Method for preparing flexible electrode layer by using laser-induced graphene and flexible electrode layer

Abstract

The invention discloses a method for preparing a flexible electrode layer by using laser-induced graphene and the flexible electrode layer. The method comprises the following steps: preparing a laser-induced graphene pattern on the surface of a polymer by using a carbon dioxide laser; and coating flexible photosensitive resin on the surface of the polymer with the laser-induced graphene pattern, carrying out ultraviolet curing, and peeling off the cured flexible photosensitive resin and the laser-induced graphene pattern from the polymer film to obtain the LIGG and flexible photosensitive resin double-layer structure. The graphene pattern induced by laser is quickly, simply and conveniently transferred to the flexible photosensitive resin substrate by adopting an ultraviolet curing method, and the flexible electrode layer which can be bent, can be patterned, has excellent conductivity and is provided with the LIGG and flexible photosensitive resin layer structure is obtained.

Description

Technical Field

[0001] The present invention belongs to the field of flexible electronic device preparation, in particular to the field of flexible electrode layer preparation of flexible pressure sensors, and specifically relates to a method for preparing a flexible electrode layer using laser-induced graphene and a flexible electrode layer. Background Art

[0002] Flexible electronic devices are a type of electronic product that is bendable, deformable, and flexible. Compared with traditional rigid electronic devices, flexible electronic devices can be attached to complex surfaces and have a wide range of application prospects in the fields of wearable devices, health monitoring, human-computer interaction, humanoid robots, etc. However, the electrode layer of flexible electronic devices is usually a thinned metal film or a metal film deposited by magnetron sputtering technology. Since the functional layer of flexible electronic devices is usually a polymer material, there is a natural modulus mismatch problem with these metal films. Therefore, if a metal film is used as an electrode layer, it will lead to poor contact between the functional layer and the electrode layer, and it is easy to cause the metal film to fall off when repeatedly bent and deformed.

[0003] Laser-induced graphene (LIG) is a method discovered in the past decade to generate graphene on the surface of carbon-rich materials. Graphene structures can be induced by laser irradiation on the surface of carbon-containing materials. The inventors of the present application recognize that since the graphene induced by this method has good electrical properties and its pattern can be freely adjusted by drawing software, laser-induced graphene has the potential to realize patterning of designed circuits. However, it was further discovered that high-carbon materials that can usually produce LIG are not flexible, such as polyimide films (PI films). Based on this, the inventors of the present application have continuously studied how to transfer the generated LIG to a flexible substrate by other means for use in the electrode layer of flexible electronic devices, and proposed this application. Summary of the invention

[0004] According to one embodiment of the present invention, the purpose is to provide a method for preparing a flexible electrode layer using laser-induced graphene and a flexible electrode layer. The laser-induced graphene pattern, such as a circuit pattern, is quickly and easily transferred to a flexible photosensitive resin substrate using an ultraviolet light curing method, thereby obtaining a flexible electrode layer having a LIG@flexible photosensitive resin layer structure, overcoming the limitations of the application of laser-induced graphene in flexible electronic devices.

[0005] The above purpose can be achieved by implementing the following technical solutions:

[0006] According to one aspect of the present invention, the present invention provides a method for preparing a flexible electrode layer using laser-induced graphene, comprising:

[0007] Step 1) preparing a laser-induced graphene pattern on a polymer surface using a carbon dioxide laser;

[0008] Step 2) coating a flexible photosensitive resin on the polymer surface having the laser-induced graphene pattern, performing UV light curing, and peeling the cured flexible photosensitive resin together with the laser-induced graphene pattern from the polymer film to obtain a LIG@flexible photosensitive resin double-layer structure.

[0009] Optionally, the method further comprises: step 3) depositing metal nanoparticles on the LIG@flexible photosensitive resin double-layer structure to obtain a metal nanoparticles@LIG@flexible photosensitive resin three-layer structure.

[0010] Furthermore, metal nanoparticles are deposited on the LIG@flexible photosensitive resin double-layer structure by using a chemical deposition method or an electrochemical deposition method.

[0011] Optionally, the flexible photosensitive resin is a polyacrylic photosensitive resin.

[0012] Optionally, during UV curing, the power of the UV light is 10-400 W, and the UV curing time is 1-60 s. Further, UV curing is performed in a 405 nm UV curing box, and the distance between the sample and the UV light source is 10-400 mm.

[0013] Optionally, the coating method of coating the flexible photosensitive resin on the polymer surface having the laser-induced graphene circuit pattern is a spin coating method or a template dropping method.

[0014] Furthermore, the spin coating method refers to using a coating machine to spin coat the uncured flexible photosensitive resin liquid onto the polymer surface. Furthermore, during the spin coating, the spin coating speed is 10-5000rpm and the spin coating time is 1-60s;

[0015] Furthermore, the template dropping method refers to adhering a polymer having a laser-induced graphene circuit pattern to the bottom of the template, and dropping uncured flexible photosensitive resin liquid onto the polymer surface until the flexible photosensitive resin liquid fills the template. Furthermore, the thickness of the template is 0.1-50 mm.

[0016] Optionally, in the template dropping method, after the flexible photosensitive resin liquid fills the template, it further comprises: a vacuuming step under vacuum conditions. Furthermore, the vacuuming time is 1-60 minutes.

[0017] Optionally, the sheet resistance of the LIG@flexible photosensitive resin double-layer structure is 0.1-100 kΩ / □.

[0018] Optionally, in the step of preparing a laser-induced graphene pattern on the polymer surface using a carbon dioxide laser, a scanning pattern is preset based on CorelDRAW software, and laser scanning with a carbon dioxide laser is used to prepare the laser-induced graphene pattern.

[0019] Furthermore, the laser wavelength of the carbon dioxide laser is 10.6 μm, the laser power is 2W-50W, the scanning speed is 10-1000 mm / s, and the laser printing resolution is 10-1000 PPI.

[0020] Furthermore, the scan pattern preset by CorelDRAW software is a circuit pattern, and the prepared laser induced graphene pattern is a laser induced graphene circuit pattern.

[0021] Optionally, the sheet resistance of LIG in the laser-induced graphene pattern on the polymer surface is 1-500Ω / □.

[0022] Optionally, a chemical deposition method at high temperature is used to deposit metal nanoparticles on the LIG@flexible photosensitive resin double-layer structure. Optionally, the method includes: dissolving an active metal ion solution in ethanol to obtain a mixed solution; dripping the mixed solution on the surface of the LIG@flexible photosensitive resin double-layer structure and reacting at high temperature.

[0023] Furthermore, the volume ratio of the active metal ion solution to ethanol is 1:1-1:50.

[0024] Furthermore, the high temperature is 80-150° C., and the reaction time is 1-100 s.

[0025] Optionally, the sheet resistance of the metal nanoparticle@LIG@flexible photosensitive resin three-layer structure is 0.01-100Ω / □.

[0026] According to another aspect of the present invention, a flexible electrode layer provided by the present invention is prepared by the method for preparing a flexible electrode layer by using laser-induced graphene as described in the present invention.

[0027] Beneficial effects: According to one embodiment of the present invention, a flexible photosensitive resin substrate is used, which has good bendability and stretchability. The graphene induced by laser on a polymer such as polyimide can be quickly and easily transferred to the flexible photosensitive resin substrate by UV curing. Moreover, when the graphene is laser-induced, a corresponding pattern can be obtained on the flexible photosensitive resin substrate by designing the LIG pattern, thereby achieving patterning (for example, designing a planar circuit pattern to achieve circuit patterning), and a flexible and conductive LIG@flexible photosensitive resin double-layer structure is prepared, which can be used as an electrode layer of a flexible electronic device.

[0028] In addition, in a preferred embodiment of the present invention, a flexible photosensitive resin is used as a flexible substrate, LIG ​​is used as an intermediate layer, and metal nanoparticles are deposited in the porous structure of LIG to improve its conductive properties. Through the synergistic effect of LIG and metal nanoparticles, a flexible electrode layer with a three-layer structure of metal nanoparticles@LIG@flexible photosensitive resin that is bendable, patternable, and has excellent conductive properties is obtained, which can be used as an electrode layer of flexible electronic devices.

[0029] Compared with the prior art, some embodiments of the present invention also have the following advantages:

[0030] 1) Using ultraviolet light curing technology, the LIG pattern can be transferred to a flexible photosensitive resin substrate, and there is almost no residual graphene on the laser-induced graphene substrate after transfer, resulting in a LIG@flexible photosensitive resin double-layer structure that can be used as an electrode layer for flexible electronic devices.

[0031] 2) By designing the LIG pattern, a corresponding pattern can be obtained on a flexible photosensitive resin substrate, thus realizing material patterning; in particular, the pattern of a planar circuit can be designed to realize circuit patterning, which can be used as a flexible circuit for flexible electronic devices.

[0032] 3) After the step of coating the flexible photosensitive resin on the polymer surface with the LIG pattern by the template dropping method, vacuum is drawn for a period of time under vacuum conditions to ensure that the flexible photosensitive resin liquid can penetrate into the LIG porous structure on the polymer.

[0033] 4) Since the LIG structure after transfer is damaged, its resistance increases. By depositing metal nanoparticles in the double-layer LIG porous structure, the conductive performance of the flexible electrode layer is improved.

[0034] 5) When depositing metal nanoparticles, by adjusting the experimental parameters, metal nanoparticles can be deposited more evenly in the LIG porous structure, further improving the conductive properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the whole process of preparing a flexible electrode layer by using laser-induced graphene according to an embodiment of the present invention;

[0036] Figure 2 is a scanning electron microscope image of laser-induced generation of graphene on a PI film in one embodiment of the present invention;

[0037] Figure 3 This is a scanning electron microscope image of the LIG structure on the surface of the LIG@flexible photosensitive resin double-layer structure obtained in one embodiment of the present invention;

[0038] Figure 4is an X-ray photoelectron spectrum of LIG on a PI film and LIG on a flexible photosensitive resin substrate in one embodiment of the present invention;

[0039] Figure 5 This is an X-ray diffraction analysis diagram of the three-layer structure of silver nanoparticles@LIG@flexible photosensitive resin in one embodiment of the present invention. DETAILED DESCRIPTION

[0040] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] In one embodiment of the present invention, a method for preparing a flexible electrode layer using laser-induced graphene is provided, comprising the following steps:

[0042] Step 1) A laser-induced graphene (LIG) pattern with a porous structure is induced on a polymer using a carbon dioxide (CO2) laser.

[0043] The polymer refers to a carbon-containing material whose surface can be induced to have a graphene structure by laser irradiation, such as a polymer such as polyimide. The graphene induced by the carbon-containing material by laser has good electrical properties. Its pattern, such as a circuit pattern, is designed by drawing software, thereby realizing the preparation of laser-induced graphene patterns and patterning of the flexible electrode layer.

[0044] Furthermore, the laser wavelength of the carbon dioxide laser is 10.6 μm, the laser power is 2W-50W, the scanning speed is 10-1000 mm / s, and the laser printing resolution is 10-1000 PPI. When the carbon dioxide laser induces the carbon-containing material to prepare graphene, the laser scanning pattern is pre-designed by CorelDRAW software, including graphics, size, etc., such as the LIG circuit pattern scanned by the preset laser. In this step, the LIG square resistance prepared on a polymer such as polyimide is 1-500 Ω / □.

[0045] Step 2) Using ultraviolet light curing technology, the LIG pattern is transferred to a flexible photosensitive resin substrate to obtain a LIG@flexible photosensitive resin double-layer structure. The flexible photosensitive resin is a resin that can undergo a polymerization reaction under ultraviolet light irradiation conditions and thus solidify. Furthermore, the flexible photosensitive resin is a polyacrylic photosensitive resin material. In addition, in this step, the LIG pattern can be completely transferred. Complete transfer means that the laser-induced graphene can be cleanly transferred to the surface of the flexible substrate, and there is almost no residual graphene on the substrate of the laser-induced graphene after transfer.

[0046] Specifically, it includes:

[0047] Step 21) firstly uniformly coat the uncured flexible photosensitive resin liquid on the surface of the polymer such as polyimide having the LIG circuit pattern. During the coating, the coating can be carried out by method (a) or method (b).

[0048] Method (a): Use a coating machine to spin-coat the flexible photosensitive resin onto the surface of a polymer such as polyimide, wherein the spin-coating speed may be 10-5000 rpm and the spin-coating time may be 1-60 s.

[0049] Method (b): Polyimide or other polymers are adhered to the bottom of the template, and then a flexible photosensitive resin liquid is dripped onto the surface of the polyimide or other polymer until the flexible photosensitive resin completely fills the template. The thickness of the template can be 0.1-50 mm.

[0050] Preferably, when the coating method (b) is adopted, after the flexible photosensitive resin liquid completely fills the template, the method further comprises: evacuating the template under vacuum conditions for a period of time to ensure that the flexible photosensitive resin liquid can penetrate into the LIG porous structure on the polymer such as polyimide. The evacuating time is 1-60 minutes.

[0051] Step 22) Then, the sample is subjected to a photocuring reaction under the irradiation of ultraviolet light, wherein the sample to be cured is placed in a 405nm ultraviolet light curing box, the ultraviolet light power is 10-400W, the sample is 10-400mm away from the ultraviolet light source, and the ultraviolet light curing time is 1-60s.

[0052] Step 23) Finally, the cured flexible photosensitive resin film together with the LIG pattern is peeled off from the surface of the polymer such as polyimide, thus completing the transfer of the LIG pattern and obtaining a LIG@flexible photosensitive resin double-layer structure.

[0053] In this step, the LIG@flexible photosensitive resin double-layer structure prepared has a square resistance of 0.1-100 kΩ / □.

[0054] In a preferred embodiment, the method further comprises: step 3) depositing metal nanoparticles in the LIG porous structure of the LIG@flexible photosensitive resin double-layer structure to prepare a metal nanoparticle@LIG@flexible photosensitive resin three-layer structure. The metal nanoparticles may be, for example, metal nanoparticles such as Cu, Ag, and Au. The inventors of the present application noticed that the LIG structure after transfer was damaged (cracks appeared), resulting in an increase in its resistance. In this preferred embodiment, the conductive properties of the material are improved by depositing metal nanoparticles in the LIG porous structure. Based on the synergistic effect of LIG and metal nanoparticles, a bendable, patternable and conductive metal nanoparticle@LIG@flexible photosensitive resin three-layer structure is obtained, which can be used as an electrode layer of flexible electronic devices.

[0055] In addition, a chemical method is used to deposit metal nanoparticles in the porous structure of LIG by chemical reaction at high temperature. For example, by chemical deposition at high temperature, the active metal ions are reduced to metal particles to complete the deposition by chemical reaction. Furthermore, when depositing metal nanoparticles, the amount of metal ion active solution added, the heating temperature and the heating time are adjusted to uniformly deposit the metal nanoparticles in the LIG porous structure, thereby further improving the conductive performance. Specifically, it includes: dripping an active metal ion mixed solution on the surface of the LIG@flexible photosensitive resin double-layer structure; chemically reacting at a high temperature of 80-150°C for 1-100s, and generating metal nanoparticles on the surface of the LIG@flexible photosensitive resin double-layer structure after the reaction, that is, preparing a metal nanoparticle@LIG@flexible photosensitive resin three-layer structure, which effectively improves its conductive performance. Among them, during deposition, the amount of metal ion active solution added is 1μL / cm 2 -100μL / cm 2 In addition, the active metal ion mixed solution is obtained by dissolving the active metal ion solution in ethanol, and the volume ratio of the active metal ion solution to the ethanol is 1:1-1:50.

[0056] In this preferred embodiment, the sheet resistance of the prepared metal nanoparticles@LIG@flexible photosensitive resin three-layer structure is 0.01-100Ω / □. It can be seen that by depositing metal nanoparticles and adjusting the parameters, the sheet resistance of the material can be reduced from 0.1-100kΩ / □ to 0.01-100Ω / □, greatly improving the conductive performance of the material.

[0057] The technical solution of the present invention is further described below in conjunction with a specific embodiment. It should be noted that: in this embodiment, the preset scanning pattern is a square, but it is certainly not limited to this. The preset scanning pattern and its size can be directly designed using the software according to needs. For example, the scanning pattern is pre-designed as a circuit, so that the circuit patterning in the flexible electrode layer is realized.

[0058] Example 1

[0059] Figure 1 The whole process of this embodiment is schematically shown. Figure 1 As shown, this embodiment provides a method for preparing a flexible electrode layer using laser-induced graphene, comprising the following steps:

[0060] (1) Preparation of laser-induced graphene pattern. The parameters of the carbon dioxide laser were first set to laser power P = 7.5 W, laser scanning rate ν = 200 mm / s, and laser printing resolution 300 PPI. The carbon dioxide laser was used to scan a polyimide film (PI film) with a thickness of 500 μm, and the scanning pattern was preset in advance using CorelDRAW software to be a square with a size of 10 mm*10 mm. After the carbon dioxide laser was laser-scanned according to the preset scanning pattern, laser-induced graphene with the preset pattern was prepared on the PI film. The scanning electron microscope image thereof is shown in FIG. Figure 2 shown.

[0061] (2) The PI film with LIG pattern printed on its surface was adhered to the bottom of a 10 mm*10 mm*2 mm polytetrafluoroethylene template using double-sided tape.

[0062] Afterwards, the flexible photosensitive resin is pretreated. The flexible photosensitive resin used in this embodiment is Agilus 30 produced by Stratasys, referred to as A 30. The pretreatment is to put the A 30 resin into a vacuum drying oven and repeat the debubbling operation 3 times.

[0063] (3) Use a rubber-tipped dropper to drip A30 resin into the polytetrafluoroethylene template with the PI film attached to the bottom until the resin liquid completely fills the template. The filled template is then placed under vacuum conditions for 30 minutes. The purpose of vacuuming is to allow the A30 resin to fully penetrate into the porous structure of LIG under negative pressure.

[0064] After vacuuming, the template was placed in a UV curing box, with the template 100 mm away from the UV light source. The UV light source power was adjusted to 100% to start curing, and the curing time was 50 seconds. After the curing was completed, it was taken out, and the cured flexible photosensitive resin substrate was peeled off from the template, and then the PI film was peeled off to prepare the LIG@flexible photosensitive resin double-layer structure. The scanning electron microscope image is shown in Figure 2. Figure 3 As shown, the X-ray photoelectron spectrum is as follows Figure 4 shown.

[0065] (4) Place the LIG@flexible photosensitive resin double-layer structure on a heating table, and then use a pipette to drip a mixed solution of active silver ion solution and ethanol in a volume ratio of 1:4 on it, and control the amount of metal ion active solution dripped; after the solution fully infiltrates the LIG on the surface of the double-layer structure, turn on the heating table and set the temperature to 110°C to allow the solution to react and deposit silver nanoparticles on LIG to obtain a three-layer structure of Ag nanoparticles@LIG@flexible photosensitive resin. Its X-ray diffraction analysis diagram is shown below Figure 5 shown.

[0066] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a flexible electrode layer using laser-induced graphene, characterized in that: include: Step 1) preparing a laser-induced graphene pattern on a polymer surface using a carbon dioxide laser; Step 2) coating a flexible photosensitive resin on the polymer surface having the laser-induced graphene pattern, performing UV light curing, and peeling the cured flexible photosensitive resin together with the laser-induced graphene pattern from the polymer film to obtain a LIG@flexible photosensitive resin double-layer structure.

2. The method for preparing a flexible electrode layer using laser-induced graphene according to claim 1, characterized in that: Also includes: Step 3) depositing metal nanoparticles on the LIG@flexible photosensitive resin double-layer structure by chemical deposition or electrochemical deposition to obtain a metal nanoparticles@LIG@flexible photosensitive resin three-layer structure.

3. The method for preparing a flexible electrode layer using laser-induced graphene according to claim 1 or 2, characterized in that: The flexible photosensitive resin is a polyacrylic photosensitive resin.

4. The method for preparing a flexible electrode layer using laser-induced graphene according to claim 1 or 2, characterized in that: UV curing is performed in a 405nm UV curing box, and the distance between the sample and the UV light source is 10-400mm; during UV curing, the power of the UV light is 10-400W, and the UV curing time is 1-60s.

5. The method for preparing a flexible electrode layer using laser-induced graphene according to claim 1 or 2, characterized in that: The coating method of coating a flexible photosensitive resin on a polymer surface having a laser-induced graphene pattern is a spin coating method; wherein the spin coating method refers to using a coating machine to spin coat an uncured flexible photosensitive resin liquid onto a polymer surface; during spin coating, the spin coating speed is 10-5000rpm and the spin coating time is 1-60s.

6. The method for preparing a flexible electrode layer using laser-induced graphene according to claim 1 or 2, characterized in that: The coating method for coating the flexible photosensitive resin on the polymer surface with the laser-induced graphene pattern is the template dropping method; Among them, the template dropping method is to adhere the polymer with laser-induced graphene pattern to the bottom of the template, drop the uncured flexible photosensitive resin liquid onto the polymer surface, drop it until the flexible photosensitive resin liquid fills the template, and evacuate it under vacuum conditions for 1-60 minutes; the thickness of the template is 0.1-50mm.

7. The method for preparing a flexible electrode layer using laser-induced graphene according to claim 1 or 2, characterized in that: The sheet resistance of the LIG@flexible photosensitive resin double-layer structure is 0.1-100 kΩ / □.

8. The method for preparing a flexible electrode layer using laser-induced graphene according to claim 1 or 2, characterized in that: In the step of preparing a laser-induced graphene pattern on a polymer surface using a carbon dioxide laser, a scanning pattern is preset based on CorelDRAW software, and a laser scanning with a carbon dioxide laser is used to prepare the laser-induced graphene pattern; The laser wavelength of the carbon dioxide laser is 10.6 μm, the laser power is 2W-50W, the scanning speed is 10-1000 mm / s, and the laser printing resolution is 10-1000 PPI; The sheet resistance of the laser-induced graphene in the laser-induced graphene pattern is 1-500Ω / □.

9. The method for preparing a flexible electrode layer using laser-induced graphene according to claim 8, characterized in that: The scan pattern preset by CorelDRAW software is a circuit pattern, and the prepared laser-induced graphene pattern is a laser-induced graphene circuit pattern.

10. The method for preparing a flexible electrode layer using laser-induced graphene according to claim 2, characterized in that: Depositing metal nanoparticles on the surface of the LIG@flexible photosensitive resin double-layer structure by a chemical deposition method at high temperature; The method comprises: dissolving an active metal ion solution in ethanol to obtain a mixed solution; dripping the mixed solution on the surface of the LIG@flexible photosensitive resin double-layer structure and reacting at high temperature; wherein the volume ratio of the active metal ion solution to the ethanol is 1:1-1:50; the high temperature is 80-150°C, and the reaction time is 1-100s.

11. The method for preparing a flexible electrode layer using laser-induced graphene according to claim 2, characterized in that: The sheet resistance of the three-layer structure of metal nanoparticles@LIG@flexible photosensitive resin is 0.01-100Ω / □.

12. A flexible electrode layer, characterized in that: The flexible electrode layer is prepared by the method for preparing a flexible electrode layer using laser-induced graphene as described in any one of claims 1 to 11.

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