A method for preparing silver nanowire transparent conductive film using electrophoresis technology

Abstract

The present invention discloses a method for preparing a silver nanowire transparent conductive film using electrophoresis technology, comprising the following steps: Step 1: preparing a silver nanowire suspension; Step 2: treating the silver nanowire suspension obtained in Step 1 using an electrophoretic method to uniformly deposit the silver nanowires on an anode to form a silver nanowire film; Step 3: placing the anode obtained in Step 2 on a transparent substrate and performing hot rolling, and then peeling off the anode after hot rolling to obtain the silver nanowire transparent conductive film. In the present invention, the electrophoretic method can be used to control the sheet resistance and light transmittance of the silver nanowire transparent conductive film, and the hot rolling can significantly enhance the adhesion of the silver nanowire film and reduce its surface roughness.

Description

Technical Field

[0001] The present invention relates to the field of methods for preparing silver nanowire transparent conductive films, and in particular to a method for preparing silver nanowire transparent conductive films by utilizing electrophoresis technology. Background Art

[0002] Transparent conductive films are widely used in touch screens, liquid crystal displays, solar cells, and organic light-emitting diodes. Among them, indium tin oxide (ITO) has excellent light transmittance and conductivity, and dominates the market. However, shortcomings such as indium scarcity, high processing costs, and high brittleness limit the practical application of ITO in next-generation flexible optoelectronic devices. With the continuous innovation of technology, a large number of new transparent conductive materials have come into view, such as carbon nanotubes, graphene, conductive polymers, and metal nanowires. Among them, silver nanowires are considered the best candidate to replace ITO due to their high flexibility, excellent optoelectronic properties, and simple preparation process.

[0003] Currently reported methods for preparing silver nanowire transparent conductive films mainly include spin coating, spray coating, vacuum filtration, and Meyer rod coating. While spin coating is simple to operate, it is limited to the size of the substrate, resulting in weak adhesion between the resulting film and the substrate, and easily leading to waste of silver nanowires. The spray coating method produces films with poor uniformity and repeatability. The vacuum filtration method can produce relatively uniform and dense films, but its complex apparatus and cumbersome steps hinder its industrialization. The Meyer rod coating method suffers from the difficulty of precisely controlling the film thickness, which easily leads to waste of silver nanowires. Therefore, existing methods for preparing silver nanowire transparent conductive films suffer from the problems of difficult-to-control thickness and density of the silver nanowire films and poor adhesion.

[0004] Compared to these methods, electrophoresis offers advantages such as simple equipment, low cost, excellent film uniformity, high silver nanowire utilization, and compatibility with roll-to-roll technology, making it suitable for large-scale production. Furthermore, the thickness and properties of the deposited film can be controlled simply by adjusting the electrophoresis time and voltage. Therefore, developing a method for preparing silver nanowire transparent conductive films using electrophoresis is of great significance. Summary of the Invention

[0005] The present invention provides a method for preparing a silver nanowire transparent conductive film using electrophoresis technology to solve the problems of difficult to control thickness and density of the silver nanowire film and poor adhesion in the prior art preparation method of the silver nanowire transparent conductive film.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for preparing a silver nanowire transparent conductive film using electrophoresis technology comprises the following steps:

[0008] Step 1, preparing a silver nanowire suspension;

[0009] Step 2: electrophoresis is used to treat the silver nanowire suspension obtained in step 1, so that the silver nanowires are uniformly deposited on the anode to form a silver nanowire film. The voltage during the electrophoresis treatment is a constant DC voltage of 3 to 10 V, and the electrophoresis time is 2 to 10 minutes.

[0010] Step 3: Place the anode obtained in step 2 on a transparent substrate to form a stack, and adhere the silver nanowire film to the transparent substrate, then perform hot rolling on the stack. After hot rolling, peel off the anode in the stack to complete the transfer of the silver nanowire film to the transparent substrate, and obtain a silver nanowire transparent conductive film.

[0011] Furthermore, the concentration of the silver nanowire suspension prepared in step 1 is 0.1-0.5 mg / mL.

[0012] Furthermore, in step 1, the silver nanowires are firstly centrifugally washed, and then the silver nanowires are dissolved in a solvent to obtain the silver nanowire suspension.

[0013] Furthermore, in step 2, the anode used in the electrophoresis treatment is ITO / PET and the cathode is copper foil.

[0014] Furthermore, during the electrophoresis treatment in step 2, the distance between the anode and the cathode is 10 to 50 mm.

[0015] Furthermore, in step 2, the electrophoresis voltage was controlled to be maintained at a constant DC voltage of 5 V and the electrophoresis time was maintained at 5 min, thereby forming a 41.6 nm thick and 50 μg / cm 2 Silver nanowire film;

[0016] The electrophoresis voltage was controlled to maintain a constant DC voltage of 10 V and the electrophoresis time was maintained at 5 min, thereby forming a 65.0 nm thick and 78 μg / cm density layer on the anode. 2 Silver nanowire film;

[0017] The electrophoresis voltage was kept at a constant DC voltage of 5 V and the electrophoresis time was kept at 10 min, thereby forming a 109.8 nm thick and 132 μg / cm-3 layer on the anode. 2 silver nanowire film.

[0018] Furthermore, the transparent substrate in step 3 is a PVB / PET transparent substrate.

[0019] Furthermore, in step 3, the speed of the hot roller pressing is 7-9 mm / s, and the temperature of the hot roller pressing is 70-100°C.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] (1) In the present invention, a silver nanowire film is deposited on an anode by electrophoresis, and the thickness and density of the silver nanowire film are controlled by adjusting the electrophoresis parameters, thereby regulating the surface resistance and light transmittance of the silver nanowire transparent conductive film;

[0022] (2) The present invention can significantly enhance the adhesion of the silver nanowire film and reduce its surface roughness during the imprint transfer process by hot roller pressing;

[0023] (3) The silver nanowire transparent conductive film prepared by the present invention has a surface resistance difference coefficient of only 7.85%, 7.97%, 8.95%, 11.42% and 11.83% when the surface resistance is 10.5 Ω / sq, 34.9 Ω / sq, 69.5 Ω / sq, 144.8 Ω / sq and 246.4 Ω / sq, respectively, showing excellent conductive uniformity;

[0024] (4) The silver nanowire suspension raw material used in the present invention can be reused without causing waste, thereby having the advantages of high silver nanowire utilization rate, simple process, compatibility with roll-to-roll technology, and easy large-scale production. DETAILED DESCRIPTION

[0025] The present invention is further described below with reference to the embodiments.

[0026] This embodiment discloses a method for preparing a silver nanowire transparent conductive film using electrophoresis technology, comprising the following steps:

[0027] Step 1: Prepare a silver nanowire suspension. The process is as follows:

[0028] The silver nanowires were evenly dispersed in ultrapure water and centrifuged for washing. The centrifugation was repeated three times to ensure that the silver nanowires were fully washed. After centrifugation, the supernatant was removed to obtain a silver nanowire precipitate.

[0029] The silver nanowire precipitate after centrifugal washing and the solvent are uniformly mixed and shaken at 50-200 rpm for 0.2-1 h to obtain a silver nanowire suspension.

[0030] In this embodiment, ethanol is used as the solvent, and the concentration of the final silver nanowire suspension is 0.1-0.5 mg / mL.

[0031] Step 2: electrophoresis is used to treat the silver nanowire suspension obtained in step 1, so that the silver nanowires are uniformly deposited on the anode to form a silver nanowire film. The process is as follows:

[0032] Connect the anode and cathode to the positive and negative terminals of a DC power supply, respectively. Immerse the anode and cathode in the silver nanowire suspension prepared in step 1, parallel to each other and spaced apart. Apply a constant DC voltage through the DC power supply. Over time, the silver nanowires uniformly deposit on the anode to form a silver nanowire film.

[0033] In this embodiment, in order to control the thickness and density of the silver nanowire film, the electrophoresis voltage is a constant DC voltage of 3 to 10 V, the electrophoresis time is 2 to 10 minutes, and the electrophoresis treatment is performed at room temperature.

[0034] The electrophoresis voltage was controlled to be a constant DC voltage of 5 V and the electrophoresis time was maintained at 5 min, thereby forming a 41.6 nm thick and 50 μg / cm density layer on the anode. 2 Silver nanowire film;

[0035] The electrophoresis voltage was controlled to maintain a constant DC voltage of 10 V and the electrophoresis time was maintained at 5 min, thereby forming a 65.0 nm thick and 78 μg / cm density layer on the anode. 2 Silver nanowire film;

[0036] The electrophoresis voltage was kept at a constant DC voltage of 5 V and the electrophoresis time was kept at 10 min, thereby forming a 109.8 nm thick and 132 μg / cm-3 layer on the anode. 2 silver nanowire film.

[0037] In this embodiment, in order to improve the conductivity and surface smoothness of the silver nanowire film, the anode is ITO / PET and the cathode is copper foil during electrophoresis. The anode is obtained by sputtering a transparent indium tin oxide (ITO) conductive film on a polyethylene terephthalate (PET) substrate material using magnetron sputtering technology. The distance between the anode and the cathode is 10 to 50 mm.

[0038] Finally, the anode with the silver nanowire film deposited on the surface is slowly taken out from the silver nanowire suspension and dried naturally in a sealed environment.

[0039] Step 3: Place the anode obtained in step 2 on a transparent substrate to form a stack, and adhere the silver nanowire film to the transparent substrate. Then, hot roll-press the stack. After hot rolling, the anode in the stack is naturally peeled off, completing the transfer of the silver nanowire film to the transparent substrate to obtain a silver nanowire transparent conductive film.

[0040] In this embodiment, the transparent substrate is a polyvinyl butyral (PVB) / PET transparent substrate. The preparation process of the PVB / PET transparent substrate is as follows:

[0041] PVB powder is slowly added to anhydrous ethanol and stirred for 6–12 hours until the PVB powder is completely dissolved, creating a 5–20 wt% PVB solution. A piece of PET is then cut and ultrasonically cleaned in acetone, isopropyl alcohol, anhydrous ethanol, and ultrapure water for 5 minutes each. The surface is then completely dried by purging with nitrogen. Finally, the treated PET is vacuum-coated on an automatic film coating machine, and the PVB solution is applied to the tip of a Meyer rod at a rate of 50 mm / s. After drying, a uniform and clean PVB / PET transparent substrate is obtained.

[0042] In this embodiment, in order to prevent the solvent from volatilizing too quickly during PVB coating, the prepared PVB / PET transparent substrate is also dried in a vacuum drying oven at a drying temperature of 60-80° C. for 0.5-2 h.

[0043] In this embodiment, a hot roller press is used for hot roller pressing. The roller press speed is set to 7-9 mm / s (preferably 8 mm / s), the hot roller pressing temperature is 70-100°C (preferably 80°C), and the gap between the two rollers of the roller press is in the range of 150-250 μm (preferably 200 μm). During hot roller pressing, the anode with the silver nanowire film deposited on it is placed on a dried PVB / PET transparent substrate, and the silver nanowire film and the PVB layer of the PVB / PET transparent substrate are kept in contact with each other. The hot roller pressing is then carried out using the roller press.

[0044] The preferred embodiments of the present invention are described in detail above. The embodiments described in the present invention are merely descriptions of the preferred embodiments of the present invention and are not intended to limit the concept and scope of the present invention. The various specific technical features described in the above specific embodiments can be combined in any suitable manner unless there is any contradiction. Such combinations, as long as they do not violate the concept of the present invention, should also be regarded as the contents disclosed in this disclosure. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0045] The present invention is not limited to the specific details of the above-mentioned embodiments. Within the scope of the technical concept of the present invention and without departing from the design concept of the present invention, various modifications and improvements made to the technical solution of the present invention by those skilled in the art should fall within the scope of protection of the present invention. The technical contents for which protection is sought in the present invention have been fully recorded in the claims.

Claims

1. A method for preparing a silver nanowire transparent conductive film using electrophoresis technology, characterized in that: The following steps are involved: Step 1, preparing a silver nanowire suspension; Step 2: treating the silver nanowire suspension obtained in step 1 by electrophoresis to uniformly deposit the silver nanowires on the anode to form a silver nanowire film. The voltage during the electrophoresis treatment is a constant DC voltage of 3 to 10 V, and the electrophoresis time is 2 to 10 minutes. Step 3: placing the anode obtained in step 2 on a transparent substrate to form a laminate, and laminating the silver nanowire film to the transparent substrate, and then hot rolling the laminate. After hot rolling, the anode in the laminate is peeled off to complete the transfer of the silver nanowire film to the transparent substrate, thereby obtaining a silver nanowire transparent conductive film; The concentration of the silver nanowire suspension prepared in step 1 is 0.1-0.5 mg / mL; During the electrophoresis treatment in step 2, the distance between the anode and cathode is 10 to 50 mm; In step 2, the electrophoresis voltage was controlled to be maintained at a constant DC voltage of 5 V, and the electrophoresis time was maintained at 5 min, thereby forming a silver nanowire film with a thickness of 41.6 nm and a density of 50 μg / cm2 on the anode; the electrophoresis voltage was controlled to be maintained at a constant DC voltage of 10 V, and the electrophoresis time was maintained at 5 min, thereby forming a silver nanowire film with a thickness of 65.0 nm and a density of 78 μg / cm2 on the anode; the electrophoresis voltage was controlled to be maintained at a constant DC voltage of 5 V, and the electrophoresis time was maintained at 10 min, thereby forming a silver nanowire film with a thickness of 109.8 nm and a density of 132 μg / cm2 on the anode; The transparent substrate in step 3 is a PVB / PET transparent substrate; In step 3, the speed of the hot roller pressing is 7-9 mm / s, and the temperature of the hot roller pressing is 70-100°C.

2. The method for preparing a silver nanowire transparent conductive film using electrophoresis technology according to claim 1, characterized in that: In step 1, the silver nanowires are firstly centrifugally washed, and then the silver nanowires are dissolved in a solvent to obtain the silver nanowire suspension.

3. The method for preparing a silver nanowire transparent conductive film using electrophoresis technology according to claim 1, characterized in that: In step 2, the anode used in the electrophoresis treatment is ITO / PET and the cathode is copper foil.