition, inkjet printing, dipping, spin coating, etc. For physical vapor deposition, it is mainly suitable for the deposition of solid materials on the surface of the substrate. During the whole process, process conditions such as deposition rate, temperature, air pressure, and vacuum will affect the film forming effect. Chemical vapor deposition mainly uses chemical reactions at high temperatures to generate solid products and deposit them on the surface of the substrate to form a thin film. During the whole experiment, its high temperature, air pressure, and inert gas environment need to be strictly controlled to ensure the performance of the film. Spray thermal decomposition mainly uses an atomizing device to atomize the solution, and then sprays and deposits it on the surface of the substrate to crystallize it. After the crystallization is completed, annealing is required to form a thin film. Compared with the above two methods, this experiment has relatively low environmental requirements, but it has high requirements for the nozzle flow rate. If the speed is too small, it is not easy to deposit, and if the speed is too large, the defects on the surface of the substrate will be destroyed. In addition, the substrate temperature also has a great influence on the film forming effect. Inkjet printing method, it is necessary to control the voltage pulse to control the stability of inkjet printing, and it is also necessary to control the injection speed, frequency, ambient humidity, etc. to increase the uniformity of the film. The dip coating method is simple to operate, but the solution waste is serious, and it is difficult to control the uniformity of the film and the film thickness, and the film forming effect is not good. Spin coating, as a common film forming method, has the advantages of low cost and easy operation that the above methods do not have, and its film forming effect is good. However, since it is mainly suitable for planar substrate film formation, it needs to be improved to realize asymmetric spin coating operation.

[0004] The above methods all have their specific application scenarios and scope of application, but they are not applicable to the curved surface film formation operation of water-soluble PEDOT:PSS. In addition, for the inside of the already formed curved surface substrate, it has been found through practice that the film formed by the dipping method is uneven and the film thickness cannot be accurately controlled; the spray thermal decomposition method of film formation is difficult to achieve due to the high requirements for controlling the nozzle distance, inkjet speed, and substrate temperature. Summary of the invention

[0005] The purpose of the present invention is to provide a curved surface film forming method of a PEDOT:PSS electrode based on an asymmetric spin coating method, which can improve its conductivity problem, protect the device, and enable the device to have anti-static performance and EMI shielding performance, thereby improving the stability of the device.

[0006] To achieve the above object, the present invention provides a method for forming a curved surface film of a PEDOT:PSS electrode based on an asymmetric spin coating method, comprising the following steps:

[0007] S1. Select a substrate and clean the substrate to obtain a clean substrate;

[0008] S2. Use a rubber-tipped dropper to measure 0.5 ml to 2 ml of PEDOT:PSS solution, and drop the measured PEDOT:PSS solution onto the inner wall of the substrate;

[0009] S3, slowly rotating the substrate to allow the PEDOT:PSS solution to be completely coated on the inner wall of the substrate;

[0010] S4, using a buffer material to set the substrate and the centrifuge tube in the centrifuge, and centrifugally spin-coating the substrate through the centrifuge;

[0011] S5. After the centrifugal spin coating is completed, the substrate is taken out with tweezers, and the external buffer material is removed to observe the film formation;

[0012] S6. When the PEDOT:PSS in the substrate is observed to be attached normally, the substrate is placed on a constant temperature heating platform, and the liquid is evaporated to form a film while ensuring that the substrate is not damaged;

[0013] S7. Measure the resistance of the inner wall of the substrate after coating with a multimeter, cut the substrate open and observe the surface morphology of the film under a microscope as a test indicator for testing the film formation results.

[0014] Preferably, the substrate is a quartz tube with a smooth inner wall surface or a PVDF molded flexible substrate with an undamaged surface.

[0015] Preferably, in step S3, the substrate is slowly rotated with the axis of the substrate as the rotation axis, and the PEDOT:PSS solution is not allowed to spill out during this process.

[0016] Preferably, step S4 specifically comprises:

[0017] S41, placing the substrate into a centrifuge tube;

[0018] S42, placing two centrifuge tubes for the same operation in symmetrical holes of the centrifuge;

[0019] S43, start the centrifuge, set the speed of the centrifuge to 750r / min-6000r / min, and the centrifugal spin coating time to 0.5-10min to make the film uniform.

[0020] Preferably, in step S4, the outer wall of the substrate is evenly wrapped with a buffer material, and the bottom of the centrifuge tube is filled with the buffer material; the buffer material is one of a foam adhesive strip and sterile paper.

[0021] Preferably, in step S6, the heating time is 0.5-10 min, and the heating temperature is 30°C-100°C.

[0022] Therefore, the present invention adopts the above-mentioned curved surface film formation method of PEDOT:PSS electrode based on asymmetric spin coating method, which can improve its conductivity problem, protect the device, and make the device have anti-static performance and EMI shielding performance, thereby improving the stability of the device.

[0023] Beneficial effects of the present invention:

[0024] (1) The PEDOT:PSS used in the present invention has relatively good dispersibility and stability compared to other conductive coatings; the method for coating a PEDOT:PSS solution on a curved surface adopts an asymmetric spin coating film forming process, which is simple to operate, has a fast film forming speed, low cost, and good film forming uniformity;

[0025] (2) Compared with the spin coating of the conventional spin coater, the asymmetric spin coating scheme of the PEDOT:PSS film of the present invention is asymmetric with respect to the rotating shaft; in actual operation, the present invention adopts a centrifuge, and the substrate soaked in the solution is in a centrifuge tube on one side of the centrifuge, and the other side is configured in the same manner, so that it is asymmetric for a single sample and symmetric for the centrifuge; thereby, while ensuring the normal operation of the centrifuge, the PEDOT:PSS film can be evenly spin coated;

[0026] (3) The present invention is applicable to room temperature, and can achieve good film formation on the curved surface inside the substrate, and can solve the problem of contamination of the substrate by liquid accumulation in the closed space;

[0027] (4) The uniformity of the film formed by the curved surface coating operation in the present invention is good, and the flexibility of the film formed is of great significance for the film formation of the curved surface substrate. The resistance value is moderate (1kΩ-99kΩ), which can well meet the film requirements of the device; it has an important influence on the formation of surface films of common electronic devices such as: smart wearable devices, mobile phones, watches, etc., flexible electronic skin, flexible circuit boards, etc.;

[0028] (5) The present invention can provide a method for improving a coating machine to form films on asymmetric curved surfaces; by imitating the working principle of the spin coating method, the asymmetric spin coating operation can be completed by improving the instruments used in the spin coating method or exploring new instruments.

[0029] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A flowchart of a method for forming a curved surface film of a PEDOT:PSS electrode based on an asymmetric spin coating method according to an embodiment of the present invention;

[0031] Figure 2 This is a schematic diagram of the effect of the amount of PEDOT:PSS solution on the film-forming effect on the inner wall of a quartz tube in an embodiment of a method for forming a curved surface film of a PEDOT:PSS electrode based on an asymmetric spin coating method of the present invention;

[0032] Figure 3 The present invention is a method for forming a curved surface film of a PEDOT:PSS electrode based on an asymmetric spin coating method, and a schematic diagram showing the film-forming effect of a PEDOT:PSS solution on the inner wall of a quartz tube and the influence of the rotation speed; wherein (a) is a diagram showing the film-forming effect at a rotation speed of 750 r / min; (b) is a diagram showing the film-forming effect at a rotation speed of 1500 r / min;

[0033] Figure 4 This is a surface image of a thin film on the inner wall of a quartz tube under a microscope in an embodiment of a method for forming a curved surface of a PEDOT:PSS electrode based on an asymmetric spin coating method of the present invention;

[0034] Figure 5 This is a result diagram of the film surface flatness detected by a step profilometer in an embodiment of a curved surface film forming method of a PEDOT:PSS electrode based on an asymmetric spin coating method of the present invention;

[0035] Figure 6 This is a graph showing the result of measuring the film thickness inside a quartz tube by a step profiler in an embodiment of a curved surface film forming method of a PEDOT:PSS electrode based on an asymmetric spin coating method according to the present invention;

[0036] Figure 7This is a diagram showing the optimization effect of an isolation base on the film-forming effect of a DMSO-doped PEDOT:PSS solution on the inner wall of a quartz tube in an embodiment of a curved surface film-forming method of a PEDOT:PSS electrode based on an asymmetric spin coating method of the present invention; wherein (a) is a diagram showing the film-forming effect without a base; (b) is a diagram showing the optimization effect of the film-forming effect with a base;

[0037] Figure 8 This is a diagram showing the coating results of a PVDF molded flexible substrate according to an embodiment of the present invention, a method for forming a curved surface film of a PEDOT:PSS electrode based on an asymmetric spin coating method. DETAILED DESCRIPTION

[0038] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0039] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0040] like Figure 1 As shown, a method for forming a curved surface film of a PEDOT:PSS electrode based on an asymmetric spin coating method comprises the following steps:

[0041] S1. Select a substrate and clean the substrate to obtain a clean substrate.

[0042] The substrate is a quartz tube with a flat inner wall surface or a PVDF molded flexible substrate with an undamaged surface.

[0043] S2. Use a rubber-tipped dropper to measure 0.5 ml to 2 ml of PEDOT:PSS solution, and drop the measured PEDOT:PSS solution onto the inner wall of the substrate.

[0044] S3. With the axis of the substrate as the rotation axis, slowly rotate the substrate so that the PEDOT:PSS solution is completely coated on the inner wall of the substrate, and the PEDOT:PSS solution is not allowed to spill out during this process.

[0045] S4. In order to prevent the substrate from colliding with the inner wall of the centrifuge tube and breaking during the centrifugal spin coating process, the outer wall of the substrate is evenly wrapped with a buffer material. To prevent contamination by effluent, the bottom of the centrifuge tube is filled with a buffer material to form an isolation base to isolate the substrate from the effluent. The buffer material is one of a foam adhesive strip and sterile paper. The substrate is then centrifuged and spin coated using a centrifuge.

[0046] S41. Place the substrate in a centrifuge tube.

[0047] S42. Place two centrifuge tubes for the same operation in the symmetrical holes of the centrifuge. The centrifuge must be symmetrical when working, otherwise the instrument will be damaged. For a single substrate with an asymmetrical curved surface, during spin coating, the overall operation needs to ensure the symmetrical placement of the curved surface and the instrument.

[0048] S43, start the centrifuge, set the speed of the centrifuge to 750r / min-6000r / min, and centrifuge and spin coat for 0.5-10min to make the film uniform.

[0049] S5. After the centrifugal spin coating is completed, use tweezers to take out the substrate, remove the external buffer material, and observe the film formation.

[0050] S6. When the PEDOT:PSS in the substrate is observed to be attached normally, the substrate is placed on a constant temperature heating platform, the heating time is 0.5-10 minutes, and the heating temperature is 30°C-100°C. While ensuring that the substrate is not damaged, the liquid is evaporated to form a film.

[0051] S7. Measure the resistance of the inner wall of the substrate after coating with a multimeter, cut the substrate open and observe the surface morphology of the film under a microscope as a test indicator for testing the film formation results.

[0052] Embodiment 1

[0053] A method for forming a curved surface film of a PEDOT:PSS electrode based on an asymmetric spin coating method comprises the following steps:

[0054] S1. Select a quartz tube with a thickness of 0.5 mm, an outer diameter of 8 mm, and a length of 35 mm and a flat inner wall surface as a substrate, clean the inner wall of the quartz tube to obtain a clean quartz tube.

[0055] S2. Use a rubber-tipped dropper to measure 0.5 ml, 1 ml, and 1.5 ml of PEDOT:PSS solution respectively, and drop the measured PEDOT:PSS solution on the inner wall of the quartz tube.

[0056] S3. Using the axis of the quartz tube as the rotation axis, slowly rotate the quartz tube so that the PEDOT:PSS solution is completely coated on the inner wall of the quartz tube, and the PEDOT:PSS solution is not allowed to spill out during this process.

[0057] S4. In order to prevent the quartz tube from colliding with the inner wall of the centrifuge tube and breaking during the centrifugal spin coating process, the outer wall of the quartz tube is evenly wrapped with a foam adhesive strip. To prevent contamination by effluent, the bottom of the centrifuge tube is filled with a foam adhesive strip to form an isolation base to isolate the quartz tube from the effluent, thereby avoiding contamination of the quartz tube and greatly improving the performance of the film. The quartz tube is then centrifuged and spin coated using a centrifuge.

[0058] S41. Place the quartz tube into a centrifuge tube.

[0059] S42. Place two centrifuge tubes for the same operation in the symmetrical holes of the centrifuge. Symmetry must be maintained when the centrifuge is working, otherwise the instrument will be damaged.

[0060] S43, start the centrifuge, set the speed of the centrifuge to 750r / min and 1500r / min, and the centrifugal spin coating time to 2min to make the film uniform.

[0061] S5. After the centrifugal spin coating is completed, use tweezers to take out the quartz tube, remove the external foam glue strip, and observe the film formation.

[0062] S6. After observing that the PEDOT:PSS in the quartz tube is attached normally, the quartz tube is placed on a constant temperature heating platform, the heating time is 2 minutes, and the heating temperature is 75° C. While ensuring that the substrate is not damaged, the liquid is evaporated to form a film.

[0063] S7. Use a multimeter to measure the resistance of the inner wall of the quartz tube after coating. Cut the quartz tube open and use a microscope to observe the surface morphology of the film as a test indicator to verify the film formation results.

[0064] The inner wall of the quartz tube after coating in Example 1 was experimentally verified, and the results are as follows:

[0065] (1) Figure 2 As shown, the inner wall of the quartz tube after coating with 0.5ml, 1ml and 1.5ml of PEDOT:PSS solution was compared and analyzed. The difference in the amount of solution on the inner wall of the quartz tube was due to the increase in the amount of solution during centrifugal spin coating. During the centrifugal spin coating process, the precipitation time of the solution on the inner wall of the quartz tube to the bottom of the centrifuge tube was prolonged, the film became thicker, and the uniformity of the film was affected.

[0066] (2) Figure 3 As shown in the figure, under the condition of moderate amount of solution inside the quartz tube, by comparing the film-forming effects when the rotation speed is 750r / min and 1500r / min respectively, it can be seen that appropriately increasing the rotation speed can improve the uniformity of film formation to a certain extent, which is similar to the film formation by spin coating.

[0067] (3) Figure 4-Figure 5 As shown in the figure, the scratches in the two figures are artificially made to make the film observation more intuitive, and it can be clearly seen that the uniformity of the film formation is good. Figure 6 As shown, the film thickness inside the quartz tube is 80nm.

[0068] (4) Figure 7As shown, in the experiment, an isolation base was set at the bottom of the centrifuge tube to raise the quartz tube so as to separate the accumulated liquid from the quartz tube and avoid contamination of the quartz tube, thereby greatly improving the performance of the film.

[0069] Embodiment 2

[0070] For PVDF molded flexible substrate, it is not convenient to process it into a flat surface to make it suitable for spin coating by a coater, so an asymmetric spin coating operation is used to form a film, including the following steps:

[0071] S1. Select a PVDF molded flexible substrate with a thickness of 0.5 mm and no damage on the surface, and clean the PVDF molded flexible substrate to obtain a clean PVDF molded flexible substrate.

[0072] S2. Use a rubber-tipped dropper to measure 0.5 ml of PEDOT:PSS solution, and drop the measured PEDOT:PSS solution on the inner wall of the PVDF molded flexible substrate.

[0073] S3. Using the axis of the cylindrical surface where the curved surface of the PVDF molded flexible substrate is located as the rotation axis, slowly rotate the PVDF molded flexible substrate so that the PEDOT:PSS solution is completely coated on the inner wall of the PVDF molded flexible substrate, and the PEDOT:PSS solution is not allowed to spill out during this process.

[0074] S4. In order to prevent the PVDF molded flexible substrate from colliding with the inner wall of the centrifuge tube and breaking during the centrifugal spin coating process, the outer wall of the PVDF molded flexible substrate is evenly wrapped with sterile paper. To prevent contamination by effusion, the bottom of the centrifuge tube is filled with sterile paper to form an isolation base to isolate the PVDF molded flexible substrate from the effusion. The PVDF molded flexible substrate is then centrifuged and spin coated using a centrifuge.

[0075] S41. Place the PVDF molded flexible substrate into a centrifuge tube.

[0076] S42. Place two centrifuge tubes for the same operation in the symmetrical holes of the centrifuge. Symmetry must be maintained when the centrifuge is working, otherwise the instrument will be damaged.

[0077] S43, start the centrifuge, set the speed of the centrifuge to 1500r / min, and the centrifugal spin coating time to 2min to make the film uniform.

[0078] S5. After the centrifugal spin coating is completed, use tweezers to take out the PVDF molded flexible substrate, remove the external sterile paper, and observe the film formation.

[0079] S6. After observing that the PEDOT:PSS in the PVDF molded flexible substrate is normally attached, the PVDF molded flexible substrate is placed on a constant temperature heating platform for 2 minutes at a heating temperature of 75° C. While ensuring that the substrate is not damaged, the liquid is evaporated to form a film.

[0080] S7. After the coating is completed, the resistance value of the PVDF molded flexible substrate is measured with a multimeter to observe the film formation.

[0081] The PVDF molded flexible substrate after coating in Example 2 was experimentally verified, and the results are as follows:

[0082] This experiment uses a centrifuge to complete the experimental verification, and the verification shows that Figure 8 As shown, the surface curvature of the PVDF molded flexible substrate after coating is consistent with that of the uncoated PVDF molded flexible substrate. Therefore, the processed film can be well attached to the curved surface of the PVDF molded flexible substrate. Its conductivity is good after measurement, and its resistance measured by a multimeter is 17.25kΩ.

[0083] Therefore, the present invention adopts the above-mentioned curved surface film formation method of PEDOT:PSS electrode based on asymmetric spin coating method, which can improve its conductivity problem, protect the device, and make the device have anti-static performance and EMI shielding performance, thereby improving the stability of the device.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for forming a curved surface film of a PEDOT:PSS electrode based on an asymmetric spin coating method, characterized in that: The following steps are involved: S1. Select a substrate and clean the substrate to obtain a clean substrate; S2. Use a rubber-tipped dropper to measure 0.5 ml to 2 ml of PEDOT:PSS solution, and drop the measured PEDOT:PSS solution onto the inner wall of the substrate; S3, slowly rotating the substrate to allow the PEDOT:PSS solution to be completely coated on the inner wall of the substrate; S4, using a buffer material to set the substrate and the centrifuge tube in the centrifuge, and centrifugally spin-coating the substrate through the centrifuge; S5. After the centrifugal spin coating is completed, the substrate is taken out with tweezers, and the external buffer material is removed to observe the film formation; S6. When the PEDOT:PSS in the substrate is observed to be attached normally, the substrate is placed on a constant temperature heating platform, and the liquid is evaporated to form a film while ensuring that the substrate is not damaged; S7. Measure the resistance of the inner wall of the substrate after coating with a multimeter, cut the substrate open and observe the surface morphology of the film under a microscope as a test indicator for testing the film formation results.

2. The method for forming a curved surface film of a PEDOT:PSS electrode based on an asymmetric spin coating method according to claim 1, characterized in that: The substrate is a quartz tube with a flat inner wall surface or a PVDF molded flexible substrate with an undamaged surface.

3. The method for forming a curved surface film of a PEDOT:PSS electrode based on an asymmetric spin coating method according to claim 1, characterized in that: In step S3, the substrate is slowly rotated with the axis of the substrate as the rotation axis, and the PEDOT:PSS solution is not allowed to spill out during this process.

4. The method for forming a curved surface film of a PEDOT:PSS electrode based on an asymmetric spin coating method according to claim 1, characterized in that: Step S4 specifically includes: S41, placing the substrate into a centrifuge tube; S42, placing two centrifuge tubes for the same operation in symmetrical holes of the centrifuge; S43, start the centrifuge, set the speed of the centrifuge to 750r / min-6000r / min, and the centrifugal spin coating time to 0.5-10min to make the film uniform.

5. The method for forming a curved surface film of a PEDOT:PSS electrode based on an asymmetric spin coating method according to claim 1, characterized in that: In step S4, the outer wall of the substrate is evenly wrapped with a buffer material, and the bottom of the centrifuge tube is filled with the buffer material; the buffer material is one of a foam adhesive strip and sterile paper.

6. The method for forming a curved surface film of a PEDOT:PSS electrode based on an asymmetric spin coating method according to claim 1, characterized in that: In step S6, the heating time is 0.5-10 min, and the heating temperature is 30°C-100°C.

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