CN112201408B - Preparation method of flexible transparent conductive film - Google Patents

Abstract

The invention belongs to the technical field of flexible electronic materials, and discloses a preparation method of a flexible transparent conductive film. The metal nanowire film in the hollow area is combined with the graphene oxide layer, and/or the metal nanowire film corresponding to the mask covered area is combined with the graphene oxide layer; using a surface-adhesive flexible substrate, adhered and bonded with graphite oxide The metal nanowire film of the alkene layer is peeled off from the rigid substrate or the mask to obtain a flexible transparent conductive film with a mask hollow area pattern and/or a flexible transparent conductive film with a mask covering area pattern. The method of the invention can selectively transfer the silver nanowire film pattern from the rigid substrate to the flexible substrate without damage, thereby realizing the preparation of the flexible transparent conductive film, and the prepared flexible transparent conductive film has good pattern accuracy and optoelectronic properties.

Description

Preparation method of flexible transparent conductive film

technical field

The invention belongs to the technical field of flexible electronic materials, and particularly relates to a preparation method of a flexible transparent conductive film.

Background technique

Transparent conductive film patterns are an important part of electronic devices and are widely used in touch display, organic electroluminescence, organic solar cells, electromagnetic shielding and other fields. At present, the most commonly used transparent conductive material is indium tin oxide (ITO). However, ITO is prepared by gas-phase sputtering process, and the raw material is wasted seriously. In addition, the indium raw material is scarce, resulting in high cost of highly conductive ITO. In addition, the high-temperature annealing process of ITO limits the use of many transparent polymer substrates, and the bending resistance of ITO is poor, which makes ITO unable to meet the needs of flexible electronics. As a flexible alternative to ITO, a flexible transparent conductive film with silver nanowire thin film patterns formed on a flexible transparent substrate has excellent light transmittance, conductivity and bending resistance, and has broad prospects in flexible electronics.

However, the fabrication of silver nanowire thin film patterns on flexible transparent substrates still faces many problems. Using photolithography, plasma etching and other methods to prepare silver nanowire thin film patterns has disadvantages such as complicated process and equipment, serious consumption and pollution of chemical materials, and high cost. Using inkjet, screen printing, gravure printing and other methods to prepare silver nanowire thin film patterns has disadvantages such as complex ink synthesis and equipment, limited pattern accuracy and scale production, and films require subsequent processing. More importantly, for flexible substrates, the above methods are subject to many limitations, such as etching methods, high temperature treatment may cause damage to flexible substrates, and silver nanowire inks have poor film-forming properties on many flexible substrates. Due to the hydrophobicity of some flexible transparent substrates (such as PDMS), it is difficult to directly deposit silver nanowire films on them, and a long time plasma hydrophilic treatment is required before the deposition of silver nanowire films. Energy waste; and the method of fabricating thin film patterns based on the hydrophilic and hydrophobic treatment of the substrate also has the same disadvantage.

After preparing the silver nanowire thin film on the rigid substrate, transferring the patterned silver nanowire thin film to the flexible substrate is one of the optional methods for preparing the flexible transparent conductive thin film. However, on the one hand, how to achieve the non-destructive transfer of silver nanowire thin film patterns from rigid substrates to flexible substrates is a technical difficulty. The silver nanowire film deposited directly on the glass substrate by spin coating, spray coating, blade coating, etc., the silver nanowire has adhesion to the glass substrate. A considerable part remained on the glass substrate, and the 3M adhesive tape transfer part could not form a conductive network. Even if the flexible polymer precursor is coated on the surface of the film and peeled off after curing, a considerable part of the silver nanowires cannot be transferred to the flexible substrate, and the stress during the peeling process will also cause network damage, resulting in the network of silver nanowires on the flexible substrate. Conductive or weakly conductive. In the prior art, the silver nanowire film is usually prepared by vacuum filtration. The silver nanowire film is transferred from the filter film to the glass substrate and has weak adhesion. The flexible base material is coated on the surface of the film and peeled off after curing. Complete transfer to flexible substrates is possible. However, the vacuum filtration method involved in this process is cumbersome in actual production and difficult to apply on a large scale. On the other hand, how to achieve the selective transfer of specific patterns in thin films, there is currently no ideal method. Whether the pattern is first prepared on a rigid substrate and then transferred to a flexible substrate, or the ink is printed on a flexible substrate by methods such as gravure printing, the traditional patterning techniques used have technical, equipment and material challenges.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a preparation method of a flexible transparent conductive film in view of the above-mentioned deficiencies of the prior art, which can selectively transfer the silver nanowire film pattern from a rigid substrate to a flexible substrate without loss, thereby realizing flexible transparent conductive film. Preparation of thin films.

In order to solve the above-mentioned technical problems, an embodiment of the present invention provides a method for preparing a flexible transparent conductive film, which includes the following steps: on a rigid substrate, a step of coating a metal nanowire film in a variable order and a step of covering a mask are performed. , the mask has a hollow area and a covering area; the metal nanowire film corresponding to the mask hollow area is combined with the graphene oxide layer, and/or the metal nanowire film corresponding to the mask covered area is combined Graphene oxide layer; using a surface-adherable flexible substrate, a metal nanowire film incorporating a graphene oxide layer is adhered, and peeled off from the rigid substrate or mask to obtain a flexible transparent conductive film with a pattern of mask hollow areas and/or a flexible transparent conductive film with a pattern of mask coverage areas.

Compared with the prior art, the embodiments of the present invention provide a method for preparing a flexible thin film that relies on the double-sided adhesion of a graphene oxide layer to transfer silver nanowires. Based on this, the present invention first proposes two technical ideas: first, to prepare a continuous silver nanowire film on a rigid substrate, and then selectively transfer a specific patterned silver nanowire film to a flexible substrate; second , fabricating patterned silver nanowire films directly on rigid substrates, and then transferring the patterned silver nanowire films onto flexible substrates. Corresponding to the above two technical ideas, the present invention provides two optional preparation processes:

1. The optional first preparation process includes the following steps: S1: coating a metal nanowire film on a rigid substrate; S2: covering a mask on the metal nanowire film; S3: selectively making the mask hollow area or The metal nanowire film in the area covered by the mask is combined with the graphene oxide layer; S4: Using a surface-adherable flexible substrate, the metal nanowire film combined with the graphene oxide layer is adhered and peeled off from the rigid substrate to obtain a mask with a mask A flexible transparent conductive film with a pattern of hollow areas and/or a flexible transparent conductive film with a pattern of mask coverage areas.

Wherein, for the step of selectively combining the metal nanowire film in the mask hollow area or the mask covering area with the graphene oxide layer in step S3, the present application provides two more specific solutions.

As the first solution, in order to selectively combine the metal nanowire film in the hollow area of the mask with the graphene oxide layer, the following steps are performed: S311 : coating the graphene oxide dispersion liquid on the metal nanowire film covered with the mask surface, so that the metal nanowire film in the hollow area of the mask is combined with the graphene oxide layer; S312 : remove the mask.

As the second solution, in order to selectively combine the metal nanowire thin film in the area covered by the mask with the graphene oxide layer, the following steps are performed: S321 : UV-ozone treatment or plasma cleaning is performed on the metal nanowire thin film covered with the mask Treatment, so that the metal nanowire film in the hollow area of the mask loses its adhesion with graphene oxide; S322: remove the mask; S323: apply the graphene oxide dispersion on the surface of the silver nanowire film to cover the mask Areas of metal nanowire films combined with graphene oxide layers.

The following is a detailed description of the first and second options:

The first solution is: after preparing the metal nanowire film on a rigid substrate, cover the surface of the metal nanowire film with a mask, and coat the graphene oxide dispersion on the surface of the metal nanowire film covered with the mask, so that the mask The metal nanowire film in the hollow area of the mold is combined with the graphene oxide layer. After removing the mask, a flexible substrate with an adhesive surface is used to adhere the metal nanowire film combined with the graphene oxide layer and peel off from the rigid substrate. The double-sided adhesion of the graphene oxide layer to the metal nanowires and the flexible substrate transfers the metal nanowires in the hollow area of the mask from the rigid substrate to the flexible substrate to obtain flexible, transparent and conductive metal nanowires consistent with the pattern of the hollow area of the mask. The thin film, meanwhile, the metal nanowire pattern in the area covered by the mask remains on the rigid substrate.

It can be seen that the first scheme utilizes the adhesion between the graphene oxide layer and the metal nanowires, the adhesion between the cohesive flexible substrate and the graphene oxide layer, and uses graphene oxide to make the mask hollow area The metal nanowire film pattern is selectively transferred from the rigid substrate to the flexible substrate, thereby producing a flexible transparent conductive film with a pattern of masked hollow regions.

The second scheme is: after the metal nanowire film is prepared on the rigid substrate, a mask is covered on the surface of the metal nanowire film, and the metal nanowire film covered with the mask is subjected to ultraviolet ozone treatment or plasma cleaning treatment; After the metal nanowires in the hollow area are treated with ultraviolet ozone or plasma cleaning, the surface structure changes, and the adhesion to graphene oxide is very weak, and can no longer be combined with the graphene oxide layer on the surface. The adhesion performance is enhanced and the transferability of the surface graphene oxide is weakened; while the metal nanowires in the area covered by the mask maintain the original surface structural characteristics and can be closely combined with the graphene oxide layer. After removing the mask, coat the graphene oxide dispersion on the surface of the silver nanowire film, so that the metal nanowire film in the area covered by the mask is combined with the graphene oxide layer, and then use a surface-adhesive flexible substrate to adhere The metal nanowire film combined with the graphene oxide layer is peeled off from the rigid substrate, and the mask covering area (that is, without UV ozone treatment or Plasma-cleaned) silver nanowires were transferred from a rigid substrate to a flexible substrate to obtain a flexible transparent conductive film of metal nanowires consistent with the pattern of the mask coverage area.

It can be seen that the second scheme changes the local surface properties of the metal nanowire film and the rigid substrate through ultraviolet ozone treatment or plasma cleaning treatment, and utilizes the selective adhesion of graphene oxide to metal nanowires with different surface characteristics, Adhesion between the adhesive flexible substrate and the graphene oxide layer to selectively transfer the metal nanowire thin film pattern in the masked area from the rigid substrate to the flexible substrate, resulting in a flexible masked area patterned Transparent conductive film.

Further, for the first scheme, using a surface-adhesive flexible substrate, a metal nanowire film combined with a graphene oxide layer is adhered and peeled off from the rigid substrate to obtain a flexible transparent conductive pattern with a mask hollow area pattern. After the film, it also includes: S5: coating the graphene oxide dispersion on the surface of the metal nanowire film left on the rigid substrate; S6: using a surface-adhesive flexible substrate to adhere the metal with the graphene oxide layer The nanowire film is peeled off from the rigid substrate to obtain a flexible transparent conductive film with a pattern of mask coverage areas. That is to say, for the metal nanowire pattern in the mask-covered area still left on the rigid substrate, the adhesion between the graphene oxide layer and the metal nanowire, the bond between the flexible substrate and the graphene oxide layer are again utilized. With the help of graphene oxide, the part of the metal nanowire pattern is transferred to the flexible substrate, so that a flexible transparent conductive film of metal nanowires consistent with the pattern of the mask coverage area can be obtained. Through two transfers, two metal nanowire flexible film patterns were prepared, corresponding to the mask hollow area pattern and the mask covering area pattern, respectively, and the metal nanowire film on the rigid substrate was fully utilized.

2. The optional second preparation process includes the following steps: SS1: cover the rigid substrate with a mask; SS2: coat the surface of the rigid substrate covered with the mask with a metal nanowire film; make the metal nanowire film separately Deposited on the mask surface of the mask covered area and the rigid substrate surface of the mask hollow area; SS3: Coat the graphene oxide dispersion on the surface of the metal nanowire film, so that the deposited on the mask surface of the mask covered area and The metal nanowire films on the surface of the rigid substrate in the hollow area of the mask are respectively combined with graphene oxide layers; SS4: separate the mask from the rigid substrate; SS5: use a surface-adhesive flexible substrate, which is bonded to the rigid substrate with graphite oxide The metal nanowire film of the graphene layer is peeled off from the rigid substrate to obtain a flexible transparent conductive film with a mask hollow area pattern; SS6: Use a surface-adhesive flexible substrate, and the surface of the adhesive mask is combined with a graphene oxide layer The metal nanowire film is peeled off from the mask surface to obtain a flexible transparent conductive film with a mask covering area pattern.

In the second preparation process, the pattern structure of the silver nanowire thin film was first prepared on the rigid substrate and the mask surface respectively, and then the adhesion between the graphene oxide layer and the metal nanowires was used, and the surface can be adhered to the flexible substrate. The adhesion between the graphene oxide layer and the metal nanowire film pattern on the rigid substrate or mask is non-destructively transferred to the flexible substrate with the help of graphene oxide, so as to prepare a flexible transparent conductive film with a pattern of mask hollow areas , and a flexible transparent conductive film with a pattern of mask coverage areas.

Preferably, in the preparation method of the flexible transparent conductive film provided by the present application, the rigid substrate is selected from glass or silicon wafer. Coating the metal nanowire film on the above rigid substrate can be realized by coating the metal nanowire dispersion on the rigid substrate by rod coating, spin coating, spray coating, blade coating, etc., wherein the metal nanowire dispersion can be It is formed by dispersing metal nanowires in solvents such as water, ethanol, and isopropanol.

Preferably, in the preparation method of the flexible transparent conductive film provided by the present application, the metal nanowire film is a silver nanowire film; preferably, the silver nanowire has a diameter of 20-100 nm and a length of 10-100 μm.

Preferably, in the preparation method of the flexible transparent conductive film provided by the present application, the pattern structure or hollow structure of the pattern mask should be consistent with the target pattern of the flexible transparent conductive film to be prepared, and the mask should be consistent with glass, silicon wafer, etc. Rigid substrates have good conformability.

Preferably, in the preparation method of the flexible transparent conductive film provided by the present application, the concentration of the graphene oxide dispersion liquid is 0.5-5 mg/ml.

Preferably, in the preparation method of the flexible transparent conductive film provided by the present application, the graphene oxide dispersion is coated on the surface of the metal nanowire film by drop coating, dip coating, spray coating or spin coating.

Preferably, in the preparation method of the flexible transparent conductive film provided by the present application, the surface-adherable flexible substrate is a flexible substrate or a transparent tape coated with glue on the surface. Wherein, the glue can be selected from various commercial transparent glues and adhesives, and the transparent adhesive tape can be selected from various commercial transparent adhesive tapes with weaker viscosity. In the steps of adhering the graphene oxide layer-incorporated metal nanowire film and peeling off the rigid substrate using a flexible substrate coated with glue, the peeling should be done before the glue on the flexible substrate dries or cures.

Preferably, in the preparation method of the flexible transparent conductive film provided by the present application, the flexible substrate is preferably selected from polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethylene ( PE), polyimide (PI), polydimethylsiloxane (PDMS), polyvinyl alcohol (PVA), polyurethane (PU) or polymethyl methacrylate (PMMA), etc.

In addition, in the preparation method of the flexible transparent conductive film provided by the present application, the time of the ultraviolet ozone treatment or the plasma cleaning treatment is adjusted according to the power of the instrument, for example, the power is 100W, and the time is 1 to 2 minutes to change the metal in the hollow area of the mask. The surface properties of the nanowire film and its inability to bind tightly to graphene oxide.

Compared with the traditional preparation method of the flexible metal nanowire film, the preparation method of the flexible transparent conductive film provided by the present invention also has the following characteristics: the process is simple and environmentally friendly, no complicated processes such as high temperature, high pressure and vacuum filtration are required, and no expensive equipment and A large amount of material consumption can realize the complete transfer of metal nanowire film patterns from rigid substrates to various flexible substrates, including hydrophobic substrates. The prepared flexible transparent conductive films have good pattern accuracy and optoelectronic properties.

Description of drawings

1 is a flow chart of the preparation of the flexible transparent conductive film according to the first embodiment of the present invention;

2 is an optical microscope magnified image of a silver nanowire-graphene oxide-PE flexible film grid pattern in Example 1 of the present invention;

3 is a flow chart of the preparation of the flexible transparent conductive film according to the second embodiment of the present invention;

4 is an optical microscope magnified image of the silver nanowire-graphene oxide-PDMS flexible film grid pattern in Example 2 of the present invention;

5 is a flow chart of the preparation of the flexible transparent conductive film according to the third embodiment of the present invention;

6 is an optical microscope magnified image of the silver nanowire-graphene oxide-PE flexible film grid pattern in Example 3 of the present invention;

FIG. 7 is a flow chart of the preparation of the flexible transparent conductive film according to the fourth embodiment of the present invention.

Detailed ways

In order to understand the objects, features and advantages of the present invention more clearly, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The materials used without specifying the manufacturer are conventional products that can be purchased from the market. The description of the exemplary embodiments is for illustrative purposes only, and not for the purpose of limiting the invention and its applications.

The flow chart of the method for preparing a flexible transparent conductive film according to the first embodiment of the present application is shown in FIG. 1 , and specifically includes the following steps: S1: coating a metal nanowire film on a rigid substrate; S2: coating the metal nanowires Cover the film with a mask; S311: Coat the graphene oxide dispersion on the surface of the metal nanowire film covered with the mask, so that the metal nanowire film in the hollow area of the mask is combined with the graphene oxide layer; S312: Remove the mask ; S411: Using a surface-adhesive flexible substrate, a metal nanowire film combined with a graphene oxide layer is adhered and peeled off from the rigid substrate to obtain a flexible transparent conductive film with a mask hollow area pattern; S5: Graphite oxide The graphene dispersion was coated on the surface of the metal nanowire film left on the rigid substrate; S6: Using a surface-adhesive flexible substrate, the metal nanowire film combined with the graphene oxide layer was adhered and peeled off from the rigid substrate to obtain A flexible transparent conductive film with a pattern of mask coverage areas.

The following Example 1 is an example of the first embodiment of the present application, and Comparative Example 1 is a comparative example of Example 1.

Example 1

(1) Dilute the aqueous dispersion of silver nanowires (30 nm in diameter, 20 μm in length) with ethanol to 3 mg/ml, apply a film on a clean glass substrate through an applicator, and dry naturally to form a transparent conductive film of silver nanowire network .

(2) Covering the surface of the silver nanowire film with a mask having a pattern structure, and the mask is closely attached to the surface of the film. The mask pattern is a gate pattern of 500 μm×20 mm, and the stripe pitch is 500 μm.

(3) Prepare 2mg/ml graphene oxide dispersion, drop-coat on the surface of the silver nanowire film in the hollow area of the mask, blow away the excess solution with a nitrogen gun and dry naturally.

(4) Remove the mask.

(5) The PE protective film (weak viscosity) purchased from Shanghai Jiri Electronics Co., Ltd. was used as the flexible substrate, and the PE flexible substrate was attached to the surface of the graphene oxide-silver nanowire-glass substrate (PE flexible substrate and graphene oxide layer bonding), drive out air bubbles, peel off. After the above steps, the silver nanowire film at the hollow position of the mask was transferred to the PE substrate by the graphene oxide layer, and the gate pattern of the silver nanowire film with a width and a spacing of 500 μm was obtained. The enlarged image of the optical microscope is shown in Figure 2.

(6) On the surface of the silver nanowire pattern left on the glass substrate, drop-coat graphene oxide dispersion again, blow off the excess solution with a nitrogen gun and dry naturally.

(7) The PE flexible substrate in step (5) is attached to the surface of the graphene oxide-silver nanowire-rigid substrate (the PE flexible substrate is bonded to the graphene oxide layer), and the air bubbles are removed and peeled off. After the above steps, the silver nanowire thin film pattern left on the glass substrate was transferred to the PE substrate by graphene oxide, and the silver nanowire thin film grid with the same (width and spacing of 500 μm) as the mask pattern described in step (2) was obtained. pole pattern.

In this example, two silver nanowire-graphene oxide-PE flexible film patterns are prepared through two transfers, corresponding to the mask pattern and the hollow pattern respectively. The silver nanowire film is fully utilized, the pattern boundary is clear, and the square resistance of the film area is About 25Ω/□, excellent electrical conductivity, light transmittance of more than 85%.

Comparative Example 1

(1) Dilute the aqueous dispersion of silver nanowires (30 nm in diameter, 20 μm in length) with ethanol to 3 mg/ml, apply a film on a clean glass substrate through an applicator, and dry naturally to form a transparent conductive film of silver nanowire network .

(2) The above-mentioned PE protective film (weak adhesive) was attached to the surface of the silver nanowire-glass substrate, the air bubbles were removed, and then peeled off.

After the above steps, the silver nanowire film is still completely located on the glass substrate, and the conductivity and light transmittance are almost unchanged. No silver nanowire films were obtained on PE protective film (weakly tacky) substrates.

The preparation method of the flexible transparent conductive film according to the second embodiment of the present application, the flowchart of which is shown in FIG. 3 , and specifically includes the following steps: S1: coating a metal nanowire film on a rigid substrate; S2: coating the metal nanowires Cover the film with a mask; S311: Coat the graphene oxide dispersion on the surface of the metal nanowire film covered with the mask, so that the metal nanowire film in the hollow area of the mask is combined with the graphene oxide layer; S312: Remove the mask ; S411: Using a surface-adherable flexible substrate, a metal nanowire film combined with a graphene oxide layer is adhered and peeled off from the rigid substrate to obtain a flexible transparent conductive film with a mask hollow area pattern.

The following Example 2 is an example of the second embodiment of the present application, and Comparative Example 2 is a comparative example of Example 2.

Example 2

(1) Dilute the aqueous dispersion of silver nanowires (30 nm in diameter, 20 μm in length) with ethanol to 3 mg/ml, apply a film on a clean glass substrate through an applicator, and dry naturally to form a transparent conductive film of silver nanowire network .

(2) Covering the surface of the silver nanowire film with a mask having a pattern structure, and the mask is closely attached to the surface of the film. The mask pattern is a gate pattern of 150 μm×20 mm, and the stripe pitch is 300 μm.

(3) Prepare 2mg/ml graphene oxide dispersion, drop-coat on the surface of the silver nanowire film in the hollow area of the mask, blow away the excess solution with a nitrogen gun and dry naturally.

(4) A PDMS film was prepared, and liquid glue (Deli No. 7304) was spin-coated on the surface of the PDMS film at a rotational speed of 3000 rpm and a time of 1 min.

(5) Remove the mask, attach the above PDMS substrate to the surface of the graphene oxide-silver nanowire-glass substrate, remove air bubbles, and peel off before the glue is cured.

After the above steps, the silver nanowire film at the hollow position of the mask was transferred to the PDMS substrate by the graphene oxide layer, and a silver nanowire-graphene oxide gate pattern with a width of 300 μm was obtained. The enlarged image of the optical microscope is shown in Figure 4.

The silver nanowire-graphene oxide-PDMS flexible thin film pattern prepared in this example has a clear pattern boundary, the square resistance of the thin film region is about 32Ω/□, the electrical conductivity is excellent, and the light transmittance is over 85%.

Comparative Example 2

(1) Dilute the aqueous dispersion of silver nanowires (30 nm in diameter, 20 μm in length) with ethanol to 3 mg/ml, apply a film on a clean glass substrate through an applicator, and dry naturally to form a transparent conductive film of silver nanowire network .

(2) A PDMS film was prepared, and a liquid glue (Deli No. 7304) was spin-coated on the surface of the PDMS film at a rotational speed of 3000 rpm and a time of 1 min.

(3) Attach the above PDMS substrate to the surface of the silver nanowire-glass substrate, remove air bubbles, and peel off before the glue is cured.

After the above steps, the silver nanowire film is still completely located on the glass substrate, and the conductivity and light transmittance are almost unchanged. No silver nanowire films were obtained on PDMS substrates.

The preparation method of the flexible transparent conductive film according to the third embodiment of the present application, the flowchart of which is shown in FIG. 5 , and specifically includes the following steps: S1: coating a metal nanowire film on a rigid substrate; S2: coating the metal nanowires Cover the film with a mask; S321: Perform ultraviolet ozone treatment or plasma cleaning treatment on the metal nanowire film covered with the mask, so that the metal nanowire film in the hollow area of the mask loses adhesion to graphene oxide; S322: removing the mask; S323: coating the graphene oxide dispersion liquid on the surface of the silver nanowire film, so that the metal nanowire film in the area covered by the mask is combined with the graphene oxide layer. S421: Using a surface-adhesive flexible substrate, a metal nanowire film incorporating a graphene oxide layer is adhered and peeled off from the rigid substrate to obtain a flexible transparent conductive film with a pattern of mask coverage areas

The following Examples 3 and 4 are respectively examples of the third embodiment of the present application, and Comparative Example 3 is a comparative example of Examples 3 and 4.

Example 3

(1) Dilute the aqueous dispersion of silver nanowires (30 nm in diameter, 20 μm in length) with ethanol to 3 mg/ml, apply a film on a clean glass substrate through an applicator, and dry naturally to form a transparent conductive film of silver nanowire network .

(2) Cover the surface of the silver nanowire film with a mask with a pattern structure, the mask is closely attached to the surface of the film, the mask is made of Ecoflex silica gel material, the pattern is a grid pattern of 5mm×20mm, and the stripe spacing is 5mm.

(3) The silver nanowire film covering the mask is subjected to ultraviolet ozone treatment (the silver nanowire film in the hollow area of the mask is subjected to ultraviolet ozone treatment), the lamp power of the ultraviolet cleaning machine is 100W, the treatment time is 2min, and the ultraviolet light wavelength is 185nm and 254nm.

(4) Remove the mask, apply 2 mg/ml graphene oxide dispersion droplets on the surface of the silver nanowire thin film, blow off the excess solution with a nitrogen gun and dry.

(5) Using the PE protective film (micro-adhesive tape) purchased from Shanghai Jiri Electronics Co., Ltd. as a flexible substrate, the above-mentioned substrate is attached to the surface of graphene oxide-silver nanowire-glass substrate (substrate and graphene oxide layer) fit), remove air bubbles, peel off.

After the above steps, the silver nanowire film covered by the mask pattern was transferred to the flexible substrate by the graphene oxide layer, and the silver nanowire-graphene oxide gate pattern with a width and a spacing of 5 mm was obtained. The enlarged image of the optical microscope is shown in Figure 6. shown.

The gate pattern of the silver nanowire-graphene oxide-flexible substrate prepared in this example has a clear pattern boundary and is consistent with the mask pattern, the square resistance of the thin film area is about 25Ω/□, the electrical conductivity is excellent, and the light transmittance reaches 85 %above.

Example 4

Steps (1), (2), (4), and (5) of Example 4 are the same as those of Example 3, except that step (3) is: performing plasma cleaning on the silver nanowire film covering the mask (The silver nanowire film in the hollow area of the mask was cleaned by plasma), the power of the plasma cleaning machine was 100W, and the processing time was 1min.

After the above steps, the silver nanowire thin film covered by the mask pattern was transferred to the flexible substrate by the graphene oxide layer to obtain a silver nanowire-graphene oxide flexible gate pattern with a width and a spacing of 5 mm, and the pattern boundary was clear and consistent with the mask. The pattern is consistent, the square resistance of the film area is about 25Ω/□, the electrical conductivity is excellent, and the light transmittance is over 85%.

Comparative Example 3

For comparison, steps (1), (2), (4), and (5) in Example 3 were repeated, but the silver nanowire film covering the mask was not subjected to the ultraviolet ozone treatment in step (3). In step (5), after the flexible substrate is torn off, all the silver nanowire films are transferred to the flexible substrate by graphene oxide to obtain a complete silver nanowire-graphene oxide flexible film instead of a film pattern.

The manufacturing method of the flexible transparent conductive film according to the fourth embodiment of the present application, the flowchart of which is shown in FIG. 7 , and specifically includes the following steps: SS1: cover the mask on the rigid substrate; SS2: cover the rigid substrate with the mask The surface of the substrate is coated with a metal nanowire film; the metal nanowire film is deposited on the mask surface of the mask coverage area and the rigid substrate surface of the mask hollow area respectively; SS3: coating graphene oxide on the surface of the metal nanowire film Dispersion, so that the metal nanowire films deposited on the mask surface of the mask covered area and the rigid substrate surface of the mask hollow area are respectively combined with the graphene oxide layer; SS4: separate the mask from the rigid substrate; SS5: use Surface-adherable flexible substrate, adhere to the metal nanowire film combined with graphene oxide layer on the rigid substrate, and peel off from the rigid substrate to obtain a flexible transparent conductive film with a pattern of masked hollow areas; SS6: Using surface-adherable The adhered flexible substrate, the metal nanowire film with the graphene oxide layer combined on the surface of the mask is adhered, and peeled from the surface of the mask to obtain a flexible transparent conductive film with a pattern of the mask coverage area.

The following Example 5 is an example of the fourth embodiment of the present application.

Example 5

(1) Cover the surface of the clean glass substrate with a glass mask with a pattern structure, and the mask is in close contact with the surface of the substrate. The mask pattern is a gate pattern of 500 μm×20 mm, and the stripe pitch is 500 μm.

(2) The dispersion of silver nanowires (30 nm in diameter, 20 μm in length) in isopropanol was sprayed on the substrate and the mask, dried at 100° C. for 5 min, and formed on the mask and the substrate (the hollow area of the mask) respectively. Patterned structure of silver nanowire network transparent conductive films.

(3) 2 mg/ml graphene oxide dispersion solution was prepared and sprayed on the surface of the silver nanowire thin film of the mask and the substrate (the hollow area of the mask).

(4) Remove the mask.

(5) Using PE tape (weakly viscous) purchased from Shanghai Jiri Electronics Co., Ltd. as a flexible substrate, attached to the surface of the graphene oxide-silver nanowire thin film pattern on the glass substrate, removing air bubbles, and peeling off. After the above steps, the silver nanowire thin film pattern on the glass substrate was transferred to the PE substrate by the graphene oxide layer to obtain a silver nanowire thin film gate pattern with a width and a spacing of 500 μm.

(6) Attaching the PE flexible substrate described in step (5) to the patterned surface of the graphene oxide-silver nanowire thin film on the pattern mask, removing air bubbles, and peeling off. After the above steps, the silver nanowire thin film pattern on the glass mask was transferred to the PE substrate by the graphene oxide layer to obtain a silver nanowire thin film gate pattern with a width and a spacing of 500 μm.

In summary, the silver nanowire film coated on the rigid substrate has a certain adhesion to the substrate, and the flexible substrate or micro-adhesive tape whose surface glue has not dried cannot transfer the silver nanowire conductive network from the glass substrate. In Examples 1 and 2, by virtue of the double-sided strong adhesion of graphene oxide to silver nanowires and flexible substrates, the silver nanowire films were completely transferred to the flexible substrates, even on the flexible substrates that were slightly sticky or the surface glue had not yet dried. It can also be completely transferred to form a flexible film with excellent conductivity.

In Example 1 and Example 2, the silver nanowire film covering the mask is coated with a graphene oxide layer, and the silver nanowires in the hollow area of the mask (ie, covering the graphene oxide layer) can be transferred to various flexible substrates. Further, in Example 1, the surface of the silver nanowire thin film pattern left on the glass substrate was covered with a graphene oxide layer again, and this part of the leftover silver nanowire thin film pattern was successfully transferred to the flexible substrate, which effectively improved the silver nanowires. The utilization efficiency of the wire film is improved and the preparation process of the silver nanowire flexible transparent conductive film is simplified. In Comparative Example 1 and Comparative Example 2, the graphene oxide layer was not coated, and the adhesion of the silver nanowire film to the micro-adhesive substrate was weak and could not be transferred to the flexible substrate.

Embodiments 3 and 4 utilize the characteristics of silver nanowires that, after being treated with ultraviolet ozone or plasma cleaned, the change in the surface structure characteristics leads to a significant weakening of the adhesion with graphene oxide and cannot be transferred through the adhesion of graphene oxide; The adhesion of the rigid substrate to graphene oxide after water treatment was enhanced, resulting in a decrease in the transferability of surface graphene oxide. The silver nanowire film is selectively cleaned by ultraviolet ozone or plasma through a mask, the mask is removed, and the graphene oxide layer is applied, and the mask can be covered (shielding ultraviolet ozone or plasma cleaning) in the area. The silver nanowires are transferred to various flexible substrates, and the above effects can be achieved by ultraviolet ozone or plasma cleaning for 1 to 2 minutes. Obviously, the method provided by the present invention can significantly reduce energy consumption and pollution compared with the processing time of tens of minutes or even several hours required by methods such as hydrophilic treatment of hydrophobic substrates or ultraviolet ozone etching of thin films. In Comparative Example 3, no ultraviolet ozone or plasma cleaning treatment was performed, so all the silver nanowire films had strong adhesion to graphene oxide, and the films were completely transferred to the flexible substrate.

In Example 5, the pattern structure of the silver nanowire thin film was first prepared on the glass substrate and the glass mask, and then transferred to the flexible substrate through the graphene oxide layer, respectively, to prepare two flexible thin film patterns, corresponding to the pattern of the mask coverage area respectively. And the pattern of the hollow area of the mask, the silver nanowire film is fully utilized, the pattern boundary is clear, and the light transmittance and conductivity are excellent. If only the silver nanowire pattern on the glass substrate needs to be obtained, the mask material can also use other materials with higher strength but stronger adhesion to the silver nanowires instead of glass.

In addition, in the above embodiments, a nitrogen gun is used to blow away excess solution (recycling), and only a very thin graphene oxide layer can be used to achieve selective adhesion and transfer, which can not only improve the light transmittance of the film , and save materials. Compared with the prior art, the preparation method of the flexible transparent conductive film provided by the present invention is simple and environmentally friendly, has no complicated procedures such as high temperature, high pressure, vacuum filtration, etc., does not require expensive equipment and a large amount of material consumption, and can realize metal nanowires. The complete transfer of film patterns from rigid substrates to various flexible substrates, including hydrophobic substrates, has good pattern accuracy and optoelectronic properties, and can fully utilize metal nanowire films.

The above-mentioned embodiments are only for illustrating the technical concept and characteristics of the present invention, and the purpose thereof is to enable those of ordinary skill in the art who are familiar with the technology to understand the content of the present invention and implement them accordingly, and cannot limit the protection scope of the present invention. . All equivalent transformations or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims (8)

1. A preparation method of a flexible transparent conductive film is characterized in that,

the method comprises the following steps:

s1: coating a metal nanowire film on a rigid substrate;

s2: covering a mask on the metal nanowire film;

S3A: selectively bonding the metal nanowire film of the mask hollowed-out region to the graphene oxide layer: s311: coating the graphene oxide dispersion liquid on the surface of the metal nanowire film covered with the mask, so that the metal nanowire film in the hollow area of the mask is combined with the graphene oxide layer; s312: removing the mask;

S4A: adhering the metal nanowire film combined with the graphene oxide layer to a flexible substrate with an adhesive surface and peeling the metal nanowire film from the rigid substrate to obtain a flexible transparent conductive film with a mask hollow area pattern;

or comprises the following steps:

s1: coating a metal nanowire film on a rigid substrate;

s2: covering a mask on the metal nanowire film;

S3B: selectively bonding the metal nanowire thin film of the mask-covered region to the graphene oxide layer: s321: carrying out ultraviolet ozone treatment or plasma cleaning treatment on the metal nanowire film covered with the mask to enable the metal nanowire film in the mask hollow area to lose the adhesion force with the graphene oxide; s322: removing the mask; s323: coating the graphene oxide dispersion liquid on the surface of the silver nanowire film, so that the metal nanowire film in the mask coverage area is combined with the graphene oxide layer;

S4B: using a flexible substrate whose surface can be adhered, adhering the metal nanowire film combined with the graphene oxide layer and peeling the metal nanowire film from the rigid substrate to obtain the flexible transparent conductive film with the mask coverage area pattern.

2. The method for preparing a flexible transparent conductive film according to claim 1, wherein the step S4A is performed by using a flexible substrate with an attachable surface, attaching the metal nanowire film with the graphene oxide layer thereon and peeling the metal nanowire film from the rigid substrate to obtain the flexible transparent conductive film, and further comprises:

S5A: coating the graphene oxide dispersion liquid on the surface of the metal nanowire film left on the rigid substrate;

S6A: using a flexible substrate whose surface can be adhered, adhering the metal nanowire film combined with the graphene oxide layer and peeling the metal nanowire film from the rigid substrate to obtain the flexible transparent conductive film with the mask coverage area pattern.

3. The method for preparing a flexible transparent conductive film according to any one of claims 1 to 2, wherein the rigid substrate is selected from a glass or silicon wafer.

4. The method for preparing a flexible transparent conductive film according to any one of claims 1 to 2, wherein the metal nanowire film is a silver nanowire film.

5. The method for preparing a flexible transparent conductive film according to claim 4, wherein the silver nanowires have a diameter of 20 to 100nm and a length of 10 to 100 μm.

6. The method for preparing a flexible transparent conductive film according to any one of claims 1 to 2, wherein the concentration of the graphene oxide dispersion liquid is 0.5-5 mg/ml; the graphene oxide dispersion liquid is coated on the surface of the metal nanowire film in a dropping, dip, spraying or spin coating mode.

7. The method for preparing a flexible transparent conductive film according to any one of claims 1 to 2, wherein the flexible substrate with the surface capable of adhering is a flexible substrate with a surface coated with glue or a transparent adhesive tape.

8. The method of preparing a flexible transparent conductive film according to claim 7, wherein the flexible substrate is selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate, polyethylene, polyimide, polydimethylsiloxane, polyvinyl alcohol, polyurethane, and polymethylmethacrylate.

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