A method for preparing silver nanowire conductive film

Abstract

The present invention is a divisional application with application number 2019105285912, and discloses a method for preparing a silver nanowire conductive film. The additive is made of the following raw materials: distilled water, ethylene glycol, a dispersant, a leveling agent, a thickener, a surfactant and a defoaming agent are mixed in a weight ratio of 6.5-7.5:5.5-6.5:0.2-0.8:0.1-0.5:0.1-0.3:0.002-0.008:0.01-0.03, and the optical properties, electrical properties and mechanical stability of the conductive film are guaranteed by a specific ratio and raw materials. The silver nanowire conductive film prepared by the present invention can still maintain good square resistance and transmittance after multiple bendings, and has high stability. The present invention prepares a flexible transparent conductive film by inkjet printing technology, and the preparation method is simple and the preparation cost is low, which solves the problem that it is difficult to realize large-scale production of flexible transparent conductive films, and is conducive to promoting the large-scale application of silver nanowire conductive films in flexible devices such as solar cells and organic light-emitting diodes.

Description

[0001] This application is a divisional application with application number 2019105285912, filing date June 18, 2019, and titled "A method for preparing a silver nanowire conductive film and its additives." Technical Field

[0002] The invention relates to the technical field of conductive films, in particular to a method for preparing a silver nanowire conductive film. The invention also relates to an additive for the silver nanowire conductive film. Background Art

[0003] As the next generation of optoelectronic devices tend towards mobile and wearable devices, flexible electronics have become crucial in the development of efficient and stretchable optoelectronic devices such as organic light-emitting diodes, touch screens, e-readers, e-paper, and organic photovoltaics. The basic component of flexible electronics is transparent conductive film, which is a thin film material with high transmittance and excellent conductivity in the visible light range.

[0004] At present, indium tin oxide is the main material used to produce transparent conductive films, but indium tin oxide is prone to cracks under repeated bending and is fragile. Limited reserves and high-cost production technology of indium tin oxide films make it difficult to develop indium tin oxide conductive films on a large scale and in large quantities. Therefore, several emerging materials such as graphene, carbon nanotubes and conductive polymers are regarded as the next generation of transparent conductive film materials to replace indium tin oxide, but these materials have certain limitations: graphene has good optoelectronic and mechanical properties, but the mainstream preparation method of graphene film - chemical vapor deposition method has high requirements on the substrate, high preparation cost and difficult to transfer the prepared film, so it is difficult to promote and apply it in flexible devices; carbon nanotubes have good mechanical properties, but their transmittance and square resistance are poor; conductive polymers (such as PEDOT:PSS) are relatively cheaper, but they will degrade over time and are greatly affected by the environment, resulting in unstable device performance. Summary of the invention

[0005] In order to overcome the deficiencies of the prior art, the present invention provides a method for preparing a silver nanowire conductive film and an additive thereof.

[0006] The technical solution adopted by the present invention to solve its technical problem is:

[0007] An additive for preparing a silver nanowire conductive film is prepared from the following raw materials: distilled water, ethylene glycol, a dispersant, a leveling agent, a thickener, a surfactant and a defoamer are mixed in a weight ratio of 6.5-7.5:5.5-6.5:0.2-0.8:0.1-0.5:0.1-0.3:0.002-0.008:0.01-0.03.

[0008] The distilled water, ethylene glycol, dispersant, leveling agent, thickener, surfactant and defoamer are mixed in a weight ratio of 7:6:0.5:0.3:0.2:0.005:0.02.

[0009] The dispersant is prepared by mixing a high molecular block polymer containing multiple pigment anchoring groups and a surfactant solution.

[0010] The leveling agent is polyether modified dimethylsiloxane.

[0011] The thickener is polyether polyurethane.

[0012] The surfactant is a nonionic fluorocarbon surfactant.

[0013] The defoamer is a nonionic polyglycol ether defoamer.

[0014] A method for preparing a silver nanowire conductive film, comprising the following steps:

[0015] 1) preparing silver nanowires by a liquid phase polyol method, wherein the silver nanowires have a diameter of 25-35 nm and a length of 25-30 μm, and preparing the silver nanowires into a 50 mg / mL silver nanowire-ethanol solution by anhydrous ethanol;

[0016] 2) placing the silver nanowire-ethanol solution in an ultrasonic instrument to break the silver nanowire into short silver nanowires with a length of 2-3 μm. Silver nanowires that are too long cannot pass through the nozzle of the ink cartridge and may also cause the nozzle to be blocked. Therefore, the present invention induces the silver nanowires to break by ultrasound so that they can be smoothly ejected from the nozzle;

[0017] 3) Prepare the above additives in proportion and perform ultrasonic treatment for 2 hours to mix the components evenly;

[0018] 4) mixing the silver nanowire-ethanol solution subjected to the ultrasonic treatment in step 2), the additive obtained in step 3) and distilled water in a volume ratio of 4:1:4, then evaporating to remove the volatile solvent, and then mixing the evaporated mixture with distilled water in a volume ratio of 3:50 to obtain a silver nanowire conductive ink;

[0019] 5) Preparing a silver nanowire transparent conductive film by inkjet printing, placing a flexible transparent substrate in a microelectronic printer, placing the silver nanowire conductive ink prepared in step 4) in an ink cartridge, and after the silver nanowire conductive ink is printed on the flexible transparent substrate, setting the heating stage temperature to 80° C. and drying for 5 minutes to obtain the silver nanowire transparent conductive film.

[0020] The specific setting parameters of the microelectronic printer in step 5) are: the number of nozzles is 4, the nozzle temperature is 35°C, the printing voltage is 20V, the printing speed is 150μm / s, the printing ink drop spacing is 20μm, and the printing height (from the substrate surface) is 0.5-1.0mm.

[0021] The thickness of the silver nanowire conductive film is 350-400nm.

[0022] The beneficial effects of the present invention are: applying inkjet printing technology to the production of flexible transparent conductive films, the preparation method is simple, the preparation cost is low, and the problem that the flexible transparent conductive film is difficult to achieve large-scale production is solved. At the same time, the present invention also discloses a ratio of additives, which ensures the optical properties, electrical properties and mechanical stability of the conductive film with a specific ratio and raw materials. The silver nanowire conductive film prepared by the present invention can still maintain good square resistance and transmittance after multiple bendings, and has high stability, which is conducive to promoting the large-scale application of silver nanowire conductive films in flexible devices such as solar cells and organic light-emitting diodes. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0024] Figure 1 is a SEM image of Example 1 after bending once;

[0025] Figure 2 is the SEM image of Example 1 after bending 10 times;

[0026] Figure 3 is the SEM image of Example 1 after bending 20 times;

[0027] Figure 4 is the SEM image of Example 1 after bending 30 times;

[0028] Figure 5 is the SEM image of Example 1 after being bent 40 times;

[0029] Figure 6 is a curve diagram of light transmittance and square resistance variation at different bending times of Example 1;

[0030] Figure 7 is a physical picture of the silver nanowire conductive ink of the present invention;

[0031] Figure 8 This is a physical picture of the silver nanowire conductive film prepared by the present invention;

[0032] Fig. 9 This is a physical picture of the silver nanowire conductive film prepared by the present invention in a bent state. DETAILED DESCRIPTION

[0033] Embodiment 1:

[0034] An additive for preparing a silver nanowire conductive film is made of raw materials in the following proportions: distilled water, ethylene glycol, a dispersant (Tuyile® Disper-CED of Tianjin Hepfill New Materials Co., Ltd.), a leveling agent (Tuyile® SIF-720 of Tianjin Hepfill New Materials Co., Ltd.), a thickener (WZ-907 of Guangzhou Zhongwan New Materials Co., Ltd.), a surfactant (Capstone FS-3100 of DuPont Company, USA), and a defoaming agent (DF105 of Dow Chemical Company, USA), which are mixed in a weight ratio of 7:6:0.5:0.3:0.2:0.005:0.02.

[0035] A method for preparing a silver nanowire conductive film, comprising the following steps:

[0036] 1) preparing silver nanowires by a liquid phase polyol method, wherein the diameter of the silver nanowires is 25-35 nm and the length is 25-30 μm, and preparing the silver nanowires into a 50 mg / mL silver nanowire-ethanol solution by anhydrous ethanol,

[0037] The specific operation is as follows: 0.064g hexahydrate and ferric chloride are weighed and dissolved in 65mL ethylene glycol solution and stirred evenly, and then 1.299g PVP is added and stirred thoroughly to obtain liquid A; 0.6695g silver nitrate is weighed and dissolved in 40mL ethylene glycol solution and stirred evenly to obtain liquid B; liquid A and liquid B are poured into a reactor, reacted at 160°C for 3 hours, cooled to room temperature after the reaction, and then centrifuged to obtain a precipitate, which is silver nanowires. The silver nanowires are centrifugally washed twice with acetone and anhydrous ethanol, and finally the silver nanowires are configured into a 50mg / mL silver nanowire-ethanol solution with anhydrous ethanol;

[0038] 2) placing the silver nanowire-ethanol solution in an ultrasonic instrument to break the silver nanowires into short silver nanowires with a length of 2-3 μm;

[0039] 3) Additives were prepared according to the above ratios and ultrasonically treated for 2 h to ensure uniform mixing of the components;

[0040] 4) mixing the silver nanowire-ethanol solution subjected to the ultrasonic treatment in step 2), the additive obtained in step 3) and distilled water in a volume ratio of 4:1:4, then evaporating to remove the volatile solvent, and then mixing the evaporated mixture with distilled water in a volume ratio of 3:50 to obtain a silver nanowire conductive ink;

[0041] 5) Preparing a silver nanowire transparent conductive film by inkjet printing, placing a flexible transparent substrate in a microelectronic printer, placing the silver nanowire conductive ink prepared in step 4) in an ink cartridge, and after printing the silver nanowire conductive ink on the flexible transparent substrate, setting the heating stage temperature to 80° C. and drying for 5 minutes to obtain a silver nanowire transparent conductive film with a thickness of 400 nm.

[0042] Reference Figures 1 to 9 , the present embodiment was subjected to a bending test and a square resistance and transmittance change curve was plotted. The transmittance of the present embodiment was 80-82%, the square resistance was 15-25Ω / sq, and after 35 bends, the square resistance increased to about 97Ω / sq ​​and then basically stabilized, while the transmittance remained at about 82%.

[0043] Embodiment 2:

[0044] An additive for preparing a silver nanowire conductive film is made of raw materials in the following proportions: ethylene glycol, a dispersant (Tuyile® Disper-CED of Tianjin Hepfill New Materials Co., Ltd.), a leveling agent (Tuyile® SIF-720 of Tianjin Hepfill New Materials Co., Ltd.), a thickener (WZ-907 of Guangzhou Zhongwan New Materials Co., Ltd.), a surfactant (Capstone FS-3100 of DuPont Company, USA), and a defoaming agent (DF105 of Dow Chemical Company, USA) are mixed in a weight ratio of 6.5:5.5:0.2:0.1:0.1:0.002:0.01.

[0045] A method for preparing a silver nanowire conductive film is the same as that in Example 1, and the thickness of the silver nanowire conductive film is 350 nm.

[0046] Embodiment 3:

[0047] An additive for preparing a silver nanowire conductive film is made of raw materials in the following proportions: ethylene glycol, a dispersant (Tuyile® Disper-CED of Tianjin Hepfill New Materials Co., Ltd.), a leveling agent (Tuyile® SIF-720 of Tianjin Hepfill New Materials Co., Ltd.), a thickener (WZ-907 of Guangzhou Zhongwan New Materials Co., Ltd.), a surfactant (Capstone FS-3100 of DuPont Company, USA), and a defoaming agent (DF105 of Dow Chemical Company, USA) are mixed in a weight ratio of 7.5: 6.5: 0.8: 0.5: 0.3: 0.008: 0.03.

[0048] A method for preparing a silver nanowire conductive film is the same as that in Example 1, and the thickness of the silver nanowire conductive film is 375 nm.

[0049] The above implementation modes cannot limit the protection scope of the present invention. The equivalent modifications and changes made by those skilled in the art without departing from the overall concept of the present invention are still within the scope of the present invention.

Claims

1. A method for preparing a silver nanowire conductive film, characterized in that Here are the steps: 1) preparing silver nanowires by a liquid phase polyol method, wherein the silver nanowires have a diameter of 25-35 nm and a length of 25-30 μm, and preparing the silver nanowires into a 50 mg / mL silver nanowire-ethanol solution by anhydrous ethanol; 2) placing the silver nanowire-ethanol solution in an ultrasonic instrument to break the silver nanowires into short silver nanowires with a length of 2-3 μm; 3) Add the additives in proportion and perform ultrasonic treatment for 2 hours to mix the components evenly; The additive is made of the following raw materials: distilled water, ethylene glycol, dispersant, leveling agent, thickener, non-ionic fluorocarbon surfactant, and defoamer are mixed in a weight ratio of 7:6:0.5:0.3:0.2:0.005:0.02; the leveling agent is polyether-modified dimethylsiloxane; the thickener is polyether polyurethane; the dispersant is made by mixing a high molecular block polymer containing a variety of pigment anchoring groups and a surfactant solution; the defoamer is a non-ionic polyglycol ether defoamer; 4) mixing the silver nanowire-ethanol solution subjected to the ultrasonic treatment in step 2), the additive obtained in step 3) and distilled water in a volume ratio of 4:1:4, then evaporating to remove the volatile solvent, and then mixing the evaporated mixture with distilled water in a volume ratio of 3:50 to obtain a silver nanowire conductive ink; 5) Preparing a silver nanowire transparent conductive film by inkjet printing, placing a flexible transparent substrate in a microelectronic printer, placing the silver nanowire conductive ink prepared in step 4) in an ink cartridge, and after the silver nanowire conductive ink is printed on the flexible transparent substrate, setting the heating stage temperature to 80° C. and drying for 5 minutes to obtain the silver nanowire transparent conductive film.

2. The method for preparing the silver nanowire conductive film according to claim 1, characterized in that The specific setting parameters of the microelectronic printer in step 5) are: the number of nozzles is 4, the nozzle temperature is 35° C., the printing voltage is 20 V, the printing speed is 150 μm / s, the printing ink drop spacing is 20 μm, and the printing height from the substrate surface is 0.5-1.0 mm.

3. The method for preparing the silver nanowire conductive film according to claim 1, characterized in that The thickness of the silver nanowire conductive film is 350-400nm.

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